Superior hot carrier reliability of single halo (SH) silicon-on-insulator (SOI) nMOSFET in analog applications

Abstract

In this paper, for the first time, we report a study on the hot carrier reliability performance of single halo (SH) thin film silicon-on-insulator (SOI) nMOSFETs for analog and mixed-signal applications. The SH structure has a high pocket impurity concentration near the source end of the channel and low impurity concentration in the rest of the channel. Besides excellent dc output characteristics and experimental characterization results on these devices show better V/sub th/-L roll-off, low DIBL, higher breakdown voltages, and kink-free operation. Further SH SOI MOSFETs have been shown to exhibit reduced parasitic bipolar junction transistor effect in comparison to the homogeneously doped channel (conventional) SOI MOSFETs. Small-signal characterization on these devices shows higher ac transconductance, higher output resistance, and better dynamic intrinsic gain (g/sub m/R/sub o/) in comparison with the conventional homogeneously doped SOI MOSFETs. Also, the low drain junction capacitance as a result of low impurity concentration near the drain region is beneficial for improved circuit performance. The experimental results show that SH SOI MOSFETs exhibit a lower hot carrier degradation in small-signal transconductance and dynamic output resistance in comparison with conventional homogeneously doped SOI MOSFETs. From 2-D device simulations, the lower hot carrier degradation mechanism in SH SOI MOSFETs is analyzed and compared with the conventional SOI MOSFETs.