TWI247099B - Stable high temperature sensor/heater system and method with tungsten on AlN - Google Patents

Abstract

A sensor system has an AlN substrate (4), a W layer (2) on the substrate, a signal source (70) adapted to apply an electrical actuating signal to the W layer, and a sensor (72) adapted to sense the response of the W layer. The W layer can comprise a thin film, with various types of optional protective layers (12) over the film. Applications include sensing temperature, fluid flow rates, fluid levels, pressure and chemical environments. For a planar heater, the W layer comprises a plurality of conductive strands (34) distributed on the substrate, with the strands generally parallel and serpentine shaped for a rectangular substrate (32), and extending along respective lines of longitude (40) that merge at opposite poles (44) of the substrate for a circular substrate (42).

Description

1247099 IX. DESCRIPTION OF THE INVENTION: FIELD OF THE INVENTION The present invention relates to sensing systems suitable for high temperature applications, and more particularly to the use of tungsten as a sensing and/or heating element on an A1N substrate. [Prior Art] Continuously looking for improvements in the capabilities of various types of sensing and planar heating systems such as sensing temperature, fluid flow rate and level, pressure and gas environment systems, self-testing planar heaters and high speed uniform heaters . Features that have been identified to be enhanced include faster response times, greater sensitivity, higher temperature capabilities, and lower offset. Temperature measurement devices such as sensors are generally classified into six categories (ICs); (2) pyrometers; (3) resistance temperature detectors (rti nodes; (5) thermocouples (TCs); (6) Electric machinery and volume: (1) integrated circuit

The electrical input (such as current) to the TC junction, but does require electrical input to maintain the reference junction. EMVs include devices such as metal coils and metal strips, tubes of measured volume, and spherical thermometers that use metal/fluid expansion/contraction to measure temperature. Flow Rate and Fluid Level The precise flow rate monitoring and control of the gas is accomplished by temperature sensors (usually RTDs) in devices known as mass flow controllers. In the "replacement', a portion of the total airflow is fed around the main flow path. The gas is heated as it passes through the alternate path. Under normal pressure, each gas has a depleted and only hot valley. Thus, the difference in temperature between 2 to 4/JEL degrees of sensing in series along the alternate flow path can be used to measure and control the gas flow rate through the device. Applications include all methods that require precise control, such as semiconductor wafer fabrication. For a single flow sensing or a fluid level sensor, the thermal capacity of the surrounding environment is characterized by its composition, state (gaseous or liquid), density, and rate of flow through the sensor. The self-heating temperature sensor at a known location in the bit slot indicates that the tank is injected below or above the sensor location or indicates the flow rate of gas/fluid passing therethrough. Pressure Sensor The most common pressure sensor associated with the present invention is a thermocouple (10) barometer. The pressure between the atmospheric pressure readings in the vacuum system was measured using TC air pressure. However, @' is limited in its sensitivity to surface temperature changes from pressure changes and its high temperature capability. Planar heaters Planar heaters can be applied to all areas except the edge of a substrate. 93277.doc -6 - 1247099

Thermocouples on Ceramics” Page 62: Pt is deposited on A1N grains relative to PtRh films for use as thin film thermocouples (TCs). The offset of TC binding relative to temperature (to 1500 ° C) is discussed. ISHM '91 Journal of Υ·Η. Chiao et al.''Interfacial Bonding in Brazed and Cofired Aluminum Nitride pp. 460-480: discusses the reaction for connecting interfaces between AIN and several metals including W and Connection method (steaming or cofiring) comparison. A multilayer A1N/W structure is disclosed in which interface connections are formed due to interlocking grain boundaries. Although not disclosed herein, such a structure has been used as a heater, but it does not have any mechanism for sensing the actual temperature. Patent No. 6,084,221: discusses silver and silver alloys on A1N for planar heater applications. Patent Case No. 6, 103, 146: Will it be promoted by people 11, and people? Bu? A thick film, screenable printed circuit consisting of a conductive paste composition of a mixture of 1 and 1 〇1 and an alloy is applied directly to the surface of an A1N substrate. Patent No. 6,242,719: The thick film is described as being by chemical vapor phase Deposition and deposition on A1N. Patent No. 6,239,432 issued on May 29, 2001 in the name of the inventor of the present invention: a SiC comprising a conductive assembly layer including \¥, boundary (:, \¥2€) The IR absorbing body is electrically connected and mechanically connected to an A1N substrate. SUMMARY OF THE INVENTION The present invention seeks to provide a faster response time, greater sensitivity, higher temperature capability, and lower offset than previous sensing systems. A novel sensing system and method. 93277.doc -8- 1247099 s In the preferred embodiment, a tungsten thin film layer is provided over an A1N substrate, and a pair of tungsten layers are applied to apply an electrical actuation signal. a signal source and a sensor that senses the response of the tungsten layer to the actuation signal. A different oxidation protection layer may be provided on the tungsten layer, the protective layer comprising gold, Au_pt, gold (on the alloy Depending on the case of tungsten or B2〇rSiQ2 layer) or p - a layer of 32 〇 3_81 卩 2 on the Pt.). An A1N cover may also be provided on the protective layer. ' In a preferred embodiment, the tungsten layer is distributed on a planar A1N substrate. a plurality of conductive lines. For a shape of a substrate such as a rectangle, the material lines are preferably formed and parallel. For a circular substrate, the lines are preferably/exposed to each other and extend over the substrate. The opposite pole is merged. When the 'A1N substrate crane is preferred, the invention can be summarized as an aw substrate and a conductive layer on the substrate, the conductive layer having a substrate on a predetermined temperature operating range. a coefficient of expansion within 1 〇〇 〇〇 〇〇 7 and which does not substantially react with the substrate and generally exhibits no solid solubility or interdiffusion with the substrate. It can also be summarized as an insulating substrate and The use of a tungsten-conducting layer on the substrate, the conductive layer having an expansion coefficient within 1.00+/_0 07 of the substrate within a predetermined temperature operating range, and which substantially does not react with the substrate and substantially Demonstrate no solid solubility with the substrate Interdiffusion. Applications for the material system include: a planar heater that can self-measure its own temperature, use only a single W/A1N component, or use a pair of such components spaced in the fluid flow path ( Fluid flow rate for heating one element, the other element is not heated and both sense the temperature of the fluid at its respective position 93277.doc -9 - 1247099 Sensor, fluid that can sense whether it is immersed in a predetermined fluid Level sensing 15' is a pressure sensor in which the voltage/current relationship of the sensor is related to ambient gas pressure and a chemical sensor for an environment in which the tungsten layer is subject to environmental changes to change its response characteristics. These and other features and advantages of the present invention will become apparent from the <RTIgt; [Embodiment] The present invention provides a novel system and method for sensing temperature, fluid flow rate, pressure, and chemical environmental conditions, and which can be used as a heater capable of sensing its own temperature and is more sensitive than previous sensing The device has higher temperature capability, greater sensitivity, faster response time, and/or lower offset. In the preferred embodiment, it is based on the formation of a tungsten (w) film (typically a film defined as having a thickness of about 100 to 10,000 angstroms) on an A1N substrate. Since A1N has a thermal expansion coefficient of about 4·4χ1 (Γ6/°Κ at 330°Κ and a thermal expansion coefficient of about 5.3χ10-6ΛΚ at 1273〇Κ, while the thermal amine coefficient of the town is at 330°Κ The time is about 4·6χ1 (Γ6/°Κ and about 5·1χ1〇-6/〇Κ at 1273CK, so the combination of these materials is particularly advantageous. Therefore, the thermal expansion coefficients of the two materials are very close to each other, Allows for a high degree of structural stability over a wide temperature range. The substrate is insulating, while tungsten is generally electrically conductive and has a resistivity that varies with temperature in a known manner. The American Institute of Physics Handbook, reprinted in 1982 The temperature-resistance characteristics of tungsten are discussed in pages 2–41 of the second edition, the contents of which are incorporated herein by reference. When W/A1N is a preferred material combination, the material system can be summarized as 93277.doc -10- 1247099 An AIN substrate having a conductive layer on a substrate or an insulating substrate having a tungsten layer on the substrate, in either case the conductive layer has an expansion within 1.00 +/- 0.07 of the substrate within a predetermined temperature operating range Coefficient, and generally Does not react with the substrate and has substantially no solid solubility or interdiffusion with the substrate. A1N has a thermal conductivity of about 1+7-2.4 W/cfK which is about ten times higher than the thermal conductivity of ceramic A12〇3. When it is heated by the adjacent tungsten layer of the factory, the child's rain conductivity makes it very efficient as a heater. A1N also exhibits a high resistance to chemical reactions with metals such as tungsten. It sublimes at about 25 〇〇 and depends on its environment and has a temperature of approximately ll5 (rc to 180 (continuous use temperature above the TC and makes it suitable for use in the high temperature range. Tungsten has a solubility of about 341 (TC) The temperature is also known to be 18 〇 (the following rc does not chemically react with A1N, which is also advantageous for high temperatures in the composition with Am. ', between tungsten and A1N at a temperature of about 1880 ° C in an inert atmosphere The slow chemical reaction, (4) solubility and interdiffusion, which are completely absent or unmeasurable, ensure that the cross section of the crane circuit is not reduced by chemical reaction with the A1N substrate, which also ensures that the surface of the A1N substrate does not become conductive: The surface of the A1N substrate with the crack of the ^ circuit method - the temperature range The very well-matched temperature expansion coefficient within the thermocouple ensures that the tungsten circuit does not peel off the A1N substrate during thermal cycling. As will be described in further detail below, an additional circuit layer composed of or an Au-Pt alloy can be provided on the tungsten circuit layer. Perform three functions: (1) protect the 4 5H tungsten circuit from oxidation; (2) place the circuit on the A1N substrate with the cover 93277.doc 1247099 «In the beginning (four) - have the electrical insulation layer exposed at the top and bottom\ (4) Multi-layer circuits; (3) Provide additional cross-sectional area for circuit paths. Compatibility between additional ruthenium layers such as hai and tungsten (or wc, when carbon reacts with tungsten to form another layer = cement) f includes: (1) little or no chemical reaction between the maximum operating temperatures; (7) In the case of limited interdiffusion and limited solid solubility, the gentleman is connected to the interface at or near the opposite interface, holding the difference between the moon, the, and the ,, and (3) limiting the maximum solid solubility between them. So that the basin does not form a homomorphic or pseudo-homomorphic phase diagram at the maximum operating temperature; (4) it does not form a compound with each other' and (5) its melting temperature exceeds the maximum operating temperature. Demand i; 4 ensures these additional circuit layers Unexpectedly (or - destroying its interface and ensuring that the combined circuit resistance is not offset in the case of operation. Also as described in the following paragraphs - some examples include a mixture of lead salts (B203 + Sl〇2) Encapsulating. The glutamic acid is applied in a non-reactive form and then reacted by heating the structure to at least 丨〇(8). C. The mixture after the reaction is bonded to an oxidizable surface and covered. Non-oxidizable a layer of glass. It does not have to be in contact with the circuit layer and remains as an electrical insulator. Additional circuit material can be applied or deposited on and around the edge of an A1N substrate or cover or by the substrate or cover An additional circuit material applied or deposited in the via is formed from an extended portion of the circuit layer itself to form an electrode for applying an electrical signal to the germanium circuit layer. Additional electrode layers may be provided on top of the tungsten electrode for wire or tape attachment The additional layers may comprise carbon, platinum or gold. The carbon provides a thermally active bond 93277.doc -12-1247099 material that joins W to W or joins W to M〇 when heated to above about 700 t. The bonding material consumes carbon by reacting with W and Mo to form a carbonized metal bonding interface that remains intact at temperatures above 1 800 ° C. Platinum provides a pedestal on which Pt or Au can be soldered, the bonding It will remain intact at a temperature equal to the melting point of the Pt or Au-Pt alloy formed during the soldering process. Gold provides a pedestal on which the Au or solder Pt is bonded, which will be equal to the Au formed during the soldering process or Au-Pt alloy The temperature remains constant at the temperature of the melting point. The additional electrode layer may also comprise a layered Pt and Au or Au-Pt alloy. It provides a pedestal on which the Au or solder Pt is bonded. Participation in steaming, bonding or soldering processes The thickness of the electrode material should be at least 0.05 times the diameter of the lead or the thickness of the guiding tape. The electrodes can be exposed, encapsulated or covered by A1N. The A1N substrate or cover surface that is in contact with W: by electrostatic force And holding the W film on the surface of the A1N by cracks penetrating the surface of the A1N. Although it is difficult to determine the amount, the observation results indicate that good W adhesion is obtained on all ceramic A1N surfaces (average roughness of 2 2 μm (0.05 Mms)). However, the maximum thickness of W is directly proportional to the average surface roughness of A1N. The maximum thickness of W on the surface of A1N is about 100 times the average surface roughness. Application on the A1N substrate and cover and its 'formation': several vapor deposition techniques (such as RF/DC sputtering, RF/DC common sputtering, electron beam evaporation, and chemical vapor deposition (CVD) can be used. )) Apply W to the A1N substrate with the correct combination. Since adhesion is produced by physical bonding rather than chemical bonding, the A1N surface temperature is not important in W deposition. 93277.doc -13- 1247099 When deposited, the W film will not have a theoretical density unless deposited by CVD. The film density can be increased by thermal annealing and the particle boundary region can be reduced. When the density or grain boundary region is important to protect the W/A1N interface from additional circuit layer metals, w should be annealed prior to application of additional circuit layer metal. The annealing temperature ranges from 800 ° C to 1400 ° C, and the density and particle growth depend on the time of the temperature. The annealing atmosphere should be vacuum or inert (Ajt, N2).

When it is desired to "form" to promote bonding of the upper layer, the tungsten film may be partially or completely converted into WC. In this treatment, carbon is applied as in the case of depositing or annealing a film by sputtering, physical vapor deposition or physical application of CVD or graphite (e.g., screen printing). The film is transformed into (''formed&) by thermal induced diffusion. The formation temperature range is from 80 〇^: to 14 〇〇. (::, preferably has a higher temperature. The "forming" atmosphere should be vacuum or inert (Ar, N2). For the purpose of the present Z, σ, as mentioned in the scope of these patents, W&quot; Also included is the WC's officially found that wc^bw has a lower coefficient of thermal expansion and therefore is not as suitable as the general application except for joining an overlapping layer in place.

If W is to be covered by an additional circuit layer metal layer, the minimum preferred thickness of the deposition w is equal to the average roughness of the A1N substrate surface. If w is only the film containing the electrical path, then the minimum of the following two requirements is determined to be the minimum; after T degrees · (1) W, the thickness of the treatment should be at least the average roughness of the surface of the picking surface two ... or (7) its thickness multiplied The width (sectional area) should be sufficient to provide the

...the current processing capability. Low quality radiant heaters or circuit applications typically do not require thicknesses greater than 1 〇 microns when there is no fundamental limit on minimum W thickness. Additional Circuit Layer CACL) Metal The ACLs as applied/deposited may consist of a layer of 93277.doc -14-1247099 or layers, which are applied/deposited sequentially. Each layer of ALC can be applied by coloring, screen printing, electroplating, or vapor deposition (technical depending on the material). The treated ACL can be a single or multilayer film comprised of a graded composition of elements or alloys or both. The treated ACL can be as applied/deposited or it can be heat treated to redistribute the film composition. Although melting may occur in one or more (but not all) layers of the ACL during heat treatment, the resulting alloy must be solid at the same processing temperature. For example, Au-Pt-bonded Au can be formed by heating an Au/Pt multilayer structure to a temperature that exceeds the melting temperature of Au but below the melting temperature of the desired alloy. In this case only Au is dissolved, so it is quickly consumed by Pt to form an alloy having a higher melting temperature. The thickness of the ACL metal to be applied/deposited should be such that the post-treatment thickness of the ACL is equal to or greater than the average roughness of the A1N surface. The minimum preferred thickness of the applied/deposited ACL is 5 x 10 6 cm. The minimum thickness of the ACL can be determined by the W+ACL cross-sectional area sufficient to provide the current handling capability required by the sensor or heater. The minimum thickness of the ACL is limited by the line to which the circuit associated with A1N is applied and by the difference in expansion coefficients between W and ACL. Tests conducted so far have shown that the upper thickness limit is 60 times greater than the W thickness. Carbon reactive bonding: carbon provides a thermally active bonding material that bonds the W/Mo wire/band to the W electrode when heated above about 700 ° C, wherein carbon is consumed by W and Mo to be in W and W or A WC or Mo-carbide bonding interface is formed between W and Mo, and the bonding remains intact at temperatures exceeding 1800 °C. 93277.doc -15- 1247099 Participation. The thickness of the electrode material for the reactive bonding treatment should be sufficient to consume all of the carbon. This bonding process requires c, w^. Interdiffusion so that the bonding is completed = the rate is directly proportional to the temperature. The thickness of the electrode material involved in brazing, joining or tanning shall be 5 times the diameter of the wire or 0.05 times the thickness of the tape or pressure. According to the experimental investigation, it is a functional joint = Take a small f-degree requirement. However, it is difficult to achieve strong bonding at this ratio (low-recommended, the electrode thickness is at least G.1 times the wire diameter or at least the strip thickness, which is due to higher yield. And improved the thick chain of the joint

Degree 0

Au and Pt alloy bonding: - pt electrode layer provides - soldering or soldering / bonding / brazing such as wire / tape pedestal; at a temperature equal to the temperature of the melting point of Au Pt gold formed during pt or bonding The bond formed between the tape and the electrode will remain Μ. The Au electrode layer, the layered pmAu electrode layer and the Au_Pt alloy electrode layer each provide a pedestal on which the bonding/bonding //belt or the solder/brazed Pt wire/tape is formed; formed at equal to Au or during bonding The bond formed between the wire/tape and the electrode will remain intact as the temperature of the Au Pt a to the melting point. The thickness of the electrode materials involved in brazing, bonding or soldering processes is similar to that of carbon bonding. The lead wires/tapes should be attached to the electrode pads by bonding, brazing or soldering. The expansion coefficient of the guide wire material should be within twice the expansion coefficient of the composition of the post-treatment electrode layer. The diameter of the wire which can be flattened/welded/brazed to the bungee of the wire which is perpendicular to its flat surface in the case of 5 liters is the appropriate diameter used in determining the minimum thickness of the electrode layer. 1 illustrates a sensor in accordance with the present invention, wherein the tungsten circuits are further bonded to the package 14 of the substrate, preferably on an A1N substrate 4 93277.doc -16-1247099. The borosilicate mixture consisted of 45% by weight of 82 〇 3 + 55 wt% iSiO 2 . It was reacted at 1000 ° C for 5 minutes in air. In the embodiment shown in Figure 5, an A1N盍16 is placed on top of the unreacted B2〇3 + Si〇2 in Figure 4 and the resulting structure is thermally reacted to join the A1N cover 16 at a suitable additional protection. Both the package 14 and the cover 16 expose the electrode pads 6 to receive wires or strips for applying an electrical signal to the tungsten circuit. The borosilicate was reacted in air at 1 Torr for 5 minutes to join the lid where appropriate. In the embodiment illustrated in Figure 6, au and Pt layers 18 and 2 are applied as a film on the tungsten layer of the finished structure shown in Figure i; pt or may be a top layer. The result is a three-layer circuit on the A1N substrate 4. The assembly is then thermally reacted to form a two-layer circuit having a configuration similar to that shown in Figure 3, which has a lower layer comprising a crane and an Au_Pt alloy having a thickness determined by the Au and pt layers. The top layer of the circuit. In one example, a 1 Å enamel layer is sputter deposited on the A1N substrate, followed by a 100 angstrom Au and a 1000 angstrom Pt sputter deposition layer. According to the map! The thermal reaction to form the Au-Pt alloy is completed during electrode preparation as described. Another embodiment having an ACL and a protective A1N cover is illustrated in Figures 7 and 8. Referring first to Figure 7, as shown in Figure 6, a substrate assembly is provided having Ail and Pt layers 18 and 20 on the tungsten layer 2 of the substrate 4 (not in this order). An A1N cover 22 is provided having a similar three-layer conductor structure consisting of a town layer 2', Au and Pt (or Pt and Au) layers 18, and 20, all of which have the same layer as the substrate 4 geometric. The cover 22 is positioned on the substrate 4 and aligned with the different layers. The composition is then thermally reacted to form a three-layer circuit as shown in FIG. 8. The three-layer electrical 93277.doc -19-1247099 road has a S-substrate 4 and a cover 24 of the crane® 2 # &lt; And 2 sub-layered an Au_pt alloy circuit layer 24 therein. In a ribbed towel, a 10 angstrom thick Au layer and a 1 angstrom thick sound were sputtered on a 10 (8) angstrom sputter deposited tungsten layer. Fig. 9 is a view showing the structure obtained by the self-heating reaction of the structure shown in Fig. 6, which has a -Au-Pt alloy circuit layer 26 on the crane circuit layer 2. A seclating acid salt package 28 is formed on the 3 structure in a manner similar to package 14 of FIG. Figure 1A illustrates an embodiment in which the structure of Figure 9 is further protected by an A1N cover 30. The lid was placed in position and the niobate was reacted in air for 5 minutes under (10) generation to engage the lid. The invention can be advantageously applied to a planar heater. Figure u illustrates a heater formed on a rectangular (including square) A1N substrate which, in the absence of ACLs, acts as a base for a tungsten heating element that can be fabricated as described above. The tungsten layer is formed such that it is preferably a series of substantially parallel, twisted lines 34 that are parallel and connected at the opposite ends of the substrate by terminal strip %, and preferably in the array The electrode % is provided at the opposite corner. The shape provides uniform heating across all A1N substrate regions (except for their edges) and results in a more uniform rise in the rapid thermal tilt at a rate of TM seconds and a plate. The circuit line is straight to the right, and is initially heated at the center of each line and at its terminal 180. The turning occurs most rapidly, and the substrate is placed in danger of being destroyed due to the parallel thermal gradients when the heat is extremely tilted. For a thin (0.01 inch to 〇〇 14 inch (7) 〇 25 cm to 〇〇 % cm), low quality A1N substrate, the width of line 34 should not exceed 吋 (0.25 m) and The spacing between the lines should be uniform and not exceed 〇 们 277 93277.doc -20-1247099 (0.18 cm) to ensure that the thermal gradient across the spacing between the lines will not cause substrate damage. The distance between the peak and the valley perpendicular to one of the line conduction paths should not exceed the width of the line itself. These lines should be bent without forming sharp corners. The distance between the peaks and the valleys parallel to the line conduction path should be no more than 1 inch (2.5 cm) to prevent the substrate from rupturing during rapid heating, and the shorter distance can be on the surface of the substrate during rapid heating. Provides more uniform heating. The combined resistance of the lines is the resistance of a single line divided by the total number of lines in the pattern plus the resistance of an electrode strip. Parallel conductive lines allow rapid heating to high temperatures with a suitable voltage and film line (100 - 1 〇, 〇〇〇 厚 thick). Together with the terminal strips 36 provided in Figure 11, the tungsten wires are not only geometrically parallel but also electrically parallel. The terminal strips 36 can be replaced with separate electrodes at the opposite ends of each line, but are not required. Electrodes 38 are placed at opposite corners of the substrate to maintain any change in voltage that drops to a lower level across different lines. In an alternative embodiment illustrated in Figure 12, a plurality of wire terminals 4G are provided on each electrode strip % and are just opposite each other and are associated with their service line (each electrode serves no more than two wires) . Figure 13 illustrates a preferred tungsten pattern for a circular substrate 42 that ensures that the electric field strength between the opposing electrodes 44 at elevated temperatures does not exceed the dielectric decomposition strength of the A1N substrate; beyond the dielectric decomposition The strength can cause the substrate to crack or be damaged. The dielectric strength of the substrate decreases with increasing temperature and its pre-slurry is about 2000 volts/inch pairs (787 volts/cm) at 1300C. The tungsten wires 46 are bent and extend generally along respective warp threads that merge at opposite ends of the electrode 44. The lines are symmetrical about a centerline 48 that passes through the electrode electrodes 93277.doc -21 - 1247099. To ensure that the power is evenly dissipated along the length of each line, the line can be overlapped from the electrodes, but the line width perpendicular to its conduction path should remain constant. Since the lines having different distances from the center line 48 have different lengths, the width of each line associated with other lines should be decremented toward the center line so that the power dissipation per unit length of each line is close to the power per unit length of other lines. dissipation. It ensures uniform heating of the A1N substrate and the substrate is not damaged by thermal gradients. To ensure that the thermal gradient between the lines perpendicular to the line path does not cause damage to a thin, low-mass A1N substrate, the maximum spacing between the points in the lines should not exceed 0.07 inches (0._m). The spacing distance between the lines does not have to be the same: it should be symmetrical about the centerline 48. For temperatures above the heater temperature, the spacing between the midpoints of the line should be less than 〇 7 inches (〇 18 cm). Figures 14 and 15 illustrate the application of the present invention to a temperature sensing device, a single ended heater or a heater that senses its own temperature. In Fig. 14, a voltage source 5 is applied with a voltage to pass over a tungsten conductive film 2 deposited on the A1N substrate 4. An ammeter 52 monitors the current through the tungsten film. When t is used to sense the temperature of the surrounding environment, (4) a low voltage is applied to apply an actuation signal that does not significantly heat the tungsten film. The resistance of the film is determined by the temperature of its surrounding environment based on the known temperature coefficient of the tungsten resistor. The temperature of the surrounding film can be determined by dividing the applied voltage by the measured current to determine the resistance of the film. The response of the tungsten film sensed by the ammeter 52 to a known applied voltage changes with ambient temperature. The current level that can be sustained in the tungsten film without causing significant heating of the film is determined by several factors such as ambient temperature, film thickness, surface area and shape, and ambient heat capacity 93,277.doc -22-1247099. Typically, once the heating threshold is reached, the film will undergo a rapid increase in heating as the current level continues to increase. When the ambient temperature increases, the heating threshold increases. When used as an open heater, a higher voltage level is applied. The system can be pre-registered to at least close to - the amount of heating that can be obtained from a given voltage level and without the need for an ammeter 52. To operate as a heater that senses its own temperature, an ammeter μ is added back to the circuit to sense the current through the crane layer. The temperature of the film can be accurately determined by using the electrical dust and current levels and determining the known geometry of the film from which the temperature of the m resistance curve of the cell is operated. The system of Figure 15 is similar to the system of Figure 14, but instead of applying a voltage across the tungsten film and sensing the resulting current, the current source 54 is used to drive the two actuation currents through the membrane 2 and use a voltmeter. The resulting voltage across the membrane was measured. The film depletion temperature can be determined again in the same manner as in Fig. 14. The temperature-resistance characteristic of one of the structures shown in Figure 1 is measured and compared to the known theoretical resistance-temperature curve 58 of tungsten shown in the figure. The amount obtained in the flowing Ar environment can be indicated by a hollow circle 6〇. The results are measured and tracked very close to the theoretical curve of the measured limit of 14 ° C. The measured trace in air is about 26 (the theoretical curve of the temperature of TC, beyond which the oxidation of the tungsten is Starting from the theoretical curve, the measurement obtained in the air environment is indicated by a solid circle 62. The edge test of Fig. 16 is performed in a water-cooled condensed quartz tube. Prototype sensing is placed on an AW sheet, which is located at RF heating on the graphite susceptor. The wire extending from each of the two sensor electrodes extends through a 〇-ring seal extension 93277.doc -23-1247099 to provide precise current input to the sensing person The voltage and current source sub-extends to a multimeter for measuring the output voltage of the sensor. It is the first time to measure the sensitivity of a tungsten film. It can be calibrated using the material shown in Figure 16. a tungsten film of known cross section and length As a temperature sensor. Perform a test in the air on the heater chuck of the ball ball adapter, where the prototype sensor is clamped on the surface of the heater chuck. The top and sides of the sensors are made of tannin. Cotton insulation. The electrical contact to the sensor electrode is made using a gold probe that extends from the micromanipulator and is compressively connected to the sensor electrode. The applied current is measured with the measured sensor output voltage and The applied voltage of the waveform tracer, the voltage read from the waveform tracer across the sensors and the current passing through the sensors, performs a two-wire power measurement. The type shown in Figure 11 is also tested. Planar electric heater. Its size is 4 25 in. χ4·25 ΐη·χ0·014 in•thickness (10·8 cmxl〇.8 cmx0.036 cm). The maximum heating rate is obtained at about 500 C % and the maximum temperature is about 15 〇〇, both of which are limited by the useful power. The area power density versus temperature curve of Figure 17 shows the power of the detected A1N substrate area per cell, while the volume power density versus temperature in Figure 18 The resulting A1N basis per unit in the curve The power of the volume can also be used by measuring the change in the temperature of the self-heating sensor. The device is located along the flow path 4' and can be immersed in the fluid or in contact with the wall of the flow path. In the illustration of Fig. 19, a gas is sensed by self-heating sensor 66 of the type described herein located along the flow path and immersing in the flow or contacting the flow path wall 68. Or the flow rate of fluid 93277.doc -24-1247099 (indicated by the head 64). In the present embodiment described herein and the following examples, the actuation signal is illustrated by an adjustable current source 70. Seventh, wherein the voltmeter 72 senses the voltage response of the sensor, which in turn corresponds to the sensor resistance and thus corresponds to the fluid temperature. However, a voltage can be provided as the actuation signal and the resulting current is sensed. The flow rate can be determined by comparing the sensed temperature / temperature at the V-speed and considering the heat capacity of the fluid. In the differential flow rate sensor illustrated in Figure 20, two or more sensors 74, 76 of the type described herein are connected in series along the fluid flow path 64. The flow rate is sensed by measuring the temperature difference between the sensors. At zero flow, the upstream sensor 74 is electrically self-heated by a known current (or known voltage) from current source 70 to a resistor representing a known temperature. The downstream sensor 76 is biased (flowed) by a small amount of non-heating current or voltage. The independent current source 7〇 can be supplied from an ordinary current source or equally as shown to provide an actuating current. The fluid flow removes heat from the upstream self-heating sensor 74 and releases some of the heat to the downstream sensor 76. The change in voltage across each of the sensors is related to the flow rate through the heat capacity of the gas or fluid. This type of differential flow rate sensing can be used in a conduit parallel to the main flow path to determine the flow rate through the path. Figure 21 illustrates the application of the present invention to a fluid level sensor in which a sensing member 66 is disposed in a fluid container 78 or at a fixed location in contact with the outer wall of the container. A rise and fall of the fluid 8 in the container causes the sensor 66 to be immersed in or removed from the fluid. The heat capacity of the sensor's tight environment depends on whether the fluid level has risen to 93277.doc -25-1247099 depending on the sensor. When the sensor is at a known level of the container and it is used as a self-heating temperature sensor as described above, the heat can be determined by sensing how quickly the sensor can remove heat from the sensor. Whether the sensor is immersed in the fluid. When the application is described in the form of a fluid sensor, it can also be used to detect the presence or absence of gas in a sealed container at least at a minimum density level. When applying the present invention to the above flow rate or fluid level sensing applications, the main advantages of the present invention are faster response times (related to high substrate thermal conductivity) and greater sensitivity (also associated with high substrate thermal conductivity). And relatively low or no offset (related to the small expansion coefficient mismatch between the W sensing circuit and the A1N substrate). In Figure 22, the sensor 66 of the present invention is used to sense a sealed container. Gas pressure in the middle. The pressure in the vessel can be sensed by determining the desired current to maintain a particular voltage across the sensor or the voltage required to maintain a particular current across the sensor. This data may be related to the pressure/density of the gas having a known heat capacity in the vessel, which may be a vacuum chamber. The current source 70 shown in Figure 22 is adjusted to maintain a particular voltage level as sensed by the voltmeter 72 across the sense 1 §. The conversion of the current level to the pressure level in the vessel is illustrated by a pressure gauge 84 provided by the current source. The present invention enables voltage and current sensing that is more sensitive than currently available thermocouples and thus enables a more sensitive pressure sensing and can operate at higher temperatures than available thermocouples. Figure 23 illustrates a chemical composition for use in the present invention to detect its environment. As shown in Figure 1 'this sensing|§ exposes the circuit material to the environment so that it is to be sensed by 93277.doc -26 - 1247099 or BeO). The substrate is a heater and receives heat from the resistance heating circuit metal.嫣, line type: This type of resistance heating tungsten wire is used in the bulb and halogen tungsten lamp. It can be seen from the overview of &quot;Hai et al. that the present invention is significantly improved in the operating temperature, &amp; circumference, accuracy and response time for temperature sensing and heating. Improvements also exist in zh's range, sensitivity, low offset, strong thermal shock resistance and heating efficiency. A number of variations and alternative embodiments will be apparent to those skilled in the art when a number of illustrative embodiments of the invention are described. Such changes and substitutions are intended to be and are not intended to be in the spirit and scope of the invention as defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sensor/heater according to an embodiment of the present invention, wherein a thin film tungsten layer is provided on a substrate of one turn; FIG. 2 is a cross-sectional view of another embodiment, wherein Figure 1 is a perspective view of another embodiment having a protective layer on the tungsten layer of the Figure; Figure 4 is a perspective cross-sectional view of another embodiment, wherein Figure 4 is a perspective view of another embodiment of the present invention; Figure 1 is a perspective cross-sectional view of another embodiment, wherein the structure of Figure 4 has a top cover; Figure 6 is a perspective view of a front body of another embodiment, 93277.doc -28- 1247099 provides a protective cover for the structure shown in Figure i; Figure 7 is a perspective cross-sectional view of another example, wherein the structures are assembled as shown in Figure 6; Figure 8 is A perspective cross-sectional view of the structure formed by the heat response to the structure of Fig. 12; Fig. 9 is a perspective cross-sectional view of another example in which a protective package is formed on the structure after the structure of the heat is restored; Fig. 10 has a The structure of the A1N cover shown in Figure 9 Cross-sectional view; FIG. 11 is a plan view illustrating a rectangular plane 12 based heater of one embodiment in accordance with one embodiment of the present invention, having two different electrodes configuration; FIG. 13 lines of a plan view illustrating a circular planar heater embodiment. Figures 14 and 15 are simplified schematic views of two heater/temperature sensor embodiments of the present invention, each having voltage and current drive; Figure 16 is a comparison of the theory and measurement of the structure shown in Figure 1 Graphs of temperature versus temperature characteristics; Figures 17 and 18 are graphs of energy per unit substrate area and energy per unit substrate volume for the function of temperature used in the embodiment of the Figure; Figure 19, 20, 21 22 and 23 illustrate simplified views of the application of the present invention to a single element flow rate sensor, a dual element flow rate sensor, a fluid level sensor, a pressure sensor, and an environmental sensor, respectively; 24, 25 and 26 respectively summarize the temperature range of various embodiments of the present invention for different operating environments, the characteristics of the temperature sensor using various embodiments of the present invention, and the prior art temperature sensor, and the use thereof. Invention 2 Table 93277.doc -29- 1247099 of the characteristics of the heaters of the various embodiments compared to prior art heaters. [Main component symbol description] 2 W layer 2' W layer 4 A1N substrate 6 Electrode 8 A1N cover 10 WC layer 12 Au film 14 Package 16 A1N cover 18 Au (or Pt) layer 18, Au (or Pt) layer 20 Pt ( Or Au) layer 20! Pt (or Au) layer 22 A1N cover 24 Au-Pt circuit layer / A1N cover 26 Au-Pt alloy circuit layer 28 package 30 A1N cover 32 A1N substrate 34 wire 36 terminal strip / electrode strip 38 electrode 93277 .doc - 30 - Wire Terminal / Warp Round Substrate Electrode W Line Center Line Voltage Source Amperage Current Source Voltmeter W Known Theoretical Resistance - Temperature Curve Hollow Round Solid Circle Arrow (Indicating a Gas or Fluid) Sensor Flow Path wall current source current source voltmeter upstream sensor / self-heating sensor downstream sensor fluid container fluid sealed container pressure gauge gas tank -31 -

Claims (1)

1247|)Shu 114815 Patent Application '' Chinese Patent Application Substitution (June 1994) X. Patent Application Range: 1. A sensor system comprising: an A1N substrate (4), one at The W layer (2) on the substrate is adapted to apply an electrical actuation signal source (7〇) to the W layer, and the second is adapted to sense the response of the W layer to the actuation signal. Sensor (72). 2. The system of claim 1 wherein the layer comprises a film. 3. The system of claim 1, further comprising an anti-oxidation protective layer (12) on the layer. 4. The system of claim 1, which is constructed as a temperature sensor, wherein the actuation No. 7 applies a non-heating electrical signal to the 4 w layer, and the sensor senses the w layer to actuate the violation The response of the signal is an indication of the temperature near the sensor. 5. The system of claim 1, wherein the signal source applies a signal to heat the w layer. 6. The system of claim 5, wherein the sensor senses a response of the w layer indicating its temperature. The system of claim 6 further comprising an additional A1N substrate having an additional W layer (2) on the surface, connecting the signal source to add substantially unheated electrical signals to the additional w layer of palladium, and connecting one The sensor (72) senses a response of the additional W layer indicating its temperature, the outer substrate and the W layer being disposed downstream of the substrate and the conductive layer in a fluid flow path (64), wherein the W The temperature between the additional W layers is 93277-940708.doc 1247099 The difference corresponds to the fluid flow rate. 8 · The system of claim 1 wherein the substrate and the W layer are disposed in a fluid flow path (6 4) to control the signal source to apply an actuation signal for heating the w layer, wherein the sensing is performed by the sensing The response sensed by the device corresponds to a fluid flow rate along the path. 9. The system of claim 1, wherein the substrate and the w layer are alternately immersed in and removed from a predetermined fluid (80), and the response sensed by the sensor indicates whether the substrate and the W layer are in the In the fluid. The system of claim 1, wherein the substrate and the W layer are disposed in a variable pressure environment (82) that senses the response of the w layer as an indication of the pressure in the environment. U. The system of claim 1, wherein the substrate and layer are disposed in an environment (86) in which the W layer is subjected to an environment in which the W layer responds to a given actuation signal. The change governs, wherein the relationship between the actuation signal and the response indicates the chemical nature of the environment. 12. A circuit component comprising: an A1N substrate (32), and a W film layer (34) on the substrate. 13. The circuit component of claim 12, wherein the W layer comprises a plurality of wires (34) distributed over the substrate, wherein the substrate is rectangular and the wires are substantially parallel and formed into a bowl. 4. The circuit component of claim 13, wherein the layer comprises a plurality of wires distributed on the substrate, wherein the substrate is circular (42) and the wires extend along respective two, bundles (4 turns) The warp threads are joined at the opposite pole (44) of the substrate 93277-M0708.doc 1247099 15. A sensing method includes the following steps: 16. 17. 18. Sensing the W layer's response to the actuation signal. The method of claim 15 wherein a non-heating actuation is applied to the W layer to sense its response as an indication of the temperature in its vicinity. A method of requesting Jf 1 4 , ^, wherein the actuating signal heats the method of claim 7, wherein the temperature of the W layer is sensed. 93277-940708.doc -3 - I247Q99 f 〇93114815 Patent Application Chinese Graphic Replacement Page (July 94) 93277