US5219485A
Expired / Lapsed
US
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Materials and methods for etching silicides, polycrystalline silicon and polycides
Assignee: Applied Materials Inc
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Filing: 1991-10-17
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Granted: 1993-06-15
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Expires: 2011-10-17
Abstract
Abstract Gas chemistry and a related RIE mode process is described for etching silicides of the refractory metals titanium, tantalum, tungsten and aluminum and for etching composites of these silicides on polycrystalline silicon layers. BCl 3 is added to the HCl/Cl 2 gas chemistry used for the polysilicon etch along with additives selected from fluorinated gases and oxygen to satisfy the multiple requirement of the two-step silicide-polysilicon etch process, including the silicide-to-polysilicon etch ratio requirement.
Inventors
- 👤 David N. Wang
- 👤 Mei Chang
- 👤 T. K. Leong, deceased
- 👤 executor Peter P. Leong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:13
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
72 words
A gas composition for anisotropically etching refractory metal silicide comprising principally a mixture of Cl 2 , BCl 3 and HCl and further comprising a small amount of dopant gas not exceeding twenty volume percent of the total gas, selected from fluorine-containing gas, oxygen, and a mixture of fluorine-containing gas and oxygen, for providing a high etch selectivity to organic photoresist masks and a high etch rate ratio of silicide to polysilicon.
Claim 2
Dependent Claim
72 words
A gas composition for anisotropically etching refractory metal silicide comprising principally a mixture of Cl 2 , BCl 3 and HCl and further comprising a small amount of dopant gas not exceeding twenty volume percent of the total gas, selected from fluorine-containing gas, oxygen, and a mixture of fluorine-containing gas and oxygen, for providing a high etch selectivity to organic photoresist masks and a high etch rate ratio of silicide to polysilicon.
Claim 3
Dependent Claim
19 words
The gas composition of claim 1, wherein the fluorine-containing gas is selected from CF 4 and NF 3 .
Claim 4
Dependent Claim
29 words
The etching gas composition of claim 1, wherein the dopant gas is a mixture of oxygen and CF 4 containing at least 90 percent by volume CF 4 .
Claim 5
Dependent Claim
19 words
The etching gas composition of claim 1, wherein the dopant gas is NF 3 , for etching tungsten silicide.
Claim 6
Dependent Claim
19 words
The etching gas composition of claim 1, wherein the dopant gas is CF 4 , for etching tungsten silicide.
Claim 7
Dependent Claim
17 words
The etching as composition of claim 1, wherein the dopant gas is oxygen, for etching molybdenum silicide.
Claim 8
Dependent Claim
19 words
The etching gas composition of claim 1, wherein the volumetric flow ratios of HCl:BCl 3 :Cl 2 are (40-75):(80-40):(60-40).
Claim 9
Dependent Claim
28 words
The etching gas composition of claim 7, wherein the etching gas mixture comprises HCl:BCl 3 :Cl 2 :fluorinated etching gas in the volumetric flow ratio of about 75:40:40:20.
Claim 10
Dependent Claim
26 words
The etching gas composition of claim 8, wherein the reactive gas mixture comprises HCl:BCl 3 :Cl 2 :oxygen in a volumetric flow rate of about 75:40:40:(5-10).
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1996-06-14 | 1996-12-14 | 1997-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-14 | 2000-12-14 | 2001-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-14 | 2004-12-14 | 2005-06-15 | $7700.00 | Window Closed / Lapsed |