A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design

Abstract

The present invention relates to a GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, belonging to the technical field of semiconductor devices. It includes a substrate, a buffer layer located above the substrate, and a high-resistance layer located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. A channel layer is located above the high-resistance layer, a barrier layer is located above the channel layer, and a cap layer is located above the barrier layer. After adopting the above structure, the present invention has the following advantages: The high-resistance layer design of the present invention effectively improves the breakdown voltage performance and longitudinal current blocking ability of the GaN-based HEMT epitaxial structure, making it suitable for application scenarios with higher voltages. At the same time, it relatively reduces the on-resistance of the device and improves the current lateral transmission performance of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and specifically refers to a GaN-based HEMT epitaxial structure with a GaN high-resistance layer design. Background Art

[0002] GaN-based high electron mobility transistors (HEMTs) have been widely used in the fields of power electronics, high-frequency microwaves, etc. due to their high electron mobility, low on-resistance, and good blocking ability.

[0003] For example, in the existing patent, a HEMT device, a HEMT epitaxial structure based on a GaN substrate, and a manufacturing method thereof with the application number 202011174655.2. The HEMT epitaxial structure based on a GaN substrate includes an interface treatment layer, a barrier layer, an isolation layer, a channel layer, and a contact layer formed in sequence on an N-face polar semi-insulating GaN substrate.

[0004] However, in practical applications, it is impossible to improve the breakdown voltage performance and current blocking ability of the device, and the breakdown voltage performance and blocking ability of GaN-based HEMT devices still face certain challenges. Summary of the Invention

[0005] The present invention aims to solve the above technical problems and provides a GaN-based HEMT epitaxial structure with a GaN high-resistance layer design.

[0006] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0007] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, comprising

[0008] a substrate;

[0009] a buffer layer located above the substrate;

[0010] a high-resistance layer located above the buffer layer, the high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a wider bandgap than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping, and the doping source contains a compound containing C or Fe; the third functional sub-layer is a carrier neutralization layer and is a doping design with a gradually increasing gradient;

[0011] a channel layer located above the high-resistance layer;

[0012] a barrier layer located above the channel layer;

[0013] a cap layer located above the barrier layer.

[0014] Preferably, the AlxGa1-xN is designed as the barrier layer, where 30% ≤ x ≤ 100%.

[0015] Preferably, the AlyGa1-yN is designed as the well layer, where 0 ≤ y ≤ 50%.

[0016] Preferably, the superlattice structure is composed of periodically alternating wide and narrow bandgap well and barrier layers.

[0017] Preferably, the cap layer is an undoped GaN layer or a SiN layer or a p-type GaN layer doped artificially.

[0018] Preferably, the third functional sub-layer forms a doping maximum step with the channel layer on the surface far from the substrate.

[0019] Preferably, the barrier layer has a bandgap width higher than that of the channel layer, forming a heterojunction two-dimensional electron gas.

[0020] After adopting the above structure, the present invention has the following advantages:

[0021] The high-resistance layer design of the present invention effectively improves the breakdown voltage performance and longitudinal current blocking ability of the GaN-based HEMT epitaxial structure, making it applicable to higher voltage application scenarios. At the same time, the on-resistance of the device is relatively reduced, and the current lateral transmission performance of the device is improved.

[0022] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is the electron density map of the lateral transmission electron channel of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Specific embodiments of the present invention will now be described in detail. Although the present invention is described in connection with these specific embodiments, it should be understood that the present invention is not intended to be limited to these specific embodiments. On the contrary, these embodiments are intended to cover alternatives, modifications, or equivalent embodiments that may be included within the spirit and scope of the invention as defined by the claims. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail in order not to unnecessarily obscure the present invention.

[0026] When used in conjunction with the terms "comprising," "method comprising," or similar language in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0027] The present invention will be further described in detail below in conjunction with the full text.

[0028] Combined with the attached Figure 1 , a GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, comprising

[0029] a substrate;

[0030] a buffer layer, located on the substrate;

[0031] a high-resistance layer, located on the buffer layer,

[0032] the high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer,

[0033] The first functional sub-layer electron blocking layer is designed as a wide-bandgap material with a bandgap width higher than that of the buffer layer, having high thermal stability and good electrical characteristics, and can provide ideal blocking characteristics. Its structure is designed as an AlxGa1-xN / AlyGa1-yN superlattice structure to further improve the blocking characteristics and enhance the epitaxial breakdown voltage performance, where 30% ≤ x ≤ 100% and 0 ≤ y ≤ 50%; the AlxGa1-xN layer is designed as the barrier layer, and the AlyGa1-yN layer is designed as the well layer; the superlattice structure is composed of periodically alternating narrow and wide bandgap well-barrier layers, and excellent electron blocking performance is achieved by modulating the layer thickness and composition ratio.

[0034] The second functional sub-layer is a vertically inserted compensation layer, which is designed as a periodic vertically inserted compensation doping. The doping source contains compounds containing C or Fe, not limited to C2H4 and CP2Fe, as shown in Table 1; the vertically inserted highly doped compensation layer can eliminate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer. Here, low and high are relative concepts.

[0035] Table 1

[0036]

[0037] The third functional sub-layer is a carrier neutralization layer with a gradually increasing doping design, forming the largest doping step on the surface far from the substrate and the channel layer, as shown in Table 2; precise doping control is carried out in the high-resistance layer, which can optimize the conductive performance and blocking characteristics of the device. By using the gradient doping technology, the doping concentration is gradually increased to achieve good rectifying characteristics. It longitudinally restricts the current, reduces the lateral on-resistance, and improves the lateral current conduction characteristics of the device.

[0038] Table 2

[0039]

[0040] The channel layer is located above the high-resistance layer; it forms different doping characteristics with the semiconductor material of the high-resistance layer;

[0041] The barrier layer is located above the channel layer; it has a wider bandgap than the channel layer, forming a two-dimensional electron gas of heterojunction;

[0042] The cap layer is located above the barrier layer; the cap layer is an undoped GaN layer or SiN layer or a doped P-type GaN layer; it can be divided into depletion-type or enhancement-type devices according to the characteristic requirements.

[0043] The first, second, and third functional sub-layers of the high-resistance layer effectively improve the breakdown voltage performance and longitudinal current blocking ability of the GaN-based HEMT epitaxial structure, making it suitable for application scenarios with higher voltages. At the same time, it relatively reduces the on-resistance of the device and improves the lateral current transmission performance of the device.

[0044] When the present invention is specifically implemented, such as Figure 1As shown above, in the optimization experiment process of the MOCVD equipment for the above-mentioned invention rules, a C-V equipment was used to measure the cross-sectional thickness-electron concentration curve of the epitaxial layer. The highest point of the carrier concentration is 1E+19, which is also the position of the two-dimensional electron gas at the same time; when the depth of the epitaxial layer is about 0.7um, the carrier concentration (after the intrinsic GaN is compensated and doped) is close to 1E+13; the electron transport layer (1E+19) / optimized high-resistance layer (1E+13) > 1E+6, which meets the high-resistance characteristics and is not overly compensated. Specifically, when the gate is pressurized, the cross-sectional carrier distribution shows that the electron density of the lateral electron transport channel is 1E+6 to 1E+7 times that of the high-resistance layer, with good confinement characteristics, demonstrating excellent lateral migration and longitudinal blocking characteristics.

[0045] Example 1:

[0046] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, comprising

[0047] A substrate;

[0048] A buffer layer, located above the substrate;

[0049] A high-resistance layer, located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a wider bandgap than the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 31%, and AlyGa1-yN is designed as the well layer, where y is 2%;

[0050] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source is a C-containing compound. The vertically inserted highly doped compensation layer can annihilate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer; the third functional sub-layer is a carrier neutralization layer and is a doping design with a gradually increasing gradient; the third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0051] A channel layer, located above the high-resistance layer;

[0052] A barrier layer, located above the channel layer, having a wider bandgap than the channel layer, forming a heterojunction two-dimensional electron gas.

[0053] A cap layer, located above the barrier layer. The cap layer is an undoped GaN layer.

[0054] Example 2:

[0055] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, comprising

[0056] Substrate;

[0057] Buffer layer, located above the substrate;

[0058] High-resistance layer, located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a bandgap width higher than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 98%, and AlyGa1-yN is designed as the well layer, where y is 46%.

[0059] The second functional sub-layer is a vertically inserted compensation layer and is of periodic vertical insertion compensation doping. The doping source contains a compound of Fe. The vertically inserted highly doped compensation layer can annihilate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer. The third functional sub-layer is a carrier neutralization layer and is of a gradient-increasing doping design; the third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0060] Channel layer, located above the high-resistance layer;

[0061] Barrier layer, located above the channel layer, having a bandgap width higher than that of the channel layer, forming a heterojunction two-dimensional electron gas.

[0062] Cap layer, located above the barrier layer. The cap layer is a SiN layer.

[0063] Example 3:

[0064] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, including

[0065] Substrate;

[0066] Buffer layer, located above the substrate;

[0067] High-resistance layer, located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a bandgap width higher than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 45%, and AlyGa1-yN is designed as the well layer, where y is 25%.

[0068] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source is a C-containing compound. The vertically inserted highly doped compensation layer can eliminate carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer. The third functional sub-layer is a carrier neutralization layer and has a doping design with a gradually increasing gradient. The third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0069] The channel layer is located above the high-resistance layer;

[0070] The barrier layer is located above the channel layer and has a wider bandgap than the channel layer, forming a two-dimensional electron gas in the heterojunction.

[0071] The cap layer is located above the barrier layer, and the cap layer is an artificially doped P-type GaN layer.

[0072] Example 4:

[0073] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, including

[0074] The substrate;

[0075] The buffer layer is located above the substrate;

[0076] The high-resistance layer is located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a wider bandgap than the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure. The superlattice structure consists of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 85%, and AlyGa1-yN is designed as the well layer, where y is 35.

[0077] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source is a C-containing compound. The vertically inserted highly doped compensation layer can eliminate carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer. The third functional sub-layer is a carrier neutralization layer and has a doping design with a gradually increasing gradient. The third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0078] The channel layer is located above the high-resistance layer;

[0079] The barrier layer is located above the channel layer and has a wider bandgap than the channel layer, forming a two-dimensional electron gas in the heterojunction.

[0080] The cap layer is located above the barrier layer, and the cap layer is a non-artificially doped GaN layer.

[0081] Example 5:

[0082] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, comprising

[0083] a substrate;

[0084] a buffer layer, located above the substrate;

[0085] a high-resistance layer, located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a bandgap width higher than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 15%, and AlyGa1-yN is designed as the well layer, where y is 12%.

[0086] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source contains a C compound. The vertically inserted highly doped compensation layer can annihilate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer; the third functional sub-layer is a carrier neutralization layer and is a doping design with a gradually increasing gradient; the third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0087] a channel layer, located above the high-resistance layer;

[0088] a barrier layer, located above the channel layer, having a bandgap width higher than that of the channel layer, forming a two-dimensional electron gas of a heterojunction.

[0089] a cap layer, located above the barrier layer. The cap layer is an artificially doped P-type GaN layer.

[0090] Example 6:

[0091] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, comprising

[0092] a substrate;

[0093] a buffer layer, located above the substrate;

[0094] The high-resistance layer is located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a bandgap width higher than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 67%, and AlyGa1-yN is designed as the well layer, where y is 12%.

[0095] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source contains a Fe compound. The vertically inserted highly doped compensation layer can annihilate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low-doped compensation layer usually serves as a relaxation buffer for the vertically inserted high-compensation layer; the third functional sub-layer is a carrier neutralization layer and is a doping design with a gradually increasing gradient; the third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0096] The channel layer is located above the high-resistance layer;

[0097] The barrier layer is located above the channel layer and has a bandgap width higher than that of the channel layer, forming a two-dimensional electron gas at the heterojunction.

[0098] The cap layer is located above the barrier layer, and the cap layer is a SiN layer.

[0099] Example 7:

[0100] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, including

[0101] The substrate;

[0102] The buffer layer is located above the substrate;

[0103] The high-resistance layer is located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a bandgap width higher than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 15%, and AlyGa1-yN is designed as the well layer, where y is 45%.

[0104] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source contains a compound of Fe. The vertically inserted highly doped compensation layer can eliminate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low doped compensation layer usually serves as a relaxation buffer for the vertically inserted highly compensated layer. The third functional sub-layer is a carrier neutralization layer and has a doping design with a gradually increasing gradient. The third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0105] The channel layer is located above the high-resistance layer;

[0106] The barrier layer is located above the channel layer and has a wider bandgap than the channel layer, forming a two-dimensional electron gas of heterojunction.

[0107] The cap layer is located above the barrier layer, and the cap layer is an unintentionally doped GaN layer.

[0108] Example Eight:

[0109] A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, including

[0110] The substrate;

[0111] The buffer layer is located above the substrate;

[0112] The high-resistance layer is located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide bandgap material with a wider bandgap than the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure. The superlattice structure is composed of periodically alternating wide and narrow bandgap well-barrier layers. Among them, AlxGa1-xN is designed as the barrier layer, where x is 65%, and AlyGa1-yN is designed as the well layer, where y is 23%.

[0113] The second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping. The doping source contains a compound of C. The vertically inserted highly doped compensation layer can eliminate the carriers with different energy levels in the gallium nitride material that are not artificially introduced. The low doped compensation layer usually serves as a relaxation buffer for the vertically inserted highly compensated layer. The third functional sub-layer is a carrier neutralization layer and has a doping design with a gradually increasing gradient. The third functional sub-layer forms the largest doping step with the channel layer on the surface far from the substrate.

[0114] The channel layer is located above the high-resistance layer;

[0115] The barrier layer is located above the channel layer and has a wider bandgap than the channel layer, forming a two-dimensional electron gas of heterojunction.

[0116] The cap layer is located above the barrier layer, and the cap layer is a SiN layer.

[0117] The above describes the present invention and its implementation manners. Such description is not restrictive. What is shown throughout the text is only one of the implementation manners of the present invention. The actual structure is not limited thereto. In summary, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A GaN-based HEMT epitaxial structure with a GaN high-resistance layer design, characterized in that, Comprising A substrate; A buffer layer located above the substrate; A high-resistance layer located above the buffer layer. The high-resistance layer includes a first functional sub-layer, a second functional sub-layer, and a third functional sub-layer. The first functional sub-layer is an electron blocking layer and is a wide-bandgap material with a bandgap width greater than that of the buffer layer. The structure of the first functional sub-layer is an AlxGa1-xN / AlyGa1-yN superlattice structure; the second functional sub-layer is a vertically inserted compensation layer and is a periodic vertically inserted compensation doping, and the doping source contains a compound containing C or Fe; the third functional sub-layer is a carrier neutralization layer and is a doping design with a gradually increasing gradient. The doping concentration of the third functional sub-layer gradually increases from the surface close to the substrate to the surface far from the substrate; A channel layer located above the high-resistance layer; A barrier layer located above the channel layer; A cap layer located above the barrier layer; The third functional sub-layer forms a maximum doping step with the channel layer at the surface far from the substrate; The barrier layer has a bandgap width greater than that of the channel layer, forming a heterojunction two-dimensional electron gas.

2. The GaN-based HEMT epitaxial structure with a GaN high-resistance layer design according to claim 1, characterized in that: The AlxGa1-xN is designed as a barrier layer, where 30% ≤ x ≤ 100%.

3. The GaN-based HEMT epitaxial structure with a GaN high-resistance layer design according to claim 2, characterized in that: The AlyGa1-yN is designed as a well layer, where 0 ≤ y ≤ 50%.

4. The GaN-based HEMT epitaxial structure with a GaN high-resistance layer design according to claim 3, characterized in that: The superlattice structure is composed of periodically alternating narrow and wide bandgap well and barrier layers.

5. The GaN-based HEMT epitaxial structure with a GaN high-resistance layer design according to claim 1, characterized in that: The cap layer is an undoped GaN layer or a SiN layer or a p-type GaN layer doped artificially.

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