Nano eBooklet: Etching, Machining, and Molding High-Aspect-Ratio Microstructures
Nanoscale etching and fabrication are attracting growing attention as nanomaterials projects explore how best to move from the lab into commercial productions. Dr. Mark Jackson, Professor of Mechanical Engineering at Purdue University’s College of Technology, brings NanoScienceWorks.org members his expertise in nanomachinery and microscale metal cutting, molding and manufacturing with his exclusive 56-page eBooklet.
This exclsuive NanoScienceWorks.org eBooklet is entitled
Dr. Mark J. Jackson;
Birck Nanotechnology Center and College of Technology;
Purdue University, West Lafayette, IN 47907
Exclusive NanoScienceWorks.org eBooklet: 56 pgs; June 2007
The area of nanoscale etching of microstructures made from silicon-based materials is well-established, the process today is too slow for mass production and must be considered a microfabrication process.
Micromanufacturing of microstructures can be achieved by mechanically machining substrates from engineering materials or by mechanically machining molds for use in the mass production of microstructures made from polymeric materials.
Micromolding of thermoplastic polymers is also a well-established process. Several micromolding machines are sold on the market, and mold inserts fabricated with various techniques suitable for most applications are available. Micromolding can be classified as a micromanufacturing process.
Dr. Jackson’s 56-page eBooklet also includes a comprehensive look at many of the issues and challenges that can occur during nanofabrication processes, and the reasons they occur. Among Dr. Jackson’s list are:
- Boundary distortion: This occurs when the distance between the boundary layer and substrate changes along the length of the substrate that can be caused by trenches. The effect causes distortion of the electric field, which changes the concentration and direction of incoming ions so that they no longer impact the substrate at 90° degrees.
- Sidewall passivation: Results from the protective inhibiting layer formed over the substrate. However, in the case of a high-aspect-ratio trenches inhibitor build can vary with depth, specifically it is thicker at the trench top than at the bottom allowing the potential for undercutting.
- Sidewall charging: If the inhibitor is an insulator, it can gain a charge. This causes problems because successive charges can be repelled, disrupting the etching process, and incident ions can leave their charge on the wall.
- Ion deflection: This occurs when ions enter the trench (owing to the image force) and additional deflection is caused by the negative potential of the trench walls (a result of sidewall charging), which is believed to be one of the main sources of undercuts.
NanoScienceWorks.org members: Download your free copy of “Etching, Machining, and Molding High-Aspect-Ratio Microstructures,” Dr. Mark Jackson, Purdue University (56 pages, June 2007)