| 1. |
- Andersson, Helene, et al.
(author)
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Hydrophobic valves of plasma deposited octafluorocyclobutane in DRIE channels
- 2001
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In: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 75:1-2, s. 136-141
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Journal article (peer-reviewed)abstract
- The suitability of using octafluorocyclobutane (C4F8) patches as hydrophobic valves in microfluidic biochemical applications has been shown. A technique has been developed to generate lithographically defined C4F8 hydrophobic patches in deep reactive ion-etched silicon channels. Some of the advantages of this process are that no specific cleaning of the substrate is required, C4F8 is deposited on the sidewalls and the bottom of the channels, a standard photoresist mask can be used to define the patches, and that it is a fast and convenient dry chemical process performed by a standard inductively coupled plasma etcher using the Bosch process. Different patch lengths (200-1000 mum) of C4F8 were deposited in 50 mum wide channels to evaluate which size is most suitable for microfluidic biochemical applications. The valve function of the hydrophobic patches was tested for the following liquids: DD water, acetone, propanol, bead solution and a mixture used for pyrosequencing of DNA. Patch lengths of 200 mum of C4F8 successfully stopped each solution for at least 20 consecutive times. The C4F8 film resists water for at least 5 h. The hydrophobic valve also resists very high concentrations (25%) of surfactants (Tween 80). C4F8 shows a much higher resistance towards water and surface active solutions than previous hydrophobic patches. However, 50% Tween 80 was not stopped at all by the hydrophobic patch. An applied pressure of 760 Pa at the inlet was needed for water to over-run the hydrophobic patch.
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| 2. |
- Frank, Niklaus
(author)
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Adhesive Wafer Bonding for Microelectronic and Microelectromechanical Systems
- 2002
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Doctoral thesis (other academic/artistic)abstract
- Semiconductor wafer bonding has been a subject of interestfor many years and a wide variety of wafer bonding techniqueshave been reported in literature. In adhesive wafer bondingorganic and inorganic adhesives are used as intermediatebonding material. The main advantages of adhesive wafer bondingare the relatively low bonding temperatures, the lack of needfor an electric voltage or current, the compatibility withstandard CMOS wafers and the ability to join practically anykind of wafer materials. Adhesive wafer bonding requires nospecial wafer surface treatmentssuch as planarisation.Structures and particles at the wafer surfaces can be toleratedand compensated for some extent by the adhesive material.Adhesive wafer bonding is a comparably simple, robust andlowcost bonding process. In this thesis, adhesive wafer bondingtechniques with different polymer adhesives have beendeveloped. The relevant bonding parameters needed to achievehigh quality and high yield wafer bonds have been investigated.A selective adhesive wafer bonding process has also beendeveloped that allows localised bonding on lithographicallydefined wafer areas. Adhesive wafer bonding has been utilised in variousapplication areas. A novel CMOS compatible film, device andmembrane transfer bonding technique has been developed. Thistechnique allows the integration of standard CMOS circuits withthin film transducers that can consist of practically any typeof crystalline or noncrystalline high performance material(e.g. monocrystalline silicon, gallium arsenide,indium-phosphide, etc.). The transferred transducers or filmscan be thinner than 0.3 µm. The feature sizes of thetransferred transducers can be below 1.5 µm and theelectrical via contacts between the transducers and the newsubstrate wafer can be as small as 3x3 µm2. Teststructures for temperature coefficient of resistancemeasurements of semiconductor materials have been fabricatedusing device transfer bonding. Arrays of polycrystallinesilicon bolometers for use in uncooled infrared focal planearrays have been fabricated using membrane transfer bonding.The bolometers consist of free-hanging membrane structures thatare thermally isolated from the substrate wafer. Thepolycrystalline silicon bolometers are fabricated on asacrificial substrate wafer. Subsequently, they are transferredand integrated on a new substrate wafer using membrane transferbonding. With the same membrane transfer bonding technique,arrays of torsional monocrystalline silicon micromirrors havebeen fabricated. The mirrors have a size of 16x16 µm2 anda thickness of 0.34 µm. The advantages of micromirrorsmade of monocrystalline silicon are their flatness, uniformityand mechanical stability. Selective adhesive wafer bonding hasbeen used to fabricate very shallow cavities that can beutilised in packaging and component protection applications. Anew concept is proposed that allows hermetic sealing ofcavities fabricated using adhesive wafer bonding. Furthermore,microfluidic devices, channels and passive valves for use inmicro total analysis systems are presented. Adhesive wafer bonding is a generic CMOS compatible bondingtechnique that can be used for fabrication and integration ofvarious microsystems such as infrared focal plane arrays,spatial light modulators, microoptical systems, laser systems,MEMS, RF-MEMS and stacking of active electronic films forthree-dimensional high-density integration of electroniccircuits. Adhesive wafer bonding can also be used forfabrication of microcavities in packaging applications, forwafer-level stacking of integrated circuit chips (e.g. memorychips) and for fabrication of microfluidic systems.
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| 3. |
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| 4. |
- Haasl, Sjoerd, et al.
(author)
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Arrays of monocrystalline silicon micromirrors fabricated using CMOS compatible transfer bonding : IEEE The sixteenth annual international conference on Micro Electro Mechanical Systems
- 2003
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In: MEMS-03. - New York : IEEE. - 0780377443 ; , s. 271-274
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Conference paper (peer-reviewed)abstract
- In this paper, we present CMOS compatible fabrication of monocrystalline silicon micromirror arrays using membrane transfer bonding. To fabricate the micromirrors, a thin monocrystalline silicon device layer is transferred from a standard silicon-on-insulator (SOI) wafer to a target wafer (e.g. a CMOS wafer) using low temperature adhesive wafer bonding. In this way, very flat, uniform and low stress micromirror membranes made of monocrystalline silicon can be directly fabricated on top of CMOS circuits. The mirror fabrication does not contain any bond alignment between the wafers; thus, the mirror dimensions and alignment accuracies are only limited by the photolithographic steps. Micromirror arrays with 4x4 pixels and a pitch size of 16mum x 16mum have been fabricated.
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| 5. |
- Kälvesten, Edvard, et al.
(author)
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Method of joining components
- 2000
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Patent (pop. science, debate, etc.)abstract
- A method of combining components to form an integrated device, wherein the components are provided on a first sacrificial wafer, and a second non-sacrificial wafer, respectively. The sacrificial wafer carries a first plurality of components and the non-sacrificial wafer carries a second plurality of components. The wafers are bonded together with an intermediate bonding material. Optionally the sacrificial wafer is thinned to a desired level. The components of the sacrificial wafer are electrically interconnected to the component(s) on the non-sacrificial wafer. Finally, optionally the intermediate bonding material is stripped away.
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| 6. |
- Niklaus, Frank, et al.
(author)
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A method to maintain wafer alignment precision during adhesive wafer bonding
- 2003
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In: Sensors and Actuators A-Physical. - : Elsevier BV. - 0924-4247 .- 1873-3069. ; 107:3, s. 273-278
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Journal article (peer-reviewed)abstract
- In this paper, a novel method is presented that prevents aligned wafers from shifting relative to each other during adhesive bonding. The attainable pre-bond wafer alignment accuracy on commercially available bonding equipment is typically 2-5 mum. However, in adhesive wafer bonding, the intermediate adhesive material must exist in a liquid-like state to wet the wafer surfaces and thereby achieve bonding. When pressing the wafers together with the bond chucks during the bonding process it is practically inevitable that shear forces occur, which act in parallel to the bond line. The intermediate liquid adhesive material cannot counteract the shear forces, thus, the wafers move relative to each other. Consequently, the achievable alignment accuracy in adhesive wafer bonding is typically less than 15 mum using commercial bonding equipment. A novel method has been developed that utilises structures at the wafer surfaces to provide areas with solid-state material contact between the two wafers during the bonding process. The resulting frictional forces prevent the wafers from shifting relative to each other during the time the intermediate adhesive material is in a liquid state. Thus, the pre-bond alignment accuracy of 2-5 mum can be maintained during adhesive wafer bonding using standard wafer bonding equipment as compared to a wafer alignment accuracy of 15-50 mum when no frictional structures are used.
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| 7. |
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| 8. |
- Niklaus, Frank, et al.
(author)
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A new concept for CMOS-compatible fabrication of uncooled infrared focal plane arrays using wafer-scale device transfer bonding
- 2001
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In: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE). - : SPIE-INT SOC OPTICAL ENGINEERING. - 0819440647 ; , s. 397-404
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Conference paper (peer-reviewed)abstract
- In this paper we present a new membrane transfer bonding technology for fabrication of uncooled infrared focal plane arrays (MFPAs). The technology consists only of low temperature processes, thus, it is compatible with standard integrated circuits (ICs). In the future this technology may allow infrared detectors with high temperature annealed, high performance thermistor materials to be integrated in CMOS based uncooled IRFPAs. The infrared detectors and the ICs are processed and optimised on different wafers. The wafer with the detectors (sacrificial detector-wafer) is bonded to the IC wafer (target wafer) using low temperature adhesive bonding. The detector-wafer is sacrificially removed by etching or by a combination of grinding and etching, while the detectors remain on the target wafer. The detectors are mechanically and electrically contacted to the target wafer. Finally, the adhesive bonding material is sacrificially removed. One of the unique advantages of this technology is the ability to integrate small, high temperature annealed detectors and ICs. We have applied membrane transfer bonding to the fabrication of arrays of infrared bolometers with polycrystalline silicon thermistors. In principle, membrane transfer bonding can be applied to the fabrication of any type of free-standing transducer including bolometers, ferroelectric detectors and movable micro-mirrors.
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| 9. |
- Niklaus, Frank, et al.
(author)
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Adhesive sacrificial bonding of spatial light modulators
- 2003
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Patent (pop. science, debate, etc.)abstract
- A method of combining components to form an integrated device, wherein at least one first component is provided on a first surface of a sacrificial substrate, and at least one second component is provided on a first surface of a non-sacrificial substrate. At least one support structure is formed on at least one of the first surfaces of the sacrificial substrate, and the non-sacrificial substrate, respectively, such that said at least one support structure is extended outwardly from at least one of the first surfaces. The sacrificial substrate carrying the first component, and the non-sacrificial substrate carrying the second component, respectively, are bonded, so that the first and second surfaces will be facing one another with a distance defined by a thickness of the support structure. At least a part of the sacrificial substrate is removed.; The first component and second components are interconnected.
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| 10. |
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