TSV Electrical Continuity Testing via Preliminary Backside UBM
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Solution Overview
Problem
Conventional methods for testing through-silicon-via (TSV) structures are ineffective before forming backside metal and bumps, making it difficult to determine defects, thereby impacting semiconductor fabrication throughput, efficiency, and cost.
Innovation Solution
A method involving wafer thinning from the backside, forming an under bump metallization (UBM) layer or patterned conductive layers on the backside to serve as a grounding layer, allowing for early electrical continuity testing of TSV structures using a probing card before the formation of bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional inline electrical testing is performed before forming backside metal and bumps, then testing can be done earlier in the process, but the TSV structures are not functional and cannot be tested for continuity
Solution Approach 1:
The patent forms a preliminary conductive layer on the backside of the wafer before completing the conventional backside metal and bump formation. This preliminary conductive structure enables electrical continuity testing of TSV structures at an earlier stage in the manufacturing process, resolving the contradiction between early testing and functional capability by creating a temporary test-enabling structure that is later removed or integrated into the final device.
2Reliability
If backside metal and bumps are formed before testing, then TSV structures become functional and testable, but throughput and efficiency are adversely influenced due to delayed defect detection
Solution Approach 1:
The patent performs the electrical continuity testing action in advance by creating a preliminary conductive layer that enables testing before the full backside metal and bump structure is complete. This preliminary testing action allows defect detection to occur earlier in the manufacturing sequence, improving throughput by identifying and addressing defects before additional processing steps are performed on defective wafers.
3Loss of time
If TSV structures are tested before forming backside metal and bumps, then defect detection can occur earlier, but no grounding layer exists to enable electrical continuity measurement
Solution Approach 1:
The patent introduces a preliminary conductive layer as an intermediary element that temporarily serves as a grounding layer during the testing phase. This intermediary structure enables electrical continuity measurement by providing a reference potential on the backside of the wafer, and is later removed or integrated into the final device structure, thus enabling early testing without permanent additional complexity.
Data Source
AI summary
A method for testing TSV structures includes providing a wafer having a front side and a back side, the wafer further comprising a plurality of TSV structures formed therein; thinning the wafer from the back side of the wafer; forming a first under bump metallization layer on the back side of the wafer blanketly; providing a probing card to the front side of the wafer to test the TSV structures; and patterning the first UBM layer.