Pyrex Glass Wafer Research Articles

Development of MEMS Acoustic Sensor With Microtunnel for High SPL Measurement

The fabrication of piezoelectric ZnO-based micro-electro-mechanical systems (MEMS) acoustic sensor has been reported. The sensor structure consists of a piezoelectric ZnO film deposited between two Al electrodes on a thin silicon diaphragm. A microtunnel is fabricated in the sensor structure using novel approach. This microtunnel is used to protect the diaphragm and determine the lower cut-off frequency of device. The approach presented in this paper completely removed a serious problem of microtunnel blockages during fabrication of sensors. In the developed process, the acoustic sensor fabricated using silicon-on-insulator and the Pyrex glass wafers are diced separately with same chip dimensions. Finally, both Pyrex glass and acoustic sensor chips are fitted in a jig for alignment and then anodically bonded. In reference to microtunnel blockages, the yield of the present technique is obtained as almost 100%. Also, the technique will serve as a cost-effective alternative to the present practice. The developed technique can also be used in manufacturing of similar devices where the microtunnels or microchannels are required in device structure. The technological development is supported by extensive atomic force microscopy (AFM), field emission scanning electron microscopy, Raman spectroscopy, and X-ray diffraction studies of ZnO film; glass-to-silicon bond strength measurement; resonance frequency measurement by laser doppler vibrometer; response characterization of the fabricated sensor, and scanning electron microscopy of microtunnel mouth to demonstrate the feasibility and yield of the process.

High-Consistency Optical Fiber Fabry-Perot Pressure Sensor Based on Silicon MEMS Technology for High Temperature Environment.

This paper proposes a high-temperature optical fiber Fabry–Perot pressure sensor based on the micro-electro-mechanical system (MEMS). The sensing structure of the sensor is composed of Pyrex glass wafer and silicon wafer manufactured by mass micromachining through anodic bonding process. The separated sensing head and the gold-plated fiber are welded together by a carbon dioxide laser to form a fiber-optic Fabry–Perot high temperature pressure sensor, which uses a four-layer bonding technology to improve the sealing performance of the Fabry–Perot cavity. The test system of high temperature pressure sensor is set up, and the experimental data obtained are calculated and analyzed. The experimental results showed that the maximum linearity of the optical fiber pressure sensor was 1% in the temperature range of 20–400 °C. The pressure sensor exhibited a high linear sensitivity of about 1.38 nm/KPa at room temperature at a range of pressures from approximarely 0-to 1 MPa. The structure of the sensor is characterized by high consistency, which makes the structure more compact and the manufacturing process more controllable.

Monolithically Integrated Diffused Silicon Two-Zone Heaters for Silicon-Pyrex Glass Microreactors for Production of Nanoparticles: Heat Exchange Aspects.

We present the design, simulation, fabrication and characterization of monolithically integrated high resistivity p-type boron-diffused silicon two-zone heaters in a model high temperature microreactor intended for nanoparticle fabrication. We used a finite element method for simulations of the heaters’ operation and performance. Our experimental model reactor structure consisted of a silicon wafer anodically bonded to a Pyrex glass wafer with an isotropically etched serpentine microchannels network. We fabricated two separate spiral heaters with different temperatures, mutually thermally isolated by barrier apertures etched throughout the silicon wafer. The heaters were characterized by electric measurements and by infrared thermal vision. The obtained results show that our proposed procedure for the heater fabrication is robust, stable and controllable, with a decreased sensitivity to random variations of fabrication process parameters. Compared to metallic or polysilicon heaters typically integrated into microreactors, our approach offers improved control over heater characteristics through adjustment of the Boron doping level and profile. Our microreactor is intended to produce titanium dioxide nanoparticles, but it could be also used to fabricate nanoparticles in different materials as well, with various parameters and geometries. Our method can be generally applied to other high-temperature microsystems.

Microelectromechanical system-based, high-finesse, optical fiber Fabry–Perot interferometric pressure sensors

A high-finesse, optical fiber, extrinsic Fabry–Perot interferometric (EFPI) pressure sensor based on a microelectromechanical system (MEMS) technique is proposed and experimentally demonstrated. The essential element in the pressure sensor is the high-finesse EFPI cavity that consists of a Pyrex glass wafer, a micromachined silicon wafer, and highly reflective dielectric films. Another Pyrex glass is used for fixing an optical fiber collimator, which allows the realization of the alignment of the incident light. Experimental results show that the proposed sensor exhibits a pressure sensitivity of 1.598 μm/MPa and a high-pressure sensing resolution of 0.002% of the full scale. This sensor is expected to benefit many applications that require high-accuracy pressure measurements, and especially atmospheric pressure applications.

Batch-producible MEMS fiber-optic Fabry-Perot pressure sensor for high-temperature application.

A fiber-optic Fabry-Perot pressure sensor based on a micro-electro-mechanical system (MEMS) and CO2 laser fusion technology is developed and experimentally demonstrated for high-temperature application. The sensing heads are batch-fabricated by anodically bonding the micromachined Pyrex glass wafer and local gold-plated silicon wafer. The separated sensing head and the single-mode fiber are fused together to form the Fabry-Perot cavity using the CO2 laser. In order to improve the measurement accuracy in a high-temperature environment, a fiber Bragg grating is used as a temperature sensor for temperature decoupling. The experimental results show that the fiber-optic Fabry-Perot pressure sensor has a maximum nonlinearity of 0.4%. The maximal error of the pressure after temperature decoupling is less than 1.05% over a pressure range of 0-0.5MPa and a temperature range of 20°C-350°C. The batch fabrication technology makes the sensors low cost and high uniformity.

Wafer-level vacuum package of two-dimensional micro-scanner

We present wafer-level vacuum package of two-dimensional (2-D) micro-scanner based on glass-silicon anodic bonding. To form the sacrificial gap for evacuating air in the package cavity before hermetically sealed, the reflow process of Au/Sn/Cr posts due to low-melting temperature of Sn metal is introduced. Structures in Pyrex glass wafers are patterned using wet etching in the 49% HF solution. The 2-D micro-scanner is fabricated by the SOI-based micromachining technology. The resonant frequencies of 2-D micro-scanner after packaged in vacuum are 30 kHz and 290 Hz for the inner mirror and the gimbal frame respectively. The rotation angle of packaged 2-D micro-scanner is 25° at driving voltages of 20 and 17 V for the inner mirror and the gimbal frame respectively. The pressure in the package is estimated in terms of measuring the quality factor of packaged 2-D micro-scanner. The effect of packaging on the performance of the 2-D micro-scanner such as squeeze film air damping caused by the optical window and the substrate is also analyzed in this paper.

Fabrication of Capacitive Micromachined Ultrasonic Transducer Arrays With Isolation Trenches Using Anodic Wafer Bonding

This paper presents a novel process for the fabrication of capacitive micromachined ultrasonic transducer (CMUT) arrays with isolation trenches using anodic bonding technique. The developed fabrication process is easy, stiction-free, repeatable, reliable, requires low-temperature (<;400°C), and gives high yield. It is a four-mask process. The process is best suited for air-coupled CMUT devices, and can also be used for vacuum-sealed devices. The CMUT device is designed and fabricated successfully using the developed process, which requires silicon-on-insulator (SOI) wafer for membrane and cavity formation, and Pyrex glass wafer for cavity and bottom electrode formation. The process is used for single-cell as well as for development of 1 × 5, 5 × 5, and 10 × 10 CMUT arrays. CMUT cells were designed using MEMSCAD tool CoventorWare. The fabricated devices have been characterized using nanovibration analyzer, and the resonance frequency is found to be ~1.5 MHz.

Optimization of Hot-Wire Airflow Sensors on an Out-of-Plane Glass Bubble for 2-D Detection

This paper presents design, analysis, fabrication, and measurement of airflow sensors with three hot-wire resistors on an out-of-plane glass bubble. The fabrication process is based on etching cavities in silicon wafer, followed by anodic bonding of a thin Pyrex glass wafer to the etched silicon wafer. The bonded wafers are then heated inside a furnace at a temperature above the softening point of the glass, and because of the expansion of the trapped gas in the silicon cavities, the glass is blown into three-dimensional (3-D) spherical glass bubbles. Resistors patterned on the glass wafer above the cavities are elevated above the base during the glass bubble blowing process. An optimization analysis on the structure and geometry of the sensor, fabrication process, and properties of multilayer thin-film resistors on glass has been conducted in an attempt to improve the sensitivity. [2014-0177]

Formation of gallium arsenide nanostructures in Pyrex glass

In this paper, we report on a simple, low-cost process to grow GaAs nanostructures of a few nm diameter and ∼50 nm height in Pyrex glass wafers. These nanostructures were grown by sequential plasma activation of GaAs and Pyrex glass surfaces using a low-temperature hybrid plasma bonding technology in air. Raman analyses of the activated surfaces show gallium oxide and arsenic oxide, as well as suppressed non-bridging oxygen with aluminate and boroxol chains in glass. The flow of alkaline ions toward the cathode and the replacement of alkaline ions by Ga and As ions in glass result in the growth of GaAs nanostructures in nanopores/nanoscratches in glass. These nanopores/nanoscratches are believed to be the origin of the growth of the nanostructures. It was found that the length of the GaAs nanostructures may be controlled by an electrostatic force. Cross-sectional observation of the bonded interface using high-resolution transmission electron microscopy confirms the existence of the nanostructures. A possible application of the nanostructures in glass is a filtration system for biomolecules.

Fabrication and Experimental Characterization of Nanochannels

Nanofluidics is the science and technology involving a fluid flowing in or around structures with a least one dimension in the nanoscale, which is defined as the range from 1 nm to 100 nm. In this paper, we present the fabrication and characterization of nanochannels in silicon and glass. Since the lateral dimension of the channels is limited by the wavelength of UV light used in photolithography, the channel width can only be fabricated in the micrometer scale. However, the depth of the channel can be controlled precisely by the etching rate of reactive ion etching (RIE). Microchannels and access holes were etched with deep reactive ion etching (DRIE). Both nanochannels and microchannels were sealed by a Pyrex glass wafer using anodic bonding. The fabricated nanochannels were characterized by capillary filling and evaporation experiments. Due to the small channel height and weak fluorescent signal, fluorescent techniques are not suitable for the characterization of the nanochannels. A long exposure time is needed because of the limited amount of fluorescent molecules inhibit the measurement of transient and dynamic processes. However, as the channel height is shorter than all visible wavelengths, the contrast in refractive indices of air and liquid allows clear visualization of nanochannels filled with liquids. Automatic image processing with matlab allows the evaluation of capillary filling in nanochannels. Interesting phenomena and discrepancies with conventional theories were observed.

An electric-field responsive microsystem for controllable miniaturised drug delivery applications

Abstract A novel MEMS based drug delivery device has been developed, consisting of an array of metallic contacts on silicon and Pyrex glass wafers. The meander structured device creates a uniform electric field which stimulates drug release. An electro-active hydrogel based polymer matrix has also been developed, which responds to an electrical stimulus and shrinks or de-swells on application of an electric field from the fabricated device. Different drug candidates can be encapsulated within the polymer matrix. The de-swelling of the polymer enables the encapsulated drug to be released from the matrix. The gel is able to recover its original size once electric stimulation is ceased. By controlling the applied voltage and its duration, the drug release rate and dose can be precisely controlled. Controlled drug delivery devices may be integrated with sensor technology in combined diagnostic/therapeutic point of care devices.

A MEMS-based pneumatic micro-conveyor for planar micromanipulation

This paper present a two dimensional pneumatic actuator based on silicon MEMS technology for objects micro-manipulation using tilted air jets. The device is composed of three layers stacked together, two micro-machined silicon wafers and a Pyrex glass wafer. The system is composed of a set of micro-conveyors in about 9mm×9mm area. Each micro-conveyor has four nozzles and can generate tilted air-jets which allow four conveyance directions. An experiment of the conveyance of a silicon chip of 3mm diameter and weighing approximately 2mg was performed with pulsed air flow.

MEMS Process by Film Transfer Using a Fluorocarbon Anti-Adhesive Layer

A low cost and low temperature microelectromechanical systems (MEMS) transfer process is presented. The process is based on adhesion control of molded electroplated Ni microstructures on the donor wafer by using a plasma deposited fluorocarbon film. Adhesive bonding of the microstructures on the target wafer using BCB sealing enables mechanical tearing off from the donor wafer. This proposed process has allowed us to realize from 7 μm down to 700 nm thick Ni patterns on Si, Pyrex glass wafers and Kapton foils. Multiple transfers lead to Ni stacked microstructures. We demonstrated the interest of a simple film transfer process for the elaboration of 3D microstructures.

A Silicon Microturbopump for a Rankine-Cycle Power-Generation Microsystem—Part II: Fabrication and Characterization

In Part I of this two-part paper, the design approach for a microturbopump was presented. This second part describes the fabrication and experimental characterization of the demo microturbopump device, which includes hydrostatic bearings, a spiral-groove viscous pump, and a multistage microturbine. The device is composed of five wafers: one glass wafer, one silicon-on-insulator (SOI) wafer, and three silicon wafers. The silicon and SOI wafers are patterned using shallow and deep reactive ion etching (total of 14 masks), while the Pyrex glass wafer was ultrasonically drilled. Anodic bonding, fusion bonding, and manual assembly with alignment structures were then used to complete the device and enclose the 4-mm-diameter rotor. The approach allowed the microfabrication of unique interdigitated blade rows in the microturbine and interchangeable parts for flexible testing. After completion of the device, bearings were first tested in static and dynamic conditions. Then, the turbine was characterized with compressed air only and spun up to 330 000 r/min, producing 0.38 W of mechanical power. The pump performance map was also completely characterized for speeds up to 120 000 r/min, showing a maximum pump flow rate of 9 mg/s and maximum pressure rise of 240 kPa. In a turbopump system performance test using compressed air to the turbine and water in the pump, the rotor was spun up to 116 000 r/min, which corresponds to 25 m/s in tip speed. At this condition, the turbine produced 0.073 W of mechanical power with 41 kPa of differential pressure and 24 mg/s of flow rate, and the pump pressurized water by 88 kPa with a flow rate of 4 mg/s, maintaining constant efficiency of 7.2% over the operating range. Out of the total power produced by the turbine, 10% was consumed by the viscous pump, while the rest was dissipated by other components through viscous drag. The system-level predictions by models introduced in Part I also match the measured performance, suggesting that a valid design basis has been established for this type of rotating micromachine.

TMMF dry film resist as masking layer in deep etching of Pyrex-glass for microfluidic chip fabrication

We present the application of dry film resist (TMMF) as new masking technology to process glass wafers using standard wet etching. The considered microfluidic chip features patterned metal electrodes for impedance sensing and hydraulic access holes fabricated on a Pyrex wafer. Therefore, deep etching of through holes, while protecting the deposited metal structures on the Pyrex glass wafer, is required. To achieve this, amorphous silicon (a-Si) was used as masking layer on one side and unexposed TMMF dry film resist was used as mask on the other side of the wafer. The a-Si and TMMF are excellent masking layers in deep-wet etching for Pyrex wafers with etch duration more than 1 hour in 49% hydrofluoric (HF) acid.

MEMS Process by Film Transfer Using Fluorocarbon Anti-Adhesive Layer

A low cost and low temperature MEMS transfer process is presented. The process is based on adhesion control of molded electroplated Ni microstructures on donor wafer by using plasma deposited fluorocarbon film. Adhesive bonding of the microstructures on the target wafer using BCB sealing enables mechanical tearing out from the donor wafer. This proposed process has allowed us to realize from 7 µm down to 700 nm thick Ni patterns on Si, Pyrex glass wafers and Kapton foils. Multiple transfers lead to Ni stacked microstructures. 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 various applications and brings new perspectives towards 3D integration of MEMS/NEMS.

An X band RF MEMS switch based on silicon-on-glass architecture

Communication systems such as those used on satellite platforms demand high performance from individual components that make up the various systems and sub-systems. Switching and routing of RF signals between various modules is a routine and critical operation that determines the overall efficiency of the entire system. In this paper, we present the design and fabrication aspects of a direct contact RF MEMS switch designed to operate in the X band (8–12 GHz) with a target insertion of about 0·5 dB and isolation better than 30 dB. The actuation voltage is expected to be around 50 V. The die size is designed to be 3 mm (H) × 3 mm(W) × 2 mm(H). The switch is built from a low residual stress device layer of a highly conducting (0·005 Ohms-cm) silicon on insulator (SOI) wafer. After subsequent lithographic steps, the wafer is bonded to a Pyrex glass wafer which has been previously patterned with gold transmission lines and pull in electrodes. Being built from a single crystal silicon structure, the mechanical robustness of the actuator is much greater than the those in similar membrane-based devices. A 6 mask fabrication process utilizing Deep Reactive Ion Etching to achieve high aspect ratio stiction free structures was developed and implemented. Devices from the first fabrication run are being analysed in our laboratory.

Wafer level sealing characterization method using Si micro cantilevers

In this study, a wafer level sealing characterization method using the pressure dependence of the mechanical quality factor of Si micro cantilevers has been developed. Since the equation for design of a cantilever near fixed walls in free molecular flow regime has not been derived, a new equation has been proposed. We determine that the minimum measurable pressure necessary for the characterization of MEMS sealing is 0.1 Pa, and the suitable sensor type is the resonant type using the optical measurement method. The devices are fabricated from silicon-on-insulator (SOI) and pyrex glass wafers and have many cavities in which there are three cantilever structures. A measurable pressure range of 10 −2 to 10 3 Pa is achieved. The errors in the quality factors calculated by the proposed equation are influenced by the cantilever dimensions; the energy dissipation of the cantilever (180 μm × 40 μm × 5 μm) is calculated with an error of less than 22%.

A Piezoelectric Micropump Based on MEMS Fabrication

This paper presents a valve-less micropump which is actuated by a piezoelectric ceramic chip. We employ a microelectromechanical system process for the silicon substrate and anodic bonding for assembly of the Pyrex glass and silicon wafer. The reciprocating type micropump contains two nozzle/diffuser elements and a silicon membrane with an embedded piezoelectric ceramic actuator.

Laterally stacked glass substrates with high density electrical feedthroughs

This paper reports a novel method to produce high density feedthrough glass wafers with sufficient thickness for the packaging and interconnection of high density array micro electromechanical systems (MEMS). Pyrex glass wafers with thin film metal lines on the surface are stacked and bonded with each other using phenyl methyl siloxane-based adhesive. The stacked glass wafer block is then sliced using a wire saw as the slicing surfaces cross the adhesive bonding interfaces vertically. Prototyped feedthrough glass wafers were subjected to anodic bonding to a silicon wafer with diaphragms. The anodic bonding was successful, but hermetic sealing was not achieved. The bending of the bonded sample can be reduced by annealing the sample at 400 °C in a vacuum before anodic bonding.