CN102610708B - How to make light-emitting diodes - Google Patents

Abstract

The invention relates to a method for manufacturing a light-emitting diode, which comprises the following steps: the method comprises the steps of front-end process, electrode manufacturing, semi-finished product formation after electrode manufacturing, chemical film forming and cutting, wherein the chemical film forming comprises the following steps: providing a solution which is alkaline and has high oxygen content; and soaking, namely soaking the semi-finished product in the solution to enable the semi-finished product to react with the solution so as to form an AlGaAs oxide layer at a preset position of the semi-finished product. Therefore, the service life of the light emitting diode under high humidity can be improved.

Description

How to make light-emitting diodes

technical field

The invention relates to a method for manufacturing a light-emitting diode, in particular to a method for making a light-emitting diode that can increase the lifespan of the light-emitting diode under high humidity.

Background technique

Due to the advantages of small size, low power consumption and long life, light-emitting diodes (LED: Light Emitting Diode) have been widely used in home appliances, vehicles, computer peripheral products, communication products and lighting products. The importance of the new generation of light sources cannot be overstated.

As for the manufacture of the above-mentioned light-emitting diode (commonly known as: crystal grain), please refer to Figure 1. The existing manufacturing method includes: the previous process (this is known, so it will not be described in detail, and the drawing is not drawn) S101, making electrodes S102 and cutting S103, in other words, the existing manufacturing method is to cut after the electrode is made, and after cutting, the finished light-emitting diodes as shown in Figure 2 are formed. The light-emitting diode 1 includes an aluminum arsenic Gallium (AlGaAs) layer 11, a back side metal (Back side metal) layer 13 and a gallium arsenide (GaAs) layer 12 between the aluminum gallium arsenide layer 11 and the back side metal layer 13, and also includes a set An electrode (Bonding Pad) 14 on the surface of the AlGaAs layer 11.

However, since Taiwan, China is surrounded by the sea, the humidity in the air is relatively high, which will easily cause the lifespan of LEDs to be short, not to mention that there are many countries and regions with relatively high humidity in the world, where LEDs have been highly used. Now that it is applied, how to solve the problem of short service life of light-emitting diodes has long been urgent.

Therefore, how to design a manufacturing method of the present invention that can increase the lifetime of the light-emitting diode under high humidity is a major problem that the inventors of the present case desire to solve.

Contents of the invention

One of the objectives of the present invention is to provide a method for manufacturing a light-emitting diode capable of forming an oxide layer (ie, a passivation layer) at a predetermined location, so as to increase the lifespan of the light-emitting diode under high humidity.

The second object of the present invention is to provide a method for manufacturing a light-emitting diode that can improve the uniformity of the oxide layer (i.e., the passivation layer), so as to improve the lifespan of the light-emitting diode under high humidity. That is: the more uniform the passivation layer, the better.

In order to achieve the above-mentioned purpose, the present invention provides a method for manufacturing a light-emitting diode, comprising: a front-stage process, making electrodes and cutting steps, and forming a semi-finished product after making electrodes, characterized in that: between the making electrodes step and the cutting step further includes A chemical film forming step, the chemical film forming step includes: providing a solution, the solution is alkaline and has a high oxygen content; and soaking, soaking the semi-finished product in the solution, so that the semi-finished product itself reacts with the solution, And a layer of oxide layer is formed on the predetermined position of the semi-finished product. Therefore, the lifetime of the light emitting diode under high humidity can be improved.

Preferably, the manufacturing method of the light emitting diode of the present invention further includes a uniform means, and the uniform means is to make the formation of the oxide layer more uniform. Therefore, the effect of increasing the lifespan of the light-emitting diode under high humidity can be better because the oxide layer is more uniform.

Description of drawings

Fig. 1 is the flow chart of existing preparation method.

FIG. 2 is a schematic structural diagram of a light-emitting diode manufactured according to a conventional manufacturing method.

Fig. 3 is a flowchart of the first embodiment of the method of the present invention.

Fig. 4 is a flow chart of the second embodiment of the method of the present invention.

Fig. 5 is a schematic structural view of a light-emitting diode manufactured according to the method of the present invention.

Fig. 6 is a schematic structural view of the control device used in soaking according to the present invention.

Fig. 7 is a schematic diagram of the method of the present invention under isolation control.

Description of main component symbols

1 LED

11 AlGaAs layer 12 GaAs layer

13 back metal layer 14 electrodes

2 LEDs

21 AlGaAs layer 22 GaAs layer

23 back metal layer 24 electrodes

25 Passivation layer 26 Groove

27 gallium arsenide

3 control device

31 Base 32 Inclined frame

33 container 331 solution liquid level 34 placing tool

4 release agent

S301 Front-end process

S303 Making electrodes

S305 chemical film formation

S307 cutting

S401 Front-end process

S403 Making electrodes

S405 Uniform means

S407 chemical film formation

S409 cutting

Detailed ways

In order to further understand the features, features and technical content of the present invention, please refer to the following detailed description and accompanying drawings of the present invention, but the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present invention.

The invention provides a method for making a light-emitting diode, mainly forming a mixed oxide layer on the light-emitting diode, which is marked as a passivation (Passivation) layer, so as to improve the life of the light-emitting diode under high humidity, and also The axial brightness of the light-emitting diode can be improved. As shown in Fig. 3 and Fig. 4, the first and second embodiments of the method of the present invention are disclosed respectively.

<First embodiment>

Please refer to the first embodiment of the present invention shown in Fig. 3 and Fig. 5. The method of the present invention includes: front-end process (for example: yellow light, chemical etching or cleaning, evaporation and alloying, etc.) S301, making electrodes S303 and cutting steps S307, and after making the electrode 24 as shown in Figure 5 to form a semi-finished product, the feature of the present invention is: a chemical film forming S305 step is further included between the two steps of making the electrode S303 and cutting S307, the chemical film forming S305 Steps include:

Provide a solution, the solution is an alkaline solution with a high oxygen content (for example: an oxygen content greater than 28% based on hydrogen peroxide H ₂ O ₂ , which is a high oxygen content solution); and,

Soaking means immersing the semi-finished product in the solution so that the semi-finished product itself reacts with the solution to form an oxide layer at the predetermined position of the semi-finished product. This oxide layer is marked as a passivation layer 25 .

Wherein, the semi-finished product of the light-emitting diode 2 includes an aluminum gallium arsenide layer 21 and a gallium arsenide layer 22, therefore, the semi-finished product itself has materials such as aluminum, gallium and arsenic, and the aluminum, gallium and arsenic react with the solution And form described oxide layer (aluminium-gallium-arsenic oxide layer), this oxide layer promptly marks as passivation layer 25, and the chemical reaction formula of this semi-finished product itself and solution is:

2Al ³⁺ +6OH ^- →2Al ₂ (OH) ₃ →Al ₂ O ₃ +3H ₂

2Ga ³⁺ +6OH ^- →2Ga ₂ (OH) ₃ →Ga ₂ O ₃ +3H ₂

2As ³⁺ +6OH ^- →2As ₂ (OH) ₃ →As ₂ O ₃ +3H ₂

, used to obtain aluminum oxide, gallium oxide and arsenic oxide mixed into the oxide layer, this oxide layer is marked as the passivation layer 25 . The solution is a mixed solution of ammonia and hydrogen peroxide (as follows):

NH ₄ OH:H ₂ O ₂

, and because the ratio of ammonia water to hydrogen peroxide is too high, it will damage the light-emitting diode 2, but if the ratio is too low, the process time will be relatively increased. Therefore, the ratio of ammonia water to hydrogen peroxide in the mixed solution is 1:50～1: 150.

Please refer to Fig. 5, the light-emitting diode 2 manufactured by the method of the present invention includes an aluminum gallium arsenide (AlGaAs) layer 21, a back side metal (Back side metal) layer 23 and a layer located on the aluminum gallium arsenide layer. 21 and the gallium arsenide (GaAs) layer 22 between the back metal layer 23, and also includes an electrode (Bonding Pad) 24 arranged on the surface of the aluminum gallium arsenide layer 21 and an electrode (Bonding Pad) 24 also formed on the aluminum gallium arsenide layer Passivation layer 25 on the surface of 2l.

<Second Embodiment>

Since the formed passivation layer 25 is more uniform, the effect is better. Therefore, please refer to FIG. 4 and FIG. S405, that is, the manufacturing method of the second embodiment of the present invention includes: front-end process S401, electrode fabrication S403, uniform means S405, chemical film formation S407, and cutting step S409.

The uniform means S405 includes: surface oxide removal, low temperature control, angle control, immersion control and isolation control.

The removal of the surface oxide: remove the oxide on the surface of the semi-finished product, preferably before chemical film formation: dilute the mixed solution of hydrofluoric acid (HF:H ₂ O) to treat the surface of the semi-finished product, or use a mixed solution formed by mixing sulfuric acid, hydrogen peroxide and water (H ₂ SO ₄ : _{H 2} O ₂ :H ₂ O) in a ratio of 3:1:1 to treat the surface of the semi-finished product , the oxide layer (passivation layer 25) is formed on this surface.

Among them, low temperature control: due to the poor uniformity of high temperature film formation (that is: formation of passivation layer 25), and low temperature film formation can obtain better uniformity, and it is also easier to control the thickness of passivation layer 25, so , the low temperature control is to control the temperature above 5°C and below 25°C.

Angle control and immersion control wherein: when forming a film (i.e. forming a passivation layer 25), the solution will generate air bubbles, which will affect the uniformity of film formation, so it is necessary to give an angle to avoid the formation of bubbles caused by air bubbles. Uneven, the angle control is to control the placement angle of the semi-finished product to have an inclination angle of 5-35 degrees from the ground plane. As for immersion control, the control solution must completely cover the semi-finished product. Please refer to the control device 3 shown in Figure 6, which includes a base 31, a slant frame 32 mounted on the pedestal 31, a container 33 carried on the slant frame 32, and a container housed in the container 33. Tool 34, the inclined frame 32 has an inclination angle of 5-35 degrees, the semi-finished products of light emitting diodes are placed on the tool 34, and the solution is also contained in the container 33, and the solution is liquid The surface 331 is higher than the semi-finished product, in other words, angle control and soaking control can be achieved at the same time through this control device 3 . As for the base 31 , it is better to use a shock-absorbing material for the base 31 because it must be left still and avoid vibrations during film formation (otherwise the passivation layer 25 will easily fall off).

Isolation control among them: Assuming that there is a first reaction rate between the predetermined place of the semi-finished product and the solution, and a second reaction rate between other places of the semi-finished product and the solution, the isolation control must be at the predetermined place of the semi-finished product The passivation layer 25 is formed unevenly because of different reaction rates. As shown in the embodiment of the present invention, because part of the process will cause the gallium arsenide layer 22 to be exposed, and the reaction rate between the gallium arsenide layer 22 and the solution is much higher than that of the surface aluminum gallium arsenide layer 21, so the two must be isolated to increase Uniformity (of course, the isolation control described above can also be used to protect the electrodes if necessary). Please refer to Figure 7, the isolation control includes:

A plurality of grooves 26 are formed on the surface of the AlGaAs layer 21; and

An isolator (for example: photoresist, etc.) 4 is filled in each of the trenches 26 for isolation. Thus, the method of the present invention carries out the step of chemical film formation S407 to form the passivation layer 25 after the isolation control. After the step of chemical film formation S407, the spacers 4 filled in must be removed to facilitate the production of the present invention. The final step of the method: the cutting S409, in other words, the cutting S409 is based on these grooves 26 as the predetermined cutting line for cutting, and after cutting, the individual light-emitting diodes 2 shown in FIG. 7 are formed. . Wherein, the grooves 26 are formed by half-cutting or mesa etching; the depth of the grooves 26 reaches the GaAs layer 22 .

To sum up, the characteristic of the manufacturing method of the light-emitting diode of the present invention is that a mixed oxide layer is formed on the surface of the aluminum gallium arsenide layer 21, and this oxide layer is marked as a passivation layer 25 to improve the performance of the light-emitting diode. 2 life under high humidity, and the more uniform the formed passivation layer 25 is, the better the effect of improving the life of the light emitting diode 2 is, and even the axial brightness of the light emitting diode 2 can be improved; moreover, according to the present invention The passivation layer 25 formed by the method also has the characteristics of low cost.

The above is only a preferred feasible embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the description and drawings of the present invention are all included in the present invention. Within the scope of rights, I agree with Chen Ming.

Claims (18)

1. A method for making a light-emitting diode, comprising a front-end process, making electrodes and cutting steps, and forming a semi-finished product after making electrodes, characterized in that: a chemical film-forming step is further included between the making electrodes step and the cutting step, the Chemical film formation steps include: providing a solution, the solution is alkaline, wherein the solution has an oxygen content greater than 28% based on hydrogen peroxide (H ₂ O ₂ ); and Soaking, immersing the semi-finished product in the solution, and controlling the temperature at above 5°C and below 25°C, so that the semi-finished product itself reacts with the solution and forms an oxide layer on the predetermined part of the semi-finished product. 2. The method of manufacturing a light-emitting diode according to claim 1, wherein the semi-finished product itself has aluminum, gallium and arsenic, and the aluminum, gallium and arsenic react with the solution to form the oxide layer. 3. The method for preparing light-emitting diodes as claimed in claim 2, wherein the chemical reaction formula between the semi-finished product itself and the solution is: 2Al ³⁺ +6OH ^- →2Al ₂ (OH) ₃ →Al ₂ O ₃ +3H ₂ 2Ga ³⁺ +6OH ^- →2Ga ₂ (OH) ₃ →Ga ₂ O ₃ +3H ₂ 2As ³⁺ +6OH ^- →2As ₂ (OH) ₃ →As ₂ O ₃ +3H ₂ It is used to obtain aluminum oxide, gallium oxide and arsenic oxide to form the oxide layer. 4. The method for preparing a light-emitting diode according to claim 2, wherein the solution is a mixed solution of ammonia and hydrogen peroxide. 5. The method for manufacturing a light emitting diode as claimed in claim 1, further comprising a uniform means, the uniform means is to make the formation of the oxide layer more uniform. 6 . The method for manufacturing a light emitting diode as claimed in claim 5 , wherein the uniform means includes: removing surface oxide, which is to remove the oxide on the surface of the semi-finished product. 7. The method for manufacturing a light-emitting diode according to claim 6, wherein the surface oxide is removed by treating the surface of the semi-finished product with a mixed solution of dilute hydrofluoric acid before chemical film formation, The oxide layer is formed on this surface. 8. The method for manufacturing a light-emitting diode according to claim 6, wherein the removal of the surface oxide is formed by mixing sulfuric acid, hydrogen peroxide and water in a ratio of 3:1:1 before chemical film formation The mixed solution is used to treat the surface of the semi-finished product, and the oxide layer is formed on this surface. 9. The manufacturing method of light-emitting diodes as claimed in claim 5, characterized in that, the means for uniformity includes: angle control, which means that there must be an inclination angle of 5-35 degrees between the placement angle of the semi-finished product and the ground plane . 10. The manufacturing method of light-emitting diodes according to claim 5, characterized in that, the uniform means includes: soaking control, which means that the solution must completely cover the semi-finished product. 11. The method for producing light-emitting diodes according to claim 5, wherein the means for uniformity comprises: isolation control, a first reaction rate between the predetermined part of the semi-finished product and the solution, and a first reaction rate between other parts of the semi-finished product and the solution. There is a second reaction rate between them, and the isolation control is to isolate the predetermined place of the semi-finished product from other places. 12. The method for manufacturing a light-emitting diode according to claim 11, wherein the semi-finished product has an AlGaAs layer, a backside metal layer, and GaAs between the AlGaAs layer and the backside metal layer layer, the semi-finished product also has electrodes disposed on the surface of the AlGaAs layer, and the oxide layer is also formed on the surface of the AlGaAs layer; as for the isolation control, it includes: A plurality of grooves are formed on the surface of the AlGaAs layer; and Isolating agents are filled in each of the trenches for isolation. 13. The method for manufacturing a light-emitting diode as claimed in claim 12, wherein the isolation control is followed by a chemical film forming step, and the filled isolation agents must be removed after the chemical film forming step. 14. The method for manufacturing a light-emitting diode as claimed in claim 12, wherein the grooves are predetermined cutting lines during the cutting step. 15. The method of manufacturing a light emitting diode as claimed in claim 12, wherein the trenches are formed by one of half-cutting and mesa etching. 16. The method of manufacturing a light-emitting diode as claimed in claim 12, wherein the depth of the grooves reaches to the gallium arsenide layer. 17. The method for manufacturing a light emitting diode as claimed in claim 12, wherein each of the spacers is a photoresist. 18 . The method for manufacturing a light emitting diode as claimed in claim 1 , wherein the semi-finished product must be soaked in the solution in a manner of standing still and avoiding vibration during chemical film formation. 19 .