Method for plasma etching tungsten
First Claim
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1. A method for etching Tungsten on a wafer comprising:
- (a) transferring a wafer into a vacuum processing chamber;
(b) applying a pressure to said chamber less than ambient to maintain said chamber at less than ambient;
(c) providing fluorine containing gas to a remote plasma chamber separated from said chamber and producing a remote plasma;
(d) adding a very weak oxygen source gas to said remote plasma chamber;
(e) adding a bromine containing gas and a resist selectivity enhancement has to said remote plasma chamber;
(f) applying a radio frequency signal across two electrodes one of which is adjacent to the wafer and causing a plasma to be formed whose dark space is in the vicinity of the surface of the slice; and
(g) flowing the gas mixture over said wafer disposed within said chamber.
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Abstract
A process wherein a thin film metal (e.g. tungsten) is anisotropically etched under plasma bombardment conditions by using a feed gas mixture which includes a fluorine source (such as SF6) plus a fluorosilane (e.g. SiF4), plus a bromine source (such as HBr), plus a weak oxygen source such as carbon monoxide. This chemistry provides anisotropic high rate fluoro-etching with good selectivity to photoresist.
115 Citations
11 Claims
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1. A method for etching Tungsten on a wafer comprising:
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(a) transferring a wafer into a vacuum processing chamber; (b) applying a pressure to said chamber less than ambient to maintain said chamber at less than ambient; (c) providing fluorine containing gas to a remote plasma chamber separated from said chamber and producing a remote plasma; (d) adding a very weak oxygen source gas to said remote plasma chamber; (e) adding a bromine containing gas and a resist selectivity enhancement has to said remote plasma chamber; (f) applying a radio frequency signal across two electrodes one of which is adjacent to the wafer and causing a plasma to be formed whose dark space is in the vicinity of the surface of the slice; and (g) flowing the gas mixture over said wafer disposed within said chamber. - View Dependent Claims (4, 5)
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2. A method for etching tungsten on a wafer comprising:
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(a) disposing said wafer into a process chamber at low pressure; (b) generating a remote plasma form a source of fluorine, a weak source of oxygen, and a source of bromide; (c) introducing said remote plasma into said chamber to a face of said wafer; and (d) generating an in situ plasma within said chamber. - View Dependent Claims (3, 6, 7)
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8. A method for etching Tungsten on a wafer in a process chamber, comprising the steps of:
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(a) generating free radicals from a fluorine containing gas, very weak oxygen source, a bromine containing gas and a resist selectivity enhancement gas to plasma generator remote from the process chamber; (b) introducing the free radicals to the process chamber and to a face of the wafer to be porocessed; and (c) generating an in situ plasma from the free radicals in the process chamber. - View Dependent Claims (9, 10, 11)
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Specification