| 摘要 |
PURPOSE:To enable the increase in controllability of the threshold voltage in MISFET having a short channel length by a method wherein the depth of a groove, thickness of the second semiconductor layer, and distance from the second semiconductor layer to the top of the third semiconductor buried layer are allowed to have a specific relation. CONSTITUTION:Using a p type material as a semiconductor substrate 1, an n type high concentration layer 2 is selectively formed by antimony diffusion. When an epitaxial layer 3 is grown on the substrate, the layer 2 turns a buried layer, and the controllability of the threshold voltage improves; when the buried high concentration layer reaches a channel region, the carrier mobility in the channel region decreases. The extreme access of the bottoms of the source and drain to the high concentration layer increases the junction capacitance. There- fore, assume the distance from the semiconductor surface to the source and drain diffused layers is X, distance to the bottom of the gate groove is Y, and distance to the upper end of the buried layer is Z, then a structure satisfying the condition of X<Y<Z becomes reasonable. |
