Abstract:
The present disclosure discloses a method of manufacturing a light-emitting device comprising the steps of providing a light-emitting wafer having a semiconductor stacked structure and an alignment mark, sensing the alignment mark, and separating the light-emitting wafer into a plurality of light-emitting diodes and removing the alignment mark accordingly.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional application of co-pending U.S. application Ser. No. 13/399,381 filed on Feb. 17, 2012. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application relates to a light-emitting device with a current block region, and a method to manufacture the same. 
       DESCRIPTION OF BACKGROUND ART 
       [0003]    In recent years, as the applications of the light-emitting diode increasing, many methods for increasing the light extraction efficiency have been provided. One of the methods is to reduce the electrical current crowding and make the electrical current spread between the electrodes wide. If the electrical current between the electrodes is not uniform and causes the electrical current crowded in some regions, the total light efficiency of the light-emitting diode will decrease. 
         [0004]    In recent years, many methods have been provided to improve the light extraction efficiency of the light-emitting diode as the light-emitting diode is applied more widely. However, the current spreading in the light-emitting diode is not uniform so the current distribution is crowded in some areas, and there is a need to improve the light extraction efficiency 
         [0005]    In order to make the current spreading uniform, a conventional LED structure has a current block region of low electric conductivity in the p-AlGaAs window layer to improve the current spreading and increase the light-emitting efficiency. 
         [0006]    Referring to  FIG. 1 , a vertical type LED comprises a semiconductor stacked layer  12 , a reflector layer  14  beneath the semiconductor stacked layer  12 , and a conductive substrate  18  bonded to the reflector layer  14  by a bonding layer  16 , wherein the semiconductor stacked layer  12  comprises an active layer  8 , a first semiconductor layer  6  and a second semiconductor layer  10 . A current block region  20  is often disposed in the vertical type LED to improve the current spreading. In general, the current block region  20  is often made of SiO 2  and formed by photolithography and etching processes to be disposed in the semiconductor stacked layer  12 . But, when the electric current is applied into the vertical type LED, the electrical current may gather around the corners of the current block region  20  to cause the high electric field. When the electric field strength is higher than the limit of the electric field loading of the LED, the LED fails.  FIG. 2  shows the failed LED due to the high electric field occurring around the corner of the current block region  20 , and a hole  21  is formed on the surface of the failed LED because of the high electric field. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    A light-emitting device comprises a support base having a planar surface, a semiconductor stacked structure disposed on the planar surface, the semiconductor stacked structure comprising a first semiconductor layer, an active layer, a second semiconductor layer, a current block region formed in one of the first semiconductor layer and the second semiconductor layer and physically contacts the planar surface and an electrode disposed on the semiconductor stacked structure. 
         [0008]    In another aspect of the present disclosure, a light-emitting device comprises a support base, a plurality of light-emitting units on the support base and a conductive unit electrically connecting the plurality of light-emitting units, wherein each of the plurality of light-emitting unit comprises a semiconductor stacked structure, an electrode disposed on the semiconductor stacked structure, a reflective layer connecting the semiconductor stacked structure, and a current block region in the semiconductor stacked structure, and wherein the reflective layer has a planar surface, and the current block region contacts the planar surface, and wherein the electrode is aligned with the current block region. 
         [0009]    A method of manufacturing a light-emitting device comprises the steps of providing a growth substrate, growing a semiconductor stacked structure on the growth substrate, wherein the semiconductor stacked structure comprises an active layer, a first semiconductor layer on the active layer, and a second semiconductor layer under the active layer, defining an alignment mark on the second semiconductor layer, forming a current block region in the semiconductor stacked structure by oxygen plasma treatment, N 2 O plasma treatment, argon plasma treatment, ion implantation, or wet oxidation, forming a reflective layer on the second semiconductor layer, bonding a substrate to the reflective layer, removing the growing substrate to expose the first semiconductor layer, and forming an electrode on the first semiconductor layer, wherein the electrode is aligned to the current block region by the alignment marks. 
         [0010]    In another aspect of the present disclosure, a method of manufacturing a light-emitting device comprising the steps of providing a light-emitting wafer having a semiconductor stacked structure and an alignment mark, sensing the alignment mark, and separating the light-emitting wafer into a plurality of light-emitting diodes and removing the alignment mark accordingly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  shows the vertical type LED with the current block region. 
           [0012]      FIG. 2  shows the failed LED due to the high electric field occurring around the corner of the current block region. 
           [0013]      FIG. 3  shows the cross-sectional view of a vertical type light-emitting diode with one current block region in the semiconductor stacked layer according to the first embodiment of the present application. 
           [0014]      FIG. 4  shows the cross-sectional view of a vertical type light-emitting diode with one current block region in the semiconductor stacked layer according to the second embodiment of the present application. 
           [0015]      FIGS. 5A to 5D  show the top view of the vertical type light-emitting diode according to the first embodiment and the second embodiment. 
           [0016]      FIGS. 6A to 6I  show the process of producing the vertical type light-emitting diode with one current block region in the semiconductor stacked la y er. 
           [0017]      FIG. 7  shows a high voltage light-emitting device formed by the vertical type light-emitting diodes according to the third embodiment of the present application. 
           [0018]      FIG. 8  shows a high voltage light-emitting device formed by the vertical type light-emitting diodes according to the fourth embodiment of the present application. 
           [0019]      FIG. 9  shows a high voltage light-emitting device formed by the vertical type light-emitting diodes according to the fifth embodiment of the present application. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    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. 
         [0021]      FIG. 3  is the cross-sectional view of a vertical type light-emitting diode with a plurality of current block regions  20  in the semiconductor stacked layer  12  according to the first embodiment of the present application. The vertical type light-emitting diode has a plurality of upper electrodes  2  ohmically contacted with the semiconductor stacked layer  12 . The semiconductor stacked layer  12  includes a first semiconductor layer  6 , an active layer  8 , and a second semiconductor layer  10 . The first semiconductor layer  6  may be an n-type semiconductor and the second semiconductor layer  10  may be a p-type semiconductor, or vice versa. The material of the first semiconductor layer  6 , the active layer  8 , and the second semiconductor layer  10  can be a compound which includes at least one substance chosen from Ga, Al, In, P, N, Zn, Cd, and Se. When the electrical current applies to the semiconductor stacked layer  12 , the active layer  8  can emit light with a wavelength of from 400 nm to 650 nm depending on the composition of the material. For example, when the material of the active layer is AlGaInP series, it can emit red light, and when the material of the active layer is AlGaInN series, it can emit blue light. There is a reflector layer  14  beneath the semiconductor stacked layer  12 . The reflector layer  14  can reflect the light emitted from the active layer  8  to improve the light extracting efficiency of the light-emitting diode. The reflector layer  14  can be made of the electrically conductive and high reflective material, such as Al, Au, Pt, Ag, Rh, Ir, or the combination thereof. A conductive substrate  18  is bonded to the reflector layer  14  by the bonding layer  16 . The bonding layer  16  can be electrically conductive, and the material of the bonding layer can be ITO, InO, SnO, CTO, ATO, AZO, ZTO, ZnO, AlGaAs, GaN, GaP, GaAs, GaAsP, etc. 
         [0022]    Each of the plurality of the current block regions  20  is formed in the semiconductor stacked layer  12  and directly contacts with the reflector layer  14 . The first contact surface  100  between the reflector layer  14  and the current block regions  20  and the second contact surface  101  between the reflector layer  14  and the semiconductor stacked layer  12  are coplanar. Each of the current block regions  20  can be formed by ion implantation, oxygen plasma treatment, N 2 O plasma treatment, argon plasma treatment, or wet oxidation. The material of the current block regions can have an electric conductivity less than one-tenth of the electric conductivity of the semiconductor material of the semiconductor stacked layer  12  around the current block regions  20 , or be an insulated oxide, such as SiO 2 , TiO 2 , or SiNx. While the electrical current disperses through the second contact surface  101 , the high electrical field does not happen and the light-emitting diode does not fail. 
         [0023]    Each of the current block regions  20  corresponds to each of the upper electrodes  2  respectively and the thickness of each of the current block regions  20  is greater than 50 Å. In other words, a virtual central normal line  102  of each of the upper electrodes  2  extends to pass the corresponding current block region  20 . The width  104  of each of the current block regions  20  is greater than the width  106  of the corresponding upper electrode  2  to make the electric current spreading wilder between the upper electrodes  2  and the lower electrode  4 . 
         [0024]      FIG. 4  is the cross-sectional view of a vertical type light-emitting diode with a plurality of current block regions  20  in the semiconductor stacked layer  12  according to the second embodiment of the present application. The difference between the second embodiment and the first embodiment is that the vertical type light-emitting diode has a transparent conductive layer  22  between the upper electrodes  2  and the semiconductor stacked layer  12 . The transparent conductive layer  22  can enhance the spread of the electric current. The material of the transparent conductive layer  22  can be ITO, InO, SnO, CTO, ATO, ZnO, GaP, etc. 
         [0025]      FIGS. 5A to 5D  are the top view of the vertical type light-emitting diode according to the aforementioned two embodiments. The shape of the current block region  20  can be a circle, a square, a rectangle, an ellipse, or any combination thereof. Generally, the shape of the current block region  20  is similar to the shape of the upper electrode  2 . 
         [0026]      FIGS. 6A to 6I  show the process of producing the vertical type light-emitting diode with a plurality of current block regions  20  in the semiconductor stacked layer  12 . 
         [0027]      FIG. 6A  shows the step of providing a growing substrate  24 . The material of the growing substrate  24  can be sapphire, SiC, GaN, GaAs, GaP, etc. Then, as  FIG. 6B  shows, a semiconductor stacked layer  12  is grown on the growing substrate  24 . The semiconductor stacked layer  12  comprises an active layer  8 , a first semiconductor layer  6  and a second semiconductor layer  10 . The first semiconductor layer  6 , the active layer  8 , and the second semiconductor layer  10  are grown in sequence. The first semiconductor layer  6  and the second semiconductor layer  10  have different conductivity type. The first semiconductor layer  6  may be an n-type semiconductor and the second semiconductor layer  10  may be a p-type semiconductor, or vice versa. In the next step, as  FIG. 6C  shows, the current block regions  20  and alignment marks  26  are formed in the second semiconductor layer  10 . The current block regions  20  can be formed by oxygen plasma treatment, N 2 O plasma treatment, argon plasma treatment, ion implantation, or wet oxidation and are not covered by the second semiconductor layer  10 , and a first surface  13  of the second semiconductor layer  10  which is planar is formed. The alignment marks  26  are opaque and indicate the region without forming the light-emitting diodes. When the semiconductor stacked layer  12  is flipped upside down, the alignment marks  26  can be used for alignment from the back side of the semiconductor stacked layer  12  in sequent steps. In the next step, as  FIG. 6D  shows, a reflector layer  14  is formed on the semiconductor stacked layer  12 . The reflector layer  14  is electrically conductive and reflective, and the material of the reflector layer  14  can be Al, Au, Pt, Ag, Rh, Ir, or the combination thereof. In the next step, as  FIG. 6E  shows, a conductive substrate  18  is bonded to the reflector  14  by the bonding layer  16 . The bonding layer  16  is electrically conductive. The material of the bonding layer  16  can be ITO, InO, SnO, CTO, ATO, AZO, ZTO, ZnO, AlGaAs, GaN, GaP, GaAs, GaAsP, etc. In the next step, as the  FIG. 6F  shows, the growing substrate  24  is separated from the semiconductor stacked layer  12 . In the next step, as shown in  FIG. 6G , the light emitting wafer  110  is flipped upside down. The upper electrodes  2  are formed on first semiconductor layer  6  and the lower electrode  4  is formed on the other surface of the conductive substrate  18 . The positions of the upper electrodes  2  are determined by sensing the positions of the alignment marks  26 . If the upper electrodes  2  do not align the alignment marks  26 , the upper electrodes  2  cannot align the current block regions  20  and the current spreading is poor. Then, as shown in  FIG. 6H , the light emitting wafer  110  is separated to form a plurality of light-emitting diodes  3  shown in the  FIG. 6I , and the alignment marks  26  are removed during the separation of the light emitting wafer  110 . 
         [0028]    Further, the aforementioned vertical type light-emitting diodes can be connected in series to form a high voltage light-emitting device.  FIG. 7  shows a high voltage light-emitting device  70  formed by the vertical type light-emitting diodes  40 , which has one current block region  20 , connected in series according to the third embodiment of the present application. Each of the light-emitting diode  40  comprises a semiconductor stacked layer  12 , a reflector layer  14 , at least one upper electrode  2  on the semiconductor stacked layer  12 . The current block regions  20  are formed in the semiconductor stacked layer  12  and contact the reflector layer  14 . The first contact surface  702 , which connects the reflector layer  12  and the current block regions  20 , and the second contact surface, which connects the reflector layer  12  and the semiconductor stacked layer  12 , are coplanar. The semiconductor stacked layer  12  includes a first semiconductor layer  6 , an active layer  8  and a second semiconductor layer  10 . The first semiconductor layer  6  and the second semiconductor layer  10  have different conductivity type. The first semiconductor layer  6  may be an n-type semiconductor and the second semiconductor layer  10  may be a p-type semiconductor, or vice versa. The material of the first semiconductor layer  6 , the active layer  8 , and the second semiconductor layer  10  can be a compound which includes at least one substance chosen from Ga, Al, In, P, N, Zn, Cd, and Se. When the electrical current applies to the semiconductor stacked layer  12 , the active layer  8  can emit light with a wavelength of from 400 nm to 650 nm depending on the composition of the material. For example, when the material of the active layer  8  is AIGaInP series, it can emit red light, and when the material of the active layer  8  is AlGaInN series, it can emit blue light. The reflector layer  14  can reflect the light emitted from the active layer  8  to improve the light extracting efficiency of the light-emitting diode. The reflector layer  14  can be made of the electrically conductive and reflective material, such as Al, Au, Pt, Ag, Rh, Ir, or the combination thereof. The plurality of light-emitting diodes  40  are bonded to the insulated substrate  34  by the bonding layer  16 . The bonding layer  16  can be electrically conductive, and the material of the bonding layer can be ITO, InO, SnO, CTO, ATO, AZO, ZTO, ZnO, AlGaAs, GaN, GaP, GaAs, GaAsP, etc. The material of the insulated substrate  34  can be glass, sapphire, AlN, ceramic, etc. The first side wall  50  and the second side wall  52  between any two of the light-emitting diodes  40  are covered by the first insulation layer  30 A and the second insulation layer  30 B respectively. The first insulation layer  30 A and the second insulation layer  30 B also cover a portion of the upper surface  54  of each of the light-emitting diodes  40 . The bonding layer  16  protrudes from the first side wall  50  and is uncovered by the first insulation layer  30 A. Between any two light-emitting diodes  40 , there is a bridge metal  32  electrically connect the bonding layer  16  of one of two light-emitting diodes  40  with the upper electrodes  2  of the other light-emitting diode  40 . For any two electrically connected light-emitting diodes  40 , the bridge metal  32  is isolated from each of the semiconductor stacked layers  12  and each of the reflector layers  14  by the first insulation layer  30 A and the second insulation layer  30 B. 
         [0029]      FIG. 8  shows a high voltage light-emitting device  80  formed by the vertical type light-emitting diodes  40 , which has one current block region  20 , connected in series according to the fourth embodiment of the present application. The difference between the preceding light-emitting device  70  and the light-emitting device  80  is that there is an insulating layer  42  between the bonding layers  16  and the substrate  44 . The insulating layer  42  can be formed by spin coating, printing, or molding glue filling, and the material of the insulating layer  42  can be spin-on-glass, silicone resin, BCB, epoxy, polyimide or PFCB. The material of the substrate  44  can be electrically conductive material, such as metal or metal alloy like Cu, Al, Sn, Zn, Cd, Ni, Co, W, Mo, or the combination thereof, or electrically insulating material, such as sapphire, diamond, glass, polymer, epoxy, quartz, acryl, AlN, etc. 
         [0030]      FIG. 9  shows a high voltage light-emitting device  90  formed by the vertical type light-emitting diodes  40 A, which has at least one current block region  20 , connected in series according to the fifth embodiment of the present application. Each of the light-emitting diode  40 A includes a semiconductor stacked layer  12 , a reflector layer  14 A, and at least one upper electrode  2  on the semiconductor stacked layer  12 . The current block regions  20  are formed in the semiconductor stacked layer  12  and exposed from the semiconductor stacked layer  12  to contact the reflector layer  14 A. The first contact surface  902 , which connects the current block region  20  and the reflector layer  14 A, and the second contact surface, which connects the current block regions  20  and the reflector layer  14 A, are coplanar. The semiconductor stacked layer  12  includes a first semiconductor layer  6 , an active layer  8 , and a second semiconductor layer  10 . The first semiconductor layer  6  and the second semiconductor layer  10  have different conductivity type. The first semiconductor layer  6  may be an n-type semiconductor and the second semiconductor layer  10  may be a p-type semiconductor, or vice versa. The material of the first semiconductor layer  6 , the active layer  8 , and the second semiconductor layer  10  can be a compound which includes at least one substance chosen from Ga, Al, In, P, N, Zn, Cd, and Se. When the electrical current applies to the semiconductor stacked layer  12 , the active layer  8  can emit light with a wavelength of from 400 nm to 650 nm depending on the composition of the material. For example, when the material of the active layer  8  is AlGalnP series, it can emit red light, and when the material of the active layer  8  is AlGaInN series, it can emit blue light. The reflector layer  14 A can reflect the light emitted from the active layer  8  to improve the light extracting efficiency of the light-emitting diode. The reflector layer  14 A can be made of the electrically conductive and high reflective material, such as Al, Au, Pt, Ag, Rh, Ir, or the combination thereof. The light-emitting diodes  40  are bonded to the substrate  38  by the insulating bonding layer  36 . The material of the insulating bonding layer  36  includes spin-on-glass, silicone resin, BCB, epoxy, polyimide, or PFCB. The material of the substrate  38  can be electrically conductive material, such as metal or metal alloy like Cu, Al, Sn, Zn, Cd, Ni, Co, W, Mo, or the combination thereof, or electrically insulating material, such as sapphire, diamond, glass, polymer, epoxy, quartz, acryl, AlN, etc. 
         [0031]    Between any two light-emitting diodes  40 A, the first insulation layer  30 A and the second insulation layer  30 B cover the first side wall  50 A, the second side wall  52 A respectively and a portion of the upper surface  54 . For each of the light-emitting diode  40 A, the reflector layer  14 A protrudes from the first side wall  50  and is uncover by the first insulation layer  30 A. For any two light-emitting diodes  40 , a bridge metal  32 A, which is disposed between the two light-emitting diodes  40 A, connects the reflector layer  14 A of one of the two light-emitting diodes  40 A with the upper electrode  2  of the other light-emitting diode  40 A. For any two electrically connected light-emitting diodes  40 A, the bridge metal  32 A is isolated from each of the semiconductor stacked layers  12  and each of the reflector layers  14 A by the first insulation layer  30 A and the second insulation layer  30 B. 
         [0032]    The light-emitting device or light-emitted diode mentioned above may be mounted with the substrate onto a submount via a solder bump or a glue material to form a light-emitting apparatus. Besides, the submount further comprises one circuit layout electrically connected to the electrode of the light-emitting device via an electrical conductive structure, such as a metal wire.