Micro-Faraday cup array structures fabrication in silicon using deep reactive ion etching

Abstract

Micro-Faraday cup array (MFCA) detectors are used for the detection and analysis of incident ion particles with greater stability and precision. New and simple micro FCA structures have been designed and fabricated considering the application in mass spectrometry and laser plasma techniques. MFCA structures were fabricated using UV lithography followed by deep reactive ion etching (DRIE). The UV lithography process was utilised for fabrication of micro-Faraday cup array structure in photoresist (AZ4903) deposited on n-type silicon substrate. After that DRIE process was used for creating array pattern in silicon. Ultimately 1 × 16 arrays having 25 μm widths with 125 μm spacing were fabricated. Maximum depth achieved with DRIE process was 16 μm. Exposure time of lithography was found to be reduced by 110% using UV-LED source for these structures. Effects of etch cycle time on cup depth and sidewall angle have also been discussed.