Abstract:
A light-emitting device comprises a base, a light-emitting unit comprising a semiconductor stack disposed on the base, and a wavelength conversion layer covering the light-emitting unit, wherein the wavelength conversion layer does not physically contact the base.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to a light-emitting device comprising a semiconductor stacking layer with a wavelength conversion layer, and a method to manufacture the same. 
       DESCRIPTION OF BACKGROUND ART 
       [0002]    Light-emitting devices manufactured with compound semiconductor light-emitting diodes can realize various colors and are used for various applications including lamps, electric display boards, and displays. In particular, since the light-emitting device can realize white light, it is used for general lighting. 
         [0003]    Generally, white light can be obtained by a combination of the blue light-emitting diode and phosphors.  FIG. 1A  shows the light-emitting diode  2  covered by the phosphor layer  1 . The light-emitting diode  2  is connected to the substrate  58  by one or more conductive units  5 . The material of the conductive unit can be metal such as Au, Cu, Sn, Ag, Al, or an alloy such as AuSn or AgSn, and the conductive unit  5  is generally formed by evaporation. Eutectic bonding process is a common method for connecting the light-emitting diode  2  and the substrate  58 . Since the structure of the conductive unit formed by evaporation is loose, the conductive unit would shrink during the eutectic bonding process.  FIG. 1B  shows the light-emitting diode  2  is connected to the substrate  58  with the conductive units  5  which is shrunken. Since the shrinking effect of the conductive units  5  occurs, a portion of the phosphor layer  1 A flows into the space between the substrate  58  and each of the conductive units  5  so a gap  100  is formed and causes the eutectic bonding to fail. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    A light-emitting device comprises a base, a light-emitting unit comprising a semiconductor stack disposed on the base, and a wavelength conversion layer covering the light-emitting unit, wherein the wavelength conversion layer does not physically contact the base. 
         [0005]    A light-emitting device comprises a base, a resist layer on the base, a plurality of light-emitting units having a side wall on the base, wherein the side wall of each of the light-emitting units has a upper surface and a lower surface, and the lower surface is closer to the base than the upper surface and covered by the resist layer, a wavelength conversion layer on the upper surface of each of the light-emitting units, and a trench between any two of the light-emitting units, wherein the trench passes through the wavelength conversion layer to expose the resist layer. 
         [0006]    A light-emitting device comprises a base, a resist layer on the base, a plurality of light-emitting units having a side wall on the base, wherein the side wall of the light-emitting unit has a upper surface and a lower surface, and the lower surface is closer to the base than the upper surface, and covered by the resist layer, a wavelength conversion layer on the upper surface of each of the light-emitting units, a glue layer on the wavelength conversion layer, and a trench between any two of the light-emitting units, wherein the trench passes through the glue layer and the wavelength conversion layer to expose the resist layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIGS. 1A and 1B  illustrate the conventional bonding process of a light-emitting diode with a phosphor layer. 
           [0008]      FIGS. 2A and 2B  are the cross-sectional view of a light-emitting diode with a wavelength conversion layer according to the first embodiment of the present application. 
           [0009]      FIG. 3  is the cross-sectional view of a light-emitting diode with a wavelength conversion layer according to the second embodiment of the present application. 
           [0010]      FIG. 4  is the cross-sectional view of a light-emitting diode with a wavelength conversion layer and a glue layer according to the third embodiment of the present application. 
           [0011]      FIG. 5  is the cross-sectional view of a light-emitting device with a wavelength conversion layer according to the fourth embodiment of the present application. 
           [0012]      FIG. 6  is the cross-sectional view of a light-emitting device with a wavelength conversion layer according to the fifth embodiment of the present application. 
           [0013]      FIG. 7  is the cross-sectional view of light-emitting device with a wavelength conversion layer and a glue layer according to the sixth embodiment of the present application. 
           [0014]      FIG. 8  is the cross-sectional view of light-emitting device with a wavelength conversion layer which has a protrusion part and a glue layer according to the seventh embodiment of the present application. 
           [0015]      FIGS. 9A to 9F  show the process of manufacturing the light-emitting diode with a wavelength conversion layer which has a protrusion part on the edge thereof according to the second embodiment of the present application. 
           [0016]      FIGS. 10A to 10D  show the process of manufacturing the light-emitting diode with a wavelength conversion layer and a glue layer according to the third embodiment of the present application. 
           [0017]      FIGS. 11A to 11E  show another process of manufacturing the light-emitting diode with a wavelength conversion layer and a glue layer according to the third embodiment of the present application. 
           [0018]      FIG. 12  shows the color temperature distribution of the light emitted from the light-emitting diode according to one embodiment of the present application. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    Exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings hereafter. The following embodiments are given by way of illustration to help those skilled in the art fully understand the spirit of the present application. Hence, it should be noted that the present application is not limited to the embodiments herein and can be realized by various forms. Further, the drawings are not precise scale and components may be exaggerated in view of width, height, length, etc. Herein, the similar or identical reference numerals will denote the similar or identical components throughout the drawings. 
         [0020]      FIGS. 2A and 2B  are the cross-sectional view of a light-emitting diode with a wavelength conversion layer according to the first embodiment of the present application. 
         [0021]    Referring to the  FIG. 2B , the light-emitting diode  2  having semiconductor stacking layers  22 ,  24 ,  26  and electrodes  28  is bonded with the base  12 . The bonding method can be a high force bonding, such as eutectic bonding, metal bonding, fusion bonding, and a low force bonding, such as adhesive bonding. The base  12  can be a conductive substrate, a support substrate, or a temporary substrate, without limited to a particular substrate. The structure of the electrodes  28  can be a single metal layer or multiple metal layers, and the material of the electrodes comprises Pt, Au, Cu, Sn, Ag, Al, the alloy thereof or the combination thereof. The electrodes are generally formed by evaporation, deposition, electrical plating, or chemical plating. The side wall  7  of the light-emitting diode  2  has an upper surface  8  and a lower surface  10 , and the lower surface  10  is closer to the base  12  than the upper surface  8 . The wavelength conversion layer  4  covers only the top surface  6  of light-emitting diode  2  and the upper surface  8 , and does not cover the lower surface  10 . The wavelength conversion layer  4  contains phosphor capable of converting the light of the first wavelength emitted from the light-emitting diode  2  into the light of the second wavelength. In the embodiment, the second wavelength is longer than the first wavelength. 
         [0022]    Normally, the structure of the electrodes  28  formed by evaporation is looser than formed by deposition, electrical plating, or chemical plating. Therefore, referring to  FIG. 2B , when the light-emitting diode  2  is bonded to the base  12  by high force bonding, the electrodes  28  formed by evaporation shrink and the height  32  of each electrode  28  decreases. Because the lower surface  10  spaces the wavelength conversion layer  4  from base  12  even after the high force bonding, the flow of the wavelength conversion layer  4  into the space between the electrode  28  and the base  12  is prevented. 
         [0023]      FIG. 3A  is the cross-sectional view of a light-emitting diode with a wavelength conversion layer according to the second embodiment of the present application. Referring to  FIG. 3A , the difference between the second embodiment and the first embodiment is that the wavelength conversion layer  4  has a protrusion part  41  extending outwards at the ends. Specifically, the protrusion part  41  is formed above the border  9  between the upper surface  8  and the lower surface  10 . In the first embodiment, when the light emitted from the active layer  24  passes through the upper surface  8  and the lower surface  10 , because the lower surface  10  is not covered by the wavelength conversion layer  4 , the light of the first wavelength which passes through the lower surface  10  is converted into the light of the second wavelength. Thus, with the protrusion part  41 , the wavelength converter layer  4  can convert more light of the first wavelength emitted from the active layer  24  which passes through the lower surface  10  than when there is no protrusion part  41 . Generally, as indicated in  FIG. 3B , the width  42  of the protrusion part is equal to or smaller than 500 μm, and is preferred to be between 10 μm and 300 μm. 
         [0024]      FIG. 4  is the cross-sectional view of a light-emitting diode with a wavelength conversion layer and a glue layer according to the third embodiment of the present application. Referring to  FIG. 4 , the third embodiment is different from the first and second embodiments in that the light-emitting diode has a glue layer  16 , which is transparent, covering the wavelength conversion layer  4 . The glue layer  16  can reduce the probability of the phosphor particle falling from the wavelength conversion layer  4  so the process stability of forming the wavelength conversion layer  4  is increased. The glue layer  16  can be formed by spin coating, printing, or molding glue filling, and the material of the glue layer  16  can be transparent and elastic material such as epoxy, silicone rubber, silicon resin, silicone gel, elastic PU, porous PU, or acrylic rubber. 
         [0025]      FIG. 5  is the cross-sectional view of a light-emitting device with a wavelength conversion layer according to the fourth embodiment of the present application. The fourth embodiment is different from the first embodiment in that the light-emitting diode  2  has the upper electrode  30  on the top surface  6 . 
         [0026]      FIG. 6  is the cross-sectional view of a light-emitting device with a wavelength conversion layer which has a protrusion part  41  extending outwards at the ends. Specifically, the protrusion part  41  is formed above the border  9  between the upper surface  8  and the lower surface  10  according to the fifth embodiment of the present application. The fifth embodiment is different from the second embodiment in that the light-emitting diode  2  has the upper electrode  30  on the top surface  6  thereof. 
         [0027]      FIG. 7  is the cross-sectional view of light-emitting device with a wavelength conversion layer and a glue layer according to the sixth embodiment of the present application. The sixth embodiment is different from the fourth embodiment in that there is a glue layer  16 , which is transparent, covering the wavelength conversion layer  4 . The glue layer  16  can reduce the probability of the phosphor particle falling from the wavelength conversion layer  4  so the process stability of forming the wavelength conversion layer  4  is increased. The glue layer  16  can be formed by spin coating, printing, or molding glue filling, and the material of the glue layer  16  can be transparent and elastic material such as epoxy, silicone rubber, silicon resin, silicone gel, elastic PU, porous PU, or acrylic rubber. 
         [0028]      FIG. 8  is the cross-sectional view of light-emitting device with a wavelength conversion layer which has a protrusion part and a glue layer according to the seventh embodiment of the present application. The seventh embodiment is different from the fifth embodiment in that there is a glue layer  16 , which is transparent, covering the wavelength conversion layer  4 . The glue layer  16  can prevent the phosphor particle falling from the wavelength conversion layer  4  so the process stability of forming the wavelength conversion layer  4  is increased. The glue layer  16  can be formed by spin coating, printing, or molding glue filling, and the material of the glue layer  16  can be transparent and elastic material such as epoxy, silicone rubber, silicon resin, silicone gel, elastic PU, porous PU, or acrylic rubber. 
         [0029]      FIGS. 9A to 9F  show the process of manufacturing the light-emitting diode with a wavelength conversion layer which has a protrusion part in accordance with the second embodiment of the present application. 
         [0030]    Referring to the  FIG. 9A , a plurality of light-emitting diodes  2  is disposed on a tape  50 . In  FIG. 9B , the plurality of light-emitting diodes  2  is flipped over and disposed on a substrate  54  which is covered by a resist layer  52  which is used to prevent the wavelength conversion layer  4  contacting the substrate  54  in later steps. The resist layer  52  can be removed by light, heating or solvent, and the material of the resist layer  52  can be photo resist or glue. The side wall  7  of each light-emitting diode  2  has an upper surface  8  and a lower surface  10 , and the lower surface  10  is closer to the substrate  54 . The lower surface  10  of each light-emitting diode  2  is covered by the resist layer  52 . In  FIG. 9C , the tape  50  is separated from the light-emitting diode  2 , and then, in  FIG. 9D , a wavelength conversion layer  4  is formed to cover the light-emitting diodes  2  and the resist layer  52 . Then, referring to  FIG. 9E , a trench  43  is formed between the light-emitting diodes  2  on the wavelength conversion layer  4  to expose the resist layer  52 . The trench  43  can be formed by the method such as photolithography, etching, or ICP cutting. The trench  43  can define the width of protrusion part  42 . As indicated in  FIG. 9F , the width  42  of the protrusion part is equal to or smaller than 500 μm, and is preferred to be between 10 μm and 300 μm. Finally, referring to  FIG. 9F , the resist layer  52  is removed and the substrate  54  is separated from the plurality of light-emitting diodes  2 . 
         [0031]      FIGS. 10A to 10D  show the process of manufacturing the light-emitting diode with a wavelength conversion layer and a glue layer for the third embodiment of the present application. Referring to the  FIG. 10A , the plurality of light-emitting diode  2  is disposed on the substrate  54 . There is a resist layer  52  formed on the substrate  54  and covering the lower surface  10  of each light-emitting diode  2 . The resist layer  52  can be removed by light, heating or solvent, and the material of the resist layer  52  can be photo resist or glue. A wavelength conversion layer  4  is formed to cover the plurality of light-emitting diodes  2  and the resist layer  52 . The resist layer  52  is used to prevent the wavelength conversion layer  4  contacting the substrate  54 . Referring to  FIG. 10B , a glue layer  16 , which is transparent, is formed to cover the wavelength conversion layer  4 . The glue layer  16  can be formed by spin coating, printing, or molding glue filling, and the material of the glue layer  16  can be transparent and elastic material such as epoxy, silicone rubber, silicon resin, silicone gel, elastic PU, porous PU, or acrylic rubber. Then, referring to  FIG. 10C , a trench  43  is formed between the light-emitting diodes  2  extending from the glue layer  16  and through the wavelength conversion layer  4  to expose the resist layer  52 . The trench  43  can be formed by the method such as photolithography, etching, or ICP cutting and define the width of protrusion part  42 . As indicated in  FIG. 10D , the width  42  of the protrusion part is equal to or smaller than 500 μm, and is preferred to be between 10 μm and 300 μm. Finally, referring to  FIG. 10D , the resist layer  52  is removed and the substrate  54  is separated from the plurality of light-emitting diodes  2 . 
         [0032]      FIGS. 11A to 11E  show another process of manufacturing the light-emitting diode with a wavelength conversion layer and a glue layer for the third embodiment of the present application. Referring to the  FIG. 11A , the plurality of light-emitting diode  2  is disposed on the substrate  54 . There is a resist layer  52  formed on the substrate  54  and covering the lower surface  10  of each light-emitting diode. The resist layer  52  can be removed by light, heating or solvent, and the material of the resist layer  52  can be photo resist or glue. A wavelength conversion layer  4  is formed to cover the plurality of light-emitting diodes  2  and the resist layer  52 . The resist layer  52  is used to prevent the wavelength conversion layer  4  contacting the substrate  54 . A glue layer  16 , which is transparent, is formed to cover the wavelength conversion layer  4 . The glue layer  16  can be formed by spin coating, printing, or molding glue filling, and the material of the glue layer  16  can be transparent and elastic material such as epoxy, silicone rubber, silicon resin, silicone gel, elastic PU, porous PU, or acrylic rubber. Then, referring to  FIG. 11B  and  FIG. 11C , a tape  18  is disposed on the glue layer  16  and the resist layer  52  and the substrate  54  are removed. Referring to  FIG. 11D , the plurality of light-emitting diodes  2  is flipped upside down and a trench  43  is formed between the plurality of light-emitting diodes  2  extending from the wavelength conversion layer  4  and through the glue layer  16  to expose the tape  18 . The trench  43  can be formed by the method such as photolithography, etching, or ICP cutting and define the width of protrusion part  42 . As indicated in  FIG. 11D , the width  42  of the protrusion part is equal to or smaller than 500 μm, and is preferred to be between 10 μm and 300 μm. Finally, referring to  FIG. 11E , the tape  18  is separated from the plurality of light-emitting diodes  2 . 
         [0033]      FIG. 12  show the color temperature distribution of the light emitted from the light-emitting diode  2  covered by the wavelength conversion layer with the protrusion part. The view angle of the XV plane is the top view of the light-emitting diode  2 . As indicated in  FIG. 12 , when the view angle (Theta) is near 90° or −90°, or more precisely, when the view angle (Theta) is between −90° and −75° or between 75° and 90°, the color temperature (CCT) can be over 6000K. In other words, the light generated from light emitting diode  2  can be bluish when the view angle (Theta) is near 90° or −90°.