| 摘要 |
PURPOSE:To prevent the propagation loss and to easily control the line width for patterning by forming a core part of an upper layer after making a clad layer, which separates a core of a lower layer and that of the upper layer from each other, flat. CONSTITUTION:A light propagating glass layer 2 having a refractive index higher than that of a clad layer 1 is formed on the surface of the substrate clad layer 1 by vapor-phase chemical reaction or the like. The glass layer 2 is patterned by photolithography to form waveguides indicated by core layers 2a-2c. A clad layer 3 is accumulated on core layers 2a, 2b, 2c... by vapor-phase chemical reaction, and a resist 6 is spin-coated on the clad layer 3 to make the resist surface flat. The resist 6 and the clad layer 3 are etched at a uniform speed in this state by ion etching or reactive ion etching using gaseous CF4+O2 while controlling etching conditions, thereby forming the clad layer 3 having a flat surface. |
