Maskless Fabrication of Nanowells Using Chemically Reactive Colloids

• Published in: Nano letters Vol. 11; no. 2; pp. 672 - 676
• Main Authors: Chaturvedi, Neetu, Hsiao, Erik, Velegol, Darrell, Kim, Seong H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.02.2011
• Subjects: Chemical synthesis methods; Colloids - chemistry; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallization - methods; Diffusion in nanoscale solids; Diffusion in solids; Exact sciences and technology; Macromolecular Substances - chemistry; Materials science; Materials Testing; Methods of nanofabrication; Molecular Conformation; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology - methods; Particle Size; Physics; Structure of solids and liquids; crystallography; Surface Properties; Transport properties of condensed matter (nonelectronic); Silicon; inverted pyramids; amidine hydrolysis; locally generated etchant; maskless nanoetching; Hydroxides; Colloids; Amidines; Etching; Etching reagent; Polystyrene; Latex; Hydrolysis; Nanoparticles; Hexagonal lattices; Nanofabrication; Wafers; Diffusion; Nanostructured materials
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl1037984

This letter describes the maskless fabrication of nanowells on a silicon substrate using chemically reactive nanoparticles. The amidine-functionalized polystyrene latex (APSL) colloids are adhered onto a silicon wafer, and hydrolysis of the particles’ amidine groups generates the ammonium hydroxide etchant locally. The localized release of reactive species and its fast diffusion into the bulk liquid ensure that the silicon etching takes place only under the APSL colloids. Thus, the basal length of the nanowells is precisely controlled by the diameter of the APSL particles. The shape of the nanowells depends on the structure of the substrate: inverted pyramids on silicon (100) and hexagonal pits on silicon (111). The method described here provides an easy, inexpensive, safe, and high-throughput approach for generating nanowells on silicon surfaces. This maskless and simple nanofabrication method will open doors for new applications with locally generated or locally delivered chemistry from nanoparticles.