Electrical and Computer Engineering ETDs

Publication Date

4-21-1978

Abstract

Semiconductor memory elements have been fabricated on silicon utilizing reactively evaporated TiO2 as the charge storage insulator medium. The dielectric and charge storage properties of TiO2 films have been characterized as a function of TiO2 deposition conditions and post-deposition heat-treatment. Experimental results indicate a strong dependence of the film properties on fabrication process parameter such as oxygen pressure during deposition, substrate temperature, and post-deposition heat-treatment temperature and time. Data taken on the test devices show that both dielectric constant and charge storage properties are enhanced by reactive evaporation of TiO2 in an oxygen ambient and substrate heating during evaporation. Post-deposition annealing in an oxygen ambient is also shown to increase the dielectric constant of the TiO2 films. Longer annealing has been found, however, to affect adversely the switching property of the device due to silicon oxide growth underneath the TiO2 films. A simple diffusion-limited oxide growth model is proposed to explain the silicon oxide growth during the post-deposition heat-treatment. Measurements on the switching properties of fabricated TiO2 devices were taken on the Metal-TiO2-SiO2-Si structure in terms of write/erase voltage pulse width and amplitude. Devices with a 1000 Å layer of TiO2 typically exhibit 5 volt memory windows for a ±15 volt write/erase pulse.

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Wayne Willis Grannemann

Second Committee Member

Harold Dean Southward

Third Committee Member

Roy Arthur Colclaser

Fourth Committee Member

William D. Brown

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