Effect of device type and plasma process on the oxide thickness dependence of plasma-induced charging damage

The electrical stress which the thin gate oxide of MOS transistors may undergo during gate charging in a plasma processing environment can introduce undesirable oxide damage. This damage can be either critical, i.e. irreversible oxide breakdown, or latent, i.e. showing itself as deteriorated oxide reliability and stability. Plasma process-induced charging damage has been extensively studied in numerous papers investigating its physical nature, relation to plasma parameters, or its effect on device reliability. As device scaling continues, the concern about plasma damage increases, since device shrinkage enhances antenna ratios for charge collection, and the decreasing gate oxide thickness reduces the voltage range at which tunneling currents may damage the gate insulator. This paper addresses the plasma damage sensitivity of CMOS devices with oxide thickness in the 40-90 Å range. The device yield of plasma sensitive antenna devices is studied with respect to oxide thickness, device type, and the plasma process under which damage occurs. In addition to device yield, latent damage in intermediate antenna structures is studied as a function of oxide thickness and device type