Method of making retarded DDD (double diffused drain) device structure

Claim 1

A method of forming a retarded double diffused drain structure, in a silicon substrate with field isolation regions and a gate structure, comprising the steps of: first forming a layer of photoresist on the field isolation regions, the silicon substrate, and the gate structure; then patterning said photoresist to expose the silicon substrate and the gate structure, but covering an area of the silicon substrate that is offset from the field isolation regions; then performing a first ion implant of a conductivity-modifying dopant in a vertical direction in exposed regions of the silicon substrate; then removing said photoresist; then performing a second ion implant of a conductivity-modifying dopant having the same conductivity type as in said first ion implant, in a vertical direction in the silicon substrate, wherein said second ion implant is at a higher Implantation dose than said first ion implant, in regions, between the field isolation regions and the gate structure; and heating the substrate to drive in dopants, whereby the outer edge, with respect to said gate structure, of a doped region formed by said first ion implant is offset from the outer edge of a more heavily doped region formed by said second ion implant.

Claim 2

A method of forming a retarded double diffused drain structure, in a silicon substrate with field isolation regions and a gate structure, comprising the steps of: first forming a layer of photoresist on the field isolation regions, the silicon substrate, and the gate structure; then patterning said photoresist to expose the silicon substrate and the gate structure, but covering an area of the silicon substrate that is offset from the field isolation regions; then performing a first ion implant of a conductivity-modifying dopant in a vertical direction in exposed regions of the silicon substrate; then removing said photoresist; then performing a second ion implant of a conductivity-modifying dopant having the same conductivity type as in said first ion implant, in a vertical direction in the silicon substrate, wherein said second ion implant is at a higher Implantation dose than said first ion implant, in regions, between the field isolation regions and the gate structure; and heating the substrate to drive in dopants, whereby the outer edge, with respect to said gate structure, of a doped region formed by said first ion implant is offset from the outer edge of a more heavily doped region formed by said second ion implant.

Claim 8

A method of forming a retarded double diffused drain structure in the drain region of a field effect transistor, in a silicon substrate with field isolation regions, a gate structure and a source region, comprising the steps of: first forming a layer of photoresist on the field isolation regions, the silicon substrate, and the gate structure; then patterning said photoresist to expose a part of the drain region, offset from the field isolation region; then performing a first ion implant of a conductivity-modifying dopant in said exposed part of the drain region, in a vertical direction; then removing said photoresist; then performing a second ion implant of a conductivity-modifying dopant having the same conductivity type as in said first ion implant, in a vertical direction wherein said second ion implant is at a higher implantation dose than said first ion implant, to form a source in the source region and the retarded double diffused drain structure in the drain region; and heating the substrate to drive in dopants, whereby the outer edge, with respect to said gate structure, of a doped region formed by said first ion implant is offset from the outer edge of a more heavily doped region formed by said second ion implant.

Claim 9

A method of forming a retarded double diffused drain structure in the drain region of a field effect transistor, in a silicon substrate with field isolation regions, a gate structure and a source region, comprising the steps of: first forming a layer of photoresist on the field isolation regions, the silicon substrate, and the gate structure; then patterning said photoresist to expose a part of the drain region, offset from the field isolation region; then performing a first ion implant of a conductivity-modifying dopant in said exposed part of the drain region, in a vertical direction; then removing said photoresist; then performing a second ion implant of a conductivity-modifying dopant having the same conductivity type as in said first ion implant, in a vertical direction wherein said second ion implant is at a higher implantation dose than said first ion implant, to form a source in the source region and the retarded double diffused drain structure in the drain region; and heating the substrate to drive in dopants, whereby the outer edge, with respect to said gate structure, of a doped region formed by said first ion implant is offset from the outer edge of a more heavily doped region formed by said second ion implant.

Claim 15

A method of forming a retarded double diffused drain structure, in a silicon substrate with field isolation regions and a gate structure, comprising the steps of: first forming a layer of photoresist on the field isolation regions, the silicon substrate, and the gate structure; then, patterning said photoresist to expose the silicon substrate and the gate structure, but covering an area of the silicon substrate that is offset from the field isolation regions; then performing a first ion implant of a conductivity-modifying dopant in a vertical direction in exposed regions of the silicon substrate; then removing said photoresist; then forming an insulating layer on the field isolation region, the silicon substrate and the gate structure; then patterning said insulating layer to form spacers adjacent to said gate structure; then performing a second ion implant of a conductivity-modifying dopant having the same conductivity type as in said first ion implant, in a vertical direction in the silicon substrate wherein said second ion implant is at a higher implantation dose than said first ion implant, in regions between the field isolation regions and said spacers; and heating the substrate to drive in dopants, whereby the outer edge, with respect to said gate structure, of a doped region formed by said first ion implant is offset from the outer edge of a more heavily doped region formed by said second ion implant.

Claim 16

A method of forming a retarded double diffused drain structure, in a silicon substrate with field isolation regions and a gate structure, comprising the steps of: first forming a layer of photoresist on the field isolation regions, the silicon substrate, and the gate structure; then, patterning said photoresist to expose the silicon substrate and the gate structure, but covering an area of the silicon substrate that is offset from the field isolation regions; then performing a first ion implant of a conductivity-modifying dopant in a vertical direction in exposed regions of the silicon substrate; then removing said photoresist; then forming an insulating layer on the field isolation region, the silicon substrate and the gate structure; then patterning said insulating layer to form spacers adjacent to said gate structure; then performing a second ion implant of a conductivity-modifying dopant having the same conductivity type as in said first ion implant, in a vertical direction in the silicon substrate wherein said second ion implant is at a higher implantation dose than said first ion implant, in regions between the field isolation regions and said spacers; and heating the substrate to drive in dopants, whereby the outer edge, with respect to said gate structure, of a doped region formed by said first ion implant is offset from the outer edge of a more heavily doped region formed by said second ion implant.