A method of fabricating a gallium nitride device

Abstract

The application discloses a preparation method of a gallium nitride device, and comprises the following steps: growing an aluminum nitride interface layer on a substrate by using a chemical vapor deposition method; wherein, the aluminum source and ammonia gas in a chemical vapor deposition reaction chamber are both in a pulse mode, and in each time period of ammonia gas input, the aluminum source is in two states of input and off, and in each time period of ammonia gas off, the aluminum source is in an input state; sequentially growing a high-resistance layer, a channel layer and a barrier layer on the aluminum nitride interface layer; the high-resistance layer is a gallium nitride layer or an aluminum gallium nitride layer. By the method, the quality of the prepared aluminum nitride interface layer, i.e. the gallium nitride device, can be improved, and the preparation efficiency is relatively high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices, and particularly relates to a preparation method of a gallium nitride device. BACKGROUND

[0002] With the development of microelectronic technology, the third generation of wide band gap semiconductor materials represented by gallium nitride has greater band gap, higher critical breakdown field and higher electron saturation drift speed, stable chemical properties, and physical properties such as high temperature resistance and radiation resistance. The use of gallium nitride material to manufacture electronic devices can further reduce chip area, improve working frequency, improve working temperature, reduce on-resistance, and improve breakdown voltage, etc. Gallium nitride material has great potential in the preparation of microwave and millimeter wave devices.

[0003] Due to the immaturity of the gallium nitride self-supporting substrate technology, at present, the gallium nitride-based material in the gallium nitride microwave and millimeter wave device is mainly deposited on a heterogeneous substrate. So far, the substrates used for growing gallium nitride materials mainly include silicon carbide and silicon (hereinafter referred to as silicon substrate). However, when the gallium nitride-based material is epitaxially grown on the silicon substrate, the lattice mismatch between silicon and gallium nitride crystal material is relatively large. Therefore, an aluminum nitride layer is generally inserted between the gallium nitride material layer and the silicon substrate as a nucleation layer and a transition layer. However, the crystal material quality of the aluminum nitride layer grown by the existing method is relatively poor, and the defects are relatively many, thereby affecting the overall quality of the gallium nitride device. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to solve the problem that the crystal material quality of the aluminum nitride layer grown by the existing method between the gallium nitride material layer and the silicon substrate in the gallium nitride device is relatively poor, the defects are relatively many, and the overall quality of the gallium nitride device is relatively poor.

[0005] To this end, the present application provides a preparation method of a gallium nitride device, comprising the following steps: growing an aluminum nitride interface layer on a substrate by a chemical vapor deposition method; wherein the aluminum source and ammonia gas in the chemical vapor deposition reaction chamber are both in a pulse mode, and in each time period of ammonia gas input, the aluminum source is in two states of input and off, and in each time period of ammonia gas off, the aluminum source is in the input state; growing a high resistance layer, a channel layer and a barrier layer on the aluminum nitride interface layer in sequence; the high resistance layer is a gallium nitride layer or an aluminum gallium nitride layer.

[0006] Further, the aluminum source in the chemical vapor deposition reaction chamber is closed after a first time period of input, and the aluminum source and ammonia gas are input in a pulse mode after the first time period of opening.

[0007] Further, the length of the input time of the aluminum source in one pulse corresponding to the aluminum source is twice the length of the off time of the aluminum source.

[0008] Further, the length of time that the aluminum source is turned on in one pulse corresponding to the aluminum source is the same as the length of time that the ammonia is turned on in one pulse corresponding to the ammonia.

[0009] Further, the length of time that the aluminum source is turned off in one pulse corresponding to the aluminum source is the same as the length of time of the first time period.

[0010] Further, the aluminum nitride interface layer also has an aluminum nitride / aluminum gallium nitride superlattice structure layer grown thereon.

[0011] Further, the aluminum nitride / aluminum gallium nitride superlattice structure layer has a growth temperature of 1050-1250 DEG C and a growth pressure of 50-200 torr.

[0012] Further, the substrate is a Si substrate, or a SiC-on-Si composite substrate prepared from a Si base substrate, or a SiC-on-SOI composite substrate prepared from a SOI base substrate.

[0013] The technical solution provided by the application has the following advantages:

[0014] 1. The method for preparing a gallium nitride device provided by the application separates the aluminum source and the ammonia to some extent by setting the aluminum source and the ammonia in the chemical vapor deposition reaction chamber to be introduced in a pulse mode, and by having the aluminum source be in both an on state and an off state in each time period in which the ammonia is introduced, and by having the aluminum source be in the on state in each time period in which the ammonia is not introduced, thereby solving the problem of poor quality of the aluminum nitride interface layer that is grown due to the strong adsorption of nitrogen atoms on aluminum atoms and the low surface mobility of the aluminum atoms, and thereby improving the quality of the aluminum nitride interface layer and the gallium nitride device prepared using the method.

[0015] 2. The method for preparing a gallium nitride device provided by the application further improves the growth rate of the aluminum nitride interface layer and effectively controls the surface mobility of the aluminum atoms in the aluminum nitride interface layer by introducing the aluminum source and the ammonia in a pulse mode, and by first introducing the aluminum source alone in a first time period (in which the ammonia is in the off state) before introducing the aluminum source and the ammonia in a pulse mode, thereby providing the entire aluminum nitride interface layer with a flat aluminum base, and thereby further improving the quality of the aluminum nitride interface layer and the entire gallium nitride device prepared using the method.

[0016] 3、The preparation method of the gallium nitride device provided by the application, by growing the aluminum nitride / aluminum gallium nitride superlattice structure layer on the aluminum nitride interface layer (the aluminum nitride / aluminum gallium nitride superlattice structure layer is grown between the aluminum nitride interface layer and the high resistance layer), the lattice mismatch of the aluminum nitride interface layer and the high resistance layer (the gallium nitride layer or the aluminum gallium nitride layer) can be relieved, and since the diffusion length of gallium atoms is higher than that of aluminum atoms, the aluminum gallium nitride insertion layer in the aluminum nitride / aluminum gallium nitride superlattice structure layer can be more conducive to dislocation bending and lateral growth, and can make dislocations annihilate at the superlattice interface, thereby further improving the quality of the gallium nitride device prepared by the method. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art of the present application, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 A step flow chart of a preparation method of a gallium nitride device provided by an embodiment of the present application is shown in the figure.

[0019] Figure 2 A structure schematic diagram of a gallium nitride device provided by an embodiment of the present application is shown in the figure.

[0020] Figure 3 A pulse graph of the introduction of an aluminum source and ammonia gas provided by an embodiment of the present application is shown in the figure.

[0021] Figure 4 Another pulse graph of the introduction of an aluminum source and ammonia gas provided by an embodiment of the present application is shown in the figure.

[0022] Explanation of reference signs:

[0023] L1-substrate; L21-aluminum nitride interface layer; L22-aluminum nitride / aluminum gallium nitride superlattice structure layer; L3-high resistance layer; L4-channel layer; L5-potential barrier layer. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described below in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0026] The present embodiment provides a preparation method of a gallium nitride device, as shown in the figure, the method comprises the following steps: Figure 1

[0027] Step S10: growing an aluminum nitride interface layer L21 on the substrate L1 by using a chemical vapor deposition method, wherein the aluminum source and the ammonia gas in the chemical vapor deposition reaction chamber are both in a pulse mode, and in each time period of the ammonia gas being introduced, the aluminum source is in both an introduction state and a closed state, and in each time period of the ammonia gas being closed, the aluminum source is in an introduction state.

[0028] In the present embodiment, the period of the pulse corresponding to the aluminum source and the period of the pulse corresponding to the ammonia gas can be the same or different, as long as in each time period of the ammonia gas being introduced, the aluminum source is in both an introduction state and a closed state, and in each time period of the ammonia gas being closed, the aluminum source is in an introduction state. Specifically, the predetermined pulse number can be set according to the needs of specific application scenarios, for example, the predetermined pulse number can be between 10 and 50.

[0029] In the present embodiment, in order to improve the regularity of the aluminum nitride interface layer L21 prepared, the period of the pulse corresponding to the aluminum source can be set to be the same as the period of the pulse corresponding to the ammonia gas, and in order to ensure that in each time period of the ammonia gas being introduced, the aluminum source is in both an introduction state and a closed state, and in each time period of the ammonia gas being closed, the aluminum source is in an introduction state, the length of time of the aluminum source being introduced in one pulse corresponding to the aluminum source can be set to be different from the length of time of the aluminum source being closed, and / or the length of time of the ammonia gas being introduced in one pulse corresponding to the ammonia gas can be set to be different from the length of time of the ammonia gas being closed.

[0030] In the present embodiment, in order to further improve the regularity of the aluminum nitride interface layer L21 prepared, the length of time of the aluminum source being introduced in one pulse corresponding to the aluminum source can be set to be the same as the length of time of the ammonia gas being introduced in one pulse corresponding to the ammonia gas; at this time, the length of time of the aluminum source being introduced in one pulse corresponding to the aluminum source and the length of time of the aluminum source being closed are different, and the length of time of the ammonia gas being introduced in one pulse corresponding to the ammonia gas and the length of time of the ammonia gas being closed are different.

[0031] ​In the embodiment, the specific ratio between the length of time when the aluminum source is turned on and the length of time when the aluminum source is turned off in one pulse corresponding to the aluminum source can be set according to the requirements for the production speed of the aluminum nitride interface layer L21 and the surface mobility of aluminum atoms in the actual application scenario. Specifically, the length of time when the aluminum source is turned on in one pulse corresponding to the aluminum source can be one and a half times, two times, or three times the length of time when the aluminum source is turned off. For example, if the length of time when the aluminum source is turned on in one pulse corresponding to the aluminum source is two times the length of time when the aluminum source is turned off, the pulse pattern corresponding to the aluminum source and the pulse pattern corresponding to the ammonia are as shown in FIG. 8. Figure 2

[0032] In the embodiment, the period of the pulse corresponding to the aluminum source can also be set according to the requirements of the specific application scenario. For example, the period can be set to be between 3-15 seconds, such as 3 seconds, 6 seconds, 9 seconds, or 15 seconds.

[0033] Specifically, if the period of the pulse corresponding to the aluminum source is 6 seconds, and the length of time when the aluminum source is turned on in one pulse corresponding to the aluminum source is two times the length of time when the aluminum source is turned off, the period of the pulse corresponding to the ammonia is the same as the period of the pulse corresponding to the aluminum source, and the length of time when the ammonia is turned on in one pulse corresponding to the ammonia is the same as the length of time when the aluminum source is turned on in one pulse corresponding to the aluminum source, during the growth of the aluminum nitride interface, the specific turning-on mode of the aluminum source and the ammonia is as follows:

[0034] Step A: Turn off the ammonia and turn on the aluminum source at the same time. Although this step is described from the moment when the ammonia is turned off and the aluminum source is turned on at the same time, it is not limited thereto. Step A can also be turning on the ammonia and turning off the aluminum source at the same time, and the following steps B-D are adjusted accordingly.

[0035] Step B: After 2 seconds, turn on the ammonia and turn off the aluminum source at the same time.

[0036] Step C: After 2 seconds, turn on the aluminum source.

[0037] Step D: After the aluminum source is turned on for 2 seconds, the ammonia is turned on for 4 seconds, and then the ammonia is turned off. At this time, the ammonia and the aluminum source have both gone through one pulse.

[0038] Step E: Repeat the above steps A-D, and the number of repetitions can be 10-50 times. The pulse pattern corresponding to the aluminum source and the ammonia is as shown in FIG. 8 Figure 2 , which is shown with 5 pulses. Figure 2

[0039] Step S20: sequentially grow a high-resistance layer L3, a channel layer L4, and a barrier layer L5 on the aluminum nitride interface layer L21, and the high-resistance layer L3 is a gallium nitride layer or an aluminum gallium nitride layer.

[0040] ​​In this embodiment, the gallium nitride device prepared after the above steps S10 and S20 is as follows: Figure 3 As shown.

[0041] In this embodiment, the high-resistivity layer L3 can be a thin film layer grown by metal-organic vapor deposition without intentional doping. Specifically, the thickness of the thin film layer can be in the range of 1um-5um.

[0042] In this embodiment, the channel layer L4 can also be a gallium nitride thin film or an aluminum gallium nitride thin film, and can also be prepared by metal-organic vapor deposition unintentionally doped. Specifically, the thickness of the channel layer L4 can be in the range of 50-300 nm.

[0043] In this embodiment, the barrier layer L5 is an aluminum gallium nitride thin film layer, which can be prepared by metal-organic vapor deposition and has a thickness of 5-35 nm.

[0044] In this application, in order to alleviate the lattice mismatch between the aluminum nitride interface layer L21 and the high-resistivity layer L3 (gallium nitride layer or aluminum gallium nitride layer), such as Figure 3 As shown, an aluminum nitride / aluminum gallium nitride (AGaN) superlattice structure layer L22 can also be grown on the aluminum nitride interface layer L21. Since the diffusion length of gallium atoms is longer than that of aluminum atoms, the AGaN insertion layer in the AGaN / AGaN superlattice structure layer L22 is more conducive to dislocation bending and lateral growth, and can also cause dislocations to annihilate at the superlattice interface, thereby further improving the quality of the gallium nitride device prepared by this method. Specifically, the AGaN / AGaN superlattice structure layer L22 can be prepared by metal-organic vapor deposition under high temperature and low pressure growth conditions. Specifically, the growth temperature can be 1050-1250℃, the growth pressure can be 50-200 torr, and the superlattice period can be 5-40 times.

[0045] In the present application, in order to further improve the quality of the aluminum nitride interface layer L21, the aluminum source in the chemical vapor deposition reaction chamber can be set to be closed after being introduced for a first time period, and the ammonia gas can be set to be opened after being introduced for the first time period, and the aluminum source and the ammonia gas are introduced in a pulse mode, so that the entire aluminum nitride interface layer L21 has a flat aluminum base. Specifically, the length of the first time period is between 1-5 seconds, and the first time period can be the same as the length of time that the aluminum source is introduced in one pulse corresponding to the aluminum source, or it can be different; when the first time period is the same as the length of time that the aluminum source is introduced in one pulse corresponding to the aluminum source, and the length of time that the aluminum source is introduced in one pulse corresponding to the aluminum source is twice the length of time that the aluminum source is closed, the period of a pulse corresponding to the ammonia gas is the same as the period of a pulse corresponding to the aluminum source, and the length of time that the ammonia gas is introduced in one pulse corresponding to the ammonia gas is the same as the length of time that the aluminum source is introduced in one pulse corresponding to the aluminum source, the first time period can be regarded as part of the pulse corresponding to the aluminum source and the pulse corresponding to the ammonia gas; taking 5 seconds as an example, the specific introduction mode of the aluminum source and the ammonia gas during the growth of the aluminum nitride interface is as follows:

[0046] Step a: introduce the aluminum source for 5 seconds. At this time, the ammonia gas is in a closed state.

[0047] Step b: close the aluminum source and simultaneously open the ammonia gas.

[0048] Step c: after the aluminum source is closed for 5 seconds, open the aluminum source.

[0049] Step d: after the aluminum source is introduced for 5 seconds, the ammonia gas is introduced for 10 seconds, and then the ammonia gas is closed.

[0050] Step e: after the ammonia gas is closed for 5 seconds, the aluminum source is introduced for 10 seconds, and then the aluminum source is closed.

[0051] Step f: repeat the above steps b-e, and the number of repetitions can be 10-50 times. The pulse pattern corresponding to the aluminum source and the ammonia gas is shown in Figure 4 . Figure 4 .

[0052] In the present application, the substrate L1 can be a Si substrate, in addition, in order to reduce the preparation cost of the preparation method of the gallium nitride device, the substrate L1 can also be set to be a SiC-on-Si composite substrate prepared from a Si base substrate, or a SiC-on-SOI composite substrate prepared from a SOI base substrate. Specifically, the preparation of the SiC-on-Si composite substrate and the SiC-on-SOI composite substrate can be realized by means of heat treatment, carbonization, or epitaxial growth of silicon carbide, etc. Taking the preparation of the SiC-on-Si composite substrate based on the Si base substrate by means of heat treatment as an example, the Si base substrate can be placed in a high-temperature furnace and heat-treated for 3-5 min in a carbon-containing atmosphere to generate a SiC-on-Si composite substrate.

[0053] The method for preparing the gallium nitride device in the application, by setting the aluminum source and ammonia gas in the chemical vapor deposition reaction chamber as a pulse mode during the preparation of the aluminum nitride interface layer L21, and in each time period of the ammonia gas, the aluminum source is in the state of opening and closing, and in each time period of the ammonia gas, the aluminum source is in the state of opening, so as to separate the aluminum source and ammonia gas to a certain extent, solve the problem of poor quality of the grown aluminum nitride interface layer caused by the strong adsorption of nitrogen atoms to aluminum atoms and the low surface mobility of aluminum atoms, so as to improve the quality of the aluminum nitride interface layer and the gallium nitride device prepared by the method; in addition, the aluminum source and ammonia gas are not completely separated, and the growth rate of the aluminum nitride interface layer can be improved, and the surface mobility of aluminum atoms in the aluminum nitride interface layer can be effectively controlled.

[0054] Obviously, the above embodiments are only examples for clearly illustrating, but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the application.

Claims

1. A method of fabricating a gallium nitride device, comprising: The method comprises the following steps: An aluminum nitride interface layer (L21) is grown on a substrate (L1) by chemical vapor deposition; wherein the aluminum source and ammonia in a chemical vapor deposition reaction chamber are both input in a pulse mode, and in each time period when ammonia is input, the aluminum source is in two states of being input and being closed, and in each time period when ammonia is closed, the aluminum source is in the state of being input; the aluminum source in the chemical vapor deposition reaction chamber is closed after a first time period, and the ammonia is opened after the first time period, and the aluminum source and ammonia are input in a pulse mode; the length of the input time of the aluminum source in one pulse corresponding to the aluminum source is twice the length of the closing time of the aluminum source; the length of the input time of the aluminum source in one pulse corresponding to the aluminum source is the same as the length of the input time of the ammonia in one pulse corresponding to the ammonia; the length of the closing time of the aluminum source in one pulse corresponding to the aluminum source is the same as the length of the first time period; A high-resistance layer (L3), a channel layer (L4) and a barrier layer (L5) are sequentially grown on the aluminum nitride interface layer (L21); the high-resistance layer (L3) is a gallium nitride layer or an aluminum gallium nitride layer.

2. The method of fabricating a gallium nitride device of claim 1, wherein, The aluminum nitride interface layer (L21) further has an aluminum nitride / aluminum gallium nitride superlattice structure layer (L22) grown thereon.

3. The method of fabricating a gallium nitride device of claim 2, wherein, The growth temperature of the aluminum nitride / aluminum gallium nitride superlattice structure layer (L22) is 1050-1250 ℃, and the growth pressure is 50-200 torr.

4. The method of fabricating a gallium nitride device of claim 2, wherein, The substrate (L1) is a Si substrate, or a SiC-on-Si composite substrate prepared from a Si base substrate, or a SiC-on-SOI composite substrate prepared from a SOI base substrate.

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