Grating test patterns and methods for overlay metrology
AssigneeTimbre Technologies, Inc.
InventorsXinhui Niu, Nickhil Jakatdar
Life of this patent
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Abstract
Overlay measurements are obtained by forming a first grating test pattern using a first layer mask. A second grating test pattern is formed using a second layer mask. The first and second grating test patterns have the same periodicity. The first and second grating test patterns are measured using an optical metrology equipment. The alignment of the second layer mask to the first layer mask is measured based on the measurement of the first and second grating test patterns.
Claims31
A method of obtaining overlay measurements, the method comprising:
- forming a first grating test pattern using a first layer mask;
- forming a second grating test pattern using a second layer mask,
- wherein the first and second grating test patterns have the same periodicity;
- measuring the first and second grating test patterns using an optical metrology equipment;
- and
- measuring the alignment of the second layer mask to the first layer mask based on the measurement of the first and second grating test patterns.
A method of obtaining overlay measurements, the method comprising:
- forming a first grating test pattern using a first layer mask;
- forming a second grating test pattern using a second layer mask,
- wherein the first and second grating test patterns have the same periodicity, and wherein the first and second grating test patterns have:
- a first grating having grating lines in a first orientation, and
- a second grating having grating lines in a second orientation perpendicular to the first orientation;
- measuring the first and second grating patterns including the first and second gratings using an optical metrology equipment;
- and
- measuring the alignment of the second layer mask to the first layer mask in the first and second orientations based on the measurement of the first and second grating patterns including the first and second gratings.
A structure formed on a semiconductor wafer for obtaining overlay measurements, the structure comprising:
- a first grating test pattern formed on the semiconductor wafer using a first layer mask;
- and
- a second grating test pattern formed on the semiconductor wafer using a second layer mask,
- wherein the first and second grating test patterns have the same periodicity,
- wherein the first and second grating test patterns are measured using an optical metrology equipment, and
- wherein the alignment of the second layer mask to the first layer mask is measured based on the measurement of the first and second grating test patterns.
Dependencies are inferred from the claim text.