Retro-etch process for integrated circuits

Claim 1

A method of forming a narrow gap in a material comprising: A. forming a first masking layer upon the material; B. forming a second masking layer upon the first masking layer; C. forming a retro-etched area by partially retro-etching the first masking layer below the second masking layer; D. substantially filling said retro-etched area with a masking layer to mask said material below the retro-etched area; E. forming a third masking layer on said material not previously covered by the first masking layer or retro-etched area; F. removing said second masking layer and masking layer within said retro-etched area; and G. forming a gap in said material between said first and third masking layers.

Claim 2

A method of forming a narrow gap in a material comprising: A. forming a first masking layer upon the material; B. forming a second masking layer upon the first masking layer; C. forming a retro-etched area by partially retro-etching the first masking layer below the second masking layer; D. substantially filling said retro-etched area with a masking layer to mask said material below the retro-etched area; E. forming a third masking layer on said material not previously covered by the first masking layer or retro-etched area; F. removing said second masking layer and masking layer within said retro-etched area; and G. forming a gap in said material between said first and third masking layers.

Claim 11

A method of isolating active components within a silicon body comprising: A. forming a silicon dioxide layer upon the silicon body; B. forming a silicon nitride layer upon the silicon dioxide layer; C. forming a retro-etched area by etching the silicon dioxide layer to a predetermined area under the silicon nitride layer; D. forming an additional silicon nitride layer over the silicon body to substantially fill the retro-etched area; E. removing the silicon nitride as applied in step D except in the retro-etched area; F. forming a layer of silicon dioxide on the silicon body in areas not covered by silicon nitride; G. removing all remaining silicon nitride; H. etching any remaining silicon dioxide to expose the silicon body in the retro-etched area; and I. etching the silicon body to form an isolation groove.

Claim 12

A method of isolating active components within a silicon body comprising: A. forming a silicon dioxide layer upon the silicon body; B. forming a silicon nitride layer upon the silicon dioxide layer; C. forming a retro-etched area by etching the silicon dioxide layer to a predetermined area under the silicon nitride layer; D. forming an additional silicon nitride layer over the silicon body to substantially fill the retro-etched area; E. removing the silicon nitride as applied in step D except in the retro-etched area; F. forming a layer of silicon dioxide on the silicon body in areas not covered by silicon nitride; G. removing all remaining silicon nitride; H. etching any remaining silicon dioxide to expose the silicon body in the retro-etched area; and I. etching the silicon body to form an isolation groove.

Claim 13

A method of forming a narrow doped region on a silicon body comprising: A. forming a silicon dioxide layer upon the silicon body; B. forming a silicon nitride layer upon the silicon dioxide layer; C. forming a retro-etched area by etching the silicon dioxide layer to a predetermined area under the silicon nitride layer; D. forming an additional silicon nitride layer over the silicon body to substantially fill the retro-etched area; E. removing the silicon nitride as applied in step D except in the retro-etched area; F. forming a layer of silicon dioxide on the silicon body in areas not covered by silicon nitride; G. removing all remaining silicon nitride; H. etching any remaining silicon dioxide to expose the silicon body in the retro-etched area; and I. diffusing a dopant into the silicon body in the exposed retro-etched area.

Claim 14

A method of forming a narrow doped region on a silicon body comprising: A. forming a silicon dioxide layer upon the silicon body; B. forming a silicon nitride layer upon the silicon dioxide layer; C. forming a retro-etched area by etching the silicon dioxide layer to a predetermined area under the silicon nitride layer; D. forming an additional silicon nitride layer over the silicon body to substantially fill the retro-etched area; E. removing the silicon nitride as applied in step D except in the retro-etched area; F. forming a layer of silicon dioxide on the silicon body in areas not covered by silicon nitride; G. removing all remaining silicon nitride; H. etching any remaining silicon dioxide to expose the silicon body in the retro-etched area; and I. diffusing a dopant into the silicon body in the exposed retro-etched area.

Claim 15

A method of forming a narrow gap in a material comprising: A. forming a first masking layer upon the material; B. forming a second masking layer upon the first masking layer; C. forming a retro-etched area by partially retro-etching the first masking layer below the second masking layer so that the second masking layer has a lateral edge which overhangs a lateral edge of the first masking layer; D. covering all of the exposed surfaces, including the lateral edges of the first and second masking layers, with a masking layer having substantially the same composition as the second masking layer so that the retro-etched area is substantially filled; E. forming a third masking layer on the material not previously covered by the first masking layer or the retro-etched area; F. removing the second masking layer and the masking layer within the retro-etched area; and G. forming a gap in the material between the first and third masking layers by using the first and third masking layers to define the gap edges.

Claim 16

A method of forming a narrow gap in a material comprising: A. forming a first masking layer upon the material; B. forming a second masking layer upon the first masking layer; C. forming a retro-etched area by partially retro-etching the first masking layer below the second masking layer so that the second masking layer has a lateral edge which overhangs a lateral edge of the first masking layer; D. covering all of the exposed surfaces, including the lateral edges of the first and second masking layers, with a masking layer having substantially the same composition as the second masking layer so that the retro-etched area is substantially filled; E. forming a third masking layer on the material not previously covered by the first masking layer or the retro-etched area; F. removing the second masking layer and the masking layer within the retro-etched area; and G. forming a gap in the material between the first and third masking layers by using the first and third masking layers to define the gap edges.

Claim 22

A method of forming a narrow gap in a substrate surface using first and second masking materials having dissimilar etching characteristics comprising the steps of: A. forming a layer of the first material over the entire substrate surface; B. forming a layer of the second material over the layer of step A; C. forming a retro-etched area by partially retro-etching the layer of step A below the layer of step B so that the layer of step B has a lateral edge overhanging a lateral edge of the layer of step A; D. covering all of the substrate surface exposed by step C with a layer of the first material thinner than the layer of step A; E. covering all of the exposed surfaces, including said lateral edges, with a uniformly thick layer of the second material to substantially fill the retro-etched area; F. removing all of the covering of step E except in the retro-etch area; G. increasing the thickness of the exposed surface of the first material until it is at least as thick as the layer of step A; H. removing all of the second material; I. removing enough of the first material to expose the substrate surface between the layers of steps A and G; and J. forming a groove in the exposed substrate surface using the layers of steps A and G to define the groove width.

Claim 23

A method of forming a narrow gap in a substrate surface using first and second masking materials having dissimilar etching characteristics comprising the steps of: A. forming a layer of the first material over the entire substrate surface; B. forming a layer of the second material over the layer of step A; C. forming a retro-etched area by partially retro-etching the layer of step A below the layer of step B so that the layer of step B has a lateral edge overhanging a lateral edge of the layer of step A; D. covering all of the substrate surface exposed by step C with a layer of the first material thinner than the layer of step A; E. covering all of the exposed surfaces, including said lateral edges, with a uniformly thick layer of the second material to substantially fill the retro-etched area; F. removing all of the covering of step E except in the retro-etch area; G. increasing the thickness of the exposed surface of the first material until it is at least as thick as the layer of step A; H. removing all of the second material; I. removing enough of the first material to expose the substrate surface between the layers of steps A and G; and J. forming a groove in the exposed substrate surface using the layers of steps A and G to define the groove width.