Method of controlling photolithography processes based upon scatterometric measurements of photoresist thickness, and system for accomplishing same
First Claim
1. A method of determining a thickness of a layer of photoresist, comprising:
- providing a library of optical characteristic traces, each of which corresponds to a grating structure comprised of a plurality photoresist features having a known thickness;
forming at least one grating structure in a layer of photoresist, said formed grating structure being comprised of a plurality of photoresist features having an unknown thickness;
illuminating said formed grating structure;
measuring light reflected off of said formed grating structure to generate an optical characteristic trace for said formed grating structure; and
determining said unknown thickness of said photoresist features by comparing said generated optical characteristic trace to at least one optical characteristic trace from said library.
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Abstract
The present invention is generally directed to a method of controlling photolithography processes based upon scatterometric measurements of photoresist thickness, and system for accomplishing same. In one embodiment, the method comprises providing a library of optical characteristic traces, each of which corresponds to a grating structure comprised of a plurality of photoresist features having a known thickness, forming at least one grating structure in a layer of photoresist, the formed grating structure being comprised of a plurality of photoresist features having an unknown thickness, and illuminating the formed grating structure. The method further comprises measuring light reflected off of the formed grating structure to generate an optical characteristic trace for the formed grating structure, and determining the unknown thickness of the photoresist features by comparing the generated optical characteristic trace to at least one optical characteristic trace from the library.
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Citations
74 Claims
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1. A method of determining a thickness of a layer of photoresist, comprising:
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providing a library of optical characteristic traces, each of which corresponds to a grating structure comprised of a plurality photoresist features having a known thickness;
forming at least one grating structure in a layer of photoresist, said formed grating structure being comprised of a plurality of photoresist features having an unknown thickness;
illuminating said formed grating structure;
measuring light reflected off of said formed grating structure to generate an optical characteristic trace for said formed grating structure; and
determining said unknown thickness of said photoresist features by comparing said generated optical characteristic trace to at least one optical characteristic trace from said library. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method, comprising:
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providing a library of optical characteristic traces, each of which corresponds to a grating structure comprised of a plurality of photoresist features having a known thickness;
forming at least one grating structure in a layer of photoresist in each of a plurality of exposure fields of a stepper exposure process, said formed grating structure being comprised of a plurality of photoresist features having an unknown thickness;
illuminating said formed grating structure;
measuring light reflected off of said formed grating structure to generate an optical characteristic trace for said formed grating structure;
determining said unknown thickness of said photoresist features by comparing said generated optical characteristic trace to at least one optical characteristic trace from said library; and
modifying at least one parameter of a process used to form a layer of photoresist on at least one subsequently processed wafer based upon said comparison of said generated optical characteristic trace and said at least one optical characteristic trace from said library. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method, comprising:
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providing a library of optical characteristic traces, each of which corresponds to a grating structure comprised of a plurality of photoresist features having a known thickness;
forming at least one grating structures in a layer of photoresist in each of at least five exposure fields of a stepper exposure process, each of said formed grating structures being comprised of a plurality of photoresist features having an unknown thickness;
illuminating said formed grating structures;
measuring light reflected off of each of said plurality of formed grating structures to generate an optical characteristic trace for each of said plurality of formed grating structures;
determining said unknown thickness of said photoresist features by comparing each of said generated optical characteristic traces to at least one optical characteristic trace from said library; and
modifying at least one parameter of a process used to form a layer of photoresist on at least one subsequently processed wafer based upon said comparison of said generated optical characteristic traces and said at least one optical characteristic trace from said library. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A method, comprising:
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providing a wafer having at least one process layer and a layer of photoresist formed thereabove;
forming at least one grating structure in said layer of photoresist;
illuminating said formed grating structures;
measuring light reflected off of said formed grating structure to generate an optical characteristic trace for said formed grating structure;
comparing the generated optical characteristic trace for said formed grating structure to a target optical characteristic trace; and
determining, based upon a comparison of said generated optical characteristic trace and said target optical characteristic trace, at least one parameter of a process to be performed to form a layer of photoresist on a subsequently processed wafer. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A method, comprising:
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providing a wafer having at least one process layer and a layer of photoresist formed thereabove;
forming at least one grating structure in said layer of photoresist in each of a plurality of exposure fields of a stepper exposure process;
illuminating said formed grating structure;
measuring light reflected off of said formed grating structure to generate an optical characteristic trace for said formed grating structure;
comparing the generated optical characteristic trace for said formed grating structure to a target optical characteristic trace; and
determining, based upon a comparison of said generated optical characteristic trace and said target optical characteristic trace, at least one parameter of a process to be performed to form a layer of photoresist on a subsequently processed wafer. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65)
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66. A method, comprising:
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providing a wafer having at least one process layer and a layer of photoresist formed thereabove;
forming at least one grating structure in said layer of photoresist in each of at least five exposure fields of a stepper exposure process;
illuminating said formed grating structure;
measuring light reflected off of said formed grating structure to generate an optical characteristic trace for said formed grating structure;
comparing the generated optical characteristic trace for said formed grating structure to a target optical characteristic trace; and
modifying, based upon a comparison of said generated optical characteristic trace and said target optical characteristic trace, at least one parameter of a process to be performed to form a layer of photoresist on a subsequently processed wafer. - View Dependent Claims (67, 68, 69, 70, 71, 72, 73, 74)
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Specification