Low-Damage Damascene Patterning Using Porous Inorganic Low-Dielectric-Constant Materials

Abstract

The degradation of porous low-dielectric-constant (low- k ) materials, such as porous methyl silsesquioxane (MSQ) and porous chemical-vapor-deposited SiOCH films, by damascene etch and ash processes has been investigated. The influence of etch damage becomes relatively stronger as ash damage improves. The etch damage to porous low- k dielectric is found particularly at the sidewall of the isolated lines. By investigating the influence of etch conditions on the damage, it is found that O 2 and Ar addition causes large sidewall damage. O 2 -added etch condition, as well as the O 2 ash process, produces oxygen radicals, which extract CH 3 groups from porous low- k films. On the other hand, Ar plasma does not efficiently extract CH 3 groups differently from O 2 plasma, but it changes the bonding states of CH 3 groups and causes H 2 O adsorption. This change in film characteristics increases dielectric constant. Finally, we successfully achieved low-damage dual damascene patterning using a porous SiOCH material whose dielectric constant is 2.2.