What are the general reliability tests for semiconductor testing basics?

Date：2022-05-30 14:20:05Views：1336

Accelerated testing

The lifetime of most semiconductor devices can exceed many years under normal use. But we can't wait a few years to study devices; We must increase the applied stress. The applied stresses can enhance or accelerate potential failure mechanisms, help identify root causes, and help take action to prevent failure modes.

In semiconductor devices, some common acceleration factors are temperature, humidity, voltage and current. In most cases, the accelerated test does not change the physical characteristics of the fault, but will change the observation time. The change between acceleration conditions and normal use conditions is called "derating".

Highly accelerated testing is a key part of JEDEC based qualification testing. The following tests reflect the high acceleration conditions based on JEDEC specification jep47. If the product passes these tests, it means that the device can be used in most use cases.

Temperature cycle

According to jed22-a104 standard, the temperature cycle (TC) makes the components undergo the conversion between extreme high temperature and low temperature. During this test, the component is repeatedly exposed to these conditions for a predetermined number of cycles.

High temperature service life (HTOL)

HTOL is used to determine device reliability under high temperature operating conditions. This test is usually conducted for a long time according to jesd22-a108 standard.

Temperature humidity bias high accelerated stress test (bhast)

According to jesd22-a110 standard, THB and bhast allow devices to withstand high temperature and high humidity conditions while under bias voltage. Their goal is to accelerate the corrosion of devices. THB and bhast are used for the same purpose, but the bhast conditions and test process make the reliability team test much faster than THB.

Autoclave / unbiased hast

The autoclave and unbiased hasts are used to determine device reliability under high temperature and humidity conditions. Like THB and bhast, it is used to accelerate corrosion. However, unlike these tests, no bias is applied to the component.

High temperature storage

HTS (also known as "bake" or htsl) is used to determine the long-term reliability of devices at high temperatures. Unlike HTOL, the device is not under operating conditions during the test.

Electrostatic discharge (ESD)

Static charge is the non-equilibrium charge at rest. Generally, it is caused by the friction or separation of insulator surfaces; One surface gains electrons while the other loses electrons. The result is an unbalanced electrical condition called static charge.

When electrostatic charge moves from one surface to another, it becomes electrostatic discharge (ESD) and moves between the two surfaces in the form of micro lightning.

When the static charge moves, a current is formed, which can damage or destroy the gate oxide, metal layer and junction.

JEDEC tests ESD in two ways:

1. human discharge model (HBM)

A component level stress used to simulate the behavior of the human body releasing the accumulated static charge to the ground through devices.

2. charged device model (CDM)

A component level stress that simulates charging and discharging events in production equipment and processes according to JEDEC jesd22-c101 specification.