Acceleration sensor and preparation method thereof

Abstract

The invention discloses an acceleration sensor and a preparation method thereof, and belongs to the technical field of semiconductors. The acceleration sensor comprises a base body, four induction resistors and a mass block, the four induction resistors are electrically connected to form a Wheatstone bridge structure, and when acceleration is provided in a detected direction, the four induction resistors can generate resistance changes under the acting force of the mass block, so that the acceleration in the detected direction is detected. The acceleration can be detected by measuring the voltage change condition of the two output ends in the equivalent circuit. According to the embodiment of the invention, the four induction resistors are electrically connected to form a Wheatstone bridge structure to calculate the acceleration, so that the influence of other environmental factors on a calculation result can be avoided, and the accuracy of the calculation result can be improved. Moreover, each of the four induction resistors comprises a nanowire structure, the size is smaller, the piezoresistive coefficient is larger, the sensitivity is higher, and the acceleration sensor has higher reliability in both low-temperature and high-temperature environments, so that the sensitivity and reliability of the acceleration sensor can be improved.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and in particular relates to an acceleration sensor and a method for preparing the same. Background Art

[0002] Traditional acceleration sensors are mostly based on the principles of piezoresistive effect, piezoelectric effect or capacitive effect, and are made of silicon materials. Boron doping is generally used as the piezoresistive material. The piezoresistive coefficient is small and the sensitivity is low. In low or high temperature environments, the temperature drift is too large and the sensor will fail.

[0003] How to improve the sensitivity of the acceleration sensor and improve the reliability of the acceleration sensor in high and low temperature environments has become a problem to be solved urgently in this field. Summary of the invention

[0004] The present application provides an acceleration sensor and a preparation method thereof, aiming to improve the sensitivity and reliability of the acceleration sensor.

[0005] In a first aspect, the present application provides an acceleration sensor, comprising a substrate, a plurality of inductive resistors and a mass block, wherein the plurality of inductive resistors comprises a first inductive resistor, a second inductive resistor, a third inductive resistor and a fourth inductive resistor, and the first inductive resistor, the second inductive resistor, the third inductive resistor and the fourth inductive resistor are respectively connected between the mass block and the substrate.

[0006] The plurality of sensing resistors all include a nanowire structure, and the first sensing resistor, the second sensing resistor, the third sensing resistor and the fourth sensing resistor are electrically connected to form a Wheatstone bridge structure.

[0007] In some embodiments, the acceleration sensor further includes a plurality of cantilever structures, the mass block includes a first end and a second end opposite to each other along a first direction, and the first direction is parallel to the plane where the substrate is located. The first end and the second end of the mass block are connected to the substrate through the cantilever structure respectively. The mass block further includes a third end and a fourth end opposite to each other along a second direction, the third end of the mass block is connected to the substrate through the first sensing resistor and the third sensing resistor, and the fourth end of the mass block is connected to the substrate through the second sensing resistor and the fourth sensing resistor, the second direction intersects with the first direction, and the second direction is parallel to the plane where the substrate is located, and the first sensing resistor and the third sensing resistor are located on the diagonal bridge arms of the Wheatstone bridge.

[0008] In some embodiments, along the first direction, the width of the sensing resistor ranges from 2 nm to 2000 nm.

[0009] In some embodiments, the acceleration sensor further includes a substrate, the base, multiple sensing resistors and the mass block are all arranged on the same side of the substrate, the substrate further includes a through cavity, and the orthographic projections of the multiple sensing resistors on the substrate are located within the range of the orthographic projection of the cavity on the substrate.

[0010] In some embodiments, the acceleration sensor further includes a substrate, which is disposed on a side of the substrate away from the base body, a surface of the substrate close to the substrate is provided with a groove, and the positive projections of the plurality of sensing resistors and the mass block on the substrate are located within the region where the groove is located.

[0011] In some embodiments, the sensing resistor further includes a gate disposed between a source and a drain of the sensing resistor.

[0012] In some embodiments, the nanowire structure also includes a stacked semiconductor layer and a barrier layer, the material of the semiconductor layer includes at least one of gallium nitride, gallium arsenide, or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide, or indium aluminum arsenide.

[0013] In a second aspect, an embodiment of the present application further provides a method for preparing an acceleration sensor, the method comprising forming a substrate, a plurality of inductive resistors and a mass block. The plurality of inductive resistors comprises a first inductive resistor, a second inductive resistor, a third inductive resistor and a fourth inductive resistor, and the first inductive resistor, the second inductive resistor, the third inductive resistor and the fourth inductive resistor are respectively connected between the mass block and the substrate. The plurality of inductive resistors all comprise a nanowire structure, and the first inductive resistor, the second inductive resistor, the third inductive resistor and the fourth inductive resistor are electrically connected to form a Wheatstone bridge structure.

[0014] In some embodiments, the preparation method of forming a substrate, a plurality of sensing resistors and a mass block includes the following steps S10 to S30: Step S10: forming a nanowire structure on a substrate.

[0015] Step S20: forming a source electrode and a drain electrode on one side of both ends of the nanowire structure away from the substrate to obtain a plurality of inductive resistors.

[0016] Step S30: etching the substrate to obtain a mass block and a base body, wherein the substrate includes a penetrating cavity, and the orthographic projections of the plurality of sensing resistors on the substrate are located within the region where the cavity is located.

[0017] In some embodiments, the preparation method further includes the following steps S40 to S50: Step S40: forming grooves on the surface of the substrate.

[0018] Step S50: bonding the substrate to the substrate, the substrate is located on a side of the substrate away from the nanowire structure, and the surface of the substrate with the groove is close to the substrate, and the positive projections of the multiple sensing resistors and the mass block on the substrate are located within the area where the groove is located.

[0019] In the embodiment provided in the present application, the acceleration sensor includes a substrate, a plurality of inductive resistors and a mass block, wherein the plurality of inductive resistors include four inductive resistors, and the four inductive resistors are respectively connected to the mass block and the substrate.

[0020] The first induction resistor, the second induction resistor, the third induction resistor and the fourth induction resistor are electrically connected to form a Wheatstone bridge structure. When the measured direction provides acceleration, the mass block will not move with the substrate due to inertia, so that the four induction resistors that play a connecting role will each undergo a slight deformation. After the four induction resistors are subjected to stress due to deformation, a change in resistance will occur under the piezoresistive effect. And the forces exerted on the four induction resistors are all generated by the same mass block, which can avoid errors caused by other factors. The magnitude of the acceleration can be calculated through the differential output of the circuit, and, compared to the method of measuring acceleration with a single induction resistor, in the embodiment of the present application, the four induction resistors are electrically connected to form a circuit structure for calculating the acceleration, which can avoid the influence of other environmental factors on the calculation results, which is conducive to improving the accuracy of the calculation results.

[0021] In addition, all four sensing resistors include nanowire structures, which are smaller in size, more obviously deformed when subjected to stress, and have higher sensitivity. Nanowire structures usually have a larger piezoresistance coefficient, and they have a quantum confinement effect at the nanoscale, which can amplify the change in the piezoresistance effect after strain. For example, the piezoresistance coefficient of silicon nanowires is two orders of magnitude higher than that of conventional silicon, and the resistance value changes more significantly under the same force, which can make the acceleration sensor have a higher sensitivity. And based on the nanowire structure, the sensing resistor works well in high and low temperature environments, which can improve the reliability of the acceleration sensor.

[0022] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 A top view of an acceleration sensor provided in an embodiment of the present application; Figure 2 for Figure 1 Equivalent circuit diagram of the acceleration sensor; Figure 3 for Figure 1 A cross-sectional view of the acceleration sensor along the section line AA'; Figure 4 A flow chart of a method for preparing an acceleration sensor provided in an embodiment of the present application; Figure 5~Figure 14A diagram of the steps for preparing an acceleration sensor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0025] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, ie, meaning "including, but not limited to."

[0026] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0027] When describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other.

[0028] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0029] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0030] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include deviations in shape due to, for example, manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0031] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0032] At present, traditional acceleration sensors are mostly based on the principles of piezoresistive effect, piezoelectric effect or capacitive effect, and are manufactured using silicon materials, and generally use boron doping as the piezoresistive material. Due to the physical properties of the material, traditional acceleration sensors have the problems of small piezoresistive coefficient and low sensitivity. In low or high temperature environments, the temperature drift is too large and the sensor will fail.

[0033] To solve at least one of the above problems, the present application provides an acceleration sensor, aiming to improve its sensitivity and reliability, such as Figure 1~Figure 3 As shown, Figure 1 A top view of an acceleration sensor provided in an embodiment of the present application, Figure 2 for Figure 1 Equivalent circuit diagram of the acceleration sensor. Figure 3 for Figure 1 Cross-sectional view of the acceleration sensor along section line AA'.

[0034] The acceleration sensor 10 includes a substrate 100, a plurality of sensing resistors and a mass block 101. The plurality of sensing resistors include a first sensing resistor 201, a second sensing resistor 202, a third sensing resistor 203 and a fourth sensing resistor 204, and the first sensing resistor 201, the second sensing resistor 202, the third sensing resistor 203 and the fourth sensing resistor 204 are connected between the mass block 101 and the substrate 100, respectively.

[0035] like Figure 2 As shown, the first sensing resistor 201, the second sensing resistor 202, the third sensing resistor 203 and the fourth sensing resistor 204 are electrically connected to form a Wheatstone bridge structure. Exemplarily, the Wheatstone bridge structure also includes a first input terminal Vin and a second input terminal GND, and a first output terminal Vout + and the second output terminal Vout- The source of the first sensing resistor 201 is electrically connected to the first input terminal Vin, and the drain of the first sensing resistor 201 is electrically connected to the first output terminal Vout. + The source of the second sensing resistor 202 is electrically connected, the drain of the second sensing resistor 202 is electrically connected to the second input terminal GND and the drain of the third sensing resistor 203, and the source of the third sensing resistor 203 is electrically connected to the second output terminal Vout. - The first sensing terminal 204 is electrically connected to the drain of the fourth sensing resistor 204 , and the source of the fourth sensing resistor 204 is electrically connected to the first input terminal Vin.

[0036] For example, Figure 2 As shown, the resistance of the first sensing resistor 201 is R1, the resistance of the second sensing resistor 202 is R2, the resistance of the third sensing resistor 203 is R3, and the resistance of the fourth sensing resistor 204 is R4. In a uniform or stationary state, that is, when no acceleration is provided, the first output terminal Vout + and the second output terminal Vout - The potential difference is .

[0037] When an acceleration is provided along the measured direction Y, the mass block 101 will not move with the substrate 100 due to inertia, and the four sensing resistors that play a connecting role will respectively undergo slight deformations. For example, the first sensing resistor 201 and the third sensing resistor 203 are respectively subjected to a stretching force. Under the piezoresistive effect, the resistance R1 of the first sensing resistor 201 and the resistance R3 of the third sensing resistor 203 change respectively. The second sensing resistor 202 and the fourth sensing resistor 204 are respectively subjected to a squeezing force. Under the piezoresistive effect, the resistance R2 of the second sensing resistor 202 and the resistance R4 of the fourth sensing resistor 204 change respectively. The forces on the four sensing resistors are all generated by the same mass block 101, which can avoid errors caused by other factors.

[0038] Exemplarily, the acceleration here can be a positive number or a negative number.

[0039] When acceleration is provided, the resistance change of the first sensing resistor 201 is recorded as , the resistance change of the second sensing resistor 202 is , the resistance change of the third sensing resistor 203 is , the resistance change of the fourth sensing resistor 204 is , since the magnitude of the force exerted by the mass block 101 on the corresponding inductive resistor is related to the magnitude of the acceleration, and the change in the resistance of the inductive resistor is related to the magnitude of the force it receives, based on this, the change in the resistance of the above four inductive resistors is related to the magnitude of the acceleration. Under this acceleration, the first output terminal Vout +and the second output terminal Vout - The potential difference is .

[0040] Based on this, by calibrating the first output terminal Vout + and the second output terminal Vout - The magnitude of acceleration can be detected by observing the change in the potential difference.

[0041] Compared with the method of measuring acceleration using a single sensing resistor, in the embodiment of the present application, four sensing resistors are electrically connected to form a Wheatstone bridge structure to calculate the acceleration, which can avoid the influence of other environmental factors on the change in the resistance value of the sensing resistor, and further avoid the influence of other environmental factors on the acceleration calculation results, which is beneficial to improving the accuracy of the calculation results.

[0042] In addition, the four sensing resistors all include nanowire structures, which are smaller in size, more obviously deformed when subjected to stress, and have higher sensitivity. Nanowire structures usually have a larger piezoresistance coefficient, and have a quantum confinement effect at the nanoscale, which can amplify the change in the piezoresistance effect after strain. For example, the piezoresistance coefficient of silicon nanowires is two orders of magnitude higher than that of conventional silicon piezoresistance coefficients, and the resistance value changes more significantly under the same force, thereby enabling the acceleration sensor 10 to have a higher sensitivity. Based on the nanowire structure, the sensing resistors work well in high and low temperature environments, thereby improving the reliability of the acceleration sensor 10.

[0043] In some embodiments, Figure 1 As shown, the acceleration sensor 10 further includes a plurality of cantilever structures 11, and the mass block 101 includes a first end D1 and a second end D2 opposite to each other along a first direction X, and the first direction X is parallel to the plane where the substrate 100 is located. The first end D1 and the second end D2 of the mass block 101 are connected to the substrate 100 through the cantilever structures 11, respectively. The mass block 101 further includes a third end D3 and a fourth end D4 opposite to each other along a second direction Y, and the third end D3 of the mass block 101 is connected to the substrate through a first sensing resistor 201 and a third sensing resistor 203, and the fourth end D4 of the mass block 101 is connected to the substrate 100 through a second sensing resistor 202 and a fourth sensing resistor 204, the second direction Y intersects with the first direction X, and the second direction Y is parallel to the plane where the substrate is located, and the first sensing resistor 201 and the third sensing resistor 203 are located on the diagonal bridge arms of the Wheatstone bridge.

[0044] Combination Figure 1The orientation shown, the second direction Y is the direction of the detected acceleration, the cantilever structure 11 plays a role in connecting and supporting the mass block 101, which can prevent the mass block 101's own gravity from acting on the four inductive resistors and thus affecting the measurement results, and is helpful to prevent the mass block from acting on the corresponding inductive resistors when the acceleration is too large, thereby causing damage to the inductive resistors. In addition, the surface of the cantilever structure 11 can also be designed for routing, and the surface of the cantilever structure 11, the mass block 101 and the substrate 100 can be used for routing design to avoid routing intersections, so that the four inductive resistors are electrically connected to form a structure as shown in FIG. Figure 2 The equivalent circuit shown is that the first sensing resistor 201 and the third sensing resistor 203 are located on the diagonal bridge arms of the Wheatstone bridge.

[0045] Based on the above positional relationship, when an acceleration is provided along the detected direction Y, under ideal conditions, the force on the first sensing resistor 201 is the same as the force on the third sensing resistor 203, and the force on the second sensing resistor 202 is the same as the force on the fourth sensing resistor 204. Under the piezoresistive effect, the resistance of the sensing resistor is related to the force it is subjected to. Therefore, the above-mentioned similar force characteristics are conducive to simplifying the equivalent circuit, thereby making the calculation of the acceleration more concise and improving the accuracy of the detection result.

[0046] It can be understood here that, ideally, the equivalent resistance of the wiring can be ignored. In the actual calculation process, the resistance values ​​of the four sense resistors may include the resistance value of the equivalent resistance of the wiring.

[0047] In some embodiments, along the first direction X, the width of the sensing resistor ranges from 2 nm to 2000 nm.

[0048] That is, the width of the nanowire structure ranges from 2nm to 2000nm, such as 2nm, 5nm, 10nm, 20nm...2000nm, etc. In different embodiments, the specific size can be optimized according to the size of the mass block to ensure the accuracy and sensitivity of the acceleration sensor 10.

[0049] In some embodiments, Figure 3 As shown, the acceleration sensor 10 also includes a substrate 21, the base 100, the multiple sensing resistors and the mass block 101 are all arranged on the same side of the substrate 21, the substrate 21 also includes a through cavity K0, and the orthographic projections of the multiple sensing resistors on the substrate 21 are located within the range of the orthographic projection of the cavity K0 on the substrate 21.

[0050] Combination Figure 1It is not difficult to understand that the film structure of the sensing resistor along the direction Z does not include the substrate 21, and the film structure of the mass block along the direction Z includes the substrate 21. Since the larger the mass, the greater the force under the same acceleration, the substrate 21 can increase the mass of the mass block 101, so that the force exerted by the mass block 101 on the sensing resistor is larger. In addition, the positive projection of the sensing resistor on the substrate 21 is located within the range of the positive projection of the cavity K0 on the substrate 21. By setting the cavity K0, the force can also be reduced from being conducted through the film layer of the substrate 21, so that the force exerted by the mass block 101 on the sensing resistor causes as much deformation of the sensing resistor as possible, thereby causing the potential difference between the two output ends of the equivalent circuit to change, which is beneficial to improving the sensitivity of the acceleration sensor 10.

[0051] In some embodiments, Figure 3 As shown, the acceleration sensor 10 further includes a substrate 22, which is disposed on a side of the substrate 21 away from the base 100, and a groove T0 is disposed on the surface of the substrate 22 close to the substrate 21, and the orthographic projections of the plurality of sensing resistors and the mass block 101 on the substrate 22 are located within the region where the groove T0 is located.

[0052] The substrate 22 provides a flat surface for the acceleration sensor 10. The groove T0 is arranged so that the mass block 101 and the sensing resistor are in a suspended structure, and the mass block 101 is connected to the substrate 100 through the sensing resistor. In the case of providing acceleration, the possibility of the force on the mass block 101 being transmitted through the substrate 22 is avoided, and the mass block 101 and the sensing resistor interact with each other, thereby causing the sensing resistor to deform. The arrangement of the groove T0 on the substrate 22 is conducive to providing the sensitivity of the acceleration sensor 10.

[0053] In some embodiments, Figure 3 As shown, the sensing resistor further includes a gate G disposed between a source S and a drain D of the sensing resistor.

[0054] In the embodiment of the present application, the four inductive resistors all include a nanowire structure 23, and the nanowire structure 23 here can be regarded as a part of a transistor, so that the four inductive resistors have transistor-related characteristics. Exemplarily, by setting a gate G and applying a voltage equal to the threshold voltage of the transistor to the gate G, compensation of the inductive resistor in the equivalent circuit can be achieved, so that Figure 2 The equivalent circuit shown is closer to the ideal equivalent effect, and the sensitivity of the acceleration sensor 10 is further improved.

[0055] In some embodiments, Figure 3As shown, the nanowire structure 23 also includes a stacked semiconductor layer and a barrier layer, the material of the semiconductor layer includes at least one of gallium nitride, gallium arsenide or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide or indium aluminum arsenide.

[0056] The nanowire structure formed by the above materials has a good quantum confinement effect. When the sensing resistor is deformed under stress, the nanowire structure is conducive to amplifying the piezoresistance change, so that the sensing resistor has a higher sensitivity. In addition, the above materials show good performance in both low and high temperature environments, which is conducive to improving the reliability of the sensing resistor. Based on this, the above materials can improve the sensitivity and reliability of the acceleration sensor 10.

[0057] Exemplarily, in some embodiments, the nanowire structure 23 further includes an insertion layer and a cap layer, wherein the semiconductor layer, the insertion layer, the barrier layer and the cap layer are stacked in sequence along a direction Z gradually moving away from the substrate 21, wherein the material of the semiconductor layer includes gallium nitride, the material of the insertion layer includes aluminum nitride, the material of the barrier layer includes aluminum gallium nitride, and the material of the cap layer includes gallium nitride.

[0058] In a second aspect, the embodiment of the present application further provides a method for preparing an acceleration sensor, the method comprising forming a substrate 100, a plurality of sensing resistors and a mass block 101. The plurality of sensing resistors comprises a first sensing resistor 201, a second sensing resistor 202, a third sensing resistor 203 and a fourth sensing resistor 204, and the first sensing resistor 201, the second sensing resistor 202, the third sensing resistor 203 and the fourth sensing resistor 204 are connected between the mass block 101 and the substrate 100, respectively.

[0059] The plurality of sensing resistors all include a nanowire structure, and the first sensing resistor 201 , the second sensing resistor 202 , the third sensing resistor 203 and the fourth sensing resistor 204 are electrically connected to form a Wheatstone bridge structure.

[0060] Therefore, the acceleration can be calculated according to the differential output of the Wheatstone bridge, which can avoid the influence of other environmental factors on the resistance change of the inductive resistor, and further avoid the influence of other environmental factors on the acceleration calculation result, which is conducive to improving the accuracy of the calculation result.

[0061] In addition, the four sensing resistors all include nanowire structures, which are smaller in size, more obviously deformed when subjected to stress, and have higher sensitivity. Nanowire structures usually have a larger piezoresistance coefficient, and have a quantum confinement effect at the nanoscale, which can amplify the change in the piezoresistance effect after strain. For example, the piezoresistance coefficient of silicon nanowires is two orders of magnitude higher than that of conventional silicon piezoresistance coefficients, and the resistance value changes more significantly under the same force, thereby enabling the acceleration sensor 10 to have a higher sensitivity. Based on the nanowire structure, the sensing resistors work well in high and low temperature environments, thereby improving the reliability of the acceleration sensor 10.

[0062] For example, Figure 4 As shown, Figure 4 A flow chart of a method for preparing an acceleration sensor provided in an embodiment of the present application, Figure 5~Figure 14 A diagram of the steps for preparing an acceleration sensor provided in an embodiment of the present application.

[0063] In some embodiments, the preparation method of forming the substrate 100, the plurality of sensing resistors and the mass block includes the following steps S10 to S30: Step S10: Figure 5~Figure 6 As shown, a nanowire structure 23 is formed on a substrate 21 .

[0064] For example, Figure 5 As shown, the substrate 21 includes a first surface P1 and a second surface P2 opposite to each other. To avoid lattice mismatch and dislocation, a buffer layer 25 is usually disposed on the first surface P1 of the substrate 21.

[0065] Then Figure 6 As shown, a nanowire structure 23 is formed on a side of the buffer layer 25 away from the substrate 21 .

[0066] Exemplarily, along the direction Z gradually away from the substrate 21, the nanowire structure 23 includes a semiconductor layer, an insertion layer, a barrier layer and a cap layer stacked in sequence. In some embodiments, the semiconductor layer, the insertion layer, the barrier layer and the cap layer can be sequentially prepared by vapor deposition according to the required size and position of the nanowire structure 23. In other embodiments, the semiconductor layer, the insertion layer, the barrier layer and the cap layer can also be sequentially prepared on the side of the buffer layer 25 away from the substrate 21, and then etched by an inductively coupled plasma etching process to form the desired nanowire structure 23.

[0067] In the above embodiments, the substrate 21 is usually a silicon substrate, or may also be a sapphire substrate. The width of the nanowire structure 23 ranges from 2 nm to 2000 nm.

[0068] Step S20: Figure 7~Figure 9As shown, a source S and a drain D are formed on both ends of the nanowire structure 23 away from the substrate 21 to obtain a plurality of inductive resistors.

[0069] In order to form a good electrical contact, Figure 7 As shown, an ohmic contact layer 24 is first formed on one side of both ends of the nanowire structure 23 away from the substrate 21 .

[0070] Afterwards, if Figure 8 As shown, a first passivation layer 26 is formed, and the first passivation layer 26 exposes a portion of the ohmic contact layer 24 .

[0071] Then, if Fig. 9 As shown, a source S and a drain D are formed.

[0072] In some embodiments, during the process of forming the source S and the drain D, a gate G is also formed. The gate G is disposed between the source S and the drain D of the sensing resistor, and finally forms a gate electrode as shown in FIG. Figure 3 The acceleration sensor 10 shown is not illustrated here.

[0073] In the process of forming the source S and the drain D, a connection line is also formed synchronously, so that the source S and the drain D of the plurality of sensing resistors are respectively electrically connected to form a Figure 2 The equivalent circuit is shown.

[0074] Afterwards, if Fig.10 As shown, a second passivation layer 27 is formed to insulate and protect the multiple sensing resistors and connecting wires. The second passivation layer 27 forms a suitable pad opening for connecting an external power source.

[0075] Step S30: Fig.11 As shown, the substrate 21 is etched to obtain the mass block 101 and the base 100 , the substrate 21 includes a penetrating cavity K0 , and the orthographic projections of the plurality of inductive resistors on the substrate 21 are located within the region where the cavity K0 is located.

[0076] It is understood that the substrate 100 includes a plurality of film structures formed sequentially in the above preparation process and located around the mass block 101 and the inductive resistor. The orthographic projection of the substrate 100 on the substrate 21 is located outside the orthographic projection of the cavity K0 on the substrate 21.

[0077] Exemplary, combined Figure 1 and Fig.11 As shown, the substrate 21 is etched on the second surface P2 of the substrate 21 by a deep silicon etching process to form a cavity K0, so that the orthographic projections of the plurality of inductive resistors on the substrate 21 are located within the region where the cavity K0 is located. Figure 1 In the illustrated embodiment, the mass block 101 and the cantilever structure 11 do not have a cavity K0 within the orthographic projection range on the substrate 21 .

[0078] In addition, in some embodiments, the preparation method further includes the following steps S40 to S50: Step S40: Fig.12 As shown, a trench T0 is formed on the surface of the substrate 22 .

[0079] Exemplarily, the size of the base 22 along direction X is the same as the size of the substrate 21 along direction X in step S10, and the size of the base 22 along direction Y is the same as the size of the substrate 21 along direction Y in step S10. That is, the orthographic projection of the base 22 can overlap with the orthographic projection of the substrate 21.

[0080] According to the orthographic projection positions of the mass block and the plurality of sensing resistors on the substrate 21 , the substrate 22 is etched to form a groove T0 , so that the orthographic projections of the plurality of sensing resistors and the mass block on the substrate 21 are finally located within the projection area of ​​the groove T0 on the substrate 22 .

[0081] Step S50: Fig.13 As shown, the base 22 can be bonded to the substrate 21 by silicon-silicon bonding. The base 22 is located on the side of the substrate 21 away from the nanowire structure 23, and the surface of the base 22 having the groove T0 is close to the substrate 21. The positive projections of the multiple sensing resistors and the mass blocks on the base 22 are located within the region where the groove T0 is located.

[0082] Finally, if Fig.14 As shown, an inductively coupled plasma etching process is used to etch away a portion of the buffer layer 25 to form a hollow structure that penetrates the cavity K0 , so that the four inductive resistors are respectively connected between the mass block 101 and the substrate 100 .

[0083] The preparation method has a relatively simple preparation process. The prepared acceleration sensor 10 can make the force of the mass block 101 cause the deformation of the sensing resistor as much as possible instead of being conducted through the substrate 21 or the base 22, thereby improving the sensitivity of the acceleration sensor 10.

[0084] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An acceleration sensor, characterized in that: The acceleration sensor comprises a substrate, a plurality of inductive resistors and a mass block; The plurality of sensing resistors include a first sensing resistor, a second sensing resistor, a third sensing resistor and a fourth sensing resistor, wherein the first sensing resistor, the second sensing resistor, the third sensing resistor and the fourth sensing resistor are respectively connected between the mass block and the substrate; The plurality of sensing resistors each include a nanowire structure, and the first sensing resistor, the second sensing resistor, the third sensing resistor, and the fourth sensing resistor are electrically connected to form a Wheatstone bridge structure.

2. The acceleration sensor according to claim 1, characterized in that: The acceleration sensor further comprises a plurality of cantilever structures, the mass block comprises a first end and a second end opposite to each other along a first direction, the first direction being parallel to the plane where the substrate is located; the first end and the second end of the mass block are respectively connected to the substrate through the cantilever structures; The mass block further includes a third end and a fourth end opposite to each other along a second direction, the third end of the mass block is connected to the substrate through the first sensing resistor and the third sensing resistor, and the fourth end of the mass block is connected to the substrate through the second sensing resistor and the fourth sensing resistor; the second direction intersects the first direction, and the second direction is parallel to the plane where the substrate is located; The first sensing resistor and the third sensing resistor are located on diagonal bridge arms of the Wheatstone bridge.

3. The acceleration sensor according to claim 2, characterized in that: Along the first direction, the width of the sensing resistor ranges from 2 nm to 2000 nm.

4. The acceleration sensor according to claim 1, characterized in that: The acceleration sensor further comprises a substrate, wherein the base, the plurality of sensing resistors and the mass block are all arranged on the same side of the substrate; The substrate further includes a penetrating cavity, and the orthographic projections of the plurality of sensing resistors on the substrate are located within the range of the orthographic projections of the cavity on the substrate.

5. The acceleration sensor according to claim 4, characterized in that: The acceleration sensor further comprises a base, which is arranged on a side of the substrate away from the base body, and a surface of the substrate close to the substrate is provided with a groove; The orthographic projections of the plurality of sensing resistors and the proof mass on the substrate are located within a region where the groove is located.

6. The acceleration sensor according to claim 1, characterized in that: The sensing resistor further includes a gate disposed between a source and a drain of the sensing resistor.

7. The acceleration sensor according to claim 1, characterized in that: The nanowire structure further includes a semiconductor layer and a barrier layer which are stacked; The material of the semiconductor layer includes at least one of gallium nitride, gallium arsenide or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide or indium aluminum arsenide.

8. A method for preparing an acceleration sensor, characterized in that: The preparation method includes forming a substrate, a plurality of inductive resistors and a mass block; The plurality of sensing resistors include a first sensing resistor, a second sensing resistor, a third sensing resistor and a fourth sensing resistor, and the first sensing resistor, the second sensing resistor, the third sensing resistor and the fourth sensing resistor are respectively connected between the mass block and the substrate; The plurality of sensing resistors each include a nanowire structure, and the first sensing resistor, the second sensing resistor, the third sensing resistor, and the fourth sensing resistor are electrically connected to form a Wheatstone bridge structure.

9. The preparation method according to claim 8, characterized in that: Forming the substrate, the plurality of inductive resistors and the one mass block comprises: forming a nanowire structure on a substrate; Forming a source electrode and a drain electrode on both ends of the nanowire structure away from the substrate to obtain the plurality of sensing resistors; The substrate is etched to obtain the mass block and the base; the substrate includes a penetrating cavity, and the orthographic projections of the plurality of inductive resistors on the substrate are located within the region where the cavity is located.

10. The preparation method according to claim 9, characterized in that: The preparation method further comprises: forming grooves on a surface of a substrate; The base is bonded to the substrate, wherein the base is located on a side of the substrate away from the nanowire structure, and a surface of the base having the groove is close to the substrate; the orthographic projections of the multiple sensing resistors and the one mass block on the substrate are located within the region where the groove is located.

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