Study on Wetting Behavior of Liquid Mercury Droplet on Silicon Wafer Surface

We addressed the wetting behavior of liquid mercury on plasma-etched Si wafer surface. The influence of the surface roughness and mercury droplet volume on the wettability was investigated with metallurgical microscope, white light interferometer, 3D profilometer and contact angle measurement. The results show that the surface roughness and Hg-droplet volume significantly affected the contact angle. The results show that the surface roughness and Hg-droplet volume had a major impact. To be specific, as the surface roughness increased, the contact angle of the mercury droplet with the same volume increased; the largest static contact angle reached 158. 3° when the surface roughness was 257. 01 μm and the volume was 1 μL; as the volume increased from 1 to 4 μL and the surface roughness remained to be the same, the contact angle gradually decreased, with a largest net decrease of 11. 6° on a dense "reticular"-structured Si wafer surface.