Quality Investigation Of Laser Processed Silicon Wafer

Gan, Puoh Yoon (2015) Quality Investigation Of Laser Processed Silicon Wafer. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Laser micromachining on silicon wafers are becoming more widely known in industries as it gives many advantages compared to other traditional methods. In this project, laser micromachining was conducted on the P-type silicon wafer at room temperature with the optimum carbon dioxide, CO2 laser power of 47.69 W, pulse frequency of 297.05 Hz and duty cycle of 60.54 % for drilling and laser power of 800 W, feed of 2100 mm/min and pulse frequency of 250 Hz for cutting under steady condition. The silicon wafer was cleaned by acetone and undergoes surface modification whereby the wafer is completely immersed and etch in potassium hydroxide (KOH) solution before being machined by CO2 laser. Parameters involves during etching are time, temperature and concentration. Effect of the thickness of silicon wafer before and after etching, surface roughness and uniformity of the modified wafer are investigated, followed by kerf width, surface roughness of the holes and hole diameter of the wafer after laser drilling. The Box-Behnken design in Response Surface Methodology (RSM) is used to model and optimize the etching parameters with the relation to the output responses obtained after laser machining. This research intends to obtain the minimal surface roughness of the holes and high quality micro holes. Hence, the etching parameters are optimized at 30 minutes, 70oC and 33.14% concentration for minimal etching responses and the wafer thickness after etching is 435.85 μm, surface roughness after etching is 0.16 μm to obtained a kerf width of 0.282 mm, hole diameter of 0.39 mm and roughness of the holes of 1 μm.

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