Abstract:
An embodiment of the invention discloses an optoelectronic semiconductor device. The optoelectronic semiconductor comprises a unit having a plurality of electrical connectors with top surfaces; an insulating material surrounding each of the plurality of electrical connectors, wherein each of the top surfaces are exposed through the insulating material; a semiconductor system, having a side surface directly covered by the insulation material, electrically connected to the plurality of electrical connectors and being narrower in width than both of the unit and the insulating material; an electrode formed on the semiconductor system at a position not corresponding to the plurality of electrical connectors; and a layer provided on the semiconductor system at a side opposite to the electrode and configured to laterally exceed outside more than one outermost boundary of the plurality of electrical connectors.

Description:
This application is a Continuation Application of U.S. application Ser. No. 12/230,203 filed on Aug. 26, 2008, which is a Continuation-in-Part application of co-pending U.S. application Ser. No. 11/160,588, filed Jun. 29, 2005, co-pending U.S. application Ser. No. 11/160,589, filed Jun. 29, 2005, and co-pending U.S. application Ser. No. 10/905,697, filed Jan. 18, 2005, and for which priority is claimed under 35 USC §120 of which the entire disclosures of the pending prior applications are hereby incorporated by reference and claims the right of priority of Taiwan Patent Application No. 096131956, filed on Aug. 27, 2007. 
    
    
     TECHNICAL FIELD 
     The invention relates to an optoelectronic semiconductor device and more particularly to an optoelectronic semiconductor device having a plurality of electrical connectors. 
     REFERENCE TO RELATED APPLICATION 
     This application claims the right of priority based on Taiwan application Ser. No. 096131956, filed Aug. 27, 2007, and the content of which is hereby incorporated by reference. 
     DESCRIPTION OF BACKGROUND ART 
     A well known structure of light-emitting diodes includes a growth substrate, n-type semiconductor layer, p-type semiconductor layer, and a light-emitting layer between the two semiconductor layers. A reflector for reflecting light from the light-emitting layer is also optionally formed in the structure. In some cases, to improve at least one of optical, electrical, and mechanical characteristics of the light-emitting diode, a well-selected material is used to replace the growth substrate and as a carrier to support the remaining structure without the growth substrate. For example, metal or silicon is used to replace sapphire substrate on which nitride is grown. The growth substrate is removed by etching, lapping, laser removal, etc. In addition, a transparent oxide can be adopted into the light-emitting diode to improve the current spreading. 
     There are several approaches to form an ohmic contact between the replacing carrier and the growth substrate. One of related materials can be referred to E. Fred Schubert, “Light-Emitting Diodes” chapter 9 (2006). Furthermore, the light-emitting diode finished products are made after being diced from a wafer; therefore, a suitable means used to protect semiconductor layers during the dicing process also becomes a notable issue. A usual protection means is a passivation layer formed on side walls of the semiconductor layer before dicing, but a careful control must be carried in each relevant step to avoid negative impact of forming the passivation layer. 
     SUMMARY OF THE DISCLOSURE 
     An optoelectronic semiconductor device in accordance with an embodiment of present invention comprises a unit having a plurality of electrical connectors with top surfaces; an insulating material surrounding each of the plurality of electrical connectors, wherein each of the top surfaces are exposed through the insulating material; a semiconductor system, having a side surface directly covered by the insulation material, electrically connected to the plurality of electrical connectors and being narrower in width than both of the unit and the insulating material; an electrode formed on the semiconductor system at a position not corresponding to the plurality of electrical connectors; and a layer provided on the semiconductor system at a side opposite to the electrode and configured to laterally exceed outside more than one outermost boundary of the plurality of electrical connectors. 
     An optoelectronic semiconductor device in accordance with another embodiment of present invention comprises an electrical conductor; a plurality of electrical connectors formed on the electrical conductor and arranged in a matrix; an insulating material having openings configured to expose the electrical connectors; and a semiconductor system, having a side surface directly covered by the insulation material, electrically connected to the electrical connectors and being narrower in width than both of the electrical conductor and the insulating material; and an electrode formed on the semiconductor system at a position not corresponding to the electrical conductor; wherein the electrical conductor is provided on the semiconductor system at a side opposite to the electrode and configured to laterally exceed outside more than one outermost boundary of the plurality of electrical connectors. 
     An optoelectronic semiconductor device in accordance with another embodiment of present invention comprises an electrical conductor; an electrical conductor; a plurality of electrical connectors formed on the electrical conductor; an insulating material having openings configured to expose the electrical connectors; a light-emitting layer, having a side surface directly covered by the insulation material, electrically connected to the plurality of electrical connectors and being narrower in width than both of the electrical conductor and the insulating material; and an electrode formed on the light-emitting layer at a position not corresponding to the electrical conductor; wherein the electrical conductor is provided on the light-emitting layer at a side opposite to the electrode and configured to laterally exceed outside more than one outermost boundary of the plurality of electrical connectors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A˜1C  illustrate a manufacturing process of an optoelectronic semiconductor device in accordance with an embodiment of present invention. 
         FIGS. 2A˜2D  illustrate cross sectional views of optoelectronic semiconductor devices in accordance with further embodiments of present invention. 
         FIGS. 3A and 3B  illustrate an optoelectronic semiconductor device in accordance with an embodiment of present invention. 
         FIGS. 4A and 4B  illustrate an optoelectronic semiconductor device having an insulating region in accordance with another embodiment of present invention. 
         FIG. 5  illustrates an optoelectronic semiconductor device having an insulating region in accordance with an embodiment of present invention. 
         FIGS. 6A˜6C  illustrate optoelectronic semiconductor devices in accordance with further embodiments of present invention. 
         FIG. 7  illustrates an optoelectronic semiconductor device having a passive light-emitting layer in accordance with an embodiment of present invention. 
         FIG. 8  illustrates an optoelectronic semiconductor device having two reflectors in accordance with an embodiment of present invention. 
         FIG. 9  illustrates an optoelectronic semiconductor device having a textured light output surface in accordance with an embodiment of present invention. 
         FIG. 10  illustrates an optoelectronic semiconductor device in accordance with an embodiment of present invention. 
         FIG. 11  illustrates an optoelectronic semiconductor device in accordance with further embodiment of present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The embodiments are described hereinafter in accompany with drawings. 
     As shown in  FIG. 1A , a semiconductor system  12  is firstly formed on a temporary substrate  11 . The semiconductor system  12  is a semiconductor device capable of performing a conversion between light energy and electronic energy, such as light-emitting diode (LED), laser diode (LD), and solar cell. However, the term “semiconductor system” in present application does not mean that the sub-systems or units are all made of semiconductor material. Other non-semiconductor material, such as metal, oxide, and insulator, can be optionally integrated into the semiconductor system. 
     An exemplary light-emitting diode has a structure including at least two semiconductor layers having different electric properties, polarities, or dopants, and a light-emitting layer (or called “active layer”) between the two semiconductor layers. A light-emitting spectrum of the light-emitting diode can be adjusted by modifying the composition of the constructed material. The common available material includes AlGaInP series, AlGaInN series, and ZnO series. In addition, the light-emitting layer can be formed in a structure such as single heterostructure (SH), double heterostructure (DH), double-side double heterostructure (DDH), or multi-quantum well (MQW). The light-emitting wavelength can be further modified by changing the pair number of the multi-quantum well. The temporary substrate  11  is used to grow or support semiconductor system  12 . The suitable material of the temporary substrate  11  includes but not limited to Ge, GaAs, InP, sapphire, SiC, Si, LiAlO 2 , ZnO, GaN, glass, composite, diamond, CVD diamond, and diamond-like carbon (DLC). 
     After the semiconductor system  12  is formed on the temporary substrate  11 , a reflector  13  can be optionally formed to reflect light directly or indirectly form the light-emitting layer towards a specific direction. The reflector  13  is constructed by using metal such as Ag, Al, Au, Cu, and Ti, or distributed Bragg reflector (DBR). The reflector  13  can be formed on all or part of surfaces of the semiconductor system  12 . 
     A first coupling layer  14  is formed to couple with the following device or structure after the reflector  13  is completed. The material adopted into the first coupling layer  14  depends on the selected technology. With metal bonding technology, the first coupling layer  14  can be formed by material such as In, Pd, Au, Cr, or alloy thereof. With glue bonding technology, the first coupling layer  14  can be formed by material such as epoxy, benzocyclobutene (BCB), or SU-8 photo resistor. With eutectic bonding technology, the first coupling layer  14  is formed by material including but not limited to Au, Sn, In, Ge, Zn, Be, and Si. 
     The semiconductor system  12  and the layers covering thereon are then etched by inductively coupled plasma (ICP) or other suitable dry etching technology until a part of the temporary substrate  11  is exposed. For example, the semiconductor system  12  and the covering layers like the reflector  13  and the first coupling layer  14  are removed to form a rim, as shown in  FIG. 1A , or etched to reach a position of the light-emitting layer of the light-emitting diode. An interfacial layer  15  is then spin-coated on the semiconductor system  12  and the layers covering thereon. For example, in  FIG. 1A , the interfacial layer  15  is overlaid on the side surfaces of the semiconductor system  12 , the reflector  13  and the first coupling  14 , and the top surface of the first coupling layer  14 . The interfacial layer  15  is between the semiconductor system  12  and an environmental medium, and can be made of insulating material such as epoxy and benzocyclobutene (BCB). 
     An electrical conductor  16  is provided to have a second coupling layer  17  and electrical connectors  18  disposed thereon. The electrical conductor  16  is used to carry the semiconductor system  12 , functions as a current channel, and is robust enough to form a stable structure. The electrical conductor  16  is formed by conductive material such as Ge, GaAs, InP, SiC, Si, LiAlO 2 , ZnO, GaN, Cu, and Al. The electrical conductor  16  can be a separate structure as shown in  FIG. 1A  and coupled with the related structures of the semiconductor system  12  by a specific method. In another aspect, the electrical conductor  16  can be formed by electroplating, bonding, or deposition after the electrical connector  18  is completed on the semiconductor system  12 . 
     The material of the second coupling layer  17  can refer to the first coupling layer  14  mentioned in the above description. Moreover, the material of the second coupling layer  17  can be different from or the same as that of the first coupling layer  14 . Other than the embodiments in each drawing, the first coupling layer  14  and the second coupling layer  17  can be used alternatively. The material of the electrical connector  18  is such as In, Sn, Al, Ag, Au/Be, Au/Ge, Au/Zn, Ni, Pd, Pb/Sn, Pd, Pt, Zn, Ge, Ti, Cu, or Cr. Besides, provided one kind of material or structure can meet the required specifications of three or any two of the electrical connector  16 , the second coupling layer  17 , and the electrical connector  18 , the corresponding parts can be integrated into one unit. 
     The interfacial layer  15  and the second coupling later  17  are brought to connect when the aforementioned preparations are finished. In the case, the electrical connectors  18  are pressed into the interfacial layer  15 , and at least part of the electrical connectors  18  passes through the interfacial layer  15  and electrically connects to the first coupling layer  14 , as shown in  FIG. 1B . 
     The temporary substrate  11  is then removed by wet etching, dry etching, mechanical polishing, or laser removal. After that, an upper electrode  22  and a lower electrode  23  are formed on the semiconductor system  12  and the electrical conductor  16  respectively. In addition, the lower electrode  23  can be formed on electrical conductor  16  before the semiconductor system  12  and the electrical conductor  16  are coupled together. Furthermore, the electrical conductor  16  can also function as an electrode provided it has necessary characteristics of an electrode. Therefore, it is not necessary to form the lower electrode  23  on the device  10 . If the optoelectronic device  10  is provided as a “wafer” level, the wafer has to be cut in order to bring the optoelectronic device  10  into a single dice level. The structure out of the foregoing processes is shown in  FIG. 1C . At least one material capable of forming the electrode  22 , electrode  23 , or both is such as In, Sn, Al, Ag, Au, Au/Be stack, Au/Ge stack, Au/Zn stack, Ni, Pd, Pt, Zn, Ge, Ti, Cu, or Cr. 
     The interfacial layer  15  is interposed between and integrates the first coupling layer  14  and the second coupling layer  17 , and further covers on the side surface of the semiconductor system  12  to protect the system  12  from being damaged during the following manufacturing processes. In addition, if the refraction index of the interfacial layer  15  is between the semiconductor system  12  and the environmental medium, light from the semiconductor system  12  is not easily total-reflected in a presence of a great change among the refractive indices. 
     In another embodiment, the electrical connector  18  even penetrates into the first coupling layer  14  by means of elongating the electrical connector  18  or compressing the interfacial layer  15  to reduce the thickness thereof. As shown in  FIG. 2A , the electrical connector  18  has penetrated the interfacial layer  15  and been into the first coupling layer  14 , but not yet reached the reflector  13 . Moreover, the interfacial layer  15  still remains between the first coupling layer  14  and the second coupling layer  17 . In the case, provided a suitable material is chosen for the electrical connector  18  and the first coupling layer  14 , a metal bonding or a eutectic bonding can be formed between the two parts. 
     As shown in  FIG. 2B , the electrical connector  18  penetrates the interfacial layer  15  and enters into the first coupling layer  14 , but has not yet reached the reflector  13 . Moreover, the first coupling layer  14  and the second coupling layer  17  are compressed to contact with each other. In the case, provided the first coupling layer  14  and the second coupling layer  17  are made by introducing suitable material, a metal bonding or a eutectic bonding can be formed between the two parts. Provided a suitable material is chosen for the electrical connector  18  and the first coupling layer  14 , a metal bonding or a eutectic bonding can accordingly be formed between the two parts. 
     As shown in  FIG. 2C , the electrical connector  18  penetrates the interfacial layer  15  to enter into the first coupling layer  14  and reach the electrically conductive reflector  13 . In another aspect, the first coupling layer  14  and the second coupling layer  17  are compressed to contact with each other. In the case, provided a suitable material is chosen for the first coupling layer  14  and the second coupling layer  17 , a metal bonding or a eutectic bonding can be formed between the two parts. Provided a suitable material is chosen for the electrical connector  18  and the first coupling layer  14 , a metal bonding or a eutectic bonding can accordingly be formed between the two parts. In present embodiment, because the electrical connector  18  and reflector  13  are electrically connected, the first coupling layer  14  can be otherwise made by introducing an insulating material suitable for glue bonding. 
     Another embodiment is shown in  FIG. 2D . The electrical connector  18  penetrates the interfacial layer  15  to enter into the first coupling layer  14  and reach the electrically conductive reflector  13 . In addition, in present embodiment, the interfacial layer  15  is interposed between the first coupling layer  14  and the second coupling layer  17 , and keeps them from directly contacting with each other. In the case, provided a suitable material is chosen for the electrical connector  18  and the first coupling layer  14 , a metal bonding or a eutectic bonding can be formed between the two parts. In present embodiment, because the electrical connector  18  and reflector  13  are already electrically connected, the first coupling layer  14  can be otherwise made by introducing an insulating material suitable for glue bonding. The alternatives of  FIGS. 2A˜2D  can be deliberately modified to use in each of the embodiments of present invention. 
     In the foregoing embodiments, the reflector  13  may be omitted from the device  10  if the first coupling layer  14  is made of a reflective material such as Au or Ag. In the case, the reflecting and coupling functions are unified into a single structure like the first coupling layer  14 . 
     One consideration of arranging the electrical connector  18  is how to form a uniform current density among the semiconductor system  12 . In a common circumstance, current is injected into the semiconductor system  12  from the electrode  22  and left through the electrode  23  along the shortest electrical passage. Therefore, the area of the semiconductor system  12  beneath the electrode  22  usually has higher current density, which is called “current crowding” effect. In other words, more photons are created in the area beneath the electrode  22 . However, those photons are often absorbed, reflected, or scattered by the electrode  22 , and become useless. Under the electrode  22 , instead of the electrical connector  18 , an insulating region  19 A is therefore formed on the semiconductor system  10  as shown in  FIG. 3A . The insulating region can bring out a current blocking effect, which makes the current from the electrode  22  detour the area beneath the electrode  22  to spread out and flow back to the electrical connector  18  among the semiconductor system  12 . Accordingly, the optoelectronic conversion can occur in larger area of the semiconductor system  12 . The material of the insulating region  19 A can be different from or the same as that of the interfacial layer  15 . Moreover, the entire insulating region  19 A is not necessarily constructed by insulating material, but has a structure able to obstruct the current to flow through itself, or possesses a higher electrical resistance than the electrical connector  18 . For example, the electrical connector  18  corresponding to the position of the electrode  22  is made to have an elevation lower than that of the other electrical connectors, or an insulating layer is formed between the electrical connector  18  corresponding to the position of the electrode  22  and the conductive material over the connector  18 . 
       FIG. 3B  shows a cross sectional view along AA line of  FIG. 3A . In the drawing, the electrical connectors  18  are arranged in a matrix configuration in the interfacial layer  15 , except in the insulating region  19 A. The pitch of the electrical connector  18  is adjusted in a constant, variable, geometric series, random, variable periodicity, constant periodicity, or quasi-periodicity configuration. The position and shape of the insulating region  19 A are arranged to correspond to those of the electrode  22 . The area of the insulating region  19 A can be smaller than, equivalent to, or greater than that of the electrode  22 . The electrical connector  18  is formed in a shape including but not limited to rectangle, circle, ellipse, triangle, hexagon, irregularity, and the combination thereof. 
     Furthermore, in another embodiment of present invention, as shown in  FIGS. 4A and 4B , the electrical connector  18 ′ is formed in a continuous configuration.  FIG. 4B  shows a cross sectional view along line BB of  FIG. 4A . Under the same configuration as aforementioned embodiment, the insulating region  19 A is formed in the electrical connector  18 ′ corresponding to the position of the electrode  22 . In present embodiment, the contact area of the continuous electrical connector  18 ′ and the first coupling layer  14  is greater than that of the distributed electrical connectors  18  and the first coupling layer  14 . In other words, less material of the interfacial layer  15  is interposed between the electrical connector  18 ′ and the first coupling layer  14 . 
     In  FIGS. 3A˜4B , the insulating region  19 A and the electrical connector  18  are formed on about the same horizontal plane, but present invention is not limited thereto. A current-blocking structure may be formed between the electrode  22  and the electrode  23 , or the electrode  22  and the electrical conductor  16 , in any elevation corresponding to the electrode  22 . 
     In another embodiment of present invention, an insulating region  19 B is further formed between the reflector  13  over the insulating region  19 A, and the semiconductor system  12  for a better current spreading result. The insulating region  19 B is identical to or different from the interfacial layer  15 , or can even constructed by a structure as long as it is able to obstruct or decrease current flowing through the region, rather than a structure entirely made by insulating material. The insulating region  19 A of present embodiment does not necessarily coexist with the insulating region  19 B, that is, the electrical connector  18  can be still formed under the insulating region  19 B. Moreover, the top surface of the insulating region  19 B is formed in a geometric pattern including but not limited to flat plane, rough surface, textured surface, and even ridged surface as shown in the drawing. Provided the ridged surface is reflective, light from the semiconductor system  12  is reflected outwardly by the ridged surface, and light is consequently absorbed by the electrode  22  with lower probability. 
     The other embodiments of present invention are shown in  FIGS. 6A˜6C . A wavelength converting material  21  is blent into the interfacial layer  15  of the optoelectronic semiconductor device  10  of  FIG. 6A . The wavelength converting material  21  is responsive to one wavelength-radiation come from the semiconductor system  12  to produce another wavelength-radiation, and is made of phosphor or dye. The phosphor having a suitable particle diameter can reach a better light-emitting performance. The preferable particle diameter is less than 5 μm, and the relevancy can be referred to U.S. Pat. No. 6,245,259. The optoelectronic semiconductor system  10  can bring out white light by adopting the semiconductor system  12  of blue wavelength spectrum and a phosphor such as Yttrium Aluminum Garnet (YAG), Terbium Aluminum Garnet (TAG, Silicate-based phosphor, or oxynitride. 
     As shown in  FIG. 6B , an upper interfacial layer  15 A mixed with the wavelength converting material  21  is formed on the semiconductor system  12 . The upper interfacial layer  15 A can be made by the material directed to the foregoing interfacial layer  15 . As shown in  FIG. 6C , the interfacial layer  15  and the upper interfacial layer  15 A covering the periphery of the semiconductor  12  are mixed with the wavelength converting material  21 , and the two layers may have different or the same wavelength converting material inside. Moreover, the upper interfacial layer  15 A can be patterned to set the distribution boundary of the wavelength converting material. The void region  153  as shown in the drawing is a region with material, such as air, insulating material, another kind of phosphor, or indium tin oxide (ITO), different from that of the upper interfacial layer  15 A. It is helpful to spread current into the semiconductor system  12  if the conductor within the void region  153  is connected to the electrode  22 . 
     The upper interfacial layer  15 A of the optoelectronic semiconductor device  10  of  FIG. 7  at least includes a passive light-emitting layer  151  and a bonding layer  152 . The passive light-emitting layer  151  is such as a bulk phosphor, an III-V series semiconductor layer, or an II-VI series semiconductor layer. The bonding layer  152  is made of at least one organic material including PI, benzocyclobutene, PFCB, and epoxy. The passive light-emitting layer  151  is induced to produce output light in response to input light from the semiconductor system  12 , and the input light and output light have a different wavelength or spectrum. 
     Another embodiment of present invention is illustrated in  FIG. 8 . The optoelectronic semiconductor device  10  includes a lower reflector  13 A and an upper reflector  13 B. The material of the two reflectors can be referred to aforementioned material directed to the reflector  13 . Light from the semiconductor system  12  is reflected to the interfacial layer  15  by the two reflectors. The light leaving the optoelectronic semiconductor device  10  is probably reflected outwardly if it is reflected back to the semiconductor system  12  by an external object. 
     The optoelectronic semiconductor device  10  in accordance with another embodiment is illustrated in  FIG. 9  and has a textured or rough outer surface. The textured or rough outer surface can destroy the total reflection between the structure and the environmental medium and increase the light extraction of the optoelectronic semiconductor device  10 . The textured or rough outer surface can be formed on the semiconductor system  12 , the interfacial layer  15 , or the outer surfaces of both. The roughness of the rough surface has to reach a level such that the light extraction can be elevated. The textured surface can be formed in a regular or irregular convex and concave structure or a photonic crystal structure. 
       FIG. 10  shows another embodiment of present invention. In present embodiment, the semiconductor system  12  and the electrical conductor  15  of the optoelectronic semiconductor device  10  are electrically connected with each by a first intermediate layer  20 A, the electrical connector  18 , and the second intermediate layer  20 B. During the manufacturing process, the electrical connector  18  can be pre-covered by the second intermediate layer  20 B and then coupled with the semiconductor system  12  where the first intermediate layer  20 A is formed. The first intermediate layer  20 A and the second intermediate layer  20 B are contacted with each other by compressing the interfacial layer  15 . The constructing material of the interfacial layer  15  potentially remains in a trench between the electrical connectors  18 . Not only an ohmic contact but a firm physical contact is formed between the first intermediate layer  20 A and the second intermediate layer  20 B. The material of each of the two layers is Ti or Cr. 
       FIG. 11  shows another embodiment of present invention. The electrical connectors  24  of the optoelectronic semiconductor device  10  are formed as an irregular structure such as a rough surface. The material of the first intermediate layer  20 A and the second intermediate layer  20 B is described above. In present embodiment, the electrical connector  24  is covered by the second intermediate layer  20 B and not yet been flattened completely. At least some protrusions of the second intermediate layer  20 B are made to penetrate the interfacial layer  15  and contact with the first intermediate layer  20 A. The constructing material of the interfacial layer  15  which potentially remains in the recesses of the rough electrical connector  24  is beneficial to connect the first intermediate layer  20 A and the second interfacial layer  20 B. 
     The foregoing description has been directed to the specific embodiments of this invention. It will be apparent; however, that other alternatives and modifications may be made to the embodiments without escaping the spirit and scope of the invention.