| 摘要 |
PURPOSE:To prevent the generation of the punch-through of B as well as to stably obtain a P type Si gate MOSFET by a method wherein, after an oxygen unpermeative film has been provided on a B-added poly Si film alone, a source and drain diffusion layer is formed by performing a heat treatment. CONSTITUTION:A poly Si layer 9 is provided on a gate oxide film 8, B is added to the above, and then an Si3N4Al2O3 film 10 is superposed, a selective etching is performed, and the oxygen unpermeative film 10 is left on the B-added poly Si gate electrode 9. Then, a P type source and drain layer 7 is formed on an N type Si substrate 6 by performing a B-ion implantation. According to this constitution, the punch-through of B is hardly generated even when oxygen is used in a heat treatment atmosphere. There is a possibility of the dissolving of B into SiO2 by the infiltration of oxygen from the side face of the layer 9, but the distance thereof is sufficiently short when compared with the gate length, and this gives no effect on the FET characteristics in the center part of the gate, thereby enabling to stably obtain the P type Si gate MOSFET. |
