Reduction of Hot Carrier Effects in Corning Silicon-on-Glass TFTs

Abstract

Hot carrier (HC) instability of thin film transistors (TFTs) fabricated on single crystalline Corning® Silicon-on-Glass (SiOG) substrates is studied (1). The n- and p-channel TFT transfer characteristics typically exhibit excellent on-state performance with electron and hole field effect mobilities (μfe) of ~251 and 201 cm2/V⋅s, threshold voltages of ~-0.3 and -1.2 V, and gate swing (S) values of ~180 mV/dec. While p-channel TFTs exhibit good stability, on-current (ION) degradation is unfortunately observed in the transfer characteristics of the n-channel TFT due to HC stress. In this study, the integration of a lightly doped drain (LDD) structure to minimize HC instability in the n-channel SiOG TFTs is reported. The LDD design has 2 μm regions produced by ion implanting phosphorus at 10 keV to a light doping (n-) level. N- levels of ~1 × 1013, 2 × 1013, and 3 × 1013 cm−2 are analyzed to determine the optimum doping conditions that leads to HC improvement with minimal detrimental impact to the on-state device performance.