The desorption kinetics of molecular hydrogen (H<inf>2</inf>) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H<inf>2</inf> desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH<inf>2/3</inf>), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150°C), while predominantly monohydride species were observed after higher temperature exposure (450°C). The ratio of surface versus subsurface H<inf>2</inf> desorption was also found to be dependent on the substrate temperature with 150°C remote hydrogen plasma exposure generally leading to more H<inf>2</inf> evolved from subsurface states and 450°C exposure leading to more H<inf>2</inf> desorption from surface SiH<inf>x</inf> species. Additional surface desorption states were observed, which were attributed to H<inf>2</inf> desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H<inf>2</inf> desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.
|Original language||English (US)|
|Journal||Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films|
|State||Published - Sep 1 2015|
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films