WO2021093408A1

WO2021093408A1 - Duplexer

Info

Publication number: WO2021093408A1
Application number: PCT/CN2020/111351
Authority: WO
Inventors: 庞慰; 郑云卓
Original assignee: 天津大学; 诺思(天津)微系统有限责任公司
Priority date: 2019-11-15
Filing date: 2020-08-26
Publication date: 2021-05-20
Also published as: CN111082190A; CN111082190B

Abstract

Provided is a duplexer, sequentially comprising, from bottom to top: a packaging carrier plate, a lower wafer, an isolation wafer and an upper wafer, wherein a transmitting filter is arranged in the lower wafer, and a receiving filter is arranged in the upper wafer; and an upper surface of the isolation wafer is bonded with a lower surface of the upper wafer, and a lower surface of the isolation wafer is bonded with an upper surface of the lower wafer. In the duplexer of the present invention, the isolation wafer is inserted between the upper wafer and the lower wafer, such that the spacing between the upper wafer and the lower wafer is increased, increasing the spacing between the transmitting filter and the receiving filter, and thus reducing capacitive coupling, and improving the device performance.

Description

A duplexer

Technical field

The present invention relates to the field of filtering devices for communication, in particular to a duplexer with high power capacity.

Background technique

In recent years, with the rapid development of the market, wireless communication terminals and equipment have continued to develop in the direction of miniaturization, multimode-multiband, and wireless communication terminals and equipment have continued to develop in the direction of miniaturization, multimode-multiband. The number of duplexers used in FDD (Frequency Division Duplexing, Frequency Division Duplexing) in wireless communication terminals has also increased. Especially with the approach of 5G commercial use, the demand for high-performance duplexers is also increasing.

At present, the small-size filters that can meet the needs of communication terminals are mainly piezoelectric acoustic wave filters. The resonators that constitute this type of acoustic wave filter mainly include: FBAR (Film Bulk Acoustic Resonator), SMR (Solidly Mounted) Resonator, solid-state assembly resonator) and SAW (Surface Acoustic Wave, surface acoustic wave resonator). Among them, the FBAR and SMR duplexers manufactured based on the principle of bulk acoustic wave have the characteristics of lower insertion loss and higher power capacity than the SAW duplexer manufactured based on the principle of surface acoustic wave.

The low insertion loss of the duplexer can ensure that under the premise of the same antenna transmission power (specified by the international unified communication protocol), the amplifier of the transmission channel can send a smaller power to save the power consumption of the terminal equipment, thereby extending the same power condition It can reduce the use time and reduce the heat generation in the transmission path, resulting in a better end user experience.

The higher power capacity of the duplexer means that the transmission power level of the terminal equipment can be appropriately increased to expand the coverage of the terminal signal, thereby reducing the network density of the operator’s base station and saving the operator’s network. cost. Supporting higher power levels has gradually become a basic requirement for 4G+ and 5G communication terminals.

Generally, duplexers are made by packaging two filter chips together. For a duplexer formed by two chips and a packaging substrate, the packaging efficiency is relatively low due to the requirement for the spacing between the chips due to the assembly process, which is generally only 50% to 60%. However, if two wafers with filters are directly bonded together using wafer-level sealing and bonding, the isolation performance of the duplexer will be very poor due to the capacitive coupling between the upper and lower wafers, and the isolation is only- 30dB～-40dB, too much performance degradation makes it unusable.

Therefore, how to realize a small-size duplexer with good isolation and excellent electrical performance has become an urgent problem for design engineers.

Summary of the invention

In view of this, the present invention provides a duplexer with good isolation and excellent electrical performance.

The object of the present invention is to provide a duplexer, which includes, from bottom to top, a package carrier, a lower wafer, an isolation wafer, and an upper wafer; the lower wafer is provided with an emission filter, The upper wafer is provided with a receiving filter; the upper surface of the isolation wafer is bonded to the lower surface of the upper wafer, and the lower surface of the isolation wafer is bonded to the upper surface of the lower wafer Together.

Optionally, the transmitting filter and the receiving filter are partially overlapped in the top view direction of the device.

Optionally, the intersection ratio of the projection filter and the receiving filter in the top view direction of the device is 0.2 to 0.8.

Optionally, the material of the isolation wafer is silicon.

Optionally, the thickness of the isolation wafer is 30-150 microns.

Optionally, the distance between the upper wafer and the lower wafer is 50-200 microns.

Optionally, in the receiving filter, the receiving resonator that needs to be connected to the outside is connected to a pad located on the lower surface of the lower wafer through a through hole made on the lower wafer, and then through welding The ball is connected to the package carrier board below; in the transmitting filter, the transmitting resonator that needs to be connected to the outside is connected to the through hole made on the upper wafer to the upper surface of the upper wafer. The bonding pad is connected to the bonding fingers on the package carrier through bonding wires.

Optionally, in the receiving filter, the receiving resonator that needs to be connected to the outside is connected to the pads on the upper surface of the upper wafer through the through holes made on the upper wafer, and then through the key The bonding wire is connected to the bonding finger on the package carrier; in the emission filter, the emission resonator that needs to be connected to the outside is connected to the bottom crystal through the via hole made on the bottom wafer. The pads on the lower surface of the circle are connected to the package carrier board below through solder balls.

Optionally, the material of the bonding wire is gold, copper or aluminum.

The duplexer of the embodiment of the present invention extends the distance between the upper and lower wafers by inserting an isolation wafer between the upper wafer and the lower wafer, thereby opening the distance between the transmitting filter and the receiving filter, thereby reducing the distance between the transmitting filter and the receiving filter. Capacitive coupling improves device performance.

Description of the drawings

The drawings are used to better understand the present invention, and do not constitute an improper limitation of the present invention. among them:

Figure 1 is a schematic cross-sectional view of an existing duplexer;

Fig. 2 is a schematic diagram of the circuit principle of the existing duplexer;

3 is a schematic cross-sectional view of a duplexer according to an embodiment of the present invention;

4 is a schematic cross-sectional view of the duplexer according to the second embodiment of the present invention;

Figure 5 is a schematic cross-sectional view of a triple duplexer according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of the circuit principle of the duplexer in the second embodiment and the third embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the drawings and embodiments.

FIG. 1 is a schematic cross-sectional view of a conventional duplexer, which includes, from bottom to top, a package carrier SU, a lower wafer W2, and an upper wafer W1. The lower surface of the upper wafer W1 is bonded to the upper surface of the lower wafer W2. The lower wafer W2 is provided with a transmitting filter Tx, and the upper wafer W1 is provided with a receiving filter Rx. The transmitting filter Tx and the receiving filter Rx are staggered in the device top view direction. Figure 2 is a schematic circuit diagram of a conventional duplexer. For the convenience of example, the transmitting filter and the receiving filter in the duplexer respectively include four series units and four parallel units. As shown in Figure 1 and Figure 2, a coupling capacitor C is formed between the transmitting filter Tx in the lower wafer W2 and the receiving filter Rx in the upper wafer W1 in the existing duplexer. The isolation performance of the device will deteriorate due to the capacitive coupling C.

The purpose of the present invention is to provide a duplexer, which includes, from bottom to top, a package carrier, a lower wafer, an isolation wafer, and an upper wafer; the lower wafer is provided with an emission filter, The upper wafer is provided with a receiving filter; the upper surface of the isolation wafer is bonded to the lower surface of the upper wafer, and the lower surface of the isolation wafer is bonded to the upper surface of the lower wafer Together. By inserting an isolation wafer between the upper wafer and the lower wafer, the distance between the upper and lower wafers is opened, thereby opening the distance between the transmitting and receiving filters, thereby reducing the capacitive coupling and improving the performance of the device.

In a traditional duplexer, the transceiver filters are staggered in the top view direction of the device. In the duplexer of the embodiment of the present invention, the distance between the upper and lower wafers is increased due to the insertion of the isolation wafer, which leads to a significant reduction in the parasitic capacitance between the transceiver filters. In fact, there is no need between the transceiver filters. Completely staggered, that is, a larger area of overlap can be achieved, thereby further reducing the size of the chip. Therefore, in the duplexer of the embodiment of the present invention, it is preferable that the transmitting filter and the receiving filter are partially overlapped in the top view direction of the device. The intersection ratio of the projection filter and the receiving filter in the top view direction of the device is 0.2 to 0.8.

FIG. 3 is a schematic cross-sectional view of a duplexer 100 according to an embodiment of the present invention. The duplexer 100 includes, from bottom to top, a package carrier SU, a lower wafer W2, an isolation wafer W3, and an upper wafer W1. The lower wafer W2 is provided with a transmitting filter Tx, and the upper wafer W1 is provided with a receiving filter Rx. The transmitting filter Tx and the receiving filter Rx are partially overlapped in the top view direction of the device. The upper surface of the isolation wafer W3 is bonded to the lower surface of the upper wafer W1, and the lower surface of the isolation wafer W3 is bonded to the upper surface of the lower wafer W2. In the duplexer 100 of this embodiment, the distance between the upper and lower wafers is opened by inserting the isolation wafer W3 between the upper wafer W1 and the lower wafer W2, thereby opening the transmitting filter Tx and the receiving filter Rx. This reduces the coupling capacitance C between the Tx filter and the Rx filter due to the overlap of the graphics, improves the performance of the device, and allows the transmit filter Tx and the receive filter Rx to partially overlap, effectively reducing Device size.

The material of the isolation wafer W3 may be silicon. Silicon wafers have the advantages of low cost and easy processing. The thickness of the isolation wafer W3 may be 30-150 microns. The distance between the upper wafer W1 and the lower wafer W2 may be 50-200 microns.

In the above-mentioned duplexer, no matter the transmitting filter or the receiving filter, the resonator is electrically connected to the package carrier through the through hole. Inside the duplexer, a coupling inductance is usually formed between the transmitting filter and the receiving filter, which impairs the performance of the device. For this reason, considering the improvement of the electrical connection mode, the duplexer 200 according to the second embodiment of the present invention and the three duplexer 300 according to the embodiment of the present invention are proposed.

4 is a schematic cross-sectional view of the duplexer 200 according to the second embodiment of the present invention. As shown in FIG. 4, in the duplexer 200, the receiving resonator in the receiving filter Rx that needs to be connected to the outside is connected to the pad located on the lower surface of the lower wafer W2 through the via VRx made on the lower wafer W2 Connect to the package carrier SU underneath through solder balls; the transmitting resonator in the transmitting filter Tx that needs to be connected to the outside is connected to the upper surface of the upper wafer W1 through the via VTx made on the upper wafer W1 On the bonding pads, the bonding wires LTx are connected to the bonding fingers on the package carrier SU.

FIG. 5 is a schematic cross-sectional view of a triple duplexer 300 according to an embodiment of the present invention. As shown in FIG. 5, in the duplexer 300, the receiving resonator in the receiving filter Rx that needs to be connected to the outside is connected to the solder on the upper surface of the upper wafer W1 through the via hole V made on the upper wafer W1. On the disk, it is connected to the bonding finger on the package carrier SU through the bonding wire LRx; the transmitting resonator in the transmitting filter Tx that needs to be connected to the outside is connected to the lower wafer through the through hole VTx made on the lower wafer W2 The pads on the lower surface of the wafer W2 are connected to the package carrier SU underneath through solder balls.

FIG. 6 is a schematic diagram of the circuit principle of the duplexer in the second embodiment and the third embodiment of the present invention. For the convenience of example, the transmitting filter and the receiving filter in the duplexer shown in FIG. 6 respectively include four series units and four parallel units. Because part of the resonators in the transmitting filter or receiving filter no longer pass through the via holes but are electrically connected to the package carrier through the bonding wire, the mutual inductance distance between the resonators is extended, and the coupling inductance is reduced. Improved the electrical performance of the duplexer.

Although the specific embodiments of the present invention are described above in conjunction with the accompanying drawings, they do not limit the scope of protection of the present invention. Those skilled in the art should understand that on the basis of the technical solutions of the present invention, those skilled in the art do not need to make creative efforts. Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims

A duplexer characterized by:

The duplexer includes, from bottom to top, a package carrier, a lower wafer, an isolation wafer, and an upper wafer;

A transmitting filter is provided in the lower wafer, and a receiving filter is provided in the upper wafer;

The upper surface of the isolation wafer is bonded with the lower surface of the upper wafer, and the lower surface of the isolation wafer is bonded with the upper surface of the lower wafer.
4. The duplexer according to claim 1, wherein in the top view direction of the device, the transmitting filter and the receiving filter are partially overlapped.
The duplexer according to claim 2, wherein the intersection ratio of the projection filter and the receiving filter in the top view direction of the device is 0.2 to 0.8.
The duplexer of claim 1, wherein the material of the isolation wafer is silicon.
The duplexer of claim 1, wherein the thickness of the isolation wafer is 30-150 microns.
The duplexer of claim 1, wherein the distance between the upper wafer and the lower wafer is 50-200 microns.
The duplexer of claim 1, wherein:

In the receiving filter, the receiving resonator that needs to be connected to the outside is connected to the pads on the lower surface of the lower wafer through the through holes made on the lower wafer, and then connected to the lower surface of the lower wafer through solder balls. The package carrier board connection;

In the transmitting filter, the transmitting resonator that needs to be connected to the outside is connected to the pad located on the upper surface of the upper wafer through the through hole made on the upper wafer, and then connected to the ground through a bonding wire. The bonding fingers on the package carrier board are connected.
The duplexer of claim 1, wherein:

In the receiving filter, the receiving resonator that needs to be connected to the outside is connected to the pads on the upper surface of the upper wafer through the through holes made on the upper wafer, and then connected to the soldering pads on the upper surface of the upper wafer through bonding wires. The bonding fingers on the package carrier are connected;

In the transmitting filter, the transmitting resonator that needs to be connected to the outside is connected to the pad located on the lower surface of the lower wafer through the through hole made on the lower wafer, and then connected to the lower surface through the solder ball. The package carrier board is connected.
The duplexer according to claim 7 or 8, wherein the material of the bonding wire is gold, copper or aluminum.