Patent ID: 8709156
Filing Date: 2014-04-29
Classification: C30B

Abstract:
1. A method for producing an epitaxially coated silicon wafer, comprising placing a silicon wafer polished on its front side on a susceptor in an epitaxy reactor, pretreating the silicon wafer in a first step under a hydrogen atmosphere and in a second and a third step with addition of an etching medium to the hydrogen atmosphere, and subsequently coating with an epitaxial layer, wherein during the first step and during the second step the hydrogen flow rate is 20-100 slm, during the second and third steps the flow rate of the etching medium is 0.5-1.5 slm, during the second step furthermore an average temperature in the reactor chamber is 950-1050° C. and the power of heating elements arranged above and below the susceptor is regulated in such a way that there is a temperature difference of 5-30° C. between a radially symmetrical region encompassing the central axis of the silicon wafer to be epitaxially coated and a part of the silicon wafer that lies outside the radially symmetrical region; and during the third step the hydrogen flow rate is reduced to 0.5-10 slm.