Preparation method of highlight reverse polarity AlGaInP light emitting diode

Abstract

The application relates to a preparation method of a high-brightness reverse-polarity AlGaInP light-emitting diode. The preparation method first makes a first mask and a second mask before ICP etching, so that only one etching is needed in the process of forming a cutting path by ICP etching, but the effect of twice etching in the prior art is achieved, the preparation process is simplified, the preparation method only needs 10-14 hours, compared with the period of 20-25 hours of the prior preparation method, the production efficiency is greatly improved, and meanwhile, the product qualified rate reaches more than 95% because multiple photoetching and etching are not needed.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a high-brightness reverse-polarity AlGaInP light-emitting diode and belongs to the optical electronic technical field. BACKGROUND

[0002] As one of the most valued light source technologies, an LED has the characteristics of small volume, low current and low voltage driving, power saving, firm structure, strong impact resistance and shock resistance, super-long service life and many other advantages. Quaternary AIGaInP is a kind of semiconductor material with a direct wide band gap, which has been widely used in the preparation of various optoelectronic devices. Since the light-emitting wavelength band of AIGaInP material can cover the red light to yellow-green light band of visible light, the visible light-emitting diode made of the AIGaInP material has been widely concerned.

[0003] For the quaternary AlGaInP reverse-polarity light-emitting diode, a roughening process is widely used to improve the brightness. In addition, a secondary etching process is performed on the cutting channel to change the side light emission, which is a main method to improve the brightness. The secondary etching process is first etched to the GaP ohmic contact layer, and then etched to the reflector, so that two times of mask photolithography and two times of etching process are required, especially the second time of mask photolithography, which needs to be operated in a deep groove, and the process is complex, the production cycle is long, and the product qualified rate is low. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a preparation method of a high-brightness reverse-polarity AlGaInP light-emitting diode. The preparation method uses two kinds of materials with different etching ratios as masks, adjusts the etching parameters, and realizes the effect of twice etching by once etching. The method is easy to operate, the process is simple, and the product qualified rate is high.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of a high-brightness reverse-polarity AlGaInP light-emitting diode, the high-brightness reverse-polarity AlGaInP light-emitting diode comprises, from bottom to top, a permanent substrate ohmic contact electrode, a permanent substrate, a reflector, a dielectric film and a P-type ohmic contact layer, a P-GaP ohmic contact layer, a P-AlGaInP current expansion layer, a P-AlInP limiting layer, an MQW multi-quantum well layer, an N-AlInP limiting layer, an N-AlGaInP current expansion layer, an N-AlGaInP roughening layer, an N-GaAs ohmic contact layer and an N-face electrode, and comprises the following steps:

[0007] (1) using MOCVD method, growing N-GaAs buffer layer, N-GaInP barrier layer, N-GaAs ohmic contact layer, N-AlGaInP roughening layer, N-AlGaInP current spreading layer, N-AlInP confinement layer, MQW multi-quantum well layer, P-AlInP confinement layer, P-AlGaInP current spreading layer and P-GaP ohmic contact layer on n-GaAs temporary substrate in sequence;

[0008] (2) evaporating dielectric film on the epitaxial wafer of step (1), and then forming P-type ohmic contact layer by photoetch, evaporation, etching, stripping and other processes;

[0009] (3) evaporating mirror on the surface of the wafer obtained in step (2);

[0010] (4) bonding the wafer of step (3) with permanent substrate;

[0011] (5) removing n-GaAs temporary substrate and N-GaInP barrier layer of the wafer after bonding;

[0012] (6) etching N-GaAs ohmic contact layer in the area other than electrode, and then performing roughening treatment;

[0013] (7) evaporating N-face electrode on the N-GaAs ohmic contact layer reserved in step (6), and forming ohmic contact by alloying process;

[0014] (8) evaporating first mask on the surface of the wafer of step (7), and removing photoresist after obtaining regular pattern by photoetch process;

[0015] (9) making second mask on the first mask by photoetch process;

[0016] (10) forming cutting path by ICP etching, and then removing second mask and first mask in sequence;

[0017] (11) thinning permanent substrate, and then evaporating ohmic contact metal and alloying to form permanent substrate ohmic contact electrode;

[0018] (12) obtaining light emitting diode by laser scribing and diamond cutting.

[0019] According to the application, preferably, in step (2), the dielectric film is SiO2, MgF2 or Al2O3, and the N-GaAs ohmic contact layer is Au / AuBe / Au or Au / AuZn / Au.

[0020] According to the application, preferably, in step (3), the mirror is gold mirror or silver mirror.

[0021] According to the application, preferably, in step (4), the bonding method is Au-Au bonding or Au-In bonding, the bonding temperature is 200-350 DEG C, the pressure is 200-500 kg, and the time is 30-50 min.

[0022] According to the application, preferably, in step (5), the n-GaAs temporary substrate of the wafer after bonding is removed by using a mixed solution of ammonia, hydrogen peroxide and water, and the volume ratio of the ammonia, hydrogen peroxide and water in the mixed solution is 1:4:5.

[0023] According to the application, preferably, in step (5), the N-GaInP blocking layer is removed by using a mixed solution of hydrochloric acid and water, and the volume ratio of the hydrochloric acid and water in the mixed solution is 3:2.

[0024] According to the application, preferably, in step (8), the regular pattern includes any one of plane geometric patterns, and the plane geometric patterns include a circle, an ellipse, a triangle, a rectangle and a square.

[0025] According to the application, preferably, in step (8), the first mask is SiO2, SiNx or Ti, and the thickness is 3000-15000 angstroms. The thickness can be adjusted according to the specific ICP etching condition.

[0026] According to the application, preferably, in step (9), the second mask is photoresist, and the thickness is >3 micrometers.

[0027] According to the application, preferably, in step (10), in the process of forming the cutting path by ICP etching, the etching depth of the first mask is greater than the thickness of the P-GaP ohmic contact layer by 0.2-0.4 micrometers. The ICP etching parameters are adjusted so that the first mask is etched to the required depth and is completely etched off.

[0028] In the above technical solution, the parts not described in detail and limited are referred to the prior art of manufacturing light emitting diodes.

[0029] Beneficial effects:

[0030] The application first makes the first mask and the second mask before ICP etching, so that only one etching is needed in the process of forming the cutting path by ICP etching, but the effect of twice etching in the prior art is achieved, the preparation process is simplified, the preparation period of the application is only 10-14 hours compared with 20-25 hours of the prior art, the production efficiency is greatly improved, and the product qualification rate reaches more than 95% due to no need of multiple photoetching and etching. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structure schematic diagram of the application.

[0032] Figure 2 Figure 1 is a schematic diagram of the structure of the first mask and the second mask of the high-brightness reverse-polarity AlGaInP light-emitting diode according to the present application.

[0033] In the figure, 1 is a permanent substrate ohmic contact electrode, 2 is a permanent substrate, 3 is a mirror, 4 is a dielectric film, 5 is a P-type ohmic contact layer, 6 is a P-GaP ohmic contact layer, 7 is a P-AlGaInP current expansion layer, 8 is a P-AlInP confinement layer, 9 is an MQW, multi-quantum well layer, 10 is an N-AlInP confinement layer, 11 is an N-AlGaInP current expansion layer, 12 is an N-AlGaInP coarsening layer, 13 is an N-GaAs ohmic contact layer, 14 is an N-face electrode, 15 is a first mask, and 16 is a second mask. DETAILED DESCRIPTION

[0034] The present application is further described below in conjunction with examples and the accompanying drawings of the specification, but is not limited thereto.

[0035] Example 1

[0036] A preparation method of a high-brightness reverse-polarity AlGaInP light-emitting diode, as shown in the figure, comprises the following steps: Figure 1 The high-brightness reverse-polarity AlGaInP light-emitting diode comprises, from bottom to top, a permanent substrate ohmic contact electrode 1, a permanent substrate 2, a mirror 3, a dielectric film 4, and a P-type ohmic contact layer 5, a P-GaP ohmic contact layer 6, a P-AlGaInP current expansion layer 7, a P-AlInP confinement layer 8, an MQW multi-quantum well layer 9, an N-AlInP confinement layer 10, an N-AlGaInP current expansion layer 11, an N-AlGaInP coarsening layer 12, an N-GaAs ohmic contact layer 13, and an N-face electrode 14.

[0037] (1) A N-GaAs buffer layer, a N-GaInP barrier layer, a N-GaAs ohmic contact layer, a N-AlGaInP coarsening layer, a N-AlGaInP current expansion layer, a N-AlInP confinement layer, an MQW multi-quantum well layer, a P-AlInP confinement layer, a P-AlGaInP current expansion layer, and a P-GaP ohmic contact layer are sequentially grown on an n-GaAs temporary substrate by using a MOCVD method;

[0038] (2) A layer of SiO2 dielectric film 4 with a thickness of 3000 angstroms is evaporated on the P-GaP ohmic contact layer 6 by using a PECVD, and then an ohmic contact layer 5 is formed by evaporation and peeling after etching by photolithography;

[0039] (3) A gold mirror 3 is evaporated on the surface of the wafer obtained in step (2);

[0040] (4) Au-Au bonding of the wafer of step (3) with a permanent silicon substrate, temperature 300°C, time 45 minutes, pressure 400kg;

[0041] (5) removing the n-GaAs temporary substrate and N-GaInP barrier layer of the bonded wafer; using a mixed solution of ammonia, hydrogen peroxide and water to remove the n-GaAs temporary substrate of the bonded wafer, the volume ratio of the mixed solution of ammonia, hydrogen peroxide and water being 1:4:5; using a mixed solution of hydrochloric acid and water to remove the N-GaInP barrier layer, the volume ratio of the mixed solution of hydrochloric acid and water being 3:2, to expose the N-GaAs ohmic contact layer 13;

[0042] (6) etching away the N-GaAs ohmic contact layer in the area other than the electrode, and then performing roughening treatment;

[0043] (7) evaporating N-face electrode 14 on the N-GaAs ohmic contact layer 13 reserved in step (6), and forming ohmic contact through alloying process; that is, evaporating AuGeNiPtAu electrode 14 on the N-GaAs ohmic contact layer 13 reserved in step (7), and alloying at 380°C for 10 minutes to form ohmic contact;

[0044] (8) evaporating SiO2 first mask 15 on the surface of the wafer of step (7), with a thickness of 8000 angstroms, and then removing photoresist after obtaining square through photoetching and etching processes;

[0045] (9) making photoresist second mask 16 on the first mask through photoetching process, with a thickness of 6μm;

[0046] (10) using ICP etching to form a cutting path, adjusting ICP etching parameters as follows: RF power 400W, ICP power 700W, pressure 6mT, temperature 20°C, chlorine 60sccm, boron trichloride 20sccm, so that the etching depth reaches 1.8μm, the first mask SiO2 is etched away, and the etching continues until the medium film 4 is etched, and then the second mask is removed, and then the first mask is removed;

[0047] (10) thinning the permanent substrate 2 to 160μm, and evaporating ohmic contact metal TiAu, and alloying at 200°C for 10 minutes to form permanent substrate ohmic contact electrode 1;

[0048] (11) obtaining a light emitting diode by laser scribing and diamond knife cutting.

[0049] The structure of the high-brightness reverse polarity AlGaInP light emitting diode after the first mask and the second mask are made is shown in FIG. 1. Figure 2

[0050] ​The preparation period of the high-brightness reverse polarity AlGaInP light emitting diode in this embodiment is 14 hours, and the product qualified rate is 96%.

[0051] Embodiment 2

[0052] According to the preparation method of the high-brightness reverse polarity AlGaInP light emitting diode in Embodiment 1, the difference lies in that:

[0053] In step (8), after the required pattern is obtained by the photoetching and etching process, no glue operation is performed, and the photoresist is reserved.

[0054] In step (9), the reserved photoresist in step (8) is directly subjected to secondary photoetching operation to obtain the required pattern.

[0055] The preparation period of the high-brightness reverse polarity AlGaInP light emitting diode in this embodiment is 12 hours, and the product qualified rate is 96%.

[0056] Compared with Embodiment 1, only one glue removal operation is required in this embodiment, which further improves the efficiency and reduces the cost.

[0057] Embodiment 3

[0058] According to the preparation method of the high-brightness reverse polarity AlGaInP light emitting diode in Embodiment 1, the difference lies in that:

[0059] In step (8), the first mask is a Ti first mask, and the thickness is 6000 angstroms.

[0060] In step (9), the thickness of the second photoresist mask is 5.5 μm.

[0061] In step (10), ICP etching is used to form a cutting path, and the ICP etching parameters are adjusted to be first segment RF power 600 W, ICP power 600 W, pressure 6 mT, temperature 20℃, chlorine 60 sccm, argon 30 sccm, second segment RF power 400 W, ICP power 700 W, pressure 6 mT, temperature 20℃, chlorine 60 sccm, boron trichloride 20 sccm, so that when the etching depth reaches 1.8 μm, the first mask SiO2 is etched completely, and the etching continues until the medium film 4 is etched, and then the mask is removed.

[0062] The preparation period of the high-brightness reverse polarity AlGaInP light emitting diode in this embodiment is 13 hours, and the product qualified rate is 96%.

Claims

1. A method for fabricating a high-brightness reverse-polarity AlGaInP light-emitting diode, wherein the high-brightness reverse-polarity AlGaInP light-emitting diode comprises, from bottom to top, a permanent substrate ohmic contact electrode, a permanent substrate, a mirror, a dielectric film, a P-type ohmic contact layer, a P-GaP ohmic contact layer, a P-AlGaInP current spreading layer, a P-AlInP confinement layer, an MQW multiple quantum well layer, an N-AlInP confinement layer, an N-AlGaInP current spreading layer, an N-AlGaInP roughening layer, an N-GaAs ohmic contact layer, and an N-face electrode, characterized in that, The steps include the following: (1) Using the MOCVD method, N-GaAs buffer layer, N-GaInP barrier layer, N-GaAs ohmic contact layer, N-AlGaInP roughening layer, N-AlGaInP current spreading layer, N-AlInP confinement layer, MQW multiple quantum well layer, P-AlInP confinement layer, P-AlGaInP current spreading layer and P-GaP ohmic contact layer are sequentially grown on n-GaAs temporary substrate; (2) A dielectric film is deposited on the epitaxial wafer in step (1), and then a P-type ohmic contact layer is formed by photolithography, evaporation, etching and stripping processes; (3) A reflective mirror is deposited on the surface of the wafer obtained in step (2); (4) Bond the wafer from step (3) to the permanent substrate; (5) Remove the n-GaAs temporary substrate and N-GaInP barrier layer from the bonded wafer; (6) Etch away the N-GaAs ohmic contact layer outside the electrode area, and then perform roughening treatment; (7) An N-face electrode is deposited on the N-GaAs ohmic contact layer retained in step (6), and an ohmic contact is formed by an alloying process; (8) A first mask is deposited on the surface of the wafer described in step (7), and the resist is removed after obtaining a regular pattern by photolithography. The first mask is one of SiO2, SiNx or Ti, and has a thickness of 3000~15000 angstroms; (9) Fabricate a second mask on the first mask using photolithography; The second mask is a photoresist with a thickness of >3μm; (10) Use ICP etching to form the cutting path, then remove the second mask first, and then remove the first mask; The parameters for the ICP etching are: RF power 400W, ICP power 700W, pressure 6mT, temperature 20℃, chlorine gas 60sccm, and boron trichloride 20sccm. During the formation of the dicing channel, the etching depth of the first mask is 0.2~0.4μm greater than the thickness of the P-GaP ohmic contact layer. (11) Thin the permanent substrate, then deposit ohmic contact metal and alloy it to form a permanent substrate ohmic contact electrode; (12) Light-emitting diodes are obtained by laser scribing and diamond cutting.

2. The method for preparing a high-brightness reverse-polarity AlGaInP light-emitting diode as described in claim 1, characterized in that, In step (2), the dielectric film is SiO2, MgF2 or Al2O3, and the N-GaAs ohmic contact layer is Au / AuBe / Au or Au / AuZn / Au.

3. The method for preparing a high-brightness reverse-polarity AlGaInP light-emitting diode as described in claim 1, characterized in that, In step (3), the reflector is a gold mirror or a silver mirror.

4. The method for fabricating a high-brightness reverse-polarity AlGaInP light-emitting diode as described in claim 1, characterized in that, In step (4), the bonding method is Au-Au bonding or Au-In bonding, the bonding temperature is 200~350℃, the pressure is 200~500kg, and the time is 30~50min.

5. The method for fabricating a high-brightness reverse-polarity AlGaInP light-emitting diode as described in claim 1, characterized in that, In step (5), a mixed solution of ammonia, hydrogen peroxide and water is used to remove the n-GaAs temporary substrate of the bonded wafer. The volume ratio of ammonia, hydrogen peroxide and water in the mixed solution is 1:4:

5.

6. The method for fabricating a high-brightness reverse-polarity AlGaInP light-emitting diode as described in claim 1, characterized in that, In step (5), a mixed solution of hydrochloric acid and water is used to remove the N-GaInP barrier layer. The volume ratio of hydrochloric acid to water in the mixed solution is 3:

2.

7. The method for fabricating a high-brightness reverse-polarity AlGaInP light-emitting diode as described in claim 1, characterized in that, In step (8), the regular graphic includes any kind of planar geometric figure, including circle, ellipse, triangle, rectangle and square.

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