Electrostatic Discharge Failures of Semiconductor Devices

ESD (Electrostatic Discharge) is a significant cause of device failures at all stages of device and equipment production, assembly, test, installation and field use. Even though device designs include protection circuitry, it is relatively easy to generate static potentials during handling and shipping that exceed the limits of the protection networks. Damage from ESDs can cause either complete device failure by parametric shifts, or device weakness by flocally heating, melting, or otherwise damaging oxides, junctions or device components. There are three principal sources of charge which can give rise to damaging ESD events. 1. A charged person touches a device and discharges the stored charge to or through the device to ground. 2. The device itself acting as one plate of a capacitor can store charge. Upon contact with an effective ground the discharge pulse can create damage. 3. An electrostatic field is always associated with charged objects. Under particular circumstances, a device inserted in this field can have a potential induced across an oxide that creates breakdown. All devices and technologies are susceptible to damaging ESDs. The difference is in their degree of susceptibility. MOS structures appear to be the most susceptible to ESD damage. The generation of charge varies with materials, environment, and conditions of contact. All materials can be charged, however with conductors the charge is readily dissipated by grounding. With insulators, the charge is immobile and not readily dissipated. Two basic measures for avoiding ESD damage and failures are: 1.