Reliability Comparison for Semiconductor ICs Using BOW Index
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Solution Overview
Problem
Conventional methods for monitoring and controlling process-related information in semiconductor integrated circuit manufacturing are limited, as they often rely on mean time to failure (MTTF) metrics, which do not adequately compare the reliability of products with different failure distributions, even if they meet lifetime requirements.
Innovation Solution
A method and system that determine reliability density functions for two groups, calculate failure probability density functions, and use the 'Better or Worse' (BOW) index to compare their reliability, allowing for the assessment of reliability comparability (RC) across various failure behaviors and distributions without assuming a specific lifetime distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MTTF metrics are used to compare reliability of semiconductor products, then the comparison is simple and straightforward, but the reliability comparison is inaccurate when products have different failure distributions
Solution Approach 1:
The patent transforms the reliability comparison from using single-parameter MTTF metrics to using multi-parameter reliability density functions and cumulative distribution functions. By changing the parameters from simple mean time to failure to comprehensive distribution functions, the method achieves accurate reliability comparison even when products have different failure distributions, while maintaining computational feasibility through standardized mathematical operations.
2Reliability
If conventional monitoring techniques are used, then the process is easy to implement, but the reliability assessment is insufficient for products with different failure behaviors
Solution Approach 1:
The patent introduces reliability density functions and cumulative distribution functions as intermediary mathematical tools to bridge the gap between different failure distributions. These intermediary functions enable meaningful comparison between products with different failure behaviors by providing a common mathematical framework, thus improving reliability assessment accuracy without requiring complex custom analysis for each product type.
3Adaptability or versatility
If reliability comparison methods assume specific lifetime distributions, then the analysis is mathematically tractable, but the method lacks adaptability to various failure behaviors
Solution Approach 1:
The patent creates a universal reliability comparison methodology that works with any lifetime distribution without requiring product-specific assumptions. By using general reliability density functions and cumulative distribution functions that can represent any failure behavior pattern, the method achieves both adaptability to various distributions and mathematical tractability through standardized comparison procedures applicable to all semiconductor products.
Data Source
AI summary
A method for determining whether a first group of a product, a component or a system in reliability life testing has longer lifetime than a second group. This method is non-parametric and free from a pre-assumption of statistical distributions and can be applied to all kinds of data and distributions. Errors from goodness-of-fit of distribution fitting and parameter estimations are thus eliminated. After pre-check on bimodal, early failures, and the failure mechanisms, the method employs numerical solutions with good accuracy by the nonparametric approach. The data under consideration can be censored, interval or bimodal, and not limited to simple cases of complete type. The method can be used to determine multiplicities of reliability tests for all product types and at all levels. Based on a comparability index derived from integrating the weighted difference between the reliability functions of the two groups under comparison. Several indices are proposed for effectiveness of reliability comparability.