TWI626767B - Ultraviolet light-emitting diode and its substrate and the substrate thereof law - Google Patents

Abstract

A substrate of an ultraviolet light emitting diode comprises a substrate having a patterned structure and a patterned buffer layer; the method for manufacturing the substrate comprises providing a substrate, and a buffer layer is disposed on the surface of the substrate, And forming a buffer layer on the buffer layer, and forming a patterned structure on the surface of the substrate, and then removing the patterned mask layer; an ultraviolet light emitting diode comprising the substrate and disposed thereon At least one epitaxial layer on the patterned buffer layer, and a multilayer semiconductor structure disposed on the epitaxial layer. By using the substrate formed by the above method, the patterned buffer layer in the substrate still retains the characteristics of a single lattice orientation, and the ultraviolet light-emitting diode formed on the substrate can achieve better luminous efficiency.

Description

Ultraviolet light-emitting diode and its substrate and the substrate thereof law

The invention relates to an ultraviolet light emitting diode; in particular to a substrate capable of providing a more luminous efficiency ultraviolet light emitting diode, an ultraviolet light emitting diode, and a manufacturing method of the substrate.

Ultraviolet light-emitting diodes can be used in medical, biomedical, sterilization and biometric applications. At present, there are mainly two kinds of substrates of ultraviolet light-emitting diodes. The first type of substrate is formed by growing an aluminum nitride epitaxial layer by hetero-epitaxial growth on a non-aluminum nitride substrate to form a substrate, and then nitriding. Due to the mismatch of the lattice constant between the aluminum epitaxial layer and the substrate, the defect density of the epitaxial layer is high, especially the density of the difference, and the defect will absorb ultraviolet light, thus affecting the ultraviolet light diode. The luminous efficiency makes the luminous efficiency poor. The second substrate is an aluminum nitride substrate, and the aluminum nitride substrate has a low defect density. Therefore, the ultraviolet light-emitting diode made of the aluminum nitride substrate has high luminous efficiency and long life, and the ultraviolet light is made of an aluminum nitride substrate. The light-emitting diode has the aforementioned advantages. However, the current technical difficulty in manufacturing an aluminum nitride substrate is high, so that the productivity of the aluminum nitride substrate is low and the price is high. Therefore, the use of ultraviolet light-emitting diodes is hindering the luminous efficiency and price, and its application is still not popular.

In view of the above, an object of the present invention is to provide an ultraviolet light emitting diode and a substrate thereof and a method of manufacturing the same, which are used to improve the luminous efficiency of the ultraviolet light emitting diode.

In order to achieve the above object, a substrate for an ultraviolet light-emitting diode according to the present invention includes: a substrate having a surface, the surface being formed with a patterned structure, the patterned structure having a plurality of recesses therefrom a surface concave formation and a plurality of convex portions are located between the concave portions, a top surface of the convex portions forming a part of the surface; a patterned buffer layer having a plurality of convex portions and a plurality of hollow regions, The protrusions are respectively disposed on the top surfaces of the protrusions and are located in the orthographic projection range of the top surfaces of the protrusions, and the protrusions have a thickness of 15 to 2000 nm and the material includes AlN _x O _y , wherein x is between 0.7 and 1, and y is between 0 and 0.3; each of the protrusions has a C-axis oriented top surface; and the hollow regions are in communication with the depressions.

The method for manufacturing a substrate of an ultraviolet light emitting diode according to the present invention comprises the following steps: A. providing a substrate having a surface; B. providing a buffer layer on the surface of the substrate; The material of the buffer layer comprises AlN _x O _y , wherein x is between 0.7 and 1, y is between 0 and 0.3; the upper surface of the buffer layer is C-axis oriented; C. is on the buffer layer a patterned mask layer is disposed on the surface, the patterned mask layer has a plurality of recesses; D. etching the buffer layer and the substrate under the recesses to remove buffers under the recesses a portion of the layer such that the buffer layer forms a patterned buffer layer; and removing a portion of the substrate below the recess to form a patterned structure on the surface of the substrate, wherein the portion of the substrate removed Forming a plurality of recessed portions of the patterned structure, the portion of the substrate between the recessed portions forming a plurality of raised portions of the patterned structure; E. removing the patterned mask layer.

The ultraviolet light emitting diode of the present invention further comprises: the substrate of the ultraviolet light emitting diode; the at least one epitaxial layer disposed on the patterned buffer layer; The layered semiconductor structure includes a first type doped semiconductor layer, a light emitting layer and a second type doped semiconductor layer, wherein the first type doped semiconductor layer contacts the at least one epitaxial layer, and the luminescent layer is located Between the first type doped semiconductor layer and the second type doped semiconductor layer.

The effect of the invention is that after the buffer layer is disposed on the surface of the substrate, the substrate and the buffer layer are etched to form a single structure of the patterned mask layer to achieve the effect of improving luminous efficiency.

〔this invention〕

100‧‧‧Ultraviolet LED epitaxial substrate and manufacturing method thereof

1, 1'‧‧‧ substrate

1a‧‧‧ raised structure

1b‧‧‧ recessed structure

10‧‧‧Substrate

10a, 10a’‧‧‧ surface

11‧‧‧Depression

12‧‧‧ raised parts

20‧‧‧buffer layer

20a‧‧‧ upper surface

20’‧‧‧ patterned buffer layer

21‧‧‧镂空区

22‧‧‧ convex

30‧‧‧ patterned mask layer

31‧‧‧ recess

32‧‧‧Bumps

30'‧‧‧ mask layer

2‧‧‧Ultraviolet light-emitting diode

40‧‧‧ epitaxial layer

41‧‧‧First epitaxial layer

42‧‧‧Second epilayer

50‧‧‧Multilayer semiconductor structure

51‧‧‧First type doped semiconductor layer

52‧‧‧Lighting layer

53‧‧‧Second type doped semiconductor layer

T‧‧‧ thickness

W1‧‧‧ bottom width

W2‧‧‧ top width

W3‧‧ depth

1 is a flow chart showing a method of manufacturing a substrate for an ultraviolet light emitting diode according to a first preferred embodiment of the present invention.

2 is a schematic view showing a manufacturing process of a substrate for an ultraviolet light emitting diode according to the above preferred embodiment.

3 is a schematic view of a substrate for an ultraviolet light emitting diode according to the above preferred embodiment.

4 is a partial perspective view of the substrate for the ultraviolet light emitting diode of the above preferred embodiment.

Figure 5 is a partial perspective view of a substrate for an ultraviolet light emitting diode according to a second preferred embodiment of the present invention.

Fig. 6 is a schematic view showing an ultraviolet light-emitting diode made of a substrate according to a first preferred embodiment of the present invention.

In order to explain the present invention more clearly, several preferred embodiments are described in detail with reference to the drawings. Referring to FIG. 1 , the first preferred embodiment of the present invention is used for ultraviolet light. A flow chart of a method of manufacturing a substrate of a light-emitting diode, and a step of fabricating the substrate 1 of FIG. 3 will be described later with reference to FIG.

As shown in FIG. 2(A), a substrate 10 is first provided. The substrate 10 is a sapphire substrate 10 in this embodiment, and the substrate 10 has a flat shape with upper and lower phases facing away from each other. Two surfaces 10a, 10a'. In practice, the substrate 10 may also be made of a tantalum substrate 10 or a tantalum carbide substrate 10, and is not limited thereto. A buffer layer 20 is disposed directly on one surface 10a of the substrate 10, and the buffer layer 20 is made of AlN _x O _y , wherein x is between 0.7 and 1, and y is between 0 and 0.3, and The upper surface 20a of the buffer layer 20 is oriented in the C-axis. The buffer layer 20 is plated by high temperature reactive sputtering, atomic layer deposition (ALD), molecular beam epitaxy (MBE), or MOCVD process.

The substrate 10 provided with the buffer layer 20 is annealed in a shielding gas, wherein the shielding gas comprises one or at least two gases including at least one of an inert gas and nitrogen, but does not contain carbon. The element or the oxygen-containing element prevents the oxygen content in the buffer layer 20 from remaining, or causes the buffer layer 20 to reduce and carburize due to the carbon-containing gas, thereby causing light absorption to affect the transmittance of the substrate 1. The annealing temperature is 1500 ° C or higher to recombine the atoms in the buffer layer 20 to achieve the effect of reducing defects. In addition, less than or equal to 10% of hydrogen may be added to the shielding gas to etch the defects of the buffer layer 20 to further reduce the defect density. By this annealing treatment, the difference in discharge density at the surface layer of the buffer layer 20 away from the substrate end can be reduced to 1 × 10 ⁹ /cm ² or less, and the optimum value can be reduced to 1 × 10 ⁸ /cm ² or less.

Then, a patterned mask layer 30 is further disposed on the upper surface 20a of the buffer layer 20. Referring to FIG. 2 (A, B), the patterned mask layer 30 is formed by a photoresist coating technique or the like, and a smooth mask layer 30 ′ is disposed before the upper surface 20 a of the buffer layer 20 . Use yellow light lithography, or use nano transfer technology, such as hot pressing into the form of nano transfer, light The mask layer 30' is formed into a patterned mask layer 30 having a plurality of recesses 31 and a plurality of bumps 32 on the surface.

Thereafter, the patterned mask layer 30 is etched, for example, by plasma etching or high temperature wet chemical etching, but is not limited thereto, so that the surface 10a of the substrate 10 is formed with a patterned structure, and The buffer layer 20 forms a patterned buffer layer 20'. 2(C), when the etching is performed, the buffer layer 20 under the recesses 31 and a portion of the substrate 10 are removed, wherein the portion of the buffer layer 20 that is removed constitutes the patterned buffer layer 20'. The cutout portion 21, the portion of the substrate 10 that is removed constitutes a plurality of recesses 11 of the patterned structure, and the recessed portions 11 are recessed from the surface 10a; the hollow regions 21 and the recess portions 11 The same.

The buffer layer 20 and the substrate 10 under the bumps 32 are retained by being covered by the thicker region of the patterned mask layer 30, and the remaining portion of the substrate 10 constitutes the raised portion of the patterned structure. 12, and the protrusions 12 are located between the recesses 11. The top surface of the protrusions 12 constitute a part of the surface 10a of the substrate 10; the remaining portion of the buffer layer 20 forms the patterned buffer layer The protrusions 22 of the 20', the thicknesses T of the protrusions 22 are between 15 and 2000 nm, and are respectively disposed directly on the top surfaces of the protrusions 12, and are orthographic projections on the top surfaces of the protrusions 12 In addition, the side walls of each of the raised portions 12 are connected to the side walls of the respective convex portions 22 provided thereon.

As shown in FIG. 2(D), after the bump 32 remaining on the convex portion 22 is removed, the substrate 1 is completed. The surface of the substrate 1 includes a plurality of convex structures 1a composed of the convex portions 12 and the convex portions 22 above, and a plurality of the hollow regions 21 and the concave portions 11 connected by the plurality of the hollow portions 21 and the concave portions 11 The recessed structure 1b is formed, and one of the adjacent convex structures 1a and the recessed structure 1b constitute a primary structure.

By the above-described design of the substrate 1 step, the top surface including the AlN _x O _y patterned buffer layer 20' can be formed into a single orientation (C-axis orientation) to achieve better light transmittance.

Please cooperate with Figure 3, the sub-structures meet the following conditions:

1. The bottom width W1 of the substructures (i.e., the width of the bottom of the raised portion 12 and the adjacent one of the recessed portions 11) is between 0.1 and 5 μm, wherein in the preferred state, the bottom width W1 is between 0.5 and 0.5. ~3μm.

2. The ratio of the top width W2 of the substructures (i.e., the top surface width of the convex portion 22 of one of the patterned buffer layers 20') to the bottom width W1 of the substructures is greater than or equal to 0.5.

3. The depth W3 of the substructures (i.e., the distance from the top surface of each of the protrusions 22 to the adjacent one of the recesses 11) is between 0.1 and 2.5 μm.

The substrate 10 and the buffer layer 20 are formed into the sub-structure by patterning the mask layer and the etching process, and by the above conditions, the problem of abnormal growth of the epitaxial process in an unexpected region can be reduced, and the LED is completed. After component processing, the light extraction efficiency can be improved by refraction, diffraction or anti-reflection effects.

The protruding structures 1a in this embodiment have a flat-topped cone as shown in FIG. 4, but are not limited thereto, and may also be a flat-topped pyramid, a flat-top spherical surface or an irregular structure; In the substrate 1 ′ of the second preferred embodiment of the present invention, the recessed structures 1 b of the substrate 1 ′ have a cup shape, but are not limited thereto, and may also have a conical shape, a pyramid shape, a bowl shape or an irregular structure. . Of course, the raised structures 1a and the recessed structures 1b may also be a combination of two or more shapes.

As shown in FIG. 6 , the ultraviolet light emitting diode 2 is further provided with at least one epitaxial layer 40 and a multilayer semiconductor structure 50 on the substrate 1 of the first preferred embodiment, wherein the at least one Lei The seed layer 40 contains at least one of AlN and AlGaN.

In this embodiment, the number of the epitaxial layers 40 is two, which are a first epitaxial layer 41 containing AlN and a second epitaxial layer 42 containing AlGaN. The first epitaxial layer 41 and the second epitaxial layer 42 can be formed by sputtering, HVPE, or MOCVD. The first epitaxial layer 41 is disposed on the substrate 1 and is not filled with the recessed portion 11 of the substrate 10 and the hollowed-out region 21 of the patterned buffer layer 20 ′ to form a void; the second epitaxial layer 42 is formed. The first epitaxial layer 41 is disposed on the first epitaxial layer 41.

The multilayer semiconductor structure 50 includes a first type doped semiconductor layer 51, a light emitting layer 52 and a second type doped semiconductor layer 53, wherein the first type doped semiconductor layer 51 contacts the second epitaxial layer 42. The second epitaxial layer 42 is disposed between the first epitaxial layer 41 and the first doped semiconductor layer 51; the luminescent layer 52 is located at the first doped semiconductor layer 51 and the second doped layer Between the semiconductor layers 53. The ultraviolet light emitted from the luminescent layer 52 will pass through the cavity formed by the recess 11 and the hollow region 21, and will be permeable from the substrate 10 to increase the light extraction rate.

According to the present invention, the substrate 1 for the ultraviolet light-emitting diode 2 and the method for fabricating the same can form a structure in which the patterned buffer layer 20 ′ located on the surface 10 a of the substrate 10 has a single orientation and has few defects. The ultraviolet light-emitting diode 2 made of the substrate 1 can achieve the effect of improving luminous efficiency.

The above is only a preferred embodiment of the present invention, and equivalent changes to the scope of the present invention and the scope of the patent application are intended to be included in the scope of the present invention.

Claims (19)

A substrate for an ultraviolet light emitting diode, comprising: a substrate having a surface, the surface being formed with a patterned structure having a plurality of recesses recessed from the surface and a plurality of protrusions Located between the recesses, a top surface of the protrusions forms a part of the surface; a patterned buffer layer having a plurality of protrusions and a plurality of hollow regions, the protrusions being directly disposed on the protrusions The top surface of the starting portion is located in the orthographic projection range of the top surface of the convex portions, and the convex portions have a thickness of 15 to 2000 nm and the material includes AlN _x O _y , wherein x is between 0.7 and 1 The y is between 0 and 0.3; each of the protrusions has a C-axis oriented top surface; and the hollow regions are in communication with the recesses. The substrate of the ultraviolet light-emitting diode according to claim 1, wherein the bottom of each of the convex portions and the convex portion disposed above the convex portion, and one of the concave portions adjacent thereto and the hollow portion communicating with the concave portion are hollowed out The regions constitute a primary structure; the bottom width of each of the secondary structures is between 0.1 and 5 μm. The substrate of the ultraviolet light emitting diode according to claim 2, wherein a bottom width of each of the substructures is between 0.5 and 3 μm. The substrate of the ultraviolet light emitting diode according to claim 1, wherein a distance from a top surface of each of the convex portions to an adjacent one of the concave portions is between 0.1 and 2.5 μm. The substrate of the ultraviolet light-emitting diode according to claim 1, wherein the bottom of each of the convex portions and the convex portion disposed above the convex portion, and one of the concave portions adjacent thereto and the hollow portion communicating with the concave portion are hollowed out The regions constitute a primary structure; the ratio of the top surface width of each of the convex portions to the bottom width of each of the secondary structures is greater than or equal to 0.5. The substrate of the ultraviolet light emitting diode according to claim 1, wherein the substrate is a sapphire, tantalum or tantalum carbide material. The substrate of the ultraviolet light-emitting diode according to claim 6, wherein the convex portion and each of the convex portions disposed thereon are formed into a flat-topped cone, a flat-topped pyramid, and a flat-topped spherical surface. At least one of the irregular structures. The substrate of the ultraviolet light-emitting diode according to claim 1, wherein each of the hollow regions and the corresponding recessed portion are in the shape of a cup, a cone, a pyramid, a bowl and an irregular structure. At least one of them. The substrate of the ultraviolet light-emitting diode according to claim 1, wherein a difference in density of the patterned buffer layer away from the surface of the substrate is 1×10 ⁹ /cm ² or less. An ultraviolet light emitting diode comprising: one of the substrates of the ultraviolet light emitting diodes according to the above claims 1 to 9; at least one epitaxial layer disposed on the patterned buffer layer; The layered semiconductor structure includes a first type doped semiconductor layer, a light emitting layer and a second type doped semiconductor layer, wherein the first type doped semiconductor layer contacts the at least one epitaxial layer, and the luminescent layer is located Between the first type doped semiconductor layer and the second type doped semiconductor layer. The ultraviolet light emitting diode of claim 10, wherein the at least one epitaxial layer comprises at least one of AlN and AlGaN. The ultraviolet light emitting diode of claim 11, wherein the at least one epitaxial layer comprises a first epitaxial layer containing AlN, and a second epitaxial layer containing AlGaN, the second epitaxial layer being located The first epitaxial layer is between the first doped semiconductor layer. A method for manufacturing a substrate of an ultraviolet light-emitting diode comprises the following steps: A. providing a substrate having a surface; B. providing a buffer layer on the surface of the substrate, the buffer layer The material comprises AlN _x O _y , wherein x is between 0.7 and 1, y is between 0 and 0.3; the upper surface of the buffer layer is C-axis oriented; C. a pattern is disposed on the upper surface of the buffer layer a mask layer having a plurality of recesses; D. etching the buffer layer and the substrate under the recesses to remove portions of the buffer layer under the recesses, Forming the buffer layer into a patterned buffer layer; and removing a portion of the substrate under the recesses to form a patterned structure on the surface of the substrate, wherein the removed portion of the substrate constitutes the patterning a plurality of recesses of the structure, the substrate between the recesses forming a plurality of protrusions of the patterned structure; E. removing the patterned mask layer. The method for producing a substrate of an ultraviolet light-emitting diode according to claim 13, wherein the substrate provided with the buffer layer is further annealed between the steps B and C, and the annealing temperature is 1500 ° C or higher. The method for manufacturing a substrate of an ultraviolet light-emitting diode according to claim 14, wherein the substrate provided with the buffer layer is annealed in a shielding gas between steps B and C, and the shielding gas does not include A gas with carbon or oxygen. The method of manufacturing a substrate of an ultraviolet light-emitting diode according to claim 15, wherein the shielding gas contains at least one of an inert gas and nitrogen. The method of manufacturing a substrate of an ultraviolet light-emitting diode according to claim 15, wherein the shielding gas contains less than or equal to 10% of hydrogen. The method of manufacturing a substrate of an ultraviolet light-emitting diode according to claim 15, wherein the shielding gas may be a mixture of two or more gases. The method for fabricating a substrate of an ultraviolet light-emitting diode according to claim 15, wherein the buffer layer is plated by high temperature reactive sputtering, atomic layer deposition (ALD), molecular beam epitaxy (MBE), or MOCVD process. .