Plasma Charging Damage Affecting Flash Memory Device Encountered at Pad Etch

Abstract

This paper is to present plasma charging damage affecting 0.18 micron flash memory product. The affected product encountered high voltage N-MOS transistor current leakage. Correlation analysis pointed towards the passivation / pad etch step. Engineering splits were performed to isolate and understand the root cause. Several factors were suspected contributing to the current leakage. These factors are categorized by recipe, consumable kit and product technology (process flow). Further splits were performed with the consumable kits divided into three groups; quartz group, anodized aluminum group and the gas distribution plate group. The focus of this paper is to highlight the combined impact of high power radio frequency (RF) from process recipe with equipment consumable parts intrinsic defect affecting flash memory device causing plasma charging damage. This paper also investigates the effectiveness of electrical test rework procedure utilizing ultraviolet (UV) erase.