Effect of boron on gate oxide degradation and reliability in PMOS devices

Abstract

Modern CMOS technology widely utilizes dual poly gate technology to create surface channel PMOS devices with low threshold voltage. The paper presents analysis of degradation and gate oxide reliability in 50 Å oxide p+-poly PMOS transistors. The post boron implant anneal temperature is used to vary amount of boron penetration into the oxide. Results indicate significant role of boron in reduction of the gate oxide lifetime of PMOS devices and enhanced electron trapping in the oxide. The degradation correlates with the threshold voltage variation due to channel doping change. No effect of the boron penetration on stress-induced leakage current was observed. The results are discussed in terms of boron-related oxide defects and deteriorated interface of boron-doped polysilicon.