Field implant process for cmos using germanium

Abstract

A complementary metal-oxide-semiconductor (CMOS) isolation structure where the field isolation structure between the adjacent areas of different conductivity types has a channel stop doped with boron or phosphorus affected by germanium. The dual use of germanium and a second dopant selected from the group of phosphorus and boron provides a more precisely placed channel stop, since the germanium retards the diffusion of the boron and phosphorus and surprisingly provides improved width effect for the devices in the well where the channel stop is employed. Alternatively, the germanium may be placed in such a manner as to avoid retarding absorption of boron or phosphorus into the field oxide and retard its diffusion over the well of a different conductivity type where it is not desired.