EFFECT OF PLASMA POLY-ETCH ON EFFECTIVE CHANNEL-LENGTH AND HOT-CARRIER RELIABILITY IN SUBMICRON TRANSISTORS

The effective channel length (L(eff)) variation resulting from exposure to the plasma during the poly-etch step was investigated. The plasma induced charging effect was also studied using gate polysilicon antenna structures. It was found that, due to the poly etching, the L(eff) variation has a larger impact on the fully processed transistor transconductance characteristics than the charging effect in the gate oxide region. It is believed that the damage in the LDD region, which gives rise to the L(eff) variation, imposes a serious hot carrier reliability problem.