An anti-single-particle GaN HEMT device with a comb channel structure

Abstract

The application 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, from bottom to top, a buffer layer, a barrier layer, a passivation layer, a source, a gate and a drain, and further comprises a comb-shaped channel structure, wherein the comb-shaped channel structure is located on the left side of the drain, above the barrier layer, and a blocking layer exists between the drain and the barrier layer. The application introduces a comb-shaped n-type AlGaN channel on the left side of the drain and separates the drain from the barrier layer by the blocking layer; a large number of carriers generated after single-particle incidence can be discharged through the comb-shaped n-type AlGaN channel, not only the electric field near the drain is modulated, but also the high voltage near the drain is borne by the blocking layer, the high field formed on the side of the drain close to the gate after single-particle incidence is greatly reduced, the collision ionization rate of the carriers near the drain and the transient current in the device are reduced, and the single-particle burnout voltage of the device is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductors and relates to a single-event-resistant GaN HEMT device with a comb-shaped channel structure. BACKGROUND

[0002] Gallium nitride (GaN) based high electron mobility transistors (HEMTs) as a representative of the third generation of semiconductor devices, with its wide bandgap (3.4 eV), high critical breakdown field (3.3 MV / cm) and high electron saturation drift velocity (2.5 x 10 7 cm / s), show revolutionary potential in the fields of radio frequency 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 12 MV / cm, and its bandgap is twice that of GaN. Therefore, using AlGaN, an alloy of GaN and AlN, as the channel material can increase the breakdown voltage without reducing the current density. The two-dimensional electron gas (2DEG) surface density of HEMT devices based on AlGaN / GaN heterostructures can reach 1 x 10 -2 cm / s, making it an ideal replacement for silicon-based devices in high-voltage, high-frequency and high-efficiency scenarios. In recent years, with the rapid development of deep space exploration, low-orbit satellite constellations and other space missions, GaN HEMTs have been widely used in key areas such as spaceborne power systems and ion thruster drive modules due to their radiation resistance. However, the single-event effects (SEEs) caused by high-energy particles (such as heavy ions and protons) in the space radiation environment, especially single-event burnout (SEB), severely restricts the reliability of GaN power devices in high-voltage operating 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 material, which makes them highly resistant to radiation-induced defects. In addition, the high electron mobility of AlGaN HEMTs reduces the probability of charge trapping and trap-induced gate leakage current, which further enhances the radiation resistance of these devices. However, single-event effects, as a typical form of transient radiation damage, have a completely different mechanism from total ionizing dose (TID): when high-energy heavy ions (such as iron ions in cosmic rays) are incident on the interior of a GaN power semiconductor device, they transfer their energy to the electrons in the device material, which generates a corresponding incident track through ionization within the device, and along the track, a high density of electron-hole pairs (>1 x 10 19 cm -3), the current of the device changes instantaneously, triggering a local avalanche multiplication effect, and eventually triggering permanent failure of the device.

[0004] To improve the SEB resistance of GaN HEMT, the academic circle has proposed various solutions: (1) structure 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 (C_gd), resulting in a decrease in switching speed; (2) material modification, using an Al composition gradient change AlGaN barrier layer to reduce the peak electric field through band engineering, but high Al content (> 30%) will cause lattice mismatch and interface defects, weakening the 2DEG mobility; (3) terminal protection design, such as integrating a Zener diode or a transient voltage suppressor (TVS), but such solutions require additional chip area and the response speed is difficult to match the nanosecond-level single particle transient. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an anti-single-particle GaN HEMT device with a comb-shaped channel structure, which 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, so that a large number of carriers generated after single particle incidence are discharged through the comb-shaped n-type AlGaN channel, reducing the collision 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] To achieve the above purpose, the present application provides the following technical solutions:

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

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

[0010] Further, the barrier layer adopts nitride, and the thickness range is 50nm-100nm, and the length range is 1um-2um.

[0011] Further, the thickness range of the buffer layer is 1um-5um.

[0012] Further, the barrier layer adopts AlGaN, and the thickness range is 15nm-25nm.

[0013] Further, the passivation layer adopts nitride, and the thickness range is 100nm-600nm.

[0014] The beneficial effects of the present application are as follows: the present application introduces a comb-shaped n-type AlGaN channel on the left side of the device drain, and uses a barrier layer to separate the drain and the barrier layer, so that a large number of carriers generated after the single particle incidence are discharged by the comb-shaped n-type AlGaN channel, not only the electric field near the drain is modulated, but also the high voltage near the drain is borne by the barrier layer, greatly reducing the high field formed on the side of the drain close to the gate after the single particle incidence, reducing the collision ionization rate of the carriers near the drain and the transient current in the device, and improving the single particle burnout voltage of the device.

[0015] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following specification, and will be learned from practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred detailed description of the present application will be combined with the drawings, in which:

[0017] Figure 1 The cross-sectional schematic diagram of the single-particle-resistant GaN HEMT device structure with a comb-shaped channel structure provided by an embodiment of the present application is shown in the figure;

[0018] Figure 2 The cross-sectional schematic diagram of a traditional enhancement-type GaN HEMT device structure is shown in the figure;

[0019] Figure 3 The electric field intensity distribution diagram of the traditional enhancement-type GaN HEMT device under the off state when a single particle is incident for 1x10 -9 s is shown in the figure;

[0020] Figure 4 The electric field intensity distribution diagram of the device of the present application under the off state when a single particle is incident for 1x10 -9 s is shown in the figure;

[0021] Figure 5 Figure 6 is a comparison chart of the simulation curves of the drain current versus time after the single particle injection at the off state of the conventional enhanced GaN HEMT device and the present application at the drain voltage of 270 V.

[0022] Figure 6 Figure 7 is a simulation curve chart of the drain current versus time after the single particle injection at the off state of the present application at the drain voltage of 740 V.

[0023] The reference numerals: 101-buffer layer, 102-potential 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-barrier layer. DETAILED DESCRIPTION

[0024] The above and other advantages and effects of the present application will become readily apparent to those of ordinary skill in the art from the description set forth below of specific, exemplary embodiments thereof, which description is made with reference to the accompanying drawings. The present application can be put into practice in various ways and can be embodied by different embodiments without departing from the spirit thereof, and the details of the description can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following examples only schematically illustrate the basic concept of the present application, and the features in the following examples and embodiments can be combined with each other without conflict.

[0025] The drawings are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical diagram, and should not be understood as a limitation on the present application; in order to better illustrate the embodiments of the present application, some components of the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product; it is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0026] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and should not be understood as a limitation on the present application, and for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0027] The application is based on the principle of reducing the collision ionization rate, i.e. reducing the high field at the drain end after heavy ion incidence, reducing the transient current in the device, and preventing the burning of the device, and proposes an anti-single-particle GaN HEMT device with a comb-shaped channel structure. 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 single-particle incidence to be discharged through the comb-shaped n-type AlGaN channel, not only modulating the electric field near the drain, but also allowing the high voltage near the drain to be borne by the barrier layer, greatly reducing the high field formed on the side of the drain close to the gate after single-particle incidence, reducing the collision ionization rate of the carriers near the drain and the transient current in the device, and improving the single-particle burnout voltage of the device.

[0028] As Figure 1 The anti-single-particle GaN HEMT device with a comb-shaped channel structure provided by the embodiment of the application is shown in the figure. The device includes, from bottom to top, a buffer layer 101, a barrier layer 102, and a passivation layer 103. A source electrode 104 and a drain electrode 106 are located at two ends above the barrier layer 102, respectively. A P-GaN layer 107 is provided above the barrier layer 102 on the right side of the source electrode 104, and a gate electrode 105 is located above the P-GaN layer 107. The drain electrode 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 electrode 106. The comb-shaped n-type AlGaN channel 108 is located above the barrier layer 102 and adjacent to the drain electrode 106, and is separated from below 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 1×1018 cm-3.

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

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

[0032] The P-GaN layer 107 is AlGaN, doped with P-type impurities, with a doping concentration of 4×1018 cm-3, a thickness of 100 nm, and a length of 2 μm.

[0033] The buffer layer 101 is GaN, with a thickness of 2 μm.

[0034] The barrier layer 102 is AlGaN, with 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 image shows a conventional enhancement-mode GaN HEMT device in the off state (device structure as shown). Figure 2 (As shown) After a single particle incident through 1×10 -9 The electric field intensity distribution at time s is shown, where a single particle is incident near the drain end of the gate. It can be observed that after the single particle incident through 1×10... -9 At time s, a high field is formed on the drain side of the device near the gate, which causes the charge carriers to undergo violent collisional ionization at that point, generating a large number of new electron-hole pairs, resulting in a surge in transient current.

[0037] Figure 4 The figure shows the device of the present invention in the off state after a single particle incident radiation of 1×10⁻⁶. -9 The electric field intensity distribution at time s is shown, where a single particle is incident near the drain end of the gate. It can be observed that after the single particle incident through 1×10s... -9 At time s, a high field is formed in the barrier layer 110 region of the present invention, while the electric field strength on the drain-to-gate side is much smaller than that of conventional devices. Furthermore, 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 structure of the comb-shaped n-type AlGaN channel 108 has a modulation effect on the electric field, thereby greatly reducing the electric field strength on the drain-to-gate side.

[0038] Figure 5 The figure shows a comparison of the simulated drain current versus time for the present invention and a conventional enhancement-mode GaN HEMT device in the off-state, with a drain voltage of 270V after a single-particle incident event. It can be observed that the linear energy transfer (LET) value of the incident single particle is 63.8 MeV·cm⁻¹. 2 At a drain voltage of 270V, conventional enhancement-mode GaN HEMT devices experience a sudden and irreversible increase in drain current after a period of time, resulting in single-event burn-out. In contrast, the drain current of this invention recovers to its normal value after a period of time at a drain voltage of 270V, without single-event burn-out. Therefore, the device of this invention has a higher single-event burn-out voltage than conventional enhancement-mode GaN HEMT devices, exhibiting superior single-event immunity.

[0039] Figure 6 The figure shows the simulated drain current versus time under off-state conditions with a drain voltage of 740V after a single-particle incident event. It can be seen that the linear energy transfer (LET) value of the incident single particle is 63.8 MeV·cm⁻¹. 2When the dose is 1.0*1011 / cm2 and the drain voltage is 740V, the drain current of the device of the present application can recover to the normal value after a period of time, and no single event burnout occurs. Therefore, the single event burnout voltage of the device of the present application is higher than 740V, which is much higher than the single event burnout voltage of the conventional enhancement-mode GaN HEMT device, and the anti-single event capability of the conventional device is greatly improved.

[0040] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions, which should be covered in the scope of the claims of the present application.

Claims

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

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

3. 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 50 nm to 100 nm and a length ranging from 1 μm to 2 μm.

4. The single-particle-resistant GaN HEMT device according to claim 1, characterized in that, The thickness of the buffer layer ranges from 1 μm to 5 μm.

5. 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 15 nm to 25 nm.

6. 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 100 nm to 600 nm.

7. The single-particle-resistant GaN HEMT device according to claim 1, 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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