A longitudinal GaN HEMT power device

Abstract

The application belongs to the technical field of power semiconductors, and particularly relates to a GaN HEMT power device with a longitudinal structure, which comprises an AlN nucleation layer, a heavily doped AlGaN or GaN buffer layer, a lightly doped GaN channel layer, an AlGaN barrier layer, a Schottky contact gate, a Mg-doped P-GaN cap layer, a metallized drain, a GaN current sink layer, a SiO2 isolation layer, a source-level field plate, a P-type doped Si substrate and a metallized source; the GaN HEMT power device with the longitudinal structure generates a high-concentration two-dimensional electron gas through the AlGaN barrier layer and the GaN channel layer, converts the current into a longitudinal direction through the GaN current sink layer, and the metal source-level field plate can effectively optimize the surface electric field, reduce the current collapse problem and improve the reliability. The GaN HEMT power device with the longitudinal structure changes the traditional lateral GaN which is subject to the current collapse and other problems. The GaN HEMT power device with the longitudinal structure has the advantages of low on-resistance, high reliability, high current density and large current capacity.

Description

Technical Field

[0001] This invention belongs to the field of power semiconductor technology, and specifically relates to a vertically structured GaN HEMT device. Background Technology

[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), it possesses higher critical electric field, electron saturation drift velocity, and good chemical stability. AlGaN / GaN heterojunction high electron mobility transistor (HEMT) structures based on GaN material exhibit electron mobilities exceeding 1800 cm⁻¹. 2 / vs and the surface density of two-dimensional electron gas (2-DEG) is approximately 10 13 cm -2 This gives GaN-based devices significant advantages in both radio frequency and power electronics fields.

[0003] Lateral GaN devices consistently face the challenge that the breakdown voltage (BV) is proportional to the gate-to-drain spacing, necessitating a larger lateral area to increase the voltage and consequently reducing integration density. Furthermore, lateral devices are severely affected by surface transverse well states and high electric fields, leading to reliability issues such as current collapse. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a GaN HEMT vertical device with high breakdown voltage and low leakage current. By using a current-controlled Sinker layer, a high concentration of electrons from the two-dimensional electron gas region is introduced into the bulk region. Under the action of the source metal field, the surface electric field can be optimized, thus expanding the design possibilities for GaN HEMT devices.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A vertical GaN HEMT power device includes 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, and an AlGaN barrier layer 4 on the lightly doped GaN channel layer 3.

[0007] It also includes a GaN current sink 8 located on the side of the AlN nucleation layer 1, the heavily doped AlGaN or GaN buffer layer 2, and the lightly doped GaN channel layer 3; a source field plate 10 located on the GaN current sink 8; the source field plate 10 extending above the Si3N4 passivation layer 9 and above the AlGaN barrier layer 4 between the Si3N4 passivation layer 9 and the metallized drain 7; a metallized source 12 located below the GaN current sink 8; and a P-type doped Si substrate 11 located between the metallized source 12 and the AlN nucleation layer 1.

[0008] It also includes a Mg-doped P-GaN capping layer 6 located on the AlGaN barrier layer 4; a Schottky contact gate 5 located on the Mg-doped P-GaN capping layer 6; a Si3N4 passivation layer 9 located between the Schottky contact gate 5 and the metallized drain 7 and above the AlGaN barrier layer 4; the metallized drain 7 and the lightly doped GaN channel layer 3 form an ohmic contact.

[0009] As a preferred embodiment, the metallized drain 7, the lightly doped GaN channel layer 3, the GaN current sink layer 8, and the metallized source 12 are used to achieve forward conduction of the semiconductor device. During forward conduction, the positive gate voltage causes the formation of a two-dimensional electron gas in the channel. When passing through the GaN current sink layer, the potential difference at the source and drain causes the current to flow vertically to the metallized source 12. The source field plate is used to optimize the surface electric field and solve the problem of current collapse.

[0010] The present invention also provides a second type of vertical GaN HEMT power device, comprising an AlN nucleation layer 1, a heavily doped AlGaN or GaN buffer layer 2 located on the nucleation layer 1, a lightly doped GaN channel layer 3 located on the heavily doped AlGaN or GaN buffer layer 2, and an AlGaN barrier layer 4 located on the lightly doped GaN channel layer 3.

[0011] It also includes a GaN current sinking layer 8 located on the side of the AlN nucleation layer 1, the heavily doped AlGaN or GaN buffer layer 2, and the lightly doped GaN channel layer 3, a Si3N4 passivation layer 9 located on the GaN current sinking layer 8, a metallized drain 7 located under the GaN current sinking layer 8, and a P-type doped Si substrate 11 located between the metallized drain 7 and the AlN nucleation layer 1;

[0012] It also includes a Mg-doped P-GaN capping layer 6 on the AlGaN barrier layer 4; a Schottky contact gate 5 on the Mg-doped P-GaN capping layer 6; and a Si3N4 passivation layer 9 on the Schottky contact gate 5 and the AlGaN barrier layer 4, wherein the metallization source stage 12 and the lightly doped GaN channel layer 3 form an ohmic contact; the metallization source stage 12 covers and extends along the surface of the Si3N4 passivation layer 9 to the region of the two-dimensional electron gas generated by the lightly doped GaN channel layer 3 and the AlGaN barrier layer 4.

[0013] The metallized drain 7, lightly doped GaN channel layer 3, GaN current sink layer 8, and metallized source 12 are used to realize the forward conduction of the semiconductor device. During forward conduction, the positive gate voltage causes the formation of a two-dimensional electron gas in the channel. When passing through the GaN current sink layer, the potential difference causes the current to flow vertically to the metallized source 12.

[0014] As a preferred embodiment, the doping concentration of the lightly doped GaN channel layer 3 is 10. 15 -10 16 cm -3 The concentration of two-dimensional electron gas (2-DEG) is on the order of magnitude, with the concentration region in the GaN Channel layer ranging from 4 nm to 5 nm.

[0015] As a preferred embodiment, the P-type doped Si substrate 11 can be replaced with a SiC substrate, a GaN substrate, or a sapphire substrate.

[0016] As a preferred embodiment, the doping concentration of the heavily doped AlGaN or GaN buffer layer 2 is greater than 1e18, and the doping concentration of the lightly doped GaN channel layer 3 is greater than 1e15.

[0017] Furthermore, the semiconductor is GaN.

[0018] The beneficial effects of this invention are as follows: The GaN current-sinking layer 8, source field plate 10, AlGaN barrier layer 4, and lightly doped GaN channel layer 3 utilize a high concentration of two-dimensional electron gas to convert the current vertically through the Sinker layer. The source metal field plate reduces the surface electric field and optimizes its distribution. It possesses advantages such as low on-resistance, low gate parasitic effect, high reliability, high current density, and high current capability, and its fabrication process is simple and easy to implement. It can effectively reduce leakage current and improve the breakdown voltage of GaNHEMT devices. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an existing GaN HEMT device;

[0020] Figure 2 This is a schematic diagram of the vertical GaN HEMT device structure according to Embodiment 1 of the present invention;

[0021] Figures 3-10 This is a schematic diagram of the GaN HEMT device fabrication method according to Embodiment 1 of the present invention;

[0022] Figure 11 This is a schematic diagram of the GaN HEMT device structure according to Embodiment 2 of the present invention.

[0023] The attached diagram lists the components represented by each number as follows:

[0024] 1 is the AlN nucleation layer, 2 is the heavily doped AlGaN or GaN buffer layer, 3 is the lightly doped GaN channel layer, 4 is the AlGaN barrier layer, 5 is the Schottky contact gate, 6 is the Mg-doped P-GaN capping layer, 7 is the metallized drain, 8 is the GaN current deposition layer, 9 is the Si3N4 passivation layer, 10 is the source field plate, 11 is the P-type doped Si substrate, and 12 is the metallized source. Detailed Implementation

[0025] To make the content and principles of the present invention clearer, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] An embodiment of the present invention provides a vertically structured GaN HEMT device:

[0027] To make the content and principles of the present invention clearer, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A vertical GaN HEMT power device includes 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, and an AlGaN barrier layer 4 on the lightly doped GaN channel layer 3.

[0031] It also includes a GaN current sink 8 located on the side of the AlN nucleation layer 1, the heavily doped AlGaN or GaN buffer layer 2, and the lightly doped GaN channel layer 3; a source field plate 10 located on the GaN current sink 8; the source field plate 10 extending above the Si3N4 passivation layer 9 and above the AlGaN barrier layer 4 between the Si3N4 passivation layer 9 and the metallized drain 7; a metallized source 12 located below the GaN current sink 8; and a P-type doped Si substrate 11 located between the metallized source 12 and the AlN nucleation layer 1.

[0032] It also includes a Mg-doped P-GaN capping layer 6 located on the AlGaN barrier layer 4; a Schottky contact gate 5 located on the Mg-doped P-GaN capping layer 6; a Si3N4 passivation layer 9 located between the Schottky contact gate 5 and the metallized drain 7 and above the AlGaN barrier layer 4; the metallized drain 7 and the lightly doped GaN channel layer 3 form an ohmic contact.

[0033] The metallized drain 7, lightly doped GaN channel layer 3, GaN current sink layer 8, and metallized source 12 are used to achieve forward conduction of the semiconductor device. During forward conduction, the positive gate voltage causes the formation of a two-dimensional electron gas in the channel. When passing through the GaN current sink layer, the potential difference at the source and drain will cause the current to flow vertically to the metallized source 12. The source field plate is used to optimize the surface electric field and solve the problem of current collapse.

[0034] The doping concentration of the lightly doped GaN channel layer 3 is 10. 15 -10 16 cm -3 The concentration of two-dimensional electron gas (2-DEG) is on the order of magnitude, with the concentration region in the GaN Channel layer ranging from 4 nm to 5 nm.

[0035] The P-type doped Si substrate 11 is replaced with a SiC substrate, or a GaN substrate, or a sapphire substrate.

[0036] The doping concentration of the heavily doped AlGaN or GaN buffer layer 2 is greater than 1e18; the doping concentration of the lightly doped GaN channel layer 3 is greater than 1e15.

[0037] See Figures 3-10 A schematic diagram of a method for fabricating a vertically oriented GaN HEMT device is provided:

[0038] 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.

[0039] Specifically, the growth methods used in the above steps include MOCVD, MBE, and HVPE.

[0040] Step 2: As Figure 4 As shown, the above structure is etched to form a GaN current deposition layer.

[0041] Specifically, the etching methods used in the above steps include ICP and PEC.

[0042] Step 3: Grow a P-GAN layer based on the above, and form a metallized gate after etching. Figure 5 The structure shown.

[0043] Step 4: Based on the above, Si3N4 is deposited to form a structure like... Figure 6 The structure shown.

[0044] Step 5: The etched structure is then subjected to magnetron sputtering to grow a metal source-level field plate and deposit a dielectric layer, forming a structure as shown above. Figure 7 The structure shown.

[0045] Step 6: Etch the drain contact hole and deposit metal to form a shape like... Figures 8-9 The structure shown

[0046] Step 7: Perform back metal deposition to form a metal source stage. Forming such a... Figure 10 The structure shown.

[0047] by Figure 2 For example, the working principle of this embodiment will be explained:

[0048] When the device is forward-biased, a positive voltage is applied to the gate, along with a forward voltage greater than the threshold voltage, causing a two-dimensional electron gas to form in the channel. The current flows from the metallized drain 7, through the region of the two-dimensional electron gas formed by the lightly doped GaN channel layer 3 and the AlGaN barrier layer 4, through the GaN current sink layer (Sinker layer) 8, and towards the metallized source 12. This process transforms the traditional lateral structure of the GaN HEMT device into a vertical structure, allowing the source-level field plate 10 to optimize the surface electric field and reduce current collapse.

[0049] When the device withstands reverse voltage, the main difference from the conventional GaN HEMT device lies in the doping of the P-type doped Si substrate 11, the AlN nucleation layer 1, and the heavily doped AlGaN or GaN buffer layer 2. In this invention, MOCVD growth is performed on the P-type doped Si substrate using a (1 1 1) crystal plane, while attention should be paid to the doping of the buffer layer. The withstand voltage is then related to the thickness of the P-type doped Si substrate 11, the AlN nucleation layer 1, and the heavily doped AlGaN or GaN buffer layer 2, i.e., the distance between the metallized drain 7 and the metallized source 12.

[0050] Example 2

[0051] like Figure 11 As shown, a vertical GaN HEMT power device includes an AlN nucleation layer 1, a heavily doped AlGaN or GaN buffer layer 2 on the nucleation layer 1, a lightly doped GaN channel layer 3 on the heavily doped AlGaN or GaN buffer layer 2, and an AlGaN barrier layer 4 on the lightly doped GaN channel layer 3.

[0052] It also includes a GaN current sinking layer 8 located on the side of the AlN nucleation layer 1, the heavily doped AlGaN or GaN buffer layer 2, and the lightly doped GaN channel layer 3, a Si3N4 passivation layer 9 located on the GaN current sinking layer 8, a metallized drain 7 located under the GaN current sinking layer 8, and a P-type doped Si substrate 11 located between the metallized drain 7 and the AlN nucleation layer 1;

[0053] It also includes a Mg-doped P-GaN capping layer 6 on the AlGaN barrier layer 4; a Schottky contact gate 5 on the Mg-doped P-GaN capping layer 6; and a Si3N4 passivation layer 9 on the Schottky contact gate 5 and the AlGaN barrier layer 4, wherein the metallization source stage 12 and the lightly doped GaN channel layer 3 form an ohmic contact; the metallization source stage 12 covers and extends along the surface of the Si3N4 passivation layer 9 to the region of the two-dimensional electron gas generated by the lightly doped GaN channel layer 3 and the AlGaN barrier layer 4.

[0054] The metallized drain 7, lightly doped GaN channel layer 3, GaN current sink layer 8, and metallized source 12 are used to realize the forward conduction of the semiconductor device. During forward conduction, the positive gate voltage causes the formation of a two-dimensional electron gas in the channel. When passing through the GaN current sink layer, the potential difference causes the current to flow vertically to the metallized source 12.

[0055] Specifically, the doping concentration of the lightly doped GaN channel layer 3 is 10. 15 -10 16 cm -3 The concentration of two-dimensional electron gas (2-DEG) is on the order of magnitude, with the concentration region in the GaN Channel layer ranging from 4 nm to 5 nm.

[0056] Specifically, the P-type doped Si substrate 11 is replaced with a SiC substrate, or a GaN substrate, or a sapphire substrate.

[0057] The doping concentration of the heavily doped AlGaN or GaN buffer layer 2 is greater than 1e18; the doping concentration of the lightly doped GaN channel layer 3 is greater than 1e15.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A vertical GaN HEMT power device, characterized in that: It includes 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), and an AlGaN barrier layer (4) on the lightly doped GaN channel layer (3). It also includes a GaN current sink layer (8) located on the side of the AlN nucleation layer (1), the heavily doped AlGaN or GaN buffer layer (2), and the lightly doped GaN channel layer (3), a source field plate (10) located on the GaN current sink layer (8), the source field plate (10) extending above the Si3N4 passivation layer (9) and above the AlGaN barrier layer (4) between the Si3N4 passivation layer (9) and the metallized drain (7), a metallized source (12) located below the GaN current sink layer (8), and a P-type doped Si substrate (11) located between the metallized source (12) and the AlN nucleation layer (1). It also includes a Mg-doped P-GaN capping layer (6) on the AlGaN barrier layer (4); a Schottky contact gate (5) on the Mg-doped P-GaN capping layer (6); a Si3N4 passivation layer (9) between the Schottky contact gate (5) and the metallized drain (7) and above the AlGaN barrier layer (4); the metallized drain (7) and the lightly doped GaN channel layer (3) form an ohmic contact.

2. The vertical GaN HEMT power device according to claim 1, characterized in that: The metallized drain (7), lightly doped GaN channel layer (3), GaN current sink layer (8), and metallized source (12) are used to realize the forward conduction of the semiconductor device. During forward conduction, the positive gate voltage causes the formation of a two-dimensional electron gas in the channel. When passing through the GaN current sink layer, the potential difference at the source and drain will cause the current to flow vertically to the metallized source (12). The source field plate is used to optimize the surface electric field and solve the problem of current collapse.

3. A vertical GaN HEMT power device, comprising an AlN nucleation layer (1), a heavily doped AlGaN or GaN buffer layer (2) on the nucleation layer (1), a lightly doped GaN channel layer (3) on the heavily doped AlGaN or GaN buffer layer (2), and an AlGaN barrier layer (4) on the lightly doped GaN channel layer (3); It also includes a GaN current sink layer (8) located on the side of the AlN nucleation layer (1), the buffer layer (2) of heavily doped AlGaN or GaN, and the lightly doped GaN channel layer (3), a Si3N4 passivation layer (9) located on the GaN current sink layer (8), a metallized drain (7) located under the GaN current sink layer (8), and a P-type doped Si substrate (11) located between the metallized drain (7) and the AlN nucleation layer (1). It also includes a Mg-doped P-GaN capping layer (6) on the AlGaN barrier layer (4); a Schottky contact gate (5) on the Mg-doped P-GaN capping layer (6); and a Si3N4 passivation layer (9) on the Schottky contact gate (5) and the AlGaN barrier layer (4), wherein the metallized source (12) and the lightly doped GaN channel layer (3) form an ohmic contact; the metallized source (12) covers and extends along the surface of the Si3N4 passivation layer (9) to the region of the two-dimensional electron gas generated by the lightly doped GaN channel layer (3) and the AlGaN barrier layer (4); Its features are: The metallized drain (7), lightly doped GaN channel layer (3), GaN current sink layer (8), and metallized source (12) are used to realize the forward conduction of the semiconductor device. When the forward conduction is achieved, the positive gate voltage causes the two-dimensional electron gas in the channel to be formed. When passing through the GaN current sink layer, the potential difference causes the current to flow vertically to the metallized source (12).

4. A vertical GaN HEMT power device according to any one of claims 1 to 3, characterized in that: The doping concentration of the lightly doped GaN channel layer (3) is 10 15 -10 16 cm -3 The concentration of two-dimensional electron gas (2-DEG) is on the order of magnitude, with a concentration region of 4 nm-5 nm in the GaN channel layer.

5. A vertical GaN HEMT power device according to any one of claims 1 to 3, characterized in that: The P-type doped Si substrate (11) is replaced with a SiC substrate, or a GaN substrate, or a sapphire substrate.

6. A vertical GaN HEMT power device according to any one of claims 1 to 3, characterized in that: The doping concentration of the heavily doped AlGaN or GaN buffer layer (2) is greater than 1e18; the doping concentration of the lightly doped GaN channel layer (3) is greater than 1e15.

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