GaN-based HEMT device with T-shaped gate structure
By adopting the T -type grid structure in the GAN base HEMT device, the short -channel effect and multi -finger -increased electrode coupling capacitance problem caused by the short grid long structure and the multi -finger structure increased the effect of improving the frequency characteristics and power characteristics.
Patent Information
- Application Number
- CN202420778935.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-16
- Publication Date
- 2025-01-24
- Estimated Expiration
- 2034-04-16
AI Technical Summary
When the existing GaN-based HEMT devices improve frequency characteristics, the short gate-long structure leads to a decrease in gate control capability, resulting in a short channel effect, and the increase in the inter-electrode coupling capacitance of the structure affects the frequency characteristics.
A GaN-based HEMT device with a T-shaped gate structure is used. A short gate length is formed through a small base foot, and a large cross-sectional area is used. The gate structure is designed to minimize the gate resistance and interelectrode capacitance Cgd.
The frequency characteristics of the device are improved, the cutoff frequency and maximum oscillation frequency are increased, the current gain is improved, and the power characteristics are improved, and good power characteristics are maintained at higher frequencies.
Smart Images
Figure CN222395995U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductor power device manufacturing, in particular to a GaN-based HEMT device with a T-type gate structure. Background Art
[0002] GaN-based high electron mobility transistors (HEMTs) have broad application prospects in the field of high frequency and high power due to their good operating frequency, output power density, electron mobility and other characteristics. As a third-generation semiconductor material, gallium nitride (GaN) has excellent physical properties such as wide bandgap, high electron mobility, high electron saturation rate, high breakdown electric field, high thermal conductivity, good chemical stability and strong radiation resistance, which makes up for the shortcomings of the previous two generations of Si and GaAs semiconductor devices in terms of high power and high frequency.
[0003] In order to improve the frequency characteristics of the device, it is necessary to increase the effective electron speed and transconductance characteristics as much as possible, while reducing the parasitic effects of the device. This requires control from the process and structure. In order to obtain good frequency characteristics, high-frequency devices are generally small-sized and short-gate length devices to reduce the transportation time of electrons in the channel. However, short-gate length devices will reduce the gate control ability of the device and cause short channel effects, which are specifically manifested as threshold voltage drift, increased leakage current, increased subthreshold swing, etc.; in addition, a multi-finger structure can be used to minimize the gate resistance, but as the gate index increases, the coupling capacitance between electrodes will also increase, and the impact on the frequency characteristics will be weakened. Both of the above methods have defects. For this reason, we propose a GaN-based HEMT device with a T-type gate structure. Utility Model Content
[0004] The utility model aims to solve one of the technical problems existing in the prior art or related technology.
[0005] To this end, the technical solution adopted in this utility model is:
[0006] A GaN-based HEMT device with a T-type gate structure comprises a substrate layer, a buffer layer is connected above the substrate layer, an AlGaN barrier layer is connected above the buffer layer, a GaN cap layer is connected above the AlGaN barrier layer, a source electrode and a drain electrode are connected to the left and right sides of the GaN cap layer, a gate electrode is connected to the top of the GaN cap layer, and a Schottky contact is formed between the gate electrode and the GaN cap layer;
[0007] The top of the GaN cap layer is connected to a SiN passivation layer, and the SiN passivation layer is arranged on both sides of the gate and has a distance from the gate;
[0008] The grid comprises a grid cap, a grid foot is fixedly connected to the center of the grid cap, and the grid cap and the grid foot are perpendicular to each other.
[0009] Based on the above technical solution, its use principle and the technical effects produced are as follows:
[0010] By setting the gate structure, a short gate length is formed by a small base foot, and a large cross-sectional area is used to minimize the gate resistance and inter-electrode capacitance C gd , thereby improving the frequency characteristics of the device.
[0011] In a preferred example, the utility model can be further configured as follows: the substrate layer material is one of SiC, Si, and sapphire, and the substrate layer thickness is set to 20-100 μm.
[0012] In a preferred example, the utility model can be further configured as follows: the material of the buffer layer is any one or a combination of GaN, AlGaN, InAlGaN and InGaN, and the thickness of the buffer layer is set to 0.8-2 μm.
[0013] In a preferred example, the utility model can be further configured as follows: the Al component value range of the AlGaN barrier layer is 0.15-0.3, and the thickness value range is 10-30 nm.
[0014] In a preferred example, the present invention can be further configured as follows: the thickness of the GaN cap layer is set to 3 nm.
[0015] In a preferred example, the present invention can be further configured as follows: the thickness of the SiN passivation layer is set to 50 nm.
[0016] In a preferred example, the present invention can be further configured as follows: the distance L from the gate to the source sg =1μm, the distance from gate to drain is L gd =3μm.
[0017] In a preferred example, the utility model can be further configured as follows: the gate length Lg=0.2 μm, the gate cap length is 0.4 μm, the gate cap thickness is 0.15 μm, the gate cap width is 1 mm, and the gate foot height is 0.1 μm.
[0018] In a preferred example, the present invention can be further configured as follows: the source and the drain are both ohmic contacts.
[0019] The nouns, conjunctions or adjectives involved in the above technical solution are explained as follows:
[0020] Fixed connection refers to a connection in which parts or components are fixed without any relative movement. There are two types of connection: detachable and non-detachable.
[0021] (1) A removable connection is a connection that uses screws, splines, wedge pins, etc. to hold parts together. This type of connection can be disassembled for maintenance without damaging the parts. However, the specifications of the connectors used must be correct (such as the length of the bolts, keys, and wedge pins) and they must be properly tightened.
[0022] (2) Non-detachable connections mainly refer to welding, riveting and tenoning. Since they need to be disassembled by forging, sawing or oxygen cutting for maintenance or replacement, spare parts generally cannot be reused. At the same time, when making connections, attention should be paid to process quality, technical inspection and remedial measures (such as calibration, polishing, etc.);
[0023] An active connection is a connection in which parts or components are fixed so that they can move relative to each other.
[0024] The above technical solution of the utility model has the following beneficial technical effects:
[0025] 1. The gate structure described in the utility model realizes low gate resistance and low gate-drain capacitance while reducing the gate length, thereby ensuring the strength of the gate metal.
[0026] 2. The frequency characteristics are mainly affected by the short channel effect and parasitic elements. The gate structure described in the utility model can increase the cutoff frequency and maximum oscillation frequency of the device, thereby improving the current gain, and then improving the power characteristics, and better power characteristics can be obtained at higher frequencies. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a schematic diagram of the layer structure of a GaN-based HEMT device with a T-type gate structure proposed by the utility model;
[0028] Figure 2 It is a schematic diagram of the layer structure of a traditional GaN-based HEMT device;
[0029] Figure 3 This is a frequency characteristic simulation diagram of two GaN-based HEMT devices with a T-type gate structure and a traditional structure proposed by the utility model;
[0030] Figure 4 This is a simulation diagram of the large signal power characteristics of the GaN-based HEMT device with a T-type gate structure proposed by the utility model at a working frequency of 1 GHz;
[0031] Figure 5 This is a simulation diagram of large signal power characteristics of a GaN-based HEMT device with a T-type gate structure at different operating frequencies proposed by the utility model.
[0032] Reference numerals
[0033] 1. Substrate layer; 2. Buffer layer; 3. AlGaN barrier layer; 4. GaN cap layer; 5. Source; 6. Drain; 7. Gate; 71. Gate cap; 72. Gate foot; 8. SiN passivation layer. DETAILED DESCRIPTION
[0034] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure. It should be noted that the embodiments of the present utility model and the features in the embodiments can be combined with each other without conflict.
[0035] According to the concept of this application, Figure 1-5 An embodiment of a GaN-based HEMT device with a T-type gate structure for improving frequency characteristics is described below. Specifically, the GaN-based HEMT device with a T-type gate structure is constructed as an integrated structure, which has components such as an AlGaN barrier layer 3, a substrate layer 1, a buffer layer 2, and a gate 7. By setting the gate 7 structure, a short gate length is formed by a small base foot, and a large cross-sectional area is used to minimize the gate 7 resistance and inter-electrode capacitance C gd , thereby improving the frequency characteristics of the device.
[0036] Combination Figure 1 As shown, the utility model provides a GaN-based HEMT device with a T-type gate structure, comprising a substrate layer 1, a buffer layer 2 connected to the substrate layer 1, an AlGaN barrier layer 3 connected to the buffer layer 2, a GaN cap layer 4 connected to the AlGaN barrier layer 3, a source 5 and a drain 6 connected to the left and right sides of the GaN cap layer 4, a gate 7 connected to the top of the GaN cap layer 4, and a Schottky contact is formed between the gate 7 and the GaN cap layer 4;
[0037] The top of the GaN cap layer 4 is connected with a SiN passivation layer 8, which is arranged on both sides of the gate 7 and has a distance from the gate 7;
[0038] The gate 7 includes a gate cap 71 . A gate foot 72 is fixedly connected to the center of the gate cap 71 , and the gate cap 71 and the gate foot 72 are perpendicular to each other.
[0039] The substrate layer 1 is mainly used for heat dissipation. In some embodiments, the material of the substrate layer 1 can be set to SiC, Si, or sapphire. For the technical solution of this embodiment, the material of the substrate layer 1 is SiC, and the thickness of the SiC substrate layer 1 can be set to 20-100μm. For the technical solution of this embodiment, the thickness is specifically set to 20μm.
[0040] The buffer layer 2 is mainly used to provide a flat surface. In some embodiments, the material of the buffer layer 2 is any one or a combination of GaN, AlGaN, InAlGaN and InGaN. For the technical solution of this embodiment, the material of the buffer layer 2 is set to GaN, and the thickness of the buffer layer 2 can be set to 0.8 to 2 μm. For the technical solution of this embodiment, the thickness is specifically set to 2 μm.
[0041] In actual use, the AlGaN barrier layer 3 can also be replaced and set to any one of AlInN, AlScN, AlN, AlInGaN, AlInScN or AlGaScN. The Al component value range of the AlGaN barrier layer 3 is 0.15-0.3. For the technical solution of this embodiment, the Al component of the AlGaN barrier layer 3 is fixed to 0.25; the thickness value range of the AlGaN barrier layer 3 is 10-30nm. For the technical solution of this embodiment, its thickness is specifically set to 20nm.
[0042] Furthermore, the thickness of the GaN cap layer 4 is set to 3 nm, and the thickness of the SiN passivation layer 8 is set to 50 nm. The SiN passivation layer 8 can suppress the current collapse effect of the GaN-based HEMT device.
[0043] The source 5 and the drain 6 are both ohmic contacts. In order to improve the breakdown characteristics, the distance between the gate and the drain (Lgd) is often greater than the distance between the gate and the source (Lgs). For the technical solution of this embodiment, the distance L from the gate 7 to the source 5 is sg =1μm, the distance L from the gate 7 to the drain 6 gd =3μm, gate 7 length L g =0.2μm, the length of the gate cap 71 is 0.4μm, the thickness of the gate cap 71 is 0.15μm, the width of the gate cap 71 is 1mm, and the height of the gate foot 72 is 0.1μm.
[0044] The specific embodiments are as follows:
[0045] In order to verify the advantages of the GaN-based HEMT device with a T-type gate structure proposed in this application over the traditional GaN-based HEMT device, the technical solution of this embodiment simulates and compares the relevant performance indicators of the two. The structure of the GaN-based HEMT device with a traditional structure is shown in FIG. Figure 2 As shown, the gate 7 length Lg = 0.2 μm, except for the gate 7 structure, other parameters are the same as Figure 1 same.
[0046] See also Figure 3, the frequency characteristics of the traditional structure and T-type gate structure GaN-based HEMT devices were simulated and compared using Sentaurus TCAD 2D device simulation tool, and V d =20V is the DC operating point, the gate voltage is scanned from -2V to 2V, the frequency is 0.1GHz to 1THz, and the frequency characteristics of the optimized tilted field plate structure device are simulated. The cutoff frequency f of the device T The maximum oscillation frequency is 90.76 GHz. max It is 203.13GHz. When the gain is 10dB, the operating frequency of the device is 28.61GHz. Its cutoff frequency is increased by 20.42GHz, 29.03% compared with the original structure. The maximum oscillation frequency is increased by 35.63GHz. When the gain is 10dB, the operating frequency increases by 7.22GHz, 33.75%.
[0047] See also Figure 4 , which shows the simulation diagram of the large signal power characteristics of the T-gate GaN-based HEMT device at 1GHz; it can be seen that the output and efficiency increase with the increase of input, while the gain decreases with the increase of input; the P out It is 4.16W / mm, Gain is 9.70dB, and PAE is 21.23%.
[0048] See also Figure 4 , which shows the simulation results of large signal power characteristics of T-gate GaN-based HEMT devices at different operating frequencies; as the operating frequency increases, P out , gain and efficiency all increase first and then decrease. The data change is small within the operating frequency range of 1-25GHz. It can be seen from the figure that when the operating frequency is 25GHz, the P out The gain is maximum and the efficiency of the device is maximum when the operating frequency is 10GHz.
[0049] The following is a further description of a GaN-based HEMT device with a T-type gate structure provided by the present invention in conjunction with the accompanying drawings and implementation modes.
[0050] A GaN-based HEMT device with a T-type gate structure comprises a substrate layer 1, a buffer layer 2 is connected above the substrate layer 1, an AlGaN barrier layer 3 is connected above the buffer layer 2, a GaN cap layer 4 is connected above the AlGaN barrier layer 3, a source electrode 5 and a drain electrode 6 are connected to the left and right sides of the GaN cap layer 4, a gate electrode 7 is connected to the top of the GaN cap layer 4, and a Schottky contact is formed between the gate electrode 7 and the GaN cap layer 4;
[0051] The top of the GaN cap layer 4 is connected with a SiN passivation layer 8, which is arranged on both sides of the gate 7 and has a distance from the gate 7;
[0052] The gate 7 includes a gate cap 71 . A gate foot 72 is fixedly connected to the center of the gate cap 71 , and the gate cap 71 and the gate foot 72 are perpendicular to each other.
[0053] In summary, the utility model provides a gate 7 structure, a small base foot to form a short gate length, and a large cross-sectional area to minimize the gate 7 resistance and inter-electrode capacitance C gd , thereby improving the frequency characteristics of the device.
[0054] In the present utility model, the term "plurality" refers to two or more than two, unless otherwise clearly defined. The term "and / or" used in this article includes any and all combinations of one or more related listed items. The terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to the specific circumstances.
[0055] It should be noted that when an element is referred to as being "assembled on", "installed on", "fixed on" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.
[0056] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0057] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.
Claims
1. A GaN-based HEMT device with a T-type gate structure, comprising a substrate layer, characterized in that: A buffer layer is connected above the substrate layer, an AlGaN barrier layer is connected above the buffer layer, a GaN cap layer is connected above the AlGaN barrier layer, a source electrode and a drain electrode are connected to the left and right sides of the GaN cap layer, a gate electrode is connected to the top of the GaN cap layer, and a Schottky contact is formed between the gate electrode and the GaN cap layer; The top of the GaN cap layer is connected to a SiN passivation layer, and the SiN passivation layer is arranged on both sides of the gate and has a distance from the gate; The grid comprises a grid cap, a grid foot is fixedly connected to the center of the grid cap, and the grid cap and the grid foot are perpendicular to each other.
2. A GaN-based HEMT device with a T-type gate structure according to claim 1, characterized in that: The substrate layer is made of one of SiC, Si and sapphire, and the thickness of the substrate layer is set to 20-100 μm.
3. The GaN-based HEMT device with a T-type gate structure according to claim 2, characterized in that: The buffer layer is made of any one of GaN, AlGaN, InAlGaN or InGaN, and the thickness of the buffer layer is set to 0.8-2 μm.
4. The GaN-based HEMT device with a T-type gate structure according to claim 3, characterized in that: The thickness of the GaN cap layer is set to 3 nm.
5. The GaN-based HEMT device with a T-type gate structure according to claim 4, characterized in that: The thickness of the SiN passivation layer is set to 50 nm.
6. The GaN-based HEMT device with a T-type gate structure according to claim 1, characterized in that: The gate to source distance L sg =1μm, the distance from gate to drain is L gd =3μm.
7. The GaN-based HEMT device with a T-type gate structure according to claim 6, characterized in that: The gate length Lg=0.2 μm, the gate cap length is 0.4 μm, the gate cap thickness is 0.15 μm, the gate cap width is 1 mm, and the gate foot height is 0.1 μm.
8. The GaN-based HEMT device with a T-type gate structure according to claim 7, characterized in that: The source and the drain are both ohmic contacts.