| 摘要 |
PROBLEM TO BE SOLVED: To increase the difference between the refractive index of a core and the refractive index of a clad layer by forming a buffer layer by using an SiO2 film doped with fluorine, forming a core film thereon and subjecting the film to a heat treatment. SOLUTION: The buffer layer 21 consisting of the F-doped SiO2 film is formed on a substrate 20 and the core film 22a consisting of the N-doped SiO2 film is formed thereon and is subjected to the heat treatment. The heat treatment tap. of this time is set at a high temp. of about 1200 deg.C. A WSi film 25a is formed on the core film 22a and photoresist patterns 26 are formed thereon. The WSi patterns 25 are formed by using the photoresist patterns 26 as a mask and the cores 22 having an approximately rectangular sectional shape are formed by patterning the core film 22a with the WSi patterns 25 as a mask. The WSi patterns 25 on the cores 22 are peeled. The surfaces of the buffer layers 21 and the cores 22 are covered with clad layer 23 consisting of the F-doped SiO2 film. |
