Localized telecentricity and focus optimization for overlay metrology
First Claim
1. An overlay metrology system comprising:
- a controller communicatively coupled to a telecentric imaging system including one or more cameras configured to capture images through an objective lens at two or more focal positions, the controller including one or more processors configured to execute program instructions causing the one or more processors to;
receive two or more alignment images of an overlay target on a sample captured at two or more focal positions by the imaging system, the two or more alignment images including one or more features of the overlay target;
generate alignment data indicative of an alignment of the overlay target within the imaging system based on the two or more alignment images;
set the two or more alignment images as measurement images when the alignment of the overlay target is within selected alignment tolerances;
direct the imaging system to adjust the alignment of the overlay target in the imaging system and further receive one or more measurement images from the imaging system when the alignment of the overlay target is outside the selected alignment tolerances; and
determine overlay between two or more layers of the sample based on at least one of the measurement images.
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Abstract
An overlay metrology tool providing site-by-site alignment includes a controller coupled to a telecentric imaging system. The controller may receive two or more alignment images of an overlay target on a sample captured at two or more focal positions by the imaging system, generate alignment data indicative of an alignment of the overlay target within the imaging system based on the alignment images, set the alignment images as measurement images when the alignment of the overlay target is within selected alignment tolerances, direct the imaging system to adjust the alignment of the overlay target in the imaging system and further receive one or more measurement images from the imaging system when the alignment of the overlay target is outside the selected alignment tolerances, and determine overlay between two or more layers of the sample based on at least one of the measurement images.
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Citations
44 Claims
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1. An overlay metrology system comprising:
a controller communicatively coupled to a telecentric imaging system including one or more cameras configured to capture images through an objective lens at two or more focal positions, the controller including one or more processors configured to execute program instructions causing the one or more processors to; receive two or more alignment images of an overlay target on a sample captured at two or more focal positions by the imaging system, the two or more alignment images including one or more features of the overlay target; generate alignment data indicative of an alignment of the overlay target within the imaging system based on the two or more alignment images; set the two or more alignment images as measurement images when the alignment of the overlay target is within selected alignment tolerances; direct the imaging system to adjust the alignment of the overlay target in the imaging system and further receive one or more measurement images from the imaging system when the alignment of the overlay target is outside the selected alignment tolerances; and determine overlay between two or more layers of the sample based on at least one of the measurement images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. An overlay metrology system comprising:
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a telecentric imaging system including one or more cameras configured to capture images through an objective lens at two or more focal positions; and a controller communicatively coupled to the imaging system, the controller including one or more processors configured to execute program instructions causing the one or more processors to; receive two or more alignment images of an overlay target on a sample captured at two or more focal positions by the imaging system, the two or more alignment images including one or more features of the overlay target; generate alignment data indicative of an alignment of the overlay target within the imaging system based on the two or more alignment images; set the two or more alignment images as measurement images when the alignment of the overlay target is within selected alignment tolerances; direct the imaging system to adjust the alignment of the overlay target in the imaging system and further receive one or more measurement images from the imaging system when the alignment of the overlay target is outside the selected alignment tolerances; and determine overlay between two or more layers of the sample based on at least one of the measurement images.
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44. An overlay metrology method comprising:
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receiving two or more alignment images of a sample captured at two or more focal positions by a telecentric imaging system, the two or more alignment images including one or more features of an overlay target; generating, with one or more processors, alignment data indicative of an alignment of the overlay target within the imaging system based on the two or more alignment images; setting the two or more alignment images as measurement images when the alignment of the overlay target is within selected alignment tolerances; directing the imaging system to adjust the alignment of the overlay target in the imaging system and further receive one or more measurement images from the imaging system when the alignment of the overlay target is outside the selected alignment tolerances; and determining, with one or more processors, overlay between two or more layers of the sample based on the measurement image.
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Specification