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
Overview E-beam Positive