MTL Annual Report

Figure 1: Tiny Lloyd’s Mirror setup includes a laser driver, diode laser, beam expander, spatial filter, and mirror/substrate chuck. At the chuck, half of the beam is reflected from the mirror and subsequently interferes with a direct beam at the substrate. The interference of two beams creates a standing wave intensity pattern that is captured in a photosensitive material.

Periodic nanostructures have proven their usefulness in the fabrication of diffraction gratings, photonic crystals, magnetic domains in recording media, nanochannels in microfluidics ^[1], and even as templates for osteoblast migration ^[2]. Unfortunately the current tools to produce periodic nanostructures are enormous, are often difficult to operate, and cost anywhere from tens of thousands to millions of dollars. To address these issues, we devised a tool to produce periodic nanostructures with less complexity, less space, and less money.

Figure 2: Scanning electron micrographs of one- and two-dimensional periodic nanostructures made with the Tiny Lloyd’s Mirror. The gratings in the left image have a width of 131.5 nm while the rods in the right image have a diameter of 152.9 nm. The gratings have a pitch of 299.4 nm, which can be quickly modified by rotating the mirror/substrate chuck in Figure 1.

Interference lithography is an ideal method for the rapid production of periodic nanostructures. The Lloyd’s mirror interference lithography system uses a simple and rigid setup to produce one- and two-dimensional patterns, but its cost and size have previously been limited by the laser source (e.g., HeCd metal-vapor laser). Newly available low-cost blue laser diodes provide the ideal solution. They are small (about the size of a penny), can be controlled with a simple current source, and can cost as little as $300.

Using a commercially available blue laser diode, we have been able to solve the problems of size, complexity, and cost while maintaining the key functionality of the system. We previously presented our initial results ^[3] and have since improved the robustness of the tool. The Tiny Lloyd’s Mirror is a tabletop system that can produce periodic nanostructures over a 1 cm² area. The tool also has the ability to control the spacing between nanostructures and produce one- and two-dimensional patterns. Figure 1 is a schematic of the Tiny Lloyd’s Mirror tool. It consists of commercially available parts that are aligned in a linear fashion for easy construction. Figure 2 displays examples of the results that are achievable with the tool. Both one-dimensional gratings and two-dimensional rods are presented.

1. S.R.J. Brueck, “Optical and Interferometric Lithography – Nanotechnology Enablers,” Proceedings of the IEEE, vol. 93, no. 10, pp. 1704-1721, Oct 2005. [↩]
2. E. Lamers et al., “The influence of nanoscale grooved substrates on osteoblast behavior and extracellular matrix deposition,” Biomaterials, vol. 31, no. 12, pp. 3307-3316, Feb 2010. [↩]
3. C.P. Fucetola, H. Korre, and K.K. Berggren, “Low-cost interference lithography,” Journal of Vacuum Science and Technology B, vol. 27, no. 6, pp. 2958-2961, Nov/Dec 2009. [↩]