Companion Test Screening for Semiconductor DPPM Reduction
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Solution Overview
Problem
Manufacturers face challenges in efficiently reducing test time for semiconductor devices while maintaining product quality, as full testing is costly and skipping tests may lead to unacceptable defective parts, especially when the number of potential defects is high.
Innovation Solution
Systematically identifying a companion test that can screen out a high percentage of failed parts, allowing for the reduction of test time by relabeling outliers as fails and excluding them from further processing, thereby ensuring product quality without compromising the yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full testing is performed to screen out defective parts, then product quality is maintained, but test time and manufacturing cost increase
Solution Approach 1:
The patent applies partial action by performing statistical analysis on a subset of test data to determine process capability, rather than requiring analysis of all production data. This allows the manufacturer to make quality decisions based on representative samples, reducing test time while maintaining reliability through statistical inference about the overall production process
Solution Approach 2:
The patent changes the parameter of testing from individual product inspection to process capability analysis. By shifting focus from testing each product to analyzing the statistical parameters (mean, standard deviation, capability indices) of the manufacturing process, the system can predict quality outcomes without exhaustive testing, thereby reducing test time while maintaining quality assurance
2Reliability
If full testing is performed to screen out defective parts, then product quality is maintained, but manufacturing cost increases
Solution Approach 1:
The patent reduces manufacturing cost by performing partial statistical analysis rather than comprehensive testing of all products. By analyzing capability indices from production data, the system can identify quality issues and adjust processes without incurring the full cost of extensive testing, achieving cost savings while maintaining quality standards
Solution Approach 2:
The patent implements feedback through continuous monitoring of process capability indices (Cp, Cpk) and using this information to adjust manufacturing processes. This feedback loop allows the system to maintain product quality by detecting and correcting process deviations early, avoiding the need for costly post-manufacturing testing and rework
3Loss of energy
If testing is reduced or skipped to lower costs, then manufacturing cost decreases, but the number of defective parts increases
Solution Approach 1:
The patent changes the approach from product-level testing to process-level parameter analysis. By monitoring capability indices and statistical parameters of the manufacturing process, the system can predict and prevent defective parts before they are produced, maintaining quality without requiring extensive product testing that would increase costs
Solution Approach 2:
The patent performs preliminary statistical analysis of process capability before full production runs. By evaluating Cp and Cpk indices during process setup and adjustment phases, the system can identify and correct potential quality issues beforehand, preventing defective parts from being produced in the first place and eliminating the need for costly post-production testing
Data Source
AI summary
The problem of high test cost of manufactured goods can be partially solved by lowering the percentage of the goods to be tested methodically while keeping the total defective portion of the goods expressed in DPPM below a preset target value. The method includes identifying a first test that is capable of screening out enough parts that would fail a second test so that the portion of the parts to be tested second test can be reduced. The number of parts screened out by the first test determines if the reduced testing scheme would violate the preset DPPM target value.