Photon-induced formation of silicon oxide thin films / Jaya Sharma.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Sharma, Jaya.

Contributor:

Dai, Hai-Lung, advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Chemistry.

Chemistry--Penn dissertations.

Local Subjects:

Penn dissertations--Chemistry.

Chemistry--Penn dissertations.

Physical Description:

xvii, 174 pages : illustrations ; 29 cm

Production:

2000.

Summary:

Silicon oxide thin films are widely used in numerous technologies such as microelectronics, coatings, and food packaging. The conventional techniques to deposit silicon oxide thin films have drawbacks such as high temperature, unsuitable for planarization, and unstable precursors. In this thesis, it is shown that uv photons can be used to induce conversion of spin-coated thin films of beta-chloroethyl silsesquioxane (beta-cesq) on a substrate to silicon oxide. This method not only overcomes the above mentioned drawbacks, but has the added advantage of spatially selective deposition. The photo-induced oxide is found to be superior to the thermally induced oxide regarding the impurity concentration of carbon.

A variety of techniques are utilized in investigating the mechanism of the photochemical conversion of beta-cesq to silicon oxide: Infra-red, UV absorption spectroscopy, Ellipsometry, Rutherford backscattering spectrometry, Atomic force microscopy, Mass spectrometry, and Time-of-flight mass spectrometry. The photo-induced conversion is initiated by the direct excitation of the RSiO chromophore of the beta-cesq molecules, resulting in the breaking of the Si-C bond. The primary photo-fragment was found to be ethyl chloride radical, while ethylene and vinyl chloride were determined to be secondary photo-fragments. The majority of the secondary photo-fragments are formed deep inside the thin film, due to further reactions of primary photo-fragments as they diffuse out of the film. A diffusion-reaction model was proposed to explain the observations of: one reaction rate for thin film (400 A) while two for thick films (2000 A) in the thickness measurements versus integrated fluence; different time behavior of different photofragments as a function of integrated fluence; and the difference in the time-of-flight signal (arrival time and decay constant) for various masses for thin and thick films. It was also found that a source of oxygen is crucial to the photochemical and thermally-induced conversion of beta-cesq to silicon oxide.

This study of a novel photochemical method for the deposition of silicon oxide thin films reveals some important aspects of solid state photo-chemistry in thin films: the importance of environment and the diffusion of small molecules and photo-fragments through the solid matrix.

Notes:

Supervisor: Hai-Lung Dai.

Thesis (Ph.D. in Chemistry) -- University of Pennsylvania, 2000.

Includes bibliographical references and index.

Local Notes:

University Microfilms order no.: 9989652.

OCLC:

244971404