Oxygen implantation for improved CMOS latchup immunity

Improvement in CMOS latchup immunity has been achieved through the application of oxygen implantation to create both a lifetime reduction layer and a potential barrier in the bulk of Si wafers. The effects of the implanted layer on the MOSFET´S and the parasitic bipolar transistors are discussed. The MOSFET´s are not affected by the oxygen implantation. The reduction in common base current gain is 50% for the lateral and 90% for the vertical parasitic bipolar transistors. As a consequence, the latchup immunity is greatly improved.