Multi-purpose Poly Edge Test Structure for Defect Location
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Solution Overview
Problem
Conventional test structures for semiconductor devices are limited in their ability to accurately determine the location of Time Dependent Dielectric Breakdown (TDDB) and leakage current between adjacent gate features, as they cannot provide information on the actual location of breakdown events and are restricted to testing breakdown voltage and leakage current properties.
Innovation Solution
A test structure comprising parallel polysilicon gate structures overlying a substrate with a conducting fuse connecting alternate gates, allowing for the application of potential differences to trigger breakdown and subsequent probing of individual gate groups to identify leakage currents and locate defects, such as polysilicon extrusions or bridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional test structures are used to test breakdown voltage and leakage current, then basic electrical properties can be measured, but the actual location of breakdown events and defects cannot be identified
Solution Approach 1:
The test structure divides the gate structure into multiple segments with separate contacts (first contact, second contact, third contact) that can independently access different regions. This segmentation allows precise localization of breakdown events by testing individual segments rather than the entire gate structure as a single unit.
Solution Approach 2:
The patent introduces an intermediary polysilicon region that connects the gate structure to separate contacts. This intermediary element enables independent electrical access to different gate regions, facilitating precise location identification of defects while maintaining the integrity of the gate structure.
2Ease of manufacture
If simple test structures are used, then manufacturing is easier, but the ability to test leakage current between adjacent gate features is limited
Solution Approach 1:
The test structure is designed with multi-functionality to test both breakdown voltage and leakage current between adjacent gate features using the same structure. The polysilicon gate structure with multiple contacts serves dual purposes: characterizing oxide breakdown and detecting polysilicon extrusions or bridges, thereby improving reliability without requiring separate specialized test structures.
3Loss of information
If conventional test methods are used, then basic breakdown voltage can be measured, but detailed information on defect locations and types cannot be obtained
Solution Approach 1:
The test structure incorporates feedback mechanisms where the electrical characteristics measured through different contacts provide information about the location and nature of defects. By analyzing current flow patterns and breakdown voltages across multiple contact points, the system feedbacks defect location information without requiring complex external testing equipment.
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
Enables precise testing of breakdown voltage, TDDB, and leakage current between adjacent gate features, providing detailed information on defect locations and improving the reliability of semiconductor device testing.
Implementation Method 1
A fuse lies between the first conducting pad and the second conducting pad
Implementation Method 2
a gate oxide overlying a doped silicon substrate
Data Source
AI summary
Multi-purpose poly edge test structure. According to an embodiment, the present invention provides a test structure. The test structure includes a doped silicon substrate, the doped silicon substrate being grounded, the doped silicon substrate including a first gate structure and a second gate structure, the first and second gate structures overlaying the doped silicon substrate. The test structure also includes a first conducting pad being electrically coupled to the first gate structure. The test structure also includes a second conducting pad being electrically coupled to the second gate structure.