KEYWORDS: Lithography, Gallium nitride, Near field scanning optical microscopy, Scanning tunneling microscopy, Field spectroscopy, Scanning probe microscopy, Near field, Emission spectroscopy, Atomic force microscopy, Spectroscopy
We have investigated the potential of wide bandgap nitride tips, specifically GaN NWs as probes tips for AFM, FEL, STM. The use of GaN nanowires as probes creates the possibility of combining AFM and SPL tools, including STM, and NSOM, so that an ‘’universal multi-purpose probe’’ can be used for several lithography and microscopy techniques. We discuss how nanowires have been integrated with Si cantilevers to form the hybrid III-N and Si lithography probe. We have achieved 0.7 nm lithography features in STM mode, sub 7.5 nm lithography in FESPL mode, and optical waveguides into it to allow NSOM measurement and NSOM detection.
KEYWORDS: Sensors, Microopto electromechanical systems, Micromirrors, Calibration, Electronics, Head, Laser sources, System integration, Signal to noise ratio, Data acquisition
Cantilever based sensor system are a well-established sensor family exploited in several every-day life applications as well as in high-end research areas. The very high sensitivity of such systems and the possibility to design and functionalize the cantilevers to create purpose built and highly selective sensors have increased the interest of the scientific community and the industry in further exploiting this promising sensors type. Optical deflection detection systems for cantilever sensors provide a reliable, flexible method for reading information from cantilevers with the highest sensitivity. However the need of using multi-cantilever arrays in several fields of application such as medicine, biology or safety related areas, make the optical method less suitable due to its structural complexity. Working in the frame of a the Joint Undertaking project Lab4MEMS II our group proposes a novel and innovative approach to solve this issue, by integrating a Micro-Opto-Electro-Mechanical-System (MOEMS) with dedicated optics, electronics and software with a MOEMS micro-mirror, ultimately developed in the frame of Lab4MEMSII. In this way we are able to present a closely packed, lightweight solution combining the advantages of standard optical read-out systems with the possibility of recording multiple read-outs from large cantilever arrays quasi simultaneously.
In this article we describe application of piezoresistive cantilevers in surface investigations carried out with the use of
shear force microscopy (ShFM). The novel piezoresistive cantilevers integrate a Wheatstone piezoresistive bridge was
used to detect the cantilever deflection, thermal deflection detector and planar tip protruding out of the spring beam.
Because the planar tip deflection can be detected and controlled electronically the described technology is very flexible
and can be applied in many surface investigations. In this article we will present operation theory of the described
solution, experimental setup, methods for calibration of the tip deflection detection and actuation The analysis will be
illustrated with example results of topography measurements performed using the described technology.
In this article we describe a novel piezoresistive cantilever technology The described cantilever can be also applied in the
investigations of the thermal surface properties in all Scanning Thermal Microscopy (SThM) techniques. Batch
lithography/etch patterning process combined with focused ion beam (FIB) modification allows to manufacture thermally
active, resistive tips with a nanometer radius of curvature. This design makes the proposed nanoprobes especially
attractive for their application in the measurement of the thermal behavior of micro- and nanoelectronic devices.
Developed microcantilever is equipped with piezoresistive deflection sensor. The proposed architecture of the cantilever
probe enables easy its easy integration with micro- and nanomanipulators and scanning electron microscopes.In order to
approach very precisely the microcantilever near to the location to be characterized, it is mounted on a compact
nanomanipulator based on a novel mobile technology. This technology allows very stable positioning, with a nanometric
resolution over several centimeters which is for example useful for large samples investigations. Moreover, thanks to the
vacuum-compatibility, the experiments can be carried out inside scanning electron microscopes.
In this paper technology of scanning probe microscopy (SPM) surface metrology using arrays of piezoresistive thermally actuated cantilevers is discussed. The cantilever architecture presented here makes it possible to image surface topography using sensors operating in parallel. In this way the throughput of the sample imaging is increased, which is of crucial importance in measurements of large area samples. Application of piezoresistive detection scheme makes it possible to investigate quantitatively the interaction between the microprobe and the imaged surface. Integration of the thermal deflection actuator with the spring beam decreases the response time and enables fast and high resolution control of the tip sample distance. The results of topography parallel measurement using 1×4 cantilever array will be presented.
Increased interest in micro-and nano-electromechanical systems (MEMS and NEMS) entail the development of reliable measurement techniques for the basic parameters of the designed and manufactured devices. The proposed methodology should provide high resolution, wide frequency range and the possibility to investigate both mechanical and electrical parameters during inspection process. In this article authors present methods for manufacturing of electrostatic MEMS devices. Measurement techniques will be presented for specifying parameters such as resonant frequency, quality factor and sensitivity of the previously manufactured structures. Manufacturing techniques will be presented on the example of the micropusher structure, whereas measurement techniques will be presented on the example of the microgripper structure.
The dielectric barrier discharge (DBD) used to generate low-temperature plasmas at atmospheric pressure are suitable for
the atomization of volatile species and can also be served as an ionization source for ambient mass spectrometry and ion
mobility spectrometry. The paper presents a source based on a plasma jet established at the end of a capillary dielectric
barrier discharge at atmospheric pressure and its application to mass spectrometry. Early results of spectroscopic analysis
are given.
In this work we present the grid of microstructures which is used for the graphene mechanical and electrical properties
investigations. The design of the mask used for the grid production was presented. Afterwards the technological process
steps for the grid production were described. In result the support structures – trenches – in shape of lines, squares and
circles are obtained with the detail dimensions varied from 1 micrometer up to 30 micrometers. Examples of graphite
and graphene deposited on the support structures are also presented.
Microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) are the promising platforms for
mass change observations. These systems in optimal solutions allow to observe the deposition of single molecules. This
is achieved by the structure miniaturization which entails increase of resolution. In this paper, we present fabrication
process of silicon nitride double-clamped beam structures. Moreover, it is presented the basic description of the beam
mechanics which is based on the Euler-Bernoulli beam theory. Additionally results of the measurements of the fabricated
devices are shown. Thanks to the possibility of recording force curves at nanometer deflections using atomic force
microscopy (AFM) system there is a possibility to determine the properties of the MEMS and/or NEMS devices. The
obtained experimental results show that the parameters of the fabricated structures differ basing on the theoretical ones,
which were calculated from the elasticity theory. This results from the stress in the silicon nitride film, which forms the
elastic beam structure and from the stress in the metallization deposited on the bridge. The influence of the described
factors on the bridge structure properties is also described. Bridge structures with thickness of 120 nm, width and length
ranging from 3 to 10 μm and from 20 μm to 80 μm respectively were investigated.
In this paper authors present two methods of determining the cantilever displacement sensitivity. In both cases the
cantilevers are examined in dynamic condition for cantilever vibrating with frequency range close to resonance
frequency. One of the method uses as measurement tool a white light interferometer, the another one uses the laser
interferometric vibrometer. For adequate comparing methods, obtained results refer to the same cantilever with
piezoresistive Wheatstone bridge. In this paper authors also present the fabrication process of piezoresistive cantilevers
with planar tip adapted for working in a shear force [1]. Additionally the piezoresistive circuit characterization by
impedance spectroscopy is presented. Finally the spring constant is determined basing on frequency response of the
cantilever measured from thermal noise density [2]. Basing on obtained results authors made a conclusion that both
methods can be successfully used for accurate characterization piazoresistive cantilevers work in a non-contact
resonance mode.
This paper is focused on manufacture technology of molecular self-assembled monolayers (SAM) using
microcontact printing (μCP) techniqe. This technique, due to its low-cost and simplicity, is a very attractive one for
further development of molecular electronics and nanotechnology. The SAM can be produced on gold or silicon oxide
using thiol and silane based chemistry respectively[1]. The μCP techniques allow the imposition of molecular structures
in specific areas. The chemical properties of the fabricated layers depend on the functional groups of tail molecules. Such
structures can be used as chemical receptors or as interface between the substrate and the biosensor receptors [2].
Architecture of the tail molecule determines the chemical reactivity and hydrophilic or hydrophobic properties. In
addition it modifies the tribological properties [4] and electrical structure parameters, such as contact potential diference
(CPD) [5]. The height of the SAM structure containing carbon chain is highly dependent on the length and type of
binding molecules to the substrate, which enables application of the μCP SAM structures in height metrology. The
results of these studies will be presented in the work.
Silicon nanowires (SiNWs) have undergone intensive research for their application in novel integrated systems such as
field effect transistor (FET) biosensors and mass sensing resonators profiting from large surface-to-volume ratios (nano
dimensions). Such devices have been shown to have the potential for outstanding performances in terms of high
sensitivity, selectivity through surface modification and unprecedented structural characteristics. This paper presents the
results of mechanical characterization done for various types of suspended SiNWs arranged in a 3D array. The
characterization has been performed using techniques based on atomic force microscopy (AFM). This investigation is a
necessary prerequisite for the reliable and robust design of any biosensing system. This paper also describes the applied
investigation methodology and reports measurement results aggregated during series of AFM-based tests.
In this article authors present a method for determining optimal photoresist exposure parameters in a
photolithography process by an analysis of a topographic profile of exposed images in a photoresist layer. As a
measurement tool an Atomic Force Microscopy (AFM) integrated with a system for maskless lithography was
used. The measurement system with the piezoresistive cantilever and experimental procedure was described.
Initial experiments result of determining the optimal exposure energy and minimizing the stitching error method
were presented.
Application of a new thermal nano-probe based on the changes of electrical resistivity of a nanometer-sized filament with temperature has been presented for the thermal imaging of microwave power active devices. The filament is integrated into an atomic force scanning probe piezoresistive type cantilever. The novel thermal probe has a spatial resolution better than 80 nm and a thermal resolution of the order of 10-3 K. The measurements have been successfully performed on a 30 fingers GaAs-MESFET with a maximum power dissipation of 2.5 W. The microwave transistor has been implemented in a circuit in such a way to prevent the undesired microwave oscillations. In this case the power dissipation is equal to the dc power input. The near-field measurements have been compared with three-dimensional finite element simulations. A good agreement between simulations and measurements is achieved.
First piezoresistive AFM sensor developed by Quate was based on SOI technology. Alternative technology for fabrication of microtips integrated with silicon cantilever beam, used as a microprobe in atomic force microscopy, is described in this paper. It is based on a bulk micromachining to define the cantilever thickness, surface micromachining to develop sharp tip and standard IC planar processing. Specific sequence of plasma treated photoresist and hard masking steps followed by wet isotropic, wet anisotropic and dry etching is utilized to obtain very sharp silicon tips. First, HF/HNO3 based polishing etchant is used to create mesa islands at the end of the formed cantilever. Next, a planar IC processing sequence is realized to fabricate piezoresistive Wheatstone bridge which will serve as a force sensing element. Thickness of the beam is precisely controlled by electrochemical etch-stop technique in. Then, sharp tip is formed by both RIE and/or wet etching, using under-cutting method. Finally, deep anisotropic silicon etching combined with SF6/Ar plasma etching is used to create cantilever silicon beam.
Atomic Force Microscope (AFM) is a very versatile instrument enabling precise surface investigations. The sensitivity of the AFM depends on the parameters of the detector system, which is used to observe the beam motions. In our experiments we have used a cantilever with integrated Wheatstone piezoresistive bridge as a deflection sensor. In this case of nonhomogeneous surfaces not only topography measurements but also investigations of other surface properties in nanometer scale are very important. In this paper we will describe the Lateral Force Microscope utilizing the Wheatstone bridge piezoresistive cantilever. During topography measurements of the nonhomogeneous smooth samples in contact mode the lateral/friction forces change depending on the on the substrate material differences. Thus friction forces imaging enables an investigation of the surface material structure. Measurement setup of the lateral force microscope with Wheatstone bridge piezoresistive cantilever will be presented. Noise considerations of the described lateral forces measurements method with Wheatstone bridge cantilever will be discussed. Measures for improving of the friction force observations will be proposed. We will show results of the topography and friction force measurements on chromium/quartz mask structure.
Atomic Force Microscopy (AFM) is a very sensitive technique to determine the surface topography. Recent developments enable investigations of other microtribological sample properties like elasticity, friction coefficients of the material, which is present on the observed surface. Although, measurements of small cantilever displacements are required in all AFM techniques. In our experiments we have used a cantilever with integrated Wheatstone piezoresistive bridge as a deflection sensor. This cantilever displacement detection system enables the investigations in UHV and low temperature conditions. In this paper we will analyze the sensitivity of the force observations with the piezoresistive Wheatstone bridge cantilever. We will examine how the detector response depends on the beam geometry. Noise considerations of the beam motion measurements method will be discussed. We will present the noise properties of the Wheatstone bridge piezoresistive detector and cantilever system. Measures for improving of the force measurements sensitivity will be proposed.
The atomic force microscope (AFM) is a very sensitive instrument to examine the topography of surfaces and their properties. The sensitivity of the AFM depends on the choice of the detector system, which is used to observe the cantilever deflection. A cantilever with integrated Wheatstone piezoresistive bridge as a deflection sensor was used in experiments. We describe noise properties of the piezoresistive Wheatstone bridge cantilever and show examples of topography measurements in contact and noncontact mode.
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