Etch metric sensitivity for endpoint detection
First Claim
1. A method of generating a computational model that relates measured optical signals produced by optical energy interacting with features etched on a substrate to values of a target geometric parameter of the features etched on the substrate, the method comprising:
- determining a range of the measured optical signals for use in the computational model, wherein determining the range comprises;
identifying a first change in the measured optical signals in the range due to a variation in values of a non-target geometric parameter,identifying a second change in the measured optical signals in the range due to a variation in values of the target geometric parameter, anddetermining that the second change is greater than the first change;
providing a training set having members with values of the optical signals in the range, wherein each member of the training set comprises (i) a value of the target geometric parameter of the features etched in the substrate, and (ii) an associated optical signal produced from etched features having the value of the target geometric parameter of the features etched in the substrate; and
producing the computational model from the training set.
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Abstract
Monitoring a geometric parameter value for one or more features produced on a substrate during an etch process may involve: (a) measuring optical signals produced by optical energy interacting with features being etched on the substrate; (b) providing a subset of the measured optical signals, wherein the subset is defined by a range where optical signals were determined to correlate with target geometric parameter values for features; (c) applying the subset of optical signals to a model configured to predict the target geometric parameter values from the measured optical signals; (d) determining, from the model, a current value of the target geometric parameter of the features being etched; (e) comparing the current value of the target geometric parameter of the features being etched to an etch process endpoint value for the target geometric parameter; and (f) repeating (a)-(e) until the comparing in (e) indicates that the current value of the target geometric parameter of the features being etched has reached the endpoint value.
59 Citations
39 Claims
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1. A method of generating a computational model that relates measured optical signals produced by optical energy interacting with features etched on a substrate to values of a target geometric parameter of the features etched on the substrate, the method comprising:
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determining a range of the measured optical signals for use in the computational model, wherein determining the range comprises; identifying a first change in the measured optical signals in the range due to a variation in values of a non-target geometric parameter, identifying a second change in the measured optical signals in the range due to a variation in values of the target geometric parameter, and determining that the second change is greater than the first change; providing a training set having members with values of the optical signals in the range, wherein each member of the training set comprises (i) a value of the target geometric parameter of the features etched in the substrate, and (ii) an associated optical signal produced from etched features having the value of the target geometric parameter of the features etched in the substrate; and producing the computational model from the training set. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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13. A method of determining an etch process endpoint of a target geometric parameter value for one or more features produced on a substrate during an etch process, the method comprising:
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(a) directing incident electromagnetic radiation onto the substrate; (b) measuring optical signals produced by the incident electromagnetic radiation interacting with features being etched on the substrate; (c) providing a subset of the measured optical signals, wherein the subset is defined by a range where optical signals were determined to correlate with values of a target geometric parameter for the features; (d) applying the subset of optical signals to a model configured to predict the target geometric parameter values from the measured optical signals, wherein the model was generated by determining the range where optical signals were determined to correlate with target geometric parameter values for features; (e) determining, from the model, a current value of the target geometric parameter of the features being etched; (f) comparing the current value of the target geometric parameter of the features being etched to an etch process endpoint value for the target geometric parameter; and (g) repeating (b)-(f) until the comparing in (f) in indicates that the current value of the target geometric parameter of the features being etched has reached the etch process endpoint value. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A system for etching one or more features on a substrate during an etch process, the system comprising:
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an etching apparatus for etching semiconductor substrates; and a controller for controlling the operation of the etching apparatus, the controller comprising non-transitory memory storing executable instructions for; (a) directing incident electromagnetic radiation to the substrate; (b) measuring optical signals produced by optical energy interacting with features being etched on the substrate; (c) providing a subset of the measured optical signals, wherein the subset is defined by a range where optical signals were determined to correlate with values of a target geometric parameter for the features; (d) applying the subset of optical signals to a model configured to predict the target geometric parameter values from the measured optical signals, wherein the model was generated by determining the range where optical signals were determined to correlate with target geometric parameter values for features; (e) determining, from the model, a current value of the target geometric parameter of the features being etched; (f) comparing the current value of the target geometric parameter of the features being etched to an etch process endpoint value for the target geometric parameter; and (g) repeating (b)-(f) until the comparing in (f) indicates that the current value of the target geometric parameter of the features being etched has reached the etch process endpoint value. - View Dependent Claims (22, 23, 24, 25, 26, 27, 38, 39)
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Specification