Silicon resonant temperature and pressure sensor and method of manufacturing the same

Abstract

The present disclosure provides a silicon resonant temperature and pressure sensor and a preparation method thereof. The silicon resonant temperature and pressure sensor comprises a pressure sensing layer, a resonant layer and a bottom silicon layer connected in sequence. The resonant layer comprises a cover plate and a resonant assembly. The resonant assembly comprises a resonant main beam, a first resonant auxiliary beam, a fixed comb, a second resonant auxiliary beam and a temperature resonant beam. The cover plate is arranged corresponding to a silicon island. The resonant main beam is connected to the cover plate and the first resonant auxiliary beam. The first resonant auxiliary beam and the fixed comb form a first electrostatic comb pair. The fixed comb and the second resonant auxiliary beam form a second electrostatic comb pair. The second resonant auxiliary beam is connected to the temperature resonant beam. Periodic driving signals are loaded to the first electrostatic comb pair and the second electrostatic comb pair respectively. The first resonant auxiliary beam drives the resonant main beam to periodically vibrate. The second resonant auxiliary beam drives the temperature resonant beam to periodically vibrate. The resonant frequency changes of the first resonant auxiliary beam and the second resonant auxiliary beam are detected to measure the to-be-measured pressure and the to-be-measured temperature respectively.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure belong to the technical field of pressure sensors, and particularly relate to a silicon resonant temperature and pressure sensor and a preparation method thereof. BACKGROUND

[0002] In related technologies, the frequency characteristics of a silicon resonator are not only sensitive to pressure, but also easily affected by environmental temperature changes, that is, there is a significant "temperature drift" phenomenon. Changes in temperature will cause changes in physical parameters such as the elastic modulus and the thermal expansion coefficient of silicon material, thereby causing the drift of the resonant frequency, which seriously interferes with the accurate extraction of the pressure signal. The current mainstream solution is to use an additional, independent temperature sensor (such as a thermistor) for temperature compensation. However, this discrete component solution has problems such as space layout, thermal coupling lag, and complex calibration, making it difficult to achieve instantaneous and accurate temperature measurement at the same point, thereby limiting the accuracy and reliability of the final pressure measurement. SUMMARY

[0003] Embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a silicon resonant temperature and pressure sensor and a preparation method thereof.

[0004] The first aspect of the present disclosure provides a silicon resonant temperature and pressure sensor, which comprises a pressure sensing layer, a resonant layer and a bottom silicon layer connected in sequence.

[0005] Two pressure sensing grooves are respectively arranged on opposite sides of the pressure sensing layer, and a pressure sensing film is formed between the two pressure sensing grooves. A silicon island is arranged on the side of the pressure sensing film close to the resonant layer. A first accommodating groove is arranged on the pressure sensing layer.

[0006] The resonant layer comprises a cover plate and a resonant assembly. The resonant assembly comprises a resonant main beam, a first resonant auxiliary beam, a fixed comb tooth, a second resonant auxiliary beam and a temperature resonant beam. The cover plate is arranged corresponding to the silicon island. The resonant main beam is connected to the cover plate and the first resonant auxiliary beam. The first resonant auxiliary beam and the fixed comb tooth form a first electrostatic comb tooth pair. The fixed comb tooth and the second resonant auxiliary beam form a second electrostatic comb tooth pair. The second resonant auxiliary beam is connected to the temperature resonant beam. The cover plate, the resonant main beam and the first resonant auxiliary beam are arranged corresponding to the pressure sensing groove. The second resonant auxiliary beam and the temperature resonant beam are arranged corresponding to the first accommodating groove.

[0007] A second accommodating groove and a third accommodating groove are arranged on the bottom silicon layer. The second accommodating groove is arranged corresponding to the pressure sensing groove. The third accommodating groove is arranged corresponding to the first accommodating groove.

[0008] The first static comb teeth pair and the second static comb teeth pair are respectively loaded with periodic driving signals, the first resonant auxiliary beam drives the resonant main beam to periodically vibrate, and the second resonant auxiliary beam drives the temperature resonant beam to periodically vibrate. The resonant frequency change of the first resonant auxiliary beam is detected to measure the pressure to be measured, and the resonant frequency change of the second resonant auxiliary beam is detected to measure the temperature to be measured.

[0009] In some embodiments of the present disclosure, the pressure sensing groove is arranged in a spaced manner with the first accommodating groove.

[0010] In some embodiments of the present disclosure, the resonant layer comprises two cover plates and two groups of resonant assemblies, the two cover plates are arranged in a spaced manner along a first direction of the resonant layer, the two groups of resonant assemblies are arranged in a spaced manner along a second direction of the resonant layer, and the two groups of resonant assemblies are respectively connected to opposite sides of the two cover plates, and the first direction is perpendicular to the second direction.

[0011] In some embodiments of the present disclosure, along the second direction from the cover plate to the direction away from the cover plate, the resonant main beam, the first resonant auxiliary beam, the fixed comb teeth, the second resonant auxiliary beam and the temperature resonant beam are arranged in sequence.

[0012] In some embodiments of the present disclosure, the first resonant auxiliary beam is provided with a first movable comb teeth, and the second resonant auxiliary beam is provided with a second movable comb teeth, and the first movable comb teeth and the second movable comb teeth respectively form the first static comb teeth pair and the second static comb teeth pair with opposite sides of the fixed comb teeth.

[0013] In some embodiments of the present disclosure, the resonant main beam, the first resonant auxiliary beam, the second resonant auxiliary beam and the temperature resonant beam are respectively connected through the cross-arranged connecting beams.

[0014] In some embodiments of the present disclosure, the resonant layer further comprises a first piezoresistive beam and a second piezoresistive beam, the first piezoresistive beam is connected with the first resonant auxiliary beam, the resonant frequency change of the first piezoresistive beam is detected to obtain a pressure change value, the second piezoresistive beam is connected with the second resonant auxiliary beam, and the resonant frequency change of the second piezoresistive beam is detected to obtain a temperature change value.

[0015] In some embodiments of the present disclosure, two ends of each first resonant auxiliary beam are connected with two first piezoresistive beams, and two ends of each second resonant auxiliary beam are respectively connected with two second piezoresistive beams.

[0016] In some embodiments of the present disclosure, a buffer groove is arranged on the cover plate, so as to reduce the weight of the cover plate and improve the elastic deformation amount of the cover plate.

[0017] The second aspect of this disclosure provides a method for fabricating a silicon resonant temperature and pressure sensor, a method for fabricating the silicon resonant temperature and pressure sensor described in any of the above embodiments, the method comprising:

[0018] Step 1: Clean the pressure-sensitive layer for later use;

[0019] Step 2: Wet etching of the silicon island, pressure-sensitive groove, and first receiving groove on the back side of the pressure-sensitive layer;

[0020] Step 3: Wet etching of the pressure-sensitive grooves on the front side of the pressure-sensitive layer to form a pressure-sensitive film;

[0021] Step 4: Bond the back side of the pressure-sensitive layer to the resonant layer;

[0022] Step 5: Thin the resonant layer;

[0023] Step 6: Etch the resonant layer to form a cover plate, a resonant main beam, a first resonant secondary beam, fixed comb teeth, a second resonant secondary beam, a temperature resonant beam, a connecting beam, a first piezoresistive beam, and a second piezoresistive beam;

[0024] Step 7: Etch the bottom silicon layer on one side facing the resonant layer to form the second and third receiving trenches;

[0025] Step 8: Evaporate getter in the second containment tank of the bottom silicon layer;

[0026] Step 9: Bond the bottom silicon layer to the side of the resonant layer opposite to the pressure-sensitive layer;

[0027] Step 10: Etch electrode vias on the pressure-sensitive layer;

[0028] Step 11: Sputtering to form a solder pad within the electrode via.

[0029] According to the silicon resonant temperature and pressure sensor and its fabrication method according to the embodiments of this disclosure, a periodic driving signal is applied to the first electrostatic comb pair of the resonant layer, causing the first resonant secondary beam constituting the first electrostatic comb pair to vibrate periodically. The first resonant secondary beam drives the resonant main beam to vibrate periodically. When the pressure-sensitive membrane of the pressure-sensitive layer senses external pressure, the pressure-sensitive membrane transmits the external pressure signal to the cover plate through the silicon island. The cover plate transmits the external pressure signal to the first resonant secondary beam through the resonant main beam. The external pressure signal causes a change in the periodic signal of the first resonant secondary beam. By detecting the resonant frequency of the first resonant secondary beam, the external pressure sensed by the sensing membrane can be detected. A periodic driving signal is applied to the second electrostatic comb pair of the resonant layer, causing the second resonant secondary beam constituting the second electrostatic comb pair to vibrate periodically. The second resonant secondary beam drives the temperature resonant beam to vibrate periodically. When the temperature resonant beam senses a change in external temperature, the external temperature causes a change in the vibration frequency of the temperature resonant beam. The temperature resonant beam causes a change in the vibration frequency of the second resonant secondary beam. By detecting the resonant frequency of the second resonant secondary beam, the external temperature change sensed by the silicon resonant temperature and pressure sensor can be detected. The silicon resonant temperature and pressure sensor disclosed herein integrates a pressure detection section and a temperature detection section, which can simultaneously perform pressure checking and temperature detection, reduce the volume of the integrated structure of the pressure sensor and temperature sensor, reduce the temperature drift of the silicon resonant temperature and pressure sensor, and improve the stability and accuracy of the silicon resonant temperature and pressure sensor. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the assembly structure of the silicon resonant temperature and pressure sensor of the present invention;

[0031] Figure 2 for Figure 1 The diagram shows the disassembled structure of the silicon resonant temperature and pressure sensor.

[0032] Figure 3 for Figure 1 A front view of the pressure-sensitive layer is shown;

[0033] Figure 4 for Figure 1 A schematic diagram of the back of the pressure-sensitive layer is shown.

[0034] Figure 5 for Figure 1 Top view of the resonant layer shown;

[0035] Figure 6 for Figure 1 A perspective view of the resonant layer shown.

[0036] Figure 7 for Figure 1 A schematic diagram of the bottom silicon layer is shown;

[0037] Figure 8This is a simulation diagram showing the relationship between temperature and vibration frequency in an embodiment of the present invention;

[0038] Figure 9 This is a flowchart of the fabrication method of the silicon resonant temperature and pressure sensor of the present invention.

[0039] The labels in the attached diagram are as follows:

[0040] 100. Silicon resonant temperature and pressure sensor;

[0041] 10. Pressure-sensitive layer; 101. First pressure-sensitive groove; 102. Second pressure-sensitive groove; 103. Pressure-sensitive membrane; 104. Silicon island; 105. First receiving groove; 106. Electrode through hole; 107. Fixing hole;

[0042] 20. Resonant layer; 201. Resonant body; 202. Pad; 203. Cover plate; 204. Buffer groove; 205. Resonant main beam; 206. First resonant secondary beam; 207. Fixed comb teeth; 208. Second resonant secondary beam; 209. Temperature resonant beam; 210. Connecting beam; 211. Piezoresistive beam; 212. Second piezoresistive beam;

[0043] 30. Base silicon layer; 301. Second receiving tank; 302. Third receiving tank; 303. Evaporated getter layer. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this disclosure and are not intended to limit the disclosure. The described embodiments are some, but not all, of the embodiments of this disclosure. Based on the described embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this disclosure.

[0045] like Figures 1 to 7 As shown, a first aspect of this disclosure provides a silicon resonant temperature and pressure sensor 100, which includes a pressure-sensing layer 10, a resonant layer 20, and a bottom silicon layer 30 connected in sequence.

[0046] Two pressure-sensitive grooves are respectively provided on opposite sides of the pressure layer 10, and a pressure-sensitive film 103 is formed between the two pressure-sensitive grooves. A silicon island 104 is provided on the side of the pressure-sensitive film 103 near the resonant layer 20, and a first receiving groove 105 is provided on the pressure-sensitive layer 10.

[0047] The resonant layer 20 includes a cover plate 203 and a resonant assembly. The resonant assembly includes a main resonant beam 205, a first secondary resonant beam 206, fixed comb teeth 207, a second secondary resonant beam 208, and a temperature resonant beam 209. The cover plate 203 is correspondingly arranged with the silicon island 104. The main resonant beam 205 is connected to the cover plate 203 and the first secondary resonant beam 206. The first secondary resonant beam 206 and the fixed comb teeth 207 form a first electrostatic comb tooth pair. The fixed comb teeth 207 and the second secondary resonant beam 208 form a second electrostatic comb tooth pair. The second secondary resonant beam 208 is connected with the temperature resonant beam 209. The cover plate 203, the main resonant beam 205, and the first secondary resonant beam 206 are correspondingly arranged with pressure-sensitive grooves. The second secondary resonant beam 208 and the temperature resonant beam 209 are correspondingly arranged with the first receiving groove 105.

[0048] The bottom silicon layer 30 is provided with a second receiving groove 301 and a third receiving groove 302. The second receiving groove 301 is provided in relation to the pressure-sensitive groove, and the third receiving groove 302 is provided in relation to the first receiving groove 105.

[0049] Periodic driving signals are applied to the first electrostatic comb tooth pair and the second electrostatic comb tooth pair respectively. The first resonant secondary beam 206 drives the resonant main beam 205 to vibrate periodically, and the second resonant secondary beam 208 drives the temperature resonant beam 209 to vibrate periodically. The pressure to be measured is measured by detecting the change in the resonant frequency of the first resonant secondary beam 206, and the temperature to be measured is measured by detecting the change in the resonant frequency of the second resonant secondary beam 208.

[0050] According to the silicon resonant temperature and pressure sensor and its fabrication method of this disclosure, a periodic driving signal is applied to the first electrostatic comb pair of the resonant layer 20, causing the first resonant secondary beam 206 constituting the first electrostatic comb pair to vibrate periodically. The first resonant secondary beam 206 drives the resonant main beam 205 to vibrate periodically. When the pressure-sensing membrane 103 of the pressure-sensing layer 10 senses external pressure, the pressure-sensing membrane 103 transmits the external pressure signal to the cover plate 203 through the silicon island 104. The cover plate 203 transmits the external pressure signal to the first resonant secondary beam 206 through the resonant main beam 205. The external pressure signal causes a change in the periodic signal of the first resonant secondary beam 206. By detecting the first resonant... The resonant frequency of the secondary beam 206 can detect the external pressure sensed by the sensing membrane. A periodic driving signal is applied to the second electrostatic comb pair of the resonant layer 20, causing the second resonant secondary beam 208, which constitutes the second electrostatic comb pair, to vibrate periodically. The second resonant secondary beam 208 drives the temperature resonant beam 209 to vibrate periodically. When the temperature resonant beam 209 senses an external temperature change, the external temperature causes a change in the vibration frequency of the temperature resonant beam 209, which in turn causes a change in the vibration frequency of the second resonant secondary beam 208. By detecting the resonant frequency of the second resonant secondary beam 208, the external temperature change sensed by the silicon resonant temperature and pressure sensor 100 can be detected. The silicon resonant temperature and pressure sensor 100 of this disclosure integrates a pressure detection part and a temperature detection part, enabling simultaneous pressure checking and temperature detection. This reduces the volume of the integrated structure of the pressure sensor and temperature sensor, reduces the temperature drift of the silicon resonant temperature and pressure sensor 100, and improves the stability of the silicon resonant temperature and pressure sensor 100.

[0051] In addition, the cover plate 203, the resonant main beam 205, and the first resonant secondary beam 206 are all provided with pressure-sensing grooves in the pressure-sensing layer 10, and the pressure-sensing grooves are correspondingly provided with the second receiving groove 301 of the bottom silicon layer 30. That is, along the thickness direction of the silicon resonant temperature and pressure sensor 100, the cover plate 203, the resonant main beam 205, and the first resonant secondary beam 206 are all located between the pressure-sensing grooves and the second receiving groove 301, so as to ensure that the cover plate 203, the resonant main beam 205, and the first resonant secondary beam 206 have a certain vibration deformation space, and ensure the accuracy of the pressure detection of the silicon resonant temperature and pressure sensor 100. The second resonant sub-beam 208 and the temperature resonant beam 209 are both provided corresponding to the first receiving groove 105 of the pressure-sensing layer 10, and the first receiving groove 105 and the third receiving groove 302 are provided corresponding to each other. That is, along the thickness direction of the silicon resonant temperature and pressure sensor 100, the second resonant sub-beam 208 and the temperature resonant beam 209 are both located between the first receiving groove 105 and the third receiving groove 302, so as to ensure that the second resonant sub-beam 208 and the temperature resonant beam 209 have a certain vibration deformation space, and ensure the accuracy of temperature detection by the silicon resonant temperature and pressure sensor 100.

[0052] like Figure 3 , Figure 4As shown, in some embodiments of this disclosure, the pressure-sensing groove and the first receiving groove 105 are spaced apart to prevent the pressure-sensing portion of the pressure-sensing layer 10 from affecting the temperature-sensing portion, thereby improving the accuracy of temperature detection and pressure detection.

[0053] Specifically, the pressure-sensing grooves on the pressure-sensing layer 10 that are far from the resonant layer 20 are called the first pressure-sensing grooves 101, and the pressure-sensing grooves that are close to the resonant layer 20 are called the second pressure-sensing grooves 102.

[0054] like Figure 5 , Figure 6 As shown, in some embodiments of this disclosure, the resonant layer 20 includes two cover plates 203 and two sets of resonant components. The two cover plates 203 are spaced apart along a first direction of the resonant layer 20, and the two sets of resonant components are spaced apart along a second direction of the resonant layer 20. The two sets of resonant components are respectively connected to opposite sides of each cover plate 203, and the first direction is perpendicular to the second direction. Specifically, the cross-section of the resonant layer 20 perpendicular to its thickness direction is rectangular, the first direction is the width direction of the rectangle, and the second direction is the length direction of the rectangle. The two cover plates 203 are spaced apart about the width direction of the rectangle and are symmetrical about the center of the rectangle; the two sets of resonant components are spaced apart about the length of the rectangle and are symmetrical about the center of the rectangle. Through a completely symmetrical design, the structure has greater stability.

[0055] Correspondingly, two first receiving tanks 105 are symmetrically arranged on both sides of the pressure-sensing tank about the pressure-sensing tank. A third receiving tank 302 is symmetrically arranged on both sides of the second receiving tank 301 about the second receiving tank 301. Both the second receiving tank 301 and the third receiving tank 302 are provided with a vapor-deposited getter layer 303.

[0056] In some embodiments of this disclosure, the cover plate 203 is provided with a buffer groove 204. The extension direction of the buffer groove 204 is the same as the length direction of the resonant layer 20. The buffer groove 204 reduces the weight of the cover plate 203 and increases the elastic deformation of the cover plate 203.

[0057] In some embodiments of this disclosure, along the second direction from the cover plate 203 away from the cover plate 203, the resonant main beam 205, the first resonant secondary beam 206, the fixed comb teeth 207, the second resonant secondary beam 208, and the temperature resonant beam 209 are sequentially arranged. By placing the temperature resonant beam 209 at the position furthest from the first resonant main beam 205, the temperature resonant beam 209 and the resonant main beam 205 are isolated, preventing mutual interference between the isolated temperature resonant beam 209 and the resonant main beam 205, thereby improving the accuracy of temperature and pressure detection.

[0058] In some embodiments of this disclosure, a set of comb teeth is provided on each of the opposite sides of the fixed comb teeth 207. The first resonant sub-beam 206 is provided with a first movable comb tooth (not shown in the figure), and the second resonant sub-beam 208 is provided with a second movable comb tooth (not shown in the figure). The first movable comb tooth and the comb tooth on one side of the fixed comb teeth 207 form a first electrostatic comb tooth pair, and the second movable comb tooth and the comb tooth on the other side of the fixed comb teeth 207 form a second electrostatic comb tooth pair. By loading a periodic vibration signal onto the fixed comb teeth 207, the fixed comb teeth 207 cause the first resonant sub-beam 206 to vibrate periodically through the first electrostatic comb tooth pair, and the fixed comb teeth 207 cause the second resonant sub-beam 208 to vibrate periodically through the second electrostatic comb tooth pair.

[0059] Furthermore, the pressure-sensitive layer is provided with a fixing hole 107 extending through its thickness direction. The fixing hole 107 is positioned corresponding to the fixing comb tooth 207. A solder pad 202 is provided inside the fixing hole 107. The solder pad 202 is welded to the middle part of the fixing comb tooth 207 so that the fixing comb tooth 207 is fixedly connected to the pressure-sensitive layer 10.

[0060] In some embodiments of this disclosure, the resonant main beam 205 is connected to the first resonant secondary beam 206 by a set of cross-connecting beams 210, and the second resonant secondary beam 208 is connected to the temperature resonant beam 209 by another set of cross-connecting beams 210. The cross-connecting beams 210 improve the reliability of the connection between the resonant main beam 205 and the first resonant secondary beam 206, and between the temperature resonant beam 209 and the second resonant secondary beam 208, while also reducing the weight of the connecting beams 210.

[0061] In some embodiments of this disclosure, the resonant layer 20 further includes a first piezoresistive beam 211 and a second piezoresistive beam 212. The first piezoresistive beam 211 is connected to the first resonant sub-beam 206, and the pressure change value is obtained by detecting the change in the resonant frequency of the first piezoresistive beam 211. The second piezoresistive beam 212 is connected to the second resonant sub-beam 208, and the temperature change value is obtained by detecting the change in the resonant frequency of the second piezoresistive beam 212.

[0062] In some embodiments of this disclosure, each first resonant sub-beam 206 has two first piezoresistive beams 211 connected to both ends, and each second resonant sub-beam 208 has two second piezoresistive beams 212 connected to both ends. Specifically, the extension direction of the first resonant sub-beam 206 is the same as the width direction of the resonant layer 20, and each end of the first resonant sub-beam 206 is connected to two first piezoresistive beams 211. The two first piezoresistive beams 211 are symmetrically arranged about their respective first resonant sub-beams 206. The vibration frequency change of the first resonant sub-beam 206 is measured by measuring the two first piezoresistive beams 211. Specifically, the extension direction of the second resonant sub-beam 208 is the same as the width direction of the resonant layer 20, and each end of the second resonant sub-beam 208 is connected to two second piezoresistive beams 212. The two second piezoresistive beams 212 are symmetrically arranged about their respective second resonant sub-beams 208. The vibration frequency change of the second resonant sub-beam 208 is measured by measuring the two second piezoresistive beams 212.

[0063] In some embodiments of this disclosure, the pressure-sensitive layer 10 is provided with multiple sets of electrode through holes 106 corresponding to the positions, and the pressure-sensitive layer 10 and the resonant layer 20 are welded together by sputtering through multiple sets of motor holes to form solder pads 202.

[0064] In some embodiments of this disclosure, the resonant layer 20 further includes a resonant body 201, which is a rectangular plate structure. Multiple grooves are formed on the resonant body 201 to accommodate the cover plate and the resonant components. The two ends of the first resonant sub-beam 206 are respectively connected to the resonant body 201, and the two ends of the second resonant sub-beam 208 are respectively connected to the resonant body 201. The resonant layer 20 is bonded to the pressure-sensitive layer 10 and the bottom silicon layer 30 of the resonant body 201.

[0065] To achieve more accurate temperature measurement, this disclosure proposes an integrated temperature and pressure silicon resonant sensor. Based on electrostatic comb-pair drive, it innovatively proposes calibrating the entire temperature range using a temperature resonant beam 209. Since the temperature resonant beam 209 is not affected by the pressure conducted through the first pressure-sensing groove 101 on the front side, but only by the electrostatic driving force, the temperature detection function can be achieved by calibrating the linear relationship between the external temperature and the temperature resonant beam 209. It should be noted that in this embodiment, the correlation between the vibration frequency of the temperature resonant beam 209 and the external temperature is pre-calibrated. Specifically, the simulation data for the correlation between the vibration frequency of the temperature resonant beam 209 and the external temperature are as follows: Figure 8 As shown.

[0066] Pressure sensing principle:

[0067] The pressure-sensitive layer 10 is used to sense external loads by the first pressure-sensitive groove 101 on the front side. The pressure load causes the pressure membrane to deform, which in turn causes the silicon islands 104 arranged opposite to each other on the second pressure groove on the back side to deform. The silicon islands 104 are connected to the silicon island 104 cover plate 203 on the resonant layer 20 by silicon bonding.

[0068] External loads cause deformation of silicon island 104, which is transmitted to resonant main beam 205 through silicon island 104 cover plate 203. This causes resonant main beam 205 to bend and deform, resulting in changes in its stiffness and consequently, changes in its resonant frequency. The external pressure load can be measured by the frequency change of resonant main beam 205.

[0069] Resonant beam driving principle:

[0070] Resonant beams typically do not spontaneously vibrate to reach their resonant frequency, so an external driving source is often required to make the resonator vibrate. The electrostatic driving method used in this paper forms a first electrostatic comb pair with the first resonant sub-beam 206 and the fixed comb 207. By applying a periodic driving signal to the first resonant sub-beam 206 and the fixed comb 207, the first resonant sub-beam 206 will generate periodic vibration under the action of electrostatic force, which in turn drives the vibration of the resonant main beam 205. The vibration frequency will change with the change of the external load.

[0071] Principle of resonant frequency detection:

[0072] The resonant frequency signal in this paper is indirectly measured through a piezoresistive beam connected to the resonant structure. That is, the resonant beam drives the piezoresistive beam to vibrate at the same frequency, and the measured resistance of the piezoresistive beam will also change periodically at the same vibration frequency. By detecting the frequency of the change in the resistance of the piezoresistive beam, the vibration frequency of the resonator can be measured.

[0073] like Figure 9 As shown, the second aspect of this disclosure discloses a method for fabricating a silicon resonant temperature and pressure sensor 100, a method for fabricating the silicon resonant temperature and pressure sensor 100 described in any of the above embodiments, the method comprising:

[0074] Step 1: Clean the pressure-sensitive layer 10 for later use;

[0075] Step 2: Wet etching of the silicon island 104, pressure-sensitive groove and first receiving groove 105 on the back side of the pressure-sensitive layer 10;

[0076] Step 3: Wet etching of the pressure-sensitive grooves on the front side of the pressure-sensitive layer 10 to form a pressure-sensitive film 103;

[0077] Step 4: Bond the back side of the pressure-sensitive layer 10 to the resonant layer 20;

[0078] Step 5: Thin the resonant layer 20;

[0079] Step 6: Etch the resonant layer 20 to form a cover plate 203, a resonant main beam 205, a first resonant secondary beam 206, fixed comb teeth 207, a second resonant secondary beam 208, a temperature resonant beam 209, a connecting beam 210, a first piezoresistive beam 211, and a second piezoresistive beam 212.

[0080] Step 7: Etch the bottom silicon layer 30 on the side facing the resonant layer 20 to form the second receiving trench 301 and the third receiving trench 302;

[0081] Step 8: Deposit getter into the second receiving tank 301 of the bottom silicon layer 30;

[0082] Step 9: Bond the bottom silicon layer 30 to the side of the resonant layer 20 that is away from the pressure-sensitive layer 10;

[0083] Step 10: Etch electrode vias 106 on the pressure-sensitive layer 10;

[0084] Step 11: Sputtering to form a pad 202 within the electrode via 106.

[0085] The method for fabricating the silicon resonant temperature and pressure sensor 100 disclosed herein integrates a pressure detection part and a temperature detection part, enabling simultaneous pressure checking and temperature detection. This reduces the volume of the integrated structure of the pressure sensor and temperature sensor, reduces the temperature drift of the silicon resonant temperature and pressure sensor 100, and improves the stability of the silicon resonant temperature and pressure sensor 100.

[0086] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A silicon resonant temperature and pressure sensor, characterized in that, The silicon resonant temperature and pressure sensor comprises a pressure-sensing layer, a resonant layer, and a bottom silicon layer connected in sequence. Two pressure-sensing grooves are respectively formed on opposite sides of the pressure-sensing layer, and a pressure-sensing film is formed between the two pressure-sensing grooves. A silicon island is provided on the side of the pressure-sensing film near the resonant layer, and a first receiving groove is provided on the pressure-sensing layer. The resonant layer includes a cover plate and a resonant assembly. The resonant assembly includes a main resonant beam, a first secondary resonant beam, fixed comb teeth, a second secondary resonant beam, and a temperature resonant beam. The cover plate is correspondingly disposed to the silicon island. The main resonant beam connects the cover plate to the first secondary resonant beam. The first secondary resonant beam and the fixed comb teeth form a first electrostatic comb tooth pair. The fixed comb teeth and the second secondary resonant beam form a second electrostatic comb tooth pair. The second secondary resonant beam is connected to the temperature resonant beam. The cover plate, the main resonant beam, and the first secondary resonant beam are disposed corresponding to the pressure-sensing groove. The second secondary resonant beam and the temperature resonant beam are disposed corresponding to the first receiving groove. The bottom silicon layer is provided with a second receiving groove and a third receiving groove, the second receiving groove being provided corresponding to the pressure-sensing groove, and the third receiving groove being provided corresponding to the first receiving groove; Periodic drive signals are applied to the first electrostatic comb tooth pair and the second electrostatic comb tooth pair respectively. The first resonant secondary beam drives the resonant main beam to vibrate periodically, and the second resonant secondary beam drives the temperature resonant beam to vibrate periodically. The pressure to be measured is measured by detecting the change in the resonant frequency of the first resonant secondary beam, and the temperature to be measured is measured by detecting the change in the resonant frequency of the second resonant secondary beam. The resonant layer includes two cover plates and two sets of resonant components. The two cover plates are spaced apart along a first direction of the resonant layer, and the two sets of resonant components are spaced apart along a second direction of the resonant layer. The two sets of resonant components are respectively connected to opposite sides of the two cover plates. The first direction is perpendicular to the second direction. Along the second direction from the cover plate away from the cover plate, the resonant main beam, the first resonant secondary beam, the fixed comb teeth, the second resonant secondary beam, and the temperature resonant beam are arranged in sequence.

2. The silicon resonant temperature and pressure sensor according to claim 1, characterized in that, The pressure-sensing groove is spaced apart from the first receiving groove.

3. The silicon resonant temperature and pressure sensor according to claim 1, characterized in that, The first resonant secondary beam is provided with a first movable comb tooth, and the second resonant secondary beam is provided with a second movable comb tooth. The first movable comb tooth and the second movable comb tooth respectively form the first electrostatic comb tooth pair and the second electrostatic comb tooth pair with the opposite sides of the fixed comb tooth.

4. The silicon resonant temperature and pressure sensor according to claim 1, characterized in that, The resonant main beam is connected to the first resonant secondary beam, and the second resonant secondary beam is connected to the temperature resonant beam via cross-connecting beams.

5. The silicon resonant temperature and pressure sensor according to claim 1, characterized in that, The resonant layer further includes a first piezoresistive beam and a second piezoresistive beam. The first piezoresistive beam is connected to the first resonant sub-beam, and the pressure change value is obtained by detecting the change in the resonant frequency of the first piezoresistive beam. The second piezoresistive beam is connected to the second resonant sub-beam, and the temperature change value is obtained by detecting the change in the resonant frequency of the second piezoresistive beam.

6. The silicon resonant temperature and pressure sensor according to claim 5, characterized in that, Each of the first resonant sub-beams is connected to two of the first piezoresistive beams at both ends, and each of the second resonant sub-beams is connected to two of the second piezoresistive beams at both ends.

7. The silicon resonant temperature and pressure sensor according to claim 1, characterized in that, The cover plate is provided with a buffer groove that extends through its thickness direction.

8. A method for fabricating a resonant temperature and pressure sensor, used to fabricate the silicon resonant temperature and pressure sensor according to any one of claims 1 to 7, characterized in that, The method includes: Step 1: Clean the pressure-sensitive layer for later use; Step 2: Wet etching of the silicon island, pressure-sensitive groove, and first receiving groove on the back side of the pressure-sensitive layer; Step 3: Wet etching of the pressure-sensitive grooves on the front side of the pressure-sensitive layer to form a pressure-sensitive film; Step 4: Bond the back side of the pressure-sensitive layer to the resonant layer; Step 5: Thin the resonant layer; Step 6: Etch the resonant layer to form a cover plate, a resonant main beam, a first resonant secondary beam, fixed comb teeth, a second resonant secondary beam, a temperature resonant beam, a connecting beam, a first piezoresistive beam, and a second piezoresistive beam; Step 7: Etch the bottom silicon layer on one side facing the resonant layer to form the second and third receiving trenches; Step 8: Evaporate getter in the second containment tank of the bottom silicon layer; Step 9: Bond the bottom silicon layer to the side of the resonant layer opposite to the pressure-sensitive layer; Step 10: Etch electrode vias on the pressure-sensitive layer; Step 11: Sputtering to form a solder pad within the electrode via.

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