Exposure Alignment Correction Using Historical Shift Data
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Solution Overview
Problem
Existing exposure alignment methods for semiconductor wafers face challenges in accurately adjusting the exposure position due to shifts in the shot component, which includes rotation and telescopic shifts, often resulting in incomplete correction of these shifts during the exposure process, leading to inaccuracies in pattern alignment across multiple layers.
Innovation Solution
The method determines a first shift amount of a lower layer pattern on the exposure target substrate and a second shift amount from a past processed lot, calculates a difference between these amounts to find a third shift amount, and uses this to determine a correction value for adjusting the exposure position, thereby accounting for shifts in the lower layer pattern from past processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the exposure position is adjusted based on alignment marks to correct shot component shifts, then the overall shift can be corrected, but the load required to execute the aligning process increases and shot component correction is often omitted
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for shot component shifts based on historical data from past processed substrates. The correction values are determined in advance using the relationship between lower layer pattern shifts and exposure position adjustments, so that during actual exposure processing, the system can directly apply pre-computed corrections without performing complex real-time alignment calculations, thereby reducing the aligning process load while maintaining exposure position accuracy
2Manufacturing precision
If the exposure position is adjusted based on past processed substrate patterns, then shot component shifts can be corrected, but the lower layer pattern itself may have shifted from the past processed substrate, making accurate adjustment difficult
Solution Approach 1:
The patent applies feedback by continuously monitoring and recording the shift amounts of lower layer patterns from past processed substrates and using this historical data to calculate correction values. The system feeds back the measured shift information from previous lots to determine appropriate exposure position adjustments for current processing, creating a closed-loop correction mechanism that accounts for pattern shifts while maintaining measurement accuracy through systematic data collection and analysis
Data Source
AI summary
In an exposure aligning method, a first shift amount indicating a shift amount of a lower layer pattern of an exposure target substrate from an origin point position is determined and a second shift amount indicating a shift amount of the lower layer pattern in at lease one past lot which has been processed before said exposure target substrate is processed, from the origin point position is determined. A third shift amount indicating a difference between the first shift amount and the second shift amount is calculated and a first correction value is determined based on the third shift amount. An exposure position of an exposure target pattern is adjusted based on the first correction value.