Abstract: A Thermal type fluid flow sensor comprises a heating resistor formed on a thin film of a substrate, and plural thermal sensitive resistors configuring a bridge circuit. The thermal sensitive resistors are disposed on the thin film of the substrate so as to be located on an adjacent upstream side and an adjacent downstream side of the heating resistor in a stream direction of fluid to be measured. Resistor traces for the thermal sensitive resistors are formed so that the respective thermal sensitive resistors exhibit substantially equal changes in resistance with each other to distortion caused in the thin film.

Abstract: A gas flowmeter capable of reducing a secular change comprises a silicon semiconductor substrate formed with a cavity and a heat element formed above the cavity of the semiconductor substrate by way of an insulating film. The heat element is a silicon (Si) semiconductor thin film impurity-doped at high concentration. Stoichiometrically stable silicon nitride (Si3N4) thin films as barrier layers which less permeate and less absorb hydrogen in the heat generating temperature range of the heat element are formed above and below the silicon (Si) semiconductor thin film.

Abstract: A thermal flow sensor which is fabricated at a low cost and has improved reliability. Over a cavity (7) formed in a semiconductor substrate (2), at least a heating resistance (4) is formed near the center of the cavity with an electrical insulation film interposed between the heating resistance and the cavity. The temperature (Th) of the heating resistance (4) is controlled to be higher than the medium temperature (Ta) by a constant temperature (?Th=Th?Ta). A distance (Ws) in the direction of airflow from an upstream end of the heating resistance (4) to an upstream end of the electrical insulation film lying over the cavity and the constant temperature (?Th) satisfy the following relationship: ?Th/Ws?800 (° C./mm) Thus, a thermal flow sensor is provided which can prevent deposition of floating fine particles, such as carbon particles, caused by the thermophoretic effect, can be fabricated at a low cost, and has high reliability.

Abstract: A semiconductor laser diode comprises: an n-type GaAs substrate; and a first laser diode structure having a first n-type cladding layer, a first active layer including a quantum well layer, a first p-type cladding layer on the first active layer, a p-type signal layer on the first p-type cladding layer and which has the same constituent elements as those of the first p-type cladding layer, and a p-type ridge waveguide in a stripe mesa-like shape on the signal layer, which has the same constituent elements as those of the signal layer, and in which composition ratios of two constituent elements in a complementary relation of constituent elements are different from those composition ratios of the signal layer.

Abstract: A thermal type flow measuring apparatus includes a heating resistor provided in a thin part of a substrate and a bridge circuit for driving the heating resistor to have a preset heating temperature, wherein resistor elements on sides forming the bridge circuit are temperature sensitive resistors, a part or whole of at least one of the temperature sensitive resistors is placed in the thin part and near the heating resistor so that the temperature sensitive resistor is influenced by a heat of the heating resistor, and the preset heating temperature is increased as the flow of fluid is increased. This configuration introduces flow dependency into the heating temperature of the heating resistor.

Abstract: A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Abstract: A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Abstract: A low reflective film is formed of, in sequence from a side in contact with a laser chip, a first dielectric film of a refractive index n1 and a thickness d1, a second dielectric film of a refractive index n2 and a thickness d2, a third dielectric film of a refractive index n3 and a thickness d3, and a fourth dielectric film of a refractive index n4 and a thickness d4, specifically, aluminum oxide Al2O3 with a refractive index n1=1.638 is used for the first dielectric film, silicon oxide SiO2 with a refractive index n2=n4=1.489 for the second and fourth dielectric films, tantalum oxide Ta2O5 with a refractive index n3=2.063 for the third dielectric film, respectively, resulting in a semiconductor laser device with a reflectance which is stably controllable.

Abstract: A thermal flow sensor which is fabricated at a low cost and has improved reliability. Over a cavity (7) formed in a semiconductor substrate (2), at least a heating resistance (4) is formed near the center of the cavity with an electrical insulation film interposed between the heating resistance and the cavity. The temperature (Th) of the heating resistance (4) is controlled to be higher than the medium temperature (Ta) by a constant temperature ({Th=Th?Ta). A distance (Ws) in the direction of airflow from an upstream end of the heating resistance (4) to an upstream end of the electrical insulation film lying over the cavity and the constant temperature (?Th) satisfy the following relationship: ?Th/Ws?800 (° C./mm) Thus, a thermal flow sensor is provided which can prevent deposition of floating fine particles, such as carbon particles, caused by the thermophoretic effect, can be fabricated at a low cost, and has high reliability.

Abstract: There is provided a flow rate measuring device which comprises a means for introducing a backward flow of the main passage into the sub-passage through the outlet of the sub-passage of the flow rate measuring device is provided near the outlet of the sub-passage, in order to keep the flow rate measuring element from being destroyed under the presence of dust and water in an intake manifold and which has high reliability for a long period of use and an excellent pulsation characteristic.

Abstract: A Thermal type fluid flow sensor comprises a heating resistor formed on a thin film of a substrate, and plural thermal sensitive resistors configuring a bridge circuit. The thermal sensitive resistors are disposed on the thin film of the substrate so as to be located on an adjacent upstream side and an adjacent downstream side of the heating resistor in a stream direction of fluid to be measured. Resistor traces for the thermal sensitive resistors are formed so that the respective thermal sensitive resistors exhibit substantially equal changes in resistance with each other to distortion caused in the thin film.

Abstract: A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Abstract: A semiconductor laser device has a front surface electrode formed by Au plating, a rear surface electrode formed by Au plating, an anti-adhesive film only on the front surface electrode and made of a material that does not react with Au, and a coating film that covers an end face on a light emitting side and an end face opposite the light emitting side. The anti-adhesive films are located on the four corners of the front surface electrode.

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: A thermal type flow measuring device comprises a heating resistor(HF), a temperature measuring resistor(Ru) upstream of the heating resistor(HF) with respect to a fluid(Q), and a temperature measuring resistor(Rd) downstream of the heating resistor(HF). A heat sensitive resistance element(CF), the upstream temperature measuring resistor(Ru) and the downstream temperature measuring resistor(Rd) form a first bridge circuit, and this first bridge circuit and the heating resistor(HF) form a second bridge circuit. Feedback control means(OP1, Tr) heat the heating resistor(HF) in accordance with an output for keeping a balance of the second bridge circuit.

Abstract: A gas flowmeter capable of reducing a secular change comprises a silicon semiconductor substrate formed with a cavity and a heat element formed above the cavity of the semiconductor substrate by way of an insulating film. The heat element is a silicon (Si) semiconductor thin film impurity-doped at high concentration. Stoichiometrically stable silicon nitride (Si3N4) thin films as barrier layers which less permeate and less absorb hydrogen in the heat generating temperature range of the heat element are formed above and below the silicon (Si) semiconductor thin film.

Abstract: A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Abstract: A gas flowmeter capable of reducing a secular change comprises a silicon semiconductor substrate formed with a cavity and a heat element formed above the cavity of the semiconductor substrate by way of an insulating film. The heat element is a silicon (Si) semiconductor thin film impurity-doped at high concentration. Stoichiometrically stable silicon nitride (Si3N4) thin films as barrier layers which less permeate and less absorb hydrogen in the heat generating temperature range of the heat element are formed above and below the silicon (Si) semiconductor thin film.

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.