Scatterometric Spectra Weighting for Wafer Process Control
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Solution Overview
Problem
Advanced semiconductor manufacturing requires precise process control, which is limited by the quality of measurements used in Advanced Process Control (APC) algorithms, necessitating improved methods for determining process control parameters.
Innovation Solution
A method and system that determine a quality metric by comparing production scatterometric spectra with reference spectra linked by machine learning, weighting contributions from multiple wafers to calculate process control parameter values for controlling semiconductor wafer processing steps, utilizing a quality metric generator and process controller to enhance APC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If measurement quality is improved to enhance process control accuracy, then manufacturing precision is improved, but measurement time and system complexity increase
Solution Approach 1:
The patent segments the process control parameter determination into multiple weighted contributions from different wafers (production wafer, different wafers in same lot, different lots, different products) rather than relying on a single measurement source. This segmentation allows the system to distribute measurement complexity across multiple simpler measurements while achieving improved overall accuracy through the quality metric-weighted combination.
2Manufacturing precision
If multiple wafer measurements are combined to improve process control, then manufacturing precision is improved, but the complexity of determining process control parameters increases
Solution Approach 1:
The patent introduces a quality metric parameter that quantifies measurement quality and uses it as a weighting factor in the process control parameter determination. By changing the parameter from simple measurement averaging to quality-weighted combination, the system achieves improved accuracy while managing complexity through a systematic weighting approach based on the quality metric.
Solution Approach 2:
The patent implements feedback by using the quality metric (derived from comparing scatterometric spectra) to adjust the weighting of different wafer measurements. This feedback mechanism allows the system to automatically adapt the contribution of each measurement based on its quality, improving accuracy while keeping the determination process systematic rather than requiring complex manual optimization.
3Productivity
If real-time process control is implemented, then productivity is improved, but measurement precision requirements increase
Solution Approach 1:
The patent applies dynamics by making the weighting factors adaptive rather than fixed. The quality metric dynamically determines the weight of each wafer's contribution to the process control parameter, allowing the system to maintain real-time control capability while adjusting to varying measurement qualities in practice, thus bridging the gap between throughput requirements and precision needs.
Data Source
AI summary
A process control method for manufacturing semiconductor devices, including determining a quality metric of a production semiconductor wafer by comparing production scatterometric spectra of a production structure of the production wafer with reference scatterometric spectra of a reference structure of reference semiconductor wafers, the production structure corresponding to the reference structure, the reference spectra linked by machine learning to a reference measurement value of the reference structure, determining a process control parameter value (PCPV) of a wafer processing step, the PCPV determined based on measurement of the production wafer and whose contribution to the PCPV is weighted with a first predefined weight based on the quality metric, and based on a measurement of a different wafer and whose contribution to the PCPV is weighted with a second predefined weight based on the quality metric, and controlling, with the PCPV, the processing step during fabrication.