Zonal Metrology Recipe Optimization for Wafer Sensitivity
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Solution Overview
Problem
Current metrology recipe optimization methods lack accuracy and applicability as they do not consider the varying sensitivity of different wafer zones to the lithographic process, leading to suboptimal measurement results.
Innovation Solution
Implementing zonal analysis during recipe setup and measurement procedures to account for spatially variable values of setup parameters across various zones on the wafer, allowing for more precise weighting and optimization of parameters and metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional uniform recipe optimization is used across the entire wafer, then the process is simple and easy to implement, but the measurement precision is reduced due to ignoring spatially varying sensitivity of different wafer zones
Solution Approach 1:
The wafer is divided into multiple zones (e.g., center, mid-ring, outer-ring zones) with different sensitivities to lithographic process variations. Each zone is assigned its own optimized recipe parameters and weighting factors, allowing measurement optimization to account for spatially varying sensitivity across the wafer surface without requiring complete redesign of the measurement system.
Solution Approach 2:
Different recipe parameters, weighting factors, and optimization criteria are applied to different wafer zones based on their specific sensitivity characteristics. For example, zones with higher sensitivity to overlay errors receive different weighting than zones with lower sensitivity, ensuring that each region is measured with parameters optimized for its local characteristics rather than using a uniform approach across the entire wafer.
2Manufacturing precision
If zonal analysis with spatially variable parameters is implemented, then the measurement precision and applicability are improved, but the recipe setup complexity increases
Solution Approach 1:
The system performs preliminary characterization of wafer zone sensitivities to the lithographic process before production measurements. This preliminary analysis establishes the spatially varying sensitivity map and pre-determines the optimal recipe parameters for each zone, so that during actual production, the complex zonal analysis has already been completed and only the pre-determined parameters need to be applied.
Solution Approach 2:
The measurement system automatically performs the zonal analysis and determines the optimal recipe parameters for each zone without requiring manual intervention or complex external calibration procedures. The system self-calibrates by analyzing measurement data across different wafer zones and automatically assigns appropriate weighting factors and optimization criteria to each zone based on its measured sensitivity characteristics.
Data Source
AI summary
Metrology methods and modules are provided, which comprise carrying out recipe setup procedure(s) and/or metrology measurement(s) using zonal analysis with respect to respective setup parameter(s) and/or metrology metric(s). The zonal analysis comprises relating to spatially variable values of the setup parameter(s) and/or metrology metric(s) across one or more wafers in one or more lots. Wafer zones may be discrete or spatially continuous, and be used to weight one or more parameter(s) and/or metric(s) during any of the stages of the respective setup and measurement processes.