Insights into stress-induced degradation of STI-based LDMOSFETs by MR-DCIV spectroscopy

Stress-induced degradation of STI-based LDMOSFETs has been studied by multi-region direct-current current voltage (MR-DCIV) spectroscopy, a new point of view over the traditional CP and I_d-V_g characterization method. The capability of identifying the interface states in LDMOSFETs has been demonstrated by MR-DCIV spectroscopy. The correlation between device degradation and MR-DCIV spectrum has been verified by 2D device simulation. Experimental results and the degradation mechanism for both ON- and OFF-state stresses have been addressed. The role played by the interface state at channel and STI region in LDMOSFETs has been clearly revealed through MR-DCIV spectroscopy. In term of the on-resistance, the OFF-state stress leads to the worst degradation in an STI-based nLDMOS, which is attributed to the interface state generation under STI region.