P- MOSFET WITH REINFORCED ABNORMALLY NARROW CHANNEL EFFECT

摘要

PURPOSE: To prevent the threshold voltage of an FET having narrow channel width from increasing and to enlarge the difference of V1 between p-FETs having wide and narrow channel widths respectively by taking advantage of abnormally narrow channel effect. CONSTITUTION: In order to suppress latch-up in a p-FET, a dopant is implanted deeply into a semiconductor substrate beneath the region for forming a p-FET. A desired logical threshold voltage difference▵V1 is set between a logical threshold voltage V1 of a p-FET having a channel width wider than 10μm being set by deep implantation and a logical V1 being set by buried implantation for p-FET having a narrow channel width. Consequently, the p-FET in the circuit has a different V1 dependent on the channel width thereof. Consequently, the threshold voltage of an FET having narrow channel width is prevented from increasing and the difference of V1 between p-FETs having wide and narrow channel widths respectively can be enlarged by taking advantage of abnormally narrow channel effect.