Preparation method of GaN-based power device and GaN-based power device
During the preparation of GaN-based power devices, the gate layer is passivated or its activation capacity changes are controlled, and the leakage current problem of Schottky contact gate is solved, which significantly reduces the gate leakage current and improves device performance.
Patent Information
- Application Number
- CN202510523675.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-22
AI Technical Summary
The gate leakage current of the Schottky contact gate of the conventional GaN-based power device is relatively high, and it is difficult to further reduce.
When forming the gate electrode or passivation layer, the gate layer is passivated, or the activation amount of the gate layer is controlled to gradually decrease from the bottom to the top, and the doping concentration and activation temperature are adjusted by introducing binding elements or multiple growths to reduce the activation amount of the gate layer.
Effectively reduce gate leakage current by 1-2 orders of magnitude and improve device performance.
Smart Images
Figure CN120358766A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular, to a method for manufacturing a GaN-based power device and a GaN-based power device. Background Art
[0002] The gate types of gallium nitride (GaN)-based power devices include ohmic gates and Schottky contact gates. Compared with ohmic gate GaN-based power devices, the Schottky contact gate GaN-based power devices have significantly reduced gate leakage current. However, compared with silicon power metal-oxide-semiconductor field effect transistors (Si Power MOSFETs), the leakage current (IGSS) of the Schottky contact gate GaN-based power devices is still very significant (more than two orders of magnitude). Therefore, how to further reduce the gate leakage current of the Schottky contact gate of GaN-based power devices remains a matter of great concern in this field. Summary of the Invention
[0003] The purpose of the present invention is to provide a method for manufacturing a GaN-based power device and a GaN-based power device to reduce the leakage current of the Schottky contact gate GaN-based power device.
[0004] To solve the above problems, the present invention provides a method for manufacturing a GaN-based power device, including:
[0005] Providing a substrate, the substrate includes a substrate layer, a channel layer, and a barrier layer stacked in sequence from bottom to top, and source and drain electrodes are respectively formed on the channel layers on both sides of the barrier layer;
[0006] Forming a highly doped gate layer on the barrier layer and performing a high-temperature activation treatment on the gate layer; and,
[0007] Forming the gate and forming a passivation layer, the gate covers the gate layer, and the passivation layer covers the gate and the barrier layer;
[0008] Wherein, when forming the gate or the passivation layer, the gate layer is passivated to reduce the activation amount of the gate layer; or, when forming the gate layer, the activation amount of the gate layer is controlled to gradually decrease from bottom to top.
[0009] Optionally, in the method for manufacturing a GaN-based power device, the method for passivating the gate layer includes: when forming the passivation layer, introducing a binding element so that the binding element binds to the activated doping ions to reduce the activation amount of the gate layer.
[0010] Optionally, in the method for preparing the GaN-based power device, the doping ions of the gate layer include magnesium, and the binding element includes hydrogen or oxygen.
[0011] Optionally, in the method for preparing the GaN-based power device, the method for controlling the activation amount of the gate layer to gradually decrease from the bottom to the top includes: the gate layer is formed by multiple growths, and the doping concentration during multiple growths changes gradually decreasing.
[0012] Optionally, in the method for preparing the GaN-based power device, the doping concentration during multiple growths is selected between 1E17 and 1E19.
[0013] Optionally, in the method for preparing the GaN-based power device, the gate layer is formed by two growths. The doping concentration C1 during the first growth satisfies: 1E18 < C1 ≤ 1E19, and the doping concentration C2 during the second growth satisfies: 1E17 ≤ C2 ≤ 1E18.
[0014] Optionally, in the method for preparing the GaN-based power device, the method for controlling the activation amount of the gate layer to gradually decrease from the bottom to the top includes: the gate layer is formed by multiple growths, and the activation temperature during multiple growths changes gradually decreasing.
[0015] Optionally, in the method for preparing the GaN-based power device, the activation temperature during multiple growths is selected between 500 and 900 °C.
[0016] Optionally, in the method for preparing the GaN-based power device, the gate layer is formed by two growths. The activation temperature T1 during the first growth satisfies: 700 °C < T1 ≤ 900 °C, and the activation temperature T2 during the second growth satisfies: 500 °C ≤ T1 ≤ 700 °C.
[0017] The present invention also provides a GaN-based power device, which is prepared by using the preparation method described in any one of the preceding items.
[0018] In summary, in the method for preparing the GaN-based power device provided by the present invention, during the process of forming the GaN-based power device, when forming the gate or the passivation layer, the gate layer is passivated to reduce the activation amount of the gate layer; or, when forming the gate layer, the activation amount of the gate layer is controlled to gradually decrease from the bottom to the top, so as to reduce the hole concentration of the doping ions in the gate layer, thereby achieving the purpose of reducing the gate leakage current. Description of the Drawings
[0019] Figure 1 It is a flowchart of the method for preparing the GaN-based power device provided in the first embodiment of the present invention;
[0020] Figure 2 Flow chart of the preparation method of the GaN-based power device provided for Embodiment 2 and Embodiment 3 of the present invention;
[0021] Figure 3 Schematic structural diagram of the GaN-based power device provided for the embodiment of the present invention;
[0022] Among them, the descriptions of each reference numeral are as follows:
[0023] 10 - Substrate layer; 20 - Channel layer; 30 - Barrier layer; 40 - Source electrode; 50 - Drain electrode; 60 - Gate layer; 70 - Gate; 80 - Passivation layer; 90 - Field plate layer. Specific embodiments
[0024] The following further elaborates on the preparation method of the GaN-based power device and the GaN-based power device provided by the present invention in conjunction with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention. In addition, the structures shown in the accompanying drawings are often part of the actual structures. In particular, the accompanying drawings need to show different emphases and sometimes use different scales. It should be recognized that relative terms such as "above", "below", "top", "bottom", etc. shown in the accompanying drawings can be used to describe the relationships between various elements with respect to each other. These relative terms are intended to cover different orientations of the elements other than the orientations depicted in the accompanying drawings. For example, if the device is inverted relative to the view in the accompanying drawings, an element described as "above" another element will now be below that element. It should also be understood that unless otherwise specifically stated or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, rather than to represent the logical relationships or sequential relationships between the various components, elements, steps, etc.
[0025]
Embodiment 1
[0026] Please refer to Figure 1 and in conjunction with Figure 3 , this embodiment provides a preparation method of a GaN-based power device, including the following steps:
[0027] S11, providing a substrate, the substrate includes a substrate layer 10, a channel layer 20, and a barrier layer 30 stacked in sequence from bottom to top, and a source electrode 40 and a drain electrode 50 are respectively formed on the channel layer 20 on both sides of the barrier layer 30;
[0028] S12, forming a highly doped gate layer 60 on the barrier layer 30, and performing a high-temperature activation treatment on the gate layer 60;
[0029] S13. Form the gate 70 and form the passivation layer 80. The gate 70 covers the gate layer 60, and the passivation layer 80 covers the gate 70 and the barrier layer 30. When forming the gate 70 or the passivation layer 80, passivate the gate layer 60 to reduce the activation amount of the gate layer 60.
[0030] The preparation method provided in this embodiment will be further described below.
[0031] First, perform step S11 to provide a substrate, which includes a substrate layer 10, a channel layer 20, and a barrier layer 30 formed in sequence from bottom to top and stacked.
[0032] The material of the substrate layer 10 can be silicon (Si), silicon carbide (SiC), sapphire (Al2O3), etc. The substrate layer 10 is used to provide mechanical support and serve as a substrate for epitaxial growth.
[0033] The material of the channel layer 20 can be gallium nitride (GaN). The channel layer 20 is the main region for forming a two-dimensional electron gas (2DEG).
[0034] The material of the barrier layer 30 can be aluminum gallium nitride (AlGaN), which forms a heterojunction with the channel layer 20 (i.e., with the GaN layer), and induces a high-concentration two-dimensional electron gas at the interface through spontaneous polarization and piezoelectric polarization effects.
[0035] Preferably, a buffer layer (not shown) is further formed between the substrate layer 10 and the channel layer 20. The material of the buffer layer can be intrinsic gallium nitride (i-GaN). The buffer layer provides a high-quality crystal structure, isolates the substrate from the epitaxial layer, and reduces defects and leakage current.
[0036] The substrate further includes a source electrode 40 and a drain electrode 50 formed on both sides of the barrier layer 30 on the channel layer 20. The source electrode 40 and the drain electrode 50 are used for current input and output.
[0037] Secondly, perform step S12 to form a highly doped gate layer 60 on the barrier layer 30 and perform a high-temperature activation treatment on the gate layer 60.
[0038] The gate layer 60 can be doped with magnesium (Mg). The gate layer 60 realizes hole conduction through Mg doping. Specifically, by highly concentrating holes to deplete the two-dimensional electron gas (2DEG) of the underlying AlGaN / GaN heterojunction, an enhancement-mode (normally-off) operation mode is realized. Optionally, the Mg doping concentration can be 10 19 ~10 20 cm -3 , and the concentration after hole activation is about 10 17 ~10 18cm -3 。
[0039] Mg has a relatively high ionization energy in GaN, and the growth process may cause the Mg acceptors to be passivated. Through high-temperature activation treatment, the active Mg acceptors can be released, significantly increasing the hole concentration.
[0040] In addition, through high-temperature activation treatment, the interface quality between the gate layer 60 and the barrier layer 30 can be improved, reducing the interface state density, thereby enhancing the gate 70 control ability (such as the threshold voltage stability).
[0041] The temperature for high-temperature activation treatment of the gate layer 60 can be between 700 and 900 °C, and further, it can be between 800 and 850 °C to balance the activation efficiency and the thermal stability of the material. If the temperature is too low, the hole concentration will be insufficient. If the temperature is too high, it may cause the decomposition of the GaN surface (nitrogen escape) or the outward diffusion of Mg.
[0042] Next, step S13 is performed to form the gate 70 and form the passivation layer 80. The gate 70 covers the gate layer 60, and the passivation layer 80 covers the gate 70 and the barrier layer 30. The gate 70 is in layer contact with the gate layer 60 to form a Schottky contact for controlling the on and off of the 2DEG.
[0043] The material of the passivation layer 80 can be silicon nitride (Si3N4), silicon dioxide (SiO2), aluminum oxide (Al2O3), aluminum nitride (AlN), etc. It can be prepared by chemical vapor deposition (CVD) or atomic layer deposition (ALD) processes.
[0044] In addition to covering the gate 70 and the barrier layer 30, as Figure 3 shown, the passivation layer 80 can also extend to the surfaces of the source electrode 40 and the drain electrode 50.
[0045] There may be unsaturated chemical bonds or defect states on the surface of the GaN-based power device. These surface states will capture electrons, resulting in current collapse and an increase in the dynamic on-resistance. By forming the passivation layer 80, the surface leakage current path can be blocked, reducing the static power consumption of the device.
[0046] In addition, after forming the passivation layer 80, the manufacturing method provided in this embodiment may further include forming a field plate layer 90. The field plate layer 90 is connected to the source electrode 40 and extends to cover the area of the passivation layer 80 between the gate 70 and the drain electrode 50. The field plate layer 90 can redistribute the electric field, improving the high electric field concentration near the edge of the gate 70, thereby significantly increasing the breakdown voltage of the device.
[0047] By performing high doping and high-temperature activation treatment on the gate layer 60 through step S12, the gate layer 60 has a high concentration of holes, which can deplete the two-dimensional electron gas of the underlying AlGaN / GaN heterojunction, realizing an enhancement-mode (normally-off) operating mode. However, it also brings the problem of significant leakage current in the device gate 70.
[0048] In view of this, in this embodiment, in step S13, when forming the gate 70 or the passivation layer 80, the gate layer 60 is passivated to reduce the activation amount of the gate layer 60.
[0049] Specifically, when forming the gate 70 or the passivation layer 80, a binding element can be introduced so that the binding element binds to the activated doping ions to reduce the activation amount of the gate layer 60. The binding element may specifically include hydrogen (H), oxygen (O), etc. For example, by introducing H, H combines with Mg to form an Mg-H complex, so that the Mg acceptor is passivated, thereby achieving the purpose of reducing the activation amount of the gate layer 60.
[0050]
Embodiment 2
[0051] Please refer to Figure 2 and combine with Figure 3 , this embodiment provides a method for manufacturing a GaN-based power device, including the following steps:
[0052] S21, providing a substrate, the substrate includes a substrate layer 10, a channel layer 20, and a barrier layer 30 stacked in sequence from bottom to top, and source electrodes 40 and drain electrodes 50 are respectively formed on the channel layer 20 on both sides of the barrier layer 30;
[0053] S22, forming a highly doped gate layer 60 on the barrier layer 30, performing high-temperature activation treatment on the gate layer 60, and when forming the gate layer 60, controlling the activation amount of the gate layer 60 to gradually decrease from bottom to top;
[0054] S23, forming a gate 70 and forming a passivation layer 80, the gate 70 covers the gate layer 60, and the passivation layer 80 covers the gate 70 and the barrier layer 30.
[0055] Comparing Embodiment 1 and Embodiment 2, it can be seen that the film layer structure of the device formed in this embodiment and the formation sequence of each film layer are the same as those in Example 1. Therefore, for the materials used in each film layer, the functions performed, and the corresponding formation methods, please refer to Embodiment 1, which will not be elaborated in this embodiment. Different from Embodiment 1, in this embodiment, by controlling the activation amount of the gate layer 60 in the step of forming the gate layer 60, the purpose of reducing the leakage current of the gate 70 is achieved.
[0056] Specifically, in this embodiment, the method for controlling the activation amount of the gate layer 60 to gradually decrease from bottom to top includes: when forming the gate layer 60, the gate layer 60 is formed by multiple growths, and the doping concentration during multiple growths changes gradually. The doping concentration during multiple growths is selected between 1E17 and 1E19.
[0057] As an example, the gate layer 60 is formed by two growths. The doping concentration C1 during the first growth satisfies: 1E18 < C1 ≤ 1E19, and the doping concentration C2 during the second growth satisfies: 1E17 ≤ C2 ≤ 1E18. Thus, at the same activation temperature, the hole concentration at the top layer of the gate layer 60 is less than the hole concentration at the bottom layer of the gate layer 60. That is, the bottom layer of the gate layer 60 formed by the second growth has a high hole concentration, and the two-dimensional electron gas of the underlying AlGaN / GaN heterojunction is depleted by the high-concentration holes to achieve an enhancement-mode (normally-off) operation mode. The top layer of the gate layer 60 formed by the first growth has a low hole concentration to suppress the leakage current of the gate 70.
[0058]
Embodiment III
[0059] Different from Embodiment II, in this embodiment, the method for controlling the activation amount of the gate layer 60 to gradually decrease from bottom to top includes: when forming the gate layer 60, the gate layer 60 is formed by multiple growths, and the activation temperature during multiple growths changes gradually. The activation temperature during multiple growths is selected between 500 and 900 °C.
[0060] As an example, the gate layer 60 is formed by two growths. The activation temperature T1 during the first growth satisfies: 700 °C < T1 ≤ 900 °C, and the activation temperature T2 during the second growth satisfies: 500 °C ≤ T1 ≤ 700 °C. Thus, at the same doping concentration, the hole concentration at the top layer of the gate layer 60 is less than the hole concentration at the bottom layer of the gate layer 60. That is, the bottom layer of the gate layer 60 formed by the second growth has a high hole concentration, and the two-dimensional electron gas (2DEG) of the underlying AlGaN / GaN heterojunction is depleted by the high-concentration holes to achieve an enhancement-mode (normally-off) operation mode. The top layer of the gate layer 60 formed by the first growth has a low hole concentration to suppress the leakage current of the gate 70.
[0061] In some other embodiments, Embodiment II and Embodiment III can also be combined, that is, by hierarchically controlling the doping concentration and / or activation temperature during the growth of the gate layer 60, so that the hole concentration at the top layer of the gate layer 60 is less than that at the bottom layer, while ensuring the normally-off operation function of the device, improving the Schottky barrier quality, and reducing the leakage current of the gate 70.
[0062] In some other embodiments, Embodiment 1 may also be combined with one or both of Embodiment 2 and Embodiment 3, which will not be elaborated herein.
[0063] In addition, an embodiment of the present invention further provides a GaN-based power device, which is prepared by using the preparation method described in any one of Embodiments 1 to 3.
[0064] Under the same conditions, compared with a conventional Schottky contact gate GaN-based power device, the gate leakage of the GaN-based power device prepared by using the preparation method provided in this embodiment is reduced by 1 to 2 orders of magnitude.
[0065] In summary, in the process of forming a GaN-based power device, the preparation method of the GaN-based power device provided by the embodiment of the present invention passivates the gate layer when forming the gate or the passivation layer to reduce the activation amount of the gate layer; or, when forming the gate layer, controls the activation amount of the gate layer to gradually decrease from the bottom to the top, so as to reduce the hole concentration of the doped ions in the gate layer, thereby achieving the purpose of reducing the gate leakage current.
[0066] It should be noted that the various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. In addition, the different parts among the various embodiments can also be combined and used. The present invention does not limit this.
[0067] In addition, the above description is only a description of the preferred embodiments of the present invention and is not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or it can be modified into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A preparation method of a GaN-based power device, characterized in that, Including: Providing a substrate, the substrate includes a substrate layer, a channel layer, and a barrier layer stacked in sequence from bottom to top, and source and drain electrodes are respectively formed on the channel layers on both sides of the barrier layer; Forming a highly doped gate layer on the barrier layer, and performing a high-temperature activation treatment on the gate layer; And, Forming a gate and forming a passivation layer, the gate covers the gate layer, and the passivation layer covers the gate and the barrier layer; Wherein, when forming the gate or the passivation layer, passivating the gate layer to reduce the activation amount of the gate layer; or, when forming the gate layer, controlling the activation amount of the gate layer to gradually decrease from bottom to top.
2. The manufacturing method of the GaN-based power device according to claim 1, wherein The method of passivating the gate layer includes: when forming the gate or the passivation layer, introducing a binding element so that the binding element combines with the activated doping ions to reduce the activation amount of the gate layer.
3. The manufacturing method of the GaN-based power device according to claim 2, characterized in that, The doping ions of the gate layer include magnesium, and the binding element includes hydrogen or oxygen.
4. The manufacturing method of the GaN-based power device according to claim 1, characterized in that, The method of controlling the activation amount of the gate layer to gradually decrease from bottom to top includes: the gate layer is formed by multiple growths, and the doping concentration during multiple growths changes gradually.
5. The manufacturing method of the GaN-based power device according to claim 4, characterized in that, The doping concentration during multiple growths is selected between 1E17 and 1E19.
6. The manufacturing method of the GaN-based power device according to claim 5, characterized in that, The gate layer is formed by two growths. The doping concentration C1 during the first growth satisfies: 1E18 < C1 ≤ 1E19, and the doping concentration C2 during the second growth satisfies: 1E17 ≤ C2 ≤ 1E18.
7. The manufacturing method of the GaN-based power device according to claim 1, characterized in that, The method of controlling the activation amount of the gate layer to gradually decrease from bottom to top includes: the gate layer is formed by multiple growths, and the activation temperature during multiple growths changes gradually.
8. The manufacturing method of the GaN-based power device according to claim 7, characterized in that, The activation temperature during multiple growths is selected between 500 and 900 °C.
9. The manufacturing method of the GaN-based power device according to claim 8, characterized in that The gate layer is formed by two growths. The activation temperature T1 during the first growth satisfies: 700 °C < T1 ≤ 900 °C, and the activation temperature T2 during the second growth satisfies: 500 °C ≤ T1 ≤ 700 °C.
10. A GaN-based power device, characterized in that, The GaN-based power device is prepared by the preparation method according to any one of claims 1 to 9.