Importance

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Abstract

The invention enables real-time control of a process using information regarding process properties that are indirectly related to the state of the process. A set of properties that characterize the process environment (fingerprint) is measured and used by a process results estimator to infer information regarding the state of the process and by a process condition monitor for monitoring the process to ascertain whether a particular type of condition exists. In one embodiment, optical emission spectra (OES) are used as the fingerprint. The process results estimator is sufficiently powerful to enable the process state to be inferred even when the relationship between the process environmental properties and the process state is complicated and difficult to describe with traditional mathematical models. In one embodiment, the process results estimator is embodied by a neural network. The process condition monitor can also be embodied by a neural network. Because the invention does not directly measure the process state, the invention is particularly useful in situations in which it is difficult or undesirable to directly determine the state of the process during the process such as monitoring and control of a plasma process such as plasma etching.

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First Claim