Dynamic Substrate Grid Alignment for Metrology Accuracy
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Solution Overview
Problem
Current substrate alignment methods in metrology tools for IC manufacturing are limited by accuracy and throughput, with two-step coarse and fine alignment processes that are prone to errors due to dynamic behavior and hysteresis, leading to measurement inaccuracies and the need for frequent realignments.
Innovation Solution
A method that determines a substrate grid based on measurements of multiple targets, updating the grid after each measurement to align subsequent targets, using target-to-position offset information to improve alignment accuracy and eliminate the need for fine alignment steps, thereby enhancing accuracy and reducing realignment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-step coarse and fine alignment processes are used, then alignment precision can be improved, but alignment time increases and system complexity increases
Solution Approach 1:
The patent extracts and eliminates the fine alignment step from the traditional two-step alignment process. By using a single coarse alignment step with updated alignment marks, the method removes the time-consuming fine alignment operation while maintaining alignment precision through dynamic grid updates based on measured mark positions.
Solution Approach 2:
The patent performs preliminary measurement of alignment mark positions during the coarse alignment step to determine actual grid positions. This preliminary action allows the system to calculate and apply position offsets before subsequent measurements, eliminating the need for a separate fine alignment step and reducing total alignment time.
2Measurement precision
If two-step coarse and fine alignment processes are used, then alignment precision can be improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the fine alignment step from the traditional two-step alignment process. By using a single coarse alignment step with updated alignment marks, the method removes the time-consuming fine alignment operation while maintaining alignment precision through dynamic grid updates based on measured mark positions.
Solution Approach 2:
The patent merges the functions of coarse alignment and fine alignment into a single alignment operation. By combining the grid establishment with dynamic position updates based on measured alignment marks, the method achieves fine alignment precision within the coarse alignment step, simplifying the overall process architecture.
3Ease of operation
If traditional alignment methods are used, then initial alignment can be achieved, but measurement accuracy deteriorates due to dynamic behavior and hysteresis
Solution Approach 1:
The patent implements a dynamic alignment grid that is updated based on measured positions of alignment marks. Instead of using a static grid, the system continuously adapts the grid positions to account for dynamic behavior and hysteresis in the alignment stage, thereby maintaining measurement accuracy throughout the measurement process.
Solution Approach 2:
The patent incorporates feedback by measuring the actual positions of alignment marks and using these measurements to update the alignment grid. This feedback loop compensates for dynamic behavior and hysteresis effects, ensuring that subsequent measurements are performed with accurate position references despite system instabilities.
Data Source
AI summary
A method of aligning a substrate within an apparatus. The method includes determining a substrate grid based on measurements of a plurality of targets, each at different locations on a substrate. The determining includes repetitions of updating the substrate grid after each measurement of a target, and using the updated grid to align a measurement of a subsequent target.