Electrical Biomolecule Detection Using Nanopatterned Silicon via Block Copolymer Lithography

An electrical biosensor exploiting a nanostructured semiconductor is a promising technology for the highly sensitive, label‐free detection of biomolecules via a straightforward electronic signal. The facile and scalable production of a nanopatterned electrical silicon biosensor by block copolymer (BCP) nano­lithography is reported. A cost‐effective and large‐area nanofabrication, based on BCP self‐assembly and single‐step dry etching, is developed for the hexagonal nanohole patterning of thin silicon films. The resultant nanopatterned electrical channel modified with biotin molecules successfully detects the two proteins, streptavidin and avidin, down to nanoscale molarities (≈1 nm ). The nanoscale pattern comparable to the Debye screening length and the large surface area of the three‐dimensional silicon nanochannel enable excellent sensitivity and stability. A device simulation confirms that the nanopatterned structure used in this work is effective for biomolecule detection. This approach relying on the scalable self‐assembly principle offers a high‐throughput manufacturing process for clinical lab‐on‐a‐chip diagnoses and relevant biomolecular studies.     

Controlled Segmentation of Metal Nanowire Array by Block Copolymer Lithography and Reversible Ion Loading

Spatial arrangement of 1D nanomaterials may offer enormous opportunities for advanced electronics and photonics. Moreover, morphological complexity and chemical diversity in the nanoscale components may lead to unique properties that are hardly anticipated in randomly distributed homogeneous nanostructures. Here, controlled chemical segmentation of metal nanowire arrays using block copolymer lithography and subsequent reversible metal ion loading are demonstrated. To impose chemical heterogeneity in the nanowires generated by block copolymer lithography, reversible ion loading method highly specific for one particular polymer block is introduced. Reversibility of the metal ion loading enables area‐selective localized replacement of metal ions in the self‐assembled patterns and creates segmented metal nanowire arrays with different metallic components. Further integration of this method with shear aligning process produces high aligned segmented metal nanowire array with desired local chemical compositions.     

Lattice Deformation and Domain Distortion in the Self‐Assembly of Block Copolymer Thin Films on Chemical Patterns

The self‐assembly of cylinder‐forming block copolymer (BCP) microdomains confined within chemical stripe patterns of widths incommensurate with the natural period of the copolymers, L₀, is studied. It is shown that this incommensurability causes changes in both the shapes of the microdomains and their spatial period. Specifically, a transition from n to n + 1 rows of microdomains is observed when the stripe width is about n ± 1/2 L₀. When the stripe's width is comparable to L₀, ellipticity of microdomains can be induced with an aspect ratio up to 2.2. Free energy models are applied to describe the energetic origin of such behavior. Although our observations qualitatively resemble results in sphere‐forming BCPs confined in topographical trenches, the quantitative difference is noteworthy and technologically important for the design of nanostructures with programmable shapes.     

Carbohydrate‐Based Block Copolymer Thin Films: Ultrafast Nano‐Organization with 7 nm Resolution Using Microwave Energy

Block copolymers (BCP) can self‐assemble into nanoscale patterns with a wide variety of applications in the semiconductor industry. The self‐assembly of BCPs is commonly accomplished by solvent vapor or thermal annealing, but generally these methods require long time (few hours) to obtain nanostructured thin films. In this contribution, a new and ultrafast method (using microwaves) is proposed—high temperature solvent vapor annealing (HTSVA), combining solvent vapor annealing with thermal annealing, to achieve fast and controllable self‐assembly of amphiphilic BCP thin films. A promising carbohydrate‐based BCP capable of forming cylindrical patterns with some of the smallest feature sizes is used for demonstrating how to obtain a highly ordered vertical cylindrical pattern with sub‐10 nm feature sizes in few seconds by HTSVA. HTSVA provides not only a simple way to achieve BCP fast self‐assembly in practical applications but also a tool to study the self‐assembly behavior of BCPs under extreme conditions.