| 摘要 |
PURPOSE:To reduce the steps and to improve the accuracy by irradiating a laser light of photoenergy smaller than the forbidden band width of a semiconductor wafer and melting or evaporating a metal thin film on the rear surface of the wafer to form a pattern. CONSTITUTION:A laser light 8 irradiated from a YAG laser oscillator 1 is focused at an arbitrary position on a GaAs wafer 4 in a predetermined spot size and irradiated through a mirror system 2 and a lens system 3. The light 8 is irradiated to a region where no surface electrode 5 exists on the wafer 4 at this time. The light 8 is absorbed to a rear surface electrode 6 on the rear surface of the wafer through the wafer 4 to be converted to heat. Thus, the electrode 6 is melted or evaporated by the heat to be able to form a recognition pattern on the electrode 6.
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