A comparative study on the Si precursors for the atomic layer deposition of silicon nitride thin films

Abstract

Silicon nitride thin films were deposited by the atomic layer deposition (ALD) technique in a batch-type reactor by alternating exposures of a Si precursor and NH 3. SiCl 4 and SiH 2Cl 2 were examined as the Si precursor, and the properties of the deposited films were comparatively characterized. The ALD by using SiH 2Cl 2 exhibited larger deposition rates at lower precursor exposures as compared with the ALD by using SiCl 4, and the deposited films from SiH 2Cl 2 had lower wet etch rates in a diluted HF solution. Silicon nitride films with a Si : N ratio of approximately 1 : 1 were prepared by using either Si precursor at 500 °C; however, the films deposited by using SiH 2Cl 2 had higher H concentrations. Silicon nitride films deposited by ALD showed physical properties comparable with those of the silicon nitride films deposited by low-pressure chemical vapor deposition, lowering the deposition temperature by more than 200 °C.