Lithographic Lens Control via Cost Function Optimization
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Solution Overview
Problem
Lithographic apparatuses face challenges in accurately reproducing small features due to limitations in wavelength and numerical aperture, leading to difficulties in achieving desired pattern dimensions and electrical functionality, especially at low k1 values, where current methods like optimization of NA and resolution enhancement techniques are insufficient to correct for residual errors across multiple fields.
Innovation Solution
A method and apparatus for determining control data for a lithographic apparatus, involving the use of a cost function that evaluates parameter data across multiple fields to minimize performance residuals, incorporating actuator control settings and routing orders, and optimizing lens model inputs to apply corrections based on parameter data and lens model dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If low k1 lithography is used to process features smaller than the classical resolution limit, then smaller feature sizes can be achieved, but pattern reproduction accuracy deteriorates
Solution Approach 1:
The patent changes the parameter k1 to enable processing of smaller features below the classical resolution limit. By operating at low k1 values, the system achieves smaller critical dimensions while managing the associated deterioration in pattern reproduction accuracy through additional correction mechanisms.
Solution Approach 2:
The patent implements a feedback mechanism where metrology measurements of previously exposed substrates are used to determine corrections for subsequent exposures. This closed-loop approach continuously refines the patterning process to compensate for accuracy deterioration at low k1 values.
2Manufacturing precision
If sophisticated fine-tuning steps and resolution enhancement techniques are applied, then pattern reproduction accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs multiple resolution enhancement techniques (RET) including optical proximity correction, phase shifting, and illumination optimization within a unified lithographic system. These multi-functional approaches improve pattern reproduction accuracy while managing overall device complexity through integration.
Solution Approach 2:
The patent applies corrections to the design layout and lithographic parameters before the actual exposure process. By performing optimization and correction steps in advance, the system improves pattern reproduction accuracy without adding complexity to the core exposure mechanism.
3Manufacturing precision
If tight control loops are used to control apparatus stability, then pattern reproduction accuracy is improved, but response time increases
Solution Approach 1:
The patent implements tight control loops that continuously monitor substrate exposure quality through metrology measurements and adjust lithographic parameters accordingly. This feedback mechanism maintains high pattern reproduction accuracy by compensating for apparatus instability while managing response time through efficient measurement and correction cycles.
4Manufacturing precision
If metrology measurements are performed to identify errors and determine corrections, then pattern reproduction accuracy is improved, but measurement and processing time increases
Solution Approach 1:
The patent performs metrology measurements on previously exposed substrates to identify errors and determine corrections before subsequent exposures. By conducting these measurements and calculations in advance, the system improves pattern reproduction accuracy for future fields while minimizing the time impact on the overall production process.
Data Source
AI summary
A method for determining an input to a lens model to determine a setpoint for manipulation of a lens of a lithographic apparatus when addressing at least one of a plurality of fields of a substrate, the method including: receiving parameter data for the at least one field, the parameter data relating to one or more parameters of the substrate within the at least one field, the one or more parameters being at least partially sensitive to manipulation of the lens as part of an exposure performed by the lithographic apparatus; receiving lens model data relating to the lens; and determining the input based on the parameter data and on the lens model data.