Atomic layer controlled growth of Si3N4 films using sequential surface reactions

Si3N4 thin films were deposited with atomic layer control on Si(100) substr ates using sequential surface chemical reactions. The Si3N4 film growth was accomplished by separating the binary reaction 3SiCl(4)+4NH(3)Si(3)N(4)+12 HCl into two half-reactions. Successive application of the SiCl4 and NH3 ha lf-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 stud ies indicated that the SiC4 and NH3 half-reactions were complete and self-l imiting at substrate temperatures greater than or equal to 700 K. In situ s pectroscopic ellipsometry monitored the Si3N4 him growth versus substrate t emperature and reactant exposure time. The maximum Si3N4 deposition rate pe r AB cycle was 2.45 Angstrom per AB cycle at 700 K for reactant exposures > 10(10) L. The Si3N4 deposition rate decreased slightly in the temperature range 700-900 K. Rutherford backscattering measurements revealed an Si/N ra tio of 1:1.35 as expected for stoichiometric Si3N4 deposition. The surface topography of the Si3N4 films measured with atomic force microscopy (AFM) w as nearly identical to the initial Si(100) substrate indicating extremely s mooth and conformal Si3N4 deposition. (C) 1998 Elsevier Science B.V. All ri ghts reserved.