A semiconductor device and a manufacturing method thereof

Abstract

A semiconductor device and a manufacturing method thereof, the manufacturing method comprising: providing a semiconductor substrate, the semiconductor substrate comprising a layer to be etched; forming a water-soluble material layer on the layer to be etched; forming a photoresist layer on the water-soluble material layer; exposing and developing the photoresist layer to form a window exposing the area to be etched in the photoresist layer, in the developing process, the developer dissolves the edge of the water-soluble material layer through the window to form an undercut area under the photoresist layer; dry etching the layer to be etched with the patterned photoresist layer as a mask, the etching gas of the dry etching reacts with the layer to be etched to form a polymer layer attached to the photoresist layer and the sidewall of the layer to be etched; removing the photoresist layer, the water-soluble material layer and the polymer layer by using a wet stripping process. According to the manufacturing method of the semiconductor device provided by the application, the polymer layer generated in the dry etching process can be effectively removed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a semiconductor device and its manufacturing method. Background Technology

[0002] Dry etching is an anisotropic etching technique that uses plasma to react physically or chemically with the layer to be etched. During dry etching, the etching gas readily reacts with the layer to be etched to form polymers. These polymers adhere to the photoresist and the sidewalls of the layer to be etched, and cannot be removed in subsequent wet stripping processes. Even after wet stripping, polymer residues remain on the sidewalls of the layer to be etched, severely impacting the performance of semiconductor devices.

[0003] Therefore, it is necessary to propose a new method for manufacturing semiconductor devices to solve the above problems. Summary of the Invention

[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] To address the existing problems, one embodiment of the present invention provides a method for manufacturing a semiconductor device, comprising:

[0006] A semiconductor substrate is provided, the semiconductor substrate including a layer to be etched;

[0007] A water-soluble material layer is formed on the layer to be etched;

[0008] A photoresist layer is formed on the water-soluble material layer;

[0009] The photoresist layer is exposed and developed to form a window in the photoresist layer that exposes the area to be etched. During the development process, the developer dissolves the edge of the water-soluble material layer through the window to form an undercut area below the photoresist layer.

[0010] Using the patterned photoresist layer as a mask, the layer to be etched is dry etched. The etching gas of the dry etching reacts with the layer to be etched to form a polymer layer attached to the photoresist layer and the sidewall of the layer to be etched.

[0011] The photoresist layer, the water-soluble material layer, and the polymer layer are removed using a wet stripping process.

[0012] In one embodiment, the material of the layer to be etched includes at least one piezoelectric layer.

[0013] In one embodiment, the piezoelectric layer comprises at least one of the following materials: lithium niobate, lithium tantalate, quartz, zinc oxide, aluminum nitride, barium strontium titanate, barium titanate, lead zirconate titanate, lithium lead barium niobate, and lead titanate.

[0014] In one embodiment, the layer to be etched further includes at least one of the following: monocrystalline silicon, polycrystalline silicon, silicon dioxide, titanium, and copper-aluminum alloy.

[0015] In one embodiment, the material of the water-soluble material layer includes a water-soluble non-photosensitive resin.

[0016] In one embodiment, after forming the water-soluble material layer, the method further includes:

[0017] The water-soluble material layer is cured at high temperature for a preset time.

[0018] In one embodiment, the high-temperature curing temperature is 150℃-210℃.

[0019] In one embodiment, the method further includes: determining the curing time and / or curing temperature of the high-temperature curing process based on the water solubility of the water-soluble material layer.

[0020] In one embodiment, the depth of the undercut zone is 1 μm-5 μm.

[0021] In one embodiment, removing the polymer layer through the undercut region includes:

[0022] The semiconductor substrate is immersed in a hydrofluoric acid solution, allowing the hydrofluoric acid solution to flow into the undercut region to remove the polymer layer.

[0023] In one embodiment, the semiconductor substrate includes a piezoelectric insulator substrate, which comprises, from bottom to top, a single-crystal silicon layer, a polycrystalline silicon layer, a silicon dioxide layer, and a piezoelectric layer; an interdigitated transducer metal layer and a protective layer covering the interdigitated transducer metal layer are also formed on the piezoelectric insulator substrate, and the water-soluble material layer is formed on the protective layer.

[0024] The layer to be etched includes the piezoelectric layer, the silicon dioxide layer, the polysilicon layer, and the protective layer.

[0025] Another aspect of the present invention provides a semiconductor device, which is manufactured using the method described above.

[0026] According to the semiconductor device manufacturing method provided by the present invention, a water-soluble material layer is formed under the photoresist layer, thereby dissolving the edge of the water-soluble material layer to form an undercut zone when the photoresist is developed. The polymer layer generated during the dry etching process can be effectively removed through the undercut zone. Attached Figure Description

[0027] The following drawings, which are incorporated herein by reference as part of this invention, are provided for understanding the invention. The drawings illustrate embodiments of the invention and their descriptions, serving to explain the principles of the invention.

[0028] In the attached image:

[0029] Figure 1 A schematic diagram is shown of the formation of a polymer layer during the etching process of a piezoelectric insulator substrate;

[0030] Figure 2 A schematic flowchart illustrating a method for manufacturing a semiconductor device according to a specific embodiment of the present invention is shown.

[0031] Figures 3A to 3E A schematic cross-sectional view of a semiconductor device obtained by sequentially performing each step of a method for manufacturing a semiconductor device according to an embodiment of the present invention is shown. Detailed Implementation

[0032] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0033] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0034] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0035] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0037] Surface acoustic wave (SAW) filters have the advantages of small size, suitability for micro-packaging, good consistency and no need for adjustment, and are widely used in 5G radio frequency. Among them, the performance of piezoelectric-on-insulator (POI) substrates is particularly excellent. SAW based on POI substrates has higher energy efficiency, lower energy loss, and therefore higher frequency and wider bandwidth.

[0038] See Figure 1 The POI substrate comprises, from bottom to top, a monocrystalline silicon layer 101, a polycrystalline silicon layer 102, a silicon dioxide layer 103, and a piezoelectric layer 104. In SAW or BAW (bulk acoustic wave filter) manufacturing processes, a dry etching process is required to open the piezoelectric layer 104, silicon dioxide layer 103, and polycrystalline silicon layer 102. During dry etching, plasma gas reacts with the piezoelectric layer 104 to generate a polymer 106, which adheres to the photoresist layer 105 and the sidewalls of the piezoelectric layer 104. Since the polymer is insoluble in the solvent of the wet stripping process, the polymer layer 106 cannot be removed in the subsequent wet stripping process, leaving polymer residue on the sidewalls of the piezoelectric layer 104 even after the photoresist layer 105 is removed.

[0039] Although polymers can dissolve in hydrofluoric acid (DHF) solution, DHF has a strong corrosive effect on both the metal and protective film on the semiconductor substrate. Therefore, the immersion time in DHF cannot be too long, which is the main reason why the industry currently struggles to remove polymers. Furthermore, the polymers generated during the etching process of POI substrates are bulky and large, further contributing to their difficulty in removal. Not only POI substrate etching generates polymers, but other etching processes also carry the risk of generating polymers that are difficult to remove. Currently, the industry's main solutions focus on preventing polymer formation, including upgrading etching equipment and changing the type of plasma gas, but these methods are all costly.

[0040] Based on this, the present invention proposes a method for manufacturing a semiconductor device, which removes the polymer layer generated by the dry etching process by forming a water-soluble material layer and forming an undercut region. The process is simple and has low cost.

[0041] To fully understand this invention, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this invention. Preferred embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0042] Figure 2 A flowchart illustrating the steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention is shown; Figures 3A-3EA schematic cross-sectional view of a semiconductor device obtained by sequentially performing each step of a method for manufacturing a semiconductor device according to an embodiment of the present invention is shown below. Figure 2 as well as Figures 3A-3E A method for manufacturing a semiconductor device according to an embodiment of the present invention will be described in detail.

[0043] First refer to Figure 2 A method for manufacturing a semiconductor device according to an embodiment of the present invention, such as... Figure 2 As shown, the semiconductor device manufacturing method 200 includes the following steps:

[0044] In step S201, a semiconductor substrate is provided, the semiconductor substrate including a layer to be etched;

[0045] In step S202, a water-soluble material layer is formed on the layer to be etched;

[0046] In step S203, a photoresist layer is formed on the water-soluble material layer;

[0047] In step S204, the photoresist layer is exposed and developed to form a window in the photoresist layer that exposes the area to be etched. During the development process, the developer dissolves the edge of the water-soluble material layer through the window to form an undercut area below the photoresist layer.

[0048] In step S205, using the patterned photoresist layer as a mask, the layer to be etched is dry etched. The etching gas of the dry etching reacts with the layer to be etched to form a polymer layer attached to the photoresist layer and the sidewall of the layer to be etched.

[0049] In step S206, the photoresist layer, the water-soluble material layer, and the polymer layer are removed using a wet stripping process.

[0050] According to the semiconductor device manufacturing method provided by the present invention, a water-soluble material layer is formed under the photoresist layer, thereby dissolving the edge of the water-soluble material layer to form an undercut zone when the photoresist is developed. The etchant can enter the interior of the polymer layer through the undercut zone and react with the polymer, causing the polymer to peel off from the layer to be etched, thereby effectively removing the polymer layer generated during the dry etching process.

[0051] The following is combined with Figures 3A to 3D An exemplary description is provided of the implementation process of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

[0052] First, a semiconductor substrate is provided, comprising a layer to be etched. The semiconductor substrate includes, but is not limited to, at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors; or silicon-on-dielectric (SOI), silicon-on-dielectric (SSOI), silicon-on-dielectric (S-SiGeOI), silicon-on-dielectric (SiGeOI), and germanium-on-dielectric (GeOI); or it may be a double-sided polished wafer (DSP), a ceramic substrate such as alumina, a quartz, or a glass substrate. The layer to be etched may include a portion of the semiconductor substrate, or it may include other layer structures formed on the semiconductor substrate.

[0053] In one embodiment, referring to Figure 3, the semiconductor substrate is a piezoelectric insulator (POI) substrate, which includes, from bottom to top, a single-crystal silicon layer 301, a polycrystalline silicon layer 302, a silicon dioxide layer 303, and a piezoelectric layer 304. The layer to be etched includes the piezoelectric layer 304, the silicon dioxide layer 303, and the polycrystalline silicon layer 302.

[0054] Exemplarily, the piezoelectric layer 304 comprises one or more piezoelectric materials selected from lithium niobate (LiNbO3), lithium tantalate (LiTaO3), quartz, zinc oxide (ZnO), aluminum nitride (AlN), barium strontium titanate (BST), barium titanate (BT), lead zirconate titanate (PZT), lithium lead barium niobate (PBLN), and lead titanate (PT). It should be noted that the piezoelectric layer may also be doped with rare earth elements, such as any one or a combination of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu) to improve the piezoelectric coefficient. The piezoelectric layer 304 can be formed by physical vapor deposition, specifically by vacuum evaporation, sputtering, ion plating, etc. The resulting piezoelectric layer 304 is microcrystalline or amorphous.

[0055] Beneath the piezoelectric layer 304 is a silicon dioxide layer 303, also known as a buried oxide layer. This buried oxide layer acts as a temperature compensation layer, suppressing the expansion or contraction of the piezoelectric layer 304 due to temperature changes, thus preventing it from affecting the frequency. Below the silicon dioxide layer 303 is a polycrystalline silicon layer 302, used to provide high resistivity to reduce losses. Besides polycrystalline silicon layers, materials used to provide high resistivity include polycrystalline alumina, polycrystalline silicon dioxide, or polycrystalline silicon carbide.

[0056] Continue to refer to Figure 3A When the semiconductor substrate is a POI substrate, an interdigitated transducer (IDT) metal layer is also formed on the piezoelectric layer 304. The material of the IDT metal layer 305 includes Ti, AlCu, etc. A protective layer 306 is formed on the IDT metal layer 305, which includes, but is not limited to, a silicon nitride (SiN) layer. Subsequent dry etching also forms openings in the protective layer 306, meaning that the layer to be etched may also include the protective layer 306.

[0057] Next, see Figure 3B A water-soluble material layer 307 and a photoresist layer 308 are sequentially formed on the layer to be etched. In one embodiment, the water-soluble material layer 307 is formed on the protective layer 306. Preferably, in the developer, the dissolution rate of the water-soluble material layer 307 is higher than that of the photoresist layer 308, so that the subsequent developer can laterally dissolve the water-soluble material layer 307 to form a larger undercut area.

[0058] The water-soluble material layer can be any material layer with water solubility. It can be a water-soluble organic layer, and more specifically, the material includes a water-soluble non-photosensitive resin. The water-soluble material layer can be a lift-off photoresist used in photolithography. For example, water-soluble material layer 307 can be a LOL photoresist, whose main component is a water-soluble non-photosensitive resin that can be dissolved in the developer. For example, the thickness of the LOL photoresist is approximately 0.5 μm. Besides LOL photoresist, LOR photoresist can also be used as the water-soluble material layer 307. LOR photoresist has lower water solubility than LOL photoresist, and therefore dissolves less quickly in the developer. It should be noted that the LOL and LOR photoresists listed above are merely examples; other materials that can dissolve in the developer can also be used for water-soluble material layer 307. For example, water-soluble material layer 307 can be a negative photoresist that dissolves in the developer when not exposed.

[0059] For example, after coating the water-soluble material layer 307, the process further includes high-temperature curing of the water-soluble material layer 307 for a predetermined time to prevent it from dissolving too quickly. If the undercut zone is too large, i.e., the lateral extension depth is too deep, the IDT metal layer 305 near the area to be etched will be exposed, making it susceptible to corrosion by the subsequent DHF solution. If the undercut zone is too small, the polymer may not be broken down, making it impossible to remove effectively. A suitable depth for the undercut zone is 1μm-5μm, and more specifically, the depth can be set to 2μm-4μm. To form an undercut zone within this depth range, the high-temperature curing temperature can be set to 150℃-210℃.

[0060] For example, the curing time and temperature for high-temperature curing can be determined based on the water solubility of the water-soluble material layer 307. Higher water solubility in the water-soluble material layer 307 requires a higher curing temperature and a longer curing time to avoid an excessively deep undercut zone. Conversely, lower water solubility in the water-soluble material layer 307 requires a lower curing temperature and a shorter curing time to avoid an excessively shallow undercut zone. For instance, if the water-soluble material layer is LOL adhesive, it can be initially cured at 200°C for 10 minutes to form an undercut zone with a depth of approximately 4 μm. If a lower water solubility LOR adhesive is used, the aforementioned high-temperature curing conditions may result in an undercut zone depth of less than 1 μm. Therefore, the high-temperature curing temperature can be reduced to 160°C to increase the undercut zone depth to approximately 2 μm.

[0061] Subsequently, a photoresist layer 308 is formed on top of the water-soluble material layer 307. The main components of the photoresist layer 308 are resin and photosensitizer. The resin has adhesive properties; for positive photoresist, the resin is relatively insoluble before exposure, but undergoes a chemical reaction after exposure, changing from insoluble to soluble. The photosensitizer acts as a dissolution inhibitor before exposure, reducing the dissolution rate of the resin, and as a dissolution enhancer after exposure, improving the photoresist's solubility in the developer. The photoresist coating method includes spin coating. During spin coating, centrifugal force causes the solvent to continuously evaporate, thereby forming a uniformly coated photoresist layer 308.

[0062] Continue to refer to Figure 3B After forming the photoresist layer 308, the photoresist layer 308 is exposed and developed to form windows in the photoresist layer 308 that expose the areas to be etched. During the development process, the developer dissolves the edge of the water-soluble material layer 307 through the windows of the photoresist layer 308 to form an undercut region 309 below the photoresist layer 308. The undercut region 309 is a laterally extending groove formed at the edge of the window of the photoresist layer 308, and the depth of the undercut region 309 refers to the distance laterally extended from the opening.

[0063] In one embodiment, the photoresist layer 308 is made of positive photoresist, and the exposed area corresponds to the etchable area of ​​the layer to be etched. The properties of the photoresist layer 308 change after exposure, making it readily soluble in the developer, while the photoresist layer 308 that has not undergone exposure will not dissolve in the developer. After immersion in the developer, the photoresist layer 308 in the exposed area is removed, forming a window above the etchable area.

[0064] In other embodiments, the photoresist layer 308 can also be made of a negative photoresist material. In this case, the area to be etched is a non-exposed area, and the exposure process targets the photoresist layer 308 outside the area to be etched. After exposure, the material properties of the photoresist layer 308 change, becoming a material that is difficult to dissolve in the developer, while the photoresist layer 308 in the non-exposed area is easily soluble in the developer. Next, the photoresist layer 308 is immersed in the developer to remove the photoresist layer 308 in the non-exposed area, thereby forming a window above the area to be etched.

[0065] During the development of the photoresist layer 308, after the developer dissolves the photoresist layer 308 to form a window, it will dissolve the water-soluble material layer 307 at the bottom of the window and continue to dissolve the water-soluble material layer 307 in a direction parallel to the surface of the semiconductor substrate, thereby forming a laterally extending groove at the bottom of the photoresist layer 307, namely the undercut region 309. In order to ensure the removal of the polymer layer without damaging the IDT metal layer, a suitable depth for the undercut region 309 is 1μm-5μm, and further, the depth of the undercut region 309 can be set to 2μm-4μm.

[0066] Then, refer to Figure 3C Using a patterned photoresist layer 308 as a mask, dry etching is performed on the layer to be etched, thereby forming grooves in the material layer to be etched. Figure 3D for Figure 3C Enlarged view of the area with the dashed line, such as Figure 3D As shown, the etching gas in dry etching reacts with the layer to be etched to form a polymer layer 310. The polymer layer 310 adheres to the sidewalls of the photoresist layer 308 and the layer to be etched (including the protective layer 306 and the piezoelectric layer 304). However, due to the presence of the undercut region 309, the polymer layer 310 does not accumulate at the interface between the photoresist layer 308 and the layer to be etched. The polymer layer 310 adhering near the opening of the undercut region 309 is relatively thin and can be easily removed by the subsequent wet stripping process. The polymer that cannot be removed by the wet stripping process can also be removed by the descum step.

[0067] Dry etching processes include, but are not limited to, reactive ion etching (RIE), ion beam etching, plasma etching, or laser ablation. A single etching method or more than one etching method may be used. Figure 3C In the example, dry etching sequentially opened the protective layer 306, the piezoelectric layer 304, the silicon dioxide layer 303, and the polysilicon layer 302, forming a groove in the middle of the opening of the IDT metal layer 305.

[0068] As mentioned above, the plasma generated by the etching gas during the dry etching process reacts with the photoresist layer and the layer to be etched, forming a polymer layer that adheres to the sidewalls of the photoresist layer 308 and the layer to be etched. The formation of this polymer has various causes and its composition is quite complex; it is insoluble in the solvents used in the subsequent wet stripping process. However, these polymers must be removed after etching; otherwise, they will become particles and contaminants that increase the density of surface defects in the device, damaging device performance and affecting the yield and reliability of the device.

[0069] For example, the material of the layer to be etched includes at least one of the following: monocrystalline silicon, polycrystalline silicon, silicon dioxide, titanium, lithium tantalate, lithium niobate, and copper-aluminum alloys. Etching the above material layers easily produces a polymer layer, but the material of the layer to be etched is not limited to the above; the etching gas can also react with many other materials to generate a polymer layer.

[0070] After completing the dry etching, see Figure 3E The photoresist layer 308, the water-soluble material layer 307, and the polymer layer 310 are removed using a wet stripping process.

[0071] For example, the wet photoresist stripping process includes at least treating the semiconductor substrate with a diluted hydrofluoric acid (DHF) solution, allowing the hydrofluoric acid solution to flow into the undercut region, and removing the polymer layer through the undercut region. Since an undercut region is formed beneath the photoresist layer 308 in this embodiment of the invention, the DHF solution can flow into the gaps of the undercut region and react with the polymer internally, making the polymer layer easier to separate from the material layer to be etched.

[0072] Furthermore, the wet resist stripping process also includes prolonged immersion of the photoresist layer 308 in a resist stripping solution (e.g., a mixed acid solution) to dissolve the photoresist layer 308; and descumming via oxygen plasma. Generally, the wet resist stripping process involves the following steps: first, a short treatment with a DHF solution for approximately 10 seconds, followed by a descumming step for approximately 1 minute, and finally, a resist stripping solution treatment for approximately 60 minutes. It is evident that during the DHF treatment, the photoresist layer 308 has not yet been removed. Without the undercut region of this embodiment, the DHF solution can only react with the polymer from the outside, making it difficult to remove the polymer layer on the sidewalls of the layer to be etched. However, with the undercut region of this embodiment, the DHF solution can peel off the polymer layer from the inside. Furthermore, the presence of the undercut region allows the DHF solution to remove a portion of the photoresist layer 308 above the undercut region, exposing the polymer layer at the edge of the layer to be etched, thereby enabling the descumming step in the resist stripping process to better remove the polymer layer adhering to the edge of the layer to be etched.

[0073] Thus, the process steps of the semiconductor device manufacturing method according to an embodiment of the present invention are completed. It is understood that the semiconductor device manufacturing method of this embodiment includes not only the above steps, but may also include other necessary steps before, during or after the above steps, all of which are included within the scope of the manufacturing method of this embodiment.

[0074] According to the semiconductor device manufacturing method provided by the present invention, a water-soluble material layer is formed under the photoresist layer, thereby dissolving the edge of the water-soluble material layer to form an undercut zone when the photoresist is developed. The polymer layer generated during the dry etching process can be effectively removed through the undercut zone.

[0075] like Figure 3E As shown, this embodiment of the invention also provides a semiconductor device, which is manufactured by the semiconductor device manufacturing method 200 described above. In one embodiment, the semiconductor device is a surface acoustic wave (SAW) filter, which includes at least a POI substrate and interdigitated transducer (IDT) metal layers formed on the POI substrate, with trenches formed by etching using the method described above between the IDT metal layers. In another embodiment, the semiconductor device can also be implemented as a bulk acoustic wave (BAW) filter. Because the semiconductor device of this embodiment is manufactured using the method described above, no polymer residue remains on the sidewalls of the material layer to be etched, thereby improving the performance of the semiconductor device.

[0076] The present invention has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a semiconductor device, characterized in that, The method includes: A semiconductor substrate is provided, the semiconductor substrate including a layer to be etched; A water-soluble material layer is formed on the layer to be etched; A photoresist layer is formed on the water-soluble material layer; The photoresist layer is exposed and developed to form a window in the photoresist layer that exposes the area to be etched. During the development process, the developing solution dissolves the edge of the water-soluble material layer through the window to form an undercut area below the photoresist layer. Using the photoresist layer as a mask, the layer to be etched is subjected to dry etching. The etching gas of the dry etching reacts with the layer to be etched to form a polymer layer that adheres to the photoresist layer and the sidewall of the layer to be etched. The photoresist layer, the water-soluble material layer, and the polymer layer are removed using a wet stripping process.

2. The manufacturing method as described in claim 1, characterized in that, The layer to be etched includes at least one piezoelectric layer.

3. The manufacturing method as described in claim 2, characterized in that, The piezoelectric layer comprises at least one of the following materials: lithium niobate, lithium tantalate, quartz, zinc oxide, aluminum nitride, barium strontium titanate, barium titanate, lead zirconate titanate, lithium lead barium niobate, and lead titanate.

4. The manufacturing method as described in claim 2, characterized in that, The layer to be etched also includes at least one of the following materials: monocrystalline silicon, polycrystalline silicon, silicon dioxide, titanium, and copper-aluminum alloy.

5. The manufacturing method as described in claim 1, characterized in that, The material of the water-soluble material layer includes a water-soluble non-photosensitive resin.

6. The manufacturing method as described in claim 1, characterized in that, After forming the water-soluble material layer, the method further includes: The water-soluble material layer is cured at high temperature for a preset time.

7. The manufacturing method as described in claim 6, characterized in that, The high-temperature curing temperature is 150℃-210℃.

8. The manufacturing method as described in claim 6, characterized in that, Also includes: The curing time and / or curing temperature of the high-temperature curing are determined based on the water solubility of the water-soluble material layer.

9. The manufacturing method as described in claim 1, characterized in that, The depth of the undercut zone is 1μm-5μm.

10. The manufacturing method as described in claim 1, characterized in that, The wet stripping process includes at least treating the semiconductor substrate with a hydrofluoric acid solution, allowing the hydrofluoric acid solution to flow into the undercut region, and removing the polymer layer through the undercut region.

11. The manufacturing method according to any one of claims 1-10, characterized in that, The semiconductor substrate includes a piezoelectric insulator substrate, which comprises, from bottom to top, a single-crystal silicon layer, a polycrystalline silicon layer, a silicon dioxide layer, and a piezoelectric layer; an interdigitated transducer metal layer and a protective layer covering the interdigitated transducer metal layer are also formed on the piezoelectric insulator substrate, and the water-soluble material layer is formed on the protective layer. The layer to be etched includes the piezoelectric layer, the silicon dioxide layer, the polysilicon layer, and the protective layer.

12. A semiconductor device, characterized in that, The semiconductor device is manufactured using the method described in any one of claims 1-11.

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