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US 7,352,453 B2Granted
Method for process optimization and control by comparison between 2 or more measured scatterometry signals
AssigneeKLA-Tencor Technologies Corporation
InventorsWalter D. Mieher, Chris A. Mack, Matt Hankinson
Life of this patent
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Abstract
A method for determining one or more process parameter settings of a photolithographic system is disclosed.
Claims33
A method, comprising:
- obtaining scatterometry signals by performing scatterometry measurements on a plurality of grating structures with different process responses, each grating structure having a first grating parameter and the grating structures having different values for the first grating parameter;
- comparing scatterometry signals from said different grating structures in order to ascertain information about one or more process parameters used to form said grating structures;
- and
- controlling said one or more process parameters based on said comparison, wherein the differences between process responses are attributable at least in part to the differences between the different values for the first grating parameters and wherein the different values for the first grating parameters are selected so as to cause different process responses under the same process parameters.
1 more element
A method for controlling one or more process parameters, comprising:
- obtaining scatterometry signals for a first grating structure with a first process response and a second grating structure with a second process response different from the first process response, each of the grating structures being configured with different sensitivities to one or more process parameters which are desired to be controlled;
- comparing scatterometry signals of the first and second grating structures, each of the first and second grating structures producing different scatterometry signals for a given set of process parameters;
- and
- extracting information about one or more process parameters of the given set of process parameters based on said comparison, wherein the first grating structure and the second grating structure each has a first grating parameter and wherein a first value of the first grating structure's first grating parameter differs from a second value of the second grating structure's first grating parameter and wherein the difference between the first process response and the second process response is attributable at least in part to the difference between the first value and the second value.
1 more element
A method of determining optimal or best focus, the method comprising:
- forming a target group at a plurality of focus settings, the target group containing a plurality of targets with different sensitivities to focus, each target having a first parameter and the plurality of targets having different values for the first parameter, wherein the differences in sensitivities are attributable at least in part to the differences between the different values and wherein the different values are selected so as to cause different process responses under the same process parameters;
- obtaining scatterometry signals for each of the targets in the target groups;
- calculating difference signals for each target group;
- forming a relationship between the difference signal or a property of the difference signal to the focus settings;
- and
- extracting optimal or best focus using the relationship.
3 more elements
A process control method, comprising:
- measuring two or more measurable patterns that are configured with different process responses so as to produce different scatterometry signals for a given set of process conditions, each pattern having a first parameter and the measurable patterns having different values for the first parameter;
- and
- extracting information about one or more process parameters associated with a photolithographic process by analyzing the differences between the different scatterometry signals from the measurable patterns for a given set of process conditions, wherein the differences between the process responses are attributable at least in part to the differences between the different values and wherein the different values are selected so as to cause different process responses under the same process conditions.
A target group, comprising:
- a plurality of scatterometry targets configured to have different process responses, each target having a first parameter, the plurality of scatterometry targets having different values for the first parameter, the scatterometry targets with different process responses producing different scatterometry signals, the differences in the scatterometry signals being attributable at least in part to one or more process parameters used to create the scatterometry targets, wherein the differences between the process responses is attributable at least in part to the differences between the different values and wherein the different values are selected so as to cause different process responses under the same process conditions.
Dependencies are inferred from the claim text.