Failure Mode of Semiconductor

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3 Failure Mechanism of Semiconductor
Devices

Contents

3.1

Reliability Factor and Failure Mechanism of
Semiconductor Devices

3- 1

3.1.1

Reliability factors

3- 1

3.1.2

Failure factors and mechanisms of
semiconductor devices

3- 4

3.2

Failure Mechanisms of Semiconductor Devices

3- 6

3.2.1

Time dependent dielectric breakdown (TDDB)

3- 6

3.2.2

Slow trap (NBTI)

3- 8

3.2.3

Hot carrier (AHC)

3-10

3.2.4

Soft error

3-12

3.2.5

Reliability problem of nonvolatile memory

3-14

3.2.6

Electromigration (EM)

3-16

3.2.7

Stress migration (SM)

3-20

3.2.8

Reliability of Cu wire

3-23

3.2.9

Al corrosion

3-25

3.2.10

Passivation crack

3-32

3.2.11

Growth of Au/Al compound

3-35

3.2.12

Secondary breakdown

3-36

3.2.13

Thermal fatigue

3-37

3.2.14

Ion migration

3-38

3.2.15

Sn whisker

3-39

3.2.16

Problems in surface mounting
(package cracking)

3.2.17

Electrostatic discharge (ESD)

3-44

3.2.18

i

3-40

Latch-up

3-53

Failure Mechanism of Semiconductor Devices
3.

Failure Mechanism of Semiconductor Devices
Reliability Factor and Failure Mechanism of Semiconductor Devices

3.1

The reliability of semiconductor devices depends on their resistance to stresses applied to the devices, such as electric stress, thermal stress, mechanical stress, and external stress (humidity, etc.). If part of a device has a particularly weak structure, the weak part may react extremely to the applied stress, and such an extreme reaction may cause serious failures.

We design semiconductor devices after thoroughly examining the internal factors that may affect their reliability, so that such internal factors can be ignored under normal use conditions. However, if a device is used under the wrong use conditions, a failure may occur. So, this section describes typical factors of failures for our customers’ reference.

3.1.1

Reliability factors

a) Electric load (overload)
The operation conditions, such as voltage, electric current and electric power, and the combination of these operation conditions with the ambient conditions (device use conditions) greatly affect the life of semiconductor devices.

The electric power may cause a rise of the junction temperature, and the rise of the junction temperature may raise the failure rate. So, the electric current should be lowered as far as possible. The voltage has the same effect as the electric power, as described above. In addition, the voltage may affect the operation of the characteristic compensation circuit. For this reason, if the voltage is extremely low compared with the recommended operation voltage, failures may occur during operation. It is also necessary to carefully handle the surge current that flows when the switch is turned on or off and the surge voltage of inductive (L) load so that they do not exceed the maximum rated values. b) Temperature

It is well known that temperature affects the life of semiconductor products. When a rapid or gradual change occurs to a device, the characteristics of the device may be deteriorated, and finally the device may malfunction. Of course, such changes can be caused by the temperature.

There is much data that proves that Arrhenius’s general formula expressing the chemical reaction rate can be used for calculation of the failure rate of semiconductors. The relation between the life “L” and the temperature “T” (absolute temperature) can be expressed as follows:

Where, A: Constant
Ea: Activation energy (eV)
k: Boltzmann constant (8.6 × 10-5 eV/K)
As shown above, the life will be shortened as the temperature rises. We cannot avoid this physical tendency. When designing equipment, therefore, it is necessary that enough measures against the above tendency are taken by adopting a ventilation device, heat radiation device, or the like. T04007BE-3 2009.4 3-1

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