Electrical characteristics of a DSA MOS transistor with a fine structure

Fabrication technologies and electrical characteristics of a diffusion self-aligned MOS transistor (DSA MOST) or a double-diffused MOS transistor (DMOST) are discussed in comparison with a conventional short-channel MOS transistor as a fundamental device for a VLSI. The symmetrical DSA MOS LSI with enhancement depletion configurations requires six photolithographic steps and the number of the steps is the same as that of an NMOS LSI with small physical dimensions. The only difference is the step orders of the enhancement channel doping in these devices. The lowering effects of the threshold voltage and the source drain breakdown voltage are smaller in the DSA MOST than in the conventional MOS transistor.