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Article
Publication date: 29 April 2014

Tijjani Adam and U. Hashim

The purpose of this study is to present reports on fabrication of silicon (Si) nanowires (NWs). The study consists of microwire formation on silicon-on-insulator (SOI) that was…

Abstract

Purpose

The purpose of this study is to present reports on fabrication of silicon (Si) nanowires (NWs). The study consists of microwire formation on silicon-on-insulator (SOI) that was fabricated using a top-down approach which involved conventional photolithography coupled with shallow anisotropic etching.

Design/methodology/approach

A 5-inch p-type silicon-on-insulator (SOI) coated with 250nm layer and Photoresist (PR) with thickness of 400nm is coated in order to make pattern transfer via binary mask, after the exposure and development, a resist pattern between 3 μm-5 μm were obtained, Oxygen plasma spreen was used to reduce the size of the PR to 800 μm, after this, the wafer with 800 μm was loaded into SAMCO inductively coupled plasma (ICP)-RIE and got silicoon microwire was obtained. Next, the sample was put into an oxidation furnace for 15, 30, 45 and 60 minutes and the sample was removed and dipped into a buffered oxide etch solution for five minutes to remove all the SiO2 ashes.

Findings

The morphological characterization was conducted using scanning electron microscopy and atomic force microscopy. At terminal two, gold electrodes which were designated as source and drain were fabricated on top of individual NWs using conventional lithography electrical and chemical response. Once the trimming process has been completed, the device's current–voltage (I-V) characteristic was measured by using a Keithley 4200 semiconductor parameter analyser. Devices with different width of wires approximately 20, 40, 60 and 80 nm were characterized. The wire current variation as a function of the pH variation in voltage was investigated: pH monitoring for variations of pH values between 5 and 9.

Originality/value

This paper provides useful information on novel and yet simple cost-effective fabrication of SiNW; as such, it should be of interest to a broad readership, especially those interested in micro/nanofabrication.

Details

Microelectronics International, vol. 31 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 March 2002

Michael Huff

Describes the key attributes of MEMS technology and existing and future business opportunities. Discusses the various stages in the fabrication of MEMS devices and offers guidance…

3897

Abstract

Describes the key attributes of MEMS technology and existing and future business opportunities. Discusses the various stages in the fabrication of MEMS devices and offers guidance regarding the selection of processing methods for deposition, lithography and etching. Also describes the MEMS‐Exchange program and associated network of fabrication centres.

Details

Sensor Review, vol. 22 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 July 2006

Javad Dargahi, Mojtaba Kahrizi, Nakka Purushotham Rao and Saeed Sokhanvar

To measure the force applied to the tissue, the traditional endoscopic graspers might be equipped with a kind of tactile force sensor.

1556

Abstract

Purpose

To measure the force applied to the tissue, the traditional endoscopic graspers might be equipped with a kind of tactile force sensor.

Design/methodology/approach

This paper presents the design, analysis, microfabrication and testing of a piezoelectric and capacitive endoscopic tactile sensor with four teeth. This tactile sensor, which is tooth‐like for safe grasping, comprises a Polyvinylidene Fluoride, PVDF film for high sensitivity and is silicon‐based for micromachinability. Being a hybrid sensor, employing both capacitive and piezoelectric techniques, it is possible to measure both the static and dynamic loads. Another feature, to be considered in its design, is the ability to detect pulse. The proposed sensor can be integrated with the tip of any current commercial endoscopic grasper without changing its original design. It is shown that using an array of sensor units, the position of the applied load can still be determined.

Findings

The static response of the sensor is obtained by applying a static force on the tooth and measuring the change in capacitance between the bottom electrode of the PVDF film and the electrode deposited on the surface of the etched cavity. The dynamic response of the device is determined by applying a sinusoidal force on the tooth of the sensor and measuring the output voltage from the PVDF film. The experimental results are compared with both analytical and finite element results. The sensor exhibits high sensitivity and linearity.

Originality/value

Capaciyive and piezoelectic are used to obtain both dynamic,pulse, and static loads. The sensor micromachined so, it can be used in various endoscopic applications.

Details

Sensor Review, vol. 26 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 5 January 2015

Norihan Abdul Hamid, J. Yunas, B. Yeop Majlis, A.A. Hamzah and B. Bais

The purpose of this paper is to discuss the fabrication technology and test of thermo-pneumatic actuator utilizing Si3N4-polyimide thin film membrane. Thin film polyimide membrane…

Abstract

Purpose

The purpose of this paper is to discuss the fabrication technology and test of thermo-pneumatic actuator utilizing Si3N4-polyimide thin film membrane. Thin film polyimide membrane capped with Si3N4 thin layer is used as actuator membrane which is able to deform through thermal forces inside an isolated chamber. The fabricated membrane will be suitable for thermo-pneumatic-based membrane actuation for lab-on-chip application.

Design/methodology/approach

The actuator device consisting of a micro-heater, a Si-based micro-chamber and a heat-sensitive square-shaped membrane is fabricated using surface and bulk-micromachining process, with an additional adhesive bonding process. The polyimide membrane is capped with a thin silicon nitride layer that is fabricated by using etch stop technique and spin coating.

Findings

The deformation property of the membrane depend on the volumetric expansion of air particles in the heat chamber as a result of temperature increase generated from the micro-heater inside the chamber. Preliminary testing showed that the fabricated micro-heater has the capability to generate heat in the chamber with a temperature increase of 18.8 °C/min. Analysis on membrane deflection against temperature increase showed that heat-sensitive thin polyimide membrane can perform the deflection up to 65 μm for a temperature increase of 57°C.

Originality/value

The dual layer polyimide capped with Si3N4 was used as the membrane material. The nitride layer allowed the polyimide membrane for working at extreme heat condition. The process technique is simple implementing standard micro-electro-mechanical systems process.

Details

Microelectronics International, vol. 32 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 11 September 2009

Craig Lowrie, Marc P.Y. Desmulliez, Lars Hoff, Ole Jakob Elle and Erik Fosse

The purpose of this paper is to review the design and fabrication of a micro‐accelerometer to be used to measure the heart wall motion of patients who have just undergone coronary…

Abstract

Purpose

The purpose of this paper is to review the design and fabrication of a micro‐accelerometer to be used to measure the heart wall motion of patients who have just undergone coronary artery bypass graft (CABG) surgery. The sensor will provide a means of early warning for the medical staff of associated complications with this surgery occurring.

Design/methodology/approach

A feasibility paper is carried out with the use of commercially available MEMS three‐axis accelerometers. The sensors are used in animal studies during which the sensor is stitched directly to the surface of a pig's heart. A need for smaller sensors is required and these are designed in‐house and fabricated using a MEMS process. The final dimensions of the sensors are 2.5×3.5×1.4 mm in width, length and height, respectively.

Findings

The results of the feasibility studies demonstrate the viability of this type of sensor for heart wall motion measurement. It is possible to detect abnormalities, which can indicate complications associated with CABG. The sensors presented here are fabricated within the tight overall size specifications deemed necessary for this application.

Research limitations/implications

This paper demonstrates an application of MEMS for implantable medical sensors.

Practical implications

In the UK, approximately 300,000 people have a heart attack each year. One of the most common surgeries that is used to treat this is CABG. This sensor is to be used by the medical staff in post‐surgery to provide “real‐time” monitoring of the heart and give early warning of regional cardiac ischemia which can save lives and reduce hospital waiting times and costs.

Originality/value

This paper demonstrates an original way of measuring heart wall motion. Results from the feasibility studies have proven that this can provide an invaluable way of providing early warning of complications after heart surgery.

Details

Sensor Review, vol. 29 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 December 2005

A. Arshak, K. Arshak, G. Lyons, D. Waldron, D. Morris, O. Korostynska and E. Jafer

Telemetry capsules have existed since the 1950s and were used to measure temperature, pH or pressure inside the gastrointestinal (GI) tract. It was hoped that these capsules would…

1443

Abstract

Purpose

Telemetry capsules have existed since the 1950s and were used to measure temperature, pH or pressure inside the gastrointestinal (GI) tract. It was hoped that these capsules would replace invasive techniques in the diagnosis of function disorders in the GI tract. However, problems such as signal loss and uncertainty of the pills position limited their use in a clinical setting. In this paper, a review of the capabilities of microelectromechanical systems (MEMS) for the fabrication of a wireless pressure sensor microsystem is presented.

Design/methodology/approach

The circuit requirements and methods of data transfer are examined. The available fabrication methods for MEMS sensors are also discussed and examples of wireless sensors are given. Finally, the drawbacks of using this technology are examined.

Findings

MEMS for use in wireless monitoring of pressure in the GI tract have been investigated. It has been shown that capacitive pressure sensors are particularly suitable for this purpose. Sensors fabricated for wireless continuous monitoring of pressure have been reviewed. Great progress, especially using surface micromachining, has been made in recent years. However, despite these advances, some challenges remain.

Originality/value

Provides a review of the capabilities of MEMS.

Details

Sensor Review, vol. 25 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 July 2006

P.A. Alvi, B.D. Lourembam, V.P. Deshwal, B.C. Joshi and J. Akhtar

To fabricate submicrometer thin membrane of silicon nitride and silicon dioxide over an anisotropically etched cavity in (100) silicon.

Abstract

Purpose

To fabricate submicrometer thin membrane of silicon nitride and silicon dioxide over an anisotropically etched cavity in (100) silicon.

Design/methodology/approach

PECVD of silicon dioxide and Silcion nitride layers of compatible thicknesses followed by thermal annealing in nitrogen ambients at 1,000°C for 30 min, leads to stable membrane formation. Anisotropic etching of (100) silicon below the membrane through channels on the sides has been used with controlled cavity dimensions.

Findings

Lateral front side etching through channels slows down etching rate drastically. The etching mechanism has been discussed with experimental details.

Practical limitations/implications

Vacuum sealed cavity membranes can be realised for micro sensor applications.

Originality/value

The process is new and feasible for micro sensor technologies.

Details

Sensor Review, vol. 26 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 25 January 2011

Pradeep Kumar Rathore and Jamil Akhtar

The purpose of this paper is to describe the fabrication of a miniaturized membrane type double cavity vacuum‐sealed micro sensor for absolute pressure using front‐side lateral…

Abstract

Purpose

The purpose of this paper is to describe the fabrication of a miniaturized membrane type double cavity vacuum‐sealed micro sensor for absolute pressure using front‐side lateral etching technology.

Design/methodology/approach

Potassium hydroxide‐based anisotropic etching of single crystal silicon is used to realize the cavities under the membrane type diaphragms through channels on the sides. The diaphragms consist of composite layers of plasma‐enhanced chemical vapour deposition (PECVD) of silicon nitride and silicon dioxide. PECVD of silicon dioxide is done for sealing the channels and the cavity in vacuum. Boron thermal diffusion in low‐pressure chemical vapour deposition of polysilicon layer over the membrane is done for realizing resistors. The fabricated device uses Wheatstone half bridge circuit to read the variation of resistance with respect to an applied pressure.

Findings

A double cavity vacuum‐sealed absolute pressure micro sensor has been fabricated successfully using front‐side lateral etching technology and has been measured for pressure range of 0‐0.45 MPa. The measured pressure sensitivity of two pressure sensors is 9.28 and 10.44 mV/MPa.

Originality/value

The paper shows that front‐side lateral etching technology is feasible in the fabrication of small vacuum‐sealed cavities and absolute pressure sensors.

Details

Sensor Review, vol. 31 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 December 2004

Vitor da Silva, Rui de Oliveira, David Watts and Erik van der Bij

The ChemicalVia process, patented by CERN, provides a new method of making microvias in high‐density multilayer printed circuit boards of different types, such as sequential…

Abstract

The ChemicalVia process, patented by CERN, provides a new method of making microvias in high‐density multilayer printed circuit boards of different types, such as sequential build‐up (SBU), high density interconnected (HDI), or laminated multi‐chip modules (MCM‐L). The process uses chemical etching instead of laser, plasma or other etching techniques and can be implemented in a chain production line. This results in an overall reduced operation and maintenance cost and a much shorter hole production time as compared with other microvia processes.

Details

Circuit World, vol. 30 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 9 September 2013

Pradeep Kumar Rathore, Pratyush Varshney, Sunil Prasad and B.S. Panwar

The purpose of this paper is to use finite element method for optimizing the membrane type double cavity vacuum sealed structure for the best achievable sensitivity in a…

Abstract

Purpose

The purpose of this paper is to use finite element method for optimizing the membrane type double cavity vacuum sealed structure for the best achievable sensitivity in a piezoresistive absolute pressure sensor and its validation using a standard complementary metal oxide semiconductor (CMOS) process.

Design/methodology/approach

A double cavity vacuum sealed piezoresistive absolute pressure sensor has been simulated and optimized for its performance and an analytical model describing the behaviour of the sensor has been described. The 1×1 mm sensor chip has two membrane type 100×30×1.7 μm diaphragms consisting of composite layers of plasma enhanced chemical vapour deposition (PECVD) of silicon nitride (Si3N4) and silicon dioxide (SiO2) each hanging over 21 μm deep rectangular cavity. Potassium hydroxide (KOH) based anisotropic etching of single crystal silicon using front side lateral etching technology is used for the fabrication of the sensor. The electrical readout circuitry uses 318 Ω boron diffused low pressure vapour chemical vapour deposition (LPCVD) of polysilicon resistors arranged in the Wheatstone half bridge configuration. The sensing structure is simulated and optimized using COMSOL Multiphysics.

Findings

Front-side lateral etching technology has been successfully used for the fabrication of double cavity absolute pressure sensor. A good agreement with the fabricated device for the chosen location of the piezoresistors through simulation has been predicted. The measured pressure sensitivity of two tested pressure sensors is 12.63 and 12.46 mV/MPa, and simulated pressure sensitivity is found to be 12.9 mV/MPa for pressure range of 0 to 0.5 MPa. The location of the piezoresistor has also been optimized using the simulation tools for enhancing the sensor sensitivity to 62.14 mV/MPa. The pressure sensitivity is further enhanced to 92 mV/MPa by increasing the width of the diaphragm to 35 μm.

Originality/value

The simulated and measured pressure sensitivities of the double cavity pressure sensor are in close agreement. Sevenfold enhancement in the pressure sensitivity of the optimized sensing structure has been observed. The proposed front-side lateral etching technology can be adopted for making membrane type diaphragms hanging over vacuum sealed micro-cavities for high sensitivity pressure sensing applications.

1 – 10 of 201