Substrate structure, method of forming the substrate structure and chip comprising the substrate structure
A groove structure formed on a surface of a substrate. The groove structure includes a lateral epitaxial pattern in a cross section perpendicular to the surface, which has: a first edge inclined to the surface; a second edge adjacent to first edge and parallel to the surface; a third edge parallel to the first edge, having a projection on the surface covering the second edge; and a fourth edge adjacent to the third edge. A first intersection between the second edge and the third edge on the second edge and an injection of a second intersection between the third edge and the fourth edge on the second edge are located on two sides of a third intersection between the first edge and the second edge, or the injection of the second intersection between the third edge and the fourth edge on the second edge coincides with the third intersection.
1. A substrate structure, comprising:
a substrate; and
at least a groove structure formed on a surface of the substrate, the groove structure having a lateral epitaxial pattern in a cross section perpendicular to the surface of the substrate,
wherein the lateral epitaxial pattern comprises:
a first edge inclined with respect to the surface of the substrate;
a second edge adjacent to the first edge and parallel to the surface of the substrate;
a third edge parallel to the first edge, having a projection on the surface of the substrate at least entirely covering the second edge; and
a fourth edge adjacent to the third edge,
in which the second edge is the bottom of the groove structure; and a first intersection point between the second edge and the third edge on the second edge and an injection of a second intersection point between the third edge and the fourth edge on the second edge are located on two sides of a third intersection point between the first edge and the second edge, or the injection of the second intersection point between the third edge and the fourth edge on the second edge coincides with the third intersection point between the first edge and the second edge.
2. The substrate structure according to claim 1 , wherein the fourth edge is perpendicular to the second edge.
3. The substrate structure according to claim 1 , wherein at least two groove structures are formed on the substrate, and a first free point on the fourth edge of a former groove structure connects with a second free point on the first edge of a later groove structure.
4. The substrate structure according to claim 1 , wherein an angle between the first edge and the second edge ranges from about 30° to about 60°.
5. The substrate structure according to claim 1 , wherein a length of the second edge ranges from about 0.01 μm to about 2.00 μm.
6. The substrate structure according to claim 3 , wherein a distance between the first free point on the first edge of the groove structure and the second free point on the fourth edge of the groove structure ranges from 0.6 μm to about 3.00 μm.
7. The substrate structure according to claim 1 , wherein the substrate is a sapphire substrate.
8. A method of forming a substrate structure, comprising the steps of:
1) providing a substrate;
2) forming a first photoresist layer on a surface of the substrate;
3) exposing and developing the first photoresist layer by a first mask, and an angle between the surface of the substrate and a direction of incident lights in the exposing step being an acute angle;
4) firstly dry etching the substrate to form at least a first groove, in which a direction of the first dry etching is the same as the direction of the incident lights in the exposing step in the step 3);
5) forming a second photoresist layer covering the surface formed with the first groove;
6) exposing and developing the second photoresist layer by a second mask, and forming the second photoresist layer above the first groove; and
7) secondly dry etching the substrate to form at least a groove structure, the groove structure having a lateral epitaxial pattern in a cross section perpendicular to the surface of the substrate, and a direction of the second dry etching in the step 7) being the same as a direction of incident lights in the exposing step in the step 6),
wherein the lateral epitaxial pattern comprises:
a first edge inclined with respect to the surface of the substrate;
a second edge adjacent to the first edge and parallel to the surface of the substrate;
a third edge parallel to the first edge, having a projection on the surface of the substrate at least entirely covering the second edge; and
a fourth edge adjacent to the third edge,
in which the second edge is the bottom of the groove structure; and a first intersection point between the second edge and the third edge on the second edge and an injection of a second intersection point between the third edge and the fourth edge on the second edge are located on two sides of a third intersection point between the first edge and the second edge, or the injection of the second intersection point between the third edge and the fourth edge on the second edge coincides with the third intersection point between the first edge and the second edge.
9. The method according to claim 8 , wherein the direction of the incident lights is perpendicular to the surface of the substrate in the step 6).
10. The method according to claim 8 , wherein the step 4) further comprises:
cleaning the substrate to remove the extra first photoresist layer after the first dry etching.
11. The method according to claim 8 , wherein the step 7) further comprises:
cleaning the substrate to remove the extra second photoresist layer after the second dry etching.
12. The method according to claim 8 , wherein the first mask and the second mask each comprises:
a base plate;
at least a strip hole formed in the base plate.
13. The method according to claim 12 , wherein the fourth edge is perpendicular to the second edge.
14. The method according to claim 12 , wherein an angle between the direction of the incident lights and the surface of the substrate ranges from about 30° to about 60°.
15. A chip, comprising:
a substrate structure comprising:
a substrate; and
at least a groove structure formed on a surface of the substrate, the groove structure having a lateral epitaxial pattern in a cross section perpendicular to the surface of the substrate,
wherein the lateral epitaxial pattern comprises:
a first edge inclined with respect to the surface of the substrate;
a second edge adjacent to the first edge and parallel to the surface of the substrate;
a third edge parallel to the first edge, having a projection on the surface of the substrate at least entirely covering the second edge; and
a fourth edge adjacent to the third edge,
in which the second edge is the bottom of the groove structure; and a first intersection point between the second edge and the third edge on the second edge and an injection of a second intersection point between the third edge and the fourth edge on the second edge are located on two sides of a third intersection point between the first edge and the second edge, or the injection of the second intersection point between the third edge and the fourth edge on the second edge coincides with the third intersection point between the first edge and the second edge; and
an LED structure formed on the substrate structure.
16. The chip according to claim 15 , wherein the LED structure comprises:
an N-type GaN layer formed on the substrate structure;
a multiple quantum well luminous layer formed on the N-type GaN layer;
a P-type GaN layer formed on the multiple quantum well luminous layer;
a conductive layer formed on the P-type GaN layer;
a metal P-electrode connected with the conductive layer; and
a metal N-electrode connected with the N-type GaN layer.
17. The chip according to claim 16 , further comprising:
a GaN nucleation layer and an intrinsic GaN layer formed between the substrate structure and the N-type GaN layer.
18. The chip according to claim 17 , further comprising:
a AlGaN electron barrier layer formed between the multiple quantum well luminous layer and the P-type GaN layer.
19. The chip according to claim 17 , wherein the P-type GaN layer comprises a Mg-doped P-type GaN layer formed on the multiple quantum well luminous layer.