Date of Award

2000

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering

First Advisor

Gil S. Lee

Abstract

The reduction of RC time delay is critical in high speed and ultra density submicron devices. One of the ways to reduce RC time delay is to use fluorinated silicon oxide (SiOF) film as an intermetal dielectric material and Cu as an interconnect metal. In this study, the chemical and electrical properties of the SiOF films prepared by plasma enhanced chemical vapor deposition were studied, then the optimized film was integrated with Cu using Ta as a diffusion barrier. The deposition of the SiOF films was made by incorporating CF4 as the fluorine source into the deposition process of SiO2 films using Si2H6 and N2O as the silicon and oxygen precursors, respectively. The SiOF film deposited at 180°C by flowing 40 sccm of Si2H 6 (5% in He), 100 sccm of N2O and 30 sccm of CF4 with 700 mTorr of chamber pressure and 50 W of rf power showed that the relative dielectric constant decreased to 3.5 due to the incorporation of fluorine. Further study showed that the addition of Ar into the deposition process of SiOF film improved the stability of the film with producing lower relative dielectric constant of 3.4. Then, Ta was sputtered on the optimized film with a relative dielectric constant of 3.4, followed by Cu sputtering. To investigate thermal stability, the films were annealed in the temperature range of 300--800°C for 1 hr in N2 ambient. The results of four-point probe, x-ray diffraction (XRD), and capacitance voltage (C-V) and current voltage (I-V) measurements suggest the structure of Cu/Ta/SiOF film is thermally stable up to 700°C.

ISBN

9780599853270

Pages

97

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