| 摘要 |
<p>Conventionally, it has been difficult to strictly control the depth of a groove in diffraction grating by normal etching when creating a grating coupler, thereby leading to a problem in which manufacturing tolerance is small. In this production method for a grating coupler, an SOI substrate is prepared, a dielectric layer (112) is formed in a grating coupler formation region, a polysilicon layer (130) is subsequently formed, and a plurality of grooves (150) that constitute a diffraction grating section are formed in the polysilicon layer (130) by etching. On this occasion, the dielectric layer (112) functions as an etching stopper when forming the grooves (150) and thereby eliminates variation in etching depth. An upper clad layer (116) that fills the grooves (150) is subsequently formed. This production method can also be applied to a multistage configuration in which the grooves are made shallower in the vicinity of an edge section of the grating coupler formation region.</p> |
