The adsorption and desorption of halogen and other gaseous species from surfaces is a key fundamental process for both wet chemical and dry plasma etch and clean processes utilized in nanoelectronic fabrication processes. Therefore, to increase the fundamental understanding of these processes with regard to aluminum nitride (AlN) surfaces, temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) have been utilized to investigate the desorption kinetics of water (H2O), fluorine (F2), hydrogen (H2), hydrogen fluoride (HF), and other related species from aluminum nitride thin film surfaces treated with an aqueous solution of buffered hydrogen fluoride (BHF) diluted in methanol (CH3OH). Pre-TPD XPS measurements of the CH3OH:BHF treated AlN surfaces showed the presence of a variety of Al-F, N-F, Al-O, Al-OH, C-H, and C-O surfaces species in addition to Al-N bonding from the AlN thin film. The primary species observed desorbing from these same surfaces during TPD measurements included H 2, H2O, HF, F2, and CH3OH with some evidence for nitrogen (N2) and ammonia (NH3) desorption as well. For H2O, two desorption peaks with second order kinetics were observed at 195 and 460°C with activation energies (Ed) of 51±3 and 87±5kJ/mol, respectively. Desorption of HF similarly exhibited second order kinetics with a peak temperature of 475°C and E d of 110±5kJ/mol. The TPD spectra for F2 exhibited two peaks at 485 and 585°C with second order kinetics and Ed of 62±3 and 270±10kJ/mol, respectively. These values are in excellent agreement with previous Ed measurements for desorption of H 2O from SiO2 and AlFx from AlN surfaces, respectively. The F2 desorption is therefore attributed to fragmentation of AlFx species in the mass spectrometer ionizer. H2 desorption exhibited an additional high temperature peak at 910°C with Ed=370±10kJ/mol that is consistent with both the dehydrogenation of surface AlOH species and H2 assisted sublimation of AlN. Similarly, N2 exhibited a similar higher temperature desorption peak with Ed=535±40kJ/mol that is consistent with the activation energy for direct sublimation of AlN.
|Original language||English (US)|
|Journal||Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films|
|State||Published - Sep 2014|
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films