Guided self-assembly of Si-containing block copolymer with a topcoat surface treatment

Directed self-assembly (DSA) of block copolymers (BCPs) is one of candidate for next generation patterning technique. Many good demonstrations of DSA have been reported using polystyrene-block-poly(methyl methacrylate) (PS-b- PMMA) these days. On the other hands, BCPs which show high chi parameter are being developed because the BCPs can be formed smaller features than PS-b-PMMA. Si-containing BCPs are one of them. Moreover Si-containing BCPs show higher etch selectivity than PS-b-PMMA because of higher etch resistance of Si-containing block. Unfortunately, while Si-containing BCPs can be aligned by solvent annealing, they but cannot be aligned perpendicular to the substrate by thermal annealing. Because Si-containing block which has low surface energy achieves maximum interaction with air interface by forming a top parallel wetting layer to the substrate. One solution to control of surface energy on top surface is the use of Top-Coat (TC). It has been already demonstrated that TC with Si-containing BCP could form perpendicular pattern. The challenges are TC coating onto BCP film and TC stripping after annealing. In order to solve these problems, polarity-changeable type TC has been developed. The effect of TC materials to generate finger print of BCP has been reported. However, this TC process should combine with DSA process to form aligned patterns. Graphoepitaxy is one of the DSA technique to align BCP pattern using guide pattern. In this technique, the characteristic of guide pattern side wall is very important to control BCP pattern alignment for the Graphoepitaxy process. Also, in order to establish the process, there are two key parameters for the materials. One is BCP and guide pattern should have enough resistance to TC solvent through TC coating process. The other is TC can be removed easily with basic aqueous solution before BCP patterning. In this report, a detail of examination for TC Graphoepitaxy process will be discussed.