US Patent 7091075 Fabrication of an EEPROM cell with SiGe source/drain regions

An EEPROM memory cell uses silicon-germanium/silicon and emitter polysilicon film for fabricating shallow source/drain regions to increase a breakdown voltage with respect to a well. The source/drain regions are fabricated to be approximately 100 nm (0.1 micrometers (μm)) in depth with a breakdown voltage of approximately 14 volts or more. A typical breakdown voltage of a well in a bipolar process is approximately 10 volts. Due to the increased breakdown voltage achieved, EEPROM memory cells can be produced along with bipolar devices on a single integrated circuit chip and fabricated on a common semiconductor fabrication line.