| 摘要 |
PURPOSE:To improve the controllability of etching depth by continuously carrying out etching with a gas having relatively low reactivity and etching with a gas having relatively high reactivity in an etching stage at the time of forming a rib part. CONSTITUTION:First clad layer 2 of Al0.5Ga0.5As is grown on a GaAs substrate 1 and waveguide layer 3 of AlGaAs and a second clad layer 4 of Al0.5Ga0.5As are formed on the layer 2. A photoresist mask having the shape of a waveguide to be formed on the layer 3 is then formed on the layer 4 and the part of the layer 4 not covered with the mask is etched with a gas having low reactivity in a first etching stage. The etched part is further etched with a gas having high reactivity in a second etching stage. Since clean etched surfaces having the same state are always obtd. after the first etching stage and then second etching is carried out, the controllability of etching depth is improved. |
