Hot-Wire Generated Atomic Hydrogen and its Impact on Thermal ALD in TiCl4/NH3 System

Abstract

We present the generation of atomic hydrogen made by the dissociation of molecular hydrogen upon collision with a tungsten (W) filament kept at a high temperature (T ≈ 1600–1900°C). We demonstrate the ability to create atomic hydrogen and to introduce it in short pulses in experiments on etching of tellurium (Te) films. We further utilize the generated atomic hydrogen (H) to explore its impact on surface reactions in the TiCl4/NH3 precursor system. Atomic hydrogen is introduced in pulses additionally to TiCl4 and NH3 with different pulse sequences. For the TiCl4/NH3/H sequence, there is no influence on the process compared to the ALD without H-pulses. The growth rate remains at 0.02 nm/cycle and the oxygen (residual gas) content - at 3–5 at%. For the TiCl4/H/NH3 pulse sequence, the growth rate decreases to 0.01 nm/cycle and the oxygen content increases to 30–35 at%. Only TiCl4/H pulses result in no growth after the formation of approximately one monolayer. Similar effect occurs after introducing NH3 via the hot filament, pointing to the decomposition of NH3 and the formation of atomic hydrogen.