Stacked-Die Semiconductor Testing via Flat Contacts and Socket Verification
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Solution Overview
Problem
The yield of semiconductor devices with multiple stacked die is low due to the inability to individually test each die before packaging, leading to the failure of entire devices when one faulty die is present, despite other die being functional.
Innovation Solution
A method involving wafer probe testing followed by full functional testing in a test socket, where individual die are prepared with flat metal contacts and molded into units that can be socket tested to ensure only functional die are included in multi-die semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wafer probe testing is used to eliminate defective die, then some defective die are eliminated, but the testing is incomplete and cannot detect all functional defects
Solution Approach 1:
The patent performs wafer probe testing as a preliminary action before packaging to eliminate obviously defective die. This preliminary screening reduces the number of die that need to be packaged, and subsequently, individual socket testing is performed on packaged die to complete the functional verification. This two-stage approach balances early defect elimination with comprehensive testing.
2Reliability
If complete functional testing is performed on each die individually before packaging, then all defective die can be eliminated, but the manufacturing process becomes complex and time-consuming
Solution Approach 1:
The patent performs preliminary wafer probe testing to eliminate obviously defective die before packaging. This preliminary action reduces the number of die requiring individual socket testing, thereby reducing overall process complexity while maintaining high reliability through the subsequent individual testing of packaged die.
Solution Approach 2:
The testing process is segmented into two distinct stages: wafer probe testing performed on the wafer before dicing, and individual socket testing performed on packaged die. This segmentation allows each testing stage to be optimized independently and reduces the complexity of performing complete testing on all die before packaging.
3Adaptability or versatility
If multiple die are stacked in a single package, then device functionality is enhanced, but the probability of including a faulty die increases
Solution Approach 1:
The patent performs preliminary wafer probe testing to eliminate obviously defective die before packaging into multi-die stacks. This preliminary action reduces the probability of including faulty die in stacked packages, thereby maintaining high reliability while enabling enhanced device functionality through multi-die stacking.
Solution Approach 2:
The patent implements a feedback mechanism where test results from wafer probe testing and individual socket testing are used to determine which die are suitable for stacking. Only die that pass both testing stages are included in stacked packages, ensuring high reliability while enabling enhanced functionality through multiple die.
4Productivity
If wafer probe testing is performed, then some defective die are eliminated, but the yield is still low due to undetected defects
Solution Approach 1:
The patent performs preliminary wafer probe testing to eliminate obviously defective die and reduce the pool of die requiring individual socket testing. This preliminary action improves productivity by reducing testing workload, while individual socket testing of packaged die ensures thorough defect detection and maintains high yield by only eliminating die with actual functional defects.
Data Source
AI summary
In constructing a multi-die semiconductor device, a plurality of semiconductor die are provided. Each die is probe tested when it is part of a wafer. Flat contacts are connected to each die when it is part of a wafer. After wafer sawing, each die is tested in a test socket, using the contacts connected thereto. The die are then packaged in stacked relation to form the multi-die semiconductor device.