| 摘要 |
PROBLEM TO BE SOLVED: To prevent the complication of production stages and structures, to improve reproducibility as a device and to prevent the increase of the cost of the device by exposing a silicon substrate to oxygen which is formed as plasma or is activated or gas having oxygen atoms in molecules, thereby oxidizing this silicon substrate. SOLUTION: A masking layer 2 opened only in the region to constitute an optical waveguide is disposed on the silicon substrate 1. The masking layer 2 is formed by making the region 3 to constitute the optical waveguide porous by an anodic chemical conversion treatment. The silicon substrate 1 is carried into a vacuum apparatus in order to remove moisture sticking to the surface of the porous silicon region 3. The substrate is then heated up to 200 to 400 deg.C in the state of <=5×10<-3> Torr and further vacuum evacuation is executed down to <=5×10<-6> Torr. The substrate is heated up to 300 to 500 deg.C and the oxygen is introduced into the apparatus. The introduced gas is thereafter activated or converted to the plasma by RF or electron cyclotron, microwaves, etc., and the silicon substrate 1 is exposed into this atmosphere, by which the oxidation of the region 3 made porous is executed. |
