Abstract: The purpose of the present invention is to provide a highly accurate and highly reliable physical quantity sensor wherein an error due to stress applied to a sensor element of the physical quantity sensor is reduced. This physical quantity sensor device is provided with: a hollow section formed in a Si substrate; an insulating film covering the hollow section; and a heating section formed in the insulating film. The sensor device is also provided with a detection element that detects the temperature of the insulating film above the hollow section, the detection element is provided with a first silicon element and a second silicon element, and the first silicon element and the second silicon element are doped with different impurities, respectively.

Abstract: Degradation of reliability of a thermal fluid flow sensor, caused by generation of a crack in an insulating film is prevented in the thermal fluid flow sensor including a detection section and a circuit section formed on the same substrate when stress adjustment is performed by forming a deep concave portion in an interlayer insulating film in the detection section and forming the insulating film having a tensile stress thereon. As a means thereof, stair-like step is provided in a side wall of a concave portion, formed in the interlayer insulating film on a diaphragm. Accordingly, each depth of a first concave portion and a second concave portion, which form the concave portion, is reduced, and coatability of the insulating film for the stress adjustment, which covers a side wall and a bottom face of the concave portion, is improved.

Abstract: A thermal air flow sensor that produces less measurement error is provided. The thermal air flow sensor includes: a semiconductor substrate; a heating resistor, resistance temperature detectors, and an electrical insulator that includes a silicon oxide film, wherein the heating resistor, the resistance temperature detectors, and the electrical insulator are formed on the semiconductor substrate; and a diaphragm portion formed by removing a portion of the semiconductor substrate. The heating resistor and the resistance temperature detectors are formed on the diaphragm portion. The thermal air flow sensor further includes a silicon nitride film formed as the electrical insulator above the heating resistor and the resistance temperature detectors. The silicon nitride film has steps conforming to the patterns of the heating resistor and the resistance temperature detectors. The silicon nitride film has a multilayer structure.

Abstract: A thermal air flow sensor that produces less measurement error is provided. The thermal air flow sensor includes: a semiconductor substrate; a heating resistor, resistance temperature detectors, and an electrical insulator that includes a silicon oxide film, wherein the heating resistor, the resistance temperature detectors, and the electrical insulator are formed on the semiconductor substrate; and a diaphragm portion formed by removing a portion of the semiconductor substrate. The heating resistor and the resistance temperature detectors are formed on the diaphragm portion. The thermal air flow sensor further includes a silicon nitride film formed as the electrical insulator above the heating resistor and the resistance temperature detectors. The silicon nitride film has steps conforming to the patterns of the heating resistor and the resistance temperature detectors. The silicon nitride film has a multilayer structure.

Abstract: The purpose of the present invention is to provide a thermal flow-rate sensor that is capable of self-diagnosis. Provided is a thermal flow-rate sensor provided with a semiconductor element that detects a flow rate and that is equipped with electrode pads for electrical conduction with the outside, wherein at least two of the electrode pads are provided, and other electrode pads proximate to the electrode pads are arranged and have an electric potential beyond the scope of output to be used at the time of flow rate detection.

Abstract: A thermal air flow sensor that offers high flow rate measurement accuracy is provided. The thermal air flow sensor includes a measuring element. The measuring element includes: a semiconductor substrate; a heating resistor and a temperature measuring resistor both formed as a result of thin films being stacked over the semiconductor substrate; an electronic insulator including a silicon oxide film; and a diaphragm portion formed after part of the semiconductor substrate is removed. The heating resistor and the temperature measuring resistor are formed over the diaphragm portion. In the thermal air flow sensor, a ratio of an area occupied by the thin films to an area of the measuring element ranges between 40% and 60%.

Abstract: In order to provide a thermal mass flowmeter which makes higher accuracy of gas flowrate measurement possible while reliability in the thermal mass flowmeter is ensured (while deterioration or breakage caused by droplet adhesion is prevented), the thermal mass flowmeter according to the present invention has a heating element for generating heat by conduction, a temperature detection bridge circuit for detecting a temperature of the heating element, and a sensor element driving circuit portion connected to the heating element and the temperature detection bridge circuit and executing conduction control to the heating element, in which the sensor element driving circuit portion has an output mechanism and an output impedance adjustment mechanism and the output impedance adjustment mechanism is disposed between the output mechanism and the heating element and its output impedance is higher than an electric resistance value of the heating element and less than 1 M?.

Abstract: In order to prevent deterioration and a breakdown of a sensor element when the sensor element is activated in a state where liquid is attached thereto, and to remove the liquid in a short period of time with lower power consumption, there is provided a gas sensor including a first heating element and a second heating element that is formed around the periphery of the first heating element and has a wider forming area than the first heating element, and measuring a gas amount by heating the first heating element to a predetermined temperature, in which the second heating element is heated when the gas sensor is activated, and the first heating element is heated to the predetermined temperature after a heat value of the first heating element is restricted for a predetermined period of time.

Abstract: A thermal air flow sensor that offers high flow rate measurement accuracy is provided. The thermal air flow sensor includes a measuring element. The measuring element includes: a semiconductor substrate; a heating resistor and a temperature measuring resistor both formed as a result of thin films being stacked over the semiconductor substrate; an electronic insulator including a silicon oxide film; and a diaphragm portion formed after part of the semiconductor substrate is removed. The heating resistor and the temperature measuring resistor are formed over the diaphragm portion. In the thermal air flow sensor, a ratio of an area occupied by the thin films to an area of the measuring element ranges between 40% and 60%.

Abstract: A thermal air flow sensor that produces less measurement error is provided. The thermal air flow sensor includes: a semiconductor substrate; a heating resistor, resistance temperature detectors, and an electrical insulator that includes a silicon oxide film, wherein the heating resistor, the resistance temperature detectors, and the electrical insulator are formed on the semiconductor substrate; and a diaphragm portion formed by removing a portion of the semiconductor substrate. The heating resistor and the resistance temperature detectors are formed on the diaphragm portion. The thermal air flow sensor further includes a silicon nitride film formed as the electrical insulator above the heating resistor and the resistance temperature detectors. The silicon nitride film has steps conforming to the patterns of the heating resistor and the resistance temperature detectors. The silicon nitride film has a multilayer structure.

Abstract: A temperature of the heating resistor is set at a temperature equal to or higher than a temperature, at which liquid droplets contacting a surface of the heating resistor evaporate and disappear by film boiling. Alternatively, when a heating resistance type air flow rate measuring device starts to operate or stops operating, the temperature of the heating resistor may be set at a temperature equal to or higher than the temperature, at which liquid droplets contacting a surface of the heating resistor evaporate and disappear by film boiling. Moreover, a water-repellent and oil-repellent protective coating may be provided on the surface of the heating resistor.

Abstract: A sensor with built-in circuits can be improved in the stability of the operation or characteristics. A circuit region and a sensor region are covered by a passivation film. The sensor region is partially covered by the passivation film. The sensor region and circuit region are protected by the passivation film, and an effect of the passivation film on the mechanical displacement of a diaphragm portion can be alleviated so that the sensor with built-in circuits may be improved in the stability of the operation or characteristics.

Abstract: The object of the present invention is to propose an etch channel sealing structure characterized by excellent impermeability to moisture and resistance to temporal change of the diaphragm in the pressure sensor produced according to the sacrificial layer etching technique, and to provide a pressure sensor characterized by excellent productivity and durability. After a very small gap is formed by the sacrificial layer etching technique, silicon oxide film is deposited by the CVD technique or the like, there by sealing the etch channel. Further, impermeable thin film of polysilicon or the like is formed to cover the oxide film. This allows an etch channel sealing structure to be simplified in the pressure sensor produced according to the sacrificial layer etching technique, and prevents entry of moisture into the cavity, thereby improving moisture resistance. Moreover, sealing material with small film stress reduces temporal deformation of the diaphragm.

Abstract: The object of the present invention is to propose an etch channel sealing structure characterized by excellent impermeability to moisture and resistance to temporal change of the diaphragm in the pressure sensor produced according to the sacrificial layer etching technique, and to provide a pressure sensor characterized by excellent productivity and durability. After a very small gap is formed by the sacrificial layer etching technique, silicon oxide film is deposited by the CVD technique or the like, thereby sealing the etch channel. Further, impermeable thin film of polysilicon or the like is formed to cover the oxide film. This allows an etch channel sealing structure to be simplified in the pressure sensor produced according to the sacrificial layer etching technique, and prevents entry of moisture into the cavity, thereby improving moisture resistance. Moreover, sealing material with small film stress reduces temporal deformation of the diaphragm.

Abstract: By sealing a diaphragm with less processes and lower cost and reducing deformation due to remaining stress, a stable and highly reliable pressure sensor construction is proposed. The pressure sensor is low in measurement error and small in floating capacitance and leakage current and good in characteristic. As a means to attain the above object, a polycrystalline silicon diaphragm is sealed with a silicon oxide film deposited through a LPCVD method and then completely covered. The diaphragm is placed on a surface of a semiconductor substrate with a nearly constant gap of 0.15 to 1.3 ?m, and has difference-in-grade constructions of a deformation reducing means due to remaining stress.

Abstract: A semiconductor device for producing a movable section by using the sacrifice etching technique, wherein in order to prevent the sticking of the movable section during the sacrifice layer etching process, the movable section is formed with a reinforcing layer before the sacrifice layer etching process to temporarily increase the rigidity of the movable section, the reinforcing layer being removed after completion of the sacrifice layer etching process. The semiconductor device solves the problem of sticking of the movable section without increasing the rigidity of the movable section more than necessary, and is high in yield.

Abstract: A pressure sensor of electric capacitance type which includes a plurality of pressure sensor units connected in parallel with one another and each formed on a substrate by an electrode, a cavity region and a diaphragm having an electrically conductive film which is disposed in opposition to the electrode with the cavity region intervening between the electrode and the diaphragm, wherein diaphragm fixing portions are disposed internally of the cavity region so that a single sheet of the diaphragm is partitionarily and regionally allotted to regions of the plural pressure sensor units, respectively. With this structure of the capacitance-type pressure sensor, ineffective region for capacitance detection is minimized and hence the parasitic capacitance can be reduced with the detection accuracy of the sensor being improved.

Abstract: A high-accuracy high-stability capacitor type pressure sensor which eliminates a parasitic capacitance between a reference capacitor and a semiconductor substrate. A capacitor type pressure sensor comprising, on a semiconductor substrate 10, an active capacitor 100 whose capacitance varies as the surrounding pressure varies, a reference capacitor 200 whose capacitance will not vary substantially as the surrounding pressure varies, and a circuit which is electrically connected to both said active and reference capacitors 100 and 200, detects the difference or ratio thereof, and uses the potential of a semiconductor substrate, wherein an electrode 30a of said reference capacitor is formed on the semiconductor substrate 10 with a dielectric 20 therebetween.

Abstract: By sealing a diaphragm with less processes and lower cost and reducing deformation due to remaining stress, a stable and highly reliable pressure sensor construction is proposed. The pressure sensor is low in measurement error and small in floating capacitance and leakage current and good in characteristic. As a means to attain the above object, a polycrystalline silicon diaphragm is sealed with a silicon oxide film deposited through a LPCVD method and then completely covered. The diaphragm is placed on a surface of a semiconductor substrate with a nearly constant gap of 0.15 to 1.3 &mgr;m, and has difference-in-grade constructions of a deformation reducing means due to remaining stress.