Silicon-Containing Resist Underlayer Film for Hardmask

The patent introduces a resist underlayer film as an intermediary layer between the photoresist and the hardmask. This underlayer film is specifically designed to be selectively removed by dry etching while leaving the photoresist intact. The underlayer film contains silicon-containing compounds with specific functional groups that enable selective etching, allowing the hardmask to be removed without damaging the photoresist layer above it.

The patent segments the underlayer structure into multiple functional layers: the photoresist layer for patterning, the resist underlayer film for selective removal, and the hardmask layer for etching protection. This segmentation allows each layer to perform its specific function independently, with the underlayer film serving as a sacrificial layer that can be selectively removed to expose the hardmask pattern without affecting the photoresist.

The patent modifies the chemical parameters of the silane compounds by introducing specific functional groups (cyclic diester groups, epoxide groups, or carboxyl groups) into the molecular structure. These parameter changes in the chemical composition enable the underlayer film to achieve both adequate dry etching rates and resistance to intermixing with the photoresist, while still maintaining film formation capability.

The patent uses composite silane compounds that combine silicon-containing structures with specific organic functional groups (cyclic diester, epoxide, or carboxyl groups). This composite material approach allows the underlayer film to exhibit multiple properties simultaneously: adhesion to the substrate, resistance to intermixing with photoresist, and appropriate dry etching rate, which cannot be achieved with simple silane compounds alone.