HIGH-VOLTAGE CMOS TRANSISTORS FOR A STANDARD CMOS PROCESS

摘要

A low-voltage 0.8-micron CMOS process is modified by implanting arsenic or phosphorus during epitaxy in a p-type substrate (14) starting material to increase the depth of selected n-well areas (16) for the purpose of producing high-voltage transistors on the same substrate in the same CMOS process. Implanting boron in a p-field extension area (18) through partially formed field oxide insulators (24, 26) so that the diffusion of boron beyond the p-field extension area (18) is minimized, achieves a similar result. That is, breakdown and punch-through voltages are increased. Together, these make CMOS transistors which operate at a higher voltage range than either innovation alone.