Block Copolymer Self-Assembly for Semiconductor Patterning
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Solution Overview
Problem
Conventional photolithography techniques for integrated circuit fabrication are limited by the properties of photo-resist materials, such as line resolution and line edge roughness, and struggle to achieve dimensions smaller than those possible with conventional methods, as well as prevent pattern collapse in tall and thin structures.
Innovation Solution
A method involving the use of a block copolymer with different types of polymer blocks, such as PMMA, PS, and PAMS, is applied to form patterns on an image layer, where the blocks are selectively removed to create mask structures with specific pitches and dimensions, allowing for the formation of multiple repeating patterns and achieving dimensions smaller than those possible with traditional photolithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If top-down photolithography patterning is used, then the process is simple and widely applicable, but line resolution and line edge roughness are limited by the large size of photo-resist polymer molecules
Solution Approach 1:
The patent inverts the conventional top-down patterning approach by using bottom-up self-assembly of block copolymers. Instead of patterning photo-resist to define features, the block copolymer spontaneously forms ordered microphase-separated structures that directly create the desired patterns. This inversion enables sub-10nm resolution by leveraging the natural self-assembly length scales of block copolymers rather than being limited by optical diffraction and photo-resist molecule size.
Solution Approach 2:
The patent employs block copolymers composed of chemically distinct polymer blocks (e.g., polystyrene and polymethylmethacrylate) that self-assemble into ordered microphase-separated structures. This composite material approach allows different blocks to form distinct patterns with controlled dimensions and spacing, achieving high resolution patterning that cannot be obtained with homogeneous photo-resist materials.
2Manufacturing precision
If photo-resist material with large polymer molecules is used, then the material is stable and easy to process, but line edge roughness increases and pattern fidelity decreases
Solution Approach 1:
The patent segments the polymer material into distinct block copolymer components with different chemical properties. Each block self-assembles into specific regions, creating well-defined interfaces with minimal line edge roughness. This segmentation at the molecular level translates to sharp, well-defined pattern edges that are insensitive to the overall polymer chain length, overcoming the line edge roughness problem of conventional photo-resist.
3Manufacturing precision
If conventional photolithography is used, then the process is well-established, but achieving dimensions smaller than conventional limits is not possible
Solution Approach 1:
The patent changes the fundamental patterning parameter from optical wavelength-limited photolithography to block copolymer equilibrium domain spacing. By selecting block copolymers with different molecular weights, compositions, and block ratios, the feature dimensions can be precisely tuned across a wide range from sub-10nm to hundreds of nanometers. This parameter change enables access to dimension regimes inaccessible to conventional photolithography.
4Manufacturing precision
If tall and thin photo-resist structures are formed, then high aspect ratio patterning is achieved, but pattern collapse occurs due to structural instability
Solution Approach 1:
The block copolymer self-assembled structures inherently possess mechanical stability at the nanoscale due to their self-organized nature and strong inter-block interactions. The microphase-separated morphology creates mechanically robust features that resist collapse during subsequent processing steps, eliminating the need for additional support structures or complex process optimization required for tall and thin photo-resist patterns.
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 creation of fine patterns with various dimensions and pitches, overcoming the limitations of conventional photolithography and allowing for the patterning of smaller features and diverse structures in integrated circuit fabrication.
Implementation Method 1
a plurality of the first type polymer blocks, a plurality of second type polymer blocks, and a plurality of third type polymer blocks are formed on an area of the image layer between outer edges of the two nearest activated areas, from the block copolymer
Implementation Method 2
A method involving the use of a block copolymer with different types of polymer blocks, such as PMMA, PS, and PAMS, is applied to form patterns on an image layer
Data Source
AI summary
For patterning during integrated circuit fabrication, an image layer is activated for forming a respective first type polymer block at each of two nearest activated areas. A layer of block copolymer is formed on the image layer, and a plurality of the first type polymer blocks and a plurality of second and third types of polymer blocks are formed on an area of the image layer between outer edges of the two nearest activated areas, from the block copolymer. At least one of the first, second, and third types of polymer blocks are removed to form a variety of mask structures.