Low temperature bonding of heterogeneous materials using Al2O3 as an intermediate layer

Sahoo, Hitesh Kumar; Ottaviano, Luisa; Zheng, Yi; Hansen, Ole; Yvind, Kresten

doi:10.1116/1.5005591

Cited by 28 publications

(21 citation statements)

References 34 publications

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“…Critical point drying (CPD) step was used in order to successfully release the MEMS. The processed wafer was then direct bonded to an InP wafer with the active material, using Al 2 O 3 as an intermediate layer [24]. The wafers were annealed at 300 • C to consolidate the wafer bonding.…”

Section: Design Of Mems Vcsel On Silicon Substratementioning

confidence: 99%

Tunable MEMS VCSEL on Silicon Substrate

Sahoo

Ansbak

Ottaviano

et al. 2019

IEEE J. Select. Topics Quantum Electron.

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We present design, fabrication and characterization of a MEMS VCSEL which utilizes a silicon-on-insulator wafer for the microelectromechanical system and encapsulates the MEMS by direct InP wafer bonding, which improves the protection and control of the tuning element. This procedure enables a more robust fabrication, a larger free spectral range and facilitates bidirectional tuning of the MEMS element. The MEMS VCSEL device uses a high contrast grating mirror on a MEMS stage as the bottom mirror, a wafer bonded InP with quantum wells for amplification and a deposited dielectric DBR as the top mirror. A 40 nm tuning range and a mechanical resonance frequency in excess of 2 MHz are demonstrated.

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Section: Design Of Mems Vcsel On Silicon Substratementioning

confidence: 99%

Tunable MEMS VCSEL on Silicon Substrate

Sahoo

Ansbak

Ottaviano

et al. 2019

IEEE J. Select. Topics Quantum Electron.

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“…To extend the operation wavelength range of AlGaAs material, sapphire can be used as the substrate material. We also developed Al2O3-assisted direct wafer bonding (DWB) process for fabricating AlGaAs-onsapphire wafers [16]. The fabrication processes for both AlGaAsOI wafers are shown in Figure 1.…”

Section: Aluminum Gallium Arsenide-on-insulator Platformmentioning

confidence: 99%

Nano-engineered high-confinement AlGaAs waveguide devices for nonlinear photonics

Zheng

Stassen

et al. 2018

Nanophotonics VII

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The combination of nonlinear and integrated photonics enables applications in telecommunication, metrology, spectroscopy, and quantum information science. Pioneer works in silicon-on-insulator (SOI) has shown huge potentials of integrated nonlinear photonics. However, silicon suffers two-photon absorption (TPA) in the telecom wavelengths around 1550 nm, which hampers its practical applications. To get a superior nonlinear performance, an ideal integrated waveguide platform should combine a high material nonlinearity, low material absorption (linear and nonlinear), a strong light confinement, and a mature fabrication technology. Aluminum gallium arsenide (AlGaAs) was identified as a promising candidate for nonlinear applications since 1994. It offers a large transparency window, a high refractive index (n≈3.3), a nonlinear index (n2) on the order of 10 -17 m 2 W −1 , and the ability to engineer the material bandgap to mitigate TPA. In spite of the high intrinsic nonlinearity, conventional deep-etched AlGaAs waveguides exhibit low effective nonlinearity due to the vertical low-index contrast. To take full advantage of the high intrinsic linear and nonlinear index of AlGaAs material, we reconstructed the conventional AlGaAs waveguide into a high index contrast layout that has been realized in the AlGaAs-on-insulator (AlGaAsOI) platform. We have demonstrated low loss waveguides with an ultra-high nonlinear coefficient and high Q microresonators in such a platform. Owing to the high confinement waveguide layout and state-of-the-art nanolithography techniques, the dispersion properties of the AlGaAsOI waveguide can be tailored efficiently and accurately by altering the waveguide shape or dimension, which enables various applications in signal processing and generation, which will be reviewed in this paper.

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“…The ALD AlO surface is treated with water, vapor, or oxygen plasma to achieve hydrophilic surfaces, followed by the post-bonding annealing at 200-330°C for bonding of Si, SiO 2 , and III-V photosemiconductors. [30][31][32][33] Even though the hydrophilic bonding via ALD AlO intermediate layer achieves the transparent bonding interface, the heating process is still required for the postbonding annealing and ALD process.…”

Section: Introductionmentioning

confidence: 99%

Room Temperature Wafer Bonding of Glass Using Aluminum Oxide Intermediate Layer

Takeuchi

Matsumoto³

et al. 2021

Adv Materials Inter

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applications, the glass bonding should not deteriorate the transparency at the interface for efficient light transmission. Moreover, voids at the bonding interface are obstacles as they lead to a topical decrease in transparency. For these reasons, the indirect bonding of glass using adhesive including epoxy and UV-curing resins is not appropriate since the adhesive layer deteriorates the optical characteristics and the sealing performance especially against water permeation. Hence, a direct glass bonding is highly required for the fabrication of reliable applications. The direct bonding of glass has been studied for a long time. One popular method is hydrophilic bonding, in which the glass surfaces are treated to achieve OH groups, followed by the post-bonding annealing at over 600 °C to achieve covalent bonds between the glass surfaces. In this method, the OH groups and water on the bonding surfaces are decomposed and the generated H 2 diffuses into the amorphous structure of glass (2Si-OH  →  Si-O-Si + H 2 O, Si + 2H 2 O  →  SiO 2 + 2H 2). [10-12] However, the high temperature annealing process will lead to damage at the bonding interface, which is induced by residual stress due to the mismatch of the coefficient of thermal expansion. The high temperature process also leads to damage to heat-sensitive components including electrodes, enzymes, and light sources. Furthermore, the decomposed H 2 O and OH groups can be trapped at the bonding interface, resulting in interfacial voids. [10,13] Therefore, glass bonding at room temperature is a desirable process. In order to lower the post-bonding annealing temperature, hydrophilic bonding has been modified mainly by using surface activation such as plasma and UV in the previous studies. The surface activation using O 2 and/or N 2 plasmas has been widely investigated to increase the OH groups on the glass surface. [14-16] For the surface activation by UV irradiation, the organic contamination on the surface is removed using O 3 induced by UV. In the meantime, the hydrophilicity of the glass surface is improved. [17,18] However, since the hydrophilic bonding mechanism is the polymerization of OH groups, a post-bonding annealing at over 200 °C is usually necessary for strong bonding. Recently, surface activated bonding (SAB) has been developed to bond inorganic materials at room temperature. [19-21] In its standard process, the bonding surfaces are treated with This paper presents a room temperature bonding technique of glass substrates with a transparent bonding interface. As a room temperature bonding method, surface activated bonding (SAB) is applied for the bonding of glass using Si intermediate layer. However, the bonding interface is colored by the deposited Si layers, which leads to lower applicability to optical devices. In this study, a new concept of SAB is developed using aluminum oxide intermediate layer. Glass substrates are successfully bonded at room temperature via the aluminum oxide intermediate layers activated by Ar ion beam irradiation, showing a...

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Low temperature bonding of heterogeneous materials using Al2O3 as an intermediate layer

Cited by 28 publications

References 34 publications

Tunable MEMS VCSEL on Silicon Substrate

Tunable MEMS VCSEL on Silicon Substrate

Nano-engineered high-confinement AlGaAs waveguide devices for nonlinear photonics

Room Temperature Wafer Bonding of Glass Using Aluminum Oxide Intermediate Layer

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