Substrate Alignment Method Using Multiple Marks
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Solution Overview
Problem
Conventional substrate alignment methods are inefficient due to prolonged alignment times and low yield of semiconductor devices caused by obscure alignment marks and a single allowable alignment score standard, which can misclassify accurately aligned substrates as abnormal.
Innovation Solution
A method that sequentially identifies and utilizes multiple alignment marks with varying brightness and shapes across different shot regions, adjusting alignment scores to optimize alignment, and includes a descending order of allowable scores to correctly identify and align substrates, reducing alignment time and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single alignment mark is aligned with a predetermined coordinate, then the alignment process is simple, but the alignment time becomes too long and yield decreases
Solution Approach 1:
The alignment process is segmented into multiple independent alignment marks (first alignment mark, second alignment mark, third alignment mark) located in different shot regions. Each alignment mark can be processed independently, allowing parallel identification and alignment operations that reduce total alignment time while maintaining process simplicity.
2Device complexity
If only one allowable alignment score is set, then the determination standard is simple, but accurately aligned substrates may be misclassified as abnormal
Solution Approach 1:
The system changes the alignment score parameter by setting multiple allowable alignment scores (first allowable alignment score, second allowable alignment score) instead of a single threshold. This allows the system to accommodate variations in alignment quality while maintaining reliable determination, preventing misclassification of accurately aligned substrates as abnormal.
3Device complexity
If alignment marks are identified in sequential order across shot regions, then the identification process is systematic, but the total identification time increases
Solution Approach 1:
The system performs preliminary identification of multiple alignment marks across different shot regions simultaneously or in optimized sequences before final alignment determination. This preliminary action allows the system to prepare alignment data in advance, reducing the total time required for the complete alignment process while maintaining systematic identification.
Data Source
AI summary
In a method of aligning a substrate, a first alignment mark and a second alignment mark in a first shot region on the substrate may be sequentially identified. The substrate may be primarily aligned using identified any one of the first alignment mark and the second alignment mark. A used alignment mark and an unused alignment mark during the primary alignment process of the first alignment mark and the second alignment mark in a second shot region on the substrate may be sequentially identified. The substrate may be secondarily aligned using identified any one of the used alignment mark and the unused alignment mark during the primary alignment process. Thus, a time for identifying the alignment mark may be reduced.