Quartz wafer processing chamber

Described herein is a process chamber with a substantially all-quartz interior surface. The preferred embodiments have upper and lower walls being curved in both the x-z and y-z planes. In one embodiment, the chamber has thin upper and lower dome walls made from a generally transparent material such as quartz, each with a convex exterior surface and a concave interior surface. These walls are joined at their side edges to a cylindrical side wall, preferably formed from a generally translucent material such as bubble quartz. The upper and lower walls and the side wall substantially enclose an all-quartz interior surface, except for apertures used for gas inlet and outlet, wafer intrusion and extraction and wafer retention. An internal reinforcement extends along the entire interior perimeter of the chamber to provide additional strength and support to the chamber. An external reinforcement surrounds the cylindrical side wall to confine outward expansion of the chamber. In another embodiment, the chamber has upper and lower dome walls that are curved along both their longitudinal and lateral axes, the walls being substantially rectangular when viewed from above.

 

What is claimed is:

1. A processing chamber, comprising:

an upper wall having a convex outer surface and a concave inner surface, the upper wall extending a length in a y dimension, a width in an x dimension and a height in a z dimension, wherein the upper wall is curved in both x-z and y-z planes;

a lower wall spaced from the upper wall having a convex outer surface and a concave inner surface, the lower wall extending a length in the y dimension, a width in the x dimension and a height in the z dimension, wherein the lower wall is curved in both x-z and y-z planes;

at least one side wall having an inner surface and an outer surface connecting the upper wall to the lower wall, wherein the upper wall, lower wall and the at least one side wall together substantially enclose a chamber space having all-quartz enclosing surfaces; and

an external reinforcement provided on at least part of the outer surface of the at least one side wall to confine outward expansion of the chamber;

wherein the upper wall is connected to the lower wall by a plurality of side walls.

2. The chamber of claim 1, wherein the upper and lower walls are generally circular when viewed from above.

3. The chamber of claim 1, wherein the upper wall is generally dome-shaped.

4. The chamber of claim 1, wherein the lower wall is generally dome-shaped.

5. The chamber of claim 2, wherein the upper wall is connected to the lower wall by a generally cylindrical side wall.

6. The chamber of claim 1, wherein the upper and lower walls are formed from transparent quartz.

7. A processing chamber, comprising:

an upper wall having a convex outer surface and a concave inner surface, the upper wall extending a length in a y dimension, a width in an x dimension and a height in a z dimension, wherein the upper wall is curved in both x-z and y-z planes;

a lower wall spaced from the upper wall having a convex outer surface and a concave inner surface, the lower wall extending a length in the y dimension, a width in the x dimension and a height in the z dimension, wherein the lower wall is curved in both x-z and y-z planes;

at least one side wall having an inner surface and an outer surface connecting the upper wall to the lower wall, wherein the upper wall, lower wall and the at least one side wall together substantially enclose a chamber space having all-quartz enclosing surfaces; and

an external reinforcement provided on at least part of the outer surface of the at least one side wall to confine outward expansion of the chamber;

wherein the at least one side wall is formed from bubble quartz.

8. The chamber of claim 1, further comprising an interior reinforcement extending from an inner surface of the at least one side wall to resist outward deformation of at least one side wall and flattening deformation of the upper and lower walls where the chamber is subjected to an external pressure greater than the pressure within the chamber.

9. The chamber of claim 8, wherein the interior reinforcement extends around the entire internal perimeter of the chamber space.

10. The chamber of claim 9, wherein the interior reinforcement is an annular support plate.

11. The chamber of claim 9, wherein the interior reinforcement includes a plurality of support plates fixed to an inner surface of the at least one side wall.

12. A processing chamber, comprising:

a quartz upper dome wall;

a quartz lower dome wall spaced from the upper dome wall, each dome wall having a convex outer surface and a concave inner surface;

a generally cylindrical quartz side wall having an inner surface and an outer surface connecting the upper and lower dome walls and defining a chamber space therebetween;

a retainer surrounding at least a portion of the outer surface of the side wall to confine outward expansion of the chamber; and

an interior reinforcement extending from the inner surface of the side wall;

wherein the chamber space is substantially enclosed only by the inner surfaces of the dome wall and the inner surface of the side wall.

13. The chamber of claim 12, wherein the interior reinforcement is joined to the inner surface of the side wall.

14. The chamber of claim 12, wherein the interior reinforcement is an annular support plate.

15. The chamber of claim 12, wherein the retainer is metallic.

16. The chamber of claim 12, wherein the side wall includes an inlet flange having an opening to the chamber space to allow for the introduction of process gases and wafer insertion.

17. The chamber of claim 12, wherein the side wall includes an outlet flange open to the chamber space to allow for gas exhaust.

18. A processing chamber, comprising:

a quartz upper dome wall;

a quartz lower dome wall spaced from the upper dome wall, each dome wall having a convex outer surface and a concave inner surface;

a generally cylindrical quartz side wall having an inner surface and an outer surface connecting the upper and lower dome walls and defining a chamber space therebetween;

a retainer surrounding at least a portion of the outer surface of the side wall to confine outward expansion of the chamber; and

a gas inlet extending from the upper wall;

wherein the chamber space is substantially enclosed only by the inner surfaces of the dome wall and the inner surface of the side wall.

19. The chamber of claim 12, wherein the inner surfaces between the dome walls and the side wall are substantially flush.

20. A processing chamber having an upstream end and a downstream end and lateral sides extending therebetween, the chamber comprising:

an upper wall and a lower wall spaced from the upper wall, each wall being outwardly curved in both a lateral and a longitudinal direction; and

a plurality of side walls connecting the upper and lower walls, including:

an inlet flange connecting the upper and lower walls at the upstream. end of the chamber;

an outlet flange connecting the upper and lower walls at the downstream end of the chamber; and

side rails connecting the upper and lower walls at the lateral sides of the chamber and connecting the inlet and outlet flanges between the upstream and downstream ends of the chamber; and

an external reinforcement provided along at least a portion of the plurality of side walls to confine outward expansion of the chamber;

wherein the chamber has a substantially all-quartz interior surface defined by the upper and lower walls and the plurality of side walls.

21. The chamber of claim 20, wherein the upper and lower walls have lateral edges and are generally circular when viewed from above.

22. The chamber of claim 21, wherein the side rails are outwardly curved to mate with the lateral edges of the upper and lower walls.

23. The chamber of claim 20, wherein an upper and lower side rail is provided at each lateral side of the chamber, each upper side rail extending from the upper wall and each lower side rail extending from the lower wall, and wherein the upper and lower side rails are joined together.

24. The chamber of claim 20, wherein the upper and lower walls are substantially circular when viewed from above.

25. The chamber of claim 24, wherein the upstream and downstream edges of the upper and lower walls appear straight when viewed from above and are outwardly curved in the vertical dimension.

26. The chamber of claim 20, further comprising an internal reinforcement extending from the interior surface of the chamber.

27. The chamber of claim 26, wherein the internal reinforcement includes a plurality of support plates joined to and extending inwardly from the inlet and outlet flanges.

28. The chamber of claim 26, wherein the internal reinforcement includes a plurality of support plates joined to and extending inwardly from the side rails.

29. The chamber of claim 20, wherein the external reinforcement includes:

retaining beams extending along the lateral sides of the chamber; and

end flanges mating with the inlet and outlet flanges.

30. A chamber for processing semiconductor wafers and the like, the chamber comprising:

outwardly convex upper and lower walls each having outer and inner surfaces and being curved in a lateral and a longitudinal direction; and

at least one side wall connecting the upper and lower walls, the at least one side wall having inner surfaces that are substantially flush with the inner surfaces of the upper and lower walls at the connection between the edges of the at least one side wall and the upper and lower walls, the upper and lower walls and the at least one side wall enclosing a chamber space having a substantially continuous inner surface formed of a nonreactive substantially light-transmissive material; wherein the at least one side wall is made of translucent quartz.

31. The chamber of claim 30, wherein the inner surface of the chamber space is formed of quartz.

32. The chamber of claim 31, wherein the upper and lower walls are made of transparent quartz.

33. The chamber of claim 31, wherein the upper and lower walls are substantially dome-shaped and the at least one side wall is generally cylindrical.

34. A processing chamber, comprising:

an upper wall and a lower wall that are both curved in x-z and y-z planes;

at least one side wall connecting the upper and lower walls such that the at least one side wall and the upper and lower walls confine a chamber space; and

a reinforcement extending along the entire interior perimeter of the chamber space to prevent outward expansion of the chamber.

35. The chamber of claim 34, wherein the reinforcement includes at least one support plate joined to an inner surface of the chamber.

36. The chamber of claim 35, wherein the at least one support plate is an annular support.

37. The chamber of claim 35, wherein a plurality of support plates defines an opening therein.

38. A processing chamber having an upstream end and a downstream end defining a longitudinal axis of the chamber, and a lateral axis perpendicular to the longitudinal axis, the chamber comprising:

outwardly curved upper and lower walls, each wall being substantially rectangular when viewed from above, wherein each wall is outwardly curved along both its longitudinal and lateral axes; and

side walls connecting the upper and lower walls, wherein the side walls are substantially flat plates.

39. The chamber of claim 38, wherein the side walls extend vertically between the upper and lower walls.

40. The chamber of claim 39, wherein the side walls include an inlet flange at the upstream end and an outlet flange at the downstream end.

41. The chamber of claim 40, wherein the inlet and outlet flanges each have upwardly and downwardly curved segments to mate with the upper and lower dome walls.

42. The chamber of claim 38, wherein the side walls include lateral side rails having upper and lower curved edges to mate with the upper and lower walls.

43. The chamber of claim 41, further comprising an internal reinforcement extending continuously along the internal perimeter of the chamber.

44. The chamber of claim 43, wherein the internal reinforcement comprises at least one support plate extending from an inner surface of the side walls.

45. A processing chamber having an upstream end and a downstream end and lateral sides extending therebetween, comprising:

an upper wall extending a length in a y dimension between the upstream and downstream ends, a width in an x dimension between the lateral sides, and a height in a z dimension, the upper wall having a substantially convex outer surface and being formed of a substantially non-reactive light transmissive material;

a lower wall extending a length in the y dimension, a width in the x dimension, and a height in the z dimension, the lower wall having a substantially convex outer surface and being formed of a substantially non-reactive light transmissive material;

at least one side wall connecting the upper wall to the lower wall to define a chamber space therebetween, the at least one side wall defining an outer periphery of the chamber space and being formed of a substantially non-reactive light transmissive material; and

an external reinforcement extending substantially entirely around the outer periphery of the chamber space to confine outward expansion of the chamber;

wherein the at least one side wall is made of translucent quartz.

46. The chamber of claim 45, wherein the external reinforcement is made of metal.

47. The chamber of claim 45, wherein the upper wall and the lower wall are made of substantially transparent quartz.

48. The chamber of claim 45, wherein the upper and lower walls are substantially circular when viewed from above.

49. The chamber of claim 45, wherein the upper and lower walls are substantially rectangular when viewed from above.

50. A processing chamber having an upstream end and a downstream end and lateral sides extending therebetween, comprising:

an upper wall extending a length in a y dimension between the upstream and downstream ends, a width in an x dimension between the lateral sides, and a height in a z dimension, the upper wall having a substantially convex outer surface and being formed of a substantially non-reactive light transmissive material;

a lower wall extending a length in the y dimension, a width in the x dimension, and a height in the z dimension, the lower wall having a substantially convex outer surface and being formed of a substantially non-reactive light transmissive material;

at least one side wall connecting the upper wall to the lower wall to define a chamber space therebetween, the at least one side wall defining an outer periphery of the chamber space and being formed of a substantially non-reactive light transmissive material; and

an external reinforcement extending substantially entirely around the outer periphery of the chamber space to confine outward expansion of the chamber;

wherein the at least one side wall includes a pair of side rails at the lateral sides of the chamber, an inlet flange at the upstream end of the chamber and an outlet flange at the downstream end of the chamber.

51. The chamber of claim 50, wherein the external reinforcement includes retaining beams at the lateral sides of the chamber and retaining flanges at the upstream and downstream ends of the chamber.

52. The chamber of claim 45, wherein the upper and lower walls have outer surface that are outwardly curved in x-z and y-z planes.

53. A processing chamber having an upstream end and a downstream end and lateral sides extending therebetween, comprising:

an upper wall extending a length in a y dimension between the upstream and downstream ends, a width in an x dimension between the lateral sides, and a height in a z dimension, the upper wall having a substantially convex outer surface and being formed of a substantially non-reactive light transmissive material;

a lower wall extending a length in the y dimension, a width in the x dimension, and a height in the z dimension, the lower wall having a substantially convex outer surface and being formed of a substantially non-reactive light transmissive material;

at least one side wall connecting the upper wall to the lower wall to define a chamber space therebetween, the at least one side wall defining an outer periphery of the chamber space and being formed of a substantially non-reactive light transmissive material;

an external reinforcement extending substantially entirely around the outer periphery of the chamber space to confine outward expansion of the chamber; and

an interior reinforcement connected to the at least one side wall at the outer periphery of the chamber space to resist outward deformation of the at least one side wall and flattening deformation of the upper and lower walls when the chamber is subjected to an external pressure greater than the pressure within the chamber.

54. The chamber of claim 53, wherein the interior reinforcement is an annular support plate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to reaction chambers for high temperature processing of semiconductor wafers. More particularly, the invention relates to a compact process chamber capable of withstanding stresses associated with high temperature, low pressure processes, and having an improved service life.

2. Description of the Related Art

Reaction chambers used for semiconductor processing generally employ radiant heaters positioned on the exterior of the chamber to heat a wafer located within the chamber. The wafer is typically separated from the heaters by chamber walls, which prevent the release of the processing gases into the ambient environment. These walls are desirably made of a transparent material to allow the radiant heat to pass through the walls and heat only the wafer. This material must also be able to withstand the very high temperatures used in processing semiconductor wafers. In addition, the chamber walls are desirably made from an inert material that does not react with the processing gases at the operative temperature. Furthermore, the material used for the chamber walls desirably has high purity characteristics to minimize contamination of the chamber that impedes the wafer processing. Quartz or a similar material is popular for use in chamber walls for exhibiting the foregoing properties.

For applications in which the pressure within a quartz chamber is to be reduced much lower than the surrounding ambient pressure, cylindrical or spherical chambers have been preferred from a strength standpoint because their curved outward surfaces can aid in withstanding inwardly direct force. A dome-shaped chamber has been described in U.S. Pat. No. 5,085,887, entitled WAFER REACTOR VESSEL WINDOWS WITH PRESSURE-THERMAL COMPENSATION, and in U.S. Pat. No. 5,108,792, entitled DOUBLE-DOME REACTOR FOR SEMICONDUCTOR PROCESSING, both of which have been assigned to Applied Materials, Inc. This chamber includes an upper wall having a convex outer surface and a concave inner surface. A greatly thickened peripheral flange is provided that radially confines the upper wall to cause the wall to bow outward due to thermal expansion, helping to resist the exterior ambient pressure in vacuum applications. The chamber requires a complex mechanism for clamping the thickened exterior flanges of the upper and lower chamber walls. In particular, the flange portion is secured between base plates and clamping plates and is sealed with O-rings.

A problem with double-dome chambers as described above is that such chambers typically have an abundance of metallic surfaces. As noted, the domes of the chambers are sealed to metal base plates and clamping plates through O-rings. These metal plates are necessary to provide the chamber with sufficient strength to prevent the top and bottom domes from bending. A disadvantage of this design is that the metallic surfaces of the plates and the O-rings come into contact with the processing gases and, if not adequately coated, are subject to elevated temperature and low pressure conditions. Specifically, metal found within an IR field absorbs heat, thereby requiring more power to heat the wafer, wafer holder and/or slip ring. Consequently, the metal ring is difficult to cool. Moreover, the O-rings have a tendency to deteriorate when exposed to chemicals at high temperatures. The existence of non-quartz or other non-inert surfaces in contact with the interior of the reaction chamber in close proximity to the wafer may lead to the introduction of contaminants on the wafer by reaction of the surfaces with the processing gases.

A lenticular chamber for processing of semiconductor wafers is described in pending application titled PROCESS CHAMBER WITH INNER SUPPORT, Ser. No. 08/637,616, filed Apr. 25, 1996, now U.S. Pat. No. 6,093,252. This chamber has thin upper and lower curved quartz walls having a convex exterior surface and a concave interior surface. These walls are welded to mate at their side edges to two quartz side rails, thus giving the chamber a generally flattened or ellipsoidal cross-section. The two side rails and an internal quartz plate provided within the chamber prevent the upper and lower walls from bending. End flanges welded to the side rails and upper and lower walls are made from translucent quartz. Thus, the lenticular chamber reduces the amount of metal exposed to the interior of the chamber, as compared to the chambers of the '887 and '792 patents.

Despite these advantages, there are certain disadvantages of the above-described lenticular chamber. For instance, upscaling the lenticular chamber to larger sizes is difficult. The lenticular chamber is rectangular because O-rings located at the longitudinal ends of the chamber should be kept farther away from the center of the chamber where the wafer is located. These O-rings have a tendency to heat up, and therefore, if located too close to the extreme temperatures at the center of the chamber, they will become difficult to cool and may deteriorate more easily due to thermal stresses. Moreover, a rectangular shape is desired for the lenticular chamber to more evenly distribute gas flow through the chamber. By providing a longer longitudinal distance for gas to flow over the wafer to be processed, the gas can spread out in the chamber before reaching the wafer, thereby allowing a more uniform deposition. Therefore, to upscale the design to larger sizes requires maintaining rectangular proportions in the chamber. Also, the non-symmetrical design of the chamber is not favorable to vertical gas flow, for example, when gas flow is provided through an inlet above the wafer.

Such a chamber used to process, for example, 300 mm wafers, would be extremely big and heavy, and difficult to fabricate, requiring special cranes and lifting devices. This increase in size also decreases the amount of clean room space available. Furthermore, the larger size also makes the chamber more difficult to clean.

Accordingly, a need exists for a reaction chamber for semiconductor processing that minimizes the amount of metallic and other heat-absorbing and contaminating materials in the reaction chamber. Desirably, the chamber should be compact and have sufficient strength to be used in low pressure, high temperature environments.

SUMMARY OF THE INVENTION

The above needs are satisfied by the process chambers described hereinbelow. Briefly stated, the preferred embodiments are constructed such that the process chamber has an interior surface of all-quartz or similar material. The chamber has thin upper and lower walls made from a generally transparent material, such as quartz, each preferably having a convex exterior surface and a concave interior surface. These walls are joined at their edges to a side wall or walls, preferably formed from a generally translucent material such as bubble quartz. The upper and lower walls and the side walls substantially enclose an all-quartz interior surface, except for apertures used for gas inlet and outlet and wafer transfer. An internal reinforcement extends from the inner surface of the side wall around the entire internal perimeter of the chamber to provide additional strength and support to the chamber.

As used herein, description of an all-quartz interior chamber surface refers to the enclosing surfaces of the chamber, such as the upper and lower walls and side wall, and not to the fixtures such as the slip ring and susceptor found inside the chamber. The illustrated all-quartz construction minimizes the metallic and non-quartz surfaces in the chamber, thereby making the chamber easier to cool and requiring less power consumption to heat the wafer and slip ring located inside the chamber. The use of substantially all-quartz surfaces also reduces contaminants within the chamber and alleviates fracturing of non-quartz parts due to the high temperature, low pressure environment. In one embodiment, the chamber also has a generally cylindrical, double-dome like shape so that it can be made smaller than rectangular chambers used for processing the same wafer size. This shape also provides better strength to the chamber while enabling either transverse and/or axial gas flow for a more uniform deposition.

In one aspect of the present invention, a processing chamber is provided comprising an upper wall having a convex outer surface and a concave inner surface. A lower wall is spaced from the upper wall having a convex outer surface and a concave inner surface. Both the upper wall and the lower wall extend a length in a y dimension, a width in an x dimension and a height in a z dimension. Both these walls are curved in both x-z and y-z planes. At least one side wall having an inner surface and an outer surface connects the upper wall to the lower wall, wherein the upper wall, lower wall and the at least one side wall together substantially enclose a chamber space having all-quartz enclosing surfaces. An external reinforcement is provided on at least part of the outer surface of the at least one side wall to confine outward expansion of the chamber.

In another aspect of the present invention, the processing chamber comprises a quartz upper dome wall and a quartz lower dome wall spaced from the upper dome wall. Each dome wall has a convex outer surface and a concave inner surface. A generally cylindrical quartz side wall having an inner surface and an outer surface connects the upper and lower dome walls and defines a chamber space therebetween. A retainer surrounds at least a portion of the outer surface of the side wall to confine outward expansion of the chamber. The chamber space is substantially enclosed only by the inner surfaces of the dome wall and the inner surface of the side wall.

In another aspect of the present invention, a processing chamber having an upstream end and a downstream end and lateral sides extending therebetween is provided. The chamber comprises an upper wall and a lower wall spaced from the upper wall, each wall being outwardly curved in both a lateral and a longitudinal direction. A plurality of side walls connects the upper and lower walls. The plurality of side walls includes an inlet flange connecting the upper and lower walls at the upstream end of the chamber, an outlet flange connecting the upper and lower walls at the downstream end of the chamber, and side rails connecting the upper and lower walls at the lateral sides of the chamber and connecting the inlet and outlet flanges between the upstream and downstream ends of the chamber. An external reinforcement is provided along at least a portion of the plurality of side walls to confine outward expansion of the chamber. The chamber has a substantially all-quartz interior surface defined by the upper and lower walls and the plurality of side walls.

In another aspect of the present invention, a chamber for processing semiconductor wafers and the like is provided. The chamber comprises outwardly convex upper and lower walls each having outer and inner surfaces and being curved in a lateral and a longitudinal direction. At least one side wall connects the upper and lower walls, the at least one side wall having inner surfaces that are substantially flush with the inner surfaces of the upper and lower walls at the connection between the edges of the at least one side wall and the upper and lower walls. The upper and lower walls and the at least one side wall enclose a chamber space having a substantially continuous inner surface formed of a nonreactive substantially light-transmissive material.

In another aspect of the present invention, the processing chamber comprises an upper wall and a lower wall that are both curved in x-z and y-z planes. At least one side wall connects the upper and lower walls such that the at least one side wall and the upper and lower walls confine a chamber space. A reinforcement extends along the entire interior perimeter of the chamber space to prevent outward expansion of the chamber.

In another aspect of the present invention, a processing chamber is provided having an upstream end and a downstream end defining a longitudinal axis of the chamber, and a lateral axis perpendicular to the longitudinal axis. The chamber comprises outwardly curved upper and lower walls, each wall being substantially rectangular when viewed from above. Each wall is outwardly curved along both its longitudinal and lateral axes. Side walls connect the upper and lower walls.

In another aspect of the present invention, a processing chamber having an upstream end and a downstream end and lateral sides extending therebetween is provided. An upper wall extends a length in a y dimension between the upstream and downstream ends, a width in an x dimension between the lateral sides, and a height in a z dimension. A lower wall also extends a length in the y dimension, a width in the x dimension, and a height in the z dimension. The upper wall and the lower wall each has a substantially convex outer surface and is formed of a substantially non-reactive light transmissive material. At least one side wall connects the upper wall to the lower wall to define a chamber space therebetween. The at least one side wall thereby defines an outer periphery of the chamber space and is formed of a substantially non-reactive light transmissive material. An external reinforcement extends substantially entirely around the outer periphery of the chamber space to confine outward expansion of the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a process chamber constructed in accordance with a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the process chamber, taken along lines 2--2, of FIG. 1.

FIG. 3 is a cross-sectional view of the process chamber, taken along lines 3--3, of FIG. 1.

FIG. 4 is a top schematic view of the process chamber of FIG. 1, showing the orientation of the chamber components.

FIG. 5 is a perspective view of a process chamber constructed in accordance with a second embodiment of the present invention.

FIG. 6 is an exploded perspective view of the process chamber of FIG. 5.

FIG. 7 is a top elevation view of the process chamber of FIG. 5.

FIGS. 8 and 9 are side views of the process chamber of FIG. 5.

FIG. 10 is a perspective view of a process chamber constructed in accordance with a third embodiment of the present invention.

FIG. 11 is an exploded perspective view of the process chamber of FIG. 10.

FIG. 12 is a top elevation view of the process chamber of FIG. 10.

FIGS. 13 and 14 are side views of the process chamber of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. First Preferred Embodiment

Referring generally to FIGS. 1-4, one preferred embodiment of a reactor vessel or processing chamber 10 for chemical vapor deposition, etching, annealing and the like is illustrated. As can be seen, upper wall 12 is has an outwardly curved shape and has a generally circular cross-section when viewed from above. With reference to FIGS. 2 and 3, the chamber 10 includes an upper quartz dome wall 12 with an outer convex surface and an inner concave surface, and a lower quartz dome wall 14 with an outer convex surface and an inner concave surface. The dome walls are connected by a side wall 16 which extends around the circumference of the chamber 10 and is attached to the rims of the upper and lower walls. The side wall 16 includes an upstream inlet flange 18 and a downstream outlet flange 20. Upstream and downstream relate to the direction of process gas flow, as will be described, and are synonymous in the present description with front and rear. An external reinforcement or retainer 38 is optionally provided surrounding the side wall 16, as will be described below.

The chamber height is preferably less than the chamber diameter. In this respect, a longitudinal or y direction for the chamber 10 extends from the inlet flange 18 to the outlet flange 20, or along section line 3--3. A lateral or x direction extends perpendicular to the longitudinal direction, or along section line 2--2. The height or z direction is perpendicular to both the longitudinal and lateral axes.

As shown in FIGS. 2 and 3, within the chamber 10, an interior reinforcement 30 extends from the side wall 16 to provide additional support to the chamber. A wafer holder or susceptor 50 is supported on rotating shaft 60, which extends through a tube 62 depending from lower wall 14. A temperature compensation or slip ring 52 surrounds the susceptor 56 within an opening defined by the reinforcement 30. Horizontal, laminar gas flow is provided from the upstream end of the chamber 10 at inlet flange 18, as directed through gas inlet 66 and slot 64. An alternative or secondary gas inlet 70 is provided from the upper wall 12 of the chamber 10 to enable axial gas flow.

With these general design principles in mind, further details regarding the first preferred embodiment are presented below.

Chamber Walls

The upper wall 12 and lower wall 14 of the chamber 10 are preferably formed a material resistant to thermal stress and transparent to certain ranges of radiant energy. More preferably, the upper and lower walls are made from a transparent quartz material. In the preferred embodiment, the inner and outer surfaces of these walls are curved in both the lateral and longitudinal dimensions, i.e., in both the x-z and y-z planes. More preferably, the upper and lower walls have an outward curvature in substantially all of the planes parallel to the z-axis of the chamber, thereby giving the walls the dome-like shape as illustrated. As shown in FIG. 4, these walls appear circular when viewed from above. The walls preferably have a convex outer surface and a concave inner surface. The upper and lower walls 12 and 14 of the chamber 10 are preferably constructed by hot forming and/or machining. In larger chambers, the walls 12 and 14 may be constructed from flat plates that are subsequently heated and formed.

It will be appreciated that other shapes may be used for the walls 12 and 14. Furthermore, while the upper and lower walls are preferably symmetrical, walls of different dimension with differing radii of curvature may also be used. It is conceivable as well that only the outer surfaces of the upper and lower dome walls be curved, or that one of the walls have no curvature at all.

As shown in FIGS. 2 and 3, the side wall 16 includes a reinforced main body having preferably a substantially cylindrical outer surface 22 which is curved to form a continuation of the curved outer surfaces of the upper wall 12 and the lower wall 14. The side wall 16 thus extends circumferentially around the interior of the chamber 10, connecting to the rims of the upper dome wall 12 and lower dome wall 14. At the inlet and outlet ends of the chamber 10, the side wall 16 is rectangularly shaped, as shown in FIGS. 3 and 4, to define inlet and outlet flanges 18, 20, respectively, having apertures for wafer transfer and gas inlet and outlet, described in further detail below. The inner surface of the side wall 16 is formed with longitudinally extending upper and lower recesses 24a, 24b, that create upper, middle and lower stub wall segments 26a, 26b and 26c, respectively. The upper and lower stub wall segments 26a, 26c mate with the side edges of the upper and lower walls 12 and 14 at longitudinal weld joints 28 to form substantially flush surfaces therebetween.

The side wall 16 is preferably translucent and fabricated from quartz having nitrogen bubbles dispersed therein. The translucent side wall 16 scatters radiant energy to reduce "light-piping" therethrough. This protects O-rings and other parts outside the chamber from exposure to extreme temperatures generated within the chamber. The side wall 16 is preferably constructed by machining.

As seen in FIG. 2, the upper and lower walls 12, 14 are preferably thin plates having an outward convex configuration. In one embodiment, to process a wafer with a diameter of 200 mm, these walls 12 and 14 preferably have a thickness of about 5 mm. Accordingly, because stub wall segments 26a and 26c of the side wall 16 mate with the upper and lower walls 12 and 14, respectively, these stub segments in this embodiment also have a thickness of about 5 mm. Between the stub segments 26a and 26c, the side wall 16 increases in thickness to provide strength and support to the chamber and to resist outward expansion of the upper and lower walls. The central stub segment 26b extending towards the interior of the chamber preferably has a thickness greater than that of the stub segments 26a and 26b and walls 12, 14, and for the exemplary embodiment, is about 10 mm.

In the illustrated embodiment, the upper and lower dome walls 12 and 14 each preferably has a constant radius of curvature of about 50 to 100 cm, thereby giving the walls a substantially curved shape. These walls are spaced apart by the side wall 16 which preferably has a height of about 5 cm, an inner diameter of about 40 cm and an outer diameter of about 50 cm.

The dimensions for the chamber will obviously be modified for larger size wafers. For example, the present chamber invention is suitable for processing wafers having diameters of 200 mm, 300 mm and even larger. Preferably, the relative cross-sectional dimensions will remain the same, and thus a larger diameter chamber to accommodate 300 mm wafers will have a larger height. The increased height in the chamber for 300 mm wafers will necessitate certain modifications to other subsystems, such as radiant heat lamps disposed around the chamber for heating the susceptor and wafer, described below. In short, although the surrounding environments for processing 200 mm and 300 mm diameter wafers may necessarily differ in certain respects, these differences are within the skill of one practiced in the art of process chamber construction and operation. The particular dimensions are, of course, given merely by way of example.

As described above, the upper and lower walls of the chamber 10 in the first preferred embodiment are constructed entirely out of a light-transmissive material such as quartz. the side wall is preferably made from bubble quartz to minimize heat losses. Thus, the upper wall 12, lower wall 14, and side wall 16 enclose a chamber space having a substantially all-quartz interior surface except for apertures for wafer transfer and gas inlet and outlet. Quartz is the preferred material for the dome walls and the side wall because of its transparency and temperature resistance to the radiant lamps used to heat the wafers. An all-quartz configuration is also much easier to cool than a chamber which contains non-quartz components. In addition, quartz is a nonreactive material that does not degrade easily. Other materials may react with the gases introduced into the chamber, thereby producing contaminants while creating structural problems in these non-quartz components. Although quartz is preferred, other materials having similar desirable characteristics may be substituted. Some of these desirable characteristics include a high melting point, the ability to withstand large and rapid temperature changes, chemical inertness, and high transparency to light.

Inner Chamber Support

As shown in FIGS. 2 and 3, an internal reinforcement 30 is provided within the chamber 10. In the preferred embodiment, the internal reinforcement is a support plate which mates with stub wall segment 26b at longitudinal weld joint 36. The support plate therefore extends entirely around the internal circumference of the chamber. The support plate 30 preferably has the same thickness as stub 26b to form substantially continuous or flush surfaces therebetween. Therefore, in the exemplary embodiment described above, both the support plate 30 and the wall segment 26b have the same thickness of about 10 mm.

The support plate 30 is preferably formed of the same material used to form the side wall 16 and is constructed by machining. The support plate 30 is preferably made from quartz. The plate 30 provides additional strength and support to the chamber 10 because, by extending from or being fixed to the inner surface of the side wall 16, the plate confines the outward expansion of the side wall 16 during low pressure applications. Furthermore, by constructing this plate from a material such as quartz, this plate will not heat excessively during processing or react or cause contamination to the chamber. While the preferred embodiment has been describ