Apparatus and methods for detecting overlay errors using scatterometry
First Claim
1. A method of determining an overlay error between two layers of a multiple layer sample, the method comprising:
- for each of a plurality of periodic targets target that each have a first structure formed from a first layer and a second structure formed from a second layer of the sample, measuring a plurality of optical signals at a plurality of incident angles, wherein there are predefined offsets between the first and second structures; and
determining an overlay error between the first and second structures by analyzing the measured optical signals at the plurality of incident angles from the periodic targets using a scatterometry overlay technique based on the predefined offsets without using a calibration operation.
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Abstract
Disclosed is a method of determining an overlay error between two layers of a multiple layer sample. For each of a plurality of periodic targets target that each have a first structure formed from a first layer and a second structure formed from a second layer of the sample, a plurality of optical signals are measured at a plurality of incident angles, wherein there are predefined offsets between the first and second structures. An overlay error is then determined between the first and second structures by analyzing the measured optical signals at the plurality of incident angles from the periodic targets using a scatterometry overlay technique based on the predefined offsets without using a calibration operation.
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Citations
14 Claims
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1. A method of determining an overlay error between two layers of a multiple layer sample, the method comprising:
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for each of a plurality of periodic targets target that each have a first structure formed from a first layer and a second structure formed from a second layer of the sample, measuring a plurality of optical signals at a plurality of incident angles, wherein there are predefined offsets between the first and second structures; and
determining an overlay error between the first and second structures by analyzing the measured optical signals at the plurality of incident angles from the periodic targets using a scatterometry overlay technique based on the predefined offsets without using a calibration operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification