Vertical Probe Research Articles

Heterogeneously Integrated Vapor–Liquid–Solid Grown Silicon Probes/(111) and Silicon MOSFETs/(100)

In this letter, we report the heterogeneous integration of vertically aligned silicon (Si) microprobe arrays/(111) with MOSFET circuits/(100) by IC processes and subsequent selective vapor-liquid-solid (VLS) growth of Si. A hybrid Si-on-insulator (SOI) substrate with different species of Si layers, e.g., a (100)-top-Si/buried oxide/(111)-handle-Si system, was utilized for the heterogeneous integration technique. MOSFETs were fabricated on (100) top Si, and vertical VLS probes were synthesized at the selectively exposed (111) handle Si. The different Si layers of the MOSFETs and probes were electrically connected by a 3-D metallization technique. In addition, the electrical properties of 3-D metallization and the MOSFETs were investigated. The results indicate potential for heterogeneous integration of VLS probes/(111) and MOSFETs/(100), promising further integrations of numerous microdevices/different species of substrates and CMOS/(100), including fully depleted SOI-CMOS for high-performance electronics, on the same chip.

Kinematic structure and mesoscale variability of the rim current near the coast of Crimea (according to the data of instrumental measurements in September 2008)

By using the results of processing of the instrumental data with high space resolution obtained in September 2008, we analyze the structure of the Rim Current in the upper 100-m layer near the coast of Crimea. We determine the statistical characteristics of the mesoscale fluctuations of currents according to the data of 1165 vertical probes. It is shown that the kinetic energy of intense mesoscale perturbations observed in the vicinity of the Rim Current is of the same order of magnitude as the kinetic energy of the mean current.

Application of Scanning Confocal Electron Microscopy to Nanomaterials and the Improvement in Resolution by Image Processing

Scanning confocal electron microscopy (SCEM) is a novel technique for threedimensional observation with a nanometer-scale resolution. Annular dark field (ADF) SCEM imaging has been demonstrated to have better depth resolution than bright field (BF) SCEM imaging. However, the depth resolution of ADF-SCEM images is limited by the vertical probe size determined by spherical aberration and convergence angle. Therefore, we attempted to employ a deconvolution image processing method to improve the depth resolution of SCEM images. The result of the deconvolution process for vertically sliced SCEM images showed the improvement in the depth resolution by 35-40%.

A MEMS guide plate for a high temperature testing of a wafer level packaged die wafer

This paper describes the design and fabrication of a MEMS guide plate, which was used for a vertical probe card to test a wafer level packaged die wafer. The size of the fabricated MEMS guide plate was 10.6 × 10.6 cm. The MEMS guide plate consisted of 8,192 holes to insert pogo pins, and four holes for bolting between the guide plate and the housing. To insert pogo pins easily, an inclined plane was defined at the back of each hole. Pitch and diameter of the hole were 650 and 260 µm, respectively. In order to define inserting holes and inclined planes at an exact position, silicon MEMS technology was used such as anisotropic etching, deep reactive etching and more. Silicon was used as the material of the guide plate to reduce alignment mismatch between the pogo pins and solder bumps during a high temperature testing. A combined probe card with the fabricated MEMS guide plate showed good x–y alignment and planarity errors within ±9 and ±10 μm at room temperature, respectively. In addition, x–y alignment and planarity are ±20 and ±16 μm at 125°C, respectively. The proposed MEMS guide plate can be applied to a vertical probe card for burn-in testing of a wafer level packaged die wafer because the thermal expansion coefficient of the MEMS guide plate and die wafer is same.

Fire temperature and residence time during dry season burning in a Sudanian savanna-woodland of West Africa with implication for seed germination

Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60°C which is considered lethal for plant tissues. Seasons of burning considered were: an early season fire set at the beginning of the dry season (beginning of December), mid-season fire set at the peak of the dry season (mid-January), and a late season fire at the end of the dry season (end of March). The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position (p < 0.001). The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.

ISCO for Groundwater Remediation: Analysis of Field Applications and Performance

A critical analysis of in situ chemical oxidation (ISCO) projects was performed to characterize situations in which ISCO is being implemented, how design and operating parameters are typically employed, and to determine the performance results being achieved. This research involved design of a database, acquisition and review of ISCO project information, population of the database, and analyses of the database using statistical methods. Based on 242 ISCO projects included in the database, ISCO has been used to treat a variety of contaminants; however, chlorinated solvents are by far the most common. ISCO has been implemented at sites with varied subsurface conditions with vertical injection wells and direct push probes being the most common delivery methods. ISCO has met and maintained concentrations below maximum contaminant levels (MCLs), although not at any sites where dense nonaqueous phase liquids (DNAPL) were presumed to be present. Alternative cleanup levels and mass reduction goals have also been attempted, and these less stringent goals are met with greater frequency than MCLs. The use of pilot testing is beneficial in heterogeneous geologic media, but not so in homogeneous media. ISCO projects cost $220,000 on average, and cost on average $94/yd3 of target treatment zone. ISCO costs vary widely based on the size of the treatment zone, the presence of DNAPL, and the oxidant delivery method. No case studies were encountered in which ISCO resulted in permanent reductions to microbial populations or sustained increases in metal concentrations in groundwater at the ISCO‐treated site.

분기된 구조를 갖는 수직형 MEMS 프로브의 설계

일반적으로 수직형 프로브는 가늘고 긴 S-자형 구조가 중복되기 때문에 신호 전달 특성이 저하되므로 이것에 대한 개선이 필요하다. 본 논문에서 제안된 프로브는 캔틸리버형보다 적은 면적을 차지하는 수직형으로 동시에 많은 메모리를 테스트하기에 적합하며, 특히 외부 압력이 가해졌을 때 분기된 스프링에 의해 폐 루프(closed loop)가 형성되어 기존의 S-자형 수직형 프로브보다 기계적 특성뿐만 아니라 전기적 신호 전달 특성이 개선된 새로운 형태의 수직형 프로브를 제안하였다. 제안된 프로브를 제작하여 측정 및 시뮬레이션을 통해 기존의 S-자형 수직형 프로브보다 오버드라이브(overdrive)는 1.2배, 컨택 포스(contact force)는 2.5배, 신호 전달특성은 <TEX>$0{\sim}10$</TEX> GHz에서 최대 1.4 dB 개선되는 것을 확인하였다. 또한 프로브 카드(probe card)의 신호 전달 특성을 예측할 수 있는 시뮬레이션 모델을 개발하였다. 이를 위하여 프로브 카드를 구성하는 각 부품의 기하학적 특성에 맞도록 2.5D 또는 3D Full-wave 시뮬레이터를 사용하였으며, 계산된 결과는 측정 결과와 매우 잘 일치 하였다. The conventional vertical probe has the thin and long signal path that makes transfer characteristic of probe worse because of the S-shaped structure. So we propose the new vertical probe structure that has branch springs in the S-shaped probe. It makes closed loop when the probe mechanically connects to the electrode on a wafer. We fabricated the proposed vertical probe and measured the transfer characteristic and mechanical properties. Compared to the conventional S-shaped vertical probe, the proposed probe has the overdrive that is 1.2 times larger and the contact force that is 2.5 times larger. And we got the improved transfer characteristic by 1.4 dB in <TEX>$0{\sim}10$</TEX> GHz. Also we developed the simulation model of the probe card by using full-wave simulator and the simulation result is correlated with measurement one. As a result of this simulation model, the cantilever probe and PCB have the worst transfer characteristic in the probe card.

Nonlinear buckling analysis of vertical wafer probe technology

Due to the demand of the industry for an increase of the number of I/Os, while decreasing the die size, the bond pads had to shrink and design restrictions for the active structures underneath had to fall. This leads to new challenges for the electrical probing and the mechanical robustness of the under-pad structures. This paper presents analytical and numerical simulation approaches for predicting the force/travel relation of buckling beam-probes that are used for testing the electrical functionality of back-end-of-line (BEOL) interconnect system underneath a chip pad. For this purpose we investigate, first, in a closed-form manner, the elastic stability of the probe needle according to the large deflection theory of buckled bars. Second, we determine, for a specific geometry of the beam, the probe forces as functions of the probe card overdrive by using the closed-form methods as well as finite-element simulations. The results are finally compared to that obtained in (probe card) experiments.

Spatial Scale‐Dependence of Preferred Flow Domains during Infiltration in a Layered Field Soil

Preferential flow at the Darcian scale may manifest as a consistent spatial pattern of high‐ and low‐flow domains. The degree of persistence of these high‐ and low‐flow domains with depth has important implications for the prediction of subsurface contaminant transport and the development of mitigation strategies to reduce pollution of sensitive environmental receptors. The objective of this study was to quantify the scale‐dependent influence of a soil horizon interface on the vertical continuity of preferred flow domains. Spatial patterns of A and B horizon transient stream tube soil water flux were measured with vertical time domain reflectometry probes in a field soil under four different quasi‐steady surface water application rates. The scale‐dependent vertical continuity of stream tube soil water flux across the A–B horizon interface was quantified with Fourier‐domain coherency spectra. Comparison of the A and B horizon fluxes across and within different water application rates revealed a loss of coherency between A and B horizon water flux with increasing flow rate between spatial scales of 1.0 to 6.75 and 0.38 to 0.50 m. The flux‐ and scale‐dependent behavior of the horizon interface is probably the outcome of: (i) convergence of the pattern of preferred flow domains in the A horizon to the spatial pattern of the saturated hydraulic conductivity of the A horizon with increasing water application rate; and (ii) increased modification of the A horizon soil water flux pattern as the wetting front moves across the soil horizon interface. The results of this study indicate that the pedon, like the representative elementary volume, is hydrologically significant.

미세 피치를 갖는 MEMS 프로브 팁의 설계 및 기계적 특성 평가

프로브 카드는 반도체 제조 공정 전에 반도체 소자 및 필름의 기능과 성능을 검사하기 위한 테스트 장비이다. 반도체 산업의 급속한 기술 발전과 반도체 소자의 고집적화로 인하여 반도체 소자의 패드 간격과 패드의 수가 증가하고 있다. 따라서 반도체 소자의 크기 및 배열의 형태가 계속 축소됨에 따라 미세 피치를 갖고 검사용 핀의 수가 많은 프로브 카드가 필요하다. 본 논문에서는 수직형 프로브 카드의 적용을 위하여 MEMS 기술을 이용한 프로브 팁을 개발하였다. 프로브 팁의 설계를 위해서 유한요소해석을 이용하여 프로브 팁의 구조 및 기계적 특성에 대한 구조설계를 수행하였다. 또한 구조 설계를 적용한 프로브 팁을 제작하여 유한요소해석의 결과와 실제 시험을 통한 접촉력의 평가를 수행하였다. 이에 따라 피치 간격이 약 <TEX>$50{\mu}m$</TEX>이하의 프로브 카드를 제작하였다. The probe card are test modules which are to classify the good semiconductor chips and thin film before the packaging process. In the rapid growth a technology of semiconductor, the number of pads per unit area is increasing and pad arrays are becoming irregular. Therefore, the technology of probe card needs narrow width and lots of probe tip. In this paper, the probe tip based on the MEMS(Micro Electro Mechanical System)technology was developed a new MEMS probe tip for vertical probe card applications. For the structural designs of probe tip were performed to mechanical characteristics and structural analysis using FEM(Finite Element Method). Also, the contact force of MEMS probe tip compared with FEM results and experimental results. Finally, the MEMS probe card was developed a fine pitch smaller than <TEX>$50{\mu}m$</TEX>.

CMOS-MEMS piezoresistive force sensor with scanning signal process circuit for vertical probe card

In response to the essential role probe cards play in the semiconductor testing industry, a CMOS-MEMS force sensing devices capable of simultaneously monitoring the probe reacting force and electrical test signals is designed for probe cards. The probe reacting force can assist operators immediately to identify a broken, deformed, or worn-out probe and recognize that the measured electrical signals are erroneous. The debug time and cost of the IC test can therefore be effectively reduced. Array-type CMOS-MEMS force sensors are capable of monitoring the status of vertical probe cards on-line in the case of both die-level and wafer-level applications. The force sensor essentially is a Wheatstone-bridge-based piezoresistive force sensor with a small surface area and can be easily fabricated. It consists of a membrane composed of metal, silicon oxide, and a piezoresistive layer made of polycrystalline silicon. Moreover, as the conventional back-etch process can barely handle the increasingly smaller probe pitch, we use front etching to etch out a cavity under the membrane on the silicon substrate in order to deform the membrane during the post-process. For measuring the output signals of the sensors, on-chip circuits to scan and amplify the output signals of the sensors are integrated in the design process. Furthermore, a finite element method is adopted to analyze the structure of the sensors and to find the optimal piezoresistive sensor design. The TSMC 0.35 μm 2P4M process is used to fabricate the force sensors and the circuits. According to the measurement results, the designed sensor reports a sensitivity of 3.114 mV/N/V while a load-bearing force is 0.0294 N.

Low-Profile, Small Circularly Polarized Inverted-L Antenna With Double-Folded Arms

A low-profile and small circularly polarized (CP) antenna is proposed and developed in this letter. The proposed CP antenna consists of two modified linearly polarized (LP) inverted-L antenna (ILA) elements with double-folded arms. The double-folded structure plays a significant role in improving impedance matching and radiation characteristics. By properly adjusting the lengths of two arms, quadrature currents can be produced on two orthogonal elements so that circular polarization is achieved. Since the proposed LP elements are low-profile and small in size, the proposed CP antenna is minimized to be about λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /4 in lateral size and λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /7 in height. In addition, the feeding configuration is simplified by using only a short vertical probe instead of an external polarizer. Good agreement is obtained between the simulated and measured results, which validate our design concept. The measured results show that the fabricated CP antenna has a wide impedance bandwidth (VSWR <; 2) of 10.4% and a 3-dB axial ratio (AR) bandwidth of 2.92%.

New fabrication method for micro-pyramidal vertical probe array for probe cards

This paper presents a novel and precision process to fabricate an array of micro metal vertical probes with various tip angles. The process includes an inclined and multiple ultraviolet (UV) lithography, contact lithography and Ni electroforming technology. The tips of micro pyramid vertical probe array utilize the inclined and multiple exposures cooperated with Snell's law. Due to the light pass through an optical transparent homogenous material, the material refractive index results in light path deflection. By changing the workpiece inclination, controllable various tip angles can be fabricated. The experimental results showed that micro metal vertical probes with 54°, 60° and 68° tip angles. The micro-pyramidal vertical probe array can be used in vertical-type probe cards without the conventional complicated assembly.

Analytical Calculation of Impedance Matching for Probe-Fed Microstrip Patch Antennas

The goal of this article is to present an analytical solution to the feeding mechanism for a microstrip patch antenna fed by a vertical probe. The feeding mechanism employs a circular capacitive structure to improve the impedance matching, specifically for microstrip patch antennas on thick dielectrics. A circuit model is introduced to find the design parameters. The circuit model includes a series inductor associated with the feeding probe, a parallel plate radial microstrip line, a series radial gap capacitor and an RLC resonator as the patch antenna. A closed form impedance transformation is generated for the parallel plate radial microstrip line. The result of a Schwarz-Christoffel mapping is used to find the radial gap capacitor. The full-wave simulation and measured results are compared with the model and display good agreement.

Anti-buckling S-shaped vertical microprobes with branch springs

We propose the S-shaped vertical probes with branch springs for the wafer-level testing of IC chips. The conventional S-shaped vertical probe requires a guide structure to prevent buckling due to the large overdrive actuation involved. However, the guide structure not only increases the cost of fabrication, but it also requires a troublesome assembly procedure. In this paper, we present the S-shaped vertical probe with branch springs on the left and right sides of the main spring to prevent buckling. This probe was designed using finite-element methods and fabricated using Ni–Co electroplating. The performances of the probe for the wafer-level testing of IC chips were measured with the probe test equipments. Compared to the identical conventional S-shaped probe, the proposed probe has the overdrive (60 μm) that is 1.2 times larger and the contact force (25 mN) that is 2.5 times larger. This new S-shaped vertical probe satisfies the design requirements for a vertical probe without the guide structure and has the potential for use as a cost-effective guide-free probe card for the wafer-level testing of IC chips.

Measurement of Transient Soil Water Flux Across a Soil Horizon Interface

Understanding the physics of water flow and transport in layered soils requires experimental observations of the magnitude and variability of these processes as they occur in the field. In this study, a time domain reflectometry (TDR) method to measure the spatial pattern of transient, local soil water flux above and below a soil horizon interface under quasi‐steady surface water application was developed and implemented in laboratory and field experiments. The method uses vertical TDR probes spanning two or more soil horizons or layers. Time series of soil water storage measured by the TDR probes are used to quantify transient, local soil water flux during infiltration under quasi‐steady surface water application. Results from the laboratory and field experiments showed that transient soil water flux estimates with the presented methodology were, on average, 106% of the applied water flux (i.e., mass recovery = 106%). Furthermore, in field experiments, excellent agreement between two independent measurements of local soil water flux through the A horizon showed that this methodology is robust and sensitive to spatial variations in soil water flux within soil horizons and changes in local soil water flux as the wetting front crosses the interface between two horizons. In the field experiments, transient local soil water flux through the A and B horizons (measured along a 6.75‐m‐long transect) were positively correlated to each other, but the strength of the correlation decreased with increasing surface water application rates. The flux‐dependent covariance between the measured patterns of transient A and B horizon soil water flux indicates that the soil horizon interface is a hydrologically significant component of the soil profile. In‐depth spatial analysis of the measured soil water flux patterns is the subject of a future study.

Evaluating the salinity distribution of a shallow coastal aquifer by vertical multielectrode profiling (Denmark)

A monitoring system, including five groups of piezometers and five vertical multielectrode profiling probes (VMEP), has been installed in an aquifer beneath a coastal dune in Denmark. In order to assess the salinity distribution within the aquifer, geoelectrical data were gathered in March, June and September 2008, by measuring a dipole-dipole and gradient array using multielectrode profiling. Interpretation of the processed resistivity data was performed by regularized inversion using a one-dimensional, horizontally layered model of formation resistivity. The standard deviation on estimated layer log-resistivity was 0.01–0.03. By estimating two parameters of a power function, observed fluid conductivities derived from samples of porewater were related to corresponding estimated formation resistivities. The conductivity profiles correlate with a winter situation in March with high sea level, active recharge and significant wave activity, causing increased hydraulic heads, a thicker freshwater lens and salt water overlying freshwater close to the sea. In June, the thickness of the freshwater lens is reduced due to less recharge and prevailing offshore winds, imposing density-stable conditions and a sharper transition between fresh and brackish water. During the autumn, aquifer recharge is enhanced and hydraulic heads increase, resulting in a thicker freshwater lens.

Fabrication of a high aspect ratio thick silicon wafer mold and electroplating using flipchip bonding for MEMS applications

We have developed a microfabrication process for high aspect ratio thick silicon wafer molds and electroplating using flipchip bonding with THB 151N negative photoresist (JSR micro). This fabrication technique includes large area and high thickness silicon wafer mold electroplating. The process consists of silicon deep reactive ion etching (RIE) of the silicon wafer mold, photoresist bonding between the silicon mold and the substrate, nickel electroplating and a silicon removal process. High thickness silicon wafer molds were made by deep RIE and flipchip bonding. In addition, nickel electroplating was developed. Dry film resist (ORDYL MP112, TOK) and thick negative-tone photoresist (THB 151N, JSR micro) were used as bonding materials. In order to measure the bonding strength, the surface energy was calculated using a blade test. The surface energy of the bonding wafers was found to be 0.36–25.49 J m−2 at 60–180 °C for the dry film resist and 0.4–1.9 J m−2 for THB 151N in the same temperature range. Even though ORDYL MP112 has a better value of surface energy than THB 151N, it has a critical disadvantage when it comes to removing residue after electroplating. The proposed process can be applied to high aspect ratio MEMS structures, such as air gap inductors or vertical MEMS probe tips.

A 60-GHz CPW-Fed High-Gain and Broadband Integrated Horn Antenna

An integrated horn antenna is presented for 60-GHz WPAN applications. Compared with other types of antenna for 60-GHz WPAN applications, an integrated horn antenna features wide bandwidth and high gain. This integrated H-plane horn is elevated on the top of the substrate using CMOS-compatible microfabrication steps. Antenna efficiency is greatly improved after eliminating dielectric loss. This antenna is excited using an integrated vertical current probe connected with a coplanar-waveguide (CPW) by surface micromachining technologies. The lower part of the horn is constructed by rows of metallized pillars. The upper part and the top wall are built by stacking two layers of micromachined silicon wafers. The horn bottom is formed by metalizing the substrate's top surface. A prototype antenna is designed, fabricated, and characterized. Simulation and measurement results have shown wide input matching bandwidth and radiation bandwidth. The measured radiation pattern agrees well with the simulated one, demonstrating a gain as high as 14.6 dBi.

Effects of Acute Administration of Sigma Receptor Ligands on Mesolimbic Dopamine Neurotransmission in Rats

Sigma receptors (σRs) can modulate cocaine's behavioral effects, which are related to increased mesolimbic dopamine (DA) neurotransmission, and σR agonists can maintain responding in rats that self administer cocaine. We report here effects of σR ligands on DA transmission in rats implanted with vertical microdialysis probes in the nucleus accumbens shell. Cocaine (0.1‐1.0 mg/kg iv) or a non‐selective σ1/2 agonist (DTG: 1.0‐5.6 mg/kg iv) dose‐dependently increased DA levels to 275 and 150% of baseline, respectively. In contrast, the preferential σ1R agonist, PRE‐084 (0.32‐3.2 mg/kg iv), did not significantly modify DA levels. The preferential σ1R antagonist, BD 1063 (10‐30 mg/kg ip), administered alone transiently (&lt;30 min) and dose‐dependently increased DA levels to a maximum of 150%, and later decreased DA levels to ~80% of baseline. The σ1/2 antagonist, BD 1008 (10 mg/kg ip) modestly decreased DA levels over the 2 hr following its administration. The effects of 5.6 mg/kg DTG were attenuated by BD 1008 (10 mg/kg ip), but not by BD 1063 (10‐30 mg/kg ip). In sum, the results show that acute administration of σR ligands can increase DA transmission in a brain area involved in the reinforcing effects of cocaine, and this effect appears to be mediated by the σ2R. Studies are in progress to understand if σR ligands can also modulate cocaine‐induced stimulation of DA transmission.