HEMT radio frequency device manufacturing method and HEMT radio frequency device

Abstract

The present invention discloses a method for fabricating a HEMT radio frequency device. The method comprises forming a NiFe2O4 material layer on a substrate, then annealing the NiFe2O4 material layer to form a plurality of magnetostrictive units in the NiFe2O4 material layer. The magnetostrictive units have upwardly convex curved surfaces, on which a HEMT epitaxial material layer including a nitride heterojunction is grown, and then a source, drain, and gate are fabricated. The magnetostrictive units with convex curved surfaces are applied to improve the HEMT material structure. The magnetostrictive units deform under the action of a magnetic field, applying stress to the HEMT epitaxial material layer, thereby inhibiting lattice deformation of the channel layer / barrier layer, maintaining the dynamic resistance of the nitride heterojunction unchanged, effectively suppressing the current collapse effect, and improving the performance and stability of the device.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductors, and in particular relates to a method for manufacturing a HEMT radio frequency device and a HEMT radio frequency device manufactured by the manufacturing method. Background Art

[0002] The third generation semiconductor material GaN has a large band gap (3.4eV), a high electron saturation velocity (2×10 7 cm / s), high breakdown electric field (1×10 10 ~3×10 10 V / cm), high thermal conductivity, corrosion resistance, and radiation resistance are currently hot research topics and have broad application prospects. In particular, AlGaN / GaN heterojunction HEMTs, with their advantages of high frequency, high power density, and high operating temperature, are a promising development direction for solid-state microwave power devices and power electronics.

[0003] In HEMT device applications, it was found that when the source-drain voltage of the GaN HEMT is high, the device's output current is greatly reduced. In addition, the device's output power under RF signals is significantly reduced (RF power compression). At the same time, the output power density and power added efficiency also decrease accordingly (RF dispersion). This current collapse phenomenon causes device performance degradation, limiting the performance of the device.

[0004] Essentially, the change in series resistance between the source, gate, and drain electrodes causes the RF current collapse. The negative bias applied to the gate creates an electric field in the AlGaN / GaN heterojunction in the same direction as the piezoelectric polarization field. This increased electric field increases the tensile stress in the AlGaN barrier layer beneath the gate, thereby increasing the compressive stress between the gate and source, and between the source and drain electrodes, reducing the polarization charge density and increasing the series resistance between them. The reduction in polarization charge in these regions can only be offset by slower-responding polarization charge or trapping effects, which cannot keep up with the frequency of the voltage change, resulting in a decrease in output current.

[0005] To suppress current collapse in GaN HEMT devices and power compression in RF applications, one approach is to grow a silicon nitride passivation layer to improve the interface state between the AlGaN and passivation layers, thereby regulating trapping. Another approach is to control the doping state of the buffer layer beneath the channel layer to regulate the off-state leakage current. This allows for the regulation of trapping in the epitaxial material, creating micro-leakage channels to mitigate the current reduction caused by trapping, thereby suppressing current collapse. However, these two methods currently only suppress current collapse and do not address the current collapse introduced by trapping during device operation. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for manufacturing a HEMT radio frequency device and a HEMT radio frequency device, which effectively suppresses the current collapse effect through stress regulation.

[0007] In order to achieve the above objectives, the technical solution of the present invention is:

[0008] A method for manufacturing a HEMT radio frequency device, comprising:

[0009] Step 1) forming a NiFe2O4 material layer on a substrate;

[0010] Step 2) annealing the NiFe2O4 material layer at a temperature of 100 to 800° C. for 15 seconds to 30 minutes, wherein after annealing, the NiFe2O4 material layer forms a plurality of magnetostrictive units, each of which has an upwardly convex arc surface;

[0011] Step 3) growing a HEMT epitaxial material layer on the substrate having the magnetostrictive unit, wherein the HEMT epitaxial material layer includes a nitride heterojunction;

[0012] Step 4) Fabricating a source, a drain, and a gate on the HEMT epitaxial material layer.

[0013] Optionally, the NiFe2O4 material layer has a thickness of 1 to 50 nm and is formed by PVD, magnetron sputtering, MBE, CVD or sol-gel chemical synthesis.

[0014] Optionally, the annealing temperature is ≥600° C., and after annealing, the NiFe 2 O 4 material layer forms a plurality of discrete spherical particles, and the spherical particles serve as the magnetostrictive units.

[0015] Optionally, the size of the spherical particles is 1 nm to 20 nm.

[0016] Optionally, the annealing temperature is ≤500°C, and after annealing, the surface of the NiFe2O4 material layer has wavy protrusions, wherein each protrusion has an arc-shaped surface, and the protrusion serves as the magnetostrictive unit; the annealing temperature is further preferably 300-500°C.

[0017] Optionally, the convex portion has a width of 5 nm to 100 nm and a height of 1 nm to 20 nm.

[0018] Optionally, the atmosphere of the annealing treatment is an inert gas, N2, H2 or CO.

[0019] Optionally, in step 3), growing the HEMT epitaxial material layer includes sequentially forming a nucleation layer, a GaN layer, a barrier layer and a cap layer, wherein the material of the barrier layer is AlGaN, AlN, InAlGaN or InAlN.

[0020] Optionally, the thickness of the nucleation layer is 10-50 nm, and the thickness of the GaN layer is 300 nm-3 um.

[0021] Annealing the NiFe2O4 material layer in a non-oxidizing atmosphere causes lattice relaxation in the thin film layer, and the energy released makes the surface more uneven. On the other hand, surface atoms may diffuse and re-agglomerate during the annealing process, thereby increasing the surface undulation and forming a surface with uniform curved protrusions. At higher temperatures, they agglomerate to form a spherical structure with uniform spacing.

[0022] A HEMT radio frequency device fabricated by the above-described fabrication method comprises, from bottom to top, a substrate, a patterned magnetostrictive layer, and a HEMT epitaxial material layer, and further comprising a source, a drain, and a gate disposed on the HEMT epitaxial material layer. The HEMT epitaxial material layer comprises a nitride heterojunction. The patterned magnetostrictive layer comprises a plurality of magnetostrictive units having upwardly convex curved surfaces. The plurality of magnetostrictive units deform under the action of an alternating magnetic field introduced by a radio frequency signal input, thereby applying stress to the HEMT epitaxial material layer.

[0023] Optionally, the substrate is silicon (Si), silicon carbide (SiC) or sapphire.

[0024] Optionally, it further includes a passivation layer covering the HEMT epitaxial material layer, source, drain and gate, the source and drain are connected to a lead-out metal penetrating the passivation layer; the passivation layer is a stack of multiple layers of dielectric materials.

[0025] The beneficial effects of the present invention are:

[0026] 1) Through an annealing process, the NiFe2O4 material layer is formed into a magnetostrictive unit with a curved protrusion, which is applied to improve the HEMT material structure. The magnetostrictive protrusion deforms under the action of a magnetic field, exerting stress on the HEMT epitaxial material layer, hindering the lattice deformation of the channel layer / barrier layer, and maintaining the dynamic resistance of the nitride heterojunction unchanged. Through stress regulation, the current collapse effect is effectively suppressed, and the performance and stability of the device are improved.

[0027] 2) The magnetostrictive units formed are evenly distributed, with a smooth transition interface and interlocking structure with the subsequently deposited HEMT epitaxial material. This not only provides stable mechanical properties, but also uniformly applies stress to the HEMT epitaxial material layer during deformation, further improving device stability.

[0028] 3) The process is highly controllable and suitable for practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a process flow chart of the method for manufacturing the HEMT radio frequency device of Example 1;

[0030] Figure 2 A schematic structural diagram of a HEMT radio frequency device manufactured by the manufacturing method of Example 1;

[0031] Figure 3 This is a schematic structural diagram of the magnetostrictive layer produced in Example 2. DETAILED DESCRIPTION

[0032] The present invention is further explained below with reference to the accompanying drawings and specific embodiments. The drawings are provided for illustrative purposes only to facilitate understanding of the present invention, and their specific proportions may be adjusted according to design requirements. Those skilled in the art will understand that the vertical relationships between components and the definitions of front and back in the figures described herein refer to the relative positions of components. Therefore, they can be flipped to present the same components, and all such representations are within the scope of this specification.

[0033] Example 1

[0034] The following combination Figure 1 The method for manufacturing the HEMT radio frequency device of Example 1 is described, which includes the following steps:

[0035] 1) Referring to 1a, a 20 nm thick NiFe2O4 material layer 2' is formed on a silicon substrate 1. For example, the NiFe2O4 material layer is formed by a polyacrylamide gel method; alternatively, a NiFe2O4 epitaxial layer may be formed by a process such as PVD, magnetron sputtering, MBE, or CVD.

[0036] 2) Referring to 1b, the structure obtained in step 1) was annealed in an annealing furnace in an N2 atmosphere at a temperature of 500°C for 20 minutes. After annealing, the NiFe2O4 material layer 2' formed a magnetostrictive layer 2, which still had a continuous layered structure with wavy protrusions on the surface. Each protrusion served as a magnetostrictive unit 21. The protrusions had an arcuate structure with a width (cross-sectional diameter at the bottom of the protrusion) of approximately 20 nm and a height of approximately 10 nm.

[0037] 3)Reference Figure 1c. Using a measurement-controlled sputtering method to evaporate a 10nm AlN nucleation layer 31, and then using a MOCVD process to grow a GaN layer 32, an AlGaN layer 33, and a cap layer 34 as the HEMT epitaxial material layer 3, with thicknesses of 1.5μm, 20nm, and 2nm, respectively; optionally, the cap layer 34 is GaN 1nm-3nm or GaN 1nm-3nm + SiN 1nm-3nm;

[0038] 4)Reference Figure 1 d. Use photolithography to create a gate pattern, then dry-etch the gate to form the source S, drain D, and gate G. A Ti / Al / Ni / Au stack with thicknesses of 20nm / 200nm / 30nm / 100nm is deposited and annealed at 850°C for 50s to form ohmic contacts, serving as the source S and drain D, with RC = 0.5 ohm.mm. Ni / Au is used for gate electrode metallization. The gate metal is selected to have a larger work function than AlGaN and GaN, ensuring that the difference in work function between the two can deplete electrons in the gate region channel. Conventional processes can be used to form a multilayer passivation layer 4 to form a T-type gate structure. PECVD is used to deposit 600nm of SiN as the top passivation layer, and photolithography is used to etch the PAD opening. The device is fabricated.

[0039] It should be noted that the width of the gate G is generally on the order of several hundred nanometers to several micrometers. It can be understood that the source S, the drain D and the gate G all cover a plurality of magnetostrictive units 21 in their arrangement direction.

[0040] refer to Figure 2 The HEMT radio frequency device of Example 1 comprises, from bottom to top, a substrate 1, a magnetostrictive layer 2, a GaN HEMT epitaxial material layer 3, and also includes a source S, a drain D, a gate G, and a passivation layer 4 provided on the HEMT epitaxial material layer 3. The HEMT epitaxial material layer 3 comprises, from bottom to top, a nucleation layer 31, a GaN layer 32, an AlGaN layer 33, and a cap layer 34, with the GaN layer 32 / AlGaN layer 33 forming a heterojunction. The magnetostrictive layer 2 is a continuous layered structure with wavy protrusions on its surface. The protrusions are arc-shaped structures, and each protrusion serves as a magnetostrictive unit 21. The magnetostrictive layer 2 with its wavy surface forms an interlocking structure with the GaN layer 32, and deforms under the action of the alternating magnetic field introduced by the RF signal input, thereby exerting stress on the HEMT epitaxial material layer.

[0041] When HEMT RF devices are operating, the GaN / AlGaN lattice deforms under the action of a strong electric field, increasing defects within the material and at the heterojunction interface. These defects can capture free electrons in the two-dimensional electron gas in the channel, leading to problems such as increased dynamic resistance and current collapse in the device. Magnetostrictive materials can change size under the action of a magnetic field. A magnetostrictive layer with an undulating surface is used to form a bite structure with the GaN layer. The raised structure on the undulating surface serves as a magnetostrictive unit extending into the GaN layer. When the device is operating, an RF signal is input, introducing an alternating magnetic field. Under the action of the magnetic field, the magnetostrictive unit deforms, exerting stress on the GaN, hindering the lattice deformation of GaN and AlGaN, and maintaining the dynamic resistance of the AlGaN / GaN heterojunction unchanged. Through stress regulation, the current collapse effect is effectively suppressed.

[0042] Example 2

[0043] The difference between the manufacturing method of the HEMT radio frequency device of Example 2 and Example 1 is that, in step 2), the structure obtained in step 1) is annealed in an annealing furnace in an N2 atmosphere at a temperature of 600°C for 10 minutes, and the NiFe2O4 material layer forms discrete spherical particles as magnetostrictive units 22, with a diameter of about 50 nm. Figure 3 shown.

[0044] The rest refer to Example 1.

[0045] Similarly, the multiple magnetostrictive units 22 are discretely spaced and arranged in a spherical particle structure, formed of NiFe2O4 material. The magnetostrictive units 22 form an interlocking structure with the GaN layer. Under the action of the alternating magnetic field introduced by the RF signal input, the magnetostrictive units 22 deform and exert stress on the HEMT epitaxial material layer, applying stress to the GaN to prevent lattice deformation of the nitride heterojunction (such as GaN and AlGaN).

[0046] The above embodiments are merely intended to further illustrate a method for manufacturing a HEMT RF device and a HEMT RF device according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for manufacturing a HEMT radio frequency device, characterized in that: include: Step 1) forming a NiFe2O4 material layer on a substrate; Step 2) annealing the NiFe2O4 material layer at a temperature of 100-800° C. for 15 seconds to 30 minutes, wherein after annealing, the NiFe2O4 material layer forms a plurality of magnetostrictive units, each having an upwardly convex arc surface; Step 3) growing a HEMT epitaxial material layer on the substrate having the magnetostrictive unit, wherein the HEMT epitaxial material layer includes a nitride heterojunction; Step 4) Fabricate source, drain, and gate electrodes on the HEMT epitaxial material layer.

2. The method for manufacturing a HEMT radio frequency device according to claim 1, wherein: The NiFe2O4 material layer has a thickness of 1-50 nm and is formed by PVD, magnetron sputtering, MBE, CVD or sol-gel chemical synthesis.

3. The method for manufacturing a HEMT radio frequency device according to claim 1, wherein: The temperature of the annealing treatment is ≥600° C. After annealing, the NiFe 2 O 4 material layer forms a plurality of discrete spherical particles, and the spherical particles serve as the magnetostrictive units.

4. The method for manufacturing a HEMT radio frequency device according to claim 3, wherein: The size of the spherical particles is 5 nm to 80 nm.

5. The method for manufacturing a HEMT radio frequency device according to claim 1, wherein: The annealing temperature is ≤500° C. After annealing, the surface of the NiFe2O4 material layer has wavy protrusions, wherein each protrusion has an arc-shaped surface, and the protrusions serve as the magnetostrictive units.

6. The method for manufacturing a HEMT radio frequency device according to claim 5, wherein: The width of the convex portion is 5nm~100nm, and the height is 1nm~20nm.

7. The method for manufacturing a HEMT radio frequency device according to claim 1, wherein: The atmosphere of the annealing treatment is an inert gas, N2, H2 or CO.

8. The method for manufacturing a HEMT radio frequency device according to claim 1, wherein: In step 3), the growing of the HEMT epitaxial material layer includes sequentially forming a nucleation layer, a GaN layer, a barrier layer and a cap layer, wherein the material of the barrier layer is AlGaN, AlN, InAlGaN or InAlN.

9. The method for manufacturing a HEMT radio frequency device according to claim 8, wherein: The thickness of the nucleation layer is 10-50 nm, and the thickness of the GaN layer is 300 nm-3 μm.

10. A HEMT radio frequency device obtained by the method for manufacturing a HEMT radio frequency device according to any one of claims 1 to 9, characterized in that: From bottom to top, the structure comprises a substrate, a patterned magnetostrictive layer, and a HEMT epitaxial material layer, as well as a source, a drain, and a gate disposed on the HEMT epitaxial material layer. The HEMT epitaxial material layer comprises a nitride heterojunction. The patterned magnetostrictive layer comprises a plurality of magnetostrictive units having upwardly convex curved surfaces. The plurality of magnetostrictive units deform under the action of an alternating magnetic field introduced by a radio frequency signal input, thereby exerting stress on the HEMT epitaxial material layer.

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