Reversed polarity red light emitting LED chip and manufacturing method thereof

Abstract

The invention relates to the technical field of chips, in particular to a reversed-polarity red light emitting LED chip and a manufacturing method thereof. The reversed-polarity red light emitting LED chip comprises a graphite substrate, a graphene bonding layer, an Ag reflector, an AZO conductive thin film layer, an MgF dielectric film layer, a GaP window layer, a P-type semiconductor layer, a light emitting layer, an N-type epitaxial limiting layer, an N-type current expansion layer, a coarsening layer, a passivation layer, a GaAs contact layer and an N electrode from bottom to top. According to the LED chip and the manufacturing method thereof, reasonable design is carried out on the chip manufacturing process, a mirror surface layer, a bonding layer, back gold and other metals do not need to be evaporated for multiple times, the chip manufacturing process is shortened, the use of chip gold can be greatly reduced, and the obtained LED chip is high in brightness, good in reliability, long in service life and low in cost.

Description

Technical Field

[0001] The invention relates to the technical field of chips, and in particular to a reverse polarity red light emitting LED chip and a manufacturing method thereof. Background Art

[0002] Reverse polarity red LED chips are widely used in the fields of plant lighting and outdoor display screens, and have great market prospects. Faced with the increasing market demand and the continuous updating of application scenarios, the reliability requirements for reverse polarity red LED chip products are becoming more and more stringent. The cumbersome manufacturing process is undoubtedly one of the main factors affecting the reliability of LED chips. In addition, in the conventional reverse polarity red LED chip process, precious metals are used as materials for the ohmic contact layer, reflector, bonding layer, etc., which makes the chip cost relatively high and cannot meet the market's cost requirements for reverse polarity red LED chips. Therefore, it is necessary to design a reverse polarity red LED chip with high brightness, reliable and stable performance, and low production cost. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a reverse polarity red light emitting LED chip and a method for manufacturing the same. By rationally designing the chip process, the cost of the reverse polarity red light chip can be greatly reduced, the optical performance, heat dissipation effect, mechanical strength and high temperature resistance can be improved, and the service life of the chip can be extended.

[0004] The present invention provides a method for manufacturing a reverse polarity red light emitting LED chip, comprising the following steps: S1. Provide a GaAs substrate, and sequentially epitaxially grow a GaInP corrosion cutoff layer, an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer, and a GaP window layer; the N-type semiconductor layer sequentially includes: an N-type epitaxial restriction layer, an N-type current spreading layer, a roughening layer, and a GaAs contact layer; S2. Spinning a photoresist on the surface of the GaP window layer, forming a MgF dielectric film pattern, and evaporating the MgF dielectric film; S3. sputtering an AZO conductive film layer on the patterned MgF dielectric film layer by magnetron sputtering; S4. sputtering a Ag reflector on the AZO (aluminum-doped zinc oxide transparent conductive glass) conductive film layer using magnetron sputtering; S5. sputtering a graphene bonding layer on the Ag mirror using magnetron sputtering; S6. Bonding the epitaxial wafer with the sputtered graphene bonding layer to the graphite substrate using a bonding machine; S7. The GaAs substrate of the chip is removed by wet etching to expose the GaInP corrosion stop layer; S8. Etch the exposed GaInP corrosion stop layer through wet etching to expose the GaAs contact layer S9. A patterned GaAs contact layer is produced using a photoresist, and the GaAs contact layer except the patterned one is removed to expose the roughened layer; S10. Spin coating and covering the surface of the GaAs contact layer with a negative photoresist to form an N electrode pattern, and then evaporate metal to form an N electrode; S11. Using photoresist to make a cutting path pattern in the roughened layer of the chip, and etching the cutting path using a dry etching process; S12. Patterning the remaining roughening layer using a photoresist, roughening the patterned roughening layer by wet etching to obtain a roughened surface; S13. depositing a passivation layer on the chip surface by PECVD (plasma enhanced chemical vapor deposition); S14. Thinning the graphite substrate by grinding; S15. Use a blade to cut and separate the chips to obtain single core particles.

[0005] The present invention makes a reasonable design from the chip manufacturing process, and does not need to evaporate mirror layer, bonding layer and back gold and other metals for many times, which not only shortens the chip manufacturing process, but also greatly reduces the use of chip gold and reduces the manufacturing cost; at the same time, AZO is designed as the P-side ohmic contact material, which is both conductive and has the advantages of high transmittance in the visible light range, Ag is used as a reflector to provide an excellent reflection effect, and the combination of graphene and graphite bonding substrate has extremely high thermal conductivity, long life, good mechanical strength and high temperature resistance, so that the obtained LED chip has high brightness, good reliability, long service life and low cost.

[0006] Furthermore, in the above technical solution S2, an optical coating machine is used to evaporate a MgF dielectric film layer with a thickness of 1120±10 angstroms, and then the excess dielectric film layer in the small hole is peeled off to obtain a MgF dielectric film hole with a diameter of 6 μm.

[0007] Furthermore, in the above technical solution S3, the conditions of magnetron sputtering are: power 500 W, 8 sccm of oxygen gas; and the thickness of the AZO conductive film layer is 1500±20 angstroms.

[0008] Furthermore, in the above technical solution S4, the process of sputtering the Ag reflector is: under vacuum conditions, first adjust the power to 450W, and sputter a layer of Ag metal layer with a thickness of 5000±50 angstroms on the AZO conductive film layer, and then adjust the power to 550W, and continue to sputter a layer of TiW alloy layer with a thickness of 1500±20 angstroms.

[0009] Furthermore, in the above technical solution S5, the power of sputtering the graphene bonding layer is 600 W, and the thickness of the graphene bonding layer is 5000±50 angstroms.

[0010] Furthermore, in the above technical solution S6, the bonding conditions are: temperature 500±20°C, pressure 32000±500kgf.

[0011] Furthermore, in the above technical solution S7, the solution for removing the GaAs substrate is a mixed solution of ammonia water and hydrogen peroxide in any proportion; in S8, the solution for removing the GaInP corrosion stop layer is a mixed solution of phosphoric acid and hydrochloric acid in any proportion.

[0012] Furthermore, in the above technical solution S10, the materials of the N electrode are Au, AuGeNi, Au, Pt, and Au in sequence.

[0013] Furthermore, in the above technical solution S11, the manufacturing process of the cutting road pattern is: using a dry etching process, etching the exposed roughened layer down to the GaP window layer, and stopping the etching when the thickness of the GaP window layer is 0.6 μm.

[0014] The present invention also provides a reverse polarity red light emitting LED chip manufactured by the above manufacturing method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention is reasonably designed from the perspective of chip manufacturing process, and a conductive film layer, a mirror layer, graphene and other structures are manufactured by magnetron sputtering, without the need for multiple evaporation processes, so that the performance is more reliable, the use of gold can be greatly reduced, and the cost is reduced; the manufacturing method uses AZO material as the P-face ohmic contact material, which is both conductive and has the advantages of high transmittance in the visible light range, and uses Ag as a reflector to provide an excellent reflection effect, thereby improving the optical performance of the chip; using graphene as a bonding material and graphite as a supporting substrate, the two are combined to achieve extremely high thermal conductivity, longevity, good mechanical strength and high temperature resistance, and finally obtain an LED chip, which not only effectively reduces the use of gold and greatly reduces costs, but also can better improve the optical performance of the chip, improve the heat dissipation effect, mechanical strength and high temperature resistance of the chip itself, and extend the service life of the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the reverse polarity red light emitting LED chip of the present invention; Figure 2 The top view structural diagram of the MgF dielectric film layer of the reverse polarity red light emitting LED chip of the present invention.

[0017] Description of the numbers in the schematic diagram: 1. Graphite substrate; 2. Graphene bonding layer; 3. Ag reflector; 4. AZO conductive film layer; 5. MgF dielectric film layer; 6. GaP window layer; 7. P-type semiconductor layer; 8. Light-emitting layer; 9. N-type epitaxial restriction layer; 10. N-type current spreading layer; 11. Roughening layer; 12. Passivation layer; 13. GaAs contact layer; 14. N electrode; 15. MgF dielectric film hole. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] In the description of the present application, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present application.

[0020] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0021] See also Figure 1 to Figure 2 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the form, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0022] Some embodiments of the present invention provide a method for manufacturing a reverse polarity red light emitting LED chip, comprising the following steps: S1. Providing a GaAs substrate, sequentially epitaxially growing a GaInP etching stop layer, an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer, and a GaP window layer; Specifically, a GaAs substrate is provided as a growth substrate for the reverse polarity red light LED epitaxial wafer structure, and a program is first set on a MOCVD (metal organic chemical vapor deposition) machine, and a GaInP etching stop layer, an N-type semiconductor layer, a light emitting layer 8, a P-type semiconductor layer 7, and a GaP window layer 6 are sequentially grown on the GaAs substrate; wherein the N-type semiconductor layer is sequentially an N-type epitaxial limiting layer 9, an N-type current spreading layer 10, a roughening layer 11, and a GaAs contact layer 13 according to the growth direction of the epitaxial wafer.

[0023] S2. Pattern a photoresist on the surface of the GaP window layer to produce a MgF dielectric film layer pattern, and evaporate the MgF dielectric film layer 5; specifically, use an optical coating machine to evaporate a MgF dielectric film layer with a thickness of 1120±10 angstroms, peel off the excess film layer in the small hole, and obtain a MgF dielectric film hole 15 with a diameter of 6μm.

[0024] S3. Sputter an AZO conductive film layer 4 on the patterned MgF dielectric film layer by magnetron sputtering; specifically, sputter a layer of AZO conductive film layer with a thickness of 1500±20 angstroms on the patterned MgF dielectric film layer by magnetron sputtering at a power of 500W and an oxygen gas of 8sccm.

[0025] S4. Use magnetron sputtering to sputter the Ag reflector 3 on the AZO conductive film layer; specifically, use magnetron sputtering, adjust the power to 450W, and under vacuum conditions, sputter a 5000±50 angstrom thick Ag metal layer on the AZO conductive film layer, and then adjust the power to 550W to sputter a 1500±20 angstrom thick TiW alloy layer.

[0026] S5. Use magnetron sputtering to sputter a graphene bonding layer 2 on the Ag reflective mirror; specifically, adjust the power to 600 W and sputter a graphene bonding layer with a thickness of 5000±50 angstroms on the Ag&TiW metal layer.

[0027] S6. Use a bonding machine to bond the epitaxial wafer with the sputtered graphene bonding layer to the graphite substrate 1; specifically, use a high-temperature and high-pressure bonding machine, set the temperature to 500±20°C and the pressure to 32000±500kgf, and bond the epitaxial wafer with the sputtered graphene bonding layer to the graphite substrate.

[0028] S7. Remove the GaAs substrate of the chip by wet etching to expose the GaInP corrosion stop layer; specifically, the solution used for wet etching is a mixed solution of ammonia water and hydrogen peroxide in any proportion, remove the GaAs substrate of the bonded chip to expose the corrosion stop layer.

[0029] S8. Etch the exposed GaInP corrosion stop layer by wet etching to expose the GaAs contact layer; specifically, the solution used for wet etching in this step is a mixed solution of phosphoric acid and hydrochloric acid in any proportion.

[0030] S9. Use photoresist to make a patterned GaAs contact layer, and remove the GaAs contact layer except the patterned layer to expose the roughened layer; specifically, wet etching is used, and the gallium arsenide etching solution used is a mixed solution of phosphoric acid, hydrogen peroxide and water.

[0031] S10. Spin coating and covering the surface of the GaAs contact layer with a negative photoresist to produce an N electrode pattern, and then vapor-depositing metal to produce an N electrode; specifically, spin coating the surface of the GaAs contact layer with a negative photoresist to produce an N electrode pattern, and then vapor-depositing metal to produce Au, AuGeNi, Au, Pt, and Au metal layers to produce an N electrode 14. After the vapor deposition is completed, use a blue film to peel off excess metal to complete the N electrode production.

[0032] S11. Use photoresist to make a cutting path pattern on the chip roughening layer, and use a dry etching process to etch out the cutting path; specifically, set ICP parameters, use a dry etching process to etch the roughening layer exposed outside down to the etched GaP window layer, and stop etching when the thickness of the GaP window layer remains 0.6μm.

[0033] S12. Patterning the remaining roughening layer using a photoresist, roughening the patterned roughening layer by wet etching to obtain a roughened surface; S13. Deposit a passivation layer 12 on the chip surface by PECVD; specifically, the passivation layer is silicon nitride, the passivation layer is patterned by photoresist, and then wet etching is used to complete the passivation layer manufacturing.

[0034] S14. Thinning the graphite substrate by grinding; S15. Use a blade to cut and separate the chips to obtain single core particles.

[0035] Some specific embodiments of the present invention also provide a reverse polarity red light emitting LED chip, the structural schematic diagram of which is shown in FIG. Figure 1As shown, the reverse polarity red light emitting LED chip includes from bottom to top a graphite substrate 1, a graphene bonding layer 2, an Ag reflector 3, an AZO conductive film layer 4, a MgF dielectric film layer 5, a GaP window layer 6, a P-type semiconductor layer 7, a light emitting layer 8, an N-type epitaxial limiting layer 9, an N-type current spreading layer 10, a roughening layer 11, a passivation layer 12, a GaAs contact layer 13, and an N electrode 14; the GaAs contact layer is completely covered by the N electrode; the passivation layer covers other chip surface areas except the roughening layer and the N electrode; the MgF dielectric film layer has a plurality of MgF dielectric film holes, which are used to make ohmic contact between the AZO conductive film layer and the GaP window layer, and the reliability is good. The schematic diagram of the top view structure of this part is shown as follows Figure 2 shown.

[0036] In summary, the present invention makes a reasonable design from the chip manufacturing process, and does not need multiple evaporation of metals such as mirror layer, bonding layer and back gold. It not only shortens the chip manufacturing process, but also greatly reduces the use of chip gold and reduces the manufacturing cost. The obtained LED chip has high brightness, good reliability, long service life and low cost.

[0037] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for manufacturing a reverse polarity red light emitting LED chip, characterized in that: The following steps are involved: S1. Provide a GaAs substrate, and sequentially epitaxially grow a GaInP corrosion cutoff layer, an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer, and a GaP window layer; the N-type semiconductor layer sequentially includes: an N-type epitaxial restriction layer, an N-type current spreading layer, a roughening layer, and a GaAs contact layer; S2. Spinning a photoresist on the surface of the GaP window layer, forming a MgF dielectric film pattern, and evaporating the MgF dielectric film; S3. sputtering an AZO conductive film layer on the patterned MgF dielectric film layer by magnetron sputtering; S4. sputtering a Ag reflector on the AZO conductive film layer using magnetron sputtering; S5. sputtering a graphene bonding layer on the Ag mirror using magnetron sputtering; S6. Bonding the epitaxial wafer with the sputtered graphene bonding layer to the graphite substrate using a bonding machine; S7. The GaAs substrate of the chip is removed by wet etching to expose the GaInP corrosion stop layer; S8. By wet etching, the exposed GaInP corrosion stop layer is etched to expose the GaAs contact layer; S9. A patterned GaAs contact layer is produced using a photoresist, and the GaAs contact layer except the patterned one is removed to expose the roughened layer; S10. Spin coating and covering the surface of the GaAs contact layer with a negative photoresist to form an N electrode pattern, and then evaporate metal to form an N electrode; S11. Using photoresist to make a cutting path pattern in the roughened layer of the chip, etching the cutting path using a dry etching process; S12. Patterning the remaining roughening layer using a photoresist, roughening the patterned roughening layer by wet etching to obtain a roughened surface; S13. Depositing a passivation layer on the chip surface by PECVD; S14. Thinning the graphite substrate by grinding; S15. Use a blade to cut and separate the chips to obtain single core particles.

2. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S2, an optical coating machine is used to evaporate a MgF dielectric film layer with a thickness of 1120±10 angstroms, and then the excess dielectric film layer in the small hole is peeled off to obtain a MgF dielectric film hole with a diameter of 6 μm.

3. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S3, the magnetron sputtering conditions are: power 500 W, 8 sccm of oxygen gas; the thickness of the AZO conductive film layer is 1500±20 angstroms.

4. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S4, the process of sputtering the Ag reflector is as follows: under vacuum conditions, first adjust the power to 450W, and sputter a layer of Ag metal layer with a thickness of 5000±50 angstroms on the AZO conductive film layer, then adjust the power to 550W, and continue to sputter a layer of TiW alloy layer with a thickness of 1500±20 angstroms.

5. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S5, the power of sputtering the graphene bonding layer is 600 W, and the thickness of the graphene bonding layer is 5000±50 angstroms.

6. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S6, the bonding conditions are: temperature 500±20°C, pressure 32000±500kgf.

7. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S7, the solution for removing the GaAs substrate is a mixed solution of ammonia water and hydrogen peroxide in any proportion; in S8, the solution for removing the GaInP corrosion stop layer is a mixed solution of phosphoric acid and hydrochloric acid in any proportion.

8. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S10, the materials of the N electrode are Au, AuGeNi, Au, Pt, and Au in sequence.

9. The method for manufacturing a reverse polarity red light emitting LED chip according to claim 1, characterized in that: In S11, the manufacturing process of the cutting road pattern is: using a dry etching process, etching the exposed roughening layer down to the GaP window layer, and stopping the etching when the thickness of the GaP window layer is 0.6 μm.

10. A reverse polarity red light emitting LED chip manufactured by the manufacturing method according to any one of claims 1 to 9.

Images