Contributing Editor, MEMS Investor Journal
IBM recently demonstrated a heated MEMS cantilever for nanoscale patterning -- producing a 25 nanometer-high 3D replica of the Matterhorn in under three minutes using the technique. Instruments using the heated MEMS cantilever will substitute for much slower and higher priced alternatives, such as e-beam lithography. IBM contends that its new patterning technique can directly create nanoscale electronic and mechanical components including optical gratings and 3D meta-materials. The technique can also be used to create shape-matching templates for the self-assembly of nanorods, nanotubes and similar nanoscale components.
Micrograph shows a close-up of the nanoscale silicon tip, similar to an atomic force microscope's measuring 500 nanometers in length and only a few nanometers at its apex, attached to a cantilever that scans the surface of the substrate material with the accuracy of one nanometer, operating like a “nanomilling” machine with ultra-high precision. Image courtesy of IBM Research - Zurich.
"The unusual part of our tool is the cantilever which we fabricated with MEMS techniques," said Urs Duerig, one of the IBM researchers working in Zurich on the project. "Now IBM wants to license this new technique to a company that will use it to build a tool that is much faster and more affordable than e-beams."
Applying a voltage to the outside section of the MEMS cantilever (Vf) invokes electrostatic force to push the cantilever against the substrate, while applying voltage to the inside section (Vh) heats the tip to evaporate resist.
Today e-beams can cost millions of dollars, prompting some research organizations to convert electron microscopes into a poor-man's e-beam. Now IBM hopes to capitalize on this need for less expensive nanofabrication techniques with its MEMS cantilever. IBM estimates that an instrument using its MEMS cantilever could yield resolutions to better than 15 nanometers -- more than twice the resolution of e-beam lithography -- while costing from one-fifth to one-tenth the price.
IBM demonstrated the accuracy of is new MEMS cantilever based tool by sculpting a 25 nanometer tall rendition (left) of the 14,692 foot tall Alpine mountain, the Matterhorn (right) at a scale of 1-to-5 billion.
IBM micromachines the tip (in a manner similar to atomic force microscopes) then uses masks to define the cantilever's two sections, as well as the resistive area that allows the tiny sub-10 nanometer tip to be heated by running current through its integrated resistor. Then, applying a voltage to the outside section invokes electrostatic force that closes the 300 nanometer gap between a cantilever and the thin film of resist on the surface of the substrate. Two levels of voltage can then be applied to the inner section of the cantilever to apply heat to the tip -- the lower temperature deforms only and the higher temperature vaporizes the resist completely, exposing the bare substrate beneath.
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