AR-P 617 Two layer lift-off system

An alternative version of the structure of  two layer systems emanates from only one resist: AR-P 617 (PMMAcoMA 33)

Schematic representation of the two layer system:
AR-P 617, SB 200°C (bottom),
AR-P 617, SB 180°C (top)

At increasing temperature, AR-P 617.08 becomes linearly more sensitive   (coat thickness 680 nm):

The bottom layer is tempered at 200°C for 10 – 20 minutes, afterwards coated with AR-P 617 and again tempered with the upper layer, however, at only 170 – 180 °C. There is no mixing during the coating, which ensures a well-defined layer composition. The resist sensitivity grows with increasing soft bake temperature, therefore AR-P 617 is about 20 % more sensitive at a post-cure of 200 °C compared to 180 °C. Thus, the dose can be systematically adjusted. After development with AR 600-50 or also MIBK/IPA, well-defined lift-off structures result:

Undercut resist architecture after development with AR 600-50:
bottom layer 400nm thick,
top layer 500nm thick

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