Comparison of surface reactivity of CN, NH, and NH2 radicals during deposition of amorphous carbon nitride films from inductively coupled rf plasmas

The interactions of CN, NH, and NH2 radicals with carbon nitride films during inductively coupled rf plasma deposition were measured using the imaging of radicals interacting with surfaces (IRIS) technique. The surface reactivity R for each species was obtained at various gas compositions of N-2/CH4 and NH3/CH4 and applied rf powers. R values for CN and NH radicals ranged from 0.85 to 1.0 and 0.1 to 0 2, respectively, and show very little dependence on the gas compositions and applied power. In contrast, R values for NH2 decreased from 0.6 +/- 1 to 0.2 +/- 0.1 when the CH4 fraction in the plasma was increased from 0% to 70%. The essentially 100% scatter measured for NH suggests that it does not contribute significantly to film growth in these systems. The effect of ion bombardment on the R values in these systems was analyzed by applying a dc bias to the substrate. In general, R values were found to decrease when a +200 V bias was applied. Results indicate that energetic ions are important in surface production of the species studied with IRIS. The plasmas have also been characterized by mass spectrometry, including the measurements of ion energy distributions. Mechanisms for film deposition in these carbon nitride systems are discussed incorporating the authors' gas-phase and gas-surface interface data. (c) 2007 Amrican Vacuum Society.