Manufacture of CMOS devices

Claim 1

A method of forming a semiconductor integrated circuit structure, comprising the steps of: implanting, in a single implant step, an N-type dopant into a selected portion of a substrate; growing a first oxide layer over said selected portion of the substrate, while simultaneously driving said N-type dopant into said substrate to form an N-well having a substantially uniform dopant concentration; implanting P-type dopant atoms into said substrate in regions not covered by said first oxide layer; and thereafter heating said substrate to drive said P-type dopant atoms to form a P-well region having a depth approximately equal to the depth of said N-well and having a first dopant concentration; and thereafter uniformly implanting additional P-type dopant atoms into said P-well region to form a surface region therein having a dopant concentration higher than said first dopant concentration; removing said first oxide layer; forming a second oxide layer over the surface of said substrate; and patterning and etching said second oxide layer to leave a field oxide region over adjacent portions of said P-well and said N-well; and growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 2

A method of forming a semiconductor integrated circuit structure, comprising the steps of: implanting, in a single implant step, an N-type dopant into a selected portion of a substrate; growing a first oxide layer over said selected portion of the substrate, while simultaneously driving said N-type dopant into said substrate to form an N-well having a substantially uniform dopant concentration; implanting P-type dopant atoms into said substrate in regions not covered by said first oxide layer; and thereafter heating said substrate to drive said P-type dopant atoms to form a P-well region having a depth approximately equal to the depth of said N-well and having a first dopant concentration; and thereafter uniformly implanting additional P-type dopant atoms into said P-well region to form a surface region therein having a dopant concentration higher than said first dopant concentration; removing said first oxide layer; forming a second oxide layer over the surface of said substrate; and patterning and etching said second oxide layer to leave a field oxide region over adjacent portions of said P-well and said N-well; and growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 7

A method for integrated circuit fabrication, comprising the steps of: implanting an N-type dopant into a selected portion of a semiconductor substrate; growing a first oxide layer over said selected portion of the substrate, while simultaneously driving said N-type dopant into said substrate to form an N-well having a substantially uniform dopant concentration; implanting P-type dopant atoms into said substrate in regions not covered by said first oxide layer; and thereafter heating said substrate to drive said P-type dopant atoms thereinto to form a P-well region having a first dopant concentration; after said heating step, uniformly implanting additional P-type dopant atoms into said P-well region to form a surface region therein having a dopant concentration higher than said first dopant concentration; removing said first oxide layer; forming a second oxide layer over the entire surface of said substrate; and patterning and etching said second oxide layer to leave a field oxide region over adjacent portions of said P-well and said N-well; and growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 8

A method for integrated circuit fabrication, comprising the steps of: implanting an N-type dopant into a selected portion of a semiconductor substrate; growing a first oxide layer over said selected portion of the substrate, while simultaneously driving said N-type dopant into said substrate to form an N-well having a substantially uniform dopant concentration; implanting P-type dopant atoms into said substrate in regions not covered by said first oxide layer; and thereafter heating said substrate to drive said P-type dopant atoms thereinto to form a P-well region having a first dopant concentration; after said heating step, uniformly implanting additional P-type dopant atoms into said P-well region to form a surface region therein having a dopant concentration higher than said first dopant concentration; removing said first oxide layer; forming a second oxide layer over the entire surface of said substrate; and patterning and etching said second oxide layer to leave a field oxide region over adjacent portions of said P-well and said N-well; and growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 15

A method for integrated circuit fabrication, comprising the steps of: implanting an N-type dopant into a selected portion of a semiconductor substrate; growing a first oxide layer over said selected portion of the substrate, while simultaneously driving said N-type dopant into said substrate to form an N-well having a substantially uniform dopant concentration; implanting P-type dopant atoms into said substrate in regions not covered by said first oxide layer; and thereafter heating said substrate to drive said P-type dopant atoms thereinto to form a P-well region having a first dopant concentration; and thereafter uniformly implanting additional P-type dopant atoms into said P-well region to form a surface region therein having a dopant concentration higher than said first dopant concentration; removing said first oxide layer; forming a second oxide layer over the surface of said substrate; patterning and etching said second oxide layer to leave a field oxide region over adjacent portions of said P-well and said N-well; and growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 16

A method for integrated circuit fabrication, comprising the steps of: implanting an N-type dopant into a selected portion of a semiconductor substrate; growing a first oxide layer over said selected portion of the substrate, while simultaneously driving said N-type dopant into said substrate to form an N-well having a substantially uniform dopant concentration; implanting P-type dopant atoms into said substrate in regions not covered by said first oxide layer; and thereafter heating said substrate to drive said P-type dopant atoms thereinto to form a P-well region having a first dopant concentration; and thereafter uniformly implanting additional P-type dopant atoms into said P-well region to form a surface region therein having a dopant concentration higher than said first dopant concentration; removing said first oxide layer; forming a second oxide layer over the surface of said substrate; patterning and etching said second oxide layer to leave a field oxide region over adjacent portions of said P-well and said N-well; and growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 23

A method of forming a semiconductor integrated circuit structure, comprising the steps of: forming N-well and P-well regions in a substantially monolithic substrate; implanting additional P-type dopant atoms, into said P-well regions only, to form a surface region therein having a dopant concentration higher than said first dopant concentration; uniformly growing a field oxide layer; patterning and etching said field oxide layer to leave field oxide regions over portions of said P-well and said N-well regions; and thereafter growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 24

A method of forming a semiconductor integrated circuit structure, comprising the steps of: forming N-well and P-well regions in a substantially monolithic substrate; implanting additional P-type dopant atoms, into said P-well regions only, to form a surface region therein having a dopant concentration higher than said first dopant concentration; uniformly growing a field oxide layer; patterning and etching said field oxide layer to leave field oxide regions over portions of said P-well and said N-well regions; and thereafter growing an additional oxide, which is thinner than said second oxide, over areas of said substrate which are exposed by said second oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 28

A method of forming a semiconductor integrated circuit structure, comprising the steps of: forming N-well and P-well regions in substantially monolithic semiconductor material; growing a field oxide layer; patterning and etching said field oxide layer to leave field oxide regions over portions of said P-well and said N-well regions; and thereafter growing an additional oxide, which is thinner than said field oxide layer, over areas of said substrate which are exposed by said field oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.

Claim 29

A method of forming a semiconductor integrated circuit structure, comprising the steps of: forming N-well and P-well regions in substantially monolithic semiconductor material; growing a field oxide layer; patterning and etching said field oxide layer to leave field oxide regions over portions of said P-well and said N-well regions; and thereafter growing an additional oxide, which is thinner than said field oxide layer, over areas of said substrate which are exposed by said field oxide layer, and thereafter removing said additional oxide; whereby said step of growing and removing said additional oxide removes damaged material.