AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS+TF-ThM

Paper PS+TF-ThM12
Morphological Variation of Plasma Polymerized TiOxCy Films as a Function of Oxygen Concentration during PECVD

Thursday, October 21, 2010, 11:40 am, Room Galisteo

Session: Plasma Deposition and Plasma Enhanced ALD
Presenter: L. Sun, General Dynamics Information Technology
Authors: L. Sun, General Dynamics Information Technology
H. Jiang, General Dynamics Information Technology
J. Grant, University of Dayton Research Institute
P. Lloyd, UES, Inc.
T. Bunning, Air Force Research Laboratory
R. Jakubiak, Air Force Research Laboratory
Correspondent: Click to Email
Amorphous titanium oxide derivative films have relatively high index of refraction compared to purely organic thin films, retain much of the functionality of their crystalline counterparts and can be deposited at low temperature. Using PECVD operated at room temperature and in a remote configuration, plasma-polymerized (PP-) TiOxCyNz films were derived from titanium (IV) isopropoxide using a mixture of argon and nitrogen as carrier gases. Upon exposure to ambient, the PP-TiOxCyNz films undergo a continual decrease in film thickness and increased index of refraction that does not stabilize for several days after deposition. After one hour in air, the thickness of the films rapidly decreased by 14% and after three weeks the thickness decreased 30% (128 - 90 nm). This was accompanied by an increase of the refractive index from n589 = 1.72 to 1.84. Broadly, the densification results from oxidation of low valence titanium moieties prevalent in films formed in an oxygen-poor environment. From AFM and SEM studies we know that the thin films possess a featureless, smooth (RMS - 0.5 nm) one phase 3-D crosslinking amorphous structure. When oxygen was substituted for nitrogen as a carrier gas, most of the titanium atoms retained the Ti4+ state of the monomer and little, if any densification was noted; however, the film morphology was strongly dependent on the argon to oxygen ratio in the carrier gas mixture. In oxygen rich conditions, the films contained granular columns (approximately 10 to 50 nm in diameter) composed of amorphous TiO2, with void and crack defects between 10-20 nm in width. Films deposited in oxygen poor conditions exhibited a uniform, amorphous structure as seen in the nitrogen/argon case.