A proposal of ESD control method with considering semiconductor device charged voltage

Abstract

We considered an advanced Electrostatic discharge (ESD) control method with monitoring device charged voltage to prevent ESD/ Charged Device Model (CDM) failure which is generated despite the ordinary ESD control implemented. That method is to use contact voltage meter. This is very simplified method and effective in the point of resolution. Coulomb meter is also available in the point of sensitivity but its capacitance is seemed to be variable with charging situation, so it is difficult to handle effectively. Even ESD protection area (EPA) is applied in manufacturing site, insufficient charging removal causes ESD failure in test or assembly site. ESD control conditioning with this proposed method by using contact voltmeter is effective to eliminate ESD/CDM failure, in particular, upcoming ESD/CDM sensitive device by advanced technology 22nm or later generation applied. As the result that direct voltage monitoring method for semiconductor test and assembly step as an advanced ESD control was investigated, the following conclusions were obtained. (1) Coulomb meter: Sensitivity is good to apply but an object device capacitance should be realized to set the detail voltage condition. (2) Voltmeter: Sensitivity is good to detect charged portion. Although the size of detector needs to be matched the object one, this is an effective method for charged voltage monitor. (3) Sensitive step for ESD: Test socket, handler and substrate cut process in test and assembly step are concerned portion. In particular, a repeated step raise charged voltage for ESD/CDM breakdown. Most of advanced technology semiconductor device seems to become ESD/CDM sensitive device even if it doesn't have RF or high speed IO. To prevent and reduce failures in production step, ESD control method adaptation with voltage monitoring of object device is effective to do.