A method for manufacturing a quad reverse polarity red light tube core N electrode

Abstract

The application provides a preparation method of a four-element reverse polarity red light tube core N electrode, and relates to the field of optoelectronic technology.The method comprises the following steps: firstly, removing the substrate and the barrier layer of a bonded four-element reverse polarity red light LED epitaxial wafer; secondly, evaporating a thin NiGeAu film on the surface as an N-type ohmic contact electrode; thirdly, using the characteristics of the NiGeAu film, annealing at high temperature to make the thin NiGeAu film and the thin GaAs layer fully fused and penetrate into the N-type AlGaInP layer; fourthly, corroding the thin NiGeAu film and the thin GaAs layer by using an Au corrosion liquid at room temperature; fifthly, coating a negative photoresist to form an N electrode pattern without removing the positive photoresist; sixthly, evaporating a thick NiGeAu film and a thick Au film in sequence; seventhly, removing the excess Au film outside the N surface electrode by using a blue film; and finally, obtaining the four-element reverse polarity red light tube core N electrode, thereby avoiding the problem of unstable four-element reverse polarity red light tube core N electrode pattern and improving the quality of the chip.

Description

TECHNICAL FIELD

[0001] The application relates to the field of optoelectronics, in particular to a preparation method of a N electrode of a quaternary reverse polarity red light tube core. BACKGROUND

[0002] The development history of quaternary red light LED chips can be traced back to 1962 when Nick Holonyak of General Electric Company successfully developed the first red light diode. This innovative achievement made Holonyak known as the "father of LED" and was permanently recorded in the history of science. The red light diode was initially applied to indicator lights, display screens and signal lights, and then gradually evolved into the earliest branch of LED technology to achieve application.

[0003] At present, the flip AlGaInP quaternary red light LED chip is widely used in the field of high-power outdoor LED display screens. The so-called flip is to replace the GaAs substrate with high absorption rate with a single-crystal conductive Si substrate or a sapphire substrate on the basis of the traditional quaternary red light LED chip. After completing the substrate replacement, the GaAs substrate is etched and removed, and the etching barrier layer is etched to expose the heavily doped layer. Then, an Au film is evaporated on the heavily doped layer to form an ohmic contact, and then an N-face ohmic contact layer pattern is prepared by a photolithography technology, and an N electrode is prepared. At present, the ohmic contact pattern is mainly prepared by a chemical etching method, but the electrode prepared by the method has poor stability. In view of the high brightness of the quaternary reverse polarity red light tube core, the stability of the N-face ohmic contact pattern is more stringent. Therefore, how to reduce the influence and ensure the stability of the quaternary reverse polarity red light tube core has become the main research topic at present. SUMMARY

[0004] In view of the above problems, the application provides a preparation method of a N electrode of a quaternary reverse polarity red light tube core, which is simple in manufacturing process and can effectively improve the light efficiency and the stability of the electrode.

[0005] The technical scheme adopted by the application to solve the technical problems is:

[0006] A preparation method of a N electrode of a quaternary reverse polarity red light tube core, comprising the following steps,

[0007] S1, a P-type ohmic contact layer and a current blocking layer are prepared on a P-type AlGaInP layer of a reverse polarity AlGaInP quaternary LED epitaxial wafer in sequence, and then the epitaxial wafer is bonded to a new substrate layer to obtain a flip AlGaInP quaternary red light LED epitaxial wafer;

[0008] S2, the GaAs substrate and the blocking layer GaInP of the flip AlGaInP quaternary red light LED epitaxial wafer obtained in step S1 are etched to expose a heavily doped GaAs layer;

[0009] S3, evaporating a thin NiAuGeAu film on the exposed thin GaAs layer;

[0010] S4, high temperature annealing, so that the thin NiAuGeAu film is fully fused with the heavily doped GaAs layer and penetrates into the N-type AlGaInP layer;

[0011] S5, coating a photoresist on the surface of the thin NiAuGeAu film and performing a photoetching to obtain a photoetching pattern;

[0012] S6, etching away the thin NiAuGeAu film, the heavily doped GaAs layer and the NiAuGeAu penetrating into the N-type AlGaInP layer in the etching area of the photoetching pattern, and forming a rough surface on the N-type AlGaInP layer;

[0013] S7, coating a second photoresist on the rough surface and performing a second photoetching;

[0014] S8, evaporating a thick NiAuGeAu film and a thick Au film in sequence and removing the excess thick NiAuGeAu film and thick Au film.

[0015] Further, the new substrate layer is a single-crystal conductive Si substrate or a sapphire substrate.

[0016] Further, the thickness of the thin NiAuGeAu film is 0.0005-0.0010 μm.

[0017] Further, the temperature of the high temperature annealing in step S4 is 520-550 ℃ and the annealing time is 10-15 minutes.

[0018] Further, the Au etching liquid used in step S6 is a mixed solution of iodine, potassium iodide and pure water, and the mass ratio of iodine, potassium iodide and pure water is 2:4:20.

[0019] Further, the etching time in step S6 is 3-4 minutes, and the temperature of the Au etching liquid is 40-50 ℃ when etching.

[0020] Further, the coating thickness of the first photoresist is 1-1.3 μm.

[0021] Further, the coating thickness of the second photoresist is 4-4.5 μm.

[0022] Further, the thickness of the thick NiAuGeAu film is 0.5-0.8 μm.

[0023] Further, the thickness of the thick Au film is 1.5-1.9 μm.

[0024] The present application has the following advantages:

[0025] The application embodiment provides a preparation method of a four-element reverse-polarity red light tube core N electrode. The substrate and the barrier layer of a bonded four-element reverse-polarity red light LED epitaxial wafer are all corroded and removed, and then a thin NiGeAu film is evaporated on the surface as an N-type ohmic contact electrode. Then, by using the characteristics of the NiGeAu film, the thin NiGeAu film and the thin GaAs layer are fully fused and penetrated into the N-type AlGaInP layer through high-temperature annealing, and then the thin NiGeAu film and the thin GaAs layer are corroded away through a normal-temperature Au corrosion liquid, the negative photoresist is coated to form an N electrode pattern without removing the positive photoresist, and then a thick NiGeAu film and a thick Au film are evaporated in sequence, the excess Au film outside the N-face electrode is removed through a blue film, and the four-element reverse-polarity red light tube core N electrode is obtained, thereby avoiding the problem of unstable four-element reverse-polarity red light tube core N electrode pattern and improving the quality of the chip. The method can obtain a more stable N electrode pattern through a conventional way, is simple to operate, can obtain a more stable rough surface, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is a structural schematic diagram of a reverse-polarity AlGaInP four-element LED epitaxial wafer;

[0027] Figure 2 FIG. 2 is a structural schematic diagram of a flip AlGaInP four-element red light LED epitaxial wafer obtained in step S1;

[0028] Figure 3 FIG. 3 is a structural schematic diagram of the flip AlGaInP four-element red light LED epitaxial wafer after the GaAs substrate and the barrier layer GaInP are removed;

[0029] Figure 4 FIG. 4 is a structural schematic diagram after the thin NiAuGeAu film is evaporated in step S3;

[0030] Figure 5 FIG. 5 is a structural schematic diagram after one-time photoetching is performed;

[0031] Figure 6 FIG. 6 is a structural schematic diagram after the thin NiAuGeAu film, the heavily doped GaAs layer and the NiAuGeAu penetrated into the N-type AlGaInP layer in the etching area of the one-time photoetching pattern are corroded;

[0032] Figure 7 FIG. 7 is a structural schematic diagram after the second photoresist is coated on the rough surface;

[0033] Figure 8 FIG. 8 is a structural schematic diagram after two-time photoetching is performed;

[0034] Figure 9 FIG. 9 is a structural schematic diagram of the four-element reverse-polarity red light tube core N electrode obtained in step S8.

[0035] Fig. 11, GaAs substrate; 12, barrier layer GaInP; 13, heavily doped GaAs layer; 14, N-type AlGaInP layer; 141, rough surface; 15, quantum well layer; 16, P-type AlGaInP layer;

[0036] 21, P-type ohmic contact layer; 22, current blocking layer; 23, new substrate layer;

[0037] 31, thin NiAuGeAu film; 32, thick NiAuGeAu film; 33, thick Au film;

[0038] 41, primary photoresist; 42, secondary photoresist. DETAILED DESCRIPTION

[0039] In order to make the person skilled in the art better understand the technical solutions in the present application, the technical solutions in the present application will be described in detail below in combination with the drawings in the present application, and the described embodiments are only some of the embodiments of the present application, but not all the embodiments. All other embodiments obtained by the person skilled in the art without creative labor on the basis of the embodiments of the present application shall belong to the protection scope of the present application.

[0040] Embodiment one

[0041] A preparation method of a quad-quaternary reverse polarity red light tube core N electrode, comprising the following steps:

[0042] S1, a P-type ohmic contact layer 21 and a current blocking layer 22 are prepared on a P-type AlGaInP layer 16 of a reverse polarity AlGaInP quad-quaternary LED epitaxial wafer in sequence, and the P-type ohmic contact layer 21 and the current blocking layer 22 are arranged at intervals, and then bonded to a new substrate layer 23, to obtain an inverted AlGaInP quad-quaternary red light LED epitaxial wafer as shown in Figure 2 The new substrate layer 23 is a single-crystal conductive Si substrate or a sapphire substrate.

[0043] As a specific embodiment, the reverse polarity AlGaInP quad-quaternary LED epitaxial wafer in the present embodiment comprises a GaAs substrate 11, a barrier layer GaInP 12, a heavily doped GaAs layer 13, an N-type AlGaInP layer 14, a quantum well layer 15 and a P-type AlGaInP layer 16 from bottom to top in sequence.

[0044] S2, as shown in Figure 3 The GaAs substrate 11 and the barrier layer GaInP 12 of the inverted AlGaInP quad-quaternary red light LED epitaxial wafer obtained in step S1 are etched away by a conventional etching method, so as to expose the epitaxially grown heavily doped GaAs layer 13.

[0045] S3, as Figure 4 As shown, a thin NiAuGeAu film 31 is deposited on the exposed thin GaAs layer by electron beam evaporation.

[0046] Preferably, the thickness of the thin NiAuGeAu film 31 is 0.0005-0.0010 μm.

[0047] S4, high-temperature annealing, thereby enabling the thin NiAuGeAu film 31 to fully fuse with the heavily doped GaAs layer 13 and penetrate into the N-type AlGaInP layer 14.

[0048] Preferably, the high-temperature annealing temperature in step S4 is 520-550℃, and the annealing time is 10-15 minutes.

[0049] S5, a photoresist 41 is coated on the surface of the thin NiAuGeAu film 31, and a photolithography is performed to obtain the desired result. Figure 5 The image shown is a single photolithography pattern.

[0050] As one specific implementation, the photolithography pattern described in this embodiment includes a rectangular retention area in the middle, with the two opposite sides of the retention area aligned with the edges of the thin NiAuGeAu film 31, and the two sides of the retention area being etched areas.

[0051] S6, such as Figure 6 As shown, the thin NiAuGeAu film 31 in the etched area of ​​the primary photolithography pattern is etched away using Au etchant. Since the thin NiAuGeAu film 31 and the heavily doped GaAs layer 13 have been fully fused together, the heavily doped GaAs layer 13 will be etched away together. The NiAuGeAu that has penetrated into the N-type AlGaInP layer 14 in the etched area of ​​the primary photolithography pattern will also be etched away, thereby forming a rough surface 141.

[0052] In one specific embodiment, the Au etching solution described in this example is a mixed solution of iodine, potassium iodide, and pure water, with a mass ratio of iodine:potassium iodide:pure water = 2:4:20. In step S6, the etching time is 3-4 minutes, and the temperature of the Au etching solution during etching is 40-50℃.

[0053] S7, such as Figure 7 As shown, the roughened surface 141 obtained in step S6 is coated with secondary photoresist 42, and a secondary photolithography is performed to obtain the surface as shown. Figure 8 The secondary lithography pattern shown is such that the projections of the secondary lithography pattern and the primary lithography pattern in the horizontal plane do not completely overlap.

[0054] As a specific embodiment, the first photoresist 41 coated in step S5 is a positive photoresist, and the second photoresist coated in step S7 is a negative photoresist. When performing photoetching, the side of the negative photoresist close to the thin NiAuGeAu film 31 is shielded, and the characteristics that the unexposed area of the negative photoresist is removed and the exposed area of the positive photoresist is removed are used to remove the positive photoresist on the upper side of the thin NiAuGeAu film 31 and the part of the negative photoresist close to the thin NiAuGeAu film 31, and only the part of the negative photoresist away from the thin NiAuGeAu film 31 is reserved, thereby obtaining the second photoetching pattern as shown in Fig. 4, which is prepared for subsequent evaporation of the thick NiAuGeAu film 32 and the thick Au film 33. Figure 8

[0055] As a specific embodiment, the coating thickness of the first photoresist 41 in the embodiment is 1-1.3 μm. The coating thickness of the second photoresist is 4-4.5 μm.

[0056] S8, the thick NiAuGeAu film 32 and the thick Au film 33 are evaporated in sequence, and the thick NiAuGeAu film 32 and the thick Au film 33 evaporated on the residual second photoresist are removed using a blue film, thereby obtaining the quad anti-polarity red light tube core N electrode as shown in Fig. 5. Figure 9

[0057] As a specific embodiment, the thickness M of the thick NiAuGeAu film 32 in the embodiment is 0.5-0.8 μm, and the thickness of the thick Au film 33 is 1.5-1.9 μm.

[0058] Embodiment Two

[0059] The difference between the embodiment and the embodiment one is that:

[0060] The first photoresist 41 coated in step S5 and the second photoresist coated in step S7 are both positive photoresists. When performing photoetching, the side of the negative photoresist away from the thin NiAuGeAu film 31 is shielded, thereby removing the first photoresist 41 on the upper side of the thin NiAuGeAu film 31 and the part of the second photoresist on both sides of the thin NiAuGeAu film 31.

[0061] Embodiment Three

[0062] The difference between the embodiment and the embodiment one is that:

[0063] ​​The photoresist 41 coated in step S5 and the photoresist coated in step S7 are both negative photoresists. When performing photolithography, the photoresist 41 on the upper side of the thin NiAuGeAu film 31 and the photoresist on the both sides of the thin NiAuGeAu film 31 are removed by shielding the upper side of the thin NiAuGeAu film 31 and the both sides of the thin NiAuGeAu film 31.

[0064] Other embodiments obtained by combining, splitting, recombining, etc. of the embodiments provided in the present application by those skilled in the art based on the embodiments provided in the present application do not go beyond the protection scope of the present application.

[0065] The above detailed description of the specific embodiments of the present application has explained the purposes, technical solutions and beneficial effects of the embodiments of the present application. The above is only a specific implementation of the embodiments of the present application and is not used to limit the protection scope of the embodiments of the present application, i.e. any modification, equivalent replacement, improvement, etc. made on the basis of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.

Claims

1. A method for fabricating a quad anti-stigmatic red light N- electrode tube core, the method comprising: It comprises the following steps, ​ S1, a P-type ohmic contact layer (21) and a current blocking layer (22) are prepared on a P-type AlGaInP layer (16) of an anti-polarity AlGaInP quaternary LED epitaxial wafer in sequence, and then the epitaxial wafer is bonded to a new substrate layer (23) to obtain an inverted AlGaInP quaternary red LED epitaxial wafer; S2, the GaAs substrate (11) and the blocking layer GaInP (12) of the inverted AlGaInP quaternary red LED epitaxial wafer obtained in step S1 are etched away to expose the heavily doped GaAs layer (13); S3, a thin NiAuGeAu film (31) is evaporated on the exposed thin GaAs layer; S4, high-temperature annealing is performed to make the thin NiAuGeAu film (31) fully fuse with the heavily doped GaAs layer (13) and penetrate into the N-type AlGaInP layer (14); S5, a photoresist (41) is coated on the surface of the thin NiAuGeAu film (31) once, and a first photoetching is performed to obtain a first photoetching pattern; S6, the thin NiAuGeAu film (31), the heavily doped GaAs layer (13) and the NiAuGeAu penetrating into the N-type AlGaInP layer (14) in the etching area of the first photoetching pattern are etched away to form a rough surface (141) on the N-type AlGaInP layer (14); S7, a second photoresist (42) is coated on the rough surface (141) and a second photoetching is performed; S8, a thick NiAuGeAu film (32) and a thick Au film (33) are evaporated in sequence, and the excess thick NiAuGeAu film (32) and thick Au film (33) are removed.

2. The method of claim 1, wherein the method further comprises: The new substrate layer (23) is a single-crystal conductive Si substrate or a sapphire substrate. ​ 3. The method of claim 1, wherein the method further comprises: The thickness of the thin NiAuGeAu film (31) is 0.0005-0.0010 μm. ​ 4. The method of claim 1, wherein the method further comprises: The temperature of high-temperature annealing in step S4 is 520-550 ℃, and the annealing time is 10-15 minutes. ​ 5. The method of claim 1, wherein the method further comprises: Au etching solution is used for etching in step S6, and the Au etching solution is a mixed solution of iodine, potassium iodide and pure water with a mass ratio of iodine: potassium iodide: pure water = 2:4:

20. ​ 6. The method of claim 5, wherein the method further comprises: In step S6, the etching time is 3-4 minutes, and the temperature of the Au etching solution is 40-50 ℃ when etching. ​ 7. The method of claim 1, wherein the method further comprises: The coating thickness of the first photoresist (41) is 1-1.3 μm. ​ 8. The method of claim 1, wherein the method further comprises: The coating thickness of the second photoresist is 4-4.5 μm. ​ 9. The method of claim 1, wherein the method further comprises: The thickness of the thick NiAuGeAu film (32) is 0.5-0.8 μm. ​ 10. The method of claim 1, wherein the method further comprises: The thickness of the thick Au film (33) is 1.5-1.9 μm. ​

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