CN105355739A - Patterned substrate, preparation method and light-emitting diode - Google Patents

Abstract

The invention proposes a patterned substrate, a preparation method and a light-emitting diode. By depositing a dielectric layer on the surface of a substrate with a plurality of protrusions, the amorphous characteristics of the dielectric layer are used to make PVD deposition on the sides and sides of the protrusions. The aluminum nitride layer of the top platform is amorphous, while the aluminum nitride covering the flat surface of the raised gap is polycrystalline composed of tiny grains. When the substrate is then applied to deposit gallium nitride-based epitaxial layers by MOCVD to form light-emitting diodes, it is easier to grow using the polycrystalline aluminum nitride on a flat surface, while amorphous aluminum nitride is not easy to deposit gallium nitride-based epitaxial layers. The epitaxial layer is selectively grown on the flat surface aluminum nitride layer of the raised gap, while the raised side and top platform are not easy to grow, which reduces the growth of the side GaN-based epitaxial layer and reduces the nitride growth of the lateral growth. The number of defects when the gallium-based epitaxial layer is combined with the forward-grown gallium nitride-based epitaxial layer on the flat surface improves the performance of the final semiconductor element. At the same time, since the growth of the lateral GaN-based epitaxial layer is suppressed, the forwardly grown GaN-based epitaxial layer is easier to merge into a flat surface.

Description

Patterned substrate, preparation method and light emitting diode

technical field

The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a patterned substrate for reducing crystal defects, a preparation method and a light-emitting diode.

Background technique

Now mainstream LEDs use patterned substrates for epitaxial growth. On the one hand, the pattern on the surface provides a variety of growth crystal phase options for the growth of the GaN epitaxial layer in the later stage, so that the GaN epitaxial layer is changed from the traditional two-dimensional The growth becomes three-dimensional growth, thereby effectively reducing the dislocation density in GaN-based LED materials, avoiding the generation of cracks, and improving the internal quantum luminous efficiency of LEDs; on the other hand, because the array pattern structure increases light scattering, The optical circuit of the LED is changed to form diffuse reflection, thereby improving the light extraction efficiency. However, due to the large lattice mismatch between the widely used sapphire substrate and the gallium nitride-based material layer, nucleation and growth are difficult, and in order to overcome the problem of difficult nucleation, it was proposed to heat the substrate at about 1000 °C Finally, grow a low-quality low-temperature buffer layer, and then turn to high-temperature conditions to grow a high-quality GaN-based epitaxial layer. Due to the high and low temperature conversion in this process, the use efficiency of MOCVD equipment is reduced; at the same time, the large temperature difference between different layers leads to the increase of stress between different layers, thus affecting the crystal performance.

Therefore, it has been proposed to deposit a layer of aluminum nitride on the surface of the patterned substrate to reduce the lattice difference between the substrate and the GaN-based epitaxial layer. The current common process is to place the patterned substrate on PVD The aluminum nitride layer is deposited on the surface of the substrate, and because the commonly used sapphire substrate has a small lattice mismatch with the aluminum nitride layer, the aluminum nitride layer not only covers the raised gap surface of the patterned substrate , while also covering the raised side and top platform, when the substrate is placed in a chemical vapor deposition chamber to grow a gallium nitride-based buffer layer, an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer When forming a semiconductor element, serious epitaxial layers compete to grow on the side of the protrusion and the surface of the gap, resulting in uneven surface of the buffer layer and increased dislocation defects; and dislocation lines will extend to the light-emitting region along the crystal growth direction, affecting device performance.

Contents of the invention

In view of the above problems, the present invention proposes a patterned substrate, a preparation method, and a light-emitting diode. By depositing a dielectric layer on the surface of a substrate with a plurality of uniformly distributed protrusions, the amorphous characteristics of the dielectric layer are used to make the PVD method The aluminum nitride layer deposited on the surface of the protrusion is amorphous, while the aluminum nitride layer covering the gap surface of the adjacent protrusion is in the polycrystalline state composed of tiny crystal grains. When the substrate is then applied to deposit epitaxial layers by MOCVD to form light-emitting diodes, it is easier to grow gallium nitride-based epitaxial layers by using polycrystalline aluminum nitride layers on the surface of the raised gaps, while amorphous aluminum nitride layers are not easy to grow. characteristics, so that the epitaxial layer is selectively grown on the surface of the aluminum nitride layer on the surface of the raised gap, while the raised surface is difficult to grow, reducing the growth probability of the gallium nitride-based epitaxial layer on the side of the substrate pattern, and reducing the lateral growth of the gallium nitride-based The lattice defect density when the epitaxial layer is combined with the flat surface of the forward-grown GaN-based epitaxial layer improves the performance of the final semiconductor device; at the same time, due to the suppression of the growth of the lateral GaN-based The grown GaN-based epitaxial layer is easier to merge into a flat surface, improving the crystal quality of the epitaxial layer.

The technical solution provided by the present invention is: a patterned substrate having opposite first and second surfaces, wherein a plurality of protrusions are uniformly distributed on the first surface, and there are gaps between the protrusions, wherein the A dielectric layer is deposited on the surface of the protrusion, and the surface of the protrusion gap does not have the dielectric layer; an aluminum nitride layer is deposited on the surface of the dielectric layer and the surface of the protrusion gap, and the nitride of the surface of the dielectric layer is The aluminum layer inhibits lateral epitaxial growth of the patterned substrate surface.

Preferably, the aluminum nitride layer on the surface of the raised gap is easier to grow GaN-based material than the aluminum nitride layer on the surface of the dielectric layer.

Preferably, the aluminum nitride layer on the surface of the protrusion is an amorphous layer, and the aluminum nitride layer on the surface of the gap between the protrusions is a polycrystalline layer composed of tiny crystal grains.

Preferably, the distance between adjacent protrusions is 50nm-5000nm.

Preferably, the dielectric layer has a thickness of 1 nm to 200 nm.

Preferably, the thickness of the aluminum nitride layer is 1 nm to 200 nm.

At the same time, the present invention proposes a method for preparing a patterned substrate, comprising the following steps:

S1. Provide a substrate with a flat surface, prepare a plurality of uniformly distributed protrusions on the flat surface, and have gaps between each protrusion;

S2. Forming a dielectric layer on the surface of the substrate treated above, which only covers the raised surface and does not cover the surface of the raised gap;

S3. Deposit an aluminum nitride layer on the surface of the dielectric layer and the surface of the raised gap to form a patterned substrate, and the aluminum nitride layer on the surface of the dielectric layer inhibits the lateral direction of the surface of the patterned substrate Epitaxial growth, reducing crystal defects when the epitaxial layer is growing forward and merging.

And the step S2 is formed by the following method:

forming a dielectric layer on the surface of the substrate processed in step S1, which covers the raised surface and the raised gap surface;

Coating photoresist on the surface of the dielectric layer, removing the photoresist and the dielectric layer on the surface of the raised gap by using an etching technique, and retaining the photoresist and the dielectric layer on the raised surface;

The photoresist on the raised surface is removed to form a substrate with a dielectric layer on the raised surface and no dielectric layer on the raised gap surface.

Preferably, the dielectric layer has a thickness of 1 nm to 200 nm.

Preferably, the thickness of the aluminum nitride layer is 1 nm to 200 nm.

In addition, the light-emitting diode provided by the present invention includes a patterned substrate and a light-emitting epitaxial stack formed on the patterned substrate, and the patterned substrate has a first surface and a second surface opposite to each other, wherein the first There are a plurality of protrusions evenly distributed on the surface, there are gaps between the protrusions, the surface of the protrusions is deposited with a dielectric layer, and the surface of the gap between the protrusions does not have the dielectric layer; the surface of the dielectric layer and the An aluminum nitride layer is deposited on the surface of the raised gap, and the aluminum nitride layer on the surface of the dielectric layer inhibits lateral epitaxial growth on the surface of the patterned substrate.

Preferably, the aluminum nitride layer on the surface of the protrusion is an amorphous layer, and the aluminum nitride layer on the surface of the gap between the protrusions is a polycrystalline layer composed of tiny crystal grains.

Preferably, the light-emitting epitaxial stack is selectively grown on the aluminum nitride layer on the surface of the raised gap.

The present invention has at least the following beneficial effects:

The present invention deposits a dielectric layer on the convex surface of the patterned substrate without depositing a dielectric layer on the surface of the convex gap. Due to the amorphous characteristics of the dielectric layer, the aluminum nitride layer deposited on the convex surface by PVD method is non-crystalline. crystalline state, while the aluminum nitride layer covering the surface of the raised gap non-dielectric layer is polycrystalline state composed of tiny crystal grains. When the substrate is subsequently applied to deposit epitaxial layers by MOCVD, it is easier to grow gallium nitride-based epitaxial layers by using the polycrystalline aluminum nitride layer on the surface of the raised gap, while the amorphous aluminum nitride layer on the raised surface is not easy to grow. The characteristics make the epitaxial layer selectively grow on the surface of the aluminum nitride layer on the surface of the raised gap, and the raised surface is not easy to grow the epitaxial layer, which reduces the growth probability of the side GaN-based epitaxial layer and reduces the lateral growth of the GaN-based layer. The lattice defect density when the epitaxial layer is merged with the GaN-based epitaxial layer grown on the flat surface, improves the performance of the final semiconductor device; at the same time, due to the suppression of the lateral GaN-based epitaxial layer growth, the forward The grown GaN-based epitaxial layer is more easily merged into a flat surface, improving the crystal quality of the epitaxial layer.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In addition, the drawing data are descriptive summaries and are not drawn to scale.

FIG. 1 is a schematic diagram of the structure of a patterned substrate according to Embodiment 1 of the present invention.

FIG. 2a is a schematic diagram of a substrate with a flat surface according to Embodiment 1 of the present invention.

FIG. 2b is a schematic diagram of a patterned substrate with a plurality of protrusions according to Embodiment 1 of the present invention.

FIG. 3 is a schematic diagram of the substrate structure after depositing a dielectric layer according to Embodiment 1 of the present invention.

FIG. 4a is a schematic diagram of the substrate structure after coating photoresist according to Embodiment 1 of the present invention.

Fig. 4b is a schematic diagram of the structure of the substrate after removing the dielectric layer on the raised gap surface according to Embodiment 1 of the present invention.

FIG. 5 is a schematic diagram of the structure of the substrate after removing the mask layer according to Embodiment 1 of the present invention.

FIG. 6 is a schematic diagram of the substrate structure after depositing an aluminum nitride layer according to Embodiment 1 of the present invention.

FIG. 7 is a schematic diagram of the epitaxial structure of Embodiment 1 of the present invention.

FIG. 8 is a schematic diagram of a patterned substrate according to Embodiment 2 of the present invention.

FIG. 9 is a schematic diagram of the structure of the substrate after depositing an aluminum nitride layer according to Embodiment 2 of the present invention.

In the figure: 10'. Flat substrate; 10. Patterned substrate; 11. Raised; 111. Raised gap surface; 112. Raised side; 113. Raised top platform; 20. Dielectric layer; 21. Raised gap surface dielectric layer; 22. Raised side dielectric layer; 23. Raised top platform dielectric layer; 30. Photoresist; 31. Raised gap surface photoresist; 32. Raised side photoresist; 40. Nitriding Aluminum layer; 41. Aluminum nitride layer on the surface of the protrusion gap; 42. Aluminum nitride layer on the side of the protrusion; 43. Aluminum nitride layer on the top platform of the protrusion; 50. Buffer layer; 60. N-type semiconductor layer; 70. Light emitting layer; 80. P-type semiconductor layer.

detailed description

The specific implementation manner of the present invention will be described in detail below with reference to the drawings and embodiments.

Example 1

Referring to accompanying drawing 1, the patterned substrate 10 that the present invention provides, described patterned substrate 10 has opposite first surface and second surface, wherein first surface is evenly distributed with plural protrusions 11 on its surface, so The distance between adjacent protrusions 11 is 50nm-5000nm, and there is no platform structure at the top of the protrusions 11, preferably a triangular pyramid structure. The side surface 112 of the protrusion 11 is deposited with a dielectric layer 22 with a thickness of 1 nm to 200 nm, while the gap surface 111 of the protrusion has no dielectric layer, and the dielectric layer 22 is any one of a silicon dioxide layer or a silicon nitride layer. The surface of the substrate with the dielectric layer 22 is deposited with an aluminum nitride layer 40 with a thickness of 1 nm to 200 nm. The aluminum nitride layer 40 covers the surface of the dielectric layer 22 of the protrusion 11 and the gap surface 111 of the adjacent protrusion, respectively forming a protrusion The aluminum nitride layer 41 on the surface of the gap and the aluminum nitride layer 42 on the side of the protrusion; because the dielectric layer 22 is amorphous, the aluminum nitride layer 42 deposited on its surface is also amorphous; and the adjacent protrusion gap There is no dielectric layer at the surface 111, which is a crystalline surface, and the aluminum nitride layer 41 deposited on the convex gap surface is polycrystalline composed of tiny crystal grains; compared with the amorphous convex side surface of the dielectric layer 22 surface The aluminum nitride layer 42 and the polycrystalline aluminum nitride layer 41 are more likely to grow subsequent gallium nitride-based epitaxial layers; thus the amorphous state on the surface of the dielectric layer 22 inhibits the lateral epitaxial growth on the surface of the patterned substrate 10, reducing the The crystal defect density when the epitaxial layer grows forward and merges, and improves the crystal quality of the epitaxial layer.

In order to realize the effect of the above-mentioned patterned substrate, the present invention proposes a method for preparing a patterned substrate, the steps of which are as follows:

S1. Provide a substrate 10' with a flat surface (as shown in FIG. 2a), and prepare a plurality of uniformly distributed protrusions 11 on the surface of the flat substrate 10' (as shown in FIG. 2b); the substrate 10' is selected from any one of sapphire substrates, silicon substrates, and silicon carbide substrates;

S2. As shown in FIG. 3 , deposit a dielectric layer 20 on the raised side surface 111, and the dielectric layer 20 covers the raised side surface 112 and the gap surface 111 between the adjacent bumps 11, forming a gap surface located on the raised gap surface. The dielectric layer 21 of 112, and the dielectric layer 22 located on the surface of the convex side 112; the thickness of the dielectric layer 20 is 1nm~200nm; subsequently, the photoresist 30 is coated on the surface of the dielectric layer 20 (as shown in Figure 4a) , using photolithography and etching techniques to remove the photoresist 31 and the dielectric layer 21 on the raised gap surface 111, and retain the photoresist 32 and the dielectric layer 22 on the raised side 112 (as shown in Figure 4b); cleaning and removal The photoresist 32 on the raised side surface 111 finally forms a substrate with a dielectric layer 22 on the raised surface and no dielectric layer on the raised gap surface 111 (as shown in FIG. 5 );

S3. As shown in FIG. 6, deposit an aluminum nitride layer 40 on the substrate surface with a dielectric layer 22 by physical vapor deposition to form a patterned surface consisting of bumps 11, a dielectric layer 22 and an aluminum nitride layer 40 The substrate 10; and the aluminum nitride layer 42 on the surface of the dielectric layer 22 inhibits the lateral epitaxial growth on the surface of the patterned substrate 10, and reduces crystal defects when the epitaxial layers grow forward and merge.

Referring to FIG. 7 , a gallium nitride-based light-emitting epitaxial stack is grown on the patterned substrate 10 to form a light-emitting diode structure. Specifically, a patterned substrate 10 is provided, which has opposite first and second surfaces, wherein a plurality of protrusions 11 are evenly distributed on the first surface, and a dielectric layer 22 is deposited on the surface of the protrusions 11, and the dielectric layer The surface 22 and the raised interstitial surface 111 are deposited with an aluminum nitride layer 40. When this substrate 10 is applied to epitaxial growth, it is easier to grow a gallium nitride-based epitaxial layer by using the polycrystalline aluminum nitride layer 41 on the surface of the non-dielectric layer adjacent to the raised gap surface 111, while the non-dielectric layer on the raised side surface 112 The characteristic that the crystalline aluminum nitride layer 42 is not easy to grow makes the gallium nitride-based epitaxial layer grow selectively on the surface of the polycrystalline aluminum nitride layer 41; and the convex side 112 is not easy to grow, which reduces the growth of the side gallium nitride-based epitaxial layer. layer growth probability, reduce the lattice defect density when the laterally grown GaN-based epitaxial layer is merged with the GaN-based epitaxial layer grown forwardly on the raised gap surface 111, and improve the performance of the final semiconductor element; at the same time, due to The growth of the lateral gallium nitride-based epitaxial layer is suppressed, so that the forward-growing gallium nitride-based epitaxial layer is more easily merged into a flat surface, and then the first semiconductor layer 60, the light-emitting layer 70 and the second semiconductor layer 60 are deposited on the flat surface. The semiconductor layer 80 yields a semiconductor element with excellent crystal quality.

Example 2

Referring to accompanying drawings 8 and 9, the difference between this embodiment and Embodiment 1 is that the protrusion of the patterned substrate 10 in this embodiment also has a top surface platform 113 structure, and the protrusion 11 is a circular frustum structure or an elliptical frustum structure. , one of the prism structures; the dielectric layer 20 is not only deposited on the raised side surface 112, but also deposited on the raised top surface platform 113, and the aluminum nitride layer 40 in the subsequent process is also deposited on the raised gap surface in turn 111, the surface of the dielectric layer 22 at the raised side 112 and the dielectric layer 23 at the raised platform 113; using the amorphous properties of the aluminum nitride layer 42 on the surface of the dielectric layer 22 and the aluminum nitride layer 43 on the surface of the top platform dielectric layer 23 And the crystalline properties of the aluminum nitride layer 41 on the raised gap surface 112 can suppress the competing growth phenomenon of the epitaxial layer on the pattern side and the gap surface, thereby improving the crystal quality of the semiconductor element.

It should be understood that the above specific implementation is a preferred embodiment of the present invention, the scope of the present invention is not limited to this embodiment, and any changes made according to the present invention are within the protection scope of the present invention.

Claims (13)

1. A patterned substrate, having opposite first surface and second surface, wherein the first surface is evenly distributed with a plurality of protrusions, there is a gap between each of the protrusions, it is characterized in that: the protrusion surface is deposited There is a dielectric layer, and the surface of the raised gap is free of the dielectric layer; the surface of the dielectric layer and the surface of the raised gap are deposited with an aluminum nitride layer, and the aluminum nitride layer on the surface of the dielectric layer suppresses the pattern Lateral epitaxial growth on the substrate surface. 2 . The patterned substrate according to claim 1 , wherein the aluminum nitride layer on the surface of the raised gap is easier to grow GaN-based material than the aluminum nitride layer on the surface of the dielectric layer. 3. The patterned substrate according to claim 2, characterized in that: the aluminum nitride layer on the raised surface is an amorphous layer, and the aluminum nitride layer on the raised gap surface is made of tiny A polycrystalline layer composed of crystal grains. 4. The patterned substrate according to claim 1, wherein the distance between the adjacent protrusions is 50nm-5000nm. 5 . The patterned substrate according to claim 1 , wherein the dielectric layer has a thickness of 1 nm to 200 nm. 6 . The patterned substrate according to claim 1 , wherein the thickness of the aluminum nitride layer is 1 nm to 200 nm. 7. A method for preparing a patterned substrate, comprising the steps of: S1. Provide a substrate with a flat surface, prepare a plurality of uniformly distributed protrusions on the flat surface, and have gaps between each protrusion; S2. Forming a dielectric layer on the surface of the substrate treated above, which only covers the raised surface and does not cover the surface of the raised gap; S3. Deposit an aluminum nitride layer on the surface of the dielectric layer and the surface of the raised gap to form a patterned substrate, and the aluminum nitride layer on the surface of the dielectric layer inhibits the lateral direction of the surface of the patterned substrate Epitaxial growth, reducing crystal defects when the epitaxial layer is growing forward and merging. 8. The method for preparing a patterned substrate according to claim 7, characterized in that: said step S2 is formed by the following method: forming a dielectric layer on the surface of the substrate processed in step S1, which covers the raised surface and the raised gap surface; Coating photoresist on the surface of the dielectric layer, removing the photoresist and the dielectric layer on the surface of the raised gap by using an etching technique, and retaining the photoresist and the dielectric layer on the raised surface; The photoresist on the raised surface is removed to form a substrate with a dielectric layer on the raised surface and no dielectric layer on the raised gap surface. 9 . The method for preparing a patterned substrate for reducing crystal defects according to claim 7 , wherein the dielectric layer has a thickness of 1 nm to 200 nm. 10 . The patterned substrate for reducing crystal defects according to claim 7 , wherein the thickness of the aluminum nitride layer is 1 nm to 200 nm. 11 . 11. A light-emitting diode, comprising a patterned substrate and a light-emitting epitaxial stack formed on the patterned substrate, the patterned substrate having opposite first and second surfaces, wherein the first surface is evenly distributed with A plurality of protrusions, there is a gap between each of the protrusions, a dielectric layer is deposited on the surface of the protrusion, and the surface of the gap between the protrusions does not have the dielectric layer; the surface of the dielectric layer and the gap between the protrusions An aluminum nitride layer is deposited on the surface, and the aluminum nitride layer on the surface of the dielectric layer inhibits lateral epitaxial growth on the surface of the patterned substrate. 12. The light-emitting diode according to claim 11, characterized in that: the aluminum nitride layer on the surface of the protrusion is an amorphous layer, and the aluminum nitride layer on the surface of the gap between the protrusions is composed of tiny crystal grains composed of polycrystalline layers. 13. The light emitting diode according to claim 11, wherein the light emitting epitaxial stack is selectively grown on the aluminum nitride layer on the surface of the raised gap.