Low-k 웨이퍼 레이저 인그레이빙 특성에 관한 연구

Study on low-k wafer engraving processes by using UV pico-second laser

  Low-k wafer engraving process has been investigated by using UV pico-second laser with high repetition rate. Wavelength and repetition rate of laser used in this study are 355㎚ and 80㎒, respectively. Main parameters of low-k wafer engraving processes are laser power, work speed, assist gas flow rate, and protective coating to eliminate debris. Results show that engraving qualities of low-k layer by using UV pico-second pulse width and high repetition rate had better kerf edge and higher work speed, compared to one by conventional laser with nano-second pulse width and low repetition rate in the range of ㎑. Assist gas and protective coating to eliminate debris gave effects on the quality of engraving edge. Total engraving width and depth are obtained less than 20㎛ and 10㎛ at more than 500㎜/sec work speed. respectively. We believe that engraving method by using UV pico-second laser with high repetition rate is useful one to give high work speed of laser material process.