Micro-Ball Lens Array Fabrication in Photoresist Using Ptfe Hydrophobic Effect

Abstract

This paper presents a simple method to fabricate micro-ball lens and its array. The key technology is to use the hydrophobic characteristics of polyterafluoroethylene (PTFE) substrate. High contact angle between melted photoresist pattern and PTFE can generate micro-ball lens and its array. PTFE thin film was spun onto a silicon wafer and dried in oven. Photoresist AZ4620 was used to pattern micro-columns with different diameters 60, 70 and 80 $\mu$m. A thermal reflow process then was applied to melt these micro-column patterns resulted in micro-ball lens array. The achieved micro-ball lens array with diameter 98 $\mu$m was fabricated using 80 $\mu$m in diameter patterns. This method provides a simple fabrication process and low material cost.