An efficient method for characterizing time-evolutional interfacestate and its correlation with the device degradation in LDD n-MOSFETs

A new characterization method is proposed to study the relationship between the hot-carrier-induced interface state N_it (x) and the device drain current degradation of submicron LDD n-MOSFETs. In this method, by making use of the conventional charge pumping measurement in combination with the power-law dependence of interface damages on stress time, the spatial distribution N_it(x) and the effective damaged length L_dam can be easily extracted. The time evolution of the interface state generation and its correlation with the device degradation can then be well explained. It is worthwhile to note that this newly developed method requires no repetitive charge pumping measurements, and hence avoids he likely imposition of re-stress on tested devices. By combining the characterized L_dam and N_it quantitatively, the results show that the damage at L_dam and V_GS≈V _DS/2 is most highly localized among various stress biases, which can explain why the generated interface states will dominate the device drain current degradation at this bias after long-term operating conditions