| 摘要 |
PURPOSE:To reduce the short channel effect of a semiconductor device by forming a high impurity density region deeper than the depth of a depletion layer produced directly under a channel in and under the channel forming region of an enhancement type MOSFET. CONSTITUTION:An SiO2 film 22 and an Si3N4 film 23 are coated on a P<->-type Si substrate 21, and a resist film 24 is formed only on an MOSFET forming region. Then, the film 23 at both sides of the film 24 is etched and removed, ion is implanted to form a P<+>-type region 25 in the substrate 21, the film 24 is converted into a film 26 to coat it on the depletion type forming region so as to form a P<+>-type region 27 in the enhancement type region. Thereafter, the film 26 is removed, a thick field SiO2 film 221 is coated on the end of the substrate 21, and the films 23, 22 are removed, a thin gate SiO2 film 222 is coated thereon so as to form a P-type region 28 for preventing leakage on the surface by ion implantation. Then, an N<->-type region 30 is diffused in the depletion region adjacent to the region 27, and an N<+>-type region 32 is formed therebetween. |
