Piezoelectric device and electronic equipment
By setting a stress adjustment layer in the piezoelectric device and adjusting its position, the problem of warping of the piezoelectric device is solved, and reliability and production efficiency are improved.
Patent Information
- Application Number
- CN202411803486.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-09
- Publication Date
- 2025-03-18
AI Technical Summary
During the production of piezoelectric devices, due to the differences in thermal expansion coefficients of each film layer and the introduction of stress during the deposition process, piezoelectric devices will produce greater warping, reducing the reliability of piezoelectric devices.
By providing a stress adjustment layer in the piezoelectric device and adjusting the set position of the stress adjustment layer according to the stress adjustment layer and the stress type in the piezoelectric layer, the stress adjustment layer can balance the warping caused by the piezoelectric layer in the piezoelectric device.
The warpage of piezoelectric devices is reduced, the reliability of piezoelectric devices is improved, and the yield and production efficiency are improved.
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Figure CN119654052A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of piezoelectric technology, in particular to a piezoelectric device and an electronic device. Background Art
[0002] Piezoelectric devices can realize the mutual conversion between pressure signals and electrical signals, and are widely used in micro-electromechanical systems, sensors, actuators and other electronic devices. However, in the process of manufacturing piezoelectric devices, due to the difference in thermal expansion coefficients of each film layer and the stress introduced during the deposition process, the piezoelectric device will produce a large warp, which reduces the reliability of the piezoelectric device.
[0003] Therefore, how to reduce the warping of the piezoelectric device to improve the reliability of the piezoelectric device has become a technical problem that needs to be solved urgently in this field. Summary of the invention
[0004] Embodiments of the present invention provide a piezoelectric device and an electronic device, which are used to improve the reliability of the piezoelectric device by reducing the warping of the piezoelectric device.
[0005] In a first aspect, an embodiment of the present invention provides a first piezoelectric device, comprising: a stacked substrate, a stress adjustment layer, a first electrode layer, a second electrode layer and a piezoelectric layer;
[0006] The first electrode layer, the piezoelectric layer and the second electrode layer are sequentially stacked on one side of the substrate;
[0007] The stress adjustment layer and the piezoelectric layer have the same stress type, and the stress adjustment layer is located on the other side of the substrate.
[0008] In a second aspect, an embodiment of the present invention provides a second piezoelectric device, comprising: a stacked substrate, a stress adjustment layer, a first electrode layer, a second electrode layer and a piezoelectric layer;
[0009] The first electrode layer, the piezoelectric layer and the second electrode layer are sequentially stacked on one side of the substrate;
[0010] The stress adjustment layer and the piezoelectric layer have different stress types. The stress adjustment layer is located between the first electrode layer and the substrate or the stress adjustment layer is located on a side of the second electrode layer away from the substrate.
[0011] In a third aspect, an embodiment of the present invention provides an electronic device, comprising the piezoelectric device as described in the first aspect or the second aspect above.
[0012] The beneficial effects of the present invention are as follows:
[0013] A piezoelectric device and electronic device provided by an embodiment of the present invention include: a stacked substrate, a stress adjustment layer, a first electrode layer, a second electrode layer and a piezoelectric layer; the first electrode layer, the piezoelectric layer and the second electrode layer are stacked in sequence on one side of the substrate; when the stress types of the stress adjustment layer and the piezoelectric layer are the same, the stress adjustment layer is located on the other side of the substrate; when the stress types of the stress adjustment layer and the piezoelectric layer are different, the stress adjustment layer is located between the first electrode layer and the substrate or the stress adjustment layer is located on the side of the second electrode layer away from the substrate. In this way, by setting a stress adjustment layer in the piezoelectric device and adjusting the setting position of the stress adjustment layer according to the stress types in the stress adjustment layer and the piezoelectric layer, the stress adjustment layer can balance the warping caused by the piezoelectric layer in the piezoelectric device, thereby reducing the warping of the piezoelectric device, improving the reliability of the piezoelectric device, and improving the production yield and production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 A cross-sectional view of a first piezoelectric device provided in an embodiment of the present invention;
[0015] Figure 2 is a cross-sectional view of a second piezoelectric device provided in an embodiment of the present invention;
[0016] Figure 3 is a cross-sectional view of a third piezoelectric device provided in an embodiment of the present invention;
[0017] Figure 4 It is a schematic diagram of an orthographic projection of a first stress adjustment layer and a piezoelectric layer on a substrate provided in an embodiment of the present invention;
[0018] Figure 5 It is a schematic diagram of an orthographic projection of a second stress adjustment layer provided in an embodiment of the present invention on a substrate;
[0019] Figure 6 It is a schematic diagram of an orthographic projection of a third stress adjustment layer provided in an embodiment of the present invention on a substrate;
[0020] Figure 7 It is a schematic diagram of an orthographic projection of a fourth stress adjustment layer provided in an embodiment of the present invention on a substrate;
[0021] Figure 8 A partial enlarged view of a stress adjustment layer of a mesh structure provided in an embodiment of the present invention;
[0022] Fig. 9 It is a schematic diagram of an orthographic projection of a fifth stress adjustment layer provided in an embodiment of the present invention on a substrate;
[0023] Fig.10 It is a schematic diagram of an orthographic projection of a sixth stress adjustment layer provided in an embodiment of the present invention on a substrate;
[0024] Fig.11 The present invention is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0025] The following will be combined with the accompanying drawings to describe in detail the specific implementation of a piezoelectric device and an electronic device provided by an embodiment of the present invention. It should be noted that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0026] An embodiment of the present invention provides a piezoelectric device, such as Figure 1 As shown, it includes: a stacked substrate 100, a stress adjustment layer 200, a first electrode layer 301, a second electrode layer 302 and a piezoelectric layer 400;
[0027] The first electrode layer 301, the piezoelectric layer 400 and the second electrode layer 302 are sequentially stacked on one side of the substrate 100;
[0028] The stress adjustment layer 200 and the piezoelectric layer 400 have the same stress type, and the stress adjustment layer 400 is located on the other side of the substrate 100 .
[0029] In this way, when the stress types of the piezoelectric layer and the stress adjustment layer are the same, that is, the stress types are both compressive stress or both tensile stress, the stress adjustment layer and the piezoelectric layer are respectively arranged on both sides of the substrate, so that the stress adjustment layer can balance the warping caused by the piezoelectric layer in the piezoelectric device, thereby reducing the warping of the piezoelectric device, improving the reliability of the piezoelectric device, and improving the production yield and production efficiency.
[0030] Based on the same inventive concept, the embodiment of the present invention also provides another piezoelectric device, such as Figure 2 As shown, it includes: a stacked substrate 100, a stress adjustment layer 200, a first electrode layer 301, a second electrode layer 302 and a piezoelectric layer 400;
[0031] The first electrode layer 301, the piezoelectric layer 400 and the second electrode layer 302 are sequentially stacked on one side of the substrate 100;
[0032] The stress adjustment layer 200 and the piezoelectric layer 400 have different stress types. The stress adjustment layer 200 is located between the first electrode layer 301 and the substrate 100 or the stress adjustment layer 200 is located on a side of the second electrode layer 302 away from the substrate 100 .
[0033] In this way, when the stress types of the piezoelectric layer and the stress adjustment layer are different, that is, the piezoelectric layer is compressive stress and the stress adjustment layer is tensile stress or the piezoelectric layer is tensile stress and the stress adjustment layer is compressive stress, the piezoelectric layer and the stress adjustment layer are arranged on the same side of the substrate, so that the stress adjustment layer can balance the warping caused by the piezoelectric layer in the piezoelectric device, thereby reducing the warping of the piezoelectric device, improving the reliability of the piezoelectric device, and improving the production yield and production efficiency.
[0034] Among them, for the above two piezoelectric devices, the stress types of the piezoelectric layer and the stress adjustment layer are related to their manufacturing materials and processes. For example, taking the manufacturing material of the piezoelectric layer as lead zirconate titanate, there is usually tensile stress in the piezoelectric layer made of lead zirconate titanate. At this time, a stress adjustment layer with tensile stress can be made on the side of the substrate away from the piezoelectric layer, such as but not limited to making a film layer with tensile stress such as lead zirconate titanate, molybdenum or titanium oxide, or a stress adjustment layer with compressive stress can be made between the substrate and the first electrode layer or on the side of the second electrode layer away from the substrate, such as but not limited to making a film layer with compressive stress such as silicon nitride. Of course, the piezoelectric layer can also be made of other piezoelectric materials, the stress type in the piezoelectric layer can also be compressive stress, and the stress adjustment layer can also be made of other film layers with compressive stress or tensile stress, which are not specifically limited here.
[0035] It should be understood that in a piezoelectric device, the thickness and stress of each film layer are different, so the degree of warping of the piezoelectric device caused by each film layer is also different. The Stoney formula can usually be used to describe the relationship between the stress of the film layer and the warping caused by the film layer. The Stoney formula is:
[0036]
[0037] Among them, σ f is the stress of the film, E s is the Young's modulus of the substrate, t s is the thickness of the substrate, ν s is the Poisson's ratio of the substrate, t f is the thickness of the film layer, and R is the bending radius caused by the film layer, that is, the warping caused by the film layer.
[0038] Specifically, by performing a deposition experiment on an 8-inch wafer with a thickness of 0.5 mm and calculating according to the Stoney formula, the following Table 1 can be obtained. In Table 1, the ITO (Indium Tin Oxides) film layer can be the first electrode and the second electrode of the piezoelectric device, the LNO (Lanthanum Nickel Oxide) film layer can be the buffer layer between the substrate and the first electrode in the piezoelectric device, and the PZT (Lead Zirconate Titanate) film layer can be the piezoelectric layer of the piezoelectric device. The bow height represents the vertical distance between the center and the edge of the substrate when the substrate is placed on a horizontal surface. The bow height is proportional to the bending radius, and the change in the bow height can reflect the size of the bending radius caused by the film layer. As can be seen from Table 1, the absolute value of the change in the bow height caused by the PZT film layer is much larger than that of other film layers, so the substrate of the PZT film layer will produce a larger warp, that is, the stress in the piezoelectric layer is the main cause of the warp of the piezoelectric device, and thus the focus needs to be on eliminating the warp of the piezoelectric device caused by the piezoelectric layer. Therefore, when setting the stress adjustment layer, if the stress types of the piezoelectric layer and the stress adjustment layer are the same, the stress adjustment layer and the piezoelectric layer can be respectively set on both sides of the substrate; if the stress types of the piezoelectric layer and the stress adjustment layer are different, the piezoelectric layer and the stress adjustment layer can be set on the same side of the substrate. Such a setting can balance the warping caused by the piezoelectric layer to a greater extent, thereby reducing the warping of the piezoelectric device to a greater extent and improving the reliability of the piezoelectric device.
[0039] Table 1
[0040] Film Bow height change value / μm Stress Type Stress value / MPa Thickness / nm ITO -43.38 Tensile stress 31.43 500 LNO -80.34 Tensile stress 432.49 100 PZT -574.81 Tensile stress 140.62 3000
[0041] It is worth noting that the Stoney formula describes the warping caused by the setting of the entire film layer. Based on the Stoney formula, when the area of the film layer is unknown, the product of the thickness of the film layer and the area can be used to represent the warping caused by the film layer, where the thickness product is the product of the film layer stress and the film layer thickness.
[0042] Optionally, the piezoelectric layer and the stress adjustment layer satisfy Formula 1:
[0043] |σ 1 |×t 1 ×S 1 =|σ 2 |×t 2 ×S 2
[0044] Among them, σ 1 is the stress of the piezoelectric layer, t 1 is the thickness of the piezoelectric layer, S 1 is the area of the piezoelectric layer, σ 2 is the stress of the stress adjustment layer, t 2is the thickness of the stress adjustment layer, S 2 is the area of the stress adjustment layer.
[0045] In this way, when the piezoelectric layer and the stress adjustment layer satisfy the above formula 1, the stress adjustment layer can eliminate the warping caused by the piezoelectric layer. When the warping of the piezoelectric device mainly comes from the piezoelectric layer, the setting of the stress adjustment layer can effectively reduce the warping of the piezoelectric device and improve the reliability of the piezoelectric device.
[0046] It should be understood that when the stress type is tensile stress, a positive value can be used to represent the stress magnitude, and when the stress type is compressive stress, a negative value can be used to represent the stress magnitude, and the sign is only used to distinguish the type of stress.
[0047] In addition, the thickness product of the film layer inside the piezoelectric device has a critical value, which can be called the critical breaking point. The critical breaking point is related to the material and size of the substrate, and its specific value can be obtained through experiments. When the thickness product of the film layer is greater than the critical breaking point, cracks may occur inside the piezoelectric device. Therefore, when making the stress adjustment layer, it is necessary to calculate the relationship between the thickness product of the stress adjustment layer and the critical breaking point, so that the thickness product of the stress adjustment layer is less than or equal to the critical breaking point, so as to avoid cracks inside the piezoelectric device and improve the reliability of the piezoelectric device.
[0048] When the piezoelectric device has no transparency requirement, the stress adjustment layer satisfies the above formula 1, and when the stress type is the same as the piezoelectric layer, the stress adjustment layer is arranged on both sides of the substrate respectively with the piezoelectric layer; when the stress type is different from the piezoelectric layer, the stress adjustment layer is arranged on the same side of the substrate with the piezoelectric layer, thereby reducing the warping of the piezoelectric device and improving the reliability of the piezoelectric device.
[0049] When the piezoelectric device is integrated with a display, the piezoelectric device may be a transparent piezoelectric device. In this case, there are additional requirements for the setting of the stress adjustment layer. The following introduces the setting of the stress adjustment layer when the piezoelectric device is a transparent piezoelectric device.
[0050] Optionally, the piezoelectric device is a transparent piezoelectric device, and the material of the stress adjustment layer is a transparent material. The transparent material includes, but is not limited to, lead zirconate titanate, titanium oxide, silicon nitride and the like. Thus, by providing a stress adjustment layer made of a transparent material, not only can the warping of the piezoelectric device be reduced and the reliability of the piezoelectric device be improved, but also the transparency of the piezoelectric device can be improved, thereby improving the display effect when the piezoelectric device is integrated with a display.
[0051] Optionally, the stress adjustment layer is provided as a whole layer. In this way, when the material of the stress adjustment layer is transparent, the stress adjustment layer is provided as a whole layer, which can also ensure the transparency of the piezoelectric device, thereby reducing the difficulty of manufacturing the stress adjustment layer and thus reducing the manufacturing cost of the piezoelectric device.
[0052] Alternatively, if Figure 3 As shown, the stress adjustment layer 200 and the piezoelectric layer 400 are made of the same material, and their areas are both 50% of the area of the substrate 100 , and the orthographic projections of the stress adjustment layer 200 and the piezoelectric layer 400 on the substrate 100 do not overlap each other.
[0053] In this way, the stress adjustment layer and the piezoelectric layer are made of the same material, which can simplify the manufacturing process of the piezoelectric device. In addition, the area of both is half of the substrate area, and the orthographic projections do not overlap, making the transmittance of the piezoelectric device more uniform. When the piezoelectric device is integrated with the display, the display effect is improved.
[0054] It should be understood that Figure 3 The figure is only a schematic diagram of the positional relationship between the stress adjustment layer 200 and the piezoelectric layer 400, and does not represent the specific structure of the stress adjustment layer 200 and the piezoelectric layer 400. Specifically, Figure 4 As shown, Figure 4 This is a schematic diagram of the orthographic projection of the stress adjustment layer 200 and the piezoelectric layer on the substrate. The piezoelectric layer may include a plurality of structural units 401, and the structural units 401 are arranged in an array. In this way, the piezoelectric device can vibrate uniformly in different areas, thereby improving the piezoelectric performance of the piezoelectric device. The orthographic projection of the stress adjustment layer 200 and the orthographic projection of each structural unit 401 do not overlap with each other, thereby reducing the warping of the piezoelectric device while ensuring the uniformity of light transmission.
[0055] Of course, the shape of the structural units in the piezoelectric layer is not limited to a square, but can also be other shapes such as a rectangle, a circle, a hexagon, etc. The number of structural units in the piezoelectric layer is not limited to 9, but can be set to any number. The shape, setting number, and arrangement of the structural units in the piezoelectric layer can be set according to actual needs and are not limited here.
[0056] Optionally, the piezoelectric device is a transparent piezoelectric device, and the material of the stress adjustment layer is a non-transparent material. Thus, when the piezoelectric device is a transparent piezoelectric device, the stress adjustment layer can also be made of a non-transparent material, thereby increasing the flexibility of setting the stress adjustment layer.
[0057] Optionally, when the piezoelectric device is a transparent piezoelectric device and the material of the stress adjustment layer is a non-transparent material, such as Figure 5 and Figure 6 As shown, the orthographic projection of the stress adjustment layer 200 on the substrate 100 is located at the edge of the substrate 100. In this way, by arranging the stress adjustment layer 200 at the edge, while arranging the stress adjustment layer 200 to reduce the warpage of the piezoelectric device, the influence of the stress adjustment layer 200 on the transparency of the piezoelectric device can be reduced, and thus a transparent piezoelectric device can be manufactured even when the material of the stress adjustment layer 200 is a non-transparent material.
[0058] Furthermore, if Figure 5As shown, when the substrate is rectangular, the orthographic projection of the stress adjustment layer 200 on the substrate 100 may be located at the four corners of the substrate 100, or, as shown in FIG. Figure 6 As shown, when the substrate is rectangular, the orthographic projection of the stress adjustment layer 200 on the substrate 100 can also be located at the four sides of the substrate 100. In this way, when the orthographic projection of the stress adjustment layer 200 on the substrate 100 is located at the edge of the substrate 100, the stress adjustment layer 200 can be arranged in a variety of ways to reduce the influence of the stress adjustment layer 200 on the transparency of the piezoelectric device, thereby improving the flexibility of the arrangement of the stress adjustment layer 200.
[0059] Of course, when the substrate is rectangular, the stress adjustment layer is not limited to being arranged at the four corners or four sides, and can also be arranged at some of the corners or some of the sides, for example, the stress adjustment layer is arranged only at two corners, or the stress adjustment layer is arranged only at one side, and the specific arrangement method can be selected according to actual needs and is not limited here. In addition, the shape of the substrate is not limited to a rectangle, and can also be a circle or other shapes. Accordingly, the stress adjustment layer can also be arranged at the edge of a circle or other shape, and the specific arrangement method can be selected according to actual needs and is not specifically limited here.
[0060] Alternatively, if Figure 7 As shown, Figure 7 : is a schematic diagram of the orthographic projection of the stress adjustment layer 200 on the substrate 100. The stress adjustment layer 200 is a mesh structure, and the transmittance of the mesh structure is greater than or equal to 70%. In this way, by setting the stress adjustment layer 200 as a mesh structure, the stress adjustment layer is evenly distributed, and the reliability of the piezoelectric device is improved; in addition, the transmittance of the mesh structure is greater than or equal to 70%, achieving a higher transmittance, and the transmittance distribution is uniform everywhere, thereby improving the display effect when the piezoelectric device is integrated with the display.
[0061] It should be understood that Figure 8 As shown, Figure 8 for Figure 7 The local enlarged view of the area shown in the dotted box Q1, taking the line width d1 of the mesh structure as 50μm as an example, when the transmittance of the mesh structure is equal to 70%, it can be calculated that the size d2 of the mesh hole of the mesh structure is approximately 65μm, that is, when the line width d1 of the mesh structure is 50μm, the size d2 of the mesh hole of the mesh structure can be set to be greater than or equal to 65μm, thereby achieving a transmittance of the mesh structure greater than or equal to 70%.
[0062] Furthermore, if Figure 8As shown, the line width d1 of the mesh structure is less than 73 μm. In this way, the line width d1 of the mesh structure is less than 73 μm. At an observation distance of 25 cm, the line width d1 is smaller than the smallest discernible size of the human eye, so that the mesh structure cannot be directly observed by the human eye, and when the piezoelectric device is integrated with the display, the display effect is improved.
[0063] It should be understood that the minimum resolution angle of the human eye is about 1 arc minute, that is, 1 / 60 degree. When the distance between the human eye and the observed object, that is, the observation distance, is x, the minimum resolvable size M can be calculated using Formula 2:
[0064]
[0065] Using the above formula 2, when the observation distance x is 25 cm, it can be calculated that the minimum resolvable size M is about 73 μm. Therefore, when the line width is set to be less than 73 μm, when the observation distance is greater than or equal to 25 cm, the mesh structure can be prevented from being directly measured, thereby improving the display effect.
[0066] Of course, when the observation distance is less than 25 cm, the line width can be set smaller according to the above formula 2, and the specific line width can be selected according to actual needs, which is not limited here. In addition, the line widths of the mesh structure can be the same or different, and the mesh shape of the mesh structure can be but not limited to: rectangular, triangular, circular, etc., and the line width and mesh shape are not specifically limited here.
[0067] Alternatively, if Fig. 9 As shown, Fig. 9 Schematic diagram of the orthographic projection of the stress adjustment layer on the substrate 100, the stress adjustment layer includes a plurality of stress adjustment units 201 arranged in an array, thereby forming a stress adjustment layer with a mesh structure. The size of the stress adjustment unit 201 is less than 73 μm, and the sizes of the stress adjustment units 201 can be the same or different, which is not limited here.
[0068] Thus, a stress adjustment layer with a mesh structure can be formed in a variety of ways, which improves the flexibility of setting the stress adjustment layer. Of course, in addition to the above two forms of mesh structures, other mesh structures well known to those skilled in the art can also be used, which are not specifically limited here.
[0069] The piezoelectric device provided by the embodiment of the present invention is explained below in conjunction with specific embodiments.
[0070] Take the piezoelectric device as a transparent piezoelectric device, the transparent substrate size is 120mm×60mm, the thickness is 0.5mm, the piezoelectric layer material is PZT, the stress type is tensile stress, the stress magnitude is 140.62MPa, the thickness is 3μm, and the area is half of the substrate area as an example. In addition, since a high-temperature heat treatment process is required when the piezoelectric layer is made of PZT material, the substrate needs to be stable at high temperatures. The material of the substrate can be, but is not limited to, alkaline earth boron aluminum silicate glass or quartz glass with a glass strain temperature greater than or equal to 700°C. The following is a specific description of the setting method when the stress adjustment layer is made of different materials.
[0071] 1. The material of the stress adjustment layer is PZT.
[0072] When the material of the stress adjustment layer is also PZT, the area of the stress adjustment layer can be set to half of the substrate area, and the orthographic projections of the stress adjustment layer and the piezoelectric layer on the substrate do not overlap each other, and then according to the above formula 1, the thickness of the stress adjustment layer is the same as the thickness of the piezoelectric layer, and the stress adjustment layer and the piezoelectric layer are respectively arranged on both sides of the substrate. In this way, the uniformity of the transmittance of the piezoelectric device is improved.
[0073] Furthermore, in the process of manufacturing piezoelectric devices, when the warpage of the piezoelectric device is between -50 μm and 50 μm, the automatic conveying and adsorption device of the semiconductor production line can be used. The warpage range can be reflected by an ITO film layer with a stress value of 31.43 MPa and a 500 nm deposition on the entire surface, that is, the thickness product of the entire layer is 15715 MPa·nm. This thickness product can be called the critical thickness product A. According to the Stoney formula, the critical thickness product A satisfies the following formula 3:
[0074] |σ 2 |×Δt 2 ×S 2 =A×S 3
[0075] Among them, σ 2 is the stress of the stress adjustment layer, Δt 2 is the maximum deviation of the stress adjustment layer thickness, S 2 is the area of the stress adjustment layer, S 3 is the area of the substrate, so the thickness of the stress adjustment layer is set at [t 2 +Δt 2 , t 2 +Δt 2 ] range, the warpage of the piezoelectric device can be achieved between -50μm and 50μm.
[0076] Therefore, when the material of the stress adjustment layer is PZT, Δt can be obtained according to Formula 3: 2is 0.22 μm, so the thickness range of the stress adjustment layer is [2.78 μm, 3.22 μm].
[0077] 2. The material of the stress adjustment layer is titanium oxide.
[0078] Titanium oxide is a transparent material, so titanium oxide can be deposited in a whole layer to ensure the transparency of the piezoelectric device. However, the stress of titanium oxide is a tensile stress of 7384.29 MPa. If the whole layer is deposited, the thickness of the stress adjustment layer may be too thin and cannot be accurately controlled, thereby reducing the reliability of the piezoelectric device. Therefore, when the material of the stress adjustment layer is titanium oxide, the setting area of the stress adjustment layer can be reduced, and the stress adjustment layer and the piezoelectric layer are respectively set on both sides of the substrate.
[0079] by Fig.10 Take the structure shown as an example, Fig.10 is a schematic diagram of an orthographic projection of the stress adjustment layer 200 on the substrate 100. Fig.10 The stress adjustment layer 200 is located at the edges of the two long sides of the substrate 100 and has a width of 1.28 mm, that is, the area of the stress adjustment layer 200 is 2×120 mm×1.28 mm=307.2 mm 2 According to Formula 1, the thickness t2 of the stress adjustment layer 200 can be calculated to be 669.48 nm. Further, according to Formula 3, Δt2 can be calculated to be 49.88 nm, so the thickness range of the stress adjustment layer is [619.6 nm, 719.36 nm].
[0080] 3. The material of the stress adjustment layer is silicon nitride.
[0081] The stress adjustment layer made of silicon nitride exhibits compressive stress, and the stress magnitude can be adjusted by deposition temperature and power. Taking the deposition temperature of 210°C, the deposition power of 1500W, and the stress magnitude of -163MPa as an example, the stress adjustment layer can be deposited as a whole layer, and the stress adjustment layer and the piezoelectric layer are located on the same side of the substrate. According to formula 1, the thickness t2 of the stress adjustment layer can be calculated to be 1.3μm. Further, according to formula 3, Δt2 can be obtained to be 0.1μm, so the thickness range of the stress adjustment layer is [1.2μm, 1.4μm].
[0082] 4. The material of the stress adjustment layer is molybdenum.
[0083] The stress type of the stress adjustment layer formed by molybdenum is compressive stress when it is not heat-treated at room temperature, and the stress magnitude is -163MPa. After vacuum annealing at 900℃, the stress type is tensile stress, and the stress magnitude is 630MPa. Here, taking the annealed molybdenum as an example, the stress adjustment layer and the piezoelectric layer are respectively arranged on both sides of the substrate. The stress adjustment layer can be arranged in the following three ways, but is not limited to:
[0084] (1) Figure 5 As shown, 10 mm×10 mm stress adjustment layers are provided at the four corners.
[0085] At this time, according to formula 1:
[0086] 140.62MPa×3μm×120mm×60mm×0.5=630MPa×t 2 ×4×10mm×10mm
[0087] From this, the thickness of the stress adjustment layer t can be calculated 2 is 6μm. Further, according to formula 3, Δt 2 is 0.45 μm, so the thickness range of the stress adjustment layer is [5.55 μm, 6.45 μm].
[0088] (2) Figure 6 As shown, stress adjustment layers with a width of 10 mm are provided on four sides.
[0089] At this time, the thickness of the stress adjustment layer t can be calculated according to formula 1: 2 is 0.67μm, and then according to formula 3, Δt 2 is 0.05 μm, so the thickness range of the stress adjustment layer is [0.62 μm, 0.72 μm].
[0090] (3) Figure 7 As shown, the stress adjustment layer is configured as a mesh structure, and the transmittance of the mesh structure is equal to 70%.
[0091] At this time, since the transmittance of the mesh structure is equal to 70%, the area of the stress adjustment layer is 30% of the substrate area. According to Formula 1, the thickness of the stress adjustment layer can be calculated as: 2 is 1.12μm, and then according to formula 3, Δt 2 is 0.08 μm, so the thickness range of the stress adjustment layer is [1.04 μm, 1.2 μm].
[0092] In summary, the stress adjustment layer can be made of materials such as PZT, titanium oxide, silicon nitride, and molybdenum, and its thickness can be calculated using Formula 1 and Formula 3. Therefore, the stress adjustment layer can be set to reduce the warping of the piezoelectric device and improve the reliability of the piezoelectric device.
[0093] Of course, the specific parameters of each membrane layer (including the substrate, piezoelectric layer, and stress adjustment layer) given in the above content are all examples. The specific area, thickness, and material of the substrate and piezoelectric layer can be set according to actual needs. Then, according to the specific area, thickness, and material of the substrate and piezoelectric layer, the material and structure of the stress adjustment layer are selected, and the area and thickness of the stress adjustment layer are calculated. The material, structure, area, and thickness of the stress adjustment layer are not specifically limited here.
[0094] Based on the same inventive concept, an embodiment of the present invention further provides an electronic device, the implementation principle of the electronic device is similar to the implementation principle of the aforementioned piezoelectric device. The specific implementation method of the electronic device can refer to the embodiment of the aforementioned piezoelectric device, and the repeated parts will not be repeated.
[0095] Specifically, an embodiment of the present invention provides an electronic device, such as Fig.11 As shown, it includes the piezoelectric device 1101 as described above. The electronic device may include but is not limited to: a touch panel, a filter, an ultrasonic probe, etc.
[0096] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A piezoelectric device, characterized in that: include: A substrate, a stress adjustment layer, a first electrode layer, a second electrode layer and a piezoelectric layer are stacked; The first electrode layer, the piezoelectric layer and the second electrode layer are sequentially stacked on one side of the substrate; The stress adjustment layer and the piezoelectric layer have the same stress type, and the stress adjustment layer is located on the other side of the substrate.
2. The piezoelectric device according to claim 1, wherein: The material of the stress adjustment layer includes: one of lead zirconate titanate, molybdenum and titanium oxide.
3. A piezoelectric device, characterized in that: include: A substrate, a stress adjustment layer, a first electrode layer, a second electrode layer and a piezoelectric layer are stacked; The first electrode layer, the piezoelectric layer and the second electrode layer are sequentially stacked on one side of the substrate; The stress adjustment layer and the piezoelectric layer have different stress types. The stress adjustment layer is located between the first electrode layer and the substrate or the stress adjustment layer is located on a side of the second electrode layer away from the substrate.
4. The piezoelectric device according to claim 3, wherein: The material of the stress adjustment layer includes silicon nitride.
5. The piezoelectric device according to any one of claims 1 to 4, characterized in that: The piezoelectric layer and the stress adjustment layer satisfy: |σ1|×t1×S1=|σ2|×t2×S2 Among them, σ1 is the stress of the piezoelectric layer, t1 is the thickness of the piezoelectric layer, S1 is the area of the piezoelectric layer, σ1 is the stress of the stress adjustment layer, t1 is the thickness of the stress adjustment layer, and S1 is the area of the stress adjustment layer.
6. The piezoelectric device according to claim 1 or 3, characterized in that: The piezoelectric device is a transparent piezoelectric device, and the material of the stress adjustment layer is a transparent material.
7. The piezoelectric device according to claim 6, wherein: The stress adjustment layer is provided as a whole layer.
8. The piezoelectric device according to claim 6, wherein: The stress adjustment layer and the piezoelectric layer are made of the same material, and their areas are both 50% of the area of the substrate. The orthographic projections of the stress adjustment layer and the piezoelectric layer on the substrate do not overlap each other.
9. The piezoelectric device according to claim 1 or 3, characterized in that: The piezoelectric device is a transparent piezoelectric device, and the material of the stress adjustment layer is a non-transparent material.
10. The piezoelectric device according to claim 9, wherein: An orthographic projection of the stress adjustment layer on the substrate is located at an edge of the substrate.
11. The piezoelectric device according to claim 9, wherein: The stress adjustment layer is a mesh structure, and the transmittance of the mesh structure is greater than or equal to 70%.
12. The piezoelectric device according to claim 11, wherein: The line width of the mesh structure is less than 73 μm.
13. An electronic device, characterized in that: Comprising the piezoelectric device according to any one of claims 1 to 12.