Atomic layer controlled growth of Si3N4 films using sequential surface reactions

Abstract

Si3N4 thin films were deposited with atomic layer control on Si(100) substrates using sequential surface chemical reactions. The Si3N4 film growth was accomplished by separating the binary reaction 3SiCl4+4NH3→Si3N4 + 12HCl into two half-reactions. Successive application of the SiCl4 and NH3 half-reactions in an ABAB... sequence produced Si3N4 deposition at substrate temperatures between 500 and 900 K and SiCl4 and NH3 reactant pressures of 1-10 Torr. Transmission Fourier transform infrared (FTIR) spectroscopy studies indicated that the SiC4 and NH3 half-reactions were complete and self-limiting at substrate temperatures ≥ 700 K. In situ spectroscopic ellipsometry monitored the Si3N4 film growth versus substrate temperature and reactant exposure time. The maximum Si3N4 deposition rate per AB cycle was 2.45 Å per AB cycle at 700 K for reactant exposures > 1010 L. The Si3N4 deposition rate decreased slightly in the temperature range 700-900 K. Rutherford backscattering measurements revealed an Si/N ratio of 1:1.35 as expected for stoichiometric Si3N4 deposition. The surface topography of the Si3N4 films measured with atomic force microscopy (AFM) was nearly identical to the initial Si(100) substrate indicating extremely smooth and conformal Si3N4 deposition. Show more