Wafer Electrical Test Prediction Using Shot-Region Sampling
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Solution Overview
Problem
Existing electrical test methods in semiconductor manufacturing are limited by the need for extensive sampling and struggle to accurately predict electrical test characteristics of unmeasured regions on a wafer, leading to inefficiencies in defect detection and process improvement.
Innovation Solution
A computing device and apparatus that utilize machine learning to determine a relationship between electrical test data and electrical die sorting data, enabling prediction of electrical test characteristics across the entire wafer based on sampled data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive sampling is performed to accurately predict electrical test characteristics, then measurement precision is improved, but productivity deteriorates due to increased testing time and cost
Solution Approach 1:
The patent performs electrical tests on a subset of shot regions (e.g., 4 out of 16 regions) as a preliminary action, then uses machine learning to predict the electrical test characteristics for the remaining unmeasured regions. This preliminary sampling combined with predictive modeling achieves high prediction accuracy without requiring extensive physical testing of all regions, thus resolving the contradiction between measurement precision and productivity.
Solution Approach 2:
The patent introduces machine learning algorithms as an intermediary between the measured electrical test data and the unmeasured regions. The ML model acts as a mediator that infers characteristics of untested regions based on patterns from tested regions, enabling accurate predictions without direct physical measurement of all areas, thereby improving both accuracy and efficiency.
2Productivity
If machine learning is used to predict electrical test data, then productivity is improved by reducing sampling requirements, but device complexity increases due to additional computational components
Solution Approach 1:
The patent creates a virtual copy of the physical testing process through machine learning models. Instead of physically testing all regions, the system trains ML models on a subset of measured data to replicate and predict test outcomes for unmeasured regions. This copying approach enables efficient prediction with reduced physical testing while managing computational complexity through standardized ML frameworks.
Solution Approach 2:
The patent develops a universal machine learning framework that can predict multiple electrical test characteristics simultaneously across different shot regions. The same ML infrastructure handles various test parameters (current, voltage, resistance) and multiple spatial regions, reducing overall system complexity compared to separate specialized systems for each measurement type.
3Measurement precision
If electrical tests are performed on all shot regions, then measurement precision is improved, but loss of time increases due to extended testing duration
Solution Approach 1:
The patent performs electrical tests on a preliminary subset of shot regions (e.g., 4 regions) and uses machine learning to predict results for remaining regions. This preliminary action combined with computational prediction achieves comprehensive test coverage information without requiring sequential physical testing of all 16 regions, significantly reducing testing time while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical/physical process of sequentially testing all shot regions with a computational substitution. After measuring a subset of regions, the system uses machine learning algorithms to substitute for the remaining physical measurements, inferring test results through computational modeling rather than continued physical testing, thus reducing time loss while maintaining comprehensive data coverage.
Data Source
AI summary
A method of operating an electrical test prediction apparatus includes determining a relationship between first electrical test (ET) data, corresponding to at least one shot region comprising a subset of a plurality of semiconductor chips of a wafer, and electrical die sorting (EDS) data, obtained by measuring a state of each chip on the wafer by a testing device, and predicting second ET data, corresponding to an region of the wafer other than the at least one shot region by performing machine learning on the relationship.


