The techniques of micromachining silicon are used for the manufacture of an anemometer with low electric consumption and great sensitivity. To reduce the energy consumption, a suspended membrane of silicon rich silicon nitride SiNx makes it possible to carry out the heat insulation between the heater and the substrate. Platinum (Pt) thin film (3000 A) with titanium (300 A) adhesion layer on SiNx/Si substrate is used for the hot resistor. Among the methods of Pt deposition tested, electron beam evaporation gives the best results for the temperature coefficient of resistance (TCR) of Pt. Its response time is about 6 ms. Sensitivity in laminar and turbulent flow range are respectively 4.80 mV/(m/s)0.45/mW and of 0.705 mV/(m/s)0.8/mW for about 20 mW power supplied. The experiments show that the temperature rise of the sensor is not sensitive to the ambient temperature. Moreover, sensor response shows no significant changes according to parallel or perpendicular orientation of the gas flow.

Anemometer with hot platinum thin film

The techniques of micromachining silicon are used for the manufacturing of a thermal accelerometer. This sensor requires no solid proof mass and has a low cost production. A heating resistor creates a symmetrical temperature profile and two temperature detectors are placed on both sides. When an acceleration is applied, the temperature profile becomes asymmetric and the two detectors measure the differential temperature. Platinum resistors deposited by electron beam evaporation on a SiN x membrane are used as heater and temperature sensors. This paper presents measurements of temperature profile and sensitivity according to the distance heater–detector, power supplied and room temperature. It shows that the sensitivity is proportional to the heating power and decreases when the room temperature increases. Experimental results in tiltmeter utilization and in a centrifuge are also presented. A 3 dB bandwidth of 20 Hz is measured applying a sinusoidal acceleration and the equivalent acceleration noise is found to be 0.3 mg RMS.

Micromachined thermal accelerometer

We present a comprehensive study of dispersion-engineered nanowire photonic crystal waveguides suitable for experiments in quantum optics and atomic physics with optically trapped atoms. Detailed design methodology and specifications are provided, as are the processing steps used to create silicon nitride waveguides of low optical loss in the near-IR. Measurements of the waveguide optical properties and power-handling capability are also presented.

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Nanowire photonic crystal waveguides for single-atom trapping and strong light-matter interactions

Abstract Integration of superconducting nanowire single-photon detectors with nanophotonic waveguides is a key technological step that enables a broad range of classical and quantum technologies on chip-scale platforms. The excellent detection efficiency, timing and noise performance of these detectors have sparked growing interest over the last decade and have found use in diverse applications. Almost 10 years after the first waveguide-coupled superconducting detectors were proposed, here, we review the performance metrics of these devices, compare both superconducting and dielectric waveguide material systems and present prominent emerging applications.

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Waveguide-integrated superconducting nanowire single-photon detectors

The effect of deposition temperature, deposition pressure, or input gas ratio (SiH2Cl2:NH3) on film stress was determined for low-pressure chemical vapor deposited silicon nitride films. Wafer curvature measurements were performed for films deposited on single crystal silicon and amorphous silica wafer substrates to determine film stress σdep, biaxial modulus Ef+, and coefficient of thermal expansion αf. Apparent plane strain film modulus Ēf′ and hardness H were measured using depth-sensing indentation. Ellipsometry was used to measure film thickness tf and refractive index n. Infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), forward recoil energy spectroscopy (FReS), and Rutherford backscattering spectroscopy (RBS) experiments were performed to determine film composition. Although film deposition stress varied from −135 MPa (compressive) to 235 MPa (tensile) Ef+, Ēf′, H, and αf remained nearly constant. Infrared spectroscopy resolved only Si-N species for all films, and results from FReS on ...

Influence of deposition conditions on mechanical properties of low-pressure chemical vapor deposited low-stress silicon nitride films

Varied SiNx films have been deposited by low pressure chemical vapor deposition from silane SiH4 and ammonia NH3 and the influences of the deposition parameters (temperature, total pressure and NH3/SiH4 gaseous ratio) on the film deposition rate, refractive index (assessed at a 830 nm wavelength), stoichiometry and thermomechanical stress are investigated and correlated. Low stress (≈600 MPa) Si3N4 films are obtained for the highest deposition temperature and the lowest total pressure but the gaseous ratio is shown to be the dominant parameter. According to the SiNx stoichiometry, silicon-rich silicon nitride and nitrogen-doped silicon (called NIDOS) depositions are obtained and compressive to tensile stresses are reported. A maximum in compressive stress is put into evidence for N/Si ratio roughly equal to 0.7 and is related to the cumulated effects of silicon nitridation and crystallization, characterizing the transition between nitrogen-doped silicon and silicon-rich silicon nitride. Finally, by consid...

E. Saint-Etienne

Papers

Residual stress in low pressure chemical vapor deposition SiNx films deposited from silane and ammonia