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1.
This paper reports on glass frit wafer bonding, which is a universally usable technology for wafer level encapsulation and packaging. After explaining the principle and the process flow of glass frit bonding, experimental results are shown. Glass frit bonding technology enables bonding of surface materials commonly used in MEMS technology. It allows hermetic sealing and a high process yield. Metal lead throughs at the bond interface are possible, because of the planarizing glass interlayer. Examples of surface micromachined sensors demonstrate the potential of glass–frit bonding. 相似文献
2.
Anodic bonding of glass to aluminium may provide a higher degree of freedom in device design. In this paper, a systematic variation of the bonding parameters for the aluminium–glass bond is presented. Hermetic seals with strengths of 18.0 MPa can be achieved using a 50–100-nm-thick bonding aluminium layer, and bonding at 300–400°C applying a voltage of 1,000–1,500 V for 20 min. With these parameters, bond yields above 95.1% were obtained on 17 wafers. The bonds survived extensive thermal ageing without significant degradation. The possibility of bonding glass to an aluminium layer with buried, electrically isolated conductors underneath is also demonstrated. 相似文献
3.
This paper presents an integration technology for RF passives using benzocyclobutene (BCB)/metal multilayer interconnection
for system-in-package applications. This technology has been specially developed for RF subsystem packages in which a thick
polymer, BCB (more than 15 μm thick), is adopted as dielectric with lossy silicon as substrate for its excellent characteristics.
Both dry-etch BCB and photosensitive BCB are applied in this work, and their processes are briefly introduced and compared.
An RF power divider, an MIM capacitor, different types of RF inductors as well as a coupled microstrip based band-pass filter
are fabricated and measured at wafer level. The results show good electrical performances, and accordingly the passives are
well applicable in RF band. Moreover, the subsystem models including monolithic chips connected with passives are presented. 相似文献
4.
Adhesive wafer bonding is a technique that uses an intermediate layer (typically a polymer) for bonding two substrates. The
main advantages of using this approach are: low temperature processing (maximum temperatures lower than 400°C), surface planarization
and tolerance to particles contamination (the intermediate layer can incorporate particles with the diameter in the layer
thickness range). The main bonding layers properties required by a large field of applications/designs can be summarized as:
isotropic dielectric constants, good thermal stability, low Young’s modulus, and good adhesion to different substrates. This
paper reports on wafer-to-wafer adhesive bonding using SINR TM polymer materials. Substrate coating process as well as wafer bonding process parameters optimization was studied. Statistical
analysis methods were used to show repeatability and reliability of coating processes. Features of as low as 15 μm size were
successfully resolved by photolithography and bonded. An unique megasonic-enhanced development process of the patterned film
using low cost solvent was established and proven to exceed standard development method performance. 相似文献
5.
Adhesive wafer bonding with a patterned polymer layer is increasingly attracting attention as cheap and simple 0-level packaging technology for microstructures, because the patterned polymer both fulfills the bonding function and determines the volumes between the two wafers housing the devices to be packaged. To be able to pattern a polymer, it has to be cross-linked to a certain degree which makes the material rigid and less adhesive for the bonding afterward. In this paper, a simple method is presented which combines the advantages of a patterned adhesive layer with the advantages of a liquid polymer phase before the bonding. The pattern in the adhesive layer is "inked" with viscous polymer by pressing the substrate toward an auxiliary wafer with a thin liquid polymer layer. Then, the substrate with the inked pattern is finally bonded to the top wafer. Benzocyclobuene (BCB) was used both for the patterned structures and as the "ink". Tensile bond strength tests were carried out on patterned adhesive bonded samples fabricated with and without this contact printing method. The bonding yield is significantly improved with the contact printing method, the fabrication procedure is more robust and the test results show that the bond strength is at least 2 times higher. An investigation of the samples' failure mechanisms revealed that the bond strength even exceeds the adhesion forces of the BCB to the substrate. Furthermore, the BCB contact printing method was successfully applied for 0-level glass-lid packaging done by full-wafer bonding with a patterned adhesive layer. Here, the encapsulating lids are separated after the bonding by dicing the top wafer independently of the bottom wafer. 相似文献
6.
Silicon-to-silicon fusion (or direct) pre-bonding is an important enabling technology for many emerging microelectronics and MEMS technologies. A silicon–silicon direct bond can be easily formed, where the wafer surfaces are highly flat and very clean (Tong and Gosele), however for practical structured MEMS devices, wafer bow and local roughness may be compromised such that it is no longer a trivial task to achieve a direct bond. Tooling has been developed to facilitate the in situ alignment and bonding of silicon-to-silicon wafers in a vacuum chamber. The rate and direction of the bond propagation are controlled, thus minimising the occurrence of non-particle related voids. The tooling system also allows wafers with “non-ideal” surfaces or warped profiles to be bonded, by maximising the area across which bonding occurs and providing in situ annealing. The ability to anneal the wafers while maintaining clamping force creates attractive forces high enough to overcome the mechanical repulsive forces between the wafers and maintain a permanent bond. The tooling system can also be configured to give control over the bow or residual stress in the bonded pair, a factor that is critical in multi-stack direct wafer bonding. 相似文献
7.
In this paper a novel process to bond and, at the same time, to electrically connect a silicon wafer to a glass wafer is presented. It consists of a low temperature anodic bonding process between silicon and glass by using a glass wafer with etched channels in order to contain metal tracks. The glass-to-silicon anodic bonding process at low temperatures (not exceeding 300°C) assures a strong mechanical link (Berthold et al. in Transducers 1999, June:7–10, 1999). The electrical contacts between the metal pads on the backside of a silicon wafer and the metal pads on the glass wafer are achieved by sintering and diffusion of metals due to a kind of thermo compression bonding. This bonding method permits a high vertical control due to a well-controlled etching of the cavity depth and to the thickness precision of both metallization (pads on silicon wafers and metal tracks on glass wafer). This IC-processing compatible approach opens up the way to a new electrical connection concept keeping, at the same time, a strong mechanical bond between glass and silicon wafers for an easier fabrication of a more complex micro-system. 相似文献
8.
In this paper, we developed a hermetic wafer level packaging for MEMS devices. Au–Sn eutectic bonding technology in a relatively
low temperature is used to achieve hermetic sealing, and the vertical through-hole via filled with electroplated copper for
the electrical connection is also used. The MEMS package has the size of 1 mm × 1 mm × 700 μm, and a square loop Au–Sn metallization
of 70 μm in width for hermetic sealing. The robustness of the package is confirmed by several tests such as shear strength
test, reliability tests, and hermeticity test. The reliability issues of Au–Sn bonding technology, and copper through-wafer
interconnection are discussed, and design considerations to improve the reliability are also presented. By applying O 2 plasma ashing and fabrication process optimization, we can achieve the void-free structure within the bonding interface.
The mechanical effects of copper through-vias are also investigated numerically and experimentally. Several factors which
could induce via hole cracking failure are investigated such as thermal expansion mismatch, via etch profile, copper diffusion
phenomenon, and cleaning process. Alternative electroplating process is suggested for preventing Cu diffusion and increasing
the adhesion performance of the electroplating process. 相似文献
9.
A low cost and low temperature thin film packaging process based on the transfer of an electroplated Nickel 3D cap is proposed.
This process is based on adhesion control of a thick molded cap Ni film on the carrier wafer by using a plasma deposited fluorocarbon
film, on mechanical debonding and on adhesive bonding of the microcaps on the host wafer with BCB sealing rings. Mechanical
characterizations show that the transferred microcaps have a high stiffness, a low stress and a high adhesion. Because this
process is simple and only involves a low temperature (250°C) heating of the host wafer, it is highly versatile and suitable
for the encapsulation of micro and nano devices, circuits and systems elaborated on a large range of substrate materials. 相似文献
10.
Manufacturing and integration of MEMS devices by wafer bonding often lead to problems generated by thermal properties of materials.
These include alignment shifts, substrate warping and thin film stress. By limiting the thermal processing temperatures, thermal
expansion differences between materials can be minimized in order to achieve stress-free, aligned substrates without warpage.
Achieving wafer level bonding at low temperature employs a little magic and requires new technology development. The cornerstone
of low temperature bonding is plasma activation. The plasma is chosen to compliment existing interface conditions and can
result in conductive or insulating interfaces. A wide range of materials including semiconductors, glasses, quartz and even
plastics respond favorably to plasma activated bonding. The annealing temperatures required to create permanent bonds are
typically ranging from room temperature to 400°C for process times ranging from 15–30 min and up to 2–3 h. This new technique
enables integration of various materials combinations coming from different production lines. 相似文献
11.
Based on the fracture mechanics analysis of crack propagation, the phenomenon of subcritical crack growth was utilized for
a controlled debonding of directly wafer-bonded interfaces. The approach allowed the well-defined separation of bonded wafers
although the bond strength was high due to thermal annealing. The achieved splitting velocity depended on the wafer material,
the wafer thickness ratio, the bonding process parameters, and the environmental conditions during cleaving. In combination
with wafer bonding, the method can be used for a temporary stiffening and handling of thin and brittle wafers during fabrication,
even if the wafers are exposed to high process temperatures. The approach can also be applied to fabricate micromechanical
systems (MEMS).
Received: 12 July 2001/Accepted: 26 February 2002
This paper was presented at the Conference of Micro System Technologies 2001 in March 2001. 相似文献
12.
Glass to glass anodic bonding using a metal interlayer was used to develop a fabrication method of spacer for field emission
display (FED). In this paper, spacers with width 100 μm and height 1000 μm and a 3.54 inch mono color anode plate patterned
with Al/Cr film as an interlayer were bonded by the anodic bonding. To bond the spacers on the anode plate vertically, two
types of spacer holders were designed and fabricated with photoetchable glass and n(110) Si wafer. The spacer holder using
Si wafer was used to fabricate for evacuated FED panel.
Received: 22 November 1999/Accepted: 27 January 2000 相似文献
13.
We developed a method of interfacing microfluidics with mass spectrometry (MS) using a robotic spotting system to automate
the contact spotting process. We demonstrate that direct and automated spotting of analyte from multichannel microfluidic
chips to a custom microstructured MALDI target plate was a simple, robust, and high-throughput method for interfacing parallel
microchannels using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Using thermoplastic cyclic olefin
copolymer (COC) polymer microfluidic chips containing eight parallel 100 μm × 46 μm microchannels connected to a single input
port, spotting volume repeatability and MALDI-MS signal uniformity are evaluated for a panel of sample peptides. The COC microfluidic
chips were fabricated by hot embossing and solvent bonding techniques followed by chip dicing to create open ends for MS interfacing.
Using the automatic robotic spotting approach, microfluidic chip-based reversed-phase liquid chromatography (RPLC) separations
were interfaced with electrochemically etched nanofilament silicon (nSi) target substrate, demonstrating the potential of
this approach toward chip-based microfluidic separation coupled with matrix-free laser desorption/ionization mass spectrometry. 相似文献
14.
This paper describes the design and fabrication of a MEMS guide plate, which was used for a vertical probe card to test a
wafer level packaged die wafer. The size of the fabricated MEMS guide plate was 10.6 × 10.6 cm. The MEMS guide plate consisted
of 8,192 holes to insert pogo pins, and four holes for bolting between the guide plate and the housing. To insert pogo pins
easily, an inclined plane was defined at the back of each hole. Pitch and diameter of the hole were 650 and 260 μm, respectively.
In order to define inserting holes and inclined planes at an exact position, silicon MEMS technology was used such as anisotropic
etching, deep reactive etching and more. Silicon was used as the material of the guide plate to reduce alignment mismatch
between the pogo pins and solder bumps during a high temperature testing. A combined probe card with the fabricated MEMS guide
plate showed good x– y alignment and planarity errors within ±9 and ±10 μm at room temperature, respectively. In addition, x– y alignment and planarity are ±20 and ±16 μm at 125°C, respectively. The proposed MEMS guide plate can be applied to a vertical
probe card for burn-in testing of a wafer level packaged die wafer because the thermal expansion coefficient of the MEMS guide
plate and die wafer is same. 相似文献
15.
An innovative and simple microfabrication method for digital microfluidics is presented. In this method, devices are formed
from copper substrates or gold compact disks using rapid marker masking to replace photolithography. The new method is capable
of forming devices with inter-electrode gaps as small as 50 μm. Saran™ wrap (polyethylene film) and commercial water repellants
were used as dielectric and hydrophobic coatings, respectively, to replace commonly used and more expensive materials such
as parylene-C and Teflon-AF. Devices formed by the new method enabled single- and two-plate actuation of droplets with volumes
of 1–12 μL. Fabricated devices were successfully tested for droplet manipulation, merging and splitting. We anticipate that
this fabrication method will bring digital microfluidics within the reach of any laboratory with minimal facilities.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
Silicon wafers have been anodically bonded to sputtered lithium borosilicate glass layers (Itb 1060) at temperatures as low
as 150–180 °C and to sputtered Corning 7740 glass layers at 400 °C. Dependent on the thickness of the glass layer and the
sputtering rate, the sputtered glass layers incorporate compressive stresses which cause the wafer to bow. As a result of
this bowing, no anodic bond can be established especially along the edges of the silicon wafer. Successful anodic bonding
not only requires plane surfaces, but also is determined very much by the alkali concentration in the glass layer. The concentration
of alkali ions as measured by EDX and SNMS depends on both the sputtering rate and the oxygen fraction in the argon process
gas. In Itb 1060 layers produced at a sputtering rate of 0.2 nm/s, and in Corning 7740 layers produced at sputtering rates
of 0.03 and 0.5 nm/s, respectively, the concentration of alkali ions in the glass layers was sufficiently high, at oxygen
partial pressures below 10 -4 Pa, to achieve anodic bonding. High-frequency ultrasonic microanalysis allowed the bonding area to be examined non-destructively.
Tensile strengths between 4 and 14 MPa were measured in subsequent destructive tensile tests of single-bonded specimens. 相似文献
17.
As one of the most important components in adaptive optics, the deformable mirror (DM) is required to have a flat surface
for better performance. For micromachined DMs, single-crystal-silicon (SCS) membrane is an ideal material for high quality
reflective mirror surface owing to its good flatness and small residual stress. In this research, a process was established
to realize SCS mirror membrane by DRIE of SOI wafer and anodic bonding of SOI wafer to Pyrex 7740 glass. Using this process,
the proof-of-concept for a micromachined DM composed of SCS mirror surface has been successfully demonstrated. The prototype
DM shows a stroke of 4.23 μm at 120 V. The P–V and rms of the reflective mirror surface are 492 and 82 nm, respectively. The
performance of the prototype DM can somewhat satisfy the need of AO in visible spectrum. Better surface quality is anticipated
by employing SOI wafers with strictly controlled residual stress. 相似文献
18.
The forming process of U-form glass micro-nanofluidic chip with long nanochannels is presented in this paper, in which the
fabrication of channels and the assembly of plates are included. The micro-nanofluidic chip is composed of two glass plates
in which there are microchannels and nanochannels, respectively. This chip can be used for trace sample enrichment, molecule
filtration, and sample separation, etc. In fabrication process, the two-step photolithograph on one wafer is often required
in early papers, as nano and micro structure designed in one plate have different depths. In this paper, the channels in micro-nanofluidic
chip are designed in two glass plates instead of in one wafer. The nanochannels and microchannels are, respectively, formed
on plates using wet etching and two-step photolithograph on one wafer is not required. Since the channels are formed, the
upper plate and the bottom plate are assembled together by alignment, preconnection and thermal bonding orderly. Firstly these
plates are aligned with the cross-marks on an inverted microscope. The aqueous film between plates is controlled to decrease
the static friction force for accurate adjustment. Then the adhesion strength of connection is enhanced with semi-dry status
for limiting movement from slight inclining and shaking. At last, the bottom plate and the upper one are irreversibly linked
together with thermal bonding. The heating period and max temperature of thermal bonding are optimized to eliminate thermal
stress gradient and the size shrinking. With the micro-nanofluidic chip, the 1 μM fluorescein isothiocyanate in 10 mM PBS
buffer is concentrated successfully. The sample concentrating factor of light intensity varies from 2.2 to 8.4 with applied
voltages between 300 and 2,000 V. The switch effect and the instability effect in concentrating process are described and
analyzed too. 相似文献
19.
Suspended inductors and 2.45 GHz BPF with patterned ground shields on the lossy silicon substrate by using Cu/BCB based wafer level packaging and bulk Si etching technologies were fabricated. Thick BCB interlayer is used as the supporting dielectric and the backside cavity is easily removed by using a two-step back-etching process. The fabricated 2.7 nH inductor has a maximum Q factor 49 at 8.2 GHz and high Q factors more than 22 in the broadband frequency range from 1 to 10 GHz. And the realized 2.45 GHz BPF has the insertion loss of 3.0 dB and the return loss of more than 14 dB at the pass band. It is also featured by more than 48 and 25 dB attenuation at 0.9 and 1.8 GHz respectively, with the second harmonic rejection being 33 dB. 相似文献
20.
Laser joining is a promising technique for wafer-level bonding. It avoids subjecting the complete microelectromechanical system (MEMS) package to a high temperature and/or the high electric field associated with conventional wafer-level bonding processes, using the laser to provide only localized heating. We demonstrate that a benzocyclobutene (BCB) polymer, used as an intermediate bonding layer in the packaging of MEMS devices, can be satisfactorily cured by using laser heating with a substantial reduction of curing time compared with an oven-based process. A glass-on-silicon (Si) cavity bonded with a BCB ring can be produced in a few seconds at a typical laser intensity of 1 W/mm 2 resulting in a local temperature of ~300degC. Hermeticity and bond strength tests show that such cavities have similar or better performance than cavities sealed by commercial substrate bonders. The influence of exposure time, laser power, and applied pressure on the degree of cure, bond strength, and hermeticity is investigated. The concept of using a large area uniform laser beam together with a simple mirror mask is tested, demonstrating that such a mask is capable of protecting the center of the cavity from the laser beam; however, to prevent lateral heating via conduction through the Si, a high-conductivity heat sink is required to be in good thermal contact with the rear of the Si. 相似文献
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