Tip Of Microprobe Research Articles

Achieving nano-patterned features by micro-EDM process using vertically aligned ZnO nanorods grown on microprobe tip: A scaling approach

Fabricating the nanopatterned features through a cost-effective nanomachining technique is one of the great challenges in NEMS industries. The micro-electrical-discharge machining process is one of the promising machining technologies which is capable to write the micro-scale features on any electrically conductive materials. However, its potential has not been tested yet for replicating the nanoscale features through the scaling approach. Hence, this article addresses a scaling approach for fabricating the nanopatterned features on super finished titanium alloy (Ti-6Al-4 V) using vertically aligned ZnO nanorods grown on the apex of the microtip. For achieving this, first of all, cylindrical micro-tools of diameter (ø) 90–95 μm (tungsten) were fabricated through a micro-electrochemical turning process under KOH (2.5 M) electrolyte medium. On the apex of the micro tools, the ZnO nanorods were grown by the low-temperature hydrothermal process by dipping the apex of the tip in seed and growth solution followed by essential heat treatment at 90 °C. It was found that the grown nanorods were well defined in shape and size and further utilized as nanotools during short-duration discharge (5 ms) μ-EDM experiments. It was expected that by downsizing the tooltip, the discharge energy per unit pulse may be reduced due to the localization effect. Moreover, it is well-known fact that the discharge happens only in the nearest established gap in the μ-EDM process. The experimental results of this study confirmed the same. The FESEM micrographs were utilized for the morphological characterization of formed nanopatterned cavities, microtools, and nanorods while the chemical characterization of the same is carried out by EDX spectroscopy. Additionally, the stability of the machining process was tested first for multiple discharge energy pulses then after a short duration discharge energy pulse has been characterized by voltage-current (V-I) waveforms during nanocavity fabrication. Finally, the supporting results of this experimental investigation show the feasibility of the approach towards nano-EDM with extensive potentials/applications in micro/nanofabrication devices.

A method for cleaning flat punch diamond microprobe tips

Microprobe tips are commonly used to perform in-situ micromechanical tests within an electron microscope. In service, such tips have a tendency to accumulate along their surface a layer of deposited material. Tip cleanliness is crucial in order to obtain reliable and reproducible data; however, cleaning of such tips can be arduous, due to their fragility. The literature on appropriate tip cleaning methods is relatively sparse; we aim in this study to fill this gap by presenting an effective way to clean flat punch diamond microprobe tips within an electron microscope, based on mechanical scraping. Initial attempts to remove deposits from a contaminated diamond tip using two micro-brush samples, one containing silica needles and the other containing cementite lamellae, were unsuccessful, due to the adherence of the deposit to the surface of the tip and its apparently high hardness. The successful cleaning method consists of milling a silicon ridge by means of a focused ion beam, and then using this ridge to effectively scrape the deposits off the tip surface in a controlled and complete manner. This method avoids potential damage to the microprobe and can be implemented easily to clean flat punch tips rapidly within a scanning electron microscope.

An innovative approach to deposit ultrathin ZnO nanoflakes (2D) through hydrothermal assisted electrochemical discharge deposition and growth method

The functionality and structural properties of nanomaterials significantly depend on the synthesis method. This work explored a novel fast route to deposit ultrathin zinc oxide (ZnO) nanoflakes on a conical microprobe tip by combining the effect of hydrothermal, electrochemical, and electro-discharge deposition process. The experimental results indicate the formation of ZnO nanoflakes and show the variance of thickness (min≤10 nm)/morphologies at different electrochemical parameters. The impact of varying voltage potential and concentration was analyzed and discussed. A hydrothermally prepared precursor solution of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and hexamine ((CH2)6N4) was used as a growth solution. The crystallinity and phase purity were analyzed by XRD. The functional groups, molecular fingerprints, were recognized by FTIR. Further, the bandgap energy (3.262eV) was estimated by Mott-Davis relation in UV–Vis spectroscopy via Tauc plot.

A NOVEL METHOD FOR STUDYING THE CORROSION RESISTANCE AND MICROSTRUCTURE OF ENAMEL COATING MODIFIED ON HIGH-STRENGTH STEEL IN 3.5 wt.% NaCl SOLUTION

A new method was introduced to research the corrosion resistance of enamel coatings which were sintered at different temperatures in this paper. 1 – 4 Scanning electrochemical microscopy (SECM) conjunction with capacitance-potential test and Mott–Schottky analysis technique were used to study the coating failure process and semiconductor conduction behavior of enamel coating in 3.5[Formula: see text]wt.% NaCl solution. The high strength steel (SAPH440) was selected as the metal substrate. The coatings which were sintered at different temperatures on the high strength steel were analyzed and their corrosion behaviors and microstructures were also measured by potentiodynamic polarization curves, Mott–Schottky analysis technique and scanning electrochemical microscopy. 5 – 10 In this paper, five kinds of enamel coatings were prepared on high strength steel. The SECM results show that the Faraday current of the microprobe tip gradually decreases with the soaking time increasing, which indicates that the coatings become failure slowly with the invasion of water and aggressive ions. At the same time, the tip current was homogeneous during the immersion process, which reflected that the surface of the sample remained stable, no obvious bulges appeared. Capacitance–potential test and Mott–Schottky analysis 7 , 8 show that the external ions and water molecules gradually penetrate into the coating; coating showed characteristics of [Formula: see text]-type semiconductor as time increases, the capacitance increases gradually, the space charge layer thickness decreases, slope of Mott–Schottky curve decreased gradually which indicates that the failure of coating in the process of soaking slowly with the charge carrier density increases.

Single‐mask fabrication of micro‐probe electrode array with various tip heights and sharpness using isotropic and anisotropic etching

In this work, a silicon-based micro-probe array was fabricated using multi-step deep reactive ion etching (DRIE) and reactive ion etching (RIE) processes. The micro-probe structure was implemented using a micromachining technique through a combination of two anisotropic DRIE and two isotropic RIE processes with a single etch mask. The cone-shaped tip height and tapered tip-end angle were experimentally varied with respect to the first DRIE depth. As the first DRIE depth was decreased, the micro-probe tip height increased and the sharpness consequently improved. The conductive layer was exposed only at the tip ends of the micro-probe to form a conical ultra-micro electrode, and it was characterised via cyclic voltammetry measurements.

High-speed microprobe for roughness measurements in high-aspect-ratio microstructures

Cantilever-type silicon microprobes with an integrated tip and a piezoresistive signal read out have successfully proven to bridge the gap between scanning force microscopy and stylus profilometry. Roughness measurements in high-aspect-ratio microstructures (HARMS) with depths down to 5 mm and widths down to 50 µm have been demonstrated. To improve the scanning speed up to 15 mm s−1, the wear of the tip has to be reduced. The atomic layer deposition (ALD) technique with alumina (Al2O3) has been tested for this purpose. Repeated wear measurements with coated and uncoated microprobe cantilevers have been carried out on a roughness standard at a speed of 15 mm s−1. The tip shape and the wear have been measured using a new probing tip reference standard containing rectangular silicon grooves with widths from 0.3 µm to 3 µm. The penetration depth of the microprobe allows one to measure the wear of the tip as well as the tip width and the opening angle of the tip. The roughness parameters obtained on the roughness standard during wear experiments agree well with the reference values measured with a calibrated stylus instrument, nevertheless a small amount of wear still is observable. Further research is necessary in order to obtain wear resistant microprobe tips for non-destructive inspection of microstructures in industry and microform measurements, for example in injection nozzles.

Using OxyLite TM fiber-optic microprobes to verify the reliability of detecting the oxygenation in rats C6 glioma by blood oxygenation level dependent functional MRI with non-hemodynamic response function analysis

Objective Using MRI compatible OxyLiteTM fiber-optic microprobes to verify the reliability of detecting the oxygenation changes in rats C6 glioma by BOLD fMRI with non-hemodynamic response function (non-HRF) post-processing algorithm. Methods A total of 20 male SD rats were used to establish the subcutaneous C6 glioma model. GRE-EPI BOLD fMRI scans were performed in the tumor-bearing rats with Carbogen inhalation after anatomic scans using 1.5 T MR imaging system with Micro-47 microscopic coil. Fiber-optic microprobes were implanted in tumor to acquire the dynamic pO2 indications during BOLD fMRI scan. Oxy-localization map and oxy-amplitude map were generated from BOLD functional image data by non-HRF post-processing algorithm analysis. A ROI about 1.5 mm on a side centered to the tip of microprobe was defined on the MRI morphological image, and then was copied onto the oxy-localization map and oxy-amplitude map to extract the values of significant re-oxygenation (T), percent BOLD signal change (ΔPSC). The mean difference of pO2(ΔpO2) measured by fiber-optic microprobes before (pO2-Air) and after (pO2-Car) Carbogen inhalation in the ROI areas was calculated. Correlation analysis was madebetween cov (T value, Δ pO2) and cov (ΔPSC value, Δ pO2). The difference between pO2-Air and pO2-Car were tested by Mann Whitney U test. Results pO2 was successfully measured and recorded from 23 points in tumor using fiber-optic microprobe during the BOLD fMRI scan. The analysis results both of physiological and functional imaging parameters were as follows: pO2-Air=2.285 (19.056) mmHg, pO2-Car=14.701 (48.390) mmHg, ΔpO2=8.107 (33.557) mmHg, ΔPSC=0.402 (2.192) %, T=2.025 (8.293) . (1) 10 points were identified clearly in parenchyma area of tumor. The mean value of pO2 during air inhalation [19.462(21.511)mmHg] significantly increased after Carbogen inhalation [59.904(56.710)mmHg] (U=14.000, P=0.007) . (2) 5 points were identified in tumor necrosis area. The mean value of pO2 during air inhalation [0.149 (0.479) mmHg] showed no significant change comparing with Carbogen inhalation[0.273 (8.050) mmHg] (U=9.000, P=0.465) . (3) 8 points were identified in the boundary of tumor parenchyma and necrosis areas. Among which, 5 showed the similar pO2 change to that located in tumor necrosis area, 2 showed the similar to the tumor parenchyma. However, the pO2 showed continuously decrease after Carbogen inhalation in the last 1 point. The ΔpO2 measured from the total of 23 points correlated positively to ΔPSC and T value extracted from the corresponding ROI (r=0.660, 0.576, P<0.01). The ΔpO2 measured from 10 points in tumor parenchyma correlated positively to ΔPSC(r=0.717, P=0.020). Conclusion Oxy-localization map and oxy-amplitude map generated from BOLD fMRI combined with non-HRF post-processing algorithm could show reliably not only the location but also the extent where the re-oxygenation occurred within tumor. Key words: Glioma; Magnetic resonance imaging; Animal experimentation

A New Automatic Testing System Based on Image Processing and Microprobes for IC-Testing

In order to develop integrated circuit (IC) testing, a new system was suggested using a microprobe array, a four-wire tester, machine vision, and motion control technology. The microprobe array can be automatically aligned with the IC die by an image-processing program in the system. It was found that the operating efficiency of the algorithm was improved by six times by extracting the rectangular edge contour. Several image-processing methods were combined and optimized to calculate the deflection angle, and the linear fitting method was improved. Inaccurate fitting was eliminated by the modified fitting method, and the alignment error was significantly reduced. Although IC electrodes were precisely aligned with the microprobe tips, the compressive displacement of the microprobe also has a greater influence on the electrical testing. The testing resistance was not a stable value until the compressive displacement exceeded 100 $\mu \text{m}$ . Finally, the effectiveness of the microprobe automatic testing approach was confirmed. The open circuits of the ICs can be detected, and the resistance of the circuits, which are not open circuits, can be automatically measured and evaluated.

A novel testing system based on microprobe and machine vision for IC testing

To achieve automatic test of the microprobe and the IC circuit, the automated test is integrated based on machine vision. It was found that fitting time of the symmetry axis in the image processing was much less than that of the rectangular fitting, and fitting efficiency was increased by one order of magnitude. On this basis, the relationship between the displacement of the rectangular under machine vision and the number of motor revolutions was obtained. The light intensity was optimized in the testing, thus the stability of automated testing was improved. Finally, the positioning and test of the micro-probe tip and the IC electrode were carried out by the motion control systems, in which the movement accuracy of x, y and the rotation direction reached to 7.6μm, 7μm and 0.066 degrees, respectively. The accuracy of the IC circuit automatic alignment test was verified by the data tested with a multimeter, and the electrical parameters and turn-off of the IC can be automatically measured and evaluated.

Force-displacement measurements of earlywood bordered pits using a mesomechanical tester.

The elastic properties of pit membranes are reported to have important implications in understanding air-seeding phenomena in gymnosperms, and pit aspiration plays a large role in wood technological applications such as wood drying and preservative treatment. Here we present force-displacement measurements for pit membranes of circular bordered pits, collected on a mesomechanical testing system. The system consists of a quartz microprobe attached to a microforce sensor that is positioned and advanced with a micromanipulator mounted on an inverted microscope. Membrane displacement is measured from digital image analysis. Unaspirated pits from earlywood of never-dried wood of Larix and Pinus and aspirated pits from earlywood of dried wood of Larix were tested to generate force-displacement curves up to the point of membrane failure. Two failure modes were observed: rupture or tearing of the pit membrane by the microprobe tip, and the stretching of the pit membrane until the torus was forced out of the pit chamber through the pit aperture without rupture, a condition we refer to as torus prolapse.

Wear-Insensitive Sidewall Microprobe With Long-Term Stable Performance for Scanning Probe Microscopy Lithography

In this paper, a wear-insensitive sidewall microprobe with long-term stable performance is proposed. The proposed microprobe helps to reduce probe-tip wear and improve patterning stability in scanning probe microscopy lithography. The microprobe tip with a uniform cuboid-shape consists of a microscale mechanical contact and two nanoscale electrical contacts formed on the sidewall of the mechanical contact. The microscale mechanical contact reduces tip wear by dispersing the force applied to the tip, while the nanoscale electrical contact enables the sketching of nanoscale features. The uniform shape of the probe tip enables the probe to maintain its stable performance, even when it is mechanically worn. A prototype of the proposed microprobe with an 80-μm long mechanical line contact and a 30-nm long electrical line contact is fabricated using microelectromechanical systems techniques. The patterning stability of the fabricated microprobe in local anodic oxidation (LAO) lithography is investigated in terms of the change in the dimensions of the drawn lines and the shape of the probe tip before and after a 2-m scan. The results of the LAO lithography show that the fabricated microprobe could maintain a stable patterning performance after 2-m scan, which is an improvement of several thousand times over a conventional probe.

Mobile acoustic streaming based trapping and 3-dimensional transfer of a single nanowire

Acoustic manipulations of single nanoscale entities were not realized before this work owing to the acoustic streaming which usually flushes a trapped entity away. Here, we demonstrate a strategy that uses mobile acoustic streaming to effectively trap and align a single nanowire within water film on substrate surface, and stably transfers a trapped nanowire through an arbitrary 3-dimensional path in the water film. The streaming is generated by a vibrating micro-probe with uniform diameter. In our experiments, a trapped nanowire is constantly on the side of the micro-probe tip, perpendicular to the micro-probe vibration, and symmetric about the micro-probe approximately.

Development of a selective electroforming process for micro-sized probe tips used in LCD inspection machines

A probe station is an inspection apparatus that automatically transfers liquid crystal display (LCD) panels and separates defective LCD products using a micro-probe unit. However, as the number of pixels increases in LCD screens, the size of the inspecting probe unit has to decrease. There are many limits to the conventional methodology when it comes to fabricating micro-sized probes. In this study, a selective electroforming process was developed and a micro-probe tip was fabricated using this process. Selective electroforming is a high-precision fabricating process where a non-conductive barrier layer is deposited on a conductive wafer and the conductive parts are electroformed using only Ni. Finally, using the selective electroforming process, the micro-sized probe was fabricated with a shape error of less than 0.1%.

유한요소해석을 이용한 수직형 프로브 팁의 설계

마이크로 프로브 팁의 설계는 매우 복잡하고 많은 비용이 든다. 이 논문에서는 새로운 타입의 프로브 팁을 유한요소해석을 이용하여 설계하였다. 유한요소해석을 이용하여 설계를 함으로써 복잡한 설계과정을 단순화 할 수 있다. 우선, 기존 프로브 팁의 실험 결과를 이용하여 유한요소해석기법을 검증하였다. 기존 프로브 팁의 물성은 100 ㎛ 의 압축 길이시 12.5 gf 의 접촉하중이 측정되었다. 본 연구에서는 새로운 타입의 프로브 팁을 제안하였다. 새로 설계된 프로브 팁의 재료는 NiCo 이며 프로브 팁의 물성은 100 ㎛ 의 압축 길이시 1~2 gf 의 접촉하중을 나타내었다.

IMPROVEMENT OF MEASUREMENT ACCURACY OF STRAIN OF THIN FILM BY CCD CAMERA WITH A TEMPLATE MATCHING METHOD USING THE 2ND-ORDER POLYNOMIAL INTERPOLATION

In this study, a system for non-contact in-situ measurement of strain during tensile test of thin films by using CCD camera with marking surface of specimen by black pen was implemented as a sensing device. To improve accuracy of measurement when CCD camera is used, this paper proposed a new method for measuring strain during tensile test of specimen with micrometer size. The size of pixel of CCD camera determines resolution of measurement, but the size of pixel can not satisfy the resolution required in tensile test of thin film because the extension of the specimen is very small during the tensile test. To increase resolution of measurement, the suggested method performs an accurate subpixel matching by applying 2nd order polynomial interpolation method to the conventional template matching. The algorithm was developed to calculate location of subpixel providing the best matching value by performing single dimensional polynomial interpolation from the results of pixel-based matching at a local region of image. The measurement resolution was less than 0.01 times of original pixel size. To verify the reliability of the system, the tensile test for the BeNi thin film was performed, which is widely used as a material in micro-probe tip. Tensile tests were performed and strains were measured using the proposed method and also the capacitance type displacement sensor for comparison. It is demonstrated that the new strain measurement system can effectively describe a behavior of materials after yield during the tensile test of the specimen at microscale with easy setup and better accuracy.

Surface nanostructuring by nano-/femtosecond laser-assisted scanning force microscopy

Surface nanostructuring with lateral resolutions beyond the capabilities of conventional optical lithography techniques was demonstrated in this study. Various nanoscopic surface features, such as grids, craters, and curves, were produced on thin metal and semiconductor films and bulk silicon by using the enhanced electric field underneath a proximity scanning probe tip irradiated with a laser beam. Nanoscale melting and crystallization of amorphous silicon films illustrates the capacity of the present scheme to provide an effective nanolaser source. Numerical simulations yield insight into the spatial distribution of the enhanced field intensity underneath the tip and associated physical phenomena. Calculations of the temperature distribution in the microprobe tip and possible tip expansion show that the main reason for the highly localized nanostructuring achieved with this technique is the enhancement of the electric field in the tip–sample gap. Possible applications of the developed nanostructuring process are anticipated in various nanotechnology fields.

Use of a gaas microprobe tip pumped by circularly polarized light as a source of spin‐polarized tunneling electrons

AbstractWe have studied the feasibility of using GaAs microprobe tips fabricated by anisotropic wet chemical etching followed by sulfur passivation as a source of spin‐polarized tunneling electrons. In our experiments, we studied the magnetic state of a nickel thin film by spin‐polarized STM, using a GaAs microprobe tip illuminated by circularly polarized light. We observed that the tunneling current was different depending on the sense of rotation of the circular polarization (and hence was proportional to the number of spin‐polarized tunneling electrons). We then made measurements of the thin film's hysteresis characteristics by the same technique and by the magnetic Kerr effect. We confirmed by time‐resolved photoluminescence measurements that surface states located at the surface of the GaAs microprobe tip can mediate the tunneling, which shortens the lifetime of electrons within the tip. This indicates that these surface states can affect the spin‐polarized tunneling signal. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(5): 21–28, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1103

Peltier-effect module for highly localized temperature manipulations

A Peltier-effect module suitable for applications that require manipulation of the temperature (cooling or heating) of microsized subjects or at a highly localized spot was developed. The module was constructed from a commercial electronic refrigeration device based on the Peltier effect with an array of microprobes attached to its top surface. The microprobes were fabricated using the LIGA (German acronym for lithographie, galvanoformung, abformung) process—one of the microelectromechanical systems technologies. The 1000-μm-tall microprobes were fabricated on a titanium plate and then bonded onto the top surface of a commercial Peltier device. When an electrical current was supplied to the Peltier device, the top surface (with microprobes) of the device was cooled and the other side was heated. Heat was conducted from a microsample on the tip of microprobe to the top surface of the Peltier device. A dynamic model of the module was developed and numerical simulation studies were conducted. The prototype module was tested and the experimental results matched well with those predicted by the numerical simulations. The maximum difference between the temperature of a microsample and that at the surface of the Peltier device was approximately 1 °C.

Scanning electrochemical microscopy (SECM) of facilitated ion transfer at the liquid|liquid interface

A new mode of the scanning electrochemical microscope (SECM) operation is presented. A micropipette-based electrode is used as an amperometric microprobe (tip). The tip current is produced by facilitated transfer of ions from the aqueous solution inside the pipette into the organic solvent, e.g., the transfer of K+ into 1,2-dichloroethane (DCE) assisted by dibenzo-18-crown-6 (DB18C6). A positive feedback current is observed when the tip approaches the water|DCE interface due to the transfer of potassium into the aqueous layer and regeneration of DB18C6 species. Good agreement with the SECM theory can be demonstrated. Negative feedback is observed when the tip approaches a glass insulator. The dependence of the SECM response on the shape of the liquid meniscus formed at the micropipette tip is discussed. The technique developed can be used for studies of ion transfer processes at the liquid|liquid and liquid|membrane interfaces and for high resolution electrochemical imaging.

Micromagnetic scanning microprobe system

We describe the apparatus, instrumentation, and data acquisition techniques which make up the micromagnetic scanning microprobe system (MSMS). This system was developed to study magnetoresistive (MR) thin films used in magnetic recording read heads. It uses a dc, four-probe resistance measurement coupled with two pairs of orthogonal field sources. Voltage contacts to the thin film are made with microprobe tips 0.1 μm in diameter on local edge and central regions of the film. Horizontal and vertical microscopes are used to verify tip placement. Results from magnetoresistance measurements of the dynamic response of a MR read head film are shown to demonstrate system operation and performance. The bulk and local magnetoresistance of a 10 μm×10 μm NiFe thin film was measured as a function of applied field and angle. Significant variations in MR responses were seen across the width of the device because of local domain formation. The MSMS is an effective tool for characterizing the effects of domain formation on the output of a MR read head.