Lecture 7 Fundamentals of Multiscale Fabrication Multiscale fabrication VI: Hybrid methods, multiscale integration Kahp-Yang Suh Associate Professor SNU MAE sky4u@snu.ac.kr

Scanning Probe Lithography (SPL) Probe technology 30 nm wires on PMMA resist 30 nm dots on PMMA resist (National nanotechnology laboratory, Lecce University, Italy)

Scanning Probe Lithography (SPL) Combination with bottom-up Carbon nanotube(CNT) attached on the tip of AFM cantilever can be used as a pen to write words on Au surface with alkylthiol ink.

Dip-pen nanolithography (DPN)

Dip-pen nanolithography (DPN) Butt (1995) the creation of aggregates of octadecanethiol on mica Mirkin (1997) transport of water to and from polymer and mica substrates as effected and observed by LFM Mirkin (1999) organic patterns of dot arrays or lines with thiol-based molecular inks on polycrystalline gold and Au(111)

Dip-pen nanolithography (DPN) Nanopatterning via DPN and wet etching Deposition of ODT onto an Au surface of a multilayer substrate using DPN selective Au/Ti etching with ferri/ferrocyanide-based etchant selectiveTi/SiO2 etching and Si passivation with HF selective Si etching with basic etchant and passivation of Si surface with HF removal of residual Au and metal oxides with aqua region and passivation of Si surface with HF

Dip-pen nanolithography (DPN) Parallel and serial writing DPN

Dip-pen nanolithography (DPN) Nanoparticle/Protein arrays generated by DPN

Dip-pen nanolithography (DPN) Electrochemical DPN E-DPN technique can be used to directly fabricate metal and semiconductor features with nanometer dimensions. tiny water meniscus as a nanometer-sized electrochemical cell in which metal salts can be dissolved, reduced into metals electrochemically, and deposited on the surface

Dip-pen nanolithography (DPN) Polymer Pen Lithography (PPL) In contrast with DPN and other SPM-based lithographies, which typically use hard silicon– based cantilevers, PPL uses elastomeric tips without cantilevers [typically polydimethylsiloxane (PDMS)] to deliver ink. A typical polymer pen array contains thousands of pyramid-shaped tips that are made with a master prepared by conventional photolithography and subsequent wet chemical etching. Science, 321, 1658 (2008)

Multi-layer transfer with contact printing Layer-by-Layer (LbL) technique Concept: Integration of various functional systems of polymers, nanoparticles (NPs) Multicomponent patterning of functional thin films composed of polyelectrolytes and nanoparticles with controlled alignment Contact printing with controlled alignment Adv. Mater. 17, 2575–2579 (2005)

Photolithography+ LbL Layer-by-Layer (LbL) technique Scaling-down process by using LbL. The molecular resist decreases the gap quantitatively between two Au nanostructures. Metal deposition is performed on top of the molecular resist into the remaining gap. Spacing: 110 nm  20 nm gap Science, 291, 1019 (2001)

Block copolymer Science, 251, 898 (1991) Diblock copolymers consist of two chemically different polymer chains (or blocks) joined by a covalent bond Because of connectivity constraints and the incompatibility between the two blocks, diblock copolymers spontaneously self-assemble into microphase-separated nanometer-sized domains that exhibit ordered morphologies at equilibrium. . Science, 251, 898 (1991)

Block copolymer (BCP) lithography Science, 276, 1401 (1997)

Photo + BCP lithography Degradation of the PMMA domains and subsequent etching allowed nanoscale features to be lithographically transferred with high fidelity, leading to highly ordered square arrays of 20-nm cylindrical pores Science, 322, 429 (2008)

E-beam + BCP lithography Process to create lithographically defined chemically prepatterned surfaces and subsequent directed assembly Science, 321, 936 (2008)

Lithography + surface tension Results showing the effects of various pinning points and surfactants, and included self-assembled particles. a) A circular pinning point in a BSA solution. b) Triangular pinning points in a Triton X-100 solution. c) A quantum-dot line forming between two square pinning points. d) SEM image of self-assembled 2-mm-bead arrays. cf) Typical coffee staining effect by evaporation from edges with pinning (no regular patterns formed) Nano Letters, 6, 271-276 (2006) Small, 2, 832-834 (2006)

Lithography + surface tension Fabrication gray zone (10 ~ 50 nm) Lithography + surface tension Nano Nanotechnology, 3, 682-690 (2008)