US Patent 7537657 Silicon wafer and process for producing it

A process for producing a single-crystal silicon wafer, comprises the following steps:producing a layer on the front surface of the silicon wafer by epitaxial deposition or production of a layer whose electrical resistance differs from the electrical resistance of the remainder of the silicon wafer on the front surface of the silicon wafer, or production of an external getter layer on the back surface of the silicon wafer, andheat treating the silicon wafer at a temperature which is selected to be such that an inequality (1)