Scanning Exposure Control Profile Extension and Deconvolution
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Solution Overview
Problem
Current lithographic processes face challenges in achieving precise control and reducing Moving Average (MA) and Moving Standard Deviation (MSD) errors during the exposure of patterns on substrates, leading to overlay and imaging issues due to limitations in process control methods and the finite size of the slit and light intensity profile.
Innovation Solution
The method involves extending the exposure correction profile beyond the regular field dimension and applying a deconvolution scheme, such as a Wiener filter, to optimize the control profile and improve exposure quality by accounting for the dimension of the illumination profile in the scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the control profile is limited to the regular field dimension, then the device complexity is reduced, but the manufacturing precision deteriorates due to intra-die variation and convolution errors
Solution Approach 1:
The control profile is extended beyond the exposure field boundaries in advance, allowing the illumination profile to be properly accounted for at the edges. This preliminary extension prevents convolution errors and intra-die variation by ensuring the control profile covers the complete illumination area, including regions that would otherwise cause edge effects and degradation in exposure quality.
Solution Approach 2:
The control profile is extended in the scanning direction beyond the traditional field boundaries. This dimensional extension allows the system to account for the finite size of the illumination profile and eliminates edge effects that occur when the control profile is truncated at the field boundaries, thereby improving exposure quality without requiring complex additional hardware.
2Measurement precision
If a deconvolution scheme is not applied, then the device complexity is reduced, but the measurement precision deteriorates due to convolution errors from the finite slit size
Solution Approach 1:
A deconvolution scheme is applied to the control profile to compensate for the convolution effect caused by the finite illumination profile. This feedback mechanism processes the control data to reverse the blurring effect, thereby improving measurement precision and correction quality while accounting for the system's inherent limitations.
Solution Approach 2:
The control profile undergoes parameter transformation through deconvolution, changing from a convolved state (blurred by the illumination profile) to a deconvolved state (restored to higher precision). This parameter change enables more accurate control and measurement by reversing the mathematical convolution effect introduced by the finite slit size.
3Manufacturing precision
If the control profile is extended beyond the exposure field, then the manufacturing precision is improved, but the loss of time increases due to extended processing area
Solution Approach 1:
The control profile is extended only to the necessary degree beyond the exposure field boundaries, rather than covering the entire substrate. This partial extension provides sufficient margin to account for the illumination profile and eliminate edge effects, improving exposure uniformity without requiring excessive processing time for the entire substrate area.
Data Source
AI summary
A method for controlling a scanning exposure apparatus configured for scanning an illumination profile over a substrate to form functional areas thereon. The method includes determining a control profile for dynamic control of the illumination profile during exposure of an exposure field including the functional areas, in a scanning exposure operation; and optimizing a quality of exposure of one or more individual functional areas. The optimizing may include a) extending the control profile beyond the extent of the exposure field in the scanning direction; and/or b) applying a deconvolution scheme to the control profile, wherein the structure of the deconvolution scheme is based on a dimension of the illumination profile in the scanning direction.