Tuesday, September 15, 2009

Home brew Microfluidics

Home brew Photolithography - large structures - high resolution imagesetter with plastic transparency for a mask
  1. Lateral positioning of the mask and substrate, resist material, and distance between mask and substrate
  2. exposure process of how to transfer patters to the photoresist layer: contact printing or projection printing
  3. development: dissolution or etching of the resist pattern
Are there any home brew or small scale/cost variants of:
  • interfereometric lithography
  • chemical vapor deposition
  • thermal oxidation
  • Sol-Gel deposition
  • Spin coating
  • wet etching
  • chemical or chemical-physical dry etching
What about pattern transfer processes? Steps in general (additive):
  1. deposit functional layer over a substrate
  2. spin coat with photoresist (positive or negative photoresist)
  3. select mask type (dark or clear field)
  4. transfer pattern to the resist layer
  5. etch the structure into the functional layer
  6. wash away photoresist
For lift-off you coat the photoresist directly on the sustrate, put on the mask, develop, but then deposit functional layer OVER the photo resist such that subsequently waashing off the parts with photoresist+functional wash away, but parts with substrate only+functional stay in place.

Sources: Fundamentals and Applications of Microfluidics, Second Ed. Nam-Trung Nguyen, Steven T. Wereley

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