A glass substrate-based hybrid filter structure and a preparation process thereof

Abstract

A glass substrate-based hybrid filter structure includes a primary die and secondary and tertiary dies stacked on the sides of the primary die, the primary die including a glass substrate, a glass semiconductor device disposed on the glass substrate, and a glass via disposed within the glass substrate, the secondary die including a surface acoustic wave filter (SAW), and the tertiary die including a bulk acoustic wave filter (BAW), the SAW and the BAW being electrically connected to the glass semiconductor device by bumps. By configuring two acoustic filters into a single filter, the acoustic filter on one surface provides steep rejection at one frequency, while the acoustic filter on the other surface provides rejection at a different frequency, achieving a sharp filter roll-off and increased bandwidth, while the glass substrate provides superior material product reliability over silicon substrates and is suitable for high frequency applications, resulting in superior electrical performance.

Description

Technical Field

[0001] This invention belongs to the field of acoustic filter technology, specifically a hybrid filter structure based on a glass substrate and its fabrication process. Background Technology

[0002] With the rapid development of mobile communication, increasingly higher demands are being placed on acoustic filters. On the one hand, filters are required to have low insertion loss to improve the signal-to-noise ratio and reduce power consumption; on the other hand, filters are required to have a wide bandwidth. Narrow-bandwidth, low-insertion-loss filters are relatively mature, but wideband, low-insertion-loss filters are more difficult to design.

[0003] Using glass substrates as the main material, SAW filters offer superior reliability compared to silicon substrates and are suitable for high-frequency applications, achieving better electrical performance. SAW filters consist of a piezoelectric substrate and two interdigital transducers (IDTs). The frequency of the SAW is directly proportional to the speed and inversely proportional to the spacing of the IDT electrodes. Smaller spacing leads to higher current density, causing electromigration and heat generation. SAW filters are highly susceptible to temperature variations and are generally only suitable for applications below 1.5 GHz. BAW filters (with a resonator quality factor Q up to 5000) possess excellent characteristics such as low insertion loss, high out-of-band rejection, high isolation, and high power capacity (>30 dBm). BAW filters are suitable for high frequencies (with advantages above 1.5 GHz), and their size decreases with increasing frequency. They are insensitive to temperature changes and offer extremely low loss and steep filter rejection. A higher quality factor Q allows for a narrower passband bandwidth, achieving better selectivity, but also results in a relatively narrow passband for both types of filters. Summary of the Invention

[0004] 1. The technical problem that the invention aims to solve

[0005] The purpose of this invention is to mitigate the drawbacks associated with stand-alone passive (IPD) filters and acoustic filters. While narrow-bandwidth low-insertion-loss filters are relatively mature, wideband low-insertion-loss filters are more difficult to design.

[0006] 2. Technical Solution

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0008] The application discloses a glass substrate-based hybrid filter structure, which comprises a primary die and secondary and tertiary dies stacked on the side surfaces of the primary die, wherein the primary die comprises a glass substrate, a glass semiconductor device arranged on the glass substrate and a glass through hole arranged in the glass substrate, the secondary and tertiary dies are provided with a plurality of bumps on the side surfaces close to the primary die, the plurality of bumps are in conduction with the glass semiconductor device or the glass through hole, the secondary die comprises a surface acoustic wave filter (SAW) which is a low-pass filter, and the tertiary die comprises a bulk acoustic wave filter (BAW) which is a high-pass filter, and the surface acoustic wave filter (SAW) and the bulk acoustic wave filter (BAW) are in conduction with the glass semiconductor device through the bumps.

[0009] Preferably, the two side surfaces of the primary die are side surface one and side surface two, and the side surface one and the side surface two are both provided with a passivation layer.

[0010] Preferably, the glass substrate is stacked with the surface acoustic wave filter (SAW) and the bulk acoustic wave filter (BAW).

[0011] Preferably, the secondary and tertiary dies are both arranged on the side surface one or the secondary and tertiary dies are both arranged on the side surface two.

[0012] Preferably, the secondary and tertiary dies are stacked on the side surface one and the side surface two of the primary die respectively.

[0013] Preferably, the acoustic filter and the glass semiconductor device are overlapped with each other and separated by less than 100 um.

[0014] Preferably, the primary die is connected with the glass through hole (TGV) and a PCB carrier through ball planting.

[0015] Preferably, the glass through hole is filled with conductive material.

[0016] According to a preparation process of the glass substrate-based hybrid filter, a plurality of glass through holes are arranged in a glass substrate, a plurality of traces are deposited on the two side surfaces of the glass substrate and then covered with a passivation layer, the plurality of traces are in conduction with the plurality of glass through holes, an acoustic filter and a glass semiconductor device are stacked on the glass substrate and in conduction with the glass through hole, a surface acoustic wave filter (SAW) and a bulk acoustic wave filter (BAW) are stacked on the side surfaces of the glass substrate, and the surface acoustic wave filter (SAW) and the bulk acoustic wave filter (BAW) are in conduction with the glass semiconductor device through bumps.

[0017] 3. Beneficial effects

[0018] Compared with the prior art, the technical scheme provided by the application has the following beneficial effects:

[0019] The application discloses a glass substrate-based hybrid filter structure, which comprises a primary die, a secondary die and a tertiary die stacked on the side of the primary die, the primary die comprises a glass substrate, a glass semiconductor device arranged on the glass substrate and a glass via arranged in the glass substrate, the secondary die and the tertiary die are provided with a plurality of bumps on the side close to the primary die, the plurality of bumps are in conduction with the glass semiconductor device or the glass via, the secondary die comprises a surface acoustic wave filter (SAW) which is a low-pass filter, and the tertiary die comprises a bulk acoustic wave filter (BAW) which is a high-pass filter, the surface acoustic wave filter (SAW) and the bulk acoustic wave filter (BAW) are in conduction with the glass semiconductor device through the bumps, the two acoustic filters are constructed into a single filter, so that the acoustic filter on one surface provides steep suppression at one frequency, and the acoustic filter on the other surface provides suppression at different frequencies, sharp filter roll-off and increased bandwidth are realized, and meanwhile, the glass is used as a main substrate material, the reliability of the glass is excellent compared with that of a silicon substrate and other materials, the glass is suitable for high-frequency application, and better electrical performance is realized. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a structural schematic diagram of a glass substrate-based hybrid filter structure according to the application;

[0021] Figure 2 FIG. 2 is a top view of a glass substrate-based hybrid filter structure according to the application.

[0022] In the figure: 1, primary die; 11, side one; 12, side two; 2, secondary die; 3, tertiary die; 4, PCB carrier; 5, solder ball; 6, bump; 7, glass via; 8, passivation layer. DETAILED DESCRIPTION

[0023] In order to make the application more comprehensively understood, the application will be described in detail below with reference to the relevant drawings, and several embodiments of the application are shown in the drawings, but the application can be realized in many different forms, and is not limited to the embodiments described herein, on the contrary, the purpose of providing these embodiments is to make the disclosure of the application more thorough and comprehensive.

[0024] It should be noted that when an element is referred to as being "fixedly attached" to another element, it can be directly on the other element or there can be intervening elements; when an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be intervening elements; the terms "vertical", "horizontal", "left", "right", and similar expressions used herein are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Example 1

[0027] See attached document Figure 1 -Appendix Figure 2 This embodiment presents a hybrid filter structure based on a glass substrate, comprising a primary die 1 and secondary dies 2 and tertiary dies 3 stacked on the side of the primary die 1. The primary die 1 includes a glass substrate, a glass semiconductor device disposed on the glass substrate, and a glass via 7 disposed within the glass substrate. The secondary dies 2 and tertiary dies 3 have a plurality of bumps 6 on their sides adjacent to the primary die 1. The bumps 6 are conductive to the glass semiconductor device or to the glass via 7. The secondary die 2 includes a surface acoustic wave (SAW) filter, which is a low-pass filter. The tertiary die 3 includes a bulk acoustic wave (BAW) filter, which is a high-pass filter. The SAW and BAW filters are conductive to the glass semiconductor device through the bumps 6. The glass via 7 is filled with conductive material. By constructing two acoustic filters into a single filter, the acoustic filter on one surface provides steep suppression at one frequency, while the acoustic filter on the other surface provides suppression at different frequencies, achieving a sharp filter roll-off and increased bandwidth. Meanwhile, using glass as the main substrate material, it offers superior reliability compared to materials such as silicon substrates, making it suitable for high-frequency applications and achieving better electrical performance.

[0028] The primary die 1 has two sides, side 11 and side 2 12, both of which are provided with a passivation layer 8. Secondary dies 2 and tertiary dies 3 can be stacked simultaneously on the same side of the primary die 1, such as side 11 or side 2 12. Alternatively, secondary dies 2 and tertiary dies 3 can be stacked on side 11 and side 2 12 of the primary die 1, respectively. The primary die 1 is connected to the glass via 7 and the PCB substrate 4 via ball bearings 5.

[0029] The acoustic filter SAW and BAW are also stacked on the glass substrate, and the acoustic filter and the glass semiconductor device are stacked and spaced apart from each other by less than 100 um, which can reduce the parasitic effect, reduce the loss, and improve the design complexity of realizing carrier aggregation in a mobile RF transceiver. A preparation process of a hybrid filter based on a glass substrate, a plurality of glass vias 7 are arranged in the glass substrate, a passivation layer 8 is deposited on the two side surfaces of the glass substrate after a plurality of traces are deposited, the plurality of traces are in conduction with the plurality of glass vias 7, the acoustic filter and the glass semiconductor device are stacked on the glass substrate and are in conduction with the glass vias 7, the surface acoustic wave filter SAW stacked on the side surface of the glass substrate can be a low-pass filter, and the bulk acoustic wave filter BAW can be a high-pass filter, and the surface acoustic wave filter SAW and the bulk acoustic wave filter BAW are in conduction with the glass semiconductor device through the bump 6.

[0030] The above-described embodiments only express certain implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application; it should be pointed out that, for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application; therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A glass substrate based hybrid filter structure, characterized by: The first-level die (1) and the second-level die (2) and the third-level die (3) stacked on the side of the first-level die (1), the first-level die (1) comprising a glass substrate, a glass semiconductor device disposed on the glass substrate, a glass via (7) disposed in the glass substrate, the second-level die (2) and the third-level die (3) being provided with a plurality of bumps (6) on the side close to the first-level die (1), the plurality of bumps (6) being in conduction with the glass semiconductor device or the glass via (7), the second-level die (2) comprising a surface acoustic wave filter SAW, the surface acoustic wave filter SAW being a low-pass filter, the third-level die (3) comprising a bulk acoustic wave filter, the bulk acoustic wave filter being a high-pass filter, the surface acoustic wave filter SAW and the bulk acoustic wave filter BAW being in conduction with the glass semiconductor device through the bumps (6); The two sides of the first-level die (1) are side one (11) and side two (12), the side one (11) and the side two (12) are provided with a passivation layer (8); the glass substrate is stacked with a surface acoustic wave filter SAW and a bulk acoustic wave filter BAW; the acoustic filter and the glass semiconductor device are stacked and separated by less than 100um; The acoustic filter is a surface acoustic wave filter SAW and a bulk acoustic wave filter BAW stacked on the glass substrate.

2. The glass substrate-based hybrid filter structure of claim 1, wherein: The second-level die (2) and the third-level die (3) are both disposed on the side one (11) or the second-level die (2) and the third-level die (3) are both disposed on the side two (12).

3. The glass substrate-based hybrid filter structure of claim 1, wherein: The second-level die (2) and the third-level die (3) are stacked on the side one (11) and the side two (12) of the first-level die (1) respectively.

4. The hybrid filter structure based on glass substrate according to any one of claims 1-3, characterized in that: The first-level die (1) is connected with the glass via (7) and the PCB carrier plate (4) through the ball (5).

5. The glass substrate-based hybrid filter structure of claim 4, wherein: The glass via (7) is filled with conductive material.

6. A process for the preparation of a glass substrate based hybrid filter, characterized in that: A plurality of glass vias (7) are provided in the glass substrate, a plurality of traces are deposited on the two sides of the glass substrate and covered with a passivation layer (8), a plurality of traces are in conduction with a plurality of glass vias (7), an acoustic filter and a glass semiconductor device are stacked on the glass substrate and in conduction with the glass via (7), a surface acoustic wave filter SAW and a bulk acoustic wave filter BAW are stacked on the side of the glass substrate, the surface acoustic wave filter SAW and the bulk acoustic wave filter BAW are in conduction with the glass semiconductor device through the bumps (6); the acoustic filter and the glass semiconductor device are stacked and separated by less than 100um; The acoustic filter is a surface acoustic wave filter SAW and a bulk acoustic wave filter BAW stacked on the glass substrate.

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