Microheater

About: Microheater is a research topic. Over the lifetime, 814 publications have been published within this topic receiving 12478 citations.

Study of the annealing effect of low-temperature oxide on the etch rate in TMAH solutions for micro-heater applications

Abstract: Suspended structures are frequently used in some micro-electro-mechanical system (MEMS) devices. They are usually protected and supported by silicon oxide. Because the suspended structures are released from the silicon substrate in various etchants, the etch resistivity of the oxide layer is very important for suspended structure fabrication. In this paper, we improve the etch resistivity of low temperature chemical vapor deposition (CVD) silicon oxide layers by using annealing process to substitute thermal oxide grown in a high-temperature and high-cleanness furnace. We prepared thermal oxide and CVD oxide samples and then measured the etch rates after tetramethyl ammonium hydroxide (TMAH) anisotropic etching process and dry etch process. According to the experiment data, we found that the etch rates of CVD oxide were slightly decreased in dry etch and obviously decreased in TMAH solution. The etch rates of 600 °C annealed TEOS based oxide and 600 °C annealed SiH4 based oxide in 25 wt.% TMAH at 80 °C are 1.1 and 0.7 A/min respectively. The etch resistivity of CVD oxide can compete the etch resistivity of thermal oxide when annealing temperature is up to 600 °C. The stress characteristics of annealed oxide layer were also measured in this paper. The stress has a minimum value at 600 °C annealing temperature. In our work, a single crystalline silicon heater was successfully completed by using annealed CVD oxide as passivation layer. The heater with a resistance of 200 ohms glowed as bias current is up to 38 mA. We also simulated and characterized the temperature distribution of the microheater. The ANSYS simulation shows the central temperature of the microheater is 1135 °C as the bias power is 0.59 W.

High Sensitivity and Power Efficient Heater Structure for Bulk Micromachined Thermal Accelerometer

Abstract: In MEMS based thermal convective accelerometers, the structure of the constituent microheater plays a crucial role in determining the sensitivity of the accelerometer. This paper reports the sensitivity improvement of a dual axis thermal accelerometer using a cross shaped heater structure. In a conventional heater design, the peak heater temperature generated at the center of the cavity offers lower temperature gradient at the position of the temperature sensors situated afar. As a result, the sensitivity obtainable from the thermal accelerometer becomes low. The sensitivity can be improved by generating the peak temperature at the side arms which are used to suspend the heater structure. This has been accomplished in this work using a cross shaped heater where the peak temperature is generated at the cross arms of the heater. Hence, the temperature gradient is higher near the temperature sensors, leading to improved sensitivity of the accelerometer. The sensitivity achieved using such a cross shaped heater is 0.36 K/g at a peak heater temperature of 615 K and having power requirement of 29.6 mW. The proposed heater structure can also be employed in other microsystem devices like gyroscope and thermal flow sensor for improving their performance.

Modeling and simulation of nichrome microheater on polycarbonate substrate

Abstract: This paper presents the design and simulation of four different structures of nichrome microheater on the polycarbonate substrate. Nichrome layer is covered by the silicon nitride dielectric layer. The comb capacitor covering dielectric layer is used for measuring electrical parameters of liquids. Designed structure allows impedance, resistance and capacitance monitoring of studied substances like chemical or biological liquids, which require constant heating value on the substrate surface. 3D model design and electro-thermal finite elements simulations were carried out by CoventorWare software. Various shapes of the heaters were studied to check the uniformity heating on the active surface.

Compact tunable photonic crystal nanobeam cavity with low power consumption

Abstract: Methods and devices for a tunable photonic crystal nanobeam cavity are disclosed. Such nanobeam cavity has high Q-factor and can be integrated with a microheater. The resonant wavelength of the cavity can be tuned to attain a high modulation depth with low power consumption.

Extension gate fet sensor

Abstract: PROBLEM TO BE SOLVED: To control catalytic activity according to temperature by using a metal having a performance for decomposing hydrogen or hydrogen compound as a gate electrode. SOLUTION: The thin film of a metal which is a gate electrode 1 is extended and guided onto a microheater 2. On the exposed surface of the electrode 1 extended part formed of the metal in a high temperature part where the heater 2 is present, hydrogen molecule (H2 )or hydrogen compound is decomposed, and the dissociated hydrogen is difused in the electrode 1 to form an electric double layer on the critical surface with a gate insulating film 3 of SiO2 . Thus, the current carried between a source and a drain is modulated, and taken out as a detection signal. A thin diaphragm 5 of SiO2 supported only in the peripheral part can be formed on a silicon base 4, and the heater 2 is arranged thereon, whereby a thermally insulated local high temperature part in which the heat transfer to a FET part is prevented can be formed. A highly sensitive FET sensor capable of controlling the catalytic activity by temperature can be realized.