PICOSECOND LASER MICROMACHINING OF SILICON WAFER: CHARACTERIZATIONS AND ELECTRICAL PROPERTIES

This work presents the feasibility of picosecond laser micromachining of polysilicon wafer. Surface topography, microstructure and residual stress of both as-received surface and laser-machined surface were analyzed carefully by confocal microscope, scanning electron microscope and Raman microscope. Moreover, electrical properties of laser-machined wafer have been investigated to examine the effect of laser micromachining on Si substrate via characterizations of resistivity and I-V curves. The results show that the wafer thickness has been reduced up to 50%, while the depth of HAZ is less than 3 mu m, and compressive stress can be achieved at the laser-machined surface. Besides, laser micromachining causes little influence on electrical properties of wafer. This proofof-concept process has the potential application in mass production of integrated circuit industry.