In-situ Fabrication of Micro Pillars on Paraffin Substrate Using Laser Heating

In this paper, a fabrication method to form micro pillars with a high aspect ratio (more than 20) from a paraffin substrate is described. This technique makes use of an interesting phenomenon that solid paraffin, melted by laser heating, grows into a pillar-shaped structure and solidifies in a liquid. The smallest size in diameter of the fabricated pillars is about 60 mum and it is possible to fabricate more precise pillar by reducing the laser spot size. Features of fabrication using cooling medium with different heat transfer rates, such as the distilled water, the silicone oil and the air, are discussed in this paper. Furthermore, influence of the material temperature on the shape of micro pillars is presented. The reproducibility and the stability of the fabrication are especially optimized when the material temperature is approaching its melting point