SRAM Test Device Open Contact Chain for Accurate Electrical Testing
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Solution Overview
Problem
Existing methods for testing SRAM devices, such as using electronic beams or separate test elements, are time-consuming and lack accuracy, leading to reduced productivity due to instability and structural differences between test and actual cell elements.
Innovation Solution
A test device with a first and second test active region on a semiconductor substrate, test gate lines, test contacts, conducting regions, and conductive wiring lines forming an open contact chain that mimics the cell region's structure, allowing for accurate electrical connection and testing of contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic beam method is used to test contact openings, then measurement capability is achieved, but testing time increases and productivity decreases
Solution Approach 1:
The patent replaces the electronic beam-based measurement system with a purely electrical measurement system. Test contacts are electrically connected through conducting regions and conductive wiring lines to form an open contact chain, allowing electrical continuity testing instead of electronic beam scanning. This substitution enables faster testing while maintaining measurement capability.
2Ease of manufacture
If separate test element is formed to test contacts, then testing capability is provided, but structural difference from actual cell element reduces measurement accuracy
Solution Approach 1:
The patent applies local quality by creating test contacts, conducting regions, and conductive wiring lines that replicate the exact local structure and material properties of the actual cell element contacts. The test structure uses the same contact holes, conducting regions, and wiring layers as the production cells, ensuring that contact opening behavior in the test element accurately reflects actual cell performance.
3Reliability
If more test contacts are tested through open contact chain, then contact reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple test contacts into a unified open contact chain structure. Multiple test contacts are electrically connected through conducting regions and conductive wiring lines, allowing simultaneous testing of multiple contact points. This merging approach enables comprehensive reliability assessment without proportionally increasing structural complexity, as the test contacts share common conducting regions and wiring infrastructure.
Data Source
AI summary
A test device, SRAM test device, semiconductor integrated circuit, and methods of fabricating the same are provided. The test device may include a first test active region extending in one direction on a semiconductor substrate, a second test active, apart from the first test active region, extending in one direction on a semiconductor substrate, a plurality of test gate lines crossing the test active regions, a plurality of test contacts on at least one of the test active regions and test gate lines, a plurality of conducting regions electrically connecting the test contacts, and a plurality of conductive wiring lines interconnecting the plurality of test contacts, wherein an open contact chain, which electrically connects the plurality of test contacts, is formed.