Systems and methods for radiant heat caps in semiconductor wafer reactors

Abstract

The reaction device contacts a process gas onto a semiconductor wafer during the wafering process. The semiconductor wafer defines a central region. The reaction device includes an upper dome, a lower dome, a shaft, and a cap. The lower dome is attached to the upper dome, and the upper dome and the lower dome define a reaction chamber. The cap is positioned on the shaft within the reaction chamber to reduce the heat absorbed by the central region of the semiconductor wafer. The cap is attached to the first end of the shaft. The cap includes a tube and a disc. The tube defines a tube diameter larger than the shaft diameter of the shaft. The tube surrounds the first end of the shaft. The disc is attached to the tube and is positioned to block radiant heat from heating the central region of the semiconductor wafer.

Description

Technology Field

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 139,387, filed December 31, 2020, the entire disclosure of which is incorporated herein by reference.

[0003] Field of invention

[0004] The present field generally relates to apparatuses and methods for wafer processing, and more specifically, to apparatuses and methods for semiconductor wafer etching or semiconductor wafer chemical vapor deposition processes. Background Technology

[0005] Epitaxial Chemical Vapor Deposition (CVD) is a process for growing a thin layer of material on a semiconductor wafer such that the lattice structure is identical to the lattice structure of the wafer. Epitaxial CVD is widely used in semiconductor wafer production to build epitaxial layers so that devices can be fabricated directly on the epitaxial layers. The epitaxial deposition process begins by preheating and cleaning the front surface of the wafer (i.e., the surface facing away from the susceptor) by introducing a cleaning gas, such as hydrogen or a mixture of hydrogen and hydrogen chloride. The cleaning gas removes native oxides from the front surface, allowing the epitaxial silicon layer to grow continuously and uniformly on the surface during subsequent steps of the deposition process. The epitaxial deposition process continues by introducing a vapor silicon source gas, such as silane or chlorinated silane, to the front surface of the wafer to deposit and grow an epitaxial silicon layer on the front surface. The back surface, opposite to the front surface of the susceptor, may be simultaneously exposed to hydrogen gas. During epitaxial deposition, the susceptor supporting the semiconductor wafer in the deposition chamber is rotated during the process to allow the epitaxial layer to grow evenly.

[0006] However, epitaxial CVD growth rates are generally non-uniform across the surface of each wafer due to the non-uniform temperature profile of the semiconductor wafer. This lack of uniformity leads to a degradation of wafer flatness and may result from variability or local temperature variations within the semiconductor wafer caused by non-uniform heating of the wafer by high-intensity lamps. Therefore, a practical and cost-effective device is required to mitigate local temperature variations in order to improve the uniformity of epitaxial CVD growth rates.

[0007] This Background Section is intended to introduce to the reader various aspects of the technology that may be related to various aspects of the present disclosure described and / or claimed below. It is believed that this discussion will help provide the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, these descriptions should be read in light of this and should not be accepted as prior art. means of solving the problem

[0008] In one embodiment, a reaction device is provided for contacting a process gas onto a semiconductor wafer during a wafering process. The semiconductor wafer defines a central region. The reaction device comprises an upper dome, a lower dome, a shaft, and a cap. The lower dome is attached to the upper dome, and the upper dome and the lower dome define a reaction chamber. The shaft supports the semiconductor wafer within the reaction chamber. The cap is positioned on the shaft within the reaction chamber to reduce heat absorbed by the central region of the semiconductor wafer. The cap is attached to a first end of the shaft. The cap comprises a tube and a disc. The tube defines a tube diameter larger than the shaft diameter of the shaft. The tube surrounds the first end of the shaft. The disc is attached to the tube and positioned to block radiant heat from heating the central region of the semiconductor wafer.

[0009] In another embodiment, a cap positioned on the shaft of a reaction device is provided to reduce heat absorbed by the central region of a semiconductor wafer during a wafering process. The cap comprises a tube and a disc. The tube defines a tube diameter larger than the shaft diameter of the shaft. The tube surrounds a first end of the shaft. The disc is attached to the tube to block radiant heat from heating the central region of the semiconductor wafer.

[0010] In yet another embodiment, a method for manufacturing a semiconductor wafer in a reaction apparatus is provided. The reaction apparatus comprises an upper dome and a lower dome defining a reaction chamber, and a shaft for supporting the semiconductor wafer. The reaction apparatus further comprises a cap positioned on the shaft within the reaction chamber to reduce heat absorbed by the central region of the semiconductor wafer. The cap comprises a tube and a disc attached to the tube. The method comprises the step of channeling a process gas into the reaction chamber. The method also comprises the step of heating the semiconductor wafer with a high-intensity lamp positioned within the reaction chamber. The method further comprises the step of using a disc to block radiant heat from the high-intensity lamp from heating the central region of the semiconductor wafer. The disc creates a uniform temperature distribution on the semiconductor wafer. The method also comprises the step of depositing a layer on the semiconductor wafer with the process gas. The uniform temperature distribution forms a uniform thickness of the layer on the semiconductor wafer.

[0011] Various improvements to the features mentioned in connection with the embodiments described above of the present disclosure exist. Additional features may also be included in the embodiments described above of the present disclosure. These improvements and additional features may exist individually or in any combination. For example, various features discussed below in connection with any of the embodiments illustrated in the present disclosure may be included in any of the embodiments described above of the present disclosure, either individually or in any combination. Brief explanation of the drawing

[0012] Figure 1 is a front view of a device for processing a substrate such as a semiconductor wafer. Figure 2 is a perspective view of the device shown in Figure 1. Figure 3 is a cross-sectional view of the device shown in Figure 1. Figure 4 is an exploded perspective view of the device shown in Figure 1. FIG. 5 is a perspective view of a cap located on the shaft shown in FIG. 3. FIG. 6 is a perspective view of the cap shown in FIG. 3 to FIG. 5. Figure 7 is a side view of the disk shown in Figure 6. Figure 8 is a plan view of the disk shown in Figure 6. Fig. 9 is a side view of the tube shown in Fig. 6. Figure 10 is a plan view of the tube shown in Figure 6. Figure 11 is a flowchart of a method for manufacturing a semiconductor wafer in a reaction apparatus shown in Figure 1. Figure 12 is a graph of the epitaxial wafer radial temperature as a function of wafer radial distance according to Example 1. Corresponding reference characters across the drawings indicate corresponding parts. Specific details for implementing the invention

[0013] Referring now to FIG. 1, an apparatus for etching a semiconductor wafer or depositing an epitaxial layer on a semiconductor substrate according to an embodiment of the present disclosure is generally referred to as 100. The illustrated apparatus is a single wafer reactor; however, to provide a more uniform epitaxial layer, the apparatus and methods disclosed herein are suitable for use in other reactor designs, for example, including multiple wafer reactors. The apparatus (100) comprises a reaction chamber (102) comprising an upper dome (104), a lower dome (106), an upper liner (108), and a lower liner (110). Collectively, the upper dome (104), the lower dome (106), the upper liner (108), and the lower liner (110) define an internal space (112) of the reaction chamber (102) where the process gas comes into contact with the semiconductor wafer (114). A gas manifold (116) is used to direct the process gas into the reaction chamber (102). A perspective view of the reaction chamber (102) and gas manifold (116) is shown in FIG. 2.

[0014] The apparatus (100) may be used to process a wafer in a wafering process, including but not limited to depositing any type of material on a wafer by a chemical vapor deposition (CVD) process, such as epitaxial CVD or polycrystalline CVD. In this regard, references to epitaxy and / or CVD processes in this specification should not be construed as limiting, as the apparatus (100) may be used for other purposes, such as performing etching or planarization processes on the wafer. Additionally, the wafers depicted herein are generally circular in shape, but wafers of other shapes are considered within the scope of this disclosure.

[0015] A cross-section of the device (100) is shown in FIG. 3. Within the internal space (112) of the reaction chamber (102), there is a preheating ring (118) for heating the process gas before contacting the semiconductor wafer (114). The outer surface of the preheating ring (118) is attached to the inner surface of the lower liner (110). For example, the preheating ring (118) may be supported by an annular protrusion (not shown) of the lower liner (110). A susceptor (120) (which may be referred to herein as the “susceptor body”) traversing the internal space up to the preheating ring (118) supports the semiconductor wafer (114).

[0016] The process gas can be heated before coming into contact with the semiconductor wafer (114). Both the preheating ring (118) and the susceptor (120) are generally opaque to absorb radiant heating light generated by high-intensity lamps (122, 124) that may be positioned above and below the reaction chamber (102) to heat the semiconductor wafer (114). Maintaining the preheating ring (118) and the susceptor (120) at a temperature higher than the surroundings allows the preheating ring (118) and the susceptor (120) to transfer heat to the process gas as the process gas passes over the preheating ring and the susceptor. Typically, the diameter of the semiconductor wafer (114) is smaller than the diameter of the susceptor (120) to allow the susceptor to heat the process gas before coming into contact with the wafer.

[0017] The preheating ring (118) and susceptor (120) may be suitably constructed of opaque graphite coated with silicon carbide, but other materials may also be considered. The upper dome (104) and lower dome (106) are typically made of a transparent material to allow radiant heating light to pass into the reaction chamber (102) and over the preheating ring (118) and susceptor (120). The upper dome (104) and lower dome (106) may be constructed of transparent quartz. Quartz is generally transparent to infrared and visible light and is chemically stable under the reaction conditions of the deposition reaction. Equipment other than high-intensity lamps (122, 124), such as resistance heaters and induction heaters, for example, may be used to provide heat to the reaction chamber. An infrared temperature sensor (not shown), such as a pyrometer, is mounted in the reaction chamber (102) and can monitor the temperature of the susceptor (120), the preheating ring (118), or the semiconductor wafer (114) by receiving infrared radiation emitted by the susceptor, the preheating ring, or the wafer.

[0018] Now, referring to FIGS. 3 through 5, in which some components of the device (100) have been removed to better illustrate the device, the device (100) includes a shaft (126) capable of supporting a susceptor (120). The shaft (126) extends through a central column (128). The shaft (126) includes a second end (130) attached to the central column (128) and a first end (132) located near a central region (134) of the semiconductor wafer (114). The shaft (126) has a shaft diameter (136) of about 5 millimeters (mm) to about 20 mm.

[0019] The shaft (126) is connected to a suitable rotation mechanism (not shown) for rotating the shaft (126), the susceptor (120), and the semiconductor wafer (114) about the longitudinal axis (X) relative to the device (100). The outer edge of the susceptor (120) and the inner edge of the preheating ring (118) (shown in FIG. 3) are separated by a gap (138) to allow rotation of the susceptor. The semiconductor wafer (114) is rotated to prevent excess material from being deposited on the wafer leading edge and to provide a more uniform epitaxial layer.

[0020] The device (100) also includes a cap (140) positioned on a shaft (126) within a reaction chamber (102) to reduce heat absorbed by the central region (134) of the semiconductor wafer (114). The cap (140) is attached to a first end (132) of the shaft (126) adjacent to the central region (134) of the semiconductor wafer (114) to block radiant heat from a lower high-intensity lamp (124) from heating the central region of the semiconductor wafer. Reducing radiant heat to the central region (134) of the semiconductor wafer (114) reduces the temperature of the central region while maintaining the temperature of the outer radiant regions (142) of the semiconductor wafer (114), thereby creating a uniform temperature profile of the semiconductor wafer.

[0021] The cap (140) comprises a tube (144) and a disc (146) attached to the tube. In the illustrated embodiment, the tube (144) and the disc (146) are formed integrally together so that the cap (140) has a single structure. In alternative embodiments, the tube (144) and the disc (146) may be formed separately and attached to each other. The tube (144) comprises a cylindrical wall (148) having a first end (150), a second end (152), and a tube length (154), and defining a tube conduit (156) and a tube diameter (158). The first end (150) defines a first end opening (160), and the second end (152) defines a second end opening (162). The tube diameter (158) is larger than the shaft diameter (136) so that the first end (132) of the shaft (126) is inserted into the first end opening (160) and the first end (150) surrounds the first end of the shaft. The second end (152) is attached to the disk (146).

[0022] The disc (146) includes an annular disc (164) defining a disc hole (166), an inner diameter (168), an outer diameter (170), and a disc thickness (172). The tube diameter (158) and the inner diameter (168) are the same or substantially the same, so that the cylindrical wall (148) is substantially the same height as the disc hole (166) and the tube conduit (156) and the disc hole define a cap conduit (174) through which the cap (140) extends. In alternative embodiments, the tube diameter (158) is larger than the inner diameter (168), and the tube conduit (156) and the disc hole (166) define the cap conduit (174).

[0023] The annular disk (164) has a first side (176) and a second side (178), and the first side of the annular disk is attached to the second end (152) of the tube (144). The first side (176) of the annular disk (164) faces the lower high-intensity ramp (124), and the second side (178) faces the central region (134) of the semiconductor wafer (114). The annular disk (164) can be attached to the tube (144) in any suitable manner. Additionally, the annular disk (164) may have other shapes, one or more recesses formed therein, and / or several openings formed therein.

[0024] The outer diameter (170) is larger than the tube diameter (158) and inner diameter (168) so that the annular disk (164) blocks radiant heat from the lower high-intensity lamp (124) from heating the central region of the semiconductor wafer. The annular disk (164) extends from the disk hole (166) and the cylindrical wall (148) so that the annular disk extends from the cylindrical wall and the disk hole by a blocking distance (180). The blocking distance (180) is configured to block a predetermined amount of radiant heat to create a uniform temperature profile of the semiconductor wafer (114).

[0025] The cap (140) is suitably made of an opaque material to block visible light and infrared light from being transmitted into the central region (134) of the semiconductor wafer (114). In other embodiments, instead of being opaque, the cap (140) may be made of a translucent material to provide local cooling to the semiconductor wafer (114) and to reduce any local or global maximum epitaxial layer thickness, thereby creating a uniform thickness profile of the epitaxial layer and / or the semiconductor wafer (114).

[0026] Generally, the cap (140) corrects and / or influences the radial temperature profile of the semiconductor wafer (114) during processing such as epitaxial deposition to mitigate non-uniformities. The cap (140) can reduce the amount of material (e.g., silicon) deposited in the center region of the semiconductor wafer (114) during epitaxial CVD processes by reducing the temperature of the center region (134) of the semiconductor wafer (114) over the cap (compared to when the cap is not used). Thus, the cap (140) is appropriately positioned at a distance below the center region (134) of the semiconductor wafer (114), where a local or global maximum layer thickness occurs to reduce deposition in the center region and create a more uniform radial deposition profile. It should be noted that this maximum layer thickness may be a local or global maximum and may generally be referred to as a non-uniformity.

[0027] The thickness profile may be determined by using any suitable method available to those skilled in the art, including, for example, the use of a Fourier transform infrared (FTIR) spectrometer or a wafer flatness tool (e.g., KLA-Tencor Wafersight or WaferSight2; Milpitas, California). In some embodiments, the radial thickness profile of the substrate may be determined before material deposition (e.g., before deposition of the epitaxial layer), and then the thickness profile of the layered structure may be measured. The thickness profile of the deposited layer may be determined by subtracting the substrate thickness from the thickness of the layered structure.

[0028] Specifically, in the illustrated embodiment, the tube length (154) is about 10 mm to about 30 mm; the tube diameter (158) is about 5 mm to about 20 mm; the inner diameter (168) is about 5 mm to about 20 mm; the outer diameter (170) is about 10 mm to about 40 mm; the disc thickness (172) is about 3 mm to about 10 mm; and the blocking distance (180) is about 5 mm to about 35 mm. In alternative embodiments, the shaft diameter (136), tube length (154), tube diameter (158), inner diameter (168), outer diameter (170), disc thickness (172), and blocking distance (180) may be any distance that enables the cap (140) to operate as described herein. More specifically, the shaft diameter (136), tube length (154), tube diameter (158), inner diameter (168), outer diameter (170), disk thickness (172), and blocking distance (180) are appropriately selected according to the location and size of the local or global epitaxial layer thickness minimum or maximum.

[0029] The distance (182) between the cap (140) and the susceptor (120) is less than about 40 mm, less than about 20 mm, or even less than about 1 mm. Reducing the distance (182) between the cap (140) and the susceptor (120) generally causes more material to be deposited on the wafer portions on the ring, and increasing the distance generally causes less deposition. Thus, the amount of material deposited on the wafer portions on the cap (140) can be adjusted by changing this distance.

[0030] The ranges described above for shaft diameter (136), tube length (154), tube diameter (158), inner diameter (168), outer diameter (170), disk thickness (172), blocking distance (180), distance (182), etc. are exemplary, and values ​​outside the mentioned ranges may be used without limitation. As illustrated in FIG. 8, the disk (146) has a substantially uniform circular shape. In other embodiments, the disk (146) may be formed to include various protrusions and / or notches or recesses. The disk (146) may also be inclined or rounded. These non-uniform shapes may cause the disk (146) to block radiant heat from the lower high-intensity lamp (124) from heating areas outside the central region (134) of the semiconductor wafer (114). For example, analysis of the temperature profile of the semiconductor wafer (114) can identify these regions having elevated temperatures that cause non-uniform deposition of material in regions outside the central region (134). The shape of the disk (146) can be adjusted to reduce material deposition in these regions by blocking radiant heat from the lower high-intensity lamp (124) from heating these regions.

[0031] FIG. 11 is a flowchart of a method (200) for manufacturing a semiconductor wafer in a reaction apparatus. The method (200) includes the step (202) of channeling a process gas into a reaction chamber. The method (200) also includes the step (204) of heating the semiconductor wafer with a high-intensity lamp located within the reaction chamber. The method (200) further includes the step (206) of blocking radiant heat from the high-intensity lamp from heating the central region of the semiconductor wafer using a disk. The disk creates a uniform temperature distribution on the semiconductor wafer. The method (200) also includes the step (208) of depositing a layer on the semiconductor wafer with the process gas. The uniform temperature distribution forms a uniform thickness of the layer on the semiconductor wafer.

[0032] Examples

[0033] The processes of the present disclosure are further explained by the following examples. However, these examples should not be construed in a limiting sense.

[0034] Example 1: Determination of the effect of using a cap on the radial temperature profile of a semiconductor wafer

[0035] The opaque cap described herein was tested in a single-wafer epitaxy reactor to determine its effect on the epitaxial wafer temperature profile. The epitaxial wafer was prepared by exposing a single-crystal silicon wafer produced by the Czochralski method to process gas at a wafer temperature of 1050°C to 1150°C. The disc of the cap had an outer diameter of 10 mm.

[0036] A control execution was performed without using a cap. FIG. 12 is a graph (300) of the epitaxial wafer radial temperature as a function of wafer radial distance. As can be seen in FIG. 12, the control caused a non-uniform epitaxial wafer radial temperature profile (302), and the cap caused a uniform epitaxial wafer radial temperature profile (304). The uniform epitaxial wafer radial temperature profile (304) is more uniform because the local temperature maximums at the ends of the profile are smaller than the local temperature maximums at the ends of the non-uniform epitaxial wafer radial temperature profile (302). Thus, the cap produced a uniform temperature profile of the epitaxial wafer.

[0037] Compared to conventional methods for producing silicon wafers, the systems and methods of the present disclosure have several advantages. For example, reactors comprising the described caps facilitate the cost-effective production of semiconductor wafers having a uniform temperature profile during deposition. A uniform temperature profile produces a more uniform deposition thickness profile. Thus, the caps enable the production of semiconductor wafers with a uniform thickness profile. An exemplary cap has a disk in or around the center of the wafer to block radiant heat from heating the center of the wafer. This reduces the temperature of the center, thereby producing a uniform temperature profile and a uniform thickness profile. Thus, the exemplary caps eliminate or reduce local temperature variations compared to the prior art to improve the uniformity of epitaxial CVD growth on the wafer. Furthermore, the use of the above examples can increase the production speed of the epitaxial CVD system and lower operating costs by reducing waste.

[0038] When introducing elements of the invention or its embodiments, the articles “a,” “an,” “the,” and “said” are intended to indicate that one or more elements exist. The terms “comprising,” “including,” “containing,” and “having” are inclusive and are intended to indicate that there may be additional elements other than those listed. The use of terms indicating specific orientations (e.g., “top,” “bottom,” “side,” etc.) is for convenience of explanation and does not require any specific orientation of the described item.

[0039] Since various modifications to the compositions and methods may be made without departing from the scope of the present disclosure, all contents included in the description and depicted in the attached drawings are intended to be interpreted as illustrative rather than restrictive.

Claims

Claim 1 A reaction device for contacting a process gas onto a semiconductor wafer during a wafering process, wherein the semiconductor wafer defines a central region, and the reaction device comprises: an upper dome; a lower dome attached to the upper dome, wherein the upper dome and the lower dome define a reaction chamber; a shaft for supporting the semiconductor wafer within the reaction chamber; and a cap positioned on the shaft within the reaction chamber to reduce heat absorbed by the central region of the semiconductor wafer, wherein the cap is attached to a first end of the shaft, and the cap comprises a tube defining a tube diameter larger than the shaft diameter of the shaft, wherein the tube surrounds the first end of the shaft; and a disc attached to the tube, wherein the disc is opaque to absorb radiant heat and positioned to block radiant heat from heating the central region of the semiconductor wafer, wherein the disc is positioned at a distance below the central region of the semiconductor wafer, and the disc includes an annular disc having an inner diameter that defines a disc hole, wherein the inner diameter is equal to the diameter of the tube. Claim 2 A reaction device according to claim 1, further comprising a lower high-intensity lamp located below the cap in the reaction chamber to heat the semiconductor wafer, wherein the disk blocks radiant heat from the lower high-intensity lamp from heating the central region of the semiconductor wafer. Claim 3 In claim 1, the wafering process is an epitaxial chemical vapor deposition reaction device. Claim 4 A reaction device according to claim 1, wherein the disk is positioned at a distance below the center region of the semiconductor wafer, and the distance is less than 5 millimeters. Claim 5 A method for manufacturing a semiconductor wafer in a reaction apparatus, wherein the reaction apparatus comprises an upper dome and a lower dome defining a reaction chamber and a shaft supporting the semiconductor wafer, wherein the reaction apparatus further comprises a cap positioned on the shaft within the reaction chamber to reduce heat absorbed by a central region of the semiconductor wafer, wherein the cap comprises a tube and a disk attached to the tube, and the method comprises: channeling a process gas into the reaction chamber; heating the semiconductor wafer with a high-intensity lamp located within the reaction chamber; and blocking radiant heat from the high-intensity lamp from heating the central region of the semiconductor wafer with the disk, wherein the disk is made of an opaque material to absorb radiant heat generated by the high-intensity lamp, and the disk creates a uniform temperature distribution on the semiconductor wafer, and the disk comprises an annular disk having an inner diameter defining a disk hole, wherein the inner diameter is equal to the diameter of the tube. A method comprising the step of depositing a layer on the semiconductor wafer with the process gas—the uniform temperature distribution forms a uniform thickness of the layer on the semiconductor wafer. Claim 6 In paragraph 5, the deposition step is carried out by epitaxial chemical vapor deposition. Claim 7 A method according to claim 5, further comprising the steps of rotating the semiconductor wafer with respect to the reaction device. Claim 8 A reaction device for contacting a process gas onto a semiconductor wafer during a wafering process, wherein the semiconductor wafer defines a central region, and the reaction device comprises: an upper dome; a lower dome attached to the upper dome, wherein the upper dome and the lower dome define a reaction chamber; a susceptor for supporting the semiconductor wafer within the reaction chamber, wherein the susceptor is supported by a shaft; a cap located on the shaft within the reaction chamber to reduce heat absorbed by the central region of the semiconductor wafer, wherein the cap is attached to a first end of the shaft, and the cap comprises a tube defining an outer diameter and an inner diameter of the tube that are larger than the shaft diameter of the shaft, wherein the tube surrounds the first end of the shaft. A reaction apparatus comprising: a disc attached to the tube—the disc defines the outer diameter of the disc, the outer diameter of the disc is larger than the outer diameter of the tube, the disc is generally opaque to absorb radiant heat and is positioned to block the radiant heat from heating the central region of the semiconductor wafer, and the disc is positioned at a distance from the central region of the semiconductor wafer and below the susceptor—; and a temperature sensor mounted on the reaction chamber—the temperature sensor is detached from the cap. Claim 9 A reaction device according to claim 8, further comprising a lower high-intensity lamp located below the cap in the reaction chamber to heat the semiconductor wafer, wherein the disk blocks radiant heat from the lower high-intensity lamp from heating the central region of the semiconductor wafer. Claim 10 In claim 8, the wafering process is an epitaxial chemical vapor deposition reaction device. Claim 11 In claim 8, the reaction device comprises a disk including an annular disk defining a disk hole, wherein the disk hole has a diameter, and the outer diameter of the disk is larger than the diameter of the disk hole. Claim 12 In paragraph 11, a reaction device wherein the inner diameter of the tube is substantially the same as the diameter of the disk hole. Claim 13 In claim 8, the reaction device wherein the disk is positioned at a distance of less than 5 millimeters below the central region of the semiconductor wafer. Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete

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