Method of making fully self-aligned bipolar transistor involving a polysilicon collector contact formed in a slot with an oxide sidewall

Claim 1

An improved method of making a fully self-aligned bipolar transistor comprising: (a) forming one or more mask layers over a silicon substrate; (b) etching at least one of said one or more masking layers to define a base contact area and a spaced apart collector contact area with an unetched emitter contact area defined in between; (c) masking said base contact area; (d) forming a collector slot in a substrate of an integrated circuit structure through said collector contact area defined in said one or more mask layers; (e) oxidizing the sidewall of said collector slot; (f) forming a deeper portion of said collector slot after oxidizing said collector slot sidewall; (g) forming a collector region in said substrate through the wall of said collector slot below said oxidized collector slot sidewall; (h) filling said collector slot and said base and collector contact regions with polysilicon; (i) forming an emitter contact region between said collector and base contact regions; and (j) forming a base region in said substrate spaced from said collector slot by said oxide formed on the sidewall of said slot.

Claim 12

A method of making a fully self-aligned bipolar transistor having a slot collector separated from the active portions of said transistor by oxide formed on the wall of said collector slot which comprises: (a) forming one or more mask layers over a silicon substrate; (b) etching at least one of said one or more masking layers to define a base contact area and a spaced apart collector contact area; (c) forming a collector slot in said substrate through said collector contact area defined in said one or more mask layers; (d) oxidizing the sidewall of said partially formed collector slot; (e) forming a deeper portion of said slot; (f) doping said substrate through the bottom portions of said slot below the oxidized sidewall of said slot to formed a doped collector region in said substrate; (g) filling said slot and said base contact area and said collector contact area in said one or more mask layers with polysilicon; (h) removing at least that portion of said one or more mask layers remaining on said substrate between said collector contact region and said base contact region to leave a polysilicon collector contact on said substrate over said slot and a polysilicon base contact over said substrate spaced from said collector contact; (i) oxidizing the sidewalls of said polysilicon base and collector contacts exposed by said removal of said one or more mask layers; (j) forming an extrinsic base region in said substrate below said base contact; (k) forming an intrinsic base region in said substrate between said extrinsic base region and said oxide sidewall of said collector slot; (l) forming an emitter region in said substrate in the surface of said intrinsic base region; and (m) forming an emitter contact above said emitter region in said substrate, said emitter contact being separated from said base and collector contacts by said oxide formed on the sidewalls of said base and collector contacts.

Claim 13

A method of making a fully self-aligned bipolar transistor having a slot collector separated from the active portions of said transistor by oxide formed on the wall of said collector slot which comprises: (a) forming one or more mask layers over a silicon substrate; (b) etching at least one of said one or more masking layers to define a base contact area and a spaced apart collector contact area; (c) forming a collector slot in said substrate through said collector contact area defined in said one or more mask layers; (d) oxidizing the sidewall of said partially formed collector slot; (e) forming a deeper portion of said slot; (f) doping said substrate through the bottom portions of said slot below the oxidized sidewall of said slot to formed a doped collector region in said substrate; (g) filling said slot and said base contact area and said collector contact area in said one or more mask layers with polysilicon; (h) removing at least that portion of said one or more mask layers remaining on said substrate between said collector contact region and said base contact region to leave a polysilicon collector contact on said substrate over said slot and a polysilicon base contact over said substrate spaced from said collector contact; (i) oxidizing the sidewalls of said polysilicon base and collector contacts exposed by said removal of said one or more mask layers; (j) forming an extrinsic base region in said substrate below said base contact; (k) forming an intrinsic base region in said substrate between said extrinsic base region and said oxide sidewall of said collector slot; (l) forming an emitter region in said substrate in the surface of said intrinsic base region; and (m) forming an emitter contact above said emitter region in said substrate, said emitter contact being separated from said base and collector contacts by said oxide formed on the sidewalls of said base and collector contacts.

Claim 18

A method of making a fully self-aligned bipolar transistor in an integrated circuit structure having a polysilicon emitter contact separated from polysilicon collector and base contacts of said transistor by oxide formed on the sidewalls of said polysilicon collector and base contacts which comprises: (a) forming a first mask layer over a silicon substrate comprising a first mask material differing from said silicon substrate; (b) forming a second mask layer over said first mask layer comprising a mask material different from said first mask layer; (c) forming a third mask layer over said second mask layer comprising a material different than said second mask layer; (d) forming a fourth mask layer over said third mask layer comprising a material different from said third mask layer; (e) etching said fourth mask layer to define a base contact area and a spaced apart collector contact area; (f) masking said base contact area exposed through said fourth mask and then removing exposed portions of said third second and first mask layers to define a collector contact region above said silicon substrate; (g) forming a collector slot in said substrate through said collector contact area defined in said mask layers; (h) oxidizing the silicon substrate sidewall of said partially formed collector slot; (i) forming a deeper portion of said slot; (j) doping said silicon substrate through the bottom portions of said slot below the oxidized sidewall of said slot to formed a doped collector region in said substrate; (k) masking said collector contact region to expose said base contact opening formed in said fourth mask layer; (l) removing portions of said underlying third, second, and first mask layers exposed by said base contact opening in said fourth mask layer; (m) removing said mask over said collector contact region and filling said base contact region and said collector contact region, including said collector slot, with polysilicon; (n) planarizing said polysilicon to remove any polysilicon above said third mask layer; (o) removing at least said portion of said third and second mask layers between said polysilicon base contact and said polysilicon collector contact; (p) oxidizing the sidewalls of said polysilicon base and collector contacts exposed by said removal of said second and third mask layers; (q) forming an extrinsic base region in said silicon substrate below said polysilicon base contact; (r) forming an intrinsic base region in said substrate by implanting a dopant into said substrate through said first mask layer between said polysilicon base and collector contacts; (s) removing said first mask layer above said intrinsic base region; (t) depositing polysilicon into said area between said polysilicon base contact and said polysilicon collector contact to form a polysilicon emitter contact separated and insulated from said polysilicon base and collector contacts by the oxidized sidewalls of said polysilicon base and collector contacts; and (u) forming an emitter region in said substrate in the surface of said intrinsic base region by diffusing dopant into the surface of said intrinsic base region in said substrate from said polysilicon emitter contact.

Claim 19

A method of making a fully self-aligned bipolar transistor in an integrated circuit structure having a polysilicon emitter contact separated from polysilicon collector and base contacts of said transistor by oxide formed on the sidewalls of said polysilicon collector and base contacts which comprises: (a) forming a first mask layer over a silicon substrate comprising a first mask material differing from said silicon substrate; (b) forming a second mask layer over said first mask layer comprising a mask material different from said first mask layer; (c) forming a third mask layer over said second mask layer comprising a material different than said second mask layer; (d) forming a fourth mask layer over said third mask layer comprising a material different from said third mask layer; (e) etching said fourth mask layer to define a base contact area and a spaced apart collector contact area; (f) masking said base contact area exposed through said fourth mask and then removing exposed portions of said third second and first mask layers to define a collector contact region above said silicon substrate; (g) forming a collector slot in said substrate through said collector contact area defined in said mask layers; (h) oxidizing the silicon substrate sidewall of said partially formed collector slot; (i) forming a deeper portion of said slot; (j) doping said silicon substrate through the bottom portions of said slot below the oxidized sidewall of said slot to formed a doped collector region in said substrate; (k) masking said collector contact region to expose said base contact opening formed in said fourth mask layer; (l) removing portions of said underlying third, second, and first mask layers exposed by said base contact opening in said fourth mask layer; (m) removing said mask over said collector contact region and filling said base contact region and said collector contact region, including said collector slot, with polysilicon; (n) planarizing said polysilicon to remove any polysilicon above said third mask layer; (o) removing at least said portion of said third and second mask layers between said polysilicon base contact and said polysilicon collector contact; (p) oxidizing the sidewalls of said polysilicon base and collector contacts exposed by said removal of said second and third mask layers; (q) forming an extrinsic base region in said silicon substrate below said polysilicon base contact; (r) forming an intrinsic base region in said substrate by implanting a dopant into said substrate through said first mask layer between said polysilicon base and collector contacts; (s) removing said first mask layer above said intrinsic base region; (t) depositing polysilicon into said area between said polysilicon base contact and said polysilicon collector contact to form a polysilicon emitter contact separated and insulated from said polysilicon base and collector contacts by the oxidized sidewalls of said polysilicon base and collector contacts; and (u) forming an emitter region in said substrate in the surface of said intrinsic base region by diffusing dopant into the surface of said intrinsic base region in said substrate from said polysilicon emitter contact.