Wafer Carrier Test Circuit for Semiconductor Yield Optimization
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Solution Overview
Problem
The high cost and inefficiency of semiconductor wafer testing, particularly due to the need for extensive dedicated testing facilities and the significant time and resources required for testing, which can be reduced by implementing testing during transit in wafer carriers.
Innovation Solution
Incorporating a test circuit within the wafer carrier to perform testing on wafers while they are being transported between manufacturing locations, using physical, wireless, or optical connections to stimulate built-in self-test circuits and transmit test data back to the carrier for remote processing, allowing for adjustments to the manufacturing process to improve yield and repair defective chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive dedicated testing facilities and procedures are used to test wafers after manufacturing, then testing completeness and reliability are improved, but testing time and manufacturing cost increase significantly
Solution Approach 1:
The patent applies preliminary action by performing initial testing on the wafer while it is still in the wafer carrier, before the wafer is removed and before final testing. The test circuit in the wafer carrier executes preliminary test routines that identify obvious defects early, so that when the wafer reaches the dedicated testing facility, only wafers that passed preliminary testing need comprehensive testing, significantly reducing total testing time while maintaining reliability
Solution Approach 2:
The testing process is segmented into two stages: preliminary testing performed in the wafer carrier using a simple test circuit, and comprehensive final testing performed at the dedicated testing facility. This segmentation allows the testing workflow to be divided such that quick preliminary tests filter out obviously defective wafers, reducing the burden on the dedicated testing facility and overall testing time
2Reliability
If extensive dedicated testing facilities and procedures are used, then testing completeness is improved, but manufacturing cost increases significantly
Solution Approach 1:
By performing preliminary testing in the wafer carrier before the wafer reaches the dedicated testing facility, the system identifies and flags obviously defective wafers early. This allows the expensive dedicated testing facility to focus resources on wafers that actually need comprehensive testing, reducing the overall testing cost while maintaining testing completeness for wafers that require it
Solution Approach 2:
The testing system is segmented into a low-cost preliminary testing stage using simple circuitry in the wafer carrier, and a high-cost comprehensive testing stage at the dedicated facility. This segmentation optimizes resource allocation by applying expensive testing resources only where necessary, reducing overall manufacturing cost while maintaining testing completeness
3Device complexity
If wafers are tested only after all manufacturing operations are complete, then manufacturing process simplicity is maintained, but the ability to identify and remedy manufacturing issues early is lost
Solution Approach 1:
The patent implements preliminary action by adding a test circuit to the wafer carrier that enables testing to occur during or between manufacturing operations. This allows early identification of manufacturing issues so that remedial actions can be taken on subsequent wafers, improving overall manufacturing yield without significantly increasing process complexity
Solution Approach 2:
The test circuit provides real-time feedback on wafer quality during the manufacturing process. When defects are detected, this feedback can be used to adjust manufacturing parameters for subsequent wafers, creating a closed-loop system that continuously improves yield. The feedback mechanism is integrated into the existing manufacturing workflow, minimizing added complexity
Data Source
AI summary
In accordance with one embodiment of the invention, a method and apparatus are provided for testing a wafer while the wafer is disposed in a wafer carrier. The test results can be utilized to adjust the manufacturing process and thereby increase processing yield.