阅读说明：本技术 图形化衬底、led外延结构及图形化衬底制造方法 (Patterned substrate, LED epitaxial structure and patterned substrate manufacturing method ) 是由 不公告发明人 于 2020-05-29 设计创作，主要内容包括：本发明提供一种图形化衬底、LED外延结构及图形化衬底制造方法,图形化衬底包括基板、缓冲层以及图形化层；缓冲层设于所述基板之上,图形化层设于缓冲层背离基板的一侧；图形化层包含多个微结构,相邻两个微结构之间间隔一间隙露出缓冲层形成生长区,微结构的表面形成多个凹陷的次级微结构。通过将表面形成有次级微结构的微结构设于缓冲层之上,从而,一方面,通过微结构表面的次级微结构,能够提前释放在生长过程中产生的应力,也可对有源层产生的光形成多次反射,增加轴向出光率；另一方面,将微结构设于缓冲层之上,减少了半导体层侧向生长产生的穿透位错,同时提高了半导体层和图形化衬底之间的折射率差值,更有利于LED出光效率的提高。(The invention provides a patterned substrate, an LED epitaxial structure and a patterned substrate manufacturing method, wherein the patterned substrate comprises a substrate, a buffer layer and a patterned layer; the buffer layer is arranged on the substrate, and the patterning layer is arranged on one side of the buffer layer, which is far away from the substrate; the patterning layer comprises a plurality of microstructures, a gap is arranged between every two adjacent microstructures to expose the buffer layer to form a growth region, and a plurality of sunken secondary microstructures are formed on the surfaces of the microstructures. The microstructure with the secondary microstructure formed on the surface is arranged on the buffer layer, so that on one hand, the stress generated in the growth process can be released in advance through the secondary microstructure on the surface of the microstructure, and the light generated by the active layer can be reflected for multiple times, so that the axial light extraction rate is increased; on the other hand, the microstructure is arranged on the buffer layer, so that the threading dislocation generated by the lateral growth of the semiconductor layer is reduced, the refractive index difference between the semiconductor layer and the patterned substrate is improved, and the improvement of the light emitting efficiency of the LED is facilitated.)

1. A patterned substrate, characterized by:

the patterned substrate comprises a substrate, a buffer layer and a patterned layer;

the buffer layer is arranged on the substrate, and the graphical layer is arranged on one side of the buffer layer, which is far away from the substrate;

the patterned layer comprises a plurality of microstructures, every two adjacent microstructures are spaced by a gap and exposed out of the buffer layer to form a growth region, and a plurality of sunken secondary microstructures are formed on the surfaces of the microstructures.

2. The patterned substrate of claim 1 wherein: the patterned layer is a silicon dioxide layer.

3. The patterned substrate of claim 2, wherein: the buffer layer is a nitride buffer layer, and the thickness range of the buffer layer is 0.1 nm-1 mu m.

4. The patterned substrate of claim 3, wherein: the buffer layer is provided with a protruding microstructure substrate at the joint of the buffer layer and the microstructure, the microstructure is arranged on the microstructure substrate, and the thickness of the microstructure substrate is larger than or equal to that of the buffer layer.

5. The patterned substrate of claim 4, wherein: the shape of the lower end face of the microstructure is consistent with that of the upper end face of the microstructure substrate, and the lower end face of the microstructure and the upper end face of the microstructure substrate are in seamless joint to form a smooth outer wall face together.

6. The patterned substrate of claim 5, wherein: the total thickness range of the microstructure and the microstructure substrate is 0.1-5 μm, and the outer diameter range of the bottom of the microstructure substrate is 1-10 μm.

7. The patterned substrate of claim 1 wherein: the length range of the growth region is 0.1-3 mu m.

8. An LED epitaxial structure, characterized in that: the LED epitaxial structure comprises the patterned substrate as claimed in any one of claims 1 to 7, and a semiconductor layer formed on the patterned substrate, the semiconductor layer growing up the growth region.

9. A method of manufacturing a patterned substrate, comprising the steps of:

providing a substrate;

sequentially growing a buffer layer and a patterning layer on the substrate;

manufacturing a photoresist mask layer on the patterning layer, wherein the photoresist mask layer forms a plurality of microstructure mask areas, and each microstructure mask area comprises a plurality of secondary microstructure mask areas;

and etching the photoresist mask layer, the patterning layer and the buffer layer in sequence to form a plurality of microstructures, wherein a plurality of secondary microstructures are formed on the surface of each microstructure.

10. The method for manufacturing a patterned substrate according to claim 9, wherein: "sequentially etching the photoresist mask layer, the patterned layer, and the buffer layer to form a plurality of microstructures" includes:

etching the photoresist layer and the patterned layer under a first gas condition;

etching the buffer layer under the second gas condition.

11. The method for manufacturing a patterned substrate according to claim 10, wherein: the first gas condition is a mixed gas of chlorine and boron trichloride in a first preset proportion, and the second gas condition is a mixed gas of chlorine and boron trichloride in a second preset proportion.

Technical Field

The invention relates to the field of semiconductor light-emitting devices, in particular to a patterned substrate, an LED epitaxial structure and a patterned substrate manufacturing method.

Background

As a novel energy-saving and environment-friendly solid-state illumination Light source, a Light Emitting Diode (LED) has the advantages of high energy efficiency, small size, Light weight, fast response speed, long service life and the like, so that the Light Emitting Diode (LED) is widely applied in many fields.

The current mainstream semiconductor luminescent materials such as gallium nitride have the problems of substrate lattice mismatch, thermal mismatch and the like, so that the service life and the luminous efficiency of the device are influenced. To solve this problem, an aluminum nitride buffer layer is generally grown on the substrate as a transition layer to reduce lattice mismatch and the like.

Meanwhile, the technology of patterning the sapphire substrate is rapidly developed in recent years, and a micro/nano-sized microstructure pattern array is prepared on the sapphire substrate, so that on one hand, the microstructure can enable a semiconductor layer to realize lateral epitaxial growth, the dislocation density of the semiconductor layer is reduced, and the stress generated in the growth process is relaxed; on the other hand, the total internal reflection caused by the difference of the refractive indexes of the materials is reduced through the reflection and diffraction effects of the microstructures on the light generated by the active layer, so that the light extraction efficiency of the LED is improved through various effects.

In the current graphical sapphire substrate, an aluminum nitride buffer layer is grown on a microstructure, on one hand, a semiconductor layer grown on the aluminum nitride buffer layer based on the side wall of the microstructure can generate more threading dislocation, and the lattice quality is influenced; on the other hand, the refractive index difference between gallium nitride (n ≈ 2.38) and aluminum nitride (n ≈ 2.0) is only about 0.38, which is smaller than the refractive index difference between materials such as silicon dioxide, and since the smaller the refractive index difference of the material interface is, the more unfavorable the improvement of the light scattering effect is, the patterned substrate of the current structure is not favorable for further improving the light emitting efficiency of the LED.

Disclosure of Invention

The invention aims to provide a patterned substrate, an LED epitaxial structure and a patterned substrate manufacturing method.

The invention provides a patterned substrate, which comprises a substrate, a buffer layer and a patterned layer; the buffer layer is arranged on the substrate, and the graphical layer is arranged on one side of the buffer layer, which is far away from the substrate; the patterned layer comprises a plurality of microstructures, every two adjacent microstructures are spaced by a gap and exposed out of the buffer layer to form a growth region, and a plurality of sunken secondary microstructures are formed on the surfaces of the microstructures.

As a further improvement of the present invention, the patterned layer is a silicon dioxide layer.

As a further improvement of the invention, the buffer layer is a nitride buffer layer, and the thickness of the buffer layer is in a range of 0.1 nm-1 μm.

As a further improvement of the present invention, a protruding microstructure substrate is further formed at a joint of the buffer layer and the microstructure, the microstructure is disposed on the microstructure substrate, and the thickness of the microstructure substrate is greater than or equal to that of the buffer layer.

As a further improvement of the invention, the shape of the lower end face of the microstructure is consistent with the shape of the upper end face of the microstructure substrate, and the lower end face and the upper end face of the microstructure substrate are in seamless joint to form a smooth outer wall face together.

As a further improvement of the invention, the total thickness of the microstructure and the microstructure substrate ranges from 0.1 to 5 μm, and the outer diameter of the bottom of the microstructure substrate ranges from 1 to 10 μm.

As a further improvement of the invention, the length of the growth region is in the range of 0.1-3 μm.

The invention also provides an LED epitaxial structure which comprises the patterned substrate and a semiconductor layer formed on the patterned substrate, wherein the semiconductor layer grows upwards along the growth region.

The invention also provides a manufacturing method of the patterned substrate, which comprises the following steps:

providing a substrate;

sequentially growing a buffer layer and a patterning layer on the substrate;

manufacturing a photoresist mask layer on the patterning layer, wherein the photoresist mask layer forms a plurality of microstructure mask areas, and each microstructure mask area comprises a plurality of secondary microstructure mask areas;

and etching the photoresist mask layer, the patterning layer and the buffer layer in sequence to form a plurality of microstructures, wherein a plurality of secondary microstructures are formed on the surface of each microstructure.

As a further improvement of the present invention, "sequentially etching the photoresist mask layer, the patterning layer, and the buffer layer to form a plurality of microstructures" comprises:

etching the photoresist layer and the patterned layer under a first gas condition;

etching the buffer layer under the second gas condition.

As a further improvement of the present invention, the first gas condition is a mixed gas of chlorine and boron trichloride in a first preset proportion, and the second gas condition is a mixed gas of chlorine and boron trichloride in a second preset proportion.

The invention has the beneficial effects that: the microstructure with the secondary microstructure formed on the surface is arranged on the buffer layer to obtain the patterned substrate, so that on one hand, the secondary microstructure on the surface of the microstructure can release stress generated in the growth process in advance, multiple reflection can be formed on light generated by the active layer, the scattering effect on the light is enhanced, and the axial light extraction rate is increased; on the other hand, the microstructure is arranged on the buffer layer, so that the lateral growth of the semiconductor layer is reduced, the lattice quality is improved, the refractive index difference between the semiconductor layer and the patterned substrate is improved, and the light emitting efficiency of the LED is improved.

Drawings

FIG. 1 is a schematic view of a patterned substrate in one embodiment of the invention.

Fig. 2 is a schematic diagram of an LED epitaxial structure in an embodiment of the invention.

Fig. 3 is a schematic flow chart of a method for manufacturing a patterned substrate according to an embodiment of the invention.

Fig. 4 is a schematic view of a method for manufacturing a patterned substrate according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be clearly and completely described below with reference to the detailed description of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

For convenience in explanation, the description herein uses terms indicating relative spatial positions, such as "upper," "lower," "rear," "front," and the like, to describe one element or feature's relationship to another element or feature as illustrated in the figures. The term spatially relative position may encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "above" other elements or features would then be oriented "below" or "above" the other elements or features. Thus, the exemplary term "below" can encompass both a spatial orientation of below and above.

As shown in fig. 1, a patterned substrate according to an embodiment of the present invention includes a substrate 1, a buffer layer 2, and a patterned layer 3;

the substrate 1 is a sapphire substrate, a silicon-based substrate, a silicon carbide substrate, a composite substrate of the above substrates, or other common LED substrate materials

The buffer layer 2 is arranged on the substrate 1, and the patterning layer 3 is arranged on one side of the buffer layer 2, which is far away from the substrate 1;

further, the patterned layer 3 includes a plurality of microstructures 31, two adjacent microstructures are separated by a gap to expose the buffer layer to form the growth region 22, and the surface of the microstructures 31 includes a plurality of recessed secondary microstructures 32.

Specifically, in the present embodiment, the secondary microstructure 32 is a plurality of irregular cone-like cavities recessed inwards on the surface of the microstructure 31.

Here, by forming the secondary microstructure 32 such that the microstructure 31 has a roughened surface, on one hand, the microstructure 31 can release stress generated during growth in advance, and thus the film formation quality of a semiconductor layer bottom layer grown on the patterned substrate can be increased and the defect density can be reduced; on the other hand, by forming a rough surface on the surface of the microstructure 31, multiple reflections can be formed on the light generated by the active layer, the scattering effect on the light is enhanced, and the axial light extraction rate is increased.

Of course, the shape of the secondary microstructure 32 is not limited thereto, and in other embodiments, the secondary microstructure 32 may also be a structure that forms a plurality of irregular outward protrusions on the surface of the microstructure 31, or a structure that forms both voids and protrusions, as long as the microstructure 31 can obtain a rough surface.

The patterned layer 3 is a silicon dioxide layer.

The buffer layer 2 is a nitride buffer layer, in this embodiment, an aluminum nitride buffer layer.

The patterned layer 3 of silicon dioxide is placed on the buffer layer 2 so that the microstructures 31 can be brought into direct contact with the semiconductor layer grown on the patterned substrate without growing the buffer layer 2 on the microstructures 31 and then growing the semiconductor layer so that it grows mainly up the growth zone 22.

Here, on the one hand, since the growth of the semiconductor layer on the silicon dioxide belongs to heterogeneous nucleation, the semiconductor layer is more prone to grow on the basis of the buffer layer 2 and not on the basis of the microstructure 31, so that the lateral growth of the semiconductor layer directly along the side wall of the microstructure 31 is reduced, the threading dislocation is reduced, the lattice quality is improved, the quantum efficiency in the LED can be improved, and the light emitting efficiency is improved.

On the other hand, the refractive index of silicon dioxide is about 1.54, the refractive index of aluminum nitride is about 2.0, and the refractive index of gallium nitride, which is the most predominant semiconductor layer material at present, is about 2.38, which is larger than the refractive index difference between silicon dioxide, i.e., the refractive index difference between the semiconductor layer and the microstructure 31 is larger than the refractive index difference between the semiconductor layer and the buffer layer 2. The larger the difference of the refractive indexes between the heterogeneous materials is, the higher the reflectivity at the interface of the heterogeneous materials is, so that the improvement of the light emitting efficiency of the LED is facilitated.

Further, the buffer layer 2 has a thickness ranging from 0.1nm to 1 μm, a raised microstructure substrate 21 is further formed at a joint with the microstructure 31, the microstructure 31 is disposed on the microstructure substrate 21, and the thickness of the microstructure substrate 21 is greater than or equal to that of the buffer layer 2.

Here, by arranging the microstructure substrate 21 on the buffer layer 2, the buffer layer 2 can be sputtered to a thick thickness in the preparation process to obtain the micron-sized buffer layer 2, so that when the buffer layer 2 is etched, the region of the buffer layer 2 between the microstructures 31 can be over-etched, and the interval region between the microstructures 31 is ensured to provide a growth nucleation region for the subsequent semiconductor layer for the buffer layer 2, so as to avoid the situation that the etching depth is not enough and the patterning layer 3 is left. The microstructure substrate 21 reduces the requirement on the precision of the production process under the condition of improving the yield of products, and is beneficial to industrial production and application.

Furthermore, the shape of the lower end face of the microstructure 31 is consistent with the shape of the upper end face of the microstructure substrate 21, and the two are seamlessly attached to form a smooth outer wall face together, so that the growth quality of the semiconductor layer is further improved.

The microstructures 31 and the microstructure substrate 21 together form a pyramid-like, frustum-like, or cylinder-like structure.

Specifically, in the present embodiment, the microstructure 31 and the microstructure substrate 21 together form a cone, the total thickness of the microstructure 31 and the microstructure substrate 21 ranges from 0.1 μm to 5 μm, and the outer diameter of the bottom of the microstructure substrate 21 ranges from 1 μm to 10 μm. The length range of the growth region 22 is 0.1-3 μm. By setting the sizes and the intervals of the microstructures 31 and the microstructure substrate 21, the reflection and scattering effects of the microstructures on light can be ensured, so that the light emitting efficiency of the LED device is improved, and the light emitting efficiency of the LED is increased.

The invention also provides an LED epitaxial structure, which comprises the patterned substrate and a semiconductor layer 4 formed on the patterned substrate, wherein the semiconductor layer 4 grows upwards along the growth region 22.

As shown in fig. 2 and 3, the present invention also provides a method for manufacturing a patterned substrate, comprising the steps of:

s1: a substrate 1 is provided.

In the embodiment, a sapphire substrate 1 is selected, ultrasonic cleaning or plasma cleaning is performed on the substrate 1, and after drying, the substrate is placed in a reaction chamber of metal organic chemical vapor deposition equipment.

S2: a buffer layer 2 and a patterned layer 3 are grown in sequence on the substrate 1.

In this embodiment, the buffer layer 2 is an aluminum nitride layer, and the patterned layer 3 is a silicon dioxide layer.

And keeping a certain temperature in the reaction chamber, introducing argon, nitrogen and oxygen, keeping stable pulse power supply power, and uniformly sputtering the buffer layer 2 on the substrate.

And uniformly sputtering the patterning layer 3 on the buffer layer 2 by using a plasma enhanced chemical vapor deposition or spin coating method.

S3: manufacturing a photoresist mask layer 5 on the patterning layer 3, wherein the photoresist mask layer 5 forms a plurality of microstructure mask regions 51, and each microstructure mask region 51 comprises a plurality of secondary microstructure mask regions 52;

specifically, the photoresist mask layer 5 with a periodically distributed thickness is manufactured on the patterning layer 3 through photoresist coating, reticle mask exposure and organic development. In this embodiment, the thickness of the secondary microstructure mask region 52 is smaller than that of the microstructure mask region 51, and in other embodiments, the thickness of the secondary microstructure mask region 52 may be higher than that of the microstructure mask region 51, as long as the difference in thickness is achieved.

S4: and etching the photoresist mask layer 5, the patterning layer 3 and the nitride buffer layer 2 in sequence to form a plurality of microstructures 31, wherein a plurality of secondary microstructures 32 are formed on the surface of each microstructure 31.

As a result of the different etching depths resulting from the provision of the secondary microstructured mask regions 52 of different thicknesses on the microstructured mask region 51, the secondary microstructures 32 are formed on the outer surface of the microstructures 31 formed when the patterned layer 3 is etched.

Further, the photoresist mask layer 5 and the patterning layer 3 are etched under the first gas condition. The buffer layer 2 is etched under the second gas condition. The buffer layer 2 is etched to ensure that the regions between the microstructures 31 are the buffer layer 2 and to avoid the patterned layer 3 remaining. In addition, the buffer layer 2 is over-etched, so that the microstructure substrate 21 is formed on the buffer layer 2.

Specifically, in this embodiment, the first gas condition is a mixed gas of chlorine and boron trichloride in a first preset ratio, and the second gas condition is a mixed gas of chlorine and boron trichloride in a second preset ratio.

In summary, the microstructure with the secondary microstructure formed on the surface is arranged on the buffer layer to obtain the patterned substrate, so that on one hand, the secondary microstructure on the surface of the microstructure can release stress generated in the growth process in advance, can reflect light generated by the active layer for multiple times, enhances the scattering effect on the light and increases the axial light extraction rate; on the other hand, the microstructure is arranged on the buffer layer, so that the lateral growth of the semiconductor layer is reduced, the lattice quality is improved, the refractive index difference between the semiconductor layer and the patterned substrate is improved, and the light emitting efficiency of the LED is improved.

It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention and is not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention are included in the scope of the present invention.