Method for preparing boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality

Abstract

The disclosure provides a boron-doped silicon substrate HEMT epitaxial wafer preparation method for improving crystal quality, and belongs to the technical field of semiconductor devices. A first AlN layer is first grown on the surface of the boron-doped silicon substrate, which can block the extension of impurities of the boron-doped silicon substrate. After the growth of the first AlN layer, chlorine gas is introduced into the reaction cavity to etch the first AlN layer. The chlorine gas can etch the surface of the first AlN layer to remove part of the defects extending to the surface of the first AlN layer, and can also release part of the stress accumulated in the first AlN layer. After the chlorine gas is introduced, the reaction cavity is subjected to air exchange treatment, and a second AlN layer is grown. The reduction of bottom layer defects and the improvement of crystal quality can reduce the possibility of leakage of the obtained HEMT epitaxial wafer and improve the reliability of the HEMT.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor devices, and particularly relates to a boron-doped silicon substrate HEMT epitaxial wafer preparation method for improving crystal quality. BACKGROUND

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

[0003] In the process of manufacturing the HEMT device, in order to improve the conductive capacity and reduce the pressure drop and energy consumption of the substrate part, a p-type boron-doped silicon substrate is mostly selected. The atomic radius of boron is smaller than that of silicon Si, and the diffusion of boron is very active under the action of high temperature, which will diffuse to the epitaxial layer, resulting in a decrease in the crystal quality of the epitaxial layer. During epitaxial growth, the concentration of boron atoms in the substrate decreases sharply, the atomic lattice changes sharply, lattice mismatch occurs, and the stress generated by the mismatch is easily released at the interface between the Si substrate and the epitaxial layer, accompanied by the epitaxial layer, so that the leakage current of the device increases, and the reliability of the obtained high electron mobility transistor is poor. SUMMARY

[0004] The embodiment of the present disclosure provides a boron-doped silicon substrate HEMT epitaxial wafer preparation method for improving crystal quality, which can improve the quality of the HEMT and reduce the possibility of HEMT leakage, and improve the reliability of the obtained HEMT. The technical scheme is as follows:

[0005] The embodiment of the present disclosure provides a high electron mobility transistor epitaxial wafer, and the boron-doped silicon substrate HEMT epitaxial wafer preparation method for improving crystal quality comprises:

[0006] A boron-doped silicon substrate is provided.

[0007] A first AlN layer is grown on the boron-doped silicon substrate.

[0008] Chlorine gas is introduced into a reaction cavity to etch the first AlN layer.

[0009] The reaction cavity is subjected to air exchange treatment.

[0010] A second AlN layer is grown on the first AlN layer.

[0011] An AlGaN buffer layer, an AlGaN high resistance layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer are sequentially grown on the surface of the second AlN layer.

[0012] Optionally, the flow rate of the chlorine gas introduced into the reaction cavity is 300-800 cmm.

[0013] Optionally, the time for which the first AlN layer is etched by introducing chlorine gas into the reaction cavity is 5-10 min.

[0014] Optionally, the first AlN layer is etched by introducing chlorine gas into the reaction cavity at a temperature of 1100-1200℃.

[0015] Optionally, the gas exchange treatment of the reaction cavity comprises:

[0016] Introducing hydrogen or nitrogen into the reaction cavity for the gas exchange treatment.

[0017] Optionally, the time for which hydrogen or nitrogen is introduced into the reaction cavity for the gas exchange treatment is 5-10 min.

[0018] Optionally, the flow rate of the hydrogen or nitrogen introduced into the reaction cavity is 2000-5000 sccm.

[0019] Optionally, the hydrogen or nitrogen is introduced into the reaction cavity for the gas exchange treatment at a pressure of 50-100 mbar and a temperature of 1100-1200℃.

[0020] Optionally, the temperature of the reaction cavity during the introduction of chlorine gas into the reaction cavity is equal to the temperature of the reaction cavity during the gas exchange treatment of the reaction cavity.

[0021] Optionally, the growth temperature of the first AlN layer is equal to the growth temperature of the second AlN layer.

[0022] The technical solutions provided by the embodiments of the present disclosure have the following beneficial effects:

[0023] The first AlN layer is grown on the surface of the boron-doped silicon substrate, which can block the extension of impurities of the boron-doped silicon substrate, reduce the impurities into the subsequent gallium nitride material, and improve the quality of the epitaxial material grown on the first AlN layer. After the first AlN layer is grown, the reaction chamber is supplied with chlorine gas to etch the first AlN layer. The chlorine gas can etch the surface of the first AlN layer to remove part of the defects extending to the surface of the first AlN layer, and can also release part of the stress accumulated in the first AlN layer, thereby reducing the number of defects extending to the subsequent epitaxial material and improving the crystal quality of the finally obtained HEMT epitaxial wafer. After the chlorine gas is supplied, the reaction chamber is subjected to a gas exchange treatment to avoid the influence of the chlorine gas on the subsequent epitaxial material to be grown, and to ensure the stable growth of the subsequent epitaxial material. After the gas exchange treatment, a second AlN layer is further grown on the etched first AlN layer. When the second AlN layer is grown on the etched surface of the first AlN layer, it can fill part of the defects on the surface of the first AlN layer and achieve good matching with the first AlN layer, so as to ensure that the obtained second AlN layer has good quality. The reduction of bottom defects and the improvement of crystal quality can reduce the possibility of leakage of the obtained HEMT epitaxial wafer and improve the reliability of the HEMT. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0025] Figure 1 is a preparation method flowchart of a boron-doped silicon substrate HEMT epitaxial wafer provided by the embodiments of the present disclosure for improving crystal quality;

[0026] Figure 2 is a structure schematic diagram of a high electron mobility transistor epitaxial wafer provided by the embodiments of the present disclosure for improving crystal quality;

[0027] Figure 3 is another preparation method flowchart of a boron-doped silicon substrate HEMT epitaxial wafer provided by the embodiments of the present disclosure for improving crystal quality;

[0028] Figure 4 is another structure schematic diagram of a high electron mobility transistor epitaxial wafer provided by the embodiments of the present disclosure for improving crystal quality. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in combination with the drawings.

[0030] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0031] Figure 1 This is a flowchart illustrating a method for fabricating a boron-doped silicon substrate HEMT epitaxial wafer to improve crystal quality, provided in an embodiment of this disclosure. (Refer to...) Figure 1 As can be seen, this disclosure provides a method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality. The method includes:

[0032] S101: Provides a boron-doped silicon substrate.

[0033] S102: The first AlN layer is grown on a boron-doped silicon substrate.

[0034] S103: Chlorine gas is introduced into the reaction chamber to corrode the first AlN layer.

[0035] S104: Perform air exchange treatment on the reaction chamber.

[0036] S105: A second AlN layer is grown on the first AlN layer.

[0037] S106: An AlGaN buffer layer, an AlGaN high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer are sequentially grown on the surface of the second AlN layer.

[0038] The first AlN layer is grown on the surface of the boron-doped silicon substrate, which can block the extension of impurities of the boron-doped silicon substrate, reduce the impurities into the subsequent gallium nitride material, and improve the quality of the epitaxial material grown on the first AlN layer. After the first AlN layer is grown, the chlorine gas is introduced into the reaction chamber to etch the first AlN layer. The chlorine gas can etch the surface of the first AlN layer to remove part of the defects extending to the surface of the first AlN layer, and can also release part of the stress accumulated in the first AlN layer, thereby reducing the number of defects extending to the subsequent epitaxial material and improving the crystal quality of the finally obtained HEMT epitaxial wafer. After the chlorine gas is introduced, the reaction chamber is purged to avoid the influence of the chlorine gas on the subsequent epitaxial material to be grown, and to ensure the stable growth of the subsequent epitaxial material. After the purging process, the second AlN layer is further grown on the etched first AlN layer. When the second AlN layer is grown on the etched surface of the first AlN layer, it can fill part of the defects on the surface of the first AlN layer and achieve good matching with the first AlN layer, so as to ensure that the quality of the obtained second AlN layer is good, the bottom defects are reduced, and the crystal quality is improved, thereby reducing the possibility of leakage of the obtained HEMT epitaxial wafer and improving the reliability of the HEMT.

[0039] It should be noted that the chlorine gas mainly relies on strong oxidation to etch the surface of the first AlN layer, and is relatively mild compared to plasma treatment. The chlorine gas can rely on chemical reaction to remove the relatively protruding defects on the surface of the first AlN layer and reduce the stress in the first AlN layer, without causing large defects on the surface of the first AlN layer. The chlorine gas can relatively stably improve the crystal quality of the first AlN layer and reduce the surface defects of the first AlN layer.

[0040] Optionally, in step S103, the flow rate of the chlorine gas introduced into the reaction chamber is 300-800 cmm.

[0041] The flow rate of the chlorine gas introduced into the reaction chamber is within the above range, which can achieve sufficient treatment of the surface of the first AlN layer, and can also ensure that there is enough chlorine gas to etch the surface of the first AlN layer for effective release of the stress accumulated in the first AlN layer.

[0042] Optionally, in step S103, the time for etching the first AlN layer by introducing chlorine gas into the reaction chamber is 5-10 min.

[0043] The sufficient release of stress in the first AlN layer can be ensured, and the chlorine gas will not excessively etch the first AlN layer.

[0044] Optionally, in step S103, the first AlN layer is etched by introducing chlorine gas into the reaction chamber at a temperature of 1100-1200°C.

[0045] It can ensure a stable reaction between chlorine and the first AlN layer, ensure the stable release of stress in the first AlN layer, and effectively remove any surface defects that may exist in the first AlN layer.

[0046] For example, chlorine gas is introduced into the reaction chamber at a pressure of 50 to 100 mbar to corrode the first AlN layer.

[0047] It can ensure a stable reaction between chlorine and the first AlN layer, ensure the stable release of stress in the first AlN layer, and effectively remove any surface defects that may exist in the first AlN layer.

[0048] In one implementation provided in this disclosure, the thickness variation of the first AlN layer before and after chlorine corrosion ranges from 150 to 200 nm. This can remove a significant number of defects.

[0049] Figure 2 This is a schematic diagram of the structure of a high electron mobility transistor epitaxial wafer for improving crystal quality, provided by an embodiment of this disclosure. Figure 2 The high electron mobility transistor epitaxial wafer shown can be employed Figure 1 The high electron mobility transistor epitaxial wafer fabrication method of the Chinese and European styles was obtained, with reference to Figure 2 It is known that the high electron mobility transistor epitaxial wafer for improving crystal quality includes a boron-doped silicon substrate 1 and a first AlN layer 2, a second AlN layer 3, an AlGaN buffer layer 4, an AlGaN high-resistivity layer 5, a GaN channel layer 6, an AlGaN barrier layer 7, and a GaN capping layer 8 sequentially stacked on the boron-doped silicon substrate 1. This ensures the basic functionality of the epitaxial wafer used to fabricate high electron mobility transistors.

[0050] Figure 3 This is a flowchart of another method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality, provided in this disclosure. (Refer to...) Figure 3 It can be seen that methods for preparing boron-doped silicon substrate HEMT epitaxial wafers to improve crystal quality also include:

[0051] S201: Provides a boron-doped silicon substrate.

[0052] Optionally, step S201 includes: treating the surface of the boron-doped silicon substrate for 5 to 10 minutes under H2 atmosphere, temperature conditions of 1000 to 1200°C, and pressure conditions of 50 to 150 mbar to remove impurities from the surface of the Si-based substrate.

[0053] For example, step S201 further includes: introducing an Al source of 50-200 sccm into the reaction chamber under temperature conditions of 1000-1100°C and pressure conditions of 40-70 mbar, so as to pre-deposit a layer of Al atoms on the surface of the boron-doped silicon substrate. This can promote the uniform growth of the AlN layer.

[0054] S202: growing a first AlN layer on the boron-doped silicon substrate.

[0055] Optionally, the growth temperature of the first AlN layer is 1100-1200℃, and the growth pressure of the first AlN layer is 40-70 mbar. A better quality first AlN layer can be obtained.

[0056] Illustratively, the growth thickness of the first AlN layer can be 150-200 nm.

[0057] The first AlN itself can effectively block impurities, and the thickness of the first AlN layer can also satisfy long-time etching of chlorine.

[0058] S203: etching the first AlN layer by introducing chlorine into the reaction chamber.

[0059] Step S203 can refer to step S103 shown in Figure 1 , and thus will not be described here again.

[0060] S204: performing gas replacement treatment on the reaction chamber.

[0061] Optionally, step S204 includes: introducing hydrogen or nitrogen into the reaction chamber to perform gas replacement treatment.

[0062] Hydrogen and nitrogen have small mass and fast moving rate, and will not cause damage to the epitaxial material. Using hydrogen and nitrogen to perform gas replacement treatment can effectively improve the gas replacement efficiency of the reaction chamber and improve the preparation efficiency of the high electron mobility transistor.

[0063] It should be noted that the gas replacement treatment on the reaction chamber refers to replacing the gas atmosphere in the reaction chamber with one or more gas atmospheres.

[0064] Optionally, the duration of introducing hydrogen or nitrogen into the reaction chamber to perform gas replacement treatment is 5-10 min.

[0065] The duration of introducing hydrogen or nitrogen into the reaction chamber to perform gas replacement treatment in the above range can ensure that the gas in the reaction chamber is fully replaced, ensure the purity of the reaction chamber before growing other epitaxial materials, and ensure the quality of the thickness epitaxial material growth.

[0066] Optionally, the flow rate of hydrogen or nitrogen introduced into the reaction chamber is 2000-5000 sccm.

[0067] The flow rate of hydrogen or nitrogen introduced into the reaction chamber in the above range can ensure rapid replacement of the atmosphere in the reaction chamber.

[0068] Optionally, the reaction cavity is ventilated with hydrogen or nitrogen at a pressure of 50-100 mbar and a temperature of 1100-1200℃. The replacement rate of the atmosphere in the reaction cavity can be ensured.

[0069] Optionally, the temperature of the reaction cavity during the process of ventilating the reaction cavity with chlorine is equal to the temperature of the reaction cavity during the process of ventilating the reaction cavity. The pressure and temperature in the reaction cavity do not need to be adjusted between the two steps, and the overall preparation efficiency of the high electron mobility transistor can be improved.

[0070] In an implementation provided in the present disclosure, the temperature of the reaction cavity during the process of ventilating the reaction cavity with chlorine, the temperature of the reaction cavity during the growth of the first AlN layer, and the temperature of the reaction cavity during the process of ventilating the reaction cavity are all equal. The stable implementation of the several steps can be ensured while the adjustment time of the growth parameters in the reaction cavity is saved, and the preparation efficiency of the high electron mobility transistor is improved.

[0071] S205: growing a second AlN layer on the first AlN layer.

[0072] Optionally, the growth temperature of the second AlN layer is 1100-1200℃, and the growth pressure of the second AlN layer is 40-70 mbar. A second AlN layer with good quality can be obtained.

[0073] Optionally, the growth temperature of the first AlN layer is equal to the growth temperature of the second AlN layer. The preparation efficiency of the high electron mobility transistor can be improved.

[0074] Exemplarily, the growth thickness of the second AlN layer can also be 150-200 nm.

[0075] The growth thickness of the second AlN layer is in the above range, which can ensure that the second AlN layer itself has good quality and can be well transitioned to other epitaxial materials grown subsequently.

[0076] S206: growing an AlGaN buffer layer on the second AlN layer.

[0077] Optionally, the growth conditions of the AlGaN buffer layer include a growth temperature of 1050-1250℃ and a pressure of 40-70 mbar. An AlGaN buffer layer with good quality can be obtained.

[0078] S207: growing an AlGaN high-resistance layer on the AlGaN buffer layer.

[0079] The AlGaN high resistance layer is grown on the AlGaN buffer layer, so that the lattice mismatch between the AlGaN buffer layer and the AlGaN high resistance layer can be effectively reduced, and the crystal quality of the obtained AlGaN high resistance layer is improved. The quality of the AlGaN high resistance layer is guaranteed, and the quality of other epitaxial materials grown on the AlGaN high resistance layer can be further improved.

[0080] Exemplarily, the growth temperature of the AlGaN high resistance layer can be 1000-1200℃, and the growth pressure of the AlGaN high resistance layer is 40-70mbar.

[0081] The growth temperature and the growth pressure of the AlGaN high resistance layer are respectively within the above ranges, so that the growth quality of the obtained AlGaN high resistance layer can be effectively improved.

[0082] Optionally, the growth thickness of the AlGaN high resistance layer is 1.0-2.0 microns. The growth quality of the AlGaN high resistance layer itself can be guaranteed, and the purpose of high resistance can be effectively achieved.

[0083] Optionally, the AlGaN high resistance layer is doped with carbon, and the doping concentration of the carbon element is 10 19 cm -3 -10 20 cm -3 .

[0084] The AlGaN high resistance layer doped with carbon can improve the high resistance effect of the AlGaN high resistance layer, and the doping concentration of the carbon element within the above range can also guarantee the quality of the AlGaN high resistance layer itself.

[0085] S208: Growing a GaN channel layer on the AlGaN high resistance layer.

[0086] Optionally, the growth conditions of the GaN channel layer include: the growth temperature is 1050-1150℃, and the pressure is 150-250mbar. A GaN channel layer with good quality can be obtained.

[0087] Exemplarily, the thickness of the GaN channel layer is between 1.0-1.5 microns. The quality of the finally obtained HEMT epitaxial wafer is improved. The quality of the obtained GaN channel layer is good.

[0088] S209: Growing an AlN insertion layer on the GaN channel layer.

[0089] Optionally, the growth temperature of the AlN insertion layer is 1050-1150℃, and the growth pressure of the AlN insertion layer is 40-70mbar. A GaN channel layer with good quality can be obtained.

[0090] S210: Growing an AlGaN barrier layer on the AlN insertion layer.

[0091] Optionally, the growth temperature of the AlGaN barrier layer is 1050-1150℃, and the growth pressure of the AlGaN barrier layer is 40-70mbar. The quality of the obtained AlGaN barrier layer is better.

[0092] In an implementation provided by the present disclosure, the growth temperature of the AlGaN barrier layer can be 1020℃. The present disclosure does not limit this.

[0093] S211: growing a GaN cap layer on the AlGaN barrier layer.

[0094] Optionally, the growth temperature of the GaN cap layer is 1050-1150℃, and the growth pressure of the AlGaN barrier layer is 40-70mbar. The quality of the obtained GaN cap layer is better.

[0095] It should be noted that in the embodiments of the present disclosure, the growth method of the LED is realized by using Veeco K 465i or C4 or RB MOCVD (Metal Organic Chemical Vapor Deposition) equipment. High-purity H2 (hydrogen) or high-purity N2 (nitrogen) or a mixed gas of high-purity H2 and high-purity N2 is used as a carrier gas, high-purity NH3 is used as an N source, trimethylgallium (TMGa) and triethylgallium (TEGa) are used as gallium sources, trimethylindium (TMIn) is used as an indium source, silane (SiH4) is used as an N-type dopant, trimethylaluminum (TMAl) is used as an aluminum source, and dimethylmagnesium (CP2Mg) is used as a P-type dopant, ferrocene (Cp2Fe) is used as a precursor of an iron (Fe) source. Carbon tetrabromide (CBr4) is used as a precursor of a carbon (C) source, and Cl2 is used as an etching gas.

[0096] Figure 4 is another structure diagram of a high electron mobility transistor epitaxial wafer with improved crystal quality provided by the embodiments of the present disclosure, referring to Figure 4 It can be known that the high electron mobility transistor epitaxial wafer can include a boron-doped silicon substrate 1 and a first AlN layer 2, a second AlN layer 3, an AlGaN buffer layer 4, an AlGaN high-resistance layer 5, a GaN channel layer 6, an AlN insertion layer 9, an AlGaN barrier layer 7, and a GaN cap layer 8 which are sequentially stacked on the boron-doped silicon substrate 1.

[0097] Optionally, the thicknesses of the first AlN layer 2 and the second AlN layer 3 are both 150-200nm. The quality of the first AlN layer 2 and the second AlN layer 3 can be guaranteed to be better, thereby providing a good growth foundation for the HEMT epitaxial wafer.

[0098] Exemplarily, the thickness of the AlGaN buffer layer 4 is 1-1.5 microns. The quality of the obtained AlGaN buffer layer 4 is good.

[0099] Optionally, the thickness of the GaN channel layer 6 can be 100-400 nm.

[0100] The thickness of the GaN channel layer 6 is appropriate, and the cost is reasonable while the quality of the high electron mobility transistor epitaxial wafer can be effectively improved.

[0101] In an implementation manner provided by the present disclosure, the thickness of the GaN channel layer 6 can be 400 nm. The present disclosure does not limit this.

[0102] Figure 4 The thickness of the GaN channel layer 6 is appropriate, and the cost is reasonable while the quality of the high electron mobility transistor epitaxial wafer can be effectively improved. Figure 2 The structure of the middle HEMT epitaxial wafer adds the AlN insertion layer 9, on the one hand, the negative influence caused by the lattice mismatch of the bottom layer is smaller. On the other hand, the interface between the AlN insertion layer 9 and the GaN channel layer 6, and the interface between the AlN insertion layer 9 and the AlGaN barrier layer 7 form a two-dimensional electron gas. Through the accumulation of the carriers at the interface by the two-dimensional electron gas, the use effect of the high electron mobility transistor epitaxial wafer can be ensured.

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

[0104] The thickness of the AlN insertion layer 9 in the above range can effectively form a two-dimensional electron gas, and the cost will not be increased too much.

[0105] In an implementation manner provided by the present disclosure, the thickness of the AlN insertion layer 9 can be 2 nm. The present disclosure does not limit this.

[0106] Optionally, the thickness of the AlGaN barrier layer 7 can be 15-40 nm. The quality of the high electron mobility transistor epitaxial wafer can be ensured.

[0107] In an implementation manner provided by the present disclosure, the thickness of the AlGaN barrier layer 7 can be 100 nm. The present disclosure does not limit this.

[0108] Exemplarily, the GaN cap layer 8 can be a P-type GaN layer. It is convenient to prepare and obtain.

[0109] Optionally, the thickness of the GaN cap layer 8 is 3-10 nm. The quality of the obtained GaN cap layer 8 as a whole is good.

[0110] Exemplarily, the impurity in the GaN cap layer 8 is Mg. It is convenient to prepare and obtain.

[0111] It should be noted that, Figure 4In other implementation manners provided by the present disclosure, in addition to the implementation manner of the high electron mobility transistor epitaxial wafer provided by the embodiments of the present disclosure, the high electron mobility transistor epitaxial wafer can also be other forms of high electron mobility transistor epitaxial wafer including a reflection layer, and the present disclosure does not limit this.

[0112] The above is not intended to limit the present disclosure in any form, although the present disclosure has been disclosed as above through embodiments, however, it is not intended to limit the present disclosure, any person skilled in the art, without departing from the technical solution range of the present disclosure, can make some changes or modifications to the above disclosed technical content as equivalent embodiments, as long as it does not deviate from the technical solution of the present disclosure, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present disclosure, still belongs to the range of the technical solution of the present disclosure.

Claims

1. A method for preparing boron-doped silicon substrate HEMT epitaxial wafers with improved crystal quality, characterized in that, The method for preparing boron-doped silicon substrate HEMT epitaxial wafers with improved crystal quality includes: Provide a boron-doped silicon substrate; A first AlN layer is grown on the boron-doped silicon substrate; Chlorine gas is introduced into the reaction chamber to etch the first AlN layer, thereby removing some defects that extend to the surface of the first AlN layer and releasing some of the stress accumulated inside the first AlN layer, reducing the number of defects that would extend into the subsequent epitaxial material. The reaction chamber is ventilated. A second AlN layer is grown on the first AlN layer; An AlGaN buffer layer, an AlGaN high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer are sequentially grown on the surface of the second AlN layer.

2. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to claim 1, characterized in that, The flow rate of chlorine gas introduced into the reaction chamber is 300~800 sccm.

3. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to claim 2, characterized in that, The time for introducing chlorine gas into the reaction chamber to corrode the first AlN layer is 5-10 minutes.

4. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to any one of claims 1 to 3, characterized in that, At a temperature of 1100~1200℃, chlorine gas is introduced into the reaction chamber to corrode the first AlN layer.

5. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to any one of claims 1 to 3, characterized in that, The process of ventilating the reaction chamber includes: Hydrogen or nitrogen gas is introduced into the reaction chamber for gas exchange.

6. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to claim 5, characterized in that, The time for purging the reaction chamber with hydrogen or nitrogen gas is 5 to 10 minutes.

7. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to claim 5, characterized in that, The flow rate of hydrogen or nitrogen gas introduced into the reaction chamber is 2000~5000 sccm.

8. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to claim 7, characterized in that, Hydrogen or nitrogen is introduced into the reaction chamber at a pressure of 50-100 mbar and a temperature of 1100-1200°C for gas exchange.

9. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to claim 8, characterized in that, The temperature of the reaction chamber during the process of introducing chlorine gas is the same as the temperature of the reaction chamber during the process of ventilating the reaction chamber.

10. The method for preparing a boron-doped silicon substrate HEMT epitaxial wafer with improved crystal quality according to any one of claims 1 to 3, characterized in that, The growth temperatures of the first AlN layer and the second AlN layer are the same.

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