The study of leakage current performance improvement in high voltage technology

The PECVD silicon oxy-nitride film has been widely used as antireflective coating (ARC) and contact etch stop layer (CESL) in IC fabrication. It is typically deposited using SiH4&N2O gas mixtures at temperatures around 400°C, with film properties such as reflective index, wet etch rate, stress and uniformity controlled by varying gas flows, RF powers, temperature and pressures. In addition, the ion bombardment plays a predominant role in controlling the film characteristics, which will influence the electrical properties of device and the yield. The article majorly focuses on the correlation between leakage current performance of high voltage device and the film quality of silicon oxy-nitride, which characterizes as CESL. In this work, a model of leakage current, which caused by the property of CESL oxy-nitride film, has been presented. The higher Si-H bond consisted CESL leads the charge behavior between source and drain, which causes leakage current on Vg <; Vt. By reducing the mixture ration of SiH4/N2O to decrease Si-H bond content of silicon oxy-nitride film, a significant yield improvement in HV device is obtained.