Gallium nitride light-emitting diode epitaxial wafer and its preparation method

Abstract

The present application discloses a gallium nitride light-emitting diode epitaxial wafer and a preparation method thereof. The method includes: epitaxially growing a layer of InGaN or n+GaN sacrificial layer and a layer of GaN LED epitaxial layer on a substrate in sequence; taking the InGaN or n+GaN sacrificial layer and the GaN LED 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; depositing a sidewall dielectric layer on the outer edge of the first epitaxial structure; and using the first epitaxial structure and the sidewall dielectric layer as a first GaN LED epitaxial wafer. It can be seen that the first GaN LED epitaxial wafer can achieve the effect of one-time growth and multiple uses, so as to produce several times the number of GaN LED devices, thereby reducing the cost of GaN LED device products. At the same time, wet etching is used to achieve epitaxial lift-off.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor device processes, and particularly to a gallium nitride light-emitting diode epitaxial wafer and a preparation method thereof. Background Art

[0002] Medium- and high-power or vertically packaged gallium nitride (GaN) light-emitting diode (LED) devices generally need to be fabricated on GaN LED epitaxial wafers on silicon carbide (SiC) or GaN substrates. However, the GaN LED epitaxial wafers on SiC or GaN substrates are usually expensive, making the cost of GaN LED epitaxial wafers account for a major part of the entire cost of GaN LED device products. Therefore, in order to reduce the cost of GaN LED device products, it is necessary to fundamentally reduce the cost of GaN LED epitaxial wafers.

[0003] In addition, such GaN LED devices generally use a laser lift-off process to separate the GaN LED device structure layer from the sapphire substrate. However, in this process, it is inevitable to generate thermal and mechanical damage to the GaN LED device, resulting in a decline in the performance of the GaN LED device. Moreover, the laser lift-off process has high costs and low efficiency. Summary of the Invention

[0004] This application provides a gallium nitride light-emitting diode epitaxial wafer and a preparation method thereof, in order to reduce the cost of GaN LED epitaxial wafers.

[0005] In a first aspect, a preparation method of a gallium nitride light-emitting diode epitaxial wafer according to this application includes:

[0006] On a substrate, a layer of indium gallium nitride InGaN or a highly doped N-type gallium nitride n+GaN sacrificial layer and a layer of gallium nitride light-emitting diode GaN LED epitaxial layer are sequentially epitaxially grown. The InGaN or n+GaN sacrificial layer is used for wet etching of GaN LED epitaxial layer stripping.

[0007] Taking the InGaN or n+GaN sacrificial layer and the GaN LED 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.

[0008] A sidewall dielectric layer is deposited on the outer edge of the first epitaxial structure. The sidewall dielectric layer is used to prevent the corrosion of the lower InGaN or n+GaN sacrificial layer during the current epitaxial layer stripping corrosion.

[0009] Take the first epitaxial structure and the sidewall dielectric layer as the first GaN LED epitaxial wafer; wherein, the first GaN LED epitaxial wafer is used to prepare GaN LED devices by sequentially using each of the GaN LED epitaxial layers in the order from the topmost layer to the bottommost layer, and then using the InGaN or n+GaN sacrificial layer for wet etching epitaxial lift-off until all the GaN LED epitaxial layers are used and lifted off, and finally recovering the substrate.

[0010] It can be seen that the first GaN LED 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 LED epitaxial wafer can produce several times the number of GaN LED devices, which is conducive to significantly reducing the cost of GaN LED device products.

[0011] Secondly, the GaN LED epitaxial layer grown on the substrate has better quality and characteristics, higher thickness, and fewer defects, which is conducive to improving the performance, yield, and qualification rate of the prepared GaN LED devices.

[0012] Thirdly, using wet etching for epitaxial lift-off avoids the problems of high process cost and low efficiency caused by laser lift-off. At the same time, through the InGaN or n+GaN sacrificial layer, the damage of lifting off the GaN LED epitaxial layer is minimized, reducing the damage to the prepared GaN LED devices due to lifting off the GaN LED epitaxial layer.

[0013] Finally, through the sidewall dielectric layer, corrosion of the lower InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching is avoided. At the same time, after all the GaN LED epitaxial layers are used and lifted off, the substrate is recovered for 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 LED epitaxial wafers and GaN LED devices.

[0014] In a second aspect, a gallium nitride light-emitting diode epitaxial wafer according to the present application is used to prepare GaN LED devices by sequentially using each gallium nitride light-emitting diode GaN LED epitaxial layer in the order from the topmost layer to the bottommost layer, and then using an indium gallium nitride InGaN or a high-doping-concentration N-type gallium nitride n+GaN sacrificial layer for wet etching epitaxial lift-off until all the GaN LED epitaxial layers are used and lifted off, and finally recovering the substrate; the epitaxial wafer includes:

[0015] A first epitaxial structure having multiple repeating stacks on the substrate, the first epitaxial structure being obtained by repeatedly growing epitaxially on the substrate multiple times with a layer of the InGaN or n+GaN sacrificial layer and a layer of the GaN LED epitaxial layer as a whole, the InGaN or n+GaN sacrificial layer being used for wet etching of GaN LED epitaxial lift-off; and,

[0016] A sidewall dielectric layer deposited on the outer edge of the first epitaxial structure, the sidewall dielectric layer being used to prevent corrosion of the underlying InGaN or n+GaN sacrificial layer during current epitaxial lift-off etching.

[0017] The beneficial effects brought about by the technical solution of the second aspect can be referred to the technical effects brought about by the technical solution of the first aspect, which will not be elaborated here. Brief Description of the Drawings

[0018] 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.

[0019] Figure 1 It is a schematic structural diagram of an epitaxial structure of a GaN LED provided by the present application;

[0020] Figure 2 It is a schematic structural diagram of a GaN LED epitaxial layer provided by the present application;

[0021] Figure 3 It is a schematic structural diagram of another epitaxial structure of a GaN LED provided by the present application;

[0022] Figure 4 It is a schematic structural diagram of a GaN LED epitaxial wafer provided by the present application;

[0023] Figure 5 It is a schematic structural diagram of another GaN LED epitaxial wafer provided by the present application;

[0024] Figure 6 It is a schematic structural diagram of a structure after preparing an etching and lift-off groove on a GaN LED epitaxial wafer provided by the present application;

[0025] Figure 7 It is a schematic structural diagram of a structure after preparing a sidewall protective film on a GaN LED epitaxial wafer provided by the present application;

[0026] Figure 8 It is a schematic structural diagram of an epitaxial structure when using an electrochemical etching process to remove the exposed InGaN or n+GaN sacrificial layer;

[0027] Figure 9It is a schematic structural diagram of an epitaxial structure when stripping the device structure layer and the GaN LED epitaxial layer provided by this application;

[0028] Figure 10 It is a schematic structural diagram of another substrate when transferring the stripped device structure layer and the GaN LED epitaxial layer to another substrate provided by this application;

[0029] Figure 11 It is a schematic flow diagram of a method for preparing a GaN LED epitaxial wafer provided by this application;

[0030] Figure 12 It is a schematic structural diagram of a GaN LED epitaxial wafer provided by this application;

[0031] Figure 13 It is a schematic structural diagram of another GaN LED epitaxial wafer provided by this application. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of this application.

[0033] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. The mention of "embodiment" in this article 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 specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment 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. In addition, "placed on", "placed", or "positioned" in the embodiments of this application is the same as "deposited", and is a layer structure deposited by thin film deposition technology in semiconductor manufacturing processes.

[0034] In the accompanying drawings provided by the embodiments of the present application, the cross-sectional view of the shown device structure may not be enlarged locally in accordance with a general ratio, and the schematic diagram is only for illustrative purposes and should not limit the scope claimed in the present application. At the same time, the thickness of each layer in the cross-sectional view of the shown device structure is only a schematic, which needs to be determined according to the specific semiconductor process and does not constitute a limitation to the embodiments of the present application. In addition, the radio frequency semiconductor device prepared in the actual manufacturing process for radio frequency semiconductor devices should include three-dimensional spatial dimensions of length, width, and depth.

[0035] The “at least one (item)” or its similar expression in the embodiments of the present application refers to any combination of these items, including any combination of a single item or multiple items, which means one or more, and multiple means two or more. For example, at least one (item) of a, b, or c can represent the following seven cases: a, b, c, a and b, a and c, b and c, a, b, and c. Among them, each of a, b, and c can be an element or a set containing one or more elements.

[0036] 1. Preparation of GaN LED epitaxial wafers

[0037]

Description

[0038] In order to reduce the cost of GaN LED device products and avoid using the laser lift-off process, the present application proposes a method for preparing GaN LED epitaxial wafers, which is specifically as follows:

[0039] First, a layer of indium gallium nitride (InGaN) or a high-doping concentration N-type gallium nitride (n+GaN) sacrificial layer is epitaxially grown on the substrate, then a GaN LED epitaxial layer is epitaxially grown thereon, and then, taking the InGaN or n+GaN sacrificial layer and the GaN LED epitaxial layer as a whole, multiple repeated epitaxial growths are performed on the substrate. Finally, a sidewall dielectric layer is deposited on the outer edge of the epitaxial structure to prepare a GaN LED epitaxial wafer.

[0040] In this way, since the GaN LED epitaxial wafer includes multiple repeated and overlapping InGaN or n+GaN sacrificial layers and GaN LED epitaxial layers grown epitaxially from bottom to top, and the GaN LED epitaxial layer is used to prepare GaN LED devices, and the InGaN or n+GaN sacrificial layer is used for wet etching of GaN LED epitaxial lift-off, the present application can sequentially use each GaN LED epitaxial layer from the topmost layer to the bottommost layer to prepare GaN LED devices, and then use the InGaN or n+GaN sacrificial layer for wet etching epitaxial lift-off until all GaN LED epitaxial layers are used and peeled off.

[0041] It can be seen that the present application prepares GaN LED epitaxial wafers by repeated epitaxial growth, so that the GaN LED epitaxial wafer can achieve the effect of being grown once and used multiple times, so that under the same wafer size, compared with other epitaxial wafers prepared by conventional technology, the GaN LED epitaxial wafer can produce several times the number of GaN LED devices, which is beneficial to significantly reduce the cost of GaN LED device products.

[0042] Secondly, the GaN LED epitaxial layer grown on the substrate has better quality and characteristics, higher thickness, and fewer defects, which is beneficial to improving the performance, finished product rate, and yield rate of the prepared GaN LED device.

[0043] Thirdly, epitaxial stripping is performed by wet etching to avoid the high process cost and low efficiency caused by laser stripping. At the same time, the damage to the stripped GaN LED epitaxial layer is minimized by the InGaN or n+GaN sacrificial layer, reducing the damage to the prepared GaN LED device caused by the stripping of the GaN LED epitaxial layer. In addition, the stripped GaN LED epitaxial layer can be heterogeneously integrated with other semiconductor devices or circuits after transfer, so that different semiconductor materials can play their best characteristics, obtain chips or components with better performance, and realize smaller and stronger chips or components.

[0044] Finally, the sidewall dielectric layer is used to prevent the lower InGaN or n+GaN sacrificial layer from being corroded during the current epitaxial stripping corrosion. At the same time, after all GaN LED epitaxial layers are used and stripped, the present application can recycle the substrate so that a new epitaxial structure can be grown on the substrate later, thereby facilitating the recycling of the substrate and further reducing the cost of GaN LED epitaxial wafers and GaN LED devices.

[0045]

Specific process flow

[0046] In combination with the above content, the specific process flow of preparing GaN LED epitaxial wafers is introduced as follows:

[0047] Step 1: Select the substrate

[0048] The substrate is the carrier of the device epitaxy and has a great influence on the RF performance. Its selection needs to comprehensively consider factors such as cost, lattice matching with the epitaxial layer, thermal conductivity, and the difficulty of obtaining large-size wafers.

[0049] Optionally, the substrate includes a SiC or sapphire substrate.

[0050] It should be noted that, in order to ensure performance, the dielectric substrate material selected in this application is SiC or sapphire.

[0051] In this way, by epitaxially growing a GaN LED epitaxial layer on a SiC or sapphire substrate, the grown GaN LED epitaxial layer can have better quality and characteristics, a higher thickness, and fewer defects, which is beneficial to improving the performance, yield, and good rate of the fabricated GaN LED devices.

[0052] Step 2: Epitaxially grow an InGaN or n+GaN sacrificial layer and a GaN LED epitaxial layer in sequence.

[0053] As Figure 1 shown, on the substrate, an InGaN or n+GaN sacrificial layer and a GaN LED epitaxial layer are epitaxially grown in sequence using an epitaxial thin film preparation process.

[0054] It should be noted that InGaN and n+GaN can have good lattice matching with SiC and sapphire, enabling the InGaN or n+GaN sacrificial layer to have good lattice matching with the SiC substrate, so as to be able to grow a GaN LED epitaxial layer with excellent crystal quality and greater thickness on the SiC substrate.

[0055] In addition, the technology of epitaxially growing GaN on sapphire is relatively mature, and an epitaxial layer with better lattice quality and less residual stress can also be obtained, so as to be able to grow a better GaN LED epitaxial layer on the sapphire substrate. At the same time, the crystal quality of the repeatedly grown epitaxial layer is mainly related to the quality of the underlying epitaxial layer, which can be considered as homoepitaxy, and the crystal quality will be relatively good.

[0056] Optionally, the purpose of preparing the InGaN or n+GaN sacrificial layer can be used for GaN LED epitaxial lift-off (such as lifting off the GaN LED epitaxial layer, lifting off the GaN LED structure device layer, etc.), or it can be used to recycle the substrate after all the GaN LED epitaxial layers have been used and lifted off.

[0057] Optionally, the InGaN sacrificial layer can include In x Ga y N sacrificial layer. Wherein, the value of x is 0.08 - 0.2, and x + y = 1.

[0058] Optionally, the high doping concentration n+ in the n+GaN sacrificial layer is 1E19 - 1E20 / cm3.

[0059] Optionally, the epitaxial thin film preparation process may include chemical vapor deposition (CVD), physical vapor deposition (PVD), etc. Among them, CVD may include metal organic chemical vapor deposition (MOCVD), plasma enhanced chemical vapor deposition (PECVD), etc.; PVD may include molecular beam epitaxy (MBE), pulsed laser deposition (PLD), magnetron sputtering, etc.

[0060] For example, MOCVD is used to epitaxially grow an InGaN or n+GaN sacrificial layer, and MBE or MOCVD is used to epitaxially grow a GaN LED epitaxial layer.

[0061] Optionally, the GaN LED epitaxial layer includes at least one of the following: an N-type contact layer, an N-type GaN layer, a multiple quantum well (MQW) layer, a P-type GaN layer, and a P-type contact layer. Among them, the N-type contact layer, the N-type GaN layer, the multiple quantum well layer, the P-type GaN layer, and the P-type contact layer are deposited in sequence from bottom to top.

[0062] Optionally, the material of the N-type contact layer may include n++GaN with a high doping concentration, etc.

[0063] Optionally, the material of the N-type GaN layer may include n+GaN with a high doping concentration, etc.

[0064] Optionally, the material of the multiple quantum well layer may include InGaN or GaN, etc.

[0065] Optionally, the material of the P-type GaN layer may include p GaN.

[0066] Optionally, the material of the P-type contact layer may include p+GaN with a high doping concentration, etc.

[0067] For example, as Figure 2 shown, the GaN LED epitaxial layer includes an n++GaN contact layer, an n+GaN layer, an InGaN / GaN multiple quantum well layer, a p GaN layer, and a p+GaN contact layer deposited in sequence from bottom to top.

[0068] Step 3: Taking the InGaN or n+GaN sacrificial layer and the GaN LED 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.

[0069] AsFigure 3 As shown, on the substrate, the InGaN or n+GaN sacrificial layer and the GaN LED epitaxial layer are repeatedly epitaxially grown to form a first epitaxial structure with multiple repeated stacks.

[0070] Optionally, the number of times of repeated epitaxial growth is 1 to 9 times. That is to say, taking the InGaN or n+GaN sacrificial layer and the GaN LED epitaxial layer as a whole, the whole is repeatedly epitaxially grown 1 to 9 times. In this way, finally, 2 to 10 InGaN or n+GaN sacrificial layers and GaN LED epitaxial layers can be obtained.

[0071] Of course, the number of times of repeated epitaxial growth in this application is not limited to 1 to 9 times, and can also be other values, which mainly depends on the process preparation ability and requirements.

[0072] Step 4: Deposit a sidewall dielectric layer on the outer edge of the first GaN LED epitaxial wafer

[0073] As Figure 4 shown, a sidewall dielectric layer is deposited on the outer edge of the first GaN LED epitaxial wafer through a deposition process. This sidewall dielectric layer is used to prevent the corrosion of the lower InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching. Finally, the first epitaxial structure and the sidewall dielectric layer are used as the first GaN LED epitaxial wafer, thereby preparing the GaN LED epitaxial wafer.

[0074] In this way, this application prepares the GaN LED epitaxial wafer by means of multiple repeated epitaxial growths, so that the GaN LED epitaxial wafer can achieve the effect of one-time growth and multiple uses, so that several times the number of GaN LED devices can be made from the GaN LED epitaxial wafer under the condition of other epitaxial wafers prepared by conventional technologies of the same size, thereby contributing to a significant reduction in the cost of GaN LED device products.

[0075] Step 5: Use each GaN LED epitaxial layer in sequence from the topmost layer to the bottommost layer to prepare GaN LED devices, and do not perform edge trimming in the glue coating process during the metal wire contact lead pad (PAD) process for preparing GaN LED devices to protect the sidewall dielectric layer, and finally form a device structure layer

[0076] It should be noted that after the first GaN LED epitaxial wafer is prepared, each GaN LED epitaxial layer can be used in sequence from the topmost layer to the bottommost layer to prepare GaN LED devices.

[0077] Meanwhile, in the photoresist coating process of the metal wire contact PAD process for fabricating GaN LED devices, no edge removal treatment is performed. This is because a sidewall dielectric layer is deposited on the outer edge of the first epitaxial structure, and not performing edge removal treatment in the photoresist coating process can effectively protect the sidewall dielectric layer, which can protect the underlying InGaN or n+GaN sacrificial layer from being corroded by subsequent stripping and etching processes.

[0078] Then, after each completion of the front process of the GaN LED device, a device structure layer is formed on the GaN LED epitaxial layer, and the GaN LED device is composed of the GaN LED epitaxial layer and the device structure layer.

[0079] For example, as Figure 5 shown, the current GaN LED device is fabricated using the current GaN LED epitaxial layer, and after the front process of the current GaN LED device is completed, the current device structure layer is formed on the current GaN LED epitaxial layer. The current GaN LED device is composed of the current GaN LED epitaxial layer and the current device structure layer.

[0080] Optionally, during the process of fabricating a GaN LED device using a GaN LED epitaxial layer each time, the etching depth does not exceed the bottommost part of the next layer (i.e., the InGaN or n+GaN sacrificial layer) of the used GaN LED epitaxial layer.

[0081] This is because, taking the use of the current GaN LED epitaxial layer as an example, the etching depth during the fabrication process of the current GaN LED device does not exceed the bottommost part of the current InGaN or n+GaN sacrificial layer. In this way, loss of the GaN LED epitaxial layer below the current InGaN or n+GaN sacrificial layer can be avoided, ensuring that the subsequent fabrication of the GaN LED device is not affected by the previous fabrication processes.

[0082] Step 6: Use an etching process to etch the device structure layer and the GaN LED epitaxial layer to expose the InGaN or n+GaN sacrificial layer

[0083] In order to perform epitaxial lift-off on the GaN LED device that has completed the front process, it is necessary to first use an etching process to etch the device structure layer and the GaN LED epitaxial layer to expose the InGaN or n+GaN sacrificial layer. This can facilitate the etching of the exposed InGaN or n+GaN sacrificial layer for GaN LED epitaxial lift-off.

[0084] For example, taking Figure 6As shown, an etching process is used to etch the device structure layer and the GaN LED epitaxial layer to prepare an etching and peeling groove, which penetrates the device structure layer and the GaN LED epitaxial layer to expose the InGaN or n+GaN sacrificial layer. Among them, the etching and peeling groove can be used to separately etch and peel between GaN LED devices.

[0085] Taking the front process of the current GaN LED device as an example, an etching process is used to prepare the current etching and peeling groove, which penetrates the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer, and the current etching and peeling groove can be used to separately etch and peel the current GaN LED device.

[0086] Step 7: Form a sidewall protective film on the inner sidewalls of the etched device structure layer and the GaN LED epitaxial layer

[0087] It should be noted that a dielectric deposition-reactive ion etching process is used to form a sidewall protective film on the inner sidewalls, and the sidewall protective film is used to prevent corrosion damage to the GaN LED device when the subsequent InGaN or n+GaN sacrificial layer is etched.

[0088] For example, it can prevent corrosion damage to the MQW inside the GaN LED device when the subsequent InGaN or n+GaN sacrificial layer is etched. At the same time, the InGaN or n+GaN sacrificial layer at the bottom of the etching and peeling groove is exposed to facilitate contact between the etching gas or solution and the InGaN or n+GaN sacrificial layer. For example, as Figure 7 shown.

[0089] Step 8: Use an etching process to remove the exposed InGaN or n+GaN sacrificial layer, so that the device structure layer and the GaN LED epitaxial layer are peeled off from the first GaN LED epitaxial wafer

[0090] In this way, the present application can peel the device structure layer and the GaN LED epitaxial layer.

[0091] Optionally, the etching process can include using an electrochemical etching process to remove the exposed n+GaN sacrificial layer, as Figure 8 shown.

[0092] At Figure 8In this process, the first GaN LED epitaxial wafer is immersed in an etching electrolyte, and an electric current is applied to the etching electrolyte through inert metals connected to both ends of the positive and negative electrodes, so as to remove the exposed n+GaN sacrificial layer by using an electrochemical etching process. Among them, the etching electrolyte may include HF mixture, oxalic acid mixture, nitric acid mixture, etc.; a bias voltage of 5-30V is applied to the positive and negative electrodes. Of course, the surface of the epitaxial wafer can be protected with photoresist to avoid etching the opened contact holes.

[0093] Optionally, the etching process may include using an etching solution and ultraviolet light irradiation in a photo-assisted electrochemical etching process to remove the exposed InGaN sacrificial layer. Among them, the etching solution may include an aqueous KOH solution; the wavelength λ of the ultraviolet light may be greater than 366nm and less than the wavelength of the absorption edge of the bandgap of InxGaN. Of course, the surface of the epitaxial wafer can be protected with photoresist to avoid etching the opened contact holes.

[0094] Optionally, for the InxGaN component, x = 0.12, and the wavelength λ of the ultraviolet light is 400nm.

[0095] In this way, through the etching process, the device structure layer and the GaN LED epitaxial layer are peeled off from the first GaN LED epitaxial wafer, as Figure 9 shown.

[0096] Step 9: Use a flexible tape or a transfer carrier to paste the peeled device structure layer and GaN LED epitaxial layer, and transfer them to other required substrates

[0097] It should be noted that after the device structure layer and the GaN LED epitaxial layer are peeled off, the peeled device structure layer and GaN LED epitaxial layer are fished out, dried, and then transferred.

[0098] It can be seen that the present application can transfer the peeled device structure layer and GaN LED epitaxial layer, so that the peeled GaN LED 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.

[0099] For example, as Figure 10 shown, the peeled device structure layer and GaN LED epitaxial layer are transferred to other substrates.

[0100] Optionally, the flexible tape may include an ultraviolet (UV) tape.

[0101] Optionally, the transfer carrier may include a quartz glass sheet, a sapphire sheet, etc.

[0102] Optionally, other substrates may include diamond substrates, AlN substrates, SiC substrates, glass, or wafers containing devices / circuits, etc.

[0103] Step 10: After the remaining first GaN LED epitaxial wafer is cleaned, it is put back into use until all GaN LED epitaxial layers are used and peeled off, finally exposing the substrate.

[0104] For example, clean and etch the surface of the first GaN LED epitaxial wafer, and continue to use the remaining GaN LED epitaxial layers in the first GaN LED epitaxial wafer to fabricate the remaining GaN LED devices until all GaN LED epitaxial layers are used and peeled off, and finally expose the substrate.

[0105] Step 11: Recycle the substrate, and after surface cleaning, perform new epitaxial growth again.

[0106] In this way, after all GaN LED epitaxial layers are used and peeled off, the present application can recycle the substrate 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 GaN LED epitaxial wafers and GaN LED devices.

[0107] For example, recycle the substrate, and continue to use InGaN or n+GaN sacrificial layers and GaN LED epitaxial layers 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, thereby using the substrate and the second epitaxial structure as a second GaN LED epitaxial wafer, and thus fabricating a new GaN LED epitaxial wafer.

[0108] Among them, the other sacrificial layer can be understood as a sacrificial layer whose material is not InGaN or n+GaN. For example, the other sacrificial layer is a niobium nitride (NbNx) sacrificial layer, etc.; the other GaN epitaxial layer can be understood as an epitaxial layer having different film layers from the GaN LED epitaxial layer.

[0109] It should be noted that when performing multiple repeated epitaxial growths again with InGaN or n+GaN sacrificial layers and GaN LED epitaxial layers as a whole, the number of repeated epitaxial growths at this time can be the same as that of the previous time, can be different from that of the previous time, which is determined by the preparation process and requirements, and no specific limitation is made here.

[0110] 2. Example illustration of a method for fabricating a GaN LED epitaxial wafer

[0111] Combined with the above content, the following is an example illustration of the GaN LED epitaxial wafer fabrication method of the present application, as Figure 11As shown. In Figure 11 the method for preparing a GaN LED epitaxial wafer may include the following steps:

[0112] S1110. On a substrate, a layer of InGaN or n+GaN sacrificial layer and a layer of GaN LED epitaxial layer are sequentially epitaxially grown. The InGaN or n+GaN sacrificial layer is used for wet etching of GaN LED epitaxial lift-off.

[0113] S1120. Taking the InGaN or n+GaN sacrificial layer and the GaN LED 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.

[0114] S1130. A sidewall dielectric layer is deposited on the outer edge of the first epitaxial structure. The sidewall dielectric layer is used to prevent the corrosion of the lower InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching.

[0115] S1140. The first epitaxial structure and the sidewall dielectric layer are used as the first GaN LED epitaxial wafer; wherein, the first GaN LED epitaxial wafer is used to prepare GaN LED devices by sequentially using each GaN LED epitaxial layer from the topmost layer to the bottommost layer, and then using the InGaN or n+GaN sacrificial layer for epitaxial lift-off until all GaN LED epitaxial layers are used and lifted off, and finally the substrate is recycled.

[0116] It can be seen that the first GaN LED epitaxial wafer 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 first GaN LED epitaxial wafer can produce several times the number of GaN LED devices, which is conducive to significantly reducing the cost of GaN LED device products.

[0117] Secondly, the GaN LED epitaxial layer grown on the substrate has better quality and characteristics, higher thickness, and fewer defects, which is conducive to improving the performance, yield, and good rate of the prepared GaN LED devices.

[0118] Thirdly, wet etching is used for epitaxial lift-off to avoid the problems of high process cost and low efficiency caused by laser lift-off. At the same time, through the InGaN or n+GaN sacrificial layer, the damage caused by lifting off the GaN LED epitaxial layer is minimized, and the damage to the prepared GaN LED devices due to lifting off the GaN LED epitaxial layer is reduced.

[0119] Finally, the sidewall dielectric layer is used to prevent the corrosion of the underlying InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching. At the same time, after all the GaN LED epitaxial layers are used and peeled off, the substrate is recycled 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 LED epitaxial wafers and GaN LED devices.

[0120] Optionally, after obtaining the first GaN LED epitaxial wafer, the method further includes the following steps:

[0121] Use the current GaN LED epitaxial layer in the first GaN LED epitaxial wafer to fabricate the current GaN LED device, and do not perform edge removal treatment during the glue application process in the metal wire contact lead pad process for fabricating the current GaN LED device to protect the sidewall dielectric layer;

[0122] After completing the front process of the current GaN LED device, form the current device structure layer on the current GaN LED epitaxial layer. The current GaN LED device is composed of the current GaN LED epitaxial layer and the current device structure layer;

[0123] Adopt an etching process to etch the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer. The current InGaN or n+GaN sacrificial layer is located in the layer below the current GaN LED epitaxial layer in the first GaN LED epitaxial wafer;

[0124] Form a sidewall protective film on the inner sidewalls of the etched current device structure layer and the current GaN LED epitaxial layer. The sidewall protective film is used to prevent corrosion damage to the current GaN LED device when the current InGaN or n+GaN sacrificial layer is corroded;

[0125] Adopt a corrosion process to remove the current InGaN or n+GaN sacrificial layer, so that the current device structure layer and the current GaN LED epitaxial layer are peeled off from the first GaN LED epitaxial wafer.

[0126] Optionally, the etching depth during the fabrication of the current GaN LED device does not exceed the bottommost part of the current InGaN or n+GaN sacrificial layer.

[0127] Optionally, adopting an etching process to etch the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer includes:

[0128] The current corrosion stripping groove is prepared by an etching process. The current corrosion stripping groove penetrates through the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer. The current corrosion stripping groove is used to separately etch and strip the current GaN LED device.

[0129] Optionally, the current InGaN or n+GaN sacrificial layer is removed by an etching process, including:

[0130] Removing the current InGaN sacrificial layer by a photo-assisted electrochemical etching process; or,

[0131] Removing the n+GaN sacrificial layer by an electrochemical etching process.

[0132] Optionally, after separating the current device structure layer and the current GaN LED epitaxial layer from the first GaN LED epitaxial wafer, the method further includes the following steps:

[0133] Using a flexible tape or a transfer carrier to paste the separated current device structure layer and the current GaN LED epitaxial layer, and transferring them to other required substrates.

[0134] Optionally, after separating the current device structure layer and the current GaN LED epitaxial layer from the first GaN LED epitaxial wafer, the method further includes the following steps:

[0135] Cleaning the surface of the first GaN LED epitaxial wafer after etching, and continuing to use the remaining GaN LED epitaxial layer in the first GaN LED epitaxial wafer to fabricate the remaining GaN LED devices until all GaN LED epitaxial layers are used and stripped, and finally exposing the substrate;

[0136] Recycling the substrate, and continuing to use the InGaN or n+GaN sacrificial layer and the GaN LED epitaxial layer as a whole, or using 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;

[0137] Regarding the substrate and the second epitaxial structure as a second GaN LED epitaxial wafer.

[0138] Optionally, the GaN LED epitaxial layer includes at least one of the following:

[0139] N-type contact layer, N-type GaN layer, multiple quantum well layer, P-type GaN layer, P-type contact layer;

[0140] The N-type contact layer, N-type GaN layer, multiple quantum well layer, P-type GaN layer, and P-type contact layer are deposited in sequence from bottom to top.

[0141] Optionally, the number of times of repeated epitaxial growth is from 1 to 9 times.

[0142] 3. Example illustration of the structure of a GaN LED epitaxial wafer

[0143] Combined with the above content, the GaN LED epitaxial wafer of the present application will be illustrated by example below, as Figure 12 shown. In Figure 12 , the GaN LED epitaxial wafer 1200 includes a first epitaxial structure 1220 having a plurality of repeated stacks on a substrate 1210, and a sidewall dielectric layer 1230 deposited on the outer edge of the first epitaxial structure 1220.

[0144] Among them, the first epitaxial structure 1220 is obtained by performing multiple repeated epitaxial growths on the substrate 1210 with a layer of InGaN or n+GaN sacrificial layer and a layer of GaN LED epitaxial layer as a whole.

[0145] Among them, the InGaN or n+GaN sacrificial layer is used for wet etching of GaN LED epitaxial lift-off.

[0146] Among them, the sidewall dielectric layer 1230 is used to prevent the corrosion of the underlying InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching.

[0147] Among them, the GaN LED epitaxial wafer 1200 is used to prepare GaN LED devices by sequentially using each GaN LED epitaxial layer in the order from the topmost layer to the bottommost layer, and then using the InGaN or n+GaN sacrificial layer for wet etching epitaxial lift-off until all GaN LED epitaxial layers are used and peeled off, and finally recycling the substrate 1210.

[0148] It can be seen that the first GaN LED epitaxial wafer can achieve the effect of one-time growth and multiple uses, so that compared with other epitaxial wafers prepared by conventional techniques under the same wafer size, the first GaN LED epitaxial wafer can produce several times the number of GaN LED devices, thus helping to significantly reduce the cost of GaN LED device products.

[0149] Secondly, the GaN LED epitaxial layer grown on the substrate has better quality and characteristics, higher thickness, and fewer defects, which is conducive to improving the performance, yield, and good rate of the prepared GaN LED devices.

[0150] Again, wet etching is used for epitaxial lift-off to avoid the problems of high process cost and low efficiency associated with laser lift-off. At the same time, the InGaN or n+GaN sacrificial layer minimizes the damage caused by lifting off the GaN LED epitaxial layer, reducing the damage to the fabricated GaN LED device due to the removal of the GaN LED epitaxial layer.

[0151] Finally, the sidewall dielectric layer prevents the etching of the underlying InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching. At the same time, after all the GaN LED epitaxial layers have been used and lifted off, the substrate is recycled for 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 LED epitaxial wafers and GaN LED devices.

[0152] Optionally, the material of the substrate 1210 is SiC or sapphire.

[0153] Optionally, the GaN LED epitaxial layer includes at least one of the following:

[0154] N-type contact layer, N-type GaN layer, multiple quantum well layer, P-type GaN layer, P-type contact layer;

[0155] The N-type contact layer, N-type GaN layer, multiple quantum well layer, P-type GaN layer, and P-type contact layer are deposited sequentially from bottom to top.

[0156] Optionally, the number of times of repeated epitaxial growth is 1 to 9 times.

[0157] Optionally, in Figure 13 the first epitaxial structure 1220 includes the current InGaN or n+GaN sacrificial layer 1221, the current GaN LED epitaxial layer 1222, the current device structure layer 1223, the current etching and lift-off groove 1224, and the sidewall protective film 1225.

[0158] Among them, the current InGaN or n+GaN sacrificial layer 1221 is located below the current GaN LED epitaxial layer 1222.

[0159] Among them, the current GaN LED epitaxial layer 1222 is located below the current device structure layer 1223.

[0160] Among them, the current GaN LED device is composed of the current GaN LED epitaxial layer 1222 and the current device structure layer 1223.

[0161] The current etching stripping groove 1224 penetrates the current device structure layer 1223 and the current GaN LED epitaxial layer 1222 to expose the current InGaN or n+GaN sacrificial layer 1221 , and the current etching stripping groove 1224 is used to separate and etch and strip the current GaN LED device.

[0162] The sidewall protection film 1225 is on the inner sidewalls of the current device structure layer 1223 and the current GaN LED epitaxial layer 1222 after etching.

[0163] The sidewall protection film 1225 is used to prevent corrosion damage to the current GaN LED device when the current InGaN or n+GaN sacrificial layer 1221 is corroded.

[0164] Optionally, the current InGaN or n+GaN sacrificial layer 1221 may be one or more; the current GaN LED epitaxial layer 1222 may be one or more; the current device structure layer 1223 may be one or more; the current etching stripping groove 1224 may be one or more; and the sidewall protection film 1225 may be one or more.

[0165] Optionally, the first epitaxial structure 1220 further includes a plurality of repeatedly stacked InGaN or n+GaN sacrificial layers and GaN LED epitaxial layers under the current InGaN or n+GaN sacrificial layer 1221 .

[0166] 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.

[0167] 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.

[0168] 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 preparing a gallium nitride light-emitting diode epitaxial wafer, characterized in that, it includes: on a substrate, epitaxially grow a layer of indium gallium nitride InGaN or a highly doped N-type gallium nitride n+GaN sacrificial layer and a layer of gallium nitride light-emitting diode GaN LED epitaxial layer in sequence, and the InGaN or n+GaN sacrificial layer is used for wet etching of GaN LED epitaxial layer stripping; taking the InGaN or n+GaN sacrificial layer and the GaN LED 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; deposit a sidewall dielectric layer on the outer edge of the first epitaxial structure, and the sidewall dielectric layer is used to prevent corrosion of the lower InGaN or n+GaN sacrificial layer during the current epitaxial layer stripping corrosion; regard the first epitaxial structure and the sidewall dielectric layer as a first GaN LED epitaxial wafer; wherein, the first GaN LED epitaxial wafer is used to prepare GaN LED devices by sequentially using each GaN LED epitaxial layer from the topmost layer to the bottommost layer, and then use the InGaN or n+GaN sacrificial layer for wet etching epitaxial layer stripping until all GaN LED epitaxial layers are used and stripped, and finally recycle the substrate; use the current GaN LED epitaxial layer in the first GaN LED epitaxial wafer to prepare the current GaN LED device, and do not perform edge removal treatment in the glue coating process during the metal wire contact lead pad process for preparing the current GaN LED device to protect the sidewall dielectric layer; after completing the front process of the current GaN LED device, form a current device structure layer on the current GaN LED epitaxial layer, and the current GaN LED device is composed of the current GaN LED epitaxial layer and the current device structure layer; adopt an etching process to etch the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer, and the current InGaN or n+GaN sacrificial layer is in the next layer of the current GaN LED epitaxial layer in the first GaN LED epitaxial wafer; form a sidewall protective film on the inner sidewalls of the etched current device structure layer and the current GaN LED epitaxial layer, and the sidewall protective film is used to prevent corrosion damage to the current GaN LED device when the current InGaN or n+GaN sacrificial layer is corroded; adopt a corrosion process to remove the current InGaN or n+GaN sacrificial layer, so that the current device structure layer and the current GaN LED epitaxial layer are stripped from the first GaN LED epitaxial wafer.

2. The method according to claim 1, characterized in that, the GaN LED epitaxial layer includes at least one of the following: N-type contact layer, N-type GaN layer, multi-quantum well layer, P-type GaN layer, P-type contact layer; The N-type contact layer, the N-type GaN layer, the multi-quantum well layer, the P-type GaN layer, and the P-type contact layer are deposited in sequence from bottom to top.

3. The method according to claim 1, wherein, the number of times of the repeated epitaxial growth is 1 to 9 times.

4. The method according to claim 1, wherein, the etching depth during the preparation process of the current GaN LED device does not exceed the bottommost part of the current InGaN or n+GaN sacrificial layer.

5. The method according to claim 1, wherein, the step of etching the current device structure layer and the current GaN LED epitaxial layer by an etching process to expose the current InGaN or n+GaN sacrificial layer includes: preparing a current etch lift-off groove by an etching process, the current etch lift-off groove penetrating through the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer, and the current etch lift-off groove being used to separately etch and lift off the current GaN LED device.

6. The method according to claim 5, wherein, the step of removing the current InGaN or n+GaN sacrificial layer by an etching process includes: removing the current InGaN sacrificial layer by a photo-assisted electrochemical etching process; or, removing the n+GaN sacrificial layer by an electrochemical etching process.

7. The method according to claim 1, wherein, after separating the current device structure layer and the current GaN LED epitaxial layer from the first GaN LED epitaxial wafer, it further includes: using a flexible tape or a transfer carrier to paste the separated current device structure layer and the current GaN LED epitaxial layer, and transferring them to other required substrates.

8. The method according to claim 1, wherein, after separating the current device structure layer and the current GaN LED epitaxial layer from the first GaN LED epitaxial wafer, it further includes: cleaning and etching the surface of the first GaN LED epitaxial wafer, and continuing to use the remaining GaN LED epitaxial layers in the first GaN LED epitaxial wafer to prepare the remaining GaN LED devices until all the GaN LED epitaxial layers are used and peeled off, and finally exposing the substrate; recovering the substrate, and continuing to use the InGaN or n+GaN sacrificial layer and the GaN LED epitaxial layer as a whole, or using 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; using the substrate and the second epitaxial structure as a second GaN LED epitaxial wafer.

9. A gallium nitride light-emitting diode epitaxial wafer, wherein, For preparing a GaN LED device by sequentially using each gallium nitride light-emitting diode (GaN LED) epitaxial layer from the topmost layer to the bottommost layer, and then using an indium gallium nitride (InGaN) or a highly doped N-type gallium nitride (n+GaN) sacrificial layer for wet etching epitaxial lift-off until all the GaN LED epitaxial layers are used and lifted off, and finally recovering the substrate; the epitaxial wafer includes: A first epitaxial structure having a plurality of repeating stacks on the substrate, the first epitaxial structure being obtained by repeatedly epitaxially growing on the substrate with one layer of the InGaN or n+GaN sacrificial layer and one layer of the GaN LED epitaxial layer as a whole, and the InGaN or n+GaN sacrificial layer being used for wet etching GaN LED epitaxial lift-off; and, A sidewall dielectric layer deposited on the outer edge of the first epitaxial structure, the sidewall dielectric layer being used to prevent the corrosion of the lower InGaN or n+GaN sacrificial layer during the current epitaxial lift-off etching; The first epitaxial structure includes a current InGaN or n+GaN sacrificial layer, a current GaN LED epitaxial layer, a current device structure layer, a current etching lift-off groove, and a sidewall protective film; The current InGaN or n+GaN sacrificial layer is located below the current GaN LED epitaxial layer; The current GaN LED epitaxial layer is located below the current device structure layer; The current GaN LED device is composed of the current GaN LED epitaxial layer and the current device structure layer; The current etching lift-off groove penetrates through the current device structure layer and the current GaN LED epitaxial layer to expose the current InGaN or n+GaN sacrificial layer, and the current etching lift-off groove is used for separately etching and lifting off the current GaN LED device; The sidewall protective film is on the inner sidewalls of the etched current device structure layer and the current GaN LED epitaxial layer; The sidewall protective film is used to prevent corrosion damage to the current GaN LED device when the current InGaN or n+GaN sacrificial layer is corroded.

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