Pore Seal Property of Ultra-thin Layer for Porous Low-<i>k</i> Films revealed by Ellipsometric Porosimetry

<jats:title>ABSTRACT</jats:title><jats:p>It was found for the first time that the control of the size of pore sealant is important to prevent diffusions of pore sealant into pores of porous low-<jats:italic>k</jats:italic> films and to achieve a good toluene seal property. Two pore sealants (PS-A, B) were prepared and the seal property and porous structure were studied using toluene based ellipsometric porosimetry (EP) measurements. It was revealed that small pore sealant (PS-B) diffuses into pores of porous low-<jats:italic>k</jats:italic> (PLK) films and did not show any seal property, while large pore sealant (PS-A) does not diffuse into pores of porous low-k films and shows a good toluene seal property. Ellipsometry shows that PS-A forms conformal layer only on the vicinity of surface of porous low-k films, but porous structure of porous low-<jats:italic>k</jats:italic> films at the bottom part is kept, according the fact that the refractive index did not increase.</jats:p><jats:p>Furthermore, we developed a new pore seal material (PS-C) to form ultra-thin conformal layer by a single pass, which shows a good toluene seal property. The dielectric constant increased from 2.10 to 2.25 by covering with PS-C. The obtained layer also shows the effect as the protect layer of porous low-<jats:italic>k</jats:italic> films from plasma damages.</jats:p>