The use of minenvironment in the CMP process of optical wavegukdes

摘要

Optical waveguides play a very important role in fiberoptic telecommunications and data transmissions. When light passes through optical fibers into these waveguides, most of the light is transmitted, but a fraction of this light will be reflected by the end surface of waveguides due to changes in the refractive indexes of different media (i.e., glass and air). In order to minmize noise caused by this reflected ligh interfering with the incoming light signals, the ends of these waveguides are lapped and polished 8 degree off from their normal plane so that the reflected light will not come back into the waveguides. When this chemicalmechanical polishing (CMP) process is operated in a noncleanroom environment, however, contaminants in the air can enter the stream of the wet slurry and often cause defects to the polished surface of the optical devices. Therefore, a Class 1 (at 0.2 mum) mini-environment with variable flow velocity and static pressure has been employed to control contamination. This CMP enclosure is used in a non-cleanroom environment. Test results show that when the mini-environment is used, surface damage is drastically reduced, surface cleanliness and smoothness are greatly enhanced, and the process time shortened. By using mini-environments in this CMP application the overall product functional yield can be drastically increased without building an expensive cleanroom.