Hot-carrier-induced degradation in deep submicron Unibond and SIMOX MOSFETs

Abstract

SOI devices are greatly competitive for the ULSI era due to significantly improved electrical properties compared with bulk devices. However, when the gate length is shortened in the deep submicron range, SOI MOSFETs also suffer from severe hot-carrier-induced degradations. Especially, for fully depleted (FD) thin film SOI devices, stressing the front channel may also damage the back channel, and the threshold voltage (Vt) shift may be affected by the charges trapped in the opposite oxide owing to the interface-coupling effect. It has been reported that the back interface of FD P-channel SIMOX transistor degrades much more than the front interface, due to the poor electrical properties of the back buried oxide. A new SOI material technology Smart-cut has been recently developed for the fabrication of Unibond wafers. A good uniformity of silicon layer without any defects and a very sharp bonded interface have been obtained from this technology. Therefore, the aim of this paper is to present a thorough comparison on hot-carrier-induced degradation in deep submicron thin Unibond and SIMOX MOSFETs.