Method of fabricating MOS field effect transistors

A method for making a MOSFET device (20) comprising the steps of:

• (a) forming a pair of spaced-apart contact electrodes (12.1, 12.2) whose top surfaces are coated with an intermediate insulating layer (13, 14), said electrodes (12.1, 12.2) being essentially metal, metal-silicide, or silicon rich metal-silicide, and said electrodes making contact with spaced-apart areas of a top surface of a semiconductor body (10);
• (b) forming sidewall edge insulating layers (15.1, 15.2) on exposed mutually opposed sidewall edges of each of said contact electrodes (12.1, 12.2) contiguous with said spaced-apart areas of contact;
• (c) forming a recess in the body (10) at the top surface thereof located between said sidewall insulating layers (15.1, 15.2) to at least a predetermined depth;
• (d) forming a gate oxide layer (10.3) coating said recess;
• and
• (e) forming a gate electrode layer (16.3) covering both said gate oxide layer (10.3) and each of the sidewall insulating layers (15.1, 15.2).

A method of making a MOSFET device comprising the steps of:

• (a) forming a pair of spaced-apart field oxide layer portions (11) at a major surface of a semiconductive silicon body (10);
• (b) introducing conductivity type determining impurities into the body to form a doped region of predetermined depth (10.5) of the body located contiguous with the major surface thereof in the space between the field oxide layer portions (11), said doped region (10.5) being of opposite type and higher conductivity as compared with the conductivity of the bulk of body ( 10);
• (c) depositing a contact electrode layer (12) essentially of metal, metal-silicide, or silicon rich metal-silicide on said field oxide layers (11) and on the exposed portions of said major surface of the body (10) in the space between the field oxide layer portions (11);
• (d) forming an intermediate insulating layer (13, 14) on said contact layer (12);
• (e) forming a first aperture penetrating through said insulating layer (13, 14) and said contact layer (12), thereby separating said contact layer (12) into a pair of spaced-apart contact electrodes (12.1, 12.2);
• and thereby exposing a pair of mutually opposed sidewall edges of the contact electrodes (12.1, 12.2) and exposing another portion of the major surface of the body (10) located between said sidewall edges of said contact electrodes (12.1, 12.2);
• (f) depositing another insulating layer (15) on said intermediate layer (13, 14), on said exposed sidewall edges of the contact electrodes (12.1, 12.2), and on said another portion of the major surface of the body (10);
• (g) anisotropically etching said another insulating layer (15), whereby material of said another insulating layer (15) remains on said sidewall edges of the contact electrodes (12.1, 12.2), thereby forming mutually opposing sidewall insulating layers (15.1, 15.2) on said sidewall edges and thereby exposing yet another, smaller portion of the major surface of the body (10) therebetween;
• (h) thermally growing a gate oxide layer (10.3) on the said yet another, smaller portion of the major surface of the body (10);
• and
• (i) forming a gate electrode layer (16.3) on said gate oxide layer (10.3), on each of said sidewall insulating layers (15.1, 15.2), and on a selected portion of said intermediate insulating layer (13, 14).