Nondestructive DCIV method to evaluate plasma charging damage in ultrathin gate oxides

Abstract

Understanding and minimizing plasma charging damage to ultrathin gate oxides become a growing concern during the fabrication of deep submicron MOS devices. Reliable detecting techniques are essential to understand its impact on device reliability. As the gate oxide thickness of MOST's rapidly scales down, the conventional nondestructive methods such as capacitor C-V and threshold voltage and subthreshold swing of MOST's are no longer effective for evaluating this damage in gate oxide. In this paper, the new developed direct-current current-voltage (DCIV) technique is reported as an effective monitor for plasma charging damage in ultrathin oxide. The DCIV measurements for p-MOST's with both 50- and 37-angstrom gate oxides clearly show the plasma charging damage region on the wafers and are consistent with the results of charge-to-breakdown measurements. In comparing with charge-to-breakdown measurement and other conventional methods, the DCIV technique has the advantages of nondestructiveness, high sensitivity and rapid evaluation.