Effects of ESD on Devices-CSDN博客

ESD can happen anywhere from the initial fabrication of the device, through packaging and board assembly, during operation, to field service of systems. When devices are handled or processed without proper ESD controls and proper ESD protection severe irreversible effects can occur.

1 Device Damage
When an electronic device is subjected to an ESD event, a very short pulse of electrical current
passes through the device. This current causes the device to heat rapidly in and near the path of
current flow. If the local temperature of the materials conducting this current exceeds the melting
point, or some other important characteristic temperature of the material, the device will be
permanently altered or “damaged”. This physical damage can typically only be “seen” by
disassembling the device and then through the aid of very high magnification and often other
sophisticated instrumentation. Another form of failure is dielectric breakdown (e.g., gate oxide). In
modern deep sub-micron processes, gate oxide damages are possibly more common in practical
applications (e.g., testing, assembly).
2 Device Failure
The most serious consequence of physical damage is that the device, in most cases, will lose its
ability to perform its intended function with its expected reliability. In many cases this loss of function will be catastrophic. That is, there will be an immediately detectable loss of function and the device will fail one or more of its characteristics as described in the device specification or data sheet. The good news of catastrophic failure is that it can be detected in production test and the manufacturer can avoid shipping a defective part to the customer. In other cases, there may be an immediate shift of one or more parameters that are still within the data sheet limits. These could, in principle,also be detected by production test programs but may not be screened out. This can lead to one type of “latent” failure.
3 Latent Defects
A device that is exposed to an ESD event may be partially degraded yet continue to perform its
intended function. If this degradation is not detected by testing or if it is within specified parametriclimits set for the device, it will still be shipped to the customer. In some cases, this degradation may lead to a significant reduction in the useful operating life time of the device. A product or systemincorporating devices with these latent defects may experience a premature failure after the user places them in service. Such failures can be costly to repair and in some applications may create personnel hazards. Establishing that a device has failed due to a latent defect is difficult, if not impossible in many cases. For this reason, the extent of latent failures due to ESD is a controversialtopic.