Spontaneous etching of B₂O₃ by HF gas studied using infrared spectroscopy, mass spectrometry, and density functional theory

The spontaneous etching of boron oxide (B2O3) by hydrogen fluoride (HF) gas is important during thermal atomic layer after BCl3 converts the surface various metal oxides to a B2O3 layer. In this study, chemical vapor (CVE) HF was experimentally monitored using Fourier transform infrared (FTIR) spectroscopy and quadrupole mass spectrometry (QMS). also analyzed density functional theory (DFT). films were grown deposition with H2O as reactants at 40 °C. FTIR then observed CVE 150 loss absorbance for B–O stretching vibration in films. studies B–F vibrations from BFx species on exposures. addition, QMS analysis able identify etch products main volatile BF3, BF2(OH), H2O. Additional detected including B3O3F3 other boroxine ring compounds. DFT predictions consistent gas. confirmed that likely because energetics reaction B2O3(s) + 6HF(g) → 2BF3(g) 3H2O(g) more favorable than self-limiting 2BF3(s) 3H2O(g). predicted temperatures above −163 °C an reactant pressure 0.2 Torr BF3 product 0.01 Torr.