US4829024A
Expired / Lapsed
US
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Method of forming layered polysilicon filled contact by doping sensitive endpoint etching
Assignee: Motorola Solutions Inc
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Filing: 1988-09-02
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Granted: 1989-05-09
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Expires: 2008-09-02
Abstract
Abstract A semiconductor process is provided for the formation of a very low resistance contact. After a straight wall contact is formed conventionally above a silicon substrate, a blanket metal barrier layer is deposited. A plurality of planar polysilicon layers are deposited above the metal barrier layer. The polysilicon layers have varying doping levels and are etched away. A byproduct gas of the etch reaction is monitored and the transition between polysilicon layers can be accurately noted. In this way, a layer of doped polysilicon is left above the metal barrier in the contact region. Metal may then be patterned over the entire structure to provide a low resistance reliable contact.
Inventors
- 👤 Jeffrey L. Klein
- 👤 Stephen S. Poon
- 👤 Mark S. Swenson
- 👤 Sudhir K. Madan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:55
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0113; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/056; H10W20/057
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
210 words
A method of forming a layered polysilicon contact, comprising the steps of: providing a substrate material with a doped diffusion region in a portion of the substrate material and at a top surface of the substrate material; depositing a layer of electrically insulating material above the substrate material and doped diffusion region; forming a contact fill region with substantially vertical sidewalls by removing a portion of insulating material to expose a portion of a top surface of the doped diffusion region; forming a first layer of a first metal over both the layer of electrically insulating material and the top surface of the doped diffusion region; forming a layer of a metal barrier material over the layer of first metal; depositing a first layer of polysilicon having an impurity added thereto above the layer of metal barrier material; depositing a second layer of polysilicon having substantially less impurity added thereto above the first layer of polysilicon; depositing a third layer of polysilicon having the impurity added thereto above the second layer of polysilicon; etching away the second and third layers of polysilicon and maintaining the first layer of polysilicon; and forming a second layer of a second metal above the first layer of polysilicon substantially above the contact fill region.
Claim 2
Independent Claim
210 words
A method of forming a layered polysilicon contact, comprising the steps of: providing a substrate material with a doped diffusion region in a portion of the substrate material and at a top surface of the substrate material; depositing a layer of electrically insulating material above the substrate material and doped diffusion region; forming a contact fill region with substantially vertical sidewalls by removing a portion of insulating material to expose a portion of a top surface of the doped diffusion region; forming a first layer of a first metal over both the layer of electrically insulating material and the top surface of the doped diffusion region; forming a layer of a metal barrier material over the layer of first metal; depositing a first layer of polysilicon having an impurity added thereto above the layer of metal barrier material; depositing a second layer of polysilicon having substantially less impurity added thereto above the first layer of polysilicon; depositing a third layer of polysilicon having the impurity added thereto above the second layer of polysilicon; etching away the second and third layers of polysilicon and maintaining the first layer of polysilicon; and forming a second layer of a second metal above the first layer of polysilicon substantially above the contact fill region.
Claim 3
Dependent Claim
41 words
The method of claim 1 wherein the first layer of polysilicon is maintained after etching away the second and third layers of polysilicon by monitoring photoemissions provided from a chemical reaction used to etch the second and third layers of polysilicon.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein the metal barrier material is titanium nitride.
Claim 5
Dependent Claim
28 words
The method of claim 1 wherein the layer of electrically insulating material is dual layer comprising a layer of borophosphosilicate glass formed over a layer of undoped oxide.
Claim 6
Dependent Claim
26 words
The method of claim 1 wherein the third layer of polysilicon is deposited to a substantially larger thickness than the first and second layers of polysilicon.
Claim 7
Dependent Claim
16 words
The method of claim 1 wherein the first and second metals are the same metal material.
Claim 8
Independent Claim
237 words
A method of forming a polysilicon contact, comprising the steps of: providing a silicon substrate having a diffusion region contained therein and extending along a portion of a top surface of the substrate, said contact to provide electrical connectivity to the diffusion region; depositing a layer of electrically insulating material above the substrate and diffusion region; forming a contact fill region by removing a portion of the layer of electrically insulating material to expose a portion of a top surface of the substrate; depositing a layer of a first metal over both the electrically insulating material and the exposed top surface of the substrate; forming a layer of titanium nitride over the layer of metal; depositing polysilion above the layer of titanium nitride to completely fill said contact fill region, said polysilicon having at least two zones of differing impurity concentrations; selectively etching by a predetermined chemical reaction each of the at least two zones of polysilicon until etching to an endpoint indicating a zone of polysilicon immediately above the layer of titanium nitride adjacent the contact fill region, said endpoint being detected by monitoring a ratio of a product produced from the predetermined reaction and a reactant used in the predetermined reaction and detecting a variation in the ratio when said endpoint is reached; and forming a layer of a second metal above the polysilicon which is not etched and substantially above the contact fill region.
Claim 9
Independent Claim
237 words
A method of forming a polysilicon contact, comprising the steps of: providing a silicon substrate having a diffusion region contained therein and extending along a portion of a top surface of the substrate, said contact to provide electrical connectivity to the diffusion region; depositing a layer of electrically insulating material above the substrate and diffusion region; forming a contact fill region by removing a portion of the layer of electrically insulating material to expose a portion of a top surface of the substrate; depositing a layer of a first metal over both the electrically insulating material and the exposed top surface of the substrate; forming a layer of titanium nitride over the layer of metal; depositing polysilion above the layer of titanium nitride to completely fill said contact fill region, said polysilicon having at least two zones of differing impurity concentrations; selectively etching by a predetermined chemical reaction each of the at least two zones of polysilicon until etching to an endpoint indicating a zone of polysilicon immediately above the layer of titanium nitride adjacent the contact fill region, said endpoint being detected by monitoring a ratio of a product produced from the predetermined reaction and a reactant used in the predetermined reaction and detecting a variation in the ratio when said endpoint is reached; and forming a layer of a second metal above the polysilicon which is not etched and substantially above the contact fill region.
Claim 10
Dependent Claim
25 words
The method of claim 7 wherein the layer of electrically insulating material is a dual layer of borophosphosilicate glass over a layer of undoped oxide.
Claim 11
Dependent Claim
23 words
The method of claim 7 wherein the ratio is a ratio of a chemical compound containing fluorine and a chemical compound containing chlorine.
Claim 12
Dependent Claim
16 words
The method of claim 7 wherein the first and second metals are the same metal material.
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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) | 1992-05-08 | 1992-11-07 | 1993-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-08 | 1996-11-07 | 1997-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-08 | 2000-11-07 | 2001-05-09 | $7700.00 | Window Closed / Lapsed |