US4131497A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing self-aligned semiconductor devices
Assignee: International Business Machines Corp
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Filing: 1977-07-12
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Granted: 1978-12-26
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Expires: 1997-07-12
Abstract
Abstract A method of forming extremely small impurity regions within other impurity regions without the need for providing critical masks. In the preferred embodiment this is achieved by forming an undercut band within masking layers atop a substrate to define a first impurity region, such as the base region of a bipolar transistor. After this region is formed by the introduction of impurities, the undercut is filled-in by a chemical vapor deposition process. A blocking mask may then be used for the formation of the second impurity region, in this case the emitter, within the first region. The window of the second region is defined by the filled-in band, thereby insuring a selected distance between the peripheries of said first and second impurity regions. The same mask may also be used to form other self-aligned regions with the first region.
Inventors
- 👤 Bai-Cwo Feng
- 👤 George C. Feng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:29
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/69; H10P14/694; H10P14/6943; H10P14/69433; H10D; H10D84/00; H10D84/01; H10D84/0112; H10D84/02; H10D84/03; H10D84/038; H10P14/66; H10P14/662; H10P14/692; H10P14/6921; H10P14/69215; H10P14/6922; H10P14/6927; H10P76/00; H10P76/40; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6329; H10P14/6334
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
157 words
A method for forming an impurity region in a semiconductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper layer to overhang said lower layer at the periphery of said first window; forming a second masking layer, which includes a material which is etchable with the same etchant as said upper material, within said first window so as to fill-in said overhang; whereby the material which is etchable by said ethchant is thinner within said first window than at said periphery; etching a second window within said first window through said second masking layer, said material at said periphery acting as a mask; and introducing an impurity through said second window into said substrate to form said impurity region.
Claim 2
Independent Claim
157 words
A method for forming an impurity region in a semiconductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper layer to overhang said lower layer at the periphery of said first window; forming a second masking layer, which includes a material which is etchable with the same etchant as said upper material, within said first window so as to fill-in said overhang; whereby the material which is etchable by said ethchant is thinner within said first window than at said periphery; etching a second window within said first window through said second masking layer, said material at said periphery acting as a mask; and introducing an impurity through said second window into said substrate to form said impurity region.
Claim 3
Dependent Claim
39 words
A method as in claim 1 wherein: said lower material of said first masking layer is silicon dioxide; and said upper material of said first masking layer is selected from the group consisting of silicon nitride and silicon oxynitride.
Claim 4
Dependent Claim
27 words
A method as in claim 1 wherein said included material in said second masking layer is selected from the group consisting of silicon nitride and silicon oxynitride.
Claim 5
Dependent Claim
54 words
A method as in claim 3 wherein the step of forming said second masking layer includes, prior to the forming of said material which is selected from said group consisting of silicon nitride and silicon oxynitride: thermally growing silicon dioxide from said substrate, whereby said thermally-grown silicon dioxide at least partially fills-in said overhang.
Claim 6
Dependent Claim
48 words
A method as in claim 1 wherein: said lower material of said first masking layer is silicon dioxide; said upper material of said first masking layer is silicon nitride; and said second masking layer includes an upper coating of silicon nitride and a lower coating of silicon dioxide.
Claim 7
Dependent Claim
90 words
A method as in claim 5 for defining a second region within said first window which is self-aligned with respect to said impurity region comprising: etching a third window through said silicon nitride coating during said etching of said second window through said silicon nitride coating, while protecting the other portions of said masking layers; and etching said third window through said silicon dioxide coating after said etching of said second window through said silicon dioxide coating, while protecting the other portions of said masking layers and said second window.
Claim 8
Dependent Claim
35 words
A method as in claim 6 further comprising: during the formation of said impurity region, forming another impurity region of the same conductivity type in an area of said substrate outside of said first window.
Claim 9
Independent Claim
183 words
A method for forming an impurity region in a semiconductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper material to overhang said lower material at the periphery of said first window; forming a second masking layer atop said substrate within said first window so as to fill-in said overhang, said layer including lower and upper materials which are selectively etchable with respect to each other; said upper material of said second masking layer covering at least the portion of said upper material of said first masking layer at the periphery of said first window; said upper materials being etchable by the same etchant; etching at least a second window through said upper and lower materials of second masking layer, said material at said periphery acting as a mask; and introducing an impurity through said second window into said substrate to form said impurity region.
Claim 10
Independent Claim
183 words
A method for forming an impurity region in a semiconductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper material to overhang said lower material at the periphery of said first window; forming a second masking layer atop said substrate within said first window so as to fill-in said overhang, said layer including lower and upper materials which are selectively etchable with respect to each other; said upper material of said second masking layer covering at least the portion of said upper material of said first masking layer at the periphery of said first window; said upper materials being etchable by the same etchant; etching at least a second window through said upper and lower materials of second masking layer, said material at said periphery acting as a mask; and introducing an impurity through said second window into said substrate to form said impurity region.
Claim 11
Dependent Claim
104 words
A method as in claim 8 for defining another region within said first window which is self-aligned with respect to said impurity region comprising: etching a third window through said upper material of said second masking layer during said etching of said second window through said upper material of said second masking layer, while protecting the other portion of said masking layers; etching said third window through said lower material of said second masking layer after said etching of said second window through said lower material of said second masking layer, while protecting the other portions of said masking layers and said second window.
Claim 12
Dependent Claim
54 words
A method as in claim 8 further comprising the step of: during the etching of said second window, etching another window through said first and second masking layers at a portion of said substrate which is outside of said first window; and introducing another impurity through said other window to form another impurity region.
Claim 13
Dependent Claim
31 words
A method as in claim 8 wherein said lower material of said second masking layer fills-in said overhang to the substantial exclusion of said upper material of said second masking layer.
Claim 14
Dependent Claim
21 words
A method as in claim 8 wherein said lower and upper material of said second masking layer jointly fill-in said overhang.
Claim 15
Dependent Claim
33 words
A method as in claim 8 wherein: said upper materials of said masking layers are selected for the group consisting of silicon nitride and silicon oxynitride; and said lower materials are silicon dioxide.
Claim 16
Dependent Claim
19 words
A method as in claim 8 wherein: said lower materials are silicon dioxide; said upper materials are silicon nitride.
Claim 17
Dependent Claim
110 words
A method as in claim 14 for defining a second region within said first window which is self-aligned with respect to said impurity region comprising: etching a third window through said silicon nitride portion of said second masking layer during the etching of said second window through said silicon nitride portion of said second masking layer while protecting the other portions of said masking layers; and etching said third window through said silicon dioxide portion of said second masking layer after said etching of said second window through said silicon dioxide portion of said second masking layer, while protecting the other portions of said masking layers and said second window.
Claim 18
Dependent Claim
35 words
A method as in claim 15 further comprising: during the formation of said impurity region, forming another impurity region of the same conductivity type in an area of said substrate outside of said first window.
Claim 19
Independent Claim
184 words
A method for forming a PN junction in a semi-conductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper layer to overhang said lower layer at the periphery of said window; introducing an impurity of a first conductivity type through said first window into said substrate to form a first impurity region; forming a second masking layer which includes a material which is etchable with the same etchant as said upper material within said first window so as to fill-in said overhang; whereby the material which is etchable by said etchant is thinner within said first window than at said periphery; etching a second window within said first window through said second masking layer, said material at said periphery acting as a mask; and introducing an impurity of a second conductivity type through said second window into said first impurity region to form said PN junction.
Claim 20
Independent Claim
184 words
A method for forming a PN junction in a semi-conductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper layer to overhang said lower layer at the periphery of said window; introducing an impurity of a first conductivity type through said first window into said substrate to form a first impurity region; forming a second masking layer which includes a material which is etchable with the same etchant as said upper material within said first window so as to fill-in said overhang; whereby the material which is etchable by said etchant is thinner within said first window than at said periphery; etching a second window within said first window through said second masking layer, said material at said periphery acting as a mask; and introducing an impurity of a second conductivity type through said second window into said first impurity region to form said PN junction.
Claim 21
Dependent Claim
39 words
A method as in claim 17 wherein: said lower material of said first masking layer is silicon dioxide; and said upper material of said first masking layer is selected from the group consisting of silicon nitride and silicon oxynitride.
Claim 22
Dependent Claim
27 words
A method as in claim 17 wherein said included material in said second masking layer is selected from the group consisting of silicon nitride and silicon oxynitride.
Claim 23
Dependent Claim
54 words
A method as in claim 19 wherein the step of forming said second masking layer includes, prior to the forming of said material which is selected from said group consisting of silicon nitride and silicon oxynitride: thermally growing silicon dioxide from said substrate, whereby said thermally-grown silicon dioxide at least partially fills-in said overhang.
Claim 24
Dependent Claim
48 words
A method as in claim 17 wherein: said lower material of said first masking layer is silicon dioxide; said upper material of said first masking layer is silicon nitride; and said second masking layer includes an upper coating of silicon nitride and a lower coating of silicon dioxide.
Claim 25
Dependent Claim
100 words
A method as in claim 21 for defining a second region within said impurity region of said first conductivity type which is self-aligned with respect to said impurity region of said second conductivity type comprising: etching a third window through said silicon nitride coating during said etching of said second window through said silicon nitride coating, while protecting the other portions of said masking layers; and etching said third window through said silicon dioxide coating after said etching of said second window through said silicon dioxide coating, while protecting the other portions of said masking layers and said second window.
Claim 26
Dependent Claim
38 words
A method as in claim 22 further comprising: during the formation of said impurity region of said second conductivity type, forming another region of said second conductivity type in an area of said substrate outside of said window.
Claim 27
Independent Claim
208 words
A method for forming a PN junction in a semiconductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper layer to overhang said lower layer at the periphery of said window; introducing an impurity of a first conductivity type through said first window into said substrate to form a first impurity region; forming a second masking layer within said first window so as to fill-in said overhang, said layer including lower and upper materials which are selectively etchable with respect to each other; said upper material of said second masking layer covering at least the portion of said upper material of said first masking layer at the periphery of said first window; said upper materials being etchable by the same etchant; etching at least a second window through said upper and lower materials of said second masking layer, said material at said periphery acting as a mask; and introducing an impurity of a second conductivity type through said second window into said first impurity region to form said PN junction.
Claim 28
Independent Claim
208 words
A method for forming a PN junction in a semiconductor substrate comprising the steps of: forming a first masking layer atop said substrate, said layer including lower and upper materials which are selectively etchable with respect to each other; etching a first window within said first masking layer so as to cause a portion of said upper layer to overhang said lower layer at the periphery of said window; introducing an impurity of a first conductivity type through said first window into said substrate to form a first impurity region; forming a second masking layer within said first window so as to fill-in said overhang, said layer including lower and upper materials which are selectively etchable with respect to each other; said upper material of said second masking layer covering at least the portion of said upper material of said first masking layer at the periphery of said first window; said upper materials being etchable by the same etchant; etching at least a second window through said upper and lower materials of said second masking layer, said material at said periphery acting as a mask; and introducing an impurity of a second conductivity type through said second window into said first impurity region to form said PN junction.
Claim 29
Dependent Claim
101 words
A method as in claim 24 for defining another region within said first window which is self-aligned with respect to said impurity region of said second conductivity type comprising: etching a third window through said upper material of said second masking layer during said etching of said second window through said upper material of said second masking layer, while protecting the other portion of said masking layers; etching said third window through said lower material of said second masking layer after said second conductivity type region is formed while protecting the other portions of said masking layers and said second window.
Claim 30
Dependent Claim
59 words
A method as in claim 24 further comprising the step of: during the etching of said second window, etching another window through said first and second masking layers at a portion of said substrate which is outside of said first window; and introducing an impurity of said second conductivity type through said other window to form another impurity region.
Claim 31
Dependent Claim
31 words
A method as in claim 24 wherein said lower material of said second masking layer fills-in said overhang to the substantial exclusion of said upper material of said second masking layer.
Claim 32
Dependent Claim
21 words
A method as in claim 24 wherein said lower and upper material of said second masking layer jointly fill-in said overhang.
Claim 33
Dependent Claim
32 words
A method as in claim 24 wherein: upper materials of said masking layers are selected from the group consisting of silicon nitride and silicon oxynitride; and said lower materials are silicon dioxide.
Claim 34
Dependent Claim
19 words
A method as in claim 24 wherein: said lower materials are silicon dioxide; said upper materials are silicon nitride.
Claim 35
Dependent Claim
110 words
A method as in claim 30 for defining a second region within said first window which is self-aligned with respect to said impurity region comprising: etching a third window through said silicon nitride portion of said second masking layer during the etching of said second window through said silicon nitride, portion of said second masking layer while protecting the other portions of said masking layers; and etching said third window through said silicon dioxide portion of said second masking layer after said etching of said second window through said silicon dioxide, portion of said second masking layer, while protecting the other portions of said masking layers and said second window.
Claim 36
Dependent Claim
35 words
A method as in claim 31 further comprising: during the formation of said impurity region, forming another impurity region of the same conductivity type in an area of said substrate outside of said first window.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-12-25 | 1982-06-26 | 1982-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-12-25 | 1986-06-26 | 1986-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-12-25 | 1990-06-26 | 1990-12-26 | $7700.00 | Window Closed / Lapsed |