TEM study of the interface of anodic-bonded Si/glass

Xing, Q.; Yoshida, M.; Sasaki, Gen

doi:10.1016/s1359-6462(02)00170-7

Cited by 22 publications

(23 citation statements)

References 10 publications

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“…3 Xing et al 3 suggested that these bands were possibly regions depleted of Na + and H + cations, involved in the mechanism. The regions grew larger as the bonding time increased, but not all of the sample micrographs showed multiple bands.…”

Section: E132mentioning

confidence: 99%

“…These authors, who concurred with Nitzsche et al, 6 suggested some of the bands might be hydrogen piling up from the leached glass layer, because H + cations can occupy the sites of depleted Na + . Xing et al, 3 hypothesized that multiple bands were not found near the interface under all the different bonding conditions because certain temperatures and bonding times gave more distinguishable H + depletion layers. EPMA results showed a depletion of Na near the interface and a diffusion of oxygen into the Si.…”

Section: E132mentioning

confidence: 99%

“…Xing et al 3 used transmission electron microscopy ͑TEM͒ and electron probe microanalysis ͑EPMA͒ to detect more than one depletion layer as Nitzsche et al 6 found. High-resolution electron microscopy ͑HREM͒ pictures were taken of Pyrex 7740 bonded to …”

mentioning

confidence: 99%

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Characterization of Si and CVD SiC to Glass Anodic Bonding Using TEM and STEM Analysis

Tudryn

Schweizer

Hopkins

et al. 2005

J. Electrochem. Soc.

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Anodic bonding is a common process used in microelectromechanical systems ͑MEMS͒ device fabrication and packaging. Polycrystalline chemical vapor deposited ͑CVD͒ silicon carbide ͑SiC͒ is emerging as a new MEMS device and packaging material because of its excellent material properties including high strength, hardness, and thermal conductivity. A novel process recipe, requiring a SiC RMS surface roughness of 45 nm, was developed for anodically bonding CVD SiC to bulk Pyrex and Hoya SD-2 glass substrates. Transmission electron microscopy ͑TEM͒ and scanning transmission electron microscopy ͑STEM͒ and elemental analysis presented distinct differences in elemental depletion band͑s͒ of bulk Pyrex and Hoya SD-2 glasses bonded to Si, and in interfacial bonding between Pyrex and CVD SiC compared to Pyrex and Si. This study indicates that magnesium in the Pyrex glass network also participates in the depletion layer process compared to previous studies where only potassium, calcium, aluminum, and sodium were identified. For the first time, this study identifies aluminum, magnesium, sodium, and zinc participating in the depletion layer process in Hoya SD-2glass.Since the invention of anodic bonding in 1969, 1 several studies have been conducted to further the understanding of the physical mechanisms involved. The following published results summarize these mechanisms, particularly in the context of the current vs. time models, and the microscopy and chemical analysis.Anodic bonding is performed with an application of a temperature and a direct current ͑dc͒ voltage to a glass and metal alloy, or semiconductor material. A typical bonding application is glass to p-type silicon ͑Si͒. The cathode is attached to the glass and the anode to the Si. The Si is at a positive potential with respect to the glass. Figure 1 shows a schematic of this electrochemical process. 2 The glass and silicon remain relatively stiff during the bonding process because temperatures below the melting point and glass transition point are used. 2 This irreversible bonding process produces a permanent, SiO 2 chemical bond at the glass/Si interface. [3][4][5] With the application of temperature and voltage, two types of reactions occur to form this SiO 2 bond: ion dissociation/association reactions and interfacial bonding reactions. 6 The elevated temperature permits ionic conduction within the glass, while the imposed potential drives the migrating ions of opposite charge towards the interface or towards the cathode. The glass behaves as an electrolyte at elevated temperatures due to the mobile ion species. The cations, principally Na, move through the glass toward the negatively charged cathode. Because the cations move toward the cathode, a depletion layer is formed, and the glass network reconstructs. This reconstruction allows for the excess anionic oxygen species, under the influence of the electrostatic potential, to move towards the interface. The space charging of the depletion layer generates an interfacial electrostatic field. These electrostatic ...

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Section: E132mentioning

confidence: 99%

Section: E132mentioning

confidence: 99%

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Characterization of Si and CVD SiC to Glass Anodic Bonding Using TEM and STEM Analysis

Tudryn

Schweizer

Hopkins

et al. 2005

J. Electrochem. Soc.

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“…The Na + and O 2-are driven by electric field and move towards the cathode and anode, respectively. A depletion layer is formed in the glass near the silicon side [13][14][15][16]. The O 2-will be deposited on the anode surface and reacts with the silicon atoms to form a thin layer of oxide because of the blocking of silicon atoms.…”

Section: Introductionmentioning

confidence: 99%

Morphology and stress at silicon-glass interface in anodic bonding

Tang

Cheng

Ming

et al. 2016

Applied Surface Science

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“…10 The basic mechanism is the thermal activation of alkali and oxygen ions and their drift in the electric field applied during bonding. 11,12 This generates a high electric field within the depletion region and forms homogeneous and reliable bonds through strong electrostatic attraction at the interface.…”

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confidence: 99%

Nanoporous Anodic Alumina Film on Glass: Improving Transparency by an Ion-Drift Process

Park

Lee

Cho

et al. 2005

Electrochem. Solid-State Lett.

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A novel method for increasing the transparency of an anodic aluminum oxide film on glass is demonstrated. The residual aluminum layer, which limits the transparency of the porous aluminum oxide film, was fully converted to its oxide by the ion-drift process. The transmittance of the film was improved more than 20% over the visible-near infrared range and was similar to that of a glass substrate. This ion-drift process also improved the adhesion of the anodic alumina film to the glass substrate.Nanoporous anodic aluminum oxide films are of great interest in various applications because of their stability and unique structural and optical properties. 1,2 As their applications grow, specific requirements for the preparation of anodic alumina film are increased. For example, a transparent porous anodic alumina film on glass is highly desired in optical and optoelectronic devices.The anodization of an aluminum film on an insulating substrate always leaves an unoxidized aluminum metal and results in a semitransparent ͑dark colored͒ anodic alumina film. Miney et al. estimate the thickness of the unoxidized aluminum layer to be ϳ1.2 nm from an ellipsometric study. 3 Although the remaining aluminum layer is very thin, the transmittance of the anodic alumina film rarely exceeds 60%, as aluminum is one of the most optically dense metals.Nearly all the previous work on complete anodization of aluminum films on insulating substrates was done by inserting a conducting medium between the substrate and the aluminum layer. Very thin layers of valve metals, such as titanium, 4 niobium, 5 and tantalum, 6,7 were introduced for this purpose. However, this produces a bulge of valve metal oxide and leaves the unoxidized layer that also reduces the transmittance. Chu et al. utilizes a transparent indium-tin oxide ͑ITO͒ layer as a conducting medium and the transmittance of the anodic alumina film was nearly equivalent to that of ITO glass. 8 It was found to be very difficult to prepare a uniform, large area anodic alumina film, however. Temperature, electric field, and the thickness of aluminum and conducting films must be uniform over entire substrate and the anodization process must be critically controlled. Otherwise, nonuniform anodization will be obtained. Also, gas evolution and sparking destroy the alumina film as the anodization reaches the Al-conducting medium interface. In addition, the adhesion between the alumina film and substrate is poor if an aluminum layer on a conducting medium is anodized. 9 This lack of adhesion may be beneficial for some purposes such as a nano-pattern transfer and preparation of free standing films, but it is highly undesirable in most applications.In other contexts, anodic bonding is widely used in microsystem technology to join glass and silicon. 10 The basic mechanism is the thermal activation of alkali and oxygen ions and their drift in the electric field applied during bonding. 11,12 This generates a high electric field within the depletion region and forms homogeneous and reliable bonds through...

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TEM study of the interface of anodic-bonded Si/glass

Cited by 22 publications

References 10 publications

Characterization of Si and CVD SiC to Glass Anodic Bonding Using TEM and STEM Analysis

Characterization of Si and CVD SiC to Glass Anodic Bonding Using TEM and STEM Analysis

Morphology and stress at silicon-glass interface in anodic bonding

Nanoporous Anodic Alumina Film on Glass: Improving Transparency by an Ion-Drift Process

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