Composite piezoelectric layer and preparation method thereof

Abstract

The invention provides a composite piezoelectric layer and a preparation method thereof, and relates to the technical field of semiconductors. The preparation method of the composite piezoelectric layer comprises the following steps: providing a first substrate, and depositing a first piezoelectric layer with a first preset thickness on the first substrate; dividing the surface of the first piezoelectric layer into a plurality of detection areas; detecting the concentration of the doped elements in each detection area; if the concentration of the doping element is larger than the preset doping concentration, the detection area is thinned, a first compensation layer is deposited on the thinned detection area, and the first compensation layer is used for reducing the overall doping concentration of the composite piezoelectric layer on the detection area; if the concentration of the doping element is smaller than the preset doping concentration, a second compensation layer is deposited on the detection area, and the second compensation layer is used for improving the overall doping concentration of the composite piezoelectric layer on the detection area. By adopting the preparation method of the composite piezoelectric layer, the deviation of electromechanical coupling coefficients in different areas on the same piezoelectric layer can be reduced.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a composite piezoelectric layer and its preparation method. Background Technology

[0002] With the rapid development of wireless communication technology, more and more devices are transmitting and receiving information at higher frequency bands, placing increasingly stringent requirements on radio frequency front-end circuits. Consequently, the market demand for high-performance filters is growing. Bulk acoustic wave filters, with their high quality factor, good out-of-band rejection, and high squareness factor, are gradually becoming the mainstream in the market.

[0003] Bulk acoustic wave (BAW) filters are constructed by cascading multiple resonators in a specific circuit configuration. High-performance filters require high-performance resonators, which possess a high quality factor. This high quality factor allows the filter to exhibit lower insertion loss and a steeper roll-off characteristic, resulting in superior filtering performance. Therefore, fabricating resonators with high stability and superior performance is of paramount importance.

[0004] Piezoelectric thin films are crucial structures affecting resonator performance. Currently, piezoelectric thin films are mainly fabricated by depositing scandium-doped AlN films on substrates using a target sputtering process. However, due to factors such as the target material and the process environment, the scandium content in different regions of the scandium-doped AlN film fluctuates. This fluctuation in scandium content leads to different electromechanical coupling coefficients in different regions of the scandium-doped AlN film, resulting in differences in the electromechanical coupling coefficients of multiple resonators fabricated from the same scandium-doped AlN film. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of the prior art by providing a composite piezoelectric layer and its preparation method, which can reduce the deviation of the electromechanical coupling coefficient in different regions of the same piezoelectric layer.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: One aspect of this application provides a method for preparing a composite piezoelectric layer, comprising: A first substrate is provided, and a first piezoelectric layer of a first predetermined thickness is deposited on the first substrate; Multiple detection areas are divided on the surface of the first piezoelectric layer; The concentration of dopant elements in each detection area is detected; If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned and a first compensation layer is deposited on the thinned detection area. The first compensation layer is used to reduce the overall dopant concentration of the composite piezoelectric layer in the detection area. If the concentration of the dopant element is less than the preset dopant concentration, a second compensation layer is deposited on the detection area. The second compensation layer is used to increase the overall dopant concentration of the composite piezoelectric layer in the detection area.

[0007] Optionally, before providing the first substrate, the method for fabricating the composite piezoelectric layer further includes: The film thickness required for the first piezoelectric layer with a preset doping concentration to reach a preset electromechanical coupling coefficient is obtained and used as the first preset thickness; The film thickness required for the first piezoelectric layer and the first compensation layer to reach the preset electromechanical coupling coefficient with the first type of doping concentration is obtained, and is used as the second preset thickness and the third preset thickness, respectively, wherein the first type of doping concentration is greater than the preset doping concentration; The required film thickness for the first piezoelectric layer and the second compensation layer to reach the preset electromechanical coupling coefficient when the second type of doping concentration is obtained, and the required film thickness of the second compensation layer is taken as the fourth preset thickness, wherein the second type of doping concentration is less than the preset doping concentration; If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area; if the concentration of the dopant element is less than the preset dopant concentration, a second compensation layer is deposited on the detection area, including: If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned to make the film thickness of the detection area become the second preset thickness, and a first compensation layer of the third preset thickness is deposited on the thinned detection area; if the concentration of the dopant element is less than the preset dopant concentration, a second compensation layer of the fourth preset thickness is deposited on the detection area.

[0008] Optionally, if the concentration of the dopant element is greater than a preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, wherein the first compensation layer is used to reduce the overall dopant concentration of the composite piezoelectric layer on the detection area; if the concentration of the dopant element is less than a preset dopant concentration, a second compensation layer is deposited on the detection area, wherein the second compensation layer is used to increase the overall dopant concentration of the composite piezoelectric layer on the detection area. The method for preparing the composite piezoelectric layer further includes: Multiple second substrates are provided, and composite piezoelectric layers are deposited on the multiple second substrates using the same process parameters according to the positions and thicknesses of the first piezoelectric layer, the first compensation layer and the second compensation layer on the first substrate, wherein the second substrates are the same as the first substrate.

[0009] Optionally, the concentration of doped elements in the first compensation layer is 0.

[0010] Optionally, providing a first substrate and depositing a first piezoelectric layer of a first predetermined thickness on the first substrate includes: A first substrate is provided, and a first piezoelectric layer of a first predetermined thickness is deposited on the first substrate using an aluminum nitride target and a scandium target; If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, including: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned and an aluminum nitride target is used to deposit the first compensation layer on the detection area. If the concentration of the dopant element is less than the preset dopant concentration, then depositing a second compensation layer on the detection area includes: If the concentration of the doped element is less than the preset doping concentration, an aluminum nitride target and a scandium target are used to deposit a second compensation layer on the first substrate.

[0011] Optionally, the first compensation layer has an upper surface and a lower surface opposite to each other, the lower surface is attached to the first piezoelectric layer, and the concentration of doped elements in the first compensation layer gradually decreases from the lower surface to the upper surface, with the concentration of doped elements on the upper surface being 0.

[0012] Optionally, providing a first substrate and depositing a first piezoelectric layer of a first predetermined thickness on the first substrate includes: A first substrate is provided, and a first piezoelectric layer of a first predetermined thickness is deposited on the first substrate using an aluminum nitride target and a scandium target; If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, including: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned, and an aluminum nitride target and a scandium target are used to deposit the first compensation layer on the detection area. During the deposition, the amount of scandium sputtered is gradually reduced. If the concentration of the dopant element is less than the preset dopant concentration, then depositing a second compensation layer on the detection area includes: If the concentration of the doped element is less than the preset doping concentration, an aluminum nitride target and a scandium target are used to deposit a second compensation layer on the first substrate.

[0013] Optionally, the detection area includes a central detection area and at least two annular detection areas, the center of the central detection area coincides with the center of the upper surface of the first piezoelectric layer, and the at least two annular detection areas surround the central detection area in sequence.

[0014] Optionally, detecting the concentration of dopant elements in each detection region includes: Multiple detection points are selected in each detection area, and the concentration of doped elements at the multiple detection points is detected. The multiple detection points are evenly distributed in a ring.

[0015] In another aspect of the embodiments of this application, a composite piezoelectric layer is provided, which is prepared by the composite piezoelectric layer preparation method of any of the above claims.

[0016] The beneficial effects of this application include: This application provides a method for preparing a composite piezoelectric layer, comprising: providing a first substrate and depositing a first piezoelectric layer of a first preset thickness on the first substrate; dividing a plurality of detection regions on the surface of the first piezoelectric layer; detecting the concentration of dopant elements in each detection region; if the concentration of dopant elements is greater than a preset dopant concentration, thinning the detection region and depositing a first compensation layer on the thinned detection region, wherein the first compensation layer is used to reduce the overall dopant concentration of the composite piezoelectric layer in the detection region; if the concentration of dopant elements is less than the preset dopant concentration, depositing a second compensation layer on the detection region, wherein the second compensation layer is used to increase the overall dopant concentration of the composite piezoelectric layer in the detection region. In the above method for preparing a composite piezoelectric layer, a first piezoelectric layer is first deposited on the surface of the first substrate, then a plurality of detection regions are divided on the surface of the first piezoelectric layer, and the film thickness of the detection region is adjusted according to the concentration of dopant elements in each detection region. By adopting the above-mentioned method for preparing composite piezoelectric layers, the concentration of doped elements in each detection region is effectively reduced, thereby reducing the difference in electromechanical coupling coefficients between each detection region. This results in higher uniformity of the electromechanical coupling coefficients in each region of the prepared composite piezoelectric layer, and also smaller differences in the electromechanical coupling coefficients of the multiple resonators obtained after cutting. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is one of the flowcharts for a method of preparing a composite piezoelectric layer provided in the embodiments of this application; Figure 2 This is a schematic diagram illustrating the fabrication process of the composite piezoelectric layer provided in the embodiments of this application; Figure 3 A schematic diagram illustrating the division of the detection region in the method for preparing the composite piezoelectric layer provided in this application embodiment; Figure 4A schematic diagram of the structure of the piezoelectric thin film prepared by the method for preparing the composite piezoelectric layer provided in the embodiments of this application; Figure 5 The second flowchart illustrates the method for preparing a composite piezoelectric layer according to an embodiment of this application.

[0019] Icons: 10-First substrate; 11-Substrate; 12-Bottom electrode; 20-First piezoelectric layer; 21-Detection area; 211-Central detection area; 212-Annular detection area; 22-Detection point; 30-First compensation layer; 40-Second compensation layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. It should be noted that, unless otherwise specified, the various features in the embodiments of this application can be combined with each other, and the combined embodiments are still within the protection scope of this application.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] Regarding one aspect of the embodiments of this application, please refer to Figure 1 A method for preparing a composite piezoelectric layer is provided, comprising: S100: Provide a first substrate and deposit a first piezoelectric layer of a first preset thickness on the first substrate.

[0026] Please refer to the reference. Figure 2 The process employs a target sputtering technique, utilizing high-energy particles (such as argon ions) to bombard the surface of a target in a vacuum environment, causing atoms or molecules to escape and deposit as a film on the surface of a first substrate 10. By controlling the sputtering time, a first piezoelectric layer 20 with a first preset thickness is obtained. The first piezoelectric layer 20 is a part of the composite piezoelectric layer to be prepared.

[0027] The first piezoelectric layer 20 is a thin film containing doped elements, typically a scandium-doped aluminum nitride thin film. Theoretically, the doping concentration of the doped elements in each region of the first piezoelectric layer 20 is a preset doping concentration. However, due to the influence of the target material and process environment, the actual doping concentration in different regions of the first piezoelectric layer 20 varies. That is to say, the doping concentration in each region of the first piezoelectric layer 20 can be equal to, less than, or greater than the preset doping concentration.

[0028] When the composite piezoelectric layer to be prepared is used to prepare the piezoelectric layer of a resonator, optionally, the first substrate 10 includes a substrate 11 and a bottom electrode 12 disposed on the substrate 11, and the first piezoelectric layer 20 is deposited on the bottom electrode 12 and the surface of the substrate 11 exposed by the bottom electrode 12. The first piezoelectric layer 20 is a part of the composite piezoelectric layer to be prepared. After the composite piezoelectric layer is prepared, a top electrode can be deposited on the surface of the composite piezoelectric layer, and then it can be cut to obtain multiple resonators.

[0029] S200: Multiple detection areas are divided on the surface of the first piezoelectric layer.

[0030] Please refer to the reference. Figure 3To obtain the doping concentration in different regions of the first piezoelectric layer 20, multiple detection regions 21 are divided on the surface of the first piezoelectric layer 20, so that the doping concentration in each detection region 21 can be detected separately. Preferably, the detection regions 21 are divided based on previously measured fluctuation data of the doping concentration on the first piezoelectric layer 20, so as to make the detection results more accurate.

[0031] Generally, the doping concentration of a certain region on the first piezoelectric layer 20 is related to the distance between that region and the center of the first piezoelectric layer 20. Therefore, dividing the detection region 21 with distance as a reference can make the measurement results more accurate. For example, the detection region 21 includes a central detection region 211 and at least two annular detection regions 212. The center of the central detection region 211 coincides with the center of the upper surface of the first piezoelectric layer 20, and the at least two annular detection regions 212 surround the central detection region 211 in sequence. Among them, the central detection region 211 is the region closest to the center of the first piezoelectric layer 20, and the distance between the at least two annular detection regions 212 and the center of the first piezoelectric layer 20 increases sequentially.

[0032] The shape of the central detection area 211 is preferably the same as the shape of the cross-section of the first piezoelectric layer 20, and the shapes of the inner and outer edges of the annular detection area 212 are preferably the same as the shape of the outer edge of the central detection area 211. Multiple detection areas 21 are connected in sequence. For example, if the cross-section of the first substrate 10 is circular, then the cross-section of the first piezoelectric layer 20 is also circular, and correspondingly, the central detection area 211 is circular, and the annular detection area 212 is annular; if the cross-section of the first substrate 10 is square, then the cross-section of the first piezoelectric layer 20 is also square, and correspondingly, the central detection area 211 is square, and the inner and outer edges of the annular detection area 212 are both square.

[0033] Optionally, there is one central detection area 211 and two annular detection areas 212, with the two annular detection areas 212 having the same width, and the width of the central detection area 211 being twice the width of the annular detection areas 212. This configuration avoids making the detection process overly complex while still achieving relatively accurate detection results.

[0034] It can be understood that if the central detection area 211 is circular and the annular detection area 212 is annular, then the width of the central detection area 211 is the diameter of the central detection area 211, and the width of the annular detection area 212 is the difference between the radii of the outer edge and the inner edge; if the central detection area 211 is square and both the inner and outer edges of the annular detection area 212 are square, then the width of the central detection area 211 is the side length of the square, and the width of the annular detection area 212 is the difference between the side length of the outer edge and the side length of the inner edge.

[0035] S300: Detects the concentration of doped elements in each detection area.

[0036] The concentration of doped elements in each detection region 21 is detected separately to obtain the detection results of the doped element concentration in each detection region 21. It can be understood that the detection results may have three situations: the concentration of doped elements is equal to the preset doping concentration, the concentration of doped elements is less than the preset doping concentration, and the concentration of doped elements is greater than the preset doping concentration.

[0037] To further improve the accuracy of the detection results, multiple detection points 22 can be selected within each detection area 21, and the concentration of doped elements at these multiple detection points 22 can be detected. If the multiple detection results are similar, the average concentration of the multiple doped elements can be taken as the overall concentration of doped elements in the detection area 21. If the multiple detection results are significantly different, it should be considered whether the division of the detection area 21 is inaccurate, and the detection area 21 can be re-divided.

[0038] It is understandable that when judging whether the differences between multiple test results are large, a judgment value can be set. If the difference between two test results is greater than the judgment value, it is considered that the results are large; if the difference between two test results is less than or equal to the judgment value, it is considered that the results are small.

[0039] If the detection area 21 includes a central detection area 211 and at least two annular detection areas 212, the center of the central detection area 211 coincides with the center of the upper surface of the first piezoelectric layer 20, and the at least two annular detection areas 212 surround the central detection area 211 in sequence, then the multiple detection points 22 in the same detection area 21 can be selected to be evenly distributed in an annular shape to make the detection results more accurate.

[0040] S400: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned and a first compensation layer is deposited on the thinned detection area. The first compensation layer is used to reduce the overall doping concentration of the composite piezoelectric layer in the detection area. If the concentration of the doping element is less than the preset doping concentration, a second compensation layer is deposited on the detection area. The second compensation layer is used to increase the overall doping concentration of the composite piezoelectric layer in the detection area.

[0041] The electromechanical coupling coefficient of a certain detection region 21 is mainly affected by the film thickness of the detection region 21 and the concentration of doping elements in the detection region 21. Therefore, when the concentration of doping elements is fixed, the electromechanical coupling coefficient can be adjusted by changing the film thickness of the detection region 21, thereby reducing the difference in the electromechanical coupling coefficient of each detection region 21.

[0042] Specifically, please refer to the following: Figure 4 , Figure 4 The detection area 21 on the left shows the case where the concentration of the dopant element is greater than the preset doping concentration; the detection area 21 in the middle shows the case where the concentration of the dopant element is equal to the preset doping concentration; and the detection area 21 on the right shows the case where the concentration of the dopant element is less than the preset doping concentration. It is understandable that... Figure 4 The division of detection areas 21 in the diagram is for illustrative purposes only; in practice, the division of detection areas 21 can be similar to... Figure 4 Depending on the division method, the first piezoelectric layer 20 may also have three types of detection regions 21 at the same time.

[0043] If the concentration of doped elements in a certain detection region 21 is equal to the preset doping concentration, then no processing is required for that detection region 21. The electromechanical coupling coefficient of that detection region 21 can be used as an adjustment standard for the electromechanical coupling coefficients of other detection regions 21.

[0044] If the concentration of doped elements in a certain detection area 21 is greater than the preset doping concentration, the detection area 21 needs to be thinned to reduce the film thickness of the detection area 21. Then, a first compensation layer 30 is deposited on the surface of the thinned detection area 21. The first compensation layer 30 is used to reduce the overall doping concentration of the composite piezoelectric layer in the detection area 21.

[0045] It is understood that the composite piezoelectric layer in the detection region 21 includes a first piezoelectric layer 20 and a first compensation layer 30. The overall doping concentration of the composite piezoelectric layer in the detection region 21 refers to the overall doping concentration of the portion of the first piezoelectric layer 20 corresponding to the detection region 21 and the first compensation layer 30 on that portion as a whole.

[0046] The first compensation layer 30 can be selected as having no doped elements or a doping concentration lower than that of the detection region 21. The thinning process, in conjunction with the first compensation layer 30, adjusts the electromechanical coupling coefficient of the detection region 21 to be equal to or approximately equal to that of the detection region 21 with a doped element concentration equal to a preset doping concentration.

[0047] If the concentration of doped elements in a certain detection region 21 is less than the preset doping concentration, a second compensation layer 40 needs to be deposited on the detection region 21 to increase the film thickness of the detection region 21. The second compensation layer 40 is used to increase the overall doping concentration of the composite piezoelectric layer on the detection region 21.

[0048] It is understood that the composite piezoelectric layer in the detection region 21 includes a first piezoelectric layer 20 and a second compensation layer 40. The overall doping concentration of the composite piezoelectric layer in the detection region 21 refers to the overall doping concentration of the portion of the first piezoelectric layer 20 corresponding to the detection region 21 and the second compensation layer 40 on that portion as a whole.

[0049] The second compensation layer 40 contains doped elements, and the concentration of the doped elements can be selected as a preset doping concentration or close to a preset doping concentration. The thickening process adjusts the electromechanical coupling coefficient of the detection region 21 to be equal to or approximately equal to the electromechanical coupling coefficient of the detection region 21 where the concentration of the doped elements is equal to the preset doping concentration.

[0050] It should be noted that the first preset thickness, the film thickness of the thinned detection area 21, the thickness of the deposited first compensation layer 30, and the thickness of the second compensation layer 40 can all be determined based on experience, software simulation, and other methods.

[0051] The above-described method for fabricating the composite piezoelectric layer involves first depositing a first piezoelectric layer 20 on the surface of a first substrate 10, then dividing the surface of the first piezoelectric layer 20 into multiple detection regions 21, and finally adjusting the film thickness of each detection region 21 according to the concentration of doped elements within that region. This method effectively reduces the concentration of doped elements in each detection region, thereby reducing the difference in electromechanical coupling coefficients between the regions. This results in higher uniformity of the electromechanical coupling coefficients in each region of the fabricated composite piezoelectric layer, and also reduces the difference in electromechanical coupling coefficients among the multiple resonators obtained after dicing.

[0052] Optionally, the concentration of doped elements in the first compensation layer 30 is 0, that is, the first compensation layer 30 does not contain doped elements.

[0053] Furthermore, the first piezoelectric layer 20 is made of scandium-doped aluminum nitride, and the first compensation layer 30 is made of aluminum nitride.

[0054] Optionally, providing a first substrate and depositing a first piezoelectric layer of a first predetermined thickness on the first substrate includes: S110: Provide a first substrate, and deposit a first piezoelectric layer of a first predetermined thickness on the first substrate using an aluminum nitride target and a scandium target.

[0055] If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, including: S410: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned and a first compensation layer is deposited on the detection area using an aluminum nitride target.

[0056] If the concentration of the dopant element is less than the preset dopant concentration, then depositing a second compensation layer on the detection area includes: S420: If the concentration of the doped element is less than the preset doping concentration, an aluminum nitride target and a scandium target are used to deposit a second compensation layer on the first substrate.

[0057] A target sputtering process is employed, in which high-energy particles (such as argon ions) bombard the surfaces of aluminum nitride and scandium targets in a vacuum environment, causing atoms or molecules to escape and deposit into a scandium-doped aluminum nitride thin film, i.e., the first piezoelectric layer 20, on the surface of the first substrate 10. Then, the concentration of doped elements in each detection region 21 of the first piezoelectric layer 20 is detected.

[0058] If the doping concentration of a certain detection area 21 is greater than the preset doping concentration, the detection area 21 is thinned, and then an aluminum nitride thin film (undoped) is sputtered on the detection area 21 using an aluminum nitride target alone as the first compensation layer 30.

[0059] If the doping concentration of a certain detection area 21 is less than the preset doping concentration, then the same method as the preparation of the first piezoelectric layer 20 is used, and both aluminum nitride target and scandium target are used to sputter a scandium-doped aluminum nitride thin film as the second compensation layer 40 on the detection area 21.

[0060] In another embodiment, the first compensation layer 30 has an upper surface and a lower surface opposite to each other, the lower surface is attached to the first piezoelectric layer 20, and the concentration of doped elements in the first compensation layer 30 gradually decreases from the lower surface to the upper surface, with the concentration of doped elements on the upper surface being 0.

[0061] In other words, the material of the first compensation layer 30 is scandium-doped aluminum nitride. Along the direction perpendicular to the first piezoelectric layer 20 and gradually away from the first piezoelectric layer 20, the scandium doping concentration of the first compensation layer 30 gradually decreases until it becomes 0.

[0062] Optionally, providing a first substrate and depositing a first piezoelectric layer of a first predetermined thickness on the first substrate includes: S120: Provide a first substrate and deposit a first piezoelectric layer of a first predetermined thickness on the first substrate using an aluminum nitride target and a scandium target.

[0063] If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, including: S430: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned, and an aluminum nitride target and a scandium target are used to deposit the first compensation layer on the detection area. During the deposition, the amount of scandium sputtered is gradually reduced.

[0064] If the concentration of the dopant element is less than the preset dopant concentration, then depositing a second compensation layer on the detection area includes: S440: If the concentration of the doped element is less than the preset doping concentration, an aluminum nitride target and a scandium target are used to deposit a second compensation layer on the first substrate.

[0065] Similarly, using a target sputtering process, high-energy particles (such as argon ions) bombard the surfaces of aluminum nitride and scandium targets in a vacuum environment, causing atoms or molecules to escape and deposit on the surface of the first substrate 10 to form a scandium-doped aluminum nitride thin film, i.e., the first piezoelectric layer 20. Then, the concentration of doped elements in each detection region 21 of the first piezoelectric layer 20 is detected.

[0066] If the doping concentration of a certain detection area 21 is greater than the preset doping concentration, the detection area 21 is thinned. Then, aluminum nitride and scandium targets are used simultaneously to sputter an aluminum nitride film on the detection area 21 as the first compensation layer 30. During sputtering, the use of scandium target is gradually reduced, thereby gradually reducing the scandium content in the scandium-doped aluminum nitride film.

[0067] If the doping concentration of a certain detection area 21 is less than the preset doping concentration, then the same method as the preparation of the first piezoelectric layer 20 is used, and both aluminum nitride target and scandium target are used to sputter a scandium-doped aluminum nitride thin film as the second compensation layer 40 on the detection area 21.

[0068] Alternatively, please refer to Figure 5 Before providing the first substrate, the method for preparing the composite piezoelectric layer also includes: S500: Obtain the film thickness required for the first piezoelectric layer with a preset doping concentration to reach a preset electromechanical coupling coefficient, and use it as the first preset thickness.

[0069] Please refer to the reference. Figure 4 As mentioned earlier, the electromechanical coupling coefficient of the first piezoelectric layer 20 is mainly affected by the film thickness and the concentration of doping elements. Therefore, there should be a corresponding relationship between the concentration of doping elements, the film thickness, and the electromechanical coupling coefficient of the first piezoelectric layer 20; once any two of them are determined, the third should also be able to be determined. Based on this principle, after determining the preset doping concentration and the preset electromechanical coupling coefficient of the first piezoelectric layer 20, the film thickness of the first piezoelectric layer 20 can be determined, and this film thickness is taken as the first preset thickness. When preparing the composite piezoelectric layer, the first piezoelectric layer 20 of the first preset thickness is first deposited on the first substrate 10, and then each detection area 21 is adjusted based on this.

[0070] The relationship between the concentration of doped elements, film thickness, and electromechanical coupling coefficient of the first piezoelectric layer 20 can be determined based on experience and software simulation. It can be understood that once the preset doping concentration and preset electromechanical coupling coefficient of the first piezoelectric layer 20 are determined, the film thickness of the first piezoelectric layer 20 can be within a range, and a value within this range can be selected as the first preset thickness.

[0071] S600: Obtain the film thickness required for the first piezoelectric layer and the first compensation layer with the first type of doping concentration to reach the preset electromechanical coupling coefficient, and use them as the second preset thickness and the third preset thickness, respectively, wherein the first type of doping concentration is greater than the preset doping concentration.

[0072] When the concentration of doped elements is greater than the preset doping concentration, thinning treatment is required in subsequent preparation before depositing the first compensation layer 30. Therefore, given that the doping concentration and the preset electromechanical coupling coefficient are determined, the film thickness of the thinned first piezoelectric layer 20 in the detection area 21 (i.e., the second preset thickness) and the thickness of the first compensation layer 30 (i.e., the third preset thickness) need to be determined respectively for subsequent preparation of the composite piezoelectric layer.

[0073] It is understandable that when the concentration of the dopant element is greater than the preset dopant concentration, the concentration of each dopant element corresponds to a second preset thickness value or range and a third preset thickness value or range. During subsequent fabrication, the corresponding second and third preset thicknesses can be selected based on the actually measured dopant element concentration. The values ​​or ranges of the second and third preset thicknesses can be determined based on experience and software simulation.

[0074] S700: Obtain the film thickness required for the first piezoelectric layer and the second compensation layer with the second type of doping concentration to reach the preset electromechanical coupling coefficient, and take the film thickness required for the second compensation layer as the fourth preset thickness, wherein the second type of doping concentration is less than the preset doping concentration.

[0075] When the concentration of doped elements is less than the preset doping concentration, thickening treatment is required in subsequent preparation. Therefore, given the doping concentration and the preset electromechanical coupling coefficient, it is necessary to determine the film thickness of the second compensation layer 40 (i.e. the fourth preset thickness) for subsequent preparation of the composite piezoelectric layer.

[0076] It is understandable that when the concentration of the dopant element is less than the preset dopant concentration, the concentration of each dopant element corresponds to a fourth preset thickness value or range. During subsequent fabrication, the corresponding fourth preset thickness can be selected based on the actually measured concentration of the dopant element. The value or range of the fourth preset thickness can be determined based on experience or software simulation.

[0077] It should be noted that, in this embodiment, the execution order of steps S500 to S700 is not limited. The three steps can be executed simultaneously or sequentially. When executed sequentially, they can be executed in the order of S500, S600, and S700, or in any other order.

[0078] Accordingly, if the concentration of the dopant element is greater than the preset doping concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area; if the concentration of the dopant element is less than the preset doping concentration, a second compensation layer is deposited on the detection area, including: S450: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned to make the film thickness of the detection area become the second preset thickness, and a first compensation layer of the third preset thickness is deposited on the thinned detection area; if the concentration of the doping element is less than the preset doping concentration, a second compensation layer of the fourth preset thickness is deposited on the detection area.

[0079] After obtaining the correspondence between the dopant element concentration, the film thickness of the first piezoelectric layer 20, the first compensation layer 30, and the second compensation layer 40, the detection areas 21 of the first piezoelectric layer 20 are adjusted according to the corresponding data, thereby reducing the deviation of the electromechanical coupling coefficient in different areas on the same composite piezoelectric layer.

[0080] Generally speaking, although the concentration of doped elements in each region of the first piezoelectric layer 20 may fluctuate, the numerical differences will not be particularly large. Therefore, when obtaining data on the second, third, or fourth preset thickness corresponding to different doped element concentrations, the concentration of a doped element can be determined at intervals of a small value. For example, if the preset doping concentration is set to 20%, the concentration of a doped element can be determined at intervals of 0.1%, and the corresponding second, third, or fourth preset thickness can be obtained.

[0081] For example, as shown in the table below, the table provides data for different dopant concentrations.

[0082]

[0083] In the table, the gray background indicates the film thickness that can be selected at the corresponding scandium doping concentration, and the bolded numbers indicate the thickness of the first compensation layer 30 corresponding to the corresponding scandium doping concentration. The table shows that the thickness of the first piezoelectric layer 20 corresponding to a 20% scandium doping concentration can be 590nm or 592nm. Therefore, when the preset doping concentration is 20%, the first preset thickness can be 590nm or 592nm. If the scandium doping concentration of a certain detection area 21 is 21%, the film thickness of the detection area 21 needs to be reduced to 572nm or 574nm, and then a first compensation layer 30 with a thickness of 19nm is deposited on the surface of the thinned detection area 21. If the scandium doping concentration of a certain detection area 21 is 19.9%, a second compensation layer 40 with a thickness of 2nm or 4nm needs to be deposited on the surface of the detection area 21 to increase the overall film thickness to 592nm or 594nm.

[0084] Optionally, if the concentration of the dopant element is greater than a preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, wherein the first compensation layer is used to reduce the overall dopant concentration of the composite piezoelectric layer on the detection area; if the concentration of the dopant element is less than a preset dopant concentration, a second compensation layer is deposited on the detection area, wherein the second compensation layer is used to increase the overall dopant concentration of the composite piezoelectric layer on the detection area. The method for preparing the composite piezoelectric layer further includes: S800: Provides multiple second substrates, and deposits composite piezoelectric layers on the multiple second substrates using the same process parameters according to the positions and thicknesses of the first piezoelectric layer, the first compensation layer and the second compensation layer on the first substrate, wherein the second substrates are the same as the first substrates.

[0085] Using the first substrate 10 as a test piece, the thicknesses of the first piezoelectric layer 20, the first compensation layer 30, and the second compensation layer 40 in different regions are obtained through a series of tests. Then, with other process parameters unchanged, each film is replicated onto the second substrate, thus realizing the mass production of piezoelectric films.

[0086] This embodiment also provides a composite piezoelectric layer, which is prepared using any of the above methods for preparing composite piezoelectric layers.

[0087] This composite piezoelectric layer has the same structure and beneficial effects as the composite piezoelectric layer prepared by the method described in the foregoing embodiments. The structure and beneficial effects of the method for preparing the composite piezoelectric layer have been described in detail in the foregoing embodiments and will not be repeated here.

[0088] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a composite piezoelectric layer, characterized in that, include: A first substrate is provided, and a first piezoelectric layer of a first predetermined thickness is deposited on the first substrate; Multiple detection areas are divided on the surface of the first piezoelectric layer; The concentration of dopant elements in each of the detection regions is detected; If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, wherein the first compensation layer is used to reduce the overall doping concentration of the composite piezoelectric layer on the detection area; if the concentration of the doping element is less than the preset doping concentration, a second compensation layer is deposited on the detection area, wherein the second compensation layer is used to increase the overall doping concentration of the composite piezoelectric layer on the detection area.

2. The method for preparing the composite piezoelectric layer as described in claim 1, characterized in that, Before providing the first substrate, the method for preparing the composite piezoelectric layer further includes: The film thickness required for the first piezoelectric layer with a preset doping concentration to reach a preset electromechanical coupling coefficient is obtained and used as the first preset thickness; The film thickness required for the first piezoelectric layer and the first compensation layer with the first type of doping concentration to reach the preset electromechanical coupling coefficient is obtained, and is respectively used as the second preset thickness and the third preset thickness, wherein the first type of doping concentration is greater than the preset doping concentration; The required film thickness for the first piezoelectric layer and the second compensation layer with the second type of doping concentration to reach the preset electromechanical coupling coefficient is obtained, and the required film thickness of the second compensation layer is taken as the fourth preset thickness, wherein the second type of doping concentration is less than the preset doping concentration; If the concentration of the dopant element is greater than the preset dopant concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area; if the concentration of the dopant element is less than the preset dopant concentration, a second compensation layer is deposited on the detection area, including: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned to make the film thickness of the detection area become the second preset thickness, and a first compensation layer of the third preset thickness is deposited on the thinned detection area; if the concentration of the doping element is less than the preset doping concentration, a second compensation layer of the fourth preset thickness is deposited on the detection area.

3. The method for preparing the composite piezoelectric layer as described in claim 1, characterized in that, If the concentration of the doping element is greater than a preset doping concentration, the detection area is thinned, and a first compensation layer is deposited on the thinned detection area, wherein the first compensation layer is used to reduce the overall doping concentration of the composite piezoelectric layer on the detection area; if the concentration of the doping element is less than the preset doping concentration, a second compensation layer is deposited on the detection area, wherein the second compensation layer is used to increase the overall doping concentration of the composite piezoelectric layer on the detection area. The method for preparing the composite piezoelectric layer further includes: A plurality of second substrates are provided, and composite piezoelectric layers are deposited on the plurality of second substrates using the same process parameters according to the positions and thicknesses of the first piezoelectric layer, the first compensation layer and the second compensation layer on the first substrate, wherein the second substrates are the same as the first substrate.

4. The method for preparing the composite piezoelectric layer as described in claim 1, characterized in that, The concentration of doped elements in the first compensation layer is 0.

5. The method for preparing the composite piezoelectric layer as described in claim 4, characterized in that, The provision of a first substrate and the deposition of a first piezoelectric layer of a first predetermined thickness on the first substrate include: A first substrate is provided, and a first piezoelectric layer of a first predetermined thickness is deposited on the first substrate using an aluminum nitride target and a scandium target; The step of thinning the detection area if the concentration of the doping element is greater than a preset doping concentration, and depositing a first compensation layer on the thinned detection area, includes: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned, and the aluminum nitride target is used to deposit a first compensation layer on the detection area. The step of depositing a second compensation layer on the detection area if the concentration of the dopant element is less than the preset dopant concentration includes: If the concentration of the doping element is less than the preset doping concentration, a second compensation layer is deposited on the first substrate using the aluminum nitride target and the scandium target.

6. The method for preparing the composite piezoelectric layer as described in claim 1, characterized in that, The first compensation layer has an upper surface and a lower surface opposite to each other. The lower surface is attached to the first piezoelectric layer. The concentration of doped elements in the first compensation layer gradually decreases from the lower surface to the upper surface, and the concentration of doped elements on the upper surface is 0.

7. The method for preparing the composite piezoelectric layer as described in claim 6, characterized in that, The provision of a first substrate and the deposition of a first piezoelectric layer of a first predetermined thickness on the first substrate include: A first substrate is provided, and a first piezoelectric layer of a first predetermined thickness is deposited on the first substrate using an aluminum nitride target and a scandium target; The step of thinning the detection area if the concentration of the doping element is greater than a preset doping concentration, and depositing a first compensation layer on the thinned detection area, includes: If the concentration of the doping element is greater than the preset doping concentration, the detection area is thinned, and the aluminum nitride target and the scandium target are used to deposit a first compensation layer on the detection area, and the amount of scandium sputtering is gradually reduced during the deposition. The step of depositing a second compensation layer on the detection area if the concentration of the dopant element is less than the preset dopant concentration includes: If the concentration of the doping element is less than the preset doping concentration, a second compensation layer is deposited on the first substrate using the aluminum nitride target and the scandium target.

8. The method for preparing the composite piezoelectric layer as described in claim 1, characterized in that, The detection area includes a central detection area and at least two annular detection areas. The center of the central detection area coincides with the center of the upper surface of the first piezoelectric layer, and the at least two annular detection areas surround the central detection area in sequence.

9. The method for preparing the composite piezoelectric layer as described in claim 8, characterized in that, The detection of the concentration of dopant elements in each of the detection regions includes: Multiple detection points are selected within each detection area, and the concentration of doped elements at the multiple detection points is detected, wherein the multiple detection points are uniformly distributed in a ring.

10. A composite piezoelectric layer, characterized in that, It is prepared by the method for preparing the composite piezoelectric layer as described in any one of claims 1 to 9.

Images