화학공학소재연구정보센터
Thin Solid Films, Vol.519, No.11, 3619-3626, 2011
Effect of ultraviolet curing wavelength on low-k dielectric material properties and plasma damage resistance
A set of SiCOH low dielectric constant films (low-k) has been deposited by plasma enhanced chemical vapor deposition using variable flow rates of the porogen (sacrificial phase) and matrix precursors. During the deposition, two different substrate temperatures and radio frequency power settings were applied. Next, the deposited films were cured by the UV assisted annealing (UV-cure) using two industrial UV light sources: a monochromatic UV source with intensity maximum at gimel = 172 nm (lamp A) and a broadband UV source with intensity spectrum distributed below 200 nm (lamp B). This set of various low-k films has been additionally exposed to NH(3) plasma (used for the CuO(x) reduction during Cu/low-k integration) in order to evaluate the effect of the film preparation conditions on the plasma damage resistance of low-k material. Results show that the choice of the UV-curing light source has significant impact on the chemical composition of the low-k material and modifies the porogen removal efficiency and subsequently the material porosity. The 172 nm photons from lamp A induce greater changes to most of the evaluated properties, particularly causing undesired removal of Si-CH(3) groups and their replacement with Si-H. The softer broadband radiation from lamp B improves the porogen removal efficiency, leaving less porogen residues detected by spectroscopic ellipsometry in UV range. Furthermore, it was found that the degree of bulk hydrophilization (plasma damage) after NH(3) plasma exposure is driven mainly by the film porosity. (C) 2011 Elsevier B.V. All rights reserved.