Wafer Sort Die Characterization for Inventory Cost Reduction
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Solution Overview
Problem
The existing process of manufacturing integrated circuits (ICs) results in high inventory costs due to the packaging of low-performance dies, which cannot be sold as high-performance dies, leading to increased depreciation and storage costs.
Innovation Solution
Characterizing dies during the wafer sort stage using a more stringent quality metric constraint than the final test stage, allowing for early binning and storage in an unpackaged state, thereby reducing the number of packaged low-performance dies and minimizing inventory costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If speed binning is performed on packaged dies at the final test stage, then high-performance dies can be identified and sold at premium prices, but low-performance dies must be packaged and kept in inventory, resulting in high inventory costs due to 30% annual depreciation
Solution Approach 1:
The patent performs speed binning characterization during the wafer sort stage before packaging, rather than at the final test stage after packaging. This preliminary characterization allows the manufacturer to identify high-performance dies early and package only those dies that will meet customer requirements, avoiding the inventory depreciation problem of packaged low-performance dies while maintaining accurate speed binning classification
2Ease of manufacture
If all dies are packaged before final testing, then all dies can be tested with the same constraint, but low-performance dies incur high inventory costs and occupy storage resources
Solution Approach 1:
The patent performs preliminary speed binning characterization during wafer sort before packaging, enabling the manufacturer to determine which dies will meet high-performance requirements. This allows selective packaging of only those dies intended for high-performance applications, reducing the quantity of packaged dies that would otherwise become costly inventory, while maintaining testing simplicity through automated characterization
3Productivity
If a less stringent constraint is used at wafer sort stage, then more dies can be packaged, but more low-performance dies end up in inventory increasing costs
Solution Approach 1:
The patent applies a more stringent constraint during wafer sort stage speed binning characterization than would be applied at final test. This preliminary stringent filtering ensures that only dies capable of meeting high-performance requirements are packaged, thereby maintaining high packaging throughput of qualified dies while minimizing the number of packaged dies that would become costly inventory
Solution Approach 2:
The patent changes the constraint parameter from the standard final test constraint to a more stringent wafer sort constraint during preliminary characterization. This parameter change enables the system to differentiate between dies that can meet high-performance requirements and those that cannot, allowing selective packaging that maximizes productivity of qualified dies while minimizing inventory costs
Data Source
AI summary
An embodiment of a method to characterize a die is disclosed. The embodiment of the method includes measuring a quality metric of the die, and determining, prior to a final test stage, whether the quality metric of the die satisfies a first constraint, where the first constraint is more stringent than a second constraint at the final test stage for the quality metric of the die.