Silicon Nitride Film Transfer Technology And Fabrication Of One Dimensional Photonic Crystal Based On Porous Silicon

This project explored the tansfer technology of silicon nitrid film and its application in RF circuits and Micro-Electro Mechanical 3D integration. Meanwhile, the fabrication and characterization of 1D photonic crystal based on porous silicon was also investigated.In the first chapter the background and content of this thesis was introduced. Substrate transfer technology, which originates from SOI and applies to decreasing Si sustrate loss in RF, is helpful for the realization of three-dimensional system integration. On the other side, the most fundamental feature of photonic crystal lies in its PBG (photonic band gap) similar to the forbidden band of semiconductor and the electromagnetic wave whose frequence located in the PBG can not be propagated. Due to its various special optical features, photonic crystal is very promising for many kinds of important applications.To find out photonic crystal with wide PBG and easy fabrication method, people are continuously exploring all kinds of materials and structures.In the second chapter, the process conditions of silicon nitride film transfer technology and all-silicon 1D photonic crystal fabrication are briefly introduced. The process steps of silicon nitride film transfer technology include anodization of Si, deposition of silicon nitride, bonding via epoxy, substrate liftoff and related postprocess. The fabrication method of ID photonic crystal includes anodization of p-and n-type silicon with various current densities under aquiferous HF solution of different concentration.In the third chapter, results and discussions of substrate transfer of thick silicon nitride film were elaborated. Silicon nitride film, as thick as 1.1 μm, was successfully deposited on porous silicon by plasma enhanced chemical vapor deposition (PECVD) for the first time. No crack or curling was detected, and on the contrary, the deposited film demonstrates a good poly-crystalline structure. Such a layer was bonded to a glass substrate via a medium of optical epoxy. And finally, separation of such combined layer from the original silicon substrate via splitting of porous silicon was realized and the transmission properties before and after transfer bonding process were investigated. It is shown that such a transfer bonding process can be a good solution to the attenuation problems in silicon based RF system. Meanwhile, due to the good absorption character of silicon nitride film in the infrared band, thistechnology will also be helpful the three dimensional integration of infrared thermopile array.In the fourth chapter, the fabrication and characterization of one dimensional photonic crystal based on both p-type and n-type porous silicon has been investigated as well. Anodization of p-type silicon was carried out and porous p-type silicon omnidirectional mirror (OM) based on one dimensional photonic crystal has been materialized. As a contrast, the formation mechanism of the reflectional structure based on n-type silicon has as well been explored. Unexpectedly, under some peculiar conditions, the interfaces between high and low porosity layers become so good that they may enable the realization of the omnidirectional reflection structure formed via n-type silicon. This implies the possible fabrication of 1D photonic crystal based on n-type porous silicon, which has not yet been reported worldwidely.In the fifth chapter, some general conclusions and outlooks were given out.