Contact resistance

About: Contact resistance is a research topic. Over the lifetime, 15262 publications have been published within this topic receiving 232144 citations. The topic is also known as: electrical contact resistance & ECR.

A study of the contacts of a diffused resistor

Abstract: The total resistance of a diffused resistor can be expressed in terms of bulk sheet resistance and three correction terms—namely, contact resistance, current crowding resistance in the contact region, and the contact width correction. The latter two terms have been arrived at theoretically. A new test structure has been designed to measure the metal-silicon contact sheet resistivity and the contact resistance of the resistor. The maximum current density in the contact region is also determined experimentally.

Soldering to a single atomic layer

Abstract: The standard technique to make electrical contact to nanostructures is electron beam lithography. This method has several drawbacks including complexity, cost, and sample contamination. We present a simple technique to cleanly solder submicron sized, Ohmic contacts to nanostructures. To demonstrate, we contact graphene, a single atomic layer of carbon, and investigate low- and high-bias electronic transport. We set lower bounds on the current carrying capacity of graphene. A simple model allows us to obtain device characteristics such as mobility, minimum conductance, and contact resistance.

Modeling Dynamic Electrical Resistance During Resistance Spot Welding

Abstract: Dynamic electrical resistance during resistance spot welding has been quantitatively modeled and analyzed in this work. A determination of dynamic resistance is necessary for predicting the transport processes and monitoring the weld quality during resistance spot welding. In this study, dynamic resistance is obtained by taking the sum of temperature-dependent bulk resistance of the workpieces and contact resistances at the faying surface and electrode-workpiece interface within an effective area corresponding to the electrode tip where welding current primarily flows. A contact resistance is composed of constriction and film resistances, which are functions of hardness, temperature, electrode force, and surface conditions. The temperature is determined from the previous study in predicting unsteady, axisymmetric mass, momentum, heat, species transport, and magnetic field intensity with a mushy-zone phase change in workpieces, and temperature and magnetic fields in the electrodes of different geometries. The predicted nugget thickness and dynamic resistance versus time show quite good agreement with available experimental data. Excluding expulsion, the dynamic resistance curve can be divided into four stages. A rapid decrease of dynamic resistance in stage I is attributed to decreases in contact resistances at the faying surface and electrode-workpiece interface. In stage 2, the increase in dynamic resistance results from the primary increase of bulk resistance in the workpieces and an increase of the sum of contact resistances at the faying surface and electrode-workpiece interface. Dynamic resistance in stage 3 decreases, because increasing rate of bulk resistance in the workpieces and contact resistances decrease. In stage 4 the decrease of dynamic resistance is mainly due to the formation of the molten nugget at the faying surface. The molten nugget is found to occur in stage 4 rather than stage 2 or 3 as qualitatively proposed in the literature. The effects of different parameters on the dynamic resistance curve are also presented.

Highly Compressible and Sensitive Pressure Sensor under Large Strain Based on 3D Porous Reduced Graphene Oxide Fiber Fabrics in Wide Compression Strains.

Abstract: The development of highly sensitive wearable and foldable pressure sensors is one of the central topics in artificial intelligence, human motion monitoring, and health care monitors. However, current pressure sensors with high sensitivity and good durability in low, medium, and high applied strains are rather limited. Herein, a flexible pressure sensor based on hierarchical three-dimensional and porous reduced graphene oxide (rGO) fiber fabrics as the key sensing element is presented. The internal conductive structural network is formed by the rGO fibers which are mutually contacted by interfused or noninterfused fiber-to-fiber interfaces. Thanks to the unique structures, the sensor can show an excellent sensitivity from low to high applied strains (0.24-70.0%), a high gauge factor (1668.48) at an applied compression of 66.0%, a good durability in a wide range of frequencies, a low detection limit (1.17 Pa), and anultrafast response time (30 ms). The dominated mechanism is that under compression, the slide of the graphene fibers through the polydimethylsiloxane matrix reduces the connection points between the fibers, causing a surge in electrical resistance. In addition, because graphene fibers are porous and defective, the change in geometry of the fibers also causes a change in the electrical resistance of the composite under compression. Furthermore, the interfused fiber-to-fiber interfaces can strengthen the mechanical stability under 0.01-1.0 Hz loadings and high applied strains, and the wrinkles on the surface of the rGO fibers increased the sensitivity under tiny loadings. In addition, the noninterfused fiber-to-fiber interfaces can produce a highly sensitive contact resistance, leading to a higher sensitivity at low applied strains.

Method for fabricating capacitor-under-bit line (CUB) dynamic random access memory (DRAM) using tungsten landing plug contacts

Abstract: DRAM devices are made having self-aligned tungsten landing plug contacts to gate electrodes for capacitor-under-bit line (CUB) for reduced aspect ratio contact openings. A planar insulating layer is formed, and openings for bit line contacts, node contacts, and contacts on the chip periphery are concurrently etched for metal landing plugs. A TiN/Ti/N+ polysilicon multilayer is deposited and annealed to form low contact resistance to the substrate A tungsten (W) layer is then deposited and etched back to form W landing plug contacts in the contact openings, which reduce the aspect ratio for the multilevel contacts. A Si3 N4 etch-stop layer and a BPSG are deposited and planarized. Capacitor openings are etched in the BPSG aligned over the node contacts. A conformal conducting layer and a planarized polymer are deposited and polished back to complete the bottom electrodes in the capacitor openings. After removing the polymer, an interelectrode dielectric layer and a conformal conducting layer (top electrode) are deposited and patterned to complete the capacitors. A planar insulating layer is formed and the interlevel contact openings etched with reduced aspect ratios to the landing plugs. W/TiN plugs are formed in the openings, and a first level of metal interconnections is formed.