Method of uniformly etching refractory metals, refractory metal alloys and refractory metal silicides
AssigneeCypress Semiconductor Corporation
InventorT. Frank Wang
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Abstract
This invention is directed to a process for etching a semiconductor device using an etchant composition to form a predetermined etched pattern therein. The semiconductor device typically has a plurality of layers. At least one of the layers comprises a refractory metal, refractory metal alloy or refractory metal silicide. The etchant composition contains a high concentration of chlorine. The source (or TCP) power is decreased over that of conventional methods, and the bias (or RF) power is increased. Using such an etchant composition, along with the adjusted power levels, uniform etching and increased oxide selectivity is achieved.
Claims13
A method for etching a semiconductor device to form a predetermined etched pattern therein, comprising:
- (a) providing a semiconductor device having a plurality of layers, at least one of the layers of the semiconductor device comprising a refractory metal-containing material;
- and
- (b) etching the semiconductor device under conditions with an etchant composition comprising a first etchant chemistry comprising a chlorine source and a fluorine source which has a chlorine concentration of about 56 percent to about 90 percent and a second etchant chemistry comprising a chlorine source, providing a uniformity of etch rate across the plurality of layers in said method of ± about 3.5 percent, wherein the chlorine source of the first etchant chemistry and the second etchant chemistry is free of BCl3.
A method of etching a refractory metal-containing layer and an oxide layer, the method comprising:
- (a) etching the refractory metal-containing layer to an end point using a first etchant chemistry at a bias power of from about 100 watts to about 750 watts, wherein the first etchant chemistry comprises a chlorine source and a fluorine source and has a chlorine concentration of about 56 percent to about 90 percent;
- and
- (b) etching partially through the oxide layer using a second etchant chemistry, wherein the second etchant chemistry comprises a chlorine source and is free of a fluorine source, and wherein the chlorine source of the first etchant chemistry and the second etchant chemistry is free of BCl3.
Dependencies are inferred from the claim text.