Showing papers on "Anodic bonding published in 1995"

Selection of glass, anodic bonding conditions and material compatibility for silicon-glass capacitive sensors

Abstract: This paper examines the process of anodic bonding with regard to the fabrication of silicon-glass capacitive sensors. Various glasses are assessed in terms of the suitability of their physical properties and results are presented on flatness control of these glasses when bonded to silicon at different temperatures. Many of the problems which can typically affect silicon-glass sensors are examined and explained in terms of the anodic bonding process. Effects such as the electrolysis of the glass and the transport of the oxygen produced in this process are discussed and design considerations for minimising deleterious effects of this oxygen are presented. We demonstrate the process of selection of glass, bonding parameters and other material selection by reference to a device on which we are currently working.

Chemical Free Room Temperature Wafer To Wafer Direct Bonding

Abstract: A limitation to the use of direct wafer bonding methods for micromachining and thin film device manufacturing has been the necessity for high temperature anneals to strengthen the bonded interface. Obviously, strong interface strength is needed to withstand backthinning processes and the rigors of device fabrication. Unfortunately, the elevated temperature exposure has a detrimental effect on implanted or diffused etch stop layers via diffusive broadening. Additionally, for many micromachined applications wafer bonding could be used as a final assembly step, replacing epoxies. However, the sensitive components of the device must be protected from thermal effects. This paper describes the use of oxygen plasmas to develop chemical free, room temperature, wafer to wafer bonding methods. The bond developed between plasma‐activated silicon wafers is virtually at full strength upon contact bonding and does not require further thermal strengthening. The results for silicon dioxide bonding show that full strength material is achieved with anneals below 300°C. This process has been applied to a number of wafer materials including sapphire, silicon dioxide, silicon nitride, and gallium arsenide. The data presented are the results of strength tests, interfacial defect etching, transmission electron microscopy analysis, initial interface reaction kinetics, and mechanisms studies. We also show preliminary results from a suggested model to explain the observed increases in kinetics compared to conventional aqueous solution processing of samples.

Characterization of the electrostatic bonding of silicon and Pyrex glass

Abstract: The electrostatic bonding of silicon and Pyrex glass was studied in order to find out the influence of process parameters on the final result and to be able to optimize the process with regard to the fabrication of silicon sensors. The most important parameters are the temperature and the voltage. The main criterion used for the optimization of their values was the induced stress in the silicon part of the bonded ensemble. It was found that a temperature of 360 degrees C and voltages in the range 750-1000 V are suitable.

Self‐propagating room‐temperature silicon wafer bonding in ultrahigh vacuum

Abstract: Wafer bonding of commercial 4 in. silicon wafers has been performed at room temperature under ultrahigh vacuum conditions. After local initiation of the bonding process the bonding area is self‐propagating just as in the case of wafer bonding under atmospheric conditions. The room‐temperature bonded wafers, without any additional heat treatment show a bonding strength typical for bulk material.

Process for bonding a shell to a substrate for packaging a semiconductor

Abstract: A process for manufacturing a vacuum enclosure for a semiconductor device formed on a substrate with leads extending peripherally. Assembly of the enclosure is compatible with known batch fabrication techniques and is carried out at pressures required for optimal device operation. In a first embodiment, an intrinsic silicon shell is sealed to the substrate via electrostatic or anodic bonding with the leads diffusing into the shell. In a second embodiment, a thin interface layer of silicon or polysilicon is deposited on the substrate prior to electrostatic bonding a glass shell thereon. In a third embodiment, tunnels are formed between a lower peripheral edge of the shell and the substrate, allowing leads to pass thereunder. The tunnels are sealed by a dielectric material applied over the enclosure.

Method for forming oxide protective film on bonding pads of semiconductor chips by UV/O3 treatment

Abstract: A method for forming a protective oxide film on the bonding pads of a semiconductor chip which is to be encapsulated by a molded-in-place capsule of plastic material including exposing a chip having bonding pads (while the chip is in the form of wafer), to O 3 and ultraviolet (UV) radiation, so that excited oxygen generated from the O 3 by UV radiation oxidizes metal atoms, for example aluminum atom of the aluminum bonding pads, to form a fine oxide film over the bonding pads, this film providing protection from water and/or ions which would otherwise cause corrosion of the bonding pads.

High strength bonding tool and a process for the production of the same

Abstract: The present invention provides a thermocompression tool, i.e. high strength bonding tool used for mounting a semiconductor device or element such as IC, LSI, etc. on a substrate, for example, a tool of pulse heating type used for soldering, and a mounting tool (bonding tool). The tool is used for heating, melting and bonding or thermocompression bonding in a lump a number of workpieces to be bonded, making up a part of electronic parts, in particular, a high precision tool called outer lead bonding tool. The high strength bonding tool has a substrate that is composed of a cemented carbide having microscopic protrusions of hard carbides and/or hard carbonitrides on at least one surface and having a coefficient of linear expansion of 4.0×10 -6 to 5.5×10 -6 /°C. at room temperature to 400° C. Furthermore, a polycrystalline diamond coating is formed on the surface having microscopic protrusions by a gaseous phase synthesis method, the surface coated with the polycrystalline diamond coating being used as a tool end surface.

Alkali metal ion migration control

Abstract: A materials system comprising a glass containing alkali metal ions capable of migrating and a silica, alumina, or tantala film deposited on the glass surface, the glass also containing high field strength ions that can change coordination. The direction of alkali metal ion flow depends on the film selected and the glass composition.

Optimization of copper wire bonding on Al-Cu metallization

Abstract: This paper reports the successful implementation of copper wire ball bonding for selected TO-220 devices on a high volume commercial scale. Since August 1992, copper wire bonding has been used in production at National Semiconductor Corp. The development of copper wire ball bonding involves a three-prong approach: optimum pad metal composition, modifications to the wire bonder and optimization of the assembly parameters. the critical material parameter is bond pad hardness. This needs to be above a critical threshold value to avoid silicon cratering. The metal composition best suited for the wire bonding process is sputtered Al-Cu(2%). Typical production yields of 99.8% at lead bond are obtained with 1.5 mil (37.5 /spl mu/m) copper wires, with ball shear and wire pull averaging 100/spl plusmn/20 gms and 15/spl plusmn/2 gms, respectively. Five issues related to copper wire bonding of TO-22 power IC packages are discussed: 1) typical bonding failure modes; 2) the relation between bond pad composition and hardness; 3) the influence of the metal deposition systems; 4) the optimization of bonding conditions; 5) the reliability of the copper wire bonded devices. >

Method of securing optical fiber components, devices and fibers to the same or to mounting fixtures

Abstract: A method of bonding glass-based optical elements comprising the steps of positioning a first glass-based optical element relative to a second glass-based optical element, applying a glass-based bonding compound about the first and second optical elements, and applying sufficient localized heat to the glass-based bonding compound to cause the glass-based bonding compound to soften and fuse with the optical elements.

Sheet glass flattening method, method of manufacturing glass substrate for an information recording disk using flattened glass, method of manufacturing a magnetic recording disk using glass substrate, and magnetic recording medium

Abstract: A glass substrate manufacturing method advantageously applicable to magnetic recording disk glass substrates, LCD glass substrates, photomask glass substrates, or optical memory glass substrates. This method includes the steps of forming a film of a solution on at least a principal surface of a sheet glass formed using a down-drawing method, the solution containing a water soluble inorganic material and a surface-active agent; sandwiching both sides of a single sheet glass on which the film is formed or of a laminated structure of plural sheet glasses with a densified sheet with a high flatness to pressure the single glass or laminated structure; and heating and annealing the single sheet glass or laminated structure to flatten the same. The end side of the flatten glass substrate is treated with a treating solution containing a hydrofluosilicic acid. The glass substrate is formed by chemically strengthen a glass substrate by immersing the glass substrate in a chemical reinforcement solution heated and then ion exchanging ions on the surface-layer of the glass substrate with ions in the chemical reinforcement solution; pulling up the substrate from the chemical reinforcement solution and then annealing it to a temperature higher than the crystallization temperature of a molten salt; annealing the glass substrate at a rate at which the crystallization of the molten salt is deposited on the surface of the glass substrate; and then cleaning the surface of the glass substrate. Moreover, the glass substrate is formed by chemically strengthen a glass substrate by immersing the glass substrate in a chemical reinforcement solution heated and then ion exchanging ions on the surface layer of the glass substrate with ions in the chemical reinforcement solution; and pulling up the substrate from the chemical reinforcement solution and then cleaning the surface of the glass substrate with a cleaning agent containing acid.

Ceramic coating method

Abstract: A method of coating a ceramic and bonding ceramic onto a substrate for practical uses over 630° C. includes forming a brazed bonding layer at a contact area between the ceramic and the substrate by a fluidic reaction and causing the bonding layer to wet both the ceramic and substrate with a wetting angle of 0-5° to thereby coat and bond the ceramic onto bond the substrate over the entire contact area with a continuous, essentially 100% dense bonding layer. The bonding layer is so free of bonding defects that the resulting bonded product can withstand repeated thermal shocks by quenching in 0° ice water from a temperature in the range of 630-980° C.

Method of making a micromechanical silicon-on-glass tuning fork gyroscope

Abstract: A micromechanical tuning fork gyroscope (14) fabricated by a dissolved silicon wafer process whereby electrostatic bonding forms a hermetic seal between an etched glass substrate (12), metal electrodes (202) deposited thereon, and a silicon comb-drive tuning fork gyroscope (14). The dissolved silicon wafer process involves single-sided processing of a silicon substrate (100), including the steps of etching recesses (102), diffusing an etch resistant dopant (104) into the silicon substrate (100), and releasing various components of the silicon gyroscope (14) by etching through the diffusion layer (104) in desired locations (106). The glass substrate (12) also undergoes single-sided processing, including the steps of etching recesses, depositing a multi-metal system in the recesses (200), and selectively etching portions of the multi-metal system (202). One substrate (100) is inverted over the other (12) and aligned before anodic bonding of the two substrates is performed.

Method of adhering green tape to a metal support substrate with a bonding glass

Abstract: In the manufacture of ceramic circuit boards having ceramic or metal support substrates, a bonding glass layer that is adherent both to the substrate material and to multilayer green tape compositions having circuitry printed thereon, is deposited and flowed onto the support substrate. The bonding glasses suitable for use with nickel plated metal substrates and green tape compositions containing forsterite-cordierite-type glasses are mixed oxides including calcium, zinc and boron as well as other oxides. These bonding glasses have a thermal coefficient of expansion that is larger than said metal substrate, and a flow temperature below that of said cordierite-type glasses.

Thickness Considerations in Direct Silicon Wafer Bonding

Abstract: A simple approximate analytical expression based on an elastic deflection principle is suggested as a design guideline for direct bonding of blank or patterned Si or dissimilar materials of various thicknesses. To achieve the high flatness requirement of the mating surfaces for thick wafer bonding, optical polishing must be employed. With a surface flatness variation of 0.1 wavelength (∼630 A), two 20 mm thick Si pieces of 100 mm in diam were spontaneously bonded at room temperature. On the other hand, the gaps designed to be formed by patterned surfaces may collapse during the bonding process if the pattern dimensions are not properly selected.

Method of cleaning residue on a semiconductor wafer bonding pad

Abstract: A method for backside grinding a semiconductor wafer and forming a contamination free bonding pad connection. The method comprises forming a passivation layer over a metal layer. Applying a photoresist pattern with an opening which will define a bonding pad area and removing the passivation layer exposed in the opening. Next, the photoresist is removed, but a polymer residue is often formed on the surfaces of the passivation layer surrounding the bonding pad. In a novel step, the residue is removed using an etchant containing Dimethylsulfoxide (D.M.D.O.) aud Monoethanolamine (M.E.A.) and is followed by au oxygen plasma treatment. Next, the device side of the wafer is covered with a protective tape and the backside of the wafer is grouud back. The tape is removed revealing a contamination free bonding pad area. A bonding connection is then made to the bonding pad.

Optical waveguide device bonded through direct bonding and a method for fabricating the same

Abstract: An optical waveguide device including a support substrate, a glass substrate, and a thin film layer formed on at least one of the substrates, if required. The support substrate and the glass substrate are bonded through direct bonding, and the glass substrate includes an optical waveguide as a part thereof. A layer having a refractive index lower than that of the glass substrate may be formed on the glass substrate. A method for fabricating such an optical waveguide device is also provided.

Thermal expansion and adhesion of ceramic to metal sealings: case of porcelain-Kovar junctions

Abstract: Glass to metal sealings necessitate a pre-oxidation of the metal, producing a thin superficial oxide layer. In the case of porcelain-kovar junctions a glassy interphase is necessary, which reacts and dissolves the oxide layer during the bonding thermal treatment. In the interfacial zone this leads to a good fitting of the thermal expansion coefficients of the phases present: in the alloy the superficial part is impoverished in iron and its thermal expansion coefficient is close to that of the FeO-rich glass which has dissolved the oxide layer. The resulting buffer zone limits the effect of strains appearing during cooling at the end of the bonding thermal treatment. Moreover, the FeO-rich glass penetrates the open porosity of the superficial alloy layer (due to its pre-oxidation) providing a good physical adherence of glass to kovar. At the porcelain-glass interface there is no problem because of the similarity of dilatometric behaviour of the two materials.

Method for the cleaning and direct bonding of solids

Abstract: Cleaning in periodic acid (H5 IO6) aqueous solutions (HI solutions) of particular compositions removes thermally unstable hydrocarbons from the surfaces of semiconductor wafers and enables the direct bonding of semiconductor surfaces such that the bonded interface between these surfaces remains free of bubbles even after heating subsequent to bonding.

Direct bonding of piezoelectric crystal onto silicon

Abstract: A method for bonding a piezoelectric crystal directly onto silicon, without any bonding agents, is reported. The interface microstructure, procedures of fabricating a lithium tantalate (LiTaO3■‐ on‐silicon resonator, and its resonant characteristics are described. This technique is very promising for miniaturizing electroacoustic integrated devices.

Bonding pad structure and method thereof

Abstract: A structure and a process for forming an improved bonding pad which allows better bonding between a bond wire and a metal bonding pad. Stripes are formed on a substrate. A conformal dielectric layer, a conformal barrier layer and a metal layer are formed over the stripes. A passivation layer with a window is formed defining a bonding pad area. The stripes promote an irregular surface in the barrier and metal layers which reduce stress between the dielectric layer, the barrier layer and the metal layer. Also, the irregular surfaces increase the barrier metal adhesion to the dielectric layer, reduce bond pad peel off, and increase bonding yields.

Sacrificial wafer bonding for planarization after very deep etching

Abstract: A new technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for resist spinning and layer patterning as well as realization of bridges or cantilevers across deep holes or grooves. The sacrificial wafer bonding technique contains a wafer bond step followed by an etch back. Results of polymer bonding followed by dry etching and anodic bonding combined with KOH etching are discussed. The polymer bonding has been applied in a strain based membrane pressure sensor to pattern the strain gauges and to provide electrical connections across a deep corrugation in a thin silicon nitride membrane by metal bridges. >

Improved direct bonding of Si and SiO2 surfaces by cleaning in H2SO4:H2O2:HF

Abstract: A method for silicon surface preparation prior to wafer bonding in presented. By cleaning thp wafers in a H2SO4:H2O2 mixture in which a small amount of HF is added, and then rinsing in H2O, the bon ...

Bonding characteristics and diffusion barrier effect of the TiC phase formed at the bonding interface in an explosively welded titanium/high- carbon steel clad

Abstract: Microstructural aspects and bonding characteristics of the explosively welded titanium/high-carbon steel clad of the as-welded and postannealed states were investigated. Amorphous and βTi phases were observed at the interface in the as-welded clad. These were considered to be the trace of melting and subsequently rapid solidification of thin layers along the contact surface of both the parent materials. The melting layer was considered to be responsible for the substantial bonding. The TiC layer was formed at the bonding interface by postannealing, which served as a barrier for diffusion of species across the interface and suppressed the formation of Fe-Ti intermetallic compounds. As a result, high bonding strength was preserved even after prolonged annealing at elevated temperatures.

Direct bonding of LiNbO3 single crystals for optical waveguides

Abstract: A new fabrication method of optical waveguides using direct bonding of lithium niobate single crystals without using any bonding agents has been developed. The bonded interface was found very uniform and the bonding was performed in an atomic scale in spite of a relatively low heat‐treatment temperature of 400 °C. It was confirmed to be possible to fabricate optical waveguides using the direct bonding. This method is very attractive to obtain high‐performance optical guided‐wave devices because of its versatility.

Bonding tool for tape automated assembly

Abstract: A bonding tool for use in tape automated bonding and wedge bonding of gold and gold plated leads or wires to contact pads of electronic devices is fabricated of Aluminum Oxide ceramic without electrically conductive metallic binders. The bonding tool has a microscopically rough surface that is brought into compressive contact with the gold leads or wires and manipulated ultrasonically or thermosonically in order to form a molecular bond between the gold lead or wire and the contact pad of the electronic device. The Aluminum Oxide ceramic bonding tool is sufficiently hard that it does not readily deform under normal ultrasonic bonding conditions and is not readily abraded by the gold leads.

Examination of glass-silicon and glass-glass bonding techniques for microfluidic systems

Abstract: We report here on the results of experiments concerning particular bonding processes potentially useful for ultimate miniaturization of microfluidic systems. Direct anodic bonding of continuous thin pyrex glass of 250 {mu}m thickness to silicon substrates gives multiple, large voids in the glass. Etchback of thick glass of 1200 {mu}m thickness bonded to silicon substrates gives thin continuous glass layers of 189 {mu}m thickness without voids over areas of 5 cm {times} 12 cm. Glass was also successfully bonded to glass by thermal bonding at 800{degrees}C over a 5 cm {times} 7 cm area. Anticipated applications include microfabricated DNA sequencing, flow injection analysis, and liquid and gas chromatography microinstruments.