An Approach on the Use of Co-Sputtered W-DLC Thin Films as Piezoresistive Sensing Materials

2021 ◽  
Vol 14 ◽  
Author(s):  
Gabriela Leal ◽  
Humber Furlan ◽  
Marcos Massi ◽  
Mariana Amorim Fraga
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Synthesis Method ◽  
Pressure Sensors ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Diamond Like Carbon ◽  
Piezoresistive Sensors ◽  
Thin Film Resistors ◽  
Lift Off

Background: Miniaturized piezoresistive sensors, particularly strain gauges, pressure sensors, and accelerometers, have been used for measurements and control applications in various fields, such as automotive, aerospace, industrial, biomedical, sports, and many more. A variety of different materials have been investigated for the development of these sensors. Among them, diamond-like carbon (DLC) thin films have emerged as one of the most promising piezoresistive sensing materials due to their excellent mechanical properties, such as high hardness and high Young’s modulus. At the same time, metal doping has been studied to enhance its electrical properties. Objective: This article explores the use of co-sputtered tungsten-doped diamond-like carbon (W-DLC) thin films as microfabricated strain gauges or piezoresistors. Methods: Different serpentine thin-film resistors were microfabricated on co-sputtered W-DLC thin films using photolithography, metallization, lift-off, and RIE (reactive ion etching) processes. In order to evaluate their piezoresistive sensing performance, gauge factor (GF) measurements were carried out at room temperature using the cantilever beam method. Results: GF values obtained in this study for co-sputtered W-DLC thin films are comparable to those reported for W-DLC films produced and characterized by other techniques, which indicates the feasibility of our approach to use them as sensing materials in piezoresistive sensors. Conclusion: W-DLC thin films produced by the co-magnetron sputtering technique can be considered as sensing materials for miniaturized piezoresistive sensors due to the following key advantages: (i) easy and well-controlled synthesis method, (ii) good piezoresistive properties exhibiting a GF higher than metals, and (iii) thin-film resistors formed by a simple microfabrication process.

Study on the Correlation between Film Composition and Piezoresistive Properties of PECVD SixCy Thin Films

2013 ◽  
Vol 740-742 ◽  
pp. 431-434 ◽  
Author(s):  
Mariana A. Fraga ◽  
Leandro L. Koberstein
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
The Other ◽  
Gauge Factor ◽  
Temperature Coefficient Of Resistance ◽  
Si Substrates ◽  
Thin Film Resistors ◽  
Lift Off

The effects of carbon content on the piezoresistive properties of non-stoichiometric silicon carbide (SixCy) films deposited on thermally oxidized (100) Si substrates by Plasma Enhanced Chemical Vapor Deposition (PECVD) from silane (SiH4) and methane (CH4) gas mixtures have been investigated. Four different film compositions have been obtained by varying SiH4 flow ratios from 1.0 to 4.0 sccm, while the other parameters were kept constant. In order to evaluate the piezoresistive properties of the SixCy films, we have developed test structures consisting of SixCy thin-film resistors defined by reactive ion etching (RIE) with Ti/Au pads formed by lift-off process. The gauge factor (GF) and temperature coefficient of resistance (TCR) of each SixCy film were measured.

Structural and Piezoresistive Characteristics of Amorphous Silicon Carbide Films Grown on AlN/Si Substrates

2012 ◽  
Vol 1433 ◽  
Author(s):  
Mariana A. Fraga ◽  
Humber Furlan ◽  
Rodrigo S. Pessoa ◽  
Luiz A. Rasia
Keyword(s):  
Thin Films ◽  
Silicon Carbide ◽  
Amorphous Silicon ◽  
Rf Magnetron Sputtering ◽  
Gauge Factor ◽  
Amorphous Silicon Carbide ◽  
Si Substrates ◽  
Intermediate Layers ◽  
Thin Film Resistors ◽  
Lift Off

ABSTRACTAmorphous silicon carbide (a-SiC) thin films have been grown on aluminum nitride (AlN) intermediate layers on (100) Si substrates by RF magnetron sputtering technique. Profilometry, four-point probe method, Rutherford backscattering spectroscopy (RBS) and Fourier transform infrared (FTIR) were employed to characterize the as-deposited SiC thin films. Test structures have been developed to investigate the piezoresistive properties. These structures consist of SiC thin-film resistors on AlN/Si substrates defined by reactive ion etching (RIE) with Ti/Au pads formed by lift-off process. Gauge factor (GF) and temperature coefficient of resistance (TCR) measurements have been performed and demonstrated the potential of these resistors to be used as sensing elements in devices for high temperature application.

scholarly journals Creep adjustment of strain gauges based on granular NiCr-carbon thin films

2021 ◽  
Vol 10 (1) ◽  
pp. 53-61
Author(s):  
Maximilian Mathis ◽  
Dennis Vollberg ◽  
Matthäus Langosch ◽  
Dirk Göttel ◽  
Angela Lellig ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Creep Behavior ◽  
Polymer Substrate ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Strain Transfer ◽  
Spring Element ◽  
Force Transducers ◽  
Carbon Thin Film

Abstract. An important property of high-precision mechanical sensors such as force transducers or torque sensors is the so-called creep error. It is defined as the signal deviation over time at a constant load. Since this signal deviation results in a reduced accuracy of the sensor, it is beneficial to minimize the creep error. Many of these sensors consist of a metallic spring element and strain gauges. In order to realize a sensor with a creep error of almost zero, it is necessary to compensate for the creep behavior of the metallic spring element. This can be achieved by creep adjustment of the used strain gauges. Unlike standard metal foil strain gauges with a gauge factor of 2, a type of strain gauges based on sputter-deposited NiCr-carbon thin films on polymer substrates offers the advantage of an improved gauge factor of about 10. However, for this type of strain gauge, creep adjustment by customary methods is not possible. In order to remedy this disadvantage, a thorough creep analysis is carried out. Five major influences on the creep error of force transducers equipped with NiCr-carbon thin-film strain gauges are examined, namely, the material creep of the metallic spring element (1), the creep (relaxation) of the polymer substrate (2), the composition of the thin film (3), the strain transfer to the thin film (4), and the kind of strain field on the surface of the transducer (5). Consequently, we present two applicable methods for creep adjustment of NiCr-carbon thin- film strain gauges. The first method addresses the intrinsic creep behavior of the thin film by a modification of the film composition. With increasing Cr content (at the expense of Ni, the intrinsic negative creep error can be shifted towards zero. The second method is not based on the thin film itself but rather on a modification of the strain transfer from the polyimide carrier to the thin film. This is achieved by controlled cutting of well-defined deep trenches into the polymer substrate via a picosecond laser.

LTCC Substrates for High Performance Strain Gauges

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000175-000180
Author(s):  
Bjoern Brandt ◽  
Marion Gemeinert ◽  
Ralf Koppert ◽  
Jochen Bolte ◽  
Torsten Rabe
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Performance ◽  
Coefficient Of Thermal Expansion ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Metal Foil ◽  
Accuracy Class ◽  
Film Sensor ◽  
Load Cells

Recent advances in the development of high gauge factor thin-films for strain gauges prompt the research on advanced substrate materials. A glass ceramic composite has been developed in consideration of a high coefficient of thermal expansion and a low modulus of elasticity for the application as support material for thin-film sensors. Constantan foil strain gauges were fabricated from this material by tape casting, pressure-assisted sintering and subsequent lamination of the metal foil on the planar ceramic substrates. The sensors were mounted on a strain gauge beam arrangement and load curves and creep behavior were evaluated. The accuracy of the assembled load cells correspond to accuracy class C6. That qualifies the load cells for the use in automatic packaging units and confirms the applicability of the LTCC substrates for fabrication of accurate strain gauges. To facilitate the deposition of thin film sensor structures onto the LTCC substrates, the pressure-assisted sintering technology has been refined. By the use of smooth setters instead of release tapes substrates with minimal surface roughness were fabricated. Metallic thin films deposited on these substrates exhibit low surface resistances comparable to thin films on commercial alumina thin-film substrates. The presented advances in material design and manufacturing technology are important to promote the development of high performance thin-film strain gauges.

scholarly journals Cylinder pressure sensors for smart combustion control

2019 ◽  
Vol 8 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Dennis Vollberg ◽  
Dennis Wachter ◽  
Thomas Kuberczyk ◽  
Günter Schultes
Keyword(s):  
Thin Films ◽  
Test Bench ◽  
Copper Wire ◽  
Combustion Process ◽  
Pressure Sensors ◽  
Gauge Factor ◽  
Full Detail ◽  
Relative Pressure ◽  
Cylinder Pressure ◽  
Combustion Control

Abstract. Different sensor concepts for time-resolved cylinder pressure monitoring of combustion engines are realized and evaluated in this paper. We distinguish a non-intrusive form of measurement outside the cylinder, performed by means of a force compression rod from intrusive, real in-cylinder measurement by means of pressure membrane sensors being exposed to the hot combustion process. The force compression rod has the shape of a sine wave with thinner zones equipped with highly sensitive foil strain gauges that experience a relatively moderate temperature level of 120 ∘C. The sensor rod delivers a relative pressure value that may be influenced by neighbour cylinders due to mechanical coupling. For the intrusive sensor type, two different materials for the membrane-type sensor element were simulated and tested, one based on the ceramic zirconia and the other based on stainless steel. Due to the higher thermal conductivity of steel, the element experiences only 200 ∘C while the zirconia element reaches 300 ∘C. Metallic chromium thin films with high strain sensitivity (gauge factor of 15) and high-temperature capability were deposited on the membranes and subsequently structured to a Wheatstone bridge. The pressure evolution can be measured with both types in full detail, comparable to the signals of test bench cylinder pressure sensors. For the preferential steel-based sensor type, a reliable laser-welded electrical connection between the thin films on the membrane and a copper wire was developed. The in-cylinder pressure sensors were tested both on a diesel test bench and on a gas-fired engine. On the latter, an endurance test with 20 million cycles was passed. Reliable cylinder pressure sensors with a minimum of internal components are thus provided. The signals will be processed inside the sensor housing to provide analysis and aggregated data, i.e. mass fraction burned (MFB50) and other parameters as an output to allow for smart combustion control.

Comparison between the Piezoresistive Properties of a-SiC Films Obtained by PECVD and Magnetron Sputtering

2011 ◽  
Vol 679-680 ◽  
pp. 217-220 ◽  
Author(s):  
Mariana A. Fraga
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Magnetron Sputtering ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Rf Magnetron Sputtering ◽  
Strain Gauges ◽  
Beam Bending ◽  
Lift Off ◽  
Sic Films

This work compares the piezoresistive properties of SiC thin films produced by two techniques enhanced by plasma, PECVD (plasma enhanced chemical vapor deposition) and RF magnetron sputtering. In order to study these properties, strain gauges based on SiC films produced were fabricated using photolithography techniques in conjunction with lift-off processes. The beam-bending method was used to characterize the SiC strain gauges fabricated.

scholarly journals Comparison of Arc Erosive and Laser Beam Trimming of Thin Film Resistors

1977 ◽  
Vol 4 (3-4) ◽  
pp. 179-183 ◽  
Author(s):  
Zs. Illyefalvi-Vitéz
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Laser Beam ◽  
Measuring Method ◽  
Optimal Conditions ◽  
Current Generator ◽  
Physical Processes ◽  
Laser Beam Machining ◽  
Arc Erosion ◽  
Thin Film Resistors

The physical processes of arc erosive micromachining and the influence of trimming on the parameters of resistors have been examined, and thin film resistors without trimming are compared with those trimmed by arc erosion and laser beam machining.In the paper a theoretical model for arc erosion of thin films is proposed. The optimal conditions of arc erosive trimming are determined. The shape of the cuts are recorded and examined. The applicability of arc erosive trimming with respect to stability is proved. A measuring method is introduced for resistors trimmed by arc erosion using a direct current generator.

Performance of Low Resistivity Electrode Prepared by Electroless Plated for Amorphous Silicon Thin-Film Transistors

2007 ◽  
Vol 561-565 ◽  
pp. 1165-1168 ◽  
Author(s):  
Chien Yie Tsay ◽  
Chung Kwei Lin ◽  
Hong Ming Lin ◽  
Shih Chieh Chang ◽  
Bor Chuan Chung
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Amorphous Silicon ◽  
Large Area ◽  
Silicon Thin Film ◽  
Adhesion Properties ◽  
Low Resistivity ◽  
N2 Atmosphere ◽  
Lift Off ◽  
Processing Steps

The TFTs array fabrication process for large-area TFT-LCD has been continuously developed for simplifying processing steps, improving performance and reducing cost in the process of mass production. In this study, the hydrogenated amorphous silicon (a-Si:H) TFTs with low resistivity electrodes , silver thin films, were prepared by using the selective deposition method that combined lift-off and electroless plated processes. This developed process can direct pattern the electrode of transistor devices without the etching process and provide ease processing steps. The as-deposited Ag films were annealed at 200 oC for 10 minutes under N2 atmosphere. The results shows that the adhesion properties can be enhanced and the resistivity has been improved from 6.0 μ,-cm, significantly decrease by 35%, of as-deposited Ag films by annealed. The thickness of Ag thin film is about 100 nm and the r. m. s roughness value is 1.54 nm. The a-Si:H TFT with Ag thin films as source and drain electrodes had a field effect mobility of 0.18 cm2/Vs, a threshold voltage of 2.65 V, and an on/off ratio of 3×104.

scholarly journals Cu-Doped TiNxOy Thin Film Resistors DC/RF Performance and Reliability

2021 ◽  
Vol 11 (16) ◽  
pp. 7498
Author(s):  
Lev V. Shanidze ◽  
Anton S. Tarasov ◽  
Mikhail V. Rautskiy ◽  
Fyodor V. Zelenov ◽  
Stepan O. Konovalov ◽  
...  
Keyword(s):  
Thin Film ◽  
Sheet Resistance ◽  
Atomic Layer ◽  
High Resistance State ◽  
Intrinsic Resistance ◽  
S Parameters ◽  
Thin Film Resistors ◽  
Power Handling Capability ◽  
Lift Off ◽  
Rf Performance

We fabricated Cu-doped TiNxOy thin film resistors by using atomic layer deposition, optical lithography, dry etching, Ti/Cu/Ti/Au e-beam evaporation and lift-off processes. The results of the measurements of the resistance temperature dependence, non-linearity, S-parameters at 0.01–26 GHz and details of the breakdown mechanism under high-voltage stress are reported. The devices’ sheet resistance is 220 ± 8 Ω/□ (480 ± 20 µΩ*cm); intrinsic resistance temperature coefficient (TCR) is ~400 ppm/°C in the T-range of 10–300 K; and S-parameters versus frequency are flat up to 2 GHz with maximum variation of 10% at 26 GHz. The resistors can sustain power and current densities up to ~5 kW*cm−2 and ~2 MA*cm−2, above which they switch to high-resistance state with the sheet resistance equal to ~200 kΩ/□ (~0.4 Ω*cm) caused by nitrogen and copper desorption from TiNxOy film. The Cu/Ti/TiNxOy contact is prone to ageing due to gradual titanium oxidation while the TiNxOy resistor body is stable. The resistors have strong potential for applications in high-frequency integrated and hybrid circuits that require small-footprint, medium-range resistors of 0.05–10 kΩ, with small TCR and high-power handling capability.

Short-range order in amorphous co-sputtered Ta-Al thin films

1986 ◽  
Vol 44 ◽  
pp. 860-861
Author(s):  
J.C. Barry ◽  
R.S. Timsit ◽  
D. Landheer
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
High Resolution ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Transmission Electron ◽  
Thin Film Resistors ◽  
Diffraction Patterns

Tantalum-aluminium thin films have assumed considerable technological importance since the discovery in the late 1960's that the films are useful in the fabrication of thin film resistors and capacitors. It is generally claimed that these films, when prepared by co-sputtering Ta and Al, are amorphous over a range of Ta concentrations extending approximately from 15 to 75 at%, and are crystalline beyond this range. Diffuse electron diffraction patterns and ‘mottle pattern’ transmission electron micrographs are typical characteristics of the amorphous phase. In this present study we have attempted to identify any atomic short range order in the amorphous Ta-Al films and to follow the changes in this order as the Ta concentration increases across the amorphous/crystalline transition. The co-sputtered Ta-Al films of ≈100A thickness were examined in a high resolution 4000EX electron microscope (top entry, ±15°(x,y) tilt, Cs = 1.0mm ) at 400kV.

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