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AssigneeApplied Materials, Inc.
InventorsPadmapani Nallan, John Holland, Valentin Todorov, Thorsten Lill
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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.
An apparatus for creating a stable plasma in a processing chamber, wherein said processing chamber comprises an inductively coupled plasma source, said apparatus including a computer automated control system which contains instructions for applying a predetermined RF power level to said inductively coupled plasma source and for applying a corresponding predetermined process chamber pressure in said processing chamber, with a RF power input having a power level PRF, with a part of said RF power input being coupled to said plasma source as a capacitive power component, Pcap, and wherein said predetermined RF power level is such that ∂Pcap/∂PRF is greater than 0, or ∂Pcap/∂PRF is less than 0 and, wherein the magnitude of_Pcap is about 10% or less than the magnitude of PRF, whereby a plasma created is said processing chamber is maintained in a stable condition.
Dependencies are inferred from the claim text.