Micro-mechanical ultrasonic transducer compatible with PZT thin film process and preparation method of micro-mechanical ultrasonic transducer

Abstract

The invention belongs to the technical field of micromachinery, and particularly relates to a piezoelectric-capacitive hybrid micromechanical ultrasonic transducer compatible with a PZT film and a preparation method of the piezoelectric-capacitive hybrid micromechanical ultrasonic transducer compatible with the PZT film. Wherein the barrier layer is made of a thin film material with low diffusion coefficient and high conductivity, namely a conductive barrier layer is adopted; correspondingly, vertical integration of the PZT-based piezoelectric transduction unit and the capacitance transduction unit on a single wafer is realized by adopting a fusion bonding technology; the preparation process comprises the steps of thin film deposition, patterned etching, wafer bonding and the like so as to optimize the performance of the transducer. Compared with a conventional micro-mechanical ultrasonic transducer, the micro-mechanical ultrasonic transducer has higher transmitting sensitivity and receiving sensitivity, and is suitable for high-precision imaging and sensing application.

Description

Technical Field

[0001] The present invention belongs to the field of micro-mechanical technology, and in particular relates to a micro-mechanical ultrasonic transducer and a preparation method thereof. Background Art

[0002] Micromachined Ultrasonic Transducer (MUT), as the core device of modern ultrasonic technology, has shown important application value in the fields of medical diagnosis, industrial flaw detection and biosensing. 1-x ]O 3 Piezoelectric Micromachined Ultrasonic Transducer (PMUT) with PZT thin film as the core has excellent piezoelectric properties (d3 3 The coefficient can reach 200-400pm / V) and shows excellent acoustic wave emission efficiency. Its electromechanical coupling coefficient is dozens of times higher than that of other piezoelectric film materials (such as aluminum nitride and zinc oxide). The capacitive micromachined ultrasonic transducer (CMUT) has significant advantages in ultrasonic signal detection due to its wide-band response (relative bandwidth can reach 100%) and high receiving sensitivity.

[0003] In view of the inherent limitations of existing PMUT and CMUT in system loop sensitivity, the hybrid micromechanical ultrasonic transducer (Hybrid MUT) based on PZT has become a highly promising technology route due to its unique synergistic effect - by organically integrating the strong driving characteristics of PZT film with the sensitive receiving characteristics of CMUT, it is theoretically possible to achieve a synergistic enhancement of the transmission efficiency and the receiving signal-to-noise ratio. However, there is a significant process conflict between the preparation process of PZT film (which requires high-temperature annealing and deposition of additional barrier layers) and the silicon-based micromachining process of CMUT: the traditional dielectric barrier layer (such as aluminum oxide and silicon oxide) is deposited between the middle electrode and the lower electrode, making it impossible to form a capacitive structure. Summary of the invention

[0004] The present invention aims to provide a micromechanical ultrasonic transducer compatible with PZT (lead zirconate titanate) film and a preparation method thereof.

[0005] The microelectromechanical ultrasonic transducer compatible with PZT (lead zirconate titanate) thin film provided by the present invention includes a capacitive microelectromechanical ultrasonic transducer, a piezoelectric microelectromechanical ultrasonic transducer based on PZT thin film, and a piezoelectric-capacitive hybrid microelectromechanical ultrasonic transducer based on PZT thin film. The present invention improves the barrier layer therein (the barrier layer in the traditional microelectromechanical ultrasonic transducer uses a dielectric material (such as alumina, silicon oxide)), and specifically uses a thin film material with both low diffusion coefficient and high conductivity, that is, a conductive barrier layer is used. Correspondingly, by using the fusion bonding technology, the vertical integration of the PZT-based piezoelectric transducer unit and the capacitive transducer unit on a single wafer can be realized, promoting the improvement of the electromechanical conversion efficiency of the hybrid MUT.

[0006] The piezoelectric-capacitive hybrid microelectromechanical ultrasonic transducer compatible with PZT thin film provided by the present invention has a unit structure including a substrate layer 1-1, a lower electrode layer 1-2, a support layer 1-3, a cavity 1-4, an elastic layer 1-5, a barrier layer 1-6, an intermediate electrode layer 1-7, a buffer layer 1-8, a seed layer 1-9, a PZT piezoelectric layer 1-10, a top electrode layer 1-10, a passivation layer 1-11, and a pad 1-12 arranged from bottom to top; as Figure 3 shown; wherein:

[0007] The cavity 1-4 is a hollow structure inside the support layer 1-3, and the cavity 1-4 is surrounded by the lower electrode layer 1-2, the support layer 1-4, and the elastic layer 1-5;

[0008] The elastic layer 1-5, the barrier layer 1-6, the intermediate electrode layer 1-7, the buffer layer 1-8, the seed layer 1-9, the PZT piezoelectric layer 1-10, the upper electrode layer 1-11, and the passivation layer 1-12 are stacked in sequence to form a vibration layer 1-14;

[0009] The pad 1-13 includes the pins of the lower electrode 1-2, the intermediate electrode layer 1-7, and the upper electrode layer 1-11;

[0010] The vibration layer 1-14 is located on the top of the cavity 1-4 and the support layer 1-3, and the vibration layer 1-14 located on the top of the cavity 1-4 can perform thin-film bending vibration, that is, the cavity 1-4 provides a vibration space for the vibration of the vibration layer 1-14;

[0011] The intermediate electrode layer 1-7 and the upper electrode layer 1-11 form the upper and lower electrodes of the piezoelectric layer 1-10. When a voltage is applied between them, the inverse piezoelectric effect of the piezoelectric material is excited, and then a bending moment acting on the vibration layer 1-14 is generated. The lower electrode layer 1-2 and the intermediate electrode layer 1-7 form the upper and lower electrodes of the capacitive structure; they are subjected to the electrostatic force of mutual attraction; when a DC bias voltage is applied in advance, the vibration layer 1-14 is subjected to a downward electrostatic force. The piezoelectric bending moment and the electrostatic force act on the vibration layer 1-14 together, causing it to bend and vibrate.

[0012] Further, in the present invention:

[0013] The substrate layer 1-1 is a conductively doped silicon wafer, preferably with a thickness of 100 to 1000 microns.

[0014] The lower electrode layer 1-2 is conductively doped silicon, and the intermediate electrode layer 1-7, the top electrode layer 1-10, and the pad 1-13 are metal thin films, preferably with a thickness of 0.1 to 1 micron.

[0015] The cavity 1-4 is a vacuum cavity, preferably circular in shape, with a radius of 10 to 100 microns and a thickness of 0.1 to 1 micron.

[0016] The support layer 1-4 is an insulating dielectric, preferably made of silicon oxide, with a thickness consistent with that of the cavity.

[0017] The elastic layer 1-5 is usually conductively doped silicon, preferably with a thickness of 0.5 to 5 microns.

[0018] The barrier layer 1-6 is a thin film material with both a low diffusion coefficient and high conductivity, preferably materials such as zirconium nitride, iridium, titanium tungsten alloy, and titanium nitride, etc., preferably with a thickness of 100 to 300 nanometers.

[0019] The intermediate electrode layer 1-7 is usually a metal thin film material, such as gold, aluminum, etc., preferably with a thickness of 100 to 300 nanometers.

[0020] The buffer layer 1-8 is usually silicon dioxide or aluminum oxide, preferably with a thickness of 100 to 300 nanometers.

[0021] The seed layer 1-9 is usually PZT, lead titanate, or strontium ruthenate, preferably with a thickness of 100 to 300 nanometers.

[0022] The PZT piezoelectric layer 1-10 is a PZT piezoelectric thin film, preferably with a thickness of 0.1 to 2 microns.

[0023] The upper electrode layer 1-11 is usually a metal thin film material, such as gold, aluminum, etc., preferably with a thickness of 100 to 300 nanometers.

[0024] The passivation layer 1-12 is usually silicon oxide or silicon nitride, preferably with a thickness of 0.1 to 1 micron.

[0025] The pad 1-13 is usually a metal thin film material, such as gold, aluminum, etc., preferably with a thickness of 100 to 300 nanometers.

[0026] The preparation method of the piezoelectric-capacitive hybrid microelectromechanical ultrasonic transducer compatible with PZT thin films provided by the present invention specifically comprises the following steps:

[0027] Step 1: Etch the front and back alignment marks 2-1 on the silicon wafer substrate 1-1 with a surface-conductive doped lower electrode 1-2.

[0028] Step 2: Thermally oxidize the silicon wafer substrate 1-1 to form a support layer 1-3 and a back oxide layer 2-2.

[0029] Step 3: Etch the support layer 1-3 to form a cavity 1-4.

[0030] Step 4: Perform a fusion bonding on the front surface of the silicon wafer 1-1 and the device layer 2-4 surface of the SOI wafer 2-3.

[0031] Step 5: Remove the substrate layer 2-6 and the buried oxide layer 2-5 of the SOI wafer 2-3 in sequence, and finally the device layer 2-4 serves as the elastic layer 1-5 of the micromachined ultrasonic transducer.

[0032] Step 6: Deposit a barrier layer 1-6, an intermediate electrode layer 1-7, a buffer layer 1-8, a seed layer 1-9, a PZT piezoelectric layer 1-10, and an upper electrode layer 1-11 in sequence.

[0033] Step 7: Etch the upper electrode layer 1-11, the PZT piezoelectric layer 1-10, the seed layer 1-9, the buffer layer 1-8, the intermediate electrode layer 1-7, and the barrier layer 1-6 in sequence to form a patterned piezoelectric functional layer.

[0034] Step 8: Pattern etch the device layer 2-4 and the support layer 1-3 to expose the lower electrode 1-2.

[0035] Step 9: Deposit and etch a dielectric material layer to form a passivation layer 1-12.

[0036] Step 10: Deposit and etch a metal layer to form a bonding pad 1-13.

[0037] The processing method provided by the present invention is compatible with a variety of manufacturing processes, including but not limited to chemical vapor deposition, physical vapor deposition, sputtering process, etching process, wafer bonding process, etc.

[0038] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0039] (1) Process Compatibility Breakthrough: Aiming at the material compatibility problem between the high-temperature crystallization process of traditional PZT thin films and the metal electrode layer of CMUT devices, the present invention innovatively adopts a conductive barrier layer. While achieving high-quality deposition of PZT thin films, this conductive functional layer effectively blocks the thermal damage to the underlying CMUT metal electrodes during the high-temperature annealing process, and for the first time successfully integrates the manufacturing of PZT piezoelectric layers and CMUT capacitive structures on the same wafer. This breakthrough process enables the synchronous preparation of piezoelectric PMUTs, capacitive CMUTs, and new hybrid MUTs based on PZT, solving the major technical bottleneck that traditional process systems are difficult to balance the integration of heterogeneous materials.

[0040] (2) Cross-Modal Performance Fusion: Through the innovative design of the piezoelectric-capacitive hybrid architecture, the present invention fully exploits the ultra-high piezoelectric constant characteristics of PZT thin films and the high receiving sensitivity advantages of CMUTs. At the transmitting end, the PZT piezoelectric layer utilizes its strong electromechanical coupling characteristics to achieve high sound pressure output, as Figure 3 shown; at the receiving end, the CMUT structure significantly improves the transmitting sensitivity of the ultrasonic transducer by obtaining weak signals through high-precision capacitance detection. The hybrid architecture performs excellently in high-frequency applications and is particularly suitable for fields such as medical imaging, non-destructive testing, and fingerprint recognition. Description of the Drawings

[0041] Figure 1 is a schematic structural diagram (vertical sectional view) of the piezoelectric-capacitive hybrid micromachined ultrasonic transducer unit based on PZT thin films of the present invention.

[0042] FIG. 2(a) and FIG. 2(b) are schematic diagrams of the preparation process of the piezoelectric-capacitive hybrid micromachined ultrasonic transducer compatible with PZT thin films of the present invention.

[0043] Figure 3 is the comparison result of the transmitting sensitivities of the piezoelectric-capacitive hybrid micromachined ultrasonic transducer compatible with PZT thin films and the piezoelectric-capacitive hybrid micromachined ultrasonic transducer compatible with AlN thin films of the present invention. Among them, (a) is the present invention, and (b) is the piezoelectric-capacitive hybrid micromachined ultrasonic transducer compatible with AlN thin films.

[0044] Reference numerals in the figures: 1-1 is the substrate layer, 1-2 is the lower electrode layer, 1-3 is the support layer, 1-4 is the cavity, 1-5 is the elastic layer, 1-6 is the barrier layer, 1-7 is the intermediate electrode layer, 1-8 is the buffer layer, 1-9 is the seed layer, 1-10 is the PZT piezoelectric layer, 1-11 is the upper electrode layer, 1-12 is the passivation layer, 1-13 is the pad, 1-14 is the vibration layer, 2-1 is the alignment mark, 2-2 is the back oxide layer, 2-3 is the SOI wafer, 2-4 is the device layer of the SOI wafer 2-3, 2-5 is the buried oxide layer of the SOI wafer 2-3, and 2-6 is the substrate layer of the SOI wafer 2-3. Detailed Embodiments

[0045] The present invention will be described in more detail below with reference to the accompanying drawings. In the respective drawings, like elements are denoted by like reference numerals. For the sake of clarity, the various parts in the drawings are not drawn to scale. In addition, some well-known parts may not be shown.

[0046] Many specific details of the present invention, such as device structures, material dimensions, processing techniques and technologies, are described below in order to understand the present invention more clearly. However, as those skilled in the art can understand, the present invention can be implemented without being limited to these specific details.

[0047] Figure 1 It is a schematic structural diagram (vertical sectional view) of a piezoelectric-capacitive hybrid micromachined ultrasonic transducer unit compatible with a PZT thin film process according to the present invention. As Figure 1 shown, the structure of the piezoelectric-capacitive hybrid micromachined ultrasonic transducer includes, from top to bottom: a substrate layer 1-1, a lower electrode layer 1-2, a support layer 1-3, a cavity 1-4, an elastic layer 1-5, a barrier layer 1-6, an intermediate electrode layer 1-7, a buffer layer 1-8, a seed layer 1-9, a PZT piezoelectric layer 1-10, an upper electrode layer 1-11, a passivation layer 1-12, and a pad 1-13. Among them, the lower electrode layer 1-2 and the intermediate electrode layer 1-7 form the upper and lower electrodes of a parallel plate capacitor; the intermediate electrode layer 1-7 and the upper electrode layer 1-11 form the upper and lower electrodes of the PZT piezoelectric layer 1-10; the sequentially stacked elastic layer 1-5, barrier layer 1-6, intermediate electrode layer 1-7, buffer layer 1-8, seed layer 1-9, PZT piezoelectric layer 1-10, upper electrode layer 1-11, and passivation layer 1-12 form a vibration layer 1-14; the substrate layer 1-1, support layer 1-3, and elastic layer 1-5 enclose to form a cavity 1-3; the cavity 1-3 provides a space for the vibration layer 1-14 to deform.

[0048] The substrate layer 1-1 is a silicon wafer with surface conductive doping, and its thickness is 100 to 1000 microns; the lower electrode layer 1-2 is a thin layer on the upper surface of the substrate layer 1-1; the cavity 1-4 is a vacuum structure with a radius of 10 to 100 microns; the support layer 1-3 is silicon oxide with a thickness of 0.1 to 1 micron; the elastic layer 1-5 is conductive doped silicon with a thickness of 0.5 - 5 microns; the preferred materials for the barrier layer 6 are zirconium nitride, iridium, titanium tungsten alloy, titanium nitride, etc., and the preferred thickness is 100 to 300 nanometers; the intermediate electrode layer 1-7 is usually a metal thin film material, such as gold, aluminum, etc., and the preferred thickness is 100 to 300 nanometers. The buffer layer 1-8 is usually silicon dioxide or aluminum oxide, and the preferred thickness is 100 to 300 nanometers. The seed layer 1-9 is usually PZT, lead titanate or strontium ruthenate, and the preferred thickness is 100 to 300 nanometers. The PZT piezoelectric layer 1-10 is a PZT piezoelectric thin film, and the preferred thickness is 0.1 to 2 microns.

[0049] Figures 2(a) and 2(b) are schematic diagrams of the preparation process of the piezoelectric-capacitive hybrid micromachined ultrasonic transducer compatible with PZT thin films according to the present invention. The preparation steps include:

[0050] Step 1: Perform phosphorus / boron ion implantation on the surface of the silicon wafer substrate 1-1, and then perform rapid annealing in a high-temperature nitrogen atmosphere after implantation to activate doping and form the lower electrode 1-2 with surface conductive doping. Subsequently, perform photolithography and reactive ion etching on the silicon wafer substrate 1-1 to form the front and back alignment marks 2-1. The alignment marks 2-1 can be used for double-sided alignment.

[0051] Step 2: At high temperature, the silicon wafer substrate 1-1 is thermally oxidized to form the support layer 1-3 and a by-product - the back oxide layer 2-2.

[0052] Step 3: Use photolithography and reactive ion etching techniques to pattern-etch the support layer 1-3. The etching gas is usually CHF 3 / O 2 mixed gas, and the etching stop layer is the lower electrode 1-2. The etched area forms the cavity 1-4.

[0053] Step 4: Clean and activate the surfaces of the silicon wafer substrate 1-1 and the SOI wafer 2-3, and then, under high temperature and high pressure, use a wafer bonder to melt-bond the front surface of the silicon wafer substrate 1-1 and the device layer 2-4 surface of the SOI wafer 2-3. Finally, perform high-temperature annealing to make silicon atoms diffuse at the interface through heating to form a permanent chemical bond.

[0054] Step 5: First, use thinning polishing and wet etching techniques to remove the substrate silicon layer 2-6 of the SOI wafer 2-3, and then use HF or buffered oxide etchant to remove the buried oxide layer 2-5;

[0055] Step 6: Sequentially deposit the barrier layer 1-6, the intermediate electrode layer 1-7, the buffer layer 1-8, the seed layer 1-9, the PZT piezoelectric layer 1-10, and the upper electrode layer 1-11 by means of magnetron sputtering technology;

[0056] Step 7: Pattern-etch the upper electrode layer 1-11, the PZT piezoelectric layer 1-10, the seed layer 1-9, the buffer layer 1-8, the intermediate electrode layer 1-7, and the barrier layer 1-6 in sequence by means of photolithography and reactive ion etching technology. The typical etching gas combination is Cl 3 / BCl 3 mixed gas to finally form a patterned piezoelectric functional layer;

[0057] Step 8: Pattern-etch the device layer 2-4 by means of photolithography and reactive ion etching technology. The etching gas commonly used is SF 6 / O 2 mixed gas, and the etching stop layer is the oxide layer 2-5. Subsequently, use HF or buffered oxide etchant to remove the oxide layer 2-5 exposed under the device layer 2-4. Finally, the etching terminates at the surface-conductively doped lower electrode 1-2.

[0058] Step 9: Deposit a dielectric material layer by means of plasma-enhanced chemical vapor deposition technology, and then pattern-etch it by reactive ion etching to form a passivation layer 1-11 with through holes;

[0059] Step 10: Deposit a metal layer by means of magnetron sputtering technology, and then pattern-etch it by dry metal etching. The etching gas commonly used is Cl 3 / BCl 3 mixed gas, and the etching stop layer is the lower electrode 1-2, the intermediate electrode 1-7, or the upper electrode 1-11 to finally form a pad 1-12.

[0060] Figure 3Comparison results of the emission sensitivities between the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with PZT thin films and the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with AlN thin films of the present invention. Among them, (a) is the present invention, and (b) is the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with AlN thin films. It can be seen from the figure that for the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with PZT thin films of the present invention, the emission sensitivity is 4179 Pa / V at a center frequency of 3 MHz; and the emission sensitivity is 6242 Pa / V at a center frequency of 10 MHz. For reference, the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with AlN thin films has an emission sensitivity of 716 Pa / V at a center frequency of 3 MHz; and the emission sensitivity is 1276 Pa / V at a center frequency of 10 MHz. As shown above, the emission sensitivity of the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with PZT thin films can be increased to 5.8 times (at 3 MHz) and 4.9 times (at 10 MHz) compared with that of the piezoelectric-capacitive hybrid MEMS ultrasonic transducer compatible with AlN thin films.

Claims

1. A piezoelectric-capacitive hybrid micromechanical ultrasonic transducer compatible with PZT thin film, characterized in that; The barrier layer is made of a thin film material with both low diffusion coefficient and high conductivity, that is, a conductive barrier layer. The specific materials are zirconium nitride, iridium, titanium tungsten alloy and titanium nitride. Accordingly, melt bonding technology is used to realize the vertical integration of PZT-based piezoelectric transducer units and capacitive transducer units on a single wafer.

2. The micromechanical ultrasonic transducer according to claim 1, characterized in that: The structure of the piezoelectric-capacitive hybrid micromechanical ultrasonic transducer compatible with a PZT thin film comprises a substrate layer (1-1), a lower electrode layer (1-2), a support layer (1-3), a cavity (1-4), an elastic layer (1-5), a barrier layer (1-6), an intermediate electrode layer (1-7), and a buffer layer arranged from bottom to top; the cavity layer (1-4) is a hollow structure inside the support layer (1-3), and the cavity (1-4) is surrounded by the substrate layer (1-1), the support layer (1-3), and the elastic layer (1-5); The elastic layer (1-5), the barrier layer (1-6), the intermediate electrode layer (1-7), the buffer layer (1-8), the seed layer (1-9), the PZT piezoelectric layer (1-10), the upper electrode layer (1-11) and the passivation layer (1-12) are stacked in sequence to form a vibration layer (1-14); The pad (1-13) comprises pins of a lower electrode layer (1-2), an intermediate electrode layer (1-7) and an upper electrode layer (1-11); The vibration layer (1-14) is located on the top of the cavity (1-4) and the support layer (1-3), wherein the vibration layer (1-14) located on the top of the cavity (1-4) performs thin film bending vibration, that is, the cavity (1-4) provides a vibration space for the vibration of the vibration layer (1-14); The intermediate electrode layer (1-7) and the top electrode layer (1-11) constitute the upper and lower electrodes of the PZT piezoelectric layer (1-10); when a voltage is applied between them, a bending moment acting on the vibration layer (1-14) is generated through the inverse piezoelectric effect; The lower electrode layer (1-2) constitutes the lower electrode of the capacitive structure, and the corresponding barrier layer (1-6) and the intermediate electrode layer (1-7) constitute the upper electrode of the capacitive structure; the two are acted upon by mutually attractive electrostatic forces; when a DC bias voltage is pre-applied, the vibration layer (1-14) is acted upon by a downward electrostatic force; the piezoelectric bending moment and the electrostatic force act together on the vibration layer (1-14), causing it to bend and vibrate.

3. The micromechanical ultrasonic transducer according to claim 2, characterized in that: The substrate layer (1-1) is silicon with conductive doping on the surface, and has a thickness of 100 to 1000 micrometers; the barrier layer (1-6) is made of zirconium nitride, iridium, titanium-tungsten alloy and titanium nitride, and has a thickness of 100 to 300 nanometers.

4. The micromechanical ultrasonic transducer according to claim 2, characterized in that: The lower electrode layer (1-2) is conductively doped silicon with a thickness of 0.5 to 5 micrometers; the middle electrode layer (1-7), the upper electrode layer (1-10) and the pad (1-13) are metal thin layers with a thickness of 0.1 to 1 micrometer; the buffer layer is silicon dioxide or aluminum oxide with a thickness of 100 to 300 nanometers; the seed layer (1-9) provides more nucleation sites for the deposition of the PZT thin film and is PZT, lead titanate or strontium ruthenate with a thickness of 100 to 300 nanometers.

5. The micromechanical ultrasonic transducer according to claim 2, characterized in that: The cavity (1-4) is a vacuum cavity, which is usually circular in shape, with a radius of 10 to 100 microns and a thickness of 0.1 to 1 micron.

6. The micromechanical ultrasonic transducer according to claim 2, characterized in that: The elastic layer (1-5) is conductively doped silicon and has a thickness of 0.5 to 5 microns.

7. The micromechanical ultrasonic transducer according to claim 2, characterized in that: The PZT piezoelectric layer (1-10) is a PZT thin film with a thickness of 0.1 to 2 microns.

8. The micromechanical ultrasonic transducer according to claim 2, characterized in that: The passivation layer (1-11) is silicon oxide or silicon nitride.

9. A method for preparing a micromechanical ultrasonic transducer according to any one of claims 2 to 8, characterized in that: The specific steps are: Step 1, etching front and back overlay marks (2-1) on a silicon wafer substrate (1-1) with a lower electrode (1-2) with surface conductive doping; Step 2, thermally oxidizing the silicon wafer (1-1) to form a support layer (1-3) and a back oxide layer (2-2); Step 3, etching the support layer (1-3) to form a cavity (1-4); Step 4, melt-bonding the front side of the silicon wafer substrate (1-1) and the surface of the device layer (2-4) of the SOI wafer (2-3); Step 5, sequentially removing the substrate silicon layer (2-6) and the buried oxide layer (2-5) of the SOI wafer (2-3); Step 6, sequentially depositing a barrier layer (1-6), an intermediate electrode layer (1-7), a buffer layer (1-8), a seed layer (1-9), a PZT piezoelectric layer (1-10) and an upper electrode layer (1-11); Step 7, etching the upper electrode layer (1-11), the PZT piezoelectric layer (1-10), the seed layer (1-9), the buffer layer (1-8), the intermediate electrode layer (1-7), and the barrier layer (1-6) in sequence to form a patterned piezoelectric functional layer; Step 8: patterning and etching the device layer (2-4) and the oxide layer (2-5) to expose the lower electrode (1-2) with conductive doping on the surface; Step 9, depositing and etching a dielectric material layer to form a passivation layer (2-12); Step 10: deposit and etch a metal layer to form a pad (2-13).

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