philip D prewett - Academia.edu (original) (raw)
Papers by philip D prewett
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Helium ion beam lithography (HIBL), an emerging technique that uses a sub-nanometre focused beam ... more Helium ion beam lithography (HIBL), an emerging technique that uses a sub-nanometre focused beam of helium ions to expose resist, has introduced an alternative to electron beam lithography (EBL) to extend beyond existing minimum feature sizes. HIBL has several advantages over EBL, including a higher patterning resolution due to a smaller spot size [1] and a reduced proximity effect due to low ion backscattering and deflection [2, 3]. However, there is yet to be a direct comparison of these two techniques on thin layer resists. Here, we present a quantitative and direct comparison study on EBL and HIBL with respect to sensitivity and proximity effects using poly(methyl methacrylate) (PMMA), an established benchmark EBL resist, leading to a demonstration of high resolution HIBL patterning of line arrays.
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Microelectronic Engineering, 2014
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Applied Physics Letters, 2017
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Microelectronic Engineering, 2016
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Micro-Electro-Opto-Mechanical-Systems or MOEMS have potential applications inter alia in biomedic... more Micro-Electro-Opto-Mechanical-Systems or MOEMS have potential applications inter alia in biomedical research. For instance, studies of the Bystander Effect require controlled irradiation of biological cells with focused X-rays to reveal the mechanisms occurring. X-ray focusing may be achieved using an adaptive optic micro-lens in which focusing is entirely reflective and therefore compatible with broad band illumination, an improvement over diffractive systems such as zone plates. Such a micro-lens can be microfabricated in the form of a bent-cantilever beam made from two dissimilar materials (polyimide and gold) in a thermal bimorph configuration, actuated with a micro heater. The parallel horizontal slots on the beam provide the transmission and focusing functions, while the heater provides control of the focal length through variation of the beam’s curvature. This novel system has been named 1D-MOXI (Micro-Opto-X-ray Imaging) and a basic system has already been made and tested thermo-mechanically. The present paper focuses on details of the geometry of the deformed slotted micro-beam lens element under thermally derived strain, using finite element analysis, and suggests an optimized MOEMS design, giving prescribed curvature of the lens through changing the number and the dimensions of the slots. The study reveals the localized stress and the small deviations of the micro-lens behavior from that of perfect spherical geometry. The focal length variation with temperature is compared with the experimental values and those predicted by an analytical model.
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X-ray micro/nano tomography is a powerful tool to reveal inside structures of a sample, either an... more X-ray micro/nano tomography is a powerful tool to reveal inside structures of a sample, either an IC chip or a porous material. A challenge in X-ray tomography is to select a correct threshold to ensure the reconstructed models as close to the reality as possible. This paper presents a study to use scanning electron microscope (SEM) images as references for
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ABSTRACT Focused Ion Beam (FIB) is generally used for machining of solid and bulk materials. Howe... more ABSTRACT Focused Ion Beam (FIB) is generally used for machining of solid and bulk materials. However, new applications such as FIB nanotomography of nanoporous surfaces require sputtering yield characterisation. This paper presents the study of the FIB sputtering yield of Ga+ on nanoporous catalyst layers (CL) of a polymer electrolyte fuel cell (PEFC) based on analytical calculations and SEM stereo imaging experiments. It is shown that a porosity of around 50% has a significant effect (approximately 400%) on the sputtering yield of materials.
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The use of scanning electron microscope (SEM) images as references for threshold tuning of X-ray ... more The use of scanning electron microscope (SEM) images as references for threshold tuning of X-ray micro/nano computed tomography reconstruction is proposed. In this research, high-resolution SEM images were used to provide a good estimation of the fibre diameter in the surface of gas diffusion layers (GDL) (5-10 mum). The X-ray tomography reconstructed binary images containing 3D information, including both the surface and the inside volume. Using the SEM images of a particular feature in carbon fibres, GDL layers were compared with the reconstructed surface of that feature from X-ray tomography data and provided the threshold estimation for reconstruction of the whole structure. Fibre diameter and continuity of the material from both the CT reconstruction and SEM images were analysed to obtain the optimum reconstruction. A linear relationship between fibre diameter and threshold variation has been found for micro/nano tomography of GDL layers.
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Microsystem …, 2002
... Piezoceramics such as lead zirconate titanate (PZT) have been widely used in MEMS applica-tio... more ... Piezoceramics such as lead zirconate titanate (PZT) have been widely used in MEMS applica-tions. ... 2. The PMMA micro-moulds can be made by various existing methods such as LIGA (German acronym for X-ray lithography, electrodeposition Fig. ...
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Microelectronic engineering, 2004
... Research Centre for Micro Engineering and Nano Technology, School of Engineering, The Univers... more ... Research Centre for Micro Engineering and Nano Technology, School of Engineering, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. ... Conventional SU-8 processes often create a trench with wide top and narrow bottom, known as the T-shape, which is ...
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Microelectronic Engineering, 2014
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… , 1996. IVMC'96., …, 1996
... Sci. Technol. B 14, (1996), in press 6. SE Huq, M. Huang, PRWilshaw and P. D. Prewett, submit... more ... Sci. Technol. B 14, (1996), in press 6. SE Huq, M. Huang, PRWilshaw and P. D. Prewett, submitted to IVMC'96 7. EC Boswell, M. Huang, GDW Smith and PR Wilshaw, J. Vac. Sci. Technol. ... Phys. Lett. 63,266 1 (1 993) 12. EC Boswell and P. R. Wilshaw, J. Vac. Sci. Technol. ...
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Microelectronic Engineering, 2011
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Journal of Experimental Nanoscience, 2009
Microelectromechanical systems (MEMS) are devices that represent the integration of mechanical an... more Microelectromechanical systems (MEMS) are devices that represent the integration of mechanical and electrical components in the micrometer regime. Self-assembled monolayers (SAMs) can be used to functionalise the surface of MEMS resonators in order to fabricate chemically specific mass sensing devices. The work carried out in this article uses atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) data to investigate
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Helium ion beam lithography (HIBL), an emerging technique that uses a sub-nanometre focused beam ... more Helium ion beam lithography (HIBL), an emerging technique that uses a sub-nanometre focused beam of helium ions to expose resist, has introduced an alternative to electron beam lithography (EBL) to extend beyond existing minimum feature sizes. HIBL has several advantages over EBL, including a higher patterning resolution due to a smaller spot size [1] and a reduced proximity effect due to low ion backscattering and deflection [2, 3]. However, there is yet to be a direct comparison of these two techniques on thin layer resists. Here, we present a quantitative and direct comparison study on EBL and HIBL with respect to sensitivity and proximity effects using poly(methyl methacrylate) (PMMA), an established benchmark EBL resist, leading to a demonstration of high resolution HIBL patterning of line arrays.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Microelectronic Engineering, 2014
Bookmarks Related papers MentionsView impact
Applied Physics Letters, 2017
Bookmarks Related papers MentionsView impact
Microelectronic Engineering, 2016
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Micro-Electro-Opto-Mechanical-Systems or MOEMS have potential applications inter alia in biomedic... more Micro-Electro-Opto-Mechanical-Systems or MOEMS have potential applications inter alia in biomedical research. For instance, studies of the Bystander Effect require controlled irradiation of biological cells with focused X-rays to reveal the mechanisms occurring. X-ray focusing may be achieved using an adaptive optic micro-lens in which focusing is entirely reflective and therefore compatible with broad band illumination, an improvement over diffractive systems such as zone plates. Such a micro-lens can be microfabricated in the form of a bent-cantilever beam made from two dissimilar materials (polyimide and gold) in a thermal bimorph configuration, actuated with a micro heater. The parallel horizontal slots on the beam provide the transmission and focusing functions, while the heater provides control of the focal length through variation of the beam’s curvature. This novel system has been named 1D-MOXI (Micro-Opto-X-ray Imaging) and a basic system has already been made and tested thermo-mechanically. The present paper focuses on details of the geometry of the deformed slotted micro-beam lens element under thermally derived strain, using finite element analysis, and suggests an optimized MOEMS design, giving prescribed curvature of the lens through changing the number and the dimensions of the slots. The study reveals the localized stress and the small deviations of the micro-lens behavior from that of perfect spherical geometry. The focal length variation with temperature is compared with the experimental values and those predicted by an analytical model.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
X-ray micro/nano tomography is a powerful tool to reveal inside structures of a sample, either an... more X-ray micro/nano tomography is a powerful tool to reveal inside structures of a sample, either an IC chip or a porous material. A challenge in X-ray tomography is to select a correct threshold to ensure the reconstructed models as close to the reality as possible. This paper presents a study to use scanning electron microscope (SEM) images as references for
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
ABSTRACT Focused Ion Beam (FIB) is generally used for machining of solid and bulk materials. Howe... more ABSTRACT Focused Ion Beam (FIB) is generally used for machining of solid and bulk materials. However, new applications such as FIB nanotomography of nanoporous surfaces require sputtering yield characterisation. This paper presents the study of the FIB sputtering yield of Ga+ on nanoporous catalyst layers (CL) of a polymer electrolyte fuel cell (PEFC) based on analytical calculations and SEM stereo imaging experiments. It is shown that a porosity of around 50% has a significant effect (approximately 400%) on the sputtering yield of materials.
Bookmarks Related papers MentionsView impact
The use of scanning electron microscope (SEM) images as references for threshold tuning of X-ray ... more The use of scanning electron microscope (SEM) images as references for threshold tuning of X-ray micro/nano computed tomography reconstruction is proposed. In this research, high-resolution SEM images were used to provide a good estimation of the fibre diameter in the surface of gas diffusion layers (GDL) (5-10 mum). The X-ray tomography reconstructed binary images containing 3D information, including both the surface and the inside volume. Using the SEM images of a particular feature in carbon fibres, GDL layers were compared with the reconstructed surface of that feature from X-ray tomography data and provided the threshold estimation for reconstruction of the whole structure. Fibre diameter and continuity of the material from both the CT reconstruction and SEM images were analysed to obtain the optimum reconstruction. A linear relationship between fibre diameter and threshold variation has been found for micro/nano tomography of GDL layers.
Bookmarks Related papers MentionsView impact
Microsystem …, 2002
... Piezoceramics such as lead zirconate titanate (PZT) have been widely used in MEMS applica-tio... more ... Piezoceramics such as lead zirconate titanate (PZT) have been widely used in MEMS applica-tions. ... 2. The PMMA micro-moulds can be made by various existing methods such as LIGA (German acronym for X-ray lithography, electrodeposition Fig. ...
Bookmarks Related papers MentionsView impact
Microelectronic engineering, 2004
... Research Centre for Micro Engineering and Nano Technology, School of Engineering, The Univers... more ... Research Centre for Micro Engineering and Nano Technology, School of Engineering, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. ... Conventional SU-8 processes often create a trench with wide top and narrow bottom, known as the T-shape, which is ...
Bookmarks Related papers MentionsView impact
Microelectronic Engineering, 2014
Bookmarks Related papers MentionsView impact
… , 1996. IVMC'96., …, 1996
... Sci. Technol. B 14, (1996), in press 6. SE Huq, M. Huang, PRWilshaw and P. D. Prewett, submit... more ... Sci. Technol. B 14, (1996), in press 6. SE Huq, M. Huang, PRWilshaw and P. D. Prewett, submitted to IVMC'96 7. EC Boswell, M. Huang, GDW Smith and PR Wilshaw, J. Vac. Sci. Technol. ... Phys. Lett. 63,266 1 (1 993) 12. EC Boswell and P. R. Wilshaw, J. Vac. Sci. Technol. ...
Bookmarks Related papers MentionsView impact
Microelectronic Engineering, 2011
Bookmarks Related papers MentionsView impact
Journal of Experimental Nanoscience, 2009
Microelectromechanical systems (MEMS) are devices that represent the integration of mechanical an... more Microelectromechanical systems (MEMS) are devices that represent the integration of mechanical and electrical components in the micrometer regime. Self-assembled monolayers (SAMs) can be used to functionalise the surface of MEMS resonators in order to fabricate chemically specific mass sensing devices. The work carried out in this article uses atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) data to investigate
Bookmarks Related papers MentionsView impact