Abnormal Die Detection Using Electrical Deviation Ranking
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Solution Overview
Problem
Current methods for detecting abnormal dies in integrated circuit manufacturing, such as Part Average Testing, are inadequate in identifying potential defects in electrical characteristics, leading to undetected defects in tested dies.
Innovation Solution
A method and system that determine surrounding dies' electrical characteristic deviations from a target die, rank these deviations, and identify characteristic-related dies within a target-related area to assess the target die's qualification based on predetermined criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Part Average Testing is used to detect abnormal dies, then the testing process is simple and fast, but the detection accuracy is insufficient and potential defects remain undetected
Solution Approach 1:
The patent segments the wafer into multiple regions (central region, first surrounding region, second surrounding region) and performs different testing strategies on each segment. The central region dies are tested individually and compared with surrounding region dies, allowing for precise identification of abnormal dies while maintaining efficient batch testing of surrounding regions.
Solution Approach 2:
The patent changes the testing parameters by introducing electrical characteristic comparisons between central region dies and surrounding region dies. By calculating difference values and comparing these against threshold values, the system achieves higher detection accuracy without sacrificing testing efficiency.
2Device complexity
If traditional testing methods are used, then the testing process is simple, but the ability to identify potential defects in electrical characteristics is insufficient
Solution Approach 1:
The patent performs preliminary classification of dies into central region and surrounding regions before detailed testing. Surrounding region dies are tested first to establish baseline electrical characteristics, which are then used to compare against central region dies. This preliminary action enables more reliable defect identification in the central region.
Solution Approach 2:
The patent implements a feedback mechanism where electrical characteristic data from surrounding region dies is used to evaluate and determine the quality of central region dies. The difference values calculated between central and surrounding dies provide feedback that indicates whether central region dies are abnormal, improving reliability without significantly increasing complexity.
Data Source
AI summary
A method for detecting an abnormal die includes providing a wafer, determining the surrounding dies in accordance with a position of a target die on the wafer, calculating a difference between a value of an electrical characteristic of each of the surrounding dies and a value of an electrical characteristic of the target die to obtain the electrical characteristic deviations, ranking the absolute values of the electrical characteristic deviations to generate a ranking result, and determining the characteristic-related dies from the surrounding dies in accordance with the ranking result, determining a target-related area in accordance with the position of the target die, determining the target-related die from the characteristic-related dies in accordance with the target-related area and determining whether the target die is qualified in accordance with the target-related die.