AR-P 8100 (Phoenix 81) thermal pattern-able positive resist
Lines written in PPA (resist AR-P 8100
Bridge with width of 16 nm, obtained after sputter coating with platinum (film thickness: 4 nm)
Adding PAGs (photo acid generator) to PPA (sample SX AR-P 8100/5) can increase the sensitivity and allow a bet- ter control of the gradation. The exposure causes a release of acid in situ which decomposes the PPA layer at 95 - 100 °C during the following PEB (positive development). The thermally induced, solvent-free development proceeds al- most completely. Despite the addition of PAGs, a very thin residual resist layer however remains.
If PAG-containing resists are used together with AR-P 617 in two-layer process, the thin remaining resist layer will not disturb the further process sequence since it is dis- solved during the subsequent development. After e-beam exposure and PEB, bottom resist AR-P 617 is selectively developed with developer AR 600-50. The undercut is ad- justed specifically by varying the duration of the develop- ment step. Reliably processable lift-off resist architectures can thus be produced. This method allows the realisation of metal bridges (platinum):
The process window is however quite narrow; already small variations of the dose affect the obtained line width considerably.