Measurement of overlay offset in semiconductor processing
First Claim
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1. A method of semiconductor manufacturing, comprising:
- forming an overlay offset measurement target including a first feature and a third feature located on a first layer and a second feature and a fourth feature located on a second layer, wherein the first feature and the second feature have a first predetermined overlay offset and the third feature and the fourth feature have a second predetermined overlay offset, different than the first predetermined overlay offset;
irradiating the target with a radiation beam having a single wavelength;
determining a first reflectivity measurement associated with the first and second feature at the single wavelength;
determining a second reflectivity measurement associated with the third and fourth feature at the single wavelength;
generating a reflectivity profile which has a first axis including reflectivity at the single wavelength and a second axis including predetermined overlay offset, wherein the generating the reflectivity profile includes;
plotting the first reflectivity measurement;
generating a first line fitted to the plotted first reflectivity measurement;
plotting the second reflectivity measurement; and
generating a second line fitted to the plotted second reflectivity measurement; and
calculating an overlay offset for the first layer and the second layer by determining a value on the second axis where the first line and the second line intersect, wherein the value provides a predetermined overlay offset that corresponds to an actual overlay offset of zero.
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Abstract
A method of semiconductor manufacturing including forming an overlay offset measurement target including a first feature on a first layer and a second feature on a second layer. The first feature and the second feature have a first predetermined overlay offset. The target is irradiated. The reflectivity of the irradiated target is determined. An overlay offset for the first layer and the second layer is calculated using the determined reflectivity.
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Citations
9 Claims
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1. A method of semiconductor manufacturing, comprising:
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forming an overlay offset measurement target including a first feature and a third feature located on a first layer and a second feature and a fourth feature located on a second layer, wherein the first feature and the second feature have a first predetermined overlay offset and the third feature and the fourth feature have a second predetermined overlay offset, different than the first predetermined overlay offset; irradiating the target with a radiation beam having a single wavelength; determining a first reflectivity measurement associated with the first and second feature at the single wavelength; determining a second reflectivity measurement associated with the third and fourth feature at the single wavelength; generating a reflectivity profile which has a first axis including reflectivity at the single wavelength and a second axis including predetermined overlay offset, wherein the generating the reflectivity profile includes; plotting the first reflectivity measurement; generating a first line fitted to the plotted first reflectivity measurement; plotting the second reflectivity measurement; and generating a second line fitted to the plotted second reflectivity measurement; and calculating an overlay offset for the first layer and the second layer by determining a value on the second axis where the first line and the second line intersect, wherein the value provides a predetermined overlay offset that corresponds to an actual overlay offset of zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification