Through-hole processing of silicon wafer using high power short pulse laser

Fine processing of silicon using high-power short-pulse laser has been studied. Through-holes are formed on silicon wafer by irradiation of the laser pulses, and the relationship between hole shapes and the laser-beam characters has been studied. The hole shape strongly depends on the beam profile, pulse width and wave length. Ultra-short (60fs) laser pulses shaped by image-relay technique give better results, namely, good shape and high speed. If the wavelength is short, processing using longer pulse laser (350ps) is also possible, although it often causes damage of the wafer. The data shown here indicate the advantage of ultra-short laser for the fine processing of silicon. (author)