Cantilevers became popular with the invention of the atomic force microscope (AFM) in 1986. Micro cantilevers are used in microcalorimetry, mass detection with resonating devices, and magnetic force microscopy. As an example, in biosensing, changes of surface stress or the selective attachment of various molecules induce static bending of the cantilever. The simple mechanical behavior of cantilever-based sensors allows straightforward translation of mechanical forces into displacement. Various applications of SU-8 cantilevers with the thicknesses of 2 –10 µm have been described in the literature.

SU-8: Benefits/Attributes

  • Highly chemical resistant
  • Low Young’s Modulus
  • Relatively easy fabrication
  • Surface can be modified

PMGI Material Attributes/Properties

  • Spin-coatable from 10nm to 6nm in a single coat
  • No intermixing with imaging resist
  • High thermal stability <300 C (Tg~189C)
  • Strippable in NMP and aqueous-based developers
  • Resistant to conventional semiconductor solvents
  • Excellent adhesion to various substrates
  • DUV, E-beam and x-ray sensitive
  • High etch rate in O2 plasma
  • Excellent conformal or planarizing formulations available

Process Flow

1. Coat release layer according to supplier recommendations.

2. Coat SU-8 layer according to the datasheet recommendations.

3. Expose and PEB SU-8 layer. Do not develop.

4. Coat second SU-8 layer according to datasheet recommendations.

5. Expose and PEB second SU-8 layer.

6. Develop SU-8 layers.

7. Release SU-8 layers from the substrate.