AVS 46th International Symposium
    Electronic Materials and Processing Division Wednesday Sessions
       Session EM-WeP

Paper EM-WeP4
Growth of Ultra Thin Oxides of Silicon by Wet Oxidation Technique: Effect of Water Vapor Pressure

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: B. Viswanath Krishna, Indian Institute of Technology, India
Authors: A. Subrahmanyam, Indian Institute of Technology, India
B. Viswanath Krishna, Indian Institute of Technology, India
K.N. Bhat, Indian Institute of Technology, India
Correspondent: Click to Email
The rapid scaling down of silicon device dimensions has renewed interest in ultra thin oxides. The desirable properties of ultra thin oxides for gate dielectric applications are: very low defect densities, low charge trapping characteristics and high break down voltages. Although the ultra thin oxides grown by wet oxidation technique have higher breakdown strengths compared to that of dry oxide, the wet oxide has invariably large trapping characteristics and has problems in uniformity and surface roughness. In the present investigation, the effect of water vapor pressure (0.004 - 1.0 atm) on the ultra thin oxides of silicon grown by wet oxidation technique has been attempted. The wet oxidation is carried out in a quartz furnace maintained at 800@super o@C for 5 - 120 minutes. The ultra thin oxides are grown on single crystal CZ silicon wafers : n-type, (100) oriented, single side polished, of resistivity 1.0 - 10 @ohm@cm. The thickness of the grown oxides(3- 10 nm) has been estimated from the measured C-V characteristics and are also confirmed by ellipsometer measurements. The thickness of the oxide (60 minutes) seems to be rather independent at water vapor pressures till 0.05 atm. In order to understand the electrical performance of these thin oxides, Al/thin SiO@sub 2@ / n-Si MOS structures are fabricated and their Capacitance (C ) - Voltage (V) (in the frequency range : 10 KHz - 1 MHz), conductance (G) - voltage (V) and Current (I) - Voltage (V) characteristics have been studied. Interface density (D@sub it@) and fixed oxide charge density (Q@sub f@) have been evaluated to asses the quality of the thin oxide layer. The breakdown voltage and the charge trapping characteristics have also been studied. The results indicate that reproducible ultra thin oxides can be grown with sufficient control by wet oxidation technique at reduced water vapor pressure.