Characterization of Al2O3 Deposition by Ultrasonic Spray Pyrolysis Technique for Non-planar MOS Capacitor

Abstract

This research proposes the characterization of aluminum oxide (Al2O3) deposition by ultrasonic spray pyrolysis (USP) technique for non-planar MOS capacitor We found that the Al2O3 thin film deposited by USPD is very suitable as the dielectric layer of non-planar structure due to the excellent hole-filling and coverage ability In order to analyze the oxide layer composition we utilized the transmission electron microscopy (TEM) atomic force microscopy (AFM) and electron spectroscopy for chemical analysis (ESCA) in this research First from the TEM images we found that the Al2O3 thin film is fully wrapped around the Si channel and the uniformity of Al2O3 is very good Furthermore the deposition rate of Al2O3 deposited by USPD is about 3 5nm per minute The USPD method showed good thickness controllability for dielectric process From AFM images we observed that the surface of Al2O3 deposited by USPD is quite smooth The root mean square (RMS) of USPD case is just 0 75nm Moreover we certified the composition of Al2O3 by ESCA We found that the aluminum/oxygen ratio is about 2 : 3 It indicate the high quality of Al2O3 deposited by USPD After material analysis we executed the capacitance-voltage (C-V) and current-voltage (I-V) electrical characteristics analysis of our devices We calculated the equivalent oxide thickness (EOT) and oxide thickness (t_ox) by capacitance value We found that the calculated t_ox is quite similar to the oxide thickness measured from TEM Then we calculated the gate current density of our devices and compared to others dielectric layer process The tendency of extrapolation line of USPD case shows good gate leakage immunity in small EOT Therefore the ultrasonic spray pyrolysis technique is suitable for the dielectric layer of non-planar structure

Date of Award	2015 Jul 28
Original language	English
Supervisor	Wei-Chou Hsu (Supervisor)