Correlation between hot carrier stress, oxide breakdown and gate leakage current for monitoring plasma processing induced damage on gate oxide

In this paper, we compare the hot carrier (HC) stress and oxide breakdown results with the fast and commonly used gate leakage current measurement. A clear correlation is found between low levels of gate leakage and both HC degradation and oxide breakdown. We, for the first time, demonstrate that the value of the gate leakage current is not only a failure indicator but also a good indicator of the reliability of the devices. A new testing method was developed to reveal latent as well as actual plasma damage, for a wide range of gate oxide quality in a very fast way. The gate oxide was stressed to break down using a ramping voltage. Moreover, oxide time-to-breakdown (t_bd) was measured with constant voltage stress. These two testing methods have been compared.