Method for plasma etching tungsten
AssigneeTexas Instruments Incorporated
InventorsRhett B. Jucha, Cecil J. Davis, John I. Jones
Life of this patent
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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 SF.sub.6) plus a fluorosilane (e.g. SiF.sub.4), 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.
Claims11
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.
A method for etching tungsten on a wafer comprising:
- (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.
A method for etching Tungsten on a wafer in a process chamber, comprising the steps of:
- (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.
Dependencies are inferred from the claim text.