| 摘要 |
An improved method for oxide etching that uses of a mixture of etching gases including CF4/C4F8/CO/Ar/N2 such that etching selectivity between oxide and other materials can be increased. Furthermore, the addition of a cleaning step between etching operations in this invention is able to remove most of the deposited polymers formed during the etching operation, hence etching stop phenomenon can be prevented. Also, the presence of N2 in the etching gas mixture is able to prevent the formation of polymers on the sidewalls of an etched contact opening. Hence, when metal is subsequently deposited into the opening to form a self-aligned silicide layer, there are few polymers to react with the metal atoms to form a layer of high resistance material on the sidewalls of the opening. Thus, reliability of the device can be maintained.
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