Reliability testing of semiconductor equipment in high-temperature and high-humidity environments

Semiconductor equipment is prone to reliability issues due to material aging and electrochemical migration in high-temperature and high-humidity environments. Testing simulates harsh conditions and utilizes accelerated models to evaluate performance changes, revealing potential failure modes. Common tests include high-temperature and high-humidity storage, highly accelerated stress testing, etc., which require the use of constant temperature and humidity chambers to monitor electrical performance and physical changes. The test results help improve materials and processes, enhancing the long-term reliability of products.

Overview

In the process of semiconductor manufacturing and packaging, equipment and components are often exposed to harsh environmental conditions. High temperature and high humidity environments can accelerate material aging, cause electrochemical migration, lead to insulation performance degradation and metal corrosion, and directly affect the long-term reliability and service life of semiconductor equipment. Therefore, simulating and evaluating the performance changes of equipment under high temperature and humidity conditions is a key part of ensuring its quality and reliability. This test aims to reveal potential failure modes through controlled environmental stresses, providing data support for material selection, process improvement, and product design.

Test Principle:

The high temperature and humidity test is mainly based on the Arrhenius equation and the Peck model, which describe the accelerated effects of temperature and humidity on the failure time. High temperature will increase the rate of molecular motion and accelerate chemical reactions; High humidity promotes water vapor adsorption and penetration, and combines with pollutants to form electrolyte, triggering electrochemical migration or corrosion. Common failure mechanisms include corrosion of metal wires, solder joint degradation, delamination of packaging materials, drop in insulation resistance, and drift of device parameters. Testing accelerates these failure processes through constant or cyclic temperature and humidity conditions, thereby evaluating the long-term reliability of products in a shorter period of time.

The correlation acceleration model can be expressed as:

AF = (RH_test/RH_use)^-n × exp[(E_a/k) × (1/T_use - 1/T_test)]

where AF is the acceleration factor, RH is relative humidity, E_a is the activation energy, k is the Boltzmann constant, T is the absolute temperature, and n is the humidity index.

Test Standards

High temperature and high humidity testing in the semiconductor industry often refers to international and domestic standards, such as JEDEC, IEC and GB standards. The test conditions need to be set according to the application scenario of the equipment, and common tests include high temperature and high humidity storage (such as 85°C/85% RH), high acceleration stress test (HAST), and temperature and humidity bias (THB) test. Testing can range from tens to thousands of hours, depending on reliability goals and acceleration levels. During the test, the stability of environmental parameters should be monitored to ensure consistency in stress application.

Test type	Typical conditions
High temperature and high humidity storage	85°C, 85% RH
High acceleration stress test	110°C-130°C, 85% RH
Temperature and humidity bias test	85°C, 85% RH, powered bias
Cyclic damp-heat test	Periodic changes in temperature and humidity

Test equipment

Environmental test chambers are used for high temperature and humidity testing, which should be able to accurately control temperature and humidity, and have good uniformity and stability. Auxiliary instruments may include: parametric analyzers to monitor changes in electrical properties, microscopes to observe physical defects, insulation resistance testers to evaluate insulation properties, and surface analysis equipment such as scanning electron microscopes for failure analysis. The instrument needs to be calibrated regularly to ensure accurate and reliable data.

Device type	Key features:
Constant temperature and humidity test chamber	Provide a stable high temperature and high humidity environment
Parameter analyzer	Measure the electrical parameters of the device
Insulation resistance tester	Evaluate insulation properties
Microscopic observation system	Check for physical structural changes

Evaluation methodology

The testing process typically includes: sample preparation and initial testing, test condition setting, environmental stress application, intermediate testing, and final testing. Samples should represent actual production batches and may be pre-treated. During the test, samples should be taken out regularly for electrical performance, physical appearance and function checks. The evaluation indicators include: failure time, parameter drift, failure ratio, etc. Through statistical analysis, the life or failure rate of the product under normal use can be estimated. Failure analysis is an important part of identifying the root cause of failure, distinguishing between material, design, or process issues.

Conclusion

Reliability testing in high temperature and high humidity environments is an important means of quality assurance of semiconductor equipment. Through scientific test design, strict implementation and in-depth analysis, potential defects can be effectively identified and product improvement can be guided. As semiconductor technology evolves, test methods need to adapt to the needs of new materials and structures to continuously improve the reliability of equipment.

References

JEDEC JESD22-A101, Steady-State Temperature Humidity Bias Life Test.

IEC 60068-2-78, Environmental testing - Part 2-78: Tests - Test Cab: Damp heat, steady state.

Peck, D. S., & Zierdt, C. H. (1974). The reliability of semiconductor devices in the presence of humidity.