Semiconductor Interconnect Electro-Migration Testing
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Solution Overview
Problem
Conventional electro-migration testing of semiconductor devices requires multiple power supplies and complex wiring to test multiple interconnects simultaneously, which is costly and inefficient, and only measures the weakest link in a daisy-chain arrangement, failing to provide a complete statistical range of results.
Innovation Solution
A method involving a substrate with a conductive layer and a resistive element between portions, allowing a test current to flow through multiple interconnects in sequence until continuity failure, with the resistive element maintaining current flow after failure, enabling simultaneous testing of multiple interconnects using a single power supply and continuous testing beyond initial failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple power supplies and complex wiring are used to test multiple interconnects simultaneously, then testing completeness is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple power supplies into a single power supply by using a current source that can sequentially drive test current through multiple interconnects. The substrate wiring is designed to share common conductive paths (first conductive layer, second conductive layer) among multiple interconnect structures, eliminating the need for separate power supplies and reducing wiring complexity while maintaining testing completeness.
Solution Approach 2:
The substrate and its conductive layers serve multiple functions: they provide mechanical support, electrical connection, and current distribution to multiple interconnects simultaneously. The single power supply unit performs the function of multiple power supplies by sequentially testing different interconnects through the shared conductive path, making the system more universal and less complex.
2Device complexity
If daisy-chain arrangement is used to test multiple interconnects, then device complexity is reduced, but measurement precision deteriorates as only the weakest link is measured
Solution Approach 1:
The patent segments the testing process into discrete test cycles, where each cycle tests one interconnect while others remain intact. The substrate includes multiple separate interconnect structures (first interconnect, second interconnect, etc.) that can be tested independently through the shared conductive path. This segmentation allows complete statistical evaluation of all interconnects rather than only the weakest link.
Solution Approach 2:
The testing process maintains continuity by using a single power supply that sequentially drives current through each interconnect without interruption. After one interconnect fails, the testing continues with remaining interconnects through the same power supply and conductive path, ensuring continuous useful action and complete statistical data collection from all interconnects.
3Ease of manufacture
If conventional testing method is used, then implementation simplicity is maintained, but productivity decreases due to inability to test multiple interconnects simultaneously
Solution Approach 1:
The patent combines multiple interconnect testing functions into a single substrate with shared conductive layers and a single power supply. This merging enables simultaneous preparation of multiple interconnects for testing while using the same test equipment, significantly improving productivity without sacrificing implementation simplicity.
Solution Approach 2:
The substrate design includes self-contained interconnect structures with integrated conductive paths that automatically route test current through each interconnect in sequence. The substrate itself provides the testing infrastructure, eliminating the need for complex external wiring and making the system both simple to implement and highly productive.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for efficient and comprehensive electro-migration testing of multiple interconnects with a single power supply, providing a complete statistical range of results and reducing costs by maintaining current flow through the resistive element after individual interconnect failures, thereby extending the testing duration and accuracy.
Implementation Method 1
forming a resistive element between first and second portions of the conductive layer... The test current continues to flow through the resistive element after the continuity failure of the second bump
Implementation Method 2
routing a test current in sequence through the first portion of the conductive layer, through the first and second bumps, and through the second portion of the conductive layer until continuity failure of the second bump... The electron momentum associated with the large DC current causes metal atoms from the bump and conductive layers under test to move with the current flow
Data Source
AI summary
A semiconductor device has a substrate and conductive layer over the substrate. A resistive element is formed between first and second portions of the conductive layer. A plurality of semiconductor die each with first and second bumps is mounted to the substrate with the first and second bumps electrically connected to the first and second portions of the conductive layer. A test current is routed in sequence through the first portion of the conductive layer, through the first and second bumps, and through the second portion of the conductive layer until continuity failure of the second bump. The test current originates from a single power supply. The test current continues to flow through the resistive element after the continuity failure of the second bump. The continuity failure can be detected by sensing an increase in voltage across the second bump.