What are the reliability tests in chip development?

Date：2023-02-16 17:08:24Views：823

The chip development process includes specification formulation, detailed design, HDL coding, simulation verification, logic synthesis, STA, formal verification, layout planning, wiring, CTS, parasitic parameter extraction, layout physical verification and other steps. For semiconductor enterprises, reliability test is an important means to improve product quality. This article has collected and collated some materials, hoping to be of great reference value to all readers.

During the reliability verification of industrial products, HTGB, H3TRB, TC, HTRB, AC/PCT and IOL tests are the main items to verify the reliability of devices:

HTGB (high temperature gate bias test)

High temperature gate bias test is the most important experimental project for silicon carbide MOS tubes. Applying voltage to the gate for a long time under high temperature environment will accelerate the performance aging of the gate, and if the gate of MOSFET bears positive voltage or negative voltage for a long time, the threshold value VGSth of the gate will drift.

H3TRB (high pressure, high temperature and high humidity reverse bias test)

There is only H3TRB in AEC-Q101. Its disadvantage is that the back pressure is too low, only 100V. It is mainly an accelerated test for failure under high temperature and high voltage environment. The high humidity environment is a great test to the packaging resin material of discrete devices and the passivation layer on the surface of the chip. The resin material can not block the water vapor and can only rely on the passivation layer. The application of three kinds of stress makes the early defects more easily exposed;

TC (temperature cycle test)

Binding wires, welding materials and resin materials are subject to aging and failure risks due to thermal stress. The temperature cycling test puts the tested object into the temperature box, and the temperature is cycled between - 55 ℃ and 150 ℃ (level H). This process is to apply heating stress on the packaging material, and evaluate the interface integrity of various materials inside the device under the effect of thermal expansion and cold contraction; This project standard is very strict for silicon carbide power modules, especially for modules applied to automobiles.

HTRB

HTRB is the most important test item for the reliability of discrete devices. Its purpose is to expose defects related to time and stress. These defects are usually removable ions in the passivation layer or temperature-driven impurities. Semiconductor devices are highly sensitive to impurities. Impurities may be introduced in the manufacturing process. Impurities will accelerate or diffuse under the action of strong electric field, and eventually the impurities will diffuse into the semiconductor to cause failure. After the passivation layer on the same wafer surface is damaged, impurities may migrate to the interior of the wafer and cause failure.

HTRB test can accelerate the appearance of these failures and find out abnormal devices. When 80% back pressure is applied to semiconductor devices in 150 ℃ ambient temperature box, leakage will occur. If the leakage parameters do not exceed the bottom line of the specification within 1000 hours and remain stable without change, it means that the device design and packaging combination meet the standard.

AC/PCT (high temperature cooking test)

High temperature cooking test is to put the tested object into the environment of high temperature, high humidity and high pressure to test the excellent degree of the passivation layer of the wafer and the performance of the resin material. The tested object is in a condensation and high humidity atmosphere, and the air pressure in the environment is high, and the moisture can enter the package interior, which may cause defects such as delamination and metallization corrosion.

IOL

Intermittent working life test is a kind of power cycle test. Place the tested object in the normal temperature environment Ta=25 ℃, apply current to make its own heating junction temperature rise, and make Tj ≥ 100 ℃, wait for its natural cooling to the ambient temperature, and then apply current to make its junction temperature rise, and keep cycling. This test can make the bonding surface of different substances of the tested object produce stress, and can find defects such as the fracture of the bonding surface between the binding line and the aluminum layer, the interface delamination between the chip surface and the resin material, and the interface delamination between the binding line and the resin material. For modules with many materials and many contact surfaces between materials, it is difficult to pass this project.

Each of the above reliability tests corresponds to a certain failure mode, which can be summarized into five categories: environmental test, life test, screening test, field use test, and identification test. It is based on different environmental conditions, test items, test purposes, and test properties, and different classification of test methods.

The purpose of reliability test is to find various defects in the design, material, process and other aspects of the product. After analysis and improvement, the reliability of the product will be gradually increased and finally reach the predetermined reliability level; Provide information to improve the combat readiness of products, improve the mission success rate and reduce maintenance costs; Confirm whether the specified reliability quantitative requirements are met. So today's content will be shared here. If you feel that the content is helpful to you, please pay attention to Chuangxin Testing. We will provide you with more industry information!