WO2022237301A1

WO2022237301A1 - Hydrophone and manufacturing method therefor

Info

Publication number: WO2022237301A1
Application number: PCT/CN2022/080855
Authority: WO
Inventors: 焦文龙; 曾怀望; 李鑫; 李嗣晗
Original assignee: 联合微电子中心有限责任公司
Priority date: 2021-05-10
Filing date: 2022-03-15
Publication date: 2022-11-17
Also published as: CN113075726A; CN113075726B

Abstract

The present disclosure provides a hydrophone and a manufacturing method therefor. The hydrophone comprises: a membrane configured to physically deform in response to dynamic sound pressure and static water pressure; a piezoelectric structure configured to generate a first sensing signal in response to the physical deformation; and piezoresistive structures configured to generate a second sensing signal in response to the physical deformation.

Description

Hydrophone and its manufacturing method

technical field

The present disclosure relates to the technical field of semiconductors, in particular to a hydrophone and a manufacturing method thereof.

Background technique

The thin-film structure MEMS hydrophone based on piezoelectric technology has the characteristics of high sensitivity and low power consumption. However, limited by the principle of piezoelectric effect detection, piezoelectric MEMS hydrophones with thin-film structures can only detect dynamic sound pressure, and cannot identify static water pressure in the use environment.

The static water pressure in the environment where the hydrophone is used will affect the deformation of the membrane structure of the MEMS hydrophone, further affecting the accuracy of its detection sensitivity. In addition, if the static water pressure is too large, it will also cause damage to the membrane structure.

Contents of the invention

It would be advantageous to provide a mechanism that alleviates, alleviates, or even eliminates one or more of the above-mentioned problems.

According to some embodiments of the present disclosure, there is provided a hydrophone comprising: a membrane configured to physically deform in response to dynamic sound pressure and static water pressure; a piezoelectric structure configured to respond to the a physical deformation to generate a first sensing signal; and a piezoresistive structure configured to generate a second sensing signal in response to the physical deformation.

According to some embodiments of the present disclosure, there is also provided a method for manufacturing a hydrophone, including: providing a semiconductor substrate; forming a piezoelectric structure and a piezoresistive structure at the first surface of the semiconductor substrate; A groove is formed on the second surface of the semiconductor substrate opposite to the first surface, so that at least a part of the semiconductor substrate forms a thin film, and the groove is related to the thin film and the piezoresistive structure and piezoelectric Structural relative.

These and other aspects of the disclosure will be apparent from and will be elucidated with reference to the embodiments described hereinafter.

Description of drawings

Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments with reference to the accompanying drawings in which:

FIG. 1 is a schematic cross-sectional view of a hydrophone according to an exemplary embodiment of the present disclosure;

FIG. 2A-FIG. 2D are schematic plan views of a hydrophone according to an exemplary embodiment of the present disclosure;

3 is a flowchart of a method of manufacturing a hydrophone according to an exemplary embodiment of the present disclosure;

4 is a flowchart of an example process of forming a piezoelectric structure and a piezoresistive structure in the method of FIG. 3 according to an exemplary embodiment of the present disclosure;

5A to 5F are schematic cross-sectional views of an example structure of a hydrophone formed in various steps of the method of FIG. 3 according to an exemplary embodiment of the present disclosure;

6 is a flowchart of an example process of forming a piezoelectric structure and a piezoresistive structure in the method of FIG. 3 according to an exemplary embodiment of the present disclosure; and

7A to 7G are schematic cross-sectional views of an exemplary structure of a hydrophone formed in various steps of the method of FIG. 3 according to an exemplary embodiment of the present disclosure.

Detailed ways

It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, that these elements, components, regions, layers and/or Sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure.

Spatially relative terms such as "below," "beneath," "lower," "below," "above," "upper," etc. may be used herein for convenience. The description is used to describe the relationship of one element or feature to another element or feature(s) as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "beneath" or "beneath" other elements or features would then be oriented "beneath" the other elements or features. over the characteristics". Thus, the exemplary terms "below" and "beneath" can encompass both an orientation of above and below. Terms such as "before" or "before" and "after" or "following" may similarly be used, for example, to indicate the order in which light passes through the elements. The device may be oriented otherwise (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be further understood that the terms "comprising" and/or "comprising" when used in this specification specify the presence of stated features, integers, steps, operations, elements and/or parts, but do not exclude the presence of one or more The presence or addition of one or more other features, integers, steps, operations, elements, parts and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items, and the phrase "at least one of A and B" means only A, only B, or both A and B.

It will be understood that when an element or layer is referred to as being "on", "connected to", "coupled to" or "adjacent to another element or layer" , it may be directly on, directly connected to, directly coupled to, or directly adjacent to another element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to," "directly coupled to" or "directly adjacent to" another element or layer , with no intermediate elements or layers present. In no event, however, "on" or "directly on" should be construed as requiring that one layer completely cover the underlying layer.

Embodiments of the disclosure are described herein with reference to schematic illustrations of idealized embodiments (and intermediate structures) of the disclosure. As such, variations from the shapes of the illustrations, for example, as a result of manufacturing techniques and/or tolerances, should be expected. Thus, embodiments of the present disclosure should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present disclosure.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted to have meanings consistent with their meanings in the relevant field and/or in the context of this specification, and will not be idealized or overly be construed in a formal sense unless expressly so defined herein.

As used herein, the term "substrate" may refer to the substrate of a diced wafer, or may refer to the substrate of an un-diced wafer. Similarly, the terms chip and die may be used interchangeably unless such interchange would cause a conflict. It should be understood that the term "film" includes layers and should not be construed to indicate vertical or horizontal thickness unless otherwise stated. It should be noted that the thickness of each material layer of the hydrophone shown in the figure is only for illustration, and does not represent the actual thickness.

The embodiments of the present disclosure provide a hydrophone, which can detect the static water pressure in the environment where the MEMS hydrophone is used, prevent the damage to the membrane structure of the piezoelectric MEMS hydrophone, and at the same time detect the hydrophone. The dynamic pressure signal is calibrated.

Fig. 1 is a schematic cross-sectional structure diagram of a hydrophone 100 according to an exemplary embodiment of the present disclosure. 2A-2D are schematic plan view diagrams of the hydrophone 100 according to an exemplary embodiment of the present disclosure. The structure of the hydrophone 100 will be described below with reference to FIGS. 1 and 2A-2D.

The hydrophone 100 includes a membrane 110 , a piezoresistive structure 120 and a piezoelectric structure 130 .

The membrane 110 is configured to physically deform in response to dynamic acoustic pressure and static water pressure. The dynamic sound pressure is the pressure on the hydrophone 100 caused by the vibration of the water body when the sound propagates in water, and the hydrophone 100 detects the sound signal based on the physical deformation of the membrane 110 in response to the dynamic sound pressure. The static water pressure is the pressure generated by the environment where the hydrophone 100 is located on the hydrophone 100 , for example, the pressure generated by seawater on the hydrophone 100 is related to the depth at which the hydrophone 100 is located. In some embodiments, the membrane has a rectangular or circular shape. According to some embodiments, as shown in FIG. 2 , the membrane 110 has a circular shape.

The piezoelectric structure 130 is configured to generate a first sensing signal in response to physical deformation of the membrane 110 . The piezoelectric structure 130 produces a piezoelectric effect based on the deformation of the thin film 110 , and converts the strain into an electrical signal and outputs it as a first sensing signal. The deformation of the membrane 110 includes transient deformation based on dynamic sound pressure and continuous deformation based on static water pressure. The piezoelectric structure 130 generates induced charges based on the deformation of the membrane 110 and generates an electrical signal reflecting the change of the charge. The electrical signal serves as The first sensing signal is output. Due to the continuous deformation of the thin film 110 under static water pressure, the induced charge is discharged by the circuit including the resistance of the piezoelectric material itself, so that the first sensing signal finally output by the piezoelectric structure 130 only contains the reflection based on the thin film 110. The electrical signal of the change of the induced charge produced by the transient deformation under the dynamic sound pressure. Therefore, based on the first sensing signal output by the piezoelectric structure 130, the change of the induced charge generated by the transient deformation of the film 110 under the dynamic sound pressure can be obtained, and then the transient deformation of the film 110 under the dynamic sound pressure can be obtained to realize The hydrophone 100 detects the dynamic sound pressure of underwater sound.

The position of the piezoelectric structure 130 on the membrane 110 can be set according to the stress distribution generated by the dynamic sound pressure of water acoustics acting on the membrane 110 . According to some embodiments, the shape of the area covered by the piezoelectric structure 130 on the thin film 110 includes a circle, a ring, or a combination of both. As shown in FIG. 2A , the area covered by the piezoelectric structure 130 on the thin film 110 is circular in shape. As shown in FIG. 2B , the area covered by the piezoelectric structure 130 on the thin film 110 is annular in shape. As shown in FIG. 2C , the shape of the area covered by the piezoelectric structure 130 on the thin film 110 is a combination of ring and circle.

It should be understood that the shape of the region covered by the piezoelectric structure 130 on the thin film 110 is only exemplary. Those skilled in the art can also set other shapes according to the stress distribution of the dynamic hydroacoustic action on the membrane 110 , which is not limited here.

In some embodiments, as shown in FIG. 2C and FIG. 2D , the area covered by the piezoelectric structure 130 on the film 110 includes a first area 130a located in the middle of the film 110 and a second area 130b different from the first area 130a, The first area 130a and the second area 130b are arranged at intervals. It will be appreciated that the arrangements shown in FIGS. 2C and 2D are exemplary only, and that in other embodiments, the first region 130a and the second region 130b may have other shapes.

The inventors have found through research that when the hydroacoustic pressure acts on the membrane, the stress distribution generated in the membrane has the following rules: when sensing the same dynamic pressure of underwater acoustics, different regions on the membrane may have stress distributions in opposite directions. Therefore, in this embodiment, the area covered by the piezoelectric structure 130 on the film 110 is set as the first area 130a and the second area 130b located in the middle of the film 110, so that the

piezoelectric structures

130 and 130 distributed in the first area 130a and The piezoelectric structures 130 distributed in the second region 130 b can respectively sense sensing signals of different signs (positive and negative) corresponding to different stress distribution directions on the film 110 in response to the physical deformation of the film 110 . The first sensing signal can be obtained by performing differential processing on the sensing signals of different signs. Since the first sensing signal is obtained by differential processing of sensing signals caused by stresses in different distribution directions on the film 110 generated by the dynamic sound pressure of the same underwater sound, its signal amplitude is compared with that of the sensing signal without differential processing. Larger and thus more sensitive to dynamic sound pressure. This makes it possible to detect a smaller dynamic sound pressure applied to the membrane 110 based on the first sensing signal, and also makes the detected dynamic sound pressure more accurate.

According to some embodiments, as shown in FIG. 2C and FIG. 2D , the shape of the first region 130 a is configured as a circle, and the shape of the second region 130 b is configured as a ring around the first region 130 a. For the case where the hydroacoustic pressure produces stress distributions in opposite directions in the middle of the membrane 110 and the surrounding areas other than the middle, this setting makes the distribution range of the piezoelectric structure 130 large enough to make the measurement results more accurate.

In some embodiments, as shown in FIG. 1 , the piezoelectric structure 130 includes a first electrode layer 131 , a piezoelectric layer 132 and a second electrode layer 133 sequentially stacked in a direction away from the film 110 . According to some embodiments, the materials of the first electrode layer 131 and the second electrode layer 132 include: molybdenum, platinum, titanium, etc., which are not limited herein. According to some embodiments, the thickness of the first electrode layer 131 and the second electrode layer 133 ranges from 100-1000 nm. According to some embodiments, the material of the piezoelectric layer 132 includes: aluminum nitride, lead zirconate titanate (PZT), lithium niobate, zinc oxide, etc., which are not limited herein. In some embodiments, the piezoelectric layer 122 has a thickness ranging from 300 nm to 3 μm.

The piezoresistive structure 120 is located at a peripheral region of the thin film 110 different from the central region 111 and is configured to generate a second sensing signal in response to physical deformation of the thin film 110 . The piezoresistive structure 120 produces a piezoresistive effect based on the deformation of the thin film 110 , and converts the strain into an electrical signal and outputs it as a second sensing signal. Wherein, the deformation of the membrane 110 includes transient deformation based on dynamic sound pressure and continuous deformation based on static water pressure, and the piezoresistive structure 120 generates an electrical signal (for example, a current signal or a voltage signal) reflecting the magnitude of the resistance value based on the deformation of the membrane 110 ). However, since the static water pressure applied to the membrane 110 is much greater than the dynamic sound pressure (for example, the magnitude of the static water pressure can be up to tens of orders of magnitude of the dynamic sound pressure), when the piezoresistive structure 120 responds to the When 110 generates an electrical signal based on the deformation caused by the dynamic sound pressure and the static water pressure, the electrical signal generated in response to the transient deformation of the membrane 110 caused by the dynamic sound pressure is compared to the electrical signal generated by the continuous deformation of the membrane 110 caused by the static water pressure. The electrical signal of can be ignored, so that the main component of the second sensing signal is the electrical signal generated by the piezoresistive structure 120 in response to the continuous deformation of the membrane 110 caused by the static water pressure. Therefore, the second sensing signal output by the piezoresistive structure 120 can be used as an electrical signal generated by the piezoresistive structure 120 in response to the continuous deformation of the film 110 caused by the static water pressure to detect the static water pressure applied to the film 110 .

According to the hydrophone 100 of this embodiment, through the second sensing signal output by the piezoresistive structure 120, the static water pressure of the hydrophone 100 in the environment where the hydrophone 100 is located can be detected, and the location of the hydrophone 100 can be realized. The monitoring of the static water pressure of the environment avoids damage to the hydrophone 100 due to excessive static water pressure in the environment. At the same time, based on the second sensing signal reflecting the static water pressure output by the piezoresistive structure 120, the piezoelectric structure 130 The output first sensing signal reflecting the dynamic sound pressure change is calibrated, so as to improve the accuracy of the sensitivity of the hydrophone 100 to detect the output signal of the dynamic sound pressure.

In some embodiments, as shown in FIG. 1 , the piezoelectric structure 130 is located above the piezoresistive structure 120 .

In some embodiments, as shown in FIG. 2D , the region where the piezoresistive structure 120 is distributed on the thin film 110 is located at the peripheral edge of the second region 130 b and is spaced from the second region 130 b. This arrangement makes the area covered by the piezoelectric structure 120 on the membrane 110 as large as possible, so that the piezoelectric structure 130 can sense dynamic sound pressure more sensitively. As mentioned above, the arrangement shown in FIG. 2D is only exemplary, and in other embodiments, the first region 130a and the second region 130b may have other shapes. In such other embodiments, the distribution area of the piezoresistive structure 120 at the thin film 110 may vary with the shape change of the second area 130b, but is located at the peripheral edge of the second area 130b.

It should be understood that, in the above embodiments, the introduction of the distribution positions of the piezoelectric structure 130 and the piezoresistive structure 120 on the thin film 110 is only exemplary. It should be understood by those skilled in the art that the piezoelectric structure 130 and the piezoresistive structure 120 can be distributed in any distribution form at the thin film 110, as long as the distribution can make the piezoelectric structure 130 respond to the physical deformation of the thin film 110 to generate representative dynamic sound. For the first sensing signal of pressure, the piezoresistive structure 120 can generate the second sensing signal representing the static water pressure in response to the physical deformation of the membrane 110 .

In some embodiments, as shown in FIG. 1 , the piezoresistive structure 120 includes at least one piezoresistor 120a.

According to some embodiments, as shown in FIG. 2 , at least one piezoresistor 120 a includes four piezoresistors 120 a uniformly distributed at the peripheral area of the membrane 110 . According to some embodiments, four varistors 120a form a Wheatstone bridge.

It should be understood that at least one varistor can also include any number of varistors, and the Wheatstone bridge formed by the arrangement and connection of varistors can also include the form of a full bridge, a half bridge, and a single-arm bridge. This is not limited.

In some embodiments, piezoresistor 120 a is located in membrane 110 . According to some embodiments, the piezoresistor 120 a includes a semiconductor doped region formed in the thin film 110 . In some embodiments, the semiconductor doped region is formed by an ion implantation process. In some other embodiments, the semiconductor doped region is formed by a diffusion doping process.

According to some embodiments, the element doped in the semiconductor doped region is boron, phosphorus, or arsenic, which is not limited herein. According to some embodiments, the depth of the semiconductor doped region ranges from 0.1 μm to 5 μm. According to some embodiments, the doping concentration of the semiconductor doped region ranges from 1×10 ¹⁵ /cm ³ to 1×10 ²⁰ /cm ³ .

In other embodiments, at least one piezoresistor 120a is located on the surface of the membrane 110 .

According to some embodiments, each piezoresistor 120a includes at least one of: doped diamond film, doped silicon, and doped silicon carbide. According to some embodiments, the type of element doped in the doped diamond film, doped silicon and doped silicon carbide is boron, phosphorus or arsenic, etc., which is not limited herein. According to some embodiments, the thickness of the piezoresistor 120 a ranges from 0.1 μm to 5 μm. According to some embodiments, the concentration of elements doped in doped polysilicon and doped silicon carbide ranges from 1×10 ¹⁵ /cm ³ to 1×10 ²⁰ /cm ³ .

In some embodiments, the piezoresistive structure 120 and the piezoelectric structure 130 further include contact structures on them, such as pads, leads, etc., which are not limited herein.

According to the hydrophone 100 of this embodiment, the piezoelectric structure 130 responds to the first sensing signal output by the hydroacoustic dynamic pressure by integrating the membrane 110 that senses the hydroacoustic pressure with the piezoelectric structure 130 and the piezoresistive structure 120, The piezoresistive structure 120 outputs the second sensing signal that basically reflects the static water pressure, and finally realizes the simultaneous detection of the dynamic pressure and the static water pressure of the hydrophone 100 . By detecting the static water pressure detected, the monitoring of the static water pressure of the environment where the hydrophone 100 is located is realized, and the hydrophone 100 is prevented from being damaged due to excessive static water pressure in the environment. The sensing signal is used to calibrate the first sensing signal output by the piezoelectric structure in response to the underwater acoustic dynamic pressure, thereby improving the accuracy of the sensitivity of the hydrophone 100 to detect the output signal of the dynamic sound pressure.

Embodiments of the present disclosure also provide a method for manufacturing a hydrophone, which can realize the manufacture of the hydrophone by using the mainstream MEMS process, and the manufactured hydrophone can detect the static water pressure in the environment where the MEMS hydrophone is used, While preventing damage to the membrane structure of the piezoelectric MEMS hydrophone, it can also calibrate the dynamic pressure signal detected by the hydrophone.

FIG. 3 is a flowchart of a method 300 of manufacturing a hydrophone according to an exemplary embodiment of the present disclosure.

An implementation of the method 300 is described below with reference to FIGS. 3 , 4 and 5A to 5F.

In step 310, a semiconductor substrate is provided. As shown in FIG. 5A , the semiconductor substrate 510 may be any type of semiconductor substrate, including a semiconductor-on-insulator substrate and the like. In such embodiments, semiconductor substrate 510 may be made of any suitable material (eg, silicon, germanium). In this context, referring to the orientation shown in FIG. 5A , the upper surface of the first substrate 510 is referred to as a first surface, and the lower surface of the first substrate 510 is referred to as a second surface opposite to the first surface.

In step 320, as shown in FIG. 5D, a piezoelectric structure 530 and a piezoresistive structure 520 are formed at the first surface of the semiconductor substrate. According to some embodiments, the piezoresistive structure 520 includes at least one piezoresistor 520 a in the semiconductor substrate 510 . Referring to FIG. 4 , an example process of forming piezoelectric and piezoresistive structures (step 320 ) in method 300 is described in accordance with an exemplary embodiment. In this embodiment, step 320 includes steps 410 to 430 .

In step 410 , as shown in FIG. 5B , a semiconductor doping process is performed on the semiconductor substrate 510 to form at least one semiconductor doped region 521 on the first surface of the semiconductor substrate 510 as the above-mentioned at least one varistor 520 a. In one embodiment, the semiconductor doping process adopts ion implantation process. In some other embodiments, the semiconductor doping process adopts a diffusion doping process. According to some embodiments, the doping element of the semiconductor doped region may be boron, phosphorus or arsenic, etc., which is not limited herein. According to some embodiments, the depth of the semiconductor doped region is in the range of 0.1-5 μm. According to some embodiments, the doping concentration of the semiconductor doped region ranges from 1×10 ¹⁵ /cm ³ to 1×10 ²⁰ /cm ³ .

In step 420 , as shown in FIG. 5C , a piezoelectric structural material stack 531 is formed, and the piezoelectric structural material stack 531 covers the first surface of the semiconductor substrate 510 .

In some embodiments, the piezoelectric structural material stack 531 includes a first material layer 532 , a piezoelectric material layer 533 and a second material layer 534 . According to some embodiments, the first material layer 532 and the second material layer 534 may be molybdenum, platinum, or titanium, etc., which are not limited herein. According to some embodiments, the piezoelectric material layer 533 may be aluminum nitride, lead zirconate titanate (PZT), lithium niobate, or zinc oxide, etc., which is not limited herein. According to some embodiments, forming the piezoelectric structural material stack 531 includes: sequentially forming a first electrode material layer 532 , a piezoelectric material layer 533 and a second electrode material layer 534 in a direction away from the thin film 510 . According to some embodiments, the methods of the first material layer 532 , the piezoelectric material layer 533 and the second material layer 534 include: chemical vapor deposition, physical vapor deposition, etc., which are not limited here.

In some embodiments, as shown in FIG. 5C , before forming the piezoelectric structural material stack 531 , a seed layer 535 is further formed, so that the piezoelectric structural material stack 531 formed in step 420 is formed on the seed layer 535 . The seed layer 535 includes the same material layer as the piezoelectric material layer 533 , for example, includes aluminum nitride, lead zirconate titanate (PZT), lithium niobate, or zinc oxide, etc., which is not limited herein. On the one hand, the seed layer 535 serves as an insulating layer between the piezoelectric material stack 531 and the semiconductor substrate 510 to insulate the semiconductor substrate 510 from the piezoelectric material stack 531; The bottom layer enables the formed piezoelectric material stack 531 to have a better crystal orientation. According to some embodiments, the method of forming the seed layer 535 includes chemical vapor deposition and physical vapor deposition, which are not limited herein.

In step 430 , as shown in FIG. 5D , the piezoelectric structure material stack 531 is patterned to form the piezoelectric structure 530 and expose the semiconductor doped region 521 . In some embodiments, as shown in FIG. 5D , the method for patterning the piezoelectric structural material stack 531 includes: sequentially patterning the second electrode material layer 534 , the piezoelectric material layer 533 and the first electrode material layer 532 to form The second electrode layer 534a, the piezoelectric layer 533a and the first electrode layer 532a. Patterning the second electrode material layer 534, patterning the piezoelectric material layer 533, and patterning the first electrode material layer 532 all include but are not limited to the following steps: a photolithography process step for forming a patterned mask layer, and patterning the mask layer The film layer is an etching process step of a mask, which is not limited here.

In step 330, as shown in FIG. 5F , a groove 560 is formed on the second surface opposite to the first surface of the semiconductor substrate 510, so that at least a part of the semiconductor substrate 510 forms a thin film 511, and the groove 560 is about the thin film 570. It is opposite to the piezoresistive structure 520 and the piezoelectric structure 530 . The piezoelectric structure 530 is located at a central area of the thin film 511, and the piezoresistive structure 520 is located at a peripheral area of the thin film 511 different from the central area where the piezoelectric structure 530 is located. According to some embodiments, the method of forming the groove 560 includes but not limited to removing a part of the semiconductor substrate 510 from the second surface of the semiconductor substrate 510 by etching, which is not limited here.

By forming the groove 560, a part of the semiconductor substrate 510 forms a thin film 511, which is used as a sensing element for the hydrophone to sense the underwater acoustic pressure, and respectively senses the dynamic sound pressure and the static water pressure of the underwater sound. The piezoelectric structure 530 is formed on the thin film 511 of the semiconductor substrate 510. Based on its own material properties, the piezoelectric structure 530 produces a piezoelectric effect in response to the deformation of the thin film 511 induced by the underwater acoustic pressure. In the charge change, the charge change based on the piezoelectric effect of the static water pressure is released by the circuit including its own resistance, so that the first output sensing signal is an electrical signal reflecting the charge change based on the piezoelectric effect of the dynamic sound pressure, and finally realizes Detection of dynamic sound pressure.

In this embodiment, a semiconductor doped region 521 is also formed in the semiconductor substrate 510 as the piezoresistor 520a of the piezoresistive structure 520, and outputs the second sensing signal reflecting the static water pressure of the water acoustics to realize the static water pressure of the water body. detection. The manufacture of hydrophones can be realized by adopting the mainstream MEMS technology, and the manufactured hydrophones can detect the static water pressure in the environment where the MEMS hydrophones are used, prevent the damage to the membrane structure of the piezoelectric MEMS hydrophones, and at the same time protect the hydrophones. The signal of the dynamic pressure detected by the instrument is calibrated.

In some embodiments, the method 300 further includes: before forming the groove 560 on the second surface of the semiconductor substrate 510 opposite to the first surface, at least one piezoresistor 520a, the first electrode layer 532a and the second electrode layer Corresponding pads 550 and leads (not shown) are formed on 534a. As shown in FIG. 5E, the pads 550 formed on the semiconductor substrate 510 are respectively in contact with the first piezoresistor 520a, the first electrode layer 532a and the second electrode layer 534a, and are connected to the semiconductor substrate through the dielectric layer 540. Other areas above 510 are isolated.

According to some embodiments, the method for forming corresponding pads 550 and leads on at least one varistor 520a, first electrode layer 532a, and second electrode layer 534a includes: forming a patterned dielectric layer 540, a patterned dielectric layer Grooves are formed in 540 to expose part of the varistor 520a, the first electrode layer 532a and the second electrode layer 534a; pads 550 and leads are formed, and the pads 550 and leads fill the grooves in the patterned dielectric layer 540 .

Another implementation of the method 300 is described below with reference to FIGS. 3 , 6 and 7A to 7F.

In step 310, a semiconductor substrate is provided. As shown in FIG. 7A , the semiconductor substrate 710 may be any type of semiconductor substrate, including a semiconductor-on-insulator substrate and the like. In such embodiments, semiconductor substrate 710 may be made of any suitable material (eg, silicon, germanium). In this context, referring to the orientation shown in FIG. 7A , the upper surface of the first substrate 710 is referred to as a first surface, and the lower surface of the first substrate 710 is referred to as a second surface opposite to the first surface.

In step 320 , as shown in FIG. 7D , a piezoelectric structure 730 and a piezoresistive structure 720 are formed at the first surface of the semiconductor substrate 710 . According to some embodiments, the piezoresistive structure 720 includes at least one piezoresistor 721 on the first surface of the semiconductor substrate 710 . Referring to FIG. 6 , an example process of forming a piezoelectric structure and a piezoresistive structure (step 320 ) is described in accordance with an exemplary embodiment. In this embodiment, step 320 includes steps 610 to 640 .

In step 610 , as shown in FIG. 7B , a piezoresistive material layer 721 is formed, and the piezoresistive material layer 721 covers the first surface of the semiconductor substrate 710 . In some embodiments, the method of forming the piezoresistive material 721 includes, but is not limited to, performing a deposition process and a doping process in sequence, which is not limited here. According to some embodiments, the piezoresistive material layer 721 includes doped diamond film, doped silicon or doped silicon carbide, etc., which is not limited herein. According to some embodiments, the elements doped in the doped diamond film, doped silicon and doped silicon carbide may be boron, phosphorus or arsenic, etc., which is not limited here. According to some embodiments, the piezoresistive material layer 721 has a thickness ranging from 0.1 μm to 5 μm. According to some embodiments, the concentration of elements doped in doped polysilicon and doped silicon carbide ranges from 1×10 ¹⁵ /cm ³ to 1×10 ²⁰ /cm ³ .

In some embodiments, as shown in FIG. 7B , a dielectric material layer 722 is also formed before forming the piezoresistive material layer 721 . The dielectric material layer 722 isolates the piezoresistive material layer 721 from the semiconductor substrate 710, so that the piezoresistive material layer 721 is isolated from the semiconductor substrate 710, so that the second output signal output by the piezoresistive material layer 721 can more accurately represent the voltage. The resistivity of the resistive structure 720 changes. According to some embodiments, the dielectric material layer 722 includes silicon oxide or silicon nitride, etc., which is not limited herein. According to some embodiments, the method for forming the dielectric material layer 722 includes, but is not limited to, any one of the following method groups: chemical vapor deposition, physical vapor deposition, etc., which are not limited herein.

In step 620 , as shown in FIG. 7C , a piezoelectric structural material stack 731 is formed, and the piezoelectric structural material stack 731 covers the piezoresistive material layer 721 . In some embodiments, the piezoelectric structural material stack 731 includes a first material layer 732 , a piezoelectric material layer 733 and a second material layer 734 . According to some embodiments, the first material layer 732 and the second material layer 734 include molybdenum, platinum or titanium, etc., which are not limited herein. According to some embodiments, the piezoelectric material layer 733 includes aluminum nitride, lead zirconate titanate (PZT), lithium niobate, or zinc oxide, etc., which is not limited herein. According to some embodiments, forming the piezoelectric structure material stack 731 includes: sequentially forming a first electrode material layer 732 , a piezoelectric material layer 733 and a second electrode material layer 734 in a direction away from the first surface of the semiconductor substrate 710 . According to some embodiments, the methods for forming the first electrode material layer 732 , the piezoelectric material layer 733 and the second electrode material layer 734 include chemical vapor deposition, physical vapor deposition, etc., which are not limited herein.

In some embodiments, as shown in FIG. 7C , before forming the piezoelectric structural material stack 731 , a seed layer 735 is further formed, so that the piezoelectric structural material stack 731 formed in step 620 is formed on the seed layer 735 . The seed layer 735 includes the same material layer as the piezoelectric material layer 733, for example, includes at least one of the following items: aluminum nitride, lead zirconate titanate (PZT), lithium niobate, zinc oxide, which is not limited here . On the one hand, the seed layer 735 serves as an insulating layer between the piezoelectric material stack 731 and the semiconductor substrate 710 to insulate the semiconductor substrate 710 from the piezoelectric material stack 731; The bottom layer enables the formed piezoelectric material stack 731 to have a better crystal orientation. According to some embodiments, the method of forming the seed layer 735 includes but not limited to at least one of the following methods: chemical vapor deposition and physical vapor deposition, which are not limited herein.

In step 630 , as shown in FIG. 7D , the piezoelectric structure material stack 731 is patterned to form the piezoelectric structure 730 and partially expose the piezoresistive material layer 721 . In some embodiments, the method for patterning the stack of piezoelectric structural materials 731 includes: sequentially patterning the second electrode material layer 734, the piezoelectric material layer 733 and the first electrode material layer 732 to form the second electrode layer 734a, The piezoelectric layer 733a and the first electrode layer 732a. Patterning the second electrode material layer 734, patterning the piezoelectric material layer 733, and patterning the first electrode material layer 732 all include but are not limited to the following steps: a photolithography process step for forming a patterned mask layer, and patterning the mask layer The film layer is an etching process step of a mask, which is not limited here.

In step 640 , as shown in FIG. 7D , the piezoresistive material layer 721 is patterned to form a piezoresistive structure 720 . In some embodiments, the method for patterning the piezoresistive material layer 721 includes but is not limited to the following steps: a photolithography process step of forming a patterned mask layer, and an etching process step using the patterned mask layer as a mask, No limitation is imposed here.

In step 330, as shown in FIG. 7F , a groove 760 is formed on the second surface opposite to the first surface of the semiconductor substrate 710, so that at least a part of the semiconductor substrate 710 forms a thin film 711, and the groove 760 is about the thin film 770. Opposite to piezoresistive structure 720 and piezoelectric structure 730 . The piezoelectric structure 730 is located at a central area of the thin film 711, and the piezoresistive structure 720 is located at a peripheral area of the thin film 711 different from the central area where the piezoelectric structure 730 is located. According to some embodiments, the method of forming the groove 760 includes but is not limited to removing a part of the semiconductor substrate 710 from the second surface of the semiconductor substrate 710 by etching, which is not limited here.

By forming the groove 760, a part of the semiconductor substrate 710 is formed into a thin film 711, and the thin film 711 is used as a sensing element for the hydrophone to sense the underwater acoustic pressure, and respectively senses the dynamic sound pressure and the static water pressure of the underwater sound. The piezoelectric structure 730 is formed on the thin film 711 of the semiconductor substrate 710. Based on its own material properties, the piezoelectric structure 730 produces a piezoelectric effect in response to the deformation of the thin film 711 induced by the underwater acoustic pressure. In the charge change, the charge change based on the piezoelectric effect of the static water pressure is released by a circuit including its own resistance, so that the output first sensing signal is constituted as an electrical signal reflecting the charge change based on the piezoelectric effect of the dynamic sound pressure, Finally, the detection of dynamic sound pressure is realized.

In this embodiment, by forming the piezoresistive material layer 721 on the semiconductor substrate 710 as the piezoresistor 720a of the piezoresistive structure 720, the second sensing signal reflecting the static water pressure of the water sound is output to realize the static water pressure of the water body. detection. The manufacture of hydrophones can be realized by adopting the mainstream MEMS technology, and the manufactured hydrophones can detect the static water pressure in the environment where the MEMS hydrophones are used, prevent the damage to the membrane structure of the piezoelectric MEMS hydrophones, and at the same time protect the hydrophones. The signal of the dynamic pressure detected by the instrument is calibrated.

In some embodiments, the method 300 further includes: before forming the groove 760 on the second surface of the semiconductor substrate 710 opposite to the first surface, at least one piezoresistor 720a, the first electrode layer 732a and the second electrode layer Corresponding pads 750 and leads are formed on 734a. According to some embodiments, the method for forming the pad 750 on the semiconductor substrate 710 includes: first, as shown in FIG. 720a, part of the first conductive layer 732a and part of the groove 741 of the second conductive layer 734a; then, as shown in FIG.

According to the manufacturing method of the hydrophone of the present disclosure, it can realize the manufacture of the hydrophone by adopting the mainstream MEMS technology, and the manufactured hydrophone can detect the static water pressure in the environment where the MEMS hydrophone is used, and prevent the piezoelectric MEMS water While the membrane structure of the earphone is damaged, the dynamic pressure signal detected by the hydrophone can also be calibrated.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative and exemplary and not restrictive; the disclosure is not limited to the disclosed the embodiment. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps not listed, the indefinite article "a" or "an" does not exclude a plurality, and the term "plurality" means two or more . The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

A hydrophone comprising:

a membrane configured to physically deform in response to dynamic sound pressure and static water pressure;

a piezoelectric structure configured to generate a first sensing signal in response to the physical deformation; and

A piezoresistive structure configured to generate a second sensing signal in response to the physical deformation.
The hydrophone of claim 1, wherein the piezoresistive structure includes at least one piezoresistor.
The hydrophone of claim 2, wherein said at least one piezoresistor comprises four piezoresistors uniformly distributed at the surface of said membrane, said four piezoresistors forming a Wheatstone bridge.
2. The hydrophone of claim 2, wherein said at least one piezoresistor is located in said membrane.
4. The hydrophone of claim 4, wherein each of said piezoresistors includes a semiconductor doped region formed in said membrane.
2. The hydrophone of claim 2, wherein said at least one piezoresistor is located on a surface of said membrane.
The hydrophone of claim 6, wherein the material of each piezoresistor comprises at least one selected from the group consisting of: doped diamond film, doped silicon, and doped silicon carbide .
The hydrophone according to any one of claims 1-7, wherein the piezoresistive structure is located at the edge of the membrane.
7. The hydrophone of any one of claims 1-7, wherein the membrane has a shape selected from the group consisting of rectangular and circular.
The hydrophone according to any one of claims 1-7, wherein the shape of the area covered by the piezoelectric structure on the membrane comprises at least one selected from the group consisting of: circular shape and ring.
The hydrophone according to claim 10, wherein the area covered by the piezoelectric structure on the membrane includes a first area located in the middle of the membrane and a second area different from the first area, wherein The first area is spaced apart from the second area.
The hydrophone of claim 11, wherein the first region has a circular shape and the second region has a ring shape surrounding the first region.
The hydrophone of claim 11, wherein the region where the piezoresistive structure is distributed at the membrane is located at a peripheral edge of the second region and is spaced from the second region.
A method of manufacturing a hydrophone, comprising:

Provide semiconductor substrates;

forming a piezoelectric structure and a piezoresistive structure at the first surface of the semiconductor substrate; and

A groove is formed on a second surface of the semiconductor substrate opposite to the first surface, so that at least a part of the semiconductor substrate forms a thin film, and the groove is related to the thin film and the piezoresistive structure and The piezoelectric structure is opposite.
The method of claim 14, wherein the piezoresistive structure includes at least one piezoresistor in the semiconductor substrate, and wherein the piezoresistive structure is formed at the first surface of the semiconductor substrate and Piezoelectric structures include:

performing a semiconductor doping process on the semiconductor substrate to form at least one semiconductor doped region at the first surface as the at least one varistor;

forming a stack of piezoelectric structural material overlying the first surface; and

The piezoelectric structure material stack is patterned to form the piezoelectric structure and expose the at least one semiconductor doped region.
The method of claim 14, wherein said piezoresistive structure comprises at least one piezoresistor on said first surface, and wherein said piezoresistive formation at said first surface of said semiconductor substrate Structural and piezoelectric structures include:

forming a piezoresistive material layer, the piezoresistive material layer covering the first surface;

forming a piezoelectric structural material stack, the piezoelectric structural material stack covering the piezoresistive material layer;

patterning the piezoelectric structure material stack to form the piezoelectric structure and partially expose the piezoresistive material layer; and

The layer of piezoresistive material is patterned to form the at least one piezoresistor.
The method of claim 16, wherein forming the piezoresistive material layer comprises:

performing a deposition process to form a first material layer overlying the first surface; and

A doping process is performed to dope the first material layer to form the piezoresistive material layer.
The method according to claim 15 or 16, wherein the piezoelectric structure comprises a first electrode layer, a piezoelectric layer and a second electrode layer stacked in sequence in a direction away from the film,

Wherein, forming the stack of piezoelectric structural materials includes: sequentially forming a first electrode material layer, a piezoelectric material layer and a second electrode material layer in a direction away from the first surface, and

Wherein, patterning the piezoelectric structural material stack includes: sequentially patterning the second electrode material layer, the piezoelectric material layer and the first electrode material layer to form the second electrode layer, the the piezoelectric layer and the first electrode layer.
The method of claim 18, further comprising:

Before forming the piezoelectric structural material stack, a seed layer is formed, wherein the seed layer includes the material of the piezoelectric material layer,

Wherein, the stack of piezoelectric structural materials is formed on the seed layer.
The method of claim 14, further comprising:

Before forming grooves on the second surface of the semiconductor substrate opposite to the first surface, corresponding solder joints are formed on the at least one piezoresistor, the first electrode layer, and the second electrode layer. plate and leads.