Selective pulsed chemical vapor deposition of water-free HfOx on Si in preference to SiCOH and passivated SiO2

HfOx was selectively deposited on Si in preference to SiCOH using an oxygen-containing precursor, Hf((OBu)-Bu-t)(4), via a pulsed chemical vapor deposition. The water-free process avoids nucleation by water on passivated oxide surfaces. The uniform HfOx film was deposited on Si by the thermal decomposition of the precursor, and the inherent selectivity of HfOx was retained over SiCOH until similar to 2 nm of HfOx was deposited on Si at 250 degrees C. Additional selectivity enhancement was demonstrated by employing molecular surface passivation and reversible adsorption/desorption of the precursor via control of the purge time. 1,1,3,3-tetramethyldisilazane (TMDS) and Bis(dimethylamino)dimethylsilane (DMADMS) were employed to passivate reactive -OH sites on SiO2 and SiCOH to increase the selectivity to similar to 7 nm HfOx deposition on Si before any significant nucleation occurred on TMDS passivated SiCOH. It is expected that the selective water-free HfOx deposition can be used for patterning nanoscale structures in MOSFET devices.