Methods for fabricating latchup-preventing CMOS device

摘要

A new CMOS device which avoids latchup while achieving a spacing between the n-channel and p-channel FETs of the device smaller than 10 mu m, as well as a method for fabricating the choice, is disclosed. The inventive device, which is formed in a substrate comprising a relatively heavily doped bulk region supporting a relatively thin, moderately doped layer, includes a polysilicon-filled trench extending through a portion of the layer, between the n- and p-channel FETs of the device. The inventive device also includes a relatively heavily doped region extending from a bottom of the trench to the bulk region. The polysilicon-filled trench, in combination with both the relatively heavily doped region and bulk region, prevents latchup.