US4411734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Etching of tantalum silicide/doped polysilicon structures
Assignee: Intersil Corp
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Filing: 1982-12-09
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Granted: 1983-10-25
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Expires: 2002-12-09
Abstract
Abstract A method of forming and anisotropically etching a structure on a substrate, said structure being comprised of a layer of doped polycrystalline silicon having thereover a layer of tantalum silicide. The method comprises providing a layer of polycrystalline silicon on the substrate, doping the silicon to render it conductive, preparing the surface of the silicon for deposition of tantalum silicide by treatment with a carbon tetrafluoride/oxygen plasma, depositing tantalum silicide thereon tantalum rich, anisotropically plasma etching the two-layered structure with an etchant mixture of carbon tetrachloride, oxygen and nitrogen, annealing the tantalum silicide layer and, if desired, covering the resultant structure with a protective layer of oxide. In a preferred embodiment, the silicon layer is deposited in the amorphorus state and annealed to the polycrystalline state.
Inventors
- 👤 Jer-shen Maa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:37
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
122 words
A method of forming a patterned structure on a substrate comprised of a layer of doped polycrystalline silicon having thereover a layer of tantalum silicide, said method comprising: (a) providing a layer of polycrystalline silicon on the substrate; (b) doping the silicon layer to render it conductive; (c) plasma treating the surface of the silicon layer with a mixture of carbon tetrafluoride and oxygen to prepare the surface for deposition of tantalum silicide; (d) depositing a layer of tantalum silicide onto the silicon layer; (e) anisotropically plasma etching the tantalum silicide layer and the silicon layer with an etchant mixture of carbon tetrachloride, oxygen and nitrogen; and (f) heating the resulting structure to a temperature sufficient to anneal the tantalum silicide layer.
Claim 2
Independent Claim
122 words
A method of forming a patterned structure on a substrate comprised of a layer of doped polycrystalline silicon having thereover a layer of tantalum silicide, said method comprising: (a) providing a layer of polycrystalline silicon on the substrate; (b) doping the silicon layer to render it conductive; (c) plasma treating the surface of the silicon layer with a mixture of carbon tetrafluoride and oxygen to prepare the surface for deposition of tantalum silicide; (d) depositing a layer of tantalum silicide onto the silicon layer; (e) anisotropically plasma etching the tantalum silicide layer and the silicon layer with an etchant mixture of carbon tetrachloride, oxygen and nitrogen; and (f) heating the resulting structure to a temperature sufficient to anneal the tantalum silicide layer.
Claim 3
Dependent Claim
47 words
A method in accordance with claim 1, wherein the silicon layer is deposited in the amorphous state by low pressure chemical vapor deposition from a source of silicon at a temperature of from about 560° to 580° C. and annealed to convert it to the polycrystalline state.
Claim 4
Dependent Claim
14 words
A method in accordance with claim 2, wherein the source of silicon is silane.
Claim 5
Dependent Claim
71 words
A method in accordance with claim 1, wherein the silicon layer is deposited in the polycrystalline state by low pressure chemical vapor deposition from a source of silicon at a temperature of about 620° C., said method additionally including the step of treating the surface of the substrate after said plasma etching step to remove residual particles of silicon by plasma etching with an etchant composition comprising carbon tetrafluoride and oxygen.
Claim 6
Dependent Claim
14 words
A method in accordance with claim 4, wherein the source of silicon is silane.
Claim 7
Dependent Claim
31 words
A method in accordance with claim 4, wherein said particles are removed utilizing an etchant mixture comprising tetrafluoride and oxygen in a ratio of from about 90:10 to about 99:1by volume.
Claim 8
Dependent Claim
23 words
A method in accordance with claim 6, wherein said mixture comprises carbon tetrafluoride and oxygen in a ratio of about 97:3 by volume.
Claim 9
Dependent Claim
15 words
A method in accordance with claim 1, wherein siad silicon layer is doped with phosphorus.
Claim 10
Dependent Claim
31 words
A method in accordance with claim 8, wherein the silicon layer is doped by diffusion of a source of phosphorus at a temperature of from about 850° to about 950° C.
Claim 11
Dependent Claim
15 words
A method in accordance with claim 9, wherein the source of phosphorus is phorphorus oxychloride.
Claim 12
Dependent Claim
26 words
A method in accordance with claim 1, wherein the mixture in step (c) is comprised of carbon tetrafluoride and oxygen in the proportion 97:3 by volume.
Claim 13
Dependent Claim
18 words
A method in accordance with claim 1, wherein the layer of tantalum silicide is deposited by magnetron sputtering.
Claim 14
Dependent Claim
32 words
A method in accordance with claim 12, wherein the layer of tantalum silicide is deposited in a molar ratio of one part tantalum to from about 1.5 to about 1.9 parts silicon.
Claim 15
Dependent Claim
28 words
A method in accordance with claim 13, wherein the layer of tantalum silicide is deposited in a molar ratio of one part tantalum to about 1.6 parts silicon.
Claim 16
Dependent Claim
48 words
A method in accordance with claim 1, wherein the etchant mixture in step (e) 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 17
Dependent Claim
36 words
A method in accordance with claim 15, wherein the etchant mixture in step (e) comprises, on a volume basis, about 59 percent of carbon tetrachloride, about 2.5 percent of oxygen and about 38.5 percent of nitrogen.
Claim 18
Dependent Claim
29 words
A method in accordance with claim 1, wherein the tantalum silicide layer is annealed in an argon atmosphere at a temperature of from about 800° to about 950° C.
Claim 19
Dependent Claim
21 words
A method in accordance with claim 17, wherein the tantalum silicide layer is annealed at a temperature of about 900° C.
Claim 20
Dependent Claim
29 words
A method in accordance with claim 1 additionally including the step of forming a layer of silicon dioxide over the structure after the tantalum silicide layer has been annealed.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-24 | 1987-04-25 | 1987-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-24 | 1991-04-25 | 1991-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-24 | 1995-04-25 | 1995-10-25 | $7700.00 | Window Closed / Lapsed |