Nitride semiconductor light emitting diode and fabrication method thereof

Abstract

The invention relates to a nitride semiconductor LED and a fabrication method thereof. In the LED, a first nitride semiconductor layer, an active region a second nitride semiconductor layer of a light emitting structure are formed in their order on a transparent substrate. A dielectric mirror layer is formed on the underside of the substrate, and has at least a pair of alternating first dielectric film of a first refractivity and a second dielectric film of a second refractivity larger than the first refractivity. A lateral insulation layer is formed on the side of the substrate and the light emitting structure. The LED of the invention effectively collimate undesirably-directed light rays, which may be otherwise extinguished, to maximize luminous efficiency, and are protected by the dielectric mirror layer formed on the side thereof to remarkably improve ESD characteristics.

1 . A wafer-level fabrication method of nitride semiconductor Light Emitting Diodes (LEDs), the method comprising the following steps of: 
 preparing a transparent wafer for growing single crystal nitride semiconductor thereon;    forming a light emitting structure including a first nitride semiconductor layer, an active layer and a second nitride semiconductor layer laminated in their order on the wafer;    cutting the wafer together with the light emitting structure into the size of LED to expose the side of each LED; and    laminating at least one alternating pair of first and second dielectric materials on the side and the underside of the LED, the first dielectric material having a first refractivity and the second dielectric material having a second refractivity larger than the first refractivity,    whereby the first and second dielectric materials are laminated at least on the underside of the LED to form a dielectric mirror layer.    
   
   
       2 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 1 , wherein the step of cutting the wafer together with the light emitting structure into the size of LED includes: attaching a tape on the light emitting structure, cutting the wafer from the underside into LEDs and stretching the tape to sufficiently expose the side of the cut LEDs.  
   
   
       3 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 1 , wherein the first and second dielectric materials are laminated on the side of the LED at substantially same thickness and number as the first and second dielectric materials on the underside of the LED to form a dielectric mirror layer.  
   
   
       4 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 1 , wherein the first and second dielectric materials comprise oxide or nitride containing one element selected from a group including Si, Zr, Ta, Ti and Al.  
   
   
       5 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 1 , wherein each of the first and second dielectric films forms a film having a thickness of about 300 to 900 Å.  
   
   
       6 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 1 , wherein each of the first and second dielectric materials comprises a SiO 2  film or a Si 3 N 4  film.  
   
   
       7 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 5 , wherein the SiO 2  film has a thickness of about 600 to 600 Å, and the Si 3 N 4  film has a thickness of about 400 to 600 Å.  
   
   
       8 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 1 , wherein the dielectric mirror layer has a reflectivity of at least 90%.  
   
   
       9 . The wafer-level fabrication method of nitride semiconductor LEDs according to  claim 8 , wherein the dielectric mirror layer has a reflectivity of at least 95%.