Self‐consistent field theory investigation of directed self‐assembly in cylindrical confinement

Abstract

We use self‐consistent field theory to study the self‐assembly of cylinder‐forming diblock copolymers confined in a cylindrical prepattern. This situation arises in contact holes—the hole shrink problem—where the goal is to produce a cylindrical hole with reduced dimensions relative to a guiding prepattern. In this study, we focus on systems with a critical prepattern dimension ranging from 50 nm to 100 nm that consequently lead to the formation of a single cylinder in the middle of the hole. We find that a variety of defect morphologies arise from the self‐assembly process and are strongly governed by the prepattern dimensions, wetting conditions as well as the polymer molecular weight. We also consider blends of diblock copolymers and homopolymers and determine optimal blending configurations that not only favor the formation of the desired cylindrical morphology but also extend the processing window relative to the pure diblock case. When defective structures form inside the prepattern, we compute their formation energy and use the string method to examine the kinetic pathways for the transition from the defective state to the perfect cylindrical state. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 142–153

Field-Theoretic Simulations of Multi-Cylinder Configurations in VIA Lithography

“…The directed self-assembly (DSA) of block copolymers in particular has been shown in numerous experimental and numerical studies to provide a robust strategy for creating a variety of useful line and space patterns with low defectivity [1][2][3][4][5][6][7] . In the context of VIA lithography, DSA of PS-PMMA in cylindrical confinement has been successfully implemented to produce PMMA VIA cylinders with a reduced critical dimension (CD) relative to a guiding prepattern [8][9][10][11] . Beyond hole shrink, interest in DSA also lies in contact multiplication by producing several cylinders at desired locations within a single guiding templates.…”

Physical design and mask optimization for directed self-assembly lithography (DSAL)

“…scanner focus, exposure energy, and mask manufacturing error) are varied [3]; the result is a set of litho images. Each litho image is then submitted to a DSA simulator [4], which outputs an expected shape of a contact (or contacts), called DSA image. Each contact, in the end, is associated with multiple DSA images as shown in Fig.…”

The Hole Shrink Problem: Self-Consistent Field Theory for Directed Self-Assembly of Miktoarm Copolymers

“…The major CD and minor CD range from H 88 nm to H 102 nm and from H 51 nm to H 66 nm, respectively. The optimized CD of cylindrical confinement for the block copolymer is H 58 nm [9]. The natural periodicity, L 0 , of the block copolymer is H 32 nm, which is determined by a bulk SCFT calculation of the copolymer.…”

“…To achieve low defectivity and wide process windows with PS-b-PMMA, blended systems have been considered [9], while the architecture of the block copolymer has received little attention.…”

“…In order to implement DSA in a contact hole application, cylindrical confinement for hole shrink has been studied both experimentally [8] and theoretically [9,10] and is relatively well understood. In contrast, more intense research for contact hole multiplication [11,12] is required to investigate defectivity, process windows, contact hole geometry and properties, etc.…”