High-Temperature Dielectric Behavior of Nanocrystalline and Microcrystalline Diamond Thin Films

Abstract

This paper presents high-temperature electrical properties of polycrystalline, microcrystalline and nanocrystalline diamond films synthesized with varying proportions of nitrogen and argon in the gas phase. Resistivity data, activation energies, barrier heights, dielectric constants and quality factors are reported for these films up to 823 K. Results indicate that high N2 (0.5 %) and Ar (85 %) levels in the gas phase degrade the electrical quality of the diamond films. This degradation is attributed to a combined effect of decreasing grain size and higher sp2 carbon content in the films. A gas ratio of 60:39:1 of Ar:H2:CH4 was found to produce improved dielectric quality with resistivities comparable to those of typical microcrystalline diamond films. A proprietary seeding technique which produced a dense diamond nucleation layer is also presented. This research resulted in the development of process conditions for diamond deposition on device substrates that incurred no observable damage to device metallization.