This paper gives an introduction to glass frit wafer bonding, which is an universally useable technology for encapsulation of microsystems, especially surface micromechanical sensors on wafer level. After a process description, some mechanical as well as electrical characteristics of glass frit bonded wafers are discussed and applications are shown
In this paper, wafer-to-wafer AuSi eutectic bonding was investigated and evaluated with various sets of experimental parameters. Single crystalline Si and amorphous Si were bonded with different dimension Au layers and observed by optical measurements. Material composition, adhesion layer, electrical insulation, bonding parameters, and surface pre-treatments were discussed and have improved bonding performance. Bond strength determined by micro-chevron-test and shear test was evaluated as well as hermeticity. High bond yield was achieved with 4 inch and 6 inch wafer stacks
In this paper, a novel wafer-level hermetic packaging technology for heterogeneous device integration is presented. Hermetic sealing is achieved by low-temperature thermo-compression bonding using electroplated Au micro-sealing frame planarized by single-point diamond fly-cutting. The proposed technology has significant advantages compared to other established processes in terms of integration of micro-structured wafer, vacuum encapsulation and electrical interconnection, which can be achieved at the same time. Furthermore, the technology is also achievable for a bonding frame width as narrow as 30 μm, giving it an advantage from a geometry perspective, and bonding temperatures as low as 300 °C, making it advantageous for temperature-sensitive devices. Outgassing in vacuum sealed cavities is studied and a cavity pressure below 500 Pa is achieved by introducing annealing steps prior to bonding. The pressure of the sealed cavity is measured by zero-balance method utilizing diaphragm-structured bonding test devices. The leak rate into the packages is determined by long-term sealed cavity pressure measurement for 1500 h to be less than Pa m3s−1. In addition, the bonding shear strength is also evaluated to be higher than 100 MPa.
This paper presents the optical design of a miniature 3D scanning system, which is fully compatible with the vertical integration technology of micro-opto-electro-mechanical systems (MOEMS). The constraints related to this integration strategy are considered, resulting in a simple three-element micro-optical setup based on an afocal scanning microlens doublet and a focusing microlens, which is tolerant to axial position inaccuracy. The 3D scanning is achieved by axial and lateral displacement of microlenses of the scanning doublet, realized by micro-electro-mechanical systems microactuators (the transmission scanning approach). Optical scanning performance of the system is determined analytically by use of the extended ray transfer matrix method, leading to two different optical configurations, relying either on a ball lens or plano-convex microlenses. The presented system is aimed to be a core component of miniature MOEMS-based optical devices, which require a 3D optical scanning function, e.g., miniature imaging systems (confocal or optical coherence microscopes) or optical tweezers.
This paper describes the application of a new method to verify the pressure and sealing of cavities in micromechanical components. The new method makes it possible to measure the pressure and the sealing (through measuring the pressure over time) of smallest gasvolumes with the monitoring of the quality factor of integrated micromechanical resonant structures. An example is used that shows the complete process of fabricating such micro mechanical resonant structures to evaluate a bonded structure
This contribution deals with capacitively actuated Ohmic switches in series single pole single throw (SPST) configuration for DC up to 4 GHz signal frequency (<0.5 dB insertion loss, 35 dB isolation) and in shunt switch SPST configuration for a frequency range from DC up to 80 GHz (<1.2 dB insertion loss, 18 dB isolation at 60 GHz). A novel high aspect ratio MEMS fabrication sequence in combination with wafer level packaging is applied for fabrication of the samples and allows for a relatively large actuation electrode area, and for high actuation force resulting in fast onresponse time of 10 s and off-response time of 6 s at less than 5 V actuation voltage. Large actuation electrode area and a particular design feature for electrode over travel and dynamic contact separation lead to high contact force in the closed state and to high force for contact separation to overcome sticking. The switch contacts, which are consisting of noble metal, are made in one of the latest process steps. This minimizes contamination of the contact surfaces by fabrication sequence residuals. A life time of 1 Billion switch cycles has been achieved. This paper covers design for reliability issues and reliability test methods using accelerated life time test. Different test methods are combined to examine electric and mechanical motion parameters as well as RF performance
We present the preliminary design, construction and technology of a microoptical, millimeter-size 3-D microlens scanner, which is a key-component for a number of optical on-chip microscopes with emphasis on the architecture of confocal microscope. The construction of the device relies on the vertical integration of micromachined building blocks: top glass lid, silicon electrostatic comb-drive X-Y and Z microactuators with integrated scanning microlenses, ceramic LTCC spacer, and bottom lid with focusing microlens. All components are connected on the wafer level only by sequential anodic bonding. The technology of through wafer vias is applied to create electrical connections through a stack of wafers. More generally, the presented bonding/connection technologies are also of a great importance for the development of various silicon-based devices based on vertical integration scheme. This approach offers a space-effective integration of complex MOEMS devices and an effect ive integration of various heterogeneous technologies
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