Surface acoustic wave filter and manufacturing method thereof

Abstract

The invention provides a surface acoustic wave filter and a manufacturing method thereof. The surface acoustic wave filter comprises a substrate, an interdigital transducer and a temperature compensation layer, the interdigital transducer is arranged above the substrate, and the temperature compensation layer covers the surface of the interdigital transducer; the top end face of the temperature compensation layer is used for making contact with a PAD metal layer, and the PAD metal layer is used for achieving connection of external electric signals. The top end face comprises a first supporting face and a second supporting face which are connected with each other, and the first supporting face and the second supporting face are in arc transition. The technical problem solved by the invention is that an opening is formed in a partial structure of a temperature compensation layer after the treatment of a photoetching process, an etching process and a photoresist removing process, a slope is formed in the position of the partial opening, and a sharp corner is left at the top of the slope. Therefore, the safety problem of the PAD metal layer deposited on the temperature compensation layer at the corner position is caused.

Description

Technical Field

[0001] The present application relates to the technical field of filters, and in particular to a surface acoustic wave filter and a method for manufacturing the same. Background Art

[0002] The filter's PAD metal layer serves as the interface between the internal circuitry and the external package, primarily responsible for signal transmission. In practical applications, the PAD metal layer is often used in conjunction with a temperature compensation layer. The integration process of these two layers directly impacts the device's temperature stability, signal transmission efficiency, and long-term reliability.

[0003] Furthermore, after the temperature compensation layer is processed by photolithography, etching and desizing processes, openings are formed in some structures, and a slope is formed in some opening positions. However, a "sharp" corner is left at the top of the slope, resulting in safety issues at the corner position of the PAD metal layer deposited on the temperature compensation layer. Summary of the Invention

[0004] The technical problem solved by this application is that openings are formed in part of the structure of the temperature compensation layer after the photolithography process, etching process and degumming process, and a slope is formed in the part of the opening position. However, a "sharp" corner is left at the top of the slope, resulting in safety issues at the corner position of the PAD metal layer deposited on the temperature compensation layer.

[0005] To solve the above problems, the present application provides a surface acoustic wave filter, which includes a substrate, an interdigital transducer and a temperature compensation layer; the interdigital transducer is arranged above the substrate, and the temperature compensation layer covers the surface of the interdigital transducer; the top surface of the temperature compensation layer is used to contact the PAD metal layer, and the PAD metal layer is used to achieve connection to external electrical signals; wherein the top surface includes a first supporting surface and a second supporting surface that are connected to each other, and the first supporting surface and the second supporting surface have an arc-shaped transition.

[0006] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: In combination with the content of this technical solution, by adjusting the transition between the first support surface and the second support surface to form an arc, the appearance of sharp corners is effectively avoided, thereby avoiding the problem of stress concentration, and thus improving the reliability of PAD metal evaporation on the temperature compensation layer. For example, before evaporating the PAD metal on the temperature compensation layer, the arc top of the sharp corner structure can be passivated by means of a dry etching process, specifically achieving a smooth arc top transition between the first and second support surfaces. After the sharp corner structure is eliminated, the PAD metal evaporation can be carried out.

[0007] Furthermore, after achieving an arc-shaped transition between the first supporting surface and the second supporting surface, the contact surface area between the PAD metal layer and the temperature compensation layer is increased to a certain extent, further improving the interfacial bonding force of the PAD metal layer attached to the top surface, thereby ensuring the attachment security of the PAD metal layer.

[0008] In one example of the present application, the PAD metal layer includes a first extension portion and a second extension portion connected to each other; the first extension portion is disposed on the temperature compensation layer through a top surface, and the second extension portion is disposed on the surface of the interdigital transducer.

[0009] In one example of the present application, the IDT is directly extended and connected to the second extension portion; or, a through-hole structure is provided at a portion of the temperature compensation layer between the first extension portion and the IDT, and the through-hole structure is filled with metal material to connect the first extension portion and the IDT.

[0010] In one example of the present application, the first extension portion includes an extension portion 1 and an extension portion 2 connected to each other; the extension portion 1 is supported by the first support surface; the extension portion 2 is sloped, connected between the extension portion 1 and the second extension portion, and the extension portion 2 is supported by the second support surface.

[0011] In one example of the present application, the climbing angle of the second extension portion is recorded as a; wherein, 15°≤a≤45°.

[0012] In one example of the present application, a climbing contact surface is provided on the side of the PAD metal layer away from the temperature compensation layer, and the climbing contact surface includes a horizontal contact surface, a climbing inclined surface and a first arc-shaped transition surface; wherein the first arc-shaped transition surface is connected between the horizontal contact surface and the climbing inclined surface.

[0013] In one example of the present application, a second arc-shaped transition surface is formed between the first supporting surface and the second supporting surface; the first arc-shaped transition surface is located vertically above the second arc-shaped transition surface.

[0014] In one example of the present application, the second supporting surface is arranged to be inclined, and a climbing angle formed between the second supporting surface and the surface of the interdigital transducer is denoted as b; wherein 15°≤b≤45°.

[0015] On the other hand, the present application also provides a method for manufacturing a surface acoustic wave filter, the manufacturing method comprising: providing a substrate; manufacturing an interdigital transducer on one side surface of the substrate; manufacturing a temperature compensation layer on the surface of the interdigital transducer; before manufacturing a PAD metal layer on the temperature compensation layer, determining whether there is a sharp-angle structure on the top surface of the temperature compensation layer for contacting the PAD metal layer; if so, processing the sharp-angle structure to convert the sharp-angle structure into an arc-shaped structure; and manufacturing the PAD metal layer on the surface of the temperature compensation layer through the top surface.

[0016] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: specifically, after the temperature compensation layer is processed by etching or degumming process, a slope surface is formed on the surface, and the pointed angle structure is located at the top of the slope surface. The surface of the temperature compensation layer is roughly composed of a first supporting surface and a second supporting surface connected to each other. The first supporting surface is, for example, horizontally arranged, and the second supporting surface is inclined, and the pointed angle structure is formed at the intersection of the first supporting surface and the second supporting surface.

[0017] Furthermore, if the PAD metal is directly evaporated onto the surface of the temperature compensation layer, the sharp corners will cause stress concentration in the deposited PAD metal layer, making it prone to metal fracture. Therefore, by converting the sharp corners into curved structures, the stress concentration problem is effectively avoided. Moreover, compared with the sharp corners, the contact surface area between the PAD metal layer and the temperature compensation layer is increased, thereby enhancing the interfacial bonding strength between the two layers.

[0018] In one embodiment of the present application, a sharp-angle structure is processed to transform the sharp-angle structure into a curved structure, comprising: processing the sharp-angle structure through an etching process to obtain the curved structure; and / or After the PAD metal layer is formed on the surface of the temperature compensation layer through the top surface, the surface of the PAD metal layer is processed by an etching process to make the surface of the PAD metal layer smoothly transitioned; wherein the etching process includes a dry etching process.

[0019] By adopting the technical solution of this application, the following technical effects can be achieved: In combination with the content of this technical solution, by adjusting the arc-shaped transition between the first support surface and the second support surface, the appearance of the sharp-angle structure is effectively avoided, thereby avoiding the problem of stress concentration, and further improving the reliability of the PAD metal vapor deposition on the temperature compensation layer. For example, before vapor-depositing the PAD metal on the temperature compensation layer, the arc top of the sharp-angle structure can be passivated by means of a dry etching process, specifically to achieve a smooth transition between the arc top of the first support surface and the second support surface. After eliminating the sharp-angle structure, the PAD metal is vapor-deposited. Furthermore, after achieving an arc-shaped transition between the first support surface and the second support surface, the contact surface area between the PAD metal layer and the temperature compensation layer is increased to a certain extent, further improving the interface bonding force of the PAD metal layer attached to the top surface, and ensuring the attachment safety of the PAD metal layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings to be used in describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort. Figure 1 A schematic diagram of the structure of a cross-sectional schematic diagram of a surface acoustic wave filter provided in an embodiment of the present application; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 A schematic diagram of the structure of a cross-sectional schematic diagram of a surface acoustic wave filter provided by the prior art; Figure 4 A schematic flow chart of a method for manufacturing a surface acoustic wave filter provided in an embodiment of the present application.

[0021] Description of reference numerals: 100, surface acoustic wave filter; 10, substrate; 20, interdigital transducer; 30, temperature compensation layer; 31, first supporting surface; 32, second supporting surface; 33, second arc-shaped transition surface; 40, PAD metal layer; 41, first extension; 411, first extension; 412, second extension; 42, second extension; 43, horizontal contact surface; 44, climbing slope; 45, first arc-shaped transition surface; 200. Sharp-angle structure. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0023] In addition, terms indicating relative spatial positions in the text, such as "top", "bottom", "up", "down", "above", "below", etc., are used to describe the relationship between a unit or feature depicted in the descriptive figure and another unit or feature therein. Terms indicating relative spatial positions can also refer to positions other than those shown in the drawings when the device is in use or operating. For example, if the device shown in the figure is turned over, a unit described as being "above" or "below" another unit or feature will be above the other unit or feature. Therefore, the descriptive term "below" can include both above and below positions. The device can be oriented in other ways (for example, rotated 90 degrees or facing another direction), and spatially related descriptive terms appearing in the text should be interpreted accordingly. When a component or layer is referred to as being "above" or "connected to" another component or layer, it can be directly above or directly connected to the other component or layer, or there can be an intermediate component or layer.

[0024] See also Figure 1 , which is a cross-sectional schematic diagram of a surface acoustic wave filter 100 provided in an embodiment of the present application. Figure 2 and Figure 3 Specifically, the surface acoustic wave filter 100 includes a substrate 10, an interdigital transducer 20 and a temperature compensation layer 30; the interdigital transducer 20 is arranged above the substrate 10, and the temperature compensation layer 30 covers the surface of the interdigital transducer 20; the top surface of the temperature compensation layer 30 is used to contact the PAD metal layer 40, and the PAD metal layer 40 is used to realize the connection of external electrical signals; wherein, the top surface includes a first supporting surface 31 and a second supporting surface 32 connected to each other, and the first supporting surface 31 and the second supporting surface 32 have an arc-shaped transition.

[0025] For example, the temperature compensation layer 30 can be made of silicon dioxide (SiO2) to compensate for temperature drift, and the temperature compensation layer 30 serves as a dielectric isolation layer to separate the IDT 20 and the PAD metal. The IDT 20 is directly fabricated on the surface of the substrate 10.

[0026] Specifically, the PAD metal is deposited on the top surface of the temperature compensation layer 30 via vapor deposition to form the PAD metal layer 40. Prior to the vapor deposition operation, the temperature compensation layer 30 undergoes etching and resist stripping processes, forming a sloped structure on the top surface consisting of a first support surface 31 and a second support surface 32. Because the intersection of the first support surface 31 and the second support surface 32 forms a sharp-angled structure 200, stress concentration occurs when the PAD metal is deposited on the sloped structure, making the PAD metal layer 40 susceptible to fracture, thereby reducing the adhesion security of the PAD metal layer 40.

[0027] Furthermore, due to the presence of the aforementioned sharp-angle structure 200 , the interfacial adhesion of the PAD metal layer 40 on the temperature compensation layer 30 changes suddenly during the transition from the first support surface 31 to the second support surface 32 , thereby reducing the adhesion reliability of the PAD metal layer 40 .

[0028] Therefore, to address the aforementioned issues caused by the presence of the sharp-angled structure 200, in accordance with the present technical solution, by adjusting the transition between the first supporting surface 31 and the second supporting surface 32 to an arc-shaped transition, the sharp-angled structure 200 is effectively avoided, thereby avoiding the problem of stress concentration and further improving the reliability of the PAD metal vapor deposition on the temperature compensation layer 30. For example, before vapor-depositing the PAD metal on the temperature compensation layer 30, the sharp-angled structure 200 can be passivated at the top of the arc by means of a dry etching process, specifically achieving a smooth transition at the top of the arc between the first supporting surface 31 and the second supporting surface 32. After the sharp-angled structure 200 is eliminated, the PAD metal vapor deposition can be performed.

[0029] Furthermore, after achieving an arc-shaped transition between the first supporting surface 31 and the second supporting surface 32, the contact surface area between the PAD metal layer 40 and the temperature compensation layer 30 is increased to a certain extent, further improving the interfacial bonding force of the PAD metal layer 40 attached to the top surface, thereby ensuring the attachment security of the PAD metal layer 40.

[0030] Preferably, the PAD metal layer 40 includes a first extension portion 41 and a second extension portion 42 connected to each other; the first extension portion 41 is disposed on the temperature compensation layer 30 through a top surface, and the second extension portion 42 is disposed on the surface of the IDT 20 .

[0031] Preferably, the IDT 20 is directly connected to the second extension 42. Alternatively, a through-hole structure is provided in the temperature compensation layer 30 between the first extension 41 and the IDT 20, and the through-hole structure is filled with metal material to connect the first extension 41 to the IDT 20. For example, the through-hole structure formed in the temperature compensation layer 30 is used to vertically connect the IDT 20 and the PAD metal layer 40, and the through-hole structure is formed by etching. The diameter of the through-hole structure can be 0.8-2 μm.

[0032] Continue to combine Figure 1-Figure 3 Preferably, the first extension portion 41 includes an extension portion 1 411 and an extension portion 2 412 connected to each other; the extension portion 1 411 is supported by the first support surface 31; the extension portion 2 412 is sloped, connected between the extension portion 1 411 and the second extension portion 42, and the extension portion 2 412 is supported by the second support surface 32.

[0033] Specifically, the first extension 411 is located at a high position on the surface of the IDT 20 relative to the second extension 42. The second extension 412 has a high end and a low end arranged in a relative manner, with the high end connected to the first extension 411 and the low end connected to the second extension 42. Because the first support surface 31 and the second support surface 32 form an arc-shaped transition, a matching arc-shaped transition is achieved between the first extension 411 and the second extension 412. Specifically, the first bottom end surface of the first extension 411 and the second bottom end surface of the second extension 412 also form an arc-shaped transition with each other. This further improves the interfacial bonding strength between the PAD metal layer 40 and the temperature compensation layer 30.

[0034] Preferably, the slope angle of the second extension portion 412 is denoted as a, wherein 15°≤a≤45°. For example, a may also be 30°.

[0035] Preferably, a climbing contact surface is provided on the side of the PAD metal layer 40 away from the temperature compensation layer 30, and the climbing contact surface includes a horizontal contact surface 43, a climbing inclined surface 44 and a first arc-shaped transition surface 45; wherein the first arc-shaped transition surface 45 is connected between the horizontal contact surface 43 and the climbing inclined surface 44.

[0036] Preferably, a second arc-shaped transition surface 33 is formed between the first supporting surface 31 and the second supporting surface 32 ; the first arc-shaped transition surface 45 is located vertically above the second arc-shaped transition surface 33 .

[0037] Preferably, the second support surface 32 is inclined, and the slope angle formed between the second support surface 32 and the surface of the IDT 20 is denoted as b, wherein 15°≤b≤45°. For example, b can be 30°.

[0038] On the other hand, the embodiment of the present application also provides a method for manufacturing a surface acoustic wave filter 100, Figure 4 , the production method includes, for example: S1, providing a substrate 10; S2, fabricating an interdigital transducer 20 on one side surface of the substrate 10; S3, forming a temperature compensation layer 30 on the surface of the IDT 20; S4, before forming the PAD metal layer 40 on the temperature compensation layer 30, determining whether there is a sharp corner structure 200 on the top surface of the temperature compensation layer 30 that contacts the PAD metal layer 40; S41, if yes, processing the pointed structure 200 to transform the pointed structure 200 into a curved structure; S42 , forming a PAD metal layer 40 on the surface of the temperature compensation layer 30 through the top surface.

[0039] Specifically, after the temperature compensation layer 30 is etched or debonded, a sloped surface is formed on the surface, and the pointed structure 200 is located at the top of the sloped surface. The surface of the temperature compensation layer 30 is roughly composed of a first supporting surface 31 and a second supporting surface 32 that are connected to each other. The first supporting surface 31 is, for example, horizontally arranged, and the second supporting surface 32 is inclined, and the pointed structure 200 is formed at the intersection of the first supporting surface 31 and the second supporting surface 32.

[0040] Furthermore, if the PAD metal is directly evaporated onto the surface of the temperature compensation layer 30, the presence of the sharp corner structures 200 would cause stress concentration in the deposited PAD metal layer 40, making the PAD metal layer 40 susceptible to metal fracture. Therefore, by converting the sharp corner structures 200 into curved structures, the stress concentration problem is effectively avoided. Furthermore, compared to the sharp corner structures 200, the contact surface area between the PAD metal layer 40 and the temperature compensation layer 30 is increased, thereby enhancing the interfacial bonding strength between the two layers.

[0041] In contrast, when it is determined that the top surface of the temperature compensation layer 30 for contacting the PAD metal layer 40 does not have the sharp corner structure 200 , the PAD metal layer 40 is fabricated on the surface of the temperature compensation layer 30 through the top surface.

[0042] Preferably, the sharp-angle structure 200 is processed to transform the sharp-angle structure 200 into a curved structure, including: The pointed structure 200 is processed by an etching process to obtain an arc-shaped structure. It should be noted that the arc-shaped structure mentioned in this embodiment has the second arc-shaped transition surface 33 mentioned in the above embodiment.

[0043] and / or After the PAD metal layer 40 is formed on the surface of the temperature compensation layer 30 through the top surface, the surface of the PAD metal layer 40 is processed by an etching process to make the surface of the PAD metal layer 40 smoothly transitioned; wherein the etching process includes a dry etching process.

[0044] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims.

Claims

1. A surface acoustic wave filter, characterized in that: The surface acoustic wave filter comprises a substrate (10), an interdigital transducer (20), and a temperature compensation layer (30); The interdigital transducer (20) is arranged above the substrate (10), and the temperature compensation layer (30) covers the surface of the interdigital transducer (20); The top surface of the temperature compensation layer (30) is used to contact the PAD metal layer (40), and the PAD metal layer (40) is used to achieve connection with external electrical signals; The top end surface comprises a first supporting surface (31) and a second supporting surface (32) connected to each other, and an arc-shaped transition is formed between the first supporting surface (31) and the second supporting surface (32).

2. The surface acoustic wave filter according to claim 1, wherein The PAD metal layer (40) includes a first extension portion (41) and a second extension portion (42) connected to each other; The first extension portion (41) is arranged on the temperature compensation layer (30) through the top surface, and the second extension portion (42) is arranged on the surface of the interdigital transducer (20).

3. The surface acoustic wave filter according to claim 2, wherein The interdigital transducer (20) is directly extended and connected to the second extension portion (42); Alternatively, a portion of the temperature compensation layer (30) located between the first extension portion (41) and the interdigital transducer (20) is provided with a through-hole structure, and the through-hole structure is filled with a metal material to connect the first extension portion (41) and the interdigital transducer (20).

4. The surface acoustic wave filter according to claim 2, wherein The first extension portion (41) includes an extension portion 1 (411) and an extension portion 2 (412) connected to each other; The first extension portion (411) is supported by the first supporting surface (31); The second extension portion (412) is slope-shaped and connected between the first extension portion (411) and the second extension portion (42), and the second extension portion (412) is supported by the second supporting surface (32).

5. The surface acoustic wave filter according to claim 4, wherein The climbing angle of the second extension portion (412) is denoted as a; Among them, 15°≤a≤45°.

6. The surface acoustic wave filter according to any one of claims 1 to 5, characterized in that: A climbing contact surface is provided on a side of the PAD metal layer (40) away from the temperature compensation layer (30), and the climbing contact surface includes a horizontal contact surface (43), a climbing inclined surface (44) and a first arc-shaped transition surface (45); The first arc-shaped transition surface (45) is connected between the horizontal contact surface (43) and the climbing slope (44).

7. The surface acoustic wave filter according to claim 6, wherein A second arc-shaped transition surface (33) is formed between the first supporting surface (31) and the second supporting surface (32); The first arc-shaped transition surface (45) is located vertically above the second arc-shaped transition surface (33).

8. The surface acoustic wave filter according to any one of claims 1 to 5, characterized in that: The second supporting surface (32) is arranged in an inclined manner, and a climbing angle formed between the second supporting surface (32) and the surface of the interdigital transducer (20) is denoted as b; Among them, 15°≤b≤45°.

9. A method for manufacturing a surface acoustic wave filter, characterized in that: The production method comprises: providing a substrate (10); An interdigital transducer (20) is fabricated on one side surface of the substrate (10); Producing a temperature compensation layer (30) on the surface of the interdigital transducer (20); Before forming the PAD metal layer (40) on the temperature compensation layer (30), determining whether a sharp corner structure (200) exists on the top surface of the temperature compensation layer (30) for contacting the PAD metal layer (40); If so, processing the pointed structure (200) to transform the pointed structure (200) into an arc structure; The PAD metal layer (40) is manufactured on the surface of the temperature compensation layer (30) through the top surface.

10. The manufacturing method according to claim 9, characterized in that: The processing of the pointed structure (200) to transform the pointed structure (200) into an arc-shaped structure comprises: Processing the pointed structure (200) through an etching process to obtain the arc-shaped structure; and / or After the PAD metal layer (40) is formed on the surface of the temperature compensation layer (30) through the top surface, the surface of the PAD metal layer (40) is processed by an etching process to make the surface of the PAD metal layer (40) smoothly transitioned; Wherein, the etching process includes a dry etching process.

Images