[19p-Z07-1~9] 3.7 Laser processing

[19p-Z07-3] Control of oxidation in Cu micropatterning using femtosecond laser reductive sintering of CuO nanoparticles

〇Kyouhei Yoshidomi¹, Mizue Mizoshiri¹ (1.Nagaoka Univ. of Tech.)

Keywords:Femtosecond laser sintering, Cu patterning, Control of oxidation

High purity Cu micropatterns were fabricated using femtosecond laser-induced reduction of CuO nanoparticles by controlling the atmosphere and pulse burst irradiation. CuO nanoparticle paste was spin-coated onto a glass substrate, and near-infrared femtosecond laser pulses were focused with a pulse energy of 0.74 nJ. First, the patterns were fabricated with a scanning speed of 5 mm/s and N₂ and Ar gas flow rates of 0-125 mL/min. The degree of reduction increased by increasing of the flow rates, indicating that the reoxidation of the patterns were induced by atmospheric oxygen in air. Line patterns were produced by pulse burst irradiation with a repetition rate of 0.80 MHz and a burst rate of 12.5 ns at a pulse rate of 20-100 and a scanning speed of 1 mm/s. Cu patterns were generated successfully under the condition that the number of the burst pulses were more than 30. The results also suggest that heat accumulation and thermal diffusion can be reduced.