Piezoelectric micro-electro-mechanical device and preparation method thereof
The method addresses the issue of polymer residues and electrode damage in piezoelectric device preparation by using a non-reactive metal electrode layer and controlled etching processes, ensuring structural integrity and improved device performance.
Patent Information
- Application Number
- CN202411344145.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-31
AI Technical Summary
Existing methods for preparing piezoelectric micro-electromechanical devices result in metal ion-containing polymer residues and damage to the film and electrode layers due to the use of alkaline solutions, leading to structural defects and impaired device performance.
A method involving the use of a metal electrode layer that is non-reactive with alkaline solutions, followed by dry etching to form a groove in the piezoelectric material layer, and subsequent wet cleaning with alkaline solutions to remove polymer residues while preserving the metal electrode layer integrity.
Ensures the structural integrity of the device by removing polymer residues and avoiding electrode damage, simplifying the process and reducing costs through simultaneous degumming, cleaning, and etching steps.
Smart Images
Figure CN119218937A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a piezoelectric micro-electromechanical device and a method for preparing the same. Background Art
[0002] Piezoelectric MEMS (Micro-Electro-Mechanical System) is a field that has developed rapidly in recent years. Piezoelectric thin film materials have the characteristics of mutual conversion between electrical signals and mechanical vibrations, which provides new possibilities for the development of MEMS devices. Piezoelectric MEMS devices have the advantages of small size, light weight, low power consumption, and fast response. With the continuous advancement of micro-machining technology, people have begun to apply piezoelectric thin film materials to the manufacture of MEMS devices, thus giving rise to the rise of piezoelectric MEMS technology, making piezoelectric MEMS widely used in consumer electronics, automotive electronics, industrial control, medical equipment and other fields.
[0003] After dry etching of existing piezoelectric thin film materials (such as aluminum nitride AlN, aluminum scandium nitride AlScN), there are serious metal ion-containing polymer residues on their surface, such as Figure 1a The figure shows the morphology of the polymer remaining on the surface of the structure after dry etching and degumming. When the wet cleaning process is used, the solution used cannot react with the piezoelectric film material and the metal electrode, resulting in the selectable solution type not being able to remove the polymer that has been coupled to the film layer, which results in the structure obtained after the process often showing the following Figure 1a The morphology shown is the situation where the photoresist mask has been removed but the polymer still remains on the surface.
[0004] Although alkaline solutions with strong polymer removal ability can effectively dissolve and remove polymers, they are also widely used in the wet cleaning process of wafer manufacturing. However, since piezoelectric thin film materials react with alkaline solutions, direct cleaning with alkaline solutions will cause damage to the film layer 2, especially serious undercutting at the bottom 4 of the film layer 2. In addition, alkaline solutions will also react with most metal electrode 1 materials to cause electrode damage, forming Figure 1b The film layer 2 on both sides of the bottom of the groove 3 is missing (i.e., the side recess at the bottom 4) and the metal electrode 1 is damaged ( Figure 1b The surface of the metal electrode 1 is not flat. This will have a serious impact on the filling effect of the deposition process, the piezoelectric performance of the device and the electrical connection, and thus lead to abnormal device performance.
[0005] It can be seen that the currently used preparation methods will cause defects in the device, making it impossible to effectively guarantee the quality of the device. Summary of the invention
[0006] The purpose of the embodiments of the present application is to provide a piezoelectric micro-electromechanical device and a method for preparing the same, which can ensure the integrity of the device morphology, improve the performance of the device, and have a low preparation cost.
[0007] In one aspect of an embodiment of the present application, a piezoelectric micro-electromechanical device is provided, comprising providing a base layer, on which at least a metal electrode layer, a piezoelectric material layer and a mask layer are sequentially formed, wherein the mask layer partially covers the piezoelectric material layer; wherein the metal electrode layer is made of a metal material that is substantially non-reactive with an alkaline solution;
[0008] Dry etching the area outside the mask layer on the piezoelectric material layer to form a groove in the piezoelectric material layer, and retaining a reserved layer on the inner wall of the groove;
[0009] The groove is cleaned by wet method with alkaline solution to remove the polymer generated and remaining by etching, the reserved layer and the mask layer, so that the piezoelectric material layer forms a target morphology and exposes the metal electrode layer.
[0010] Optionally, providing a base layer, and sequentially forming at least a metal electrode layer, a piezoelectric material layer and a mask layer on the base layer, wherein the mask layer partially covers the piezoelectric material layer; wherein the metal electrode layer is made of a metal material that is substantially non-reactive with an alkaline solution, comprises:
[0011] Depositing the metal electrode layer with a thickness of 10nm to 1um on the base layer, wherein the material of the metal electrode layer includes at least molybdenum and ruthenium;
[0012] Depositing the piezoelectric material layer with a thickness between 0.1um and 2um on the metal electrode layer;
[0013] The mask layer is prepared along two sides of the piezoelectric material layer so that the mask layer covers two side regions of the piezoelectric material layer.
[0014] Optionally, the dry etching of the area outside the mask layer on the piezoelectric material layer to form a groove in the piezoelectric material layer and retaining a reserved layer on the inner wall of the groove includes:
[0015] Etching the area outside the mask layer on the piezoelectric material layer in the direction of the metal electrode layer to form the groove, and retaining 1% to 10% of the thickness of the piezoelectric material layer on the inner wall of the groove as the reserved layer;
[0016] The reserved layer is formed with a chamfered corner at a bottom sidewall of the trench close to the metal electrode layer to transition to the bottom of the reserved layer.
[0017] Optionally, the dry etching of the area outside the mask layer on the piezoelectric material layer to form a groove in the piezoelectric material layer and retaining a reserved layer on the inner wall of the groove includes:
[0018] The wall thickness of the groove gradually increases from the top far away from the metal electrode layer to the bottom close to the metal electrode layer, so that the groove forms an inverted trapezoidal groove.
[0019] Optionally, the step of wet cleaning the groove with an alkaline solution to remove the residual polymer generated by etching, the reserved layer and the mask layer, so that the piezoelectric material layer forms a target morphology and exposes the metal electrode layer, comprises:
[0020] Using the alkaline solution to remove the polymer, the reserved layer and the mask layer;
[0021] Cleaning the groove by alcohol or ketone solution;
[0022] Cleaning the groove with deionized water;
[0023] The grooves are dried.
[0024] Optionally, the step of wet cleaning the groove with an alkaline solution to remove the residual polymer generated by etching, the reserved layer and the mask layer, so that the piezoelectric material layer forms a target morphology and exposes the metal electrode layer, comprises:
[0025] At a temperature of 30° C. to 90° C., using an alkaline solution to react with the polymer, the reserved layer, and the mask layer for 3 minutes to 30 minutes;
[0026] At a temperature of 10° C. to 40° C., the groove is cleaned with an alcohol or ketone solution for 1 minute to 30 minutes;
[0027] At a temperature of 10° C. to 40° C., the groove is cleaned with deionized water for 1 minute to 30 minutes;
[0028] The groove is dried at a temperature of 20° C. to 80° C. for 1 minute to 45 minutes.
[0029] On the other hand, an embodiment of the present application provides a piezoelectric micro-electromechanical device, which is prepared according to the above-mentioned method for preparing a piezoelectric micro-electromechanical device, and includes a base layer, a metal electrode layer and a piezoelectric material layer stacked in sequence, wherein the piezoelectric material layer is formed with a groove, and the groove extends to the metal electrode layer and exposes the metal electrode layer.
[0030] Optionally, the wall thickness of the groove gradually increases from the top far away from the metal electrode layer to the bottom close to the metal electrode layer, and the groove forms an inverted trapezoidal groove.
[0031] Optionally, the material of the metal electrode layer includes at least molybdenum and ruthenium.
[0032] Optionally, the thickness of the metal electrode layer is between 10 nm and 1 um, and the thickness of the piezoelectric material layer is between 0.1 um and 2 um.
[0033] The piezoelectric micro-electromechanical device and its preparation method provided in the embodiment of the present application effectively remove the polymer residue on the surface of the structure; and retain a part of the piezoelectric material layer as a reserved layer through the dry etching process. During the wet cleaning process, the reserved layer is removed while ensuring that the underlying metal electrode layer is completely exposed, and at the same time, the side digging and notch at the bottom of the groove are avoided, ensuring the morphology of the structure after the process treatment process: the material selection of the metal electrode layer determines the selection of the alkaline solution, and the corrosion-resistant metal is selected as the material of the metal electrode layer, so that the metal electrode layer and the alkaline solution are not easy to react, ensuring that the metal electrode layer will not be damaged, ensuring the complete morphology of the device after the process treatment process, and improving the performance of the device. The polymer and the etched material are removed simultaneously by using an alkaline solution, and the effects of degumming, cleaning and etching are achieved simultaneously through a wet cleaning step, which can effectively simplify the process steps and reduce the process cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0035] Figure 1a It is an example of the polymer morphology remaining on the surface of the structure after existing dry etching and stripping;
[0036] Figure 1b It is a schematic diagram of the cross-section of the morphology after direct cleaning with an existing alkaline solution;
[0037] Figure 2 is a schematic diagram of the structure of a piezoelectric micro-electromechanical device provided in this embodiment;
[0038] Figure 3 This is a schematic diagram of the cross-sectional morphology of the piezoelectric micro-electromechanical device provided in this embodiment before dry etching;
[0039] Figure 4 This is a schematic cross-sectional view of the morphology structure of the piezoelectric micro-electromechanical device provided in this embodiment after etching without exposing the bottom metal electrode layer;
[0040] Figure 5is a schematic cross-sectional view of the morphology structure of a piezoelectric micro-electromechanical device provided in this embodiment, in which a bottom metal electrode layer is partially exposed;
[0041] Figure 6 It is a schematic diagram of the structure and morphology of the piezoelectric micro-electromechanical device provided in this embodiment.
[0042] Icon: 1-metal electrode; 2-film layer; 3-groove; 4-bottom; 10-base layer; 11-metal electrode layer; 12-piezoelectric material layer; 12a-reserved layer; 12b-chamfer; 13-mask layer; 14-polymer; 15, 151, 152-groove; D-stacking direction; d1, d2-thickness; d3-wall thickness; d4-section width. DETAILED DESCRIPTION
[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.
[0044] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.
[0045] It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0046] The present invention provides a method for preparing a piezoelectric micro-electromechanical device. Figure 2 The piezoelectric micro-electromechanical device shown, the method comprising:
[0047] Reference Figure 3 Step 200: Provide a base layer 10, and sequentially form at least a metal electrode layer 11, a piezoelectric material layer 12 and a mask layer 13 on the base layer 10, wherein the mask layer 13 partially covers the piezoelectric material layer 12; wherein the metal electrode layer 11 is made of a metal material that is substantially unreactive with an alkaline solution.
[0048] First, a base layer 10 is provided. The base layer 10 may be a single-layer substrate, or may be other functional film layers on the substrate including the substrate. The base layer 10 may be selected according to actual needs.
[0049] Next, a metal electrode layer 11 with a thickness d1 between 10 nm and 1 um is deposited on the base layer 10. The deposition may be carried out by magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition, laser pulse deposition, etc., which are not limited here.
[0050] Furthermore, in order to prevent the alkaline solution from corroding the metal electrode layer 11 and keep the metal electrode layer 11 intact when the alkaline solution is used to remove the piezoelectric material layer 12 to form the groove in the subsequent step, the material of the metal electrode layer 11 needs to be a metal that is not easy to or does not react with the alkaline solution. In some embodiments, the material of the metal electrode layer 11 may include metals such as molybdenum (Mo) and ruthenium (Ru).
[0051] In addition, it should be noted that Figures 3 to 5 A simplified cross-sectional view illustrating a specific example of the process of forming a partial membrane structure of a piezoelectric micro-electromechanical device. Figure 2 The number of piezoelectric material layers 12 and metal electrode layers 11 presented is only an example, and the piezoelectric micro-electromechanical device may include any number of piezoelectric material layers 12 and metal electrode layers 11.
[0052] Next, a piezoelectric material layer 12 with a thickness d2 between 0.1 um and 2 um is deposited on the metal electrode layer 11 .
[0053] Depend on Figure 3 It can be seen that in the stacking direction D, the piezoelectric material layer 12 completely covers the underlying metal electrode layer 11 .
[0054] In some embodiments, the material used for the piezoelectric material layer 12 may include aluminum nitride (AlN), aluminum scandium nitride (AlScN), other piezoelectric thin film materials, or any combination of the above materials.
[0055] Finally, a mask layer 13 is prepared along both sides of the piezoelectric material layer 12 , so that the mask layer 13 covers both side regions of the piezoelectric material layer 12 .
[0056] A patterned mask is prepared on the top surface of the piezoelectric material layer 12 to form a mask layer 13. The mask layer 13 is located on both side regions of the piezoelectric material layer 12, and the middle region of the piezoelectric material layer 12 is left empty for subsequent formation of grooves.
[0057] At this point, the process before the trench etching process of the piezoelectric material layer 12 is completed. The mask layer 13 can be photoresist, other suitable mask materials or any combination thereof.
[0058] Step 201 : dry-etching the area outside the mask layer 13 on the piezoelectric material layer 12 to form a groove 15 in the piezoelectric material layer 12 , and retaining a reserved layer 12 a on the inner wall of the groove 15 .
[0059] The area outside the mask layer 13 on the piezoelectric material layer 12 is etched toward the metal electrode layer 11 , that is, the middle area of the piezoelectric material layer 12 where the mask layer 13 is not formed is etched, and a groove 15 is formed in the middle area of the piezoelectric material layer 12 .
[0060] In some embodiments, dry etching may be performed using Cl2 (chlorine) gas, Ar (argon) gas, other gases, or any combination thereof.
[0061] Furthermore, during etching, 1% to 10% of the thickness of the piezoelectric material layer 12 is retained along the inner wall of the groove 15 as a reserved layer 12 a.
[0062] Specifically, by controlling relevant parameters of the dry etching process, such as gas flow, etching gas type, number of etching steps and etching time, a portion of the piezoelectric material layer 12 between the groove and the target morphology can be retained as a reserved layer 12a based on the target morphology.
[0063] If this part of the piezoelectric material layer 12 is not retained as the reserved layer 12a, and the dry etching process is directly used to achieve the target morphology structure and CD (Critic Dimension, which refers to the critical dimension that needs to be strictly controlled during the manufacturing process) size, the piezoelectric material layer 12 and the metal electrode layer 11 will be damaged during the subsequent wet cleaning process using an alkaline solution to remove the polymer 14.
[0064] When this part of the piezoelectric material layer 12 is retained as the reserved layer 12a, in the subsequent wet cleaning process, the alkaline solution can remove the polymer 14 through the sacrificial reserved layer 12a without corroding the final target morphology of the piezoelectric material layer 12, so as to ensure the overall morphology of the device is stable.
[0065] Specifically, if Figure 4 and Figure 5 As shown, the thickness of the piezoelectric material layer 12 retained as the reserved layer 12 a may be in the range of about 1% to about 10% of the total thickness of the deposited piezoelectric material layer 12 , and the reserved layer 12 a is disposed along the inner wall of the groove 15 .
[0066] Figure 4 and Figure 5 The cross-sectional morphology shown can achieve the effect of the present application, wherein: Figure 4 The reserved layer 12a is connected to form a layer along the side wall and the bottom wall of the groove 15. Figure 5The reserved layer 12a is basically formed only on the sidewall and the bottom of the sidewall of the trench 15. Figure 4 Can be seen as Figure 5 The same type of morphology is obtained by reducing the etching time. Figure 5 The chamfer 12b at the bottom of the groove 15 is thicker and extends longer. Depending on the etching time, the extension may even completely cover the bottom metal electrode layer 11. As the etching time decreases, the bottom metal electrode layer 11 will be completely covered by the reserved layer 12a, and the following is obtained: Figure 4 The shape shown.
[0067] Figure 4 and Figure 5 The main morphological features are as follows: the reserved layer 12a presents a partially flat surface on the top sidewalls on both sides of the groove 15 away from the metal electrode layer 11, and the reserved layer 12a forms a chamfer 12b at the bottom sidewall of the groove 15 close to or adjacent to the metal electrode layer 11, which is a transition between the bottom of the reserved layer 12a, that is, the reserved layer 12a presents a curved surface at the inclined surface of the bottom sidewall of the groove 15, and the partially curved chamfer 12b can prevent the piezoelectric material layer 12 from being undercut during subsequent wet cleaning, so that the piezoelectric material layer 12 forms a fuller morphology at the bottom sidewall of the groove 15.
[0068] It should be pointed out that Figure 4 to Figure 5 All intermediate transition states of morphology evolution, or morphologies similar to all morphologies in the process state are within the protection scope of this application.
[0069] The dry etching used in the above process is a technology used in microelectronics manufacturing and semiconductor processing, and its essence is a subtractive manufacturing technology for materials. Generally, before the dry etching process is performed, a patterned mask layer 13 needs to be prepared on the etched area by photolithography technology, and the non-etched area is protected by the mask layer 13. The substrate to be etched, which has a patterned mask layer 13, is placed in the vacuum working chamber of the etching machine. Under a vacuum environment, the machine generates plasma through an ion generator, and the plasma is accelerated by a magnetic field to generate an ion beam to bombard the surface of the substrate. The ion energy is sufficient to destroy the chemical bonds on the surface of the substrate, thereby achieving etching; the reaction product generated during the etching process is the polymer 14, which will accumulate on the surface and needs to be removed by vacuuming or other means.
[0070] On the other hand, by Figure 2 to Figure 5 It can be seen that the wall thickness of the groove 15 of the present application (ie, the wall thickness d3 of the piezoelectric material layer 12 ) gradually increases from the top far away from the metal electrode layer 11 to the bottom close to the metal electrode layer 11 , so that the groove 15 forms an inverted trapezoidal groove.
[0071] Of course, in some other embodiments, the groove 15 may also be a straight groove, that is, the wall thickness of the groove 15 remains constant from the top far away from the metal electrode layer 11 to the bottom close to the metal electrode layer 11 .
[0072] As mentioned above, polymer 14 will be produced during the dry etching process, and polymer 14 will adhere to the sidewalls (grooves 152) of the mask layer 13 and / or the sidewalls of the reserved layer 12a and the bottom wall (grooves 151) of the reserved layer 12a.
[0073] The specific location where the polymer 14 is attached may vary depending on the parameters and environment of the etching process. In some embodiments, the polymer 14 is formed on the sidewall slope of the groove 15 (the groove 15 is a collective term for the groove 151 of the piezoelectric material layer 12 and the groove 152 of the mask layer 13), that is, the polymer 14 is attached to the sidewall slope of the mask layer 13 and the sidewall slope of the piezoelectric material layer 12.
[0074] In some embodiments, the length of the polymer 14 is in a range from about 1% to about 100% of the length of the slope of the sidewall of the trench 15 .
[0075] In some embodiments, the polymer 14 grows from the interface between the piezoelectric material layer 12, the groove 15 and the mask layer 13, and extends along the sidewall slope of the mask layer 13 toward the top surface of the mask layer 13, with a length ranging from about 1% to about 100% of the length of the sidewall slope of the mask layer 13.
[0076] In some embodiments, the polymer 14 is not tightly attached to the inclined surface of the sidewall of the mask layer 13 or the inclined surface of the sidewall of the piezoelectric material layer 12 , and there may be a gap between the contact surfaces.
[0077] In some embodiments, the surface of the polymer 14 is not flat, or has a wave-like or other undulating surface topography.
[0078] In some embodiments, the cross-sectional width d4 of the polymer 14 is in a range from about 10 angstroms to about 4000 angstroms (angstroms are a unit of length of 0.1 nanometers).
[0079] In some embodiments, the polymer 14 does not completely cover the sidewall slope of the groove 15, but there are intervals along the lateral direction (direction of the cross-sectional width d4) of the sidewall slope, and the spacing and number of the intervals are randomly presented.
[0080] Step 202 : wet-clean the groove 15 with an alkaline solution to remove the residual polymer 14 generated by etching, the reserved layer 12 a and the mask layer 13 , so that the piezoelectric material layer 12 forms a target morphology and exposes the metal electrode layer 11 .
[0081] The alkaline solution reacts with the polymer 14 and the reserved layer 12a in the groove 15, and the bottom surface of the groove 15 and the reserved layer 12a on the inclined side wall are removed by a wet cleaning process to expose the metal electrode layer 11. At the same time, the polymer 14 on the inclined side wall of the groove 15 and the mask layer 13 are removed by a wet cleaning process to achieve the purpose of removing the polymer 14, the reserved layer 12a and the mask layer 13. After the polymer 14, the reserved layer 12a and the mask layer 13 are removed, a Figure 2 The target morphology after wet cleaning is that the piezoelectric material layer 12 at the bottom of the groove 15 forms a fuller morphology, which solves the problem of the residual polymer 14 in the prior art being unable to be cleaned and causing the bottom of the piezoelectric material layer 12 to be undercut.
[0082] Generally, the wet removal process of the polymer 14 uses an alkaline solution for operations such as immersion or spraying. When facing common wafer manufacturing materials such as SiO2, Si, and SiN, the alkaline solution will not damage them. At the same time, it can effectively dissolve the polymer 14 produced after dry etching, and has a good removal effect and a very high selectivity. However, the alkaline solution will react with the piezoelectric material layer 12. Even if the polymer 14 is removed, it will cause morphological damage and CD abnormalities to the device, which is not worth the loss.
[0083] Therefore, the present application utilizes the reserved layer 12a to bear the corrosion of the piezoelectric material layer 12 by the alkaline solution during the wet cleaning process, and by properly controlling the parameters such as the wet cleaning process time and temperature, the alkaline solution removes the polymer 14 and the reserved layer 12a, and completely exposes the bottom metal electrode layer 11. The process flow of the present application will not form Figure 1b The damage to the piezoelectric material layer 12 and the metal electrode layer 11 shown will not affect the subsequent process and device performance of the device.
[0084] By utilizing the corrosion characteristics of the alkaline solution on the piezoelectric material layer 12, the groove 15 is completely connected with the bottom metal electrode layer 11; at the same time, since the wet etching is an isotropic etching process, the groove 15 will also be widened laterally, ultimately achieving the target morphology that meets the requirements.
[0085] In addition, the present application uses a corrosion-resistant metal as the metal electrode layer 11. Compared with the loss of the underlying metal electrode layer 11 due to over-etching in the existing dry etching process, the alkaline solution of the present application has an extremely high selectivity for the metal electrode layer 11 and the piezoelectric material layer 12, and can accurately stop the etching process on the metal electrode layer 11, thereby ensuring the integrity of the metal electrode layer 11 and making the surface of the metal electrode layer 11 flat.
[0086] It can be seen from this that the alkaline solution needs to be able to remove the polymer 14 without leaving any residue in the groove 15; at the same time, it is also necessary to react with the piezoelectric material layer 12 and corrode the reserved layer 12a to form the desired morphology; the alkaline solution cannot react with the metal electrode layer 11 to ensure that the underlying metal electrode layer 11 is not damaged, and a metal electrode layer 11 with a flat surface and integrity is obtained.
[0087] Specifically, the execution process of the wet cleaning process mainly includes the following steps:
[0088] The polymer 14, the reserved layer 12a and the mask layer 13 are removed using an alkaline solution:
[0089] The alkaline solution treatment process may be performed by immersion, spraying, or any combination of the above. The alkaline solution may include an EKC solution, etc., and the alkaline solution is used to react with the polymer 14, the reserved layer 12a, and the mask layer 13 at a temperature ranging from about 30° C. to about 90° C. for about 3 minutes to 30 minutes.
[0090] Clean the groove 15 by alcohol or ketone solution:
[0091] The alcohol solution may be an isopropyl alcohol solution, etc., and the ketone solution may be an acetone solution, etc. The cleaning process is performed at a temperature ranging from about 10° C. to about 40° C., and the trench 15 is cleaned for about 1 minute to 30 minutes.
[0092] Use deionized water to clean the groove 15:
[0093] The trench 15 is rinsed with deionized water at a temperature in the range of about 10° C. to about 40° C. for about 1 minute to 30 minutes.
[0094] Drying the groove 15:
[0095] The trench 15 is dried at a temperature of 20° C. to 80° C. for about 1 minute to 45 minutes. The drying process uses a suitable drying device (eg, a spin dryer, a drying box, etc.) to dry the wafer.
[0096] It should be noted that the above four steps can be repeated multiple times and in different combinations to achieve the effect of effectively removing the polymer 14, the reserved layer 12a and the mask layer 13, and finally obtain Figure 6 The structural morphology shown.
[0097] In summary, the preparation method of the piezoelectric micro-electromechanical device provided in the embodiment of the present application effectively removes the polymer 14 residue on the surface of the structure; and retains a portion of the piezoelectric material layer 12 as a reserved layer 12a through a dry etching process. During the wet cleaning process, the reserved layer 12a is removed while ensuring that the underlying metal electrode layer 11 is completely exposed, while also avoiding side digging at the bottom of the groove 15, thereby ensuring the morphology of the structure after the process flow: controlling the etching process so that the piezoelectric material layer 12 appears on the inner wall at the bottom of the groove 151 as shown in FIG. Figure 4 or Figure 5 The morphology of the curved chamfer 12b shown in the figure; by controlling the etching process parameters and ensuring that the metal electrode layer 11 will not be completely exposed during the process, the metal electrode layer 11 will not be damaged. In this way, the reserved layer 12a can ensure that the corrosion of the alkaline solution during wet cleaning will not cause side hollowing of the bottom inner wall of the piezoelectric material layer 12 and bottom notches, thereby ensuring the morphology of the device after the process flow.
[0098] Therefore, an alkaline solution is used to simultaneously remove the polymer 14 and the etched material (reserved layer 12a). In the wet cleaning step, the polymer 14 is cleaned while the reserved layer 12a and the mask layer 13 are corroded. Multiple purposes are achieved in one step, which can effectively simplify the process steps and reduce the process cost.
[0099] In addition, high-selectivity wet etching is achieved on the metal electrode layer 11, reducing over-etching and damage to the metal electrode layer 11 caused by pure dry etching: Since corrosion-resistant metal is used as the material of the metal electrode layer 11, when the alkaline solution corrodes the interface of the metal electrode layer 11, it will not affect the metal electrode layer 11. Compared with the existing dry etching process, this application greatly improves the selectivity of the piezoelectric material layer 12 and the metal electrode layer 11, ensures the integrity of the device morphology, and improves the performance of the device. At the same time, the wet cleaning process can achieve the effects of degumming, cleaning and etching at the same time, simplifying the process and reducing manufacturing costs.
[0100] In general, the present application adopts an etching process flow scheme for depositing a piezoelectric material layer 12 structure on a metal electrode layer 11, first performing a dry etching process, and then completing a wet etching process for the device through a high selectivity ratio between the metal electrode layer 11 and the piezoelectric material layer 12, thereby realizing an integrated process scheme for etching the wafer reserved layer 12a, removing the polymer 14, and cleaning the wafer; by optimizing the process flow, adjusting the etching menu, selecting metals, and making full use of the characteristics of alkaline solutions, the problem of the difficulty in removing the polymer 14 during the traditional etching process of the piezoelectric material layer 12 is overcome, the integrity of the morphology is ensured, and the application scenarios of alkaline solutions are expanded.
[0101] On this basis, the present application also discloses a piezoelectric micro-electromechanical device, which is prepared by the above-mentioned piezoelectric micro-electromechanical device preparation method, such as Figure 2 As shown, the piezoelectric micro-electromechanical device includes a base layer 10 , a metal electrode layer 11 and a piezoelectric material layer 12 which are stacked in sequence. The piezoelectric material layer 12 is formed with a groove which extends to the metal electrode layer 11 and exposes the metal electrode layer 11 .
[0102] The piezoelectric micro-electromechanical device has the same structure and beneficial effects as the piezoelectric micro-electromechanical device in the aforementioned embodiment. The structure and beneficial effects of the piezoelectric micro-electromechanical device have been described in detail in the aforementioned embodiment, and will not be repeated here.
[0103] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing a piezoelectric micro-electromechanical device, characterized in that: include: Providing a base layer, on which at least a metal electrode layer, a piezoelectric material layer and a mask layer are sequentially formed, wherein the mask layer partially covers the piezoelectric material layer; wherein the metal electrode layer is made of a metal material that is substantially non-reactive with an alkaline solution; Dry etching the area outside the mask layer on the piezoelectric material layer to form a groove in the piezoelectric material layer, and retaining a reserved layer on the inner wall of the groove; The groove is wet cleaned with an alkaline solution to remove the residual polymer generated by etching, the reserved layer and the mask layer, so that the piezoelectric material layer forms a target morphology and exposes the metal electrode layer.
2. The method for preparing a piezoelectric micro-electromechanical device according to claim 1, characterized in that: The step of providing a base layer, and sequentially forming at least a metal electrode layer, a piezoelectric material layer, and a mask layer on the base layer, wherein the mask layer partially covers the piezoelectric material layer; wherein the metal electrode layer is made of a metal material that is substantially non-reactive with an alkaline solution, comprises: Depositing the metal electrode layer with a thickness of 10nm to 1um on the base layer, wherein the material of the metal electrode layer includes at least molybdenum and ruthenium; Depositing the piezoelectric material layer with a thickness between 0.1um and 2um on the metal electrode layer; The mask layer is prepared along two sides of the piezoelectric material layer so that the mask layer covers two side regions of the piezoelectric material layer.
3. The method for preparing a piezoelectric micro-electromechanical device according to claim 1, characterized in that: The dry etching of the area outside the mask layer on the piezoelectric material layer to form a groove in the piezoelectric material layer and retaining a reserved layer on the inner wall of the groove includes: Etching the area outside the mask layer on the piezoelectric material layer in the direction of the metal electrode layer to form the groove, and retaining 1% to 10% of the thickness of the piezoelectric material layer on the inner wall of the groove as the reserved layer; The reserved layer is formed with a chamfered corner at a bottom sidewall of the trench close to the metal electrode layer to transition to the bottom of the reserved layer.
4. The method for preparing a piezoelectric micro-electromechanical device according to claim 1 or 3, characterized in that: The dry etching of the area outside the mask layer on the piezoelectric material layer to form a groove in the piezoelectric material layer and retaining a reserved layer on the inner wall of the groove includes: The wall thickness of the groove gradually increases from the top far away from the metal electrode layer to the bottom close to the metal electrode layer, so that the groove forms an inverted trapezoidal groove.
5. The method for preparing a piezoelectric micro-electromechanical device according to claim 1, characterized in that: The step of wet cleaning the groove with an alkaline solution to remove the residual polymer generated by etching, the reserved layer and the mask layer, so that the piezoelectric material layer forms a target morphology and exposes the metal electrode layer comprises: Using the alkaline solution to remove the polymer, the reserved layer and the mask layer; Cleaning the groove by alcohol or ketone solution; Cleaning the groove with deionized water; The grooves are dried.
6. The method for preparing a piezoelectric micro-electromechanical device according to claim 5, characterized in that: The step of wet cleaning the groove with an alkaline solution to remove the residual polymer generated by etching, the reserved layer and the mask layer, so that the piezoelectric material layer forms a target morphology and exposes the metal electrode layer comprises: At a temperature of 30° C. to 90° C., using an alkaline solution to react with the polymer, the reserved layer, and the mask layer for 3 minutes to 30 minutes; At a temperature of 10° C. to 40° C., the groove is cleaned with an alcohol or ketone solution for 1 minute to 30 minutes; At a temperature of 10° C. to 40° C., the groove is cleaned with deionized water for 1 minute to 30 minutes; The groove is dried at a temperature of 20° C. to 80° C. for 1 minute to 45 minutes.
7. A piezoelectric micro-electromechanical device, prepared according to the method for preparing a piezoelectric micro-electromechanical device according to any one of claims 1 to 6, characterized in that: The invention comprises a base layer, a metal electrode layer and a piezoelectric material layer which are stacked in sequence. The piezoelectric material layer is formed with a groove which extends to the metal electrode layer and exposes the metal electrode layer.
8. The piezoelectric micro-electromechanical device according to claim 7, characterized in that: The wall thickness of the groove gradually increases from the top far away from the metal electrode layer to the bottom close to the metal electrode layer, and the groove forms an inverted trapezoidal groove.
9. The piezoelectric micro-electromechanical device according to claim 7, characterized in that: The material of the metal electrode layer includes at least molybdenum and ruthenium.
10. The piezoelectric micro-electromechanical device according to claim 7, characterized in that: The thickness of the metal electrode layer is between 10nm and 1um, and the thickness of the piezoelectric material layer is between 0.1um and 2um.