Aim:


Cost-effective method for manufacturing micro lens arrays, no expensive tools for mould manufacture necessary apart from those for standard UV lithography

Solution:


Reflow of high viscosity positive tone photoresist ma-P 1275 and subsequent pattern transfer

Formation of photoresist mould:

  • Standard lithography of ma-P 1275 to form pillars
  • Reflow on hotplate, temperature ramp 4 – 8 K/ min from 100 °C, 5 min hold time at 140 °C
  • Lens structure controlled by height/ diameter ratio of original ma-P 1275 pillars, half spheres obtained with ratio 1 : 3
    •


    ———————— Pattern transfer:————————

    A

    B
  • ma-P 1275 lenses transferred by RIE e.g. into Si or glass
  • (optional: subsequent UV moulding into OrmoStamp and OrmoComp)
    •
  • UV moulding with UV curable OrmoStamp
  • Application of antisticking layer
  • OrmoStamp mould for multiple UV moulding of OrmoComp micro lens arrays
    •

    Reflow_process flow

    reflow_120µm
    reflow_60µm_ormocomp
    Array of 120 µm diameter lenses transferred into Si by RIE
    Array of 60 µm diameter lenses transferred into OrmoComp by UV moulding