Influence of Atomic Layer Deposition Temperatures on TiO2/n-Si MOS Capacitor

This paper reports on the influence of deposition temperature on the structure, composition, and electrical properties of TiO2 thin films deposited on n-type silicon (100) by plasma-assisted atomic layer deposition (PA-ALD). TiO2 layers similar to 20 nm thick, deposited at temperatures ranging from 100 to 300 degrees C, were investigated. Samples deposited at 200 degrees C and 250 degrees C had the most uniform coverage as determined by atomic force microscopy. The average carbon concentration throughout the oxide layer and at the TiO2/Si interface was lowest at 200 degrees C. Metal oxide semiconductor capacitors (MOSCAPs) were fabricated, and profiled by capacitance-voltage techniques. The sample prepared at 200 degrees C had negligible hysteresis (from a capacitance-voltage plot) and the lowest interface trap density (as extracted using the conductance method). Current-voltage measurements were carried out with top-to-bottom structures. At -2 V gate bias voltage, the smallest leakage current was 1.22 x 10(-5) A/cm(2) for the 100 degrees C deposited sample. (C) 2013 The Electrochemical Society.