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Investigation Of Low-Temperature Wafer Bonding And Long-Wavelength Tunable Integrated Optical Demultiplexing And Receiving Device For WDM Application

Posted on:2008-09-03Degree:DoctorType:Dissertation
Country:ChinaCandidate:W J WangFull Text:PDF
GTID:1118360215483668Subject:Electromagnetic field and microwave technology
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The research in this thesis is supported by grants from The National Basic Research Program of China(No.2003CB314902), The National High Technology Research and Development Program of China(No: 2003AA31g050 and 2003AA312020), Key Program project of the National Natural Science Foundation of China(No.90201035) and the project of the National Natural Science Foundation of China(No: 60576018).With the rapid development of information technology, it's becoming an urgent need for large capability, high speed transmission and management. Substituting photon for electron, photon technology or optoelectronic technology for micro-electronic technology, and developing optical integration or optoelectronic integration will push information technology to a brand-new period. In this thesis, a great deal of research work can be described as follow: low-temperature wafer bonding process, designing and fabrication of novel WDM integrated demultiplexing and receiving device. The main achievements are listed as follows.1. Under the bonding condition deduced from minimum energy principle, the effect of macro-scale wafer bow and micro-scale wafer waviness on wafer bonding process were modeled through linear elastic thin plate theory. The simulated results were discussed as follows: for wafers with a little camber, the flatness of the bonding interface was decided by the flatness of the thicker wafer, leaving elastic strain energy mainly in the thinner one; It's easier to bond the wafers in the edge area than in the center area, when the wafer was thinner, the difference was not obvious and the bonding area was enlarged; When the whole thickness of the two wafers were fixed, it's easier to bond with a larger thickness difference, and it's most difficult for wafers with the same thickness to bond; For wafers with micro-waviness on surface, the thinner the wafer was, the lower requirements for the surface roughness of the wafer, and it's easier for wafers to bond.2. The interfacial thermal stresses arising from wafer bonding were analysed by thermal stress theory for bimetal strip. Physical model was established, and the stresses distribution in the bonding interface of GaAs/InP,Si/InP were analysed. The calculation indicated that the shearing and peeling stresses at the interface were concentrated near the edges of the bonding pair and minished to zero when moved from the edge to the center, and it's opposite for the normal stress. By analyzing the normal stress and elastic strain energy which clearly reflected the influence of thermal stress on the wafer bonding, we concluded that reducing the annealing temperature was the most effective method to decrease the thermal stresses, and the stresses could also be decreased by thinning one or both of the wafers.3. Based on abrupt isotype semiconductor heterojunction theory, the electric characteristic of the isotype heterojunction was analysed considering the high and low density of interface states. The current density-voltage curves of n-GaAs/n-InP and n-Si/n-InP were modeled under degenerate and nondegenerate condition.4. Methods for low-temperature GaAs/InP,Si/InP,Si/Si wafer bonding using boride-treated surface were presented, which were simple and nontoxic, and the annealing temperatures were 290℃,270℃,180℃respectively. The SEM and TEM images of the cleaving interface showed that the bonded wafers were tightly adhesive, and no fracture or void occurred along the bonded interface. The current-voltage characteristics, X-ray diffraction(XRD) and photoluminescence(PL) revealed that crystal quality of the bonded MQW was preserved with little inference to the electronic and optical characteristics. Thin intermediate layers with thickness of about 17nm(GaAs/InP) and 21.56nm (Si/InP) at the bonding interface were detected by secondary ion mass spectroscopy(SIMS). X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy analyses ensured the chemical bonds on the boride-treated wafer surfaces were B-O-P,P-O-As,As-O-B,Si-O-B and P-O-Si, which would reconstruct to form a stable strcture and ensure the the strong bonding at such low temperature.5. Three methods to realize long-wavelength "One Mirror Inclined Three-Mirror Cavity" photodetector were proposed as follows: through low-temperature wafer bonding, GaAs based F-P filtering cavity was combined with InP based absorption part; A InP based micro-machined tunable photodetector with InP/air DBRstructure; A GaAs based photodetector with InGaNAs/GaAs MQW structure. Designs of the three types of photodetectors were introduced. And the fabrication and test of the first one and the third one were presented in details. For the photodetector fabricated by the first method, a spectral linewidth of 0.6nm (FWHM), an external quantum efficiency of 78.4%, a tuning range of 10.5nm and the 3dB bandwidth of 12 GHz have been achieved experimentally. For the photodetector based on the InGaNAs/GaAs MQW structure, a spectral linewidth of 3nm(FWHM) was obtained in the wavelength of 1558nm.One achievement of our group named "High-speed, narrow-linewidth and tunable integrated optical demultiplexing and receiving device and its key fabrication technologies"(including the research work of this paper) has been selected as one of the Year 2006's Chinese ten greatest science and technologies progresses of the university and colleges, and has won second class of Beijing science and technologies awards. At present, State technology invention second class awards was applied, which was under review. This achievement was authorized and high honored by the Nobel prizewinner Zhores I. Alferov, American Engineering academician Tingye Li, American Engineering academician Joe C. Campbell and Chinese Engineering academician Hequan Wu. Principal of the achievement Doctor Xiaomin Ren has been invited to report on NANO-2006 by Zhores I. Alferov academician.
Keywords/Search Tags:low-temperature wafer bonding, GaAs/InP wafer bonding, InP/Si wafer bonding, WDM demultiplexing receiving device, one-mirror inclined three-mirror cavity (OMITMiC) photodector
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