The two dimensional laminar and turbulence stagnation-point flow over a wafer surface within a cleanroom environment are numerically simulated. This study shows the relationship between particle capture area on the wafer and the particle size and flow conditions. The mean flow field is simulated using a two equation k-ϵ turbulence model. Trajectories of aerosol particles are evaluated by solving the corresponding Lagrangian equation of motion that includes effects of drag, gravity, lift force, Brownian motion and turbulence fluctuations. The Brownian motion is modeled as a white noise process and turbulence fluctuation is assumed to behave as Gaussian random process. Simulations are carried out for aerosol particles (of various sizes) released at different locations over the surface. Depositions of particles on the wall are evaluated and a capture area which varies with particle sizes is produced. The results show that Brownian motion becomes very significant when turbulence fluctuations start to disappear near the wall for particles smaller than 1 μ m in diameter. The results also show that, deposition of particles in turbulent flows are usually higher than that in laminar flows for all particle sizes considered. The effect of fluid on particle deposition rate is predicted for fluid of air and water. The results show that, particles deposition rate in air is higher than that in water.

An attempt has been made to summarize some of the important developments in the emerging technology of microelectromechanical systems (MEMS) from the mechanical engineering perspective. In the micro domain, design and fabrication issues are very much different from those of the macro world. The reason for this is twofold. First, the limitations of the micromachining techniques give way to new exigencies that are nonexistent in the macromachinery. One such difficulty is the virtual loss of the third dimension, since most of the microstructures are fabricated by integrated circuit based micromachining techniques that are predominantly planar. Second, the batch-produced micro structures that require no further assembly, offer significant economical advantage over their macro counterparts. Furthermore, electronic circuits and sensors can be integrated with micromechanical structures. In order to best utilize these features, it becomes necessary to establish new concepts for the design of MEMS. A set of key joints and mechanisms using which majority of the mechanical devices can be built, is identified. It is surmised that such an effort will be advantageous in designing micromechanisms as they form the basis for what we call fabrication building blocks (joints) and synthetic building blocks (mechanisms). The paper also reviews some of the fabrication techniques and the micromechanical devices that have already been made, and makes suggestions regarding the fabrication of a few generic mechanisms that can be made using these techniques. In particular, it discusses the fabrication of a motor-driven four-bar linkage using the “boron-doped bulk-silicon dissolved-wafer process” developed at The University of Michigan’s Center for Integrated Sensors and Circuits.

Particle transport and deposition in a CVD chamber and a horizontal diffusion furnace are studied. Mean flow and thermal fields are simulated using GENFLOW, which is a general computer code for fluid flow and heat transfer computations. Trajectories of aerosol particles in the chamber and the furnace are evaluated by solving the corresponding Lagrangian equation of motion that includes effects of temperature, drag, gravity, Brownian motion and turbulence fluctuations generated during pumping or venting. Aerosol particles are released at the gas inlet and are carried towards the wafers with sizes of 0.05–1.0 micron in the CVD chamber and 1.0 micron in the diffusion furnace. Depositions of particles on the wafer, wafer temperature and inlet turbulence intensity are evaluated.

The application of piezoelectric actuators and sensors in the vibration suppression of flexible structures is demonstrated experimentally. Navy Type II piezoceramic wafers were bonded at the base of a flexible arm to increase damping of its first structural mode at at 0.138 Hz. A Positive Position Feedback (PPF) analog compensator was used for active vibration control. The damping of the first mode was increased from 0.3% to 1.5 % by using the active control.

Low pressure chemical vapor deposition (LPCVD) processes are used in the microelectronic manufacturing industry. As circuit dimensions decrease, it becomes ever more critical to control the particulate contamination of the wafer during fabrication. To accurately predict the particle motion, and thus minimize contamination, the flow field must be known. This paper outlines the procedure to numerically simulate the velocity, temperature, and concentration fields in a low pressure application. From these solutions, accurate particle trajectories are predicted using a Lagrangian formulation that includes effects of temperature, drag, gravity, and Brownian motion.

A closed-form method of calculating Input Shaping sequences for two modes of vibration is presented. The new method eliminates the optimization routines previously required to find the same solutions. Input Shaping is a feed forward method of reducing residual vibrations in flexible structures by convolving an Input Shaping sequence with a command profile. The two-mode sequences are installed on a four-axis robot used in the manufacture of silicon wafers — the Cassette Management System. The new sequences are found to significantly improve the performance of the system. In standard throughput tests, speed increases of 15%–25% were obtained on each axis while vibrations were simultaneously reduced by 20%–90%.

Comb actuators are electrostatic drives commonly used in micro-electromechanical systems (MEMS). These devices are typically fabricated using standard Integrated Circuit (IC) fabrication techniques such as lithography, oxidation, chemical vapor deposition and etching. The design of MEMS devices such as comb actuators is a complex process due to the dimensionality of the parametric design space and the parametric interdependencies imposed by performance, manufacturability and reliability constraints. We present a study aimed at the decomposition and structured organization of the various design and manufacturability considerations for comb actuators. The value of this knowledge organization is illustrated by the formulation and solution of a design problem that ensures optimal parametric design and layout of a comb actuator on a silicon wafer. We combine analytical models and specialized fabrication “design rules” to obtain optimal solutions for two interesting problems in MEMS comb actuator design.

High-frequency ultrasonic cleaning is widely used in the semiconductor and other industries affected by contamination for the removal of particulate contamination. High frequency (near 1 MHz) ultrasonic cleaning (known as megasonic cleaning) is specially used in semiconductor manufacturing [1]. Many studies concerning submicron particle removal using megasonic and ultrasonic cleaning has been conducted recently [2–7]. The megsonic cleaning process proved to be the essential processes in cleaning silicon wafers after processes such as CMP, RIE, CVD, Sputter, etc. This paper introduces recent results that involve new techniques for introducing the ultrasonic energy in the cleaning bath.

This paper discusses the approximate and feedback relevant parametric identification of a positioning mechanism present in a wafer stepper. The positioning mechanism in a wafer stepper is used in chip manufacturing processes for accurate positioning of the silicon wafer on which the chips are to be produced. The accurate positioning requires a robust and high performance feedback controller that enables a fast through put of silicon wafers. A set of multivariable finite dimensional linear time invariant discrete time models will be estimated, that is suitable for model-based robust control design of the positioning mechanism.

A simple, practical analytical approach to capacity planning is described in the context of semiconductor wafer fabrication (fab) areas and implementation of Drum-Buffer-Rope methodology. The well validated model integrates bottleneck identification with predictors of headcount requirement, fab activity levels, cycle time and inventory curves, financial impacts and other metrics, as desired, for given volume and mix. The model, used in combination with the knowledge of local experts, provides information for medium or long range planning and for focusing improvement efforts for maximum effect. Opportunities for improvement are simply explained, verified, quantified and prioritized through the use of specific tool models and of Overall Equipment Effectiveness (OEE) as a measure of equipment performance. Several manufacturing areas on the same site can be simultaneously modeled, showing the effect of a change on the entire site.

The megasonic cleaning process proved to be an essential process in cleaning silicon wafers after processes such as pre-oxidation, pre-CVD, pre-EPI, post-ASH and lately post-CMP. Current post-CMP cleans are contact cleaning techniques. These contact techniques have a low throughput and may cause wafer scratching. In addition, in contact cleaning, brush shedding which occurs under many operating conditions causes additional particulate contamination. There is a need for an effective post-CMP cleaning process. Megasonic cleaning provides the best alternative or compliment to brush clean.

Electro-Thermal-Compliant (ETC) micro devices are a new class of compliant mechanisms that elastically deform in response to Joule-heating induced constrained thermal expansion. In ETC devices, the mechanism and the actuator are indistinguishable and therefore it is called embedded actuation. This type of actuation is attractive for Micro-Electro-Mechanical Systems (MEMS) where the actuator is often much larger than the mechanism and the mechanical coupling of the actuator and mechanism leads to additional difficulties. In this paper, we focus on thin, planar, appropriately shaped, deformable structures made of a conducting material to fabricate micro mechanisms with embedded actuation. We have developed a bulk micromachining process, called PennSOIL, using silicon-on-insulator (SOI) wafers to make silicon ETC devices, and also combined PennSOIL with excimer laser micromachining to make ETC devices with not only silicon but also a variety of metals. The experimental measurements are compared with the theoretical predictions. Test-structures are used to characterize the process and the resulting materials properties some of which are strongly temperature-dependent and process-dependent. The experimental results using the materials properties obtained from the test structures show agreement with the theoretical results.

This paper presents a technique to obtain a Design Structure Matrix (DSM) from a Design Matrix (DM). This technique enables us to obtain the design information flow pattern at early stage of the design, and apply the DSM system analysis and management techniques at the time when the most important decisions about the system and the design are made. The validity of this method is proven using a case study on the design integration process of an electrostatic chuck used in semiconductor wafer processing. The algorithm underlying this technique is also proven logically and mathematically to be valid.

Structural acoustic control via passive and hybrid electrical shunting of a piezoceramic wafer bonded onto the surface of a simply supported plate is investigated with emphasis on modeling and understanding the effect of piezoceramic nonlinearity on system performance. A nonlinear rate-independent finite-dimension Ishlinskii hysteresis model is experimentally identified for the PZT wafer by itself and then integrated into the coupled dynamic equations of the overall system consisting of the plate and electrically shunted PZT wafer. This model is then used to investigate the impact of PZT hysteresis on its structural acoustic control performance in passive and hybrid scenarios. A multi-term describing function representation of the Ishlinskii hysteresis model is formulated to aid in computational studies.

Over the past decade, wearable robotics and exoskeletons have been gaining recognition in the field of medical, assistive and augmentative robotics and have led to numerous new innovative mechanisms and designs. Due to fast-paced research activities, the critical importance and performance of established mechanisms such as wrap spring clutch/brake, Wafer Disc Brakes have been overlooked or used ineffectively. This paper describes a practical design approach that will enable the designer to choose a mechanism based on the application of the device, which will promote overall growth in current technology. The Legged Anthropomorphic Robotic Rehabilitation Exoskeleton (LARRE) project used this approach to design, manufacture, and test the knee joint for ground-level walking. This paper provides the reasoning behind the selection of wrap spring clutch, its evaluation, and testing standards as the knee joint. A thorough literature review was conducted to understand the current state of the art. This project collected a rich set of biomechanical data to ensure that the mechanism will produce the right moments and range of motions during walking. To ensure that our mechanism meets the requirements, the mechanism was put through a wide range of stress tests. The paper establishes a methodology to choose a mechanism for an exoskeleton’s joint based on the desired requirements. The outcome of this paper is an analytical based design approach that can be used by other researchers to impart additional traits and weights, which will aid in the development of exoskeleton design.

In this study, a label-free detection approach for effective detection of the odontoglossum ringspot virus (ORSV) infected orchids has been developed. We used semiconductor fabrication process to fabricate 1,810 micro/nano hybrid structured sensing electrodes on a 8 inch reclaimed wafer. The self-assembled monolayer (SAM) process was then employed to sequentially modify the electrode surface with 11-mercaptoundecanoic acid (11-MUA), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/ N-hydroxysuccinimide (NHS), anti-ORSV, and ORSV. EIS was conducted for the ORSV concentration detection. Experimental results demonstrated that the ORSV concentration in a virus infected orchid leaf could be effectively detected. When compared with the ELISA kit, our device possesses a wider linear detection range (0.5–50,000 ng/mL) and a higher sensitivity. The specificity of our device on ORSV detection was also confirmed. Our sensing device retains advantages, such as label-free, lower amounts of the antibody and target sample required, low detection time, and a wider linear detection range. Those results imply the feasibility of our sensing device in field applications.

Gene transfer technology changes some of the characteristics of crops. However, genetically modified foods have been reported to have an impact on human health. We proposed a cost effective and highly sensitive biosensor electrode with self-assembled monolayer of gold nanoparticle on a micro hemisphere array to detect genetically modified soybean. An ordered array of micro hemispherical features was formed on a 6-inch reclaimed silicon wafer using photolithography. Then, a thin gold layer was sputtered onto the hemispheres. The wafer was then immersed into a 5 mM ethanol solution of 1,6-hexanedithiol (1,6-HDT) to enable the attachment of one thio-end of 1,6-HDT to the thin gold layer. Next, a colloidal gold (15 nm) solution was dripped onto the wafer and baked on a hot plate in such a way that the monolayer of gold nanoparticles could self-assemble on the 1,6-HDT surface. Finally, we used electrochemical impedance spectroscopy (EIS) analysis to detect genetically modified soybean. Experimental results demonstrate that our biosensor can successfully distinguish the genetically modified soybeans from the normal ones.

In the Letter, we reported the tension-induced Raman spectrum enhanced phenomena of graphene membrane. The standard micro-fabrication processes are utilized to fabricate micro-scale holes on Silicon-On-Insulator (SOI) wafers, and suspended graphene membranes are transferred onto target substrates with shallow holes and flat substrates using the dry and wet transfer techniques, respectively. The corrugated graphene near the hole is stretched smoothly due to the built-in strain during the transfer processes, and the intensity ratio between the 2D and G bands I 2D /I G >5, which demonstrates the high quality of graphene sheet is obtained under the stretching stress. The intensity ratio between the 2D and G bands would diminish greatly when the graphene membrane is broken. Therefore, the Raman spectrum intensities of graphene membranes can be tuned by the built-in strain. The study can be helpful for further understanding the formation mechanism of corrugated graphene, the suppressing method of the small ripple in graphene, and the way to improve the quality of graphene.

This paper reports on the design, fabrication, and characterization of non-interdigitated comb drive actuators in Silicon-on-Insulator (SOI) wafers, using a single mask surface microma-chining process. The response of the actuator is analyzed numerically and experimentally. The results show at the fundamental frequency; it behaves as a longitudinal comb drive actuator. At a higher frequency, it exhibits a high-quality factor which is appropriate for sensor applications.

A novel design for MEMS capacitive pressure sensors is presented that can effectively eliminate the temperature drift in sensor for high temperature applications. The design uses a bilayer membrane made of a thin metal film deposited on the top of membrane to balance the deformation the membrane experiences when the ambient temperature changes. The thermal expansion mismatch of the metal layer and the membrane results in out-of-plane bending if the temperature changes. This deformation can compensate the deformation in the membrane due to the temperature change. By optimizing the dimensions of the top metal layer (shape and thickness), it is possible to minimize the change in the device capacitance due to temperature rise. A coupled-field multiphysics solver in ANSYS ® APDL is used for design, simulation and optimization of the sensor’s structure and to solve the governing equations of the coupled electrostatic and structural physics. The membrane material is silicon carbide (SiC), the top metal layer is nickel (Ni) and the substrate is a single-crystal silicon wafer. The thickness and dimensions of top metal layer is optimized using FEM simulations. The results display a very stable capacitance value for a large pressure range and over a wide range of ambient temperature (0–600°C), demonstrating the proposed design can effectively eliminate the temperature effect. Different pressure values ranging from 0.0 to 20 bars have been examined in the simulations and for most of the pressure range, a highly stable capacitance value is observed with less than 0.5% error over 600 °C temperature range.