Dissipation Mechanisms in Thin-Film Silicon Microresonators on Glass Substrates

ABSTRACTThe fabrication and characterization of thin-film silicon resonators processed at temperatures below 110°C on glass substrates is described. The microelectromechanical structures consist of surface micromachined bridges of phosphorus-doped hydrogenated amorphous silicon (n+-a-Si:H) deposited by plasma-enhanced chemical vapor deposition (PECVD) suspended over a metallic gate counterelectrode. The structures are electrostatically actuated. Resonance frequencies in the MHz range and quality factors as high as 5000 are observed in vacuum. The effect of the geometrical dimensions of the bridges and of the measurement pressure on the resonance amplitude and frequency is studied. The elementary energy dissipation processes in a-Si:H-based resonators are discussed. At atmospheric pressure, air damping dominates the energy dissipation. In vacuum, intrinsic mechanisms, such as clamping losses and surface losses, control the energy dissipation.

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MEMS Microresonators Based on Nanocrystalline Silicon

MRS Proceedings ◽

10.1557/proc-808-a10.9 ◽

2004 ◽

Vol 808 ◽

Cited By ~ 1

Author(s):

J. Gaspar ◽

T. Adrega ◽

V. Chu ◽

J. P. Conde

Keyword(s):

Energy Dissipation ◽

Chemical Vapor ◽

Nanocrystalline Silicon ◽

Quality Factors ◽

Electrostatically Actuated ◽

Glass Substrates ◽

Boron Doped ◽

Resonance Frequencies ◽

Geometrical Dimensions

ABSTRACTThis paper describes the fabrication and characterization of thin-film nanocrystalline silicon microresonators processed at temperatures below 110°C on glass substrates. The microelectromechanical structures consist of surface micromachined bridges of boron-doped hydrogenated nanocrystalline silicon (p+-nc-Si:H) deposited at 100°C by hot-wire chemical vapor deposition (HWCVD). The microbridges, which are suspended over an Al gate electrode, are electrostatically actuated and the mechanical resonance is detected in vacuum using an optical setup. The resonance frequency and energy dissipation in p+-nc-Si:H based resonators are studied as a function of the geometrical dimensions of the microstructures. Resonance frequencies between 700 kHz and 36 MHz and quality factors as high as 2000 are observed. A Young's modulus of 160 GPa for the structural bridge film is extracted from the experimental data using an electromechanical model and the main intrinsic energy dissipation mechanisms in nc-Si:H microresonators are discussed.

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Thin-Film Electrostatic Actuators on Flexible Plastic Substrates

MRS Proceedings ◽

10.1557/proc-782-a2.5 ◽

2003 ◽

Vol 782 ◽

Cited By ~ 3

Author(s):

J. Gaspar ◽

V. Chu ◽

J. P. Conde

Keyword(s):

Thin Film ◽

Resonance Frequency ◽

Actuation Voltage ◽

Quality Factors ◽

Electrostatic Actuators ◽

Plastic Substrates ◽

Electrostatically Actuated ◽

Glass Substrates ◽

Resonance Frequencies ◽

Silicon Based

ABSTRACTThin-film silicon micromachined bridge actuators are fabricated at temperatures below 110°C on flexible polyethylene terephthalate plastic substrates. The micromechanical structures are electrostatically actuated both at the resonance frequency and at below-resonance frequencies, and the resulting deflection is optically monitored. Deflections up to 100 nm are measured below the resonance frequency with subnanometric precision. Resonance frequencies in the MHz range are observed in vacuum with quality factors of the order of 100. The movement is studied as a function of the geometrical dimensions of the actuators, of the actuation voltage and of the measurement pressure. The experimental data are analyzed using an electromechanical model. The performance of hydrogenated amorphous silicon based resonators on PET substrates is compared to that of similar microstructures on glass substrates.

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Performance of Thin-Film Silicon MEMS Resonators in Vacuum

MRS Proceedings ◽

10.1557/proc-762-a18.1 ◽

2003 ◽

Vol 762 ◽

Cited By ~ 2

Author(s):

J. Gaspar ◽

V. Chu ◽

J. P. Conde

Keyword(s):

Thin Film ◽

Single Layer ◽

Quality Factors ◽

Gate Electrode ◽

Glass Substrates ◽

Mems Resonators ◽

Resonance Frequencies ◽

Heavily Doped ◽

Processing Steps

AbstractThis paper reports on the fabrication and characterization of microelectromechanical bridge resonators on glass substrates using thin-film technology and surface micromachining. All the processing steps are performed at temperatures below 110°C. The microbridges consist of either a single layer of heavily doped n-type amorphous silicon (n+-a-Si:H) or bilayers of aluminum (Al) and intrinsic a-Si:H. The bridge is suspended over a gate electrode with a 1 μm air-gap. Applying a voltage between the bridge and an underlying Al gate electrode electrostatically actuates the microstructures. The resulting deflection is monitored optically. The resonance of the microbridges is measured in air and in vacuum. Resonance frequencies up to 70 MHz and quality factors up to 3000 are obtained at pressures below 1 Torr. The energy dissipation mechanisms of the resonators are discussed.

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Improving low pressure chemical vapor deposited zinc oxide contacts for thin film silicon solar cells by using rough glass substrates

Thin Solid Films ◽

10.1016/j.tsf.2011.06.080 ◽

2011 ◽

Vol 520 (4) ◽

pp. 1218-1222 ◽

Cited By ~ 14

Author(s):

J. Steinhauser ◽

J.-F. Boucher ◽

E. Omnes ◽

D. Borrello ◽

E. Vallat-Sauvain ◽

...

Keyword(s):

Thin Film ◽

Zinc Oxide ◽

Solar Cells ◽

Chemical Vapor ◽

Low Pressure ◽

Silicon Solar Cells ◽

Glass Substrates ◽

Thin Film Silicon ◽

Chemical Vapor Deposited ◽

Pressure Chemical

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Thin Film Microelectromechanical Systems

MRS Proceedings ◽

10.1557/proc-715-a12.3 ◽

2002 ◽

Vol 715 ◽

Cited By ~ 1

Author(s):

V. Chu ◽

J. Gaspar ◽

J.P. Conde

Keyword(s):

Thin Film ◽

Microelectromechanical Systems ◽

Absolute Calibration ◽

Quality Factors ◽

Large Area ◽

Glass Substrates ◽

Resonance Frequencies ◽

Bridge Structures ◽

On Chip

AbstractThis paper presents the fabrication and characterization of MEMS structures on glass substrates using thin film silicon technology and surface micromachining. The technology developed to process bridge and cantilever structures as well as the electromechanical characterization of these structures is discussed. This technology can enable the expansion of MEMS to applications requiring large area and/or flexible substrates. The main results for the characterization of the movement of the structures are as follows: (1) in the quasi-DC regime and at low applied voltages, the response is linear with the applied dc voltage. Using an electromechanical model which takes into account the constituent materials and geometry of the bilayer, it is possible to extract the deflection of the structures. This estimate suggests that it is possible to control the actuation of these structures to deflections on the sub-nanometric scale; (2) resonance frequencies of up to 20 MHz have been measured on hydrogenated amorphous silicon (a-Si:H) bridge structures with quality factors (Q) of 70-100 in air. The frequency depends inversely on the square of the structure length, as predicted by the mechanical model; and (3) using an integrated permanent magnet/magnetic sensor system, it is possible to measure the structure movement on-chip and to obtain an absolute calibration of the deflection of the structures.

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Thin film amorphous silicon bulk-mode disk resonators fabricated on glass substrates

MRS Proceedings ◽

10.1557/opl.2011.62 ◽

2011 ◽

Vol 1299 ◽

Cited By ~ 2

Author(s):

A. Gualdino ◽

V. Chu ◽

J. P. Conde

Keyword(s):

Thin Film ◽

Amorphous Silicon ◽

Chemical Vapour ◽

Quality Factors ◽

Glass Substrates ◽

Disk Resonators ◽

Bulk Mode ◽

Resonance Frequencies ◽

Silicon Bulk

ABSTRACTThe fabrication and characterization of thin-film silicon bulk resonators processed on glass substrates is described. The microelectromechanical (MEMS) structures consist of surface micromachined disk resonators of phosphorous-doped hydrogenated amorphous silicon (n+-a-Si:H) deposited by radiofrequency plasma enhanced chemical vapour deposition (RF-PECVD). The devices are driven into resonance by electrostatic actuation and the vibrational displacement is detected optically. Resonance frequencies up to 30 MHz and quality factors in the 103-104 range in vacuum were measured. A high density of modes that increases with resonator diameter was observed. Membrane-like vibrational modes show good agreement with finite element simulations. The effect of geometrical dimensions of the disks on the resonance frequency was also studied. When operated in air higher harmonic modes show increasing quality factors.

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Reliability and stability of thin-film amorphous silicon MEMS on glass substrates

MRS Proceedings ◽

10.1557/opl.2011.253 ◽

2011 ◽

Vol 1299 ◽

Author(s):

P. M. Sousa ◽

V. Chu ◽

J. P. Conde

Keyword(s):

Thin Film ◽

Resonance Frequency ◽

Frequency Shift ◽

Amorphous Silicon ◽

Structural Damage ◽

Chemical Vapor ◽

Stability Study ◽

Glass Substrates ◽

Resonance Frequency Shift ◽

Mems Resonators

ABSTRACTIn this work, we present a reliability and stability study of doped hydrogenated amorphous silicon (n+-a-Si:H) thin-film silicon MEMS resonators. The n+-a-Si:H structural material was deposited using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) and processed using surface micromachining at a maximum deposition temperature of 110 ºC. n+-a-Si:H resonant bridges can withstand the industry standard of 1011 cycles at high load with no structural damage. Tests performed up to 3x1011 cycles showed a negligible level of degradation in Q during the entire cycling period which in addition shows the high stability of the resonator. In measurements both in vacuum and in air a resonance frequency shift which is proportional to the number of cycles is established. This shift is between 0.1 and 0.4%/1x1011 cycles depending on the applied VDC. When following the resonance frequency in vacuum during cyclic loading, desorption of air molecules from the resonator surface is responsible for an initial higher resonance frequency shift before the linear dependence is established.

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Integrated Magnetic Sensing of Electrostatically Actuated Thin-Film Microbridges

MRS Proceedings ◽

10.1557/proc-729-u3.7 ◽

2002 ◽

Vol 729 ◽

Cited By ~ 3

Author(s):

J. Gaspar ◽

Haohua Li ◽

P.P. Freitas ◽

V. Chu ◽

J.P. Conde

Keyword(s):

Thin Film ◽

Low Temperatures ◽

Counter Electrode ◽

Spin Valve ◽

Metal Gate ◽

Electrostatically Actuated ◽

Glass Substrates ◽

Hydrogenated Amorphous ◽

Bridge Length ◽

The Magnetic Field

AbstractBilayer microbridges of aluminum and hydrogenated amorphous silicon are fabricated using thin film technology and surface micromachining at low temperatures on glass substrates. The microstructure is electrostatically actuated by applying a voltage between the bridge and a metal gate counter electrode placed beneath it. The movement is measured with a precision close to 0.1 Å by sensing the magnetic field of a permanent magnet, deposited and patterned on top of the microbridge, with an integrated spin valve magnetic sensor. The deflection of the bridge is at the same time monitored using an optical setup. The deflection of the structures is studied as a function of the driving applied gate voltage and bridge length and experimental results are analyzed with an electromechanical model.

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