| 摘要 |
<p>PURPOSE:To prevent generating microcrack by scanning sub laser beam of low energy density before, or before and after main laser beam is scanned along a scribing line of a semiconductor wafer. CONSTITUTION:A wafer 2 is mounted on an X-Y table 1 and is shifted by shift signal MS in a controlling circuit 3. A power supply 5 of a laser oscillator 4 is started by signal KS and a flash light 6 illuminates and the illuminated pulse is condensed 7 and YAG laser 8 is irradiated, then optical excitation is performed. A excited laser beam is taken out through a resonant mirror 10 and Q-switch 11 and focused 16 on the wafer 2 through lenses 13, 14 and a total reflection mirror. A lens 16 is devided into A-C sections whose optical axises and focuses are different and each B and C area is about one third of A area. Passing beams are separated to 9a-9c and are focused to three points (a)-(c) respectively on a wafer. Main beam is beam 9a. As the wafer is pre-heated by the sub beam 9b or 9c, before being irradiated by the main beam 9a, microcrack is not generated by processing heat and also yield and quality are improved.</p> |
