A GaN radio frequency device and a method of testing the same

Abstract

The application discloses a GaN radio frequency device and a testing method thereof. The GaN radio frequency device structure comprises a substrate, a gallium nitride buffer layer, a gallium nitride main body layer, a barrier layer and an insulation layer. The top surface of the insulation layer is provided with two types of through holes with different opening shapes. Ohmic contacts are formed by filling conductive materials in different target areas to test the device performance under different electrode configurations. This design allows researchers to flexibly try various electrode size and position combinations on the same GaN radio frequency device, without the need to prepare multiple GaN radio frequency devices with different sizes, thereby significantly reducing material consumption and labor cost, simplifying the process flow, shortening the research and development cycle, and improving the research and development efficiency of the GaN radio frequency device and the product update speed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a GaN radio frequency device and a testing method thereof. BACKGROUND

[0002] In the field of radio frequency, high electron mobility transistors (HEMTs) based on gallium nitride (GaN) are extremely critical devices. GaN materials have excellent characteristics such as high breakdown electric field and high electron saturation velocity, which enable HEMTs based on GaN to exhibit outstanding performance in high-frequency and high-power radio frequency applications, such as 5G communication base stations, satellite communication, and radar systems, providing strong hardware support for modern communication and detection technologies.

[0003] The performance of HEMTs is closely related to key electrode dimensions such as the source-gate spacing, gate-drain spacing, and length dimensions of the source, gate, and drain. The source-gate spacing affects the threshold voltage and transconductance of the device, and improper spacing can cause unstable operation of the device; the gate-drain spacing is related to the output power and efficiency of the device, and unreasonable settings can cause power loss and signal distortion; the length dimensions of the source, gate, and drain have an important role in the current density and frequency characteristics of the device, and inappropriate lengths can limit the high-frequency performance of the device. However, to optimize these key dimension parameters for optimal performance, traditional methods require the production of multiple HEMTs with different size specifications for performance testing, and then the selection of the optimal combination from among them. This process not only requires a large amount of materials and manpower, resulting in high costs, but also has a complex process flow and a long cycle, greatly hindering the research and development efficiency of HEMTs and the speed of product updates and replacements. SUMMARY

[0004] The purpose of the present application is to provide a GaN radio frequency device and a testing method thereof, which can improve the above-mentioned problems.

[0005] Embodiments of the present application are implemented as follows:

[0006] In a first aspect, the present application provides a first GaN radio frequency device, which can be a high electron mobility transistor (HEMT) based on gallium nitride (GaN), comprising:

[0007] a substrate, a gallium nitride buffer layer, a gallium nitride body layer, and a barrier layer grown in sequence on the substrate, a channel layer formed at the junction of the gallium nitride body layer and the barrier layer due to piezoelectric polarization and spontaneous polarization;

[0008] the barrier layer is divided into a first region, a second region, and a third region in a first direction, a dielectric layer is stacked on the second region, and an insulating layer covers the dielectric layer and the first region and the third region;

[0009] The surface of the insulating layer is provided with first-type through holes and second-type through holes;

[0010] The first-type through holes penetrate the insulating layer to expose the dielectric layer.

[0011] The second-type through holes penetrate the insulating layer to expose the barrier layer.

[0012] It can be understood that the researchers can try to prepare the source electrode, the gate electrode and the drain electrode in various sizes and positions by using the HEMT disclosed in the first aspect. The first region, the second region and the third region are preliminary demarcated regions for receiving the source test signal, the gate test signal and the drain test signal respectively, and the target regions for receiving the respective test signals can be determined in detail in the three preliminary demarcated regions. The researchers can try to determine the first target region in any position and in any size in the second region for receiving the gate test signal, and can also try to determine the second target region and the third target region in any position and in any size in the first region and the third region for receiving the source test signal and the drain test signal respectively. The remaining target through holes are filled with conductive material in the respective target regions, so that the target material layer regions in communication with the target through holes form ohmic contacts. Finally, different test signals are applied to the above target regions respectively to obtain the performance test parameters of the HEMT, so as to determine whether the current target region scheme is optimal. When the test of a certain target region scheme is completed, the respective through holes can be cleaned by using special materials to restore the HEMT for the test of the next target region scheme. When the researchers design the sizes and positions of the different electrodes of the HEMT, the HEMT disclosed in the first aspect can be used to try the sizes and positions of the source electrode, the gate electrode and the drain electrode arbitrarily to determine the optimal design scheme without preparing multiple HEMTs from the beginning.

[0013] In an optional embodiment of the present application, the openings of the first-type through holes and the second-type through holes on the surface of the insulating layer are different in shape, so as to facilitate the researchers to identify the respective types of through holes when filling the conductive material.

[0014] In an optional embodiment of the present application, the first region is used for receiving the source test signal, the second region is used for receiving the gate test signal, and the third region is used for receiving the drain test signal.

[0015] In an optional embodiment of the present application, the first type of through holes are arranged in the second region, and the second type of through holes are arranged in the first region and the third region. It can be understood that if the researchers can preliminarily predict the approximate range of the three regions according to the theoretical formula, the first type of through holes exposing the dielectric layer can be arranged in the second region, and the second type of through holes exposing the barrier layer can be arranged in the first and third regions. Such an arrangement can reduce the number of non-conductive through holes in the target region receiving each test signal while ensuring flexible attempts at electrode size and position, thereby improving test efficiency.

[0016] In an optional embodiment of the present application, a distributed Bragg reflector (DBR) structure of alternating high-refractive-index material layers and low-refractive-index material layers is grown between the barrier layers and the GaN body layer. The high-refractive-index material layers are generally made of AlGaN material with a high refractive index, and the low-refractive-index material layers are generally made of GaN material with a low refractive index.

[0017] It can be understood that the DBR structure is integrated between the GaN body layer and the barrier layer of the HEMT to achieve synergistic control of photons and electrons and enhance the functionality of the device in the field of optoelectronic integration. When light signals are incident on the DBR, the multilayer structure produces constructive interference, reflecting light of a specific wavelength. For example, in an AlGaN / GaN heterojunction, the DBR can reflect light in the near-ultraviolet to visible light band, so that it is confined in the channel region. The gate voltage controls the depth of the potential well in the AlGaN / GaN heterojunction through the Schottky contact, thereby adjusting the density of the 2DEG. The reflected light of the DBR interacts with the electrons in the 2DEG, which can change the channel conductance through the photo-generated carrier effect or the hot electron effect, thereby achieving light-controlled current modulation. The reflection characteristics of the DBR and the electrical characteristics of the HEMT are synergistic. For example, in a photodetector, the DBR can improve the light absorption efficiency; in a laser, the DBR can be used as a resonant cavity mirror to reduce the threshold current.

[0018] In a second aspect, the present application discloses a GaN radio frequency device testing method, comprising steps S11 to S15, wherein S11, S12, etc. are only step identifiers, and the execution order of the method does not necessarily follow the order from small to large, for example, step S12 can be executed before step S11, and the present application does not make any limitation.

[0019] S11, providing the GaN radio frequency device according to any one of the first aspect.

[0020] S12, filling the first type of through holes with conductive material in the first target region on the surface of the second region, and applying a gate test signal to the first target region through the first signal pad.

[0021] S13, filling the second type of via hole with conductive material in the second target region of the first region surface, and applying a source test signal to the second target region through a second signal pad.

[0022] S14, filling the second type of via hole with conductive material in the third target region of the third region surface, and applying a drain test signal to the third target region through a third signal pad, the second target region and the third target region being located on both sides of the first target region respectively.

[0023] S15, obtaining a performance test parameter of the GaN radio frequency device.

[0024] S16, cleaning the conductive material in the first type of via hole and the second type of via hole by a pre-set solution.

[0025] In a third aspect, the present application provides a second GaN radio frequency device, which can be a high electron mobility transistor (HEMT) based on gallium nitride (GaN). Compared with the first GaN radio frequency device, the second GaN radio frequency device provided in the third aspect has the following features:

[0026] The barrier layer includes at least two barrier sub-layers grown in sequence, the second type of via hole includes at least two types of sub-via holes, and the opening shapes of the at least two types of sub-via holes on the surface of the insulating layer are different; the number of types of the sub-via holes is equal to the number of barrier sub-layers, and each type of sub-via hole exposes a corresponding barrier sub-layer;

[0027] According to the order of the number of barrier sub-layers through which each type of sub-via hole passes from large to small, each type of sub-via hole is classified, and the higher the level of the sub-via hole, the greater the number of barrier sub-layers through which the sub-via hole passes;

[0028] The level of the sub-via hole in the third region is lower than the level of the sub-via hole in the first region.

[0029] In an optional embodiment of the present application, in the first region and the third region, the level of the sub-via hole gradually decreases along the first direction.

[0030] In an optional embodiment of the present application, the barrier layer comprises a third barrier sublayer, a second barrier sublayer and a first barrier sublayer grown in sequence, the second type of via hole comprises a first sub-via hole, a second sub-via hole and a third sub-via hole, the first sub-via hole, the second sub-via hole and the third sub-via hole have different opening shapes on the surface of the insulating layer; the first sub-via hole penetrates the insulating layer, the first barrier sublayer and the second barrier sublayer to expose the third barrier sublayer; the third sub-via hole penetrates the insulating layer and the first barrier sublayer to expose the second barrier sublayer; the second sub-via hole penetrates the insulating layer to expose the first barrier sublayer; the first sub-via hole, the third sub-via hole and the second sub-via hole are arranged in sequence in the first direction in the first region and the third region.

[0031] It can be understood that in the HEMT in the field of radio frequency, the barrier layer can be designed to be ladder-shaped, which has different thicknesses at the positions of the gate, the source and the drain. Such an asymmetric design significantly optimizes the high-frequency performance, power density and reliability of the device by regulating the electric field distribution, carrier transport and thermal management. While the researchers design the positions and sizes of the electrodes, they can also consider the asymmetric barrier layer design. The HEMT disclosed in the third aspect adds sub-via holes penetrating different numbers of barrier sublayers to the HEMT disclosed in the first aspect, and an ohmic contact can be formed to the barrier layers with different thicknesses by injecting conductive materials into sub-via holes of different levels.

[0032] In an optional embodiment of the present application, the gallium nitride body layer further has a distributed Bragg reflector structure of alternating high-refractive-index material layers and low-refractive-index material layers grown between the barrier layers. The high-refractive-index material layers are generally made of AlGaN material with a relatively high refractive index, and the low-refractive-index material layers are generally made of GaN material with a relatively low refractive index.

[0033] It can be understood that the DBR structure integrated between the gallium nitride body layer and the barrier layer of the HEMT aims to realize the synergistic control of photons and electrons and enhance the functionality of the device in the field of optoelectronic integration. When light signals are incident on the DBR, the multilayer structure produces constructive interference and reflects light of a specific wavelength. For example, in an AlGaN / GaN heterojunction, the DBR can reflect light in the near-ultraviolet to visible light band, so that the light is confined in the channel region. The gate voltage controls the depth of the potential well in the AlGaN / GaN heterojunction through the Schottky contact, thereby adjusting the density of the 2DEG. The reflected light of the DBR interacts with the electrons in the 2DEG, which can change the channel conductance through the photo-generated carrier effect or the hot electron effect, thereby realizing light-controlled current modulation. The reflection characteristics of the DBR and the electrical characteristics of the HEMT are mutually synergistic. For example, in a photodetector, the DBR can improve the light absorption efficiency; in a laser, the DBR can be used as a resonant cavity mirror to reduce the threshold current.

[0034] In a fourth aspect, the application discloses a GaN radio frequency device testing method, comprising steps S21-S25, wherein S21, S22, etc. are only step identifiers, and the execution order of the method does not necessarily follow the order from small to large, for example, step S22 can be executed first and then step S21, which is not limited by the application.

[0035] S21, providing the GaN radio frequency device according to any one of the third aspect.

[0036] S22, filling the first type of via holes in the first target area in the second area with conductive material, and applying a gate test signal to the first target area through the first signal pad.

[0037] S23, filling the remaining second type of via holes in the second target area with conductive material after filling the sub-via holes with a level lower than the first level value with insulating material in the first area, and applying a source test signal to the second target area through the second signal pad.

[0038] S24, filling the remaining second type of via holes in the third target area with conductive material after filling the sub-via holes with a level higher than the second level value with insulating material in the third area, and applying a source test signal to the third target area through the third signal pad.

[0039] S25, obtaining the performance test parameters of the GaN radio frequency device.

[0040] S26, cleaning the insulating material and conductive material in the first type of via holes and the second type of via holes with a pre-set solution.

[0041] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the following optional embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0043] Figure 1 is a cross-sectional view of a GaN radio frequency device provided by the application;

[0044] Figure 2 is Figure 1 is a top view of the insulating layer of the GaN radio frequency device.

[0045] Figure 3 is Figure 1 a schematic diagram of a test step of the GaN radio frequency device shown in FIG. 1;

[0046] Figure 4 is a schematic diagram of another GaN radio frequency device provided by the present application;

[0047] Figure 5 is Figure 4 a top view of an insulating layer of the GaN radio frequency device shown in FIG. 1;

[0048] Figure 6 is another top view of an insulating layer of the GaN radio frequency device provided by the present application;

[0049] Figure 7 is a schematic diagram of yet another GaN radio frequency device provided by the present application;

[0050] Figure 8 is a schematic diagram of still another GaN radio frequency device provided by the present application. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0052] In a first aspect, the present application provides a first GaN radio frequency device 100, i.e., a gallium nitride (GaN) based high electron mobility transistor (HEMT). In the field of radio frequency, the gallium nitride (GaN) based high electron mobility transistor (HEMT) is very critical. The gallium nitride (GaN) material has excellent characteristics, which makes it perform outstandingly in high frequency and high power applications, provides strong hardware support for 5G communication, etc., and is an important element of modern communication and detection technology.

[0053] As Figure 1 and Figure 2As shown, the first GaN radio frequency device 100 comprises: a substrate 10 and a gallium nitride buffer layer 11, a gallium nitride body layer 12 and a barrier layer 13 sequentially grown on the substrate 10; wherein the substrate 10 provides mechanical support and physical basis for the device; the gallium nitride buffer layer 11 is between the substrate 10 and the gallium nitride body layer 12, and its own lattice characteristics can buffer the lattice difference between the substrate 10 and the gallium nitride body layer 12, and reduce the stress generated due to lattice mismatch; the barrier layer 13 generally uses AlGaN material, and a channel layer is formed at the junction of the barrier layer 13 and the gallium nitride body layer 12 due to the existence of piezoelectric polarization and spontaneous polarization effects of the two, and the two polarizations induce a high-concentration two-dimensional electron gas at the junction, which is gathered to form a channel layer. The channel layer is the main movement area of the carrier, and its characteristics have a major impact on the performance of the HEMT and can control the on-off and size of the current.

[0054] The barrier layer 13 is sequentially divided into a first region 150, a second region 160 and a third region 170 along a first direction (indicated by an arrow in the figure), and a dielectric layer 15 is stacked on the second region 160. The dielectric layer 15 and the first region 150 and the third region 170 are covered with an insulating layer 16.

[0055] The surface of the insulating layer 16 is arranged with first-type through holes 101 and second-type through holes 102, and the opening shapes of the first-type through holes 101 and the second-type through holes 102 on the surface of the insulating layer 16 are different. As shown in the figure, Figure 2 The opening shape of the first-type through hole 101 on the surface of the insulating layer 16 is square, and the opening shape of the second-type through hole 102 on the surface of the insulating layer 16 is circular, so as to facilitate the subsequent distinction between the two types of through holes. As shown in the figure, Figure 1 The first-type through hole penetrates through the insulating layer 16 to expose the dielectric layer 15; and the second-type through hole penetrates through the insulating layer 16 to expose the barrier layer 13.

[0056] In an optional embodiment of the present application, the first region 150 is prepared for receiving a source test signal, the second region 160 is prepared for receiving a gate test signal, and the third region 170 is prepared for receiving a drain test signal.

[0057] It can be understood that the researchers can try to prepare the source, gate and drain of various sizes and positions through the HEMT disclosed in the first aspect, and the first region 150, the second region 160 and the third region 170 are preliminary demarcated regions for receiving the source test signal, the gate test signal and the drain test signal respectively, and the target regions for receiving the respective test signals can be determined in detail in the three preliminary demarcated regions. As shown in the figure, Figure 2 and Figure 3As shown, the developer can attempt to determine the first target region 110 of any size at any position of the second region 160 for receiving the gate test signal, and attempt to determine the second target region 120 and the third target region 130 of any size at any position of the first region 150 and the third region 170 for receiving the source test signal and the drain test signal, respectively. The remaining target via is filled with conductive material in each target region, so that the target material layer region in communication with the target via forms ohmic contact. Finally, the performance test parameters of the HEMT are obtained by applying different test signals to the above target regions, respectively, so as to determine whether the current target region scheme is optimal. When the test of a certain target region scheme is completed, the HEMT can be restored by cleaning each via with special material for the test of the next target region scheme. When the developer designs the size and position of the different electrodes of the HEMT, the size and position of the source, gate and drain of the HEMT disclosed in the first aspect can be arbitrarily attempted to determine the optimal design scheme without preparing multiple HEMTs from scratch.

[0058] In an optional embodiment of the present application, as shown in Figure 2 The first type of via 101 is arranged in the second region 160, and the second type of via 102 is arranged in the first region 150 and the third region 170. It can be understood that if the developer can preliminarily predict the approximate range of the three regions according to the theoretical formula, the first type of via exposing the dielectric layer can be arranged in the second region, and the second type of via exposing the barrier layer can be arranged in the first and third regions. Such arrangement can reduce the number of non-conductive vias in the target region receiving each test signal while ensuring flexible attempt of electrode size and position, thereby improving the efficiency of the test.

[0059] In an optional embodiment of the present application, as shown in Figure 7 On the basis of the structure of the first GaN radio frequency device 100, the distributed Bragg reflector structure 90 in which the high-refractive material layer and the low-refractive material layer are alternately arranged is grown between the gallium nitride body layer 12 and the barrier layer 13. The high-refractive material layer generally adopts AlGaN material with high refractive index, and the low-refractive material layer generally adopts GaN material with low refractive index.

[0060] It can be understood that the DBR structure is integrated between the gallium nitride body layer and the barrier layer of the HEMT, and the purpose is to realize the synergistic control of photons and electrons, and enhance the functionality of the device in the field of optoelectronic integration. When the light signal is incident to the DBR, the multilayer structure produces constructive interference, and reflects light of a specific wavelength. For example, in the AlGaN / GaN heterojunction, the DBR can reflect light in the near ultraviolet to visible light band, so that it is confined in the channel region. The gate voltage controls the depth of the potential well in the AlGaN / GaN heterojunction through the Schottky contact, thereby adjusting the density of the 2DEG. The reflected light of the DBR interacts with the electrons in the 2DEG, which can change the channel conductance through the photo carrier effect or the hot electron effect, and realize the light-controlled current modulation. The reflection characteristics of the DBR and the electrical characteristics of the HEMT are mutually synergistic. For example, in the optical detector, the DBR can improve the light absorption efficiency; in the laser, the DBR can be used as a resonant cavity mirror to reduce the threshold current.

[0061] In a second aspect, the application discloses a GaN radio frequency device testing method, comprising steps S11-S15, wherein S11, S12, etc. are only step identifiers, and the execution order of the method does not necessarily follow the order from small to large, for example, step S12 can be executed first and then step S11, which is not limited by the application.

[0062] S11, providing a GaN radio frequency device according to any one of the first aspect.

[0063] S12, as shown in the second region 160, the first target area 110 is filled with a conductive material, and the first signal pad 301 is used to apply a gate test signal to the first target area 110. Figure 2

[0064] S13, in the second target area 120 on the surface of the first region 150, the second type of via hole 102 is filled with a conductive material, and the second signal pad 302 is used to apply a source test signal to the second target area 120.

[0065] S14, in the third target area 130 on the surface of the third region 170, the second type of via hole 102 is filled with a conductive material, and the third signal pad 303 is used to apply a drain test signal to the third target area 130, and the second target area 120 and the third target area 130 are respectively located on both sides of the first target area 110.

[0066] S15, obtaining performance test parameters of the GaN radio frequency device.

[0067] S16, cleaning the conductive material in the first type of via hole 101 and the second type of via hole 102 by using a predetermined solution.

[0068] ​In the alternative embodiments of the present application, the conductive material can be made of the following specific materials:

[0069] Silver Paste, Silver Paste is made of silver particles and organic binder (such as resin, solvent), which is in the form of high-viscosity paste when not cured, and can be accurately filled into the via by screen printing or dispensing process. After curing, it has excellent conductivity (resistivity as low as 10⁻ 6 Ω·cm), and silver and GaN barrier layer can form a good ohmic contact. Uncured silver paste can be dissolved and removed with organic solvents (such as isopropanol, acetone); after curing, it needs to be etched by high-temperature ashing (more than 400℃) or nitric acid (HNO3) solution, but attention should be paid to the potential corrosion of GaN material, and the conditions should be strictly controlled.

[0070] Conductive Epoxy, with epoxy resin as the matrix, mixed with silver, copper or graphite particles, forming a viscous conductive adhesive. Uncured, moderate flow, can fill micron-sized vias, high mechanical strength after curing, good environmental stability. Uncured can be removed with ethanol or acetone; after curing, it needs to be removed by soaking in organic solvents (such as N-methyl pyrrolidone, NMP) or oxygen plasma etching, which causes less damage to GaN.

[0071] Peelable Conductive Film, based on a polymer matrix (such as polyimide) mixed with conductive fillers, forming a peelable viscous adhesive film. Uncured, can be filled into the via by stamping or spraying, and after curing, it can be removed by mechanical peeling or solvent dissolution. Directly tear off the adhesive film, or remove it with isopropanol, ethyl acetate and other solvents, without chemical residues.

[0072] In a third aspect, the present application further provides another second GaN radio frequency device 200, specifically a high electron mobility transistor (HEMT) based on gallium nitride (GaN). The second GaN radio frequency device 200 adds the following features to the first GaN radio frequency device 100:

[0073] The barrier layer includes at least two barrier sublayers grown in sequence, and the second type of via includes at least two types of sub-vias, the openings of the at least two types of sub-vias on the surface of the insulating layer are different in shape; the number of barrier sublayers and the number of types of sub-vias are equal, and each type of sub-via exposes a corresponding barrier sublayer. For example, Figure 4As shown, the barrier layer 13 includes a third barrier sublayer 133, a second barrier sublayer 132, and a first barrier sublayer 131, which are sequentially grown; the second type of via hole includes a first sub-via hole 1021 and a second sub-via hole 1022, the first sub-via hole 1021 has a triangular shape on the surface of the insulating layer 16, and the second sub-via hole 1022 has a circular shape on the surface of the insulating layer 16, wherein the first sub-via hole 1021 passes through the insulating layer 16, the first barrier sublayer 131, and the second barrier sublayer 132, and exposes the third barrier sublayer 133; the second sub-via hole 1022 passes through the insulating layer 16 and exposes the first barrier sublayer 131.

[0074] Figure 5 As shown, the surface of the insulating layer 16 is sequentially divided into a first region 150, a second region 160, and a third region 170 along a first direction (arrow direction); the first region 150 is prepared to receive a source test signal, the second region 160 is prepared to receive a gate test signal, and the third region 170 is prepared to receive a drain test signal; the first type of via hole 101 is arranged in the second region 160, and the second type of via hole is arranged in the first region 150 and the third region 170, i.e., the first sub-via hole 1021 is arranged in the first region 150, and the second sub-via hole 1022 is arranged in the third region 170.

[0075] According to the order of the number of barrier sublayers passed by the sub-via hole from large to small, the various sub-via holes are classified, and the higher the level of the sub-via hole, the greater the number of barrier sublayers passed; the level of the sub-via hole in the third region is lower than that in the first region; in the first region 150 and the third region 170, the level of the sub-via hole gradually decreases along the first direction. For example, Figure 5 As shown, the first sub-via hole 1021 and the second sub-via hole 1022 are sorted according to the number of barrier sublayers passed by the sub-via hole from large to small, and the level of the first sub-via hole 1021 located in the first region 150 is higher than that of the second sub-via hole 1022 located in the third region.

[0076] It can be understood that in the HEMT in the field of radio frequency, the barrier layer can be designed as a ladder type, which has different thicknesses at the positions of the gate, the source, and the drain. This asymmetric design significantly optimizes the high-frequency performance, power density, and reliability of the device by regulating the electric field distribution, carrier transport, and thermal management. While researchers design the positions and sizes of the electrodes, they can also consider the design of the asymmetric ladder-type barrier layer. The HEMT disclosed in the third aspect adds sub-via holes that pass through different numbers of barrier sublayers to the HEMT disclosed in the first aspect, and by injecting conductive materials into sub-via holes of different levels, an ohmic contact is formed to different thickness barrier layers, thereby achieving testing of different size designs of ladder-type barrier layers until the optimal ladder-type barrier layer design is found.

[0077] AsFigure 6 As shown, the second type of via in the second GaN RF device 200 may further include a third sub-via 1023. The third sub-via 1023 has a rhomboid opening shape on the surface of the insulating layer 16. The third sub-via 1023 passes through the insulating layer 16 and the first barrier sub-layer 131, exposing the second barrier sub-layer 132. The third sub-via 1023 can be disposed in the first region 150 and the third region 170, providing more dimensional space for researchers to design stepped barrier layers. The first sub-via 1021, the third sub-via 1023, and the second sub-via 1022 are arranged sequentially along the first direction in the first region 150 and the third region 170.

[0078] In optional embodiments of this application, such as Figure 8 As shown, based on the structure of the second GaN RF device 200, a distributed Bragg reflector structure 90 with alternating high-refractive-index material layers and low-refractive-index material layers is grown between the gallium nitride host layer 12 and the barrier layer 13. The high-refractive-index material layers generally use AlGaN material with a higher refractive index, while the low-refractive-index material layers generally use GaN material with a lower refractive index.

[0079] The integration of a photodiode-based phototransistor (DBR) structure between the gallium nitride (GaN) host layer and the barrier layer in a HEMT aims to achieve synergistic control of photons and electrons, enhancing the device's functionality in optoelectronic integration. When an optical signal is incident on the DBR, the multilayer structure generates constructive interference, reflecting light of a specific wavelength. For example, in an AlGaN / GaN heterojunction, the DBR can reflect light in the near-ultraviolet to visible light band, confining it to the channel region. The gate voltage controls the depth of the potential well in the AlGaN / GaN heterojunction via a Schottky contact, thereby adjusting the density of the 2DEG (photodiode-based phototransistor). The interaction between the reflected light from the DBR and the electrons in the 2DEG can alter the channel conductance through photogenerated carrier effects or hot electron effects, achieving optically controlled current modulation. The reflective properties of the DBR synergize with the electrical properties of the HEMT. For example, in photodetectors, the DBR can improve light absorption efficiency; in lasers, the DBR can act as a resonant cavity mirror, reducing the threshold current.

[0080] Fourthly, this application discloses a GaN radio frequency device testing method, including steps S21 to S25. Here, S21, S22, etc. are only step identifiers, and the execution order of the method does not necessarily follow the order of numbers from smallest to largest. For example, step S22 can be executed first and then step S21 can be executed. This application does not impose any restrictions.

[0081] S21, providing a GaN RF device as described in any of the third aspects;

[0082] S22, filling the first type of via holes in the first target region 110 within the second region 160 with a conductive material, and applying a gate test signal to the first target region 110 through the first signal pad;

[0083] S23, filling the sub-via holes with a level lower than the first level value with an insulating material on the second target region within the first region 150, and then filling the remaining second type of via holes within the second target region with a conductive material, and applying a source test signal to the second target region through the second signal pad;

[0084] S24, filling the sub-via holes with a level higher than the second level value with an insulating material on the third target region within the third region 170, and then filling the remaining second type of via holes within the third target region with a conductive material, and applying a source test signal to the third target region through the third signal pad;

[0085] S25, obtaining a performance test parameter of the GaN radio frequency device.

[0086] S26, cleaning the insulating material and the conductive material in the first type of via holes and the second type of via holes through a pre-set solution.

[0087] In an optional embodiment of the present application, the above-mentioned insulating material can be made of the following specific materials:

[0088] A polyimide (PI) precursor, which is a viscous liquid when not cured, can be filled into the via holes by injection. After curing, it forms a thin film with high temperature resistance and high insulation performance, and can be removed by an organic solvent (such as N-methyl pyrrolidone, NMP), which is suitable for test scenarios requiring repeated cleaning.

[0089] A benzocyclobutene (BCB) resin, which is a viscous liquid when not polymerized, can form an insulating layer after filling and curing. Its advantages are low shrinkage rate after curing, high chemical stability, and can be removed by an organic solvent (such as propylene glycol methyl ether acetate, PGMEA) or hydrogen fluoride (HF) based etching solution, which is suitable for the compatibility requirements of GaN devices.

[0090] Silicone or acrylic photoresist, partially modified silicone or high viscosity acrylic photoresist (such as SU-8) is in liquid state when not exposed, which can fill the via holes and temporarily solidify. It can be dissolved by an organic solvent (such as acetone, isopropyl alcohol) or ashed by oxygen plasma when removed, which is simple to operate and low in cost.

[0091] In an optional embodiment of the present application, the above-mentioned conductive material can be made of the following specific materials:

[0092] Silver Paste, Silver paste is made of silver particles mixed with organic binder (such as resin, solvent), which is in high viscosity paste form when uncured, can be filled into via holes accurately by screen printing or dispensing process. After curing, it has excellent conductivity (resistivity as low as 10⁻ 6 Ω·cm), and silver and GaN barrier layer can form good ohmic contact. Uncured silver paste can be dissolved and removed by organic solvents (such as isopropanol, acetone); after curing, it needs to be removed by high-temperature ashing (more than 400℃) or nitric acid (HNO3) solution etching, but attention should be paid to the potential corrosion of GaN material, and the conditions need to be strictly controlled.

[0093] Conductive Epoxy, with epoxy resin as the matrix, mixed with silver, copper or graphite particles, forming a viscous conductive glue. Uncured, moderate fluidity, can fill micron-level via holes, high mechanical strength after curing, good environmental stability. Uncured can be removed by ethanol or acetone; after curing, it needs to be removed by organic solvent (such as N-methyl pyrrolidone, NMP) soaking or oxygen plasma etching, less damage to GaN.

[0094] Peelable Conductive Film, based on polymer matrix (such as polyimide) mixed with conductive filler, forming a peelable viscous glue film. Uncured, can be filled into via holes by stamping or spraying, and can be removed by mechanical peeling or solvent dissolution after curing. Directly tear off the glue film, or remove it with the help of isopropanol, ethyl acetate and other solvents, without chemical residues.

[0095] The expressions “first”, “second”, “the first”, or “the second” used in various embodiments of the disclosure can modify various components regardless of order and / or importance, but the expressions do not limit the corresponding components. The above expressions are configured only for the purpose of distinguishing the elements from other elements. For example, the first user equipment and the second user equipment represent different user equipment, although both are user equipment. For example, without departing from the scope of the disclosure, a first element can be called a second element, and similarly, a second element can be called a first element.

[0096] When an element (for example, a first element) is referred to as being “(operatively or communicatively) coupled with” or “(operatively or communicatively) coupled to” another element (for example, a second element) or “connected to” another element (for example, a second element), it should be understood that the one element is directly connected to the other element or the one element is indirectly connected to the other element via still another element (for example, a third element). In contrast, it can be understood that when an element (for example, a first element) is referred to as being “directly connected” or “directly coupled” to another element (a second element), no element (for example, a third element) is inserted therebetween.

[0097] It should be noted that, in the present document, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a", "comprising", or "comprises" does not, without further qualification, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. The terms "coupled" and "coupling" as used in the present document refer to any direct or indirect coupling or link between the elements that are coupled, and can include an electrical coupling, a mechanical coupling, an optical coupling, a magnetic coupling, or any combination thereof.

[0098] The above description is only optional embodiments of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the inventive scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features and the technical features disclosed in the present application (but not limited to) with similar functions can be replaced with each other to form a technical solution.

[0099] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting." Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" can be interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]."

[0100] The above description is only optional embodiments of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the inventive scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features and the technical features disclosed in the present application (but not limited to) with similar functions can be replaced with each other to form a technical solution. The above description is only optional embodiments of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the inventive scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features and the technical features disclosed in the present application (but not limited to) with similar functions can be replaced with each other to form a technical solution. The above description is only optional embodiments of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the inventive scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features and the technical features disclosed in the present application (but not limited to) with similar functions can be replaced with each other to form a technical solution. The above description is only optional embodiments of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the inventive scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features and the technical features disclosed in the present application (but not limited to) with similar functions can be replaced with each other to form a technical solution. The above description is only optional embodiments of the present application and an explanation of the technical principles applied. Those skilled in the art should understand that the inventive scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features and the technical features disclosed in the present application (but not limited to) with similar functions can be replaced with each other to form a technical solution.

Claims

1. A testing method for GaN radio frequency devices, characterized in that, Includes the following steps: S11, a GaN radio frequency device is provided, the GaN radio frequency device comprising: A substrate and a gallium nitride buffer layer, a gallium nitride host layer and a barrier layer sequentially grown on the substrate, wherein a channel layer is formed at the junction of the gallium nitride host layer and the barrier layer due to piezoelectric polarization and spontaneous polarization. The barrier layer is divided into a first region, a second region and a third region along a first direction. A dielectric layer is stacked on the second region. An insulating layer covers the dielectric layer, the first region and the third region. The surface of the insulating layer is provided with a first type of through hole and a second type of through hole; The first type of through-hole penetrates the insulating layer and exposes the dielectric layer; The second type of via penetrates the insulating layer, exposing the barrier layer; The first region is configured to receive a source signal, the second region is configured to receive a gate signal, and the third region is configured to receive a drain signal. The first type of through holes is arranged in the second region, and the second type of through holes is arranged in the first region and the third region; The barrier layer includes at least two barrier sub-layers grown in sequence, and the second type of via includes at least two types of vias, the at least two types of vias having different opening shapes on the surface of the insulating layer; the number of barrier sub-layers and the number of types of vias are equal, and each type of via exposes the corresponding barrier sub-layer. Along the first direction, there are multiple first-type through holes in the second region, multiple second-type through holes in the first region, and multiple second-type through holes in the third region; S12, fill the first type of via with conductive material in the first target area on the surface of the second region, and apply a gate test signal to the first target region through the first signal pad; S13, fill the second type of via with conductive material in the second target area of ​​the first region, and apply a source test signal to the second target region through the second signal pad; S14, the second type of via is filled with conductive material in the third target area on the surface of the third region, and a drain test signal is applied to the third target region through the third signal pad; S15, Obtain the performance test parameters of the GaN RF device; S16, the conductive materials in the first type of via and the second type of via are cleaned with a preset solution to restore the HEMT device for testing in the next target scheme, thereby designing the size and position of the source, drain and gate of the HEMT to determine the optimal technical solution.

2. The GaN RF device testing method according to claim 1, characterized in that, The sub-vias are classified in descending order of the number of sub-vias passing through the barrier sub-layer; the higher the level, the greater the number of sub-vias passing through the barrier sub-layer. The level of the sub-via in the third region is lower than the level of the sub-via in the first region.

3. The GaN RF device testing method according to claim 2, characterized in that, In the first region and the third region, the level of the sub-via gradually decreases along the first direction.

4. The GaN RF device testing method according to claim 3, characterized in that, The barrier layer comprises a third barrier sublayer, a second barrier sublayer, and a first barrier sublayer stacked sequentially. The second type of via comprises a first sub-via, a second sub-via, and a third sub-via. The opening shapes of the first sub-via, the second sub-via, and the third sub-via on the surface of the insulating layer are different. The first sub-via passes through the insulating layer, the first barrier sublayer, and the second barrier sublayer, exposing the third barrier layer. The third sub-via passes through the insulating layer and the first barrier layer, exposing the second barrier layer. The second sub-via passes through the insulating layer, exposing the first barrier layer. The first sub-through hole, the third sub-through hole, and the second sub-through hole are arranged sequentially along the first direction in the first region and the third region.

5. The GaN RF device testing method according to any one of claims 1 to 4, characterized in that, Between the gallium nitride host layer and the barrier layer, a distributed Bragg reflector structure is also grown, in which high-refractive-index material layers and low-refractive-index material layers are arranged alternately.

Images