Semiconductor Junction Testing via Constant Voltage Avalanche
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Solution Overview
Problem
Current methods for testing semiconductor devices in mass production, such as avalanche testing and die attach testing, face challenges with self-heating issues that affect test accuracy and throughput, as they require significant time and can interfere with each other, leading to reduced efficiency and increased testing times.
Innovation Solution
A method and device that apply a fixed voltage higher than the breakdown voltage to a semiconductor device's junction, measuring the resulting breakdown current to determine dissipated power and thermal impedance, allowing for a consistent stress level and reducing the impact of thermal impedance variations, enabling faster and more accurate testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant current avalanche pulse is applied for 500 μs, then the test can be performed with normal measurement equipment, but the test cannot screen defects as well as the UIS test and requires special equipment or complex setups
Solution Approach 1:
The patent changes the test parameters by applying a constant voltage instead of constant current during the avalanche test. This voltage parameter is specifically set to 1.05-1.5 times the breakdown voltage, which fundamentally alters the test characteristics to achieve both simplicity and high defect detection capability without requiring complex UIS equipment
2Reliability
If UIS test equipment is used, then defect screening capability is improved, but the equipment is expensive and slows down the handler, reducing units per hour from potential high throughput to lower throughput
Solution Approach 1:
The patent employs a simple, inexpensive constant voltage source that can be implemented with normal measurement equipment rather than expensive UIS equipment. This cheap test setup achieves comparable defect detection capability while enabling fast testing throughput, effectively replacing the need for costly specialized equipment
Solution Approach 2:
By changing from constant current to constant voltage parameter control, the test system achieves both high reliability in defect detection and high productivity in units per hour, eliminating the trade-off present in conventional UIS equipment
3Temperature
If the die attach test is made first, then the avalanche test can apply less current before maximum junction temperature is reached, but the effectiveness of the avalanche test to detect defects is limited
Solution Approach 1:
The patent performs the avalanche test first before the die attach test, establishing the baseline defect detection under controlled temperature conditions. This preliminary action ensures that defects are identified before thermal effects from the die attach test interfere with avalanche detection effectiveness
Solution Approach 2:
The patent implements separate, sequential test phases where the avalanche test is conducted first under controlled conditions, followed by the die attach test. This periodic separation of test functions allows each test to operate optimally without thermal interference from the other
4Productivity
If the avalanche test is made first, then the device starts the die attach test at elevated junction temperature, but the cooling of the junction temperature from the avalanche test is superimposed on the heating of the die attach test resulting in much lower and less accurate values
Solution Approach 1:
The patent performs the avalanche test first as a preliminary action to identify defects under controlled temperature conditions. By completing this test before the die attach test, the system avoids thermal interference that would compromise measurement precision, while maintaining efficient productivity through sequential testing
5Measurement precision
If other tests are put in between the die attach test and the avalanche test, then thermal interference effects are mitigated, but these tests may cause heating or be influenced by increased junction temperature
Solution Approach 1:
The patent establishes the avalanche test as the preliminary action performed first, before any other tests. This sequencing eliminates the need for intermediate tests to mitigate thermal interference, as the critical defect detection is completed under controlled conditions before subsequent testing begins
Solution Approach 2:
The patent segments the testing process into distinct sequential phases: first the avalanche test for defect detection under controlled temperature, then the die attach test for thermal impedance measurement. This clear segmentation eliminates thermal interference issues without requiring additional intermediate tests, maintaining device simplicity
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 allows for faster and more accurate testing by maintaining a fixed junction temperature, reducing the influence of thermal impedance and enabling the detection of defects without lengthy settling times, thereby improving the efficiency of semiconductor device testing in mass production environments.
Implementation Method 1
The breakdown voltage of a junction comprised by the semiconductor devices is exceeded
Implementation Method 2
The difference between the two measurements is proportional to the increase in junction temperature and that is a measure for the thermal impedance
Data Source
AI summary
A method of testing a semiconductor device, in a package, having a junction between a semiconductor material of a first type and a semiconductor material of a second type. The junction has a temperature dependent breakdown voltage, and the method includes the steps of determining the breakdown voltage, providing a fixed voltage over the junction, via pins of the package, and the fixed voltage is higher than the breakdown voltage, and measuring, via pins of the package, a breakdown current flowing through the junction, determining a dissipated power based on the fixed voltage and the measured breakdown current, and the dissipated power is a qualitive measure for the semiconductor device.