A high performance coupled filter and its preparation method

Abstract

The present invention provides a high-performance coupled filter and a method for fabricating it, relating to the field of filter technology. The fabrication method comprises providing a substrate; depositing an insulating layer on the substrate, then machining groove groups on the front and back sides of the substrate, the groove groups comprising multiple grooves, and machining a through-hole at one end of the substrate, with both ends of the through-hole extending through the front and back sides of the substrate, respectively; forming a metal filling layer within the grooves, a metal connecting column within the through-hole, and a metal electroplating layer on the front and back sides of the substrate through an electroplating process; removing the metal electroplating layer through a chemical mechanical polishing process; and forming a dielectric passivation layer on the front and back sides of the substrate, respectively. In the present invention, a coil is combined with substrate backside rewiring technology and substrate groove technology to achieve high aspect ratio routing while simultaneously achieving a narrow line pitch, thereby enhancing coil coupling and reducing routing loss, thereby achieving better filter performance.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to a high-performance coupling filter and a preparation method thereof. Background Art

[0002] The rapid adoption of portable electronic products, wearable smart devices, and systems has sparked significant interest in miniaturization and integration of various product modules and components within both industry and academia. Transmission protocols within communication systems can include single-ended signaling, differential signaling, or a combination of single-ended and differential signaling. For example, single-ended signaling is suitable for low-speed data transmission systems; however, high-speed data transmission systems require differential signaling, which offers better noise immunity. These systems include mobile electronic devices such as smartphones, tablets, computers, and systems incorporating Universal Serial Bus (USB) applications. In addition to noise immunity, protection against large transient voltage and current spikes that can damage these systems is also desirable. Noise filters (including common-mode filters (CMFs)) and electrostatic discharge (ESD) protection circuits are mounted on printed circuit boards (PCBs) along with other communication system circuitry to reduce common-mode noise on differential signal lines and suppress large transient current spikes, respectively. However, this component configuration consumes significant PCB real estate, which is disadvantageous in mobile electronic products. In addition, ESD protection circuits are made of low-resistivity substrates to accommodate the high currents encountered during ESD events; however, eddy currents exist on low-resistivity substrates that can degrade filtering performance, making it undesirable to manufacture filtering components such as inductors on low-resistivity substrates.

[0003] The process of developing a variety of integrated miniaturized common-mode filters is to utilize a back-end process on a silicon wafer, through copper electroplating and dielectric layer coating stacking. The line spacing controls the coupling between single-layer coils. Under the same conditions, it is hoped that the coil can achieve a larger thickness and the smaller the line width and line spacing, the better. However, due to the limitations of the electroplating process, existing filters can usually only achieve a trace thickness / line width / spacing ratio of approximately 1:1:1, and the trace resistance loss is relatively high. Summary of the Invention

[0004] The present invention provides a high-performance coupled filter and a preparation method thereof, which are used to solve the technical problem that existing filters can usually only achieve a wiring thickness / line width / spacing ratio of about 1:1:1 and have high wiring resistance loss.

[0005] To solve the above technical problems, the present invention discloses a method for preparing a high-performance coupled filter, comprising the following steps:

[0006] Step 1: providing a substrate;

[0007] Step 2: Depositing an insulating layer on the substrate, and then processing groove groups on the front and back sides of the substrate, the groove groups including multiple grooves, and processing a through hole at one end of the substrate, with both ends of the through hole passing through the front and back sides of the substrate respectively;

[0008] Step 3: forming a metal filling layer in the groove, a metal connecting column in the through hole, and a metal electroplating layer on the front and back sides of the substrate respectively through an electroplating process;

[0009] Step 4: Remove the metal plating layer through chemical mechanical polishing process;

[0010] Step 5: Form a dielectric passivation layer on the front side and the back side of the substrate respectively.

[0011] Preferably, in step 1, the substrate material is at least one of silicon, silicon carbide, germanium, gallium arsenide or other Group III / V compound semiconductors.

[0012] Preferably, in step 2, the insulating layer is made of insulating material.

[0013] Preferably, in step 2, the groove aspect ratio is greater than or equal to 2 and less than or equal to 30.

[0014] Preferably, in step 2, the plurality of grooves are arranged at equal intervals along the length direction of the substrate.

[0015] Preferably, in step 2, the groove group on the front side of the substrate and the groove group on the back side of the substrate are arranged symmetrically.

[0016] Preferably, in step 3, the formation of the metal connecting pillars includes the following steps:

[0017] Step 301: First, a metal seed layer is sputtered around the through hole on the front side of the substrate. Then, the front side of the substrate is electroplated by an electroplating process to form a metal filling layer in the groove on the front side of the substrate. At the same time, a sealing layer is formed between the metal seed layers. The sealing layer is used to seal the through hole on the front side of the substrate.

[0018] Step 302: Turning over the substrate so that the back side of the substrate faces upward;

[0019] Step 303: a metal filling layer is formed in the groove on the back side of the substrate through an electroplating process. At the same time, electroplated metal is filled into the through hole from the through hole on the back side of the substrate. The electroplated metal fills the through hole to form a metal connecting column.

[0020] Preferably, in step 5, a first connection hole is opened on the dielectric passivation layer, and one end of the first connection hole extends to the surface of the metal filling layer.

[0021] Preferably, in step 5, a metal routing layer is first set on the front and back sides of the substrate, and the metal routing layer is connected to the metal filling layer and the metal connecting column respectively, and then a second connecting hole is opened on the dielectric passivation layer, and one end of the second connecting hole extends to the surface of the metal routing layer.

[0022] The present application also provides a high-performance coupled filter, which is prepared using the above-mentioned preparation method, including a substrate, a plurality of grooves symmetrically arranged inside the front and back sides of the substrate, a metal filling layer arranged in the grooves, a through hole arranged at one end of the substrate, a metal connecting column arranged in the through hole, and a dielectric passivation layer arranged on the front and back sides of the substrate.

[0023] The technical solution of the present invention has the following advantages: The present invention provides a high-performance coupled filter and a preparation method, which relates to the field of filter technology. The preparation method includes providing a substrate; depositing an insulating layer on the substrate, then machining a groove group on the front and back sides of the substrate, the groove group including multiple grooves, and machining a through hole on one end of the substrate, with both ends of the through hole extending through the front and back sides of the substrate respectively; forming a metal filling layer in the groove, a metal connecting column in the through hole, and a metal electroplating layer on the front and back sides of the substrate respectively through an electroplating process; removing the metal electroplating layer through a chemical mechanical polishing process and polishing the metal electroplating layer flat to the substrate surface. This method can achieve a high aspect ratio t / w, as well as a small line width w and a small line spacing s. Among them, a general deep silicon etching process can achieve a structure with an aspect ratio of up to 30:1, which fully meets the structural requirements; and forming a dielectric passivation layer on the front and back sides of the substrate. In the present invention, the coil is combined with the substrate backside rewiring technology and the substrate groove technology to achieve a high aspect ratio routing and a narrow line spacing, thereby enhancing the coupling of the coil and reducing the routing loss, thereby achieving better performance of the filter.

[0024] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the devices particularly pointed out in the written description and the accompanying drawings.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 This is a schematic diagram of the steps of a method for preparing a high-performance coupled filter according to the present invention;

[0028] Figure 2Schematic diagram of the existing filter structure;

[0029] Figure 3 Schematic diagram of the substrate structure in the present invention;

[0030] Figure 4 Schematic diagram of the groove and through-hole structure in the present invention;

[0031] Figure 5 Schematic diagram of the structure of the metal filling layer, metal connecting column and metal electroplating layer in the present invention;

[0032] Figure 6 This is a schematic diagram of the structure of the substrate after being processed by a chemical mechanical polishing process in the present invention;

[0033] Figure 7 A schematic structural diagram of a high-performance coupling filter in the present invention;

[0034] Figure 8 Schematic diagram of another structure of the high performance coupling filter in the present invention;

[0035] Figure 9 Schematic diagram of a metal seed layer during the formation of a metal connecting column of the present invention;

[0036] Figure 10 Schematic diagram of the sealing layer during the formation of the metal connecting column of the present invention;

[0037] Figure 11 Schematic diagram of flipping the substrate during the formation of the metal connecting column of the present invention;

[0038] Figure 12 Schematic diagram of the formation of metal connecting pillars in the present invention.

[0039] In the figure: 1. substrate; 2. groove; 3. through hole; 4. metal filling layer; 5. metal connecting column; 6. metal electroplating layer; 7. dielectric passivation layer; 8. metal seed layer; 9. sealing layer; 10. first connecting hole; 11. metal routing layer; 12. second connecting hole. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0041] In addition, in the present invention, descriptions such as "first" and "second" are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions and technical features between the various embodiments can be combined with each other, but this must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] Example 1

[0043] The embodiment of the present invention provides a method for preparing a high performance coupled filter. Figures 1-12 As shown, the following steps are included:

[0044] Step 1: providing a substrate 1;

[0045] Step 2: Depositing an insulating layer on the substrate 1, and then processing two groups of grooves on the front and back of the substrate 1, respectively. The groove group 2 includes multiple grooves 2, and processing a through hole 3 at one end of the substrate 1. The two ends of the through hole 3 pass through the front and back of the substrate 1 respectively;

[0046] Step 3: forming a metal filling layer 4 in the groove 2, a metal connecting column 5 in the through hole 3, and a metal electroplating layer 6 on the front and back sides of the substrate 1 respectively through an electroplating process;

[0047] Step 4: removing the metal plating layer 6 by a chemical mechanical polishing process;

[0048] Step 5: forming a dielectric passivation layer 7 on the front surface and the back surface of the substrate 1 respectively.

[0049] The working principle and beneficial effects of the above technical solution are as follows: a process for an integrated common mode filter is to use a back-end process on a silicon wafer to achieve it by electroplating copper and laminating a dielectric layer, such as Figure 2As shown, the common winding copper coil is about 5um thick, and the line width and spacing is also 5um, or even greater than 5um. It can be seen that the existing filter can usually only achieve a wiring thickness / line width / spacing of about 1:1:1, and the wiring resistance loss is relatively high. In order to reduce the wiring resistance loss and enhance the coupling of the coil, the present application provides a high-performance coupling filter preparation method, comprising the following steps: first providing a substrate 1, then depositing an insulating layer on the substrate 1, and then processing 2 groups of grooves on the front and back sides of the substrate 1, respectively. The groove 2 group includes a plurality of grooves 2. Preferably, the groove 2 has a depth of 10μm and a spacing between the grooves 2 is 2μm, thereby improving the aspect ratio of the groove 2 and reducing the spacing between the grooves 2, and processing a through hole 3 at one end of the substrate 1, and the through hole 3 is divided into two ends. The invention relates to a method for forming a first-layer circuit of the first substrate 1 and a second-layer circuit of the first substrate 1 on the front and back of the substrate 1. The first-layer circuit of the first substrate 1 and the second-layer circuit of the second substrate 1 on the back of the substrate 1 are connected to each other through the MEMS process ...

[0050] Example 2

[0051] On the basis of the above-mentioned embodiment 1, in step 1, the substrate 1 is made of at least one material selected from silicon, silicon carbide, germanium, gallium arsenide or other Group III / V compound semiconductors.

[0052] The working principle and beneficial effects of the above technical solution are as follows: the substrate 1 can have high resistance characteristics or low resistance characteristics. In order to improve the radio frequency performance, a high resistance silicon substrate 1 is often used.

[0053] Example 3

[0054] Based on embodiment 1 or 2, in step 2, the insulating layer is made of an insulating material;

[0055] The aspect ratio of groove 2 is greater than or equal to 2 and less than or equal to 30;

[0056] A plurality of grooves 2 are arranged at equal intervals along the length direction of the substrate 1;

[0057] The two groups of grooves on the front surface of the substrate 1 are symmetrically arranged with the two groups of grooves on the back surface of the substrate 1 .

[0058] The working principle and beneficial effects of the above technical solution are as follows: a layer of insulating material is deposited on the substrate 1 to form an insulating layer, which is used as a mask for etching the substrate 1, or a photoresist film is used to form a groove 2 with a high aspect ratio in the substrate 1 through deep silicon etching and other processes. The groove 2 has a thickness of 10 μm and a spacing of 2 μm. The grooves 2 etched on the front and back sides of the substrate 1 are used for routing to achieve routing with a high aspect ratio. Multiple grooves 2 are arranged at equal intervals and have a spacing of 2 μm, which is smaller than the existing 5 μm spacing, further achieving a narrower line pitch, enhancing the coupling of the coil and reducing the loss of the routing, so that the filter can achieve better performance.

[0059] Example 4

[0060] On the basis of any one of Examples 1-3, Figures 9-12 As shown, in step 3, the formation of the metal connecting column 5 includes the following steps:

[0061] Step 301: First, a metal seed layer 8 is sputtered around the through hole 3 on the front surface of the substrate 1. Then, the front surface of the substrate 1 is electroplated by an electroplating process to form a metal filling layer 4 in the groove 2 on the front surface of the substrate 1. At the same time, a sealing layer 9 is formed between the metal seed layers 8. The sealing layer 9 is used to seal the through hole 3 on the front surface of the substrate 1.

[0062] Step 302: Turn over the substrate 1 so that the back side of the substrate 1 faces upward;

[0063] Step 303: A metal filling layer 4 is formed in the groove 2 on the back side of the substrate 1 through an electroplating process. At the same time, electroplated metal is filled from the through hole 3 on the back side of the substrate 1 into the through hole 3. The electroplated metal fills the through hole 3 to form a metal connecting column 5.

[0064] The working principle and beneficial effects of the above technical scheme are as follows: when preparing the metal connecting column 5, the front side of the substrate 1 is first placed facing upward, and a metal seed layer 8 is sputtered on the outer periphery of the upper end of the through hole 3 on the front side of the substrate 1, and then the front side of the substrate 1 is electroplated by an electroplating process, and the electroplated metal forms a metal filling layer 4 in the groove 2 on the front side of the substrate 1. At the same time, the electroplated metal forms a sealing layer 9 between the metal seed layer 8, and the sealing layer 9 can seal the through hole 3 on the front side of the substrate 1; after the metal electroplating layer 6 on the front side of the substrate 1 is formed, the substrate 1 is turned over so that the back side of the substrate 1 faces upward; then the back side of the substrate 1 is treated by an electroplating process, and the electroplated metal fills the groove 2, and forms a metal filling layer 4 in the groove 2 on the back side of the substrate 1. At the same time, the electroplated metal is filled from the through hole 3 on the back side of the substrate 1 into the through hole 3, and the electroplated metal fills the through hole 3 to form a metal connecting column 5. Through the above scheme, the voids generated inside the through hole 3 during the electroplating process can be reduced, thereby reducing the pore defects generated during the formation process of the metal connecting column 5, improving the preparation quality of the metal connecting column 5, and enhancing the performance of the metal connecting column 5.

[0065] Example 5

[0066] On the basis of any one of Examples 1-4, Figure 7 As shown, in step 5, a first connection hole 10 is opened on the dielectric passivation layer 7, and one end of the first connection hole 10 extends to the surface of the metal filling layer 4.

[0067] The working principle and beneficial effects of the above technical solution are as follows: after forming the dielectric passivation layer 7, a first connection hole 10 is opened at the position where the signal needs to be connected in the dielectric passivation layer 7, thereby exposing the signal pad, which is convenient for external connection with the metal filling layer 4 or the metal connection column 5. The coil signals on both sides can go through the external signal connection, or be connected through the metal connection column 5 in the through hole 3 of the substrate 1, and the signal line of the upper and lower coupled coils is formed with the help of the packaged connection.

[0068] Example 6

[0069] On the basis of any one of Examples 1-4, Figure 8 As shown, in step 5, a metal routing layer 11 is first set on the front side and the back side of the substrate 1, and the metal routing layer 11 is connected to the metal filling layer 4 and the metal connecting column 5 respectively, and then a second connecting hole 12 is opened on the dielectric passivation layer 7, and one end of the second connecting hole 12 extends to the surface of the metal routing layer 11.

[0070] The working principle and beneficial effects of the above technical solution are as follows: before forming the dielectric passivation layer 7, a metal routing layer 11 is first produced on the front and back sides of the substrate 1. The metal routing layer 11 is connected to the metal filling layer 4 and the metal connecting column 5 respectively. The metal routing layer 11 is made of metal copper. Then, the dielectric passivation layer 7 is formed, and a second connection hole 12 is opened on the dielectric passivation layer 7. It is connected to the metal routing layer 11 through an external connection to achieve interconnection with other devices.

[0071] The present application also provides a high performance coupling filter, which is prepared by the above preparation method, such as Figure 7 or Figure 8 As shown, it includes a substrate 1, a plurality of grooves 2 are symmetrically arranged inside the front and back sides of the substrate 1, a metal filling layer 4 is arranged in the groove 2, a through hole 3 is arranged at one end of the substrate 1, a metal connecting column 5 is arranged in the through hole 3, and a dielectric passivation layer 7 is arranged on the front and back sides of the substrate 1.

[0072] The filter achieves high aspect ratio routing and narrow line spacing, thereby enhancing the coupling of the coils and reducing routing loss, thereby improving the performance of the filter.

[0073] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0074] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0075] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a high-performance coupled filter, characterized in that: The following steps are involved: Step 1: providing a substrate (1); Step 2: depositing an insulating layer on the substrate (1), and then processing groove (2) groups on the front and back sides of the substrate (1), respectively, wherein the groove (2) group includes a plurality of grooves (2), the plurality of grooves (2) are arranged along the length direction of the substrate (1), and processing a through hole (3) at one end of the substrate (1), wherein both ends of the through hole (3) respectively penetrate the front side of the substrate (1) and the back side of the substrate (1); Step 3: forming a metal filling layer (4) in all the grooves (2), forming a metal connecting column (5) in the through hole (3), and forming a metal electroplating layer (6) on the front and back of the substrate (1) through an electroplating process, wherein the metal electroplating layer (6) covers the metal filling layer (4) and the metal connecting column (5); Step 4: removing the metal plating layer (6) by chemical mechanical polishing process; Step 5: forming a dielectric passivation layer (7) on the front side of the substrate (1) and the back side of the substrate (1) respectively.

2. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 1, the substrate (1) is made of at least one material selected from silicon, silicon carbide, germanium, gallium arsenide or other III / V group compound semiconductors.

3. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 2, the insulating layer is made of an insulating material.

4. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 2, the aspect ratio of the groove (2) is greater than or equal to 2 and less than or equal to 30.

5. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 2, a plurality of grooves (2) are arranged at equal intervals along the length direction of the substrate (1).

6. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 2, the groove (2) group on the front side of the substrate (1) and the groove (2) group on the back side of the substrate (1) are arranged symmetrically.

7. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 3, the formation of the metal connecting pillar (5) includes the following steps: Step 301: first, a metal seed layer (8) is sputtered on the periphery of the through hole (3) on the front surface of the substrate (1), and then the front surface of the substrate (1) is electroplated by an electroplating process to form a metal filling layer (4) in all the grooves (2) on the front surface of the substrate (1). At the same time, a sealing layer (9) is formed between the metal seed layers (8), and the sealing layer (9) is used to seal the through hole (3) on the front surface of the substrate (1); Step 302: turning over the substrate (1) so that the back side of the substrate (1) faces upward; Step 303: A metal filling layer (4) is formed in all the grooves (2) on the back side of the substrate (1) through an electroplating process. At the same time, the electroplated metal is filled from the through hole (3) on the back side of the substrate (1) into the through hole (3). The electroplated metal fills the through hole (3) to form a metal connecting column (5).

8. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 5, a first connection hole (10) is opened on the dielectric passivation layer (7), and one end of the first connection hole (10) extends to the surface of the metal filling layer (4).

9. The method for preparing a high-performance coupled filter according to claim 1, wherein: In step 5, a metal wiring layer (11) is first provided on the front surface of the substrate (1) and the back surface of the substrate (1), and the metal wiring layer (11) is connected to the metal filling layer (4) and the metal connection column (5) respectively. Then, a second connection hole (12) is opened on the dielectric passivation layer (7), and one end of the second connection hole (12) extends to the surface of the metal wiring layer (11).

10. A high-performance coupling filter, prepared by the method for preparing a high-performance coupling filter according to any one of claims 1 to 9, characterized in that: The high-performance coupling filter includes a substrate (1), a plurality of grooves (2) are symmetrically arranged inside the front and back surfaces of the substrate (1), the plurality of grooves (2) are arranged along the length direction of the substrate (1), a metal filling layer (4) is arranged in the groove (2), a through hole (3) is arranged at one end of the substrate (1), a metal connecting column (5) is arranged in the through hole (3), and a dielectric passivation layer (7) is arranged on the front and back surfaces of the substrate (1).

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