A 7-mask CMOS process with selective oxide deposition

A seven mask CMOS process using liquid phase oxide deposition which has selectivity against photoresist is described. The process modules for self-aligned well and one-mask LDD formation are developed. The features of the process are: (1) short TAT (7 masks to first metallization), (2) self-aligned twin retrograde wells with 40% reduction of the p/sup +/-n/sup +/ spacing compared to conventional wells, and (3) optimal LDD design using different sidewall spacer width for n- and p-channel MOSFETs giving a 10% larger on-current for p-channel MOSFETs compared to a conventional process.>