Creating 3D structures with a direct-write grayscale photomask made from Sn/In bimetallic films

Glenn Chapman; Yuqiang Tu; Jun Peng

doi:10.1117/12.529492

15 July 2004 Creating 3D structures with a direct-write grayscale photomask made from Sn/In bimetallic films

Glenn Chapman, Yuqiang Tu, Jun Peng

Proceedings Volume 5339, Photon Processing in Microelectronics and Photonics III; (2004) https://doi.org/10.1117/12.529492
Event: Lasers and Applications in Science and Engineering, 2004, San Jose, Ca, United States

Abstract

Bilayer thermal resist Sn/In films have been found to be promising analogue direct-write photomask materials. The bimetallic films turn to be more transparent after a laser exposure which raises the films above the eutectic temperature. Laser converted layers are oxidized to a controlled extent, depending on the laser exposure energy. The exposure causes a change of absorption at 365nm from 3OD to 0.22OD. The thermal resist shows near wavelength invariance from IR to UV. The Sn/In films, each layer ~40 nm thick, were DC-sputtered onto glass slides or quartz substrates. To make grayscale photomasks the samples are placed on a computer-controlled high accuracy X-Y table. The computer takes a bitmap gray-scale pattern as the input and modulates an optical shutter, which in turn, controls the actual power of a CW Argon laser (514 nm) beam applied to the thermal resist according to the gray-scale value. Sn/In photomasks have been used together with a standard mask aligner to successfully make 3D patterns on Shipley SPR2FX-1.3 photoresist. CF4/O2 plasma etching has been used to transfer the 3D patterns to SiO₂ substrates. XRD analysis shows that laser power determines the extent of oxidation of the metal films.

Citation Download Citation

Glenn Chapman, Yuqiang Tu, and Jun Peng "Creating 3D structures with a direct-write grayscale photomask made from Sn/In bimetallic films", Proc. SPIE 5339, Photon Processing in Microelectronics and Photonics III, (15 July 2004); https://doi.org/10.1117/12.529492

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