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Direct bonding

About: Direct bonding is a research topic. Over the lifetime, 2065 publications have been published within this topic receiving 25136 citations.


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Journal ArticleDOI
TL;DR: In this paper, it was found that strong bonding takes place when a pair of clean, mirror-polished silicon surfaces are contacted at room temperature after hydrophilic surface formation.
Abstract: It was found that strong bonding takes place when a pair of clean, mirror‐polished silicon surfaces are contacted at room temperature after hydrophilic surface formation. Bonding strength reaches the fracture strength of silicon bulk after heating above 1000 °C. Electric resistivity at the interface is less than 10−6 Ω/cm2. Bonding p‐type silicon to n‐type silicon forms a diode. The reaction between silanol groups formed on the surface may cause the bonding force. Heating above 1000 °C was thought to diffuse oxygen to inside the silicon bulk, forming an epitaxial‐like lattice continuity at the interface.

517 citations

Journal ArticleDOI
01 Aug 1998
TL;DR: Wafer-to-wafer bonding processes for microstructure fabrication are categorized and described in this article, which have an impact in packaging and structure design, including direct bonds, anodic bonds and bonds with intermediate layers.
Abstract: Wafer-to-wafer bonding processes for microstructure fabrication are categorized and described. These processes have an impact in packaging and structure design. Processes are categorized into direct bonds, anodic bonds, and bonds with intermediate layers. Representative devices using wafer-to-wafer bonding are presented. Processes and methods for characterization of a range of bonding methods are discussed. Opportunities for continued development are outlined.

478 citations

Journal ArticleDOI
A Plößl1
TL;DR: In this article, the authors provide an overview of the current understanding of the factors determining the bondability and strength of the bonding obtainable and assess the present state of the experimental methods for determining basic parameters governing the adhesion.
Abstract: It is a well-known phenomenon that two solids with sufficiently flat surfaces can stick to each other when brought into intimate contact in ambient air at room temperature. The attraction between the two bodies is primarily mediated through van der Waals forces or hydrogen bonding. Without a subsequent heating step, that type of bonding is reversible. Annealing may increase the energy of adhesion up to the cohesive strength of the materials concerned. The wafer bonding phenomena in brittle materials systems, especially in silicon, is reviewed in the experiment. The focus is on low temperature bonding techniques. The pivotal influence chemical species on the surfaces have on the subsequent type of bonding (van der Waals, hydrogen, covalent bonding, mechanical interlocking) is discussed. Methods of modifying the surface chemistry for tailoring bonding properties are addressed. The paper is aimed at providing an overview of the current understanding of the factors determining the bondability and strength of the bonding obtainable. The authors assess the present state of the experimental methods for determining basic parameters governing the adhesion. A number of examples illustrate the applicability of fusion bonding for as diverse fields as opto-electronics, microsystems technology, and fabrication of advanced substrates like silicon-on-insulator wafers.

389 citations

Journal ArticleDOI
TL;DR: In this paper, a magneto-optical isolator is demonstrated for use with a Si waveguide, which is based on a Mach-Zehnder interferometer employing a non-reciprocal phase shift.
Abstract: A magneto-optical isolator is demonstrated for use with a Si waveguide. The isolator is based on a Mach–Zehnder interferometer employing a nonreciprocal phase shift and is fabricated by bonding a magneto-optic garnet CeY2Fe5O12 (Ce:YIG) directly onto the Si waveguide. The surface-activated bonding is based on oxygen-plasma exposure in a high-vacuum chamber. The nonreciprocal phase shift is observed by applying an external magnetic field. An isolation ratio of 21dB is obtained at a wavelength of 1559nm.

319 citations

Journal ArticleDOI
TL;DR: In this paper, a new method for fabricating capacitive micromachined ultrasonic transducers (CMUTs) that uses a wafer bonding technique is introduced. But the method is not suitable for large CMUTs.
Abstract: Introduces a new method for fabricating capacitive micromachined ultrasonic transducers (CMUTs) that uses a wafer bonding technique. The transducer membrane and cavity are defined on an SOI (silicon-on-insulator) wafer and on a prime wafer, respectively. Then, using silicon direct bonding in a vacuum environment, the two wafers are bonded together to form a transducer. This new technique, capable of fabricating large CMUTs, offers advantages over the traditionally micromachined CMUTs. First, forming a vacuum-sealed cavity is relatively easy since the wafer bonding is performed in a vacuum chamber. Second, this process enables better control over the gap height, making it possible to fabricate very small gaps (less than 0.1 /spl mu/m). Third, since the membrane is made of single crystal silicon, it is possible to predict and control the mechanical properties of the membrane to within 5%. Finally, the number of process steps involved in making a CMUT has been reduced from 22 to 15, shortening the device turn-around time. All of these advantages provide repeatable fabrication of CMUTs featuring predictable center frequency, bandwidth, and collapse voltage.

312 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202236
202172
202074
2019107
201889