Method for the production of gallium nitride substrate using multi-ion implantation

Abstract

Method for producing a gallium nitride substrate (100), the method comprising: Formation of a bond oxide film (120) on a first gallium nitride (110); Performing a first ion implantation for a surface of the first gallium nitride (110) on which the bonding oxide film (120) is formed, at least once, to form a damaged layer (113), thereby canceling any deflection of the first gallium nitride (110); Performing a second ion implantation for the surface of the first gallium nitride (110) on which the bonding oxide film (120) is formed, in order to form a blister layer (114); Connecting the bonding oxide film (120) of the first gallium nitride (110) to a temporary substrate (130); Separation of the first gallium nitride (110) using the vesicle layer (114) to form a nucleation layer (115); and Enabling the growth of a second gallium nitride (140) using the nucleation layer (115) to form gallium nitride in bulk, wherein, during the formation of the damaged layer (113), the thickness of the damaged layer (113) is controlled according to an accelerating voltage of the first ion implantation, wherein the second ion implantation is performed at an accelerating voltage that is lower than that of the first ion implantation, wherein the blister layer (114) is formed at a position which is closer to the surface of the first gallium nitride (110) on which the bonding oxide film (120) is formed, compared to a position of the damaged layer (113), wherein during the second ion implantation the bubble layer (114) is formed at a depth of 0.1 µm to 4 µm from the surface of the first gallium nitride (110), wherein a heat treatment at 400 °C to 800 °C is carried out for the bubble layer (114), wherein the first gallium nitride (110) comprises an N-surface (111) and a Ga-surface (112), wherein during the second ion implantation the blister layer (114) is formed on the Ga-surface (112) of the first gallium nitride (110), wherein the second gallium nitride (140) is allowed to grow using the Ga surface (112) of the first gallium nitride (110) as a nucleation layer (115).

Description

Field of invention

[0001] The present invention relates to a method for producing a gallium nitride substrate using a plurality of ion implantation methods and in particular a method for producing a high-quality gallium nitride substrate with low defect density by preventing the gallium nitride substrate from bending and cracking. Description of the related prior art

[0002] The performance and lifetime of semiconductor devices, such as laser diodes and light-emitting diodes, are determined by various factors that constitute the device and are particularly influenced by the base substrate on which the elements are stacked. Several methods for fabricating a high-quality semiconductor substrate have been proposed. Furthermore, interest in III-V compound semiconductor substrates is increasing.

[0003] A gallium nitride (GaN) substrate is a typical group III-V compound semiconductor substrate. Along with GaAs and InP substrates, GaN is a suitable choice for semiconductor devices. However, the manufacturing costs of GaN substrates are significantly higher than those of GaAs or InP substrates.

[0004] Crystal growth rates in GaN substrates are slow because crystal growth is achieved through vapor-phase processes such as hydride vapor deposition (HVPE) or metal-organic chemical vapor deposition (MOCVD). For example, only a crystalline GaN mass with a thickness of approximately 10 mm can be obtained in a crystal growth time of 100 hours. From a crystal of this thickness, only a small number of GaN substrates, e.g., 10 GaN substrates with a thickness of approximately 200 µm to 400 µm, can be produced.

[0005] However, if the thickness of GaN films cut from the crystalline GaN mass is reduced to obtain a greater number of GaN substrates, the mechanical strength decreases, making it impossible to form self-supporting substrates. Therefore, there was a need for a method capable of guaranteeing the strength of thin GaN films cut from a crystalline GaN mass.

[0006] Traditionally, a substrate fabrication process was used to bond a GaN thin film to a substrate with a different chemical composition to enhance the strength of the GaN thin film. However, bonded substrates produced using this method exhibited the problem that a substrate of a different type than the GaN thin film was easily detached from the GaN thin film during a process of laminating a semiconductor layer onto the GaN thin film.

[0007] To address these problems, JP 2011-243968.A, KR 101581044B1, and JP 2012-243792A proposed methods for thin-film separation by ion implantation. In such conventional thin-film separation methods using ion implantation, hydrogen, helium, or nitrogen ions are implanted into a surface of the crystalline GaN mass to bond with a substrate of a different type to form a damaged layer. The crystalline GaN mass, including the damaged layer formed on it, is then directly bonded to the substrate and subjected to heat treatment. Following this, the crystalline GaN mass on the damaged layer is removed to produce a substrate bonded to a thin GaN film.

[0008] However, conventional methods damage crystals within the crystalline GaN mass, leading to visible deformations such as bending. Furthermore, since crystalline GaN mass is impossible to recycle, manufacturing costs increase.

[0009] DE 10 2006 007 293 A1 describes a method for producing a quasi-substrate wafer and a semiconductor body produced using such a quasi-substrate wafer.

[0010] EP 2 157 602 A1 describes a method for producing a large number of gallium nitride wafers.

[0011] O. Moutanabbir (Moutanabbir, O. [et al.]: Stress adjustment and bonding of H-implanted 2 in. freestanding GaN wafer: The concept of double-sided splitting. In: Electrochemical and Solid-State Letters (ESL), VOL. 12, 2009, No. 4, pp. H105-H108. - ISSN 1099-0062 (P); 1944-8775 (E). DOI: 10.1149 / 1.3066081) also proposed a method for producing a GaN substrate in which hydrogen ions are implanted into both sides of a GaN substrate to reduce the deflection of a GaN substrate. However, this method revealed the problem that multiple layers of a GaN substrate can be damaged by hydrogen ions implanted on both sides of the GaN substrate, thus degrading the quality of the GaN substrate. Additionally, the method demonstrated the complexity of the process, as thermal annealing is performed after ion implantation. Summary of the invention

[0012] Therefore, the present invention was made with regard to the above problems, and it is an object of the present invention to provide a method for producing a gallium nitride substrate characterized in that a first ion implantation is carried out at least once to reduce the bending of the first gallium nitride and then a second ion implantation is carried out to address the bending and cracking of the gallium nitride substrate, which are the main factors influencing the production yield.

[0013] A further object of the present invention is to provide a method for producing a high-quality gallium nitride substrate with low defect density in order to prevent both a deflection phenomenon and a cracking phenomenon of a gallium nitride substrate.

[0014] A further object of the present invention is to provide a method for producing a gallium nitride substrate characterized in that a second gallium nitride, used as a seed layer, is enabled to grow on a Ga surface of the first gallium nitride in order to reduce a defect ratio of a gallium nitride substrate.

[0015] According to one aspect of the present invention, the above and other problems can be solved by providing a method for producing a gallium nitride substrate, the method comprising a step of forming a bonding oxide film on the first gallium nitride; a step of performing a first ion implantation at least once on a surface of the first gallium nitride on which the bonding oxide film is formed to form a damaged layer, thereby canceling any deflection of the first gallium nitride; a step of performing a second ion implantation on the surface of the first gallium nitride on which the bonding oxide film is formed to form a blister layer; a step of bonding the bonding oxide film of the first gallium nitride to a temporary substrate; and a step of separating the first gallium nitride using the blister layer to form a nucleation layer.and a step to enable the growth of the second gallium nitride using the nucleation layer to form gallium nitride in bulk;

[0016] In the formation step, the thickness of the damaged layer is controlled according to an accelerating voltage of the first ion implantation.

[0017] The curvature of the first gallium nitride can be controlled according to the thickness of the damaged layer.

[0018] The blister layer is formed at a depth of 0.1 µm to 4 µm from the surface of the first gallium nitride.

[0019] Ion implantation for the bladder layer can be performed using at least one of hydrogen, helium, nitrogen and argon.

[0020] The first gallium nitride comprises an N-face and a Ga-face.

[0021] In the step of performing the second ion implantation, the bubble layer is formed on the Ga surface of the first gallium nitride.

[0022] In the step of performing the second ion implantation, a heat treatment is also carried out on the bladder layer.

[0023] The heat treatment is carried out at temperatures between 400°C and 800°C.

[0024] The joining process can be carried out for 5 hours at 200°C to 450°C.

[0025] In the step of enabling growth, the temporary substrate can be further removed. The temporary substrate can consist of an amorphous thin film on one of its surfaces.

[0026] The amorphous thin film can consist of at least one of silicon dioxide (SiO₂). x ), silicon nitride (SiN x ) and silicon oxynitride (SiON).

[0027] The temporary substrate can be at least one of sapphire, gallium arsenide (GaAs), spinel, silicon (Si), indium phosphide (InP) and silicon carbide (SiC). Brief description of the drawings

[0028] The above and other tasks, features and other advantages of the present invention will be better understood from the following detailed description in conjunction with the accompanying drawings, in which: Fig. Figures 1a to 1h are sectional views illustrating a method for producing a gallium nitride substrate according to an embodiment of the present invention; Fig. 2 a transmission electron microscope (TEM) image of first gallium nitride illustrated, implanted into a Ga surface of first gallium nitride by first ion implantation according to a method for producing a gallium nitride substrate according to an embodiment of the present invention; Fig.3a is a graph representing the thickness of a damaged layer, which depends on an accelerating voltage of the first ion implantation, according to a method for producing a gallium nitride substrate according to an embodiment of the present invention; Fig. 3b is a graph representing a curvature rate (Δ deflection of a GaN wafer) that depends on the thickness of a damaged layer of the first gallium nitride produced according to a method for producing a gallium nitride substrate according to an embodiment of the present invention; Fig. 4 is a graph showing a vacancy concentration as a function of depth of a surface of a Ga surface of the first gallium nitride that has been subjected to a first ion implantation according to a method for producing a gallium nitride substrate according to an embodiment of the present invention; Fig.5. A TEM image and a graph are shown, representing the amount of implanted ions and the amount of vacancies in the first gallium nitride, which are formed by performing a second ion implantation into a Ga surface of first gallium nitride according to a method for producing a gallium nitride substrate according to an embodiment of the present invention; and Fig. Figure 6 illustrates a TEM image of a gallium nitride substrate produced by a method for producing a gallium nitride substrate according to an embodiment of the present invention. Detailed description of the invention

[0029] The present invention will now be described in more detail with reference to the accompanying drawings and the contents disclosed therein. However, the present invention should not be interpreted as being limited to the exemplary embodiments described herein.

[0030] The terms used in this description are employed to explain a specific exemplary embodiment and not to limit the present inventive concept. Thus, the term singularity in this description includes the term plural unless otherwise specified in the context. It is further understood that the terms "comprise" and / or "comprising," when used in this description, specify the presence of the indicated components, steps, operations, and / or elements, but do not exclude the presence or addition of any such components, steps, operations, and / or elements thereof.

[0031] It should not be understood that arbitrary aspects or designs revealed in “forms of execution”, “examples”, “aspects”, etc., used in the description are more satisfactory or advantageous than other aspects or designs.

[0032] Furthermore, the expression "or" means "inclusive or" and not "exclusive or". That is, unless otherwise stated or clearly inferred from the context, the expression "x uses a or b" means any of the natural inclusive permutations.

[0033] As used in the description of the invention and the attached claims, the singular forms “ein”, “eine” and “der / das / die” are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0034] Although the terms used in this description are selected from those commonly used in related technical fields, other expressions may be used in accordance with technical developments and / or due to changes, practices, priorities of engineers, etc. Therefore, these terms should not be understood as limiting the technical concept of the present invention, but rather as serving as examples to describe embodiments of the present invention.

[0035] Furthermore, some of the terms used herein may be arbitrarily chosen by the applicant. In this case, these terms are defined in more detail below. Accordingly, the specific terms used herein should be understood based on their unambiguous meanings and the overall context of the present invention.

[0036] Terms such as "first" and "second" are used here merely to describe a multitude of constituent elements, but the constituent elements are not limited by these expressions. The terms are used only to distinguish one constituent element from another.

[0037] When an element such as a layer, film, area, or component is described as being "on" another element, the element may be directly on top of another element, or an intervening element may be present. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meanings as they are commonly understood by a person skilled in the art. Furthermore, it is understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and the present invention, and should not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0038] However, in the following description of the present invention, a detailed description of the known functions and configurations contained herein is omitted where this might render the subject matter of the present invention unclear. The terms used in the description are defined with regard to functions employed in the present invention and may be modified according to the intended or conventionally used methods of customers, operators, and users. Accordingly, definitions of terms should be understood based on the entirety of the present description.

[0039] Below, a process for producing a gallium nitride substrate according to an embodiment of the present invention is described in detail with reference to the Fig. Described in sections 1a to 1h.

[0040] Fig.Figures 1a to 1h are sectional views illustrating a method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0041] The method for producing a gallium nitride substrate according to an embodiment of the present invention is characterized in that a binding oxide film 120 is formed on the first gallium nitride 110 and a first ion implantation is carried out for a surface of the first gallium nitride 110 on which the binding oxide film 120 has been formed at least once, in order to form a damaged layer 113, thereby reducing deflection of the first gallium nitride 110.

[0042] Subsequently, the surface of the first gallium nitride 110, on which the binding oxide film 120 has been formed, is subjected to a second ion implantation, thereby forming a bubble layer 114.

[0043] The bonding oxide film 120 of the first gallium nitride 110 is connected to a temporary substrate 130, and the first gallium nitride 110 is separated from it using the blister layer 114, thereby forming a nucleation layer 115. Subsequently, the second gallium nitride 140 can grow using the nucleation layer 115, thereby forming bulk gallium nitride (bulk GaN).

[0044] The method for producing a gallium nitride substrate according to an embodiment of the present invention is characterized in that the first ion implantation is performed on a surface of the first gallium nitride 110 at least once before the second ion implantation is carried out in order to form a damaged layer 113, thereby eliminating any deflection of the first gallium nitride 110. Accordingly, a high-quality gallium nitride substrate with low defect density can be produced, taking into account the curvature and cracking of a gallium nitride substrate as key factors influencing production yield.

[0045] The process for producing a gallium nitride substrate according to an embodiment of the present invention is described in detail below with reference to the Fig. Described in sections 1a to 1h.

[0046] Fig.Figure 1a is a sectional view illustrating a process for forming the first gallium nitride according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0047] Gallium nitride (GaN) is used as a core material for various optical devices due to its excellent physical and chemical properties. Gallium nitride can be grown on a substrate such as sapphire, silicon carbide, or silicon by heterogeneous epitaxial growth.

[0048] In addition, gallium nitride has an important crystalline property, i.e., “crystal polarity”, as well as defects.

[0049] In gallium nitride (e.g. wurtzite gallium nitride), each gallium atom is tetrahedrally coordinated to four nitrogen atoms.

[0050] If three strong bonds between each gallium (Ga) atom and three adjacent nitrogen (N) atoms closest to the gallium (Ga) atom are directed downwards towards a growth substrate, the polarity is +c (also known as the Ga face). If three strong bonds between each gallium (Ga) atom and three adjacent nitrogen (N) atoms closest to the gallium (Ga) atom are directed upwards in a growth direction, the polarity is -c (also known as the N face), opposite to +c.

[0051] Therefore, gallium nitride can be classified into a Ga-face type and an N-face type according to the orientations of the atoms that form the same (N-face). Here, the label "c" denotes a crystal plane that is horizontal to a plane of an epitaxial film.

[0052] Although polarity is not a surface property of gallium nitride, it should be noted that polarity strongly influences its bulk properties. Furthermore, the properties of gallium nitride can be varied depending on its polarity. Therefore, a device can be fabricated using the polarity properties of an epitaxial gallium nitride growth layer.

[0053] For example, in many cases it is preferred to use layers with a Ga surface in the production of gallium nitride components.

[0054] The first gallium nitride 110 used in the process for producing a gallium nitride substrate according to an embodiment of the present invention comprises a Ga surface 112 and an N surface 111.

[0055] Since the method for producing a gallium nitride substrate according to an embodiment of the present invention uses the first gallium nitride 110 including the Ga surface 112 as a seed layer to enable the growth of the second gallium nitride, a defect ratio of one gallium nitride substrate can additionally be reduced.

[0056] Although it is ideal for the first gallium nitride 110 to have a flat structure without bending, the commonly used gallium nitrides additionally have a convex or concave structure that is bent upwards or downwards.

[0057] When the first gallium nitride 110, which has a curved structure like in Fig. When 1a is used, the defect density increases, which degrades the quality of a gallium nitride substrate.

[0058] Therefore, the method for producing a gallium nitride substrate according to an embodiment of the present invention is characterized in that the first ion implantation for the first gallium nitride 110 is carried out at least once to eliminate any bending.

[0059] Fig. 1b and Fig. Figure 1c shows sectional views of a process whereby deflection of the first gallium nitride is eliminated by performing the first ion implantation for a surface of the first gallium nitride at least once to form a damaged layer according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0060] According to the method for producing a gallium nitride substrate according to an embodiment of the present invention, the damaged layer 113 on the first gallium nitride 110 is formed by the first ion implantation, as shown in Fig. 1a shown.

[0061] In particular, the bond oxide film 120 can be formed on the first gallium nitride 110, as shown in Fig. 1a shown.

[0062] The bond oxide film 120 can be made from silicon dioxide (SiO₂). x ) or aluminum oxide (Al2O3).

[0063] The method for producing a gallium nitride substrate according to an embodiment of the present invention is characterized in that the first ion implantation for a surface of the first gallium nitride 110, on which the binding oxide film 120 has been formed, is carried out at least once in order to form the damaged layer 113, thereby eliminating the deflection of the first gallium nitride 110.

[0064] The first ion implantation can be performed at least once. If the first ion implantation is performed multiple times, the accelerating voltage can be controlled differently.

[0065] Additionally, ions of at least one of hydrogen, helium, nitrogen, and argon can be used for the first ion implantation. Preferably, the first ion implantation is performed using hydrogen ions.

[0066] When an ion implantation is performed once for the first gallium nitride 110 to form the damaged layer 113 according to the method for producing a gallium nitride substrate according to an embodiment of the present invention, an ion implantation layer can be formed to a large extent.

[0067] If the ion implantation for the first gallium nitride 110 is performed several times to form the damaged layer 113, the ion implantation is concentrated on a first implanted ion implantation layer, thereby enabling the uniform formation of an ion implantation layer.

[0068] The in Fig. The damaged layer 113 shown in Figure 1b can contain multiple vacancies due to gas bubbles generated within the first gallium nitride 110. According to the method for producing a gallium nitride substrate according to an embodiment of the present invention, artificial damage can be created within the first gallium nitride 110 due to the multiple vacancies of the damaged layer 113, and the first gallium nitride 110 with a convex or concave structure is flattened by eliminating any deflection of the first gallium nitride 110.

[0069] According to the method for producing a gallium nitride substrate according to an embodiment of the present invention, the first ion implantation can be carried out in a convex part of the first gallium nitride 110.

[0070] The damaged layer 113 can be formed by performing the initial ion implantation of the first gallium nitride 110 at an accelerating voltage of 10 keV to 200 keV. If the accelerating voltage is 10 keV or less, the thickness of the damaged layer 113 will be too thin. Consequently, the deflection of the first gallium nitride 110 may not be sufficiently corrected. If the accelerating voltage is greater than 200 keV, the thickness of the damaged layer 113 will be too thick, and the first gallium nitride 110 may deflect in the opposite direction.

[0071] Additionally, the thickness of the damaged layer 113 can be controlled according to an accelerating voltage of the first ion implantation. Furthermore, the curvature of the first gallium nitride 110 can be controlled according to the thickness of the damaged layer 113.

[0072] The thickness of the damaged layer 113 increases with increasing acceleration voltage of the first ion implantation and a curvature rate of the first gallium nitride 110 increases with increasing thickness of the damaged layer 113.

[0073] The curvature rate refers to a curvature difference between an initial first gallium nitride 110 and a first gallium nitride 110 after diffraction has been canceled.

[0074] As in Fig.As shown in Figure 1c, the first gallium nitride 110, freed from diffraction, can be obtained by controlling an accelerating voltage of the first ion implantation as a function of a degree of curvature of the initial first gallium nitride 110.

[0075] In the process for producing a gallium nitride substrate according to one embodiment of the present invention, the angle of the first ion implantation is not specifically limited, and the first ion implantation for the first gallium nitride 110 can be carried out at an angle of 0° to 7°. Preferably, a channeling effect can be minimized by irradiating the first gallium nitride 110 with ions at an inclination of 7 degrees.

[0076] Fig.Figure 1d is a sectional view illustrating a process for performing the second ion implantation for a surface of the first gallium nitride 110 on which the binding oxide film 120 is formed, to form a blister layer according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0077] According to the method for producing a gallium nitride substrate according to an embodiment of the present invention, the second ion implantation is carried out for a surface of the first gallium nitride 110 on which the binding oxide film 120 is formed, thereby forming the bubble layer 114.

[0078] By the second ion implantation of the method for producing a gallium nitride substrate according to an embodiment of the present invention, gas bubbles are generated within the first gallium nitride 110 to form the bubble layer 114 with multiple vacancies.

[0079] The second ion implantation of the method for producing a gallium nitride substrate according to an embodiment of the present invention can be carried out for the Ga surface 112 of the first gallium nitride 110.

[0080] The bubble layer 114 can be formed by performing the second ion implantation on the first gallium nitride 110 with an accelerating voltage of 10 keV to 500 keV. If the accelerating voltage is 10 keV or less, the ion implantation will be insufficient, and the first gallium nitride 110 will not be separated. If the accelerating voltage is greater than 500 keV, the thickness of the bubble layer 114 will be too high, which may increase the number of defects in the first gallium nitride 110.

[0081] Additionally, the second ion implantation can be performed using ions of at least one of hydrogen, helium, nitrogen, and argon. Preferably, the second ion implantation is performed using hydrogen ions.

[0082] In addition, according to the method for producing a gallium nitride substrate according to an embodiment of the present invention, the second ion implantation for the first gallium nitride 110 is carried out at an accelerating voltage that is lower than that of the first ion implantation, thereby forming the bubble layer 114.

[0083] The depth of an ion-implanted layer of the first gallium nitride 110 can be controlled according to the magnitude of an accelerating voltage. If the accelerating voltage is high, the ion-implanted layer is formed at a deeper position of the gallium nitride 110, and if the accelerating voltage is low, the ion-implanted layer is formed at a shallower position of the gallium nitride 110.

[0084] Accordingly, during the second ion implantation, following the procedure for preparing a gallium nitride substrate, the bubble layer 114 is formed in a flat position from the surface of the first gallium nitride 110 to form a thin nucleation layer. The second ion implantation is therefore performed at a lower accelerating voltage than the first ion implantation.

[0085] Since, on the other hand, the first ion implantation for the first gallium nitride 110 is performed to eliminate a deflection, it is carried out at a higher accelerating voltage than that of the second ion implantation. Accordingly, the damaged layer 113 is formed in a deeper position.

[0086] In the process for producing a gallium nitride substrate according to one embodiment of the present invention, the angle of the second ion implantation is not specifically limited, and the second ion implantation for the first gallium nitride 110 can be carried out at an angle of 0° to 7°. Preferably, the channeling effect can be minimized by irradiating the first gallium nitride 110 with ions at an inclination of 7 degrees.

[0087] According to one embodiment, the blister layer 114 can be formed at a depth of 0.1 µm to 4 µm from the surface of the first gallium nitride 110.

[0088] If the depth of the blister layer 114 is shallow, i.e., 0.1 µm or less, ion implantation will not be sufficient. Consequently, the first gallium nitride 110 may not be separated. If the depth of the blister layer 114 is greater than 4 µm, defects in the first gallium nitride 110 may increase due to the excessive thickness of the blister layer 114.

[0089] The method for producing a gallium nitride substrate according to an embodiment of the present invention may further comprise, after carrying out the second ion implantation for the first gallium nitride 110 from the bubble layer 114, a process for heat treatment of the bubble layer 114.

[0090] The heat treatment can be carried out at a temperature at which the first gallium nitride 110 is not separated by the bubble layer 114, or at a lower temperature at which the first gallium nitride 110 is separated in order to relieve any stress on the first gallium nitride 110 caused by the first and second ion implantation, and to ensure effective ion implantation into the first gallium nitride 110.

[0091] For example, the heat treatment can be carried out at 400 °C to 800 °C. If the heat treatment temperature is 400 °C or less, the stress of the first gallium nitride 110 is not sufficiently reduced, and if the heat treatment temperature is higher than 800 °C, the first gallium nitride 110 can be separated by the blister layer 114.

[0092] Fig.Figure 1e is a sectional view illustrating a process for bonding the bonding oxide film 120 of the first gallium nitride 110 to the temporary substrate 130 according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0093] The method for producing a gallium nitride substrate according to an embodiment of the present invention comprises a method for joining the temporary substrate 130 in order to separate the blister layer 114 of the first gallium nitride 110 in a subsequent process.

[0094] For example, the method for producing a gallium nitride substrate according to an embodiment of the present invention may comprise a method for bonding the first gallium nitride 110 to the temporary substrate 130 using the bonding oxide film 120 formed on the surface of the first gallium nitride, as shown in Fig. 1e shown.

[0095] According to one embodiment, the first gallium nitride 110 can be bonded to the temporary substrate 130 by heat or pressure. Preferably, the temporary substrate 130 can be bonded by holding the first gallium nitride 110 at 200 °C to 450 °C for 5 hours.

[0096] If the temperature used to join the temporary substrate 130 with the first gallium nitride 110 is too high, defects (e.g., cleavage) may occur before joining.

[0097] The temporary substrate 130 can be at least one of sapphire, gallium arsenide (GaAs), spinel, silicon (Si), indium phosphide (InP) and silicon carbide (SiC).

[0098] According to one embodiment, the temporary substrate 130 can contain an amorphous thin film on one of its surfaces. The amorphous thin film can consist of at least one silicon oxide (SiO₂). x ), silicon nitride (SiN x ) and silicon oxynitride (SiON).

[0099] Fig. Figure 1f is a sectional view illustrating a process for separating the first gallium nitride 110 according to the method for producing a gallium nitride substrate according to an embodiment of the present invention in order to form the nucleation layer 115.

[0100] In the process for producing a gallium nitride substrate according to an embodiment of the present invention, the temporary substrate 130 is separated from the first gallium nitride 110 using the blister layer 114 by a heat treatment process or a mechanical process (e.g. cutting), thereby forming the nucleation layer 115.

[0101] Additionally, in the process for producing a gallium nitride substrate according to an embodiment of the present invention, the first gallium nitride 110 can be removed from the bubble layer 114 by crystal rearrangement and bubble coagulation in the bubble layer 114 by heat-treating the temporary substrate 130.

[0102] Heat treatment can be used when the ionic bubble layer 114 forms at a relatively shallow position within the first gallium nitride 110. By heat-treating the first gallium nitride 110 and the temporary substrate 130, which are bonded together, the ionic bubble layer 114 becomes brittle, and the first gallium nitride 110 is separated from the embrittled ionic bubble layer 114, leaving the nucleated layer 115. The heat treatment can be carried out at temperatures between 400 °C and 800 °C, depending on the properties of the ions.

[0103] In the process for producing a gallium nitride substrate according to one embodiment of the present invention, the first gallium nitride 110 may not separate if the heat treatment is carried out at less than 400 °C. On the other hand, the first gallium nitride 110 may separate earlier if the heat treatment is carried out at more than 800 °C, which affects the yield.

[0104] Additionally, in the process for producing a gallium nitride substrate according to one embodiment of the present invention, a mechanical method can be used if the bubble layer 114 is formed in a relatively deep position. This mechanical method also exhibits excellent precision, can be easily carried out, and can ensure separation of the first gallium nitride 110.

[0105] According to the method for producing a gallium nitride substrate according to an embodiment of the present invention, the first gallium nitride 110 can be separated after the second ion implantation by the aforementioned heat treatment method or mechanical method, thereby obtaining the nucleation layer 115 with a flat separation surface.

[0106] Fig. Figure 1g is a sectional view illustrating a method for enabling the growth of the second gallium nitride 140 according to the method for producing a gallium nitride substrate according to an embodiment of the present invention in order to mass-produce gallium nitride.

[0107] Referring to Fig.1g of the second gallium nitride 140 can grow on the nucleation layer 115 formed on the temporary substrate 130 to mass-produce the gallium nitride according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0108] In the process for producing a gallium nitride substrate according to an embodiment of the present invention, the second gallium nitride 140 can be grown using any hydride vapor phase epitaxy (HVPE), metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), sublimation and liquid phase processes, such as a flux process and a high nitrogen pressure solution process.

[0109] In the process for producing a gallium nitride substrate, the second gallium nitride 140 is grown using the Ga surface 112 of the first gallium nitride 110 as a nucleation layer 115, thereby reducing a defect ratio in the gallium nitride substrate.

[0110] Fig. Figure 1h is a sectional view showing a gallium nitride substrate produced by the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0111] Referring to Fig. 1h a gallium nitride substrate 100 with a self-supporting structure can be produced by removing the temporary substrate 130 and the binding oxide film 120 according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0112] A gallium nitride substrate with a template substrate structure can be produced by terminating a process without removing the temporary substrate 130 after the growth of the second gallium nitride 140, as shown in Fig. 1g shown, according to an embodiment of the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0113] The properties of the gallium nitride substrate produced by the process for producing a gallium nitride substrate according to an embodiment of the present invention are described in detail below with reference to Fig. 2 to Fig. 5b described.

[0114] Fig.Figure 2 illustrates a transmission electron microscope (TEM) image of the first gallium nitride implanted into a Ga surface of the first gallium nitride by first ion implantation according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0115] Referring to Fig. 2. The first gallium nitride with a Ga face and an N face, as in Fig. 1a shown, undergoing the first ion implantation, as in Fig. Figure 1b shows a damaged layer with a thickness of 234 nm.

[0116] Additionally, a degree of curvature of the initial first gallium nitride, as in Fig. 1a shown, -12 µm, but a first gallium nitride canceled by diffraction, as in Fig. Figure 1c shows the formation of a damaged layer with a thickness of 234 nm in the first gallium nitride, as shown in Fig.1b was represented with a degree of curvature of +19 µm and thus had a curvature rate of + 31.

[0117] Fig. Figure 3a is a graph illustrating the thickness of a damaged layer, which depends on an accelerating voltage of the first ion implantation, according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0118] Referring to Fig. 3a can be confirmed that the thickness of the damaged layer is changed according to an accelerating voltage of the first ion implantation in the process for producing a gallium nitride substrate according to an embodiment of the present invention.

[0119] Fig.Figure 3b is a graph representing a curvature rate (Δ deflection of a GaN wafer) that depends on the thickness of a damaged layer of the first gallium nitride produced according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0120] Referring to Fig. 3b it can be confirmed that a curvature rate of the first gallium nitride depends on the thickness of the damaged layer produced by the first ion implantation in the process for producing a gallium nitride substrate according to an embodiment of the present invention.

[0121] The curvature rate refers to a curvature difference between an initial first gallium nitride and a first gallium nitride after diffraction has been canceled.

[0122] With reference to Fig. 3a and Fig.3b The curvature of the first gallium nitride can be easily controlled by adjusting the accelerating voltage of the first ion implantation according to the degree of curvature of the initial first gallium nitride, as shown in Fig. 3 shown.

[0123] Fig. Figure 4 is a graph showing a vacancy concentration as a function of depth from a surface of a Ga area of ​​the first gallium nitride that was subjected to a first ion implantation, according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0124] Referring to Fig.4. The first ion implantation for the Ga surface of the first gallium nitride was carried out at respective accelerating voltages of 36 keV, 53 keV, and 70 keV according to the method for producing a gallium nitride substrate according to an embodiment of the present invention. Additionally, the first ion implantation for the Ga surface of the first gallium nitride was performed three times (3-stage H + - Implantation) was performed at respective acceleration voltages of 36 keV, 53 keV and 70 keV.

[0125] Referring to Fig. 4. It can be confirmed that the vacancy concentration of the damaged layer increases with increasing acceleration voltage of the first ion implantation in the process for producing a gallium nitride substrate according to an embodiment of the present invention.

[0126] The following Table 1 shows a bending rate (Δbending) according to an acceleration voltage of the first ion implantation according to the method for producing a gallium nitride substrate according to an embodiment of the present invention. [Table 1] Allium nitride (GaN) substrates Bending Curvature rate (Δbending) Thickness of the gallium nitride (GaN) substrate: 368 µm After the laser lift-off -180 µm - First ion implantation at an acceleration voltage of 36 keV -177 µm + 3 µm First ion implantation at an acceleration voltage of 53 keV -170 µm +7 µm First ion implantation at an acceleration voltage of 70 keV -142 µm. +28 µm Perform the first ion implantation three times (at respective voltages of 36 keV, 53 keV and 70 keV) + 38 µm

[0127] Referring to Table 1, the curvature rate was +3 µm when the first ion implantation was performed at an accelerating voltage of 36 keV, the curvature rate was +7 µm when the first ion implantation was performed at an accelerating voltage of 53 keV, the curvature rate was +28 µm when the first ion implantation was performed at an accelerating voltage of 70 keV, and the curvature rate was +38 µm when the first ion implantation for the Ga surface of the first gallium nitride was performed at accelerating voltages of 36 keV, 53 keV and 70 keV, i.e. three times.

[0128] These results confirm that the curvature rate increases with increasing acceleration voltage of the first ion implantation in the process for producing a gallium nitride substrate according to an embodiment of the present invention.

[0129] Additionally, it can be confirmed that the thickness of the damaged layer continues to increase when the first ion implantation is performed three times while the accelerating voltage is increased.

[0130] Fig. Figure 5 is a TEM image and a graph representing the amount of implanted ions and the amount of vacancies in first gallium nitride, which is formed by performing a second ion implantation into a Ga surface of first gallium nitride according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0131] According to the second ion implantation of the method for producing a gallium nitride substrate according to an embodiment of the present invention, ions were implanted in an amount of 1.3 × 10 17 H2 + / cm 2 The gallium nitride was implanted using an energy of 70 keV, forming a bubble layer 286 nm thick. Additionally, the first gallium nitride was heat-treated at 500 °C for 30 minutes after the second ion implantation.

[0132] Referring to Fig. 5. A bubble layer with a thickness of approximately 300 nm was formed within the first gallium nitride by the second ion implantation according to the method for producing a gallium nitride substrate according to an embodiment of the present invention. Accordingly, the number of ions and vacancies in the bubble layer increased.

[0133] It can be confirmed that the bubble layer, in which several vacancies are formed, is satisfactorily formed within the first gallium nitride by the second ion implantation according to the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0134] Fig. Figure 6 illustrates a TEM image of a gallium nitride substrate produced by the method for producing a gallium nitride substrate according to an embodiment of the present invention.

[0135] Referring to Fig.In step 6, gallium nitride was grown on a silicon oxide layer formed on a sapphire substrate, and the resulting gallium nitride substrate showed no deflection or cracking. As a result, the fabrication of a high-quality, low-defect gallium nitride substrate, while addressing both deflection and cracking, was successfully completed.

[0136] According to one embodiment of the present invention, a gallium nitride substrate is provided, wherein the bending of the first gallium nitride is reduced by performing a first ion implantation at least once, and then the bending and tearing of the gallium nitride substrate, which are the main factors influencing the production yield, are addressed with a second ion implantation.

[0137] In addition, according to one embodiment of the present invention, a high-quality gallium nitride substrate with low defect density can be produced by preventing both a deflection phenomenon and a cracking phenomenon of the gallium nitride substrate.

[0138] According to one embodiment of the present invention, a gallium nitride substrate with a reduced defect ratio can be provided by growing a second gallium nitride, which is used as a seed layer, on a Ga surface of the first gallium nitride. [Description of reference symbols] 100 GALLIUM NITRIDE SUBSTRATE 110 FIRST GALLIUM NITRIDE 111 N-AREA 112 Ga-AREA 113 DAMAGED SHIFT 114 BUBBLE LAYER 115 Germination Layer 120 Bonding Oxide Film 130 TEMPORARY SUBSTRATE 140 SECOND GALLIUM NITRIDE

Claims

[1] Method for producing a gallium nitride substrate (100), the method comprising: Formation of a bond oxide film (120) on a first gallium nitride (110); Performing a first ion implantation for a surface of the first gallium nitride (110) on which the bonding oxide film (120) is formed, at least once, to form a damaged layer (113), thereby canceling any deflection of the first gallium nitride (110); Performing a second ion implantation for the surface of the first gallium nitride (110) on which the bonding oxide film (120) is formed, in order to form a blister layer (114); Connecting the bonding oxide film (120) of the first gallium nitride (110) to a temporary substrate (130); Separation of the first gallium nitride (110) using the vesicle layer (114) to form a nucleation layer (115); and Enabling the growth of a second gallium nitride (140) using the nucleation layer (115) to form gallium nitride in bulk, wherein, during the formation of the damaged layer (113), the thickness of the damaged layer (113) is controlled according to an accelerating voltage of the first ion implantation, wherein the second ion implantation is performed at an accelerating voltage that is lower than that of the first ion implantation, wherein the blister layer (114) is formed at a position which is closer to the surface of the first gallium nitride (110) on which the bonding oxide film (120) is formed, compared to a position of the damaged layer (113), wherein during the second ion implantation the bubble layer (114) is formed at a depth of 0.1 µm to 4 µm from the surface of the first gallium nitride (110), wherein a heat treatment at 400 °C to 800 °C is carried out for the bubble layer (114), wherein the first gallium nitride (110) comprises an N-surface (111) and a Ga-surface (112), wherein during the second ion implantation the blister layer (114) is formed on the Ga-surface (112) of the first gallium nitride (110), wherein the second gallium nitride (140) is allowed to grow using the Ga surface (112) of the first gallium nitride (110) as a nucleation layer (115). [2] Method according to claim 1, wherein the degree of curvature of the first gallium nitride (110) is controlled according to the thickness of the damaged layer (113). [3] Method according to claim 1, wherein the ion implantation for the bubble layer (114) is carried out using at least one of hydrogen, helium, nitrogen and argon. [4] Method according to claim 1, wherein the joining is carried out for 5 hours at 200 °C to 450 °C. [5] Method according to any one of claims 1 to 4, wherein the temporary substrate (130) is further removed. [6] Method according to claim 1, wherein the temporary substrate (130) comprises an amorphous thin film on a surface thereof. [7] Method according to claim 6, wherein the amorphous thin film comprises at least one of silicon oxide (SiO₂). x ), silicon nitride (SiN x ) and silicon oxynitride (SiON). [8] Method according to claim 1, wherein the temporary substrate (130) is at least one of sapphire, gallium arsenide (GaAs), spinel, silicon (Si), indium phosphide (InP) and silicon carbide (SiC).

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