TWI429105B - Led substrate and manufacturing mehtod thereof and led - Google Patents

Description

Light-emitting diode substrate, manufacturing method thereof and light-emitting diode

The present invention relates to a light emitting diode technology, and more particularly to a light emitting diode substrate, a method of fabricating the same, and a light emitting diode using the same.

A light-emitting diode is a light-emitting element made of a compound semiconductor, which can be converted into light by means of a combination of electrons and holes. The light-emitting diode is cold-emitting, so it has the advantages of low power consumption, no lamp warm-up time, long component life, fast reaction speed, etc., plus its small size, impact resistance, and mass production, which is easy to match with the application. It can be made into very small or array components.

In order to make the LEDs have more application space and prospects in the future, how to improve the luminance of the LEDs is one of the most important studies in the world. However, in fact, due to various loss mechanisms, the photons generated by the active region of the light-emitting diode cannot be transmitted 100% to the outside world.

At present, in order to improve the luminous efficiency of the light-emitting diode, a patterned light-emitting diode substrate, such as a light-emitting diode substrate composed of a plurality of cone or platform structures, has been used to scatter light emitted by the light-emitting diode. To reduce total reflection.

The invention provides a light-emitting diode substrate with high light-emitting efficiency.

The present invention further provides a light emitting diode having the above light emitting diode substrate.

The present invention further provides a method of manufacturing a light-emitting diode substrate, which can produce a substrate having high light-emitting efficiency.

The invention provides a light emitting diode substrate comprising a sapphire substrate having a plurality of upper three lower hexagonal cones, wherein each upper three lower six structures is a hexagonal cone and a triangular pyramid on the hexagonal cone The structure of the composition. Moreover, the ratio of the projected area of each triangular pyramid to the projected area of each of the upper three lower hexagonal cones is greater than zero and less than 0.5.

In an embodiment of the invention, the ratio of the total projected area of the triangular pyramid of the upper three lower hexagonal cones to the projected area of the sapphire substrate is, for example, less than 0.2.

In one embodiment of the invention, the upper three lower hexagonal cones have a pitch of less than 10 μm.

In an embodiment of the invention, the maximum height of each of the upper three lower hexagonal cones is, for example, between 1 μm and 2 μm.

In an embodiment of the invention, the top of the triangular pyramid is planar or pointed.

In an embodiment of the present invention, the symmetrical section of the triangular pyramid has a first bottom angle and a second bottom angle, the second bottom angle is greater than the first bottom angle, and the second bottom angle is at an angle of 28 degrees to Between 32 degrees.

In an embodiment of the invention, the symmetrical cross section of the hexagonal cone having the triangular pyramid has a third bottom angle and a fourth bottom angle, wherein the fourth bottom angle is greater than the third bottom angle, and the fourth bottom angle The angle is between 50 and 70 degrees.

In one embodiment of the invention, the surface of the sapphire substrate other than the upper three lower hexagonal cones is a (0001) plane, and the (0001) plane occupies between 10% and 60% of the projected area of the sapphire substrate.

The present invention further provides a light emitting diode having the above light emitting diode substrate.

The invention further provides a method for manufacturing a light-emitting diode substrate, comprising etching the sapphire substrate by using at least one wet etching process, so as to etch a plurality of upper and lower hexagonal cones on the surface thereof, wherein each of the three upper and lower hexagonal cones The hexagonal cone is a structure composed of a hexagonal cone and a triangular pyramid on the hexagonal cone, and the ratio of the projected area of the triangular pyramid to the projected area of each of the upper three lower hexagonal cones is greater than 0 and less than 0.5.

In still another embodiment of the present invention, the wet etching is performed by using a patterned hard mask formed on the surface of the sapphire substrate as an etching mask.

In still another embodiment of the present invention, the wet etching process includes a single wet etching step or two wet etching steps.

In still another embodiment of the present invention, the single wet etching step includes etching using a mixed etching solution containing at least phosphoric acid to form a triangular pyramid in the upper three lower hexagonal cones.

In still another embodiment of the present invention, the two wet etching steps include performing a first wet etching step to form a plurality of hexagonal pyramids on the surface of the sapphire substrate, and then performing a second wet etching step. The above triangular pyramid is formed on a hexagonal cone.

Based on the above, the structure of the present invention basically consists of a sapphire substrate composed of a plurality of upper three lower hexagonal cones as a light-emitting surface, so that the light scattering can be increased by the nine faces of the upper three lower hexagonal cones themselves. Further improving the light extraction efficiency of the substrate. Moreover, the ratio of the projected area of the triangular pyramid to the projected area of each of the upper three lower hexagonal cones is less than 0.5, which can reduce problems such as voids or electrostatic discharge (ESD) caused by epitaxial defects.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a perspective view of a light emitting diode substrate in accordance with a first embodiment of the present invention. A sapphire substrate 100 is shown in FIG. This sapphire substrate 100 has a plurality of upper three lower hexagonal cones 102. Each of the upper three lower hexagonal cones 102 is a structure consisting of a hexagonal cone 104 and a triangular pyramid 106 on the hexagonal cone 104, wherein each surface of the hexagonal cone 104 belongs to the same direction family and a triangular pyramid. Each surface of the body 106 is also in the same direction family. Moreover, the ratio of the projected area of each triangular pyramid 106 to the projected area of a single upper triple hexagonal cone 102 needs to be greater than zero and less than 0.5. When the ratio of the projected area of the single triangular pyramid 106 to the projected area of the single upper triple hexagonal cone 102 is greater than 0.5, voids may occur due to the influence of epitaxy or electrostatic discharge (ESD) may be caused. In the first embodiment, the ratio of the total projected area of the triangular pyramid 106 of the upper three lower hexagonal cones 102 to the projected area of the entire sapphire substrate 100 is, for example, less than 0.2.

The surface of the sapphire substrate 100 of the present embodiment other than the upper three lower hexagonal cones 102 is a (0001) plane, and the (0001) plane can occupy 10% to 60% of the projected area of the entire sapphire substrate 100; preferably 10 %~30%. When the (0001) plane occupies more than 60% of the projected area of the entire sapphire substrate 100, the gain of light output efficiency may be insufficient, but when the (0001) plane occupies less than 10% of the projected area of the entire sapphire substrate 100, It may cause difficulties in epitaxial.

2A and 2B, wherein FIG. 2A is a perspective view of two upper three lower hexagonal cones in the first embodiment; FIG. 2B is three above FIG. Schematic diagram of a symmetrical section of a hexagonal cone (a section of a BB line segment).

The pitch p of the upper three lower hexagonal cones 102 is shown in Figure 2B. The term "period" means the distance between each of the upper and lower hexagonal cones 102. In the present embodiment, p is, for example, less than 10 μm, preferably between 1 μm and 4 μm. The maximum height h of the upper three lower hexagonal cones 102 is, for example, proportional to the period of the upper three lower hexagonal cones 102; that is, the larger the p, the higher the h, the smaller the p, the lower the h. The so-called "maximum height" is the distance from the top of the triangular pyramid 106 to the bottom of the hexagonal cone 104. In the present embodiment, the maximum height of the upper three lower hexagonal cones 102 is, for example, between 1 μm and 2 μm, preferably. It is between 1.5μm and 2μm. When the maximum height of the upper three lower hexagonal cones 102 is greater than 2 μm, there may be cases where it is difficult to epitaxial.

In this embodiment, the symmetrical section of the triangular pyramid 106 of the upper three lower hexagonal cones 102 has a first bottom angle a1 and a second bottom angle a2, the second bottom angle a2 is greater than the first bottom angle a1, and the second bottom The angle of the angle a2 is, for example, between 28 and 32 degrees; the symmetrical section of the hexagonal cone 104 has a third base angle a3 and a fourth base angle a4, wherein the fourth base angle a4 is greater than the third base angle a3, and fourth The angle of the base angle a4 is, for example, between 50 and 70 degrees; preferably between 55 and 65 degrees.

The top of the triangular pyramid 106 in the above figures is the tip end, but the present invention is not limited thereto, and the top of the triangular pyramid 106 may also have a flat shape as in Fig. 3 of the second embodiment.

In FIG. 3, the sapphire substrate 300 of the second embodiment has the same upper three lower hexagonal cones 302 as the first embodiment, and each upper three lower hexagonal cone 302 is a hexagonal cone 304 and a triangle. The structure of the cone 306. The second embodiment differs from the first embodiment in that the top of the triangular pyramid 306 of FIG. 3 is a flat surface 308, and a mask (not shown) may be present on the flat surface 308. As for other structural parameters, the first embodiment can be referred to, and therefore will not be described again.

4 is a cross-sectional view showing a light emitting diode according to a third embodiment of the present invention. A sapphire substrate 100 of the first embodiment is shown in Fig. 4 (see Fig. 1 for details). On the sapphire substrate 100, a first semiconductor layer 400, a light emitting layer 402, a second semiconductor layer 404, a first ohmic electrode 406 contacting the first semiconductor layer 400, and a second ohmic electrode contacting the second semiconductor layer 404 are generally disposed. 408. However, the sapphire substrate 100 in FIG. 4 can also be replaced with a sapphire substrate 300 (see FIG. 3 for details).

In the third embodiment, the first semiconductor layer 400, the light emitting layer 402, and the second semiconductor layer 404 may be a III-V semiconductor, such as a gallium nitride based semiconductor. As for the first and second ohmic electrodes 406 and 408, for example, oxides and nitrogens containing nickel, lead, cobalt, iron, titanium, copper, ruthenium, gold, rhenium, tungsten, zirconium, molybdenum, niobium, silver, and the like. At least one alloy or multilayer film selected from the group consisting of the compounds. In addition, the first and second ohmic electrodes 406 and 408 may also be an alloy or a multilayer film selected from the group consisting of ruthenium, osmium, silver, and aluminum.

5A to 5C are schematic cross-sectional views showing a manufacturing process of a light-emitting diode substrate according to a fourth embodiment of the present invention.

Referring first to FIG. 5A, a sapphire substrate 500 is first prepared, and then a patterned hard mask 502 is formed on the sapphire substrate 500, which is composed of a plurality of circular pattern masks 502a, each of which is patterned by a circular pattern mask 502a. The diameter is, for example, less than 1 μm; preferably greater than 0 μm to 0.7 μm. In addition, the patterned hard mask 502 may also be provided with other shapes of pattern masks, such as squares, triangles, etc., and is not limited to the circular shape shown in the figure.

Then, referring to FIG. 5B, the sapphire substrate 500 is subjected to a single wet etching step using a mixed etching solution, such as an etching solution containing at least phosphoric acid. Moreover, by adjusting the acid ratio of the mixed etching liquid, the circular pattern mask 502a can be gradually reduced while etching the sapphire substrate 500, for example, the phosphoric acid ratio of the mixed etching liquid (ie, phosphoric acid/mixed acid) is adjusted. Within the range of 0.1~0.5. During this etch, the sapphire substrate 500 will first form a hexagonal cone 504.

Thereafter, referring to FIG. 5C, while the circular pattern mask 502a of FIG. 5B is gradually etched away, the mixed etching solution containing at least phosphoric acid continues to etch the sapphire substrate 500 to form on the original hexagonal cone 504. Triangular cone 506. The process of the fourth embodiment can not only produce the light-emitting diode substrate of FIG. 1, but if the circular pattern mask 502a remains on the triangular pyramid 506 as shown in FIG. 5B, the light emission of FIG. 3 can be formed. Diode substrate.

6A to 6C are schematic cross-sectional views showing a manufacturing process of a light-emitting diode substrate according to a fifth embodiment of the present invention.

Referring first to FIG. 6A, a sapphire substrate 600 is first prepared, and then a patterned hard mask 602 is formed on the surface thereof, which is composed of a plurality of circular pattern masks 602a, each of which has a diameter of the mask 602a. For example, it is less than 1 μm; preferably more than 0 μm to 0.7 μm. In addition, the patterned hard mask 602 may also be provided with other shapes of pattern masks, such as squares, triangles, etc., and is not limited to the circular shape shown in the figure.

Then, referring to FIG. 6B, a first wet etching step is performed, such as wet etching using a first etching solution 604 for about several minutes. During this etch, the sapphire substrate 600 will first appear as a hexagonal cone 606.

Thereafter, referring to FIG. 6C, a second wet etching step is performed, for example, a second etching solution 608 is used for wet etching for about 1 minute, and the temperature can be controlled between 250 ° C and 300 ° C. The temperature in the etching step is inversely proportional to the time. For example, the wet etching time is shorter when the temperature is higher; on the contrary, the wet etching time is longer when the temperature is lower. A triangular pyramid 610 is formed on the hexagonal cone 606 after the etching is completed.

Process of the Fifth Embodiment If the circular pattern mask 602a is removed prior to FIG. 6C, the light-emitting diode substrate of FIG. 1 can be formed. Further, if the circular pattern mask 602a is left, the light-emitting diode substrate of FIG. 3 can be formed.

The above is merely a description of several manufacturing processes for the light-emitting diode substrate of the present invention, and is not intended to limit the scope of the present invention.

In summary, the illuminating diode substrate of the present invention is a sapphire substrate composed of a top three lower hexagonal cone as a light-emitting surface, and the area ratio of the triangular pyramid to the upper three hexagonal pyramid is controlled within a certain range. Therefore, the degree of light scattering can be greatly increased, and the light-emitting efficiency of the light-emitting diode using such a substrate can be increased.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 300, 500, 600. . . Sapphire substrate

102, 302. . . Upper three lower hexagonal cone

104, 304, 504, 606. . . Hexagonal cone

106, 306, 506, 610. . . Triangular cone

308. . . flat

400. . . First semiconductor layer

402. . . Luminous layer

404. . . Second semiconductor layer

406. . . First ohmic electrode

408. . . Second ohmic electrode

502, 602. . . Hard mask

502a, 602a. . . Round pattern mask

604, 608. . . Etching solution

A1, a2, a3, a4. . . Bottom angle

h. . . maximum height

p. . . cycle

1 is a perspective view of a light emitting diode substrate in accordance with a first embodiment of the present invention.

Fig. 2A shows a perspective view of two upper three lower hexagonal cones in the first embodiment.

Figure 2B is a schematic cross-sectional view of the three lower hexagonal cones above Figure 2A.

3 is a perspective view of a light emitting diode substrate in accordance with a second embodiment of the present invention.

4 is a cross-sectional view showing a light emitting diode according to a third embodiment of the present invention.

5A to 5C are schematic cross-sectional views showing a manufacturing process of a light-emitting diode substrate according to a fourth embodiment of the present invention.

6A to 6C are schematic cross-sectional views showing a manufacturing process of a light-emitting diode substrate according to a fifth embodiment of the present invention.

100. . . Sapphire substrate

102. . . Upper three lower hexagonal cone

104. . . Hexagonal cone

106. . . Triangular cone

Claims (14)

A light-emitting diode substrate comprising a sapphire substrate, the sapphire substrate having a plurality of upper three lower hexagonal cones, each upper triple hexagonal cone being a hexagonal cone and a triangular cone located on the hexagonal cone The structure of the body, the light emitting diode substrate is characterized in that the ratio of the projected area of the triangular pyramid to the projected area of each of the upper three lower hexagonal cones is greater than 0 and less than 0.5. The light-emitting diode substrate of claim 1, wherein a ratio of a total projected area of the triangular pyramid of the upper three lower hexagonal pyramids to a projected area of the sapphire substrate is less than 0.2. The light-emitting diode substrate of claim 1, wherein the upper three lower hexagonal cones have a period of less than 10 μm. The light-emitting diode substrate according to claim 1, wherein a maximum height of each of the upper three hexagonal pyramids is between 1 μm and 2 μm. The light-emitting diode substrate of claim 1, wherein the top of the triangular pyramid is a flat surface or a pointed end. The illuminating diode substrate of claim 1, wherein the triangular cross section has a first bottom angle and a second bottom angle, the second bottom angle being greater than the first bottom angle, and The angle of the second base angle is between 28 and 32 degrees. The illuminating diode substrate of claim 1, wherein the symmetrical cross section of the hexagonal cone has a third bottom angle and a fourth bottom angle, the fourth bottom angle being greater than the third bottom angle, and The angle of the fourth base angle is between 50 degrees and 70 degrees. The illuminating diode substrate of claim 1, wherein the surface of the sapphire substrate other than the upper three lower hexagonal pyramids comprises a (0001) plane, and the (0001) plane occupies a projected area of the sapphire substrate. Between 10% and 60%. A light-emitting diode comprising the light-emitting diode substrate according to any one of claims 1 to 8. A method for manufacturing a light-emitting diode substrate, comprising: etching a sapphire substrate by using at least one wet etching process to form a plurality of upper and lower hexagonal cones on the surface of the sapphire substrate, wherein each of the upper three hexagonal cones The body is a structure composed of a hexagonal cone and a triangular pyramid located on the hexagonal cone, and the ratio of the projected area of the triangular cone to the projected area of each of the upper three lower hexagonal cones is greater than 0 and less than 0.5. . The method for fabricating a light-emitting diode substrate according to claim 10, wherein the at least one wet etching process uses a patterned hard mask formed on the surface of the sapphire substrate as an etching mask. The method of fabricating a light-emitting diode substrate according to claim 10, wherein the at least one wet etching process comprises a single wet etching step or two wet etching steps. The method for fabricating a light-emitting diode substrate according to claim 12, wherein the single wet etching step comprises etching using a mixed etching solution to form the triangular pyramid in each of the upper three lower hexagonal cones. And the mixed etching solution includes at least phosphoric acid. The method for manufacturing a light-emitting diode substrate according to claim 12, wherein the two wet etching steps comprise: performing a first wet etching step to form a plurality of hexagonal cones on the surface of the sapphire substrate; And performing a second wet etching step to form the triangular pyramid on each of the hexagonal cones.