Surface treatment method of gallium nitride-based material and device preparation method

Abstract

The application discloses a surface treatment method of gallium nitride-based material and a preparation method of a device. The surface treatment method of the gallium nitride-based material comprises the following steps: growing an oxide protective film on a surface of a structure layer of the gallium nitride-based material to obtain a first intermediate structure layer; performing hydrogen ion gas treatment on the surface of the first intermediate structure layer to obtain a second intermediate structure layer; and etching and removing the oxide protective film in the second intermediate structure layer. The method can effectively reduce the surface state of the structure layer of the gallium nitride-based material and improve the electrical performance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a surface treatment method for gallium nitride-based materials and a method for fabricating gallium nitride-based material devices. Background Technology

[0002] Gallium nitride (GaN) is a representative of third-generation wide-bandgap semiconductor materials and has attracted widespread attention from researchers worldwide. GaN and its related nitrides are key materials for high-voltage and high-frequency devices due to their wide bandgap, high electron saturation velocity, and high breakdown field strength. Compared to Si, GaN has a bandgap more than three times wider, a breakdown field strength ten times greater, and an electron saturation velocity reaching 2.7 × 10⁻⁶. 7 cm / s; therefore, compared with Si-based devices, GaN-based HEMT devices have superior performance such as lower on-resistance, smaller parasitic capacitance, and higher breakdown voltage, which can meet the application requirements of next-generation systems for semiconductor devices with higher power, smaller size, and higher frequency.

[0003] However, GaN-based devices are susceptible to surface states, leading to performance degradation. This phenomenon is particularly pronounced in GaN-based high electron mobility transistors, where surface states trap and release electrons in the barrier layer, affecting the two-dimensional electron gas and causing problems such as high gate leakage current, gate hysteresis, and current collapse. In gallium nitride diodes, surface states also increase reverse leakage current. Therefore, surface states severely impact the output characteristics and reliability of GaN-based power electronic devices, making the effective reduction of surface states a pressing issue. Summary of the Invention

[0004] Therefore, in order to solve the above-mentioned problems in the prior art, the present invention provides a surface treatment method for gallium nitride-based materials and a method for fabricating gallium nitride-based material devices.

[0005] Therefore, according to a first aspect, the present invention provides a surface treatment method for gallium nitride-based materials, comprising the following steps:

[0006] An oxide protective film is grown on the surface of the structural layer of a gallium nitride-based material to obtain the first intermediate structural layer;

[0007] The surface of the first intermediate structural layer is treated with hydrogen ion gas to obtain the second intermediate structural layer;

[0008] The oxide protective film in the second intermediate structural layer is removed by etching.

[0009] Further, the step of treating the surface of the first intermediate structural layer with hydrogen ion gas to obtain the second intermediate structural layer specifically includes the following steps:

[0010] The first intermediate structure layer is placed in a microwave plasma chemical vapor deposition apparatus for hydrogen ion gas treatment. After a first preset time, the second intermediate structure layer is obtained. The hydrogen flow rate of the microwave plasma chemical vapor deposition apparatus is between 50 Sccm and 200 Sccm, and the first preset time is between 10 min and 15 min.

[0011] Furthermore, the oxide protective film is an aluminum oxide protective film.

[0012] According to a second aspect, the present invention also provides a method for fabricating a gallium nitride-based material device, comprising the following steps:

[0013] Obtain the substrate for preparation;

[0014] A plurality of gallium nitride-based conductive structure layers are sequentially grown on a substrate; at least one gallium nitride-based conductive structure layer is treated with the surface treatment method of gallium nitride-based material in the first aspect or any embodiment of the first aspect described above.

[0015] Conductive electrodes are grown on the top gallium nitride-based conductive structure layer.

[0016] Furthermore, the step of sequentially growing a plurality of gallium nitride-based conductive structure layers on the substrate specifically includes the following steps:

[0017] A gallium nitride-based channel layer and a gallium nitride-based barrier layer are sequentially grown on the substrate; the gallium nitride-based barrier layer is treated using the surface treatment method for gallium nitride-based materials described in the first aspect or any embodiment of the first aspect.

[0018] Furthermore, the step of sequentially growing a plurality of gallium nitride-based conductive structure layers on the substrate specifically includes the following steps:

[0019] A gallium nitride-based channel layer, a gallium nitride-based barrier layer, and a gallium nitride-based gate dielectric layer are sequentially grown on a substrate; the gallium nitride-based gate dielectric layer is located in the gate region on the gallium nitride-based barrier layer; both the gallium nitride-based barrier layer and the gallium nitride-based gate dielectric layer are treated using the surface treatment method for gallium nitride-based material devices described in the first aspect or any embodiment of the first aspect.

[0020] Furthermore, the fabrication method of gallium nitride-based material devices also includes the following steps:

[0021] A passivation layer is grown on the exposed surface of a gallium nitride-based conductive structure layer; the passivation layer also coats the conductive electrode.

[0022] The technical solution provided by this invention has the following advantages:

[0023] 1. The surface treatment method for gallium nitride-based materials provided by the present invention first grows an oxide protective film on the surface of the structural layer of the gallium nitride-based material, and then treats the surface of the structural layer of the gallium nitride-based material with the oxide protective film with hydrogen ion gas. This can reduce the surface states of the structural layer of the gallium nitride-based material while preventing damage to the surface of the structural layer of the gallium nitride-based material by bombardment of high-energy hydrogen ions. Then, by removing the oxide protective film, the oxide protective film whose quality is affected by the bombardment can be prevented from becoming the surface of the overall structure, thus preventing the formation of new surface leakage channels. It can also prevent the formation of gallium-oxygen bonds between the bombarded oxide protective film and the surface of the structural layer of the gallium nitride-based material, thus preventing the reduction of device performance. Therefore, the surface states of the structural layer of the gallium nitride-based material can be effectively reduced.

[0024] 2. The method for fabricating gallium nitride-based material devices provided by the present invention can improve the electrical output characteristics of the prepared gallium nitride-based devices by performing surface treatment to reduce the surface states of the gallium nitride-based conductive structure layer.

[0025] 3. The method for fabricating gallium nitride-based material devices provided by the present invention, by performing a surface treatment to reduce the surface states of the gallium nitride-based conductive structure layer (i.e., the gallium nitride-based barrier layer in a depletion-type device, or the gallium nitride-based barrier layer and gallium nitride-based gate dielectric layer in an enhancement-type device, etc.) located on the surface of the device, and then growing a passivation layer on the device surface (i.e., the exposed surface of the gallium nitride-based conductive structure layer), can prevent the device surface from being exposed to air and causing the hydrogen ion treatment effect to degrade, thereby improving the electrical performance stability of the device prepared by this method. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a flowchart of the surface treatment method for gallium nitride-based materials provided in Embodiment 1 of the present invention;

[0028] Figure 2 The surface state diagram of the gallium nitride-based material structure layer under an oxide-free protective film after being bombarded by high-energy hydrogen ions;

[0029] Figure 3 This is a diagram showing the surface state of a gallium nitride-based material structure layer under an oxide protective film after being bombarded by high-energy hydrogen ions.

[0030] Figure 4 This is a flowchart of the method for fabricating gallium nitride-based material devices provided in Embodiment 2 of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] Example 1

[0034] This embodiment provides a surface treatment method for gallium nitride-based materials, such as... Figure 1 As shown, the method includes the following steps:

[0035] Step S10: An oxide protective film is grown on the surface of the gallium nitride-based material structural layer to obtain the first intermediate structural layer.

[0036] In this embodiment, the oxide protective film can be an alumina protective film, and it can be grown in an atomic layer deposition apparatus. Specifically, the thickness of the alumina protective film can be between 5 nm and 20 nm; for example, the thickness of the alumina protective film can be 10 nm.

[0037] Step S20: Treat the surface of the first intermediate structural layer with hydrogen ion gas to obtain the second intermediate structural layer.

[0038] Specifically, the first intermediate structure layer can be treated with hydrogen ion gas in a microwave plasma chemical vapor deposition (MPCVD) apparatus for a first preset time to obtain the second intermediate structure layer. Specifically, the hydrogen flow rate of the MPCVD is between 50 Sccm and 200 Sccm, and the first preset time is between 10 min and 15 min. Furthermore, the chamber pressure of the MPCVD can be set between 20 Torr and 50 Torr, and the radio frequency power between 1000 W and 2000 W. For example, the hydrogen flow rate of the MPCVD can be set to 100 Sccm, the chamber pressure to 40 Torr, the radio frequency power to 1500 W, and the first preset time to 15 min.

[0039] Step S30: Etch away the oxide protective film in the second intermediate structural layer.

[0040] Specifically, the oxide protective film in the second intermediate structural layer can be removed by etching with BOE solution for a second preset time. Specifically, the BOE solution is a mixture of 49% HF solution and 40% NH4F solution in a 1:6 ratio, and the second preset time is between 60 and 80 seconds. For example, the second preset time is 70 seconds.

[0041] In this embodiment, the oxide protective film is used to prevent high-energy hydrogen ion bombardment from damaging the surface of the gallium nitride-based material's structural layer. Specifically, under the same MPCVD parameters and the same first preset time, the surface condition of the gallium nitride-based material's structural layer after being bombarded by high-energy hydrogen ions without an oxide protective film is as follows: Figure 2 As shown, the surface condition of the gallium nitride-based material structural layer (i.e., the first intermediate structural layer) with an oxide protective film after being bombarded by high-energy hydrogen ions is as follows. Figure 3 As shown. It can be seen that, relative to Figure 2 The surface was bombarded into an amorphous shape. Figure 3 The surface inside is clearly protected.

[0042] In this embodiment, based on the provision of an oxide protective film, the working time of MPCVD (i.e., the first preset time), cavity pressure, radio frequency power, etc., can be controlled to allow hydrogen ions to reach the interface between the oxide protective film and the gallium nitride-based material structural layer according to a Gaussian distribution, and accumulate there, thereby achieving surface treatment of the gallium nitride-based material structural layer based on hydrogen ions.

[0043] The surface treatment method for gallium nitride-based materials in this embodiment first grows an oxide protective film on the surface of the gallium nitride-based material's structural layer, and then performs hydrogen ion treatment on the surface of the gallium nitride-based material's structural layer with the oxide protective film. This reduces the surface states of the gallium nitride-based material's structural layer while preventing damage to the surface of the structural layer caused by high-energy hydrogen ion bombardment. Then, by removing the oxide protective film, the surface state of the oxide protective film, which has been affected by the bombardment, is prevented from becoming part of the overall structure surface, thus preventing the formation of new surface leakage channels. It also prevents the formation of gallium-oxygen bonds between the bombarded oxide protective film and the surface of the gallium nitride-based material's structural layer, which would reduce device performance. Thus, the surface states of the gallium nitride-based material's structural layer are effectively reduced.

[0044] Example 2

[0045] This embodiment provides a method for fabricating gallium nitride-based material devices, such as... Figure 4 As shown, the method includes the following steps:

[0046] Step S100: Obtain the preparation substrate.

[0047] In this embodiment, the substrate can be prepared during the entire process of the method, or it can be a preform obtained directly. Specifically, the substrate can include a substrate, or it can include a substrate and a buffer layer disposed on the substrate. Specifically, the substrate material can be any of existing substrate materials such as Si, SiC, or sapphire, and the buffer layer material can be one or more of GaN, AlGaN, and AlN.

[0048] Step S200: A number of gallium nitride-based conductive structure layers are sequentially grown on the substrate.

[0049] In this embodiment, at least one gallium nitride-based conductive structure layer is treated using the surface treatment method for gallium nitride-based materials described in Embodiment 1 above.

[0050] In this embodiment, taking the gallium nitride-based material device prepared by this method as a depletion-type high electron mobility transistor as an example, the gallium nitride-based conductive structure layers can specifically include gallium nitride-based channel layers and gallium nitride-based barrier layers. Correspondingly, step S200 specifically includes the following steps:

[0051] Step S201: A gallium nitride-based channel layer and a gallium nitride-based barrier layer are sequentially grown on the substrate. At this time, the gallium nitride-based barrier layer can be treated using the surface treatment method for gallium nitride-based materials described in Example 1 above, or both the gallium nitride-based channel layer and the gallium nitride-based barrier layer can be treated using the surface treatment method for gallium nitride-based materials described in Example 1 above.

[0052] In this embodiment, taking the gallium nitride-based material device prepared by this method as an enhancement-mode high electron mobility transistor as an example, the gallium nitride-based conductive structure layers can specifically include a gallium nitride-based channel layer, a gallium nitride-based barrier layer, and a gallium nitride-based gate dielectric layer. Correspondingly, step S200 specifically includes the following steps:

[0053] Step S210: A gallium nitride (GaN)-based channel layer, a GaN-based barrier layer, and a GaN-based gate dielectric layer are sequentially grown on the substrate, with the GaN-based gate dielectric layer located in the gate region on the GaN-based barrier layer. At this time, the GaN-based barrier layer and the GaN-based gate dielectric layer can be treated using the surface treatment method for GaN-based materials described in Example 1 above, or all three layers can be treated using the surface treatment method for GaN-based materials described in Example 1 above.

[0054] Step S300: Growing conductive electrodes on the top gallium nitride-based conductive structure layer.

[0055] In this embodiment, taking the gallium nitride-based material device prepared by this method as a high electron mobility transistor as an example, the conductive electrodes grown in this step include a gate, a source, and a drain, and the gate is grown between the source and the drain; and if it is specifically a depletion-type high electron mobility transistor, the gate, the source, and the drain are all grown on a gallium nitride-based barrier layer; if it is specifically an enhancement-type high electron mobility transistor, the source and the drain are grown on a gallium nitride-based barrier layer, and the gate is grown on a gallium nitride-based gate dielectric layer.

[0056] In this embodiment, a gallium nitride-based material device prepared by this method is used as an example, which includes an anode and a cathode as conductive electrodes.

[0057] The method for fabricating gallium nitride-based devices in this embodiment improves the electrical output characteristics of the fabricated gallium nitride-based devices by performing a surface treatment on the gallium nitride-based conductive structure layer to reduce the surface states.

[0058] As an optional embodiment of the present invention, in order to further improve the electrical performance of the device prepared by this method, such as... Figure 4 As shown, the fabrication method of this gallium nitride-based material device may further include the following steps:

[0059] Step S400: A passivation layer is grown on the exposed surface of the gallium nitride-based conductive structure layer; the passivation layer also covers the conductive electrode.

[0060] The method for fabricating gallium nitride-based devices in this embodiment involves performing a surface treatment to reduce the surface states of the gallium nitride-based conductive structure layer (i.e., the gallium nitride-based barrier layer in a depletion-type device, or the gallium nitride-based barrier layer and gallium nitride-based gate dielectric layer in an enhancement-type device, etc.) located on the surface of the device, and then growing a passivation layer on the device surface (i.e., the surface where the conductive electrode is located, i.e., the exposed surface of the gallium nitride-based conductive structure layer). This method can prevent the device surface from being exposed to air, which would degrade the effect of hydrogen ion treatment and improve the electrical performance stability of the device prepared by this method.

[0061] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for fabricating a gallium nitride-based material device, characterized in that, Includes the following steps: Obtain the substrate for preparation; A plurality of gallium nitride-based conductive structure layers are sequentially grown on the prepared substrate; Conductive electrodes are grown on the top gallium nitride-based conductive structure layer; The step of sequentially growing a plurality of gallium nitride-based conductive structure layers on the prepared substrate specifically includes the following steps: A gallium nitride-based channel layer and a gallium nitride-based barrier layer are sequentially grown on the substrate; the gallium nitride-based barrier layer is treated using a surface treatment method for gallium nitride-based materials. The surface treatment method for the gallium nitride-based material specifically includes the following steps: An oxide protective film is grown on the surface of the structural layer of a gallium nitride-based material to obtain the first intermediate structural layer; The surface of the first intermediate structural layer is treated with hydrogen ion gas to obtain the second intermediate structural layer. The oxide protective film in the second intermediate structural layer is removed by etching.

2. The method for fabricating gallium nitride-based material devices according to claim 1, characterized in that, The step of treating the surface of the first intermediate structural layer with hydrogen ion gas to obtain the second intermediate structural layer specifically includes the following steps: The first intermediate structural layer is placed in a microwave plasma chemical vapor deposition apparatus for hydrogen ion gas treatment. After a first preset time, the second intermediate structural layer is obtained. The hydrogen flow rate of the microwave plasma chemical vapor deposition apparatus is between 50 Sccm and 200 Sccm, and the first preset time is between 10 min and 15 min.

3. The method for fabricating gallium nitride-based material devices according to claim 1, characterized in that, The oxide protective film is an aluminum oxide protective film.

4. The method for fabricating gallium nitride-based material devices according to claim 1, characterized in that, The step of sequentially growing a plurality of gallium nitride-based conductive structure layers on the prepared substrate specifically includes the following steps: A gallium nitride-based channel layer, a gallium nitride-based barrier layer, and a gallium nitride-based gate dielectric layer are sequentially grown on the substrate. The gallium nitride-based gate dielectric layer is located in the gate region on the gallium nitride-based barrier layer. Both the gallium nitride-based barrier layer and the gallium nitride-based gate dielectric layer are treated using the surface treatment method for gallium nitride-based material devices.

5. The method for fabricating a gallium nitride-based material device according to claim 1, characterized in that, It also includes the following steps: A passivation layer is grown on the exposed surface of the gallium nitride-based conductive structure layer; the passivation layer also covers the conductive electrode.

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