HEMT device
By introducing heteroepitaxial structures and appropriate thickness design into HEMT devices, multiple two-dimensional electron gas channels are formed, which solves the problem of high electron collision rate, improves electron mobility and reduces resistance, while avoiding increased processing difficulty in chip fabrication.
Patent Information
- Application Number
- CN202520003727.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2035-01-02
AI Technical Summary
Existing gallium nitride HEMT devices suffer from high electron collision rates due to single-channel two-dimensional electron gas, which increases resistance. Furthermore, existing improvement solutions require redesigning the chip manufacturing process, increasing processing difficulty.
Introducing heteroepitaxial structures into HEMT devices forms multiple two-dimensional electron gas channels, and the total thickness of the channel layer and heteroepitaxial structure is designed to be 150–350 nanometers, thus avoiding the need to redesign the chip manufacturing process.
It improves electron mobility, reduces on-resistance, and avoids the increased processing difficulty caused by the large distance between channels in multi-channel HEMT devices.
Smart Images
Figure CN223957880U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of semiconductor, especially relates to a HEMT device. BACKGROUND
[0002] With the development of semiconductor technology, gallium nitride HEMT (High electron mobility transistor) has been more and more used. HEMT uses two materials with different energy gaps to form a heterojunction, which can obtain 2-DEG (Two-dimensional electron gas) to provide a channel for carriers. The gallium nitride HEMT developed in recent years has attracted a lot of attention due to its good high-frequency characteristics.
[0003] Conventional gallium nitride HEMT has a single-channel two-dimensional electron gas. The electrons in the single-channel device are tightly packed, which increases the rate of electron-electron collision, thereby increasing the resistance and improving the power consumption of the HEMT device. Therefore, the existing scheme improves the gallium nitride HEMT to realize multiple two-dimensional electron gases in the gallium nitride HEMT. However, such improvement mostly requires re-designing the structure of the gallium nitride HEMT, which increases the processing difficulty of the chip process in the subsequent process. UTILITARIAN CONTENT
[0004] In view of at least some of the problems and deficiencies in the prior art, the embodiments of the utility model disclose a HEMT device to realize multiple-channel two-dimensional electron gas without changing the processing difficulty of the existing chip process.
[0005] On the one hand, the HEMT device provided by the embodiments of the utility model, for example, includes: a substrate; a channel layer disposed on one side of the substrate, the material of the channel layer including undoped GaN; a heteroepitaxial structure including at least one superlattice structure formed by stacking an AlGaN layer and a GaN layer, in each of the superlattice structures, the GaN layer is disposed on the side of the AlGaN layer away from the channel layer; a barrier layer disposed on the side of the heteroepitaxial structure away from the channel layer, the material of the barrier layer including AlGaN; wherein the total thickness of the channel layer and the heteroepitaxial structure is 150-350 nanometers, and the proportion of Al elements in the AlGaN layer is the same as the proportion of Al elements in the barrier layer.
[0006] From the above, the technical features of the utility model can have one or more beneficial effects as follows: the embodiment of the utility model forms multiple two-dimensional electron gas channels by setting the heteroepitaxial structure between the channel layer and the barrier layer, reduces the crowding of electrons in the single two-dimensional electron gas channel, thereby improving the electron mobility and reducing the on-resistance; in addition, the total thickness of the channel layer and the heteroepitaxial structure is designed to be 150-350 nanometers, thereby avoiding the need to redesign the chip process in subsequent processes and avoiding the situation that the distance between the channels of the multi-channel HEMT device is far apart, thereby increasing the processing difficulty of the chip process in subsequent processes. BRIEF DESCRIPTION OF DRAWINGS
[0007] In order to more clearly illustrate the technical scheme of the embodiment of the utility model, the following will briefly introduce the drawings needed to be used in the embodiment description, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creative labor.
[0008] Figure 1 The structure schematic diagram of the HEMT device provided in the embodiment of the utility model.
[0009] Figure 2 Another structure schematic diagram of the HEMT device provided in the embodiment of the utility model.
[0010] Figure 3 The specific structure schematic diagram of the HEMT device in the embodiment of the utility model. Figure 1
[0011] The specific structure schematic diagram of the HEMT device in the embodiment of the utility model. Figure 4 Figure 2 The structure schematic diagram of the HEMT device provided in one specific embodiment of the utility model.
[0012] Figure 5 The flow chart of the preparation method of the HEMT device provided in the embodiment of the utility model.
[0013] DETAILED DESCRIPTION Figure 6
[0014] It should be noted that the terms "first", "second", and the like in the description and in the claims of the utility model of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged under appropriate circumstances, so that the utility model embodiments described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0015] Referring to Figure 1 The utility model embodiment provides a HEMT device 10 for example, for example including: substrate 100, channel layer 500, heteroepitaxial structure 600 and barrier layer 700. Wherein, channel layer 500 is for example set up in one side of the substrate 100, the material of channel layer 500 includes undoped GaN. Referring to Figure 2 Heteroepitaxial structure 600 for example includes at least one superlattice structure 610 formed by AlGaN layer 611 and GaN layer 612 stacking, in each superlattice structure 610, the GaN layer 612 is set up in one side of AlGaN layer 611 away from channel layer 500. It is for example undoped GaN in GaN layer 612. Barrier layer 700 is for example set up in one side of heteroepitaxial structure 600 away from channel layer 500, and the material of barrier layer includes AlGaN. Specifically, the total thickness of channel layer and heteroepitaxial structure is 150-350 nanometers.
[0016] For example, the material of the substrate 100 is Al2O3, for example, a sapphire substrate. The superlattice structure mentioned above is, for example, a layered fine composite material, which is, for example, formed by alternately growing a periodic structure of two materials with good lattice matching. In the embodiment of the present application, the AlGaN layer 611 of the superlattice structure 610 in the heteroepitaxial structure 600 forms a heterostructure with the channel layer 500, thereby obtaining a 2-DEG (Two-dimensional electron gas) to form a two-dimensional electron gas channel. And the GaN layer 612 can form a heterostructure with the barrier layer 700, thereby obtaining a 2-DEG to form a two-dimensional electron gas channel. Therefore, when the heteroepitaxial structure 600 only includes one superlattice structure 610, the embodiment of the present application can provide two two-dimensional electron gas channels. In other words, based on the fact that the heteroepitaxial structure 600 includes at least one superlattice structure 610, the embodiment of the present application can provide at least two two-dimensional electron gas channels, which can increase the electron mobility, reduce the crowding of electrons in a single two-dimensional electron gas channel, thereby improving the electron mobility and reducing the on-resistance.
[0017] As described above, in the prior art, the thickness of the channel layer is 150-350 nanometers. In the embodiment of the present application, the total thickness of the channel layer 500 and the heteroepitaxial structure 600 is designed to be 150-350 nanometers, so that the chip process does not need to be redesigned in the subsequent process, avoiding the situation that the distance between the channels of the multi-channel HEMT device is far apart, which increases the processing difficulty of the chip process in the subsequent process.
[0018] The HEMT device 10 will be described below in conjunction with specific embodiments.
[0019] Referring to Figure 3 The HEMT device 10 provided by the embodiment of the present application, for example, includes a substrate 100, a high-resistance layer 400, a channel layer 500, a heteroepitaxial structure 600, an isolation layer 700, a barrier layer 800, and a protective layer 900.
[0020] Referring to Figure 3The substrate 100 is provided with a buffer layer, for example, having a thickness of 20-80 nm, for example, including a first buffer layer 200 and / or a second buffer layer 300. Specifically, the first buffer layer 200 is provided on the substrate 100 by a plasma-enhanced chemical vapor deposition method, for example, the first buffer layer 200 is made of AlN, for example, having a thickness of 20-40 nm, and is subjected to heat treatment in a hydrogen atmosphere at 1000-1200 °C for 8-12 minutes to obtain a higher-crystal-quality AlN material. As described above, the second buffer layer 300 is provided on the side of the first buffer layer 200 away from the substrate 100. Specifically, the second buffer layer 300 is deposited on the side of the first buffer layer 200 away from the substrate 100 by a metal-organic chemical vapor deposition method. The second buffer layer 300 is made of AlN or AlGaN, for example, having a thickness of 20-40 nm.
[0021] Specifically, compared with the substrate 100 (sapphire substrate, material: Al2O3), the lattice mismatch and the thermal expansion coefficient mismatch between AlN and GaN are smaller, and GaN is epitaxially grown on the surface of AlN, so that the obtained GaN material has a lower XRD(102) / XRD(002) and a smoother surface. The XRD(102) is the characteristic peak value of the 102 crystal plane of the GaN material on the XRD diffraction pattern, and the XRD(002) is the characteristic peak value of the 002 crystal plane of the GaN material on the XRD diffraction pattern. That is, the first buffer layer 200 and the second buffer layer 300 are used to buffer the problem that the GaN and Al2O3 lattices in the substrate 100 do not match each other.
[0022] Referring again to Figure 3 The high-resistance layer 400 is provided on the side of the second buffer layer 300 away from the first buffer layer 200, for example, the high-resistance layer 400 is a flat GaN layer structure with a high resistance value. For example, the roughness of the high-resistance layer 400 is less than 0.3 nm, and the resistance Rs of the high-resistance layer 400 is greater than 1e9 Ω / □. The material of the high-resistance layer 400 includes GaN, and the thickness of the high-resistance layer 400 is greater than 1 micron. In one embodiment, the high-resistance layer 400 is a Fe and / or C-doped GaN layer, and the doping concentration of the high-resistance layer 400 is greater than 2e18 cm -3The high resistance layer 400 is doped with Fe and / or C to increase the resistance of the high resistance layer 400. In another embodiment, the high resistance layer 400 is, for example, an undoped GaN layer. The high resistance layer 400 can be directly grown by epitaxy to have a flat high resistance. For example, the V / III ratio (NH3 / Ga ratio) and the growth temperature of the high resistance layer 400 can be optimized to obtain a flat high resistance of the undoped GaN high resistance layer 400. For example, the V / III ratio of the GaN high resistance layer is 900-2000, and the growth temperature is 1000-1150°C. The flat high resistance of the high resistance layer 400 can suppress the leakage current and improve the voltage resistance of the HEMT device 10.
[0023] As described above, the channel layer 500 is disposed on the side of the high resistance layer 400 away from the second buffer layer 300. The channel layer 500 is made of undoped GaN. The thickness of the channel layer 500 is 100-200 nm. The thickness of the channel layer 500 is designed to avoid the problem of the HEMT device 10 failing to turn off and causing a leakage current due to the excessive thickness of the channel layer 500.
[0024] Preferably, the hetero-epitaxial structure 600 includes at most three superlattice structures 610. Figure 4 That is, the hetero-epitaxial structure 600 includes three superlattice structures 610. For example, a heterostructure is formed between the AlGaN layer 611 and the channel layer 500 at the surface of the channel layer 500 close to the AlGaN layer 611, thereby obtaining a 2-DEG to form a two-dimensional electron gas channel 620. A heterostructure is formed between the GaN layer 612 and the AlGaN layer 611 at the surface of the GaN layer 612 close to the AlGaN layer 611, thereby obtaining a 2-DEG to form a two-dimensional electron gas channel 620. A heterostructure is formed between the GaN layer 612 and the barrier layer 800 at the surface of the GaN layer 612 close to the barrier layer 800, thereby obtaining a 2-DEG to form a two-dimensional electron gas channel 620. That is, in the embodiment of the hetero-epitaxial structure 600, four two-dimensional electron gas channels are formed, which can better reduce electron crowding and improve electron mobility. Figure 4 However, when the number of superlattice structures 610 exceeds three, the effect of reducing electron crowding is not significant due to the large number of two-dimensional electron gas channels. In addition, a large number of superlattice structures 610 can significantly increase the difficulty of subsequent chip processing, and can also increase the resistance of the chip.
[0025] Further, each of the superlattice structure 610 has a thickness, for example, less than or equal to 40 nanometers. In this way, the distance between the channels of the heteroepitaxial structure 600 is not too far, so that the subsequent chip manufacturing process does not need to be changed in design, and the processing difficulty or the problem of electric leakage is avoided. Preferably, the thickness of the channel layer 500 is in the range of 100-200 nanometers, the thickness of the AlGaN layer 611 is less than or equal to 10 nanometers, and the thickness of the GaN layer 612 is greater than the thickness of the AlGaN layer 611 and less than or equal to 30 nanometers. When the thickness of the AlGaN layer 611 is too large, it will affect the formation of the two-dimensional electron gas channel, resulting in poor dispersion of electrons in the two-dimensional electron gas channel.
[0026] In one embodiment, referring to Figure 5 , the superlattice structure 610 further comprises an InGaN layer 613, and in each of the superlattice structure 610, the InGaN layer 613 is arranged between the AlGaN layer 611 and the GaN layer 612. By arranging the InGaN layer 613, the electron mobility in the formed two-dimensional electron gas channel is effectively improved by using the high electron mobility of the InGaN layer 613. That is, the AlGaN / InGaN / GaN heterojunction formed by inserting the InGaN layer into the AlGaN / GaN heterojunction is superior to the conventional AlGaN / GaN heterojunction. It should be noted that although the InGaN layer 613 can improve the electron mobility, the thickness of the superlattice structure 610 will also increase accordingly. Therefore, the thickness of the superlattice structure 610 still needs to be less than or equal to 40 nanometers, so that the distance between the channels of the heteroepitaxial structure 600 is not too far, and the subsequent chip manufacturing process does not need to be changed in design, and the problem of electric leakage is avoided.
[0027] Preferably, referring to Figure 3 , the isolation layer 700 is arranged on the side of the heteroepitaxial structure 600 away from the channel layer 500, the material of the isolation layer 700 is AlN, and the thickness of the isolation layer 700 is, for example, 1-2 nanometers. By arranging the isolation layer 700, the mobility performance of the HEMT device 10 can be improved.
[0028] Further, referring to Figure 3 , the barrier layer 800 is arranged, for example, on the side of the isolation layer 700 away from the heteroepitaxial structure 600, and the material of the barrier layer 800 is AlGaN. The proportion of aluminum in the barrier layer 800 is, for example, 20%-30%, and the thickness of the barrier layer 800 is, for example, 15-30 nanometers. The AlGaN in the barrier layer 800 forms a heterostructure with the GaN layer 612 in the superlattice structure 610 of the heteroepitaxial structure 600, so as to obtain 2-DEG.
[0029] Specifically, by setting the isolation layer 700 (AlN thin layer) between the barrier layer 800 (AlGaN) and the GaN layer 612 in the superlattice structure 610 in the heteroepitaxial structure 600, the electron density of the two-dimensional electron gas can be improved, the resistance can be reduced, the mobility can be increased, and greater current can be achieved. Specifically, the effective Delta Ec (cathode polarization value) caused by the polarization effect of the AlGaN / AlN / GaN structure is increased, a deeper quantum well is generated, and thus a higher electron concentration is generated; the penetration of the two-dimensional electron gas into the barrier layer 800 is significantly reduced, so that alloy disorder scattering can be reduced to improve the mobility. That is, the AlGaN / AlN / GaN heterojunction formed by inserting an AlN thin layer at the AlGaN / GaN heterojunction interface is superior to the conventional AlGaN / GaN heterojunction.
[0030] Further, referring to Figure 3 , the HEMT device 10 further comprises a protective layer 900, for example, the surface protective layer 900 comprises a protective layer and / or a passivation layer. The protective layer 900 is arranged on the side of the barrier layer 800 away from the isolation layer 700. For example, a first protective layer can be arranged on the side of the barrier layer 800 away from the isolation layer 700, and the material of the first protective layer is, for example, GaN; or a second protective layer can be arranged on the side of the barrier layer 800 away from the isolation layer 700, and the material of the second protective layer is, for example, SiNx; or the first protective layer can be arranged on the side of the barrier layer 800 away from the isolation layer 700, and the second protective layer can be arranged on the first protective layer. The thickness of the protective layer is, for example, 1-4 nanometers. The first protective layer can protect the HEMT device, and the second protective layer can improve the dynamic resistance and reduce the leakage.
[0031] In summary, the embodiment of the utility model provides a plurality of two-dimensional electron gas channels by setting the heteroepitaxial structure between the channel layer and the barrier layer, thereby reducing the crowding of electrons in a single two-dimensional electron gas channel, improving the electron mobility, and reducing the on-resistance; in addition, the total thickness of the channel layer and the heteroepitaxial structure is designed to be 150-350 nanometers, so that the chip process does not need to be redesigned in the subsequent process, and the situation that the processing difficulty of the chip process in the subsequent process is increased due to the far distance between the channels of the multi-channel HEMT device is avoided.
[0032] Further, referring to Figure 6 The following is a preparation method of the HEMT device 10 provided by the embodiment of the application, which comprises, for example:
[0033] S11: providing a substrate;
[0034] S13: growing a high-resistance layer on the substrate;
[0035] S15: growing a channel layer, a heteroepitaxial structure, an isolation layer and a barrier layer on the high-resistance layer in sequence.
[0036] Wherein, between step S11 and step S13, step S12 is further included, and step S12 specifically comprises:
[0037] S121: growing AlN on the substrate by plasma-enhanced chemical vapor deposition method, and heat treating in a hydrogen environment at 1000-1200℃ for 8-12 minutes to improve the lattice quality of the first buffer layer;
[0038] S123: growing the second buffer layer on the first buffer layer by metal organic chemical vapor deposition method.
[0039] As described above, step S13 specifically comprises: growing the high-resistance layer on the second buffer layer under the conditions of epitaxial GaN flow field and temperature field.
[0040] Further, step S15 specifically comprises:
[0041] S151: growing the channel layer on the high-resistance layer;
[0042] S153: growing the heteroepitaxial structure on the channel layer;
[0043] S155: growing the isolation layer on the heteroepitaxial structure;
[0044] S157: growing the barrier layer on the heteroepitaxial structure.
[0045] Wherein, step S153 specifically comprises: growing at least one superlattice structure on the channel layer; wherein, the superlattice structure comprises AlGaN layers and GaN layers grown in sequence.
[0046] In addition, after step S15, step S17 is further included, and step S17 specifically comprises:
[0047] S171: growing a protective layer on the barrier layer.
[0048] Step S171 specifically comprises: growing a first protective layer on the barrier layer; and growing a second protective layer on the first protective layer.
[0049] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A HEMT device, characterized by, The application relates to a semiconductor device, comprising: a substrate; a channel layer disposed on one side of the substrate, the material of the channel layer comprising undoped GaN; a heteroepitaxial structure comprising at least one superlattice structure formed by a stack of AlGaN layers and GaN layers, in each of the superlattice structures, the GaN layer is disposed on the side of the AlGaN layer away from the channel layer; a barrier layer disposed on the side of the heteroepitaxial structure away from the channel layer, the material of the barrier layer comprising AlGaN; wherein the total thickness of the channel layer and the heteroepitaxial structure is 150-350 nanometers, and the proportion of Al in the AlGaN layer is the same as the proportion of Al in the barrier layer.
2. The HEMT device of claim 1, wherein, The heteroepitaxial structure comprises at most three superlattice structures.
3. The HEMT device of claim 1, wherein, The thickness of each superlattice structure is less than or equal to 40 nanometers.
4. The HEMT device of claim 3, wherein, The thickness of the AlGaN layer is less than or equal to 10 nanometers, and the thickness of the GaN layer is greater than the thickness of the AlGaN layer and less than or equal to 30 nanometers.
5. The HEMT device of claim 3, wherein, The thickness of the channel layer ranges from 100 to 200 nanometers.
6. The HEMT device of claim 1, wherein, The superlattice structure further comprises an InGaN layer, and in each of the superlattice structures, the InGaN layer is disposed between the AlGaN layer and the GaN layer.
7. The HEMT device of any of claims 1-6, wherein, The thickness of the barrier layer ranges from 15 to 30 nanometers.
8. The HEMT device of claim 7, wherein, Further comprising an isolation layer disposed between the heteroepitaxial structure and the barrier layer, the material of the isolation layer comprising AlN, and the thickness of the isolation layer ranges from 1 to 2 nanometers.
9. The HEMT device of claim 8, wherein, Further comprising a high-resistance layer disposed between the substrate and the channel layer, the high-resistance layer being an undoped GaN layer.
10. The HEMT device of claim 9, wherein, Further comprising: a buffer layer disposed between the high-resistance layer and the substrate, the thickness of the buffer layer being 20-80 nanometers; and a protective layer disposed on the side of the barrier layer away from the heteroepitaxial structure, the thickness of the protective layer being 1-4 nanometers.