GaN grain and control circuit heterogeneous integration structure applied to high-power microwave module and preparation method thereof

Abstract

The application belongs to the technical field of semiconductor system package (SiP), and specifically discloses a GaN crystal grain and control circuit heterogeneous integration structure applied to a high-power microwave module and a preparation method thereof. The GaN high electron mobility transistor power crystal grain and the CMOS control crystal grain are heterogeneously integrated on the same packaging substrate, a horizontal coplanar configuration is adopted to match a short-path interconnection structure, direct electrical connection between the crystal grains is realized through a redistribution layer (RDL) or a metal wire, the physical path length is less than 2 mm, and parasitic inductance and signal loss are greatly reduced; the top surface structure is completely covered with a packaging adhesive material, and an integrated heterogeneous integration package is formed. The application effectively improves the switching speed, high-frequency response and transmission efficiency of the high-power microwave module, simultaneously realizes device miniaturization, high reliability and system-level integration, and is suitable for high-power microwave application scenarios such as radar, communication and electromagnetic radiation.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor packaging and high-power microwave device technology, and particularly relates to a heterogeneous integration structure of GaN grain and control circuit for use in high-power microwave modules and its fabrication method. Background Technology

[0002] High-power microwave modules are core components of electronic equipment such as radar systems, satellite communications, and electromagnetic countermeasures. Their power amplification units generally use gallium nitride (GaN) high electron mobility transistors (HEMTs), which have significant advantages such as high frequency, high voltage, and high power density.

[0003] Traditional high-power microwave equipment typically employs a discrete layout: the GaN power amplifier and control circuitry are placed on different circuit boards or in separate packages, interconnected via long PCB traces or external leads. This structure has the following technical drawbacks: (1) The signal transmission path is too long, which leads to a significant increase in parasitic inductance, limiting the microwave pulse switching speed and system response time; (2) Under high-frequency and high-voltage operating conditions, long interconnects cause signal attenuation, crosstalk and reflection, which deteriorate signal integrity; (3) The discrete layout occupies a large volume, which is not conducive to module miniaturization and high-density integration; (4) The multiple connection and assembly steps reduce the overall reliability and yield.

[0004] Currently, there is no heterogeneous integration solution for GaN power chips and CMOS control circuits specifically designed for high-power microwave applications, which cannot simultaneously meet the comprehensive requirements of high-frequency performance, high power capacity, miniaturization, and high reliability. Therefore, there is an urgent need to design a heterogeneous integration structure for GaN chips and control circuits that features miniaturization, low parasitics, high-frequency response, and high reliability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing high-power microwave modules, such as large parasitic inductance, high signal loss, slow response speed, and large size caused by discrete layout. It provides a miniaturized, low parasitic, high-frequency response, and high-reliability GaN die and control circuit heterogeneous integration structure. Through heterogeneous integration within a single package and short-path interconnection, the high-power microwave transmission efficiency and system stability are improved.

[0006] To achieve the above objectives, the present invention provides a heterogeneous integration structure of GaN chips and control circuits for high-power microwave modules, comprising a packaging substrate, at least one GaN power chip, at least one control chip, a short-path interconnect structure, and a packaging material; the packaging substrate has metal conduction pillars and redistribution layer (RDL) lead areas inside, and a chip bonding area is provided on the top surface; the GaN power chip is disposed on the top surface of the packaging substrate corresponding to the bonding area; the control chip and the GaN power chip are horizontally arranged side by side and coplanarly disposed on the same top surface of the packaging substrate; the GaN power chip and the control chip are electrically connected through the short-path interconnect structure, and the physical path length of the short-path interconnect structure is less than 2 mm; the packaging material covers the GaN power chip, the control chip, the short-path interconnect structure, and the top surface of the packaging substrate, together constituting a heterogeneous integration structure of a single system package (SiP).

[0007] Furthermore, in this invention, the GaN power chip is a GaN high electron mobility transistor (HEMT) chip, and the control chip is a CMOS control chip. Furthermore, in this invention, the short-path interconnect structure employs an internal redistribution layer (RDL) or a top surface metal conductor to achieve direct electrical connection between the GaN power chip and the control chip.

[0008] Furthermore, in this invention, the encapsulating material is an epoxy molding compound, which completely covers the GaN power die, control die, interconnect structure and top surface of the encapsulation substrate, exposing only the bottom electrical connection area of ​​the substrate.

[0009] Furthermore, in this invention, the packaging substrate is a high-frequency low-loss ceramic substrate or an organic high-frequency substrate.

[0010] Furthermore, in this invention, the GaN power die is fixed to the packaging substrate by eutectic bonding or conductive adhesive.

[0011] Furthermore, in this invention, the control die is fixed to the packaging substrate by eutectic bonding or conductive adhesive.

[0012] Furthermore, in this invention, the control chip is a CMOS silicon-based semiconductor chip material used to drive, modulate, and protect the GaN power chip.

[0013] The present invention also provides a method for fabricating the above-mentioned heterogeneous integration structure of GaN grains and control circuits for use in high-power microwave modules, which specifically includes the following steps: Step S1: Provide a packaging substrate and preprocess the packaging substrate.

[0014] Step S2: At least one GaN power chip is mounted on the top surface of the packaging substrate and electrical connection is completed.

[0015] Step S3: At least one CMOS control die is mounted on the top surface of the packaging substrate at a position that is horizontally parallel and coplanar with the GaN power die, and electrical connection is completed.

[0016] Step S4: Fabricate a short-path interconnect structure to electrically connect the GaN power die and the control die, and the physical path length of the short-path interconnect structure is less than 2 mm.

[0017] Step S5: Use encapsulation material to integrally mold and encapsulate the GaN power die, control die, short-path interconnect structure and the top surface of the encapsulation substrate to form a single system package (SiP) heterogeneous integrated structure.

[0018] Furthermore, this invention also includes the following steps: Step S6: Perform post-curing and stress relief treatment on the molded and packaged structure, and then conduct appearance and dimensional inspection, electrical performance testing and reliability screening in sequence.

[0019] This invention relates to a heterogeneous integration structure for GaN chips and control circuits in high-power microwave modules. It integrates gallium nitride (GaN) high electron mobility transistor power chips and CMOS control chips onto the same packaging substrate, employing a horizontal coplanar configuration and a short-path interconnect structure. Direct electrical connections between chips are achieved through redistribution layers (RDLs) or metal wires, with a physical path length of less than 2mm, significantly reducing parasitic inductance and signal loss. The top surface structure is completely encapsulated with encapsulating material, forming an integrated heterogeneous package. This invention effectively improves the switching speed, high-frequency response, and transmission efficiency of high-power microwave modules, while achieving device miniaturization, high reliability, and system-level integration. It is suitable for high-power microwave applications such as radar, communication, and electromagnetic radiation. Compared with existing technologies, this invention has the following advantages: (1) Heterogeneous integration and miniaturization: GaN power chips and CMOS control chips are integrated into a single SiP package, eliminating long-distance external interconnects, realizing module miniaturization and high-density integration, and adapting to the needs of miniaturized radar, portable communication equipment and miniaturized electromagnetic interference devices.

[0020] (2) Short path interconnection and low parasitics: The interconnection path between the chips is less than 2 mm, which significantly reduces parasitic inductance, capacitance and signal loss, improves microwave pulse switching speed and high frequency response capability, and is compatible with high frequency microwave radar, pulse communication system and radio frequency front-end transceiver module.

[0021] (3) Signal integrity improvement: Reduce signal reflection and crosstalk, improve signal quality in high power and high frequency environments, improve microwave transmission efficiency, and adapt to 5G / 6G base stations, satellite communication radio frequency units and high-precision detection radar.

[0022] (4) High reliability and high yield: Reduced assembly process, full coverage protection with encapsulation material, adaptable to harsh working conditions such as high temperature, high humidity, and high vibration, greatly improving yield and reliability, and suitable for vehicle radar, aerospace vehicles, and industrial high temperature and high humidity industrial control microwave modules.

[0023] (5) High versatility: It is compatible with various GaN specifications and CMOS control chips, and can be directly applied to high-power microwave modules for both military and civilian use, such as radar, communication, and electromagnetic countermeasures. Attached Figure Description

[0024] The specific embodiments of the present invention will be further explained below with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the heterogeneous integration structure of GaN grains and control circuits applied to high-power microwave modules according to the present invention.

[0026] Figure 2 This is a flowchart illustrating the fabrication method of the heterogeneous integration structure of GaN grains and control circuits for use in high-power microwave modules according to the present invention.

[0027] Figure 3 This is a schematic diagram of the packaging substrate in the fabrication method of the heterogeneous integration structure of GaN grains and control circuits for high-power microwave modules according to the present invention.

[0028] Figure 4 This is a schematic diagram of the structure completed by eutectic welding and conductive adhesive curing in the fabrication method of the heterogeneous integration structure of GaN grains and control circuits for high-power microwave modules according to the present invention.

[0029] Figure 5 This is a schematic diagram illustrating the short-path interconnect fabrication process in the method for fabricating a heterogeneous integrated structure of GaN grains and control circuits for high-power microwave modules according to the present invention.

[0030] Figure 6 This is a schematic diagram of the molding and packaging process in the fabrication method of the heterogeneous integration structure of GaN grains and control circuits for high-power microwave modules according to the present invention.

[0031] In the figure: 10 - Packaging substrate; 20 - GaN power die; 30 - Control die; 40 - Short-path interconnect structure; 50 - Packaging adhesive. Detailed Implementation Example 1

[0032] Combination Figure 1As shown, the heterogeneous integration structure of GaN die and control circuit applied to high-power microwave modules in this embodiment includes a packaging substrate 10, a GaN power die 20, a control die 30, a short-path interconnect structure 40, and a packaging adhesive 50.

[0033] Preferably, in this embodiment, the packaging substrate 10 is an alumina (Al2O3) high-frequency ceramic substrate with dimensions of 6 mm × 4 mm × 0.5 mm and a thermal conductivity of 25 W / (m·K). The packaging substrate 10 contains metal conductive pillars and a redistribution layer (RDL) with a linewidth of 30 μm. The bottom of the packaging substrate 10 has an array of pads for electrical connection to the external HPM motherboard.

[0034] In this embodiment, preferably, the GaN power die 20 is a GaN HEMT power die with a size of 2 mm × 1 mm. The die is fixed to the top left side region of the packaging substrate 10 by eutectic bonding, the eutectic bonding temperature is 220 ℃, and the solder is AuSn alloy.

[0035] In this embodiment, preferably, the control chip 30 is a CMOS driver control chip with a size of 1.5 mm × 1 mm. The control chip 30 is mounted to the right side of the top surface of the packaging substrate 10 using conductive adhesive, and is horizontally arranged side-by-side with the GaN power chip 20, with a center-to-center distance of 1.2 mm. After mounting, it is cured in an oven to allow the conductive adhesive to form a stable conductive path.

[0036] In this embodiment, preferably, the short-path interconnect structure 40 utilizes the redistribution layer (RDL) inside the package substrate 10 to achieve electrical connection between the GaN power die 20 and the control die 30. Specifically, the gate, drain, and source pads of the GaN power die 20 are connected to the RDL lines through micro-pads on the surface of the package substrate 10, and the RDL lines are then connected to the corresponding drive signal output pads of the control die 30. The physical length of the entire interconnect path (measured along the RDL trace from the pads of the GaN die 20 to the pads of the control die 30) is 1.6 mm, less than 2 mm.

[0037] In this embodiment, preferably, the encapsulating material 50 is made of high-temperature resistant epoxy molding compound (EMC), which completely covers the GaN power die 20, control die 30, short-path interconnect structure 40, and the entire top surface of the encapsulation substrate 10 through a molding process. The encapsulating material is 1.2 mm thick, with only the pads at the bottom of the encapsulation substrate 10 exposed. After molding, post-curing is performed at a curing temperature of 150°C for 2 hours to release stress and improve cross-linking.

[0038] The performance of the heterogeneous integration structure of GaN die and control circuit applied to the high-power microwave module in this embodiment was tested. The test results are as follows: parasitic inductance is reduced by more than 75% compared with the traditional discrete layout; microwave pulse rise time is less than 2 ns; high frequency loss is less than 0.3 dB; and the module size is reduced by 60% compared with the traditional solution. Example 2

[0039] The heterogeneous integration structure of GaN die and control circuit applied to high-power microwave modules in this embodiment is miniaturized and optimized based on Embodiment 1, specifically as follows: In this embodiment, preferably, the packaging substrate 10 is an organic high-frequency BT substrate with dimensions of 4mm × 3mm × 0.4mm. The packaging substrate 10 has internal metal conductive pillars and a fine metal wiring layer on its top surface.

[0040] In this embodiment, preferably, the GaN power chip 20 is a GaN HEMT power chip with a size of 1.5 mm × 0.8 mm, which is fixed to the left side of the top surface of the packaging substrate 10 by conductive silver paste.

[0041] In this embodiment, preferably, the control chip 30 is a CMOS control chip with a size of 1 mm × 0.8 mm. It is attached to the right side of the top surface of the packaging substrate 10 with conductive adhesive, and is horizontally parallel and coplanar with the GaN power chip 20, with a center distance of 0.9 mm between them.

[0042] In this embodiment, preferably, the short-path interconnect structure 40 is directly connected using top-surface metal wires. Specifically, after the die is mounted, the gate pad of the GaN power die 20 is directly connected to the corresponding drive output pad of the control die 30 using a 25 μm diameter gold wire through an automated gold wire bonding device. The physical length of the interconnect path (gold wire arc length) is 1.2 mm, which is less than 2 mm.

[0043] In this embodiment, preferably, the encapsulating material 50 is made of low-stress epoxy molding compound with a temperature resistance of ≥150 ℃. After molding and encapsulation, the material completely covers the grains and bonding wires, and the bottom surface of the encapsulation substrate 10 is exposed.

[0044] The performance of the heterogeneous integration structure of GaN die and control circuit applied to the high-power microwave module in this embodiment was tested. The test results are as follows: the high-frequency response bandwidth is improved by 40% compared with the traditional discrete layout; the signal isolation (adjacent channels) is ≥60dB; the module volume is only about 35% of the traditional solution, which is suitable for portable high-power microwave equipment. Example 3

[0045] Combination Figure 2As shown, the fabrication method of the heterogeneous integration structure of GaN grains and control circuits for high-power microwave modules in this embodiment specifically includes the following steps: Step S1: Provide a packaging substrate 10, the structure of which is as follows: Figure 3 As shown, the packaging substrate 10 is pretreated to clean the surface and activate the bonding area to ensure reliable die bonding.

[0046] Specifically, in this embodiment, the pretreatment steps include: first, ultrasonically cleaning the 96% alumina ceramic substrate (40 kHz, 25 ℃, 5 min), then rinsing with pure water (twice, 2 min each time), then drying with a hot plate (100 ℃, 10 min), and finally cooling to room temperature with high-purity nitrogen gas to ensure that the surface cleanliness of the encapsulation substrate 10 is Class 1000, free of particles, watermarks, oil stains, and dust.

[0047] Step S2: At least one GaN power chip 20 is mounted on the top surface of the packaging substrate 10 and electrical connection is completed.

[0048] Specifically, in this embodiment, the GaN die 20 mounting and soldering includes: under vacuum and anti-static conditions, using a die bonder to vacuum adsorb and load the GaN die 20, with a nozzle pressure of 0.1 MPa ~ 0.3 MPa, optical alignment correction for offset, offset accuracy ±5 μm, mounting after alignment of GaN pads, eutectic soldering for 10 s under nitrogen protection at 220℃ and 0.5 MPa, GaN shear strength ≥5 N, and no cold solder joints.

[0049] Step S3: At least one control die 30 is mounted on the top surface of the packaging substrate 10 at a position that is horizontally parallel and coplanar with the GaN power die 20, and electrical connection is completed.

[0050] The controlled die curing process includes: vacuum adsorption loading of CMOS wafers using a die bonder in a vacuum and anti-static environment, with a nozzle pressure of 0.1 MPa ~ 0.3 MPa, optical alignment correction for offset with an offset accuracy of ±5 μm, application of conductive adhesive to the CMOS pads after alignment and mounting, and curing in a 150 ℃ oven for 30 min after alignment. The CMOS shear strength is ≥3 N, with no debonding or excess adhesive contaminating the circuit.

[0051] Structures that have completed eutectic bonding and conductive adhesive curing, such as Figure 4 As shown.

[0052] Step S4: Fabricate a short-path interconnect structure 40 to electrically connect the GaN power die 20 and the control die 30, achieving low parasitic electrical connection between GaN and the CMOS die. The physical path length of the short-path interconnect structure 40 is less than 2 mm. Figure 5 As shown.

[0053] In this embodiment, the substrate RDL (coating photoresist → exposure → development → sputtering → etching → resist removal, line width 20 μm ~ 40 μm) or 25 μm gold wire (arc height 80 μm) is used for wire bonding. The interconnect length is controlled to be <2 mm, the interconnect resistance is ≤50 mΩ, and there are no broken wires, short circuits, or fallen wires. The interconnect path avoids the edge of the die to prevent scratching the die surface.

[0054] Step S5: Use encapsulating adhesive 50 to integrally mold and encapsulate the GaN power die 20, control die 30, short-path interconnect structure 40, and the top surface of the packaging substrate 10, forming a heterogeneous integrated single-system package (SiP) structure, such as... Figure 6 As shown. This protects the die and interconnect structure, improving mechanical and environmental reliability.

[0055] In this embodiment, the sealing process specifically includes: first, placing the product into the mold cavity, preheating the sealing compound, and applying a vacuum; then, transferring the molding material, maintaining pressure, and curing; finally, demolding and removing excess material and burrs. Epoxy molding compound is used, and the molding process is carried out at 150℃~175℃ and 5MPa~8MPa, with curing time of 60 min~90 min. The sealed surface should be smooth and free of pores, cracks, and delamination; there should be no excess material contaminating the interface; the mold must be clean to prevent air bubbles and insufficient encapsulation.

[0056] Furthermore, this invention also includes the following steps: Step S6: Perform post-curing and stress relief treatment on the molded and packaged structure to improve the cross-linking degree of the sealant, stabilize dimensions and reliability. First, place the product on a high-temperature resistant tray, then perform gradient temperature curing. In this embodiment, two-stage heating is used: first, maintain at 120 ℃ for 2 hours, then maintain at 150 ℃ for 4 hours; finally, allow it to cool naturally to room temperature to release stress. The final packaged structure is as follows. Figure 1 As shown, the encapsulation should be free of yellowing and warping; hardness ≥ D80; then, the appearance and dimensions should be inspected sequentially to remove defective products and ensure that the dimensions meet the specifications: check for cracks, bubbles, burrs, and dirt; measure the length, width, height, encapsulation thickness, and pin positions; sort OK / NG products; finally, electrical performance testing should be performed to verify continuity, parasitic inductance, high frequency, isolation, and function. Probe contact test pads should be performed to test connectivity, insulation, parasitic inductance, and reliability screening. High frequency S-parameter and isolation tests should be performed, with continuity resistance ≤ 100 mΩ, parasitic inductance ≤ 1 nH, and isolation ≥ 60 dB. The temperature should be cycled 100 times from -40 ℃ to 125 ℃, and the data should be automatically recorded and judged.

[0057] Many specific details have been set forth in the foregoing description to provide a thorough understanding of the present invention. However, the above description is merely a preferred embodiment of the present invention, and the present invention can be implemented in many other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed above. Furthermore, any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A heterogeneous integration structure of GaN die and control circuit for use in high-power microwave modules, characterized in that: The package includes a packaging substrate, at least one GaN power die, at least one control die, a short-path interconnect structure, and a packaging adhesive. The packaging substrate has metal conductive pillars and a redistribution layer lead area inside, and a die bonding area on its top surface. The GaN power die is disposed on the top surface of the packaging substrate in the corresponding bonding area. The control die and the GaN power die are horizontally arranged side by side and coplanarly disposed on the same top surface of the packaging substrate. The GaN power die and the control die are electrically connected through the short-path interconnect structure, and the physical path length of the short-path interconnect structure is less than 2 mm. The packaging adhesive covers the GaN power die, the control die, the short-path interconnect structure, and the top surface of the packaging substrate, together forming a heterogeneous integrated structure for a single system package.

2. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The GaN power chip is a GaN high electron mobility transistor chip, and the control chip is a CMOS control chip.

3. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The short-path interconnect structure uses an internal redistribution layer or a top surface metal conductor on the packaging substrate to achieve direct electrical connection between the GaN power chip and the control chip.

4. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The encapsulating material is an epoxy molding compound that completely covers the GaN power die, control die, interconnect structure, and top surface of the encapsulation substrate, with only the bottom electrical connection area of ​​the substrate exposed.

5. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The packaging substrate is a high-frequency, low-loss ceramic substrate or an organic high-frequency substrate.

6. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The GaN power die is fixed to the packaging substrate by eutectic bonding or conductive adhesive.

7. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The control die is fixed to the packaging substrate by eutectic bonding or conductive adhesive.

8. The heterogeneous integration structure of GaN die and control circuit for high-power microwave modules according to claim 1, characterized in that: The control chip is a CMOS silicon-based semiconductor chip material used to drive, modulate, and protect GaN power chips.

9. A method for fabricating a heterogeneous integrated structure of GaN grains and control circuits for use in high-power microwave modules, characterized in that: Includes the following steps: Step S1: Provide a packaging substrate and preprocess the packaging substrate; Step S2: At least one GaN power die is mounted on the top surface of the packaging substrate and electrical connection is completed; Step S3: At least one CMOS control die is mounted on the top surface of the packaging substrate at a position that is horizontally parallel and coplanar with the GaN power die, and electrical connection is completed; Step S4: Fabricate a short-path interconnect structure to electrically connect the GaN power die and the control die, and the physical path length of the short-path interconnect structure is less than 2 mm; Step S5: Use encapsulation adhesive to integrally mold and encapsulate the GaN power die, control die, short-path interconnect structure and the top surface of the encapsulation substrate to form a single-system package heterogeneous integrated structure.

10. The method for fabricating a heterogeneous integrated structure of GaN grains and control circuits for use in high-power microwave modules according to claim 9, characterized in that: It also includes the following steps: Step S6: Perform post-curing and stress relief treatment on the molded and packaged structure, and then conduct appearance and dimensional inspection, electrical performance testing and reliability screening in sequence.

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