Metrology Feed Forward for Semiconductor Process Drift
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Solution Overview
Problem
Semiconductor metrology systems face challenges in maintaining accuracy and precision due to constantly changing wafer characteristics and process variations, leading to potential excursions in metrology performance that can disrupt manufacturing processes.
Innovation Solution
A metrology performance analysis system that utilizes detectors and processors to receive and analyze metrology data, determine deviations from nominal values, and identify root causes of these deviations by establishing relationships with semiconductor process variations, allowing for feed-forward data to mitigate these issues and prevent excursions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor process tools operate continuously to maintain productivity, then manufacturing output increases, but process drift occurs causing metrology performance degradation
Solution Approach 1:
The system performs preliminary actions by continuously monitoring process parameters and predicting potential drifts before they cause metrology excursions. The feed-forward mechanism proactively adjusts process parameters to prevent performance degradation, rather than reacting after problems occur.
Solution Approach 2:
The system implements feedback by using metrology measurements to detect process variations and feed this information back to adjust process parameters. This closed-loop control maintains metrology performance by continuously correcting drift caused by continuous operation.
2Measurement precision
If process parameters are adjusted frequently to maintain metrology accuracy, then measurement precision is improved, but system complexity increases
Solution Approach 1:
The system changes process parameters based on predicted process drift and metrology performance requirements. By dynamically adjusting parameters like focus, dose, or process conditions, the system maintains measurement precision without requiring complex hardware modifications.
3Manufacturing precision
If metrology measurements are performed frequently to detect process variations, then process control accuracy is improved, but manufacturing throughput decreases
Solution Approach 1:
The system performs preliminary metrology measurements and process characterization to establish predictive models before full production. This allows the feed-forward control to anticipate and correct issues without requiring frequent interruptive measurements during manufacturing.
Solution Approach 2:
The system skips detailed metrology measurements for routine wafers by using predictive models based on process data, reserving comprehensive measurements for exceptional cases. This reduces measurement overhead while maintaining process control accuracy through intelligent sampling.
Data Source
AI summary
A metrology performance analysis system includes a metrology tool including one or more detectors and a controller communicatively coupled to the one or more detectors. The controller is configured to receive one or more metrology data sets associated with a metrology target from the metrology tool in which the one or more metrology data sets include one or more measured metrology metrics and the one or more measured metrology metrics indicate deviations from nominal values. The controller is further configured to determine relationships between the deviations from the nominal values and one or more selected semiconductor process variations, and determine one or more root causes of the deviations from the nominal values based on the relationships between values of the one or more metrology metrics and the one or more selected semiconductor process variations.