MOS Backgate-BJT Structure for Realistic Gate Dielectric Stress
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Solution Overview
Problem
Existing reliability tests for metal-oxide-semiconductor (MOS) transistors, such as DMOS transistors, accelerate gate dielectric degradation under conditions that differ from actual use, making it difficult to accurately troubleshoot and improve reliability, as they do not replicate the stress conditions encountered in real-world usage.
Innovation Solution
A semiconductor device configuration that includes a MOS transistor and a bipolar junction transistor (BJT) with an independently accessible backgate region, allowing for concurrent activation to increase hole injection into the gate dielectric, thereby accelerating degradation under conditions similar to actual product usage, enabling more accurate monitoring and troubleshooting of gate dielectric failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reliability tests are performed under accelerated stress conditions, then gate dielectric degradation can be accelerated and failure information can be obtained faster, but the test conditions differ significantly from actual use conditions making it difficult to accurately troubleshoot failures
Solution Approach 1:
The patent applies parameter changes by adjusting the electrical bias conditions applied to the MOS transistor during testing. Specifically, it uses a combination of gate voltage, drain voltage, and backgate voltage to create stress conditions that accelerate dielectric degradation while maintaining relevance to actual device operation. The backgate bias is particularly important as it allows independent control of the electric field distribution to simulate realistic stress scenarios.
Solution Approach 2:
The patent implements multi-functionality by using a single test structure that can operate in multiple modes: normal operation mode and accelerated stress mode. The same MOS transistor structure serves both as a functional device and as a reliability test vehicle, eliminating the need for separate test structures and allowing direct correlation between test results and actual device performance.
2Duration of action of stationary object
If existing reliability tests are used, then gate dielectric degradation can be accelerated, but the conditions are substantially different from actual use conditions reducing the accuracy of failure analysis
Solution Approach 1:
The patent applies dynamics by implementing time-dependent stress protocols that can be adjusted during testing. The bias conditions are dynamically changed to simulate different operational scenarios and stress levels. This allows the test to progress through different degradation stages while maintaining conditions that are relevant to actual device usage, improving the accuracy of failure mode reproduction.
Solution Approach 2:
The patent incorporates feedback mechanisms by continuously monitoring device parameters such as threshold voltage shifts, leakage current, and breakdown characteristics during the stress test. This real-time feedback allows adjustment of stress conditions to maintain optimal degradation acceleration while ensuring that the failure modes observed are representative of actual device failures.
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 configuration allows for the accelerated stress testing of gate dielectric degradation, providing insights into failure mechanisms and improving reliability by replicating the electric field conditions of actual product usage, facilitating more effective troubleshooting and yield enhancement.
Implementation Method 1
the base of the BJT injects carriers of a first charge type into the backgate region of the MOS transistor, the first charge type being opposite charge type to channel current carriers
Data Source
AI summary
The disclosed technology relates generally to semiconductor devices, and more particularly to semiconductor devices including a metal-oxide-semiconductor (MOS) transistor and are configured for accelerating and monitoring degradation of the gate dielectric of the MOS transistor. In one aspect, a semiconductor device configured with gate dielectric monitoring capability comprises a metal-oxide-semiconductor (MOS) transistor including a source, a drain, a gate, and a backgate region formed in a semiconductor substrate. The semiconductor device additionally comprises a bipolar junction transistor (BJT) including a collector, a base, and an emitter formed in the semiconductor substrate, wherein the backgate region of the MOS transistor serves as the base of the BJT and is independently accessible for activating the BJT. The MOS transistor and the BJT are configured to be concurrently activated by biasing the backgate region independently from the source of the MOS transistor, such that the base of the BJT injects carriers of a first charge type into the backgate region of the MOS transistor, where the first charge type is opposite charge type to channel current carriers.