Preparation method for improving the quality of high electron mobility transistor epitaxial wafer

Abstract

The present invention provides a preparation method for improving the quality of high electron mobility transistor epitaxial wafers, belonging to the technical field of semiconductor devices. A first AlN layer and a second AlN layer are sequentially grown on a substrate, and the growth temperature of the second AlN layer is 100 to 300°C higher than that of the first AlN layer, so as to release stress and improve quality. During the growth of the second AlN layer, Ar is used as a carrier gas to promote the plane movement of Al atoms and improve the growth uniformity. For the AlN film formed during the growth of the second AlN layer, H 2 The treatment reduces dislocations, improves the quality of the second AlN layer, and also improves the quality of the AlGaN buffer layer grown on the first AlN layer, the second AlN layer, and the quality of the underlying structure can improve the quality of the high electron mobility transistor epitaxial wafer that is ultimately grown on the underlying structure.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor devices, and in particular to a preparation method for improving the quality of high electron mobility transistor epitaxial wafers. Background Art

[0002] HEMT (High Electron Mobility Transistor) is a heterojunction field effect transistor, which is widely used in various electrical appliances. HEMT epitaxial wafer is the basis for preparing HEMT devices. HEMT epitaxial wafer includes substrate and AlN layer, AlGaN buffer layer, GaN channel layer, AlGaN barrier layer and GaN cap layer stacked on the substrate in sequence.

[0003] When the AlN layer grows on the substrate, since Al atoms have a high surface adhesion coefficient, the surface migration ability of Al atoms is relatively weak during the growth of the AlN layer or the AlGaN layer with a high Al component. If the Al atoms do not have enough energy to migrate to the lowest energy nucleation positions such as steps or kinks, they will serve as nucleation points at the initial position and grow into islands, forming a three-dimensional growth pattern. During the island growth process, defects such as high-density dislocations and grain interfaces will be generated around the islands. Two adjacent three-dimensional islands that continue to grow and merge will generate tensile stress, which may cause gross dislocations or even cracks on the surface of the epitaxial layer. This results in poor quality of the AlN layer and AlGaN buffer layer grown directly on the substrate, and poor quality of the bottom layer will lead to the quality of the final high electron mobility transistor epitaxial wafer. Summary of the invention

[0004] The disclosed embodiment provides a preparation method for improving the quality of a high electron mobility transistor epitaxial wafer, which can improve the crystal quality of the AlN layer and the AlGaN buffer layer to improve the quality of the high electron mobility transistor epitaxial wafer. The technical solution is as follows:

[0005] The embodiment of the present disclosure provides a high electron mobility transistor epitaxial wafer, and the preparation method for improving the quality of the high electron mobility transistor epitaxial wafer includes:

[0006] providing a substrate;

[0007] sequentially growing a first AlN layer and a second AlN layer on the substrate, wherein the growth temperature of the second AlN layer is 100 to 300° C. higher than the growth temperature of the first AlN layer;

[0008] sequentially growing an AlGaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer on the second AlN layer;

[0009] Growing the second AlN layer, comprising:

[0010] Using argon as carrier gas, Al source and reaction gas are introduced into the reaction chamber to grow an AlN film layer;

[0011] Turn off the Al source and reaction gas;

[0012] Introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. to treat the AlN film layer;

[0013] The above steps are repeated until the second AlN layer is obtained.

[0014] Optionally, the thickness of each AlN film layer is 5-10 nm.

[0015] Optionally, hydrogen is introduced into the reaction chamber at a temperature of 1050-1250° C. for a period of 5-10 seconds to treat the AlN film layer.

[0016] Optionally, the second AlN layer has a thickness of 100-200 nm.

[0017] Optionally, growing the AlGaN buffer layer comprises:

[0018] Using argon as carrier gas, Al source, Ga source and reaction gas are introduced into the reaction chamber to grow an AlGaN film layer;

[0019] Turn off the Al source, Ga source and reaction gas;

[0020] Introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. to treat the AlGaN film layer;

[0021] The above steps are repeated until the AlGaN layer is obtained.

[0022] Optionally, the AlGaN film layer has a thickness of 20-50 nm.

[0023] Optionally, the method of introducing Al source, Ga source and reaction gas into the reaction chamber using argon as a carrier gas to grow the AlGaN film layer further includes:

[0024] Argon is used as a carrier gas to introduce Al source, Ga source, Fe source and reaction gas into the reaction chamber to grow an AlGaN film layer.

[0025] Optionally, the flow rate of the Fe source is 50-200 sccm.

[0026] Optionally, the growth temperature of the first AlN layer is 800-1000° C., the growth temperature of the second AlN layer is 1050-1250° C., and the thickness of the first AlN layer is 50-100 nm.

[0027] Optionally, the preparation method further comprises:

[0028] Before sequentially growing the first AlN layer and the second AlN layer on the substrate, a layer of Al atoms is pre-spread on the substrate.

[0029] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include:

[0030] The first AlN layer and the second AlN layer are sequentially grown on the substrate, the growth temperature of the second AlN layer is 100-300°C higher than that of the first AlN layer, the first AlN layer is used as the basis, and the second AlN layer with a higher temperature is subsequently grown, so as to release certain stress and ensure that the quality of the first AlN layer and the second AlN layer is good, and the first AlN layer can be transitioned to the second AlN layer to establish a good underlying structural foundation. In the process of growing the second AlN layer, Ar is used as a carrier gas for growth. Compared with the commonly used N2 or H2 carrier gas, Ar has a larger atomic mass, can provide higher momentum, can improve the surface migration ability of Al atoms, and promote the plane movement of Al atoms, so that the first AlN layer and the second AlN layer can grow in a film-like shape as a whole, the overall crystal quality growth can be more uniform, and the surface flatness is also higher. For the AlN film formed during the growth of the second AlN layer, the Al source and the reaction gas are turned off and hydrogen is introduced into the reaction chamber at a temperature of 1050-1250°C. H2 has a certain etching property under high temperature conditions, and can be used to etch the surface of the epitaxial layer and then recrystallize, which can reduce the edge dislocation density formed during the AlN growth process due to argon as a carrier gas, thereby improving the crystal quality of the epitaxial layer. The quality of the first AlN layer and the second AlN layer is improved, and the quality of the first AlN layer, the second AlN layer and the grown AlGaN buffer layer will also be improved. The improvement of the quality of the underlying structure can improve the quality of the high electron mobility transistor epitaxial wafer that is finally grown on the underlying structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 It is a flow chart of a preparation method for improving the quality of a high electron mobility transistor epitaxial wafer provided by an embodiment of the present disclosure;

[0033] Figure 2 is a schematic structural diagram of a high electron mobility transistor epitaxial wafer provided by an embodiment of the present disclosure;

[0034] Figure 3 is a flow chart of another method for preparing a high electron mobility transistor epitaxial wafer for improving its quality provided by an embodiment of the present disclosure;

[0035] Figure 4 It is a schematic diagram of the structure of another high electron mobility transistor epitaxial wafer provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0037] Figure 1 is a flow chart of a method for preparing a high electron mobility transistor epitaxial wafer for improving its quality provided by an embodiment of the present disclosure, such as Figure 1 As shown, the preparation method for improving the quality of a high electron mobility transistor epitaxial wafer includes:

[0038] S101: providing a substrate.

[0039] S102: sequentially growing a first AlN layer and a second AlN layer on the substrate, wherein the growth temperature of the second AlN layer is 100-300° C. higher than the growth temperature of the first AlN layer. Growing the second AlN layer comprises: introducing an Al source and a reaction gas into a reaction chamber using argon as a carrier gas to grow an AlN film layer; closing the Al source and the reaction gas and introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. to treat the AlN film layer; and repeating the above steps until the second AlN layer is obtained.

[0040] S103: sequentially growing an AlGaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer on the second AlN layer.

[0041] The first AlN layer and the second AlN layer are sequentially grown on the substrate, the growth temperature of the second AlN layer is 100-300°C higher than that of the first AlN layer, the first AlN layer is used as the basis, and the second AlN layer with a higher temperature is subsequently grown, so as to release certain stress and ensure that the quality of the first AlN layer and the second AlN layer is good, and the first AlN layer can be transitioned to the second AlN layer to establish a good underlying structural foundation. In the process of growing the second AlN layer, Ar is used as a carrier gas for growth. Compared with the commonly used N2 or H2 carrier gas, Ar has a larger atomic mass, can provide higher momentum, can improve the surface migration ability of Al atoms, and promote the plane movement of Al atoms, so that the first AlN layer and the second AlN layer can grow in a film-like shape as a whole, the overall crystal quality growth can be more uniform, and the surface flatness is also higher. For the AlN film formed during the growth of the second AlN layer, the Al source and the reaction gas are turned off and hydrogen is introduced into the reaction chamber at a temperature of 1050-1250°C. H2 has a certain etching property under high temperature conditions, and can be used to etch the surface of the epitaxial layer and then recrystallize, which can reduce the edge dislocation density formed during the AlN growth process due to argon as a carrier gas, thereby improving the crystal quality of the epitaxial layer. The quality of the first AlN layer and the second AlN layer is improved, and the quality of the first AlN layer, the second AlN layer and the grown AlGaN buffer layer will also be improved. The improvement of the quality of the underlying structure can improve the quality of the high electron mobility transistor epitaxial wafer that is finally grown on the underlying structure.

[0042] It should be noted that when conventional N2 or H2 is used as a carrier gas, the Al atoms cannot obtain enough energy to migrate to the nucleation position, resulting in the AlN layer (the same as the AlGaN buffer layer) being in a three-dimensional growth mode. In the case of a three-dimensional growth mode, three-dimensional islands will be formed. Two-dimensional planar growth is lateral uniform growth. When the three-dimensional islands merge, tensile stress will be generated, which may cause the surface of the epitaxial layer to be rough or even cracked. The present disclosure uses argon as a carrier gas, and the growth state of the second AlN layer is closer to the state of two-dimensional growth, which can effectively improve the growth uniformity and planarity, reduce the occurrence of tensile stress caused by three-dimensional growth and the density of cracks, and the quality of the second AlN layer can be effectively improved.

[0043] Optionally, the growth temperature of the first AlN layer is 800-1000° C., the growth temperature of the second AlN layer is 1050-1250° C., and the thickness of the first AlN layer is 50-100 nm.

[0044] The growth temperature of the first AlN layer and the growth temperature of the second AlN layer are respectively within the above ranges, and the first AlN layer can be slowly deposited on the substrate to ensure the surface flatness of the first AlN layer and the crystal quality of the first AlN layer. The thickness of the first AlN layer is 50-100nm, which can ensure the stability of the basic structure and transition to the second AlN layer. The second AlN layer can grow stably on the first AlN layer and release a certain amount of stress, thereby improving the overall quality of the first AlN layer and the second AlN layer obtained. On the other hand, the growth temperature of the second AlN layer is within the above range, which can also facilitate the treatment of hydrogen during the growth of the second AlN layer, without the need for frequent temperature adjustment, and can also effectively control the growth cost of the second AlN layer. While improving the quality of the first AlN layer and the second AlN layer, the preparation cost of the first AlN layer and the second AlN layer will not be excessively increased.

[0045] Optionally, the growth pressure of the first AlN layer and the second AlN layer is 40-70 mbar, which can ensure the stable growth of the first AlN layer and the second AlN layer.

[0046] Optionally, the thickness of each AlN film layer is 5-10 nm.

[0047] When the thickness of each AlN film layer is within the above range, the growth of the AlN film layer can be more uniform, and the surface flatness of the AlN film layer is higher. Combined with the subsequent hydrogen treatment, the surface dislocation density of the AlN film layer can be effectively reduced, and the crystal quality of the second AlN layer finally obtained can be improved.

[0048] Optionally, hydrogen is introduced into the reaction chamber at a temperature of 1050-1250° C. for 5-10 seconds to treat the AlN film layer.

[0049] The duration of hydrogen treatment is within the above range, which can ensure that the surface of the AlN film layer is sufficiently treated by hydrogen, and the AlN film layer also undergoes sufficient annealing during this time, and the crystal quality of the AlN film layer can be further improved.

[0050] Optionally, the thickness of the second AlN layer is 100-200 nm.

[0051] When the thickness of the second AlN layer is within the above range, the quality of the second AlN layer is good, and the second AlN layer can also provide a good growth foundation for the AlGaN buffer layer, thereby improving the quality of the AlGaN buffer layer.

[0052] For ease of understanding, here is provided Figure 2 , Figure 2 is a schematic diagram of the structure of a high electron mobility transistor epitaxial wafer provided by an embodiment of the present disclosure, with reference to Figure 2It can be seen that the high electron mobility transistor epitaxial wafer includes a substrate 1 and a first AlN layer 2, a second AlN layer 3, an AlGaN buffer layer 4, a GaN channel layer 5, an AlGaN barrier layer 6 and a GaN cap layer 7 which are sequentially stacked on the substrate 1.

[0053] Figure 3 is another flow chart of a method for preparing a high electron mobility transistor epitaxial wafer for improving its quality provided by an embodiment of the present disclosure, with reference to Figure 3 It can be seen that the preparation method for improving the quality of high electron mobility transistor epitaxial wafers may include:

[0054] S201: providing a substrate.

[0055] S202: Before sequentially growing the first AlN layer and the second AlN layer on the substrate, pre-laying a layer of Al atoms on the substrate.

[0056] Since the lateral mobility of Al atoms is relatively low, pre-laying the Al atomic layer is beneficial to improving the flatness of the subsequent first AlN layer, thereby improving the uniformity of the entire epitaxial layer, which is beneficial to improving the overall quality of the HEMT epitaxial wafer.

[0057] Optionally, an Al source with a flow rate of 50-200 sccm is pre-introduced into the reaction chamber for 10s-100s at a temperature of 1000-1100° C. to lay an Al atomic layer on the substrate.

[0058] Under the above temperature conditions, an Al source with a flow rate of 50 to 200 sccm is introduced into the reaction chamber for a certain period of time, and a relatively stable Al atomic layer with moderate thickness can be stacked on the substrate to ensure stable and uniform growth of the subsequent AlN layer.

[0059] S203: sequentially growing a first AlN layer and a second AlN layer on the substrate, wherein the growth temperature of the second AlN layer is 100-300° C. higher than the growth temperature of the first AlN layer. Growing the second AlN layer comprises: introducing an Al source and a reaction gas into a reaction chamber using argon as a carrier gas to grow an AlN film layer; closing the Al source and the reaction gas and introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. to treat the AlN film layer; and repeating the above steps until the second AlN layer is obtained.

[0060] Step S203 can refer to Figure 1 The step S102 in the process is described above, so it will not be described in detail here.

[0061] S204: growing an AlGaN buffer layer on the second AlN layer.

[0062] Optionally, step S204 may include: introducing an Al source, a Ga source and a reaction gas into a reaction chamber using argon as a carrier gas to grow an AlGaN film layer; closing the Al source, the Ga source and the reaction gas; introducing hydrogen into the reaction chamber at a temperature of 1050 to 1250° C. to treat the AlGaN film layer; and repeating the above steps until an AlGaN layer is obtained.

[0063] During the growth of the AlGaN buffer layer, a growth method similar to the second AlN layer is also adopted, which can improve the growth uniformity and surface flatness of the AlGaN buffer layer. While the crystal quality of the AlGaN buffer layer itself is improved, the structure of gallium nitride grown based on the surface of the AlGaN buffer layer can also be improved.

[0064] Optionally, the thickness of the AlGaN film layer is 20-50 nm.

[0065] When the thickness of each AlGaN film layer is within the above range, the growth of the AlGaN film layer can be relatively uniform, and the surface flatness of the AlGaN film layer is relatively high. Combined with subsequent hydrogen treatment, the surface dislocation density of the AlGaN film layer can be effectively reduced, thereby improving the crystal quality of the second AlGaN layer finally obtained.

[0066] Optionally, hydrogen is introduced into the reaction chamber to treat the AlGaN film layer at a temperature of 1050-1250° C. for 5-10 seconds.

[0067] The duration of hydrogen treatment is within the above range, which can ensure that the surface of the AlGaN film layer is sufficiently treated by hydrogen, and the AlGaN film layer also undergoes sufficient annealing during this time, and the crystal quality of the AlGaN film layer can be further improved.

[0068] Optionally, the thickness of the AlGaN buffer layer is 100-200 nm.

[0069] When the thickness of the AlGaN buffer layer is within the above range, the quality of the AlGaN buffer layer is good and can also provide a good growth foundation for subsequent growth structures.

[0070] Optionally, Al source, Ga source and reaction gas are introduced into the reaction chamber using argon as a carrier gas to grow an AlGaN film layer, and the method further includes:

[0071] Argon is used as a carrier gas to introduce Al source, Ga source, Fe source and reaction gas into the reaction chamber to grow an AlGaN film layer.

[0072] The incorporation of Fe elements into the AlGaN film layer can achieve high resistance of the AlGaN buffer layer, facilitating the transition to subsequent high-resistance gallium nitride materials.

[0073] It should be noted that, under the premise that argon is used as a carrier gas to pass through the Al source, Ga source, Fe source and reaction gas to grow the AlGaN film layer, during the subsequent hydrogen treatment of the AlGaN film layer, the Al source, Ga source, Fe source and reaction gas also need to be turned off at the same time.

[0074] Optionally, the flow rate of the Fe source is 50-200 sccm.

[0075] When the flow rate of the Fe source is within the above range, an AlGaN buffer layer of good quality can be obtained.

[0076] For example, the Fe doping concentration in the AlGaN buffer layer is 10 18 ~10 20 cm -3 The AlGaN buffer layer has good quality and can achieve a good transition with the subsequent high-resistance GaN material.

[0077] Optionally, the growth conditions of the AlGaN buffer layer include: a growth temperature of 1050° C. to 1250° C. and a pressure of 40 to 70 mbar, so that an AlGaN buffer layer of good quality can be obtained.

[0078] In an implementation provided by the present disclosure, the growth temperature of the second AlN layer can be equal to the growth temperature of the AlGaN buffer layer. While obtaining a second AlN layer and an AlGaN buffer layer of good quality, there is no need to adjust the temperature change, and the preparation cost of the second AlN layer and the AlGaN buffer layer can be controlled.

[0079] S205: growing a GaN high resistance layer on the AlGaN buffer layer.

[0080] Optionally, the growth conditions of the GaN high resistance layer include: a growth temperature of 950° C. to 1050° C. and a pressure of 40 to 70 mbar, so that a GaN high resistance layer of good quality can be obtained.

[0081] For example, the thickness of the GaN high resistance layer is between 1.0 and 1.5 microns, and the GaN high resistance layer is doped with a range of 1019 cm -3 ~1020cm -3 The carbon element between them improves the quality of the final HEMT epitaxial wafer.

[0082] S206: growing a GaN channel layer on the GaN high resistance layer.

[0083] Optionally, the growth conditions of the GaN channel layer include: a growth temperature of 1050° C. to 1150° C. and a pressure of 150 to 250 mbar, so that a GaN channel layer of good quality can be obtained.

[0084] Exemplarily, the thickness of the GaN channel layer is between 1.0 and 1.5 micrometers, thereby improving the quality of the final HEMT epitaxial wafer and obtaining a GaN channel layer of good quality.

[0085] S207: growing an AlN insertion layer on the GaN channel layer.

[0086] Optionally, the growth temperature of the AlN insertion layer is 1050° C. to 1150° C., and the growth pressure of the AlN insertion layer is 40 to 70 mbar, so that a good quality AlN insertion layer can be obtained.

[0087] S208: growing an AlGaN barrier layer on the AlN insertion layer.

[0088] Optionally, the growth temperature of the AlGaN barrier layer is 1050° C. to 1150° C., and the growth pressure of the AlGaN barrier layer is 40 to 70 mbar. The quality of the obtained AlGaN barrier layer is good.

[0089] In an implementation provided by the present disclosure, the growth temperature of the AlGaN barrier layer may be 1020° C. The present disclosure does not limit this.

[0090] S209: growing a GaN cap layer on the AlGaN barrier layer.

[0091] Optionally, the growth temperature of the GaN cap layer is 1050° C. to 1150° C., and the growth pressure of the AlGaN barrier layer is 40 to 70 mbar. The quality of the obtained GaN cap layer is good.

[0092] S210: Lowering the temperature of the reaction chamber to room temperature in a nitrogen atmosphere to terminate the epitaxial growth.

[0093] Step S210 can release the thermal stress inside the HEMT epitaxial wafer to a certain extent, thereby improving the quality of the HEMT epitaxial wafer finally obtained.

[0094] It should be noted that in the disclosed embodiment, Veeco K 465i or C4 or RB MOCVD (Metal Organic Chemical Vapor Deposition) equipment is used to realize the growth method of LED. High-purity H2 (hydrogen) or high-purity N2 (nitrogen) or a mixture of high-purity H2 and high-purity N2 is used as a carrier gas, high-purity NH3 is used as an N source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) are used as gallium sources, trimethyl indium (TMIn) is used as an indium source, silane (SiH4) is used as an N-type dopant, trimethyl aluminum (TMAl) is used as an aluminum source, bis(ocene magnesium) (CP2Mg) is used as a P-type dopant, and ferrocene (Cp2Fe) is used as a precursor of an iron (Fe) source.

[0095] Figure 4 is a schematic diagram of the structure of another high electron mobility transistor epitaxial wafer provided in an embodiment of the present disclosure, with reference to Figure 4 It can be seen that the high electron mobility transistor epitaxial wafer may include a substrate 1 and a first AlN layer 2, a second AlN layer 3, an AlGaN buffer layer 4, a GaN high resistance layer 8, a GaN channel layer 5, an AlN insertion layer 9, an AlGaN barrier layer 6 and a GaN cap layer 7 stacked in sequence on the substrate 1.

[0096] Optionally, the thickness of the second AlN layer 3 is 150-300 nm, which can ensure that the quality of the second AlN layer 3 is good and provide a good growth foundation for the HEMT epitaxial wafer.

[0097] Exemplarily, the thickness of the AlGaN buffer layer 4 is 1 to 1.5 micrometers. The obtained AlGaN buffer layer 4 has good quality.

[0098] For example, the thickness of the GaN high resistance layer 8 is 300-600 nm, which can provide a good buffering effect.

[0099] Optionally, the thickness of the GaN channel layer 5 may be 100-400 nm.

[0100] The thickness of the GaN channel layer 5 is relatively appropriate, the cost is relatively reasonable, and the quality of the high electron mobility transistor epitaxial wafer can be effectively improved.

[0101] In an implementation provided by the present disclosure, the thickness of the GaN channel layer 5 may be 400 nm, which is not limited by the present disclosure.

[0102] Figure 4 Medium relative Figure 1 In the structure of the HEMT epitaxial wafer, an AlGaN buffer layer 4, a GaN high-resistance layer 8 and an AlN insertion layer 9 are added. On the one hand, the negative impact caused by the lattice mismatch of the bottom layer is small. On the other hand, the interface between the AlN insertion layer 9 and the GaN channel layer 5, and the interface between the AlN insertion layer 9 and the AlGaN barrier layer 6 form a two-dimensional electron gas, which increases the accumulation of carriers at the interface through the two-dimensional electron gas, and can ensure the use effect of the high electron mobility transistor epitaxial wafer.

[0103] Optionally, the thickness of the AlN insertion layer 9 is 0.5-2 nm.

[0104] When the thickness of the AlN insertion layer 9 is within the above range, the two-dimensional electron gas can be effectively generated without increasing the cost too much.

[0105] In an implementation provided by the present disclosure, the thickness of the AlN insertion layer 9 may be 2 nm, which is not limited by the present disclosure.

[0106] Optionally, the thickness of the AlGaN barrier layer 6 may be 15-40 nm, which can ensure the quality of the high electron mobility transistor epitaxial wafer.

[0107] In an implementation provided by the present disclosure, the thickness of the AlGaN barrier layer 6 may be 100 nm, which is not limited by the present disclosure.

[0108] Exemplarily, the GaN cap layer 7 may be a P-type GaN layer, which is convenient for preparation and acquisition.

[0109] Optionally, the thickness of the GaN cap layer 7 is 3-10 nm. The obtained GaN cap layer 7 has good overall quality.

[0110] Exemplarily, the impurity in the GaN cap layer 7 is Mg, which is convenient for preparation and acquisition.

[0111] It should be noted that Figure 4 This is only one implementation of the high electron mobility transistor epitaxial wafer provided in the embodiment of the present disclosure. In other implementations provided in the present disclosure, the high electron mobility transistor epitaxial wafer may also be other forms of high electron mobility transistor epitaxial wafer including a reflective layer, and the present disclosure does not limit this.

[0112] The above does not limit the present disclosure in any form. Although the present disclosure has been disclosed as above through the embodiments, it is not used to limit the present disclosure. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present disclosure. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure still falls within the scope of the technical solution of the present disclosure.

Claims

1. A method for improving the quality of a high electron mobility transistor epitaxial wafer, characterized in that: The preparation method for improving the quality of a high electron mobility transistor epitaxial wafer comprises: providing a substrate; sequentially growing a first AlN layer and a second AlN layer on the substrate, wherein the growth temperature of the second AlN layer is 100 to 300° C. higher than the growth temperature of the first AlN layer; sequentially growing an AlGaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer on the second AlN layer; Growing the second AlN layer, comprising: Using argon as carrier gas, Al source and reaction gas are introduced into the reaction chamber to grow an AlN film layer; Turn off the Al source and reaction gas; Introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. to treat the AlN film layer; Repeat the above steps until the second AlN layer is obtained.

2. The method for preparing a high electron mobility transistor epitaxial wafer according to claim 1, characterized in that: The thickness of each AlN film layer is 5-10 nm.

3. The method for preparing a high electron mobility transistor epitaxial wafer according to claim 1, characterized in that: The AlN film layer is treated by introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. for 5-10 seconds.

4. The method for preparing a high electron mobility transistor epitaxial wafer according to any one of claims 1 to 3, characterized in that: The thickness of the second AlN layer is 100-200 nm.

5. The method for preparing a high electron mobility transistor epitaxial wafer according to any one of claims 1 to 3, characterized in that: Growing the AlGaN buffer layer comprises: Using argon as carrier gas, Al source, Ga source and reaction gas are introduced into the reaction chamber to grow an AlGaN film layer; Turn off the Al source, Ga source and reaction gas; Introducing hydrogen into the reaction chamber at a temperature of 1050-1250° C. to treat the AlGaN film layer; The above steps are repeated until the AlGaN layer is obtained.

6. The method for preparing a high electron mobility transistor epitaxial wafer according to claim 5, characterized in that: The thickness of the AlGaN film layer is 20-50 nm.

7. The method for preparing a high electron mobility transistor epitaxial wafer according to claim 5, characterized in that: The method of using argon as a carrier gas to introduce an Al source, a Ga source and a reaction gas into the reaction chamber to grow an AlGaN film layer also includes: Argon is used as a carrier gas to introduce Al source, Ga source, Fe source and reaction gas into the reaction chamber to grow an AlGaN film layer.

8. The method for preparing a high electron mobility transistor epitaxial wafer according to claim 7, characterized in that: The flow rate of the Fe source is 50-200 sccm.

9. The method for improving the quality of a high electron mobility transistor epitaxial wafer according to any one of claims 1 to 3, characterized in that: The growth temperature of the first AlN layer is 800-1000° C., the growth temperature of the second AlN layer is 1050-1250° C., and the thickness of the first AlN layer is 50-100 nm.

10. The method for improving the quality of a high electron mobility transistor epitaxial wafer according to any one of claims 1 to 3, characterized in that: The preparation method further comprises: Before sequentially growing the first AlN layer and the second AlN layer on the substrate, a layer of Al atoms is pre-spread on the substrate.

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