Exposure Alignment Parameter Optimization via Statistical Error Estimation
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Solution Overview
Problem
Conventional alignment parameter optimization methods for exposure systems are inefficient, requiring extensive time and cost to measure overlay errors for numerous combinations, which hinders the production of high-precision microdevices with high throughput.
Innovation Solution
A method that determines optimal alignment parameters by performing position measurements under predetermined parameters, calculating reference and comparative computation results, and estimating processing errors, allowing for the selection of alignment parameters that reduce processing errors without exhaustive measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment parameter optimization methods are used to measure overlay errors for numerous combinations, then manufacturing precision is improved, but productivity deteriorates due to extensive time and cost requirements
Solution Approach 1:
The patent applies preliminary action by pre-calculating expected overlay errors for multiple alignment parameter combinations using simulation data and statistical models before actual exposure. This allows the system to predict which parameter combinations will yield acceptable overlay errors without performing exhaustive physical measurements, thereby reducing measurement time while maintaining precision.
Solution Approach 2:
The patent uses copying by creating virtual models and simulation data that replicate the behavior of the exposure system. Instead of measuring actual overlay errors for every parameter combination, the system uses simulated copies to predict performance, significantly reducing the number of physical measurements needed while maintaining accuracy in optimization.
2Manufacturing precision
If exhaustive measurement of overlay errors for numerous alignment parameter combinations is performed, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The system performs preliminary calculations using pre-collected simulation data and statistical models to predict overlay errors for different alignment parameter combinations. This preliminary action eliminates the need for time-consuming exhaustive measurements, as the system can quickly evaluate multiple parameter sets using pre-computed data and statistical inference.
Solution Approach 2:
The patent applies partial action by measuring overlay errors for only a selected subset of alignment parameter combinations rather than all possible combinations. The system uses statistical sampling and prediction methods to evaluate representative samples, achieving sufficient optimization without the time cost of exhaustive measurement of every possible parameter combination.
3Productivity
If statistical processing is used to determine alignment parameters, then productivity is improved by reducing measurement requirements, but manufacturing precision may deteriorate
Solution Approach 1:
The system incorporates feedback by using actual overlay error measurements from a subset of parameter combinations to validate and refine the statistical models. The measured data feeds back into the simulation and statistical analysis, allowing the system to continuously improve the accuracy of its predictions while maintaining high productivity through reduced measurement requirements.
Solution Approach 2:
The patent applies parameter changes by systematically varying alignment parameters within defined ranges and evaluating their effects using statistical analysis. The system changes parameters such as stage position, focus, and exposure conditions while using statistical models to predict outcomes, enabling efficient optimization that maintains precision through controlled parameter exploration rather than exhaustive measurement.
Data Source
AI summary
Alignment parameters determination method with less overlay error after exposure without tremendous expending time and cost is provided. Provision is made of a fetching unit performing position measurement and statistical processing to obtain reference computation results. Another fetching unit obtains reference processing results by positioning and exposing shots at a predetermined exposure apparatus based on the reference computation results, then measuring overlay error for the shots. Another fetching unit changes at least parts of the predetermined alignment parameters and performs position measurement and statistical processing to obtain comparative computation results. A controller 650 calculates estimated overlay error when assuming positioning and exposure of shots at a predetermined exposure apparatus based on the comparative computation results using the reference computation results, comparative computation results, and reference processing results.