A surface acoustic wave filter and its preparation method

Abstract

The present invention discloses a surface acoustic wave filter and its fabrication method. The surface acoustic wave filter comprises a substrate, two first interdigital electrodes, a plurality of second interdigital electrodes, an input transducer, and an output transducer. The two first interdigital electrodes are symmetrically arranged on the substrate, each having a first lead portion at its center. The substrate is provided with a deep hole shaped to match the bottom end of the first lead portion, and a metal coating is provided between the first lead portion and the deep hole. The surface acoustic wave filter designed in the present invention has high antistatic properties and can be fabricated through processes such as evaporation, etching, and metal filling, reducing manufacturing costs.

Description

Technical Field

[0001] The present invention belongs to the field of surface acoustic wave technology, relates to the design and manufacturing technology of surface acoustic wave filters, and specifically relates to a surface acoustic wave filter capable of improving antistatic performance and a preparation method thereof. Background Art

[0002] Surface acoustic wave (SAW) filters utilize the properties of surface acoustic waves to filter signals. They offer advantages such as small size, light weight, low cost, high reliability, and ease of integration. They are widely used in various electronic devices, including mobile communications, satellite communications, radar systems, and navigation systems. With the advancement of microelectronics manufacturing technology and the increasing integration and complexity of electronic devices, the manufacturing process for SAW filters has become increasingly complex, placing increasing demands on the manufacturing process and performance. Antistatic capability is a key performance characteristic.

[0003] The main method for improving the anti-static capability of surface acoustic wave filters in existing technologies is to form deep holes within the PAD metal layer and then fill these holes with metal. This method can effectively improve the anti-static capability of surface acoustic wave filters, but it requires complex evaporation and etching processes, resulting in high manufacturing costs, low production efficiency, and the possibility of process failures, which affect production stability and product quality.

[0004] In addition, while existing technologies improve the anti-static capability of surface acoustic wave filters, they may affect other properties, such as filtering performance and frequency selectivity, which limits their application in certain high-performance fields. Summary of the Invention

[0005] Technical purpose: In response to the above technical problems, the present invention proposes a surface acoustic wave filter and a preparation method thereof, which adopts evaporation and etching processes to form deep holes inside the PAD metal layer, and then fills the deep holes with metal, which can effectively improve the anti-static ability of the surface acoustic wave filter while avoiding the use of complex evaporation and etching processes, thereby reducing manufacturing costs and improving the company's market competitiveness.

[0006] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A surface acoustic wave filter, comprising:

[0008] substrate;

[0009] Two first interdigital electrodes are symmetrically arranged on the substrate, each interdigital electrode is a strip structure with a predetermined width and length, a first lead portion is provided in the middle portion, and extends beyond the upper and lower surfaces of the first interdigital electrode. The first lead portion is parallel to the long side direction of the first interdigital electrode and has the same length as the long side direction of the first interdigital electrode. A deep hole is provided in the substrate to match the shape of the bottom end of the first lead portion, and a metal plating layer is provided between the first lead portion and the deep hole.

[0010] a plurality of second interdigital electrodes, arranged in parallel between the two first interdigital electrodes;

[0011] The input transducer and the output transducer are respectively arranged on the first interdigital electrodes, which are PAD metal layers for connecting to external electrical signals.

[0012] Preferably, a second lead portion is provided below at least one interdigitated electrode, the second lead portion extends downward into a preset depth of the substrate, a deep hole matching the shape of the bottom end of the second lead portion is provided on the substrate, and a metal plating layer is provided between the second lead portion and the deep hole.

[0013] Preferably, a metal plating layer is provided between the first lead-out portion, the second lead-out portion and the corresponding deep hole, the material used for the metal plating layer is silver, and the material of the PAD metal layer is Ti, Cr or Ni.

[0014] Preferably, the surface acoustic wave filter further comprises:

[0015] a first passivation layer covering the surfaces of the second interdigital electrodes, the input transducer, the output transducer, and the surface of the first interdigital electrodes extending out of the PAD metal layer;

[0016] The second passivation layer is arranged between the first lead-out portion and the PAD metal layer.

[0017] Preferably, the depth of the deep hole is 1 / 3 of the thickness of the substrate.

[0018] A method for preparing a surface acoustic wave filter comprises the following steps:

[0019] Step 1: Select a substrate material and open deep holes of a predetermined number and shape at predetermined positions of the substrate material;

[0020] Step 2: fabricating two first interdigital electrodes, a first lead portion, and a plurality of second interdigital electrodes on the upper surface of the substrate and arranging them in a preset layout;

[0021] Step 3: fabricate corresponding PAD metal layers on the two first interdigital electrodes to form an input transducer and an output transducer;

[0022] Step 4: Use the evaporation process to form a metal coating in the deep hole below the PAD metal layer. The operation is as follows:

[0023] The workpiece with the PAD metal layer is placed in an evaporation device. By controlling the temperature and pressure of the evaporation device, metal atoms are deposited in the deep hole below the PAD metal layer, so that a metal coating is formed between the bottom end of the first lead-out portion and the deep hole.

[0024] Step 5: Use etching process to process the deep hole. The operation is as follows:

[0025] The workpiece after step 4 is placed in an etching device, and the temperature and voltage of the etching device are controlled so that the etching liquid etches the deep hole to improve the size and shape of the deep hole;

[0026] Step 6: Fill the deep hole with metal. The specific steps are as follows:

[0027] The workpiece that has completed step five is placed in a metal filling device. By controlling the temperature and pressure of the metal filling device, metal atoms are deposited again inside the deep hole until the deep hole is completely filled.

[0028] Preferably, in step 4, the temperature in the evaporation equipment is controlled at 200-300° C., the pressure is controlled at 1-5 Pa, and the evaporation time is 1-2 hours.

[0029] Preferably, in step five, the temperature of the etching equipment is controlled at 50-80° C., the voltage is controlled at 10-30 V, and the etching is performed for 30-60 minutes, so that the etching solution corrodes the deep hole to a predetermined size and shape.

[0030] Preferably, in step six, the temperature of the metal filling equipment is controlled at 200-300° C., the pressure is controlled at 1-5 Pa, and the filling time is 1-2 hours.

[0031] Beneficial effects: Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0032] 1) Reduce manufacturing costs: The present invention adopts a new process means, which can reduce manufacturing costs while improving production efficiency and enhancing the market competitiveness of enterprises.

[0033] 2) Improve production stability: The present invention optimizes the process flow, simplifies the operation process, effectively reduces the occurrence of process failures, improves production stability, and ensures product quality.

[0034] 3) Improved performance: By improving the process, the present invention can improve the antistatic ability while maintaining the stability of other properties, thereby expanding its application range in high-performance fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of a surface acoustic wave filter in Example 1;

[0036] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of the surface acoustic wave filter along the AB direction;

[0037] Among them, 1 is substrate, 2 is first interdigital electrode, 3 is second interdigital electrode, 4 is PAD metal layer, 5 is first lead portion, 6 is second lead portion, 7 is first passivation layer, and 8 is second passivation layer. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below.

[0039] Example 1

[0040] Figure 1 A surface acoustic wave filter is shown, comprising:

[0041] Substrate 1;

[0042] Two first interdigitated electrodes 2 are symmetrically arranged on the substrate 1. Each first interdigitated electrode 2 is a strip structure with a predetermined width and length. A first lead-out portion 5 is provided in the middle portion, extending beyond the upper and lower surfaces of the first interdigitated electrode 2. The first lead-out portion 5 is parallel to the long side direction of the first interdigitated electrode and has the same length as the long side. A deep hole that is adapted to the shape of the bottom end of the first lead-out portion 5 is provided on the substrate 1, and a metal plating layer is provided between the first lead-out portion 5 and the deep hole. The length of the common edge of the first lead-out portion 5 and the upper surface of the first interdigitated electrode 2 is a3, the length of the common edge of the first lead-out portion 5 and the lower surface of the first interdigitated electrode 2 is a1, and the width of the first interdigitated electrode is a2. The relationship is: a1 / a2=1 / 5, a3 / a1=1 / 3. The specific values ​​are taken according to the actual design values, and the unit is micrometer or nanometer.

[0043] A plurality of second interdigital electrodes 3 are arranged in parallel between the two first interdigital electrodes 2, with both ends of each second interdigital electrode respectively connected to the nearest first interdigital electrode 2, and each second interdigital electrode 3 is provided with a dummy gap;

[0044] The input transducer and the output transducer are respectively arranged on the first interdigital electrode. In order to realize the PAD metal layer 4 for connecting to the external electrical signal, the left and right PADs are symmetrical.

[0045] a first passivation layer 7 covering the surfaces of the second interdigital electrodes, the input transducer, the output transducer, and the surface of the first interdigital electrodes 2 extending out of the PAD metal layer 4;

[0046] The second passivation layer 8 is disposed between the first lead-out portion 5 and the PAD metal layer 4 .

[0047] like Figure 2As shown, two second lead portions 6 are provided below one of the second interdigital electrodes 3. These extend downward into the substrate to a predetermined depth. Deep holes are formed in the substrate 1 to match the shape of the bottom ends of the second lead portions 6. A metal coating is provided between the second lead portions 6 and the deep holes. The top width b1 of the second lead portion 6 and the distance b2 between the two second lead portions 6 are related by the following relationship: b1 / b2 = 1 / 5 to 1 / 10.

[0048] Example 2:

[0049] This embodiment provides a method for preparing a surface acoustic wave filter having the structure described in the first embodiment, and the specific steps are as follows:

[0050] Step 1: Select a substrate material and open deep holes of a predetermined number and shape at predetermined positions on the substrate material. The depth of the deep holes is about 1 / 3 of the thickness of the substrate.

[0051] Step 2: fabricating the first interdigital electrode, the first lead portion, the second interdigital electrode, and the second lead portion of the structure on the upper surface of the substrate, and arranging them in a preset layout;

[0052] Step 3: Form corresponding PAD metal layers on the two first interdigital electrodes to form an input transducer and an output transducer; the material of the PAD metal layer can be common metals such as Ti, Cr, Ni, etc.;

[0053] Step 4: Use the evaporation process to form a metal coating in the deep hole below the PAD metal layer. The operation is as follows:

[0054] The workpiece with the PAD metal layer is placed in an evaporation device. By controlling the temperature and pressure of the evaporation device, metal atoms are deposited in the deep holes below the PAD metal layer, forming a metal coating between the bottom end of the interdigital electrode lead-out portion and the deep holes. The temperature is controlled at 200-300°C, the pressure is controlled at 1-5 Pa, and the evaporation time is controlled at 1-2 hours.

[0055] Step 5: Use etching process to process the deep hole. The operation is as follows:

[0056] The workpiece after step 4 is placed in an etching device. By controlling the temperature and voltage of the etching device, the etching liquid etches the deep hole to a predetermined size and shape. The purpose of etching is to carve open the evaporated hole to facilitate metal filling. The temperature is controlled at 50-80°C, the voltage is controlled at 10-30V, and the etching time is controlled at 30-60 minutes.

[0057] Step 6: Fill the deep hole with metal. The specific steps are as follows:

[0058] Place the workpiece that has completed step five in a metal filling device. By controlling the temperature and pressure of the metal filling device, metal atoms are deposited again inside the deep hole until the deep hole is completely filled. The temperature is controlled at 200-300°C, the pressure is controlled at 1-5Pa, and the filling time is controlled at 1-2 hours.

[0059] In this embodiment, the PAD metal layer is used to conduct signals, and the deep hole below the interdigital electrode lead-out portion can enhance the anti-ESD capability of the surface acoustic wave filter product, allowing static electricity to be conducted downward through the substrate, preventing the current generated by static electricity from breaking down at the location of the dummy gap. The metal used in step six is ​​silver, because silver has good electrical conductivity and antistatic ability. Through the above steps, the antistatic ability of the surface acoustic wave filter can be effectively improved while maintaining the stability of other properties.

[0060] Improving the antistatic capabilities of surface acoustic wave filters. In the field of surface acoustic wave filter manufacturing, the present invention improves existing evaporation and etching processes to form deep holes of a predetermined shape and size within the PAD metal layer. These holes are then filled with metal, thereby enhancing the antistatic capabilities of the surface acoustic wave filter. This method not only effectively improves the antistatic capabilities of the surface acoustic wave filter, but also reduces manufacturing costs, improves production efficiency, and ensures production stability and product quality.

[0061] In the field of microelectronics manufacturing technology, the technical solution of the present invention can provide a new manufacturing process with a simple operation process, easy to control, and can effectively improve the performance of surface acoustic wave filters.

[0062] In the field of materials science, the technical solution of the present invention can provide a new way of using metal materials, which will promote the development of the field of materials science and promote the development and application of new materials.

[0063] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. A surface acoustic wave filter, characterized in that: include: substrate; Two first interdigital electrodes are symmetrically arranged on the substrate, each of the first interdigital electrodes is a strip structure with a predetermined width and length, a first lead portion is provided in the middle of the first interdigital electrodes, extending beyond the upper and lower surfaces of the first interdigital electrodes, the first lead portion is parallel to the long side direction of the first interdigital electrodes and has the same length as the long side direction of the first interdigital electrodes, a deep hole is provided in the substrate that matches the shape of the bottom end of the first lead portion, and a metal plating layer is provided between the first lead portion and the deep hole; a plurality of second interdigital electrodes, arranged in parallel between the two first interdigital electrodes; The input transducer and the output transducer are respectively arranged on the first interdigital electrodes, which are PAD metal layers for connecting to external electrical signals.

2. A surface acoustic wave filter according to claim 1, characterized in that: A second lead portion is provided below at least one interdigital electrode, and the second lead portion extends downward into a preset depth of the substrate. A deep hole matching the shape of the bottom end of the second lead portion is provided on the substrate, and a metal plating layer is provided between the second lead portion and the deep hole.

3. A surface acoustic wave filter according to claim 2, characterized in that: Metal plating layers are provided between the first lead-out portion, the second lead-out portion and the corresponding deep holes. The metal plating layers are made of silver, and the PAD metal layer is made of Ti, Cr or Ni.

4. The surface acoustic wave filter according to claim 2, wherein: The surface acoustic wave filter further comprises: a first passivation layer covering the surfaces of the second interdigital electrodes, the input transducer, the output transducer, and the surface of the first interdigital electrodes extending out of the PAD metal layer; The second passivation layer is arranged between the first lead-out portion and the PAD metal layer.

5. A surface acoustic wave filter according to claim 4, characterized in that: The depth of the deep hole is 1 / 3 of the thickness of the substrate.

6. A method for preparing a surface acoustic wave filter, comprising preparing the surface acoustic wave filter according to claim 1, characterized in that: The method comprises the following steps: Step 1: Select a substrate material and open deep holes of a predetermined number and shape at predetermined positions of the substrate material; Step 2: fabricating two first interdigital electrodes, a first lead portion, and a plurality of second interdigital electrodes on the upper surface of the substrate and arranging them in a preset layout; Step 3: fabricate corresponding PAD metal layers on the two first interdigital electrodes to form an input transducer and an output transducer; Step 4: Use the evaporation process to form a metal coating in the deep hole below the PAD metal layer. The operation is as follows: The workpiece with the PAD metal layer is placed in an evaporation device. By controlling the temperature and pressure of the evaporation device, metal atoms are deposited in the deep hole below the PAD metal layer, so that a metal coating is formed between the bottom end of the first lead-out portion and the deep hole. Step 5: Use etching process to process the deep hole. The operation is as follows: The workpiece after step 4 is placed in an etching device, and the temperature and voltage of the etching device are controlled so that the etching liquid etches the deep hole to improve the size and shape of the deep hole; Step 6: Fill the deep hole with metal. The specific steps are as follows: The workpiece that has completed step five is placed in a metal filling device. By controlling the temperature and pressure of the metal filling device, metal atoms are deposited again inside the deep hole until the deep hole is completely filled.

7. The method for preparing a surface acoustic wave filter according to claim 6, wherein: In the step 4, the temperature in the evaporation equipment is controlled at 200-300° C., the pressure is controlled at 1-5 Pa, and the evaporation is performed for 1-2 hours.

8. The method for preparing a surface acoustic wave filter according to claim 6, wherein: In the step 5, the temperature of the etching equipment is controlled at 50-80° C., the voltage is controlled at 10-30 V, and the etching is performed for 30-60 minutes, so that the etching solution corrodes the deep hole to a predetermined size and shape.

9. The method for preparing a surface acoustic wave filter according to claim 6, wherein: In step six, the temperature of the metal filling equipment is controlled at 200-300° C., the pressure is controlled at 1-5 Pa, and the filling is carried out for 1-2 hours.

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