Method for fabricating mos transistors

Abstract

In PMOS having a gate electrode 7 of a p-type polysilicon film 5 along with a silicon nitride film 13, boron diffusion from the p-type polysilicon film 5 and boron punching through the gate oxide film 4 are prevented, thereby stabilizing the properties of the PMOS. Hydrogen existing in the silicon nitride film 13 accelerates boron diffusion from the film 5. To prevent it, all subsequent steps after the step of forming the silicon nitride film 13 are effected within a temperature range within which the boron diffusion is not accelerated by hydrogen. Forming the silicon oxide film 14 through reduced pressure CVD is effected in a furnace at a temperature lower than 850° C. Annealing for dopant activation in the compensation region 17 to be formed on the substrate in the bottom of the contact hole 16 is effected in a manner of RTA (rapid thermal annealing) at a temperature lower than 1000° C.

Dependencies are inferred from the claim text.