Diffusion and reaction kinetics governing surface blistering in radio frequency sputtered hydrogenated a-SixGe1-x (0 ≤ x ≤ 1) thin films

Abstract

The preparation of blister free layers of hydrogenated a-Si x Ge 1-x (0≤ x ≤1) is a primary requisite for their technological applications. In RF (Radio Frequency) sputtered layers the formation of blisters is temperature dependent, as also shown here. This dependence is used to propose a theoretical model aimed at a better understanding of the mechanisms determining the blistering.Beside the reaction kinetics responsible for the release of H atoms from SiH and/or GeH complexes the model takes into particular account the contribution of the diffusion of H. The activation energy for blistering also enters in the model. The validation of the theoretical frame of the model is confirmed by the fact that it predicts a blistering threshold temperature in reasonable agreement with the experiment. The amorphous hydrogenated thin layers were deposited on polished silicon by RF co-sputtering. They were annealed between 150 and 350 °C. The

Silicon Nitride and Hydrogenated Silicon Nitride Thin Films: A Review of Fabrication Methods and Applications

“…During annealing, thermal expansion resulted in the increase of the volume of these bubbles, which at a critical point burst caused blister creation on the surface. The creation of blisters with a~100 nm diameter at such a low temperature should be attributed to a similar effect reported by Serényi et al [86] for a-Si:H layers. Due to the hydrogen and/or nitrogen release from the layer, bubbles filled with gases containing hydrogen and/or nitrogen molecules were created on the layer surface.…”

Examination of the Hydrogen Incorporation into Radio Frequency-Sputtered Hydrogenated SiNx Thin Films

“…Similar to the effect reported in Ref. [22], blisters on the layer surface could be burst bubbles filled with hydrogen and/or nitrogen containing molecules. Initially, the volume of these bubbles was increasing due to thermal expansion of the fill-up gas during heat treatment.…”

“…All modeling and calculations were performed using Woollam VASE software (versions of 3.83 and 3.84). The activation energy of the surface modification was determined from the Arrhenius equation using an optical measurement configuration, the details of which are given elsewhere [22]. The 1.6 MeV Rutherford backscattering spectrometry/elastic recoil detection analysis (RBS/ERDA) measurements were performed in a scattering chamber with a two-axis goniometer, which was connected to the 5 MV EG-2R Van de Graaff accelerator operated at the Wigner Research Center of Physics in Budapest, Hungary.…”

“…The arrangement of the measurement described in Ref. [22] enables the determination of onset time of the layer surface change by monitoring the elapsed time and the alteration of the reflectivity of the sample surface.…”