Semiconductor reliability testing and test sockets
KLD Tech takes you to learn about semiconductor chip reliability testing and chip test sockets
1. Acceleration testing
The life of most semiconductor devices can exceed many years under normal use. But we can't wait until several years later to study the device; we need to increase the applied stress. The applied stress can enhance or accelerate the potential failure mechanism, help find the root cause, and help TI take measures to prevent the failure mode.
In semiconductor devices, some common acceleration factors are temperature, humidity, voltage, and current. In most cases, accelerated testing does not change the physical characteristics of the failure, but shifts the observation time. The transfer between accelerated conditions and normal use conditions is called "derating". Highly accelerated testing is a key part of JEDEC qualification testing. The following tests reflect highly accelerated conditions based on JEDEC specification JESD47. If the product passes these tests, it means that the device can be used in most usage situations.
According to the JESD22-A104 standard, temperature cycling (TC) subjects the parts to changes between extreme high and low temperatures. This test is performed by repeatedly exposing the part to these conditions for a predetermined number of cycles.
1.1. Temperature Cycling
1.2. High Temperature Operating Life (HTOL)
HTOL is used to determine device reliability under high temperature operating conditions. This test is usually performed for an extended period of time per JESD22-A108.
1.3. Temperature Humidity Bias (THB)/Bias Highly Accelerated Stress Test (BHAST)
Per JESD22-A110, THB and BHAST subject the device to high temperature and humidity conditions while under bias with the goal of accelerating corrosion of the device. THB and BHAST serve the same purpose, but the BHAST conditions and test process allow the reliability team to test much faster than THB.
1.4. Hot Press/Unbiased HAST
Hot Press and Unbiased HAST is used to determine device reliability under high temperature and humidity conditions. Like THB and BHAST, it is used to accelerate corrosion. Unlike these tests, no bias is applied to the part.
1.5. High-temperature storage
HTS (also called "baking" or HTSL) is used to determine the long-term reliability of devices at high temperatures. Unlike HTOL, the devices are not under operating conditions during testing.
2. Electrostatic discharge (ESD)
Electrostatic charge is an unbalanced charge at rest. Typically, it is generated by the friction or separation of insulator surfaces against each other; one surface gains electrons while the other loses electrons. The result is an unbalanced charged condition, also known as static charge.
When static charge moves from one surface to another, it becomes electrostatic discharge (ESD) and moves between the two surfaces in the form of miniature lightning.
When static charge moves, it forms a current, which can damage or destroy gate oxides, metal layers, and contacts.
JEDEC tests ESD in two ways:
1) Human body model (HBM)
A component-level stress that simulates the behavior of the human body discharging the accumulated static charge through the device to ground.
2) Charged Device Model (CDM)
A component-level stress that simulates charging and discharging events in production equipment and processes according to the JEDEC JESD22-C101 specification.
