System and method for generating and analyzing roughness measurements and their use for process monitoring and control
In one embodiment, a method includes receiving measured linescan information describing a pattern structure of a feature, applying the received measured linescan information to an inverse linescan model that relates measured linescan information to feature geometry information, and identifying, based at least in part on the applying the received measured linescan model to the inverse linescan model, feature geometry information that describes a feature that would produce a linescan corresponding to the received measured linescan information. The method also includes determining, at least in part using the inverse linescan model, feature edge positions of the identified feature, analyzing the feature edge positions to determine errors in the manufacture of the pattern structure, and controlling a lithography tool based on the analysis of the feature edge positions.
1 . A method, comprising:
receiving measured linescan information describing a pattern structure comprised of at least two features, wherein the measured linescan information is generated from a scanning electron microscope (SEM) image of the pattern structure that includes image noise;
applying the received measured linescan information to an inverse linescan model that relates measured linescan information to feature geometry information;
calibrating the inverse linescan model using an averaged linescan obtained by averaging pixels along an axis of symmetry of a feature to determine parameters that are constant for the image;
analyzing one or more feature edge positions to determine one or more pattern placement errors in the manufacture of the pattern structure, wherein the one or more feature edge positions are determined using the inverse linescan model based on one or more identified features in feature geometry information, wherein the analyzing includes determining the one or more feature edge positions by numerically fitting the inverse linescan model to each measured linescan without filtering the SEM image, and wherein the one or more pattern placement errors describe a position of a feature in the pattern structure relative to one or more other features in the pattern structure; and
based on the determined one or more pattern placement errors, controlling a lithography tool used to fabricate the pattern structure.
2 . The method of claim 1 , wherein the one or more pattern placement errors describe the position of a feature in the pattern structure relative to one or more other features in the pattern structure.
3 . The method of claim 1 , wherein two or more of the features in the pattern structure were fabricated from multiple patterning steps.
4 . The method of claim 1 , wherein the pattern structure was fabricated in multiple steps of lithography followed by etch.
5 . The method of claim 1 , wherein the pattern structure was fabricated by self-aligned multiple patterning.
6 . The method of any of the claims above claim 1 , wherein the one or more pattern placement errors describe an overlay error of one patterning step relative to another patterning step.
7 . The method of claim 1 , wherein a measurement of pattern placement error is used to control a lithography tool.
8 . The method of claim 7 , wherein the lithography tool is controlled to reduce one or more overlay errors.
9 . The method of claim 1 , wherein a measurement of the one or more pattern placement errors or overlay for long patterns is used to predict or control the one or more pattern placement errors or overlay of shorter patterns.
10 . An edge detection system, comprising:
an imaging device configured to generate a first image of a pattern structure, wherein the first image of the pattern structure includes image noise; and
a processor, coupled to the imaging device, the processor configured to:
generate, based at least in part on the first image of the pattern structure, measured linescan information describing a pattern structure of a feature, wherein the measured linescan information is generated from a scanning electron microscope (SEM) image of the pattern structure that includes image noise;
apply the measured linescan information to an inverse linescan model that relates measured linescan information to feature geometry information;
calibrating the inverse linescan model using an averaged linescan obtained by averaging pixels along an axis of symmetry of a feature to determine parameters that are constant for the image;
analyze one or more feature edge positions to determine one or more pattern placement errors in the manufacture of the pattern structure, wherein the one or more feature edge positions are determined using the inverse linescan model based on one or more identified features in feature geometry information, wherein, to analyze the one or more feature edge positions, the processor is configured to determine the one or more feature edge positions by numerically fitting the inverse linescan model to each measured linescan without filtering the SEM image, and wherein the one or more pattern placement errors describe a position of a feature in the pattern structure relative to one or more other features in the pattern structure; and
control a lithography tool, based on the determined one or more pattern placement errors, used to fabricate the pattern structure.
11 . The edge detection system of claim 10 , wherein the one or more pattern placement errors describe the position of a feature in the pattern structure relative to one or more other features in the pattern structure.
12 . The edge detection system of claim 10 , wherein two or more of the features in the pattern structure were fabricated from multiple patterning steps.
13 . The edge detection system of claim 10 , wherein the pattern structure was fabricated in multiple steps of lithography followed by etch.
14 . The edge detection system of claim 10 , wherein the pattern structure was fabricated by self-aligned multiple patterning.
15 . The edge detection system of claim 10 , wherein the one or more pattern placement errors describes an overlay error of one patterning step relative to another patterning step.
16 . The edge detection system of claim 10 , wherein the measurement of pattern placement error is used to control a lithography tool.
17 . The edge detection system of claim 10 , wherein the lithography tool is controlled to reduce one or more overlay errors.
18 . The edge detection system of claim 10 , wherein a measurement of pattern placement error or overlay for long patterns is used to predict or control the pattern placement error or overlay of shorter patterns.
19 . A tangible, non-transitory computer-readable medium storing instructions that, when executed, cause a processing device to:
obtain a first image of a pattern structure, wherein the first image of the pattern structure includes image noise;
generate, based at least in part on the first image of the pattern structure, measured linescan information describing a pattern structure of a feature, wherein the measured linescan information is generated from a scanning electron microscope (SEM) image of the pattern structure that includes image noise;
apply the measured linescan information to an inverse linescan model that relates measured linescan information to feature geometry information;
calibrating the inverse linescan model using an averaged linescan obtained by averaging pixels along an axis of symmetry of a feature to determine parameters that are constant for the image;
analyze one or more feature edge positions to determine one or more pattern placement errors in the manufacture of the pattern structure, wherein the one or more feature edge positions are determined using the inverse linescan model based on one or more identified features in feature geometry information wherein to analyze the one or more feature edge positions, the processor is configured to execute instruction to determine the one or more feature edge positions by numerically fitting the inverse linescan model to each measured linescan without filtering the SEM image, and wherein the one or more pattern placement errors describe a position of a feature in the pattern structure relative to one or more other features in the pattern structure; and
based on the determined one or more pattern placement errors, control a lithography tool used to fabricate the pattern structure.
20 . The computer-readable medium of claim 19 , wherein the one or more pattern placement errors describe a position of a feature in the pattern structure relative to one or more other features in the pattern structure.