Abstract:
An LED manufacturing method includes following steps: providing an LED die; providing an electrode layer having a first section and a second section electrically insulated from the first section, and arranging the LED die on the second section wherein an electrically conductive material electrical connects a bottom of the LED die with second section; forming a transparent conductive layer to electrically connect a top of the LED die with the first section; providing a base and coating an outer surface of the base with a layer of electrically conductive material, defining a continuous gap in the electrically conductive material to divide the electrically conductive material into a first electrode part, and a second electrode part, arranging the electrode layer on the base so that the first section contacts the first electrode part, and the second section contacts the second electrode part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a divisional application of patent application Ser. No. 13/300,731, filed on Nov. 21, 2011, entitled “LIGHT EMITTING DIODES AND METHOD FOR MANUFACTURING THE SAME,” which is assigned to the same assignee as the present application, and which is based on and claims priority from Chinese Patent Application No. 201110005426.2 filed in China on Jan. 10, 2011. The disclosures of patent application Ser. No. 13/300,731 and the Chinese Patent Application are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to solid state light emitting devices and, more particularly, to a method for manufacturing light emitting diodes (LEDs) wherein there is no electrode which may hinder light radiation from a top of the LED formed on the top of the LED. 
     2. Description of Related Art 
     In recent years, LEDs have been widely used in devices to provide illumination. Typically, an LED may include an LED die, an electrode layer, and two gold wires. The LED die may include a light emitting surface. Two spaced terminals may be formed on the light emitting surface. The LED die may be electrically connected to the electrode layer through wire bonding, in which the two gold wires may be respectively soldered to the terminals and the electrode layer by solder. However, part of the light emitting surface of the LED die may be blocked by the solder and the gold wires, resulting in a decreased illumination efficiency of the LED. 
     What is needed, therefore, is an LED to overcome the described disadvantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an LED of a first embodiment of the present disclosure. 
         FIGS. 2-7  are cross-sectional views illustrating steps of manufacturing an LED chip of the LED as disclosed in  FIG. 1 . 
         FIG. 8  is a cross-sectional view of an LED of a second embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an LED  10  is shown. The LED  10  may include a base  11 , an LED chip  12  arranged on the base  11 , and a packaging layer  13  arranged on the base  11  and encapsulating the LED chip  12  therein. 
     The base  11  is electrically insulated and has a size larger than the LED chip  12 . An outer surface of the base  11  is coated with a layer of electrically conductive material. A continuous gap  113  is defined in the electrically conductive material to divide the electrically conductive material into two separate parts: a first electrode part  111  and a second electrode part  112 . The base  11  has good heat dissipation efficiency and absorbs heat generated from the LED chip  12  to prevent the LED chip  12  from overheating. 
     Referring also to  FIG. 7 , the LED chip  12  may comprises an electrode layer  14 , an electrically conductive layer  18  formed on the electrode layer  14 , an LED die  15  formed on the electrically conductive layer  18 , an electrically insulating layer  16  surrounding the LED die  15  and the electrically conductive layer  18 , and a transparent electrically conducting layer  17  electrically connecting the LED die  15  and the electrode layer  14 . 
     The electrode layer  14  has a size smaller than that of the base  11  and is formed on a central portion of a top of the base  11 . A through hole  144  is defined in the electrode layer  14  and aligned with the continuous gap  113  of the base  11 . In the present embodiment, the through hole  144  is located at a left side of the LED die  15 , and has a width smaller than a width of the continuous gap  113  of the base  11 . The through hole  144  is coaxial with the continuous gap  113 . An electrically insulating material  143  is filled in the through hole  144 . The through hole  144  divides the electrode layer  14  into two separate sections: a first section  141  and a second section  142 . The insulating material  143  is between the first section  141  and the second section  142  to insulate the first section  141  from the second section  142 . The first section  141  and the second section  142  are electrically connected to the first electrode part  111  and the second electrode part  112 , respectively. 
     The LED die  15  includes an electrically insulating substrate  151 , an N-doped region formed on the electrically insulating substrate  151 , an active layer  154  formed on the N-doped region, and a P-doped region formed on the active layer  154 . In this embodiment, the P-doped region is a P-type gallium nitrogen layer  157 . The N-doped region is an N-type gallium nitrogen layer  153 . The electrically insulating substrate  151 , the N-type gallium nitrogen layer  153 , the active layer  154  and the P-type gallium nitrogen layer  157  are stacked one on the other along a vertical direction of the LED  10 . The N-type gallium nitrogen layer  153 , the active layer  154 , and the P-type gallium nitrogen layer  157  cooperatively construct a P-N junction. 
     The electrically conductive layer  18  has a size equal to that of the LED die  15  and is located on the second section  142  of the electrode layer  14 , and is electrically connected to the second section  142 . A through hole  1511  is defined in the electrically insulating substrate  151 . An electrically conductive pole  181  protrudes from the electrically conductive layer  18 . The electrically conductive layer  18  is coated on the electrically insulating substrate  151 , and the electrically conductive pole  181  extends through the through hole  1511 . The electrically conductive layer  18  is electrically connected to the N-type gallium nitrogen layer  153  through the electrically conductive pole  181 . 
     The electrically insulating layer  16  is transparent and made of silicon dioxide or silicon nitride. In the present embodiment, the electrically insulating layer  16  completely covers lateral sides of the LED die  15  and the electrically conductive layer  18 , and partially covers a periphery of a top side of the LED die  15  with a through hole  161  defined above a central portion of a top of the P-type gallium nitrogen layer  157 . The electrically insulating layer  16  also covers part of top surfaces of the first and second sections  141 ,  142  near the LED die  15 . The electrically insulating layer  16  covers the through hole  144  of the electrode layer  14 . 
     The transparent electrically conducting layer  17  electrically connects the P-type gallium nitrogen layer  157  and the first section  141  of the electrode layer  14 . The transparent electrically conducting layer  17  is made of transparent alloys, such as indium tin oxide, or carbon nanotube film. The transparent electrically conducting layer  17  comprises a first covering portion  171  on the top side of the LED die  15 , a second covering portion  173  on the first section  141 , and a connecting portion  172  interconnecting the first covering portion  171  and the second covering portion  173  and on a lateral side of a left part of the electrically insulating layer  16 . 
     The first covering portion  171  fills the through hole  161  to connect the central portion of the P-type gallium nitrogen layer  157  of the LED die  15 . The second covering portion  173  is arranged on the first section  141 . The electrically insulating layer  16  is located between the electrically conducting layer  17  and the LED die  15  to electrically insulate the electrically conducting layer  17  from the LED die  15  except the central portion of the top of the P-type gallium nitrogen layer  157 . 
     The packaging layer  13  is made of transparent, electrically insulating materials, such as silicone, epoxy, quartz, or glass. The packaging layer  13  encapsulates the LED chip  12  therein and is formed on the base  11 . 
     In the present disclosure, because the transparent electrically conducting layer  17  and the electrically insulating layer  16  are transparent, and coated directly on the LED die  15 , light emitted from the active layer  154  may not be blocked by any element of the LED  10 . Therefore, light emitting efficiency of the LED  10  may be improved in comparison with the conventional LED. 
       FIGS. 2-7  illustrate steps of manufacturing a LED chip according to an embodiment of the present disclosure. 
     Referring to  FIGS. 2-3  wherein the LED die  15  is provided. The through hole  1511  is etched through the electrically insulating substrate  151  to define the through hole  1511 . An electrically conductive material is provided. The electrically conductive material fills the through hole  1511  and coats an outer surface of the electrically insulating substrate  151  to form the electrically conductive layer  18  and the electrically conductive pole  181  shown in  FIG. 3 . 
     Referring to  FIG. 4  wherein the electrode layer  14  is provided. The through hole  144  is etched through the electrode layer  14 . The electrically insulating material  143  is filled in the through hole  144 . The electrically conductive layer  18  is arranged on the second section  142  of the electrode layer  14  and is electrically connected to the second section  142 . 
     Referring to  FIGS. 5-6 , firstly the electrically insulating layer  16  is coated on the peripheries of the LED die  15  and the electrically conductive layer  18 , and on the top side of the electrode layer  14 . The electrically insulating layer  16  may be deposited through electroplating or sputtering deposition. Secondly, the electrically insulating layer  16  is etched to expose the central portion of the top of the P-type gallium nitrogen layer  157 , and parts of the first section  141  and the second section  142  of the electrode layer  14 . In another embodiment, the electrically insulating layer  16  may be etched only to expose the central portion of the P-type gallium nitrogen layer  157  and a part of the first section  141 , while the electrically insulating layer  16  covering the second section  142  of the electrode layer  14  may remain intact. 
     Referring to  FIG. 7 , the transparent electrically conducting layer  17  is coated on corresponding parts of the LED die  15 , the electrically insulating layer  16 , and the electrode layer  14 . The transparent electrically conducting layer  17  may be deposited through electroplating, sputtering deposition, or electron-beam evaporative deposition. The manufacturing processes of the LED chip  12  are completed. 
     Referring to  FIG. 1  again, wherein the base  11  is provided. The base  11  is coated by an electrically conducting material and the electrically conducting material is etched to define the continuous gap  113  at a left side of the base  11 . The electrode layer  14  is arranged on the base  11  with the first section  141  and the second section  142  electrically contacting the first electrode part  111  and the second electrode part  112 , respectively. The through hole  144  is aligned with the central portion of the continuous gap  113 . Finally, the packaging layer  13  is formed on the base  11  and encapsulates the LED chip  12  therein. The manufacturing processes of the LED  10  are completed. 
     Referring to  FIG. 8 , wherein an LED  20  of a second embodiment is shown. The LED  20  comprises an electrode layer  24 , an LED die  25 , an electrically insulating layer  26 , a transparent electrically conductive layer  27  and a packaging layer  23 . The LED  20  has a similar LED chip as the LED chip  12  of the LED  10  of the first embodiment. However, the base  11 , the first and second electrode parts  111 ,  112  of the LED  10  are omitted from the LED  20 . A width of the electrode layer  24  in LED  20  may be larger than that of the electrode layer  14  in LED  10 . The packaging layer  23  covers a central portion of a top of the electrode layer  24 , with a peripheral portion thereof being exposed. The electrode layer  24  is divided into a first section and a section, wherein the first and second sections are separate by a continuous gap filled with an electrically insulating material. The first section of the electrode layer  24  functions directly as a first electrode part, and the second section of the electrode layer  24  functions directly as a second electrode part. Similar to the LED  10  of the first embodiment, the LED die  25 , the electrically insulating layer  26 , and the transparent electrically conductive layer  27  of the LED  20  are also encapsulated by the packaging layer  23  of the LED  20 . 
     It is to be understood, however, that even though numerous characteristics and advantages of the embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.