Electrical, mechanical and metal contact properties of polycrystalline 3C-SiC films for MEMS in harsh environments (original) (raw)
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Journal of Micromechanics and Microengineering, 2014
This paper details the development of low-stress, heavily-doped polycrystalline 3C-SiC films suitable for microelectromechanical systems applications. The films were deposited on 100 mm-diameter silicon (Si) and silicon dioxide (SiO 2 )-coated Si wafers in a large-volume, low-pressure chemical vapor deposition furnace using dichlorosilane (DCS) (SiH 2 Cl 2 ) and acetylene (C 2 H 2 ) as precursors and ammonia (NH 3 ) as the dopant source gas. The effects of NH 3 and deposition pressure on the deposition rate, film residual stress and electrical resistivity were studied. Deposition parameters optimized for a combination of resistivity and residual stress yielded an average resistivity of 0.02 cm and a residual tensile stress of 59 MPa as measured using wafer-scale methods. X-ray photoelectron spectroscopy indicated that the nitrogen concentration in the films was less than 0.5 at%. Variations in the flow rate of NH 3 did not affect the surface roughness of the films, but changes in deposition pressure had an obvious effect on the surface roughness.
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.
Low Stress Polycrystalline SiC Thin Films Suitable for MEMS Applications
Journal of The Electrochemical Society, 2011
This paper details the development of low residual stress and low stress gradient unintentionally doped polycrystalline SiC (poly-SiC) thin films. The films were deposited in a large-volume, low-pressure chemical vapor deposition (LPCVD) furnace on 100 mm-diameter silicon (Si) wafers using dichlorosilane (SiH 2 Cl 2 ) and acetylene (C 2 H 2 ) as precursors. We found that the flow rate of SiH 2 Cl 2 could be used to control the residual film stress in the as-deposited films. Wafer curvature measurements for 2m−thickfilmsindicatedthattensilestressrangingfrom4to55MPaacrossa25waferboathadbeenachieved.Avarietyofmicromachinedstructuresincludinglateralresonantstructures,stresspointersandcantileverswerefabricatedforcharacterizationofthedepositedSiCfilms.TheaverageYoung′smoduluswasfoundtobe403GPa.Residualstressmeasurementswereconsistentwiththoseobtainedusingawafercurvaturetechnique.Interferometricmeasurementsofcantileverbeamsindicatedstressgradientswithanupperboundof52MPa/mfor2 m-thick films indicated that tensile stress ranging from 4 to 55 MPa across a 25 wafer boat had been achieved. A variety of micromachined structures including lateral resonant structures, stress pointers and cantilevers were fabricated for characterization of the deposited SiC films. The average Young's modulus was found to be 403 GPa. Residual stress measurements were consistent with those obtained using a wafer curvature technique. Interferometric measurements of cantilever beams indicated stress gradients with an upper bound of 52 MPa/m for 2m−thickfilmsindicatedthattensilestressrangingfrom4to55MPaacrossa25waferboathadbeenachieved.Avarietyofmicromachinedstructuresincludinglateralresonantstructures,stresspointersandcantileverswerefabricatedforcharacterizationofthedepositedSiCfilms.TheaverageYoung′smoduluswasfoundtobe403GPa.Residualstressmeasurementswereconsistentwiththoseobtainedusingawafercurvaturetechnique.Interferometricmeasurementsofcantileverbeamsindicatedstressgradientswithanupperboundof52MPa/mfor2 m-thick films with tensile stress less than 55 MPa.
Mechanical Properties of 3C-SiC Films for MEMS Applications
MRS Proceedings, 2007
There is a technological need for hard thin films with high elastic modulus and fracture toughness. Silicon carbide (SiC) fulfills such requirements for a variety of applications at high temperatures and for high-wear MEMS. A detailed study of the mechanical properties of single crystal and polycrystalline 3C-SiC films grown on Si substrates was performed by means of nanoindentation using a Berkovich diamond tip. The thickness of both the single and polycrystalline SiC films was around 1-2 µm. Under indentation loads below 500 µN both films exhibit Hertzian elastic contact without plastic deformation. The polycrystalline SiC films have an elastic modulus of 457 + 50 GPa and hardness of 33.5 + 3.3 GPa, while the single crystalline SiC films elastic modulus and hardness were measured to be 433 + 50 GPa and 31.2 + 3.7 GPa, respectively. These results indicate that polycrystalline SiC thin films are more attractive for MEMS applications when compared with the single crystal 3C-SiC, which is promising since growing single crystal 3C-SiC films is more challenging.
Applications of SiC-Based Thin Films in Electronic and MEMS Devices
The goal of this chapter is to discuss the role of in situ incorporation of nitrogen, oxygen, aluminum, boron, phosphorus and argon on the properties of SiC films. Special attention is given to the low temperature SiC growth processes. An overview on the applications of SiC-based thin films in electronic and MEMS devices is presented and discussed. Our recent researches on heterojunction diodes and MEMS sensors are emphasized.
Large area (up to 4") polycrystalline 3C-SiC films have been deposited by Electron Cyclotron Resonance Chemical Vapor Deposition (ECR-CVD) technique. Crystalline and non crystalline substrates such as (100) Si wafers, thermally oxidized Si wafers and Al2O3 ceramic sheets have been used, maintaining the same deposition conditions. The structural and morphological properties of the films were analyzed by means of Transmission Electron Microscopy (TEM) and X-Ray Diffractometry (XRD), while surface morphology was characterized by Atomic Force Microscopy (AFM). Preliminary results on technological processes for the realization of polycrystalline SiC based micro-electro-mechanical systems (MEMS) are reported.
3C-SiC Films on Si for MEMS Applications: Mechanical Properties
Materials Science Forum, 2009
Single crystal 3C-SiC films were grown on and Si substrate orientations in order to study the resulting mechanical properties of this material. In addition, poly-crystalline 3C-SiC was also grown on (100)Si so that a comparison with monocrystaline 3C-SiC, also grown on (100)Si, could be made. The mechanical properties of single crystal and polycrystalline 3C-SiC films grown on Si substrates were measured by means of nanoindentation using a Berkovich diamond tip. These results indicate that polycrystalline SiC thin films are attractive for MEMS applications when compared with the single crystal 3C-SiC, which is promising since growing single crystal 3C-SiC films is more challenging. MEMS cantilevers and membranes fabricated from a 2 µm thick single crystal 3C-SiC grown on (100)Si under similar conditions resulted in a small degree of bow with only 9 µm of deflection for a cantilever of 700 µm length with an estimated tensile film stress of 300 MPa. Single crystal 3C-SiC films on (111)Si substrates have the highest elastic and plastic properties, although due to high residual stress they tend to crack and delaminate.
Single crystal 3C-SiC films were grown on and Si substrate orientations in order to study the resulting mechanical properties of this material. In addition, poly-crystalline 3C-SiC was also grown on (100)Si so that a comparison with monocrystaline 3C-SiC, also grown on (100)Si, could be made. The mechanical properties of single crystal and polycrystalline 3C-SiC films grown on Si substrates were measured by means of nanoindentation using a Berkovich diamond tip. These results indicate that polycrystalline SiC thin films are attractive for MEMS applications when compared with the single crystal 3C-SiC, which is promising since growing single crystal 3C-SiC films is more challenging. MEMS cantilevers and membranes fabricated from a 2 µm thick single crystal 3C-SiC grown on (100)Si under similar conditions resulted in a small degree of bow with only 9 µm of deflection for a cantilever of 700 µm length with an estimated tensile film stress of 300 MPa. Single crystal 3C-SiC films on (111)Si substrates have the highest elastic and plastic properties, although due to high residual stress they tend to crack and delaminate.