| With the rapid development of information communication and optical communication technology,integrated photonics plays a key role in optical communication system,which has attracted extensive attention.Single crystal Lithium Niobate（LN）,with excellent electro-optic properties and nonlinear optical properties,has undoubtedly become a promising photonic platform.The heterogeneous integration of Si and LN is compatible with the mature process of Si photons and the excellent optical properties of LN,providing a new solution for the realization of low-cost,high-quality integrated optoelectronic devices.In this thesis,Benzocyclobutene（BCB）was selected as the intermediate layer,and the heterogeneous bonding process of BCB based Si and LN block material was explored in detail through experiments,and the process was applied to the heterogeneous integration between Si substrate and LN thin film microring resonator.The effect of device’s performance after integration was explored using the optical test platform.The main research contents and experimental results are as follows:（1）BCB was taken as the middle layer,and the thickness of BCB bonding was controlled by adjusting the process parameters.In traditional BCB bonding,the thickness of BCB bonding layer is usually in the micron level,and the thick middle layer thickness is not conducive to optical coupling in integrated optical devices,which will affect the performance of device.In order to make sure the thickness of BCB intermediate layer is at sub-micron level,BCB was diluted with Mesitylene and speed of spin coating was adjusted.SEM and other characterization methods were used to obtain the relationship between the thickness of BCB and parameters,the rule of BCB layer thickness was controlled.BCB bonding layer’s thickness of 150 nm was obtained at high dilution ratio and rotational speed.By controlling the thickness of BCB intermediate layer,the bonding of LN optical device and Si can be flexibly assembled according to the specific structure size of device.（2）Plasma activation technology and curing temperature ensured the strength of Si and LN bonded samples.In order to reduce the thickness of BCB intermediate layer,the spin coating and pre-bonding process of BCB would be affected,thus the bonding quality would be influenced,and the influence of thermal mismatch would be more significant.In this thesis,plasma activation technology was used to treat the Si substrate surface and BCB interface layer.Contact Angle measurement was used to characterize the wettability and adhesion properties of the interface of the bonding surface,and the spin-coating effect and pre-bonding effect of BCB on the substrate surface were improved under high rotational speed and dilution ratio parameters.On this basis,fragmentation of LN caused by thermal mismatch was solved by adjusting annealing temperature curve.Tensile test was used to characterize the bonding strength of bonded samples with different parameters,and the bonding strength remained above 3MPa,which verified the reliability of the process.（3）Simulation design and fabrication of LN thin film microring resonator,optical testing platform was used to test and analyze the device performance before and after bonding.The structure size of 20 GHz microring resonator was designed by COMSOL simulation.LN thin film microring resonator was prepared by micro-nano machining technology.The Extinction ratio of the microring resonator is 6.981 d B,the Q value is86123.63 and the transmission loss is 0.4150 d B/cm.Based on the above process,the heterointegration of LN thin film microring resonator and Si substrate was realized,and the test was carried out on the optical platform again.The Q value of the microring resonator was reduced to 43060.56 and the transmission loss was changed to1.3511 d B/cm,but the extinction ratio increases to 11.383 d B,which verified the feasibility of heterointegration of LN optical device with Si based on BCB. |
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