Accelerated Semiconductor Lifetime Testing via Negative Gate Bias
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Solution Overview
Problem
Current methods for determining the lifetime of semiconductor power devices under accelerated life tests, such as ALT-HTRB, are time-consuming and costly, requiring 10,000 to 20,000 hours to achieve sufficient failure data, which delays reliability assessment and remedial measures.
Innovation Solution
A system and process that applies a negative gate bias voltage (Vgs) and varies temperature conditions to increase the electric field in semiconductor power devices, allowing for faster failure rates and reducing testing time by applying a negative gate bias voltage (Vgs) during the test, thereby accelerating the failure rate and achieving results more quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ALT-HTRB testing is used to determine semiconductor device lifetime, then sufficient failure data can be obtained for reliable lifetime determination, but the testing time becomes excessively long (10,000 to 20,000 hours or more)
Solution Approach 1:
The patent applies parameter changes by introducing a negative gate bias voltage (Vgs) in addition to the traditional reverse bias voltage. This changes the electrical stress parameters applied to the device, creating accelerated failure conditions that maintain statistical validity while reducing test duration from 10,000-20,000+ hours to a more manageable timeframe.
Solution Approach 2:
The patent implements dynamics by varying the gate bias voltage dynamically during the test sequence. The test applies different voltage stress levels in sequence, with each stress level designed to accelerate failure modes differently, allowing the system to adaptively gather failure data across multiple operating conditions without requiring excessively long continuous testing.
2Reliability
If traditional ALT-HTRB testing is used, then lifetime data can be collected, but testing costs increase substantially due to the extended testing period
Solution Approach 1:
By changing the electrical stress parameters to include negative gate bias voltages, the patent accelerates the failure rate of semiconductor devices. This parameter modification allows sufficient failure data to be collected in a shorter time period, thereby reducing the energy consumption and operational costs associated with extended testing campaigns.
3Measurement precision
If extended testing periods are used to gather sufficient failure data, then statistical confidence in lifetime determination is achieved, but delays occur in obtaining and analyzing critical reliability data
Solution Approach 1:
The patent uses dynamic voltage stress sequencing to accelerate failure accumulation. By applying different stress levels in a structured sequence, the system maintains statistical rigor for lifetime determination while significantly reducing the time required to accumulate sufficient failure data for confident reliability assessment.
Solution Approach 2:
The patent implements preliminary action by applying controlled stress conditions that pre-accelerate failure mechanisms. The negative gate bias voltage is applied in advance to induce and accelerate degradation processes, allowing failure data to be collected much faster than under normal operating conditions while maintaining statistical validity.
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 significantly reduces the time required for high voltage lifetime evaluation of semiconductor power devices, achieving a first predetermined confidence level of statistical failure data in 3000 to 9000 hours, which is 30% to 80% faster than prior art methods, and allows for a more efficient determination of device reliability.
Implementation Method 1
arranging an N number of devices in a temperature-controlled environment such that a temperature of the N number of devices is near one of the following: a maximum temperature rated for the N number of devices and a minimum temperature rated for the N number of devices
Implementation Method 2
applying a negative gate bias voltage (Vgs) to the N number of devices; applying a drain voltage (Vds) to the N number of devices
Implementation Method 3
measuring currents and/or device voltages of the N number of devices to generate device test data
Data Source
AI summary
A process and system for testing includes: arranging devices in a temperature-controlled environment; applying a negative gate bias voltage (Vgs) to the devices; applying a drain voltage (Vds) to the devices; measuring currents and/or voltages of the devices to generate device test data; determining a failure of one or more of the devices based on the device test data generated from the device currents and/or the voltages to generate failure data; and outputting the failure data for the of devices.