Semiconductor Overlay Sampling for Incomplete Wafer Shots
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Solution Overview
Problem
Conventional semiconductor overlay processes ignore observation points in incomplete shots, leading to calculation errors and reduced yield in these areas.
Innovation Solution
A method to select and uniformly distribute observation points in incomplete shots by eliminating those with fewer than three points, adjusting their distribution to meet a preset total, and generating an offset vector map using the remaining points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If observation points in incomplete shots are abandoned without calculation, then the processing complexity is reduced, but the offset vector calculation accuracy deteriorates and die yield decreases
Solution Approach 1:
The patent changes the parameter of observation point selection by introducing a minimum threshold (3 observation points) and a uniform distribution requirement. This transforms the approach from completely abandoning incomplete shots to selectively including them based on quantitative criteria, thereby improving offset vector calculation accuracy while maintaining manageable processing complexity.
Solution Approach 2:
The patent applies partial action by not including all observation points from incomplete shots, but only those that meet the uniform distribution criterion. This selective inclusion improves accuracy for critical areas without overwhelming the processing system with excessive data from poorly distributed points.
2Productivity
If all observation points in incomplete shots are included, then the die yield in incomplete shots improves, but the calculation error increases due to non-uniform distribution
Solution Approach 1:
The patent introduces a uniform distribution parameter as a selection criterion for observation points in incomplete shots. This parameter change ensures that only observation points meeting the uniform distribution requirement are included, thereby improving die yield without compromising offset vector calculation accuracy.
Solution Approach 2:
The patent applies local quality by treating observation points in incomplete shots differently from those in complete shots. Specifically, it evaluates the uniform distribution of observation points locally in each incomplete shot and selectively includes only those with adequate distribution, thereby improving local die yield while maintaining global calculation accuracy.
3Measurement precision
If observation points are uniformly distributed and filtered by threshold, then the offset vector accuracy improves, but the processing steps and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-filtering observation points in incomplete shots based on the uniform distribution criterion before performing offset vector calculations. This preliminary filtering step ensures that only high-quality observation points are processed, improving offset vector accuracy while preventing excessive processing complexity during the main calculation phase.
Data Source
AI summary
The invention provides a semiconductor manufacturing process, which comprises the following steps: using a computer system to define plurality of shots on a wafer range, distributing a plurality of observation points in each shot, finding out parts of incomplete shots from all of the shots, calculating the number of observation points in each incomplete shot, eliminating the incomplete shots with the number less than 3 observation points, counting all observation points in the remaining incomplete shots, and deleting a part of observation points until the total number of observation points meets a preset total number, and uniformly distributing all observation points, and performing an overlay measurement step on the remaining observation points to generate an offset vector map.