Improvement In Temperature Coefficient Research Articles

Dual-Mode AlN-on-Silicon Micromechanical Resonators for Temperature Sensing

In this paper, we present dual-mode (DM) AlN-on-silicon micromechanical resonators for self-temperature sensing. In-plane width-shear (WS) and width-extensional (WE) modes of [110]-oriented silicon resonators have been used as alternatives to first- and third-order modes to enhance DM temperature sensitivity by engineering device geometry, which reduces inherent beat frequency f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> between the two modes. This configuration provides a 50× improvement in temperature coefficient of beat frequency (TCf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> ) compared with single-mode temperature measurement and eliminates the need for additional frequency multipliers to generate f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> from its constituents. [100]-oriented WS/WE resonators provide 4× larger TCF difference between modes (ΔTCF) than first and third width-extensional resonators, which further contributes to TCf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> enhancement. WS/WE mode resonators also demonstrate the capability of operating as a temperature-stable reference f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> . The proposed modes for DM operation have high Q and low motional resistance, and are 180 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> out-of-phase when operated in two-port configuration, thus enabling mode-selective low-power oscillator interfacing for resonant temperature sensing.

Improvement of Temperature Coefficient of Resistance by Co-Implantation of Argon or Xenon or Fluorine in Boron Implanted Polysilicon Resistors

This paper proposes a new method to decrease the absolute value of temperature coefficient of resistance (TCR) in P-type boron implanted polysilicon resistors, at a given intermediate sheet resistance values, by selecting an optimized combination of boron doping implant conditions with co-implantation conditions. The co-implantation ion species that were investigated are fluorine, argon and xenon. Each of the co-implantation species was studied at three different co-implantation conditions and two different boron doping implant conditions of dose and energy. The stopping and range of ions in matter (SRIM) Monte Carlo simulation and thermawave measurements were used in order to set the experimental conditions and to evaluate the crystal damage and the amorphous layer depth created by the co-implantation. Amorphous layer is defined in this work as highly disordered material with vacancies concentration above 10% of the crystal density. Electrical measurements show that co-implantation causes a remarkable change in sheet resistance and TCR. Deeper co-implanted amorphous layer increases TCR and decreases sheet resistance. Typical polysilicon TCR is negative, while the TCR of a single crystal is positive. An improvement of TCR is defined at this work as minimum TCR in absolute values, which is lower sensitivity of sheet resistance to operational temperatures. Co-implantation that created deep amorphous layer in the polysilicon, decreases the TCR absolute values by up to ~75 % at the lower boron doping implant samples. Deep co-implanted amorphous layer also decreases sheet resistance by up to ~40% in both of the boron doping implants. Co-implanted xenon and fluorine exhibit similar effect on sheet resistance and TCR, while the co-implanted argon effect is weaker in comparison to samples without co-implantation. The increase of TCR and the decrease of sheet resistance are attributed to grains regrowth during the rapid thermal anneal (RTP). The regrowth of the co-implanted amorphous layer creates larger grains with less grain boundaries and less defects in comparison to the polysilicon samples without co-implantation. Analysis by X-ray diffractometer (XRD) and atomic force microscope (AFM) supports the suggested model.

Ar-O&lt;SUB&gt;2&lt;/SUB&gt;混合ガス雰囲気下でSiO&lt;SUB&gt;2&lt;/SUB&gt;/Al&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;3&lt;/SUB&gt;基板上に作製されたPt/Ti薄膜の組織と抵抗温度係数の改善

Ar-O&lt;SUB&gt;2&lt;/SUB&gt;混合ガス雰囲気下でSiO&lt;SUB&gt;2&lt;/SUB&gt;/Al&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;3&lt;/SUB&gt;基板上に作製されたPt/Ti薄膜の組織と抵抗温度係数の改善

The Improvement of Temperature Coefficient of Frequency in Thin Film Bulk Acoustic Wave Resonator using Secondary Harmonics

ABSTRACTWe have succeeded in making an 870MHz-range thin film bulk acoustic wave (BAW) resonator that has a small temperature coefficient of frequency (TCF) using secondary harmonics. The 870MHz-range BAW resonator has been requested to have nearly zero TCF, because it will be used in an oscillator for remote keyless entry systems. The BAW resonator has composite structure that consists of Al electrodes and ZnO/SiO2. We directed our attention to the fact that ZnO and Al have negative TCF, and SiO2 has a positive one. It is theoretically possible to make zero TCF BAW resonators by optimizing the thickness ratio of ZnO and SiO2. However, using fundamental resonance, TCF is so sensitive to the thickness ratio that it cannot be easily controlled by MEMS techniques. We founds in finite element method simulation and confirmed by experiment that the TCF of secondary harmonics has a local minimum when changing the ZnO/SiO2 thickness ratio. As the result, a nearly zero TCF resonator without strict control of ZnO/SiO2 thickness ratio has been realized by adopting Al/ZnO/SiO2/ZnO/Al/SiO2 structure and combining thermal oxidized Si and sputtered SiO2. The resonator has the TCF of -1.86ppm/degree in the range of −40 to 85 degrees centigrade.

ゼナーダイオードを用いた基準電圧の温度係数の改善

ゼナーダイオードを用いた基準電圧の温度係数の改善