Showing papers on "Microheater published in 1998"

Realization and performance of thin SiO2/SiNx membrane for microheater applications

Abstract: There is considerable interest in thin-film microheaters for decreasing the power consumption in portable applications. In this paper, we present the study of new stacked thin membranes (SiO 2 /SiN 1.2 ) supporting the heating element (polysilicon resistor). The great interest of using SiN 1.2 deposited onto a SiO 2 layer is the improvement in mechanical properties of the membrane, leading to a fabrication yield very close to 100%. Microheaters fabricated with a 1.6 mm × 1.6 mm square and 0.7 μm thick SiO 2 /SiN 1.2 membrane give promising results in terms of power consumption; 230°C is reached with an electrical power of 50 mW.

Characteristics of Ceramic Microheater for Fiber Coupler Fabrication

Abstract: Properties of a microheater have been greatly improved for use in fused-tapered fiber coupler fabrication by employing a ceramic heat source. Lanthanum chromite was adopted as a heat source because it has the highest melting point for the use in air and can be used without cooling equipment. The usual susceptibility to heat shock exhibited by ceramic heaters was essentially overcome by miniaturizing the structure so that it could handle quick temperature changes during fiber coupler fabrication. The microheater was typically only 22 mm long which helps shorten the fiber coupler length. The lifetime of the microheater was about 1500 h at 1530°C. This is more than 100 times that of the previously developed precious metal microheater. There was only a slight change in the temperature distribution along the heater with heating time. 1.31/1.55-µm wavelength-division-multiplexing (WDM) couplers were fabricated during the lifetime test and it was confirmed that the coupling properties could be very well controlled even after the test.

Hot wire type microheater

Abstract: PROBLEM TO BE SOLVED: To provide a hot wire type microheater having a durability enough against a high temp. of about 500°C in operation. SOLUTION: The hot wire type microheater formed by the semiconductor microprocessing technology is composed of an Si substrate 10, SiO2 insulation film 11 formed on the top face of the Si substrate 10, heater 12 provided on the insulation film 11, first SiO2 protective film 13 covering the surface including the heater 12, Si3N4 reinforced part 14 located above the heater for suppressing the displacement of the heater, and heat insulating cavity 16. According to the hot wire type microheater, it is possible to obtain a hot wire type microheater which has a high durability and allows the working time to be greatly prolonged, compared with the hot wire type microheater in prior art. COPYRIGHT: (C)2000,JPO

Fabrication of the Pt microheater using aluminum oxide as a medium layer and its characteristics

Abstract: The electrical and physical characteristics of aluminum oxide films, onto which Pt thin films are deposited by reactive sputtering and DC magnetron sputtering, respectively, were analyzed by increasing the annealing temperature (400 ∼ 800°C) by a four-point probe method and by SEM and XRD. Below the annealing temperature of 600°C, aluminum oxide films improved Pt adhesion to silicon thermal oxide films and acted as insulators without chemically reacting with Pt thin films. Also, the resistivity of Pt thin films was improved. However, these properties of aluminum oxide films with deposited Pt thin films were degraded at annealing temperatures above 600°C because aluminum oxide films were changed into aluminum metal which reacted with the deposited Pt thin films. The thermal characteristics of Pt microheaters were analyzed using Pt-RTD temperature sensors integrated on the same substrates. In the analyses of the properties of the Pt microheater, a Pt microheater with the smaller active area had better thermal characteristics. The temperature of the Pt microheater with an active area of 200 μm x 200 μm was 400°C with a heating power of 1.5 W.

Evaporating source for organic material

Abstract: PROBLEM TO BE SOLVED: To provide an easily treatable evaporating source for an organic material capable of executing uniform heating at a certain temp. to various organic evaporating materials, particularly, to liq. organic evaporating materials. SOLUTION: A vessel 3 for evaporation housing an organic compound monomer 2 and a heating medium source 4 controlling the temp. of a heating medium 40 in a heating medium tank 45 to a prescribed one are provided. The vessel 3 for evaporation is composed of a housing part 30 housing the organic compound monomer 2 and a heating medium holding part 31 provided so as to surround the vicinity of the housing part 30, and a heating medium circulating path 32 is formed by the space between the housing part 30 and the heating medium holding part 31. The heating medium 40 is introduced into the heating medium circulating path 32 from the heating medium source 4 and is circulated, and the organic compound monomer 2 in the housing part 30 is heated and cooled. A microheater 62 for heating the organic compound monomer 2 to a temp. higher than that in the vessel 2 for evaporation is wound around the heating medium holding part 31.

CMOS MEMS technology and CAD: the case of thermal microtransducers

Abstract: Thermally-based transducer microsystems can be made by using CMOS IC technology, post-CMOS micromachining or deposition, and flip-chip packaging. Technology steps, materials, and physical effects pertinent to thermal microtransducers are summarized together with microheater, thermistor, thermopile, thermal isolation, and heat sink structures. An infrared intrusion detector, a thermal air flow sensor, and thermally excited microresonators for acoustic and chemical sensing serve as demonstrators. We discuss the characterization of process-dependent properties of CMOS materials crucial for thermal microtransducer CAD.

Microheater, flow pate sensor, and humidity sensor

Abstract: PROBLEM TO BE SOLVED: To provide a microheater that, when used with various sensors, can reduce the power consumed, without decreasing their detecting accuracy SOLUTION: At the rise time of a constant current pulse, a constant current source, which intermittently passes constant current pulses in order to raise the temperature of a resistor to a certain target temperature, supplies a current [current waveform 1] which is given the overshoot A of a current value for a certain time, so that the heat response time τ1 for the resistor temperature to reach the target temperature is reduced, with the result that the current- carrying time required for intermittent drive can be reduced, and since the intermittent drive can be achieved without hindrance, the power consumed can be reduced At the same time, since the pulses are not made shorter than the heat response time τ1 and the detecting action of a sensor is performed while it carries the constant current pulses attained by the proper current value, detecting accuracy as a sensor is not deteriorated

Silicon carbide microheater

Abstract: Using a silicon carbide meander on a dielectric substrate as a basis, we have made SiC microheaters, from 10 to 1000 microns in size, which are long-term operable in air with the heater unit temperature above 1000/spl deg/C. The use of a membrane in the microheater design has made it possible to essentially reduce the power consumption and improve persistence properties.

Ink jet head and thermal actuator

Abstract: PROBLEM TO BE SOLVED: To widen the scope of free selection of an ink by structuring an actuator means in such a way that the energy for discharging ink droplets by deformation due to thermal expansion is generated, in a device for discharging ink droplets by pressurizing the ink of an ink liquid chamber with the help of the actuator means. SOLUTION: Electricity is fed to a microheater 5 of an actuator means 6 through electrode parts 7, 8 to heat he microheater 5 at about 200°C. Consequently, a mechanical shape change occurs based on the difference in a coefficient of heat expansion between an Ni-Cr coating film 4 and an SiO 2 coating film 2 which form the microheater 5. That is, the actuator means 6 is deformed in such a manner that it protrudes to the higher value side of the coefficient of heat expansion (the microheater 5 side). As a result, an ink in an ink liquid chamber 10 is pressurized to discharge ink droplets 16 from a nozzle 13. When this kind of actuator means 6 is used, it is possible to control the amount of the ink droplets 16 to an optimal level by controlling the degree (temperature) of heating and therefore, solve the problem of kogation (scorching). COPYRIGHT: (C)1999,JPO

A Novel Cold-Wall MOCVD Method for Fabrication of a Durable Micro-Machined SnO 2 Gas Sensor.

Abstract: A novel cold-wall metal organic chemical vapor deposition (MOCVD) method has been developed to fabricate a durable micro-machined SnO 2 thin-film gas sensor. Instead of using a hot plate or a heater around a reactor, a microheater fabricated using micromachining technology is put into the reactor and used as the heat source for thermal decomposition of the metal organic source. Since SnO 2 film is selectively deposited on the microheater using this method, no patterning process for the SnO 2 film is necessary. Moreover, the durability of the sensor fabricated using this method (N-sensor) is considerably improved compared with that of a sensor fabricated by a conventional hot-wall MOCVD method (C-sensor). The N-sensor outlasted over seven million heat cycles (500°C for 100 ms and room temperature for 100 ms), while the C-sensors were broken after a few hundred thousand heat cycles. Although the N-sensor demonstrated excellent durability, its sensitivity for methane gas was low. However, the sensitivity of the method may be improved by optimizing the deposition conditions.

Thermal Characteristics of Microheater for Gas Sensors

Abstract: Using the results analyzed by FEM(Finite Element Method). the microheaters with the stress-balanced (150 nm)/(300 nm)/(150 nm) diaphragms were fabricated by silicon micromachining techniques. Pt was used as microheater materials. Pt temperature sensor was fabricated to measure the temperature of microheaters. Resistance of temperature sensor and power dissipation of microheater were measured and calculated at the various temperatures. The thermal distribution of heater was examined by a IR thermoviewer. Measured and simulated results are compared and analyzed. The temperature coefficient of resistance of heater was about . Pt heater showed the power dissipation of about 51 mW at and a uniform thermal distribution on the surface.