LED structure, LED device and methods for forming the same

1. An LED structure, comprising:

an LED wafer;

a transparent accommodating layer directly formed on a light emitting surface of the LED wafer, wherein the transparent accommodating layer is conductive and has a recess; and

a phosphor layer having a flat surface and formed in recess of the transparent accommodating layer, wherein the phosphor layer is formed by centrifugal spin coating.

2. The LED structure according to claim 1 , further comprising:

a protective layer formed above the phosphor layer, wherein the protective layer is a silicon dioxide layer or a transparent metal oxide layer.

3. The LED structure according to claim 1 , wherein the transparent accommodating layer comprises:

a bottom; and

a side wall surrounding the bottom,

in which the side wall and the bottom define the recess.

4. The LED structure according to claim 3 , wherein a middle portion of the bottom of the transparent accommodating layer is convex, the bottom of the transparent accommodating layer comprises a first bottom portion, a second bottom portion, and a middle bottom portion between the first and second bottom portions, in which a depth of the first bottom portion to a top surface of the recess equals to that of the second bottom portion to the top surface of the recess, and the depth of the first bottom portion to the top surface of the recess is no less than that of the middle bottom portion to the top surface of the recess.

5. A method for forming an LED structure, comprising steps of:

providing an LED wafer;

forming a transparent accommodating layer having a recess directly on the light emitting surface of the LED wafer, wherein the transparent accommodating layer is conductive;

forming a mixture of a fluorescent substance and an adhesive in the recess by centrifugal spin coating; and

curing the mixture of the fluorescent substance and the adhesive to form a phosphor layer having a flat surface.

6. The method according to claim 5 , further comprising:

forming a protective layer above the phosphor layer, wherein the protective layer is a silicon dioxide layer or a transparent metal oxide layer.

7. The method according to claim 5 , further comprising:

removing extra mixture of the fluorescent substance and the adhesive flowing outside the recess with an adhesive film.

8. The method according to claim 5 , wherein the transparent accommodating layer comprises:

a bottom; and

a side wall surrounding the bottom,

in which the side wall and the bottom define the recess.

9. The method according to claim 8 , wherein the step of forming the transparent accommodating layer comprises:

forming a transparent material layer on the light emitting surface of the LED wafer; and

etching the transparent material layer to form the recess.

10. The method according to claim 8 , wherein a middle portion of the bottom of the transparent material layer is convex.

11. The method according to claim 10 , wherein the bottom of the transparent accommodating layer comprises a first bottom portion, a second bottom portion, and a middle bottom portion between the first and second bottom portions, in which a depth of the first bottom portion to a top surface of the recess equals to that of the second bottom portion to the top surface of the recess, and the depth of the first bottom portion to the top surface of the recess is no less than that of the middle bottom portion to the top surface of the recess.

12. The method according to claim 5 , wherein the centrifugal spin coating is performed with a spin coater.

13. An LED device, comprising:

a substrate;

an LED epitaxial layer comprising a first semiconductor layer, an active layer and a second semiconductor layer formed sequentially on the substrate;

a first electrode electrically connected to the first semiconductor layer;

a second electrode electrically connected to the second semiconductor layer;

a transparent accommodating layer directly formed on the LED epitaxial layer, wherein the transparent accommodating layer is conductive and has a recess; and

a phosphor layer having a flat surface formed in the recess, wherein the phosphor layer is formed by centrifugal spin coating.

14. The LED device according to claim 13 , wherein the transparent accommodating layer comprises:

a bottom; and

a side wall surrounding the bottom, in which the side wall and the bottom define the recess.

15. The LED device according to claim 14 , wherein the bottom of the transparent accommodating layer comprises a first bottom portion, a second bottom portion, and a middle bottom portion between the first and second bottom portions, in which a depth of the first bottom portion to a top surface of the recess equals to that of the second bottom portion to the top surface of the recess, and the depth of the first bottom portion to the top surface of the recess is no less than that of the middle bottom portion to the top surface of the recess.

16. The LED device according to claim 13 , wherein the LED device is a horizontal face-up LED device, a horizontal flip LED device, a vertical face-up LED device, or a vertical flip LED device.

17. A method for forming an LED device, comprising steps of:

providing an LED wafer;

forming a phosphor layer having a flat surface above a light emitting surface of the LED wafer by a method according to claim 8 ;

photoetching a surface of the LED wafer to expose an electrode area;

depositing an electrode in the electrode area; and

disparting the LED wafer to form a plurality of LED devices.