CN111106209B - A kind of preparation method of AlGaInP quaternary LED chip - Google Patents

Abstract

Preparation method of AlGaInP quaternary LED chipThe temporary bonding substrate is bonded through the temporary bonding material layer, the bonding layer is manufactured by bonding the lower end face of the ohmic contact layer, the permanent substrate layer is manufactured below the bonding layer by using an electron beam evaporation process, the P electrode is arranged on the P surface by using a secondary bonding technology, light is emitted from the P surface, the substrate is replaced by the method, the luminous efficiency is improved, meanwhile, the traditional electrode structure for emitting light from the P surface is obtained, and subsequent circuit management is facilitated. Meanwhile, the transparent conductive film adopts ITO or Zno or SiO₂Or TCF material, the refractive index of which is favorable for reducing the critical angle of light in packaging materials such as silica gel, epoxy and the like, so that the power of the LED chip manufactured by the method can be improved by about 10% compared with that of a common flip chip.

Description

A kind of preparation method of AlGaInP quaternary LED chip

technical field

The invention relates to the technical field of LEDs, in particular to a preparation method of an AlGaInP quaternary LED chip.

Background technique

LED is a new light source for lighting in the 21st century. Under the same brightness, the power consumption of semiconductor lamps is only 1/10 of that of ordinary incandescent lamps, and the lifespan can be extended by 100 times. LED devices are cold light sources with high luminous efficiency, low operating voltage, low power consumption, small size, flat packaging, easy to develop thin and light products, sturdy structure and long life, the light source itself does not contain mercury, lead and other harmful substances, No infrared and ultraviolet pollution, no pollution to the outside world during production and use. Therefore, semiconductor lamps have the characteristics of energy saving, environmental protection, and long life. Just like transistors replace electron tubes, semiconductor lamps will replace traditional incandescent lamps and fluorescent lamps. It will also be the general trend. Whether from the perspective of saving electricity, reducing greenhouse gas emissions, or reducing environmental pollution, LED as a new type of lighting source has great potential to replace traditional lighting sources.

The AlGaInP material system was originally used to fabricate visible-light laser diodes, first proposed by Japanese researchers in the mid-1980s. LED and LD devices in that period usually used Ga0.5In0.5P matched with GaAs substrate as the active light-emitting region, and the light-emitting wavelength was 650 nm, which was widely used in quaternary laser pointers, DVDs and players. Later, researchers found that the introduction of Al composition into GaInP can further shorten the emission wavelength, however, if the Al content is too high, the luminous efficiency of the device will drop sharply, because when the Al content in GaInP exceeds 0.53, AlGaInP will become Indirect band gap semiconductors, so AlGaInP materials are generally only used to prepare LED devices with emission wavelengths above 570 nm. In 1997, the world's first AlGaInP-based LED with multiple quantum well (MQW) composite Bragg reflector (DBR) structure was born. LED devices designed based on this structure still occupy a large share of the low-end LED market.

Aluminum gallium indium phosphorous (AlGaInP) materials are rapidly developed and used to make high-power, high-brightness red and yellow LEDs. Although red LEDs made of AlGaInP materials have been commercially produced, LEDs with quaternary alloy materials as the active region of multiple quantum wells have extremely high internal quantum efficiency. However, due to the limitations of the material itself and the substrate, the external quantum efficiency of conventional AlGaInP-LEDs is extremely low. An important reason for the poor light extraction efficiency of traditional AlGaInP-LEDs is that the substrate GaAs is a light absorbing material, resulting in a large amount of light radiated from the active layer (MQW) towards the substrate being absorbed by the GaAs substrate. Orientation reflection (ODR) and substrate transfer technology replace the traditional GaAs substrate, and the amount of radiation reflected to the active layer will still cause a fixed proportion of loss.

Chinese patent document CN104518056A discloses a method for preparing a reverse-polarity AlGaInP red light LED chip, which includes the following steps: (1) bonding the GaAs substrate light-emitting diode wafer and silicon wafer together; (2) etching the GaAs substrate , rotate the wafer 180 degrees in the vertical direction, and continue to corrode; (3) After the etching of the GaAs substrate is completed, scrape off the metal film layer remaining on the edge of the wafer; (4) Rinse the surface of the wafer; Use sulfuric acid solution to block the surface of the wafer (5) Paste a high temperature resistant tape strip with a larger area than the overlay mark on the plate registration mark of the wafer; (6) Then carry out the evaporation of the N-type metal electrode, and use the window etching solution to corrode the window; After the corrosion is completed, a clear overlay registration mark pattern is obtained. In this patent, the relevant dimensions are confirmed before the operation is carried out. Due to the long manufacturing process of the reverse polarity AlGaInP quaternary LED chip, the possibility of process instability is greater, and the final output chip is N-side light.

Chinese patent document CN104157757A discloses a solution: a quaternary light-emitting diode with a transparent substrate, including an AlGaInP-LED epitaxial wafer, and the surface of the GaP layer of the AlGaInP-LED epitaxial wafer is roughened and used as a bond surface, coat the film on the bonding surface, then bond the film with the transparent substrate, and finally remove the GaAs substrate. The thin film is one or more combinations of silicon oxide layer, silicon nitride layer, aluminum oxide layer and magnesium chloride layer, and the transparent substrate is sapphire, aluminum nitride or glass.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the above technologies, the present invention provides a preparation method of an AlGaInP quaternary LED chip that utilizes the P surface to emit light after changing the substrate.

The technical scheme adopted by the present invention to overcome its technical problems is:

A method for preparing an AlGaInP quaternary LED chip, comprising the following steps:

a) Preparation of an epitaxial wafer structure for LED, the epitaxial wafer structure from bottom to top is a gallium arsenide substrate, an N-type buffer layer, an N-type AlGaInP layer, a multiple quantum well layer and a P-type layer;

b) growing a layer of SiO ₂ on the P-type layer, and using the photolithography process to etch the SiO ₂ layer into N strip-shaped current blocking layers at uniform intervals, where N is a positive integer greater than or equal to 2;

c) prepare a layer of transparent conductive film on the P-type layer, the transparent conductive film is used as a current spreading layer, and the transparent conductive film is made of ITO or Zno or SiO ₂ or TCF material;

d) using silica gel material to bond on the current spreading layer and each current blocking layer to form a temporary bonding material layer, and making a temporary bonding substrate made of sapphire or silicon wafer or metal material on the temporary bonding material layer;

e) Etch the gallium arsenide substrate to the N-type buffer layer with an etching solution;

f) making an ohmic contact layer made of Ni and/or Ge and/or Au on the lower end face of the N-type buffer layer;

g) using the electron beam evaporation process to bond the lower end face of the ohmic contact layer to form a bonding layer, and using the electron beam evaporation process to make a permanent substrate layer below the bonding layer;

h) removing the temporary bonding material layer with a silica gel dissolving agent, so that the temporary bonding substrate is peeled off from the current spreading layer;

i) making a P electrode on the current blocking layer, and cutting along the vertical direction at the center between each two current blocking layers to form a scribe line, the depth of the scribe line reaching the upper surface of the ohmic contact layer;

j) Grinding and thinning the permanent substrate layer to the required thickness, and making the N-face metal layer of Ni or Ge or Au on the lower end face of the thinned permanent substrate layer;

k) Using laser cutting or grinding wheel cutter to cut along the cutting path to form N independent LED chips.

Preferably, in step b), an electron beam or PECVD process is used to grow a layer of SiO ₂ on the P-type layer, and the thickness of the grown SiO ₂ is 400-1200 Å.

Preferably, the thickness of the current spreading layer in step c) is 300-1200 Å.

Preferably, in step d), the bonding temperature when the temporary bonding material layer is formed by bonding is 100-200° C., and the bonding time is 2-4 hours.

Preferably, the corrosion solution in step e) is a mixed solution of ammonia water, hydrogen peroxide and water, wherein the volume ratio of ammonia water: hydrogen peroxide: water is 1:2:6.

Preferably, in step f), an ohmic contact layer is prepared on the lower end face of the N-type buffer layer by using an electron beam evaporation process or a sputtering metal material process.

Preferably, in step g), the bonding layer is made of Au and/or In and/or Ag and/or Al materials, the bonding temperature is 200-250° C., the bonding time is 15-30 min, and the bonding is performed during bonding. The pressure is 20-50 kg.cm ² .

Preferably, the dissolving temperature of the silica gel dissolving agent in step h) is 100-150°C.

Preferably, in step j), the permanent substrate layer is ground and thinned to a thickness of 100-180 μm.

The beneficial effects of the invention are as follows: the temporary bonding substrate is bonded through the temporary bonding material layer, the bonding layer is formed by bonding the lower end face of the ohmic contact layer, and the permanent lining is formed under the bonding layer by the electron beam evaporation process. The bottom layer, through the secondary bonding technology, realizes that the P electrode is on top and the light is emitted from the P surface. This method not only replaces the substrate to improve the luminous efficiency, but also obtains the traditional electrode structure of the P surface light emission, which is convenient for subsequent circuits. manage. At the same time, the transparent conductive film is made of ITO or Zno or SiO ₂ or TCF material, and its refractive index is conducive to reducing the critical angle of light in packaging materials such as silica gel and epoxy, so the LED chip made by this method will be more powerful than ordinary flip-chip. Increase by about 10%.

Description of drawings

Fig. 1 is the sectional structure diagram of the independent LED chip made by the present invention;

Fig. 2 is the sectional structure diagram of the epitaxial wafer of the present invention;

3 is a schematic cross-sectional structure diagram of the current blocking layer made of the present invention;

4 is a schematic cross-sectional structure diagram of a current spreading layer made of the present invention;

5 is a schematic cross-sectional structure diagram of a temporary bonding substrate made of the present invention;

6 is a schematic diagram of the cross-sectional structure of the present invention after the gallium arsenide substrate is etched;

7 is a schematic cross-sectional structure diagram of the present invention after making a permanent substrate layer;

8 is a schematic cross-sectional structure diagram of the present invention after peeling off the temporary bonding substrate;

9 is a schematic cross-sectional structure diagram of the present invention after cutting to form a scribe line;

10 is a cross-sectional structural diagram of the present invention after the N-face metal layer is made;

In the figure, 1. N-face metal layer 2. Permanent substrate layer 3. Bonding layer 4. N-type AlGaInP layer 5. P-type layer 6. Current spreading layer 7. Current blocking layer 8. P electrode 9. Gallium arsenide lining Bottom 10. N-type buffer layer 11. Temporary bonding material layer 12. Temporary bonding substrate 13. Multiple quantum well layer 14. Ohmic contact layer.

Detailed ways

The present invention will be further described below with reference to Fig. 1 to Fig. 10 .

A method for preparing an AlGaInP quaternary LED chip, comprising the following steps:

a) Prepare the epitaxial wafer structure of LED, the epitaxial wafer structure from bottom to top is gallium arsenide substrate 9, N-type buffer layer 10, N-type AlGaInP layer 4, multiple quantum well layer 13 and P-type layer 5;

b) A layer of SiO ₂ is grown on the P-type layer 5, and N strip-shaped current blocking layers 7 are etched on the SiO ₂ layer by a photolithography process at uniform intervals, and N is a positive integer greater than or equal to 2;

c) prepare a layer of transparent conductive film on the P-type layer 5, the transparent conductive film is used as the current spreading layer 6, and the transparent conductive film is made of ITO or Zno or SiO or TCF material _;

d) Using silica gel material to bond on the current spreading layer 6 and each current blocking layer 7 to form a temporary bonding material layer 11, and on the temporary bonding material layer 11, a temporary bond made of sapphire or silicon wafer or metal material is made bonding substrate 12;

e) Etching the gallium arsenide substrate 9 to the N-type buffer layer 10 with an etching solution;

f) making an ohmic contact layer 14 made of Ni and/or Ge and/or Au on the lower end face of the N-type buffer layer 10;

g) using the electron beam evaporation process to bond the lower end face of the ohmic contact layer 14 to form the bonding layer 3, and using the electron beam evaporation process to make the permanent substrate layer 2 under the bonding layer 3;

h) removing the temporary bonding material layer 11 with a silica gel dissolving agent, so that the temporary bonding substrate 12 is peeled off from the current spreading layer 6;

i) making a P electrode 8 on the current blocking layer 7, and cutting along the vertical direction at the center between each two current blocking layers 7 to form a scribe line, the depth of the scribe line reaching the upper surface of the ohmic contact layer 14;

j) grinding and thinning the permanent substrate layer 2 to the required thickness, and making the N-face metal layer 1 of Ni, Ge or Au on the lower end face of the thinned permanent substrate layer 2;

k) Using laser cutting or grinding wheel cutter to cut along the cutting path to form N independent LED chips.

At present, the reverse polarity AlGaInP quaternary LED chip is widely used in the field of high-power red LED display. The bottom, etc., can improve the light efficiency by more than 20%, but the N pole (light-emitting surface) of the chip completed by this process is on the top, and the P electrode is on the bottom, which is very different from the traditional red light chip. When this kind of red light chip When used together with blue-green chips, there will be a phenomenon that the difficulty of circuit management will increase. In the AlGaInP quaternary LED chip preparation method of the present invention, the temporary bonding substrate 12 is bonded by the temporary bonding material layer 11, and the bonding layer 3 is formed by bonding the lower end face of the ohmic contact layer 14, and the bonding layer 3 is formed by using the electron beam evaporation process. A permanent substrate layer 2 is formed under the bonding layer 3. Through the secondary bonding technology, the P electrode 8 is on top and light is emitted from the P surface. This method not only replaces the substrate, improves the luminous efficiency, but also obtains the P surface. The traditional electrode structure that emits light is convenient for subsequent circuit management. At the same time, the transparent conductive film is made of ITO or Zno or SiO ₂ or TCF material, and its refractive index is conducive to reducing the critical angle of light in packaging materials such as silica gel and epoxy. Therefore, the LED chip made by this method has higher power than ordinary flip-chip Increase by about 10%.

Example 1:

In step b), an electron beam or PECVD process is used to grow a layer of SiO ₂ on the P-type layer 5 , and the thickness of the grown SiO ₂ is 400-1200 Å.

Example 2:

The thickness of the current spreading layer 6 in step c) is 300-1200 Å.

Example 3:

In step d), the bonding temperature when the temporary bonding material layer 11 is formed by bonding is 100-200° C., and the bonding time is 2-4 hours.

Example 4:

In step e), the corrosion solution is a mixed solution of ammonia water, hydrogen peroxide and water, wherein the volume ratio of ammonia water: hydrogen peroxide: water is 1:2:6.

Example 5:

In step f), the ohmic contact layer 14 is prepared on the lower end face of the N-type buffer layer 10 by using the electron beam evaporation process or the sputtering metal material process.

Example 6:

In step g), the bonding layer 3 is made of Au and/or In and/or Ag and/or Al materials, the bonding temperature is 200-250° C., the bonding time is 15-30 min, and the bonding pressure during bonding is 20-50kg.cm ² .

Example 7:

The dissolving temperature of the silica gel dissolving agent in step h) is 100-150°C.

Example 8:

In step j), the permanent substrate layer 2 is ground and thinned to a thickness of 100-180 μm.

Claims (9)

1. A preparation method of an AlGaInP quaternary LED chip is characterized by comprising the following steps:

a) preparing an epitaxial wafer structure of the LED, wherein the epitaxial wafer structure comprises a gallium arsenide substrate (9), an N-type buffer layer (10), an N-type AlGaInP layer (4), a multi-quantum well layer (13) and a P-type layer (5) from bottom to top respectively;

b) growing a layer of SiO on the P-type layer (5)₂By photolithography on SiO₂N strip-shaped current blocking layers (7) are etched on the layer at uniform intervals, wherein N is a positive integer greater than or equal to 2;

c) preparing a transparent conductive film on the P-type layer (5), wherein the transparent conductive film is used as a current expansion layer (6), and the transparent conductive film adopts ITO (indium tin oxide), Zno (zinc oxide) or SiO (silicon oxide)₂Or a TCF material;

d) bonding a silica gel material on the current expansion layer (6) and each current barrier layer (7) to prepare a temporary bonding material layer (11), and preparing a temporary bonding substrate (12) made of sapphire or silicon wafer or metal on the temporary bonding material layer (11);

e) corroding the gallium arsenide substrate (9) to the N-type buffer layer (10) by using a corrosion solution;

f) an ohmic contact layer (14) made of Ni and/or Ge and/or Au is manufactured on the lower end face of the N-type buffer layer (10);

g) bonding the lower end face of the ohmic contact layer (14) by using an electron beam evaporation process to form a bonding layer (3), and forming a permanent substrate layer (2) below the bonding layer (3) by using the electron beam evaporation process;

h) removing the temporary bonding material layer (11) by using a silica gel dissolving agent to peel the temporary bonding substrate (12) from the current spreading layer (6);

i) manufacturing a P electrode (8) on the current blocking layers (7), and cutting a cutting channel in the vertical direction at the center between every two current blocking layers (7), wherein the depth of the cutting channel reaches to the upper surface of the ohmic contact layer (14);

j) grinding and thinning the permanent substrate layer (2) to a required thickness, and manufacturing an N-surface metal layer (1) made of Ni or Ge or Au on the lower end face of the thinned permanent substrate layer (2);

k) and cutting the LED chips along the cutting path by using laser cutting or a grinding wheel cutter to form N independent LED chips.

2. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: growing a layer of SiO on the P-type layer (5) by using an electron beam or PECVD process in the step b)₂Growing SiO₂The thickness of (A) was 400-1200A.

3. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: the thickness of the current spreading layer (6) in step c) is 300-1200A.

4. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: the bonding temperature when the temporary bonding material layer (11) is prepared by bonding in the step d) is 100-200 ℃, and the bonding time is 2-4 hours.

5. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: the corrosive solution in the step e) is a mixed solution of ammonia water, hydrogen peroxide and water, wherein the ammonia water: hydrogen peroxide: the volume ratio of water is 1: 2: 6.

6. the method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: and f), preparing an ohmic contact layer (14) on the lower end face of the N-type buffer layer (10) by using an electron beam evaporation process or a metal material sputtering process.

7. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: in the step g), the bonding layer (3) is made of Au and/or In and/or Ag and/or Al materials, the bonding temperature is 200-250 ℃, the bonding time is 15-30min, and the bonding pressure is 20-50kg.cm during bonding² 。

8. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: the dissolution temperature of the silica gel dissolvent in the step h) is 100-150 ℃.

9. The method of fabricating an AlGaInP quaternary LED chip according to claim 1, wherein: the permanent substrate layer (2) is ground and thinned in the step j) to a thickness of 100-.

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