Low-k organosilicate films are considered essential for meeting the material needs of interconnect dielectric layers in present and future semiconductor devices. These materials, whether deposited by chemical vapor deposition or spin-on processes, are mechanically inferior as compared to undoped silicate glass or fluorine doped silicate glass. The introduction of porosity to further lower the dielectric constant diminishes the mechanical properties even more. For this reason, post-porosity treatments such as E-beam and UV curing have been explored. In this paper, we describe the use of laser spike annealing ͑LSA͒ to achieve similar results. Infrared analysis coupled with Rutherford backscattering, forward recoil, and X-ray photoelectron spectroscopy were used to study the effect of varying laser power and dwell time on the structural changes of both a dense and porous organosilicate, indicating removal of hydrogen and some carbon from the samples. These changes were interpreted in terms of oxidative and bond redistribution transformations. As a result of the structural changes, significant increases in Young's modulus were achieved. Properties such as k, refractive index, film shrinkage, and water contact angle were also correlated with laser power and dwell time. LSA compares favorably with both E-beam and UV curing and three times improvements in modulus without significantly affecting k were observed.
ZrO2films deposited on silicon (100) substrates using pulsed-pressure metalorganic chemical vapor deposition (PP-MOCVD) with zirconium n-propoxide (ZnP) Zr(OC3H7)4were dense and fully crystalline for substrate temperatures of 500 to 700 °C. Film thicknesses were 40 to 815 nm thick, measured after growth using ellipsometry and scanning electron microscopy (SEM). The growth rate was between 0.1 μm/h at 500 °C and 1 μm/h at 700 °C. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) indicated an average grain size of 10 to 20 nm. There was a random orientation of cubic/tetragonal zirconia at the highest experimental temperature of 700 °C. SEM and atomic force microscopy (AFM) was used to characterize island height of discontinuous films in the initial stages of growth where defects in the substrate caused preferred nucleation of isolated particles. At later stages of growth, the average surface roughness of continuous films was 30 nm, which revealed a more uniform growth had developed. A growth model is proposed, and optimal growth conditions are suggested for targeted microstructures of ZrO2films.
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