Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device comprising the steps of:

• (a) forming a trench in a first conductivity type semiconductor layer serving as a drain area, and forming a gate electrode and a gate oxide film;
• (b) forming, in any one of the steps, a channel diffusion area and a source area in a longitudinal direction;
• (c) forming a source electrode made of a metal on the surface of said source area;
• (d) carrying out a thermal process to allow said metal of said source electrode to spike into said source area and said channel diffusion area so that an alloy layer for allowing said source electrode to be made in ohmic contact with said source area and said channel diffusion area is formed, and
• (e) forming a drain elect ode that is electrically connected to said semiconductor layer.

A method for manufacturing a semiconductor device comprising the steps of:

• (a) forming a trench in a first conductivity type semiconductor layer serving as a drain area, and forming a gate electrode and a gate oxide film in said trench;
• (b″) forming, in any one of the steps, a channel diffusion area and a source area in a longitudinal direction around said gate electrode;
• (f) forming a thick insulating film by oxidizing the surface of said gate electrode, as well as exposing the surface of said source area;
• (c′) forming a source electrode made of a metal on the surface of said insulating film formed on said gate electrode and the exposed surface of said source area;
• (d) carrying out a thermal process to allow said metal of said source electrode to spike into said source area and said channel diffusion area so that an alloy layer for allowing said source electrode to be made in ohmic contact with said source area and said channel diffusion area is formed, and
• (e) forming a drain electrode that is electrically connected to said semiconductor layer.