A reverse polarity LED structure and manufacturing method thereof

Abstract

The present application discloses a reverse polarity LED structure and a method for manufacturing the same. Photolithography is performed on a P-GaP window layer of a reverse polarity epitaxial wafer, a highly doped P-GaP window layer is partially etched by a dry or wet etching process to form a patterned P-GaP window layer, and then the entire surface is coated to form an oxidized structure. Without affecting the voltage, the external quantum efficiency is improved, the current expansion is better, and the voltage is reduced.

Description

Technical Field

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

[0002] As a new lighting source in the 21st century, LED consumes only 1 / 10 of the power of ordinary incandescent lamps at the same brightness, but its life span can be extended by 100 times. LED devices are cold light sources with high light efficiency, low operating voltage, low power consumption, small size, flat packaging, easy development of thin and light products, strong structure and long life. In addition, the light source itself does not contain harmful substances such as mercury and lead, no infrared and ultraviolet pollution, and will not pollute the outside world during production and use. Therefore, semiconductor lamps have the characteristics of energy saving, environmental protection, and long life. Just like transistors replacing electron tubes, semiconductor lamps will replace traditional incandescent lamps and fluorescent lamps, which 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 lighting source has great potential to replace traditional lighting sources.

[0003] Currently, the P-face GaP LED chips in the industry are all full-surface structures without graphics, and the P-face GaP high-doping layer absorbs light, resulting in low brightness. Summary of the invention

[0004] In view of this, the present invention provides a reverse polarity LED structure and a method for manufacturing the same, by manufacturing a patterned P-GaP window layer on a reverse polarity epitaxial wafer, the external quantum efficiency is improved, the current expansion is better, and the voltage is reduced without affecting the voltage.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for manufacturing a reverse polarity LED structure, the manufacturing method comprising:

[0007] Providing a GaAs substrate;

[0008] A GaAs buffer layer, an etching stop layer, a GaAs ohmic contact layer, an N-type roughening layer, an N-type confinement layer, an MQW quantum well active layer, a P-type confinement layer, and a P-GaP window layer are sequentially grown on a surface of one side of the GaAs substrate to form an epitaxial wafer of the reverse polarity LED structure; wherein the side of the P-GaP window layer away from the P-type confinement layer is a highly doped P-GaP window layer;

[0009] Etching the highly doped P-GaP window layer portion by using photolithography technology to form a patterned P-GaP window layer;

[0010] An oxidation structure is formed on a surface of the patterned P-GaP window layer on a side away from the GaAs substrate, wherein the oxidation structure comprises a first oxidation layer, a second oxidation layer and a third oxidation layer, wherein the second oxidation layer is located between the first oxidation layer and the third oxidation layer;

[0011] Etching the oxide structure by photolithography to form a plurality of dielectric holes penetrating the oxide structure, and filling the dielectric holes with dielectric material to form a bonding metal structure;

[0012] forming a metal mirror layer on a surface of the oxide structure facing away from the epitaxial wafer, wherein the metal mirror layer is metal-bonded to the bonding metal structure;

[0013] Performing substrate transfer, removing the GaAs substrate, and forming an N electrode on a surface of the epitaxial wafer facing away from the oxidation structure, and forming a roughened structure on both sides of the N electrode;

[0014] Forming a Si substrate on a surface of the metal mirror layer facing away from the oxidation structure;

[0015] A P electrode is formed on a surface of the Si substrate facing away from the metal mirror layer.

[0016] Preferably, in the above-mentioned manufacturing method, the doping concentration of the highly doped P-GaP window layer is 2×10 18 cm -3 .

[0017] Preferably, in the above-mentioned manufacturing method, the first oxide layer is an ITO layer, an IZO layer or an Al2O3 layer.

[0018] Preferably, in the above-mentioned manufacturing method, the second oxide layer is a SiO2 layer.

[0019] Preferably, in the above-mentioned manufacturing method, the third oxide layer is an Al2O3 layer or an ITO layer or an IZO layer.

[0020] Preferably, in the above-mentioned manufacturing method, the bonding metal structure is an AuZnAu layer or an AuBeAu layer.

[0021] Preferably, in the above-mentioned manufacturing method, the method of etching the highly doped P-GaP window layer portion comprises:

[0022] Forming a first photoresist layer on a surface of the highly doped P-GaP window layer that is away from the P-type confinement layer;

[0023] Using a photolithography process, etching the first photoresist layer to form a patterned first photoresist layer;

[0024] Based on the patterned first photoresist layer, etching the highly doped P-GaP window layer portion to form a patterned P-GaP window layer;

[0025] The remaining first photoresist layer is removed.

[0026] Preferably, in the above-mentioned manufacturing method, the method of forming the oxidation structure comprises:

[0027] forming a first oxide layer on a surface of the patterned P-GaP window layer facing away from the P-type confinement layer;

[0028] forming a second oxide layer on a surface of the first oxide layer facing away from the patterned P-GaP window layer;

[0029] A third oxide layer is formed on a surface of the second oxide layer on a side facing away from the first oxide layer.

[0030] Preferably, in the above-mentioned manufacturing method, the method for forming the bonding metal structure includes:

[0031] forming a second photoresist layer on a surface of the third oxide layer facing away from the second oxide layer;

[0032] Using a photolithography process, etching the second photoresist layer to form a patterned second photoresist layer;

[0033] Based on the patterned second photoresist layer, etching the oxide structure to remove part of the first oxide layer, part of the second oxide layer and part of the third oxide layer to form a plurality of dielectric holes penetrating the oxide structure;

[0034] Filling the dielectric material in the dielectric hole to form a bonding metal structure;

[0035] The remaining second photoresist layer is removed.

[0036] The present invention also provides a reverse polarity LED structure, the reverse polarity LED structure comprising:

[0037] An epitaxial wafer, the epitaxial wafer comprising a GaAs buffer layer, an etching stop layer, a GaAs ohmic contact layer, an N-type roughening layer, an N-type confinement layer, an MQW quantum well active layer, a P-type confinement layer and a patterned P-GaP window layer grown in sequence on the same side; wherein the side of the patterned P-GaP window layer away from the P-type confinement layer is a highly doped P-GaP window layer;

[0038] An oxidation structure located on a surface of the patterned P-GaP window layer facing away from the P-type confinement layer, the oxidation structure comprising a first oxidation layer, a second oxidation layer and a third oxidation layer, wherein the second oxidation layer is located between the first oxidation layer and the third oxidation layer;

[0039] a plurality of bonded metal structures disposed in the oxide structure;

[0040] A metal mirror layer located on a surface of the oxidation structure facing away from the epitaxial wafer, wherein the metal mirror layer is metal-bonded to the bonding metal structure;

[0041] An N-electrode located on a surface of the epitaxial wafer facing away from the oxidized structure, and roughened structures located on both sides of the N-electrode;

[0042] A Si substrate located on a surface of the metal mirror layer facing away from the oxidation structure;

[0043] A P electrode is located on the surface of the Si substrate facing away from the metal mirror layer.

[0044] From the above description, it can be seen that in the reverse polarity LED structure and its manufacturing method provided by the technical solution of the present invention, by performing photolithography on the P-GaP window layer of the reverse polarity epitaxial wafer, etching the highly doped P-GaP window layer portion by a dry or wet etching process to form a patterned P-GaP window layer, and then coating the entire surface to form an oxide structure, the external quantum efficiency is improved without affecting the voltage, the current expansion is better, and the voltage is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0046] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

[0047] Figure 1-Figure 16 A process flow chart of a method for manufacturing a reverse polarity LED structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0049] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0050] refer to Figure 1-Figure 16 , Figure 1-Figure 16 A process flow chart of a method for manufacturing a reverse polarity LED structure provided by an embodiment of the present invention, such as Figure 1-Figure 16 As shown, the manufacturing method comprises:

[0051] Step S1: Figure 1 As shown, a GaAs substrate 10 is provided;

[0052] Step S2: Figure 2 As shown, a GaAs buffer layer 111, an etching stop layer 112, a GaAs ohmic contact layer 113, an N-type roughening layer 114, an N-type confinement layer 115, an MQW quantum well active layer 116, a P-type confinement layer 117, and a P-GaP window layer 118 are sequentially grown on a surface of one side of the GaAs substrate 10 by MOCVD (metal organic chemical vapor deposition) to form the epitaxial wafer 11 of the reverse polarity LED structure; wherein the side of the P-GaP window layer 118 away from the P-type confinement layer 117 is a highly doped P-GaP window layer 121;

[0053] The doping concentration of the highly doped P-GaP window layer 121 may be 2×10 18 cm -3 .

[0054] Step S3: Figure 3-Figure 5 As shown, the highly doped P-GaP window layer 121 is partially etched using photolithography technology to form a patterned P-GaP window layer 118;

[0055] The method for etching part of the highly doped P-GaP window layer 121 includes:

[0056] First, if Figure 3 As shown, a first photoresist layer 13 is formed on a surface of the highly doped P-GaP window layer 121 on one side away from the P-type confinement layer 117;

[0057] Then, if Figure 4 As shown, the first photoresist layer 13 is etched by a photolithography process to form a patterned first photoresist layer 13;

[0058] Finally, if Figure 5 As shown, based on the patterned first photoresist layer 13 , the highly doped P-GaP window layer 121 is partially etched to form a patterned P-GaP window layer 118 , and the remaining first photoresist layer 13 is removed.

[0059] In an embodiment of the present invention, the surface of the epitaxial wafer 11 can be cleaned by acetone, isopropyl alcohol, deionized water, etc., and then photolithography is performed on the surface of the P-GaP window layer 118, and the highly doped P-GaP window layer 121 on the surface is removed by dry or wet etching, and the photoresist is removed after etching.

[0060] Step S4: Figure 6-Figure 8 As shown, an oxidation structure 14 is formed on a surface of the patterned P-GaP window layer 118 facing away from the GaAs substrate 10, and the oxidation structure 14 includes a first oxide layer 141, a second oxide layer 142 and a third oxide layer 143, and the second oxide layer 142 is located between the first oxide layer 141 and the third oxide layer 143;

[0061] The method for forming the oxidation structure 14 includes:

[0062] First, if Figure 6 As shown, a first oxide layer 141 is formed on the surface of the patterned P-GaP window layer 118 which is away from the P-type confinement layer 117 ; the first oxide layer 141 may be an ITO layer, an IZO layer, or an Al 2 O 3 layer.

[0063] Then, if Figure 7 As shown, a second oxide layer 142 is formed on a surface of the first oxide layer 141 that is away from the patterned P-GaP window layer 118 ; the second oxide layer 142 may be a SiO 2 layer.

[0064] Finally, if Figure 8 As shown, a third oxide layer 143 is formed on a surface of the second oxide layer 142 that is away from the first oxide layer 141. The third oxide layer 143 may be an Al2O3 layer, an ITO layer, or an IZO layer.

[0065] Step S5: Figure 9-12As shown, the oxide structure 14 is etched by photolithography technology to form a plurality of dielectric holes 16 penetrating the oxide structure 14, and dielectric material is filled in the dielectric holes 16 to form a bonding metal structure 17; the bonding metal structure 17 can be an AuZnAu layer or an AuBeAu layer.

[0066] The method for forming the bonding metal structure 17 includes:

[0067] First, if Fig. 9 As shown, a second photoresist layer 15 is formed on a surface of the third oxide layer 143 facing away from the second oxide layer 142;

[0068] Then, if Fig.10 As shown, the second photoresist layer 15 is etched by a photolithography process to form a patterned second photoresist layer 15;

[0069] Then, if Fig.11 As shown, based on the patterned second photoresist layer 15, the oxide structure 14 is etched to remove part of the first oxide layer 141, part of the second oxide layer 142 and part of the third oxide layer 143, so as to form a plurality of dielectric holes 16 penetrating the oxide structure 14;

[0070] Finally, if Fig.12 As shown, a dielectric material is filled in the dielectric hole 16 to form a bonding metal structure 17, and the remaining second photoresist layer 15 is removed.

[0071] Step S6: Fig.13 As shown, a metal mirror layer 18 is formed on a surface of the oxide structure 14 facing away from the epitaxial wafer 11, and the metal mirror layer 18 is metal-bonded to the bonding metal structure 17;

[0072] The material of the metal mirror layer 18 may be any one or more combinations of Ag, TiW, Ti, Pt and Au.

[0073] Step S7: Fig.14 As shown, substrate transfer is performed, the GaAs substrate 10 is removed, and an N electrode 19 is formed on the surface of the epitaxial wafer 11 on one side away from the oxide structure 14, and a roughened structure 20 is formed on both sides of the N electrode;

[0074] Step S8: Fig.15 As shown, a Si substrate 21 is formed on a surface of the metal mirror layer 18 facing away from the oxidation structure 14;

[0075] Step S9: Fig.16As shown, a P electrode 22 is formed on a surface of the Si substrate 21 which is away from the metal mirror layer 18 .

[0076] In the embodiment of the present invention, Al2O3 / ITO / IZO is plated after the P-GaP window layer 118 is patterned, which can make the current expansion better, reduce the voltage, and improve the reliability and brightness. In addition, Al2O3 / ITO / IZO plays a role in increasing the adhesion of SiO2 and the Ag mirror. The refractive index of GaP (~3.3), the refractive index of SiO2 (~1.4), and the refractive index of Al2O3 / ITO / IZO (~1.8), and Al2O3 / ITO / IZO is plated between GaP and SiO2, which is conducive to improving the external quantum efficiency and brightness.

[0077] From the above description, it can be seen that in the method for manufacturing the reverse polarity LED structure provided by the technical solution of the present invention, by performing photolithography on the P-GaP window layer of the reverse polarity epitaxial wafer, etching the highly doped P-GaP window layer portion by a dry or wet etching process to form a patterned P-GaP window layer, and then coating the entire surface to form an oxide structure, the external quantum efficiency is improved without affecting the voltage, the current expansion is better, and the voltage is reduced.

[0078] Based on the above embodiment, another embodiment of the present invention further includes a reverse polarity LED structure, wherein the reverse polarity LED structure is prepared by the above manufacturing method, such as Fig.16 As shown, the reverse polarity LED structure includes:

[0079] An epitaxial wafer 11, the epitaxial wafer 11 comprises a GaAs buffer layer 111, an etching stop layer 112, a GaAs ohmic contact layer 113, an N-type roughening layer 114, an N-type confinement layer 115, an MQW quantum well active layer 116, a P-type confinement layer 117 and a patterned P-GaP window layer 118, which are sequentially grown on the same side; wherein the side of the patterned P-GaP window layer 118 away from the P-type confinement layer 117 is a highly doped P-GaP window layer 121;

[0080] An oxidation structure 14 located on a surface of the patterned P-GaP window layer 118 facing away from the P-type confinement layer 117, the oxidation structure 14 comprising a first oxidation layer 141, a second oxidation layer 142 and a third oxidation layer 143, wherein the second oxidation layer 142 is located between the first oxidation layer 141 and the third oxidation layer 143;

[0081] a plurality of bonding metal structures 17 located in the oxide structure 14;

[0082] A metal mirror layer 18 located on a surface of the oxidation structure 14 facing away from the epitaxial wafer 11, wherein the metal mirror layer 18 is metal-bonded to the bonding metal structure 17;

[0083] An N-electrode 19 located on the surface of the epitaxial wafer 11 facing away from the oxide structure 14, and a roughened structure 20 located on both sides of the N-electrode 19;

[0084] A Si substrate 21 located on a surface of the metal mirror layer 18 facing away from the oxidation structure 14;

[0085] A P electrode 22 is located on the surface of the Si substrate 21 which is away from the metal mirror layer 18 .

[0086] From the above description, it can be seen that in the reverse polarity LED structure provided by the technical solution of the present invention, by performing photolithography on the P-GaP window layer of the reverse polarity epitaxial wafer, etching the highly doped P-GaP window layer portion by a dry or wet etching process to form a patterned P-GaP window layer, and then coating the entire surface to form an oxide structure, the external quantum efficiency is improved without affecting the voltage, the current expansion is better, and the voltage is reduced.

[0087] In this specification, each embodiment is described in a progressive, parallel, or progressive and parallel manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the reverse polarity LED structure disclosed in the embodiment, since it corresponds to the manufacturing method of the reverse polarity LED structure disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the manufacturing method.

[0088] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0089] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for manufacturing a reverse polarity LED structure, characterized in that: The production method comprises: Providing a GaAs substrate; A GaAs buffer layer, an etching stop layer, a GaAs ohmic contact layer, an N-type roughening layer, an N-type confinement layer, an MQW quantum well active layer, a P-type confinement layer, and a P-GaP window layer are sequentially grown on a surface of one side of the GaAs substrate to form an epitaxial wafer of the reverse polarity LED structure; wherein the side of the P-GaP window layer away from the P-type confinement layer is a highly doped P-GaP window layer; Etching the highly doped P-GaP window layer portion by using photolithography technology to form a patterned P-GaP window layer; An oxidation structure is formed on a surface of the patterned P-GaP window layer on a side away from the GaAs substrate, wherein the oxidation structure comprises a first oxidation layer, a second oxidation layer and a third oxidation layer, wherein the second oxidation layer is located between the first oxidation layer and the third oxidation layer; Etching the oxide structure by photolithography to form a plurality of dielectric holes penetrating the oxide structure, and filling the dielectric holes with dielectric material to form a bonding metal structure; forming a metal mirror layer on a surface of the oxide structure facing away from the epitaxial wafer, wherein the metal mirror layer is metal-bonded to the bonding metal structure; Performing substrate transfer, removing the GaAs substrate, and forming an N electrode on a surface of the epitaxial wafer facing away from the oxidation structure, and forming a roughened structure on both sides of the N electrode; Forming a Si substrate on a surface of the metal mirror layer facing away from the oxidation structure; A P electrode is formed on a surface of the Si substrate facing away from the metal mirror layer.

2. The method according to claim 1, characterized in that: The doping concentration of the highly doped P-GaP window layer is 2×10 18 cm -3 .

3. The method according to claim 1, characterized in that: The first oxide layer is an ITO layer, an IZO layer or an Al2O3 layer.

4. The method according to claim 1, characterized in that: The second oxide layer is a SiO2 layer.

5. The method according to claim 1, characterized in that: The third oxide layer is an Al2O3 layer, an ITO layer or an IZO layer.

6. The method according to claim 1, characterized in that: The bonding metal structure is an AuZnAu layer or an AuBeAu layer.

7. The manufacturing method according to claim 1, characterized in that: The method for etching the highly doped P-GaP window layer portion comprises: Forming a first photoresist layer on a surface of the highly doped P-GaP window layer that is away from the P-type confinement layer; Using a photolithography process, etching the first photoresist layer to form a patterned first photoresist layer; Based on the patterned first photoresist layer, etching the highly doped P-GaP window layer portion to form a patterned P-GaP window layer; The remaining first photoresist layer is removed.

8. The manufacturing method according to claim 1, characterized in that: The method for forming the oxidized structure comprises: forming a first oxide layer on a surface of the patterned P-GaP window layer facing away from the P-type confinement layer; forming a second oxide layer on a surface of the first oxide layer facing away from the patterned P-GaP window layer; A third oxide layer is formed on a surface of the second oxide layer on a side facing away from the first oxide layer.

9. The manufacturing method according to claim 1, characterized in that: A method for forming the bonded metal structure, comprising: forming a second photoresist layer on a surface of the third oxide layer facing away from the second oxide layer; Using a photolithography process, etching the second photoresist layer to form a patterned second photoresist layer; Based on the patterned second photoresist layer, etching the oxide structure to remove part of the first oxide layer, part of the second oxide layer and part of the third oxide layer to form a plurality of dielectric holes penetrating the oxide structure; Filling the dielectric material in the dielectric hole to form a bonding metal structure; The remaining second photoresist layer is removed.

10. A reverse polarity LED structure, characterized in that: The reverse polarity LED structure comprises: An epitaxial wafer, the epitaxial wafer comprising a GaAs buffer layer, an etching stop layer, a GaAs ohmic contact layer, an N-type roughening layer, an N-type confinement layer, an MQW quantum well active layer, a P-type confinement layer and a patterned P-GaP window layer grown in sequence on the same side; wherein the side of the patterned P-GaP window layer away from the P-type confinement layer is a highly doped P-GaP window layer; An oxidation structure located on a surface of the patterned P-GaP window layer facing away from the P-type confinement layer, the oxidation structure comprising a first oxidation layer, a second oxidation layer and a third oxidation layer, wherein the second oxidation layer is located between the first oxidation layer and the third oxidation layer; a plurality of bonded metal structures disposed in the oxide structure; A metal mirror layer located on a surface of the oxidation structure facing away from the epitaxial wafer, wherein the metal mirror layer is metal-bonded to the bonding metal structure; An N-electrode located on a surface of the epitaxial wafer facing away from the oxidized structure, and roughened structures located on both sides of the N-electrode; A Si substrate located on a surface of the metal mirror layer facing away from the oxidation structure; A P electrode is located on the surface of the Si substrate facing away from the metal mirror layer.

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