CN113551834B - Vacuum sensor and vacuum gauge - Google Patents
Vacuum sensor and vacuum gauge Download PDFInfo
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- CN113551834B CN113551834B CN202110737875.XA CN202110737875A CN113551834B CN 113551834 B CN113551834 B CN 113551834B CN 202110737875 A CN202110737875 A CN 202110737875A CN 113551834 B CN113551834 B CN 113551834B
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L21/00—Vacuum gauges
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Abstract
The invention discloses a vacuum sensor and a vacuum gauge, relates to the technical field of vacuum pressure measurement, and is used for expanding the vacuum degree measurement range of the vacuum sensor, so that the vacuum sensor can be used for measuring the vacuum degree under higher air pressure and expanding the application range of the vacuum sensor under higher air pressure. The vacuum sensor includes: a base and a suspension structure. The substrate is provided with a groove. The suspension structure is arranged above the groove. The suspension structure includes a suspension hotplate and at least two cantilever beams. The suspended hotplate is connected with the substrate through at least two cantilever beams. Each cantilever beam has a support portion and a heating portion disposed on the support portion. The material of the heating portion has a thermal expansion coefficient different from that of the material of the supporting portion. The heating part is used for heating the corresponding cantilever beam when the vacuum sensor is in a working state so as to shorten the heat exchange distance of the vacuum sensor. The vacuum sensor is applied to a vacuum gauge.
Description
Technical Field
The invention relates to the technical field of vacuum pressure measurement, in particular to a vacuum sensor and a vacuum gauge.
Background
A Pirani vacuum sensor belongs to one of heat conduction vacuum sensors. The working principle is as follows: the heat conducted by the ambient gas to the heated object comprised by the pirani sensor varies with the gas pressure. Based on the above, the relation between the electrical response and the vacuum degree is established by the thermoelectric coupling principle, so that the pressure monitoring of the vacuum environment is realized. The Pirani vacuum sensor has the advantages of small volume, low cost, low energy consumption, quick response and the like, and is widely applied to vacuum packaging of various sizes and vacuum degree monitoring of micro cavities.
However, the measurement range of the existing pirani vacuum sensor is smaller, and the measurement range cannot be used for measuring the vacuum degree of higher air pressure, so that the application of the pirani vacuum sensor is limited.
Disclosure of Invention
The invention aims to provide a vacuum sensor and a vacuum gauge, which are used for expanding the vacuum degree measuring range of the vacuum sensor, so that the vacuum sensor can be used for measuring the vacuum degree under higher air pressure and expanding the application range of the vacuum sensor under higher air pressure.
In order to achieve the above object, the present invention provides a vacuum sensor comprising:
the substrate is provided with a groove;
and a suspension structure disposed above the recess; the suspension structure comprises a suspension hot plate and at least two cantilever beams; the suspension hot plate is connected with the substrate through at least two cantilever beams; each cantilever beam is provided with a supporting part and a heating part arranged on the supporting part; the thermal expansion coefficient of the material of the heating part is different from that of the material of the supporting part; the heating part is used for heating the corresponding cantilever beam when the vacuum sensor is in a working state so as to shorten the heat exchange distance of the vacuum sensor.
Compared with the prior art, in the vacuum sensor provided by the invention, the suspension hot plate included in the suspension structure is connected with the substrate through at least two cantilever beams and is positioned above the groove formed in the substrate. Based on this, when the vacuum sensor is in an operating state, since the heat dissipation on the suspension hot plate includes the heat dissipation of the suspension hot plate by the heat conduction of the gas, the radiation heat dissipation of the suspension hot plate, and the heat dissipation of the suspension hot plate by the heat conduction of the solid in contact therewith, in the case where the suspension hot plate is not directly in contact with the substrate, the heat dissipation of the suspension hot plate by the heat conduction of the solid in contact therewith is made to include only the heat dissipation by the cantilever Liang Dere, and the heat dissipation by the heat conduction of the substrate is not made to be included, so that in the case where other factors are the same, the heat dissipation amount of the suspension hot plate by the heat conduction of the solid in contact therewith is reduced, whereby the ratio of the gas heat conduction in the total heat dissipation can be improved, and the measurement lower limit of the vacuum sensor can be further made to be expanded downward.
In addition, the cantilever includes a support portion, and a heating portion disposed on the support portion. The material of the heating part has a thermal expansion coefficient different from that of the material of the supporting part. And the heating part is used for heating the corresponding cantilever beam when the vacuum sensor is in an operating state. Based on this, after the cantilever beam is heated, the cantilever beam is deformed due to unequal thermal expansion between the heating portion and the supporting portion. Meanwhile, one end of the cantilever beam is connected with the suspension hot plate, so that the deformed cantilever beam can change the longitudinal displacement of the suspension hot plate, and the heat exchange distance of the vacuum sensor can be shortened. In this case, since the vacuum sensor can only measure the switching point air pressure P which is more than that of the vacuum sensor 0 Low air pressure corresponds to vacuum degree, and the vacuum sensor is corresponding to air pressure P higher than the switching point 0 Is of the air pressure of (2)Insensitive, the vacuum sensor has a switching point pressure P 0 The upper measurement limit of the vacuum sensor is determined. And, because of the heat exchange interval and the conversion point air pressure P of the vacuum sensor 0 Inversely proportional, so that the pressure P of the conversion point can be effectively increased when the heat exchange distance is reduced 0 So that the upper measurement limit of the vacuum sensor can be further extended upward. That is, the vacuum degree at higher air pressure can be measured by the vacuum sensor provided by the invention, so that the application range of the vacuum sensor at higher air pressure is widened.
The invention also provides a vacuum gauge which comprises the vacuum sensor provided by the technical scheme.
Compared with the prior art, the vacuum gauge provided by the invention has the same beneficial effects as the vacuum sensor provided by the technical scheme, and the description is omitted here.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
FIG. 1 is a schematic diagram of a first structure of a vacuum sensor according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a second structure of a vacuum sensor according to an embodiment of the present invention;
FIG. 3 is a schematic top or bottom view of a suspension structure according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the relationship between the measured gas pressure of the vacuum sensor and the thermal conductivity of the gas in the test environment.
Reference numerals:
11 is a base, 111 is a recess, 112 is a substrate,
12 is a suspension structure, 121 is a suspension hotplate, 1211 is a support membrane,
1212, 1213, 122 are cantilevered beams,
1221 is a support, 12211 is a first support section, 12212 is a second support section,
1222 is a heating portion, and,
13 is a gas-permeable cover body, and the gas-permeable cover body is provided with a gas-permeable cover body,
14 is a cavity.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
Various structural schematic diagrams according to embodiments of the present disclosure are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and relative sizes, positional relationships between them shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.
In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present therebetween. In addition, if one layer/element is located "on" another layer/element in one orientation, that layer/element may be located "under" the other layer/element when the orientation is turned. In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise. The meaning of "a number" is one or more than one unless specifically defined otherwise.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
A vacuum sensor is a sensor for measuring gases below one atmosphere. It is generally used to measure the gas pressure by utilizing the change of some physical effect of the gas under different gas pressures, and is widely applied in scientific research and industrial production. Specifically, the vacuum sensor is classified into a capacitive thin film type vacuum sensor, a resonant type vacuum sensor, a heat conduction type vacuum sensor, an ionization type vacuum sensor, and the like.
Wherein, the Pirani vacuum sensor belongs to one of the heat conduction vacuum sensors. Existing pirani vacuum sensors generally include a grooved substrate and a suspension structure disposed on the groove. The substrate is provided with a temperature measuring piece for measuring the ambient temperature. The suspension structure has a cantilever beam, and a suspension hotplate connected to the substrate by the cantilever beam. The suspension hot plate is internally provided with a heating resistor and a temperature measuring resistor. When the Pirani vacuum sensor is in a working state, the heating resistor can heat the suspension hot plate so that the temperature of the suspension hot plate is higher than the ambient temperature. At this time, the heat consumption of the suspended heat plate includes gas heat conduction and dissipation, radiation and dissipation, and solid dissipation. Because the thermal conductivity of the gas changes with the pressure, the thermal conductivity of the gas is related to the vacuum degree of the vacuum environment. And the relation between the electrical response and the vacuum degree is established by a thermoelectric coupling principle, so that the pressure monitoring of the vacuum environment is realized. The Pirani vacuum sensor has the advantages of small volume, low cost, low energy consumption, quick response and the like, and is widely applied to vacuum packaging of various sizes and vacuum degree monitoring of micro cavities.
However, the conventional pirani vacuum sensor has a small measurement range, and cannot be used for measuring the vacuum degree at higher air pressure.
In order to solve the technical problems, the embodiment of the invention provides a vacuum sensor and a vacuum gauge. In the vacuum sensor provided by the embodiment of the invention, the cantilever beam comprises a supporting part and a heating part arranged on the supporting part. The material of the heating part has a thermal expansion coefficient different from that of the material of the supporting part. And the heating part is used for heating the corresponding cantilever beam when the vacuum sensor is in an operating state. Based on the above, after the cantilever beam is heated, the cantilever beam is deformed due to unequal thermal expansion between the heating part and the supporting part, so that the heat exchange distance of the vacuum sensor is shortened, the upper measurement limit of the vacuum sensor can be further expanded upwards, the vacuum degree of the vacuum sensor under higher air pressure can be measured by the vacuum sensor provided by the embodiment of the invention, and the application range of the vacuum sensor under higher air pressure is widened.
As shown in fig. 1 to 3, an embodiment of the present invention provides a vacuum sensor. The vacuum sensor includes: a base 11 and a suspension structure 12.
As shown in fig. 1 to 3, the substrate 11 is provided with a groove 111. The suspension structure 12 is disposed above the recess 111. The suspension structure 12 includes a suspension hotplate 121 and at least two cantilever beams 122. The suspension hotplate 121 is connected to the base 11 by at least two cantilever beams 122. Each cantilever beam 122 has a support portion 1221, and a heating portion 1222 provided on the support portion 1221. The material of the heating portion 1222 has a thermal expansion coefficient different from that of the material of the supporting portion 1221. The heating part 1222 is used for heating the corresponding cantilever beam 122 when the vacuum sensor is in an operating state, so as to shorten the heat exchange interval of the vacuum sensor.
Specifically, the base may be a substrate on which a film layer is not formed. For example: the base may be a silicon substrate. Alternatively, the base may be a substrate on which some structures are formed. For example: as shown in fig. 1 and 2, the base 11 may include a substrate 112, and a second temperature measuring member (not shown) disposed on the substrate 112. The recess 111 is provided in the substrate 112. The second temperature measuring piece is used for measuring the temperature of the testing environment. In this case, the vacuum sensor provided by the embodiment of the invention is also integrated with a second temperature measuring member. The second temperature measuring member can monitor the temperature of the test environment in real time so as to set the heating temperature of the suspension structure 12 and improve the accuracy of the output measurement result of the vacuum sensor. The substrate 112 may be a semiconductor substrate such as a silicon substrate. The second temperature measuring member may be any element capable of measuring the temperature of the test environment, such as a temperature measuring resistor and a thermocouple, and is not particularly limited herein.
In addition, the depth of the groove formed in the substrate can be set according to actual requirements. For example: as shown in fig. 1, the groove 111 may penetrate the substrate 11 in the thickness direction of the substrate 11. Also for example: as shown in fig. 2, in the case where the depth direction of the groove 111 is the same as the thickness direction of the substrate 11, the depth of the groove 111 may be smaller than the thickness of the substrate 11. Specifically, the specifications and positions of the grooves may be set according to the specifications and positions of the suspension structure. For example: the cross-sectional area of the notch of the groove is slightly larger than that of the suspension structure.
For the suspension structure, the specification and number of the cantilever beams included in the suspension structure may be set according to the specification and actual requirement of the suspension hot plate, which is not limited herein. For example: under the condition that the specification of the suspension hot plate is large, the number of the cantilever beams included in the suspension structure can be properly increased, or the specification of the cantilever beams is increased, so that the suspension hot plate can be stably arranged above the groove through the cantilever beams, and the structural reliability of the vacuum sensor is improved.
In addition, for the material of the supporting portion and the heating portion included in the cantilever beam, the material of the supporting portion and the material of the heating portion may be set according to actual requirements, so long as the material can be applied to the vacuum sensor provided by the embodiment of the present invention. The material of the supporting portion may be at least one of silicon oxide, silicon nitride, silicon, aluminum oxide, magnesium oxide, or silicon nitride. The heating portion may be made of any conductive metal material such as aluminum, gold, titanium, copper, tin, tungsten, molybdenum, chromium, or platinum. Of course, the material of the heating portion may be a non-metal conductive material such as doped polysilicon. Specifically, the thermal expansion coefficient of the material of the heating portion may be greater than the thermal expansion coefficient of the material of the supporting portion. Alternatively, the thermal expansion coefficient of the material of the heating portion may be smaller than the thermal expansion coefficient of the material of the supporting portion. For example: when the material of the heating portion is aluminum and the material of the supporting portion is silicon oxide, the thermal expansion coefficient of the material of the heating portion is larger than that of the material of the supporting portion. Also for example: when the heating portion is made of tungsten and the supporting portion is made of magnesium oxide, the thermal expansion coefficient of the heating portion is smaller than that of the supporting portion.
Specifically, the support portion may have a single-layer structure or a laminated structure. When the support portion has a single-layer structure, the support portion may be a silicon oxide support portion, a silicon nitride support portion, a silicon carbide support portion, or the like. When the support portion has a laminated structure, the support portion may have a laminated structure of silicon dioxide/silicon nitride or the like.
In a practical application process, as shown in fig. 1 to 3, when the vacuum sensor is in an operating state, the temperature of the suspended heat plate 121 is higher than the temperature of the environment. At this time, the heat dissipation on the suspension hotplate 121 includes the heat dissipation of the suspension hotplate 121 by the heat conduction of the gas, the radiation heat dissipation of the suspension hotplate 121, and the heat dissipation of the suspension hotplate 121 by the heat conduction of the solid in contact therewith, so that in the case where the suspension hotplate 121 is suspended above the groove 111 by the at least two cantilever beams 122, the suspension hotplate 121 is not directly in contact with the substrate 11, so that the heat dissipation of the suspension hotplate 121 by the heat conduction of the solid in contact therewith includes only the heat dissipation by the heat conduction of the cantilever beams 122, and does not include the heat dissipation by the heat conduction of the substrate 11 directly, that is, in the case of the same other factors, the suspension hotplate 121 by the solid in contact therewithThe heat conduction and dissipation amount is reduced, so that the ratio of gas heat conduction to total heat consumption can be increased, and the measurement lower limit of the vacuum sensor can be further extended downwards. Meanwhile, the heating part 1222 can heat the cantilever beam 122 including the heating part 1222. After the cantilever beam 122 is heated, the cantilever beam 122 is deformed due to the unequal thermal expansion between the heating portion 1222 and the supporting portion 1221. In addition, since one end of the cantilever beam 122 is connected to the suspension hot plate 121, the deformed cantilever beam 122 can change the longitudinal displacement of the suspension hot plate 121, and thus the heat exchange interval of the vacuum sensor can be shortened. In this case, as shown in FIG. 4, since the vacuum sensor can only measure the switching point air pressure P which is more than that of the vacuum sensor 0 Low air pressure corresponds to vacuum degree, and the vacuum sensor is corresponding to air pressure P higher than the switching point 0 Is insensitive to the air pressure of the vacuum sensor, the vacuum sensor has a switching point air pressure P 0 The upper measurement limit of the vacuum sensor is determined. And, because of the heat exchange interval and the conversion point air pressure P of the vacuum sensor 0 Inversely proportional, so that the pressure P of the conversion point can be effectively increased when the heat exchange distance is reduced 0 So that the upper measurement limit of the vacuum sensor can be further extended upward.
From the above, it can be seen that the vacuum sensor provided by the embodiment of the invention can not only enable the measurement lower limit of the vacuum sensor to be extended downwards by suspending the suspension hot plate above the groove through at least two cantilever beams. The support part and the heating part with different thermal expansion coefficients are further arranged, and the longitudinal displacement mode of the suspension hot plate is changed through the deformed cantilever beam after being heated, so that the heat exchange distance of the vacuum sensor is shortened, the upper measurement limit of the vacuum sensor is expanded upwards, namely the vacuum sensor provided by the embodiment of the invention can measure the vacuum degree under lower and higher air pressure, and the application range of the vacuum sensor is widened.
In one example, as shown in fig. 1 and 2, the vacuum sensor may further include a venting cover 13. The gas permeable cover 13 is disposed on the base 11 at least above the suspension structure 12. A cavity 14 is provided between the ventilation cover 13 and the suspension structure 12. It should be understood that, in the case that the vacuum sensor further includes the ventilation cover 13, if the ventilation cover 13 is used as a heat exchanging heat sink of the suspension heat plate 121, the volume of the heat exchanging heat sink can be increased, and the gas heat exchanging sensitivity between the suspension heat plate 121 and the ventilation cover 13 can be improved, so that the accuracy of the output measurement structure of the vacuum sensor can be improved, and the working performance of the vacuum sensor can be improved. Further, the ventilation cover 13 may be a cover having a ventilation hole formed therein. Alternatively, the gas-permeable cover 13 may be a cover that is in open connection with the base 11. Based on this, the cavity 14 is an open cavity, and the external air can enter the cavity 14.
Specifically, the shape and specification of the ventilation cover body can be set according to the shape and specification of the groove formed on the substrate and actual requirements. In addition, under the condition that the ventilation cover body is used as a heat exchange heat sink of the suspension hot plate, the depth of the cavity between the ventilation cover body and the suspension hot plate determines the size of the heat exchange distance of the vacuum sensor, so that the measurement range of the vacuum sensor is influenced, and therefore the depth of the cavity can be determined according to the requirements of an actual application scene on the measurement range of the vacuum sensor and an actual manufacturing process. For example: the depth of the cavity may be 30 μm to 50 μm. Furthermore, the ventilation cover body can be arranged on the substrate in a bonding, inlaid, bonding and other modes. When the ventilation cover body is bonded on the substrate, the ventilation cover body can be fastened and connected on the substrate, the structural reliability of the vacuum sensor is improved, and meanwhile, the distance between the upper surface of the suspension hot plate and the inner surface of the ventilation cover body can be shortened. Under the condition that the ventilation cover body is used as a heat exchange heat sink of the suspension hot plate, the distance between the upper surface of the suspension hot plate and the inner surface of the ventilation cover body is shortened, so that the heat exchange distance of the vacuum sensor is shortened, and the pressure P of a conversion point of the vacuum sensor can be improved 0 Further, the sensitivity of the vacuum sensor and the upper limit of vacuum measurement can be improved.
The material of the ventilation cover body can be set according to actual requirements, and is not particularly limited here. For example: the material of the ventilation cover body can be silicon, metal, silicon carbide and other materials.
As described above, after the cantilever beam is heated, the cantilever beam is deformed due to unequal thermal expansion between the heating portion and the supporting portion. It is conceivable that the directions in which the cantilever beam deforms are different when the relative positional relationship between the heating portion and the supporting portion and the thermal expansion coefficients of the materials of the heating portion and the supporting portion are different. Correspondingly, the direction of longitudinal displacement of the suspended hot plate is changed by the deformed cantilever beam. Based on this, because in the case that the vacuum sensor further comprises a venting cover, both the venting cover and the substrate can act as heat exchange heat sinks for the suspended hotplate. And the heat exchange distance of the vacuum sensor is the vertical distance between the suspended hot plate and the heat exchange heat sink, so the relative position between the heating part and the supporting part can be set according to the position of the heat exchange heat sink, and the heat exchange distance of the vacuum sensor is shortened when the vacuum sensor works. The following describes the positional relationship between the heating portion and the supporting portion in two cases according to the difference of heat exchange heat sinks of the suspension heat plate:
in one example, as shown in fig. 3, when the substrate 11 is used as a heat exchanging heat sink for the suspension hotplate 121, the heat exchanging interval is a vertical distance between the lower surface of the suspension hotplate 121 and the bottom surface of the groove 111. In this case, the heating portion 1222 is located at a side of the supporting portion 1221 away from the substrate 11, and the thermal expansion coefficient of the material of the heating portion 1222 is greater than that of the material of the supporting portion 1221. Or, the heating portion 1222 is located at a side of the supporting portion 1221 away from the air permeable cover 13, and the thermal expansion coefficient of the material of the heating portion 1222 is smaller than that of the material of the supporting portion 1221.
In the practical application process, when the substrate is used as a heat exchange heat sink of the suspension hot plate, the heat exchange distance is the vertical distance between the lower surface of the suspension hot plate and the bottom surface of the groove. Under the condition, when the heating part is positioned at one side of the supporting part far away from the substrate and the thermal expansion coefficient of the material of the heating part is larger than that of the material of the supporting part, after the heating part heats the corresponding cantilever beam, the thermal expansion amount of the heating part is larger than that of the supporting part, so that the cantilever beam warps downwards, the heating part can drive the suspension hot plate to move towards the direction close to the bottom surface of the groove in a mode of pulling the cantilever beam downwards, and the vertical distance between the lower surface of the suspension hot plate and the bottom surface of the groove is shortened, so that the heat exchange distance is reduced.
When the heating part is positioned at one side of the supporting part far away from the ventilation cover body, and the thermal expansion coefficient of the material of the heating part is smaller than that of the material of the supporting part, after the cantilever beam is heated, the thermal expansion amount of the heating part is smaller than that of the supporting part, so that the cantilever beam is warped downwards, and the suspension hot plate can be driven to move towards the bottom surface close to the groove in a mode that the supporting part pulls the cantilever beam downwards, so that the reduction of the heat exchange interval is realized.
In another example, as shown in fig. 3, when the vacuum sensor further includes the ventilation cover 13 and the ventilation cover 13 is used as a heat exchanging heat sink of the suspension heat plate 121, the heat exchanging interval is a vertical distance between the upper surface of the suspension heat plate 121 and the inner side surface of the ventilation cover 13. In this case, the heating portion 1222 is located at a side of the supporting portion 1221 away from the ventilation cover 13, and the thermal expansion coefficient of the material of the heating portion 1222 is larger than that of the material of the supporting portion 1221. Or, the heating portion 1222 is located at a side of the supporting portion 1221 away from the substrate 11, and a thermal expansion coefficient of a material of the heating portion 1222 is smaller than a thermal expansion coefficient of a material of the supporting portion 1221.
In the practical application process, when the ventilation cover body is used as a heat exchange heat sink of the suspension hot plate, the heat exchange distance is the vertical distance between the upper surface of the suspension hot plate and the inner side surface of the ventilation cover body. Under the condition, when the heating part is positioned at one side of the supporting part far away from the ventilation cover body, and the thermal expansion coefficient of the material of the heating part is larger than that of the material of the supporting part, after the heating part heats the corresponding cantilever beam, the thermal expansion amount of the heating part is larger than that of the supporting part, so that the cantilever beam is warped upwards, the heating part can drive the suspension hot plate to move towards the direction close to the inner side surface of the ventilation cover body in a mode of pushing the cantilever beam upwards, the vertical distance between the upper surface of the suspension hot plate and the inner side surface of the ventilation cover body is shortened, and the heat exchange distance is reduced.
When the heating part is positioned at one side of the supporting part far away from the substrate, and the thermal expansion coefficient of the material of the heating part is smaller than that of the material of the supporting part, after the heating part heats the corresponding cantilever beam, the thermal expansion amount of the heating part is smaller than that of the supporting part, so that the cantilever beam is warped upwards, and the suspension hot plate can be driven to move towards the direction close to the inner side surface of the ventilation cover body in a mode that the supporting part pushes the cantilever beam upwards, so that the heat exchange distance is reduced.
In one example, as shown in fig. 3, the heating portion 1222 may be a conductive heating wire. In this case, when the vacuum sensor is in an operating state, the cantilever beam 122 including the conductive heating wire may be heated by energizing the conductive heating wire. Because the structure of the conductive heating wire is simpler, the manufacturing difficulty of the vacuum sensor can be reduced.
Specifically, the distribution condition of the conductive heating wires on the supporting portion can be set according to actual requirements. For example, as shown in fig. 3, the above-mentioned conductive heating wires may be distributed on the support portion 1221 in a serpentine structure. Both ends of the conductive heating wire are disposed at the same side of the support 1221. At this time, the conductive heating wires of the snake-shaped structure may be uniformly distributed on the supporting portion 1221, so that each region of the cantilever beam 122 may be uniformly heated when the vacuum sensor works, so that the heated temperatures of each region of the cantilever beam 122 are approximately the same, and thus the cantilever beam 122 is ensured to warp in the corresponding direction after being heated, the deformation amount of the heated cantilever beam 122 is increased, and the degree of shortening the heat exchange distance is increased, so that the upper measurement limit of the vacuum sensor is further extended upwards. In addition, when the two ends of the same conductive heating wire are arranged on the same side of the supporting portion 1221, the conductive heating wire is conveniently electrified through an external power supply device, and the use difficulty of the vacuum sensor is reduced.
In one example, as shown in fig. 3, the support 1221 may include a first support section 12211 and a second support section 12212 coupled together. The first support section 12211 has an angle α between the axial direction and the axial direction of the second support section 12212 of 0 ° < α < 180 °. The end of the first support section 12211 remote from the second support section 12212 is connected to the suspended platen 121. The end of the second support section 12212 remote from the first support section 12211 is connected to the base 11. The heating portion 1222 is disposed on the second support section 12212.
It is noted that an included angle is formed between the axial direction of the first support section and the axial direction of the second support section, and the two support sections form a folded structure. Because fracture toughness of the folded structure is greater than that of the linear structure, the support part comprises the first support section and the second support section, and the heating part is arranged on the second support section, after the cantilever beam is heated by the heating part, the fracture risk of the cantilever beam caused by deformation can be reduced, the structural stability of the vacuum sensor is improved, and the service life of the vacuum sensor is prolonged.
Specifically, the included angle α may be set according to actual requirements. For example: as shown in fig. 3, the included angle α may be 90 °. At this time, the support portion 1221 is an L-shaped support portion. In this case, the L-shaped support portion has high fracture toughness, so that the L-shaped support portion can reduce the space occupied by the L-shaped support portion between the suspended hot plate 121 and the substrate 11 while preventing the cantilever beam 122 from being broken during deformation, in the case that the length of the first support section 12211 and the length of the second support section 12212 are unchanged, which is advantageous for miniaturization of the vacuum sensor.
Of course, the support portion may be a folded support portion or a linear support portion, in addition to the L-shaped support portion, so long as the support portion can be applied to the vacuum sensor provided in the embodiment of the present invention.
In one example, as shown in FIG. 3, at least two cantilever beams 122 are symmetrically disposed about the center of the suspended hotplate 121. In this case, the suspended hot plate 121 suspended above the groove 111 by the at least two cantilever beams 122 may be uniformly stressed, improving structural stability of the vacuum sensor. Moreover, after the cantilever beams 122 are deformed by heating, the longitudinal displacement of each region of the suspension hot plate 121 can be approximately the same by at least two cantilever beams 122 symmetrically arranged about the center of the suspension hot plate 121, so that the surface of the suspension hot plate 121 can be parallel to the surface of the substrate 11 before and after moving, the accuracy of the output measurement result of the vacuum sensor is improved, and the measurement accuracy of the vacuum sensor is improved.
Specifically, the positional relationship between the at least two cantilever beams and the suspension hot plate can be set according to the shape and actual requirements of the suspension hot plate. For example: as shown in fig. 3, when the suspension hotplate 121 is rectangular and the suspension structure 12 includes four cantilever beams 122, the four cantilever beams 122 may be disposed on four sides of the rectangular suspension hotplate 121, respectively, and symmetrically disposed about the center of the suspension hotplate 121.
In one example, as shown in fig. 1 to 3, the above-described suspension hotplate 121 has a support film 1211, and a heating element 1212 and a first temperature measuring element 1213 provided within the support film 1211. The heating element 1212 is used to heat the support film 1211. The first temperature measuring member 1213 is used for measuring the temperature of the support film 1211.
Specifically, the shape and structure of the support film may be set with reference to the shape and structure of the suspension hot plate, and the material of the support film may be set with reference to the material of the support portion, which is not described herein. For the heating member, the heating member may be any member capable of heating the support film. For example: the heating element may be a heating resistor. The heating resistor may be made of a metal material capable of conducting electricity, such as platinum, aluminum, or copper. The first temperature measuring member may be any element capable of measuring the temperature of the support film, such as a temperature measuring resistor, and is not particularly limited herein. When the first temperature measuring element is a temperature measuring resistor, the first temperature measuring element can measure the temperature of the support film through the characteristic that the resistance value of the first temperature measuring element increases along with the temperature increase of the support film. The temperature measuring resistor can be made of metal materials such as platinum, titanium, aluminum or copper, and can also be doped silicon. Alternatively, the first temperature measuring element may be a temperature sensitive diode or the like.
In one example, as shown in fig. 1 to 3, the suspension structure 12 further includes at least two sets of connection lines (not shown) disposed at least within the support membrane 1211 and the support 1221. Each set of connection wires is electrically connected to a respective heating element 1212 or a respective first temperature measuring element 1213.
Specifically, the material of the connecting wire may be a metal material capable of conducting electricity, such as platinum, gold, silver, copper, aluminum, and the like. Each group of connecting wires can lead out the two ends of the heating element or the first temperature measuring element which are electrically connected with the connecting wires, so that the heating element is convenient to supply power, and the measuring result of the first temperature measuring element is convenient to read.
The embodiment of the invention also provides a vacuum gauge which comprises the vacuum sensor provided by the embodiment.
Compared with the prior art, the vacuum gauge provided by the embodiment of the invention has the same beneficial effects as the vacuum sensor provided by the embodiment, and the description is omitted here.
In the above description, technical details of patterning, etching, and the like of each layer are not described in detail. Those skilled in the art will appreciate that layers, regions, etc. of the desired shape may be formed by a variety of techniques. In addition, to form the same structure, those skilled in the art can also devise methods that are not exactly the same as those described above. In addition, although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (10)
1. A vacuum sensor, comprising:
the substrate is provided with a groove;
and a suspension structure disposed above the recess; the suspension structure comprises a suspension hot plate and at least two cantilever beams; the suspension hot plate is connected with the substrate through at least two cantilever beams; each cantilever beam is provided with a supporting part and a heating part arranged on the supporting part; the thermal expansion coefficient of the material of the heating part is different from that of the material of the supporting part; the heating part is used for heating the corresponding cantilever beam when the vacuum sensor is in a working state so as to shorten the heat exchange distance of the vacuum sensor; the suspension hot plate is provided with a supporting film, a heating piece and a first temperature measuring piece, wherein the heating piece and the first temperature measuring piece are arranged in the supporting film; the heating piece is used for heating the support film; the first temperature measuring piece is used for measuring the temperature of the support film.
2. The vacuum sensor of claim 1, further comprising a venting cover; the ventilation cover body is arranged on the substrate and is at least positioned above the suspension structure; a cavity is arranged between the ventilation cover body and the suspension structure.
3. The vacuum sensor according to claim 2, wherein in the case where the heat exchange interval is a vertical distance between a lower surface of the suspension hot plate and a bottom surface of the groove, the heating portion is located at a side of the supporting portion away from the substrate, and a thermal expansion coefficient of a material of the heating portion is greater than a thermal expansion coefficient of a material of the supporting portion; or, the heating part is positioned at one side of the supporting part far away from the ventilation cover body, and the thermal expansion coefficient of the material of the heating part is smaller than that of the material of the supporting part;
when the heat exchange distance is the vertical distance between the upper surface of the suspension hot plate and the inner side surface of the ventilation cover body, the heating part is positioned at one side of the supporting part far away from the ventilation cover body, and the thermal expansion coefficient of the material of the heating part is larger than that of the material of the supporting part; or, the heating part is located at one side of the supporting part away from the substrate, and the thermal expansion coefficient of the material of the heating part is smaller than that of the material of the supporting part.
4. The vacuum sensor of claim 2, wherein the gas permeable cover is bonded to the substrate.
5. The vacuum sensor of claim 1, wherein the heating portion is an electrically conductive heating wire.
6. The vacuum sensor according to claim 1, wherein the support is made of at least one of silicon oxide, silicon nitride, silicon, aluminum oxide, magnesium oxide, and silicon carbide; the heating part is made of aluminum, gold, titanium, copper, tin, tungsten, molybdenum, chromium or platinum.
7. The vacuum sensor of claim 1, wherein the support comprises a first support section and a second support section connected together; an included angle alpha is formed between the axial direction of the first support section and the axial direction of the second support section, and the included angle alpha is more than 0 degrees and less than 180 degrees;
one end of the first support section, which is far away from the second support section, is connected with the suspension hot plate; one end of the second support section, which is far away from the first support section, is connected with the substrate; the heating portion is disposed on the second support section.
8. The vacuum sensor of claim 1, wherein the support is an L-shaped support, a reverse-turn support, or a straight support; and/or the number of the groups of groups,
at least two cantilever beams are symmetrically arranged about the center of the suspension hot plate; and/or the number of the groups of groups,
the base comprises a substrate and a second temperature measuring piece arranged on the substrate; the groove is formed in the substrate; the second temperature measuring piece is used for measuring the temperature of the testing environment.
9. The vacuum sensor of claim 1, wherein the suspension structure further comprises at least two sets of connection lines disposed within the support membrane and the support portion; each group of connecting wires is electrically connected with the corresponding heating element or the corresponding first temperature measuring element.
10. A vacuum gauge comprising the vacuum sensor of any one of claims 1 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5528939A (en) * | 1995-03-21 | 1996-06-25 | Martin; Jacob H. | Micromechanical pressure gauge having extended sensor range |
| JP5745205B2 (en) * | 2008-08-22 | 2015-07-08 | 木村 光照 | Thermal conductivity type barometric sensor using heating excitation |
| US8195013B2 (en) * | 2009-08-19 | 2012-06-05 | The United States Of America, As Represented By The Secretary Of The Navy | Miniature fiber optic temperature sensors |
| GB2491806B (en) * | 2011-05-25 | 2013-07-10 | Microvisk Ltd | Apparatus and method for measuring properties of a fluid |
| CN103424224A (en) * | 2013-07-24 | 2013-12-04 | 无锡微奇科技有限公司 | Micro-machined vacuum sensor |
| CN104931193A (en) * | 2014-03-19 | 2015-09-23 | 北京大学 | MEMS Pirani gauge with reference vacuum chamber |
| CN106404826B (en) * | 2016-10-24 | 2019-03-22 | 河海大学 | A kind of thermal-expansion coefficient of polycrystalline silicon thin film extracting method based on resonance characteristic |
| CN207763855U (en) * | 2017-12-19 | 2018-08-24 | 歌尔科技有限公司 | Pressure sense die and pressure sensor |
| CN108387341A (en) * | 2018-04-12 | 2018-08-10 | 昆山光微电子有限公司 | Micro vacuum meter and its working method |
| CN209878208U (en) * | 2019-04-01 | 2019-12-31 | 上海圭革智能传感技术有限公司 | MEMS Pirani vacuum gauge |
| CN210603717U (en) * | 2019-11-19 | 2020-05-22 | 川北真空科技(北京)有限公司 | Film vacuum gauge |
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