Semiconductor Test Circuit Isolation for TDDB Accuracy
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Solution Overview
Problem
Existing methods for testing time-dependent dielectric breakdown (TDDB) characteristics in semiconductor devices often damage the main circuit when the test transistor breaks down, limiting the number of data obtainable and reducing test accuracy.
Innovation Solution
A semiconductor device with a test circuit that includes a test transistor and input and protection switches, allowing for electrical isolation of the test circuit from the main circuit, enabling stress voltage application and subsequent grounding to prevent damage and enhance data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test transistor is formed on a die to test TDDB characteristics, then test accuracy and data collection are improved, but the main circuit may be damaged when the test transistor breaks down
Solution Approach 1:
The patent divides the circuit into separate test circuit and main circuit regions on the die. The test transistor is isolated in a dedicated test circuit area with separate voltage application nodes, allowing independent testing without affecting the main circuit. This spatial segmentation enables accurate TDDB testing while protecting the main circuit from damage.
Solution Approach 2:
The patent introduces protection switches as intermediary elements between the test transistor and the main circuit. These switches act as mediators that can disconnect the test circuit from the main circuit when breakdown occurs, preventing harmful effects from propagating to the main circuit while allowing continuous testing.
2Object-affected harmful factors
If a test transistor is formed on a tag area of a wafer to avoid damaging the main circuit, then the main circuit is protected, but the number of data obtainable is limited
Solution Approach 1:
The patent segments the die into multiple independent test circuits, each containing a test transistor. This allows multiple test transistors to be formed on each die, significantly increasing the number of test data points that can be collected while maintaining circuit protection through the same isolation mechanisms.
3Measurement precision
If stress voltage is applied to test transistor to measure breakdown time, then TDDB characteristics can be tested, but leakage current may damage adjacent main circuit
Solution Approach 1:
The patent introduces protection switches as intermediary elements between the test transistor and the main circuit. These switches can be controlled to disconnect the test circuit from the main circuit when leakage current exceeds safe levels, preventing damage while allowing continuous stress voltage application for accurate breakdown time measurement.
Solution Approach 2:
The test transistor is designed as a sacrificial element that can be repeatedly stressed and replaced. The protection circuitry is designed to allow the test transistor to fail without affecting permanent components, enabling multiple measurement cycles on the same die.
Data Source
AI summary
Provided are a semiconductor device and a method of operating the same. A semiconductor includes a test circuit which comprises: a test transistor to be tested for time-dependent dielectric breakdown (TDDB) characteristics using a stress voltage; an input switch disposed between a voltage application node to which the stress voltage is applied and an input node which transmits the stress voltage to the test transistor; and a protection switch disposed between the input node and a ground node.