A flexible thin film impedance sensor has been developed. Device manufacturing process and preparation of test wafers are described. Sensors with ring shaped Au electrodes have been fabricated on a polyimide substrate using Si wafer as a temporary substrate. The sensors have been characterized by means of Agilent 4294A analyzer and tested in measurements of impedance of human skin, Si wafers and other materials. Results of indirect measurements of samples covered with dielectric layer (SU-8, glass) confirm advantages of the sensors.
In this paper we describe the method for monitoring the progress of electrochemical deposition process. The procedure allows to control the deposition of metals as well as conductive polymers on metallic seed layer. The method is particularly useful to very thin layers (1-10 nm) of deposited medium which mechanical or optical methods are troublesome for. In this method deposit is grown on the target and on the test silicon micro-cantilever with a metal pad. Galvanic deposition on the cantilever causes the change of its mass and consequently the change of its resonance frequency. Changes of the frequency is measured with laser vibro-meter then the layer thicknesses can be estimated basing on the cantilever calibration curve. Applying this method for controlling of gold deposition on platinum seed layer, for improving the properties of the biochemical sensors, is described in this paper.
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.
KEYWORDS: Atomic force microscopy, Dielectrics, Silicon, Manufacturing, Silica, Finite element methods, Etching, Sensors, Optics manufacturing, Deep reactive ion etching
In this paper authors present design, technology and application of soft silicon dioxide AFM cantilevers. Novel technology allows for manufacturing ultra-soft cantilevers equipped with silicon tip. Mechanical properties of developed probes were tested and finally applied in AFM measurements of fragile samples.
Andrzej Sierakowski, Piotr Prokaryn, Rafał Dobrowolski, Anna Malinowska, Dariusz Szmigiel, Piotr Grabiec, Damian Trojanowski, Dagmara Jakimowicz, Jolanta Zakrzewska-Czerwinska
In this paper we present a new method of polymer microfluidic bioreactor fabrication by means of a gray scale lithography technique. As a result of the gray scale lithography process the 3D model of the bioreactor is defined in photoresist. The obtained model serves as a sacrificial layer for the subsequent transfer of the 3D shape into the polymer material. The proposed method allows simultaneous definition of both the overall bioreactor geometry and the multi steps cell traps in a single photolithography step. Such microfluidic structure can be used for sorting cells based on their size. The developed solution significantly simplifies the production technology and reduces its costs in comparison to standard photolithography techniques.
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.
This paper describes the idea of the energy harvester which converts thermal gradient present in environment into
electricity. Two kinds of such devices are proposed and their prototypes are shown and discussed. The main parts of
harvesters are bimetallic spring, piezoelectric transducer or electrostatic transducer with electret. The applied piezomembrane
was commercial available product but electrets was made by authors. In the paper a fabrication procedure of
electrets formed by the corona discharge process is described. Devices were compared in terms of generated power,
charging current, and the voltage across a storage capacitor.
The paper presents the design, technology and parameters of a new .silicon detector for detection of electrons (below named as beta detector) developed at the Institute of Electron Technology (ITE). The detector will be used for research on transactinide elements at the GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (GSI). The detector consists of a monolithic 32-element array with an active area diameter of 90 mm and a thickness of 0.9 mm. The starting material is a high-resistivity ν silicon wafer (5 kΩcm resistivity). 32 planar p+-ν junctions are formed by boron diffusion on the top side of the wafer. On the bottom side, an n+ region, which forms a common cathode, is formed on the entire surface by phosphorus diffusion.
The array is mounted on a special epoxy-glass laminate substrate, copper-clad on both sides. Two model detectors have been fabricated and studied. Very good electrical parameters have been achieved. For the first array, with supply voltage VR = 20 V, the minimum dark current was 8 nA, the maximum dark current 97.1 nA, and the average dark current 25.1 nA. For the second array, it was 11.5 nA, 378.8 nA and 40.0 nA respectively.
Maciej Węgrzecki, Dariusz Wolski, Jan Bar, Tadeusz Budzyński, Arkadiusz Chłopik, Piotr Grabiec, Helena Kłos, Andrzej Panas, Tadeusz Piotrowski, Wojciech Słysz, Maciej Stolarski, Dariusz Szmigiel, Iwona Węgrzecka, Michał Zaborowski
The paper presents the design, technology and parameters of a new, silicon 64-element linear photodiode array developed at the Institute of Electron Technology (ITE) for the detection of scintillations emitted by CsI scintillators (λ≈550 nm). The arrays are used in a device for examining the content of containers at border crossings under development at the National Centre for Nuclear Research. Two arrays connected with a scintillator block (128 CsI scintillators) form a 128-channel detection module. The array consists of 64 epiplanar photodiode structures (5.1 × 7.2 mm) and a 5.3 mm module. p+-ν-n+ photodiode structures are optimised for the detection of radiation of λ≈ 550 nm wavelength with no voltage applied (photovoltaic mode). The structures are mounted on an epoxy-glass laminate substrate, copper-clad on both sides, on which connections with a common anode and separate cathode leads are located. The photosensitive surface of photodiodes is covered with a special silicone gel, which protects photodiodes against the mechanical impact of scintillators
The subject of this paper is to describe the novel method of substrates bonding applied in MEMS technology.
This method gives a possibility of carrying out bonding processes in standard devices for wafer bonding. It
can be applied to chemical, high voltage or high temperature sensitive surfaces. It can be used for bonding
substrates with deep etching area with sharp edges and covered with films characterized by low adhesion to the
classical materials exploited for photolithography. The main idea of the method is based on two various polymer
materials usage. The first material enables to define accurate borders of bonding area, whereas the other
guarantees suitable parameters of bonding: firstly the exact adhesion and a stable join and secondly, desirable
electrical or thermal parameters.
A study of pH sensitivity of miniature ISFET-type sensors with silicon nitride sensitive layer has been presented. 4 μm
wide SOI FET microsensor process and 100 nm FinFET nanosensor process have been completed with oxygen plasma
treatment. ID(VDS) and gds characteristics of the devices as well as source follower circuit output signal measurements
have been reported. An influence of 1% HF etching of the gate dielectric on pH sensitivity of the sensors has been
described and an explanation of phenomenon of the sensitivity adjustment has been proposed.
Maciej Węgrzecki, Jan Bar, Tadeusz Budzyński, Michal Cież, Piotr Grabiec, Roman Kozłowski, Jan Kulawik, Andrzej Panas, Jerzy Sarnecki, Wojciech Słysz, Dariusz Szmigiel, Iwona Węgrzecka, Marek Wielunski, Krzysztof Witek, Alexander Yakushev, Michał Zaborowski
The paper discusses the design of charged-particle detectors commissioned and developed at the Institute of Electron
Technology (ITE) in collaboration with foreign partners, used in international research on transactinide elements and to
build personal radiation protection devices in Germany. Properties of these detectors and the results obtained using the
devices are also presented. The design of the following epiplanar detector structures is discussed:
♦ 64-element chromatographic arrays for the COMPACT (Cryo On-line Multidetector for Physics And Chemistry of
Transactinides) detection system used at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt (GSI)
for research on Hassium, Copernicium and Flerovium, as well as elements 119 and 120,
♦ 2-element flow detectors for the COLD (Cryo On-Line Detector) system used for research on Copernicium and
Flerovium at the Joint Institute for Nuclear Research, Dubna,
♦ detectors for a radon exposimeter and sensors for a neutron dosimeter developed at the Institut für Strahlenschutz,
Helmholtz Zentrum München.
The design of planar detectors – single-sided and double-sided strip detectors for the Focal Plane Detector Box used at
GSI for research on Flerovium and elements 119 and 120 is also discussed.
Iwona Wegrzecka, Andrzej Panas, Jan Bar, Tadeusz Budzyński, Piotr Grabiec, Roman Kozłowski, Jerzy Sarnecki, Wojciech Słysz, Dariusz Szmigiel, Maciej Węgrzecki, Michał Zaborowski
The paper discusses the technology of silicon charged-particle detectors developed at the Institute of Electron
Technology (ITE). The developed technology enables the fabrication of both planar and epiplanar p+-ν-n+ detector
structures with an active area of up to 50 cm2. The starting material for epiplanar structures are silicon wafers with a
high-resistivity n-type epitaxial layer ( ν layer - ρ < 3 kΩcm) deposited on a highly doped n+-type substrate
(ρ< 0,02Ωcm) developed and fabricated at the Institute of Electronic Materials Technology. Active layer thickness of
the epiplanar detectors (νlayer) may range from 10 μm to 150 μm. Imported silicon with min. 5 kΩcm resistivity is used
to fabricate planar detectors. Active layer thickness of the planar detectors (ν) layer) may range from 200 μm to 1 mm.
This technology enables the fabrication of both discrete and multi-junction detectors (monolithic detector arrays), such as
single-sided strip detectors (epiplanar and planar) and double-sided strip detectors (planar). Examples of process
diagrams for fabrication of the epiplanar and planar detectors are presented in the paper, and selected technological
processes are discussed.
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.
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.
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.
This paper presents an electronic tongue system with blind source separation (BSS) and wireless sensor network (WSN)
for remote multi-ion sensing applications. Electrochemical sensors, such as ion-sensitive field-effect transistor (ISFET)
and extended-gate field-effect transistor (EGFET), only provide the combined concentrations of all ions in aqueous
solutions. Mixed hydrogen and sodium ions in chemical solutions are observed by means of H+ ISFET and H+ EGFET
sensor array. The BSS extracts the concentration of individual ions using independent component analysis (ICA). The
parameters of ISFET and EGFET sensors serve as a priori knowledge that helps solve the BSS problem. Using wireless
transceivers, the ISFET/EGFET modules are realized as wireless sensor nodes. The integration of WSN technology into
our electronic tongue system with BSS capability makes distant multi-ion measurement viable for environment and
water quality monitoring.
In this paper, we present the design of electronic tongue system for multi-ion sensing applications. The ion-sensitive
field-effect transistor (ISFET) detects the concentration of a particular ion in aqueous solution. However, when the given
chemical solution contains two or more ions, the ISFET sensor can only provide the combined concentration of ions. In
this end, our electronic tongue included a blind source separation (BSS) method of independent component analysis (ICA) to process the ISFET signals and to extract the concentrations of individual ions in the solution. The results of ISFET modeling based on fixed interference method (FIM) serve as a priori knowledge to help solve this blind source problem. Experiments are conducted on this electronic tongue system using aqueous solution containing hydrogen and sodium ions flowing through the array of dual H+ ISFET devices. The results of ICA processing successfully determined the concentration of hydrogen ions amidst the presence of sodium ions. This capability of ion separation allows us to move towards the development of smart electronic tongue systems for environmental and water quality monitoring.
Single-photon detectors (SPDs) are the foundation of all quantum communications (QC) protocols.
Among different classes of SPDs currently studied, NbN superconducting SPDs (SSPDs) are established as the
best devices for ultrafast counting of single photons in the infrared (IR) wavelength range. The SSPDs are
nanostructured, 100 μm2
in total area, superconducting meanders, patterned by electron lithography in ultra-thin
NbN films. Their operation has been explained within a phenomenological hot-electron photoresponse model.
We present the design and performance of a novel, two-channel SPD receiver, based on two fiber-coupled NbN
SSPDs. The receivers have been developed for fiber-based QC systems, operational at 1.3 μm and 1.55 μm
telecommunication wavelengths. They operate in the temperature range from 4.2 K to 2 K, in which the NbN
SSPDs exhibit their best performance. The receiver unit has been designed as a cryostat insert, placed inside a
standard liquid-heliumstorage dewar. The input of the receiver consists of a pair of single-mode optical fibers,
equipped with the standard FC connectors and kept at room temperature. Coupling between the SSPD and the
fiber is achieved using a specially designed, precise micromechanical holder that places the fiber directly on top
of the SSPD nanostructure. Our receivers achieve the quantum efficiency of up to 7% for near-IR photons, with
the coupling efficiency of about 30%. The response time was measured to be < 1.5 ns and it was limited by our
read-out electronics. The jitter of fiber-coupled SSPDs is < 35 ps and their dark-count rate is below 1s-1. The
presented performance parameters show that our single-photon receivers are fully applicable for quantum correlation-type QC systems, including practical quantum cryptography.
We have fabricated fiber-coupled superconducting single-photon detectors (SSPDs), designed for quantum-correlationtype
experiments. The SSPDs are nanostructured (~100-nm wide and 4-nm thick) NbN superconducting meandering
stripes, operated in the 2 to 4.2 K temperature range, and known for ultrafast and efficient detection of visible to nearinfrared
photons with almost negligible dark counts. Our latest devices are pigtailed structures with coupling between
the SSPD structure and a single-mode optical fiber achieved using a micromechanical photoresist ring placed directly
over the meander. The above arrangement withstands repetitive thermal cycling between liquid helium and room
temperature, and we can reach the coupling efficiency of up to ~33%. The system quantum efficiency, measured as the
ratio of the photons counted by SSPD to the total number of photons coupled into the fiber, in our early devices was
found to be around 0.3 % and 1% for 1.55 &mgr;m and 0.9 &mgr;m photon wavelengths, respectively. The photon counting rate
exceeded 250 MHz. The receiver with two SSPDs, each individually biased, was placed inside a transport, 60-liter
liquid helium Dewar, assuring uninterrupted operation for over 2 months. Since the receiver's optical and electrical
connections are at room temperature, the set-up is suitable for any applications, where single-photon counting capability
and fast count rates are desired. In our case, it was implemented for photon correlation experiments. The receiver
response time, measured as a second-order photon cross-correlation function, was found to be below 400 ps, with
timing jitter of less than 40 ps.
This paper presents an analog processor design for ion sensitive field effect transistor (ISFET)-based flow through
system and its application in smart living space. The dynamic flow-cell measurement explores more information
compared to stationary measurement and is useful in environmental monitoring and electronic tongue systems. The
multi-channel floating source readout circuitry has been developed for flow-through analysis of ion sensitive field effect
transistor based array. The flow injection analysis system with two different ISFET structures has been investigated by
using performance parameters such as sensitivity, uniformity, response time of pH sensing. In addition, a self-tuning
multi-sensor water quality monitoring system based on adaptive-network-based fuzzy interference system (ANFIS)
learning method is developed. The results can be directly used in drinking water and swimming pool monitoring for
improving living space and quality.
On the foundation of joint experience acquired by several research centres there was defined the roadmap to the desired single technological platform for fabrication of a specific class of photonic integrated circuits, which are controlled by mechanical means. In the paper the challenges of fabrication of such photonic circuits are discussed. The main arguments in favour of the Silicon-on-Insulator materials system as the basis for the platform are presented. Options for the mechanics-to-optics arrangement, materials and processes are described and illustrated with the current achievements from the authors' labs. In the roadmap the preference is given to the vertical arrangement in which, the mechanical part is stacked above the waveguiding layer. A flexible trimming routine is designed to complement the process flow if the technologies developed cannot provide the required reproducibility.
Most approaches to perform switching and tuning in photonic integrated circuits (PICs) are based on modulation of effective refractive index of a waveguide or a resonant structure and use a variety of means by which the desired perturbation of index is to be achieved. Limitations to these methods, which obstacle achievement of the desired results, are discussed. It is shown that the promising alternative, at least for applications, for which speed is not a critical issue, can be to control light by means of nano/micromechanic actuation. The general idea is presented and the applicability of mechanical actuation to very-large-scale integration (VLSI) photonics is assessed. Particular concepts of switching and tuning are described.
The paper presents an idea of a reconfigurable optical add-drop multiplexer (ROADM) based on micro/nanomechanically switched micro-ring resonators. Main issues related to the design and fabrication of mechanically controlled ROADM are discussed.
We present the design and performance of a novel, two-channel single-photon receiver, based on two fiber-coupled NbN superconducting single-photon detectors (SSPDs). The SSPDs are nanostructured superconducting meanders covering an area of 100 μm2 and are known for ultrafast and efficient counting of single, visible-to-infrared photons. Their operation has been explained within a phenomenological hot-electron photoresponse model. Our receiver is intended for fiber-based quantum cryptography and communication systems, operational at near-infrared (NIR) telecommunication wavelengths, λ = 1.3 μm and λ = 1.55 μm. Coupling between the NbN detector and a single-mode optical fiber was achieved using a specially designed, micromechanical photoresist ring, positioned directly over the SSPD active area. The positioning accuracy of the ring was below 1 μm. The receiver with SSPDs was placed (immersed) in a standard liquid-helium transport Dewar and kept without interruption for over two months at 4.2 K. At the same time, the optical fiber inputs and electrical outputs were kept at room temperature. Our best system reached a system quantum efficiency of up to 0.3 % in the NIR radiation range, with the detector coupling efficiency of about 30 %. The response time was measured to be about 250 ps and was limited by our read-out electronics. The measured jitter was close to 35 ps. The presented performance parameters show that our NIR single photon detectors are suitable for practical quantum cryptography and for applications in quantum-correlation experiments.
Iwona Wegrzecka, Maciej Wegrzecki, Jan Bar, Maria Grynglas, Andrzej Uszynski, Remigiusz Grodecki, Piotr Grabiec, Sylwester Krzeminski, Tadeusz Budzynski
Silicon avalanche photodiodes (APDs) -- due to the effect of avalanche multiplication of carriers in their structure -- are most sensitive and fastest detectors of visible and near infrared radiation. Also the value of noise equivalent power NEP of these detectors is the smallest. In the paper, the design, technology and properties of the silicon avalanche photodiodes with a n+ - p - π - p+ epiplanar structure developed at the Institute of Electron Technology (ITE) are presented. The diameters of photosensitive area range from 0.3 mm to 5 mm. The ITE photodiodes are optimized for the detection of the 800 nm ÷ 850 nm radiation, but the detailed research on spectral dependencies of the gain and noise parameters has revealed that the spectral operating range of the ITE photodiodes is considerable wider and achieves 550 ÷ 1000 nm. These photodiodes can be used in detection of very weak and very fast optical signals. Presently in the world, the studies are carried out on applying the avalanche photodiodes in detection of X radiation and in the scintillation detection of nuclear radiation.
Maciej Wegrzecki, Iwona Wegrzecka, Jan Bar, Wojciech Slysz, Maria Grynglas, Andrzej Uszynski, Remigiusz Grodecki, Piotr Grabiec, Sylwester Krzeminski, Tadeusz Budzynski, Andrzej Panas
The paper presents the results of the work on high speed epiplanar photodiodes of a small active area used in laser and fiber-optic techniques and epiplanar diodes of a large active area destined for nuclear radiation detection. Also planar diodes with a large active area and thick active region assigned for detection of optical, nuclear and X radiation are discussed.
The p+-v-n+ detectors applied in selective detection of nuclear radiation have been examined by the Light Beam Induced Current (LBIC) method. The LBIC method enables the comprehensive analysis of photocurrent generated by focused light beam in the microregion in active area of detector. Results of LBIC examinations allowed comparing two kinds of structures. One kind of the structures is those that fulfill requirements regarding parameters of diodes applied in the detection of nuclear radiation. For other kind, dark current exceeds the permissible value. The capacity-voltage characteristics have been presented too.
The construction of the microsensor with the ultrasonic wave Lambda-type as well as the conditions of the wave propagation were presented. The possibilities of the fabrication of multi-layer membranes on the silicon base using the microelectronics technologies were presented and discussed. The analysis of the usefulness of the processes mentioned to the production of the thin membrane sensors was carried out taking the intrinsic stresses into consideration. The summary of the experimental results was done and the most useful parameters of the membrane ultrasonic sensors were pointed out.
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.
The suitability of pattern transfer through multi-component chemically amplified resists (CARs) has been studied. We report on direct-write electron-beam lithographic and reactive ion etching (RIE) experiments with single-layer CARs used for the fabrication of silicon structures with sizes from micro- down to submicrometer scale and high aspect ratio. The 30 keV e-beam response of new types of CARs in thicker layers and the optimization possibilities of the exposure and etching conditions were investigated as well. We measured the basic characteristics of used resists and also the influence of proximity effects. The study includes the effects of resist process variations on the global 3D resist-relief structure. The resolved resist- relief structures at optimized process conditions have shown high aspect ratios with nearly vertical sidewalls. The paper will discuss the deep pattern transfer results into the underlying SiO2 and/or directly into Si-substrate by using RIE. The results show an etch that has excellent vertical sidewalls free of passivation, and is anisotropic.
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.
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.
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.
A new rapid thermal diffusion (proximity RTD) method, utilizing spin-on dopant (SOD) layers, was reported recently. This technique is based on an evaporation-gas phase diffusion- adsorption-surface reaction-diffusion in Si scheme. In this paper we use FTIR spectroscopy to investigate a relationship between the SOD layer structure/composition and its doping efficiency, as determined by sheet resistance (RS) measurements, for a phosphorus diffusion case.
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