Porous underlayer coating and underlayer coating forming composition for forming porous underlayer coating
There is provided an underlayer coating causing no intermixing with photoresist layer and having a high dry etching rate compared with photoresist, which is used in lithography process of manufacture of semiconductor device. Concretely, it is an underlayer coating forming composition for forming a porous underlayer coating for use in manufacture of semiconductor device, comprising a blowing agent, an organic material and a solvent, or a polymer having a blowing group and a solvent. The underlayer coating formed from the composition has porous structure which has pores therein, and makes possible to attain a high dry etching rate.
1. An underlayer coating forming composition for forming a porous underlayer coating occupied by pores of 5 to 80% at a rate of volume for use in the manufacture of a semiconductor device, comprising a blowing agent, an organic material and a solvent, wherein a proportion of the blowing agent in solid content of the composition is 2 to 30 mass %, and wherein the blowing agent is selected from the group consisting of 4,4-oxybisbenzene sulfonyl hydrazide and azodicarbonamide.
2. The underlayer coating forming composition according to claim 1 , wherein the blowing agent is a blowing agent that is decomposed with heat to generate nitrogen, carbon dioxide or water vapor.
3. The underlayer coating forming composition according to claim 1 , wherein the organic material is an organic material containing at least one component selected from the group consisting of a polymer, a crosslinking compound and a light absorbing compound.
4. The underlayer coating forming composition according to claim 3 , wherein the polymer is a polymer having at least one aromatic ring structure selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring and a triazine ring.
5. The underlayer coating forming composition according to claim 3 , wherein the crosslinking compound is a compound having at least two crosslink forming substituents.
6. The underlayer coating forming composition according to claim 3 , wherein the light absorbing compound is a compound having at least one ring structure selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring and a triazine trione ring.
7. A method for forming a photoresist pattern for use in the manufacture of a semiconductor device, comprising:
forming a porous underlayer coating occupied by pores of 5 to 80% at a rate of volume by applying the underlayer coating forming composition according to claim 1 on a semiconductor substrate and heating it;
forming a photoresist layer on the porous underlayer coating;
exposing the semiconductor substrate covered with the porous underlayer coating and the photoresist to light;
developing the photoresist alter the exposure to light; and
removing the porous underlayer coating corresponding to a part of developed and removed photoresist by etching.