Thermoresistive Micro Sensor Device

Abstract

A thermoresistive micro sensor device includes a semiconductor chip; a through hole, which runs through the semiconductor chip from an upper side to a lower side; electrically conductive structures, wherein the middle section of each of the electrically conductive structures spans over the through hole at the upper side of the semiconductor chip; an electrically insulating arrangement for electrically insulating the electrically conductive structures and the semiconductor chip from each other, wherein the through hole runs through the electrically insulating arrangement; and a contact arrangement including contacts, wherein each of the contacts is electrically connected to one of the first end sections or one of the second end sections, so that electrical energy is fed to at least one of the electrically conductive structures to heat the respective electrically conductive structure, and so that an electrical resistance of one of the electrically conductive structures is measured at the contact arrangement.

Claims

1. A thermoresistive micro sensor device for a mass flow meter for measuring a mass flow of a fluid or for a pressure meter for measuring a pressure in a fluid, the thermoresistive micro sensor device comprising: a semiconductor chip having an upper side and a lower side; at least one through hole, which runs through the semiconductor chip from the upper side to the lower side; one or more electrically conductive structures, wherein each of the electrically conductive structures comprises a first end section, a second end section and a middle section being arranged between the first end section and the second end section, wherein the first end section and the second end section of each of the electrically conductive structures are mounted to the semiconductor chip so that the middle section of each of the electrically conductive structures spans over the through hole at the upper side of the semiconductor chip; an electrically insulating arrangement configured for electrically insulating the one or more electrically conductive structures and the semiconductor chip from each other, wherein the through hole runs through the electrically insulating arrangement; and a contact arrangement comprising a plurality of contacts, wherein each of the plurality of contacts is electrically connected to one of the first end sections or to one of the second end sections, so that electrical energy, which is supplied to the contact arrangement, is fed to at least one of the electrically conductive structures in order to heat the respective electrically conductive structure, and so that an electrical resistance of one of the electrically conductive structures may be measured at the contact arrangement, wherein in a top view a transverse width of the middle section of one of the electrically conductive structures increases from a central portion of the middle section to the first end section of the middle section and from the central portion to the second end section of the middle section.

2. The thermoresistive micro sensor device according to claim 1, wherein the one or more electrically conductive structures comprise an electrically conductive heating and sensing structure, wherein the electrical energy from the contact arrangement is fed to the electrically conductive sensing and heating structure, and wherein the electrical resistance, which may be measured at the contact arrangement, is an electrical resistance of the electrically conductive heating and sensing structure.

3. The thermoresistive micro sensor device according to claim 1, wherein the first end section of one of the electrically conductive structures is connected to a first contact of the contact arrangement and to a second contact of the contact arrangement, and wherein the second end section of the one of the electrically conductive structures is connected to a third contact of the contact arrangement and to a fourth contact of the contact arrangement.

4. The thermoresistive micro sensor device according to claim 1, wherein the through hole comprises a circular through hole.

5. The thermoresistive micro sensor device according to claim 1, wherein, in a plan view, the thermoresistive micro sensor device is symmetrical with respect to a vertical line of symmetry.

6. A thermoresistive micro sensor device for a mass flow meter for measuring a mass flow of a fluid or for a pressure meter for measuring a pressure in a fluid, the thermoresistive micro sensor device comprising: a semiconductor chip having an upper side and a lower side; at least one through hole, which runs through the semiconductor chip from the upper side to the lower side; one or more electrically conductive structures, wherein each of the electrically conductive structures comprises a first end section, a second end section and a middle section being arranged between the first end section and the second end section, wherein the first end section and the second end section of each of the electrically conductive structures are mounted to the semiconductor chip so that the middle section of each of the electrically conductive structures spans over the through hole at the upper side of the semiconductor chip; an electrically insulating arrangement configured for electrically insulating the one or more electrically conductive structures and the semiconductor chip from each other, wherein the through hole runs through the electrically insulating arrangement; and a contact arrangement comprising a plurality of contacts, wherein each of the plurality of contacts is electrically connected to one of the first end sections or to one of the second end sections, so that electrical energy, which is supplied to the contact arrangement, is fed to at least one of the electrically conductive structures in order to heat the respective electrically conductive structure, and so that an electrical resistance of one of the electrically conductive structures may be measured at the contact arrangement, wherein the one or more electrically conductive structures comprise a plurality of electrically conductive structures which are spaced in a horizontal direction apart from each other.

7. The thermoresistive micro sensor device according to claim 6, wherein the one or more electrically conductive structures comprise an electrically conductive heating and sensing structure, wherein the electrical energy from the contact arrangement is fed to the electrically conductive sensing and heating structure, and wherein the electrical resistance, which may be measured at the contact arrangement, is an electrical resistance of the electrically conductive heating and sensing structure.

8. The thermoresistive micro sensor device according to claim 6, wherein the first end section of one of the electrically conductive structures is connected to a first contact of the contact arrangement and to a second contact of the contact arrangement, and wherein the second end section of the one of the electrically conductive structures is connected to a third contact of the contact arrangement and to a fourth contact of the contact arrangement.

9. The thermoresistive micro sensor device according to claim 6, wherein the first end section of one of the electrically conductive structures is connected to a fifth contact of the contact arrangement and to a sixth contact of the contact arrangement.

10. The thermoresistive micro sensor device according to claim 6, wherein the through hole comprises a circular through hole.

11. The thermoresistive micro sensor device according to claim 6, wherein, in a plan view, the thermoresistive micro sensor device is symmetrical with respect to a vertical line of symmetry.

12. The thermoresistive micro sensor device according to claim 6, wherein, in a plan view, the thermoresistive micro sensor device is symmetrical with respect to a horizontal line of symmetry.

13. The thermoresistive micro sensor device according to claim 6, wherein the one or more electrically conductive structures comprise an electrically conductive heating structure and an electrically conductive sensing structure being different from the electrically conductive heating structure, wherein the electrical energy, which is supplied to the contact arrangement, is fed to the electrically conductive heating structure, and wherein the electrical resistance, which may be measured at the contact arrangement, is the electrical resistance of the electrically conductive sensing structure.

14. The thermoresistive micro sensor device according to claim 13, wherein an electrostatic actuator is configured for electrostatically deflecting the electrically conductive heating structure and/or the electrically conductive sensing structure so that a distance between the electrically conductive heating structure and the electrically conductive sensing structure may be changed by applying a first voltage to the electrostatic actuator.

15. The thermoresistive micro sensor device according to claim 13, wherein a piezoelectric actuator is configured for deflecting the electrically conductive heating structure and/or the electrically conductive sensing structure so that a distance between the electrically conductive heating structure and the electrically conductive sensing structure may be changed by applying a second voltage to the piezoelectric actuator.

16. The thermoresistive micro sensor device according to claim 13, wherein a thermomechanical actuator is configured for deflecting the electrically conductive heating structure and/or the electrically conductive sensing structure so that a distance between the electrically conductive heating structure and the electrically conductive sensing structure may be changed by applying a current to the thermomechanical actuator.

17. The thermoresistive micro sensor device according to claim 16, wherein the distance between the electrically conductive heating structure and the electrically conductive sensing structure is increased by applying the current to the thermomechanical actuator.

18. The thermoresistive micro sensor device according to claim 17, wherein the distance between the electrically conductive heating structure and the electrically conductive sensing structure is increased by a deformation of the electrically conductive heating structure.

19. The thermoresistive micro sensor device according to claim 18, wherein the deformation comprises a middle section deformation of the electrically conductive heating structure.

20. The thermoresistive micro sensor device according to claim 16, wherein a first distance between the electrically conductive sensing structure and the electrically conductive heating structure and a second distance between the electrically conductive heating structure and the thermomechanical actuator are the same in a mode of operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Embodiments of the present invention are described herein making reference to the appended drawings.

[0059] FIG. 1 shows a schematic top view of a first embodiment of a thermoresistive micro sensor device;

[0060] FIG. 2 shows a schematic cross-sectional side view of the first embodiment of the thermoresistive micro sensor device;

[0061] FIG. 3 shows a schematic top view of a second embodiment of a thermoresistive micro sensor device;

[0062] FIG. 4 shows a schematic top view of a third embodiment of a thermoresistive micro sensor device;

[0063] FIG. 5 shows a schematic top view of a fourth embodiment of a thermoresistive micro sensor device;

[0064] FIG. 6 shows a schematic top view of a fifth embodiment of a thermoresistive micro sensor device;

[0065] FIG. 7 shows a schematic top view of a sixth embodiment of a thermoresistive micro sensor device;

[0066] FIG. 8 shows a schematic top view of a seventh embodiment of a thermoresistive micro sensor device;

[0067] FIG. 9 shows a schematic top view of an eighth embodiment of a thermoresistive micro sensor device, wherein an electrostatic actuator is switched off;

[0068] FIG. 10 shows a schematic top view of the eighth embodiment of a thermoresistive micro sensor device, wherein the electrostatic actuator is switched on;

[0069] FIG. 11 shows an exemplary diagram showing normalized sensor responses for different distances between the electrically conductive heating structure and the electrically conductive sensing structure of the eighth embodiment of a thermoresistive micro sensor device;

[0070] FIG. 12 shows a schematic top view of a ninth embodiment of a thermoresistive micro sensor device;

[0071] FIG. 13 shows a schematic cross-sectional side view of the ninth embodiment of the thermoresistive micro sensor device;

[0072] FIG. 14 shows a schematic top view of a tenth embodiment of a thermoresistive micro sensor device;

[0073] FIG. 15 shows a schematic top view of an eleventh embodiment of a thermoresistive micro sensor device;

[0074] FIG. 16 shows an exemplary temperature distribution at a thermoresistive micro sensor device according to the eleventh embodiment;

[0075] FIG. 17 shows a schematic top view of a twelfth embodiment of a thermoresistive micro sensor device;

[0076] FIG. 18 shows a schematic top view of a thirteenth embodiment of a thermoresistive micro sensor device;

[0077] FIG. 19 shows a schematic top view of a fourteenth embodiment of a thermoresistive micro sensor device;

[0078] FIG. 20 shows a schematic top view of a fifteenth embodiment of a thermoresistive micro sensor device;

[0079] FIG. 21 shows a schematic cross-sectional side view of a sixteenth embodiment of the thermoresistive micro sensor device;

[0080] FIG. 22 shows a schematic top view of an embodiment of a mass flow meter comprising a thermoresistive micro sensor device; and

[0081] FIG. 23 shows a schematic top view of an embodiment of a pressure meter comprising a thermoresistive micro sensor device.

[0082] Equal or equivalent elements or elements with equal or equivalent functionality are denoted in the following description by equal or equivalent reference numerals.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0083] In the following description, a plurality of details is set forth to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form rather than in detail in order to avoid obscuring embodiments of the present invention. In addition, features of the different embodiments described hereinafter may be combined with each other, unless specifically noted otherwise.

[0084] FIG. 1 shows a schematic top view of a first embodiment of a thermoresistive micro sensor device 1 and FIG. 2 shows a schematic cross-sectional side view of the first embodiment of the thermoresistive micro sensor device 1.

[0085] The thermoresistive micro sensor device for a mass flow meter for measuring a mass flow of a fluid or for a pressure meter for measuring a pressure in a fluid, the thermoresistive micro sensor device 1 comprises

[0086] a semiconductor chip 2 having an upper side 3 and a lower side 4;

[0087] at least one through hole 5, which runs through the semiconductor chip 2 from the upper side 3 to the lower side 4;

[0088] one or more electrically conductive structures 6, wherein each of the electrically conductive structures 6 comprises a first end section 7, a second end section 8 and a middle section 9 being arranged between the first end section 7 and the second end section 8, wherein the first end section 7 and the second end section 8 of each of the electrically conductive structures 6 are mounted to the semiconductor chip 2 so that the middle section 9 of each of the electrically conductive structures 6 spans over the through hole 5 at the upper side 3 of the semiconductor chip 2;

[0089] an electrically insulating arrangement 10 configured for electrically insulating the one or more electrically conductive structures 6 and the semiconductor chip 2 from each other, wherein the through hole 5 runs through the electrically insulating arrangement 10; and

[0090] a contact arrangement 11 comprising a plurality of contacts 12, wherein each of the plurality of contacts 12 is electrically connected to one of the first end sections 7 or to one of the second end sections 8, so that electrical energy, which is supplied to the contact arrangement 11, is fed to at least one of the electrically conductive structures 6 in order to heat the respective electrically conductive structure 6, and so that an electrical resistance of one of the electrically conductive structures 6 may be measured at the contact arrangement 11.

[0091] According to some embodiments the one or more electrically conductive structures 6 comprise an electrically conductive heating and sensing structure 6, wherein the electrical energy from the contact arrangement 11 is fed to the electrically conductive sensing and heating structure 6, and wherein the electrical resistance, which may be measured at the contact arrangement 11, is an electrical resistance of the electrically conductive heating and sensing structure 6.

[0092] According to some embodiments the first end section 7 of one of the electrically conductive structures 6 is connected to a first contact 12.1 of the contact arrangement 11 and to a second contact 12.2 of the contact arrangement 11, and the second end section 8 of the one of the electrically conductive structures 6 is connected to a third contact 12.3 of the contact arrangement 11 and to a fourth contact 12.4 of the contact arrangement 11.

[0093] FIG. 1 and FIG. 2 show a simple layout for four-terminal sensing with a single heating wire in a schematic representation. The electrically conductive structure 6 is used for sensing and for heating. It is suspended above the through hole 5, supported (at the ends) by a membrane 10 manufactured from (thermally and electrically) isolating material. The contacts 12.1 and 12.2 are electrically connected to the first end section 7 and the contacts 12.3 and 12.4 are connected to the second and section 8 of the electrically conductive structure 6.

[0094] FIG. 3 shows a schematic top view of a second embodiment of a thermoresistive micro sensor device 1. The second embodiment is based on the first embodiment.

[0095] According to some embodiments in a top view a cross section 13 of the through hole 5 in the electrically insulating arrangement 10 is smaller than a cross section 14 of the through hole 5 in the semiconductor chip 2. By the reduced opening in the electrically insulating arrangement 10 a higher sensitivity may be achieved as the speed of the fluid is increased for a certain mass flow.

[0096] FIG. 4 shows a schematic top view of a third embodiment of a thermoresistive micro sensor device 1. The third embodiment is also based on the first embodiment.

[0097] According to some embodiments in a top view a transverse width TW of the middle section 9 of one of the electrically conductive structures 6 increases from a central portion of the middle section 9 to the first end section 7 of the middle section 9 and from the central portion to the second end section 8 of the middle section 9.

[0098] FIG. 5 shows a schematic top view of a fourth embodiment of a thermoresistive micro sensor device 1. The fourth embodiment is also based on the first embodiment.

[0099] According to some embodiments in a top view the middle section 9 of one of the electrically conductive structures 6 comprises a plurality of electrically conductive substructures 16 parallelly arranged to a direction from the first end section 7 of the one of the electrically conductive structures 6 to the second end section 8 of the one of the electrically conductive structures 6, wherein the electrically conductive sub-structures 16 are separated by one or more elongated openings 17.

[0100] FIG. 6 shows a schematic top view of a fifth embodiment of a thermoresistive micro sensor device 1. The fifth embodiment is also based on the first embodiment.

[0101] According to some embodiments the middle section 9 of the one of the electrically conductive structures 6 comprises at least one electrically insulating support element 18, which mechanically connects at least some of the electrically conductive substructures 16, and which spans at least over one of the elongated openings 17 at an angle to the direction from the first end section 7 of the one of the electrically conductive structures 6 to the second end section 8 of the one of the electrically conductive structures 6.

[0102] FIG. 7 shows a schematic top view of a sixth embodiment of a thermoresistive micro sensor device 1. The sixth embodiment is also based on the first embodiment.

[0103] According to some embodiments in a top view the middle section 9 of one of the electrically conductive structures 6 comprises a frame-like portion 19 having in a top view a frame-like shape. Shown is an exemplary layout with a ring-shaped heating structure to optimize the heat transfer to and from the fluid.

[0104] FIG. 8 shows a schematic top view of a seventh embodiment of a thermoresistive micro sensor device 1. The seventh embodiment is also based on the first embodiment.

[0105] According to some embodiments in a top view the middle section 9 of one of the electrically conductive structures 6 comprises a perforated portion 20 having in a top view a two-dimensional perforation comprising a plurality of through holes 21.

[0106] Shown here is an exemplary layout with a perforated membrane acting as the heating/sensing structure 6, to increase contact surface with the fluid and thus increase heat transfer. By shaping the holes and/or arranging the perforation density among the membrane, flow profiles can be integrated and weighted for measurements; featuring their thermal and flow gradients.

[0107] FIG. 9 shows a schematic top view of an eighth embodiment of a thermoresistive micro sensor device 1, wherein an electrostatic actuator 24 is switched off and FIG. 10 shows a schematic top view of the eighth embodiment of a thermoresistive micro sensor device 1, wherein the electrostatic actuator 24 is switched on.

[0108] According to some embodiments the one or more electrically conductive structures 6 comprise a plurality of electrically conductive structures 22, 23 which are spaced in a horizontal direction HD apart from each other.

[0109] According to some embodiments the one or more electrically conductive structures 6 comprise an electrically conductive heating structure 22 and an electrically conductive sensing structure 23 being different from the electrically conductive heating structure 22, wherein the electrical energy, which is supplied to the contact arrangement 11, is fed to the electrically conductive heating structure 22, and wherein the electrical resistance, which may be measured at the contact arrangement 11, is the electrical resistance of the electrically conductive sensing structure 23.

[0110] According to some embodiments an electrostatic actuator 24 is configured for electrostatically deflecting the electrically conductive heating structure 22 and/or the electrically conductive sensing structure 23 so that a distance DI between the electrically conductive heating structure 22 and the electrically conductive sensing structure 23 may be changed by applying a first voltage to the electrostatic actuator 24.

[0111] According to some embodiments a piezoelectric actuator is configured for deflecting the electrically conductive heating structure 22 and/or the electrically conductive sensing structure 23 so that a distance DI between the electrically conductive heating structure 22 and the electrically conductive sensing structure 23 may be changed by applying a second voltage to the piezoelectric actuator.

[0112] According to some embodiments a thermomechanical actuator is configured for deflecting the electrically conductive heating structure 22 and/or the electrically conductive sensing structure 23 so that a distance DI between the electrically conductive heating structure 22 and the electrically conductive sensing structure 23 may be changed by applying a current to the thermomechanical actuator.

[0113] The electrically conductive heating structure 22 is electrically connected to the contacts 12.6 and 12.9. The electrically conductive sensing structure 23 is electrically connected to the contacts 12.5 and 12.8. Further, the electrostatic actuator 24 is electrically connected to the contacts 12.7 and 12.10. By applying a first voltage to at least one of the contacts 12.7 and 12.10 the electrically conductive heating structure 22 may be deflected so that the distance DI between the electrically conductive heating structure 22 and the electrically conductive sensing structure 23 is changed. Different distances DI are in particular beneficial for sensitivity in different pressure ranges and thus increase total measurement range.

[0114] The electrostatic actuator 24 may be replaced by a piezoelectric actuator (not shown) or a thermomechanical actuator (not shown).

[0115] FIG. 11 shows an exemplary diagram showing normalized sensor responses for different distances between the electrically conductive heating structure 22 and the electrically conductive sensing structure 23 of the eighth embodiment of a thermoresistive micro sensor device 1.

[0116] The normalized sensor responses Ke/KO depending on the pressure p are shown for distances DI having the values d=100 m, d=1 μm and d=10 μm. With decreasing the distance DI between the electrically conductive heating structure 22 and the electrically conductive sensing structure 23 the detectable pressure range is shifted up. Vice versa, with increasing distance DI it is shifted down, so that a plurality pressure ranges may be covered.

[0117] FIG. 12 shows a schematic top view of a ninth embodiment of a thermoresistive micro sensor device 1 and FIG. 13 shows a schematic cross-sectional side view of the ninth embodiment of the thermoresistive micro sensor device 1.

[0118] According to some embodiments the one or more electrically conductive structures 6 comprise a plurality of electrically conductive structures 6 which are spaced in a vertical direction VD apart from each other.

[0119] In this embodiment the electrically conductive sensing structures 23.1 to 23.5 are arranged parallelly in a mechanical and an electrical sense. The electrically conductive sensing structures 23.1 to 23.5 are connected to the contacts 12.1 to 12.4 so that four-terminal sensing is possible. The electrically conductive heating structures 22.1 to 22.5 are also arranged parallelly in a mechanical and an electrical sense. They are electrically connected to the contacts 12.6 and 12.9 so that they can be heated by applying electrical energy to the contacts 12.6 and 12.9. The electrically conductive heating structures 22.1 to 22.5 and the electrically conductive heating structures 22.1 to 22.5 are arranged in such way that they are in the top view perpendicular to each other. However, we also could be arranged at an arbitrary angle with respect to each other. Exemplary a number of the electrically conductive heating structures 22.1 to 22.5 and the electrically conductive sensing structures 23.1 to 23.5 is five. However, the number can be adjusted. Exemplary two layers of electrically conductive structures 6, 22 and 23 are shown. However a person skilled in the art would understand that more or less layers could be used.

[0120] FIG. 14 shows a schematic top view of a tenth embodiment of a thermoresistive micro sensor device 1.

[0121] Here, two electrically conductive structures 6.1 and 6.2 are shown. Further, two reference sensing structures 25.1 and 25.2 are shown. The two electrically conductive structures 6.1 and 6.2 and the two reference sensing structures 25.1 and 24.2 are connected in such way that they form a Wheatstone bridge. The four terminals of the Wheatstone bridge are electrically connected to the contacts 12.11, 12.12, 12.13 and 12.14. The reference sensing structures 25.1 and 25.2 can be buried in the electrically insulating arrangement 10 or even in the semiconductor chip 2 in order to minimize thermal interaction with the environment.

[0122] FIG. 15 shows a schematic top view of an eleventh embodiment of a thermoresistive micro sensor device 1.

[0123] The exemplary layout comprises three electrically conductive structures 6 which comprise the electrically conductive heating structure 22 and two electrically conductive sensing structures 23.1 and 23.2. The latter two are arranged symmetrically with respect to the electrically conductive heating structure 22. The electrically conductive heating structure 22 is electrically connected to the contacts 12.16 and 12.19. The electrically conductive sensing structure 23.1 is electrically connected to the contacts 12.15 and 12.20 and the electrically conductive sensing structure 23.2 is connected to the contacts 12.17 and 12.18.

[0124] FIG. 16 shows an exemplary temperature distribution TD at a thermoresistive micro sensor device 1 according to the eleventh embodiment. It's apparent that the temperature distribution TD depends on the mass flow MV of the fluid.

[0125] FIG. 17 shows a schematic top view of a twelfth embodiment of a thermoresistive micro sensor device 1.

[0126] The embodiment shown here comprises two electrically conductive structures 6.1 and 6.2 which may be used for sensing and for heating. The electrically conductive structure 6.1 is connected to the contacts 12.22 and 12.23 and the electrically conductive structure 6.2 is connected to the contacts 12.21 and 12.24. An AC voltage may be applied between the electrically conductive structures 6.1 and 6.2 to deflect them symmetrically so that the output a signal which is modulated by the AC voltage. In this case the signal-to-noise ratio may be improved by AC band-pass filters. The frequency of the AC voltage may be the resonance frequency of the electrically conductive structures 6.1 and 6.2.

[0127] FIG. 18 shows a schematic top view of a thirteenth embodiment of a thermoresistive micro sensor device 1. The exemplary layout comprises three electrically conductive structures 6 which comprise the electrically conductive heating structure 22 and two electrically conductive sensing structures 23.1 and 23.2. The latter two are arranged symmetrically with respect to the electrically conductive heating structure 22. The electrically conductive heating structure 22 is electrically connected to the contacts 12.26 and 12.29. The electrically conductive sensing structure 23.1 is electrically connected to the contacts 12.25 and 12.30 and the electrically conductive sensing structure 23.2 is connected to the contacts 12.27 and 12.28. Heating power and sensing power are two independent parameters which may be optimized separately. The electrically conductive heating structure 22 is mechanically stiffer than the two electrically conductive sensing structures 23.1 and 23.2. If an AC voltage is applied to contacts 12.26 and 12.29, the two electrically conductive sensing structures 23.1 and 23.2 will be deflected periodically so that the output signal is modulated. In this case the signal-to-noise ratio may be improved by AC band-pass filters. The frequency of the AC voltage may be the resonance frequency of the electrically conductive sensing structures 23.1 and 23.2.

[0128] FIG. 19 shows a schematic top view of a fourteenth embodiment of a thermoresistive micro sensor device 1.

[0129] The exemplary layout comprises three electrically conductive structures 6 which comprise two electrically conductive heating structures 22.1 and 22.2 and the electrically conductive sensing structure 23. The first two are arranged symmetrically with respect to the electrically conductive sensing structure 23. The electrically conductive heating structure 22.1 is electrically connected to the contacts 12.33 and 12.34. The electrically conductive heating structure 22.2 is electrically connected to the contacts 12.31 and 12.36 and the electrically conductive sensing structure 23 is connected to the contacts 12.32 and 12.34. Heating power and sensing power are two independent parameters which may be optimized separately. The two electrically conductive heating structures 22.1 and 22.2 are mechanically stiffer than the electrically conductive sensing structure 23. If an AC voltage is applied between contacts 12.33 and 12.34 and between contacts 12.31 and 12.36, the electrically conductive sensing structure 23 will be deflected periodically so that the output signal is modulated. In this case the signal-to-noise ratio may be improved by AC band-pass filters. The frequency of the AC voltage may be the resonance frequency of the electrically conductive sensing structure 23.

[0130] FIG. 20 shows a schematic top view of a fifteenth embodiment of a thermoresistive micro sensor device 1.

[0131] Here, two electrically conductive sensing structures 23.1 and 23.2 are shown. Further, two reference sensing structures 25.1 and 25.2 are shown. The two electrically conductive sensing structures 23.1 and 23.2 and the two reference sensing structures 25.1 and 24.2 are connected in such way that they form a Wheatstone bridge. The four terminals of the Wheatstone bridge are electrically connected to the contacts 12.37, 12.38, 12.39 and 12.4o. The reference sensing structures 25.1 and 25.2 can be buried in the electrically insulating arrangement 10 or even in the semiconductor chip 2 in order to minimize thermal interaction with the environment. In this embodiment the sensing function is separated from the heating function. For the heating function an additional electrically conductive heating structure 22, which is stiffer than the two electrically conductive sensing structures 23.1 and 23.2, is provided. The electrically conductive heating structure 22 is electrically connected to the contacts 12.41 and 12.42. If an AC voltage is applied between contacts 12.41 and 12.42, the electrically conductive sensing structures 23.1 and 23.2 will be deflected periodically so that the output signal is modulated. In this case the signal-to-noise ratio may be improved by AC band-pass filters. The frequency of the AC voltage may be the resonance frequency of the electrically conductive sensing structures 23.1 and 23.2.

[0132] FIG. 21 shows a schematic cross-sectional side view of a sixteenth embodiment of the thermoresistive micro sensor device 1. Here, the plurality of electrically conductive structures 6 are shown, wherein each of the electrically conductive structure 6 is supported by a portion of the electrically insulating arrangement 10. It's well-known that the speed of the fluid which is guided through a through hole 5 has a maximum at the center of the through hole 5, it is if there are no obstacles in the flow path. In order to compensate this, the electrically conductive structure 6 are arranged in such way that in a center portion of the through hole 5 higher partial mass flow is possible than in a peripheral portion of the through hole 5.

[0133] All of the variants above can be stacked vertically for increased sensitivity as well as directionality of the flow measurement.

[0134] FIG. 22 shows a schematic top view of an embodiment of a mass flow meter 26 for measuring a mass flow of a fluid.

[0135] The mass flow meter 26 comprises

[0136] a thermoresistive micro sensor device 1 according to one of the claims 1 to 15;

[0137] an electrical energy supply unit 27 for supplying the electrical energy to the contact arrangement 11; and

[0138] a measuring unit 28 for measuring the electrical resistance at the contact arrangement 11;

[0139] wherein the measuring unit 28 is configured for measuring the mass flow MV of the fluid flowing through the through hole 5 depending on the electrical resistance.

[0140] FIG. 23 shows a schematic top view of an embodiment of a pressure meter for measuring a pressure in a fluid.

[0141] The pressure meter 29, the pressure comprises

[0142] a thermoresistive micro sensor device 1 according to one of the claims 1 to 15;

[0143] an electrical energy supply unit 27 for supplying the electrical energy to the contact arrangement 11; and

[0144] a measuring unit 28 for measuring the electrical resistance at the contact arrangement;

[0145] wherein the measuring unit 28 is configured for measuring the pressure PR of the fluid at the through hole 5 depending on the electrical resistance.

[0146] Embodiments may comprise one or more of the following features:

[0147] One or more (poly-silicon) heating/sensing structures are suspended completely exposed above a hole that runs vertically through the whole chip.

[0148] The sensing/heating structures are arranged side-by-side and/or above each other (in multiple, separate layers).

[0149] At least one of those sensing/heating structures is used for resistive/joule heating.

[0150] The fluid flow is guided through the hole in the chip and has to pass the sensing/heating structure(s).

[0151] The fluid transports thermal energy away from the heating structure(s).

[0152] The sensing structure(s) receive(s) a temperature change, which can be measured as a shift in resistance.

[0153] This disclosure proposes in particular the placement of several polysilicon heating and sensing structures above a hole in the substrate of a silicon chip, in particular leaving those structures completely exposed to fluid passing through perpendicular to the chip surface. The exposed heating/sensing structures exhibit a high sensitivity to temperature changes due to their low volume-to-surface-ratio as well as the small heat capacity caused by the low mass and good thermal insulation at the heating/sensing structure support. Due to the low fluidic resistance, the sensor exhibits a flow optimized measurement principle for low flow rates. This device can both be used as an anemometer for measuring mass flow of fluids, as well as a pressure meter for measuring a pressure in different ranges. MEMS structure capabilities can be used to vary/adjust the sensor in field measurements by using moveable mechanical structures (example pressure meter with electrostatic actuation).

[0154] While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.