Treatment apparatus

A treatment apparatus comprises a treatment chamber for performing a treatment for a workpiece W, a loading chamber connected to the treatment chamber, for loading and unloading a holding member which contains the workpiece into and from the treatment chamber, and an input/output chamber for inputting and outputting the workpiece to and from the loading chamber. The input/output chamber includes a cassette accommodating vessel port which holds a cassette accommodating vessel. The vessel is filled with clean air or an inert gas, and is airtightly closed. A cassette receiving mechanism is disposed below the port and lowers only the cassette of the vessel so as to receive the cassette. Thus, when the cassette is input and output to and from the outside of the treatment apparatus, the workpiece contained within the cassette is not exposed to the atmosphere in a working region. Consequently, it is not necessary to improve the cleanliness level of the atmosphere in the working region. As a result, the construction cost of the clean room and the operation cost thereof can be reduced. A clean air blowing device is disposed below the port. The clean air blowing device blows a side flow of clean air. Thus, the atmosphere at a position below the port where air tends to stay is circulated. Thus, since the surface of the workpiece loaded in the treatment chamber is exposed to the side flow, particles and the like that adhere thereto are purged.

 

What is claimed is:

1. A treatment apparatus, comprising:

means defining a treatment chamber for performing a predetermined treatment for a workpiece contained in a holding member;

means defining a loading chamber having a transfer mechanism for loading and unloading the holding member containing the workpiece into and from said treatment chamber;

means defining an input/output chamber for transferring a cassette accommodating vessel accommodating a cassette and for inputting and outputting the workpiece contained in the cassette to and from said loading chamber;

means defining a cassette accommodating vessel port for connecting said input/output chamber and an outside thereof and for holding a cassette accommodating vessel conveyed from the outside;

receive means disposed in said input/output chamber, for receiving the cassette accommodating vessel held on said cassette accommodating vessel port to an inside of said input/output chamber;

a cassette extracting stage disposed between said input/output chamber and said loading chamber, for extracting the cassette from the cassette accommodating vessel; and

vessel transfer means disposed in said input/output chamber and for transferring the cassette accommodating vessel received by said receive means to said cassette extracting stage.

2. The treatment apparatus as set forth in claim 1, wherein

said input/output chamber includes a carrier stock stage for temporarily stocking the cassette.

3. The treatment apparatus as set forth in claim 1, wherein

said loading chamber is a load lock chamber airtightly partitioned from said input/output chamber.

4. The treatment apparatus as set forth in claim 3, wherein

said cassette extracting stage has a casing opening to said loading chamber, and includes a ceiling holding portion having a cassette inlet hole, for holding the cassette accommodating vessel, said cassette inlet hole being airtightly closed by the cassette accommodating vessel.

5. The treatment apparatus as set forth in claim 4, wherein

said ceiling holding portion has a vessel holder for securing the cassette accommodating vessel at a predetermined position on said ceiling holding portion.

6. The treatment apparatus as set forth in claim 4, wherein

a cassette extracting mechanism is provided for extracting the cassette from the cassette accommodating vessel held at said ceiling holding portion.

7. The treatment apparatus as set forth in claim 6, wherein

said cassette extracting mechanism includes a vessel bottom portion holding table for airtightly closing said cassette inlet hole, for holding the cassette accommodating vessel, and for raising and lowering the cassette.

8. The treatment apparatus as set forth in claim 7, wherein

the cassette accommodating vessel includes a main body and a bottom portion detachably mounted on the main body through lock means, said vessel bottom portion holding table including release means for releasing the lock means so as to separate the bottom portion from the main body.

9. The treatment apparatus as set forth in claim 1, wherein

circulation of clean air is provided within said loading chamber, the atmospheric pressure in said loading chamber being higher than the atmospheric pressure in said input/output chamber.

10. The treatment apparatus as set forth in claim 9, wherein

said cassette extracting stage includes a ceiling holding portion having a cassette inlet hole, said ceiling holding portion being adapted to hold the cassette accommodating vessel.

11. The treatment apparatus as set forth in claim 10, wherein

said ceiling holding portion includes a vessel holder for securing the cassette accommodating vessel at a predetermined position on said ceiling holding portion.

12. The treatment apparatus as set forth in claim 11, wherein

a cassette extracting mechanism is provided for extracting the cassette from the cassette accommodating vessel held on said ceiling holding portion.

13. The treatment apparatus as set forth in claim 12, wherein

said cassette extracting mechanism includes a vessel bottom portion holding table for holding the cassette accommodating vessel, for raising and lowering the cassette.

14. The treatment apparatus as set forth in claim 13, wherein

the cassette accommodating vessel includes a main body and a bottom portion detachably mounted on the main body through lock means, said vessel bottom portion holding table including release means for releasing the lock means so as to separate the bottom portion from the main body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a treatment apparatus for performing a predetermined treatment for a workpiece such as a semiconductor wafer.

2. Description of the Related Art

In semiconductor fabrication processes, various treatment apparatuses that form an oxide film on a semiconductor wafer, which is a workpiece, form a thin film on a semiconductor wafer corresponding to heat CVD method, and form impurity regions with different concentrations on a semiconductor wafer corresponding to heat diffusion method have been used. In the following description, the semiconductor wafer may be referred to as simply a wafer.

In recent years, upright type heat treatment apparatuses have been widely used instead of conventional flat type heat treatment apparatuses. As an example of the upright type heat treatment apparatuses, a wafer boat (which serves as a holding member) that contains a large number of wafers is loaded into a nearly-cylindrical upright type treatment chamber (process tube). The inside of the process tube is heated in an atmosphere of a predetermined treatment gas so as to perform various treatments for the wafers.

In the conventional heat treatment apparatus of this type, a manifold is disposed below the process tube (that is made of quartz or the like). An exhaust pipe and a delivery pipe are disposed on the manifold so as to exhaust waste gas therefrom and to deliver clean gas thereto. A heater is disposed around the process tube so as to heat the inside thereof at a desired temperature.

The wafer boat, which contains a large number of wafers, is transferred from a loading chamber to the process tube by a boat elevator that constructs a transfer mechanism. At this point, a flange of the wafer boat is brought into contact with the manifold so as to airtightly close the inside of the process tube.

An input/output means is disposed in a transfer chamber adjacent to the loading chamber. The input/output means inputs and outputs the wafers accommodated in a wafer carrier to and from the wafer boat.

When the wafers are treated by the heat treatment apparatus, they are contained in the wafer boat in an atmosphere of an inert gas (such as nitrogen N.sub.2), namely an atmosphere of non-oxygen. The wafer boat is raised and loaded into the process tube by the boat elevator. Thereafter, the N.sub.2 gas is exhausted through the exhaust pipe. When the inside of the process tube becomes a vacuum of a predetermined level, a treatment gas is delivered into the process tube through the delivery pipe so as to perform a desired treatment. In the above-described conventional apparatus, a load lock chamber construction where the inside of the loading chamber is airtightly closed and air and gas are exhausted therefrom has been used. As another construction of the apparatuses, the inside of the loading chamber is always kept at the pressure of an atmosphere of clean air.

In the above-described upright type heat treatment apparatuses, when the wafer carrier is input and output to and from the transfer chamber, which accommodates the wafer carrier, a door disposed on the transfer chamber is opened and closed, respectively. The wafer carrier is transferred to the vacuum chamber by an automatic guided vehicle (AGV) or the operator in the condition that the wafers contained in the wafer carrier are exposed to clean air. In addition, the wafers that have been treated are output from the vacuum chamber in the condition that the wafers are exposed to the clean air.

Thus, the outside of the transfer chamber (namely the entire clean room in which the operator and the like work) should be kept at a cleanliness level equal to or close to the cleanliness level of the transfer chamber and the loading room (for example, class 1) so as to prevent particles from adhering to the wafers.

When the clean room is constructed, the construction cost of the clean room is proportional to the cleanliness level thereof. Thus, if the working regions for the wafer carrier, the operator, and the like were constructed with such a high cleanliness level, the construction cost would remarkably increase.

In addition, since the large clean room should be kept with the high cleanliness level, the running cost thereof will also increase.

SUMMARY OF THE INVENTION

The present invention is made from the above-described point of view. An object of the present invention is to provide a treatment apparatus having a cassette accommodating vessel such as SMIF (Standard Mechanical InterFace) pot so as to reduce the cleanliness level.

A first aspect of the present invention is a treatment apparatus, comprising a treatment chamber for performing a predetermined treatment for a workpiece contained in a holding member, a loading chamber having a transfer mechanism for loading and unloading the holding member containing the workpiece into and from the treatment chamber, an input/output chamber for transferring a cassette containing the workpiece and for inputting and outputting the workpiece contained in the cassette to and from the loading chamber, a cassette accommodating vessel port for connecting the input/output chamber and an outside thereof and for holding a cassette accommodating vessel conveyed from the outside, the cassette accommodating vessel being adapted to accommodate the cassette, a cassette receiving mechanism disposed in the input/output chamber for receiving the cassette from the cassette accommodating vessel held on the cassette accommodating vessel port to the inside the input/output chamber, and a clean air blowing means disposed in the input/output chamber, for blowing a side flow of clean air into the cassette transferred by the cassette receiving mechanism.

A second aspect of the present invention is a treatment apparatus, comprising a treatment chamber for performing a predetermined treatment for a workpiece contained in a holding member, a loading chamber having a transfer mechanism for loading and unloading the holding member containing the workpiece into and from the treatment chamber, an input/output chamber for transferring a cassette accommodating vessel accommodating a cassette and for inputting and outputting the workpiece contained in the cassette to and from the loading chamber, a cassette accommodating vessel port for connecting the input/output chamber and an outside thereof and for holding a cassette accommodating vessel conveyed from the outside, receive means disposed in the input/output chamber, for receiving the cassette accommodating vessel held on the cassette accommodating vessel port to the inside of the input/output chamber, a cassette extracting stage disposed between the input/output chamber and the loading chamber, for extracting the cassette from the cassette accommodating vessel, and vessel transfer means disposed in the input/output chamber, for transferring the cassette accommodating vessel received by the receive means to the cassette extracting stage.

A third aspect of the present invention is a treatment apparatus, comprising a treatment chamber for performing a predetermined treatment for a workpiece contained in a holding member, a loading chamber for loading and unloading the holding member containing the workpiece into and from the treatment chamber, a pass box for temporarily storing an accommodating vessel conveyed from the outside of the treatment apparatus, the accommodating vessel including a main body and a lid, and airtightly contain the workpiece, a gas supply/exhaust means for substituting the atmosphere in the pass box with an inert gas, a lid removing mechanism disposed in the pass box and for removing the lid from the main body of the accommodating vessel, and transferring means for transferring the workpiece contained in the accommodating vessel to the loading chamber.

A fourth aspect of the present invention is a treatment apparatus, comprising a treatment chamber for performing a predetermined treatment for a workpiece contained in a holding member, a loading chamber communicating with the outside of the treatment chamber through an inlet/outlet opening, for loading and unloading the holding member into and from the treatment chamber, a box holding mechanism holding a accommodating vessel having a main body and a lid from the outside of the loading chamber so as to close the inlet/outlet opening with the lid, the accommodating vessel airtightly containing the workpiece a lid removing door mechanism for normally closing the inlet/outlet opening from the inside of the loading chamber and for removing the lid of the accommodating vessel held by the box holding mechanism so as to make the inside of the accommodating vessel communicate with the inside of the loading chamber, and a transfer means for transferring the workpiece contained in the accommodating vessel held at the inlet/outlet opening to the loading chamber.

According to the first aspect of the present invention, when the workpieces are input and output to and from the input/output chamber, the cassette accommodating vessel, which is airtightly sealed from the outer atmosphere, is placed in the cassette accommodating vessel port. The cassette containing the workpieces is accommodated in the cassette accommodating vessel. The cassette accommodating vessel placed at the port is received to the input/output chamber by the cassette receiving mechanism. When the cassette is transferred to the input/output chamber, the clean air blowing means disposed on a side portion thereof forces a side flow of clean air into the workpieces contained in the cassette, thereby purging particles that adhere to the workpieces and the atmosphere that stays below the port. Consequently, it is not necessary to remarkably improve the cleanliness level of the working region where the cassette is transferred between apparatuses and the operator works. As a result, the construction cost of the clean room can be reduced.

According to the second aspect of the present invention, when the workpieces are input and output to and from the input/output chamber, the cassette accommodating vessel that is airtightly sealed from the outer atmosphere is placed at the cassette accommodating vessel port in the input/output chamber. The accommodating vessel placed at the port is received to the apparatus by the receiving means. The accommodating vessel is transferred to the cassette extracting stage by the vessel transfer means. The cassette, which contains the workpieces, is extracted from the cassette accommodating vessel. The cassette is transferred to the treatment chamber through the loading chamber. After the workpieces have been treated, the treated workpieces are contained in the cassette. The cassette is accommodated in the cassette accommodating vessel. The cassette accommodating vessel, which is airtightly sealed from the outer atmosphere is conveyed from the cassette accommodating vessel port to the outside of the treatment apparatus. Thus, since the workpieces are not exposed to the atmosphere in the working region, where the operator works, it is not necessary to remarkably improve the cleanliness level of the working region. In addition, it is not necessary to prepare an area for an empty cassette accommodating vessel.

According to the third aspect of the present invention, when the accommodating vessel is transferred from the outside to the pass box, it is temporarily exposed to the atmosphere. However, inert gas is supplied to the pass box by the gas supply/exhaust means, thereby purging air and impurities that adhere to the outer surface of the accommodating vessel. Since the capacity of the pass box can be small, with a relatively small amount of gas supplied from the gas supply/exhaust means, air can be quickly substituted with inert gas having a high purity. In the atmosphere of inert gas, the lid of the accommodating vessel is opened by the lid removing mechanism. The accommodating vessel, which contains the workpieces, is transferred to the treatment chamber of the treatment apparatus main body, which is filled with the atmosphere of inert gas. In the treatment chamber, a predetermined treatment operation is preformed. Thus, the workpieces can be input and output to and from the treatment apparatus in the atmosphere of inert gas without being exposed to air. Consequently, air (O.sub.2), gas impurities, and particle impurities can be easily and securely prevented from adhering to the workpieces and from entering the treatment apparatus.

According to the fourth aspect of the present invention, the accommodating vessel that contains the workpieces in the atmosphere of inert gas is airtightly connected to the workpiece input/output opening of the loading chamber by the box holding mechanism. In this condition, the lid of the workpiece transfer box is removed by the lid removing door mechanism of the apparatus main body. Thus, the accommodating vessel is opened to the inside of the treatment apparatus main body. Consequently, the accommodating vessel is airtightly connected to the treatment apparatus main body. As a result, the workpieces in the accommodating vessel are transferred to the treatment chamber of the treatment apparatus main body. In the treatment chamber, a predetermined treatment operation is performed.

These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view showing a treatment apparatus according to a first embodiment of the present invention;

FIG. 2 is a schematic plan view showing the treatment apparatus;

FIG. 3 is a sectional view showing a holding member accommodating chamber according to the first embodiment of the present invention;

FIG. 4 is a perspective view showing the front of the treatment apparatus according to the first embodiment of the present invention;

FIG. 5 is a sectional view showing a cassette accommodating vessel port;

FIG. 6 is a perspective view showing a cassette horizontal moving mechanism;

FIG. 7A is a side view showing a wafer counter disposed on a carrier transfer;

FIG. 7B is a view taken along line B--B of FIG. 7A;

FIG. 8 is an exploded view showing a flow of clean air in an input/output chamber;

FIG. 9 is a side sectional view showing the relation between a clean air blowing means and a cassette in the input/output chamber;

FIG. 10 is a plan view of FIG. 9;

FIG. 11 is a schematic sectional view showing a treatment apparatus according to a second embodiment of the present invention;

FIG. 12 is a perspective view showing the front of the treatment apparatus of FIG. 11;

FIG. 13 is a schematic plan view showing the treatment apparatus;

FIG. 14 is a sectional view showing a holding member accommodating chamber according to the second embodiment of the present invention;

FIG. 15 is a sectional view showing a cassette extracting stage;

FIG. 16 is a sectional view showing a construction of a cassette accommodating vessel;

FIG. 17 is a schematic sectional view showing a treatment apparatus according to a modification of the second embodiment of the present invention;

FIG. 18 is a partial horizontal sectional view showing the treatment apparatus of FIG. 17;

FIG. 19 is a vertical sectional view showing a treatment apparatus according to a third embodiment of the present invention;

FIG. 20 is a horizontal sectional view taken along line A--A of FIG. 19;

FIG. 21 is a vertical sectional view taken along line B--B of FIG. 19;

FIG. 22 is a vertical sectional view taken along line C--C of FIG. 20;

FIG. 23 is a schematic diagram showing a gas control system of the treatment apparatus;

FIG. 24 is a vertical sectional view showing an upright type heat treatment apparatus according to a modification of the third embodiment of the present invention; and

FIG. 25 is a partial vertical sectional view showing an upright type heat treatment apparatus according to another modification of the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIRST EMBODIMENT

Next, with reference to FIGS. 1 to 10, a first embodiment of the present invention will be described.

In this embodiment, the present invention is applied to a heat treatment apparatus for semiconductor wafers.

FIG. 1 is a schematic sectional view showing a treatment apparatus according to a first embodiment of the present invention; FIG. 2 is a schematic plan view showing the treatment apparatus; FIG. 3 is a sectional view showing a holding member accommodating chamber according to the first embodiment of the present invention; FIG. 4 is a perspective view showing the front of the treatment apparatus according to the first embodiment of the present invention; FIG. 5 is a sectional view showing a cassette accommodating vessel port; FIG. 6 is a perspective view showing a cassette horizontal moving mechanism; FIG. 7A is a side view showing a wafer counter disposed on a carrier transfer; FIG. 7B is a view taken along line B--B of FIG. 7A; FIG. 8 is an exploded view showing a flow of clean air in an input/output chamber; FIG. 9 is a side sectional view showing the relation between a clean air blowing means and a cassette in the input/output chamber; and FIG. 10 is a plan view of FIG. 9.

The treatment apparatus according to the first embodiment of the present invention comprises a process tube 1, a loading chamber 8, an input/output chamber 13, a cassette accommodating vessel port 14, and a holding member accommodating chamber 16. The process tube 1 is a treatment chamber that performs a predetermined treatment for a wafer W that is a workpiece. The loading chamber 8 has a transfer mechanism 12 that loads and unloads a wafer boat 6 into and from the process tube 1. The wafer boat 6 serves as a holding member that contains a large number of (for example, 100) wafers W. The input/output chamber 13 inputs and outputs the wafers W to and from the loading chamber 8. The cassette accommodating vessel port 14 is disposed in the input/output chamber 13. The holding member accommodating chamber 16 is disposed between the loading chamber 8 and the input/output chamber 13. The holding member accommodating chamber 16 accommodates the wafer boat 6. A cassette receiving mechanism 17 and a clean air blowing means 18 are disposed in the input/output chamber 13. The cassette receiving mechanism 17 receives a cassette C from a cassette accommodating vessel. The clean air blowing means 18 forces a side flow of clean air into the cassette C.

As shown in FIG. 2, the loading chamber 8 is integrally connected to the holding member accommodating chamber 16. A side wall that partitions the chambers 8 and 6 is provided with clean air delivery openings 20 and 20 that have respective filters 19 and 19. The opposed side wall is provided with air exhaust openings 22 and 22 that have respective filters 21 and 21. Both the chambers 8 and 16 are kept at nearly normal pressure so that a side flow of clean air with a high cleanliness level (for example class 1) is produced. Part of air executed from the air exhaust openings 22 and 22 is returned to the air delivery openings 20 and 20 and then circulated in these chambers 8 and 16.

As shown in FIG. 3, a holding table 24 is disposed below the holding member accommodating chamber 16 through a bellows seal 23. The holding table 24 is vertically moved. A detecting means 25 is disposed on the holding table 24 at a position outside the holding member accommodating chamber 16. The detecting means 25 determines whether or not the wafer boat 6 is present on the holding table 24. The detecting means 25 comprises a movable detecting member 25A and a light sensor 25D. The movable detecting member 25A is connected to the holding table 24. The light sensor 25D is constructed of a light emitting portion 25B and a light receiving portion 25C. The light emitting portion 25B is opposed to a vertical moving portion of the movable detecting member 25A. Thus, when the wafer boat 6 is accommodated in the holding member accommodating chamber 16 and the wafer boat 6 is placed on the holding table 24, the holding table 24 lowers due to its weight against an elastic force of the bellows seal 23. The movable detecting member 25A lowers corresponding to the holding table 24. Thus, the movable detecting member 25A blocks a light beam, which is emitted from the light emitting portion 25B to the light receiving portion 25C. Consequently, the detecting means 25 detects the presence of the wafer boat 6. It should be appreciated that the present invention is not limited to such a construction. Instead of the detecting means 25, another detecting means may be used to detect the presence of the wafer boat 6. For example, a sensor may be buried in a ceiling portion, a floor portion, or a wall portion of the holding member accommodating chamber 16 through a seal mechanism so as to detect the presence of the wafer boat 6. On the other hand, when the wafer boat 6 is raised from the holding table 24, it rises due to the elastic force of the bellows seal 23.

As shown in FIG. 1, a wafer transfer 50 is disposed adjacent to the input/output chamber 13 in the holding member accommodating chamber 16. The wafer transfer 50 is supportably moved by a transfer elevator 51. While the wafer transfer 50 is rising or lowering, it extracts one of the wafers W contained in the carrier C placed on the transfer stage 48 in the input/output chamber 13 at a time and places the wafers W on the wafer boat 6 accommodated in the holding member accommodating chamber 16. Alternatively, the wafer transfer 50 returns the treated wafers W to the carrier C placed on the transfer stage 48.

The process tube 1, which constructs the treatment chamber, is formed of an invert-U-letter shaped, upright type cylindrical quartz vessel. A heater 5 is disposed on an outer periphery of the process tube 1. A cylindrical manifold 2 is connected to a lower end portion of the opening of the process tube 1. The manifold 2 has an upper flange and a lower flange. As shown in FIG. 1, a gas delivery pipe 4 and a gas exhaust pipe 3 are connected to a peripheral wall portion of the manifold 2. The gas delivery pipe 4 delivers a predetermined treatment gas to the process tube 1. The gas exhaust pipe 3 exhausts waste gas from the process tube 1. The gas delivery pipe 4 is connected to a treatment gas supply source and a clean air supply source (that are not shown) through a gas switch valve (not shown) so as to alternately supply the treatment gas and the clean air to the process tube 1.

The loading chamber 8 is airtightly constructed in such a way that the entire outer periphery of the loading chamber 8 (that is made of for example stainless steel panels) is welded or the loading chamber 8 is sealed by O-ring seals. A clean air delivery pipe 27 is connected to upper and lower portions of the loading chamber 8. The clean air delivery pipe 27 is also connected to for example a clean air supply source (not shown). The transfer mechanism 12 disposed in the loading chamber 8 comprises a boat elevator 12 and a ball screw unit 7A. The boat elevator 7 holds the wafer boat 6. The ball screw unit 7A vertically moves the ball elevator 7. Since the inside of the loading chamber 8 is not necessarily in a vacuum condition, wall panels of the loading chamber 8 does not need to have a high rigidity. It should be appreciated that the ball screw unit 7A of the transfer mechanism 12 may be secured to a wall of the loading chamber 8. A conveying mechanism 28 is disposed adjacent to the holding member accommodating chamber in the loading chamber 8. The conveying mechanism 28 transfers the wafer boat 6 between the boat elevator 7 of the transfer mechanism 12 and the holding member accommodating chamber 16. The conveying mechanism 28 is connected to a drive portion 28A and a multi-articulated arm 28B. The drive shaft 28A is disposed outside the loading chamber 8. The drive shaft 28A horizontally rotates and rises and lowers the multi-articulated arm 28B. The multi-articulated arm 28B is connected to a transmission shaft of the drive portion 28A disposed in the loading chamber 8. The multi-articulated arm 28B holds the wafer boat 6. A furnace opening portion is formed at an upper portion of the loading chamber 8. The furnace opening portion has an auto shutter 29 that opens and closes an opening portion that connects the loading chamber 8 and the process tube 1.

The input/output chamber 13 is disposed in the atmosphere of clean air with a high cleanliness level (for example class 1). The input/output chamber 13 has the cassette accommodating vessel port 14, at which the cassette accommodating vessel 30 is placed. The cassette accommodating vessel 30 accommodates the wafer carrier C, which contains a plurality of (for example, 25) wafers. As described above, the input/output chamber 13 has the cassette receiving mechanism 17 and the clean air blowing means 18. The cassette receiving mechanism 17 receives the cassette C from the cassette accommodating vessel 30. The clean air blowing means 18 blows a side flow of clean air into the cassette C. In the example shown in FIG. 1, there are two cassette accommodating vessel ports 14 disposed at a left position and a right position of the input/output chamber 13.

Next, the cassette accommodating vessel 30 will be described. As shown in FIG. 5, the cassette accommodating vessel 30, which is disclosed in Japanese Patent Laid-Open Publication No. 1-222429 and U.S. Pat. No. 4,534,389, comprises a vessel main body 31 and a vessel bottom portion 32. The vessel main body 31 is open-bottomed and has a space for accommodating one cassette C. The vessel bottom portion 32 closes the open portion of the vessel main body 31. The cassette C is accommodated in the cassette accommodating vessel 30 in such a way that it is positively pressed with clean air or inert gas with a high cleanliness level. A gas delivery passageway (not shown) that delivers the clean air or the inert gas to the cassette accommodating vessel 30 is formed on the vessel bottom portion 32. The gas delivery passageway has a valve.

The vessel bottom portion 32 is airtightly disposed on a flange portion 31A at a lower portion of the vessel main body 31 through a seal member 33 such as an O-ring. Lock pins 34 that are protrusible and contractible are disposed at predetermined peripheral positions of the vessel bottom portion 32. The lock pins 34 are connected to a rotating link mechanism 35 disposed at a center portion of the vessel bottom portion 32. Thus, when the rotating link mechanism 35 is rotated, the vessel bottom portion 32 is connected to the vessel main body 31. As an example of the cassette accommodating vessel 30, SMIF-POD (Trade Mark) may be used.

As shown in FIGS. 1 and 4, the cassette accommodating vessel port 14 is formed of a cavity of the front wall of the input/output chamber 13. As shown in FIG. 5, a boat holding table 36, on which the vessel main body 31 is placed, has a cassette inlet hole 37 that is larger than the inner diameter of the flange portion 31A of the vessel main body 31 and smaller than the outer diameter thereof. A vessel bottom portion holding table 38 is disposed at the cassette inlet hole 37. The vessel bottom portion holding table 38 has a peripheral portion with a downward inclination so as to go down from the boat holding table 36. The vessel bottom portion holding table 38 constructs a part of the cassette receiving mechanism 17. A rotating pin 39 is disposed at a center portion of the table 38. The rotating pin 39 fits to the rotating link mechanism 35 of the vessel bottom portion 32. When the table 38 is rotated, the rotating link mechanism 35 works, thereby protruding the lock pins 34.

As shown in FIG. 1, the vessel bottom portion holding table 38 is disposed at a forward end of a vertical moving arm 41. The vertical moving arm 41 is vertically moved by a ball screw 40. The vessel main body 31 is not moved, whereas the vessel bottom portion 32 and the cassette C disposed thereon are lowered. Thus, the cassette C is transferred to the input/output chamber 13. In such a way, the cassette receiving mechanism 17 is constructed.

A horizontal moving arm 42 that is a multi-articulated arm is disposed on the ball screw 40. The horizontal moving arm 42 is horizontally moved from a lower position of the vessel bottom portion holding table 38. An arm auxiliary member 42A is disposed at a forward end of the horizontal moving arm 42. The arm auxiliary member 42A swings so that it is always kept horizontal. Nail portions 43 are disposed at both edges of the arm auxiliary member 42A. When the nail portions 43 are closed, while the horizontal moving arm 42 is being bent, an upper side wall of the cassette C is held by the nail portions 43.

A handle portion 44 is disposed at an upper portion of the vessel main body 31 of the cassette accommodating vessel. For example, the operator can hold the handle portion 44 to carry the entire cassette accommodating vessel.

A plurality of key-shaped vessel holders 45 are disposed on the boat holding table 36 at peripheral positions of the cassette inlet hole 37. When the key-shaped vessel holders 45 are raised and lowered, the flange portion 31A of the cassette accommodating vessel 31 is locked and unlocked, respectively.

As shown in FIG. 1, a carrier transfer 46 is disposed just behind the cassette accommodating vessel port 14 in the input/output chamber 13. The carrier transfer 46 is raised and lowered by an elevator 47. A transfer stage 48 is disposed behind the carrier transfer 46. A shelf-shaped carrier stock stage 49 is disposed at an upper side position of the transfer stage 48. The carrier stock stage 49 is constructed of a plurality of shelves that have two rows and four levels. The carrier stock stage 49 can store the wafers carriers C without changing their orientation. The carrier stock stage 49 can also store empty carriers C where wafers have been removed.

As shown in FIGS. 7A and 7B, a reflection type laser beam sensor (wafer counter) 53 is disposed at a forward end of each of the carrier transfers 46. The laser beam sensor 53 is constructed of a light emitting device 52A and a light receiving device 52B that are aligned on nearly the same plane. When the carrier transfer 46 is raised or lowered, the laser beam sensor 53 detects reflection beams reflected from edge portions of wafers, thereby obtaining information about the number of wafers and positions thereof. This information is used when the wafer transfer 46 transfers wafers. FIG. 7B is a view taken along lines B--B of FIG. 7A. The input/output chamber 13, the loading chamber 8, the holding member accommodating chamber 16, and the process tube 1 are partitioned by a partition wall 54 except for a portion where the transfer stage 48 operates. An air delivery HEPA filter 55 is disposed between the partition wall 54 and the carrier stock stage 49. An air delivery opening 56 is disposed at an upper portion of the air delivery HEPA filter 55. The air delivery opening 56 delivers clean air with a high cleanliness level (for example class 1) to the input/output chamber 13. The delivered clean air horizontally flows from a side surface to the input/output chamber 13 (see FIG. 8).

An inner HEPA filter 57 is disposed at an upper portion of the cassette accommodating vessel port 14. The inner HEPA filter 57 is opposed to the air delivery HEPA filter 55. The inner HEPA filter 57 has a blowing opening 57A that faces downward. Thus, the inner HEPA filter 57 downwardly bends the flow of the clean air filtered by the air delivery HEPA filter, thereby creating a circulation flow or a down flow. The blowing opening 57A should be as wide and large as possible as long as it does not interfere with the carrier transfer 46.

As shown in FIG. 8, an air exhaust opening 58 is disposed at a lower position on the side wall of the input/output chamber 13. The air exhaust opening 58 has a air blow fan 59 that receives circulation flow or the down flow of waste air. An air exhaust duct 60 is connected to the air exhaust opening 58 along a vertical corner portion of the input/output chamber 13. The air exhaust duct 60 exhausts the atmosphere in the input/output chamber 13 to the outside of the treatment apparatus. Part of the waste air may be returned to the input/output chamber 13 rather than being directly exhausted to the outside of the treatment apparatus. FIG. 8 is an exploded perspective view showing an air ventilation system of the input/output chamber.

As shown in FIGS. 1, 9, and 10, a side flow blowing header 62 is disposed on a side wall 61 that partitions a lower portion of the cassette accommodating vessel port 14, which is formed in a stage shape. The side flow blowing header 62 constructs a part of the clean air blowing means 18. A blowing opening 63 is formed at a lower portion of the cassette accommodation vessel port 14, where the cassette C is lowered and received in the input/output chamber. The blowing opening 63 has a large number of blades 64 that are aligned in horizontal direction toward the cassette C. Thus, the blowing opening 63 blows a side flow 65 of clean air into the cassette C. The blades 64 may be bent in oblique direction.

The size of the side flow blowing header 62 is nearly the same as the size of the side wall 61, which partitions the lower portion of the boat 14, so as to prevent the atmosphere from staying at a lower position.

As a clean air supply means, a clean air passageway 66 is disposed. The clean air passageway 66 connects an upper portion of the side flow blowing header 62 and the blowing opening 57A of the inner HEPA filter 57. A funnel-shaped air delivery portion 67 is disposed at a side edge portion of the blowing opening 57A of the clean air passageway 66 so as to receive a desired amount of clean air.

A distributing passageway 68 is disposed at an upper portion of the side flow blowing header 62. The distributing passageway 68 equally distributes clean air supplied from the clean air passageway 66 in a width direction of the side flow blowing header 62.

The distributing passageway 68 may be a pipe member that has a large number of air ventilation holes. The clean air supply method is not limited to the above-described method, where air supplied from the inner HEPA filter 57 is used. Instead, a clean air supply pipe (not shown) disposed adjacent to the treatment apparatus may be directly connected to the side flow blowing header 62. In addition, to keep the cleanliness level of clean air high, a HEPA filter may be disposed in the side flow blowing header 62.

Next, operations of the above-described treatment apparatus will be described.

First, an operation for transferring wafers accommodated in the input/output chamber 13 to the process tube 1 through the loading chamber 8 will be descried.

The wafer boat 6 is accommodated in the holding member accommodating chamber 16. The wafer carrier C contains a predetermined number of wafers W. The wafer carrier C is transferred to the wafer boat 6 disposed in the holding member accommodating chamber 16 by the wafer transfer 50. Next, the conveying mechanism 28 is driven so that the wafer boat 6 is moved to and placed on the boat elevator 7.

The boat elevator 7 is raised and the wafer boat 6 is loaded into the process tube 1. The flange 6A of the wafer boat 6 is brought into contact with the flange 2A. Thus, the process tube 1 is airtightly closed. The atmospheric gas in the process tube 1 is exhausted by the exhaust pipe 3. When the inside of the process tube 1 becomes a vacuum, a treatment gas is delivered from the gas delivery pipe 4 to the process tube 1 so as to perform a desired treatment.

After the treatment is completed, the treatment gas in the process tube 1 is exhausted. When the inside of the process tube 1 becomes a predetermined vacuum, clean air is delivered from the gas delivery pipe 4 to the process tube 1. When the pressure of the clean air becomes nearly equal to the pressure of the clean air in the loading chamber 8, namely the same pressure as the atmosphere, the wafer boat 6 is lowered. In the reverse order of the wafer loading sequence, the treated wafers W are unloaded.

Clean air with a high cleanliness level, for example class 1, is always delivered to the loading chamber 8 and the holding member accommodating chamber 16 through the filters 19 and 19. The side flow is produced and a part thereof is circulated so that the loading chamber 8 and the holding member accommodating chamber 16 are kept at nearly the atmospheric pressure. In this case, the air pressures in the loading chamber 8 and the holding member accommodating chamber 16 are preferably slightly higher than the air pressure in the output/input chamber 13. Thus, the loading chamber 8 and the holding member accommodating chamber 16 are positively pressured. Consequently, the atmosphere in the loading chamber 8 and the holding member accommodating chamber 16 flows to the input/output chamber 13 through the transfer stage 48, thereby purging particles (see FIG. 2).

Next, an operation for transferring wafers W between the cassette accommodating vessel 30 and the input/output chamber 13 will be described.

The cassette C, which contains for example 25 wafers W that have been treated in the preceding step or not treated, is accommodated in the cassette accommodating vessel 30. The cassette accommodating vessel 30 is placed on the vessel bottom portion holding table 38, which is a predetermined position of the boat holding table 36 of the cassette accommodating vessel port 14, by the AGV or the operator. At this point, the vessel holder 45 of the boat holding table 36 is raised so as to secure the flange portion 31A of the vessel main body.

At this point, the vessel bottom portion holding table 38 disposed at the forward end of the vertical moving arm 41 of the cassette receiving mechanism 17 airtightly closes the cassette inlet hole 37, which is formed on the boat holding table 36, so as to prevent the atmosphere in the working region with a low cleanliness level from entering the input/output chamber 13. The cassette accommodating vessel 30 is filled with clean air with a very high cleanliness level or an inert gas such as N2 gas so as to create the non-oxygen atmosphere. The clean air or inert are is positively pressured so as to prevent the atmosphere in the other chambers from entering the cassette accommodating vessel 30. Thus, even if the cassette C is conveyed through a working region in a low cleanliness level such as class 1000, the wafers W are not exposed to the atmosphere. In this embodiment, the cassette accommodating vessel 30 is filled with clean air with a high cleanliness level.

After the vessel main body 31 is secured to the boat holding table 36, the rotating pin 39 on the vessel bottom portion holding table 38 is rotated, thereby removing the lock pins, which connect the vessel bottom portion 32 and the flange portion 31A.

Next, the vertical moving arm 41 is lowered. Thus, the cassette C placed on the vessel bottom portion 32 is entered into the input/output chamber 13. The vessel bottom portion holding table 38 is lowered and thereby the cassette inlet hole 37 of the boat holding table 36 is opened. Since the vessel main body 31 of the cassette accommodating vessel is airtightly closed, the atmosphere in a low cleanliness level does not enter the input/output chamber 13.

After the cassette C has been received, the horizontal moving arm 42 is bent. The nail portions 43 of the horizontal moving arm 42 are placed above the cassette C. The nail portions 43 are closed so as to hold the upper side portions of the cassette C. While the cassette C is being held, the horizontal moving arm 42 is extended. Thus, the cassette C is moved in horizontal direction. The cassette C is transferred to the carrier transfer 46, which is vertically moved, by the elevator 47. When the wafers W are conveyed from the carrier transfer 46 to the outside, the above-described operation is performed in the reverse order.

Just before the carrier C is transferred to the carrier transfer 46 by the horizontal moving arm 42, a laser beam is irradiated from the light emitting device 52A of the laser beam sensor 53 (see FIG. 7), which is a wafer counter and disposed at the forward end of the carrier transfer 46, which is raised or lowered along a side of the carrier C. When the light receiving device 52B receives the reflected light beam reflected from the edge surfaces of the wafers, the information about the number of wafers and positions thereof is obtained. The wafer transfer 46 transfers the wafer boat 6 corresponding to the obtained information.

The cassette, after the information about the number of wafers and positions thereof has been detected, is transferred to the carrier transfer 46 that will be raised or lowered.

When the carrier C transferred to the carrier transfer 46 is queued for the treatment, the carrier C is temporarily placed on the carrier stock stage 49. Alternatively, when the transfer stage 48 is empty, the carrier C is placed on the transfer stage 48. One or a plurality of the wafers W are extracted from the carrier C placed on the carrier stage 48 at a time and transferred to the wafer boat 6.

The cassette C, which is empty, is held by the wafer transfer 50 and accommodated in the carrier stock station 49 until the treatment for the wafers W is completed.

The cassette accommodating vessel 30, which is airtightly sealed from the outer atmosphere, is placed on the cassette accommodating vessel port 14 so as to input and output the wafers W. Thus, it is not required to remarkably improve the cleanliness level of the working region S, where the operator or the like works, in comparison with the conventional apparatus, where wafers are exposed to the atmosphere while they are being conveyed. In the conventional apparatus, the cleanliness level of the working region S should be kept to class 1 so as to prevent particles from adhering to the wafers W. However, according to this embodiment, the cleanliness level of the atmosphere in only the cassette accommodating chamber 30, the loading chamber 8, and the holding member accommodating chamber 16 should be keep at the class 1. The cleanliness level of the atmosphere in the working region S can be lower than the cleanliness level of the atmosphere in these chambers. For example, the cleanliness level of the atmosphere in the working region S may be the class 1000. Thus, the cleanliness level of the atmosphere in the working region S can be lowered, thereby reducing the construction cost and the operation cost of the clean room. Consequently, the fabrication cost of the wafers can be remarkably reduced.

In this case, the pressure applied to the inside of the cassette accommodating vessel 30 is higher than the air pressure in the input/output chamber, the atmosphere in a low cleanliness level does not enter the cassette accommodating vessel 30.

As shown in FIG. 8, clean air delivered from an upper portion of the input/output chamber 13 is circulated therein through the air delivery HEPA filter 55. Thus, the circulation flow or a down flow is produced.

In other words, clean air is filtered by the air delivery HEPA filter 55 and delivered from the blowing opening in horizontal direction. The air is filtered by the inner HEPA filter 57 and delivered from the blowing opening 57A in downward direction. Thus, the down flow 69 is produced.

The waste air at the bottom of the input/output chamber 13 is exhausted to the outside of the treatment apparatus through the air exhaust opening 58 and the exhaust duct 60. Part of exhausted air is returned to the input/output chamber 13 and recirculated therein.

The part of clean air filtered by the inner HEPA filer 57 is supplied to the side flow blowing header 62 of the clean air blowing means 18 through the clean air passageway 66. The clean air is horizontally delivered from the side flow blowing header 62. Thus, the side flow 65 is created below the cassette accommodating vessel port 14.

As shown in FIGS. 9 and 10, a large number of wafers W are horizontally aligned at predetermined pitches in the cassette C. Thus, when the cassette is lowered and placed in the input/output chamber 13, since the wafers W are exposed to the side flow 65, particles that adhere to the wafers are blown and purged.

Since the cassette accommodating vessel port 14 is formed in a stage shape, the space below the cassette accommodating vessel port 14 is not exposed to the down flow 69. Thus, air tends to stay in this space. However, the side flow 65 of clean air delivered from the side flow blowing header 62 prevents the air from staying in this space. The side flow 65 can effectively purge particles and the like that take place in a movable mechanism such as the cassette receiving mechanism 17, which is constructed of the ball screw 40 and the vertical moving arm 41. Thus, the decrease of the yield of the final products can be prevented.

The side flow 65 of the air containing the particles and the like is downwardly exhausted to the outside of the treatment apparatus by the down flow 69.

The empty cassette accommodating vessel 30 may be temporarily accommodated in a holding shelf (not shown) that is disposed in a working region S upstream of the treatment apparatus by the operator. In this case, the vessel bottom portion holding table 38 of the cassette receiving mechanism 17 should be raised so as to airtightly close the cassette inlet hole 37.

It should be appreciated that the construction of the cassette accommodating vessel according to the first embodiment of the present invention is not limited to the above-described construction. Instead, any construction may be used as long as the cassette accommodating vessel can airtightly accommodate the cassette. In addition, the constructions of the vertical moving arm 41 and the horizontal moving arm 42 of the cassette receiving mechanism 17, which transfer the carrier C to and from the cassette accommodating vessel are not limited to the above-described constructions as long as the cassette C can be transferred.

In the above-described embodiment, the treatment apparatus is provided with the holding member accommodating chamber 16 so as to reduce the consumption of inert gas and operating time of the treatment apparatus. However, the first embodiment may be applied to the conventional treatment apparatus, which is not provided with the holding member accommodating chamber 16. In addition, the transfer stage 48 and the boat elevator 7 may be adjacently disposed so that the transfer elevator 51 directly transfers the wafers W contained in the cassette C on the transfer stage to the wafer boat 6 on the boat elevator 7.

In the above-described embodiment, the construction of the holding member accommodating chamber 16 of the input/output chamber 13 and the construction of the loading chamber 8 are the same as the conventional constructions, where the atmospheric air therein is always kept at nearly the air pressure by clean air. However, it should be appreciated that the first embodiment of the present invention is not limited to such constructions. Instead, the loading chamber 8 may be airtightly closed against the input/output chamber 13 (this construction is referred to as load lock chamber construction). In addition, a construction where inert gas such as N2 or clean air is supplied for a positive pressure, exhausted, and deaerated for a vacuum may be used.

When the cassette accommodating vessel is filled with an inert gas such as N2, the input/output chamber and the loading chamber are preferably filled with the inert gas as the atmospheric gas so as to suppress natural oxide films from being formed on the wafer surfaces.

The first embodiment of the present invention may be applied to treatment apparatuses for glass substrates, LCD substrate, and so forth as well as upright type CVD apparatuses and oxide diffusion apparatuses.

As was described above, according to the treatment apparatus of the first embodiment, the following excellent effects can be obtained.

The workpieces are contained in the cassette. The cassette is accommodated in the cassette accommodating vessel. The cassette accommodating vessel is placed on the cassette accommodating vessel port. The cassette accommodating vessel port is input and output to and from the input/output chamber. Thus, the workpieces are not exposed to atmosphere in the working region. Consequently, it is not required to remarkably improve the cleanliness level of the working region outside the treatment apparatus in comparison with the cleanliness level of the atmospheric air in the input/output chamber.

Thus, it is required to improve the cleanliness level of the atmosphere only in the input/output chamber and the loading chamber, where the workpieces are exposed to the atmosphere. In other words, since the cleanliness level of the working region in the clean room can be lowered, the construction cost of the clean room and the running cost thereof can be remarkably reduced.

In addition, the clean air blowing means is disposed below the cassette accommodating vessel port so as to create the side flow of the clean air. Thus, particles can be purged from the surface of the workpieces. Alternatively, the atmosphere at the bottom of the port can be circulated so as to prevent the air from staying. Thus, the yield of the final products can be improved.

SECOND EMBODIMENT

Next, with reference to FIGS. 11 to 18, a second embodiment of the present invention will be described.

In this embodiment, the present invention is applied to a heat treatment apparatus for semiconductor wafers.

FIG. 11 is a schematic sectional view showing a treatment apparatus according to a second embodiment of the present invention; FIG. 12 is a perspective view showing the front of the treatment apparatus of FIG. 11; FIG. 13 is a schematic plan view showing the treatment apparatus; FIG. 14 is a sectional view showing a holding member accommodating chamber according to the second embodiment of the present invention; FIG. 15 is a sectional view showing a cassette extracting stage; and FIG. 16 is a sectional view showing a construction of a cassette accommodating vessel. In this embodiment, a loading room of the treatment apparatus is constructed of a load lock chamber that is airtightly sealed from other chambers and filled with an inert gas such as N2 gas that can be delivered and deaerated.

The treatment apparatus according to the second embodiment comprises a process tube 101, a load lock chamber 108, an input/output chamber 112, a cassette accommodating vessel port 113, a receiving means 115, a vessel storage stage 116, a cassette extracting stage 117, vessel transfer means 118, and a holding member accommodating chamber 119. The process tube 101 is a treatment chamber that performs a predetermined treatment for wafers W, which are workpieces. The load lock chamber 108 serves as a loading chamber and has a transfer mechanism 107. The transfer mechanism 107 transfers a wafer boat 106 to and from the process tube 101. The wafer boat 106 serves as a holding member that contains a large number of (for example 100) wafers W. The input/output chamber 112 inputs and outputs the wafers W to and from the load lock chamber 108. The cassette accommodating vessel port 113 is formed at the input/output chamber 112. The receiving means 115 receives the cassette accommodating vessel 114 placed on the cassette accommodating vessel port 113 into the input/output chamber 112. The vessel storage stage 116 temporarily stores the cassette accommodating vessel 114. The cassette extracting stage 117 extracts the cassette C from the cassette accommodating vessel 114. The vessel transfer means 118 transfers the cassette accommodating vessel 114 in the input/output chamber 112. The holding member accommodating chamber 119 is disposed between the load lock chamber 108 and the input/output chamber 112. The holding member accommodating chamber 119 accommodates the wafer boat 106.

A front auto door 120 is disposed between the holding member accommodating chamber 119 and the input/output chamber 112. A rear auto door 121 is disposed between the holding member accommodating chamber 119 and the load lock chamber 108. If necessary, the front auto door 120 and the rear auto door 121 are opened. When the front auto door 120 and the rear auto door 121 are closed, the holding member accommodating chamber 119 is sealed from other chambers. A vacuum pipe 122 is connected to the holding member accommodating chamber 119. The vacuum pipe 122 is connected to a vacuum pump (not shown). In addition, a N.sub.2 gas delivery pipe 123 and a N.sub.2 gas exhaust pipe 124 are connected to the holding member accommodating chamber 119. The N.sub.2 gas delivery pipe 123 is connected to for example a N.sub.2 gas supply source (not shown). Thus, the atmosphere in the holding member accommodating chamber 119 can be substituted with the atmosphere of a predetermined vacuum or N.sub.2 gas.

As shown in FIG. 14, a holding table 126 is disposed at a lower position of the holding member accommodating chamber 119. The holding table 126 is vertically moved through for example a bellows seal 125. A detecting means 127 is disposed at an outer position of the holding table 126. The detecting means 127 determines whether or not the wafer boat 106 is present. The detecting means 127 comprises a movable detecting member 127A and a light sensor 127D. The movable detecting member 127A is connected to the holding table 126. The light sensor 127D is constructed of a light emitting portion 127B and a light receiving portion 127C. The light emitting portion 127B is opposed to a vertical moving portion of the movable detecting member 127A. When the wafer boat 106 is accommodated in the holding member accommodating chamber 119 and the wafer boat 106 is placed on the holding table 126, the holding table 126 lowers due to the weight thereof against an elastic force of the bellows seal 125. In addition, the movable detecting member 127A also lowers, thereby preventing the light beam emitted by the light emitting portion from entering the light receiving portion 127C. Thus, the detecting means 127 can determine whether or not the wafer boat 106 is present. It should be appreciated that the detecting means 106 is not limited to such a construction. Instead, any detecting means may be used. For example, the presence of the wafer boat 106 may be determined by a sensor buried in a ceiling portion, a floor portion, or a wall portion of the holding member accommodating chamber 119 through a seal mechanism.

The process tube 101, which constructs the treatment chamber, is formed of an inverse-U-letter shaped, upright type cylindrical quartz vessel. A heater 105 is disposed on an outer periphery of the process tube 101. A protection cover 128 is disposed around the heater 105. The protection cover 128 contains a cooling pipe and a heat insulating material. A manifold 102 is disposed at an lower end of an opening of the process tube 101. The manifold 102 is cylindrically shaped and has an upper flange and a lower flange. As shown in FIG. 11, a gas delivery pipe 104 and a gas exhaust pipe 103 are connected to a peripheral wall portion of the manifold 102. The gas delivery pipe 104 delivers a predetermined treatment gas to the process tube 101. The gas exhaust pipe 103 exhausts waste gas from the process tube 101. The gas delivery pipe 104 is connected to a predetermined treatment gas supply source and an N.sub.2 gas supply source through a gas switch valve (not shown). Thus, the treatment gas and the N.sub.2 gas can be alternately delivered to the process tube 101.

The load lock chamber 108 is sealed by welding the entire periphery of for example stainless steel panels. Alternatively, the load lock chamber 108 is sealed by an O ring. A N.sub.2 gas delivery pipe 129 and a N.sub.2 gas exhaust pipe 130 are connected to an upper portion and a lower portion of the load lock chamber 108, respectively. The N.sub.2 gas delivery pipe 129 is connected to for example a N.sub.2 gas supply source (not shown). Thus, a predetermined amount of N.sub.2 gas is always supplied to the load lock chamber 108. The transfer mechanism 107, which is disposed in the load lock chamber 108, comprises a boat elevator 107A and a ball screw unit 107B. The boat elevator 107A holds the wafer boat 106. The ball screw unit 107B vertical moves the boat elevator 107A. A conveying mechanism 131 is disposed in the load lock chamber 108 adjacent to the holding member accommodating chamber 119. The conveying mechanism 131 conveys the wafer boat 106 between the boat elevator 107A of the transfer mechanism 107 and the holding member accommodating chamber 119. The conveying mechanism 131 comprises a drive portion 131A and a multi-articulated arm 131B. The drive portion 131A is disposed outside the load lock chamber 108 and drives a horizontal rotation (swing motion) and vertical motion. The multi-articulated arm 131B is disposed in the load lock chamber 108 and connected to a transmission shaft of the drive portion 131A. The multi-articulated arm 131B holds the wafer boat 106. A furnace opening portion is formed at an upper portion of the load lock camber 108. An auto shutter 132 is disposed at the furnace opening portion. The auto shutter 132 opens and closes an opening portion that connects the load lock chamber 108 and the process tube 101.

As shown in FIG. 11 (right side), two cassette accommodating vessel ports 113 are disposed on left and right positions at the front of the input/output chamber 112. As described above, each of the cassette accommodating vessel ports 113 holds the cassette accommodating vessel 114. The cassette accommodating vessel 114 accommodates the carrier C, which contains a plurality of (for example, 25) wafers W (see FIG. 12).

Next, the cassette accommodating vessel 114 will be described. The cassette accommodating vessel 114 is disclosed in Japanese Patent Laid-Open Publication No. 1-222429 and U.S. Pat. No. 4,534,389. As shown in FIG. 16, the cassette accommodating vessel 114 comprises a square vessel main body 132 and a vessel bottom portion 133. The vessel main body 132 has a size for accommodating the cassette C. The vessel main body 132 is open-bottomed. The vessel bottom portion 133 airtightly closes the opening portion. When the cassette C is accommodated in the cassette accommodating vessel 114, it is filled with clean air with a high cleanliness level or an inert gas such as N.sub.2. Thus, the inside of the cassette accommodating vessel 114 is positively pressured. A gas delivery passageway 134 with a valve is disposed at a bottom portion or a side wall of the cassette accommodating vessel 114. The gas delivery passageway 134 delivers the clean air and the inert gas to the cassette accommodating vessel 114.

The vessel bottom portion 133 is airtightly disposed at a flange portion 132A that is disposed at a lower portion of the vessel main body 132 through a seal member 135 such as an O-ring. Lock pins 136 are protrusibly and contractibly disposed at peripheral positions of the vessel bottom portion 133. When the lock pins 136 are connected to a rotating link mechanism 137 that is disposed at a center portion of the vessel bottom portion 133 and the rotating link mechanism 137 is rotated, the vessel bottom portion 133 is attached to or detached from the vessel main body 132. A handle portion 138 is disposed at an upper portion of the vessel main body 132 of the cassette accommodating vessel. For example, when the operator holds the handle portion 138, he or she can be easily carry the entire cassette accommodating vessel. An example of the cassette accommodating vessel 114 is SMIF-POS (Trade Mark). As shown in FIGS. 11 and 12, the cassette accommodating vessel ports 113 are defined by a cavity of the front wall of the input/output chamber 112. A vessel inlet 140 is formed on the boat holding table 139, which holds the cassette accommodating vessel 114. The size of the vessel inlet 140 is slightly larger than the area of the bottom portion of the cassette accommodating vessel so that the cassette accommodating vessel 114 is input to the input/output chamber 112. A lifting table 142 is disposed at a forward end of an arm 141 of the receiving means 115 so that the vessel inlet 140 is airtightly closed by the lifting table 142. The arm 141 is connected to for example a ball screw 143 so that the arm 141 is vertically moved. Thus, when the cassette accommodating vessel 114 is placed on the lifting table 142 and the lifting table 142 is lowered, the cassette accommodating vessel is input to the input/output chamber 112 as shown in a phantom line of FIG. 11.

A vessel transfer 144 is disposed between the cassette accommodating vessel port 113 and the vessel storage stage 116 in the input/output chamber 112. The vessel transfer 144 serves as vessel transfer means that raises and lowers the cassette accommodating vessel through an elevator 145. The vessel transfer 144 has a bending arm 147. The bending arm 147 is disposed on a base table 146 that rises and lowers along the elevator 145. A pair of chucks 148 are disposed at a forward end of the bending arm 147. The chucks 148 are approached to each other so as to hold side walls of the cassette accommodating vessel 114. The lower end of the elevator 145 is movably supported by a guide rail 149 disposed in the alignment direction of the vessel storage stage 116 through for example a bearing 150. Thus, the cassette accommodating vessel 114 placed on the cassette accommodating vessel port 113 is held and transferred by the vessel transfer 144 to the vessel storage stage 116.

A working space S is defined between the elevator 145 and the vessel storage stage 116 so that the cassette accommodating vessel 114 held by the vessel transfer 144 is moved. In this embodiment, the vessel storage stage 116 has a shelf portion 151 with three levels and three rows that are partitioned vertically and horizontally, respectively. Thus, the vessel storage stage 116 can store a total of nine cassette accommodating vessels 114. It should be appreciated that the number of cassette accommodating vessels 114 stored in the vessel storage stage 116 is not limited to nine. If necessary, the number of cassette accommodating vessels 114 can be increased or decreased. However, the number of cassette accommodating vessels 114 should be designated so that they can contain a total of for example 100 wafers. When one cassette contains 25 wafers, the number of cassette accommodating vessels 114 should be four.

A cassette extracting stage 117 on which the cassette C is extracted from the cassette accommodating vessel 114 is disposed at a lower position of the working space S. In reality, the cassette extracting stage 117 has a rectangular-parapellopiped, side-opened casing 153. The open side of the casing 153 is opening toward the wafer transfer 152. The casing 153 is connected to a partition wall 154 that separates the input/output chamber 112 from the load lock chamber 108 and the holding member accommodating chamber 119. Thus, when the cassette C is extracted from the cassette accommodating vessel 114, the wafers W are exposed to the atmosphere of inert gas in the holding member accommodating chamber 119. A cassette inlet hole 155 is formed in a ceiling holding portion 153A of the casing 153. The size of the cassette inlet hole 155 is larger than the inner diameter of the flange portion 132A and smaller than the outer diameter thereof. The cassette inlet hole 155 serves as an opening portion that opens when the cassett