Claims
- 1. A gas composition for anisotropically etching refractory metal silicide comprising principally a mixture of Cl.sub.2, BCl.sub.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.
- 2. The gas composition of claim 1, wherein the fluorine-containing gas is selected from CF.sub.4 and NF.sub.3.
- 3. The etching gas composition of claim 1, wherein the dopant gas is a mixture of oxygen and CF.sub.4 containing at least 90 percent by volume CF.sub.4.
- 4. The etching gas composition of claim 1, wherein the dopant gas is NF.sub.3, for etching tungsten silicide.
- 5. The etching gas composition of claim 1, wherein the dopant gas is CF.sub.4, for etching tungsten silicide.
- 6. The etching as composition of claim 1, wherein the dopant gas is oxygen, for etching molybdenum silicide.
- 7. The etching gas composition of claim 1, wherein the volumetric flow ratios of HCl:BCl.sub.3 :Cl.sub.2 are (40-75):(80-40):(60-40).
- 8. The etching gas composition of claim 7, wherein the etching gas mixture comprises HCl:BCl.sub.3 :Cl.sub.2 :fluorinated etching gas in the volumetric flow ratio of about 75:40:40:20.
- 9. The etching gas composition of claim 8, wherein the reactive gas mixture comprises HCl:BCl.sub.3 :Cl.sub.2 :oxygen in a volumetric flow rate of about 75:40:40:(5-10).
Parent Case Info
This is a divisional application of Ser. No. 443,811, filed Nov. 29, 1989, now U.S. Pat. No. 5,112,435, which is a continuation of Ser. No. 185,256, filed Apr. 19, 1988, now abandoned, which is a continuation of Ser. No. 786,783, filed Oct. 11, 1985, now abandoned.
US Referenced Citations (5)
Divisions (1)
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Date |
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443811 |
Nov 1989 |
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Continuations (2)
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185256 |
Apr 1988 |
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Parent |
786783 |
Oct 1985 |
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