Abstract
The perpendicularly orientated lamellar structure of the self-organized diblock copolymer is an attractive template for sub-10-nm line-and-space pattern formation. We propose a method of evaluating the neutral layer (NL) whose performance has an important bearing on the perpendicular orientation of the lamellar structure. The random copolymer of methyl methacrylate and i-butyl POSS methacrylate (MAIBPOSS) has been investigated as an NL for a polymethylmethacrylate-b-polymethacrylethylPOSS (PMMA-b-PMAIBPOSS) lamellar structure. PMMA-b-PMAIBPOSS material has the potential to form sub-10 nm line-and-space pattern, in addition to high etch selectivity due to its POSS structure. Under the free surface, PMMA-b-PMAIBPOSS film on the random copolymer layer showed horizontal orientation. However, a half-pitch of a 7-nm finger pattern structure was observed by peeling off the horizontally oriented layer. The upper portion of the PMMA-b-PMAIBPOSS film was eliminated till proximity of the random copolymer layer by CF4 gas etching. From the result, it was revealed that the PMMA-r-PMAIBPOSS works as an NL. It was confirmed that the contact angle analysis using an appropriate polymer is a suitable method for evaluation of the surface energy performance of the copolymer with the attribute of high segregation energy.
Highlights
Directed self-assembly (DSA) lithography, which combines self-assembling materials and lithographically defined prepatterns, is a candidate to extend optical/EUV lithography beyond sub-10 nm.[1,2] DSA of block copolymer (BCP) films on chemically or topologically patterned substrates is an attractive patterning technique that combines the ability of BCPs to self-assemble into nanoscale features with the use of lithographic tools.[3,4,5,6,7] One of the important problems concerning practical application of DSA lithography is a “defect” problem
The contact angle of the PMMA dot was measured by AFM. 3 Results and Discussion 3.1 Performance of Si-Containing BCP Materials PS-PMMA has been investigated for application of fine lineand-space pattern formation
PMMA is high for an organic BCP material, and the relatively low segregation energy enables perpendicular orientation of lamellar structure in a normal ambience without any special atmosphere or top coat.[9,15]
Summary
Directed self-assembly (DSA) lithography, which combines self-assembling materials and lithographically defined prepatterns, is a candidate to extend optical/EUV lithography beyond sub-10 nm.[1,2] DSA of block copolymer (BCP) films on chemically or topologically patterned substrates is an attractive patterning technique that combines the ability of BCPs to self-assemble into nanoscale features with the use of lithographic tools.[3,4,5,6,7] One of the important problems concerning practical application of DSA lithography is a “defect” problem. The typical defect densities remain orders of magnitude away from the target concentration of 0.01 defects∕cm[2] proposed by the International Technology Roadmap for Semiconductors.[8] it is crucially important to minimize defect levels and maximize DSA lithography process margin by carefully designing lithographically defined prepatterns and precisely adjusting process conditions. Applying polystyrene-polymethylmethacrylate (PS-b-PMMA) diblock copolymer in a full-pitch size of around 25 nm, such a defect investigation has been reported.[9] On the other hand, the domain size of self-organization is basically determined by the Flory–Huggins χ parameter and the polymerization index.[10,11] To realize sub-10 nm feature size patterns, a higher χ parameter diblock copolymer is required. Polystyrene-b-poly 2-vinylpyridine and polystyrene-b-polydimethylsiloxane are well known as high χ materials with a potential for
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