Area-Selective Low-Pressure Thermal Atomic Layer Deposition of Aluminum Nitride

Abstract

This work demonstrates intrinsic area-selective deposition of AlN films by thermal atomic layer deposition (ALD). Using sequential pulses of trimethylaluminum and NH 3 at a substrate temperature of 623 K, polycrystalline AlN was selectively formed on a thin layer of sputtered AlN that was patterned on thermal SiO 2 grown on Si substrates. A pretreatment to remove native AlO x N y facilitated the selective growth of ALD-AlN. Transmission electron microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and atomic force microscopy examined the interfaces and layer thickness. As reported in this article, the deposition of AlN exhibits intrinsic selectivity, a trait that can be exploited to grow other III-nitrides selectively, such as GaN.

Thermal atomic layer deposition of aluminum oxide, nitride, and oxynitride: A mechanistic investigation

“…Specifically, the ALD of Al nitride using AlCl 3 and ammonia (NH 3 ) requires temperatures above 600 ○ C because NH 3 does not react with AlCl 3 at lower temperatures. 21 The deposition temperature can be substantially reduced if AlCl 3 is replaced with TMA. The reaction between NH 3 and the adsorption products of TMA to produce Al nitride starts at 300 ○ C. 22 However, TMA undergoes substantial decomposition on different substrates (Si, SiO 2 , etc.)…”