System for indirectly monitoring and controlling a process with particular application to plasma processes
First Claim
1. A system for controlling a process implemented by a processing apparatus, the process being characterized by process state having a plurality of process properties, each process property having a process property value at each instant in time, comprising:
- means for detecting a process fingerprint, the process fingerprint being indirectly representative of a plurality of process property values;
a process condition monitor for monitoring the process in real-time to ascertain whether a particular process condition exists;
a process property estimator for estimating a process property value at an instant in time based on the process fingerprint;
means for comparing the process property value estimate to a target process property value to produce a process property value difference; and
means for determining a control response as a function of the process property value difference, the control response adapted to change the process property value and the process state of the processing apparatus in real-time based on the process property value difference.
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Accused Products
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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Citations
12 Claims
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1. A system for controlling a process implemented by a processing apparatus, the process being characterized by process state having a plurality of process properties, each process property having a process property value at each instant in time, comprising:
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means for detecting a process fingerprint, the process fingerprint being indirectly representative of a plurality of process property values; a process condition monitor for monitoring the process in real-time to ascertain whether a particular process condition exists; a process property estimator for estimating a process property value at an instant in time based on the process fingerprint; means for comparing the process property value estimate to a target process property value to produce a process property value difference; and means for determining a control response as a function of the process property value difference, the control response adapted to change the process property value and the process state of the processing apparatus in real-time based on the process property value difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for controlling a plasma process implemented by a processing apparatus, the process being characterized by a process state having a plurality of process properties, each process property having a process property value at each instant in time, comprising:
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means for detecting a process fingerprint, the process fingerprint being indirectly representative of a plurality of process property values; a multilayer perceptron neural network for producing a process property value estimate at an instant in time for a particular process property based on said process fingerprint; means for comparing the process property value estimate to a target process property value to produce a process property value difference; and means for determining a control response as a function of the process property value difference, the control response adapted to change the process property value and the process state of the processing apparatus in real-time based on the process property value difference. - View Dependent Claims (10)
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11. A system for controlling a plasma process implemented by a processing apparatus, the process being characterized by a process state having a plurality of process properties, each process property having a process property value at each instant in time, comprising:
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means for detecting a process fingerprint, the process fingerprint being indirectly representative of a plurality of process property values; a fuzzy min-max neural network for monitoring the process to ascertain whether a particular process property value exists and to generate a process property value estimate; means for comparing the process property value estimate to a target process property value to produce a process property value difference; and means for determining a control response as a function of the process property value difference, the control response adapted to change the process property value and the process state of the processing apparatus in real-time based on the process property value difference. - View Dependent Claims (12)
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Specification