| AVS 54th International Symposium | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS1+TF-TuM |
| Session: | Plasma Enhanced Atomic Layer Deposition and Plasma Deposition |
| Presenter: | M.T. Seman, Colorado School of Mines |
| Authors: | M.T. Seman, Colorado School of Mines S. Agarwal, Colorado School of Mines J.J. Robbins, CMD Research, LLC C.A. Wolden, Colorado School of Mines |
| Correspondent: | Click to Email |
In this presentation we describe how conventional plasma-enhanced chemical vapor deposition (PECVD) may be engineered to deliver self-limiting deposition of metal oxides using pulsed power modulation. Self-limiting growth is assured when no deposition occurs during continuous operation with either the plasma on or the plasma off. The requirements that must be met to achieve this behavior are described. The pulsed PECVD technique has the potential to combine the digital control over thickness and composition provided by atomic layer deposition with the high throughput and low temperature capability offered by PECVD. To date the process has been demonstrated for both tantalum1 and aluminum oxides,2 and in this paper we focus on the process-property relationships in the former system. Tantalum oxide films were deposited by pulsed PECVD using continuous delivery of oxygen and penta-ethoxy tantalum (PET, Ta(OC2H5)5) in a capacitively-coupled reactor. Deposited films were characterized by spectroscopic ellipsometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and dielectric performance. The deposition rate per pulse may be readily adjusted over a broad range (1- 10 Å/pulse) using variables such as the PET concentration and the plasma off time. With these variables fixed digital control over film thickness is demonstrated. The process is insensitive to substrate temperature, with a constant deposition rate observed from 90 to 350 °C. Films contain impurities due to carbon and hydroxyl groups, however these signals attenuate as the rate is reduced and are not detectable by FTIR for rates < 3 Å/pulse. Films deposited under these conditions at 190 ºC displayed a high dielectric constant (κ ~ 25) while maintaining leakage current densities below 1 μA/cm2 out to a field strength of 1 MV/cm.
1 M. Seman, J. J. Robbins, S. Agarwal, and C. A. Wolden, Appl. Phys. Lett. 90, 131504 (2007).
2 S. Szymanski, M. T. Seman, and C. A. Wolden, Surf. Coat. Technol. in press (2007).