Method for reusing pit type PSS, composite substrate and LED epitaxial wafer

Abstract

The embodiment of the present application discloses a kind of reuse methods of pit type PSS, composite substrate and LED epitaxial wafer.The reuse method of pit type PSS includes: providing patterned substrate, patterned substrate includes substrate and the multiple convex microstructures and multiple pits formed on the surface of substrate, pit surrounds convex microstructure;Form a layer of heterostructure on patterned substrate;Pattern heterostructure, form multiple heterostructure pattern structures, and heterostructure pattern structure one-to-one covers convex microstructure and the pit adjacent to convex microstructure.The embodiment of the present application can solve the problem that PSS cannot continue to use after pit is generated, improve the effective delivery rate of product, reduce manufacturing cost.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to semiconductor technology, and more particularly to a reuse method of a pit type PSS, a composite substrate and an LED epitaxial wafer. BACKGROUND

[0002] Sapphire substrates have high melting point, high hardness, high light transmittance, mature process, low cost and other characteristics, and are the most important substrate material in the LED market. Currently, more than 95% of blue-green GaN-based LED epitaxial wafers use patterned sapphire substrates (PSS) as substrate materials.

[0003] However, in the etching process, due to irregular glue columns, improper process formula adjustment, etching machine alarm and other abnormalities, pits will be generated at the bottom of the PSS pattern. The pit type PSS will increase the use risk of the epitaxial customer end, reduce the effective product delivery rate, and increase the manufacturing cost. SUMMARY

[0004] The present application provides a reuse method of a pit type PSS, a composite substrate and an LED epitaxial wafer. The PSS with pits is reprocessed into a substrate that can be reused, improving the effective product delivery rate and reducing manufacturing costs.

[0005] In a first aspect, embodiments of the present application provide a reuse method of a pit type PSS, comprising:

[0006] A patterned substrate is provided, which includes a substrate and a plurality of raised microstructures and a plurality of pits formed on the surface of the substrate, the pits surrounding the raised microstructures;

[0007] A hetero layer is formed on the patterned substrate;

[0008] The hetero layer is patterned to form a plurality of hetero pattern structures, the hetero pattern structures one-to-one corresponding to cover the raised microstructures and the pits adjacent to the raised microstructures.

[0009] Optionally, forming a hetero layer on the patterned substrate comprises:

[0010] A chemical vapor deposition process is used to deposit the hetero layer at a deposition rate of less than 10 nm / min and a chamber pressure of less than 1.2 mT.

[0011] Optionally, after forming a hetero layer on the patterned substrate, further comprising:

[0012] A photoresist is coated to form a photoresist layer on the hetero layer;

[0013] forming a plurality of heterogeneous pattern structures, each of the heterogeneous pattern structures covering the protruding microstructure and the pit adjacent to the protruding microstructure, comprising:

[0014] exposing and developing the photoresist layer to form a plurality of photoresist columns, a vertical projection of the photoresist column on a plane of the substrate covering a vertical projection of the protruding microstructure and the pit adjacent to the protruding microstructure on the plane of the substrate;

[0015] etching the heterogeneous layer as a mask of the photoresist column until the region between the protruding microstructures exposes the surface of the substrate.

[0016] Optionally, after etching the heterogeneous layer as a mask of the photoresist column until the region between the protruding microstructures exposes the surface of the substrate, the method further comprises:

[0017] adopting an organic cleaning agent to remove the residual photoresist column.

[0018] Optionally, before providing the patterned substrate, the method further comprises:

[0019] detecting the patterned substrate to screen out the patterned substrate with a pit width greater than 35 nm and a pit depth greater than 15 nm.

[0020] In a second aspect, an embodiment of the present application further provides a patterned composite substrate, comprising:

[0021] a substrate, a surface of the substrate being formed with a plurality of protruding microstructures and a plurality of pits, the pits surrounding the protruding microstructures;

[0022] a heterogeneous pattern structure, each of the heterogeneous pattern structures covering the protruding microstructure and the pit adjacent to the protruding microstructure.

[0023] Optionally, the heterogeneous pattern structure comprises a side wall part and a planar part, the side wall part covering a side wall of the protruding microstructure, and the planar part covering the pit and at least part of the region between the protruding microstructures on the surface of the substrate.

[0024] The thickness of the side wall part is greater than the height of the planar part on the surface of the substrate.

[0025] Optionally, the thickness of the side wall part ranges from 50 nm to 300 nm, and the height of the planar part on the surface of the substrate ranges from 20 nm to 100 nm.

[0026] Optionally, the distance between adjacent heterogeneous pattern structures is W1, and the distance between adjacent pits is W2, and W1:W2>50%.

[0027] Optionally, the bottom width of the protruding microstructure ranges from 1.5 μm to 4.5 μm, and the height ranges from 1.0 μm to 3.0 μm.

[0028] Optionally, the convex microstructure has a sidewall curvature, and the sidewall convex height ranges from 80 to 200 nm.

[0029] Optionally, the convex microstructure has a sidewall curvature, and the sidewall convex height ranges from 80 to 200 nm.

[0030] In a third aspect, the embodiments of the present application further provide a LED epitaxial wafer, comprising the patterned composite substrate of the second aspect.

[0031] The patterned substrate provided by the embodiments of the present application comprises a substrate, a plurality of convex microstructures and a plurality of pits formed on the surface of the substrate, the pits surrounding the convex microstructures; a hetero layer is formed on the patterned substrate; the hetero layer is patterned to form a plurality of hetero pattern structures, the hetero pattern structures one-to-one corresponding to the convex microstructures and the pits adjacent to the convex microstructures. The embodiments of the present application solve the problem that the PSS with pits generated in the production operation cannot be continuously used, improve the preparation cost, and can rework the PSS with pits into a substrate that can be reused, improve the effective product delivery rate, and reduce the manufacturing cost. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a recycling method flow chart of a pit type PSS provided by the embodiments of the present application;

[0033] Figure 2 is Figure 1 is a structural flow chart of the pit type PSS recycling method shown in FIG. 1;

[0034] Figure 3 is Figure 2 is a top view of the patterned substrate shown in a) of FIG. 1;

[0035] Figure 4 is a recycling method flow chart of another pit type PSS provided by the embodiments of the present application;

[0036] Figure 5 is Figure 4 is a structural flow chart of the pit type PSS recycling method shown in FIG. 1;

[0037] Figure 6 is a structural schematic diagram of a patterned composite substrate provided by the embodiments of the present application;

[0038] Figure 7 is a structural schematic diagram of a LED epitaxial wafer provided by the embodiments of the present application. DETAILED DESCRIPTION

[0039] The application will be described in further detail below with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not to be used to limit the scope of the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for the sake of convenience.

[0040] Figure 1 is a flow chart of a recycling method of a pit type PSS provided by an embodiment of the application, Figure 2 is Figure 1 a structural flow chart of the recycling method of the pit type PSS, referring to Figure 1 and Figure 2 , the recycling method of the pit type PSS comprises:

[0041] S110, providing a patterned substrate, the patterned substrate comprising a substrate 10 and a plurality of raised microstructures 11 and a plurality of pits 12 formed on the surface of the substrate 10, the pits 12 surrounding the raised microstructures 11;

[0042] Referring to Figure 2 a) of the drawings, the patterned substrate is a sapphire substrate, and can also be a patterned substrate formed of silicon, silicon carbide, gallium nitride, etc., the patterned substrate having a plurality of raised microstructures 11 and a plurality of pits 12, Figure 3 is Figure 2 a top view of the patterned substrate shown in a) of the drawings, referring to Figure 2 a) of the drawings and Figure 3 , the pits 12 are formed when the substrate is etched to form the raised microstructures 11, and are distributed around the raised microstructures 11. In addition, in the embodiment shown in Figure 2 and Figure 3 , the raised microstructures 11 are substantially conical, but in actual applications, the raised microstructures 11 on the patterned substrate can also be circular truncated cones, pyramids, prismatic truncated cones, etc., which are not limited herein. It should be noted that in this patterned substrate, in addition to the pits 12 surrounding the raised microstructures 11, there is also a flat surface, i.e., a C surface, between the raised microstructures 11, which is used to form a crystal nucleus growth epitaxy when preparing an epitaxial layer.

[0043] S120, forming a hetero layer 13 on the patterned substrate;

[0044] Referring to Figure 2b) Figure, the hetero layer 13 is substantially different from the material of the patterned substrate, with light transmission and high dielectric properties, which can be an oxide, nitride, carbide or an element, exemplarily, the oxide can be SiOx, ZnO, TiOx, TaOx, HfO2, ZrOx, AlOx, GaOx, MgOx, BaOx, InOx, SnO2, LiOx, CaOx, CuOx, IrOx, RhOx, CdGeO, InGaZnO, ZnRhO, GaIn2O4, LaO, LaCuO, etc., the nitride can be SiNx, TiN, WN, CN, BN, LiN, TiON, SiON, CrN, CrNO, etc., the carbide can be SiC, HfC, ZrC, WC, TiC, CrC, etc., and the element can be diamond, Si, Mo, Cu, Fe, Ag, Wu, Ni, Al, etc.

[0045] Optionally, a hetero layer 13 is formed on the patterned substrate, including: using a chemical vapor deposition process to deposit the hetero layer at a deposition rate less than 10 nm / min and a chamber pressure less than 1.2 mT. Using the above deposition rate and chamber pressure, the hetero layer material can effectively fill the pits 12.

[0046] S130, the hetero layer 13 is patterned to form a plurality of hetero pattern structures, each of which corresponds to cover the protruding microstructure 11 and the pit 12 adjacent to the protruding microstructure 11.

[0047] Reference Figure 2 c) Figure, a layer of hetero film with a thickness of 50-300 nm is plated on the pit type PSS surface by a vapor deposition method (PECVD), the hetero layer 13 after forming a plurality of hetero pattern structures covers the protruding microstructure 11 and the pit 12, covers the pattern and still maintains the protruding pattern topography, rather than completely filling the gap to make the surface tend to be flat. Similarly, the adjacent hetero pattern structures after patterning here cover the respective protruding microstructure 11 and pit 12, and the C surface between the two protruding microstructures 11 on the patterned substrate in the middle region is exposed, to ensure that when epitaxial growth is used on the patterned composite substrate, the crystal nucleus is formed by epitaxial growth through the C surface between the two protruding microstructures 11 covered with the hetero pattern structure.

[0048] As described above, the patterned substrate provided in this embodiment of the invention includes a substrate and multiple raised microstructures and multiple pits formed on the surface of the substrate, with the pits surrounding the raised microstructures; a heterogeneous layer is formed on the patterned substrate; the heterogeneous layer is patterned to form multiple heterogeneous patterned structures, each heterogeneous patterned structure correspondingly covering the raised microstructures and the pits adjacent to the raised microstructures. Specifically, this embodiment of the invention solves the problem that PSSs with pits generated during production cannot be used, increasing manufacturing costs, and enables PSSs with pits to be reprocessed into reusable PSSs, improving the effective product yield and reducing manufacturing costs.

[0049] Figure 4 This is a flowchart of another method for reusing pitted PSS provided by an embodiment of the present invention. Figure 5 yes Figure 4 The flowchart of the pitted PSS reuse method shown is for reference. Figure 4 and Figure 5 The method for reusing this pitted PSS includes:

[0050] S210. The patterned substrate is inspected, and patterned substrates with pit width greater than 35nm and depth greater than 15nm are selected.

[0051] refer to Figure 5 As shown in Figure d), when the width of the pit is greater than 35nm and the depth is greater than 15nm, the patterned substrate will increase the risk of use by the epitaxial client, that is, it is determined that the product cannot be shipped. The patterned substrate is prepared when the above-mentioned patterned substrate is detected by atomic force microscopy (AFM).

[0052] S220. A patterned substrate is provided, the patterned substrate including a substrate 10 and a plurality of raised microstructures 11 and a plurality of pits 12 formed on the surface of the substrate 10, the pits 12 surrounding the raised microstructures 11.

[0053] S230, A heterogeneous layer 13 is formed on a patterned substrate;

[0054] S240. Coating photoresist to form a photoresist layer 14 on the heterogeneous layer;

[0055] refer to Figure 5 As shown in Figure f), a photoresist layer 14 with a thickness of 2.0–4.0 µm is formed on the heterolayer 13 using positive or negative photoresist through coating processes such as spraying or spin coating.

[0056] S251, exposing and developing the photoresist layer 14 to form a plurality of photoresist columns 15, the vertical projection of the photoresist columns 15 on the plane of the substrate 30 one-to-one covers the vertical projection of the protruding microstructure 11 and the adjacent pit 12 on the plane of the substrate 10;

[0057] Referring to Figure 5 g) of FIG., aligning and exposing so that the photoresist columns 15 are located directly above the protruding microstructure 11 and the surrounding pits 12, it is emphasized that in order to ensure that the pits 12 that have been filled and covered will not be etched again, the bottom film width of the photoresist columns 15 is greater than or equal to the sum of the bottom width of the protruding microstructure 11 and the width of the two side pits 12.

[0058] S252, using the photoresist columns 15 as a mask, etching the hetero-layer 13 until the area between the protruding microstructures 11 exposes the surface of the substrate 10;

[0059] Referring to Figure 5 h) of FIG., the etching process of the hetero-layer 13 can be achieved by using an inductively coupled plasma (ICP) etching process, and the present embodiment provides specific process parameters for the specific ICP plasma etching process. Specifically, using the photoresist columns 15 as a mask, pure boron trichloride (BCl3) gas is used as the etching gas, the gas flow is 50sccm~90sccm, the upper electrode power of the etching machine is set to 800W~1000W, the lower electrode power is set to 300W~400W, the cavity pressure is set to 1.5mT~4mT, and the etching time is set to 5min~15min; This process is mainly based on pure physical bombardment, and the exposure of the C face of the hetero-layer 13 just etched is the cut-off time point.

[0060] S260, using organic cleaning to remove residual photoresist columns 15.

[0061] Referring to Figure 5 i) of FIG., using organic cleaning to remove residual photoresist, for example, acetone can be used to clean the photoresist, and the patterned composite substrate 100 structure is obtained after organic cleaning.

[0062] From the above, in the embodiment of the present application, first, the width of the pit is greater than 35nm, and the depth of the pit is greater than 15nm, and a hetero layer is formed on the patterned substrate, and a photoresist layer is formed on the hetero layer, and the photoresist layer is exposed and developed to form a plurality of photoresist columns, it should be noted that the vertical projection of the photoresist column on the substrate plane one-to-one covers the vertical projection of the convex microstructure and the pit adjacent to the convex microstructure on the substrate plane, through the above arrangement, the photoresist column can be located directly above the convex microstructure and the pit around it; the hetero layer is etched with the photoresist column as a mask until the substrate surface is exposed between the convex microstructures, the residual photoresist column is removed with an organic material, and finally a patterned composite substrate is obtained, which can realize the reuse of the pit type PSS. Specifically, the embodiment of the present application can solve the problem that the PSS cannot be used after the pit is generated, reduce the effective delivery rate of the product, and increase the manufacturing cost. A new way is provided for the reuse of the pit type PSS, the PSS with pits can be reused through the reuse method of the embodiment of the present application, the effective delivery rate of the product is improved, and the manufacturing cost is reduced.

[0063] Based on the same inventive concept, Figure 6 is a structural schematic diagram of a patterned composite substrate 100 provided by the embodiment of the present application. Referring to Figure 6 The patterned composite substrate 100 comprises a substrate 10, a plurality of convex microstructures 11 and a plurality of pits 12 are formed on the surface of the substrate 10, and the pit 12 surrounds the convex microstructure 11; a hetero pattern structure, the hetero pattern structure one-to-one covers the convex microstructure 11 and the pit 12 adjacent to the convex microstructure 11.

[0064] Optionally, the hetero pattern structure comprises a side wall part and a plane part, the side wall part covers the side wall of the convex microstructure 11, and the plane part covers at least part of the area between the convex microstructures 11 on the surface of the substrate 10 and the pit 12.

[0065] The thickness R of the side wall part is greater than the height H of the plane part on the surface of the substrate 10.

[0066] Optionally, the thickness R of the side wall part is 50-300nm, and the height H of the plane part on the surface of the substrate 10 is 20-100nm.

[0067] Specifically, the low height H of the plane part on the substrate surface can provide sufficient longitudinal space for the growth of the epitaxial layer buffer layer, on the other hand, the large thickness of the side wall part thickness R is beneficial to the multi-layer refraction, reflection and escape of photons.

[0068] Optionally, the distance between adjacent heterogeneous pattern structures is W1 and the distance between adjacent pits 12 is W2, and W1:W2>50%.

[0069] Specifically, W1:W2>50% provides sufficient process window for alignment exposure on the one hand, and provides sufficient lateral space for the growth of the epitaxial layer buffer layer on the other hand.

[0070] Optionally, the bottom width of the convex microstructure 11 ranges from 1.5 to 4.5 microns, and the height ranges from 1.0 to 3.0 microns.

[0071] Optionally, the convex microstructure 11 has a sidewall curvature, and the sidewall convex height ranges from 80 to 200 nanometers.

[0072] Optionally, the duty cycle of the convex microstructure 11 on the surface of the substrate 10 is greater than 80%.

[0073] Reference Figure 6 The duty cycle of the convex microstructure 11 on the surface of the substrate 10 is greater than 80%, which means that the convex microstructure 11 has a larger surface area on the substrate 10, and the bottom gap is small. At this time, under the condition of low pressure and low deposition rate, active particles tend to adhere to the upper part of the convex microstructure 11, and relatively few to the bottom. Therefore, the thickness R of the sidewall part is greater than the height H of the planar part on the surface of the substrate 10.

[0074] The patterned composite substrate provided by the embodiment of the present application comprises: a substrate, a plurality of convex microstructures and a plurality of pits are formed on the surface of the substrate, the pits surround the convex microstructures, a heterogeneous pattern structure, the heterogeneous pattern structure corresponds to one-to-one covering the convex microstructure and the pit adjacent to the convex microstructure, the heterogeneous pattern structure comprises a sidewall part and a planar part, the sidewall part covers the sidewall of the convex microstructure, the planar part covers the pit and at least part of the area between the convex microstructures on the surface of the substrate, and the thickness of the sidewall part is greater than the height of the planar part on the surface of the substrate. By reasonably designing the above structure, the quality of the patterned composite substrate can be improved. Specifically, the embodiment of the present application can solve the problem that the PSS cannot be used after the pits are generated, reduce the effective delivery rate of the product, and increase the manufacturing cost. A new way is provided for the reuse of the pit type PSS. The pit type PSS generated can be reused by the reuse method of the embodiment of the present application, the effective delivery rate of the product is improved, and the manufacturing cost is reduced.

[0075] Based on the patterned composite substrate provided in the above embodiment, the embodiment of the present application further provides an LED epitaxial wafer, Figure 7 is a structure diagram of an LED epitaxial wafer provided by the embodiment of the present application, referring to Figure 7The LED epitaxial wafer comprises any one of the patterned composite substrates 100 provided by the embodiments of the present application and the epitaxial layer 200 formed on the patterned composite substrate 100.

[0076] For forming epitaxial layers on different material hetero-microstructures, different LED epitaxial wafer growth technologies are required, and for the patterned composite substrate 100 provided by the embodiments of the present application, the epitaxial layer 200 on the LED epitaxial wafer can be a GaN, AlGaN epitaxial layer, etc. The LED epitaxial wafer adopts the patterned composite substrate 100 provided by the above embodiments, and thus has the same beneficial effects as the patterned composite substrate 100.

[0077] Note that the above are only preferred embodiments of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustments, mutual combinations and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A method for reusing pitted PSS, characterized in that, include: A patterned substrate is provided, the patterned substrate including a substrate and a plurality of raised microstructures and a plurality of pits formed on the surface of the substrate, the pits surrounding the raised microstructures; A heterogeneous layer is formed on the patterned substrate; The heterogeneous layer is patterned to form multiple heterogeneous pattern structures, each heterogeneous pattern structure correspondingly covering the protruding microstructure and the pit adjacent to the protruding microstructure. After forming a heterogeneous layer on the patterned substrate, the method further includes: Photoresist is coated onto the heterogeneous layer to form a photoresist layer. The heterogeneous layer is patterned to form multiple heterogeneous patterned structures, each heterogeneous patterned structure correspondingly covering the protruding microstructure and the pit adjacent to the protruding microstructure, including: The photoresist layer is exposed and developed to form multiple photoresist pillars. The vertical projection of the photoresist pillars onto the plane of the substrate corresponds to the vertical projection of the protruding microstructure and the pit adjacent to the protruding microstructure onto the plane of the substrate. Using the photoresist pillars as a mask, the heterolayer is etched until the area between the protruding microstructures is exposed on the substrate surface.

2. The reuse method according to claim 1, characterized in that, A heterogeneous layer is formed on the patterned substrate, comprising: The heterogeneous layer was deposited using a chemical vapor deposition process at a deposition rate of less than 10 nm / min and a chamber pressure of less than 1.2 mT.

3. The reuse method according to claim 1, characterized in that, Using the photoresist pillars as a mask, the heterolayer is etched until the area between the protruding microstructures is exposed on the substrate surface, and then the process further includes: Organic methods are used to remove residual photoresist pillars.

4. The reuse method according to claim 1, characterized in that, Before providing the patterned substrate, including: The patterned substrates are inspected, and patterned substrates with a pit width greater than 35nm and a depth greater than 15nm are selected.

5. A patterned composite substrate, characterized in that, The patterned composite substrate is manufactured by the method for reusing the pit-type PSS according to any one of claims 1-4, and the patterned composite substrate comprises: A substrate having a plurality of raised microstructures and a plurality of pits formed on its surface, the pits surrounding the raised microstructures; A heterogeneous pattern structure, wherein the heterogeneous pattern structure covers the raised microstructure and the pit adjacent to the raised microstructure in a one-to-one correspondence.

6. The patterned composite substrate according to claim 5, characterized in that, The heterogeneous pattern structure includes a sidewall portion and a planar portion, the sidewall portion covering the sidewall of the raised microstructure, and the planar portion covering the pit and at least a portion of the substrate surface located between the raised microstructures; The thickness of the sidewall portion is greater than the height of the planar portion on the substrate surface.

7. The patterned composite substrate according to claim 6, characterized in that, The thickness of the sidewall portion ranges from 50 to 300 nm, and the height of the planar portion on the substrate surface ranges from 20 to 100 nm.

8. The patterned composite substrate according to claim 5, characterized in that, The spacing between adjacent heterogeneous pattern structures, W1, and the spacing between adjacent pits, W2, satisfy the condition: W1:W2 > 50%.

9. The patterned composite substrate according to claim 5, characterized in that, The bottom width of the protruding microstructure ranges from 1.5 to 4.5 μm, and the height ranges from 1.0 to 3.0 μm.

10. The patterned composite substrate according to claim 5, characterized in that, The protruding microstructure has a sidewall curvature, and the height of the sidewall protrusion ranges from 80 to 200 nm.

11. The patterned composite substrate according to claim 5, characterized in that, The protruding microstructure has a duty cycle of more than 80% on the substrate surface.

12. An LED epitaxial wafer, characterized in that, Including the patterned composite substrate as described in any one of claims 5-11.

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