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AssigneeSumco Corporation
InventorsKazunari Kurita, Shinsuke Sadamitsu, Hiroyuki Takao, Masataka Hourai
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By using oxygen-containing silicon wafers obtained by the CZ method and by combining the first heat treatment comprising controlled heat-up operation (ramping) with the second heat treatment comprising high-temperature heat treatment and medium temperature heat treatment in accordance with the process for producing high-resistance silicon wafers according to the present invention, it is possible to obtain high-resistance silicon wafers capable of maintaining their high resistance even after heat treatment in the process of device manufacture while efficiently inhibiting the formation of oxygen donors and preventing changes in resistivity. Further, excellent epitaxial wafers and SOI wafers can be produced using those high-resistance silicon wafers and, therefore, they can be applied in a wide field including high-frequency communication devices and analog/digital hybrid devices, among others.
A process for producing high-resistance silicon wafers wherein it comprises subjecting silicon wafers obtained by the Czochralski method and having a resistivity of 100 Ωcm or above, an initial interstitial oxygen concentration of 8×1017 atoms/cm3 or above (ASTM F 121-1979) and, further, a carbon concentration of 5×1015 to 5×1017 atoms/cm3 (ASTM F 123-1981) to first heat treatment consisting in 0.5 to 5 hours of heat treatment at 850-1000° C. employing a rate of heat-up of 0.5 to 10° C./minute at least in the temperature range of 700-850° C. and, further, to second heat treatment consisting in 1 to 2 hours of heat treatment at 1150° C. or above followed by subsequent lowering of the temperature and heat treating at 1000-1150° C. for 2 to 10 hours.
Dependencies are inferred from the claim text.