US4460435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Patterning of submicrometer metal silicide structures
Assignee: Intersil Corp
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Filing: 1983-12-19
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Granted: 1984-07-17
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Expires: 2003-12-19
Abstract
Abstract A method is disclosed of forming elongated strips, e.g. interconnections, of a doped polycrystalline silicon/refractory metal silicide structure having a width less than about one micrometer over a vertical step in a substrate wherein the walls of the substrate, after etching, are free of impurity deposits called stringers. The subject method comprises isotropically etching said structure utilizing a resist pattern having a width substantially larger than one micrometer, redefining the resist pattern to the desired width and anisotropically etching the structure to the desired width.
Inventors
- 👤 Jer-shen Maa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:33
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/947
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
171 words
A method of forming an elongated strip of conductive material comprising a layer of doped polycrystalline silicon having thereover a layer of a refractory metal silicide on a substrate, said strip transversing a vertical step on the substrate and having a width less than about 1 micrometer, said method comprising: (a) depositing a layer of doped polycrystalline silicon on the substrate; (b) depositing a layer of a refractory metal silicide thereover; (c) forming a patterned layer of resist material over the metal silicide layer, said pattern including an elongated strip having a width substantially larger than the desired width of said strip of conductive material; (d) isotropically etching the exposed portion of the metal silicide layer and the underlying doped polysilicon layer to the substrate; (e) irradiating and developing the remaining resist layer to reduce the width of said elongated strip to the desired width of said strip of conductive material; and (f) anisotropically etching the exposed metal silicide layer and the underlying doped polycrystalline layer to form said elongated strip.
Claim 2
Independent Claim
171 words
A method of forming an elongated strip of conductive material comprising a layer of doped polycrystalline silicon having thereover a layer of a refractory metal silicide on a substrate, said strip transversing a vertical step on the substrate and having a width less than about 1 micrometer, said method comprising: (a) depositing a layer of doped polycrystalline silicon on the substrate; (b) depositing a layer of a refractory metal silicide thereover; (c) forming a patterned layer of resist material over the metal silicide layer, said pattern including an elongated strip having a width substantially larger than the desired width of said strip of conductive material; (d) isotropically etching the exposed portion of the metal silicide layer and the underlying doped polysilicon layer to the substrate; (e) irradiating and developing the remaining resist layer to reduce the width of said elongated strip to the desired width of said strip of conductive material; and (f) anisotropically etching the exposed metal silicide layer and the underlying doped polycrystalline layer to form said elongated strip.
Claim 3
Dependent Claim
48 words
A method in accordance with claim 1, wherein the polycrystalline silicon layer is formed in the amorphous state by low pressure chemical vapor deposition from a vapor containing silicon at a temperature of from about 560° to 580° C. and annealed to convert it to the polycrystalline state.
Claim 4
Dependent Claim
12 words
A method in accordance with claim 2, wherein the vapor is silane.
Claim 5
Dependent Claim
22 words
A method in accordance with claim 2, wherein the silicon layer is doped in-situ by adding a suitable dopant to said vapor.
Claim 6
Dependent Claim
12 words
A method in accordance with claim 4, wherein said dopant is phosphine.
Claim 7
Dependent Claim
33 words
A method in accordance with claim 1, wherein the silicon layer is doped after deposition by diffusion from a source of phosphorus at a temperature of from about 850° to about 950° C.
Claim 8
Dependent Claim
15 words
A method in accordance with claim 6, wherein the source of phosphorus is phosphorus oxychloride.
Claim 9
Dependent Claim
41 words
A method in accordance with claim 1, additionally including the step of plasma treating the surface of the doped polycrystalline silicon with a mixture of carbon tetrafluoride and oxygen to prepare the surface for the deposition of the refractory metal silicide.
Claim 10
Dependent Claim
15 words
A method in accordance with claim 1, wherein the refractory metal silicide is tantalum silicide.
Claim 11
Dependent Claim
14 words
A method in accordance with claim 9, wherein said layer is deposited tantalum rich.
Claim 12
Dependent Claim
33 words
A method in accordance with claim 1, wherein the width of said elongated strip of resist material is from about 2 to 5 times the desired width of said strip of conductive material.
Claim 13
Dependent Claim
30 words
A method in accordance with claim 11, wherein the width of said elongated strip of resist material is about four times the desired width of said strip of conductive material.
Claim 14
Dependent Claim
27 words
A method in accordance with claim 1, wherein the isotropic etching in step (d) is plasma etching utilizing a mixture of carbon tetrafluoride, carbon tetrachloride and oxygen.
Claim 15
Dependent Claim
25 words
A method in accordance with claim 13, wherein said mixture comprises carbon tetrafluoride, carbon tetrachloride and oxygen in a ratio of about 20:20:2 by volume.
Claim 16
Dependent Claim
28 words
A method in accordance with claim 1, wherein said anisotropic etch in step (f) is a plasma etch using an etchant mixture of carbon tetrachloride, oxygen and nitrogen.
Claim 17
Dependent Claim
45 words
A method in accordance with claim 1, wherein said etchant mixture comprises, on a volume basis, from about 30 to about 80 percent of carbon tetrachloride, from about 1 to about 6 percent of oxygen and from about 20 to about 50 percent of nitrogen.
Claim 18
Dependent Claim
20 words
A method in accordance with claim 1, wherein the refractory metal silicide layer is annealed after said anisotropic etch step.
Claim 19
Dependent Claim
29 words
A method in accordance with claim 17, wherein the metal silicide layer is annealed in an argon atmosphere at a temperature of from abut 800° to about 950° C.
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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) | 1987-07-17 | 1988-01-16 | 1988-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-17 | 1992-01-16 | 1992-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-17 | 1996-01-16 | 1996-07-17 | $7700.00 | Window Closed / Lapsed |