Hybrid Pre-patterns for Directed Self-Assembly of Block Copolymers
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Solution Overview
Problem
Current methods for directed self-assembly of block copolymers face challenges in achieving self-aligned customization of perpendicularly oriented domain patterns over regions with different wetting properties and etch characteristics, particularly at smaller pitch sizes, due to limitations in overlay budgets and defects such as flipped domains and etch resistance issues.
Innovation Solution
A hybrid pre-pattern with independent elevated and recessed surfaces and sidewalls is used, where the self-assembly material forms lamellar domain patterns with specific etch resistance properties, allowing for selective etching and transfer of patterns, enabling self-aligned customization without the need for separate cut layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate cut layers are used for customization, then pattern customization is achieved, but overlay budget is exceeded and alignment precision deteriorates
Solution Approach 1:
The patent merges the customization function and the DSA guiding function into a single hybrid pre-pattern layer. The pre-pattern contains both directing regions (with chemical functionality for DSA) and non-directing regions (enabling customization) within the same layer structure, eliminating the need for separate cut layers and thereby preserving overlay budget.
Solution Approach 2:
The hybrid pre-pattern serves multiple functions simultaneously: it acts as a chemical directing pattern for DSA, provides etch resistance in specific regions, and enables pattern customization all within a single layer structure. This multi-functionality resolves the contradiction by integrating what previously required separate layers.
2Adaptability or versatility
If alignment conferring region width is increased, then customization capability is improved, but domain orientation stability deteriorates due to flipped domains
Solution Approach 1:
The patent applies different properties to different regions of the pre-pattern: directing regions have chemical functionality and specific width ranges (0.5Lo-1.5Lo) that ensure stable perpendicular domain orientation, while non-directing regions have different etch resistance properties that enable customization. This local differentiation allows both customization and orientation stability within the same layer.
3Device complexity
If single-layer pre-pattern is used, then process complexity is reduced, but etch resistance uniformity deteriorates across different regions
Solution Approach 1:
The hybrid pre-pattern incorporates regions with different etch resistance properties (directing regions with higher etch resistance, non-directing regions with lower etch resistance) within a single layer structure. This local differentiation of etch resistance enables selective etching for customization while maintaining the layer's function as a unified DSA guiding pattern.
4Productivity
If pitch is reduced for higher density, then productivity is improved, but pattern customization becomes more difficult due to tighter overlay budget
Solution Approach 1:
By merging customization and DSA guidance into a single hybrid pre-pattern layer, the patent enables pattern customization even at reduced pitches where overlay budget is tight. The integration eliminates the cumulative overlay errors that would result from using separate cut layers, making customization feasible at higher densities.
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 enables the generation of self-aligned customized transfer patterns with improved etch resistance and reduced defects, effectively addressing the challenges of pattern customization at smaller scales and varying surface properties.
Implementation Method 1
The SA material is capable of self-assembling to form a phase separated lamellar domain pattern having a characteristic pitch Lo
Implementation Method 2
the directed self-assembly (DSA) of block copolymers (BCPs) is a promising resolution enhancement technology to extend patterning. Chemoepitaxy, a form of DSA, has been demonstrated to reliably generate dense grating and hexagonal arrays from sparse chemical pre-patterns
Implementation Method 3
material underlying the elevated surfaces of the pre-pattern has greater etch-resistance in a given etch process compared to material underlying the recessed surfaces of the pre-pattern
Data Source
AI summary
Hybrid pre-patterns were prepared for directed self-assembly of a given block copolymer capable of forming a lamellar domain pattern. The hybrid pre-patterns have top surfaces comprising independent elevated surfaces interspersed with adjacent recessed surfaces. The elevated surfaces are neutral wetting to the domains formed by self-assembly. Material below the elevated surfaces has greater etch-resistance than material below the recessed surfaces in a given etch process. Following other dimensional constraints of the hybrid pre-pattern described herein, a layer of the given block copolymer was formed on the hybrid pre-pattern. Self-assembly of the layer produced a lamellar domain pattern comprising self-aligned, unidirectional, perpendicularly oriented lamellae over the elevated surfaces, and parallel and/or perpendicularly oriented lamellae over recessed surfaces. The domain patterns displayed long range order along the major axis of the pre-pattern. The lamellar domain patterns are useful in forming transfer patterns comprising two-dimensional customized features.