Difference between revisions of "Photolithography"

Latest revision as of 15:41, 21 December 2023

Photolithography explained

Photolithography

SU8 process (square features)

Procedure updated Nov 2023

Handling of chemicals

Preparations the day before photolithography

• Open a new lab note here
  • Note down your desired process
  • As you go on the day, note all observations and final result
• Decide how thick layer of SU8 you need
• Choose right SU8 and protocol
  • GM1060 for layers between 5-25µm. Full datasheet
  • GM1070 for layers between 15-200µm. Full datasheet
• Find and note the following parameters (See page with tables and notes on parameters):
  • Speed of spin-coater in rpm
  • Pre- and post-bake times at 65 and 95 C, t_{65}, t_{95}
  • Exposure dose (divide the number from the table by factor 2 to 4, follow Mathias' measurement, use 20% power and multiply the time by 5)
  • PGMEA development time
• Take SU8 out of fridge and place in cupboard in 129
• Program
  • Spin coater
  • Hotplate

Materials and tools

• SU8
• Wafer (3" or 4")
• Isopropanol
• Wafer tweezers (in LAF bench and fume hood)
• Fine tipped tweezer
• Clean glass plate for placing wafers on
• N2 guns in 128 and 129
• Beaker and wafer holder for development
• Lint free paper

Procedure

• Turn on N2
• Turn on and open LAF bench

• Turn off N2
• Turn off and close LAF bench

Procedure notes before Nov 2023

• Full description of process

• A Simplified Version

• Mathias Busek's protocol 2020

Programming various equipment

UV KUB programming

Spin coater programming

Hot plate programming

Important notes 05.03.2021

• UV doses in the tables are too large. Look at comments in Matias Busek's protocol
• The programmable hotplate is not reliable
  • Two times in a row the same procedure for 25 um thick substrate with VWR and programmable hot plates gave good results for VWR hotplate but overdevelopment for programmable hotplate.
  • I have observed that the programmable hotplate seems to spend too long time at each step.

XT process (rounded channels)