Photo-ablation lithographic technique at 172 nm based upon flat excimer lamps (Conference Presentation)

Photolithographic techniques capable of producing sub-micron scale features typically involve laser or electron beam sources and chemical development of an exposed photoresist. We report here a novel, low cost photolithographic process utilizing flat, efficient lamps emitting at 172 nm. Recently developed 10 cm x 10 cm lamps, for example, produce more than 25 W of average power at 172 nm which enables the precise and fast patterning of most polymers, including those normally employed as e-beam resists and photoresists. Recent experiments demonstrate that PMMA films less than 100 nm in thickness are patterned in less than 20 s through a contact mask with high contrast resolution of 500 nm features. The ultimate resolution limit is expected to be ≤ 300 nm for a contact method. Electroplating technique was further used to deposit 500 nm gold features on a silicon substrate. The reported process does not require a photoresist development step and is performed in nitrogen atmosphere at atmospheric pressure which make it fast and affordable for fabrication facilities that have no access to high-tech photolithography equipment. Samples as large as 76 mm (3”) in diameter may be exposed with a single lamp in one step and areas of 1 m2 and above may be processed with tiled arrays of lamps. Patterning of bulk polymers (acrylic sheets, for example) through a photomask and subsequent formation of sub-micron features has also been demonstrated.