Three-dimensional composite pressure sensitive membrane structure and preparation method thereof

Abstract

The present invention provides a three-dimensional composite pressure-sensitive diaphragm structure and a preparation method thereof. The integration of a beam-island structure can reduce the deformation of a hole-blocking membrane layer under load, thereby avoiding the problem of linearity deterioration caused by large deflection deformation; the integration of the beam-island structure can concentrate stress on a central beam where detection resistors are arranged, thereby achieving an effect of "amplifying" a detection signal, thereby achieving high sensitivity; and in the present invention, the central island and wing islands are separately arranged, which are more flexible in design, can retain the concentrated effect of stress on the central beam, and can avoid the problem of sensitivity reduction caused by excessive rigidification due to the arrangement of large-sized islands, and can also avoid the problem of stress concentration on sensitive films around large-sized islands, thereby improving overload capacity; further, by arranging the inner island release holes on the central island, the wing islands and the outer islands of the beam, and the outer island release holes arranged on the substrate area, a flexible layout of the release holes can be achieved, thereby improving the release efficiency of the structure.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon micromechanical sensing and relates to a three-dimensional composite pressure-sensitive diaphragm structure and a preparation method thereof. Background Art

[0002] MEMS pressure sensors mainly include the following categories according to their working principles: piezoresistive, capacitive, optical fiber, resonant and piezoelectric. Among them, piezoresistive pressure sensors detect pressure changes through the piezoresistive effect of semiconductor materials. They have the advantages of high sensitivity, good linearity, simple interface circuit, ability to measure static and dynamic pressure signals, and low price. They are widely used in consumer electronics, automobiles, industry, medical care, aerospace and other fields.

[0003] As an important core structure of the pressure sensor, the mechanical properties of the pressure sensitive diaphragm structure directly determine the performance of the sensor. The flat diaphragm pressure sensitive diaphragm structure is easy to design and process, and is the most commonly used structural form. However, for MEMS pressure sensors with a small range, it is usually necessary to monitor very small pressure difference changes in real time. If the flat diaphragm pressure sensitive diaphragm structure is still used, a large and thin diaphragm is required to meet the required sensitivity, but the consistency and yield of the large and thin diaphragm are difficult to control in actual processing. Moreover, the large deflection deformation caused by the pressure to be measured will lead to mechanical nonlinearity, thereby causing serious nonlinear errors. When the beam-island structure is integrated on the pressure sensitive film to form a three-dimensional composite pressure sensitive diaphragm structure, it is conducive to achieving a balance between linearity and sensitivity: on the one hand, the pressure sensitive diaphragm can be properly reinforced to avoid the nonlinear problem caused by large deflection deformation; at the same time, under the pressure to be measured, stress concentration will be generated at the beam structure, and the detection piezoresistors arranged in the stress concentration area will bring a larger output signal due to the greater stress, thereby achieving high sensitivity. However, how to efficiently prepare a beam-island-membrane composite pressure-sensitive diaphragm structure with high sensitivity, high yield, high consistency and low cost has always been a difficult problem in the industry.

[0004] In the prior art, the three-dimensional composite pressure-sensitive diaphragm structure mostly adopts an integrated island structure, which has the following defects:

[0005] 1) The island has greater rigidity than the sensitive film. Large-sized islands will lead to excessive rigidity of the composite sensitive structure, resulting in decreased sensitivity and failure to take into account higher sensitivity.

[0006] 2) The large-sized island has excessive stiffness, which may cause the sensitive film around the island to rupture easily due to stress concentration under high pressure.

[0007] Therefore, it is necessary to provide a three-dimensional composite pressure-sensitive membrane structure and a preparation method thereof. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a three-dimensional composite pressure-sensitive diaphragm structure and a preparation method thereof, so as to solve the application problem of the three-dimensional composite pressure-sensitive diaphragm structure with integrated island in the prior art.

[0009] In order to achieve the above-mentioned object and other related objects, the present invention provides a three-dimensional composite pressure-sensitive membrane structure, wherein the three-dimensional composite pressure-sensitive membrane structure comprises:

[0010] A single crystal silicon substrate, the single crystal silicon substrate comprising a beam-island-membrane region and a substrate region;

[0011] A patterned beam-island-membrane three-dimensional composite membrane, wherein the beam-island-membrane three-dimensional composite membrane is located in the beam-island-membrane region, and comprises a hole-blocking membrane layer and a patterned single crystal silicon layer from bottom to top, wherein the patterned single crystal silicon layer comprises a central beam, a central island and wing islands, wherein the central island is connected to the central beam, and the wing islands are arranged separately from the central island;

[0012] An intra-island release hole, wherein the intra-island release hole is located in the beam-island-membrane region, and the hole-blocking membrane layer fills the intra-island release hole;

[0013] An out-island release hole, wherein the out-island release hole is located in the substrate region, and the hole-blocking film layer fills the out-island release hole;

[0014] A reference pressure chamber is located in the single crystal silicon substrate, and the projections of the release holes inside the island and the release holes outside the island are both located inside the reference pressure chamber, and the beam-island-membrane three-dimensional composite diaphragm is released through the reference pressure chamber.

[0015] Optionally, the patterned single crystal silicon layer further includes discrete outer beam islands, and the inner island release holes are arranged on the outer beam islands.

[0016] Optionally, the three-dimensional composite pressure-sensitive diaphragm structure is distributed axially symmetrically along the central beam.

[0017] Optionally, the material of the hole-plugging film layer includes polycrystalline silicon, amorphous silicon or single crystal silicon; and the single crystal silicon substrate includes a (111) crystal plane single crystal silicon substrate.

[0018] Optionally, the beam-island-membrane three-dimensional composite membrane includes, from bottom to top, the hole-blocking membrane layer, a dielectric layer and the patterned single crystal silicon layer.

[0019] Optionally, a reference pressure back hole is further included, the reference pressure back hole is connected to the reference pressure cavity, and the projection of the island covers the reference pressure back hole.

[0020] The present invention also provides a method for preparing a three-dimensional composite pressure-sensitive membrane structure, comprising the following steps:

[0021] Providing a single crystal silicon substrate, the single crystal silicon substrate comprising a beam-island-membrane region and a substrate region;

[0022] forming an insulating layer on the surface of the single crystal silicon substrate;

[0023] Patterning the insulating layer, and etching the single crystal silicon substrate to form a groove in the single crystal silicon substrate;

[0024] forming a passivation layer on the surface of the insulating layer and the inner wall of the trench;

[0025] Patterning the passivation layer to expose the bottom of the groove;

[0026] Patterning the single crystal silicon substrate, forming an island-inside release hole located in the beam-island-membrane region and an island-outside release hole located in the substrate region based on the groove;

[0027] Wet etching is performed based on the release holes inside the island and the release holes outside the island to remove part of the single crystal silicon substrate to release the single crystal silicon layer to form a reference pressure chamber;

[0028] removing the passivation layer and the insulating layer;

[0029] forming a hole-blocking film layer, wherein the hole-blocking film layer covers the surface of the single crystal silicon substrate, the inner wall of the reference pressure chamber and blocks the release holes inside the island and the release holes outside the island;

[0030] removing the pore-blocking film layer located on the surface of the single crystal silicon substrate;

[0031] The single crystal silicon layer is patterned to obtain a beam-island-membrane three-dimensional composite membrane including the hole-plugging membrane layer and the patterned single crystal silicon layer from bottom to top, wherein the patterned single crystal silicon layer includes a central beam, a central island and side islands, the central island is connected to the central beam, and the side islands are separately arranged from the central island.

[0032] Optionally, the patterned single crystal silicon layer further includes discretely arranged outer beam islands, and the inner island release holes are formed on the outer beam islands.

[0033] Optionally, between the steps of removing the passivation layer and the insulating layer and forming the hole-plugging film layer, a step of forming a dielectric layer on the surface of the single crystal silicon substrate, the surface of the reference pressure chamber and the inner wall of the release hole is also included.

[0034] Optionally, the method further includes forming a reference pressure back hole from the back side of the single crystal silicon substrate, wherein the reference pressure back hole is connected to the reference pressure cavity, and the projection of the island covers the reference pressure back hole.

[0035] As described above, the three-dimensional composite pressure-sensitive diaphragm structure and the preparation method thereof of the present invention form a beam-island-membrane three-dimensional composite diaphragm by integrating a beam-island structure on the pore-blocking membrane layer, wherein the integration of the beam-island structure can reduce the deformation of the pore-blocking membrane layer under load, and avoid the linearity deterioration problem caused by large deflection deformation; the integration of the beam-island structure can concentrate the stress on the central beam where the detection resistor is arranged, which has the effect of "amplifying" the detection signal, thereby achieving high sensitivity; and in the present invention, including the discretely arranged central island and wing islands, the design is more flexible, which can retain the concentrated effect of stress on the central beam, while avoiding the problem of excessive rigidification and reduced sensitivity due to the setting of large-sized islands, and can also avoid the problem of stress concentration in the sensitive film around the large-sized islands, thereby improving the overload capacity; further, through the island release holes arranged on the central island, the wing islands and the island outside the beam, and the island release holes arranged on the substrate area, a flexible layout of the release holes can be achieved, thereby improving the release efficiency of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Shown is a schematic diagram of the three-dimensional structure of the three-dimensional composite pressure-sensitive diaphragm structure with an integrated island structure in the comparative example.

[0037] Figure 2 Shown is a schematic diagram of the process flow for preparing a three-dimensional composite pressure-sensitive membrane structure in an embodiment of the present invention.

[0038] Figure 3 to Figure 16 It is a schematic diagram of the structure presented in each step when preparing a three-dimensional composite pressure-sensitive membrane structure in an embodiment of the present invention.

[0039] Description of Reference Numerals

[0040] 10 Liang

[0041] 20 islands

[0042] 30 membrane

[0043] 100 Single crystal silicon substrate

[0044] 101 Groove

[0045] 102 Release hole

[0046] 103 Reference pressure chamber

[0047] 112 Island release hole

[0048] 122 Release hole outside the island

[0049] 110 Single crystal silicon layer

[0050] 200 Insulation

[0051] 300 Passivation layer

[0052] 400 Dielectric Layer

[0053] 410 Surface dielectric layer

[0054] 420 interlayer dielectric layer

[0055] 500 pore blocking film layer

[0056] 600 Beam-Island-Membrane Three-Dimensional Composite Diaphragm

[0057] 601 center beam

[0058] 612 Central Island

[0059] 622 Flanking Island

[0060] 632 Liangwai Island

[0061] 700 Reference pressure back hole

[0062] A Beam-Island-Membrane Area

[0063] B substrate area DETAILED DESCRIPTION

[0064] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0065] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0066] For ease of description, spatial relational terms such as “under”, “below”, “below”, “below”, “over”, etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other orientations of the device in use or operation in addition to the orientation depicted in the drawings, and may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, so that the first and second features may not be in direct contact. In addition, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or one or more intervening layers may also be present.

[0067] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0068] Comparative Example

[0069] like Figure 1 The comparative example provides a beam-island-membrane three-dimensional composite diaphragm, which includes a beam 10 and an island 20 located on a membrane 30, and the beam 10 and the island 20 are interconnected. Although the beam-island-membrane three-dimensional composite diaphragm can reduce the deformation of the membrane 30 under load and avoid the linearity deterioration problem caused by large deflection deformation, the stress is concentrated on the beam 10 where the detection resistor is arranged, which has the effect of "amplifying" the detection signal, thereby achieving high sensitivity. Moreover, since the island 20 has a greater rigidity than the thinner membrane 30, arranging a release hole (not shown) thereon does not have an adverse effect on the mechanical properties of the structure. Therefore, the beam-island-membrane three-dimensional composite diaphragm of this scheme has good mechanical properties and reliability. However, in order to accelerate corrosion to release the beam-island-membrane three-dimensional composite diaphragm, when a release hole is added to the island 20, this will further increase the size and rigidity of the island 20, thereby causing the overall rigidity of the beam-island-membrane three-dimensional composite diaphragm to be too large, resulting in a decrease in sensitivity. Therefore, a trade-off needs to be made between higher sensitivity and faster corrosion release time. Furthermore, the integrated island 20 has a larger size and thus a greater rigidity, which may cause the sensitive film 30 around the island 20 to easily break due to stress concentration under high pressure.

[0070] Example

[0071] See also Figure 2The present embodiment provides a method for preparing a three-dimensional composite pressure-sensitive diaphragm structure. The present embodiment forms a beam-island-membrane three-dimensional composite diaphragm by integrating a beam-island structure on a hole-blocking membrane layer, wherein the integration of the beam-island structure can reduce the deformation of the hole-blocking membrane layer under load, and avoid the linearity deterioration problem caused by large deflection deformation; the integration of the beam-island structure can concentrate the stress on the central beam where the detection resistor is arranged, which has the effect of "amplifying" the detection signal, thereby achieving high sensitivity; and in the present embodiment, including a discretely arranged central island and wing islands, the design is more flexible, which can retain the concentrated effect of stress on the central beam, while avoiding the problem of excessive rigidification and reduced sensitivity caused by the setting of large-sized islands, and can also avoid the problem of stress concentration on the sensitive film around the large-sized island, thereby improving the overload capacity; further, by arranging the island release holes on the central island, the wing islands and the island outside the beam, and the island release holes outside the island arranged on the substrate area, a flexible layout of the release holes can be achieved, thereby improving the release efficiency of the structure.

[0072] See also Figure 3 to Figure 16 The following introduces the three-dimensional composite pressure-sensitive membrane structure and its preparation method related to this embodiment in conjunction with the drawings in the specification.

[0073] First, see Figure 2 and Figure 3 , perform step S1, provide a single crystal silicon substrate 100, and the single crystal silicon substrate 100 includes a beam-island-membrane region A and a substrate region B.

[0074] Specifically, in this embodiment, the single crystal silicon substrate 100 is divided into the beam-island-membrane region A and the substrate region B.

[0075] The single crystal silicon substrate 100 is preferably a (111) crystal plane single crystal silicon substrate to prepare a high-quality three-dimensional composite pressure sensitive membrane structure. The size and thickness of the single crystal silicon substrate 100 are not limited here and can be selected according to needs.

[0076] Next, see Figure 2 and Figure 3 , executing step S2 , forming an insulating layer 200 on the surface of the single crystal silicon substrate 100 .

[0077] Specifically, the insulating layer 200 can protect the single crystal silicon substrate 100 and avoid damage to the single crystal silicon substrate 100 when the subsequent step S5, ie, patterning the passivation layer 300, is performed.

[0078] The material of the insulating layer 200 may be selected as a silicon oxide layer or a silicon nitride layer according to needs, and the method of forming the insulating layer 200 may include a thermal oxidation method, a CVD method, etc.

[0079] Next, see Figure 2 and Figure 3 , executing step S3 , patterning the insulating layer 200 , and etching the single crystal silicon substrate 100 to form a groove 101 in the single crystal silicon substrate 100 .

[0080] Specifically, a patterned photoresist layer (not shown) can be first formed on the surface of the insulating layer 200 by coating, exposing, and developing, and then the insulating layer 200 is etched based on the patterned photoresist layer to pattern the insulating layer 200. Thereafter, the single crystal silicon substrate 100 is patterned by etching to form the groove 101 in the single crystal silicon substrate 100 to prepare for the subsequent preparation of the release hole 102.

[0081] The type of the photoresist layer can be selected according to needs, and the removal method of the photoresist layer can be, for example, an ashing method, etc. The size and distribution of the grooves 101 can be set according to the needs of the subsequent release holes 102 .

[0082] Next, see Figure 2 and Figure 4 , executing step S4 to form a passivation layer 300 on the surface of the insulating layer 200 and the inner wall of the trench 101 .

[0083] Specifically, the material of the passivation layer 300 may be selected as a silicon oxide layer or a silicon nitride layer, etc., and the method of forming the passivation layer 300 may include a thermal oxidation method, a CVD method, etc., as required.

[0084] Next, see Figure 2 and Figure 4 , executing step S5, patterning the passivation layer 300 to expose the bottom of the groove 101.

[0085] Specifically, dry etching can be directly used without a patterned photoresist layer to remove the lateral passivation layer 300 to expose the bottom of the groove 101, while retaining the passivation layer 300 on the sidewall of the groove 101 to facilitate subsequent etching processes.

[0086] Next, see Figure 2 and Figure 4 , executing step S6, patterning the single crystal silicon substrate 100, forming an island-inside release hole 112 located in the beam-island-membrane area A and an island-outside release hole 122 located in the substrate area B based on the groove 101.

[0087] Specifically, the retained passivation layer 300 and the insulating layer 200 can protect the single crystal silicon substrate 100 during the etching process. Based on the groove 101 of the single crystal silicon substrate 100, the single crystal silicon substrate 100 can be etched to form Figure 4 The release hole 102 in Fig. 9 and Fig.11 The island release holes 112 located in the beam-island-membrane area A and the island release holes 122 located in the substrate area B are provided, so that the release efficiency of the structure is improved through the setting of the island release holes 112 and the island release holes 122.

[0088] Next, see Figure 2 and Figure 5 , executing step S7, performing wet etching based on the inner island release hole 112 and the outer island release hole 122, removing part of the single crystal silicon substrate 100 to release the single crystal silicon layer 110 to form a reference pressure chamber 103.

[0089] Specifically, the selection of the etching solution and the control of the process parameters of the wet etching can be selected according to needs and are not limited here.

[0090] Next, see Figure 2 and Figure 6 , perform step S8 to remove the passivation layer 300 and the insulating layer 200, such as by wet etching or other methods, which is not limited here.

[0091] Next, see Figure 2 and Figure 7 , executing step S9 to form a hole-blocking film layer 500 , wherein the hole-blocking film layer 500 covers the surface of the single crystal silicon substrate 100 , the inner wall of the reference pressure chamber 103 and blocks the release hole 102 .

[0092] Specifically, the material of the hole-blocking film layer 500 may be selected from polycrystalline silicon, amorphous silicon, monocrystalline silicon, etc., and the method of forming the hole-blocking film layer 500 may include CVD, epitaxy, etc. Among them, the thickness of the formed hole-blocking film layer 500 should at least reach the thickness that can block the release hole 102. Since the inner wall of the reference pressure cavity 103, especially the top of the reference pressure cavity 103, has the hole-blocking film layer 500, the hole-blocking film layer 500 can be used as the bottom sensitive film in the beam-island-membrane three-dimensional composite diaphragm 600.

[0093] Next, see Figure 2 and Figure 8 , executing step S10, removing the hole-blocking film layer 500 located on the surface of the single crystal silicon substrate 100.

[0094] Specifically, the pore-blocking film layer 500 located on the surface of the single crystal silicon substrate 100 may be removed by etching, but the present invention is not limited thereto.

[0095] Next, see Figure 2 and Figure 8 , executing step S11, patterning the single crystal silicon layer 110, obtaining a beam-island-membrane three-dimensional composite membrane 600 including the hole-blocking membrane layer 500 and the patterned single crystal silicon layer 110 from bottom to top, wherein, referring to Fig. 9 Indicated Figure 8 The top view structural diagram of the three-dimensional composite pressure-sensitive diaphragm structure is shown in FIG. 1 . In this embodiment, the patterned single crystal silicon layer 110 includes a central beam 601, a central island 612 and side islands 622. The central island 612 is connected to the central beam 601, and the side islands 622 are separately arranged from the central island 612.

[0096] Specifically, a patterned photoresist layer can be formed on the surface of the single crystal silicon layer 110 by coating, exposing, and developing to serve as a mask, so that the single crystal silicon layer 110 in the exposed area can be selectively removed to form the beam-island-membrane three-dimensional composite membrane 600, and then the excess photoresist layer can be removed.

[0097] In order to achieve good performance of the three-dimensional composite pressure-sensitive membrane structure, in this embodiment, the three-dimensional composite pressure-sensitive membrane structure is axially symmetrically distributed along the central beam 601, such as Fig. 9 The dotted line in can be regarded as the axis of symmetry.

[0098] For further information, see Fig.11 When patterning the single crystal silicon layer 110 , it may further include forming a discrete outer beam island 632 in the single crystal silicon layer 110 , and the inner island release hole 112 is formed on the outer beam island 632 .

[0099] Specifically, the central island 612 and the side islands 622 can be regarded as inner islands of the beam, and the islands far away from the central beam 601 can be regarded as outer islands of the beam 632. Therefore, by setting the outer islands of the beam 632, the number of release holes 112 in the islands can be effectively increased, thereby improving the release efficiency of the structure.

[0100] For further information, see Fig.10 and Fig.11 ,in, Fig.11 Indicated Fig.10 The top view structural diagram of the three-dimensional composite pressure-sensitive diaphragm structure described in the figure, in another embodiment, may also include the step of forming a reference pressure back hole 700 from the back side of the single crystal silicon substrate 100, wherein the reference pressure back hole 700 is connected to the reference pressure cavity 103, and the projection of the island covers the reference pressure back hole 700.

[0101] Specifically, after the reference pressure back hole 700 is formed on the back side of the single crystal silicon substrate 100 , a differential pressure sensor can be prepared, wherein the vertical projection of the central island 612 , the side island 622 or the beam outer island 632 covers the reference pressure back hole 700 .

[0102] In another embodiment, between the above steps S8 and S9 , a step of forming a dielectric layer 400 on the surface of the single crystal silicon substrate 100 , the surface of the reference pressure chamber 103 and the inner wall of the release hole 102 may be included.

[0103] Specifically, the following steps may be included:

[0104] See also Fig.12 and Fig.16 , forming the dielectric layer 400 on the surface of the single crystal silicon substrate 100, the surface of the reference pressure chamber 103 and the inner wall of the release hole 102, wherein the dielectric layer 400 includes a surface dielectric layer 410 located on the single crystal silicon layer 110 and an interlayer dielectric layer 420 located under the single crystal silicon layer 110;

[0105] See also Fig.13 , forming the hole-blocking film layer 500, the hole-blocking film layer 500 covers the surface of the single crystal silicon substrate 100, the inner wall of the reference pressure chamber 103 and blocks the release hole 102;

[0106] See also Fig.14 , removing the hole-blocking film layer 500 located on the surface of the single crystal silicon substrate 100;

[0107] See also Fig.15 , patterning is performed to obtain the beam-island-membrane three-dimensional composite membrane 600 including the hole-plugging membrane layer 500, the interlayer dielectric layer 420, the single crystal silicon layer 110 and the surface dielectric layer 410 from bottom to top, wherein the beam-island structure includes the central beam 601, the central island 612 and the side islands 622, the central island 612 is connected to the central beam 601, and the side islands 622 are separately arranged from the central island 612.

[0108] In this example, when the beam-island-membrane three-dimensional composite membrane 600 is patterned, the interlayer dielectric layer 420 can be used as an etching self-stop layer when etching the single crystal silicon layer 110 to avoid over-etching the hole-blocking membrane layer 500. If necessary, after the etching of the single crystal silicon layer 110 is completed, the exposed interlayer dielectric layer 420 can also be removed, such as Fig.15 4 shows a structural diagram of removing the exposed interlayer dielectric layer 420.

[0109] Similarly, see Fig.16 According to the needs, it may also include the steps of forming the discretely arranged outer beam island 632 having the inner island release hole 112 and / or forming the reference pressure back hole 700, which will not be elaborated here.

[0110] See also Figure 3 to Figure 16 This embodiment further provides a three-dimensional composite pressure-sensitive membrane structure, the three-dimensional composite pressure-sensitive membrane structure comprising:

[0111] A single crystal silicon substrate 100, wherein the single crystal silicon substrate 100 comprises a beam-island-membrane region A and a substrate region B;

[0112] A patterned beam-island-membrane three-dimensional composite membrane 600, wherein the beam-island-membrane three-dimensional composite membrane 600 is located in the beam-island-membrane area A, and comprises a hole-blocking membrane layer 500 and a patterned single crystal silicon layer 110 from bottom to top, wherein the patterned single crystal silicon layer 110 comprises a central beam 601, a central island 612 and wing islands 622, wherein the central island 612 is connected to the central beam 601, and the wing islands 622 are arranged separately from the central island 612;

[0113] An intra-island release hole 112, wherein the intra-island release hole 112 is located in the beam-island-membrane region A, and the hole-blocking film layer 500 fills the intra-island release hole 112;

[0114] The outer-island release hole 122 is located in the substrate region B, and the hole-blocking film layer 500 fills the outer-island release hole 122;

[0115] A reference pressure chamber 103 is provided, wherein the reference pressure chamber 103 is located in the single crystal silicon substrate 100 , and the projections of the release holes 112 inside the island and the release holes 122 outside the island are both located inside the reference pressure chamber 103 , and the beam-island-membrane three-dimensional composite diaphragm 600 is released through the reference pressure chamber 103 .

[0116] As an example, the three-dimensional composite pressure-sensitive diaphragm structure is distributed in an axisymmetric manner along the central beam 601 .

[0117] As an example, the hole-plugging film layer 500 includes polycrystalline silicon, amorphous silicon or single crystal silicon; and the single crystal silicon substrate 100 includes a (111) crystal plane single crystal silicon substrate.

[0118] As an example, the beam-island-membrane three-dimensional composite membrane 600 includes the hole-blocking membrane layer 500 , the dielectric layer 400 and the patterned single crystal silicon layer 110 from bottom to top.

[0119] As an example, the patterned single crystal silicon layer 110 further includes discretely arranged outer beam islands 632 , and the inner island release holes 112 are arranged on the outer beam islands 632 .

[0120] As an example, a reference pressure back hole 700 is further included, the reference pressure back hole 700 is connected to the reference pressure chamber 103 , and the projection of the island covers the reference pressure back hole 700 .

[0121] The preparation of the three-dimensional composite pressure-sensitive diaphragm structure may refer to the above-mentioned preparation method, but the preparation of the three-dimensional composite pressure-sensitive diaphragm structure is not limited to this. In this embodiment, the preparation of the three-dimensional composite pressure-sensitive diaphragm structure is directly formed by the above-mentioned preparation method, so the material, structure, etc. of the three-dimensional composite pressure-sensitive diaphragm structure may refer to the above-mentioned preparation method, which will not be elaborated here.

[0122] In summary, the three-dimensional composite pressure-sensitive diaphragm structure and the preparation method thereof of the present invention integrate a beam-island structure on the pore-blocking membrane layer to form a beam-island-membrane three-dimensional composite diaphragm. The integration of the beam-island structure can reduce the deformation of the pore-blocking membrane layer under load and avoid the linearity deterioration problem caused by large deflection deformation; the integration of the beam-island structure can concentrate the stress on the central beam where the detection resistor is arranged, which has the effect of "amplifying" the detection signal, thereby achieving high sensitivity; and in the present invention, including the discretely arranged central island and wing islands, the design is more flexible, which can retain the concentrated effect of stress on the central beam, while avoiding the problem of excessive rigidification and decreased sensitivity due to the setting of large-sized islands, and can also avoid the problem of stress concentration in the sensitive film around the large-sized islands, thereby improving the overload capacity; further, through the island release holes arranged on the central island, the wing islands and the island outside the beam, and the island release holes arranged on the substrate area, a flexible layout of the release holes can be achieved to improve the release efficiency of the structure.

[0123] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A three-dimensional composite pressure-sensitive membrane structure, characterized in that: The three-dimensional composite pressure-sensitive membrane structure comprises: A single crystal silicon substrate, the single crystal silicon substrate comprising a beam-island-membrane region and a substrate region; A patterned beam-island-membrane three-dimensional composite membrane, wherein the beam-island-membrane three-dimensional composite membrane is located in the beam-island-membrane region, and comprises a hole-blocking membrane layer and a patterned single crystal silicon layer from bottom to top, wherein the patterned single crystal silicon layer comprises a central beam, a central island and wing islands, wherein the central island is connected to the central beam, and the wing islands are arranged separately from the central island; An intra-island release hole, wherein the intra-island release hole is located in the beam-island-membrane region, and the hole-blocking membrane layer fills the intra-island release hole; An out-island release hole, wherein the out-island release hole is located in the substrate region, and the hole-blocking film layer fills the out-island release hole; A reference pressure chamber is located in the single crystal silicon substrate, and the projections of the release holes inside the island and the release holes outside the island are both located inside the reference pressure chamber, and the beam-island-membrane three-dimensional composite diaphragm is released through the reference pressure chamber.

2. The three-dimensional composite pressure-sensitive membrane structure according to claim 1, characterized in that: The patterned single crystal silicon layer also includes discrete outer beam islands, and the inner island release holes are arranged on the outer beam islands.

3. The three-dimensional composite pressure-sensitive membrane structure according to claim 1, characterized in that: The three-dimensional composite pressure-sensitive diaphragm structure is distributed in an axisymmetric manner along the central beam.

4. The three-dimensional composite pressure-sensitive membrane structure according to claim 1, characterized in that: The material of the hole-blocking film layer includes polycrystalline silicon, amorphous silicon or single crystal silicon; the single crystal silicon substrate includes a (111) crystal plane single crystal silicon substrate.

5. The three-dimensional composite pressure-sensitive membrane structure according to claim 1, characterized in that: The beam-island-membrane three-dimensional composite membrane comprises, from bottom to top, the hole-blocking membrane layer, a dielectric layer and the patterned single crystal silicon layer.

6. The three-dimensional composite pressure-sensitive membrane structure according to claim 1, characterized in that: It also includes a reference pressure back hole, which is communicated with the reference pressure cavity, and the projection of the island covers the reference pressure back hole.

7. A method for preparing a three-dimensional composite pressure-sensitive membrane structure, characterized in that: The following steps are involved: Providing a single crystal silicon substrate, the single crystal silicon substrate comprising a beam-island-membrane region and a substrate region; forming an insulating layer on the surface of the single crystal silicon substrate; Patterning the insulating layer, and etching the single crystal silicon substrate to form a groove in the single crystal silicon substrate; forming a passivation layer on the surface of the insulating layer and the inner wall of the trench; Patterning the passivation layer to expose the bottom of the groove; Patterning the single crystal silicon substrate, forming an island-inside release hole located in the beam-island-membrane region and an island-outside release hole located in the substrate region based on the groove; Wet etching is performed based on the release holes inside the island and the release holes outside the island to remove part of the single crystal silicon substrate to release the single crystal silicon layer to form a reference pressure chamber; removing the passivation layer and the insulating layer; forming a hole-blocking film layer, wherein the hole-blocking film layer covers the surface of the single crystal silicon substrate, the inner wall of the reference pressure chamber and blocks the release holes inside the island and the release holes outside the island; removing the pore-blocking film layer located on the surface of the single crystal silicon substrate; The single crystal silicon layer is patterned to obtain a beam-island-membrane three-dimensional composite membrane including the hole-plugging membrane layer and the patterned single crystal silicon layer from bottom to top, wherein the patterned single crystal silicon layer includes a central beam, a central island and side islands, the central island is connected to the central beam, and the side islands are separately arranged from the central island.

8. The method for preparing a three-dimensional composite pressure-sensitive membrane structure according to claim 7, characterized in that: The patterned single crystal silicon layer also includes discrete outer beam islands, and the inner island release holes are formed on the outer beam islands.

9. The method for preparing a three-dimensional composite pressure-sensitive membrane structure according to claim 7, characterized in that: Between the steps of removing the passivation layer and the insulating layer and forming the hole-blocking film layer, a step of forming a dielectric layer on the surface of the single crystal silicon substrate, the surface of the reference pressure chamber and the inner wall of the release hole is also included.

10. The method for preparing a three-dimensional composite pressure-sensitive membrane structure according to claim 7, characterized in that: The method also includes the step of forming a reference pressure back hole from the back side of the single crystal silicon substrate, wherein the reference pressure back hole is connected to the reference pressure cavity, and the projection of the island covers the reference pressure back hole.

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