Gallium nitride high electron mobility transistor epitaxial wafer and its manufacturing method

Abstract

The present application discloses a gallium nitride high electron mobility transistor epitaxial wafer and a preparation method thereof. The method includes: epitaxially growing a layer of NbNx sacrificial layer and a layer of GaN HEMT epitaxial layer on a substrate in sequence, where the NbNx sacrificial layer is used for GaN HEMT epitaxial lift-off; taking the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, performing multiple repeated epitaxial growths on the substrate, and finally forming a first epitaxial structure with multiple repeated stacks on the substrate; using the first epitaxial structure as a first GaN HEMT epitaxial wafer. It can be seen that the first GaN HEMT epitaxial wafer can achieve the effect of growing once and being used multiple times, so as to produce several times the number of GaN HEMT devices, thereby facilitating a significant reduction in the cost of GaN HEMT device products.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor device processes, and particularly to a gallium nitride high electron mobility transistor epitaxial wafer and a preparation method thereof. Background Art

[0002] Gallium nitride (GaN) high electron mobility transistors (HEMTs) generally need to be fabricated on GaN HEMT epitaxial wafers of substrates. However, the price of GaN HEMT epitaxial wafers is usually relatively expensive, making the cost of GaN HEMT epitaxial wafers account for a major part in the overall cost of GaN HEMT device products. Therefore, in order to reduce the cost of GaN HEMT device products, it is necessary to fundamentally reduce the cost of GaN HEMT epitaxial wafers. Summary of the Invention

[0003] This application provides a gallium nitride high electron mobility transistor epitaxial wafer and a preparation method thereof, in order to reduce the cost of GaN HEMT epitaxial wafers.

[0004] In a first aspect, a preparation method of a gallium nitride high electron mobility transistor epitaxial wafer according to this application includes:

[0005] On a substrate, a niobium nitride NbNx sacrificial layer and a gallium nitride high electron mobility transistor GaN HEMT epitaxial layer are sequentially epitaxially grown. The NbNx sacrificial layer is used for GaN HEMT epitaxial lift-off.

[0006] Taking the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, multiple repeated epitaxial growths are performed on the substrate, and finally a first epitaxial structure with multiple repeated stacked layers is formed on the substrate.

[0007] Taking the first epitaxial structure as a first GaN HEMT epitaxial wafer; wherein, the first GaN HEMT epitaxial wafer is used to fabricate GaN HEMT devices by sequentially using each GaN HEMT epitaxial layer from the topmost layer to the bottommost layer, and then using the NbNx sacrificial layer for epitaxial lift-off until all the GaN HEMT epitaxial layers are used and lifted off, and finally recycling the substrate.

[0008] It can be seen that the first GaN HEMT epitaxial wafer can achieve the effect of one-time growth and multiple uses, so that under the same wafer size, compared with other epitaxial wafers prepared by conventional technologies, the first GaN HEMT epitaxial wafer can produce several times the number of GaN HEMT devices, which is beneficial to significantly reducing the cost of GaN HEMT device products.

[0009] Secondly, the GaN HEMT epitaxial layer grown on the substrate has better quality and characteristics, a higher thickness, and fewer defects, which is conducive to improving the performance, yield, and good rate of the fabricated GaN HEMT devices.

[0010] Thirdly, the NbNx sacrificial layer minimizes the damage caused by peeling off the GaN HEMT epitaxial layer, reducing the damage to the fabricated GaN HEMT devices due to the peeling of the GaN HEMT epitaxial layer.

[0011] Finally, after all the GaN HEMT epitaxial layers have been used and peeled off, the substrate is recycled to facilitate the subsequent epitaxial growth of a new epitaxial structure on the substrate, which is conducive to realizing the recycling of the substrate and further reducing the cost of GaN HEMT epitaxial wafers and GaN HEMT devices.

[0012] In a second aspect, a gallium nitride high electron mobility transistor epitaxial wafer according to the present application is used to fabricate GaN HEMT devices by sequentially using each gallium nitride high electron mobility transistor GaN HEMT epitaxial layer from the topmost layer to the bottommost layer, and then using a niobium nitride NbNx sacrificial layer for epitaxial peeling until all the GaN HEMT epitaxial layers have been used and peeled off, and finally recycling the substrate; the epitaxial wafer includes:

[0013] On the substrate, there are multiple repetitively stacked first epitaxial structures, which are obtained by repeatedly growing epitaxially on the substrate with one layer of the NbNx sacrificial layer and one layer of the GaN HEMT epitaxial layer as a whole, and the NbNx sacrificial layer is used for GaN HEMT epitaxial peeling.

[0014] The beneficial effects brought by the technical solution of the second aspect can refer to the technical effects brought by the technical solution of the first aspect, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below.

[0016] Figure 1 It is a schematic structural diagram of an epitaxial structure of a GaN HEMT provided by the present application;

[0017] Figure 2 It is a schematic structural diagram of a GaN HEMT epitaxial layer provided by the present application;

[0018] Figure 3 It is a schematic structural diagram of another epitaxial structure of a GaN HEMT provided by the present application;

[0019] Figure 4 is a schematic structural diagram of another epitaxial structure of a GaN HEMT provided by the present application;

[0020] Figure 5 is a schematic structural diagram of a structure after preparing an etching and peeling groove on a GaN HEMT epitaxial wafer provided by the present application;

[0021] Figure 6 is a schematic structural diagram of an epitaxial structure when etching the exposed NbNx sacrificial layer with XeF2 gas provided by the present application;

[0022] Figure 7 is a schematic structural diagram of an epitaxial structure when peeling off the device structure layer and the GaN HEMT epitaxial layer provided by the present application;

[0023] Figure 8 is a schematic structural diagram of another substrate when transferring the peeled device structure layer and GaN HEMT epitaxial layer to another substrate provided by the present application;

[0024] Figure 9 is a schematic flow diagram of a method for preparing a GaN HEMT epitaxial wafer provided by the present application;

[0025] Figure 10 is a schematic structural diagram of a GaN HEMT epitaxial wafer provided by the present application;

[0026] Figure 11 is a schematic structural diagram of another GaN HEMT epitaxial wafer provided by the present application. Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0028] In the description, claims, and the above-mentioned drawings of this application, terms such as "first", "second", etc. are used to distinguish different objects, rather than to describe a specific order. The mention of "embodiment" in this text means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various positions in the description does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. Additionally, in the embodiments of this application, "placed on", "placed", or "positioned" is the same as "deposited", which is a layer structure deposited by thin film deposition technology in semiconductor manufacturing processes.

[0029] In the drawings provided in the embodiments of this application, the cross-sectional views of the shown device structures may not be enlarged locally in accordance with a general ratio, and the schematic diagrams are only for illustrative purposes and should not limit the scope claimed in this application. At the same time, the thicknesses of the various layers in the cross-sectional views of the shown device structures are only for illustration and need to be determined according to specific semiconductor processes, and do not constitute a limitation on the embodiments of this application. Additionally, in the actual manufacturing process of radio frequency semiconductor devices, the fabricated radio frequency semiconductor devices should include three-dimensional spatial dimensions of length, width, and depth.

[0030] The expression "at least one (item)" or its similar expressions in the embodiments of this application refers to any combination of these items, including any combination of single items or plural items, and means one or more, where multiple means two or more. For example, at least one (item) of a, b, or c can represent the following seven situations: a, b, c, a and b, a and c, b and c, a, b, and c. Each of a, b, and c can be an element or a set containing one or more elements.

[0031] 1. Preparation of GaN HEMT Epitaxial Wafers

[0032]

Description

[0033] In order to reduce the cost of GaN HEMT device products, it is necessary to fundamentally reduce the cost of GaN HEMT epitaxial wafers. Based on this, this application proposes a method for preparing GaN HEMT epitaxial wafers, which is specifically as follows:

[0034] First, a niobium nitride (NbNx) sacrificial layer is epitaxially grown on a substrate, then a GaN HEMT epitaxial layer is epitaxially grown thereon, and then, with the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, multiple repeated epitaxial growths are performed on the substrate, and finally an epitaxial structure with multiple repeated stacked layers is formed on the substrate, thereby preparing a GaN HEMT epitaxial wafer.

[0035] In this way, since the GaN HEMT epitaxial wafer includes multiple repeated and overlapping NbNx sacrificial layers and GaN HEMT epitaxial layers grown epitaxially from bottom to top, and the GaN HEMT epitaxial layers are used to fabricate GaN HEMT devices, and the NbNx sacrificial layers are used for GaN HEMT epitaxial lift-off, therefore, in this application, each GaN HEMT epitaxial layer can be used in sequence from the topmost layer to the bottommost layer to fabricate GaN HEMT devices, and then the NbNx sacrificial layer is used for epitaxial lift-off until all GaN HEMT epitaxial layers are used and lifted off.

[0036] It can be seen that in this application, the GaN HEMT epitaxial wafer is fabricated by means of multiple repeated epitaxial growths, so that the GaN HEMT epitaxial wafer can achieve the effect of one-time growth and multiple uses. In the same wafer size, compared with other epitaxial wafers fabricated by conventional techniques, several times as many GaN HEMT devices can be made from this GaN HEMT epitaxial wafer, which is conducive to significantly reducing the cost of GaN HEMT device products.

[0037] Secondly, the GaN HEMT epitaxial layers grown on the substrate have better quality and characteristics, higher thickness, and fewer defects, which is conducive to improving the performance, yield, and good rate of the fabricated GaN HEMT devices.

[0038] Thirdly, the NbNx sacrificial layer minimizes the damage caused by lifting off the GaN HEMT epitaxial layer, reducing the damage to the fabricated GaN HEMT devices due to lifting off the GaN HEMT epitaxial layer. At the same time, the lifted-off GaN HEMT epitaxial layer can be heterogeneously integrated with other semiconductor devices or circuits after transfer, so that different semiconductor materials can play their respective optimal characteristics, obtaining chips or components with better performance and realizing smaller and stronger chips or components.

[0039] Finally, after all GaN HEMT epitaxial layers are used and lifted off, this application can recycle the substrate for subsequent epitaxial growth of a new epitaxial structure on the substrate, which is conducive to realizing the cyclic reuse of the substrate and further reducing the cost of GaN HEMT epitaxial wafers and GaN HEMT devices.

[0040]

Specific Process Flow

[0041] Combined with the above content, the specific process flow for fabricating the GaN HEMT epitaxial wafer is introduced as follows:

[0042] Step 1: Select a substrate

[0043] The substrate is the carrier for device epitaxy and has a great impact on radio frequency performance. The selection of the substrate needs to comprehensively consider factors such as cost, lattice matching degree with the epitaxial layer, thermal conductivity, and the difficulty of obtaining large-size wafers.

[0044] Optionally, the substrate includes a GaN or SiC substrate.

[0045] It should be noted that, in order to ensure performance, the dielectric substrate material of the substrate selected in this application is GaN or SiC. In this way, growing a GaN HEMT epitaxial layer on a GaN or SiC substrate can make the grown GaN HEMT epitaxial layer have better quality and characteristics, higher thickness, and fewer defects, thus being beneficial to improving the performance, yield, and good rate of the prepared GaN HEMT devices.

[0046] Step 2: Sequentially grow an NbNx sacrificial layer and a GaN HEMT epitaxial layer

[0047] As Figure 1 shown, on the substrate, an NbNx sacrificial layer and a GaN HEMT epitaxial layer are sequentially grown by using an epitaxial thin film preparation process.

[0048] Since the lattice constant of NbNx is between that of GaN and SiC, the NbNx sacrificial layer can have good lattice matching with GaN and SiC, so as to be able to grow a GaN HEMT epitaxial layer with excellent crystal quality and greater thickness on a GaN or SiC substrate.

[0049] Optionally, the purpose of preparing the NbNx sacrificial layer can be for GaN HEMT epitaxial lift-off (such as lifting off the GaN HEMT epitaxial layer, lifting off the GaN HEMT device structure layer, etc.), or for recycling the substrate after all GaN HEMT epitaxial layers have been used and lifted off.

[0050] Optionally, the epitaxial thin film preparation process can include Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), etc. Among them, CVD can include Metal Organic CVD (MOCVD), Plasma-Enhanced CVD (PECVD), etc.; PVD can include Molecular Beam Epitaxy (MBE), Pulsed Laser Deposition (PLD), Magnetron Sputter, etc.

[0051] For example, MBE is used to epitaxially grow the NbNx sacrificial layer, and MBE or MOCVD is used to epitaxially grow the GaN HEMT epitaxial layer.

[0052] Optionally, the GaN HEMT epitaxial layer includes at least one of the following: a nucleation layer, a buffer layer, a high-resistance layer, a channel layer, a barrier layer, and a cap layer. Among them, the nucleation layer, the buffer layer, the high-resistance layer, the channel layer, the barrier layer, and the cap layer are deposited in sequence from bottom to top.

[0053] For the nucleation layer, due to the lattice mismatch problem between the substrate and the buffer layer, such as the lattice mismatch rate between SiC and GaN being 3.5%, the present application can introduce a nucleation layer with a certain thickness (such as nanoscale) to reduce the interfacial tension caused by this mismatch. Among them, the nucleation layer plays an important role in reducing current collapse caused by interfacial mismatch, defects or trap effects, reducing static current leakage and radio frequency conduction, and improving radio frequency performance. Among them, the material of the nucleation layer can include at least one of aluminum gallium nitride (AlGaN), aluminum nitride (AlN), GaN, etc.

[0054] For the buffer layer, the buffer layer has high resistivity, and its thickness can usually be in the micron scale. It is used to form a two-dimensional electron gas (2DEG) and reduce the background carrier concentration to reduce the drain current collapse caused by the buffer layer trap effect. Among them, the material of the buffer layer can include GaN, AlGaN, etc.

[0055] For the high-resistance layer, the high-resistance layer can have high-resistance characteristics to reduce device leakage and improve the breakdown characteristics and frequency characteristics of the GaN HEMT. Among them, the material of the high-resistance layer can include GaN, etc.

[0056] For the channel layer, the channel layer can provide an electron transport channel and control the magnitude and nature of the current, directly affecting the function and performance of the device. Among them, the material of the channel layer can include GaN, etc.

[0057] For the barrier layer, the barrier layer can provide a certain barrier height for the gate Schottky contact. Due to the influence of surface traps, for a thinner barrier layer, the electric field strength is greater, the current collapse is more serious, and the saturated output power is lower. However, a thicker barrier layer will increase the parasitic effect and reduce the small-signal gain characteristics. Among them, the material of the barrier layer can include at least one of AlGaN, AlN, indium aluminum nitride (InAlN), etc.

[0058] For the cap layer, the cap layer plays an important role in reducing drain current collapse and maintaining the 2DEG generated by the polarization characteristics. At the same time, it can also reduce the gate leakage current, enhance the source and drain ohmic contacts and breakdown voltage. Among them, the material of the cap layer can include GaN, etc.

[0059] For example, such asFigure 2 As shown, the GaN HEMT epitaxial layer includes an AlN nucleation layer, an AlGaN buffer layer, a GaN high-resistance layer, a GaN channel layer, an AlGaN barrier layer, and a GaN cap layer deposited in sequence from bottom to top.

[0060] Step 3: Taking the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, perform multiple repeated epitaxial growths on the substrate, and finally form a first epitaxial structure with multiple repeated stacks on the substrate.

[0061] In this way, the present application prepares a GaN HEMT epitaxial wafer by means of multiple repeated epitaxial growths, enabling the GaN HEMT epitaxial wafer to achieve the effect of single growth and multiple uses, so that several times the number of GaN HEMT devices can be fabricated from the GaN HEMT epitaxial wafer compared to other epitaxial wafers prepared by conventional techniques of the same size, thereby contributing to a significant reduction in the cost of GaN HEMT device products.

[0062] As Figure 3 shown, repeat the epitaxial growth of the NbNx sacrificial layer and the GaN HEMT epitaxial layer on the substrate to form a first epitaxial structure with multiple repeated stacks, and finally use the first epitaxial structure as the first GaN HEMT epitaxial wafer, thereby preparing a GaN HEMT epitaxial wafer.

[0063] Optionally, the number of repeated epitaxial growths is 1 to 9 times. That is, taking the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, repeat the epitaxial growth of this whole 1 to 9 times. In this way, finally 2 to 10 NbNx sacrificial layers and GaN HEMT epitaxial layers can be obtained.

[0064] Of course, the present application is not limited to the number of repeated epitaxial growths being 1 to 9 times, and it can also be other values, which mainly depends on the process preparation capabilities and requirements.

[0065] Step 4: Use each GaN HEMT epitaxial layer in sequence from the topmost layer to the bottommost layer to fabricate GaN HEMT devices to form a device structure layer.

[0066] After the first GaN HEMT epitaxial wafer is fabricated, each GaN HEMT epitaxial layer can be used in sequence from the topmost layer to the bottommost layer to fabricate GaN HEMT devices. Among them, after the front process of the GaN HEMT device is completed each time, a device structure layer is formed on the GaN HEMT epitaxial layer, and the GaN HEMT device is composed of the GaN HEMT epitaxial layer and the device structure layer.

[0067] For example, as Figure 4As shown, the current GaN HEMT device is fabricated using the current GaN HEMT epitaxial layer. After the front-end process of the current GaN HEMT device is completed, the current device structure layer is formed on the current GaN HEMT epitaxial layer, and the current GaN HEMT device is composed of the current GaN HEMT epitaxial layer and the current device structure layer.

[0068] Optionally, during the process of fabricating a GaN HEMT device using a GaN HEMT epitaxial layer each time, the etching depth does not exceed the bottommost part of the NbNx layer beneath the used GaN HEMT epitaxial layer.

[0069] This is because, taking the use of the current GaN HEMT epitaxial layer as an example, the etching depth during the fabrication process of the current GaN HEMT device does not exceed the bottommost part of the current NbNx sacrificial layer. In this way, it is possible to avoid damaging the GaN HEMT epitaxial layer beneath the current NbNx sacrificial layer, ensuring that the subsequent fabrication of the GaN HEMT device is not affected by the previous fabrication processes.

[0070] Step 5: Use an etching process to etch the device structure layer and the GaN HEMT epitaxial layer to expose the NbNx sacrificial layer

[0071] In order to perform epitaxial lift-off on the GaN HEMT device that has completed the front-end process, it is necessary to first use an etching process to etch the device structure layer and the GaN HEMT epitaxial layer to expose the NbNx sacrificial layer. This makes it convenient to etch the exposed NbNx sacrificial layer for GaN HEMT epitaxial lift-off.

[0072] For example, as Figure 5 shown, use an etching process to etch the device structure layer and the GaN HEMT epitaxial layer to prepare an etching and lift-off groove that penetrates the device structure layer and the GaN HEMT epitaxial layer to expose the NbNx sacrificial layer. Among them, this etching and lift-off groove can be used to separately etch and lift off between GaN HEMT devices.

[0073] Taking the completion of the front-end process of the current GaN HEMT device as an example, use an etching process to prepare the current etching and lift-off groove that penetrates the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer, and this current etching and lift-off groove can be used to separately etch and lift off the current GaN HEMT device.

[0074] Step 6: Use an etching process to remove the exposed NbNx sacrificial layer, causing the device structure layer and the GaN HEMT epitaxial layer to be lifted off from the first GaN HEMT epitaxial wafer

[0075] In this way, the present application can strip the device structure layer and the GaN HEMT epitaxial layer.

[0076] Optionally, the etching process may include etching the exposed NbNx sacrificial layer with XeF2 gas to remove the NbNx sacrificial layer, as Figure 6 shown. In this way, the device structure layer and the GaN HEMT epitaxial layer are peeled off from the first GaN HEMT epitaxial wafer, as Figure 7 shown.

[0077] Step 7: Use a flexible tape or a transfer carrier to paste the peeled device structure layer and GaN HEMT epitaxial layer, and transfer them to other required substrates.

[0078] It should be noted that after the device structure layer and the GaN HEMT epitaxial layer are peeled off, the peeled device structure layer and GaN HEMT epitaxial layer are fished out, dried, and then transferred.

[0079] It can be seen that the present application can transfer the peeled device structure layer and GaN HEMT epitaxial layer, so that the peeled GaN HEMT epitaxial layer can be hetero-integrated with other semiconductor devices or circuits after transfer, so that different semiconductor materials can play their respective optimal characteristics, obtain chips or components with better performance, and realize smaller and stronger chips or components.

[0080] For example, as Figure 8 shown, the peeled device structure layer and GaN HEMT epitaxial layer are transferred to other substrates.

[0081] Optionally, the flexible tape may include an ultraviolet (UV) tape.

[0082] Optionally, the transfer carrier may include a quartz glass sheet, a sapphire sheet, etc.

[0083] Optionally, other substrates may include a diamond substrate, an AlN substrate, a SiC substrate, glass, or a wafer containing devices / circuits, etc.

[0084] Step 8: After the remaining first GaN HEMT epitaxial wafer is cleaned, it is put back into use until all GaN HEMT epitaxial layers are used and peeled off, and finally the substrate is exposed.

[0085] For example, clean the surface of the first GaN HEMT epitaxial wafer by etching, and continue to use the remaining GaN HEMT epitaxial layers in the first GaN HEMT epitaxial wafer to fabricate the remaining GaN HEMT devices until all GaN HEMT epitaxial layers are used and peeled off, and finally the substrate is exposed.

[0086] Step 9: Recycle the substrate and perform a new epitaxial growth after surface cleaning.

[0087] In this way, after all the GaN HEMT epitaxial layers are used and peeled off, the present application can recycle the substrate so as to epitaxially grow a new epitaxial structure on the substrate subsequently, which is conducive to realizing the recycling of the substrate and further reducing the costs of the GaN HEMT epitaxial wafer and the GaN HEMT device.

[0088] For example, recycle the substrate and continue to use the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, or use other sacrificial layers and other GaN epitaxial layers as a whole to perform multiple repeated epitaxial growths on the substrate to form a second epitaxial structure with multiple repeated stacked layers, so as to use the second epitaxial structure as a second GaN HEMT epitaxial wafer, thereby preparing a new GaN HEMT epitaxial wafer.

[0089] Among them, the other sacrificial layer can be understood as a sacrificial layer whose material is not NbNx; for example, the other sacrificial layer is an indium gallium nitride (InGaN) sacrificial layer or a highly doped N-type gallium nitride (n+GaN) sacrificial layer, etc.; the other GaN epitaxial layer can be understood as an epitaxial layer having a different film layer from the GaN HEMT epitaxial layer.

[0090] It should be noted that when using the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole to perform multiple repeated epitaxial growths again, the number of repeated epitaxial growths at this time can be the same as that of the previous time or different from that of the previous time, which is determined by the preparation process and requirements, and no specific limitation is made thereto.

[0091] 2. Example description of a method for preparing a GaN HEMT epitaxial wafer

[0092] Combined with the above content, the following is an example description of the GaN HEMT epitaxial wafer preparation method of the present application, as Figure 9 shown. In Figure 9 , the GaN HEMT epitaxial wafer preparation method may include the following steps:

[0093] S910: Epitaxially grow a layer of NbNx sacrificial layer and a layer of GaN HEMT epitaxial layer on the substrate in sequence, and the NbNx sacrificial layer is used for GaN HEMT epitaxial peeling.

[0094] S920: Use the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole to perform multiple repeated epitaxial growths on the substrate, and finally form a first epitaxial structure with multiple repeated stacked layers on the substrate.

[0095] S930. Use the first epitaxial structure as the first GaN HEMT epitaxial wafer. Among them, the first GaN HEMT epitaxial wafer is used to prepare GaN HEMT devices by sequentially using each GaN HEMT epitaxial layer from the topmost layer to the bottommost layer, and then using the NbNx sacrificial layer for epitaxial lift-off until all GaN HEMT epitaxial layers are used and lifted off, and finally recovering the substrate.

[0096] It can be seen that the first GaN HEMT epitaxial wafer can achieve the effect of one-time growth and multiple uses. Under the same wafer size, compared with other epitaxial wafers prepared by conventional technologies, the first GaN HEMT epitaxial wafer can fabricate several times the number of GaN HEMT devices, which is conducive to significantly reducing the cost of GaN HEMT device products.

[0097] Secondly, the GaN HEMT epitaxial layers grown on the substrate have better quality and characteristics, higher thickness, and fewer defects, which is conducive to improving the performance, yield, and good rate of the fabricated GaN HEMT devices.

[0098] Thirdly, the NbNx sacrificial layer minimizes the damage caused by lifting off the GaN HEMT epitaxial layers and reduces the damage to the fabricated GaN HEMT devices due to the lift-off of the GaN HEMT epitaxial layers.

[0099] Finally, after all GaN HEMT epitaxial layers are used and lifted off, the substrate is recovered to facilitate subsequent epitaxial growth of a new epitaxial structure on the substrate, which is conducive to realizing the recycling of the substrate and further reducing the cost of GaN HEMT epitaxial wafers and GaN HEMT devices.

[0100] Optionally, the GaN HEMT epitaxial layer includes at least one of the following:

[0101] Nucleation layer, buffer layer, high-resistance layer, channel layer, barrier layer, cap layer;

[0102] The nucleation layer, buffer layer, high-resistance layer, channel layer, barrier layer, and cap layer are deposited in sequence from bottom to top.

[0103] Optionally, the number of times of repeated epitaxial growth is 1 to 9 times.

[0104] Optionally, after obtaining the first GaN HEMT epitaxial wafer, the method further includes the following steps:

[0105] Use the current GaN HEMT epitaxial layer in the first GaN HEMT epitaxial wafer to prepare the current GaN HEMT device;

[0106] After completing the front process of the current GaN HEMT device, a current device structure layer is formed on the current GaN HEMT epitaxial layer, and the current GaN HEMT device is composed of the current GaN HEMT epitaxial layer and the current device structure layer;

[0107] An etching process is used to etch the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer, and the current NbNx sacrificial layer is in the next layer of the current GaN HEMT epitaxial layer in the first GaN HEMT epitaxial wafer;

[0108] A corrosion process is used to remove the current NbNx sacrificial layer, so that the current device structure layer and the current GaN HEMT epitaxial layer are peeled off from the first GaN HEMT epitaxial wafer.

[0109] Optionally, the etching depth in the preparation process of the current GaN HEMT device does not exceed the bottom of the current NbNx sacrificial layer.

[0110] Optionally, using an etching process to etch the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer includes:

[0111] An etching process is used to prepare the current corrosion stripping groove, and the current corrosion stripping groove penetrates through the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer, and the current corrosion stripping groove is used to separately corrode and strip the current GaN HEMT device.

[0112] Optionally, using a corrosion process to remove the current NbNx sacrificial layer includes:

[0113] XeF2 gas is used to corrode the current NbNx sacrificial layer to remove the current NbNx sacrificial layer.

[0114] Optionally, after the current device structure layer and the current GaN HEMT epitaxial layer are peeled off from the first GaN HEMT epitaxial wafer, the method further includes the following steps:

[0115] Use a flexible tape or a transfer carrier to paste the peeled current device structure layer and the current GaN HEMT epitaxial layer, and transfer them to other required substrates.

[0116] Optionally, after the current device structure layer and the current GaN HEMT epitaxial layer are peeled off from the first GaN HEMT epitaxial wafer, the method further includes the following steps:

[0117] Clean the surface of the first GaN HEMT epitaxial wafer, and continue to use the remaining GaN HEMT epitaxial layers in the first GaN HEMT epitaxial wafer to fabricate the remaining GaN HEMT devices until all the GaN HEMT epitaxial layers are used and stripped, finally exposing the substrate;

[0118] Recycle the substrate, and continue to use the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, or use other sacrificial layers and other GaN epitaxial layers as a whole, to perform multiple repeated epitaxial growths on the substrate to form a second epitaxial structure with multiple repeated stacked layers;

[0119] Use the second epitaxial structure as the second GaN HEMT epitaxial wafer.

[0120] 3. Example description of the structure of a GaN HEMT epitaxial wafer

[0121] Combined with the above content, the GaN HEMT epitaxial wafer of the present application is described by way of example below, as Figure 10 shown. In Figure 10 , the GaN HEMT epitaxial wafer 1000 includes a first epitaxial structure 1020 having multiple repeated stacked layers on a substrate 1010.

[0122] Among them, the first epitaxial structure 1020 is obtained by performing multiple repeated epitaxial growths on the substrate 1010 with one layer of NbNx sacrificial layer and one layer of GaN HEMT epitaxial layer as a whole.

[0123] Among them, the NbNx sacrificial layer is used for GaN HEMT epitaxial layer stripping.

[0124] Among them, the GaN HEMT epitaxial wafer 1000 is used to fabricate GaN HEMT devices by sequentially using each GaN HEMT epitaxial layer from the topmost layer to the bottommost layer, and then using the NbNx sacrificial layer for epitaxial layer stripping until all the GaN HEMT epitaxial layers are used and stripped, and finally recycling the substrate 1010.

[0125] It can be seen that the GaN HEMT epitaxial wafer 1000 can achieve the effect of one-time growth and multiple uses, so that compared with other epitaxial wafers prepared by conventional technologies under the same wafer size, the GaN HEMT epitaxial wafer 1000 can fabricate several times the number of GaN HEMT devices, thus helping to significantly reduce the cost of GaN HEMT device products.

[0126] Secondly, the GaN HEMT epitaxial layer grown on the substrate has better quality and characteristics, higher thickness, and fewer defects, which is beneficial to improving the performance, yield, and qualification rate of the fabricated GaN HEMT devices.

[0127] Again, the NbNx sacrificial layer minimizes the damage caused by peeling off the GaN HEMT epitaxial layer, reducing the damage to the fabricated GaN HEMT device due to the peeling of the GaN HEMT epitaxial layer.

[0128] Finally, after all the GaN HEMT epitaxial layers have been used and peeled off, the substrate is recycled to facilitate the subsequent epitaxial growth of a new epitaxial structure on the substrate, thereby facilitating the cyclic reuse of the substrate and further reducing the cost of the GaN HEMT epitaxial wafer and the GaN HEMT device.

[0129] Optionally, the material of the substrate 1010 is GaN or SiC.

[0130] Optionally, the GaN HEMT epitaxial layer includes at least one of the following: a nucleation layer, a buffer layer, a high-resistance layer, a channel layer, a barrier layer, and a cap layer. Among them, the nucleation layer, the buffer layer, the high-resistance layer, the channel layer, the barrier layer, and the cap layer are deposited in sequence from bottom to top.

[0131] Optionally, the number of times of repeated epitaxial growth is 1 to 9 times.

[0132] Optionally, in Figure 11 , the first epitaxial structure 1020 includes a current NbNx sacrificial layer 1021, a current GaN HEMT epitaxial layer 1022, a current device structure layer 1023, and a current corrosion and peeling groove 1024.

[0133] Among them, the current NbNx sacrificial layer 1021 is located on the next layer of the current GaN HEMT epitaxial layer 1022.

[0134] Among them, the current GaN HEMT epitaxial layer 1022 is located on the next layer of the current device structure layer 1023.

[0135] Among them, the current GaN HEMT device is composed of the current GaN HEMT epitaxial layer 1022 and the current device structure layer 1023.

[0136] Among them, the current corrosion and peeling groove 1024 penetrates the current device structure layer 1023 and the current GaN HEMT epitaxial layer 1022 to expose the current NbNx sacrificial layer 1021, and the current corrosion and peeling groove 1024 is used to separately corrode and peel the current GaN HEMT device.

[0137] Optionally, the current NbNx sacrificial layer 1021 can be one or more; the current GaN HEMT epitaxial layer 1022 can be one or more; the current device structure layer 1023 can be one or more; the current corrosion and peeling groove 1024 can be one or more.

[0138] Optionally, the first epitaxial structure 1020 further includes a NbNx sacrificial layer and a GaN HEMT epitaxial layer having a plurality of repeated stacks under the current NbNx sacrificial layer 1021 .

[0139] It should be noted that, for the above-mentioned various method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. Those skilled in the art should be aware that the present application is not limited by the described order of actions, because some steps in the embodiments of the present application can be performed in other orders or simultaneously. In addition, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present application.

[0140] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0141] The embodiments of the present application are described in detail above, and the description in the embodiments of the present application is only used to help understand the method and core idea of ​​the present application. Those skilled in the art should know that the embodiments of the present application may be changed in specific implementation and application scope, and the content of this specification should not be construed as limiting the present application.

Claims

1. A method for fabricating a gallium nitride high electron mobility transistor epitaxial wafer, characterized in that, Including: On a substrate, a niobium nitride NbNx sacrificial layer and a gallium nitride high electron mobility transistor GaN HEMT epitaxial layer are sequentially epitaxially grown. The NbNx sacrificial layer is used for GaN HEMT epitaxial lift-off. Taking the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, multiple repeated epitaxial growths are performed on the substrate, and finally a first epitaxial structure with multiple repeated stacks is formed on the substrate. Using the first epitaxial structure as a first GaN HEMT epitaxial wafer; wherein, the first GaN HEMT epitaxial wafer is used to sequentially use each GaN HEMT epitaxial layer to fabricate GaN HEMT devices in the order from the topmost layer to the bottommost layer, and then use the NbNx sacrificial layer for epitaxial lift-off until all GaN HEMT epitaxial layers are used and lifted off, and finally recover the substrate. Fabricating a current GaN HEMT device using the current GaN HEMT epitaxial layer in the first GaN HEMT epitaxial wafer. After completing the front-end process of the current GaN HEMT device, a current device structure layer is formed on the current GaN HEMT epitaxial layer, and the current GaN HEMT device is composed of the current GaN HEMT epitaxial layer and the current device structure layer. Using an etching process to etch the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer, and the current NbNx sacrificial layer is in the next layer of the current GaN HEMT epitaxial layer in the first GaN HEMT epitaxial wafer. Using an etching process to remove the current NbNx sacrificial layer, so that the current device structure layer and the current GaN HEMT epitaxial layer are lifted off from the first GaN HEMT epitaxial wafer.

2. The method according to claim 1, characterized in that, The GaN HEMT epitaxial layer includes at least one of the following: Nucleation layer, buffer layer, high-resistance layer, channel layer, barrier layer, cap layer. The nucleation layer, the buffer layer, the high-resistance layer, the channel layer, the barrier layer, and the cap layer are sequentially deposited from bottom to top.

3. The method according to claim 2, characterized in that, The number of times of the repeated epitaxial growth is 1 to 9 times.

4. The method according to claim 1, characterized in that, The etching depth in the fabrication process of the current GaN HEMT device does not exceed the bottommost part of the current NbNx sacrificial layer.

5. The method according to claim 1, characterized in that, The using an etching process to etch the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer includes: Using an etching process to prepare a current etching and lift-off groove, and the current etching and lift-off groove penetrates through the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer, and the current etching and lift-off groove is used for separating and etching and lifting off the current GaN HEMT device.

6. The method according to claim 1, characterized in that, The using an etching process to remove the current NbNx sacrificial layer includes: Using XeF2 gas to etch the current NbNx sacrificial layer to remove the current NbNx sacrificial layer.

7. The method according to claim 1, characterized in that, After the current device structure layer and the current GaN HEMT epitaxial layer are peeled off from the first GaN HEMT epitaxial wafer, the following steps are further included: Use a flexible tape or a transfer carrier to paste the peeled current device structure layer and the current GaN HEMT epitaxial layer, and transfer them to other required substrates.

8. The method according to claim 1, characterized in that, After the current device structure layer and the current GaN HEMT epitaxial layer are peeled off from the first GaN HEMT epitaxial wafer, the following steps are further included: Clean and etch the surface of the first GaN HEMT epitaxial wafer, and continue to use the remaining GaN HEMT epitaxial layers in the first GaN HEMT epitaxial wafer to fabricate the remaining GaN HEMT devices until all the GaN HEMT epitaxial layers are used and peeled off, finally exposing the substrate; Recover the substrate, and continue to use the NbNx sacrificial layer and the GaN HEMT epitaxial layer as a whole, or use other sacrificial layers and other GaN epitaxial layers as a whole, to perform multiple repeated epitaxial growths on the substrate to form a second epitaxial structure with multiple repeated stacks; Use the second epitaxial structure as the second GaN HEMT epitaxial wafer.

9. A gallium nitride high electron mobility transistor epitaxial wafer, characterized in that, For fabricating GaN HEMT devices by sequentially using each gallium nitride high electron mobility transistor (GaN HEMT) epitaxial layer from the topmost layer to the bottommost layer, and then using the niobium nitride (NbNx) sacrificial layer for epitaxial peeling until all the GaN HEMT epitaxial layers are used and peeled off, and finally recovering the substrate; The epitaxial wafer includes: A first epitaxial structure with multiple repeated stacks on the substrate, the first epitaxial structure is obtained by performing multiple repeated epitaxial growths on the substrate with one layer of the NbNx sacrificial layer and one layer of the GaN HEMT epitaxial layer as a whole, and the NbNx sacrificial layer is used for GaN HEMT epitaxial peeling; The topmost first epitaxial structure includes the current NbNx sacrificial layer and the current GaN HEMT epitaxial layer; The current NbNx sacrificial layer is located in the layer below the current GaN HEMT epitaxial layer; The current GaN HEMT epitaxial layer is located in the layer below the current device structure layer; The current GaN HEMT device is composed of the current GaN HEMT epitaxial layer and the current device structure layer; The current etching and peeling groove penetrates through the current device structure layer and the current GaN HEMT epitaxial layer to expose the current NbNx sacrificial layer, and the current etching and peeling groove is used for separately etching and peeling the current GaN HEMT device.

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