Low-temperature growth of wafer-scale amorphous boron nitride films with low-dielectric-constant and controllable thicknesses.

Abstract

Amorphous boron nitride (aBN) films, with extremely low relative dielectric constant (κ) and chemical inertness, are excellent insulation and packaging materials for electronic device interconnection. It is of great significance to prepare the low-κaBN films with controllable thickness, but there are still some limitations to achieve the goal. In this study, we succeed in growing wafer-scale aBN films with specific thicknesses from 1.2 to 4.0 nm by varying the growth time and temperature. The thickness of the films increases linearly with growth time and the crystallinity of BN films is precisely controlled by the growth temperature. The preferred temperature for aBN films ranges from 200°C to 400°C. Raman spectroscopy, x-ray photoelectron spectroscopy and transmission electron microscope all confirm the amorphous feature. These films are wafer-scale uniformity and have an ultra-flat surface, with excellent thermal stability and corrosion resistance. Particularly, the growth temperature affects theκvalue and breakdown voltage of aBN films. The aBN films grown at 200°C have the lowestκvalue of 1.66 at 100 kHz, along with the breakdown field strength of 5.5 MV cm^-1. We believe that wafer-level aBN films with various thicknesses can bring new opportunities for the development and application of nanoscale electrical devices.