A novel ultra-violet assisted anisotropic etching of plastic to realize micro-gears

• DOI: 10.1016/j.sna.2004.02.015
• Publication Date: 2004-04-02T05:15:22Z
• Authors: B. Sadeghi-Makki; M.R. Ghafouri-Fard; S. Mohajerzadeh; T. Maleki; S. Mohammadi; M. Miri; E.Asl Soleimani
• Keywords: Undercut; Isotropic etching; Ultraviolet; Light intensity; Intensity; Ultraviolet light

An ultraviolet assisted chemical etching of plastic is reported in which the etching of PET substrates is anisotropic in the direction of light illumination. A strong solvent as di-methyl-formamide (DMF) is exploited to perform the chemical etching process and patterning of the desired structures is feasible using a Ge/Cu bi-layer as the masking film. Etch rate depends strongly on the intensity of the ultra-violet light and temperature of the solution during this etching process. An average etch rate of 15 m/h is achieved with little mask undercut in the presence of 6–8 mW/cm 2 of 365 nm UV at a temperature of 120 ◦ C. The highest achieved etch rate in this technique is 40 m/h using an intensity of 16 mW/cm 2 for the UV illumination. The effects of solution temperature during etching, the intensity of light, and the amount of the solvent above the sample have been studied. This technique has been applied to etch 80m of PET substrates and to make 40m thick square membranes with an area of 500m × 500m. Also 120m thick micro-gears have been realized with a diameter of 900m. The gears have been freed and installed on their corresponding axels with a diameter of 100m. © 2004 Elsevier B.V. All rights reserved.