Abstract: A MOS type semiconductor device has a gate whose length is 170 nm (0.17 .mu.m) or less, a junction depth of source and drain diffusion layers in the vicinity of a channel is 22 nm or less, and a concentration of impurities at the surface in the source and drain diffusion layers is made to 10.sup.20 cm.sup.-3 or more. Such structure is obtained using solid phase diffusion using heat range from 950.degree. C. to 1050.degree. C. and/or narrowing gate width by ashing or etching. The other MOS type semiconductor device is characterized in that the relationship between the junction depth x.sub.j ?nm! in the source and drain diffusion layer regions and the effective channel length L.sub.eff ?nm! is determined by L.sub.eff >0.69 x.sub.j -6.17.

Abstract: A diffused layer serves as a source and a drain. It is formed comprised of a deep first diffused layer and a shallow second diffused layer positioned between the first diffused layer and the channel region. In the second diffused region, a distribution in a depth direction of carriers has a profile in which the concentration is more than 5.times.10.sup.18 cm.sup.-3 at the peak and is in correspondence with a carrier concentration of the semiconductor substrate at a depth less than 0.04 .mu.m. Since the second diffused layer has a high concentration, the short-channel effect can be suppressed. As the second diffused region, a solid phase diffusion source such as an impurity doped silicate glass is used.