Method for manufacturing a semiconductor device utilizing selective epitaxial growth and post heat treating

Claim 1

A method of making a semiconductor device comprising the steps of: preparing a semiconductor substrate having a main surface and a semiconductor layer therein of one conductivity type adjacent to said main surface; covering said main surface of said semiconductor substrate with a first mask having an opening which exposes a portion of said semiconductor layer; doping impurity atoms into said semiconductor layer through said opening of said first mask to make a first semiconductor region of another conductivity type opposite to said one conductivity type in said semiconductor layer; selectively covering the main surface of said semiconductor substrate with a second mask to cover the entire exposed surface of said first semiconductor region and an adjacent outer portion of the semiconductor layer provided in said main surface and to expose another portion of the semiconductor layer on the main surface whereby the another portion of the semiconductor layer is left uncovered; depositing a second semiconductor region of said one conductivity type epitaxially on the exposed portion of said semiconductor layer not covered with second mask; and heating said semiconductor substrate to cause diffusion of said impurity atoms outwardly from said first semiconductor region to enlarge said first semiconductor region into a portion of the semiconductor layer and into a portion of the second semiconductor region, the second mask preventing auto-doping of said impurity atoms from said first semiconductor region into said second semiconductor region during deposition of said second semiconductor region, and the width of the second semiconductor region being controllably reduced.

Claim 2

A method of making a semiconductor device comprising the steps of: preparing a semiconductor substrate having a main surface and a semiconductor layer therein of one conductivity type adjacent to said main surface; covering said main surface of said semiconductor substrate with a first mask having an opening which exposes a portion of said semiconductor layer; doping impurity atoms into said semiconductor layer through said opening of said first mask to make a first semiconductor region of another conductivity type opposite to said one conductivity type in said semiconductor layer; selectively covering the main surface of said semiconductor substrate with a second mask to cover the entire exposed surface of said first semiconductor region and an adjacent outer portion of the semiconductor layer provided in said main surface and to expose another portion of the semiconductor layer on the main surface whereby the another portion of the semiconductor layer is left uncovered; depositing a second semiconductor region of said one conductivity type epitaxially on the exposed portion of said semiconductor layer not covered with second mask; and heating said semiconductor substrate to cause diffusion of said impurity atoms outwardly from said first semiconductor region to enlarge said first semiconductor region into a portion of the semiconductor layer and into a portion of the second semiconductor region, the second mask preventing auto-doping of said impurity atoms from said first semiconductor region into said second semiconductor region during deposition of said second semiconductor region, and the width of the second semiconductor region being controllably reduced.

Claim 4

A method making a Field Controlled Thyristor comprising the steps of: preparing a semiconductor substrate having a pair of opposing main surfaces and a stack structure of semiconductor areas therebetween which includes a first semiconductor area of one conductivity type adjacent to one of said main surfaces and a second semiconductor area of another conductivity type opposite to said one conductivity type adjacent to the other main surface of said first semiconductor area; covering said one of the main surfaces of said semiconductor substrate with a first mask having an opening which exposes a portion of said first semiconductor area; doping impurity atoms into said first semiconductor area through said opening of said first mask to make a first semiconductor region of said another conductivity type in said one semiconductor area; selectively covering said one of the main surfaces of said semiconductor substrate with a second mask to cover the entire exposed surface of said first semiconductor region and an adjacent outer portion of the first semiconductor area and to expose another portion of the first semiconductor area whereby the another portion of the first semiconductor area is left uncovered; depositing a second semiconductor region of said one conductivity type epitaxially on the exposed portion of said first semiconductor area not covered with said second mask to form a channel region of the Field Controlled Thyristor; and heating said semiconductor substrate to cause diffusion of said impurity atoms outwardly from said first semiconductor region to enlarge said first semiconductor region into a portion of the first semiconductor area and into a portion of the second semiconductor region, the second mask preventing auto-doping of said impurity atoms from said first semiconductor region into said second semiconductor region during deposition of said second semiconductor region, and the width of the second semiconductor region being controllably reduced.

Claim 5

A method making a Field Controlled Thyristor comprising the steps of: preparing a semiconductor substrate having a pair of opposing main surfaces and a stack structure of semiconductor areas therebetween which includes a first semiconductor area of one conductivity type adjacent to one of said main surfaces and a second semiconductor area of another conductivity type opposite to said one conductivity type adjacent to the other main surface of said first semiconductor area; covering said one of the main surfaces of said semiconductor substrate with a first mask having an opening which exposes a portion of said first semiconductor area; doping impurity atoms into said first semiconductor area through said opening of said first mask to make a first semiconductor region of said another conductivity type in said one semiconductor area; selectively covering said one of the main surfaces of said semiconductor substrate with a second mask to cover the entire exposed surface of said first semiconductor region and an adjacent outer portion of the first semiconductor area and to expose another portion of the first semiconductor area whereby the another portion of the first semiconductor area is left uncovered; depositing a second semiconductor region of said one conductivity type epitaxially on the exposed portion of said first semiconductor area not covered with said second mask to form a channel region of the Field Controlled Thyristor; and heating said semiconductor substrate to cause diffusion of said impurity atoms outwardly from said first semiconductor region to enlarge said first semiconductor region into a portion of the first semiconductor area and into a portion of the second semiconductor region, the second mask preventing auto-doping of said impurity atoms from said first semiconductor region into said second semiconductor region during deposition of said second semiconductor region, and the width of the second semiconductor region being controllably reduced.