US4956314A
Expired / Lapsed
US
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Differential etching of silicon nitride
Assignee: Motorola Solutions Inc
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Filing: 1989-05-30
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Granted: 1990-09-11
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Expires: 2009-05-30
Abstract
Abstract A method for differentially etching silicon nitride, preferably formed in a hydrogen free environment, wherein hydrogen is implanted into various regions of the silicon nitride. The silicon nitride may then be etched by a number of different etchants, some of which will etch the implanted regions appreciably faster and others which will etch the non-implanted regions more quickly. This method is especially useful in the fabrication of self-aligned gate devices.
Inventors
- 👤 Gordon Tam
- 👤 Ronald N. Legge
- 👤 Wayne M. Paulson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:16
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/061; H10D30/0612; H10D30/0614; H10D64/00; H10D64/01; H10D64/012; H10D64/0124; H10D64/0125; H10P; H10P30/00; H10P30/40; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
38 words
A method for differentially etching silicon nitride comprising the steps of: forming a silicon nitride layer in an essentially hydrogen-free environment; implanting hydrogen into various regions of said silicon nitride layer; and differentially etching said silicon nitride layer.
Claim 2
Independent Claim
38 words
A method for differentially etching silicon nitride comprising the steps of: forming a silicon nitride layer in an essentially hydrogen-free environment; implanting hydrogen into various regions of said silicon nitride layer; and differentially etching said silicon nitride layer.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein the silicon nitride layer is formed by reactive sputtering.
Claim 4
Dependent Claim
19 words
The method of claim 1 wherein the silicon nitride layer is wet etched by hydrofluoric acid or phosphoric acid.
Claim 5
Dependent Claim
27 words
The method of claim 1 wherein the silicon nitride layer is dry etched by a plasma containing sulfur hexafluoride or a mixture of oxygen and carbon tetrafluoride.
Claim 6
Dependent Claim
17 words
The method of claim 1 wherein hydrogen is implanted into the silicon nitride layer at an angle.
Claim 7
Dependent Claim
88 words
The method of claim 1 wherein a FET is formed by further performing the steps of: providing a semiconductor substrate having a surface including a doped channel therein, the silicon nitride layer being formed on said surface of said substrate; forming a mask on said silicon nitride layer prior to implanting hydrogen; forming doped regions in said surface of said substrate before or after differentially etching said silicon nitride layer; removing said mask; forming ohmic metal above said doped regions; and forming gate metal above said doped channel.
Claim 8
Dependent Claim
38 words
The method of claim 6 wherein the silicon nitride layer is partially etched prior to the formation of the doped regions and the remainder of the silicon nitride layer is etched following the formation of the doped regions.
Claim 9
Independent Claim
71 words
A method of forming a FET employing differential etching of silicon nitride comprising the steps of: providing a semiconductor substrate having a surface; forming a silicon nitride layer on said surface of said substrate, said silicon nitride layer being formed in an essentially hydrogen-free environment; forming a mask on said silicon nitride layer; implanting hydrogen into said unmasked portions of said silicon nitride layer; and differentially etching said silicon nitride layer.
Claim 10
Independent Claim
71 words
A method of forming a FET employing differential etching of silicon nitride comprising the steps of: providing a semiconductor substrate having a surface; forming a silicon nitride layer on said surface of said substrate, said silicon nitride layer being formed in an essentially hydrogen-free environment; forming a mask on said silicon nitride layer; implanting hydrogen into said unmasked portions of said silicon nitride layer; and differentially etching said silicon nitride layer.
Claim 11
Dependent Claim
15 words
The method of claim 8 wherein the silicon nitride layer is formed by reactive sputtering.
Claim 12
Dependent Claim
18 words
The method of claim 8 wherein the silicon nitride layer is wet etched by hydrofluoric or phosphoric acid.
Claim 13
Dependent Claim
27 words
The method of claim 8 wherein the silicon nitride layer is dry etched by a plasma containing sulfur hexafluoride or a mixture of oxygen and carbon tetrafluoride.
Claim 14
Dependent Claim
17 words
The method of claim 8 wherein hydrogen is implanted into the silicon nitride layer at an angle.
Claim 15
Independent Claim
198 words
A method of forming a FET employing differential etching of silicon nitride comprising the steps of: providing a semiconductor substrate having a surface; forming a doped channel in said surface of said substrate; forming a silicon nitride layer on said surface of said substrate, said silicon nitride layer being formed in an essentially hydrogen-free environment; forming a photoresist region on said silicon nitride layer, said photoresist region being disposed above said doped channel; implanting hydrogen into said silicon nitride layer excepting that disposed beneath said photoresist region; partially etching through said hydrogen implanted silicon nitride layer; forming doped regions in said surface of said substrate beneath said partially etched silicon nitride layer; removing said photoresist region; implanting hydrogen into said silicon nitride layer; etching away said silicon nitride layer to expose said surface of said wafer excepting a portion of said silicon nitride layer disposed above said doped channel; forming ohmic metal above said doped regions; forming a polymer layer on said ohmic metal and said surface of said substrate leaving said portion of said silicon nitride layer exposed; removing said portion of said silicon nitride layer to form an opening; and forming gate metal in said opening.
Claim 16
Independent Claim
198 words
A method of forming a FET employing differential etching of silicon nitride comprising the steps of: providing a semiconductor substrate having a surface; forming a doped channel in said surface of said substrate; forming a silicon nitride layer on said surface of said substrate, said silicon nitride layer being formed in an essentially hydrogen-free environment; forming a photoresist region on said silicon nitride layer, said photoresist region being disposed above said doped channel; implanting hydrogen into said silicon nitride layer excepting that disposed beneath said photoresist region; partially etching through said hydrogen implanted silicon nitride layer; forming doped regions in said surface of said substrate beneath said partially etched silicon nitride layer; removing said photoresist region; implanting hydrogen into said silicon nitride layer; etching away said silicon nitride layer to expose said surface of said wafer excepting a portion of said silicon nitride layer disposed above said doped channel; forming ohmic metal above said doped regions; forming a polymer layer on said ohmic metal and said surface of said substrate leaving said portion of said silicon nitride layer exposed; removing said portion of said silicon nitride layer to form an opening; and forming gate metal in said opening.
Claim 17
Dependent Claim
17 words
The method of claim 13 wherein the layer of silicon nitride material is formed by reactive sputtering.
Claim 18
Dependent Claim
20 words
The method of claim 13 wherein the partially etching and etching steps are performed by wet etching with hydrofluoric acid.
Claim 19
Dependent Claim
21 words
The method of claim 13 wherein the implanting hydrogen steps include implanting hydrogen into the silicon nitride layer at an angle.
Claim 20
Independent Claim
45 words
A method for differentially etching silicon nitride comprising the steps of: forming a silicon nitride layer in an essentially hydrogen-free environment; implanting hydrogen into various regions of said silicon nitride layer, said hydrogen being implanted at an angle; and differentially etching said silicon nitride layer.
Claim 21
Independent Claim
45 words
A method for differentially etching silicon nitride comprising the steps of: forming a silicon nitride layer in an essentially hydrogen-free environment; implanting hydrogen into various regions of said silicon nitride layer, said hydrogen being implanted at an angle; and differentially etching said silicon nitride layer.
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