Low-k protection from F radicals and VUV photons by multilayer pore grafting approachстатья
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Дата последнего поиска статьи во внешних источниках: 10 августа 2018 г.
Аннотация:Polymer grafting is studied in porous low-k SiCOH films as a protection against plasma damage. Pores of low-k films were covered by plasma damage management (PDM) polymer. A multistep deposition approach was applied to increase polymer layer thickness that helped avoid pore stuffing, nonuniform deposition and polymer overburden. To study polymer protection low-k films were exposed to F radicals and VUV photons, separately and simultaneously at temperatures from -45C to +10C. Effective polymer protection at room temperatures was demonstrated. Lowering the temperature decreases degradation by F radicals while VUV damage, which is temperature independent, becomes dominant. Low-k damage protection was also significant under simultaneous exposure to F radicals and VUV photons. In the tested temperature range damage under simultaneous exposure to F radicals and VUV photons was higher than the sum of separate F and VUV damages due to a synergistic effect. To decrease the material k-value after etching the polymer was removed from the pore walls using UV cure. It is shown that almost complete polymer removal was achieved after UV treatment. The described approach was applied to low-k etching in RF CCP CF4, CF4/Ar plasmas and exposure to Ar plasma. Significant improvement of the film k-value after the plasma treatment was confirmed.