Single-particle-resistant GaN HEMT device with comb-shaped channel structure

Abstract

The invention relates to an anti-single-particle GaN HEMT device with a comb-shaped channel structure, and belongs to the technical field of semiconductors. The device comprises a buffer layer, a barrier layer, a passivation layer, a source electrode, a grid electrode and a drain electrode from bottom to top and further comprises a comb-shaped channel structure, the comb-shaped channel structure is located on the left side of the drain electrode and above the barrier layer, and a blocking layer exists between the drain electrode and the barrier layer. According to the invention, the comb-shaped n-type AlGaN channel is introduced to the left side of the drain electrode, and the drain electrode is separated from the barrier layer by the barrier layer; a large number of carriers generated after incidence of a single particle can be discharged through the comb-shaped n-type AlGaN channel, an electric field near the drain electrode is modulated, high voltage near the drain electrode is borne by the blocking layer, a high field formed on the side, close to the grid electrode, of the drain electrode after incidence of the single particle is greatly reduced, and the reliability of the device is improved. The collision ionization rate of carriers near the drain electrode and the transient current in the device are reduced, and the single-particle burning voltage of the device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors and relates to a single-particle resistant GaN HEMT device with a comb-shaped channel structure. Background Art

[0002] As a representative of the third generation of semiconductor devices, gallium nitride (GaN)-based high electron mobility transistor (HEMT) has a wide bandgap (3.4 eV), high critical breakdown field (3.3 MV / cm) and high electron saturation drift velocity (2.5×10 7 cm / s), showing revolutionary potential in the field of RF power amplifiers and power electronics. Studies have shown that aluminum nitride (AlN) has almost the same saturated electron drift velocity as GaN, but its breakdown field strength can reach 12MV / cm, and its bandgap width is twice that of GaN. Therefore, using AlGaN, an alloy of GaN and AlN, as a channel material can increase the breakdown voltage without reducing the current density. The surface density of the two-dimensional electron gas (2DEG) of the HEMT device based on the AlGaN / GaN heterostructure can reach 1×10^13cm -2 , the electron mobility exceeds 2000cm2 / (V·s), making it an ideal substitute for silicon-based devices in high-voltage, high-frequency and high-efficiency scenarios. In recent years, with the rapid development of space missions such as deep space exploration and low-orbit satellite constellations, GaN HEMT has been widely used in key areas such as onboard power systems and ion thruster drive modules due to its radiation resistance. However, single-event effects (SEEs), especially single-event burnout (SEB), caused by high-energy particles (such as heavy ions and protons) in the space radiation environment, have seriously restricted the reliability of GaN power devices under high-voltage conditions.

[0003] The radiation resistance of AlGaN HEMTs is due to the high radiation hardness of the AlGaN / GaN material system. This high radiation hardness is due to the high atomic number and high melting point of the materials, which make them highly resistant to radiation-induced defects. In addition, the high electron mobility of AlGaN HEMTs reduces the probability of charge capture and trap-induced gate leakage current, which further enhances the radiation resistance of these devices. However, the single-event effect, as a typical form of transient radiation damage, has a completely different mechanism of action from total radiation dose (TID): when high-energy heavy ions (such as iron ions in cosmic rays) are incident on the GaN power semiconductor body, they transfer their own energy to the electrons in the device material, and their energy generates a corresponding incident track through ionization inside the device, and a high density of electron-hole pairs (>1×10 19 cm -3), the current of the device changes instantaneously, triggering a local avalanche multiplication effect, which eventually leads to permanent failure of the device.

[0004] In order to improve the anti-SEB capability of GaN HEMT, the academic community has proposed a variety of solutions: (1) structural optimization, such as introducing a field plate or a step field plate to smooth the electric field distribution, but the field plate will increase the gate-drain capacitance (Cgd), resulting in a decrease in switching speed; (2) material modification, using an AlGaN barrier layer with a gradient Al composition to reduce the peak electric field through band engineering, but a high Al content (>30%) will cause lattice mismatch and interface defects, weakening the 2DEG mobility; (3) terminal protection design, such as integrated Zener diodes or transient voltage suppressors (TVS), but such solutions require additional chip area and the response speed is difficult to match the nanosecond single-particle transient. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a single-particle resistant GaN HEMT device with a comb-shaped channel structure, by introducing a comb-shaped n-type AlGaN channel on the left side of the drain, and separating the drain from the barrier layer with a barrier layer, so that a large number of carriers generated after single particle incidence are discharged through the comb-shaped n-type AlGaN channel, reducing the impact ionization rate of carriers near the drain and the transient current inside the device, and improving the single-particle burnout voltage of the device.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A single-particle resistant GaN HEMT device with a comb-shaped channel structure comprises a buffer layer, a barrier layer and a passivation layer from bottom to top, wherein a source, a drain and a P-GaN layer are formed in the passivation layer above the barrier layer, wherein a gate is formed above the P-GaN layer.

[0008] In addition, a comb-shaped n-type AlGaN channel is arranged in the passivation layer on the left side of the drain, and the comb-shaped n-type AlGaN channel is adjacent to the drain. The drain and the barrier layer are separated by a blocking layer.

[0009] Furthermore, the comb-shaped n-type AlGaN channel is separated by an embedded layer. The thickness of the comb-shaped n-type AlGaN channel ranges from 50nm to 150nm, and the length ranges from 0.5μm to 3μm. The embedded layer is made of nitride, with a thickness range of 50nm to 100nm and a length range of 0.1μm to 1μm, and the interval length between adjacent embedded layers ranges from 0.1μm to 1μm.

[0010] Furthermore, the barrier layer is made of nitride, with a thickness ranging from 50 nm to 100 nm and a length ranging from 1 μm to 2 μm.

[0011] Furthermore, the thickness of the buffer layer ranges from 1 μm to 5 μm.

[0012] Furthermore, the barrier layer is made of AlGaN, and its thickness ranges from 15nm to 25nm.

[0013] Furthermore, the passivation layer is made of nitride, and its thickness ranges from 100nm to 600nm.

[0014] The beneficial effect of the present invention is that: by introducing a comb-shaped n-type AlGaN channel on the left side of the device drain and separating the drain from the barrier layer with a barrier layer, a large number of carriers generated after a single particle is incident are discharged through the comb-shaped n-type AlGaN channel, which not only modulates the electric field near the drain, but also the high voltage near the drain is borne by the barrier layer, which greatly reduces the high field formed on the gate side of the drain after the single particle is incident, reduces the collision ionization rate of the carriers near the drain and the transient current inside the device, and improves the single particle burnout voltage of the device.

[0015] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0017] Figure 1 A schematic cross-sectional view of a single-particle resistant GaN HEMT device structure with a comb-shaped channel structure provided in one embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the cross-section of the structure of a conventional enhancement-mode GaN HEMT device;

[0019] Figure 3 The conventional enhancement-mode GaN HEMT device in the off state is subjected to a single particle incident on a 1×10 -9 The electric field intensity distribution at s;

[0020] Figure 4 The device of the present invention is in the off state when a single particle is incident through 1×10 -9 Electric field intensity distribution at s;

[0021] Figure 5 It is a comparison diagram of the simulation curves of the drain current and time after single particle incident of the present invention and the conventional enhanced GaN HEMT device in the off state at a drain voltage of 270V;

[0022] Figure 6 It is a simulation curve diagram of the drain current and time after a single particle is incident in the present invention under the off state and the drain voltage is 740V.

[0023] Reference numerals: 101 - buffer layer, 102 - barrier layer, 103 - passivation layer, 104 - source electrode, 105 - gate electrode, 106 - drain electrode, 107 - P-GaN layer, 108 - comb-shaped n-type AlGaN channel, 109 - embedded layer, 110 - blocking layer. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0025] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0026] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0027] The present invention is based on the principle of reducing the collision ionization rate, that is, reducing the high field appearing at the drain end after heavy ion incidence, reducing the transient current inside the device, and then preventing the device from burning. A single-particle GaN HEMT device with a comb-shaped channel structure is proposed. The device introduces a comb-shaped n-type AlGaN channel on the left side of the drain, and separates the drain from the barrier layer with a barrier layer. This structure allows a large number of carriers generated after a single particle is incident to be discharged through the comb-shaped n-type AlGaN channel, which not only modulates the electric field near the drain, but also transfers the high voltage near the drain to the barrier layer, greatly reducing the high field formed on the gate side of the drain after a single particle is incident, reducing the collision ionization rate of carriers near the drain and the transient current inside the device, and increasing the single-particle burnout voltage of the device.

[0028] like Figure 1 The figure shows a single-particle resistant GaN HEMT device with a comb-shaped channel structure provided by an embodiment of the present invention. The device includes a buffer layer 101, a barrier layer 102 and a passivation layer 103 from bottom to top. The source 104 and the drain 106 are respectively located at two ends above the barrier layer 102. A P-GaN layer 107 is provided above the barrier layer 102 on the right side of the source 104, and the gate 105 is located above the P-GaN layer 107. The drain 106 is separated from the barrier layer 102 by a barrier layer 110. A comb-shaped n-type AlGaN channel 108 is introduced on the left side of the drain 106. The comb-shaped n-type AlGaN channel 108 is located above the barrier layer 102 and adjacent to the drain 106. The comb-shaped n-type AlGaN channel 108 is separated from the drain 106 by an embedded layer 109.

[0029] The thickness of the comb-shaped n-type AlGaN channel 108 is 100 nm, and the length is 1 μm. The comb-shaped n-type AlGaN channel 108 is doped with n-type impurities, and the doping concentration is 1×10 18 cm -3 .

[0030] The embedded layer 109 is made of nitride, with a thickness of 50 nm and a length of 0.2 μm. The interval length between adjacent embedded layers is in the range of 0.2 μm.

[0031] The barrier layer 110 is made of nitride, with a thickness of 50 nm and a length of 1.5 μm.

[0032] The P-GaN layer 107 is made of AlGaN doped with P-type impurities, with a doping concentration of 4×10 18 cm -3 , a thickness of 100 nm, and a length of 2 μm.

[0033] The buffer layer 101 is made of GaN and has a thickness of 2 μm.

[0034] The barrier layer 102 is made of AlGaN and has a thickness of 25 nm.

[0035] The passivation layer 103 is made of nitride and has a thickness of 200 nm.

[0036] Figure 3 The figure shows a conventional enhancement-mode GaN HEMT device in the off state (the device structure is shown in FIG. Figure 2 As shown in the figure, a single particle incident on a 1×10 -9 The electric field intensity distribution at s, where a single particle is incident on the gate near the drain end. It can be found that when a single particle is incident on the gate through 1×10 -9 s, a high field is formed on the drain side of the device close to the gate, which causes violent impact ionization of carriers at this location, generating a large number of new electron-hole pairs, causing a surge in transient current.

[0037] Figure 4 The figure shows the device of the present invention in the off state when a single particle is incident through 1×10 -9 The electric field intensity distribution at s, where a single particle is incident on the gate near the drain end. It can be found that when a single particle is incident on the gate through 1×10 -9 s, the present invention forms a high field in the barrier layer 110 region, while the electric field strength on the drain side close to the gate is much smaller than that of the traditional device, and a high field is also formed near the connection between the comb-shaped n-type AlGaN channel 108 and the barrier layer 102. This is because the high field inside the device is borne by the barrier layer 110, and the comb-shaped n-type AlGaN channel 108 structure has a modulation effect on the electric field, thereby greatly reducing the electric field strength on the drain side close to the gate.

[0038] Figure 5 The figure shows the comparison of the simulation curves of the drain current and time of the present invention and the conventional enhanced GaN HEMT device under the off state with the drain voltage of 270V after the single particle is incident. It can be found that when the linear energy transfer value LET of the incident single particle is 63.8MeV·cm 2 / mg, when the drain voltage of the conventional enhanced GaN HEMT device is 270V, its drain current suddenly increases after a period of time and cannot be recovered, that is, single particle burnout occurs; while when the drain voltage of the present invention is 270V, its drain current can still recover to a normal value after a period of time, and no single particle burnout occurs. Therefore, the device of the present invention has a higher single particle burnout voltage than the conventional enhanced GaN HEMT device, and has a better single particle resistance capability than the conventional GaN HEMT device.

[0039] Figure 6 The figure shows the simulation curve of the drain current and time of the present invention in the off state when the drain voltage is 740V and a single particle is incident. It can be seen that when the linear energy transfer value LET of the incident single particle is 63.8MeV·cm 2 / mg, when the drain voltage of the present invention is 740V, the drain current can still recover to the normal value after a period of time, and no single particle burnout occurs. Therefore, the single particle burnout voltage of the device of the present invention is higher than 740V, far exceeding the single particle burnout voltage of the traditional enhanced GaN HEMT device, and greatly improving the single particle resistance of the traditional device.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A single-particle resistant GaN HEMT device with a comb-shaped channel structure, comprising a buffer layer, a barrier layer and a passivation layer from bottom to top, wherein a source electrode, a drain electrode and a P-GaN layer are formed in the passivation layer above the barrier layer, and a gate electrode is formed above the P-GaN layer, characterized in that: The drain electrode and the barrier layer are separated by a barrier layer. A comb-shaped n-type AlGaN channel is arranged in the passivation layer on the left side of the drain electrode, and the comb-shaped n-type AlGaN channel is adjacent to the drain electrode.

2. The single particle resistant GaN HEMT device according to claim 1, characterized in that: The comb-shaped n-type AlGaN channel is separated by an embedded layer.

3. The single particle resistant GaN HEMT device according to claim 2, characterized in that: The embedded layer is made of nitride, has a thickness ranging from 50nm to 100nm, a length ranging from 0.1μm to 1μm, and a spacing length ranging from 0.1μm to 1μm between adjacent embedded layers.

4. The single particle resistant GaN HEMT device according to claim 1, characterized in that: The barrier layer is made of nitride, with a thickness ranging from 50nm to 100nm and a length ranging from 1μm to 2μm.

5. The single particle resistant GaN HEMT device according to claim 1, characterized in that: The thickness of the buffer layer is in the range of 1 μm to 5 μm.

6. The single particle resistant GaN HEMT device according to claim 1, characterized in that: The barrier layer is made of AlGaN and has a thickness ranging from 15nm to 25nm.

7. The single particle resistant GaN HEMT device according to claim 1, characterized in that: The passivation layer is made of nitride and has a thickness ranging from 100nm to 600nm.

8. The single particle resistant GaN HEMT device according to claim 1 or 2, characterized in that: The thickness of the comb-shaped n-type AlGaN channel ranges from 50 nm to 150 nm, and the length ranges from 0.5 μm to 3 μm.

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