| 摘要 |
PURPOSE:To cleanse the surface of the first upper clad layer by a method wherein a striped groove in such a depth as to leave a part of the protective layer, which has the same conductive type as that of the second growth layer or is non-doped, is formed in the etching process and impurities adhered on the surface of the semiconductor substrate and the protective layer left are made to evaporate in the thermal cleaning process. CONSTITUTION:A first growth layer 20 is laminated on a semiconductor substrate 10 in an MBE device, the laminated material is drawn out outside and a lapping is performed on the back surface of the semiconductor substrate 10. Then, a selective etching is respectively performed on an evaporation preventing layer 26 and a photo absorption layer 25 using a photo resist 60 as a mask and a striped groove 30 is formed in such a depth as to leave a pat of a protective layer 24 and in the desired width. The laminated material is again installed in the MBE device. Here, the semiconductor substrate 10 is heated at 720 deg.C or more while arsenic molecular beams are irradiated on the semiconductor substrate 10 and such impurities as oxides adhered on the surface of the semiconductor substrate 10 and the protective layer 24 left are made to evaporate, whereby the striped groove 30 is formed into a striped groove 31 to reach up to a first clad layer 23. The temperature is set at about 600 deg.C and a second growth layer 40 consisting of a second upper P-type AlyGa1-yAs clad layer 41 and a P<+> type GaAs layer 42 is laminated.
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