Enhanced GaN HEMT for improving single event burnout resistance

Abstract

The invention discloses an enhanced GaN HEMT (high electron mobility transistor) for improving single event burnout resistance, the enhanced GaN HEMT comprises a substrate, a layered buffer layer, a channel layer, a barrier layer and a passivation layer from bottom to top, the layered buffer layer comprises N buffer layers, N is greater than or equal to 2 and less than or equal to M. The buffer layers are made of the same material which is any one of Al < x > Ga < 1-x > N, In < x > Ga < 1-x > N and In < x > Al < 1-x > N, x is reduced layer by layer in the direction from the substrate (1) to the channel layer (3), and the reduction amplitude value of x in each layer is larger than or equal to 0.01. When the enhanced GaN HEMT is applied to a space environment, even if heavy ions are incident, the number of carriers entering a channel can be effectively reduced through a plurality of barriers formed in the layered buffer layer, so that the single particle burning resistance is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an enhanced GaN HEMT for improving the single particle burnout resistance capability. Background Art

[0002] Gallium nitride (GaN) high electron mobility transistors (HEMTs) have broad application prospects in the field of power electronics due to their advantages such as fast high-frequency response, high power density, and good high-temperature stability. In addition, due to the radiation resistance of GaN materials, power devices have important research and application potential in radiation environments such as spacecraft, satellite communications, space exploration, and nuclear energy facilities. However, there are a large number of heavy ions in the radiation environment, and GaN devices are sensitive to heavy ions under bias conditions and are prone to irreversible damage, which seriously restricts the application of GaN power devices in complex radiation environments.

[0003] In the prior art, for example, the patent “Transmissive GaN UV photocathode based on composition-gradient buffer layer” with application number 2010102094359 discloses a composition-gradient buffer layer. The material composition or doping concentration of the gradient buffer layer changes continuously and slightly. Therefore, in the energy band diagram, the energy band presents a “slope-like” distribution without obvious energy band mutation. Therefore, it will not isolate the carriers in the buffer layer, and will not reduce the collection of electrons by the drain, and will not improve the ability to resist single-particle burnout. In the patent “A GaN HEMT multi-level heterogeneous buffer layer structure” with application number 2024101969355, a multi-level heterogeneous buffer layer structure is proposed. In a space environment, heavy ions may be incident from various positions of the device at various angles. If the buffer layer is layered vertically, such as Figure 2 As shown in the figure, when heavy ions are incident on C through only one buffer layer, the generated carriers will not be disturbed by the potential barrier and can easily flow into the channel region, and the same single particle burnout phenomenon will occur; and the vertical layering will be more complicated in terms of process. At the same time, due to the lattice mismatch at the interface between the layers, stress concentration may occur at the interface, and even dislocation may occur, introducing more defects. This may make the device more susceptible to device degradation due to defects in the space environment, and defects may cause the electrical characteristics of the device itself to decrease, such as increasing resistance or reducing mobility. Therefore, it is necessary to study a gallium nitride device suitable for the space environment with improved resistance to single particle burnout. Summary of the invention

[0004] The present invention provides an enhanced GaN HEMT for improving the single particle burnout resistance capability, so as to overcome the technical problem that the GaN HEMT in the prior art has a weak single particle burnout resistance capability and is easily damaged when used in a space environment.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] An enhanced GaN HEMT for improving the ability to resist single-particle burnout comprises, from bottom to top, a substrate, a layered buffer layer, a channel layer, a barrier layer and a passivation layer, wherein the layered buffer layer comprises:

[0007] There are N buffer layers, 2≤N≤M, and the material of each buffer layer is the same, which is Al x Ga 1-x N、In x Ga 1-x N and In x Al 1-x Any one of N, wherein x decreases layer by layer along the direction from the substrate to the channel layer, and the amplitude value of the decrease of x in each layer is greater than or equal to 0.01.

[0008] Furthermore, the buffer layer in the N-layer buffer layer adjacent to the communication layer is a channel buffer layer, and the thickness of the channel buffer layer is not less than 0.1 μm.

[0009] Furthermore, a P-GaN layer, a source and a drain are provided on the upper surface of the barrier layer, the P-GaN layer is adjacent to the passivation layer, and the source and the drain are respectively provided at two ends of the barrier layer; a gate is provided above the P-GaN layer, a drain field plate is provided on the side of the upper surface of the passivation layer close to the drain, and a gate field plate is provided on the side of the upper surface of the passivation layer close to the gate.

[0010] Furthermore, the distance between the gate field plate and the drain field plate is not less than 20% of the distance between the drain and the gate.

[0011] Furthermore, the value of M is 5.

[0012] Beneficial effects: The present invention designs an enhanced GaN HEMT with a layered buffer layer structure, and the component x decreases layer by layer along the direction from the substrate to the channel layer, and the value of the reduction of x in each layer is greater than or equal to 0.01. In a space environment, after heavy ion incidence, the multiple potential barriers formed inside the layered buffer layer effectively reduce the number of carriers entering the channel, thereby improving the single particle burnout resistance of the enhanced GaN HEMT device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 It is a schematic diagram of the structure of an enhanced GaN HEMT used for improving the single particle burnout resistance in the present invention;

[0015] Figure 2 A schematic diagram of a GaN HEMT multi-level heterogeneous buffer layer structure according to an embodiment of the present invention;

[0016] Figure 3 is a comparison diagram of basic characteristic curves of a conventional structure and a reinforced structure in an embodiment of the present invention;

[0017] Figure 4 is a curve comparison diagram of the change of drain current over time of the conventional structure and the reinforced structure after heavy ion incidence with a linear energy conversion value of 0.71 pC / μm in the embodiment of the present invention;

[0018] Figure 5 It is a comparison diagram of the energy bands cut along the drain side of the gate field plate between the conventional structure and the reinforced structure in the embodiment of the present invention;

[0019] Figure 6 It is a comparison diagram of the electron concentration of the channel portion cut along the ion trajectory of the conventional structure and the reinforced structure in the embodiment of the present invention when the ion is incident for 0.2ns.

[0020] In the figure: 1, substrate; 2, layered buffer layer; 21, first buffer layer; 3, channel layer; 4, barrier layer; 5, passivation layer; 6, P-GaN layer; 7, source; 8, drain; 9, gate; 10, gate field plate; 11, drain field plate;

[0021] A. Channel buffer layer. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] This embodiment provides an enhanced GaN HEMT for improving the single event burnout resistance. Figure 1 As shown, from bottom to top, it includes: a substrate 1, a layered buffer layer 2, a channel layer 3, a barrier layer 4 and a passivation layer 5, and the layered buffer layer 2 includes:

[0024] There are N buffer layers, 2≤N≤M, and the material of each buffer layer is the same, which is Al x Ga 1-x N、Inx Ga 1-x N and In x Al 1-x Any one of N, wherein x decreases layer by layer along the direction from the substrate 1 to the channel layer 3, and the amplitude value of the decrease of x in each layer is greater than or equal to 0.01.

[0025] Specifically, the enhanced GaN HEMT for improving the ability to resist single-particle burnout proposed in this embodiment can effectively adjust the lateral electric field distribution through the proposed layered buffer layer without affecting its other basic characteristics, reduce the carriers entering the channel, reduce the amount of electrons collected at the drain, and increase the voltage threshold for single-particle burnout to improve the ability to resist single-particle burnout. Specifically, the layered buffer layer is composed of a plurality of discrete buffer layers, and x decreases layer by layer along the direction from the substrate 1 to the channel layer 3. Since the value of the reduction of x in each layer is greater than or equal to 0.01, in the energy band diagram, there will be a band mutation at the interface between adjacent buffer layers, that is, the conduction band and the valence band jump discontinuously at the interface, and the energy band presents a "sawtooth" distribution. In a space environment, after heavy ions are incident, the enhanced GaN HEMT for improving the ability to resist single-particle burnout can isolate the newly generated carriers between two high potential barriers, so that they cannot flow into the channel region, thereby reducing the collection of electrons by the drain, and ultimately reducing the possibility of single-particle burnout.

[0026] Specifically, if the composition difference between adjacent buffer layers is too small, a high potential barrier that can effectively block carriers will not be formed. Therefore, this embodiment sets the amplitude value of the reduction of x in each layer to be greater than or equal to 0.01, thereby improving the single-particle burnout resistance of the device.

[0027] In a specific embodiment, Figure 1 As shown, the layered buffer layer includes a first buffer layer 21, ..., an Mth buffer layer A, wherein the buffer layer adjacent to the communication layer 3 among the N buffer layers, i.e., the Mth buffer layer is a channel buffer layer A, and the thickness of the channel buffer layer A is not less than 0.1 μm.

[0028] Specifically, in this embodiment, to ensure that the electrical characteristics of the device are not affected, the thickness of the channel buffer layer A is set to be no less than 0.1 μm, thereby preventing the potential barrier formed at the interface from affecting the two-dimensional electron gas in the channel and further affecting the electrical characteristics of the device.

[0029] In a specific embodiment, the upper surface of the barrier layer 4 is further provided with a P-GaN layer 6, a source electrode 7 and a drain electrode 8, the P-GaN layer 6 is adjacent to the passivation layer 5, and the source electrode 7 and the drain electrode 8 are respectively arranged at both ends of the barrier layer 4;

[0030] A gate 9 is disposed above the P-GaN layer 6 , a drain field plate 11 is disposed on the upper surface of the passivation layer 5 near the drain 8 , and a gate field plate 10 is disposed on the upper surface of the passivation layer 5 near the gate 9 .

[0031] Specifically, Figure 1 As shown, in this embodiment, a drain field plate 11 with the same thickness as the gate field plate is introduced on the left side of the drain. The drain field plate 11 can lead the high electric field at the drain to the left side of the drain. Without sacrificing the basic electrical characteristics of the device, the internal electric field distribution of the device is optimized, which can not only realize more complex drain electric field modulation and improve the breakdown voltage, but also avoid the single particle burnout of the device caused by local electric field concentration, and further improve the single particle burnout resistance of the enhancement mode GaN HEMT device.

[0032] Specifically, the drain field plate 11 should not be too long or too short. If it is too long, the electric field peak at one end of the drain field plate will overlap with the electric field peak at one end of the gate field plate, resulting in a decrease in the breakdown voltage. If it is too short, the effect of the drain field plate will be reduced. Therefore, in this embodiment, the distance between the gate field plate 10 and the drain field plate 11 is set to be no less than 20% of the distance between the drain 8 and the gate 9.

[0033] In a specific embodiment, if the number of buffer layers is large, the process is difficult to implement and the cost is high, so the value of M is 5 in this embodiment.

[0034] In a specific embodiment, the substrate is made of any one of sapphire, SiC, GaN, or Si, and has a thickness of 3 μm;

[0035] In a specific embodiment, the material of the channel layer is GaN, and its thickness is 0.2 μm;

[0036] In a specific embodiment, the barrier layer is made of AlGaN with a thickness of 15 nm;

[0037] In a specific embodiment, the material of the passivation layer is any one of SiNx, Al2O3, and SiO2, and the thickness thereof is 0.6 μm.

[0038] In a specific embodiment, the distance between the source and the gate is 2.5 μm, and the distance between the drain and the gate is 7 μm.

[0039] In a specific embodiment, the length of the gate field plate is 4 μm, and the length of the drain field plate is 0.8 μm.

[0040] In this embodiment, the enhanced GaN HEMT reinforcement structure with added layered buffer layer 2 and drain field plate 11 and the traditional GaN HEMT structure proposed in this embodiment are modeled and simulated using Sentaurus TCAD semiconductor device simulation software. The results are as follows: Figures 3 to 6 shown.

[0041] The basic characteristics of the reinforcement structure proposed by the present invention and the traditional structure are simulated and compared, such as Figure 3 As shown, since the reinforcement structure proposed in the present invention does not affect the two-dimensional electron gas in the channel, the threshold voltage of the two devices is 2.5V when the drain bias is 10V, and when the gate bias is 2V, the output capacity when the drain bias is 2, 4, and 6V remains unchanged. It proves that the basic characteristics of the structure proposed in the present invention are almost the same as those of the traditional structure, and do not affect other device performances.

[0042] The single particle burnout characteristics of the reinforcement structure proposed in the present invention and the traditional structure are simulated and compared. Since the drain field plate is added to the reinforcement structure proposed in the present invention, the internal electric field of the device is optimized, and the potential barrier of the buffer layer is adjusted, which reduces the electrons flowing into the channel, reduces the collection of electrons by the drain, and reduces the possibility of single particle burnout. For traditional devices, after heavy ion incidence, a large number of electron-hole pairs will be generated inside the device. The electrons will be affected by the energy provided by the high electric field at the gate field plate and move quickly to the drain. The drain current increases instantly, causing irreversible damage to the device. Figure 4 As shown, the traditional structure has a burnout problem when the drain bias is 140V under the incidence of heavy ions, while the reinforced structure proposed in the present invention can increase the drain bias to 470V before the single particle burnout phenomenon occurs, which is an improvement of 235%. It proves that the structure proposed in the present invention has good single particle burnout resistance performance.

[0043] The reinforcement structure proposed by the present invention and the conventional structure are compared along the cut energy band of the gate field plate near the drain side. Figure 5 As shown in Figure 1, at the interface of the double buffer layer, the energy band is raised, forming an obvious potential barrier. This barrier can effectively hinder the cross-layer flow of carriers, thereby reducing the carrier concentration in the channel.

[0044] When the ion incident on the reinforced structure proposed by the present invention and the conventional structure is 0.2ns, Figure 6 As shown in the figure, the electron concentration of the reinforced structure is reduced compared with the traditional structure, which indicates that the potential barrier at the interface of the double buffer layer effectively prevents the new carriers generated by the heavy ion incidence from flowing into the channel. This proves the effectiveness of the multiple buffer layer reinforcement.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An enhanced GaN HEMT for improving single event burnout resistance, comprising from bottom to top: A substrate (1), a layered buffer layer (2), a channel layer (3), a barrier layer (4) and a passivation layer (5), wherein the layered buffer layer (2) comprises: There are N buffer layers, 2≤N≤M, and the material of each buffer layer is the same, which is Al x Ga 1-x N、In x Ga 1-x N and In x Al 1-x Any one of N, wherein x decreases layer by layer along the direction from the substrate (1) to the channel layer (3), and the amplitude value of the decrease of x in each layer is greater than or equal to 0.

01.

2. The enhanced GaN HEMT for improving single event burnout resistance according to claim 1, characterized in that: The buffer layer in the N-layer buffer layer that is adjacent to the communication layer (3) is a channel buffer layer (A), and the thickness of the channel buffer layer (A) is not less than 0.1 μm.

3. The enhanced GaN HEMT for improving the single event burnout resistance according to claim 2, characterized in that: The upper surface of the barrier layer (4) is also provided with a P-GaN layer (6), a source electrode (7) and a drain electrode (8); the P-GaN layer (6) is adjacent to the passivation layer (5); and the source electrode (7) and the drain electrode (8) are respectively arranged at two ends of the barrier layer (4); A gate electrode (9) is provided above the P-GaN layer (6), a drain field plate (11) is provided on the side of the upper surface of the passivation layer (5) close to the drain electrode (8), and a gate field plate (10) is provided on the side of the upper surface of the passivation layer (5) close to the gate electrode (9).

4. The enhanced GaN HEMT for improving the single event burnout resistance according to claim 3, characterized in that: The distance between the gate field plate (10) and the drain field plate (11) is not less than 20% of the distance between the drain (8) and the gate (9).

5. The enhanced GaN HEMT for improving single event burnout resistance according to claim 2, characterized in that: The value of M is 5.

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