PROCESS FOR MANUFACTURING A SILICON CARBIDE COATED BODY

Abstract

The present invention relates to a new process for manufacturing a silicon carbide (SiC) coated body by depositing SiC in a chemical vapor deposition method using dimethyldichlorosilane (DMS) as the silane source on a graphite substrate. A further aspect of the present invention relates to the new silicon carbide coated body, which can be obtained by the new process of the present invention, and to the use thereof for manufacturing articles for high temperature applications, susceptors and reactors, semiconductor materials, and wafer.

Claims

1. A method of manufacturing a purified graphite member and modifying surface porosity thereof, comprising: providing a porous graphite member having an open porosity and comprising pores with an initial average pore diameter in a range of 0.4-5.0 m and comprising pores with an initial surface pore diameter of <10 m, and having an initial average grain size of <0.05 mm; locating the porous graphite member in a furnace and flowing nitrogen in the furnace until an oxygen content in the furnace is about 5.0%; heating the porous graphite member in the furnace to a temperature of at least about 1000 C.; continuing flowing nitrogen and heating the porous graphite member until the oxygen content in the furnace is less than or equal to 0.5%; directly subjecting the porous graphite member to a chlorination treatment by increasing the temperature of the furnace to >1500 C. and starting flowing chlorine gas; and heating the porous graphite member in the chlorine gas in the furnace to a temperature of greater than or equal to 1700 C. to form the purified graphite member.

2. The method of claim 1, wherein during locating the porous graphite member in a furnace and flowing nitrogen in the furnace until the oxygen content in the furnace is about 5.0%, nitrogen is flowed until the oxygen content in the furnace is about 3.0%.

3. The method of claim 1, wherein during the continuing flowing nitrogen and heating of the porous graphite member until the oxygen content in the furnace is <0.5%, nitrogen flow and heating is continued until the oxygen content is reduced to between 0.1% and 0.3%.

4. The method of claim 1, wherein a chlorine content in the porous graphite member after heating the porous graphite member in the chlorine gas in the furnace to a temperature of >1700 C., chlorine is present in the porous graphite member at between 20.00 ppb by weight to 60.00 ppb by weight.

5. The method of claim 1, wherein after heating the porous graphite member in the chlorine gas in the furnace to a temperature of >1700 C., chlorine is present in the porous graphite member greater than or equal to 50 m below a main surface.

6. The method of claim 1, wherein while heating the porous graphite member in the furnace to a temperature of at least about 1000 C. and continuing flowing nitrogen and heating of the porous graphite member until the oxygen content in the furnace is <0.5% and the temperature is between 1000 and 1500 C.

7. The method of claim 1, wherein the pores of the porous graphite member are enlarged to average pore diameter of >10 m.

8. The method of claim 1, wherein the porous graphite member having modified porosity further comprises one or more of the following elements in an amount of: calcium<50.00 ppb by weight, magnesium<50.00 ppb by weight, aluminum<50.00 ppb by weight, titanium<10.00 ppb by weight, chromium<100.00 ppb by weight, manganese<10.00 ppb by weight, copper<50.00 ppb by weight, iron<10.00 ppb by weight, cobalt<10.00 ppb by weight, nickel<10.00 ppb by weight, zinc<50.00 ppb by weight, or molybdenum<150.00 ppb by weight.

9. A porous graphite member having a purity of greater than or equal to 98%, wherein the porous graphite member is manufactured by: providing a graphite member having an open porosity and comprising pores with an initial average pore diameter in a range of 0.4-5.0 m and comprising pores with an initial surface pore diameter of <10 m, and having an initial average grain size of <0.05 mm; locating the graphite member in a furnace and flowing nitrogen in the furnace until an oxygen content in the furnace is about 5.0%; heating the porous graphite member in the furnace to a temperature of at least about 1000 C.; continuing flowing nitrogen and heating of the porous graphite member until the oxygen content in the furnace is less than or equal to 0.5%; directly subjecting the porous graphite member to a chlorination treatment, by increasing the temperature of the furnace to >1500 C. and starting flowing chlorine gas; and heating the porous graphite member in the chlorine gas in the furnace to a temperature of greater than or equal to 1700 C.

10. The porous graphite member of claim 9, wherein the porous graphite member comprises pores having a pore diameter at an outer surface thereof of greater than or equal to 10 m.

11. The porous graphite member of claim 9, wherein the porous graphite member has a chlorine content of between 20.00 ppb by weight to 60.00 ppb by weight.

12. The porous graphite member of claim 9, further comprising pores having an average grain size of <0.05 mm.

13. The porous graphite member of claim 9, wherein the porous graphite member has a purity of at least 98%.

14. The porous graphite member of claim 9, further comprising one or more of the following elements in an amount of: calcium<50.00 ppb by weight, magnesium<50.00 ppb by weight, aluminum<50.00 ppb by weight, titanium<10.00 ppb by weight, chromium<100.00 ppb by weight, manganese<10.00 ppb by weight, copper<50.00 ppb by weight, iron<10.00 ppb by weight, cobalt<10.00 ppb by weight, nickel<10.00 ppb by weight, zinc<50.00 ppb by weight, or molybdenum<150.00 ppb by weight.

15. A porous graphite semiconductor processing chamber component, comprising: a porous graphite base having: a plurality of modified pores therein, at least a portion of the plurality of modified pores opening at an outer surface of the porous graphite base and having a diameter of at least 10 m at the outer surface of the porous graphite base; and a chlorine content of between 20.00 ppb by weight to 60.00 ppb by weight; and a silicon carbide coating extending on the outer surface of the porous graphite base, the silicon carbide coating extending inwardly of the pores of the porous graphite base.

16. The porous graphite semiconductor processing chamber component of claim 15, wherein the modified pores are increased in diameter from their original diameter prior to forming the silicon carbide coating on the porous graphite base.

17. The porous graphite semiconductor processing chamber component of claim 15, further comprising one or more of the following elements in an amount of: calcium<50.00 ppb by weight, magnesium<50.00 ppb by weight, aluminum<50.00 ppb by weight, titanium<10.00 ppb by weight, chromium<100.00 ppb by weight, manganese<10.00 ppb by weight, copper<50.00 ppb by weight, iron<10.00 ppb by weight, cobalt<10.00 ppb by weight, nickel<10.00 ppb by weight, zinc<50.00 ppb by weight, or molybdenum<150.00 ppb by weight.

18. The porous graphite semiconductor processing chamber component of claim 15, wherein the silicon carbide coating comprises: a first silicon carbide sublayer; and a second silicon carbide sublayer at least partially extending over the first silicon carbide sublayer.

19. The porous graphite semiconductor processing chamber component of claim 15, wherein the first silicon carbide sublayer, the second silicon carbide sublayer, or a combination thereof is stoichiometric.

20. The porous graphite semiconductor processing chamber component of claim 15, wherein the first silicon carbide sublayer, the second silicon carbide sublayer, or a combination thereof has compressive internal stress.

Description

DESCRIPTION OF THE FIGURES AND THE REFERENCE SIGNS

[0549] FIG. 1 shows a SEM image with a 680 fold magnification of a silicon carbide coated body according to the present invention with a graphite substrate (1) and SiC tendrils (4) in the interfacial layer (3) thereof as well as the SiC coating layer (2). It can be seen that the interfacial layer (3) has a thickness of approximately 200 m, i.e. SiC tendrils (4) extend into the porous graphite substrate (1) with a length of at least 50 m. The SiC coating layer (2) has a thickness of approximately 50 m

[0550] FIG. 2 shows a SEM image with a 1250 fold magnification of a silicon carbide coated body with a multilayer SiC coating of different density. The different SiC coating layers exhibit different thickness with a first SiC layer (2-A) of approximately 43 m thickness, a second SiC layer (2-B) of approximately 7 m thickness, and a third SiC layer (2-C) of approximately 50 m thickness. The image further shows the tendrils (4) with the SiC pore filling in the form of a SiC coating of the inner walls of the open pores (5) in the interfacial layer (3).

[0551] FIG. 3 shows a SEM image of a silicon carbide coated body with a SiC coating layer (2) of nearly 100 m thickness on the porous graphite substrate (1) but without formation of tendrils and an interfacial layer. The open pores (6) of the graphite substrate (1) are well apparent.

[0552] FIG. 4 shows a SEM image with a 510 fold magnification of a silicon carbide coated body with a SiC coating layer (2) of more than 50 m thickness on the porous graphite substrate (1) but without formation of tendrils and an interfacial layer due to the use of argon as purge gas. The open pores (6) of the graphite substrate (1) are well apparent.

[0553] FIGS. 5a and 5b show a SEM image with a 500 fold magnification of a top view on the SiC tendrils (4); therefore, the graphite substrate was burnt off in air, morphology and distribution of the tendrils is visible, the distribution of tendril is very uniform and dense

[0554] FIG. 6a shows a SEM image with a 390 fold magnification of a cross-sectional view of SiC tendrils (4), which connect with the SiC coating layer (2) very firmly

[0555] FIG. 6b shows a SEM image with a 2000 fold magnification of the cross-sectional view of SiC tendrils (4), which connect with the SiC coating layer (2) very firmly

[0556] FIGS. 7a and 7b show a SEM image with a 2000 fold magnification of a porous graphite material prior to the purification and activation process of the present invention (pre-product) having quite small pores wherein the pores have a pore size/diameter<10 m

[0557] FIG. 7c shows the pore distribution and the average pore size of said porous graphite material prior to the purification and activation process of the present invention (pre-product)

[0558] FIGS. 8a and 8b show a SEM image with a 2000 fold magnification of a porous graphite material after the activation process of the present invention clearly showing the modified surface porosity with the significantly enlarged surface pores, now comprising a significant amount of enlarged pores having a pore size/diameter10 m

[0559] FIG. 8c shows the pore distribution and the average pore size of said porous graphite material after the activation process of the present invention illustrating the increased porosity degree and the increased average pore size compared to the graphite material prior to the activation process

[0560] FIG. 9 illustrates the critical temperature dependency and its influence on SiC nucleation, growth and crystal formation in a CVD process

[0561] FIG. 10 shows a SEM image with a 3500 fold magnification of a top view on the improved SiC material of the present invention with the substantially tetrahedral crystallinity and the crystal size up to 10 to 30 m being clearly visible

[0562] FIG. 11 shows an XRD pattern of the improved SiC material of the present invention showing a very sharp p-sic crystallinity peak and showing very little side-product peaks or amorphous SiC, which confirms the high purity and crystallinity of the SiC formed in the process of the present invention

[0563] (1) porous graphite substrate

[0564] (2) SiC coating layer

[0565] (2-A), (2-B), (2-C) SiC coating layers of different density

[0566] (3) interfacial layer with

[0567] (4) tendrils formed in open pores

[0568] (5) SiC coating on the inner walls of open pores

[0569] (6) open pores in the graphite substrate

[0570] (7) tight connection between tendrils and coating layer

[0571] (8) tetrahedral crystals

VI. EXAMPLES

Example 1

Activation and Chlorination of a Graphite Member and Tendril Formation

[0572] A porous graphite member was activated, purified and subjected to a chlorination treatment as described in the present invention.

[0573] The following chlorine content was measured in the chlorinated graphite member:

TABLE-US-00001 element graphite member Cl 0.06 ppm wt.

[0574] The formation of activated graphite with enlarged surface porosity has been shown in FIGS. 7a to c compared to FIGS. 8a to c. The SEM has been prepared as described above.

[0575] The chlorinated graphite member was used as a porous graphite substrate (1) in a CVD deposition method as described herein.

[0576] In the CVD method SiC tendrils (4) according to the present invention were formed in the pores (6) of the accordingly chlorinated graphite substrate, as shown in FIGS. 1, 2, 3, 4, 5a, 5b, 6a and 6b.

[0577] The SiC characteristics and quality described herein has been shown in FIGS. 10 and 11.

Example 2

Influence of the Fume Gas

[0578] A silicon carbide coated body was prepared with the process of the present invention using H.sub.2 as the purge gas.

[0579] As a comparative Example, argon was used as purge gas.

[0580] As becomes apparent from FIGS. 1 and 4, the use of argon does not lead to the formation of tendrils (4).

Example 3

Multilayer SiC-Coating

[0581] A silicon carbide coated body was prepared with the process of the present invention, therein varying the amounts of DMS for preparing a multilayer SiC coating having varying densities (2-A), (2-B), (2-C) etc.

[0582] Therein, the following DMS amounts were introduced into the process chamber of a laboratory size test reactor using H.sub.2 as the carrier gas in the deposition phases:

TABLE-US-00002 Deposition phase DMS amount 1. approximately 0.5 g / minute 2. approximately 1.0 g / minute 3. approximately 1.5 g / minute 4. approximately 2.0 g / minute

[0583] The SiC coatings deposited in the first to fourth deposition phase showed varying crystal sizes, which increased with increasing DMS amounts, leading to SiC coating layers with decreasing density.

[0584] A further example, illustrating the SiC multilayer structure due to varying DMS amounts is shown in FIG. 2.

Example 4

DMS Purity (Siloxanes)

[0585] A silicon carbide coated body was prepared with the process of the present invention with DMS of varying siloxane impurities.

[0586] DMS with the following amounts of siloxane impurities were used:

TABLE-US-00003 DMS DMS DMS Sample Sample Sample Siloxane compound A B C 1,3-dichloro-1,1,3,3,- 0.193 0.103 0.710 tetramethyldisiloxane wt. % wt. % wt. % 1,3-dichloro-1,1,3,5,5,5,- 0.042 0.072 0.110 hexamethyltrisiloxane wt. % wt. % wt. % octamethylcyclotetrasiloxane 0.112 0.157 0.156 wt. % wt. % wt. % total amount of siloxane 0.389 0.375 1.04 impurities wt. % wt. % wt. % total amount of impurities 0.119 0.580 1.239 wt. % wt. % wt. %

[0587] With DMS according to sample A and B the formation of SiC tendrils occurred according to the present invention.

[0588] With DMS according to sample C no sufficient formation of SiC tendrils occurred.

[0589] Further, the following ranges were found as effective with respect to the desired tendril formation:

TABLE-US-00004 Total Siloxane Tendril Content formation >2.00 wt.% 0.50 to 2.00 wt.% + <0.50 wt.% ++ represents no or insufficient tendril formation in the open pores + represents moderate to low tendril formation in the open pores ++ represents adequate to optimum tendril formation in the open pores

Example 5

DMS Purity (Mn)

[0590] A silicon carbide coated body was prepared with the process of the present invention with DMS of varying manganese impurities.

[0591] DMS with the following amounts of manganese impurities were used:

TABLE-US-00005 metal DMS DMS DMS element Sample A Sample B Sample C manganese 2 ppb 11 ppb 150 ppb (Mn) wt. wt. wt.

[0592] With DMS according to sample A and B the formation of SiC tendrils occurred according to the present invention.

[0593] With DMS according to sample C no sufficient formation of SiC tendrils occurred.

[0594] Further, the following ranges were found as effective with respect to the desired tendril formation:

TABLE-US-00006 Total Manganese Tendril Content formation 150 ppb wt. 40 to 150 ppb wt. + <40 ppb wt. ++ represents no or insufficient tendril formation in the open pores + represents moderate to low tendril formation in the open pores ++ represents adequate to optimum tendril formation in the open pores

Example 6

DMS Purity (Cu)

[0595] A silicon carbide coated body was prepared with the process of the present invention with DMS of varying copper impurities.

[0596] DMS with the following amounts of copper impurities were used:

TABLE-US-00007 metal DMS DMS DMS element Sample A Sample B Sample C copper (Cu) 1 ppb wt. 18 ppb wt. 41 ppb wt.

[0597] With DMS according to sample A and B the formation of SiC tendrils occurred according to the present invention.

[0598] With DMS according to sample C no sufficient formation of SiC tendrils occurred.

[0599] Further, the following ranges were found as effective with respect to the desired tendril formation:

TABLE-US-00008 Total Copper Tendril Content formation 50 ppb wt. 30 to <50 ppb wt. + <30 ppb wt. ++ represents no or insufficient tendril formation in the open pores + represents moderate to low tendril formation in the open pores ++ represents adequate to optimum tendril formation in the open pores

Example 7

DMS Purity (Zn)

[0600] A silicon carbide coated body was prepared with the process of the present invention with DMS of varying zinc impurities.

[0601] DMS with the following amounts of zinc impurities were used:

TABLE-US-00009 metal DMS DMS DMS element Sample A Sample B Sample C zinc (Zn) 1 ppb wt. 19 ppb wt. 42 ppb wt.

[0602] With DMS according to sample A and B the formation of SiC tendrils occurred according to the present invention.

[0603] With DMS according to sample C no sufficient formation of SiC tendrils occurred.

[0604] Further, the following ranges were found as effective with respect to the desired tendril formation:

TABLE-US-00010 Total Zinc Tendril Content formation 50 ppb wt. 30 to <50 + ppb wt. <30 ppb wt. ++ represents no or insufficient tendril formation in the open pores + represents moderate to low tendril formation in the open pores ++ represents adequate to optimum tendril formation in the open pores

Example 8

DMS Purity (Siloxane Plus Mn Plus Cu Plus Zn)

[0605] The following ranges of total siloxane content in the presence of Mn, Cu and Zn metal impurities were found as effective with respect to the desired tendril formation:

TABLE-US-00011 Total Total Total Total Siloxane Manganese Copper Zinc Tendril Content Content Content Content formation >2.00 wt.% 150 ppb wt. 50 ppb wt. 50 ppb wt. 0.50 to 2.00 40 to 150 30 to <50 30 to <50 + wt.% ppb wt. ppb wt. ppb wt. <0.50 wt.% <40 ppb wt. <30 ppb wt. <30 ppb wt. ++ represents no or insufficient tendril formation in the open pores + represents moderate to low tendril formation in the open pores ++ represents adequate to optimum tendril formation in the open pores