Abstract

Thin-film transistors (TFTs) with channel materials made out of hydrogenated amorphous silicon (a-Si:H) and polycrystalline silicon (poly-Si) have been extensively investigated. Amorphous silicon continues to dominate the large-format display technology; however newer technologies demand a higher performance TFT which a-Si:H cannot deliver due to its low electron mobility, µn ~ 1 cm2/V*s. Metal-oxide materials such as Indium-Gallium-Zinc Oxide (IGZO) have demonstrated semiconductor properties, and are candidates to replace a Si:H for TFT backplane technologies.

This work involves the fabrication and characterization of TFTs utilizing a-IGZO deposited by RF sputtering. An overview of the process details and results from recently fabricated IGZO TFTs following designed experiments are presented, followed by analysis of electrical results. The investigated process variables were the thickness of the IGZO channel material, passivation layer material, and annealing conditions. The use of electron-beam deposited Aluminum oxide (alumina or Al2O3) as back-channel passivation material resulted in improved device stability; however ID VG transfer characteristics revealed the influence of back-channel interface traps.

Results indicate that an interaction effect between the annealing condition (time/temperature) and the IGZO thickness on the electrical behavior of alumina-passivated devices may be significant. A device model implementing fixed charge and donor-like interface traps that are consistent with oxygen vacancies (OV) resulted in a reasonable match to measured characteristics. Modified annealing conditions have resulted in a reduction of back-channel interface traps, with levels comparable to devices fabricated without the addition of passivation material.

Library of Congress Subject Headings

Thin film transistors--Materials; Integrated circuits--Passivation

Publication Date

12-18-2014

Document Type

Thesis

Student Type

Graduate

Degree Name

Microelectronic Engineering (MS)

Department, Program, or Center

Microelectronic Engineering (KGCOE)

Advisor

Karl Hirschman

Advisor/Committee Member

Michael Jackson

Advisor/Committee Member

Sean Rommel

Comments

Physical copy available from RIT's Wallace Library at TK7871.96.T45 W35 2014

Campus

RIT – Main Campus

Plan Codes

MCEE-MS

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