Via Location Metrology for Lithography Overlay Correction
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Solution Overview
Problem
Advanced packaging substrates face alignment errors due to unknown actual locations of laser-drilled holes, leading to misalignment between layers and increased contact resistance, which affects yield and performance.
Innovation Solution
A method to measure and correct alignment errors by comparing via locations on a substrate to planned locations, preparing offset data, and entering it into a lithographic tool database, using a larger dataset for improved alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional alignment methods using fewer alignment points are used, then throughput is improved, but alignment accuracy deteriorates
Solution Approach 1:
The system performs preliminary measurements of via locations before lithography exposure, compares them to planned locations, and calculates offset data in advance. This preliminary action enables accurate alignment correction to be applied during exposure, allowing reduced alignment points while maintaining accuracy.
Solution Approach 2:
The system measures actual via locations, compares them to planned locations from the production file, and uses the measured offsets as feedback to generate correction data. This feedback loop enables the system to compensate for alignment errors and achieve high accuracy with fewer alignment points during exposure.
2Manufacturing precision
If more alignment points are used per exposure, then alignment accuracy is improved, but throughput deteriorates
Solution Approach 1:
Comprehensive via location measurements and offset calculations are performed in advance before exposure. This preliminary action shifts the alignment work to a pre-processing stage, enabling fewer alignment points to be used during the actual exposure process while maintaining high accuracy through the pre-calculated offset corrections.
3Speed
If actual via locations are not measured, then process speed is improved, but alignment precision deteriorates
Solution Approach 1:
Via location measurements are performed as a preliminary step before lithography exposure. By completing the measurement and offset calculation work in advance, the system enables fast exposure processing with high alignment precision, as the correction data is already prepared and ready for application.
Solution Approach 2:
The system measures actual via locations and uses this feedback information to calculate offset corrections. This feedback enables the system to achieve high alignment precision by compensating for actual deviations from planned via locations, while the corrections are applied efficiently to maintain process speed.
Data Source
AI summary
Various examples herein describe an apparatus and related method to track and correct alignment errors of features used on a substrate. For example, in various embodiments, the disclosed subject-matter is a method for measuring x-coordinates and y-coordinates of a number of features (such as vias) on a layer on the substrate for each of the layers formed on the substrate that are to underlie a subsequently formed layer; compare the x-coordinates and the y-coordinates on the layer to respective locations of a production file used to determine a planned location of the features for each of the respective layers; prepare offset data based on the comparison for each of the respective layers; and enter the offset data into a lithographic tool database to minimize or correct the alignment errors for each of the respective layers. Other systems, apparatuses, and methods are also disclosed.