Ion projector wafer exposure results at 5× ion-optical reduction obtained with nickel and silicon stencil masks

A detailed study of the resolution performance of an advanced research type ‘‘Alpha Ion Projector’’ with 5× ion-optical reduction has been performed. One part of the study was done with a nickel open stencil test mask with an active field of 40 mm×40 mm with smallest line pattern openings of ≊0.7 μm width (2.0 μm periodicity). The other part was done with a silicon stencil test mask (120 mm diam, 2.5 μm thickness, 60 mm×60 mm design field) with smallest line patterns of ≊0.4 μm width (1.0 μm periodicity). The Alpha Ion Projector exposures were performed in positive (PMMA: OEBR-1000) and negative (SNR-M4, RAY-PN) resist materials with subsequent wet chemical development. The 0.15-μm resolution was obtained in the case of wafer exposures with the nickel stencil mask within the 8 mm×8 mm exposure field whereas in the case of wafer exposures with the silicon stencil mask sub-0.1-μm resolution could be achieved near the center of the exposure field at 5.2× ion-optical reduction.