Reliability projection and polarity dependence of TDDB for ultra thin CVD HfO/sub 2/ gate dielectrics

Abstract

A systematic study of long-term reliability of ultra thin CVD HfO/sub 2/ gate stack (EOT=10.5 /spl Aring/) with TaN gate electrode is presented. The polarity and area dependence and temperature acceleration of time-to-breakdown (TBO), defect generation rate, and critical defect density are studied. It is found that T/sub BD/ is polarity-independent (T/sub BD,-Vg/=T/sub BD,+Vg/). TDDB lifetime acceleration shows that 10-year lifetime of HfO/sub 2/ gate stack is projected at Vg=1.63 V for EOT=8.6 /spl Aring/ and Vg=1.88 V for EOT=10.6 /spl Aring/ at 25/spl deg/C. However, after temperature acceleration of 150/spl deg/C, area scaling to 0.1 cm/sup 2/, and the projection to low percentage failure rate of 0.01%, the maximum operating voltages are projected to be Vg=0.6 V for EOT 8.6 /spl Aring/ and Vg=0.75 V for EOT=10.6 /spl Aring/.