Method for producing CMOS transistor

A method of producing a CMOS transistor device, comprising:

• the first step of forming a P type MOS device region and an N type MOS device region adjacent to each other in a surface portion of a semiconductor substrate;
• the second step of forming sequentially a gate insulating film and a gate electrode on the gate insulating film on each of the device regions;
• the third step of removing the gate insulating film on each of the device regions using the associated gate electrode as a mask, and then exposing an active semiconductor surface on each of the device regions;
• the fourth step of applying a gas containing an impurity component of P conductivity type to the exposed active semiconductor surface to form thereon an adsorption film composed of the impurity component of P conductivity type;
• the fifth step of forming a resist layer on the P type MOS device region;
• the sixth step of removing the adsorption film formed in the fourth step from the N type MOS device region, using the resist layer formed in the fifth step as a mask;
• the seventh step of ion implanting an N conductivity type impurity component into the N type MOS device region to form N type MOS device source and drain regions using the resist layer as a mask;
• and
• the eighth step of effecting solid-phase diffusion of the impurity component of P conductivity type from a diffusion source composed of the adsorption film to form source and drain regions of P conductivity type in said P type MOS device region.