Master Mold for Patterned Magnetic Disks via Block Copolymer Self-Assembly
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Solution Overview
Problem
The challenge lies in creating a master mold capable of achieving high areal bit density and a bit aspect ratio (BAR) greater than 1 for patterned-media magnetic recording disks, which is difficult with the resolution limitations of electron beam (e-beam) lithography.
Innovation Solution
A method involving conventional or e-beam lithography to form radial stripes on a substrate, followed by guided self-assembly of block copolymers to multiply these stripes into radial lines, and subsequent formation of concentric rings to define the island dimensions, resulting in a master mold with a higher BAR, enabling the production of patterned-media disks with ultra-high areal density and higher BAR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If e-beam lithography is used to create master mold patterns, then manufacturing precision can be achieved, but productivity is limited due to resolution constraints and lengthy fabrication processes
Solution Approach 1:
The fabrication process is segmented into distinct stages: forming radial stripes, depositing block copolymer, annealing to self-assemble, and etching concentric rings. This segmentation allows each stage to be optimized independently, improving overall productivity while maintaining precision through the self-organizing nature of block copolymer phase separation.
Solution Approach 2:
Radial stripes are formed in advance as a template before block copolymer deposition. This preliminary patterning establishes the radial orientation and spacing that guides subsequent self-assembly, enabling high-density circumferential features to be generated automatically through the phase separation process rather than direct lithography.
2Productivity
If conventional lithography is used to form patterns, then productivity is improved, but manufacturing precision deteriorates due to inability to achieve high BAR patterns
Solution Approach 1:
Block copolymer serves as an intermediary material that translates conventional lithography patterns (radial stripes) into high-precision nanoscale features (radial lines with high circumferential density). The self-assembling block copolymer amplifies the pattern density while maintaining geometric fidelity, acting as a mediator between low-resolution lithography and high-resolution final patterns.
Solution Approach 2:
The method changes the physical and chemical parameters of the patterning system by introducing block copolymer materials with specific phase separation characteristics. By controlling annealing temperature and copolymer composition, the system transforms conventional lithography patterns into high-precision nanoscale patterns with BAR > 1, achieving parameter transformation from micrometer to nanometer scale.
3Quantity of substance
If block copolymer self-assembly is used to multiply radial stripes, then circumferential density is improved, but process complexity increases
Solution Approach 1:
The block copolymer performs self-service by automatically organizing into radially-oriented lamellae through thermodynamic phase separation during annealing. This self-organizing behavior multiplies the circumferential density of patterns without requiring additional lithography steps or complex alignment procedures, as the material autonomously generates the high-density radial line pattern from the simpler radial stripe template.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the production of patterned-media disks with both high areal density and a BAR greater than 1, significantly improving the circumferential density of the master mold, enabling the fabrication of disks with higher areal bit density and higher BAR, overcoming the limitations of e-beam lithography.
Implementation Method 1
guided self-assembly of block copolymers to multiply these stripes into radial lines
Data Source
AI summary
A method for making a master mold that is used in the nanoimprinting process to make patterned-media disks with patterned data islands uses guided self-assembly of a block copolymer into its components. Conventional or e-beam lithography is used to first form a pattern of generally radial stripes on a substrate, with the stripes being grouped into annular zones or bands. A block copolymer material is then deposited on the pattern, resulting in guided self-assembly of the block copolymer into its components to multiply the generally radial stripes into generally radial lines. Various methods, including conventional lithography, guided self-assembly of a second block copolymer, and e-beam lithography, are then used to form concentric rings over the generally radial lines. After etching and resist removal, the master mold has a pattern of either pillars or holes, depending on the method used.