Residual Stress in Lithium Niobate Film Layer of LNOI/Si Hybrid Wafer Fabricated Using Low-Temperature Bonding Method
Residual Stress in Lithium Niobate Film Layer of LNOI/Si Hybrid Wafer Fabricated Using Low-Temperature Bonding Method
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DOI：
10.3390/mi10020136
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发表时间：
2019-02-01
期刊：
影响因子：
3.4
通讯作者：
Asano, Tanemasa
中科院分区：
文献类型：
--
作者：
Takigawa, Ryo;Tomimatsu, Toru;Asano, Tanemasa
研究了绝缘体上锂（LNOI）/硅混合晶片中锂氧化物（LN）薄膜层的残余应力。该应力源自层的热膨胀系数之间的大的失配。一种改进的表面活化键合方法实现了薄膜LNOI/Si混合晶片的制造。这种在100 ℃下的低温结合方法显示出LN和SiO2层之间的强结合，其足以承受使用常规机械抛光将晶片薄化至约5 μ m的LN厚度。利用显微拉曼光谱，在这种三层结构（LN/SiO2/Si）的键合LN膜中的残余应力进行了研究。测得的LN膜层中的残余拉伸应力约为155 MPa，这与通过应力分析计算出的值相似。本研究将有助于各种异质集成LN微器件的开发，包括硅基LNOI集成光子器件。
This paper focuses on the residual stress in a lithium niobate (LN) film layer of a LN-on-insulator (LNOI)/Si hybrid wafer. This stress originates from a large mismatch between the thermal expansion coefficients of the layers. A modified surface-activated bonding method achieved fabrication of a thin-film LNOI/Si hybrid wafer. This low-temperature bonding method at 100 degrees C showed a strong bond between the LN and SiO2 layers, which is sufficient to withstand the wafer thinning to a LN thickness of approximately 5 m using conventional mechanical polishing. Using micro-Raman spectroscopy, the residual stress in the bonded LN film in this trilayered (LN/SiO2/Si) structure was investigated. The measured residual tensile stress in the LN film layer was approximately 155 MPa, which was similar to the value calculated by stress analysis. This study will be useful for the development of various hetero-integrated LN micro-devices, including silicon-based, LNOI-integrated photonic devices.