WO2022205214A1 - Filter and manufacturing method therefor, and electronic device - Google Patents

Abstract

Provided in the present application are a filter and a manufacturing method therefor, and an electronic device, which are used for improving the power of a filter, and for solving the problem of it being impossible for a filter applied to a terminal device such as a mobile phone at present to be applied to a base station due to a lower power. The filter comprises: a silicon carbide substrate, an acoustic wave reflection layer, which is arranged on one side of the silicon carbide substrate, and a metal electrode, which is arranged on the side of the acoustic wave reflection layer that is away from the silicon carbide substrate. The metal electrode comprises a bottom metal electrode and a top metal electrode, and a piezoelectric functional layer is arranged between the bottom metal electrode and the top metal electrode. A silicon carbide substrate is used for the filter, and the silicon carbide substrate can achieve stronger heat dissipation and has higher temperature compensation, thereby reducing temperature drifts, and further improving the power of the filter, such that the filter can be applied to an application scenario with a higher power, such as a small base station or micro base station scenario in 5G.

Description

Filter, method for making the same, and electronic device technical field

The present application relates to the field of semiconductor technology, and in particular, to a filter, a method for making the same, and an electronic device.

Background technique

In current wireless communication base stations, dielectric filters are generally used as filters. The dielectric filters are bulky and heavy, and the weight of the filters may account for 5% to 10% of the total weight of the base station. In the base station of the 5th generation mobile networks (5G), the multiple-input multiple-output (massive multiple-input, multiple-output, massive MIMO) technology of the massive antenna is introduced, and the number of radio frequency channels will be From 64 channels to 128 channels, or even more, the volume and weight of the filter have to be miniaturized and lightweight.

At present, filters applied to terminal equipment such as mobile phones can meet the requirements of lightweight, but due to the structure of the device, the power of the filter is relatively low, generally less than 1 watt (W), which cannot meet the high-power requirements of base stations.

SUMMARY OF THE INVENTION

The present application provides a filter, a method for making the same, and an electronic device, which are used to increase the power of the filter and solve the problem that the filter currently applied to terminal equipment such as mobile phones cannot be applied to a base station due to its low power.

In a first aspect, an embodiment of the present application provides a filter. The filter includes: a silicon carbide substrate, an acoustic wave reflection layer disposed on one side of the silicon carbide substrate, and a metal electrode disposed on the side of the acoustic wave reflection layer away from the silicon carbide substrate. The metal electrode includes a bottom metal electrode and a top metal electrode, and a piezoelectric functional layer is arranged between the bottom metal electrode and the top metal electrode.

It should be understood that the filter is a solidly mounted resonator (SMR). In the filter, the sound wave can vibrate between the bottom metal electrode and the top metal electrode, and the sound wave reflection layer realizes total reflection, so as to realize the function of filtering.

Based on the filter provided in the first aspect. The filter uses a silicon carbide substrate, which can achieve better heat dissipation and better temperature compensation, thereby reducing temperature drift, thereby increasing the power of the filter, enabling it to be used in higher power application scenarios , such as the small base station or micro base station scenario in 5G.

Optionally, the acoustic wave reflection layer includes a plurality of low acoustic impedance layers and a plurality of high acoustic impedance layers arranged in layers, and the low acoustic impedance layers and the high acoustic impedance layers are alternately arranged. The low acoustic impedance layer refers to a hierarchical structure formed of a material with a faster sound propagation speed, such as a silicon dioxide (SiO ₂ ) material. The high acoustic impedance layer refers to a hierarchical structure made of materials with slow sound propagation speed, such as silicon nitride (Si ₃ N ₄ ), tantalum pentoxide (Ta ₂ O ₅ ), and metal tungsten (W). In this way, the sound wave reflection layer can be formed into a Bragg reflector, and the sound wave can be reflected into the piezoelectric functional layer, and the sound wave reflection layer is alternately arranged by multiple layers of high acoustic impedance and multiple layers of low acoustic impedance, and The thickness of each impedance layer (high acoustic impedance layer or low acoustic impedance layer) is 1/4 of the acoustic wave wavelength λ, so that after the acoustic wave is transmitted to the acoustic wave reflection layer, phenanthrene occurs at the interface between the high acoustic impedance layer and the low acoustic impedance layer. Neil reflection, after the superposition of the emitted sound wave and the incident wave, the sound wave is finally totally reflected to the piezoelectric functional layer.

Optionally, the bottom metal electrode is located on the side of the acoustic wave reflection layer away from the silicon carbide substrate, and one end of the top metal electrode extends along the sidewall of the piezoelectric functional layer to the acoustic wave reflection layer and is flush with the bottom metal electrode. In this way, when the filter chip is packaged, the packaging wiring of the top metal electrode and the bottom metal electrode can be realized on the same plane, which is more convenient for packaging wiring, and also saves the volume after packaging, thereby saving costs.

Optionally, on the plane where the bottom metal electrode is located, there is an isolation region between the bottom metal electrode and the top metal electrode, and the isolation region is filled with a dielectric material. In this way, isolation of the bottom metal electrode from the top metal electrode can be achieved.

Optionally, the dielectric material is silicon dioxide. When silicon dioxide is used as the dielectric material, silicon dioxide can also be used as a bonding material, which can increase the adhesion between the piezoelectric functional layer, the acoustic wave reflection layer and the isolation region, thereby improving the stability and reliability of the filter structure.

Optionally, the material of the piezoelectric functional layer is one of single crystal lithium niobate, single crystal lithium tantalate or single crystal aluminum nitride. Setting the material of the piezoelectric functional layer to a single crystal material can increase the frequency of the filter to improve the filtering performance of the filter.

In a second aspect, the embodiments of the present application provide another filter. The filter includes: a silicon carbide substrate, and a piezoelectric functional layer arranged on one side of the silicon carbide substrate. The silicon carbide substrate includes a first silicon carbide substrate portion and a second silicon carbide substrate portion, and a cavity structure is formed between the first silicon carbide substrate portion, the second silicon carbide substrate portion and the piezoelectric functional layer. The side of the piezoelectric functional layer away from the silicon carbide substrate is provided with a top metal electrode, and the side of the piezoelectric functional layer close to the silicon carbide substrate is provided with a bottom metal electrode, and the bottom metal electrode is located in the first silicon carbide substrate part, the second In the cavity structure between the silicon carbide substrate portion and the piezoelectric functional layer.

It should be understood that the filter is a film bulk acoustic resonator (FBAR). In the filter, sound waves can vibrate between the bottom metal electrode and the top metal electrode, and the cavity under the bottom metal electrode is used as an air reflection layer to achieve total reflection, thereby realizing the function of filtering.

Based on the filter provided in the second aspect, the filter also uses a silicon carbide substrate. The silicon carbide substrate can achieve better heat dissipation and better temperature compensation, thereby reducing temperature drift, thereby increasing the power of the filter, making the It can be applied to higher power application scenarios, such as small base stations or micro base stations in 5G.

Optionally, the above filter further includes a bonding material layer. The bonding material layer is located between the piezoelectric functional layer and the silicon carbide substrate, and the side of the bonding material layer close to the piezoelectric functional layer is flush with the side of the bottom metal electrode close to the piezoelectric functional layer. In this way, the piezoelectric functional layer can be bonded to the silicon carbide substrate through the bonding material layer, so as to improve the stability and reliability of the structure.

Optionally, the material of the bonding material layer is silicon dioxide.

Optionally, the thickness of the bonding material layer is 0.1 to 5 microns.

Optionally, both ends of the bottom metal electrode extend to the first silicon carbide substrate portion and the second silicon carbide substrate portion along the sidewalls of the first silicon carbide substrate portion and the second silicon carbide substrate portion respectively. Bottom outer edge. In this way, the wiring of the bottom metal electrode during packaging can be facilitated, so as to simplify the packaging process and save costs.

Optionally, the material of the piezoelectric functional layer is one of single crystal lithium niobate, single crystal lithium tantalate or single crystal aluminum nitride. In this way, the frequency and filtering performance of the filter can be improved.

In a third aspect, the embodiments of the present application provide yet another filter. The filter includes a piezoelectric functional layer and a metal electrode arranged on one side of the piezoelectric functional layer. A silicon carbide substrate is provided on the side of the piezoelectric functional layer away from the metal electrode. A bonding material layer is arranged between the silicon carbide substrate and the piezoelectric functional layer.

It should be understood that the filter is a surface acoustic wave filter (surface acoustic wave filters, SAW filters). In the filter, the metal electrode may include a plurality of interdigital transducers IDTs, and the plurality of interdigital transducers IDTs are arranged at intervals. When realizing the filtering function, the interdigital transducer IDT in the metal electrode converts the electrical signal into a sound signal to form a mechanical vibration wave, which propagates on the surface of the piezoelectric functional layer, and then is converted into an electrical signal by another interdigital transducer IDT. Signal output, so as to achieve the function of filtering.

Based on the filter provided by the third aspect. The filter still uses a silicon carbide substrate, which can achieve better heat dissipation and better temperature compensation, thereby reducing temperature drift, thereby increasing the power of the filter, enabling it to be applied to higher power applications Scenarios, such as small base stations or micro base stations in 5G. In addition, a bonding material layer is used between the piezoelectric functional layer and the silicon carbide substrate to realize the bonding between the silicon carbide substrate and the piezoelectric functional layer, which can improve the performance of the silicon carbide substrate, the piezoelectric functional layer and the bonding material layer. The adhesion between the filters improves the stability and reliability of the filter on the premise that the filter has better heat dissipation.

Optionally, the thickness of the bonding material layer is 0.1 μm to 5 μm, and the material of the bonding material layer is silicon dioxide or metal.

Optionally, the material of the piezoelectric functional layer is one of single crystal lithium niobate, single crystal lithium tantalate or single crystal aluminum nitride.

In a fourth aspect, an embodiment of the present application provides a method for fabricating a filter. The manufacturing method can be applied to any filter provided in the first aspect. The fabrication method includes: fabricating an acoustic wave reflection layer on one side of a silicon carbide substrate. The bottom metal electrode is fabricated on the side of the acoustic wave reflection layer away from the silicon carbide substrate. On the side of the bottom metal electrode away from the silicon carbide substrate, the piezoelectric functional layer is bonded by means of wafer bonding. The top metal electrode is fabricated on the side of the piezoelectric functional layer away from the silicon carbide substrate.

Optionally, the manufacturing method provided in the fourth aspect may further include: forming an isolation region by etching on the bottom metal electrode, and depositing a dielectric material in the isolation region.

Optionally, bonding the piezoelectric functional layer on the side of the bottom metal electrode away from the silicon carbide substrate by means of wafer bonding may include: using ion implantation to bond the piezoelectric functional layer to the piezoelectric functional layer material. circle, pre-cut. The pre-cut wafer is bonded to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding. The pre-cut wafer is peeled off so that the thickness of the piezoelectric functional layer meets the designed thickness of the piezoelectric functional layer.

Optionally, bonding the piezoelectric functional layer on the side of the bottom metal electrode away from the silicon carbide substrate by means of wafer bonding may include: bonding the wafer made of the piezoelectric functional layer material by wafer bonding. way to bond to the bottom metal electrode on the side away from the SiC substrate. By means of mechanical thinning, the thickness of the piezoelectric functional layer can meet the designed thickness of the piezoelectric functional layer.

It should be understood that by fabricating the piezoelectric functional layer by wafer bonding, the material of the piezoelectric functional layer can be made of a single crystal material, thereby increasing the frequency of the filter, increasing the bandwidth of the filter, and further improving the filtering performance of the filter.

In a fifth aspect, the embodiments of the present application provide another method for fabricating a filter. The manufacturing method is applied to any filter provided in the second aspect. The fabrication method includes: fabricating a bonding material layer and a bottom metal electrode on one side of a silicon carbide substrate. On the side of the bonding material layer and the bottom metal electrode away from the silicon carbide substrate, the piezoelectric functional layer is bonded. The top metal electrode is fabricated on the side of the piezoelectric functional layer away from the silicon carbide substrate. Etching from the bottom of the silicon carbide substrate to form a first silicon carbide substrate portion and a second silicon carbide substrate portion with a bottom metal electrode between the first silicon carbide substrate portion and the second silicon carbide substrate portion within the cavity structure.

Optionally, the fabrication method provided in the fifth aspect may further include: a sidewall of the cavity structure between the first silicon carbide substrate portion and the second silicon carbide substrate portion, and the first silicon carbide substrate portion and The second silicon carbide substrate is partially away from the side of the piezoelectric functional layer, and the bottom metal electrode is formed.

Optionally, on the side of the bonding material layer and the bottom metal electrode that is far away from the silicon carbide substrate, bonding the piezoelectric functional layer by means of wafer bonding may include: using ion implantation to bind the piezoelectric functional layer. Wafers made of layer materials are pre-cut. The pre-cut wafer is bonded to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding. The pre-cut wafer is peeled off so that the thickness of the piezoelectric functional layer meets the designed thickness of the piezoelectric functional layer.

Optionally, on the side of the bonding material layer and the bottom metal electrode away from the silicon carbide substrate, bonding the piezoelectric functional layer by means of wafer bonding, which may include: bonding a wafer made of piezoelectric functional layer material, Bonded to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding. By means of mechanical thinning, the thickness of the piezoelectric functional layer can meet the designed thickness of the piezoelectric functional layer.

In a sixth aspect, an embodiment of the present application provides yet another method for fabricating a filter, and the fabricating method is applied to any filter provided in the third aspect. The fabrication method includes: fabricating a bonding material layer on one side of a silicon carbide substrate. On the side of the bonding material layer away from the silicon carbide substrate, the piezoelectric functional layer is bonded by means of wafer bonding. Metal electrodes are fabricated on the side of the piezoelectric functional layer away from the silicon carbide substrate.

Optionally, on the side of the bonding material layer far away from the silicon carbide substrate, bonding the piezoelectric functional layer by means of wafer bonding may include: using ion implantation to bond the piezoelectric functional layer made of the piezoelectric functional layer material. Wafers, pre-cut. The pre-cut wafer is bonded to the side of the bonding material layer away from the silicon carbide substrate by wafer bonding. The pre-cut wafer is peeled off so that the thickness of the piezoelectric functional layer meets the designed thickness of the piezoelectric functional layer.

Optionally, on the side of the bonding material layer away from the silicon carbide substrate, bonding the piezoelectric functional layer by means of wafer bonding, which may include: bonding the wafer made of the piezoelectric functional layer material through wafer bonding. Bonding to the side of the bonding material layer away from the silicon carbide substrate. By means of mechanical thinning, the thickness of the piezoelectric functional layer can meet the designed thickness of the piezoelectric functional layer.

In a seventh aspect, an embodiment of the present application provides an electronic device. The electronic device includes an antenna PCB board, multiple antennas and multiple filters. Multiple antennas and multiple filters are coupled on the antenna PCB. Wherein, the filter is any one of the possible filters in the first aspect to the third aspect above.

It can be understood that, the manufacturing method, electronic device, etc. of any filter provided above can be realized by the corresponding filter provided above, or associated with the corresponding filter provided above, so , the beneficial effects that can be achieved can be referred to the beneficial effects of the filters provided above, which will not be repeated here.

Description of drawings

FIG. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of another electronic device provided by an embodiment of the present application;

3 is a schematic structural diagram of an active antenna unit in an electronic device provided by an embodiment of the present application;

4 is a schematic structural diagram of a filter provided by the first embodiment of the present application;

Fig. 5 is the production method flow chart of the filter in Fig. 4;

6 is a schematic structural diagram of performing S501 in FIG. 5;

FIG. 7 is a schematic structural diagram of performing S502 in FIG. 5;

FIG. 8 is a schematic structural diagram of performing S503 in FIG. 5;

FIG. 9 is a schematic structural diagram of performing S503 by means of ion implantation;

FIG. 10 is a schematic structural diagram of performing S503 by means of mechanical thinning;

FIG. 11 is a schematic structural diagram after performing S504 in FIG. 5;

12 is a schematic structural diagram 1 of a filter provided by the second embodiment of the application;

13 is a second schematic structural diagram of a filter provided by the second embodiment of the application;

Fig. 14 is a flow chart of the manufacturing method of the filter shown in Fig. 12 and Fig. 13;

FIG. 15 is a schematic structural diagram after performing S1401 in FIG. 14 to deposit a bonding material layer on a silicon carbide substrate;

FIG. 16 is a schematic structural diagram after performing the S1401 etching in FIG. 14 to remove the bonding material layer at the middle position of the silicon carbide substrate;

FIG. 17 is a schematic structural diagram of depositing a bottom metal electrode at the position where the bonding material layer is etched and removed by performing S1401 in FIG. 14;

FIG. 18 is a schematic structural diagram of performing the formation of S1402 in FIG. 14;

FIG. 19 is a schematic structural diagram of performing S1402 by means of ion implantation;

FIG. 20 is a schematic structural diagram of performing S1402 by means of mechanical thinning;

FIG. 21 is a schematic structural diagram of performing the formation of S1403 in FIG. 14;

FIG. 22 is a schematic structural diagram of performing the formation of S1404 in FIG. 14;

FIG. 23 is a schematic structural diagram of performing the formation of S1405 in FIG. 14;

24 is a schematic structural diagram of a filter provided by a third embodiment of the application;

Figure 25 is a flow chart of a method for making the filter shown in Figure 24;

FIG. 26 is a schematic structural diagram of performing S2501 formation in FIG. 25;

FIG. 27 is a schematic structural diagram of performing the formation of S2502 in FIG. 25;

FIG. 28 is a schematic structural diagram of performing S2502 by means of ion implantation;

FIG. 29 is a schematic structural diagram of performing S2502 by means of mechanical thinning;

FIG. 30 is a schematic structural diagram of performing the formation of S2503 in FIG. 25;

31 is a schematic diagram of a filter structure formed by interconnecting a plurality of filters shown in FIG. 24;

FIG. 32 is a filter graph of the filter shown in FIG. 31 .

Detailed ways

In this application, "at least one" means one or more, and "plurality" means two or more. "And/or", which describes the association relationship of the associated objects, indicates that there can be three kinds of relationships, for example, A and/or B, which can indicate: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A, B can be singular or plural. "At least one item(s) below" or similar expressions thereof refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (a) of a, b or c may represent: a, b, c, a-b, a-c, b-c or a-b-c, where a, b and c may be single or multiple. The character "/" generally indicates that the associated objects are an "or" relationship. In addition, in the embodiments of the present application, words such as "first" and "second" do not limit the quantity and execution order.

It should be noted that, in this application, words such as "exemplary" or "for example" are used to represent examples, illustrations or illustrations. Any embodiment or design described in this application as "exemplary" or "such as" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present the related concepts in a specific manner.

In this application, unless otherwise expressly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" may be a fixed connection, a detachable connection, or an integrated body; it may be directly connected, or Can be indirectly connected through an intermediary. In addition, the term "electrical connection" may be a direct electrical connection or an indirect electrical connection through an intermediate medium.

In a wireless communication system, devices can be divided into devices that provide wireless network services and devices that use wireless network services. The devices that provide wireless network services refer to those devices that make up a wireless communication network, which can be referred to as network equipment or network elements for short. Network equipment is usually owned by operators (such as China Mobile and Vodafone) or infrastructure providers (such as tower companies), and these manufacturers are responsible for operation or maintenance. Network devices can be further classified into radio access network (RAN) devices and core network (core network, CN) devices. A typical RAN device includes a base station (BS).

It should be understood that the base station may also sometimes be referred to as a wireless access point (access point, AP), or a transmission reception point (transmission reception point, TRP). Specifically, the base station may be a general node B (generation Node B, gNB) in a 5G new radio (new radio, NR) system, or an evolutional Node B (evolutional Node B, eNB) in a 4G long term evolution (long term evolution, LTE) system. ). Base stations can be classified into macro base stations or micro base stations according to their physical form or transmit power. Micro base stations are also sometimes referred to as small base stations or small cells.

Devices using wireless network services are usually located at the edge of the network and may be referred to as a terminal for short. The terminal can establish a connection with the network device, and provide the user with specific wireless communication services based on the service of the network device. It should be understood that because the terminal has a closer relationship with the user, it is sometimes also referred to as user equipment (user equipment, UE), or subscriber unit (subscriber unit, SU). In addition, as opposed to base stations, which are usually placed in fixed locations, terminals tend to move with users and are sometimes referred to as mobile stations (mobile stations, MSs). In addition, some network devices, such as relay nodes (relay nodes, RNs) or wireless routers, can sometimes be regarded as terminals because they have UE identity or belong to users.

Specifically, the terminal may be a mobile phone, a tablet computer, a laptop computer, a wearable device (such as a smart watch, smart bracelet, smart helmet, smart glasses), and other Devices with wireless access capabilities, such as smart cars, various Internet of things (IOT) devices, including various smart home devices (such as smart meters and smart home appliances) and smart city devices (such as security or monitoring equipment, intelligent road transport facilities), etc.

FIG. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present application. The electronic device may be a terminal or a base station in this embodiment of the present application. As shown in FIG. 1, the electronic device may include an application subsystem, a memory, a mass storage, a baseband subsystem, a radio frequency integrated circuit (RFIC), a radio frequency front end, RFFE) devices, and antennas (antenna, ANT), these devices can be coupled through various interconnecting buses or other electrical connections.

In FIG. 1 , ANT_1 represents the first antenna, ANT_N represents the Nth antenna, and N is a positive integer greater than 1. Tx represents the transmit path, Rx represents the receive path, and different numbers represent different paths. FBRx represents the feedback receiving path, PRx represents the primary receiving path, and DRx represents the diversity receiving path. HB means high frequency, LB means low frequency, both refer to the relative high and low frequency. BB stands for baseband. It should be understood that the labels and components in FIG. 1 are for illustrative purposes only, and are only used as a possible implementation manner, and the embodiments of the present application also include other implementation manners.

The application subsystem can be used as the main control system or main computing system of the electronic device to run the main operating system and application programs, manage the hardware and software resources of the entire electronic device, and provide users with a user interface. The application subsystem may include one or more processing cores. In addition, the application subsystem may also include driver software related to other subsystems (eg, baseband subsystem). The baseband subsystem may also include one or more processing cores, as well as hardware accelerators (HACs) and caches.

In Figure 1, the RFFE device, RFIC 1 (and optionally RFIC 2) can collectively form an RF subsystem. The RF subsystem can be further divided into the RF receive path (RF receive path) and the RF transmit path (RF transmit path). The RF receive channel can receive the RF signal through the antenna, process the RF signal (eg, amplify, filter and down-convert) to obtain the baseband signal, and transmit it to the baseband subsystem. The RF transmit channel can receive the baseband signal from the baseband subsystem, perform RF processing (such as up-conversion, amplification and filtering) on the baseband signal to obtain the RF signal, and finally radiate the RF signal into space through the antenna. Specifically, the radio frequency subsystem may include an antenna switch, an antenna tuner, a low noise amplifier (LNA), a power amplifier (PA), a mixer (mixer), a local oscillator (LOO) ), filters and other electronic devices, which can be integrated into one or more chips as required. Antennas can also sometimes be considered part of the RF subsystem.

The baseband subsystem can extract useful information or data bits from the baseband signal, or convert the information or data bits into the baseband signal to be transmitted. These information or data bits may be data representing user data or control information such as voice, text, video, etc. For example, the baseband subsystem can implement signal processing operations such as modulation and demodulation, encoding and decoding. Different radio access technologies, such as 5G NR and 4G LTE, tend to have different baseband signal processing operations. Therefore, in order to support the convergence of multiple mobile communication modes, the baseband subsystem may simultaneously include multiple processing cores, or multiple HACs.

In addition, since the radio frequency signal is an analog signal, the signal processed by the baseband subsystem is mainly a digital signal, and an analog-to-digital conversion device is also required in the electronic equipment. The analog-to-digital conversion device includes an analog-to-digital converter (ADC) that converts an analog signal to a digital signal, and a digital-to-analog converter (DAC) that converts a digital signal to an analog signal. In this embodiment of the present application, the analog-to-digital conversion device may be disposed in the baseband subsystem, or may be disposed in the radio frequency subsystem.

It should be understood that, in this embodiment of the present application, the processing core may represent a processor, and the processor may be a general-purpose processor or a processor designed for a specific field. For example, the processor may be a central processing unit (center processing unit, CPU), or may be a digital signal processor (digital signal processor, DSP). The processor may also be a microcontroller (micro control unit, MCU), a graphics processor (graphics processing unit, GPU), an image signal processor (image signal processing, ISP), an audio signal processor (audio signal processor, ASP) ), and processors specially designed for artificial intelligence (AI) applications. AI processors include, but are not limited to, neural network processing units (NPUs), tensor processing units (TPUs), and processors called AI engines.

Hardware accelerators can be used to implement some sub-functions with high processing overhead, such as data packet assembly and parsing, data packet encryption and decryption, etc. These sub-functions can also be implemented using general-purpose processors, but hardware accelerators may be more appropriate due to performance or cost considerations. Therefore, the type and number of hardware accelerators can be specifically selected based on requirements. In a specific implementation manner, one or a combination of a field programmable gate array (FPGA) and an application specific integrated circuit (ASIC) can be used to implement the implementation. Of course, one or more processing cores may also be used in a hardware accelerator.

Memory can be divided into volatile memory (volatile memory) and non-volatile memory (non-volatile memory, NVM). Volatile memory refers to memory in which data stored inside is lost when the power supply is interrupted. At present, volatile memory is mainly random access memory (random access memory, RAM), including static random access memory (static RAM, SRAM) and dynamic random access memory (dynamic RAM, DRAM). Non-volatile memory refers to memory whose internal data will not be lost even if the power supply is interrupted. Common non-volatile memories include read only memory (ROM), optical disks, magnetic disks, and various memories based on flash memory technology. Generally speaking, memory can choose volatile memory, and mass storage can choose non-volatile memory, such as magnetic disk or flash memory.

In the embodiment of the present application, the baseband subsystem and the radio frequency subsystem together form a communication subsystem, which provides a wireless communication function for the electronic device. Generally, the baseband subsystem is responsible for managing the hardware and software resources of the communication subsystem, and can configure the working parameters of the radio frequency subsystem. One or more processing cores of the baseband subsystem may be integrated into one or more chips, which may be referred to as baseband processing chips or baseband chips. Similarly, RFICs may be referred to as radio frequency processing chips or radio frequency chips. In addition, with the evolution of technology, the functional division of the radio frequency subsystem and the baseband subsystem in the communication subsystem can also be adjusted. For example, the functions of part of the radio frequency subsystem are integrated into the baseband subsystem, or the functions of part of the baseband subsystem are integrated into the radio frequency subsystem. In practical applications, based on the needs of application scenarios, electronic devices may employ combinations of different numbers and types of processing cores.

In this embodiment of the present application, the radio frequency subsystem may include an independent antenna, an independent radio frequency front end (RF front end, RFFE) device, and an independent radio frequency chip. A radio frequency chip is also sometimes referred to as a receiver, transmitter, or transceiver. Antennas, RF front-end devices, and RF processing chips can all be manufactured and sold separately. Of course, the RF subsystem can also use different devices or different integration methods based on power consumption and performance requirements. For example, some devices belonging to the radio frequency front-end are integrated into the radio frequency chip, and even the antenna and the radio frequency front-end device are integrated into the radio frequency chip, and the radio frequency chip can also be called a radio frequency antenna module or an antenna module.

In this embodiment of the present application, the baseband subsystem may be used as an independent chip, and the chip may be called a modem chip. The hardware components of the baseband subsystem can be manufactured and sold in units of modem chips. Modem chips are also sometimes called baseband chips or baseband processors. In addition, the baseband subsystem can also be further integrated in the SoC chip, and manufactured and sold in the unit of SoC chip. The software components of the baseband subsystem can be built into the hardware components of the chip before the chip leaves the factory, or can be imported into the hardware components of the chip from other non-volatile memory after the chip leaves the factory, or can also be downloaded online through the network. and update these software components.

FIG. 2 is a schematic structural diagram of another electronic device according to an embodiment of the present application. Figure 2 shows some common components used for RF signal processing in electronic equipment. It should be understood that although only one radio frequency receiving channel and one radio frequency transmitting channel are shown in FIG. 2 , the electronic device in this embodiment of the present application is not limited thereto, and the electronic device may include one or more radio frequency receiving channels and radio frequency transmitting channels.

For the radio frequency receiving channel, the radio frequency signal received from the antenna is selected by the antenna switch and sent to the radio frequency receiving channel. Since the RF signal received from the antenna is usually very weak, it is usually amplified by a low noise amplifier (LNA). The amplified signal first goes through the down-conversion processing of the mixer, then passes through the filter and the analog-to-digital converter ADC, and finally completes the baseband signal processing. For the radio frequency transmission channel, the baseband signal can be converted into an analog signal through the digital-to-analog converter DAC, and the analog signal is converted into a radio frequency signal through the up-conversion processing of the mixer, and the radio frequency signal is processed by the filter and the power amplifier PA, Finally, through the selection of the antenna switch, it radiates outward from the appropriate antenna.

Among them, in the mixer, the input signal and the local oscillator LO signal are mixed, and up-conversion (corresponding to the radio frequency transmit channel) or down-conversion (corresponding to the radio frequency receive channel) operation can be realized. Among them, the local oscillator LO is a common term in the field of radio frequency, usually referred to as the local oscillator. The local oscillator is sometimes called a frequency synthesizer or frequency synthesizer, or simply frequency synthesizer. The main function of the local oscillator or frequency synthesizer is to provide the specific frequency required for radio frequency processing, such as the frequency point of the carrier. Higher frequencies can be implemented using devices such as phase locked loops (PLLs) or delay locked loops (DLLs). The lower frequency can be realized by directly using a crystal oscillator, or by dividing the frequency of the high-frequency signal generated by devices such as PLL.

It should be understood that the filter is the core component of the RF front-end RFFE in electronic equipment. The main function of the filter is to eliminate the interference and clutter in the RF transmission channel or the RF reception channel, so that useful signals can pass through, and the The signal is attenuated as little as possible, and the unwanted signal is attenuated as much as possible, allowing for more accurate frequency band selection.

In the current wireless communication base station, the filter generally adopts the dielectric filter. The dielectric filter has the characteristics of low insertion loss, high suppression, and high power. However, the dielectric filter is large in size and heavy, and the weight of the filter may account for To 5% to 10% of the total weight of the base station. In the base station of the 5th generation mobile networks (5G), the multiple-input multiple-output (massive multiple-input, multiple-output, massive MIMO) technology of the massive antenna is introduced, and the number of radio frequency channels will be From 64 channels to 128 channels, or even more, the volume and weight of the active antenna unit (AAU) have requirements for miniaturization and light weight. It should be understood that the active antenna unit may be the radio frequency subsystem in the electronic device shown in FIG. 1 , or may be a combination of the antenna shown in FIG. 2 and the radio frequency signal processing module.

In a 5G base station, as shown in FIG. 3 , the active antenna unit 01 may include an antenna printed circuit board (PCB) 20 , multiple antennas 30 and multiple filters 10 . The multiple antennas 30 and the multiple filters are all coupled to the antenna PCB 20, so as to realize the filtering function of the radio frequency signal before the signal is transmitted or after the signal is received.

In order to realize the lightweight requirement of the active antenna unit, the volume and weight of the filter are required to be lightweight. Filters currently applied to terminal equipment such as mobile phones, such as solidly mounted resonator (SMR), film bulk acoustic resonator (FBAR) and surface acoustic wave filters (surface acoustic wave filters, SAW filters), etc. The volume of this type of filter is generally 1/40 of the dielectric filter, and the weight is 1/30 of the dielectric filter, which can meet the needs of lightweight, but due to the structure of the device, the power of the filter is relatively low, generally less than 1 Watts (W) cannot meet the high power requirements of the base station.

In order to increase the power of the filter, the embodiments of the present application provide an improved filter structure. The improved filter structure will be described in detail below with reference to FIGS. 4 to 30 .

FIG. 4 is a schematic structural diagram of a filter provided by the first embodiment of the present application. As shown in FIG. 4 , the filter 100 includes a silicon carbide (SiC) substrate 101 , an acoustic wave reflective layer 102 disposed on one side of the SiC substrate 101 , and a metal disposed on the side of the acoustic wave reflective layer 102 away from the SiC substrate electrode. The metal electrodes include a bottom metal electrode 103 and a top metal electrode 105 , and a piezoelectric functional layer 104 is disposed between the bottom metal electrode 103 and the top metal electrode 105 .

It should be noted that what is shown in FIG. 4 is an assembled bulk acoustic wave filter (solidly mounted resonator, SMR). In the filter 100, the sound wave can vibrate between the bottom metal electrode 103 and the top metal electrode 105, and realize total reflection through the sound wave reflection layer 102, thereby realizing the function of filtering.

It should be understood that in the above filter 100, the silicon carbide (SiC) substrate 101 may be a crystalline type silicon carbide (SiC) material such as 4H, 6H, or 15R, which is usually a semi-insulating silicon carbide substrate with a resistance >1e5 ohms · In centimeters (Ohm·cm), the off-angle of the crystal orientation of the silicon carbide substrate 101 is 0 degrees to 8 degrees.

In the filter 100 device, the silicon carbide substrate 101 can achieve better heat dissipation and better temperature compensation, thereby reducing temperature drift, thereby increasing the power of the filter 100, making it applicable to higher power applications Scenarios, such as small base stations or micro base stations in 5G.

In addition, in order to realize the total reflection of acoustic waves in the acoustic wave reflection layer 102, the acoustic wave reflection layer 102 includes a plurality of low acoustic impedance layers 1021 and a plurality of high acoustic impedance layers 1022 arranged in layers, and the low acoustic impedance layer 1021 and the high acoustic impedance layer 1022 Alternate settings. As shown in FIG. 4 , on the silicon carbide substrate 101, a low acoustic impedance layer 1021 is first arranged, then a high acoustic impedance layer 1022 is arranged, then a low acoustic impedance layer 1021 is arranged, and a high acoustic impedance layer 1021 is arranged. The acoustic impedance layers 1022 are stacked and alternately arranged in sequence. The thicknesses of the low acoustic impedance layer 1021 and the high acoustic impedance layer 1022 can both be selected in the range of 0 to 1 μm.

The low acoustic impedance layer 1021 refers to a hierarchical structure formed by a material with a faster sound propagation speed (lower acoustic impedance), such as a silicon dioxide (SiO ₂ ) material. The high acoustic impedance layer 1022 refers to a hierarchical structure made of materials with slower sound propagation speed (higher acoustic impedance), such as silicon nitride (Si ₃ N ₄ ), tantalum pentoxide (Ta ₂ O ₅ ) and Metal tungsten (W) and other materials.

In this way, the acoustic wave reflection layer 102 can be formed into a Bragg reflector, and the acoustic wave can be reflected into the piezoelectric functional layer 104, and the acoustic wave reflection layer 102 is composed of multiple layers of high acoustic impedance layers 1022 and multiple layers of low acoustic impedance layers. 1021 are alternately arranged, and the thickness of each impedance layer (high acoustic impedance layer 1022 or low acoustic impedance layer 1021) is 1/4 of the acoustic wave wavelength λ, so that after the acoustic wave is transmitted to the acoustic wave reflection layer 102, the high acoustic impedance layer 1022 and The Fresnel reflection occurs at the interface of the low acoustic impedance layer 1021 , and the reflected sound wave and the incident wave are superimposed, and finally the sound wave is totally reflected to the piezoelectric functional layer 104 .

It should be understood that the number of alternating layers of the low-acoustic impedance layer 1021 and the high-acoustic impedance layer 1022 is not limited to the two layers shown in FIG. There is no special restriction on this. The low-acoustic impedance layer 1021 may also be disposed above the high-acoustic impedance layer 1022. The embodiments of the present application do not specifically limit the positional relationship between the low-acoustic impedance layer 1021 and the high-acoustic impedance layer 1022. The material selected for the resistance layer 1022 determines the positional relationship between them.

For metal electrodes, the bottom metal electrode 103 and the top metal electrode 105 may be made of molybdenum (Mo), tungsten (W), or aluminum (Al) and other materials.

As shown in FIG. 4 , the bottom metal electrode 103 is located on the side of the acoustic wave reflection layer 102 away from the silicon carbide substrate 101 , and one end of the top metal electrode 105 extends along the sidewall of the piezoelectric functional layer 104 to the acoustic wave reflection layer 102 , and is connected with the acoustic wave reflection layer 102 . The bottom metal electrode 103 is flush. That is, one end of the top metal electrode 105 extends to the plane where the bottom metal electrode 103 is located. In this way, when the filter 100 chip is packaged, the packaging wiring of the top metal electrode 105 and the bottom metal electrode 103 can be realized on the same plane, which is more convenient for packaging wiring, and also saves the volume after packaging, thereby saving costs.

In this way, after one end of the top metal electrode 105 extends to the plane where the bottom metal electrode 103 is located, in order to realize the isolation between the top metal electrode 105 and the bottom metal electrode 103, an isolation area as shown in FIG. 4 is provided. The isolation can be achieved by filling with a dielectric material, which can be selected from silicon dioxide (SiO ₂ ).

It should be noted that, as shown in FIG. 4 , the isolation region is located between the acoustic wave reflection layer 102 and the piezoelectric functional layer 104 . The dielectric material of the isolation region is silicon dioxide, which can also be used as a bonding material, which can increase the adhesion between the piezoelectric functional layer 104 , the acoustic wave reflection layer 102 and the isolation region, thereby improving the structural stability and reliability of the filter 100 .

In order to meet the frequency requirements of the filter 100, the following relationship is satisfied between the frequency f, the phase θ, the sound speed v and the thickness t of the piezoelectric functional layer 104 of the filter:

It should be understood that the sound speed v is related to the material of the piezoelectric functional layer.

It should also be understood that the material of the piezoelectric functional layer 104 may be one of single crystal lithium niobate (LN), single crystal lithium tantalate (LT) or single crystal aluminum nitride (AlN). The material of the piezoelectric functional layer 104 is set to the material of single crystal. The single crystal material has higher crystal quality and fewer grain boundaries, which makes the sound propagation speed faster, thereby reducing the insertion loss of the filter and improving the filter performance. bandwidth. Since the frequency f has a proportional relationship with the sound propagation speed v, that is, f=V/λ (λ is the wavelength), the single crystal type of single crystal lithium niobate (LN), single crystal lithium tantalate (LT) or single crystal is used. The aluminum nitride (AlN) material can increase the frequency of the filter 100 and increase the bandwidth of the filter 100 , thereby improving the filtering performance of the filter 100 .

For the filter 100 shown in FIG. 4 , an embodiment of the present application further provides a manufacturing method applied to the filter 100 shown in FIG. 4 .

As shown in FIG. 5 , the manufacturing method applied to the filter 100 shown in FIG. 4 includes:

S501 , as shown in FIG. 6 , an acoustic wave reflection layer 102 is formed on one side of the silicon carbide substrate 101 .

As shown in FIG. 4 , the acoustic wave reflection layer 102 includes a plurality of low acoustic impedance layers 1021 and a plurality of high acoustic impedance layers 1022 arranged in layers, and the low acoustic impedance layers 1021 and the high acoustic impedance layers 1022 are alternately arranged. In this step, a layer of low acoustic impedance layer 1021 may be fabricated by sputtering process, then a layer of high acoustic impedance layer 1022 may be fabricated, then a layer of low acoustic impedance layer 1021 may be fabricated, and then a layer of high acoustic impedance layer 1022 may be fabricated , and so on, until the low acoustic impedance layer 1021 and the high acoustic impedance layer 1022 reach the required number of layers.

S502 , forming the bottom metal electrode 103 on the side of the acoustic wave reflection layer 102 away from the silicon carbide substrate 101 .

As shown in FIG. 7 , the bottom metal electrode 103 can be fabricated by a physical vapor deposition (PVD) process, and the bottom metal electrode 103 can be the same width as the silicon carbide substrate 101 and the acoustic wave reflection layer 102, so as to facilitate subsequent Production of hierarchical structures.

According to the filter 100 shown in FIG. 4 , the top metal electrode 105 of the filter 100 extends to the plane where the bottom metal electrode 103 is located, and on the plane where the bottom metal electrode 103 is located, the distance between the top metal electrode 105 and the bottom metal electrode 103 is There is an isolation region 106 in between, and the isolation region 106 is filled with a dielectric material.

Therefore, after the bottom metal electrode 103 is fabricated, photolithography and etching processes can be used to etch the bottom metal electrode 103 to form an isolation region 106 , and then a dielectric material such as silicon dioxide is deposited in the isolation region 106 . Next, a chemical mechanical polishing (chemical mechanical polishing, CMP) process may also be used to planarize the surfaces of the bottom metal electrode 103 and the isolation region 106 .

S503 , as shown in FIG. 8 , the piezoelectric functional layer 104 is bonded by wafer bonding on the side of the bottom metal electrode 103 away from the silicon carbide substrate 101 .

Since the top metal electrode 105 needs to be formed on the side of the piezoelectric functional layer 104 away from the silicon carbide substrate 101 later, and the top metal electrode 105 will extend to the plane where the bottom metal electrode 103 is located, in this step S503, the piezoelectric The functional layer 104 can only cover the bottom metal electrode 103 on one side of the isolation region 106 and the isolation region 106 , so that when the top metal electrode 105 is subsequently fabricated, the top metal electrode 105 is connected to the bottom metal electrode 103 on the other side of the isolation region 106 , and use it as the final top metal electrode 105 .

It should be understood that the piezoelectric functional layer 104 can be made of a prefabricated single crystal lithium niobate (LN) wafer, single crystal lithium tantalate (LT) wafer or single crystal aluminum nitride (AlN) wafer, using wafer bonding produced in a coherent manner.

In order to achieve a specific thickness of the piezoelectric functional layer 104, as shown in FIG. 9, ion implantation can be used, that is, a prefabricated single crystal lithium niobate (LN) wafer 400, single crystal lithium tantalate (LT) wafer 400 or single crystal aluminum nitride (AlN) wafer 400 is pre-cut, and then the pre-cut wafer 400 is bonded to the bottom metal electrode 103 and the isolation region 106 by wafer bonding, away from the silicon carbide substrate One side of 101 is heated at a high temperature to peel off the pre-cut wafer, so that the thickness of the piezoelectric functional layer 104 reaches a specific thickness, such as λ/2 thickness (where λ is 1000-2000 nanometers).

In order to achieve a specific thickness of the piezoelectric functional layer 104 , as shown in FIG. 10 , a mechanical thinning method can also be used, that is, a pre-fabricated single crystal lithium niobate (LN) wafer 400 , single crystal lithium tantalate (LT) The wafer 400 or single crystal aluminum nitride (AlN) wafer 400 is bonded to the bottom metal electrode 103 and the side of the isolation region 106 away from the silicon carbide substrate 101 by means of wafer bonding, and then is mechanically thinned. In this way, the thickness of the piezoelectric functional layer 104 can reach a specific thickness, such as a thickness of λ/2 (where λ is 1000-2000 nanometers).

It should be noted that the piezoelectric functional layer 104 is fabricated by a conventional deposition method, and the piezoelectric functional layer 104 is generally a polycrystalline material. To fabricate the piezoelectric functional layer 104 by wafer bonding, a wafer structure of lithium niobate (LN), lithium tantalate (LT) or aluminum nitride (AlN) may be fabricated first, and then the fabricated lithium niobate (LN) , The wafer structure of lithium tantalate (LT) or aluminum nitride (AlN) can be a single crystal material, and then the wafer structure of the single crystal piezoelectric functional layer 104 material is bonded to the bottom metal electrode 103 away from One side of the silicon carbide substrate 101 , so that the acoustic wave filter 100 can propagate and reflect in the single crystal piezoelectric functional layer 104 , thereby increasing the frequency of the filter 100 and further improving the filtering performance of the filter 100 .

S504 , a top metal electrode 105 is formed on the side of the piezoelectric functional layer 104 away from the silicon carbide substrate 101 .

After the bonding of the piezoelectric functional layer 104 is completed, the top metal electrode 105 may be formed by deposition using a PVD process. For the convenience of packaging, when depositing the top metal electrode 105, the deposition can be started on the bottom metal electrode 103 formed in the step S502, which does not cover the piezoelectric functional layer 104, and is deposited on the upper surface of the piezoelectric functional layer 104, so as to form such as: In the structure shown in FIG. 11 , the top metal electrode 105 extends to the acoustic wave reflection layer 102 and is flush with the bottom metal electrode 103 .

FIG. 12 is a schematic structural diagram of a filter provided by a second embodiment of the present application. As shown in FIG. 12 , the filter 200 includes a silicon carbide substrate and a piezoelectric functional layer 203 disposed on one side of the silicon carbide substrate. The silicon carbide substrate includes a first silicon carbide substrate portion 201 and a second silicon carbide substrate portion 202, and is formed between the first silicon carbide substrate portion 201, the second silicon carbide substrate portion 202 and the piezoelectric functional layer 203 cavity structure. A top metal electrode 205 is provided on the side of the piezoelectric functional layer 203 away from the silicon carbide substrate. A bottom metal electrode 204 is provided on the side of the piezoelectric functional layer 203 close to the silicon carbide substrate, and the bottom metal electrode 204 is located between the first silicon carbide substrate portion 201 , the second silicon carbide substrate portion 202 and the piezoelectric functional layer 203 within the cavity structure.

It should be noted that what is shown in FIG. 12 is a film bulk acoustic resonator (FBAR). In the filter 200, the sound wave can vibrate between the bottom metal electrode 204 and the top metal electrode 205, and the cavity under the bottom metal electrode 204 is used as an air reflection layer to realize total reflection, thereby realizing the function of filtering. It should be understood that the thickness of the piezoelectric functional layer 203 in the filter 200 may refer to the thickness of the piezoelectric functional layer 103 in the filter 100 described above, which will not be repeated here.

It should also be understood that, in the above filter 100, the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 can both be 4H, 6H, or 15R and other crystalline silicon carbide materials, which are usually semi-insulating carbide materials. Silicon substrate, resistance >1e5 ohm·cm (Ohm·cm), and its crystallographic deflection angle is 0 degrees to 8 degrees.

In the filter 200 device, silicon carbide is still used as the substrate material to achieve better heat dissipation and better temperature compensation, thereby reducing temperature drift, thereby increasing the power of the filter 200, so that it can be applied to more High-power application scenarios, such as small base stations or micro base stations in 5G.

In order to facilitate the bonding of the piezoelectric functional layer 203 to the silicon carbide substrate, the filter 200 further includes a bonding material layer 206 . The bonding material layer 206 is located between the silicon carbide substrate and the piezoelectric functional layer 203 . That is, the bonding material layer 206 is provided between the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 and the piezoelectric functional layer 203 . The piezoelectric functional layer 203 and the silicon carbide substrate are bonded through the bonding material layer 206 to improve the stability of the structure. Correspondingly, as shown in FIG. 12 , the side of the bonding material layer 206 close to the piezoelectric functional layer 203 is flush with the side of the bottom metal electrode 204 close to the piezoelectric functional layer 203 to facilitate the fabrication of the filter 200 .

Optionally, the material of the bonding material layer 206 may be silicon dioxide (SiO ₂ ), and the thickness of the bonding material layer 206 may be 0.1 μm to 5 μm.

In addition, as shown in FIG. 13 , both ends of the bottom metal electrode 204 extend to the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 along the sidewalls of the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 respectively. The bottom outer edge of the second silicon carbide substrate portion 202, so that both ends of the bottom metal electrode 204 extend from the cavity structure between the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 to the second silicon carbide substrate portion 202. The bottom outer edges of the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 facilitate wiring of the bottom metal electrode 204 during packaging, simplify the packaging process, and save costs.

It should also be understood that the filter 200 shown in FIG. 12 and FIG. 13 is similar to the filter 100 shown in FIG. 4 , and the material of the piezoelectric functional layer 203 can also be single crystal lithium niobate (LN), single crystal tantalic acid One of lithium (LT) or single crystal aluminum nitride (AlN) to improve the frequency and filtering performance of the filter 200 .

For the filter 200 shown in FIG. 12 and FIG. 13 , an embodiment of the present application further provides a manufacturing method applied to the filter 200 shown in FIG. 12 and FIG. 13 .

As shown in FIG. 14 , the manufacturing method applied to the filter 200 shown in FIG. 12 and FIG. 13 includes:

S1401 , forming a bonding material layer 206 and a bottom metal electrode 204 on one side of the silicon carbide substrate 500 .

As shown in FIG. 15, on one side of a complete silicon carbide substrate 500, the bonding material layer 206 may be deposited by a chemical vapor deposition (CVD) process, and then etched away by an etching process. The bonding material layer 206 at the middle position of the bottom 500 forms the structure shown in FIG. 16 .

Next, as shown in FIG. 17 , at the position where the bonding material layer 206 is removed by etching, a physical vapor deposition (PVD) process is used to deposit and form a bottom metal electrode 204, and then a CMP process is used to realize the bonding material layer 206 and the surface of the bottom metal electrode 204 are planarized.

S1402 , on the side of the bonding material layer 206 and the bottom metal electrode 204 away from the silicon carbide substrate 500 , bonding the piezoelectric functional layer 203 by wafer bonding.

As shown in FIG. 18 , after the surfaces of the bonding material layer 206 and the bottom metal electrode 204 are planarized, prefabricated single crystal lithium niobate (LN) wafers, single crystal lithium tantalate (LT) wafers or A single crystal aluminum nitride (AlN) wafer is bonded to the side of the bonding material layer 206 and the bottom metal electrode 204 away from the silicon carbide substrate 500 as the piezoelectric functional layer 203 . In order to achieve a specific thickness of the piezoelectric functional layer 203 , as shown in FIGS. 19 and 20 , ion implantation or mechanical thinning may be used. For details, refer to step S503 shown in FIG. 5 , which will not be repeated here.

S1403 , forming the top metal electrode 205 on the side of the piezoelectric functional layer 203 away from the silicon carbide substrate 500 .

As shown in FIG. 21 , after the wafer bonding of the piezoelectric functional layer 203 is completed, the top metal electrode 205 may be fabricated by a PVD deposition process.

S1404, etching from the bottom of the silicon carbide substrate 500 to form a first silicon carbide substrate portion 201 and a second silicon carbide substrate portion 202, and making the bottom metal electrode 204 located between the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202 within the cavity structure of the silicon carbide substrate portion 202 .

As shown in FIG. 22, the etching can be started from the bottom of the silicon carbide substrate 500, and the etching area is sufficient to expose the bottom metal electrode 204, so that the acoustic wave can propagate and reflect in the piezoelectric functional layer 203, and the bottom metal electrode 204 can be exposed. The lower surface of the metal electrode 204 is an air boundary to achieve total reflection.

In order to facilitate packaging, both ends of the bottom metal electrode 204 can be extended to the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 201 along the sidewalls of the second silicon carbide substrate portion 202 respectively. Bottom outer edge of silicon carbide substrate portion 202 to facilitate package wiring. Optionally, the method shown in FIG. 15 may further include:

S1405, as shown in FIG. 23, the sidewall of the cavity structure between the first silicon carbide substrate portion 201 and the second silicon carbide substrate portion 202, and the first silicon carbide substrate portion 201 and the second silicon carbide liner The bottom metal electrode 204 is formed on the side of the bottom portion 202 away from the piezoelectric functional layer.

FIG. 24 is a schematic structural diagram of a filter provided by a third embodiment of the present application. As shown in FIG. 24 , the filter 300 includes a piezoelectric functional layer 303 and a metal electrode 304 on one side of the piezoelectric functional layer 303 . A silicon carbide substrate 301 is provided on the side of the piezoelectric functional layer 303 away from the metal electrode 304 , and a bonding material layer 302 is provided between the silicon carbide substrate 301 and the piezoelectric functional layer 303 . The metal electrode 304 includes a plurality of interdigitated transducers (IDTs), and the width of each interdigital transducer IDT may be 100 nanometers to 1000 nanometers. The distance can be 0.5 microns to 1 micron.

It should be noted that what is shown in FIG. 24 is a surface acoustic wave filter (surface acoustic wave filters, SAW filters). In the filter 300, the interdigital transducer IDT in the metal electrode 304 converts the electrical signal into a sound signal to form a mechanical vibration wave, which propagates on the surface of the piezoelectric functional layer 203, and then is converted by another interdigital transducer IDT It is the electrical signal output, so as to realize the function of filtering.

It should be understood that the silicon carbide (SiC) substrate 301 can be a crystalline type of silicon carbide (SiC) material such as 4H, 6H, or 15R, which is usually a semi-insulating silicon carbide substrate with a resistance > 1e5 ohm·cm (Ohm·cm ), the crystallographic declination is 0° to 8°.

In the filter 300 device, silicon carbide is still used as the substrate material to achieve better heat dissipation and better temperature compensation, thereby reducing temperature drift, thereby increasing the power of the filter 300, so that it can be applied to more High-power application scenarios, such as small base stations or micro base stations in 5G.

In the filter 300 shown in FIG. 24 , the thickness of the bonding material layer 302 can be 0.1 μm to 5 μm, and the material of the bonding material layer 302 can be selected from silicon dioxide (SiO ₂ ) or metal.

It should also be understood that the filter 300 shown in FIG. 24 is similar to the filter 100 shown in FIG. 4 , and the material of the piezoelectric functional layer 303 can also be single crystal lithium niobate (LN), single crystal lithium tantalate (LT) ) or single crystal aluminum nitride (AlN) to improve the frequency and filtering performance of the filter 300.

For the filter 300 shown in FIG. 24 , an embodiment of the present application further provides a manufacturing method applied to the filter 300 shown in FIG. 24 .

As shown in FIG. 25 , the manufacturing method applied to the filter 300 shown in FIG. 24 includes:

S2501 , forming a bonding material layer 302 on one side of the silicon carbide substrate 301 .

As shown in FIG. 26, on one side of a complete silicon carbide substrate 301, a bonding material layer 302 may be deposited by a chemical vapor deposition (CVD) process.

S2502 , bonding the piezoelectric functional layer 303 on the side of the bonding material layer 302 away from the silicon carbide substrate 301 .

As shown in FIG. 27 , after the surface of the bonding material layer 302 is planarized, a prefabricated single crystal lithium niobate (LN) wafer, single crystal lithium tantalate (LT) wafer or single crystal aluminum nitride (AlN) wafer, which is bonded to the side of the bonding material layer 302 away from the silicon carbide substrate 301 as the piezoelectric functional layer 303 . In order to achieve a specific thickness of the piezoelectric functional layer 303, as shown in FIG. 28 and FIG. 29, ion implantation or mechanical thinning may be used. For details, please refer to step S503 shown in FIG. 5, which will not be repeated here.

S2503 , forming a metal electrode 304 on the side of the piezoelectric functional layer 303 away from the silicon carbide substrate 301 .

As shown in FIG. 30 , a metal electrode 304 can be deposited on the side of the piezoelectric functional layer 303 away from the silicon carbide substrate 301 by a PVD process, and then a photolithography process or a lift off process can be used to form a plurality of spacers. The interdigitated transducer (inter digitated transducer, IDT).

In the specific application, as shown in Figure 31, the filters shown in Figure 24 can be interconnected. For example, a ladder-type interconnection structure is used to obtain a combined filter by connecting three filters in series and three filters in parallel. filter to achieve high-power filtering. FIG. 32 is a filter graph of the filter shown in FIG. 31 . As shown in Figure 32, the working frequency of the filter shown in Figure 31 is 2.6 GHz, which can meet the frequency and filtering requirements of the filter in the 5G base station.

In the several embodiments provided in this application, it should be understood that the disclosed circuits and methods may be implemented in other manners. For example, the circuit embodiments described above are only illustrative. For example, the described division of modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components. It may be incorporated or integrated into another device, or some features may be omitted, or not implemented.

The units described as separate components may or may not be physically separated, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place, or may be distributed to multiple different places . Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

Finally, it should be noted that: the above are only specific embodiments of the present application, but the protection scope of the present application is not limited to this, and any changes or replacements within the technical scope disclosed in the present application should be covered by the present application. within the scope of protection of the application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims (21)

1. A filter, characterized in that, comprising:

   Silicon carbide substrate;

   an acoustic wave reflection layer disposed on one side of the silicon carbide substrate;

   a metal electrode disposed on the side of the acoustic wave reflection layer away from the silicon carbide substrate;

   The metal electrode includes a bottom metal electrode and a top metal electrode; and a piezoelectric functional layer is arranged between the bottom metal electrode and the top metal electrode.
2. The filter according to claim 1, wherein the acoustic wave reflection layer comprises a plurality of low acoustic impedance layers and a plurality of high acoustic impedance layers arranged in layers, and the low acoustic impedance layer and the high acoustic impedance layer The layers are alternately set.
3. The filter according to claim 1 or 2, wherein the bottom metal electrode is located on the side of the acoustic wave reflection layer away from the silicon carbide substrate, and one end of the top metal electrode is located along the piezoelectric The sidewall of the functional layer extends to the sound wave reflection layer and is flush with the bottom metal electrode.
4. The filter according to claim 3, wherein on the plane where the bottom metal electrode is located, an isolation region is formed between the bottom metal electrode and the top metal electrode, and the isolation region is filled with a medium Material.
5. The filter according to claim 4, wherein the dielectric material is silicon dioxide.
6. The filter according to any one of claims 1 to 5, wherein the material of the piezoelectric functional layer is one of single crystal lithium niobate, single crystal lithium tantalate or single crystal aluminum nitride.
7. A filter, characterized in that, comprising:

   Silicon carbide substrate;

   a piezoelectric functional layer disposed on one side of the silicon carbide substrate;

   The silicon carbide substrate includes a first silicon carbide substrate portion and a second silicon carbide substrate portion, and the first silicon carbide substrate portion, the second silicon carbide substrate portion and the piezoelectric functional layer A cavity structure is formed between;

   The piezoelectric functional layer is provided with a top metal electrode on one side away from the silicon carbide substrate;

   One side of the piezoelectric functional layer close to the silicon carbide substrate is provided with a bottom metal electrode, and the bottom metal electrode is located at the first silicon carbide substrate part and the second silicon carbide substrate part in the cavity structure between the piezoelectric functional layer.
8. The filter according to claim 7, wherein the filter further comprises a bonding material layer, the bonding material layer is located between the piezoelectric functional layer and the silicon carbide substrate, and the The side of the bonding material layer close to the piezoelectric functional layer is flush with the side of the bottom metal electrode close to the piezoelectric functional layer.
9. The filter according to claim 8, wherein the material of the bonding material layer is silicon dioxide.
10. The filter according to claim 8 or 9, wherein the thickness of the bonding material layer is 0.1 micrometers to 5 micrometers.
11. The filter according to any one of claims 7 to 10, wherein the two ends of the bottom metal electrode are respectively along the first silicon carbide substrate portion and the second silicon carbide substrate portion. sidewalls extending to bottom outer edges of the first silicon carbide substrate portion and the second silicon carbide substrate portion.
12. The filter according to any one of claims 7 to 11, wherein the material of the piezoelectric functional layer is one of single crystal lithium niobate, single crystal lithium tantalate or single crystal aluminum nitride.
13. A method of making a filter, the method comprising:

    Make a sound wave reflection layer on one side of the silicon carbide substrate;

    making a bottom metal electrode on the side of the acoustic wave reflection layer away from the silicon carbide substrate;

    On the side of the bottom metal electrode away from the silicon carbide substrate, the piezoelectric functional layer is bonded by wafer bonding;

    A top metal electrode is formed on the side of the piezoelectric functional layer away from the silicon carbide substrate.
14. The manufacturing method according to claim 13, wherein the method further comprises:

    An isolation region is formed by etching on the bottom metal electrode, and a dielectric material is deposited in the isolation region.
15. The manufacturing method according to claim 13 or 14, wherein the piezoelectric functional layer is bonded by wafer bonding on the side of the bottom metal electrode away from the silicon carbide substrate, comprising: :

    Pre-cutting the wafer made of the piezoelectric functional layer material by means of ion implantation;

    bonding the pre-cut wafer to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding;

    The pre-cut wafer is peeled off so that the thickness of the piezoelectric functional layer meets the designed thickness of the piezoelectric functional layer.
16. The manufacturing method according to claim 13 or 14, wherein the piezoelectric functional layer is bonded by wafer bonding on the side of the bottom metal electrode away from the silicon carbide substrate, comprising:

    bonding the wafer made of the piezoelectric functional layer material to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding;

    By means of mechanical thinning, the thickness of the piezoelectric functional layer can meet the designed thickness of the piezoelectric functional layer.
17. A method of making a filter, the method comprising:

    Making a bonding material layer and a bottom metal electrode on one side of the silicon carbide substrate;

    On the side of the bonding material layer and the bottom metal electrode away from the silicon carbide substrate, the piezoelectric functional layer is bonded by wafer bonding;

    Making a top metal electrode on the side of the piezoelectric functional layer away from the silicon carbide substrate;

    By etching from the bottom of the silicon carbide substrate, a first silicon carbide substrate portion and a second silicon carbide substrate portion are formed, and the bottom metal electrode is located between the first silicon carbide substrate portion and the second silicon carbide substrate portion. within the cavity structure between the silicon carbide substrate portions.
18. The manufacturing method according to claim 17, wherein the method further comprises:

    the sidewalls of the cavity structure between the first silicon carbide substrate portion and the second silicon carbide substrate portion, and the first silicon carbide substrate portion and the second silicon carbide substrate Part of the side away from the piezoelectric functional layer is made of the bottom metal electrode.
19. The manufacturing method according to claim 17 or 18, wherein the bonding material layer and the bottom metal electrode are bonded by wafer bonding on the side away from the silicon carbide substrate. Combined piezoelectric functional layer, including:

    Pre-cutting the wafer made of the piezoelectric functional layer material by means of ion implantation;

    Bonding the pre-cut wafer to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding;

    The pre-cut wafer is peeled off so that the thickness of the piezoelectric functional layer meets the designed thickness of the piezoelectric functional layer.
20. The manufacturing method according to claim 17 or 18, wherein the bonding material layer and the bottom metal electrode are bonded by wafer bonding on the side away from the silicon carbide substrate. Combined piezoelectric functional layer, including:

    bonding the wafer made of the piezoelectric functional layer material to the side of the bottom metal electrode away from the silicon carbide substrate by wafer bonding;

    By means of mechanical thinning, the thickness of the piezoelectric functional layer can meet the designed thickness of the piezoelectric functional layer.
21. An electronic device, characterized in that an antenna PCB board, multiple antennas, and multiple filters are coupled to the antenna PCB board, and the filters are A filter as claimed in any one of claims 1 to 12.

Images