SEMICONDUCTOR ELEMENT

1 . A semiconductor element, comprising:

a substrate, comprising a bottom portion and an island-shaped protrusion,

wherein the island-shaped protrusion is disposed on the bottom portion;

a light-emitting diode chip disposed on the island-shaped protrusion; and

an encapsulating layer disposed on the light-emitting diode chip;

wherein a side surface of the island-shaped protrusion has a first roughness, a top surface of the island-shaped protrusion has a second roughness, and the first roughness is different from the second roughness.

2 . The semiconductor element as claimed in claim 1 , wherein the first roughness of the side surface of the island-shaped protrusion is greater than the second roughness of the top surface of the island-shaped protrusion.

3 . The semiconductor element as claimed in claim 1 , wherein the first roughness of the side surface of the island-shaped protrusion is greater than or equal to 0.28 um.

4 . The semiconductor element as claimed in claim 1 , wherein the second roughness of the top surface of the island-shaped protrusion is less than or equal to 0.25 um.

5 . The semiconductor element as claimed in claim 1 , wherein the encapsulating layer covers the bottom portion, the island-shaped protrusion, and the light-emitting diode chip.

6 . The semiconductor element as claimed in claim 1 , wherein a side surface of the bottom portion is aligned with a side surface of the encapsulating layer.

7 . The semiconductor element as claimed in claim 1 , wherein a first pitch between the side surface of the island-shaped protrusion and a side surface of the bottom portion is d 1 , and satisfies:

0

<

d

⁢

1

<

Xb

⁢

1

-

Hb

1

-

(

1

n

⁢

1

)

2

wherein,

Xb 1 is a first distance between a first side surface of the light-emitting diode chip and the side surface of the bottom portion;

Hb is a chip height of the light-emitting diode chip; and

n 1 is a refractive index of the encapsulating layer.

8 . The semiconductor element as claimed in claim 7 , wherein the first pitch is greater than or equal to 10 um and less than or equal to 20 um.

9 . The semiconductor element as claimed in claim 7 , wherein the refractive index of the encapsulating layer is greater than 1.

10 . The semiconductor element as claimed in claim 1 , wherein a first pitch between the side surface of the island-shaped protrusion and a side surface of the bottom portion is d 1 , and satisfies:

Hi

×

Xb

⁢

1

Hb

+

Hi

≥

d

⁢

1

wherein,

Xb 1 is a first distance between a first side surface of the light-emitting diode chip and the side surface of the bottom portion;

Hb is a chip height of the light-emitting diode chip; and

Hi is a protrusion height of the island-shaped protrusion.

11 . The semiconductor element as claimed in claim 1 , wherein a protrusion height of the island-shaped protrusion is Hi, and satisfies:

Hi

≥

Hb

×

d

⁢

1

(

Xb

⁢

1

-

d

⁢

1

)

wherein,

Hb is a chip height of the light-emitting diode chip;

d 1 is a first pitch between the side surface of the island-shaped protrusion and a side surface of the bottom portion; and

Xb 1 is a first distance between a first side surface of the light-emitting diode chip and the side surface of the bottom portion.

12 . The semiconductor element as claimed in claim 10 , wherein the protrusion height is greater than or equal to 35 um and less than or equal to 45 um.

13 . The semiconductor element as claimed in claim 1 , wherein a projection area of the island-shaped protrusion on the bottom portion accounts for A % of a total area of the bottom portion, and satisfies:

(

P

⁢

1

-

2

×

Hi

×

Xb

⁢

1

Hb

+

Hi

)

×

(

P

⁢

2

-

2

×

Hi

×

Xb

⁢

2

Hb

+

Hi

)

P

⁢

1

×

P

⁢

2

×

100

⁢

%

≤

A

⁢

%

<

100

⁢

%

wherein,

P 1 is a width of the semiconductor element;

P 2 is a length of the semiconductor element;

Hi is a protrusion height of the island-shaped protrusion;

Hb is a chip height of the light-emitting diode chip;

Xb 1 is a first distance between a first side surface of the light-emitting diode chip and the side surface of the bottom portion; and

Xb 2 is a second distance between a second side surface of the light-emitting diode chip and the side surface of the bottom portion.

14 . The semiconductor element as claimed in claim 13 , wherein the projection area of the island-shaped protrusion on the bottom portion accounts for 85% to 93% of the total area of the bottom portion.

15 . The semiconductor element as claimed in claim 1 , wherein the light-emitting diode chip comprises at least one blue light-emitting diode chip.

16 . The semiconductor element as claimed in claim 15 , wherein the light-emitting diode chip further comprises a green light-emitting diode chip or a red light-emitting diode chip.

17 . The semiconductor element as claimed in claim 1 , wherein the encapsulating layer comprises a light-transmitting matrix, and a light emitted by the light-emitting diode chip penetrates the light-transmitting matrix.

18 . The semiconductor element as claimed in claim 17 , wherein the encapsulating layer further comprises a wavelength conversion material dispersed in the light-transmitting matrix.

19 . The semiconductor element as claimed in claim 1 , wherein the island-shaped protrusion and the bottom portion have the same material.

20 . The semiconductor element as claimed in claim 1 , wherein the island-shaped protrusion is integrally formed with the bottom portion.