Si - Based Study On Optical Communication Devices Produced By Wet Process

According to the semiconductor Si, the etching rate of some crystallographic planes is higher than others in the special etchants. Based on this phenomenon, anisotropic wet etching method has gotten great development in the fabrication process of the Optical Communication Devices and occupied an irreplaceable position in this field. Compared with the dry etching method, the wet one costs less and is more convenient. This paper demonstrates thoroughly the theoretic analysis about the anisotropic wet etching property of the silicon material and gives details on the fabrication work of V-grooves as well as waveguides on SOI basing on the wet etching technique.An emphasis is put on the design and fabrication of the V-groove structure in this paper. Meanwhile, as the basic principles, the coupled mode theory of single-mode fiber as well as rib waveguides has been described and analyzed, and the best coupling condition is concluded serving for the proper design of the V-groove structure. During the whole experimental work, we tried the dry-wet mask-making technology, analyzed thoroughly the negative elements for the photolithography, proposed neo-technique for eliminating residue of photosensitive resist by ICP etching and found out the most appropriate compositions of the anisotropic etchant for V-groove fabricating. Finally, we made out the fiber arrays based on the V-grooves, tested the energy loss and evaluated the quality for this device.In light of the low cost as well as the easy processing technique for the wet etching method, it has been applied widely in fabricating Optical Communication Devices such as MMI (Multimode interference), Y-branches and M-Z interference device. Furthermore, combined with the dry etching method and relying on the multiple etching techniques, the wet one can be used to fabricate waveguides. Based this principle and the previous experimental work of our laboratory, this paper attempts to fabricate the AWG devices on SOI by wet etching method. Through timeafter time experiments, we found out the relationships among the etching rate, temperature, and reagent concentration and also the best reacting condition leading to the smoothness of the etching surfaces. This work makes great contribution for the extensive roughness problem resulted from the limitation of ICP machines in our lab and paves the way for the further work.