| 摘要 |
We have discovered a method which permits plasma etching at a constant etch rate. The constant etch rate is achieved by controlling plasma process parameters so that a stable plasma is obtained, with a portion of the power deposited to the plasma being a capacitive contribution, and a portion being an inductive contribution. In particular, a stable plasma may be obtained within two process regions. In the first region, the gradient of the capacitive power to the power applied to the inductively coupled source for plasma generation [∂Pcap/∂PRF] is greater than 0. In the second region, plasma stability is controlled so that [∂Pcap/∂PRF] is less than 0 and so that Pcap<<PRF. Typically, the magnitude of Pcap is less than about 10% of the magnitude of PRF. Operation of the etch process in a stable plasma region enables use of a timed etch end point.
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