Surface acoustic wave filter and preparation method thereof

Abstract

The invention discloses a surface acoustic wave filter and a preparation method thereof, 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, the middle part of each first interdigital electrode is provided with a first lead-out part, and the middle part of each second interdigital electrode is provided with a second lead-out part; the substrate is provided with a deep hole matched with the bottom end of the first lead-out part in shape, and a metal coating is arranged between the first lead-out part and the deep hole. The surface acoustic wave filter designed by the invention has relatively high antistatic capacity, and can be prepared by process means such as evaporation, etching and metal filling, so that the manufacturing cost is reduced.

Description

Technical Field

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

[0002] Surface acoustic wave filter is a device that uses the characteristics of surface acoustic wave to filter signals. It has the advantages of small size, light weight, low cost, high reliability, and easy integration. It is widely used in various electronic devices such as mobile communications, satellite communications, radar systems, and navigation systems. With the development of microelectronics manufacturing technology and the continuous improvement of the integration and complexity of electronic equipment, the manufacturing process of surface acoustic wave filters has become more and more complicated, and the manufacturing process and performance requirements of surface acoustic wave filters have become higher and higher, among which antistatic ability is one of the key performances.

[0003] In the existing technology, the main method to improve the antistatic ability of the surface acoustic wave filter is to form deep holes inside the PAD metal layer and then fill these deep holes with metal. This method can effectively improve the antistatic ability of the surface acoustic wave filter, but it requires the use of complex evaporation and etching processes, with high manufacturing costs, low production efficiency, and prone to process failures, affecting production stability and product quality.

[0004] In addition, while the existing technology improves the anti-static ability of the surface acoustic wave filter, it may affect other performances, such as filtering performance, frequency selectivity, etc., which limits its application in certain high-performance fields. Summary of the invention

[0005] Technical purpose: In view of 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 market competitiveness of enterprises.

[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 exceeds the upper surface and the lower surface 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, a deep hole matching the shape of the bottom end of the first lead portion is provided on the substrate, and a metal plating layer is provided between the first lead portion and the deep hole;

[0010] A plurality of second interdigital electrodes are 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 realizing connection 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 covers 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 with a predetermined number and shape at a preset position of the substrate material;

[0020] Step 2: manufacturing two first interdigital electrodes, a first lead-out 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: respectively fabricating corresponding PAD metal layers on the two first interdigitated electrodes to form an input transducer and an output transducer;

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

[0023] Placing the workpiece with the PAD metal layer in an evaporation device, and depositing metal atoms in the deep hole below the PAD metal layer by controlling the temperature and pressure of the evaporation device, so that a metal coating layer 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 corrodes 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 after step five is placed in a metal filling device, and the temperature and pressure of the metal filling device are controlled to allow metal atoms to be 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 is performed for 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 method, which can reduce manufacturing costs, improve production efficiency and enhance the market competitiveness of enterprises.

[0033] 2) Improving 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: The present invention can improve the antistatic ability while maintaining the stability of other properties by improving the process means, thereby expanding its application range in the high-performance field. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of a surface acoustic wave filter in Embodiment 1;

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

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

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

[0039] Embodiment 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, and 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 and exceeds the upper surface and the lower surface 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. 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 upper surface of the first lead-out portion 5 and the first interdigitated electrode 2 is a3, the length of the common edge of the lower surface of the first lead-out portion 5 and the first interdigitated electrode 2 is a1, and the width of the first interdigitated electrode is a2, and there is a relationship: a1 / a2=1 / 5, a3 / a1=1 / 3, and 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 two first interdigital electrodes 2, two ends of each second interdigital electrode are respectively connected to the closer 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, and the PAD metal layer 4 for connecting to the external electrical signal is symmetrical on the left and right sides;

[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-out portions 6 are provided below one of the second interdigital electrodes 3, the second lead-out portions 6 extend downward into a preset depth of the substrate, a deep hole matching the shape of the bottom end of the second lead-out portion 6 is provided on the substrate 1, and a metal plating layer is provided between the second lead-out portion 6 and the deep hole. The top edge width b1 of the second lead-out portion 6 and the distance b2 between the two second lead-out portions 6 are in the relationship of b1 / b2=1 / 5-1 / 10.

[0048] Embodiment 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 with a predetermined number and shape at a preset position of the substrate material, wherein the depth of the deep holes is about 1 / 3 of the thickness of the substrate;

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

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

[0053] Step 4: Use an 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, and the temperature and pressure of the evaporation device are controlled to deposit metal atoms in the deep holes below the PAD metal layer, so that a metal coating layer is formed between the bottom end of the interdigital electrode lead-out portion and the deep holes, wherein 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, and the temperature and voltage of the etching device are controlled so that the etching liquid etches the deep hole to a predetermined size and shape. The purpose of etching is to carve the evaporated hole to facilitate metal filling; wherein 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, and by controlling the temperature and pressure of the metal filling device, allow metal atoms to be deposited again inside the deep hole until the deep hole is completely filled, wherein 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, so that static electricity is conducted downward in the direction of the substrate, and the current generated by static electricity is prevented from breaking down at the position of the dummygap. 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 ability of surface acoustic wave filters In the field of surface acoustic wave filter manufacturing, the technical solution of the present invention can form deep holes of predetermined shape and size inside the PAD metal layer by improving the existing evaporation and etching processes, and then fill these holes with metal, thereby improving the antistatic ability of the surface acoustic wave filter. This method can not only effectively improve the antistatic ability of the surface acoustic wave filter, but also reduce manufacturing costs, improve production efficiency, and ensure production stability and product quality.

[0061] In the field of microelectronic manufacturing technology, the technical solution of the present invention can provide a new manufacturing process, which has a simple operation process and is 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 solution obtained by equivalent replacement or equivalent transformation falls within the protection scope 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 interdigital electrode is a strip structure with a predetermined width and length, a first lead portion is provided in the middle portion and exceeds the upper surface and the lower surface 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, a deep hole matching the shape of the bottom end of the first lead portion is provided on the substrate, and a metal plating layer is provided between the first lead portion and the deep hole; A plurality of second interdigital electrodes are 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 realizing connection 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 interdigitated 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: 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.

4. A surface acoustic wave filter according to claim 2, characterized in that: The surface acoustic wave filter further comprises: A first passivation layer covers 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, characterized in that: The steps include: Step 1: Select a substrate material, and open deep holes with a predetermined number and shape at a preset position of the substrate material; Step 2: manufacturing two first interdigital electrodes, a first lead-out portion and a plurality of second interdigital electrodes on the upper surface of the substrate, and arranging them in a preset layout; Step 3: respectively fabricating corresponding PAD metal layers on the two first interdigitated electrodes to form an input transducer and an output transducer; Step 4: Use an evaporation process to form a metal coating in the deep hole below the PAD metal layer. The operation is as follows: Placing the workpiece with the PAD metal layer in an evaporation device, and depositing metal atoms in the deep hole below the PAD metal layer by controlling the temperature and pressure of the evaporation device, so that a metal coating layer 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 corrodes 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 after step five is placed in a metal filling device, and the temperature and pressure of the metal filling device are controlled to allow metal atoms to be 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, characterized in that: 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, characterized in that: In the step five, the temperature of the etching equipment is controlled at 50-80° C., the voltage is controlled at 10-30V, 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, characterized in that: 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 performed for 1-2 hours.

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