Empirical method of calibrating a 4-point microarray for measuring thin-film-sheet resistance

The calibration of a 4-point probe used for sheet-resistance measurements of a thin-film sample is usually based on the calculation of a correction factor C, depending on the probe and sample dimensions. Based on the Van, der Pauw idea, a method of experimental calibration of the 4-point probe is given, if the probe dimensions are sufficiently small in comparison with the sample.     

Correction factor curves for square-array and rectangular-array four-point probes near conducting or nonconducting boundaries

Resistivity measurements made with a four-point probe on a sample having at least one of its dimensions small (i. e., of the order of the spacing between the points of the probe or smaller) require a correction factor to compensate for this condition. Correction factors for various four-point probe arrangements near a conducting or a nonconducting boundary have been derived and plotted for cases where : 1) the four-point probe array is rectangular and of various proportions rather than square, 2) the current points of the square-or rectangular-array probe are perpendicular to the boundary 3) the current points of the square-or rectangular-array probe are parallel to the boundary.     

An implantable CMOS circuit interface for multiplexedmicroelectrode recording arrays

A second-generation multichannel probe designed for measuring single-unit activity in neural structures is described. The probe includes CMOS circuitry for electronically positioning the recording sites with respect to the active neurons and for amplifying and multiplexing the recorded signals. The probe selects eight active recording sites from among 32 on the probe shank using a static input channel selector. The neural signals on the selected channels are then amplified and multiplexed to the outside world. The probe offers a typical AC gain of 300 (15 Hz to 7 kHz), a DC gain of 0.3, and an equivalent input noise of 15 μV rms. Operating from a single 5-V supply, the probe dissipates 2.5 mW of power and implements channel selection, self-testing, data output, and initialization using three external leads. The probe is realized using 12 masks in a high-yield single-sided dissolved wafer process with a 3-μm feature size for the circuitry and a 3-μm pitch on the electrode shanks     

基于全光纤相干层析系统快速扫描探头的研制

提出并实现了应用于光学相干层析系统(OCT)的快速扫描探头结构。该探头利用带有自聚焦透镜的光纤悬臂的共振特性,通过对压电双晶片施加共振频率下的方波电压,实现光纤悬臂的一维线性扫描。利用二维位置敏感探测器,同步记录扫描轨迹。通过软件对光纤延迟线的非线性进行校正。并将扫描探头应用于OCT系统中的玻片实验,获得清晰玻片的二维图像。该探头具有结构简单、易于控制、成本较低、精度较高、速度较快等优点。     

Parameter Modeling for Wafer Probe Test

This paper presents the simulation of parameters for wafer probe test by finite-element modeling with consideration of probe over-travel (OT) distance, scrub, contact friction coefficient, probe tip shapes, and diameter. The goal is to minimize the stresses in the device under the bond pad and eliminate wafer failure in probe test. In the probe test modeling, a nonlinear finite-element contact model is developed for the probe tip and wafer bond pad. Modeling results have shown that the probe test OT, probe tip shape and tip diameters, contact friction between the probe tip and bond pad, as well as the probe scrub of the probe tip on bond pad are important parameters that impact the failure of interlayer dielectric (ILD) layer under bond pad. Comparison between probe test damage and wire bonding failure shows the degree of damage to both probe test and wire bonding on the same bond pad structures. In addition that, a design of experiment (DOE) probe test with different ILD and metal thickness is carried. The correlation between the modeling and the DOE test is studied. The results show that the modeling solution agrees with the DOE probe test data. Modeling results have further revealed that probe test can induce the local tensile (or bending) first principal stress in ILD layer, which may be a root cause of the ILD failure in probe test.     

A Multifilament Method-of-Moments Solution for the Input Impedance of a Probe-Excited Semi-Infinite Waveguide

The input impedance and surface currents of a probe-excited, short-circuited semi-infinite waveguide are determined by the method of moments. Expressions are given for the impressed electric field used to excite the probe from the coaxial source input using a semi-infinite-waveguide Green's function, and expressions are given for a free-space approximate impressed electric field which arises from the coaxial source input. The method-of-moments formulation used is based on a multifilament current approximation and solves for the surface currents of the probe as a function of probe angle around the probe. Comparison of theory and experiment is made.     

An Insulated Coaxial Probe for EM Local Heating

An insulated miniature coaxial probe with a modified geometry has been developed for EM local heating of a biological (or conducting) medium. This probe is basically a lossy coaxial cavity, and its input impedance, current distribution, and power dissipation pattern can be controlled by the selection of terminal impedances, insulating sheath, and the dimensions of the probe. An approximate theory and an experimental study on the probe are presented.     

一种新型的STM探针

以普通的石英光纤为材料，用熔拉腐蚀复合的方法制备出nm量级的光纤探针，而后在针尖表面镀上数十nm厚的金属膜，达到导电性，使其能传导隧道电流，从而研制出一种新型的扫描隧道显微镜（STM）光纤隧道探针，在STM上取得了比较理想的实验结果。本文将光纤隧道探针与金属隧道探针作了比较，并对其性能作了分析。     

STM光纤探针的研制

以普通的石英光纤为材料运用腐蚀－熔拉－腐蚀复合的方法制备出光纤探针，而后在针尖表面镀上一层数十nm厚的金属膜。达到导电性，使其能传导隧道电镜，并在STM上取得了理想的测试结果。     

A probe antenna for in situ measurement of the complex dielectricconstant of materials

A new probe for the in situ measurement of the complex dielectric constant of materials in the microwave frequency region is described. The probe uses two stub antennas mounted on a cylinder. The cylinder is inserted in the material and the transmission coefficient between the two antennas is measured. By comparing this signal with that predicted from a numerical model of the probe obtained by the finite-difference time-domain (FDTD) method we can determine the dielectric constant of the material. The measurement setup and numerical model of the probe are described and several measurement examples in natural and artificial media are presented     

Recombination effects with high-pressure Langmuir probes

With increasing ion density, the ion current collected by a negatively biased electric probe is eventually dominated by ions produced by reactive processes in the vicinity of the probe. Here, we derive an expression for the probe current to a cylindrical probe when all the ions collected to the probe are assumed to be generated within the sheath which surrounds the probe. Measurements of probe current in a seeded atmospheric-pressure flame are in good agreement with the theory. The significance of reaction processes is reinforced by the fact that the maximum probe current is found to be approximately three times the total current that the flame would produce with frozen chemistry, i.e. the saturation current.     

Complex-Point Dipole Formulation of Probe-Corrected Cylindrical and Spherical Near-Field Scanning of Electromagnetic Fields

A probe-corrected electromagnetic theory based on complex-point dipoles is presented for computing the field of an arbitrary source of finite extent (for example a test antenna) from measurements of its near field on a cylindrical or spherical scanning surface. By representing the probe with complex-point dipoles, probe correction is achieved by simple factors that involve Hankel functions evaluated at complex points. Only four complex-point dipoles are needed to represent a typical precision probe used in near-field measurements. The theory uses neither translation and rotation theorems nor differential operators. One disadvantage of the theory is that it employs nonlinear optimization to determine the parameters of the probe model. The complex-point dipole representation of the probe makes realistic simulations of near-field scanning systems straightforward. The cylindrical theory is validated through a numerical example. The spherical theory is validated by experimental data.     

Noninvasive electrical characterization of materials at microwavefrequencies using an open-ended coaxial line: test of an improvedcalibration technique

Dielectric measurements using a probe consisting of a coaxial transmission line with an open-circuit end placed against the sample are discussed. For the 2.99- or 3.6-mm (OD) probes considered, a simple lumped parameter model shows errors above 1 GHz that increase greatly with frequency. An approximate model based on measured probe impedances from 1 to 18 GHz with samples consisting of water, methanol, and dioxane-water mixtures is evaluated. This model is more accurate than the lumped-parameter model and is better suited for calibration of the automatic network analyzer (ANA). The errors introduced in dielectric measurements by the use of approximate models for the probe are discussed. The technique succeeds because of partial cancellation of errors in modeling the probe in ANA-based measurements     

Response of Insulated Electric Field Probes in Finite Heterogeneous Biological Bodies

An ideal probe for measuring the electric field inside a finite heterogeneous biological body should possess a constant calibration factor; probe effective length and equivalent impedance must therefore be independent of its location in the body. A practical probe with minimal variation of these parameters can be implemented by insulating the metallic probe with a thick low-loss dielectric coating of low permittivity. An idealized spherical probe, insulated by a dielectric layer and immersed in a finite Iossy-dielectric body (representative of more general probes) is studied. Analytical expressions for the effective diameter and equivalent impedance of the probe are obtained. Numerical results indicate that the variation of these parameters with probe location is minimized by coating the probe with a relatively thick Iow-permittivity dielectric layer. Experimental impedance and electric field measurements confirm this conclusion. Limitation of using this probe in biological media with low dieletric constants is discussed.     

Electric Probe Measurements on Microstrip

The aim of the experimental investigation reported here is to measure the electric field of microstrip using a field probe. To establish the accuracy of these measurements, the probe is first calibrated against a known field which is obtained by analyzing a wire suspended axially in a rectangular metal tube. Measurements on a simple wire over ground plane circuit indicate that unshielded structures are basically unsuitable for accurate probe calibration. Finally, the theoretical results predicted by a numerical analysis program for microstrip, published recently, are verified by comparing these with the actual field distribution determined experimentally.     

Atomic force microscope probe based controlled pushing for nanotribological characterization

Using an atomic force microscope (AFM) probe as a nanomanipulator, micrometer- and nanometer-sized objects, especially particles, are pushed on substrates for characterizing the object-substrate friction parameters and behavior in various environments, e.g., air, liquid, and vacuum. Two possible nanotribological characterization methods are proposed in this paper: 1) sliding the micro/nano-object on the substrate while it is attached to an AFM probe and 2) nanorobotic pushing of the micro/nano-object with the sharp tip of an AFM probe. The modeling of these methods are realized and experiments are conducted for the latter method using a piezoresistive AFM probe as a one-dimensional force sensor and nanomanipulator. In the experiments, 500-nm radius gold-coated latex particles are pushed on a silicon substrate. Preliminary results show that different frictional behavior such as sliding, rolling, and rotation could be observed, and shear stresses and frictional behavior could be estimated using these techniques at the nanoscale.     

The Electric-Field Probe Near a Material Interface with Application to the Probing of Fields in Biological Bodies

A theoretical model is formulated to determine the effect of an interface between different media on the response of an electric-field probe. The model used provides a "worst case" estimate of the interaction between the probe and the interface. The effect of the interface on the response of the probe is examined as a function of the size of the probe, the insulation on the probe, the load admittance at the terminals of the probe, the dissipation in the surrounding medium and the spacing between the probe and the interface. The use of electricity small bare and insulated probes to measure the field in the interior of biological bodies is discussed as an example. Measured results are shown to be in general agreement with the theory.     

Double $phi$-Step $theta$-Scanning Technique for Spherical Near-Field Antenna Measurements

Probe-corrected spherical near-field antenna measurements with an arbitrary probe set certain requirements on an applicable scanning technique. The computational complexity of the general high-order probe correction technique for an arbitrary probe, that is based on the Phi scanning, is O(N⁴), where N is proportional to the radius of the antenna under test (AUT) minimum sphere in wavelengths. With the present knowledge, the computational complexity of the probe correction for arbitrary probes in the case of the thetas scanning is O(N^-6), which is typically not acceptable. This paper documents a specific double Phi-step thetas scanning technique for spherical near-field antenna measurements. This technique not only constitutes an alternative spherical scanning technique, but it also enables formulating an associated probe correction technique for arbitrary probes with the computational complexity of 0(N4) while the possibility for the exploitation of the advantages of the thetas scanning are maintained.     

New electrostatic probe for absolute measurement of amplitude of surface acoustic wave

A new electrostatic probe is proposed for the absolute measurement of the amplitude of s.a.w. propagating on piezoelectric materials. Experimental measurements have been done on Y-cut Z-propagation LiNbO3 and results are compared with those obtained using an optical probe.