Semiconductor structure and manufacturing method thereof

Abstract

The invention discloses a semiconductor structure and a manufacturing method thereof. The manufacturing method of the semiconductor structure comprises the following steps: forming a metal mask layer on one side of a substrate, wherein the metal mask layer is provided with an opening region; a first epitaxial layer is formed in the opening area, the first epitaxial layer comprises a first gallium nitride layer and a second gallium nitride layer which are arranged in a stacked mode, the second gallium nitride layer is located on the side, away from the substrate, of the first gallium nitride layer, and the atomic percent of gallium and nitrogen in the second gallium nitride layer is larger than that of gallium and nitrogen in the first gallium nitride layer; and forming a second epitaxial layer on one side, far away from the substrate, of the first epitaxial layer, wherein the second epitaxial layer and the first epitaxial layer form a light-emitting unit. According to the invention, the stripping difficulty of the light-emitting unit can be reduced, the transfer yield of the light-emitting unit is improved, the repair number of the light-emitting unit after transfer is reduced, the repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit is reduced.

Description

Technical Field

[0001] Embodiments of the present invention relate to the technical field of semiconductor optoelectronic devices, and in particular, to a semiconductor structure and a manufacturing method thereof. Background Art

[0002] Micro-LED, that is, a micro light-emitting diode, is an LED whose size is further reduced to the micron level based on the traditional light-emitting diode (LED). As a new generation of core display technology, Micro-LED has excellent characteristics such as low power consumption, high integration, high display effect, and long lifespan, making it show a booming development trend.

[0003] During the massive transfer process of Micro-LED, the peeling process of Micro-LED is prone to causing damage to Micro-LED, resulting in a relatively low peeling yield of Micro-LED, and further causing high transfer difficulty of Micro-LED and high repair cost after Micro-LED is damaged. Summary of the Invention

[0004] The present invention provides a semiconductor structure and a manufacturing method thereof to achieve improving the transfer yield of light-emitting units and reducing the manufacturing cost of light-emitting units.

[0005] In a first aspect, an embodiment of the present invention provides a manufacturing method of a semiconductor structure, including:

[0006] Form a metal mask layer on one side of a substrate, and the metal mask layer has an opening area;

[0007] Form a first epitaxial layer in the opening area, the first epitaxial layer includes a first gallium nitride layer and a second gallium nitride layer arranged in a stacked manner, the second gallium nitride layer is located on a side of the first gallium nitride layer away from the substrate, and the atomic percentage of gallium and nitrogen in the second gallium nitride layer is greater than the atomic percentage of gallium and nitrogen in the first gallium nitride layer;

[0008] Form a second epitaxial layer on a side of the first epitaxial layer away from the substrate, and the second epitaxial layer and the first epitaxial layer form a light-emitting unit.

[0009] Optionally, forming the first epitaxial layer in the opening area includes:

[0010] In a first stage, form the first gallium nitride layer by using a first flow rate of a gallium source and a second flow rate of ammonia gas;

[0011] In a second stage, form the second gallium nitride layer by using a third flow rate of a gallium source and a fourth flow rate of ammonia gas; the ratio of the second flow rate to the first flow rate is less than the ratio of the fourth flow rate to the third flow rate.

[0012] Optionally, the ratio of the second flow rate to the first flow rate ranges from 500 to 1200.

[0013] Optionally, before forming the first epitaxial layer in the opening region, the method further includes:

[0014] forming a peeling structure in the opening region, the peeling structure including alternately arranged growth regions and non-growth regions;

[0015] Forming the first epitaxial layer in the opening region includes:

[0016] forming the first epitaxial layer in the growth regions.

[0017] Optionally, the metal mask layer further has a step, the step is disposed around the opening region, and when forming the first epitaxial layer and / or forming the second epitaxial layer, at least a part of the first epitaxial layer and / or the second epitaxial layer covers the surface of the step.

[0018] Optionally, the sum of the thicknesses of the first epitaxial layer and the second epitaxial layer is greater than the thickness of the step.

[0019] Optionally, forming a second epitaxial layer on a side of the first epitaxial layer away from the substrate includes:

[0020] forming a quantum well layer on a side of the first epitaxial layer away from the substrate;

[0021] forming an electron blocking layer on a side of the quantum well layer away from the substrate;

[0022] forming a conductive layer on a side of the electron blocking layer away from the substrate.

[0023] In a second aspect, an embodiment of the present invention further provides a method for manufacturing a semiconductor structure, including:

[0024] forming a metal mask layer on one side of a substrate, the metal mask layer having an opening region;

[0025] forming a peeling structure in the opening region, the peeling structure including alternately arranged growth regions and non-growth regions;

[0026] forming an epitaxial layer in the growth regions, the epitaxial layer forming a light-emitting unit.

[0027] In a third aspect, an embodiment of the present invention further provides a semiconductor structure formed by using the method for manufacturing a semiconductor structure described in the first aspect.

[0028] In a fourth aspect, an embodiment of the present invention further provides a semiconductor structure, including:

[0029] a substrate;

[0030] A metal mask layer is disposed on one side of the substrate, and the metal mask layer has an opening area;

[0031] A stripping structure is disposed on one side of the metal mask layer and is located in the opening area. The stripping structure includes alternately arranged growth areas and non-growth areas;

[0032] An epitaxial structure is disposed in the growth area, and the epitaxial structure forms a light-emitting unit.

[0033] In the technical solution of the embodiment of the present invention, by forming a first epitaxial layer in the opening area, the contact area between the first epitaxial layer and the film layer in contact with the side close to the substrate can be reduced, the contact area between the light-emitting unit and the film layer in contact with it can be reduced, so that the stripping difficulty of the light-emitting unit can be reduced, the transfer yield of the light-emitting unit can be improved, the number of repairs after the transfer of the light-emitting unit can be reduced, and thus the repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit can be reduced. At the same time, the first epitaxial layer includes a first gallium nitride layer and a second gallium nitride layer arranged in a stacked manner. The second gallium nitride layer is located on the side of the first gallium nitride layer away from the substrate. The atomic percentage of gallium and nitrogen in the second gallium nitride layer is greater than that in the first gallium nitride layer. Due to the insufficient supply of nitrogen atoms, tiny holes are formed on the surface of the first gallium nitride layer close to the substrate side, which can weaken the interfacial bonding force between the first gallium nitride layer and the film layer in contact with it, and thus it is easier to break the valence bond between the first gallium nitride layer and the film layer in contact with it. When the first epitaxial layer is stripped, the stripping difficulty of the first epitaxial layer can be further reduced, the transfer yield and repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit can be further reduced. Description of the Drawings

[0034] Figure 1 It is a flowchart of a manufacturing method of a semiconductor structure provided by an embodiment of the present invention;

[0035] Figure 2 It is a schematic structural diagram of a semiconductor structure in step S110 provided by an embodiment of the present invention;

[0036] Figure 3 It is a schematic structural diagram of a semiconductor structure in step S120 provided by an embodiment of the present invention;

[0037] Figure 4 It is a schematic structural diagram of a semiconductor structure in step S130 provided by an embodiment of the present invention;

[0038] Figure 5 It is a flowchart of another manufacturing method of a semiconductor structure provided by an embodiment of the present invention;

[0039] Figure 6Schematic diagram of a peeling structure provided by an embodiment of the present invention;

[0040] Figure 7 Schematic diagram of a semiconductor structure provided by an embodiment of the present invention;

[0041] Figure 8 Schematic diagram of another semiconductor structure provided by an embodiment of the present invention;

[0042] Figure 9 Schematic diagram of a semiconductor structure covered with a UV film provided by an embodiment of the present invention;

[0043] Figure 10 Schematic diagram of a structure in which a UV film adheres to a light-emitting unit for transfer provided by an embodiment of the present invention;

[0044] Figure 11 Schematic diagram of a structure in which local release of a light-emitting unit is achieved by local UV irradiation provided by an embodiment of the present invention;

[0045] Figure 12 Flow chart of a manufacturing method of another semiconductor structure provided by an embodiment of the present invention;

[0046] Figure 13 Schematic diagram of another semiconductor structure provided by an embodiment of the present invention. Detailed implementation manners

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention are shown in the accompanying drawings, rather than all structures.

[0048] Figure 1 Flow chart of a manufacturing method of a semiconductor structure provided by an embodiment of the present invention. This embodiment is applicable to the case of performing mass transfer on Micro-LEDs after fabricating Micro-LEDs on a substrate. This method can be executed by a manufacturing apparatus for a semiconductor structure, and the method includes:

[0049] S110. Form a metal mask layer on one side of the substrate, and the metal mask layer has an opening area;

[0050] Among them, the substrate is used to carry other film layers and epitaxially form light-emitting units. Exemplarily, the substrate can be silicon-based or sapphire-based. Before forming the metal mask layer on one side of the substrate, the surface of the substrate can be cleaned. A buffer layer, a U-shaped gallium nitride layer, and a first N-type gallium nitride layer (as the first N-type conductive layer) can also be epitaxially grown on the substrate. Exemplarily, on the cleaned sapphire substrate, a buffer layer including AlN and a superlattice composite buffer layer of AlN / AlGaN can be grown on the sapphire substrate by using the Metal-organic Chemical Vapor Deposition (MOCVD) process. The thickness of the AlN buffer layer can be 10 - 300 nm, the thickness of the AlN / AlGaN superlattice composite buffer layer can be 500 - 2000 nm, and the growth pressure is 100 - 500 Torr. After forming the buffer layer, a first N-type gallium nitride layer is grown as the first N-type conductive layer. The thickness of the first N-type conductive layer is 1 - 5 μm, and the silicon doping concentration therein is 5E18 - 9E19 / cm 2 .

[0051] Then, a metal mask layer is formed on the side of the first N-type gallium nitride layer away from the substrate. The material of the metal mask layer can be a metal, for example, at least one of Fe, Mn, Ni, and Ti. When forming the metal mask layer, a lithography process can be adopted, and metal coating equipment such as magnetron sputtering and electron beam evaporation can be used to prepare a periodic pattern so that the metal mask layer has an opening area. The pitch between the opening areas of the metal mask layer is 0.5 - 20 μm, and the height is 100 - 1000 nm. Figure 2 The structural schematic diagram of a semiconductor structure provided by an embodiment of the present invention in step S110. As Figure 2 shown, the metal mask layer 10 has an opening area 11, there is a step 12 between adjacent opening areas 11, the width b of the step 12 in the direction pointing to the opening area 11 is 3 μm, and the height h of the step 12 is 400 nm.

[0052] S120. Form a first epitaxial layer in the opening area. The first epitaxial layer includes a first gallium nitride layer and a second gallium nitride layer arranged in a stacked manner. The second gallium nitride layer is located on the side of the first gallium nitride layer away from the substrate, and the atomic percentage of gallium and nitrogen in the second gallium nitride layer is greater than that in the first gallium nitride layer;

[0053] Among them, Figure 3 The structural schematic diagram of a semiconductor structure provided by an embodiment of the present invention in step S120. As Figure 3As shown, the first epitaxial layer 20 can be a second N-type gallium nitride layer. The first epitaxial layer 20 is located within the opening region 11, such that the metal mask layer 10 defines the position of the first epitaxial layer 20 and reduces the contact area between the first epitaxial layer 20 and the film layer it contacts. When forming a light-emitting unit with the first epitaxial layer 20 and other epitaxial layers, the contact area between the light-emitting unit and the film layer it contacts can be reduced. Thus, when the light-emitting unit is peeled off, the peeling difficulty between the light-emitting unit and the film layer it contacts can be reduced, the transfer yield of the light-emitting unit can be improved, the number of repairs after the transfer of the light-emitting unit can be reduced, and further, the repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit can be reduced. Exemplarily, a first N-type gallium nitride layer 01 is provided on the substrate 00, and the metal mask layer 10 is disposed on the first N-type gallium nitride layer 01. The opening region 11 exposes the surface of a portion of the first N-type gallium nitride layer 01. When forming the first epitaxial layer 20 in the opening region 11, the first epitaxial layer 20 contacts the surface of the first N-type gallium nitride layer 01 within the opening region 11, reducing the contact area between the first epitaxial layer 20 and the first N-type gallium nitride layer 01. When subsequently peeling off the first epitaxial layer 20, the peeling difficulty between the first epitaxial layer 20 and the first N-type gallium nitride layer 01 can be reduced.

[0054] When forming the first epitaxial layer 20 in the opening region 11, different process conditions can be used to form the first gallium nitride layer and the second gallium nitride layer respectively. At this time, the semiconductor structure is a gallium nitride system. The first gallium nitride layer is located on the side closer to the substrate than the second gallium nitride layer. At the same time, on the side of the first gallium nitride layer closer to the substrate, the film layer material in contact with the first gallium nitride layer can be gallium nitride, such that on the side of the first gallium nitride layer closer to the substrate, a gallium nitride transistor bond is formed with the contacting film layer. When the gallium nitride crystal is cleaved, cleavage can be performed through the weakest bonded crystal planes, thereby breaking the valence bond between the first gallium nitride layer and the contacting film layer. The low-index crystal plane of gallium nitride is (0001), which is the growth direction of gallium nitride. When forming the first epitaxial layer 20, the atomic percentages of gallium and nitrogen in the second gallium nitride layer can be made greater than the atomic percentages of gallium and nitrogen in the first gallium nitride layer, such that the surface of the first gallium nitride layer closer to the substrate forms micro holes due to insufficient supply of nitrogen atoms, which can weaken the interfacial bonding force between the first gallium nitride layer and the contacting film layer, and further, the valence bond between the first gallium nitride layer and the contacting film layer can be more easily broken. When peeling off the first epitaxial layer 20, the peeling difficulty of the first epitaxial layer 20 can be further reduced, the transfer yield and repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit can be further reduced.

[0055] S130. Form a second epitaxial layer on the side of the first epitaxial layer away from the substrate, and the second epitaxial layer and the first epitaxial layer form a light-emitting unit.

[0056] Wherein, Figure 4A schematic structural diagram of a semiconductor structure provided in an embodiment of the present invention at step S130. After forming the first epitaxial layer 20, the second epitaxial layer 40 can be continuously formed on the first epitaxial layer 20 to complete the manufacturing process of the light-emitting unit. After forming the light-emitting unit, the light-emitting unit can be transferred to the array substrate by the mass transfer method to form a display device. Exemplarily, when the light-emitting unit is mass-transferred, the laser lift-off method can be used. The method mainly uses a laser to pass through the substrate, causing the interface of the first epitaxial layer 20 on the side close to the substrate to rapidly heat up and decompose into gallium metal and nitrogen, so that the separation of the first epitaxial layer 20 from the film layer in contact therewith can be realized.

[0057] The technical solution of this embodiment can reduce the contact area between the first epitaxial layer and the film layer in contact with the side close to the substrate by forming the first epitaxial layer in the opening area, reduce the contact area between the light-emitting unit and the film layer in contact therewith, thereby reducing the peeling difficulty of the light-emitting unit, improving the transfer yield of the light-emitting unit, reducing the number of repairs after the transfer of the light-emitting unit, and further improving the repair efficiency of the light-emitting unit and reducing the manufacturing cost of the light-emitting unit. At the same time, the first epitaxial layer includes a first gallium nitride layer and a second gallium nitride layer arranged in a stacked manner, the second gallium nitride layer is located on the side of the first gallium nitride layer away from the substrate, and the atomic percentage of gallium and nitrogen in the second gallium nitride layer is greater than that in the first gallium nitride layer, so that the surface of the first gallium nitride layer on the side close to the substrate forms micro-holes due to insufficient supply of nitrogen atoms, which can weaken the interfacial bonding force between the first gallium nitride layer and the film layer in contact therewith, and further make it easier to break the valence bond between the first gallium nitride layer and the film layer in contact therewith. When the first epitaxial layer is peeled off, the peeling difficulty of the first epitaxial layer can be further reduced, the transfer yield and repair efficiency of the light-emitting unit are improved, and the manufacturing cost of the light-emitting unit is further reduced.

[0058] In some embodiments, forming the first epitaxial layer in the opening area includes:

[0059] In the first stage, a first gallium nitride layer is formed by using a first flow rate of a gallium source and a second flow rate of ammonia gas;

[0060] Specifically, when forming the first epitaxial layer, the formation process of the first epitaxial layer can be divided into two stages for forming the first gallium nitride layer and the second gallium nitride layer respectively. By changing the ratio of the flow rate of the gallium source to the flow rate of ammonia in different stages, the flow rate ratio of ammonia to the gallium source in the first stage is made smaller than that in the second stage. Under the condition of the same number of gallium atoms, the number of N atoms in the first gallium nitride layer is less than that in the second gallium nitride layer, so that the atomic percentage of gallium and nitrogen in the second gallium nitride layer can be greater than that in the first gallium nitride layer. For example, when forming the first gallium nitride layer in the first stage, the first gallium nitride layer can be formed by using a gallium source with a first flow rate and ammonia with a second flow rate. In addition, the division of the first stage and the second stage can be determined according to the thickness of the first epitaxial layer and the growth rate of the thickness. Exemplarily, the thickness of the first epitaxial layer can be 100 - 400 nm, and the growth rate of the thickness of the first epitaxial layer can be 10 nm / min. At this time, the first stage can be set to be less than or equal to 2 minutes. For example, the first stage can be 45 s at the initial stage of growing the first epitaxial layer. The second stage is the remaining time other than the first stage in growing the first epitaxial layer.

[0061] In the second stage, the second gallium nitride layer is formed by using a gallium source with a third flow rate and ammonia with a fourth flow rate; the ratio of the second flow rate to the first flow rate is less than the ratio of the fourth flow rate to the third flow rate.

[0062] Specifically, when forming the second gallium nitride layer in the second stage, the second gallium nitride layer can be formed by using a gallium source with a third flow rate and ammonia with a fourth flow rate, and the ratio of the second flow rate to the first flow rate is less than the ratio of the fourth flow rate to the third flow rate, so that the atomic percentage of gallium and nitrogen in the second gallium nitride layer can be greater than that in the first gallium nitride layer. Exemplarily, when forming the second gallium nitride layer, the ratio range of the ammonia flow rate to the gallium source flow rate can be 1500 - 3000, that is, the V / III ratio of the process conditions when forming the second gallium nitride layer is 1500 - 3000. So that the second gallium nitride layer can be a conventional gallium nitride layer to ensure the requirements of the first epitaxial layer for the normal gallium nitride film layer. When forming the first gallium nitride layer, relative to the process conditions of the second gallium nitride layer, it is equivalent to increasing the flow rate of the gallium source to provide a gallium-rich environment and reducing the flow rate of ammonia, thereby weakening the bonding force between the first epitaxial layer and the film layer close to the substrate side.

[0063] In some embodiments, the ratio range of the second flow rate to the first flow rate is 500 - 1200 to ensure the gallium-rich environment when forming the first gallium nitride layer and at the same time ensure the basic process conditions for forming the first gallium nitride layer.

[0064] Figure 5 The flowchart of another method for manufacturing a semiconductor structure provided by an embodiment of the present invention is as Figure 5 shown, and the method includes:

[0065] S210. Form a metal mask layer on one side of the substrate, the metal mask layer having an opening area;

[0066] S220. Form a peeling structure in the opening area, the peeling structure including alternately arranged growth areas and non-growth areas;

[0067] Specifically, the material of the peeling structure can be a metal material. The peeling structure includes alternately arranged growth areas and non-growth areas. When the peeling structure is disposed in the opening area, it is equivalent to further disposing a metal mask layer in the opening area. Among them, the growth area exposes the surface of the film layer on one side of the substrate, and the non-growth area covers the surface of the film layer on one side of the substrate. Exemplarily, Figure 6 FIG. is a schematic structural diagram of a peeling structure provided by an embodiment of the present invention. As Figure 6 shown, the peeling structure 30 may include growth areas 31 arranged in an array, and non-growth areas 32 are disposed around the growth areas 31.

[0068] S230. Form a first epitaxial layer in the growth area.

[0069] Specifically, after forming the peeling structure, forming a first epitaxial layer in the growth area can further reduce the contact area between the first epitaxial layer and the film layer in contact with one side of the substrate, thereby further reducing the peeling difficulty between the light-emitting unit and the film layer in contact therewith, improving the transfer yield of the light-emitting unit, reducing the number of repairs after the transfer of the light-emitting unit, and further improving the repair efficiency of the light-emitting unit and reducing the manufacturing cost of the light-emitting unit. Exemplarily, a first N-type gallium nitride layer is provided on the substrate, and a surface portion of the first N-type gallium nitride layer is covered by the metal mask layer. When forming the first epitaxial layer, the first epitaxial layer covers the remaining surface of the first N-type gallium nitride layer. Thus, by providing the peeling structure, the contact area between the first epitaxial layer and the first N-type gallium nitride layer can be further reduced, and when the first epitaxial layer is peeled off subsequently, the peeling difficulty between the first epitaxial layer and the first N-type gallium nitride layer can be further reduced.

[0070] S240. Form a second epitaxial layer on the side of the first epitaxial layer away from the substrate, and the second epitaxial layer and the first epitaxial layer form a light-emitting unit.

[0071] In some embodiments, forming a second epitaxial layer on the side of the first epitaxial layer away from the substrate includes:

[0072] Form a quantum well layer on the side of the first epitaxial layer away from the substrate;

[0073] Specifically, Figure 7 FIG. is a schematic structural diagram of a semiconductor structure provided by an embodiment of the present invention. As Figure 7As shown, the second epitaxial layer 40 may include a quantum well layer 41, an electron blocking layer 42, a first p-type gallium nitride layer 43, and a second p-type gallium nitride layer 44. After forming the first epitaxial layer 20, the quantum well layer 41 may be formed on the side of the first epitaxial layer 20 away from the substrate. The material of the quantum well layer 41 may be InGaN / GaN. The number of pairs of quantum well regions MQW is 2 - 14 pairs, where the thickness of the barrier GaN is 10 - 150 nm, the thickness of the well InGaN is 5 - 30 nm, and the growth temperature of InGaN is 680 - 790 °C.

[0074] An electron blocking layer is formed on the side of the quantum well layer away from the substrate;

[0075] Specifically, after forming the quantum well layer 41, the electron blocking layer 42 is formed on the side of the quantum well layer 41 away from the substrate. The electron blocking layer 42 may be an Mg-doped p-type AlGaN layer with a thickness of 15 - 120 nm and a growth temperature of 900 - 1030 °C.

[0076] A conductive layer is formed on the side of the electron blocking layer away from the substrate.

[0077] Specifically, Figure 7 exemplarily shows that the conductive layer includes a first p-type gallium nitride layer 43 and a second p-type gallium nitride layer 44. After forming the electron blocking layer 42, the first p-type gallium nitride layer 43 may be formed first on the side of the electron blocking layer 42 away from the substrate, and then the second p-type gallium nitride layer 44 is formed. The first p-type gallium nitride layer 43 may be P-GaN doped with Mg, and the thickness of P-GaN is 50 - 300 nm, and the growth temperature is 900 - 980 °C. The Mg doping concentration is 1E19 - 5E19 / cm 2 . When forming the second p-type gallium nitride layer 44, the doping amount of Mg may be increased relative to the first p-type gallium nitride layer 43, so that the Mg doping concentration is 5E19 - 9E19 / cm 2 , and the thickness is 10 - 30 nm. At this time, the first epitaxial layer 20 serves as the n-type conductive layer of the light-emitting unit, the quantum well layer 41 serves as the light-emitting layer of the light-emitting unit, and the conductive layer serves as the p-type conductive layer of the light-emitting unit.

[0078] Continue to refer to Figure 7 , the metal mask layer 10 also has a step 12, and the step 12 is arranged around the opening area 11. When forming the first epitaxial layer 20 and / or forming the second epitaxial layer 40, at least a part of the first epitaxial layer 20 and / or the second epitaxial layer 40 covers the surface of the step 12.

[0079] Specifically, Figure 7Exemplarily, it is shown that the second epitaxial layer 40 includes a quantum well layer 41, an electron blocking layer 42, a first p-type gallium nitride layer 43, and a second p-type gallium nitride layer 44, and the step 12 is a two-layer step structure. At this time, the side of the step 12 away from the substrate includes a first surface and a second surface. The first surface is the surface of the first layer of the step, and the second surface is the surface of the second layer of the step. The electron blocking layer 42, the first p-type gallium nitride layer 43, and the second p-type gallium nitride layer 44 extend to the first surface. After the second epitaxial layer 40 is completed, when the light-emitting unit is peeled off, under the stress generated by the large thermal mismatch in the cooling stage, the difference in the thermal expansion coefficient between a part of the second epitaxial layer 40 and the step 12 is relatively large, so that the second epitaxial layer 40 is easily separated from the step 12, thereby further reducing the peeling difficulty of the light-emitting unit, improving the transfer yield of the light-emitting unit, reducing the number of repairs after the transfer of the light-emitting unit, and further improving the repair efficiency of the light-emitting unit, reducing the manufacturing cost of the light-emitting unit. Exemplarily, the material of the second epitaxial layer 40 is gallium nitride, and its thermal expansion coefficient is 5.59×10 -6 / K. The material of the metal mask layer 10 can be Fe, Mn, Ni, Ti, etc., and their thermal expansion coefficients are 12.2×10 -6 / K, 23×10 -6 / K, 13×10 -6 / K, 10.8×10 -6 / K, respectively, which are all much larger than the thermal expansion coefficient of gallium nitride, indicating that in the cooling stage of peeling, there is a large stress between the second epitaxial layer 40 and the step 12, making the light-emitting unit easy to be peeled off. In addition, the melting points of Fe, Mn, Ni, and Ti are 1538°C, 1244°C, 1453°C, and 1668°C, respectively, which are all higher than the upper limit of the working temperature of the conventional light-emitting unit epitaxial equipment, 1150°C, so as to ensure the reliability of the metal mask layer 10. Moreover, the material of the step 12 is metal. The amorphous or polycrystalline orientation of the metal itself and the lattice difference from the gallium nitride material of the first epitaxial layer 20 and / or the second epitaxial layer 40 make it impossible for the second epitaxial layer 40 to grow on the surface of the step 12. Therefore, the growth interface of the second epitaxial layer 40 is smooth and has no viscosity. When peeling the light-emitting unit, the peeling difficulty of the light-emitting unit can be further reduced, the transfer yield of the light-emitting unit is improved, the number of repairs after the transfer of the light-emitting unit is reduced, and further the repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit is reduced. In addition, when the metal mask layer 10 has a step 12, when the first epitaxial layer 20 and / or the second epitaxial layer 40 grow on the step 12, during the growth process of the first epitaxial layer 20 and / or the second epitaxial layer 40 in the thickness direction, the dislocations are continuously bent, so that dislocation bending annihilation can be achieved, reducing the dislocations of the second epitaxial layer 40, and thus improving the crystal quality and light efficiency of the light-emitting unit.

[0080] After the light-emitting unit is formed in the first epitaxial layer 20 and / or the second epitaxial layer 40, when the second epitaxial layer 40 extends onto the step 12, the side of the light-emitting unit close to the substrate is stepped. At this time, the bottom plane of the light-emitting unit is the first epitaxial layer 20, which is an N-type gallium nitride layer. The stepped position is the second epitaxial layer 40, which can be a P-type gallium nitride layer. Thus, after the light-emitting unit is peeled off, a flip-chip structure can be obtained without etching the light-emitting unit, simplifying the manufacturing process and saving the manufacturing cost. Additionally, continuing to refer to Figure 2 the width of the first step along the direction pointing to the opening region 11 is greater than or equal to 2 μm, such that when the light-emitting unit exposes the second epitaxial layer 40, the width a of the second epitaxial layer 40 is greater than or equal to 2 μm. Thus, when the second epitaxial layer 40 serves as the metal lead electrode of the light-emitting unit, the connection reliability of the metal lead electrode can be ensured.

[0081] After the light-emitting unit is peeled off and transferred, the metal mask layer 10 can be cleaned so that the metal mask layer 10 can be reused, thereby further reducing the transfer cost of the light-emitting unit.

[0082] In some embodiments, when a peeling structure is provided in the opening region, the peeling structure can further increase the contact area between the metal material and the gallium nitride material, thereby further increasing the reduction of the peeling difficulty of the light-emitting unit and improving the transfer yield of the light-emitting unit.

[0083] It should be noted that Figure 7 exemplarily shows a structure of the step 12. In other embodiments, the step 12 can include various structures. Exemplarily, Figure 8 is a schematic structural diagram of another semiconductor structure provided by an embodiment of the present invention. As Figure 8 shown, the step 12 can also be an inverted T-shaped structure, which is not limited herein. Additionally, in some embodiments, by reducing the distance between adjacent steps 12, the contact area between the first epitaxial layer 20 and the film layer in contact therewith can be further reduced, and further the contact area between the light-emitting unit and the film layer in contact therewith can be reduced. Thus, when the light-emitting unit is peeled off, the peeling difficulty between the light-emitting unit and the film layer in contact therewith can be reduced, the transfer yield of the light-emitting unit can be improved, the number of repairs after the light-emitting unit is transferred can be reduced, and further the repair efficiency of the light-emitting unit can be improved, and the manufacturing cost of the light-emitting unit can be reduced. Exemplarily, in Figure 2 the width b of the step 12 along the direction pointing to the opening region 11 is 3 μm, and the distance d between adjacent steps 12 is 3 μm. In Figure 8 the width b' of the step 12 along the direction pointing to the opening region 11 is 5 μm, and the distance d' between adjacent steps 12 is 3 μm. Relative to Figure 2 Figure 8The occupied area of the opening region 11 on the surface of the first N-type gallium nitride layer is reduced, so that the peeling difficulty of the light-emitting unit can be further reduced.

[0084] In some embodiments, continuing to refer to Figure 7 , the sum of the thicknesses of the first epitaxial layer 20 and the second epitaxial layer 40 is greater than the thickness of the step 12.

[0085] Specifically, as Figure 7 shown, the sum of the thicknesses of the first epitaxial layer 20 and the second epitaxial layer 40 is the thickness of the light-emitting unit. During the peeling process, the thickness of the light-emitting unit is greater than the thickness of the step 12. During the peeling process, when the UV film is coated on the side of the second epitaxial layer 40 away from the first epitaxial layer 20, it helps the UV film to adhere to the second epitaxial layer 40, and at the same time avoids the UV film from adhering to the step 12, thereby facilitating the transfer of the light-emitting unit. Exemplarily, the difference between the sum of the thicknesses of the first epitaxial layer 20 and the second epitaxial layer 40 and the thickness of the step 12 is 100-1000 nm. Exemplarily, Figure 9 FIG. 12 is a schematic structural diagram of a semiconductor structure covered with a UV film according to an embodiment of the present invention, Figure 10 FIG. 14 is a schematic structural diagram of a UV film adhering to a light-emitting unit for transfer according to an embodiment of the present invention, Figure 11 FIG. 16 is a schematic structural diagram of local UV irradiation to achieve local release of a light-emitting unit according to an embodiment of the present invention. As Figures 9 to 11 shown, when the UV film 50 adheres to the light-emitting unit, the light-emitting unit array can be transferred above the area where the light-emitting unit is to be placed, for example, above the area of the display panel where the defective pixel needs to be repaired. Then, through local UV irradiation, a single light-emitting unit at the UV-irradiated area can be released to the area where the light-emitting unit is to be placed, thereby completing the transfer of the light-emitting unit.

[0086] The embodiment of the present invention also provides a manufacturing method of a semiconductor structure, Figure 12 FIG. 23 is a flowchart of another manufacturing method of a semiconductor structure according to an embodiment of the present invention. As Figure 12 shown, the method includes:

[0087] S310. Form a metal mask layer on one side of the substrate, and the metal mask layer has an opening region;

[0088] S320. Form a peeling structure in the opening region, and the peeling structure includes alternately arranged growth regions and non-growth regions;

[0089] Specifically, the material of the peeling structure can be a metal material. The peeling structure includes alternately arranged growth regions and non-growth regions. The growth regions expose the surface of the film layer on one side of the substrate, and the non-growth regions cover the surface of the film layer on one side of the substrate. When the peeling structure is disposed in the opening region, it is equivalent to further disposing a metal mask layer in the opening region.

[0090] S330. An epitaxial layer is formed in the growth region, and the epitaxial layer forms a light-emitting unit.

[0091] Specifically, the epitaxial layer may include multiple layers for forming a light-emitting unit. Exemplarily, the epitaxial layer may include a second N-type gallium nitride layer as the N-type conductive layer of the light-emitting unit. The epitaxial layer may further include a quantum well layer disposed on the side of the second N-type gallium nitride layer away from the substrate as the light-emitting layer of the light-emitting unit. The epitaxial layer may further include an electron blocking layer disposed on the side of the quantum well layer away from the substrate as the light-emitting functional layer of the light-emitting unit. The epitaxial layer may further include a first P-type gallium nitride layer and a second P-type gallium nitride layer stacked as the P-type conductive layer of the light-emitting unit. When forming the epitaxial layer in the growth region, either a conventional epitaxial layer manufacturing process or the manufacturing process provided in any embodiment of the present invention may be used, which is not limited herein. Exemplarily, when forming the second N-type gallium nitride layer, the ratio range of the ammonia flow rate to the gallium source flow rate may be 1500 - 3000, that is, the V / III of the process conditions when forming the second N-type gallium nitride layer is 1500 - 3000. This enables the second N-type gallium nitride layer to be a conventional gallium nitride layer, ensuring the requirements of the light-emitting unit for a normal gallium nitride film layer.

[0092] When forming the epitaxial layer in the growth region, the contact area of the film layer in contact with one side of the substrate of the epitaxial layer can be further reduced, thereby further reducing the peeling difficulty of the film layer in contact with the light-emitting unit, improving the transfer yield of the light-emitting unit, reducing the number of repairs after the transfer of the light-emitting unit, and further improving the repair efficiency of the light-emitting unit and reducing the manufacturing cost of the light-emitting unit.

[0093] The technical solution of this embodiment, by providing a peeling structure in the opening area of the metal mask layer, enables the peeling structure to further reduce the contact area of the film layer in contact with one side of the substrate of the epitaxial layer on the basis of the metal mask layer, thereby reducing the peeling difficulty of the film layer in contact with the light-emitting unit, improving the transfer yield of the light-emitting unit, reducing the number of repairs after the transfer of the light-emitting unit, and further improving the repair efficiency of the light-emitting unit and reducing the manufacturing cost of the light-emitting unit.

[0094] The embodiment of the present invention also provides a semiconductor structure, which can be formed by using the manufacturing method of the semiconductor structure provided in any embodiment of the present invention. Since the semiconductor structure includes the technical features of the manufacturing method of the semiconductor structure provided in any embodiment of the present invention, it has the same beneficial effects as the manufacturing method of the semiconductor structure provided in any embodiment of the present invention, which will not be elaborated herein.

[0095] The embodiment of the present invention also provides a semiconductor structure. Figure 13 It is a schematic structural diagram of another semiconductor structure provided by the embodiment of the present invention. AsFigure 13 As shown, the semiconductor structure includes:

[0096] Substrate 00;

[0097] A metal mask layer 10 is disposed on one side of the substrate 00, and the metal mask layer 10 has an opening region 11;

[0098] A peeling structure 30 is disposed on one side of the metal mask layer 10 and is located within the opening region 11. The peeling structure 30 includes alternately arranged growth regions and non-growth regions;

[0099] An epitaxial structure is disposed within the growth region, and the epitaxial structure forms a light-emitting unit.

[0100] Wherein, a first N-type gallium nitride layer 01 is disposed on one side of the substrate 00, and the metal mask layer 10 is disposed on the first N-type gallium nitride layer 01. The metal mask layer 10 may include a step 12, and the step 12 surrounds the opening region 11. Figure 13 Exemplarily shown therein is that the epitaxial structure includes a first epitaxial layer 20 and a second epitaxial layer 40. The second epitaxial layer 40 may include a quantum well layer 41, an electron blocking layer 42, a first P-type gallium nitride layer 43, and a second P-type gallium nitride layer 44 which are sequentially stacked.

[0101] The technical solution of this embodiment, by disposing a peeling structure within the opening region of the metal mask layer, enables the peeling structure to further reduce the contact area of the film layer where the epitaxial layer contacts one side of the substrate on the basis of the metal mask layer, thereby reducing the peeling difficulty between the light-emitting unit and the film layer it contacts, improving the transfer yield of the light-emitting unit, reducing the number of repairs after the transfer of the light-emitting unit, and further improving the repair efficiency of the light-emitting unit and reducing the manufacturing cost of the light-emitting unit.

[0102] Note that the above is only a preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, it may also include more other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for manufacturing a semiconductor structure, characterized in that: include: forming a metal mask layer on one side of the substrate, wherein the metal mask layer has an opening area; forming a first epitaxial layer in the opening area, the first epitaxial layer comprising a first gallium nitride layer and a second gallium nitride layer which are stacked, the second gallium nitride layer being located on a side of the first gallium nitride layer away from the substrate, and the atomic percentages of gallium and nitrogen in the second gallium nitride layer being greater than the atomic percentages of gallium and nitrogen in the first gallium nitride layer; A second epitaxial layer is formed on a side of the first epitaxial layer away from the substrate, and the second epitaxial layer and the first epitaxial layer form a light emitting unit.

2. The method for manufacturing a semiconductor structure according to claim 1, characterized in that: Forming a first epitaxial layer in the opening region includes: In the first stage, a first gallium nitride layer is formed by using a gallium source with a first flow rate and an ammonia gas with a second flow rate; In the second stage, a gallium source with a third flow rate and ammonia with a fourth flow rate are used to form a second gallium nitride layer; a ratio of the second flow rate to the first flow rate is smaller than a ratio of the fourth flow rate to the third flow rate.

3. The method for manufacturing a semiconductor structure according to claim 2, characterized in that: The ratio of the second flow rate to the first flow rate ranges from 500 to 1200.

4. The method for manufacturing a semiconductor structure according to claim 1, characterized in that: Before forming the first epitaxial layer in the opening area, the method further includes: forming a peeling structure in the opening area, wherein the peeling structure includes a growth area and a non-growth area arranged in a staggered manner; Forming a first epitaxial layer in the opening region includes: The first epitaxial layer is formed in the growth region.

5. The method for manufacturing a semiconductor structure according to claim 1, characterized in that: The metal mask layer also has a step, and the step is arranged around the opening area. When forming the first epitaxial layer and / or forming the second epitaxial layer, the first epitaxial layer and / or the second epitaxial layer at least partially covers the surface of the step.

6. The method for manufacturing a semiconductor structure according to claim 5, characterized in that: The sum of the thickness of the first epitaxial layer and the second epitaxial layer is greater than the thickness of the step.

7. The method for manufacturing a semiconductor structure according to claim 1, characterized in that: Forming a second epitaxial layer on a side of the first epitaxial layer away from the substrate, comprising: forming a quantum well layer on a side of the first epitaxial layer away from the substrate; forming an electron blocking layer on a side of the quantum well layer away from the substrate; A conductive layer is formed on a side of the electron blocking layer away from the substrate.

8. A method for manufacturing a semiconductor structure, characterized in that: include: forming a metal mask layer on one side of the substrate, wherein the metal mask layer has an opening area; forming a peeling structure in the opening area, wherein the peeling structure includes a growth area and a non-growth area arranged in a staggered manner; An epitaxial layer is formed in the growth region, and the epitaxial layer forms a light emitting unit.

9. A semiconductor structure, characterized in that: The semiconductor structure is formed by the method for manufacturing the semiconductor structure according to any one of claims 1 to 7.

10. A semiconductor structure, characterized in that: include: substrate; A metal mask layer is disposed on one side of the substrate, and the metal mask layer has an opening area; A peeling structure, arranged on one side of the metal mask layer and located in the opening area, the peeling structure comprising a growth area and a non-growth area arranged in a staggered manner; An epitaxial structure is arranged in the growth region, and the epitaxial structure forms a light-emitting unit.

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