Electrode array fabrication on ITO coated PET foil

Lithography process

• Cut the piece of PET foil and stick it to a glass substrate. Careful, the ITO layer is quite breakable and easy to crack while bending. There are two ways of doing it. At first using a both side sticky tape, but then it is almoast unpossible to detach the foil from the glass. The other way is to use parafilm instead of sticky tape, then apply some press and heat it to 50°C. The parafilm coul be later removed

• Remove the blue protective foil and instantly deposit the POSITIV photoresist.

• Put the glass into spincoater and run the STATIC program.

• Leave in petry-dish for some minutes letting fotorezist to dry a bit.

• Bake the photoresist for 30 min at 50°C.

• Exposure the photoresist over mask. The exposure time was established to 4 min at 4cm distance from the UV fluorescent tube.

• Develop the oxposed photoresist in 0.7% NaOH.

• Etch the ITO layer in 5% HCl acid (5g 30% HCl + 25g H2O) for 2min. It is possible to remove substrate from the acid and check under microscope or check conductivity of etching area during the process to avoid overetching.

• Remove the resulting photoresist using IPA.