Chemistry of inorganic compounds – Silicon or compound thereof – Binary compound
Reexamination Certificate
2002-04-25
2004-05-11
Nguyen, N. M. (Department: 1754)
Chemistry of inorganic compounds
Silicon or compound thereof
Binary compound
C423S346000, C501S088000
Reexamination Certificate
active
06733736
ABSTRACT:
RELATED APPLICATION
This application claims benefit of priority under 35 USC 119 based on Japanese Patent Application P2001-134526, filed May 1, 2001, the entire contents of which are incorporated by reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sintered silicon carbide which can be used as a semi-insulator or insulator and suitable for a semiconductor device and the like, a silicon carbide powder suitable for production of this sintered silicon carbide, and a method of producing a silicon carbide powder which can produce this silicon carbide powder efficiently.
2. Description of the Related Art
Silicon carbide show larger band gap and excellent in dielectric breakdown property, heat resistance, radiation resistance and the like as compared with silicon. Therefore, silicon carbide powders have been noticed as electronic device materials for portable high output semiconductors and the like, or as optical device materials owing to excellent optical properties, and sintered bodies thereof have been applied to electronic devices and the like.
As the method of producing the above-mentioned silicon carbide powder, there are a plurality of suggestions, however, a method of producing a silicon carbide powder having a content of impurity elements (elements belonging to group I to group XVII elements in the periodic table according to 1989, IUPAC, inorganic chemical nomenclature method, revision, and having an atomic number of 3 or more (excepting a carbon atom, nitrogen atom, oxygen atom and silicon atom)) of 1.0 ppm or less is not known well.
On the other hand, a sintered silicon carbide obtained by using a silicon carbide powder containing significant amount of a nitrogen atom and the like which are not included in the above-mentioned impurity elements can be utilized as an n-type semiconductor, and for designing a semiconductor, it is further required that the sintered silicon carbide forms a p-n junction together with a p-type semiconductor. However, a sintered silicon carbide which can be utilized as the above-mentioned p-type semiconductor is needed to have a small content of a nitrogen atom and the like which are not included in the above-mentioned impurity elements, and such a sintered silicon carbide is required to be produced by using a silicon carbide powder having a small content of a nitrogen atom and the like which are not included in the above-mentioned impurity elements, however, such as silicon carbide powder and a method of producing the same are not known under current conditions.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of such conditions, and a subject thereof is to attain the following object. Namely, an object of the present invention is to provide a sintered silicon carbide which has a small content of the above-mentioned impurity elements, has also a small content of elements such as nitrogen and the like not included in the above-mentioned impurity elements, can be used as a semi-insulator or insulator, and can be suitably used as a p-type semiconductor and the like. Another object of the present invention is to provide a silicon carbide powder suitable for production of the above-mentioned sintered silicon carbide, and a method of producing a silicon carbide powder which can produce the above-mentioned silicon carbide powder efficiently.
The objects of the present invention described above can be achieved by a method of producing a silicon carbide powder comprising sintering a mixture containing at least a silicon source and a carbon source wherein the carbon source is a xylene-based resin.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the silicon source is an alkoxysilane compound.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the alkoxysilane compound is selected from an ethoxysilane oligomer and ethoxysilane polymer.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the mixture is obtained by adding an acid to a silicon source, then, adding to this a carbon source.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the mixture is heated under a non-oxidizing atmosphere of 500 to 1000° C. before sintering.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the mixture is prepared by adding a halogen compound in an amount of 0.5 to 5 mass % to the above-mentioned mixture.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein sintering is conducted by heating at a rate of 100 to 1000° C./h to 1300 to 1600° C., then, heating at a rate of 50 to 300° C./h to 1900 to 2100° C., then, keeping at 1900 to 2100° C. for 180 minutes or less, under a non-oxidizing atmosphere.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the ratio of carbon contained in the carbon source to silicon contained in the silicon source in the mixture is 1.8 or less in sintering.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein a halogen or hydrogen halide is added in an amount of 1 to 5 vol % based on the silicon source and carbon source.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein post-treatment by heating is conducted after sintering.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the post-treatment is conducted at 2150 to 2400° C.
The objects of the present invention described above can also be achieved by the method of producing a silicon carbide powder described above, wherein the post-treatment is conducted in an argon atmosphere for 3 to 8 hours.
The objects of the present invention described above can also be achieved by a silicon carbide powder produced by the method of producing a silicon carbide powder described above.
The objects of the present invention described above can also be achieved by the silicon carbide powder described above, wherein the nitrogen content is 100 ppm or less.
The objects of the present invention described above can also be achieved by the silicon carbide powder described above, wherein the nitrogen content is 50 ppm or less.
The objects of the present invention described above can also be achieved by the silicon carbide powder described above, wherein the content of impurity elements is 0.3 ppm or less.
The objects of the present invention described above can also be achieved by the silicon carbide powder described above, wherein the volume-average particle size (D
50
) is 1 to 500 &mgr;m.
The objects of the present invention described above can also be achieved by the silicon carbide powder described above, wherein the particle size distribution (D
90
/D
10
) is 4 or less.
The objects of the present invention described above can also be achieved by a sintered silicon carbide obtained by sintering the silicon carbide powder described above.
The objects of the present invention described above can also be achieved by the sintered silicon carbide described above, wherein the volume resistivity is 1×10
0
&OHgr;·cm or more.
The objects of the present invention described above can also be achieved by the sintered silicon carbide described above, wherein the volume resistivity is 1×10
1
&OHgr;·cm or more.
The objects of the present invention desc
Endo Shigeki
Otsuki Masashi
Bridgestone Corporation
Nguyen N. M.
LandOfFree
Silicon carbide powder and method for producing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silicon carbide powder and method for producing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silicon carbide powder and method for producing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3270120