EXPOSURE OF ADVANCED POSITIVE AND NEGATIVE E-BEAM RESISTS WITH FOCUSED ION-BEAMS

Negative- and positive-tone e-beam resists have been exposed by focused beams of Si++ and Be++ ions. The resolution of the negative resist. Shipley SAL601-ER7, was better than 0.2 mum and vertical sidewalls were achieved. A dose of 2 X 10(12) ions cm-3 was required to retain the full thickness of the resist after developing. Different postexposure bake (PEB) times and temperatures were examined in this work. A saturation in resist response was observed at moderately high PEB temperatures 115-125-degrees-C). This effect has not been reported previously for either ion-beam or e-beam exposure. Increases in developing time can increase the sensitivity and the effective contrast of this resist. The positive-tone resist, OCG Microelectronic Materials P28, is at least two to three times more sensitive than PMMA. It also displays a wide range of doses (4-25 X 10(12) ions cm-2) for which positive-tone imaging is possible. Present results show the resolution of P28 to be at least 0.3 mum, which is not as fine as that of polymethylmethacrylate (PMMA). Preliminary results on the behavior of the P28 resist as a mask for silicon etching are presented.