Development of inorganic room temperature bonding technique to realize bonding interface having high light transmittance and adjustable refractive index

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02612
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Tohoku University
• Principal Investigator: Shimatsu Takehito 東北大学, 学際科学フロンティア研究所, 教授 (50206182)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 原子拡散接合法 / 室温接合 / 光透過率 / 接合強度 / 屈折率 / 耐光性 / 光学デバイス / 光学部品

Outline of Final Research Achievements

By applying atomic diffusion bonding using sub-nanometer thick ultra-thin metal films, optical wafers with an underlying oxide film were bonded at room temperature. Then, by performing post-bonded annealing at a temperature of 300°C or less, we have developed a technique to oxidize the ultra-thin metal films used for bonding. In this technique, it was also possible to adjust the refractive index by selecting the type of underlying oxide film according to the refractive index of the optical wafer to be bonded. As a result, we have realized a inorganic low-temperature bonding technology that has a completely transparent bonding interface with excellent light resistance.

Free Research Field

室温接合

Academic Significance and Societal Importance of the Research Achievements

原子拡散接合法は日本発の室温接合技術であり，一部は量産にも利用され始めている．今回，この接合技術を用いて下地酸化膜を形成した光学ウエハを接合することで，完全透明で耐光性の優れた接合界面を有する完全無機の低温接合技術を実現した．接合する光学ウエハの屈折率に合わせて下地酸化膜の種類を選択することで屈折率調整も可能である．この接合技術を用いることで，レーザ等の高輝度光に用いる新たな光学部品や光学デバイスの形成が可能となる．