Silicon-Polylactide Diblock Copolymer Nanolithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithographic techniques face limitations in creating sub-100 nm features with desired structural alignment and etch contrast for bit-patterned media, as conventional block copolymers lack sufficient etch selectivity and resolution.
Innovation Solution
A diblock copolymer system is developed, combining silicon-containing and polylactide blocks, synthesized via anionic and ring-opening polymerization, which self-assembles to form nanoporous materials suitable as etch masks in lithographic patterning, offering high etch contrast and small feature sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional block copolymers are used for lithographic patterning, then self-assembly into well-defined structures is achieved, but etch contrast and selectivity are insufficient
Solution Approach 1:
The patent introduces silicon atoms specifically into one block of the diblock copolymer (the polystyrene block), creating local compositional differences. This selective silicon incorporation provides etch selectivity between the two blocks, as the silicon-containing block exhibits different etching behavior compared to the non-silicon-containing polylactide block, thereby resolving the etch contrast and selectivity issue.
Solution Approach 2:
The patent creates a composite block copolymer system combining organic polylactide and polystyrene blocks with inorganic silicon atoms incorporated into one block. This composite structure leverages both organic self-assembly capabilities and inorganic etch resistance, achieving high etch contrast while maintaining the self-assembled nanoscale morphology needed for lithographic patterning.
2Manufacturing precision
If optical lithography is used for template patterning, then cost is reduced, but resolution for sub-25 nm features is insufficient
Solution Approach 1:
The patent segments the patterning process into two distinct stages: (1) self-assembly of diblock copolymers to form nanoscale templates with desired morphology, and (2) selective etching of one block to create the final pattern. This segmentation allows optical lithography to define the overall pattern geometry while the self-assembly process generates the sub-25 nm features, combining the advantages of both approaches.
Solution Approach 2:
The diblock copolymer template acts as an intermediary between optical lithography and the final pattern transfer. The copolymer self-assembles into well-defined nanoscale structures that serve as a mask or template, enabling the transfer of sub-25 nm features through subsequent etching processes while maintaining compatibility with optical lithography workflows.
3Productivity
If electron beam lithography is used for template patterning, then resolution for sub-25 nm features is achieved, but throughput is too slow
Solution Approach 1:
The patent employs self-service by utilizing the inherent self-assembly capability of diblock copolymers to spontaneously form ordered nanoscale structures without requiring direct electron beam writing. The copolymers self-organize into well-defined morphologies (lamellae, cylinders, spheres) with sub-25 nm features, eliminating the need for slow serial electron beam patterning while achieving comparable or superior resolution.
Solution Approach 2:
The patent replaces the mechanical/physical scanning process of electron beam lithography with a chemical self-assembly process. Instead of using electron beams to directly write patterns point-by-point, the system uses thermodynamic self-organization of copolymer chains to generate the desired nanoscale patterns in parallel across the entire substrate, dramatically increasing throughput.
4Manufacturing precision
If block copolymers with high molecular weight are used, then self-assembly into well-defined structures is achieved, but feature size is too large
Solution Approach 1:
The patent changes the molecular weight parameter of the diblock copolymer to very low values (total molecular weight of 1000-5000 g/mol), which is unconventional as most self-assembling copolymers require high molecular weights. This parameter change enables the formation of sub-25 nm features while maintaining self-assembly stability through careful selection of block composition and interaction parameters.
Solution Approach 2:
The patent introduces silicon atoms locally into one block of the low molecular weight copolymer, creating localized regions of enhanced interaction and structural stability. This local compositional modification compensates for the reduced overall molecular weight, enabling stable self-assembly into well-defined nanoscale structures despite the low polymer chain length.
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
The diblock copolymer system enables the formation of small, aligned nanostructures with high etch contrast, overcoming feature-size limitations and enhancing storage density in semiconductor applications.
Implementation Method 1
The self-assembly of diblock copolymers into well-defined structures on the order of 5-100 nm produces features on the length scale required for production of bit patterned media
Implementation Method 2
Previous research has targeted block copolymers that produce hexagonally packed cylindrical morphology with selective silicon incorporation into one block for etch resistance
Data Source
AI summary
The present invention includes a diblock copolymer system that self-assembles at very low molecular weights to form very small features. In one embodiment, one polymer in the block copolymer contains silicon, and the other polymer is a polylactide. In one embodiment, the block copolymer is synthesized by a combination of anionic and ring opening polymerization reactions. In one embodiment, the purpose of this block copolymer is to form nanoporous materials that can be used as etch masks in lithographic patterning.