Nonthermal combined ultraviolet and vacuum-ultraviolet curing process for organosilicate dielectrics

Abstract

Porous SiCOH films are of great interest in semiconductor fabrication due to their low-dielectric constant properties. Post-deposition treatments using ultraviolet (UV) light on organosilicate thin films are required to decompose labile pore generators (porogens) and to ensure optimum network formation to improve the electrical and mechanical properties of low-k dielectrics. The goal of this work is to choose the best vacuum-ultraviolet photon energy in conjunction with vacuum ultraviolet (VUV) photons without the need for heating the dielectric to identify those wavelengths that will have the most beneficial effect on improving the dielectric properties and minimizing damage. VUV irradiation between 8.3 and 8.9 eV was found to increase the hardness and elastic modulus of low-k dielectrics at room temperature. Combined with UV exposures of 6.2 eV, it was found that this "UV/VUV curing" process is improved compared with current UV curing. We show that UV/VUV curing can overcome drawbacks of UV curing and improve the properties of dielectrics more efficiently without the need for high-temperature heating of the dielectric.

Impact of VUV photons on SiO2 and organosilicate low-k dielectrics: General behavior, practical applications, and atomic models

“…76,77 Recently a room temperature curing with consequent treatment by UV (6.2 eV) and VUV (8.8 eV) photons has been proposed. 78 However, although substantial improvement of mechanical properties was demonstrated in the last work, the chemical composition of the cured low-k films was not analyzed.…”

“…63 eV. 78 Porogen was removed during the first step while the second step provided the matrix crosslinkage. It was shown that this method allows improvement of dielectric properties.…”