A GaN HEMT power device with built-in RC circuit

Abstract

The application belongs to the technical field of power semiconductors, and particularly relates to a GaN HEMT power device with a built-in RC circuit. On the basis of ensuring a certain P-GaN layer thickness and changing GaN from depletion mode to enhancement mode by depleting two-dimensional electrons, n-doped GaN and p-doped GaN are reflected between the P-GaN layer and the metallized gate. The intrinsic GaN capacitance and the edge capacitance in the traditional structure are changed. The structure can effectively increase the gate resistance, effectively increase the edge capacitance on the gate-source side and the gate-drain side, form a built-in RC absorber, and effectively solve the problems of loss and efficiency reduction caused by the external RC circuit of GaN. Meanwhile, the GaN device itself has certain EMI resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power semiconductors, and particularly relates to a GaN HEMT power device with an embedded RC circuit. BACKGROUND

[0002] Gallium nitride (GaN) is a wide-bandgap semiconductor material with a bandgap of 3.4 eV. Compared with traditional semiconductor materials such as silicon (Si) and gallium arsenide (GaAs), GaN has higher critical electric field, electron saturation drift speed, and good chemical stability. The AlGaN / GaN heterojunction high electron mobility transistor (HEMT) structure based on GaN material has higher electron mobility of more than 1800 cm 2 / vs and a two-dimensional electron gas (2-DEG) surface density of 10 13 cm 2 , so that the GaN-based device has very obvious advantages in the radio frequency field and the power electronics field.

[0003] The GaN device always faces the problem that the fast switching speed of GaN in the GaN application scenario due to the inherent high-frequency characteristics causes large di / dt and dv / dt, which easily excites serious high-frequency oscillation of the GaN device in the switching transient state. The high-frequency oscillation can cause serious electromagnetic interference, current overshoot, shoot-through, increased switching loss, and even reliability problems such as device damage. Currently, adding an RC circuit at the circuit level increases system loss and reduces efficiency. SUMMARY

[0004] In view of the problems in the prior art, the application provides a GaN HEMT power device with an embedded RC circuit. The gate resistance is improved to reduce the large di / dt and dv / dt slope of the GaN HEMT device under high-frequency operation, thereby suppressing oscillation. In addition, a parasitic capacitor is added between the metallized gate 5 and the metallized source 10, and a parasitic capacitor is added between the metallized gate 5 and the metallized drain 10. The embedded RC snubber (RC buffer) reduces EMI oscillation.

[0005] In order to achieve the above purpose, the application adopts the following technical scheme:

[0006] A GaN HEMT power device with an embedded RC circuit includes an AlN nucleation layer 1, a heavily doped AlGaN or GaN buffer layer 2 located on the AlN nucleation layer 1, a lightly doped GaN channel layer 3 located on the heavily doped AlGaN or GaN buffer layer 2, an AlGaN potential barrier layer 4 located on the lightly doped GaN channel layer 3, and a P-type doped Si substrate 11 located below the AlN nucleation layer 1.

[0007] Further comprising: a first Mg-doped p-GaN cap layer 6 on the AlGaN barrier layer 4; a second p-GaN layer 8 on the Mg-doped p-GaN cap layer 6, an n-GaN layer 7 between the two second p-GaN layers 8, a metalized gate 5 on the n-GaN layer 7 and the second p-GaN layer 8, a metalized source 9 on the left side of the AlGaN barrier layer 4; a metalized drain 10 on the right side of the AlGaN barrier layer 4; the metalized drain 10 and the lightly doped GaN channel layer 3 form an ohmic contact; the metalized source 9 and the lightly doped GaN channel layer 3 form an ohmic contact; the metalized gate 5 and the n-GaN layer 7, the second p-GaN layer 8 form a Schottky contact;

[0008] As a preferred mode, the n-GaN layer 7, the second p-GaN layer 8 are used to increase the gate resistance of the device, while the parasitic capacitance between the metalized gate 5 and the metalized source 9 is increased, and the parasitic capacitance between the metalized gate 5 and the metalized drain 10 is increased. Since GaN is usually operated at high frequency applications, a large current change rate (di / dt) and voltage change rate (dv / dt) will be generated. A large current change rate and voltage change rate will bring a certain overshoot, which will cause the device to be mistakenly turned on and cause unnecessary loss. The built-in RC snubber can reduce EMI oscillation, and the built-in RC snubber can reduce EMI oscillation.

[0009] The application further provides a second built-in RC loop GaN HEMT power device, comprising an AlN nucleation layer 1, a heavily doped AlGaN or GaN buffer layer 2 on the AlN nucleation layer 1, a lightly doped GaN channel layer 3 on the heavily doped AlGaN or GaN buffer layer 2, an AlGaN barrier layer 4 on the lightly doped GaN channel layer 3; a P-type doped Si substrate 11 under the AlN nucleation layer 1;

[0010] Further comprising a first Mg-doped p-GaN cap layer 6 on the AlGaN barrier layer 4, a second p-GaN layer 8 and an n-GaN layer 7 on the Mg-doped first p-GaN cap layer 6, the n-GaN layer 7 being on the right side of the second p-GaN layer 8, and a metalized gate 5 on the second p-GaN layer 8 and the n-GaN layer 7;

[0011] Also included are a metalized source 9 on the left side of the AlGaN barrier layer 4; a metalized drain 10 on the right side of the AlGaN barrier layer 4; the metalized source 9 and lightly doped GaN channel layer 3 form an ohmic contact; the metalized drain 10 and lightly doped GaN channel layer 3 form an ohmic contact; the metalized gate 5 and second p-GaN layer 8, n-GaN layer 7 form a Schottky contact.

[0012] The n-GaN layer 7, second p-GaN layer 8 are used to increase the gate resistance of the device, while adding parasitic capacitance between the metalized gate 5 and the metalized source 9, and adding parasitic capacitance between the metalized gate 5 and the metalized drain 10. Since GaN is usually operated at high frequency applications, it will generate a large current rate of change (di / dt), voltage rate of change (dv / dt). Larger current rate of change, voltage rate of change will bring a certain overshoot, so that the device is mistakenly turned on, causing unnecessary loss. The built-in RC snubber can reduce EMI oscillation, and the built-in RC snubber can reduce EMI oscillation.

[0013] As a preferred mode, the P-type doped Si substrate 11 is replaced by a SiC substrate, or a GaN substrate, or a sapphire substrate.

[0014] As a preferred mode, the n-GaN layer 7, second p-GaN layer 8 has a doping concentration of 10 14 -10 15 cm -3 , and a two-dimensional electron gas concentration region in the GaN channel layer 4 nm-5nm.

[0015] As a preferred mode, the doping concentration of the AlGaN barrier layer 4 is greater than 1e18, the doping concentration of the lightly doped GaN channel layer 3 is less than 1e15; the doping concentration of the Mg-doped first p-GaN cap layer 6 is greater than 1e16; the doping concentration of the heavily doped AlGaN or GaN buffer layer 2 is greater than 1e18.

[0016] The beneficial effects of the present application are: the present application inserts a second p-GaN layer 8, an n-GaN layer 7 between the original Mg-doped first p-GaN cap layer 6 and the metalized gate 5, which can raise the energy band at the two-dimensional electron gas by ensuring the thickness of the Mg-doped first p-GaN cap layer 6, so that the D-mode GaN can become E-mode GaN, while the p-GaN layer is laterally depleted, and the staggered arrangement of the n-GaN layer can increase the gate resistance, so as to reduce di / dt and dv / dt of the GaN HEMT device in the switching transient process, thereby suppressing EMI oscillation, and introducing a capacitor between the metalized source and the metalized gate, and the capacitor and the gate resistance further form an RC circuit, which further suppresses the EMI characteristic. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a structure schematic diagram of the existing GaN HEMT device;

[0018] Figure 2 It is a structure schematic diagram of a GaN HEMT power device with an embedded RC circuit according to Embodiment 1 of the present application;

[0019] Figures 3-8 It is a structure schematic diagram of a preparation method of a GaN HEMT power device with an embedded RC circuit according to Embodiment 1 of the present application;

[0020] Figure 9 It is a structure schematic diagram of a GaN HEMT power device with an embedded RC circuit according to Embodiment 2 of the present application;

[0021] In the drawings, the components represented by each reference numeral are listed as follows:

[0022] wherein 1 is an AlN nucleation layer, 2 is a heavily doped AlGaN or GaN buffer layer, 3 is a lightly doped GaN channel layer, 4 is an AlGaN barrier layer, 5 is a metalized gate, 6 is a Mg-doped first p-GaN cap layer, 7 is an n-GaN layer, 8 is a second p-GaN layer, 9 is a metalized source, 10 is a metalized drain, and 11 is a P-type doped Si substrate. DETAILED DESCRIPTION

[0023] In order to make the content and principles of the present application clearer, the technical solutions of the present application are described in detail below in combination with the drawings and specific embodiments.

[0024] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0025] Embodiment 1

[0026] A GaN HEMT power device with built-in RC circuit, comprising an AlN nucleation layer 1, a heavily doped AlGaN or GaN buffer layer 2 located on the AlN nucleation layer 1, a lightly doped GaN channel layer 3 located on the heavily doped AlGaN or GaN buffer layer 2, an AlGaN potential barrier layer 4 located on the lightly doped GaN channel layer 3; a P-type doped Si substrate 11 located below the AlN nucleation layer 1;

[0027] Further comprising: a first Mg-doped p-GaN cap layer 6 located on the AlGaN potential barrier layer 4; a second p-GaN layer 8 located on the Mg-doped p-GaN cap layer 6, an n-GaN layer 7 located between the two second p-GaN layers 8, a metalized gate 5 located on the n-GaN layer 7 and the second p-GaN layer 8, a metalized source 9 located on the left side of the AlGaN potential barrier layer 4; a metalized drain 10 located on the right side of the AlGaN potential barrier layer 4; the metalized drain 10 and the lightly doped GaN channel layer 3 form an ohmic contact; the metalized source 9 and the lightly doped GaN channel layer 3 form an ohmic contact; the metalized gate 5 and the n-GaN layer 7, the second p-GaN layer 8 form a Schottky contact.

[0028] The P-type doped Si substrate 11 is replaced by a SiC substrate, or a GaN substrate, or a sapphire substrate.

[0029] The doping concentration of the n-GaN layer 7 and the first n-GaN layer 8 is 10 14 -10 15 cm -3 , and the two-dimensional electron gas concentration region is in the GaN Channel layer 4 nm-5nm.

[0030] The doping concentration of the AlGaN potential barrier layer 4 is greater than 1e18, the doping concentration of the lightly doped GaN channel layer 3 is less than 1e15; the doping concentration of the first Mg-doped p-GaN cap layer 6 is greater than 1e16; the doping concentration of the heavily doped AlGaN or GaN buffer layer 2 is greater than 1e18.

[0031] With Figure 2Taking, for example, a GaN HEMT vertical device with high withstand voltage and low leakage current, the gain effect of the present invention is illustrated:

[0032] This invention inserts an n-GaN layer on top of the existing Mg-doped first p-GaN capping layer 6 and metallized gate 5. The n-GaN layer ensures that the thickness of the p-GaN barrier layer 4 can raise the energy band at the two-dimensional electron gas, allowing D-mode GaN to become E-mode GaN. At the same time, the lateral depletion of the p-GaN layer, n-GaN layer, and the staggered arrangement of the n-GaN layers can increase the gate resistance, thereby reducing the di / dt and dv / dt of the GaN HEMT device during the switching transient process and suppressing EMI oscillation. In addition, a capacitor is introduced between the metallized source and the metallized gate. The capacitor and the gate resistance further form an RC circuit, which further suppresses EMI characteristics.

[0033] This embodiment also provides a GaN HEMT power device with a built-in RC circuit, such as Figures 3-8 The steps shown are as follows:

[0034] Step 1: Grow a GaN HEMT heterojunction structure on the substrate, from bottom to top: substrate, nucleation layer, buffer layer, channel layer, and barrier layer. For example... Figure 3 As shown

[0035] Specifically, the growth methods used in the above steps include MOCVD (metal-organic chemical vapor deposition), MBE (molecular beam epitaxy), and HVPE (hydride vapor phase epitaxy).

[0036] Step 2: As Figure 4 As shown, the above structure is etched.

[0037] Step 3: As Figure 5 As shown, a p-GaN capping layer and an AlGaN barrier layer are grown on the above structure to raise the two-dimensional electron gas channel in the heterojunction below to above the internal Fermi level, thus completing the epitaxial structure growth. The GaN layer is a p-type GaN epitaxial layer with a thickness of 5-100 nm.

[0038] Step 4: Ion implantation is performed on the top 40 nm region of the epitaxially grown p-GaN capping layer, resulting in an N / P / N structure as shown below. Figure 6 As shown.

[0039] Step 5: Deposit a metallized gate in the above-mentioned region, such as... Figure 7 As shown.

[0040] Step 6: Deposit the metallized source and metallized drain in the above-mentioned region, such as... Figure 8 As shown.

[0041] Embodiment 2

[0042] As Figure 9 shown, a GaN HEMT power device with built-in RC circuit, including an AlN nucleation layer 1, a heavily doped AlGaN or GaN buffer layer 2 located on the AlN nucleation layer 1, a lightly doped GaN channel layer 3 located on the heavily doped AlGaN or GaN buffer layer 2, an AlGaN barrier layer 4 located on the lightly doped GaN channel layer 3; a P-type doped Si substrate 11 located below the AlN nucleation layer 1;

[0043] Further including a Mg-doped first p-GaN cap layer 6 located above the AlGaN barrier layer 4, a second p-GaN layer 8 and an n-GaN layer 7 located on the Mg-doped first p-GaN cap layer 6, the n-GaN layer 7 being located on the right side of the second p-GaN layer 8, a metallized gate 5 located above the second p-GaN layer 8 and the n-GaN layer 7;

[0044] Further including a metallized source 9 located on the left side of the AlGaN barrier layer 4; a metallized drain 10 located on the right side of the AlGaN barrier layer 4; the metallized source 9 and the lightly doped GaN channel layer 3 form an ohmic contact; the metallized drain 10 and the lightly doped GaN channel layer 3 form an ohmic contact; the metallized gate 5 and the second p-GaN layer 8, n-GaN layer 7 form a Schottky contact.

[0045] The n-GaN layer 7, the second p-GaN layer 8 are used to increase the gate resistance of the device, while increasing the parasitic capacitance between the metallized gate 5 and the metallized source 9, and the parasitic capacitance between the metallized gate 5 and the metallized drain 10. Since GaN usually works in high-frequency applications, it will produce a large current change rate (di / dt) and voltage change rate (dv / dt). A large current change rate and voltage change rate will bring a certain overshoot, causing the device to be mistakenly turned on and causing unnecessary loss. The built-in RC snubber can reduce EMI oscillation, achieving built-in RC snubber to reduce EMI oscillation.

[0046] Preferably, the P-type doped Si substrate 11 is replaced by a SiC substrate, or a GaN substrate, or a sapphire substrate.

[0047] The n-GaN layer 7, the second p-GaN layer 8 have a doping concentration of 1e14-1e15cm -3 , and a two-dimensional electron gas concentration region in the GaN channel layer 4 nm-5nm.

[0048] As a preferred mode, the doping concentration of the barrier layer 4 of AlGaN is greater than 1e18, the doping concentration of the lightly doped GaN channel layer 3 is less than 1e15; the doping concentration of the first Mg-doped p-GaN cap layer 6 is greater than 1e16; and the doping concentration of the heavily doped AlGaN or GaN buffer layer 2 is greater than 1e18.

[0049] The above embodiments only illustrate the principles and effects of the present application, but are not intended to limit the present application. Any modification or change made by those skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. An RC-embedded GaN HEMT power device, characterized by The device comprises an AlN nucleation layer (1), a heavily doped AlGaN or GaN buffer layer (2) on the AlN nucleation layer (1), a lightly doped GaN channel layer (3) on the heavily doped AlGaN or GaN buffer layer (2), an AlGaN barrier layer (4) on the lightly doped GaN channel layer (3), and a P-type doped Si substrate (11) under the AlN nucleation layer (1). The device further comprises a Mg-doped first p-GaN cap layer (6) on the AlGaN barrier layer (4), a second p-GaN layer (8) on the Mg-doped first p-GaN cap layer (6), an n-GaN layer (7) between the two second p-GaN layers (8), a metalized gate (5) on the n-GaN layer (7) and the second p-GaN layer (8), a metalized source (9) on the left side of the AlGaN barrier layer (4), and a metalized drain (10) on the right side of the AlGaN barrier layer (4).

2. The GaN HEMT power device with built-in RC circuit of claim 1, wherein: The n-GaN layer (7) and the second p-GaN layer (8) are used to increase the gate resistance of the device, while the metalized gate (5) and the metalized source (9) increase the parasitic capacitance between them, and the metalized gate (5) and the metalized drain (10) increase the parasitic capacitance between them.

3. A GaN HEMT power device with built-in RC circuit, comprising an AlN nucleation layer (1), a heavily doped AlGaN or GaN buffer layer (2) on the AlN nucleation layer (1), a lightly doped GaN channel layer (3) on the heavily doped AlGaN or GaN buffer layer (2), an AlGaN barrier layer (4) on the lightly doped GaN channel layer (3), and a P-type doped Si substrate (11) under the AlN nucleation layer (1). The device further comprises a Mg-doped first p-GaN cap layer (6) on the AlGaN barrier layer (4), a second p-GaN layer (8) on the Mg-doped first p-GaN cap layer (6), and an n-GaN layer (7) on the right side of the second p-GaN layer (8), and a metalized gate (5) on the second p-GaN layer (8) and the n-GaN layer (7). Further comprising a metalized source (9) on the left side of the AlGaN barrier layer (4); a metalized drain (10) on the right side of the AlGaN barrier layer (4); the metalized source (9) and the lightly doped GaN channel layer (3) form an ohmic contact; the metalized drain (10) and the lightly doped GaN channel layer (3) form an ohmic contact; the metalized gate (5) and the second p-GaN layer (8), n-GaN layer (7) form a Schottky contact.

4. The GaN HEMT power device with an embedded RC circuit of claim 3, wherein: The n-GaN layer (7), the second p-GaN layer (8) are used to increase the gate resistance of the device, while the parasitic capacitance between the metalized gate (5) and the metalized source (9) is increased, and the parasitic capacitance between the metalized gate (5) and the metalized drain (10) is increased.

5. The GaN HEMT power device with an embedded RC circuit according to any one of claims 1 to 4, characterized in that: The P-type doped Si substrate (11) is replaced by a SiC substrate, or a GaN substrate, or a sapphire substrate.

6. A GaN HEMT power device with an internal RC snubber according to any one of claims 1 to 4, characterized in that: The n-GaN layer (7), the second p-GaN layer (8) doping concentration is 1e14-1e15cm -3 , two-dimensional electron gas concentration area in the GaN Channel layer 4 nm-5nm.

7. A GaN HEMT power device with an internal RC snubber according to any one of claims 1 to 4, characterized in that: The doping concentration of the AlGaN barrier layer (4) is greater than 1e18, the doping concentration of the lightly doped GaN channel layer (3) is less than 1e15; the doping concentration of the first Mg-doped p-GaN cap layer (6) is greater than 1e16; the doping concentration of the heavily doped AlGaN or GaN buffer layer (2) is greater than 1e18.

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