Composite patterned substrate structure and method of fabrication

Abstract

The present application relates to the technical field of semiconductor, and relates to a composite patterning substrate structure and a preparation method thereof, which comprises a substrate and an epitaxial layer, the epitaxial layer is arranged on the upper surface of the substrate, N layer pattern structures (N is greater than or equal to 2 and is an integer) are arranged in the epitaxial layer, the N layer pattern structures are arranged at intervals from bottom to top, the planar union orthographic projection of the N layer pattern structures completely covers the upper surface of the substrate, the pattern period of the Nth layer pattern structure is smaller than the pattern period of the (N-1)th layer pattern structure, thereby, by setting different pattern diameters and pattern periods for the pattern structures of different levels, the pattern diameter of the upper layer is smaller, and the period is smaller, and such a design significantly reduces the growth defects of the subsequent epitaxial layer and improves the quality of epitaxial growth.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a composite patterned substrate structure and a preparation method thereof. BACKGROUND

[0002] Epitaxy process plays an important role in the manufacture of semiconductor devices, especially in the manufacture of light emitting diodes (LEDs). Epitaxy process mainly includes two types of homoepitaxy and heteroepitaxy. Homoepitaxy refers to epitaxially growing the same material on the same type of substrate, and heteroepitaxy refers to epitaxially growing another material on a substrate of one material.

[0003] Among them, heteroepitaxy will cause obvious epitaxial defects in the epitaxial process due to the lattice mismatch between the substrate and the epitaxial material, which greatly affects the quality of the epitaxial material; In order to alleviate this problem, the prior art mostly adopts the method of patterning the substrate, such as the commonly used PSS; Although a simple pattern structure can also reduce the defects of the epitaxial material to a certain extent, but with the upgrading of the display and lighting industry in recent years, the quality requirements for LEDs are getting higher and higher, and therefore the requirements for epitaxy are also higher, and how to further improve the quality of epitaxial growth is very important.

[0004] It should be noted that the information disclosed in this background section is only intended to increase the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that this information constitutes prior art known to those skilled in the art. SUMMARY

[0005] To solve the problem of improving the quality of epitaxial material mentioned in the background technology, the present application provides a composite patterned substrate structure, which comprises a substrate and an epitaxial layer.

[0006] The epitaxial layer is arranged on the upper surface of the substrate, and the epitaxial layer is provided with N layers of pattern structures (N≥2 and is an integer), and the N layers of pattern structures are arranged at intervals from bottom to top;

[0007] The planar union orthographic projection of the N layers of pattern structures completely covers the upper surface of the substrate, and the pattern period of the Nth layer of pattern structures is smaller than the pattern period of the N-1th layer of pattern structures.

[0008] Further, the pattern period P n satisfies the following conditions:

[0009]

[0010] Among them, P (n-1) is the pattern period of the N-1th layer, and W (n-1) is the pattern diameter of the N-1th layer.

[0011] Further, the N-layer patterned structure comprises at least a first layer patterned structure and a second layer patterned structure, one side of the first layer patterned structure is connected to the substrate and is arranged in a spaced array, the second layer patterned structure is above the first layer patterned structure, and the pattern period P 2 is expressed as:

[0012]

[0013] wherein P 1 is the pattern period of the first layer patterned structure, W 1 is the pattern diameter of the first layer patterned structure.

[0014] Further, the N-layer patterned structure further comprises a third layer patterned structure, the third layer patterned structure is above the second layer patterned structure, and the pattern period P 3 is expressed as:

[0015]

[0016] wherein P 2 is the pattern period of the second layer patterned structure, W 2 is the pattern diameter of the second layer patterned structure.

[0017] Further, the pattern diameter W n of the N-layer patterned structure satisfies the following conditions:

[0018] 1 / 4W (n-1) <W n <3 / 4W (n-1)

[0019] wherein W (n-1) is the pattern diameter of the N-1-layer patterned structure.

[0020] Further, the N-layer patterned structure is 2-10 layers.

[0021] Further, the material of the N-layer patterned structure is one or more of SiO2, Si3N4, ZnO2, Si, SiC, GaAs, Ti3O5, and TiO2.

[0022] Further, the pattern shape of the N-layer patterned structure is one or more of conical, cylindrical, concave, and pyramidal.

[0023] Further, the material of the substrate is Al2O3.

[0024] The application also provides a preparation method of a composite patterned substrate structure, which is used for preparing the composite patterned substrate structure described in any one of the above embodiments and specifically comprises the following steps:

[0025] S1, making a first layer of pattern structure on a substrate;

[0026] S2, growing an epitaxial layer so that the epitaxial layer covers the first layer of pattern structure;

[0027] S3, calculating the pattern diameter and pattern period of a second layer of pattern structure according to the pattern diameter and pattern period of the first layer of pattern structure, and making the second layer of pattern structure;

[0028] S4, growing the epitaxial layer again so that the epitaxial layer covers the second layer of pattern structure;

[0029] S5, repeating the steps of S3-S4 for (N-2) times to obtain a composite patterned substrate structure with N layers of pattern structure.

[0030] Based on the above, the composite patterned substrate structure provided by the present application has the following advantages: the union set of the orthographic projections of the multiple layers of pattern structure completely covers the surface of the substrate, and different pattern diameters and pattern periods are set for different layers of pattern structure, i.e., the upper layers of pattern structure have smaller diameters and periods, which significantly reduces the growth defects of the subsequent epitaxial layer and improves the quality of epitaxial growth.

[0031] Other features and advantages of the present application will be described in the following description and, in part, will become apparent to those skilled in the art upon examination of the following description or can be learned by practice of the present application. The purposes and other advantages of the present application can be realized and attained by the structure particularly pointed out in the written description and claims. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without any creative effort. In the following description, the positional relationship described by the drawings is based on the direction of the components shown in the drawings.

[0033] Figure 1 A schematic diagram of the defect structure of the epitaxial material obtained by the prior art heteroepitaxy technology;

[0034] Figure 2 A structural schematic diagram of the composite patterned substrate structure provided by an embodiment of the present application;

[0035] Figure 3 A top view schematic diagram of the pattern structure provided by an embodiment of the present application;

[0036] Figure 4is a structural schematic diagram of a composite patterned substrate structure provided by another embodiment of the present application;

[0037] Figure 5 is a preparation flow schematic diagram of a composite patterned substrate structure provided by an embodiment of the present application;

[0038] Figure 6 is a structure schematic diagram of a flip chip LED chip structure using a composite patterned substrate structure provided by an embodiment of the present application.

[0039] Markings in the figure:

[0040] 10-substrate 20-epitaxial layer 30-pattern structure

[0041] 40-N-type semiconductor layer 50-multiquantum well layer 60-P-type semiconductor layer

[0042] 70-current spreading layer 80-N electrode 90-P electrode

[0043] 31-first layer pattern structure 32-second layer pattern structure 33-third layer pattern structure DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments of the present application; the technical features designed in different embodiments of the present application can be combined with each other as long as they do not conflict with each other; all the other embodiments obtained by those skilled in the art without creative labor based on the embodiments in the present application are within the protection scope of the present application.

[0045] In the description of the present application, it should be understood that the terms "center", "transverse", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or component referred to must have a particular orientation, or be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more. In addition, the term "comprising" and any variation thereof means "at least including".

[0046] For the convenience of understanding, some terms are first explained:

[0047] Pattern structure: composed of multiple single patterns made of materials that will not undergo epitaxial growth, used to block epitaxial defects.

[0048] Pattern diameter W: refers to the size of the pattern diameter of the single pattern in the pattern structure.

[0049] Pattern period P: refers to the distance from a point on a single pattern to the same point on the next single pattern, i.e. the sum of the diameter of the single pattern and the spacing between the single patterns.

[0050] Overhead set orthographic projection: overhead set orthographic projection.

[0051] Embodiment one

[0052] As mentioned in the background art, due to the lattice mismatch between the substrate (substrate) and the epitaxial material, obvious epitaxial growth defects often occur. As shown in Figure 1 Such defects often spread from the bottom up at the juncture of the substrate surface and the pattern, which greatly affects the quality of the epitaxial layer.

[0053] Therefore, the embodiment provides a composite patterned substrate structure. As shown in Figure 2 and Figure 3 It includes a substrate 10 and an epitaxial layer 20. For the convenience of explanation, the material of the substrate 10 in this embodiment is preferably Al2O3, which has the advantages of good chemical stability, relatively mature production technology, etc. The epitaxial layer 20 is preferably GaN or AlN, which can obtain better lattice matching effect and reduce dislocation defects. The material of the substrate 10 and the epitaxial layer 20 can also be adjusted and matched according to actual needs, which is not limited.

[0054] The epitaxial layer 20 is arranged on the upper surface of the substrate 10, and the epitaxial layer 20 can grow upward in the vertical direction. The epitaxial layer 20 is provided with N layer pattern structure 30 (N≥2 and is an integer), and the N layer pattern structure 30 is arranged at intervals from bottom to top. The material of the N layer pattern structure 30 is one or more of SiO2, Si3N4, ZnO2, Si, SiC, GaAs, Ti3O5, and TiO2, which can be adjusted according to actual production needs, which is not limited.

[0055] Preferably, the pattern period P n of the Nth layer pattern structure 30 is smaller than the pattern period P (n -1) of the N-1th layer pattern structure 30.

[0056] Specifically, the pattern period P of the Nth layer pattern structure n satisfies the following condition:

[0057]

[0058] wherein P (n-1) is the pattern period of the (N-1)th layer, and W (n-1) is the pattern diameter of the (N-1)th layer.

[0059] Preferably, the pattern diameter W n of the Nth layer pattern structure satisfies the following condition:

[0060] 1 / 4W (n-1) < W n < 3 / 4W (n-1)

[0061] wherein W (n-1) is the pattern diameter of the (N-1)th layer pattern structure.

[0062] In the embodiment, the N-layer pattern structure 30 comprises at least a first layer pattern structure 31 and a second layer pattern structure 32. The pattern shape of the first layer pattern structure 31 and the second layer pattern structure 32 is one or more of a conical shape, a cylindrical shape, a concave hole shape, and a pyramid shape. In this embodiment, the conical shape is adopted to facilitate pattern stitching.

[0063] The first layer pattern structure 31 is arranged in an array on the substrate 10 with a space between each single pattern of the first layer pattern structure 31 for epitaxial layer 20 growth. At this time, the pattern diameter W 1 and the pattern period P 1 of the first layer pattern structure 31 can be set according to specific requirements.

[0064] The second layer pattern structure 32 is located above the first layer pattern structure 31, and the pattern diameter W 2 and the pattern period P 2 of the second layer pattern structure 32 are calculated based on the pattern diameter W 1 and the pattern period P 1 of the first layer pattern structure 31. The pattern period P 2 of the second layer pattern structure 32 is expressed as:

[0065]

[0066] The pattern diameter W 2 of the second layer pattern structure 32 is expressed as:

[0067] 1 / 4W (2-1) < W 2 < 3 / 4W (2-1)

[0068] At this time, the top view and the combined orthographic projection of the first pattern structure 31 and the second pattern structure 32 completely cover the upper surface of the substrate 10. The second pattern structure 32 can effectively block the defects that extend upward during the growth of the epitaxial layer 20. When the epitaxial layer 20 is grown for the second time, the defect level will be greatly reduced because the same material is used for epitaxial growth.

[0069] Meanwhile, the graphic period P of the first layer graphic structure 32 1 and the diameter W of the figure 1 The larger size facilitates light emission; the second layer of the graphic structure has a graphic period P of 32. 2 and the diameter W of the figure 2 Smaller size makes it easier to block defects and reduce defect levels, thus achieving higher epitaxial material quality and obtaining a high-quality epitaxial layer 20.

[0070] Example 2

[0071] Based on the above embodiments, in order to further improve the effect of the pattern structure 30 in blocking defects and reduce the defect level of the epitaxial layer 20, such as Figure 4 As shown, the N-layer graphic structure also includes a third-layer graphic structure 33, which is located above the second-layer graphic structure 22. The graphic diameter W of the third-layer graphic structure 33 is... 3 and the periodicity P of the graph 3 Through the second layer graphic structure 32, the graphic diameter W 2 and the periodicity P of the graph 2 Calculations show that the period P of the third-layer graphic structure 33 is... 3 Expressed as:

[0072]

[0073] Among them, P 2 For the graph period of the second-layer graph structure, W 2 The diameter of the second-layer graphic structure.

[0074] The diameter W of the third layer graphic structure 33 2 Expressed as:

[0075] 1 / 4W (3-1) <W 3 <3 / 4W (3-1)

[0076] At this time, the top-view orthographic projections of the first patterned structure 31, the second patterned structure 32, and the third patterned structure 33 converge to cover the upper surface of the substrate 10, thereby enhancing the effect of the patterned structure 30 in blocking defects and reducing the defect level of the epitaxial layer 20.

[0077] In this embodiment, the diameters W and the periods P of the first pattern structure 31 to the third pattern structure 33 of the patterned substrate structure are getting smaller, which is beneficial to obtain better epitaxial quality, and the patterns are getting denser from bottom to top, which can obtain better light extraction effect.

[0078] In some preferred embodiments, considering the thickness of the patterned substrate structure and the effect of the blocking defects, the number of the N layers of the patterned structure 30 is preferably 2-10.

[0079] Embodiment Three

[0080] The present application also provides a method for preparing the composite patterned substrate structure, as shown in the following steps: Figure 5

[0081] S1: performing the fabrication of the first pattern structure 31 on the substrate 10;

[0082] S2: performing the growth of the epitaxial layer 20 so that the epitaxial layer 20 covers the first pattern structure 31;

[0083] S3: combining the pattern diameter W 1 and the pattern period P 1 of the first pattern structure 31 to calculate the pattern diameter W 2 and the pattern period P 2 of the second pattern structure 32, and performing the fabrication of the second pattern structure 32;

[0084] S4: performing the secondary growth of the epitaxial layer 20 so that the epitaxial layer 20 covers the second pattern structure 32;

[0085] S5: repeating the steps of S3-S4 for (N-2) times to obtain the composite patterned substrate structure with N layers of the patterned structure 30.

[0086] In the specific implementation, the fabrication of the first pattern structure 31 is performed on the upper surface of the substrate 10, and the single pattern structure of the first pattern structure 31 is left with a surface for the growth of the epitaxial layer 20. The growth of the epitaxial layer 20 is performed on the surface reserved by the first pattern structure 31, and in this process, the upward extending defects will be generated at the reserved surface of the first pattern structure 31 and the pattern seams of the first pattern structure 31.

[0087] When the thickness of the epitaxial layer 20 exceeds the first pattern structure 31, the pattern diameter W 1 and the pattern period P 1 of the first pattern structure 31 are combined to calculate the pattern diameter W 2 and the pattern period P 2 of the second pattern structure 32 by the formula:

[0088] ​

[0089] 1 / 4W (2-1) <W 2 <3 / 4W (2-1)

[0090] The pattern diameter W of the second layer pattern structure 32 is obtained 2 and the pattern period P 2 After that, the second layer pattern structure 32 is made, which will block the extension of defects. At this time, the epitaxial layer 20 is grown again. Since the epitaxial growth is of the same material, the defect level is greatly reduced, and a better epitaxial layer can be grown above the second layer pattern structure 32.

[0091] In order to further improve the effect of the pattern structure 30 on blocking defects and reduce the defect level of the epitaxial layer 20, the calculation of the pattern diameter W and the pattern period P can be repeated and the corresponding pattern structure 30 can be made. When repeated once, there is a third layer pattern structure 33, and so on. The pattern diameter W and the pattern period P of the upper pattern structure 30 are continuously reduced, and the defect level is also reduced. The epitaxial quality of the upper pattern structure 30 is better, and the epitaxial quality of the uppermost layer is the best. At the same time, the pattern diameter W and the pattern period P of the lower pattern structure 30 are relatively larger. The design of gradually changing the pattern period P and the diameter W of each layer is beneficial to improve the overall light output.

[0092] In some preferred embodiments, the present application also provides a positive LED chip using the composite patterned substrate structure described above. In specific implementation, it comprises an N-type semiconductor layer 40, a multi-quantum well layer 50, a P-type semiconductor layer 60, a current spreading layer 70, an N electrode 80 and a 90-P electrode arranged in sequence on the epitaxial layer 20.

[0093] It should be noted that the technical solution of the present application aims to improve the quality of epitaxial material. The positive LED chip provided in the present embodiment is only for illustration, and can be applied to other vertical LED chips in specific implementation, and this is not limited.

[0094] In summary, the composite patterned substrate structure provided by the present application completely covers the substrate surface with the union of the orthographic projections of the multi-layer pattern structure, and sets different pattern diameters and pattern periods for different levels of pattern structure. The smaller the diameter and the period of the upper pattern structure, the smaller the growth defects of the subsequent epitaxial layer, and the better the quality of epitaxial growth.

[0095] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present application can only be improved in one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or background art at the same time. Those skilled in the art should understand that what is not mentioned in a claim should not be regarded as a limitation on the claim.

[0096] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A composite patterned substrate structure, characterized in that: include: Substrate; An epitaxial layer is disposed on the upper surface of the substrate. The epitaxial layer contains N patterned structures, where N ≥ 2 and is an integer. The N patterned structures are spaced apart from bottom to top, and the diameter of the patterned structure decreases with each uppermost layer. The top-view union orthographic projection of the N-layer patterned structure completely covers the upper surface of the substrate. The pattern period of the N-th layer patterned structure is less than the pattern period of the (N-1)-th layer patterned structure, and the pattern period of the N-th layer patterned structure... The following conditions must be met: in, The period of the N-1th layer of the graphic structure is given. The diameter of the graphic structure in the (N-1)th layer is given.

2. The composite patterned substrate structure according to claim 1, characterized in that: The N-layer patterned structure includes at least a first layer and a second layer. One side of the first layer is connected to the substrate and is arranged in a spaced array. The second layer is located above the first layer. The pattern period of the second layer is... Expressed as: in, The period of the first layer of the graphic structure. The diameter of the first layer of the graphic structure.

3. The composite patterned substrate structure according to claim 2, characterized in that: The N-layer graph structure also includes a third-layer graph structure, which is located above the second-layer graph structure. The graph period of the third-layer graph structure is... Expressed as: in, The period of the second layer of the graphic structure. The diameter of the second layer of the graphic structure.

4. The composite patterned substrate structure according to claim 1, characterized in that: The diameter of the Nth layer graphic structure The following conditions must be met: in, The diameter of the graphic structure in the (N-1)th layer.

5. The composite patterned substrate structure according to claim 1, characterized in that: The N-layer graph structure consists of 2 to 10 layers.

6. The composite patterned substrate structure according to claim 1, characterized in that: The material of the N-layer graphic structure is , One or more of them.

7. The composite patterned substrate structure according to claim 1, characterized in that: The shape of the N-layer graphic structure can be one or more of the following: conical, cylindrical, concave, and pyramidal.

8. The composite patterned substrate structure according to claim 1, characterized in that: The material of the substrate is .

9. A method for fabricating a composite patterned substrate structure, characterized in that: The method for preparing the composite patterned substrate structure according to any one of claims 1-8 specifically includes the following steps: S1 fabricates the first layer of patterned structure on the substrate; S2 performs epitaxial layer growth, ensuring that the epitaxial layer does not extend beyond the first layer of the pattern structure; S3 calculates the diameter and period of the second-layer graphic structure by combining the graphic diameter and period of the first-layer graphic structure, and then creates the second-layer graphic structure. S4 performs secondary growth of the epitaxial layer, ensuring that the epitaxial layer does not extend beyond the second layer of the pattern structure; S5 repeats steps S3-S4 (N-2) times to obtain a composite patterned substrate structure with N layers.

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