Wafer Bonding of SiC-AlN at Room Temperature for All-SiC Capacitive Pressure Sensor (original) (raw)
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Microsystem Technologies, 2011
In order to evaluate the potential of amorphous silicon carbide (a-SiC) films for piezoresistive sensors applications, a pressure sensor has been developed based on this material. The deposition conditions and properties of a-SiC films deposited on thermally oxidized (100) Si substrates by two techniques enhanced by plasma, PECVD (plasma enhanced chemical vapor deposition) and RF magnetron sputtering, are briefly described and compared. Among the SiC films produced, we choose the nitrogendoped PECVD SiC film to fabricate the piezoresistors of the sensor. The structure of the sensor consists of six a-SiC piezoresistors, configured in Wheatstone bridge, on a SiO 2 / Si square diaphragm. The sensor was tested for applied pressure ranging from 0 to 12 psi and supply voltage of 12 V. A preliminary study of the influence of the temperature on the performance of the sensor was performed by experimental measurements and theoretical investigations.
Fabrication of SiC MEMS Pressure Sensor Based on Novel Vacuum-Sealed Method
2008 Second International Conference on Integration and Commercialization of Micro and Nanosystems, 2008
The fabrication of SiC MEMS pressure sensor based on novel vacuum-sealed method is presented in this paper. The sensor was fabricated using surface micromachining. Due to its excellent mechanical properties and high chemical resistance, PECVD (Plasma Enhanced Chemical Vapor Deposition) SiC was chosen as structural material. Polyimide is the sacrificial layer which solve stiction problem in process. STS PECVD system is utilized to realize releasing, deposition and vacuum sealing consecutively in the process chamber. By eliminating wafer cleaning between these processes and dry etching of sacrificial layer, stiction problem is prevented. Therefore, this new process achieved high yield and low cost.
Characterization of polycrystalline 3CB-SiC thin films for MEMS and pressure sensors application
The Fifth International Conference on Advanced Semiconductor Devices and Microsystems, 2004. ASDAM 2004., 2004
Characterization of cubic 3C(fJ)-SiC samples for pressure sensors and micro-electromechanical system (MEMS) applications is reported in this paper. Polycrystalline 3C(fJ)-SiC thinjilms have been deposited on oxidized Si by low pressure chemical vapor deposition (LPCVD) to obtain bi-layer structures [Si(lOO)/SiO;lpoly 3C-SiCj. The films have been preliminary characterized by atomic force microscopy (AFM) and surface photovollage spectroscopy (SPS) and then ohmic contacts have been optimized by transmission line method (TLM) analyses performed at diff erent temperatures focusing the attention on the evaluation of the bulk resistivity (p), the spec ifi c contact resistivity (pJ.
Japanese Journal of Applied Physics, 2016
A modified surface activated bonding (SAB) with Fe-Si multi-nanolayers is expected to achieve the wafer bonding of SiC to various materials. However, Fe diffusion, which affects device performance, cannot be avoided during some annealing processes. In this work, the room-temperature wafer bonding of SiC-Si by only one sputtered Si nanolayer was successfully achieved. The bonding interface was investigated. A uniform intermediate layer with a thickness of >15 nm just containing Si, C, and Ar was found at the interface. The bonding strength between the SiC surface and the sputtered Si nanolayer could reach the bulk Si strength in accordance with the results of the strength test. This indicates that the wafer bonding of SiC to any other materials can be achieved easily if the material could be also strongly bonded to the sputtered Si nanolayer. In addition, the thermal and chemical reliabilities of the SiC-Si bonding interface were investigated by rapid thermal annealing and KOH etching, respectively.
Journal of Engineering, 2014
This paper discusses the mechanical and electrical effects on 3C-SiC and Si thin film as a diaphragm for MEMS capacitive pressure sensor operating for extreme temperature which is 1000 K. This work compares the design of a diaphragm based MEMS capacitive pressure sensor employing 3C-SiC and Si thin films. A 3C-SiC diaphragm was bonded with a thickness of 380 μm Si substrate, and a cavity gap of 2.2 μm is formed between the wafers. The MEMS capacitive pressure sensor designs were simulated using COMSOL ver 4.3 software to compare the diaphragm deflection, capacitive performance analysis, von Mises stress, and total electrical energy performance. Both materials are designed with the same layout dimensional with different thicknesses of the diaphragm which are 1.0 μm, 1.6 μm, and 2.2 μm. It is observed that the 3C-SiC thin film is far superior materials to Si thin film mechanically in withstanding higher applied pressures and temperatures. For 3C-SiC and Si, the maximum von Mises stres...
3C-SiC HeteroEpitaxial Films for Sensors Fabrication
Advances in Science and Technology, 2008
Silicon Carbide (SiC) is a very promising material for the fabrication of a new category of sensors and devices, to be used in very hostile environments (high temperature, corrosive ambient, presence of radiation, etc.). The fabrication of SiC MEMS-based sensors requires new processes able to realize microstructures on bulk material or on the SiC surface. The hetero-epitaxial growth of 3C-SiC on silicon substrates allows one to overcome the traditional limitations of SiC microfabrication. This approach puts together the standard silicon bulk microfabrication methodologies with the robust mechanical properties of 3C-SiC. Using this approach we were able to fabricate SiC cantilevers for a new class of pressure sensor. The geometries studied were selected in order to study the internal residual stress of the SiC film. X-Ray Diffraction polar figure and Bragg-Brentano scan analysis were used to check to crystal structure and the orientations of the film. SEM analysis was performed to analyze the morphology of the released MEMS structures.
Fabrication and Characterization of a SiC/SiO 2 /Si Piezoresistive Pressure Sensor
In this work, we report the fabrication and characterization of a SiC/SiO 2 /Si piezoresistive pressure sensor. The sensor structure consists of six PECVD SiC thin-film piezoresistors configured in Wheatstone bridge on a thermally oxidized micromachined silicon diaphragm. In order to fabricate this sensor, three lithographic masks were designed: one to define the square diaphragm (1800 μm x 1800 μm), another for the piezoresistors and the third for the Ti/Au metal lines. The diaphragm was formed by anisotropic etching of Si in KOH solution and the piezoresistors by reactive ion etching (RIE) of SiC. The sensor chip size is 4.5 mm x 4.5 mm. It was bonded on an alumina substrate using silicone and an aluminum cup was used for protection. The output voltage of the sensor was measured for applied pressure ranging from 0 to 12 psi and voltage suply of 12V.
Recent Developments on Silicon Carbide Thin Films for Piezoresistive Sensors Applications
The purpose of this chapter is to present an overview of the deposition techniques of SiC films, summarizing the deposition conditions that affect the piezoresistive properties of these films, the influence of the temperature on their piezoresistive properties and comparing the performance of piezoresistive sensors based on SiC films with those based in other materials. Moreover, the chapter focus attention is on the development of pressure sensors and accelerometers based on SiC films with suited piezoresistive properties to substitute the silicon in the microfabrication of these sensors so as to extend their endurance under harsh environment.
High-temperature single-crystal 3C-SiC capacitive pressure sensor
IEEE Sensors Journal
Single-crystal 3C-silicon carbide (SiC) capacitive pressure sensors are proposed for high-temperature sensing applications. The prototype device consists of an edge-clamped circular 3C-SiC diaphragm with a radius of 400 μm and a thickness of 0.5 μm suspended over a 2-μm sealed cavity on a silicon substrate. The 3C-SiC film is grown epitaxially on a 100-mm diameter <100> silicon substrate by atmospheric pressure chemical vapor deposition. The fabricated sensor demonstrates a high-temperature sensing capability up to 400°C, limited by the test setup. At 400°C, the device achieves a linear characteristic response between 1100 and 1760 torr with a sensitivity of 7.7 fF/torr, a linearity of 2.1%, and a hysterisis of 3.7% with a sensing repeatability of 39 torr (52 mbar). A wide range of sensor specifications, such as linear ranges, sensitivities, and capacitance values, can be achieved by choosing the proper device geometrical parameters.