Laser cleaning technology of the contact hole for semiconductor manufacturing

Abstract

The laser cleaning of the photoresist (PR) layer has been investigated as a function of laser energy density. The cleaning of the PR layer on silicon wafer was performed by a line beam of a KrF excimer laser in a cleanroom environment and then the applied energy density was 100 - 300 mJ/cm². The experimental results showed that the ablation rates of the PR are increased with increasing of laser energy density without silicon wafer damage. The ablation rates of PR were 0.09 μm/pulse for 100 mJ/cm², 0.15 μm/pulse for 200 mJ/cm² and 0.19 μm/pulse for 300 mJ/cm² with repetition rate of 30 Hz. The compositions of the PR covered wafers before and after laser irradiation were determined by Fourier transform infrared spectroscopy (FT-IR). The comparison of the cleaning results done in applying the laser cleaning to remove the PR and the metallic polymers resulting from reactive ion etching (RIE) was made before and after laser irradiation by scanning electron microscope (SEM). It is also shown that the PR and metallic polymer in the contact hole can be completely removed by the laser cleaning technique.