Abstract:
A method of separating semiconductor device structures comprises steps of providing a substrate having a first surface and a second surface opposite to the first surface; forming a plurality of semiconductor epitaxial stacks on the first surface; forming a patterned resist layer covering the semiconductor epitaxial stacks and exposing part of the first surface, or covering the second surface corresponding to the semiconductor epitaxial stacks; performing a physical etching process to directly server the substrate apart from an area of the first surface or the second surface not covered by the patterned resist layer; and separating the semiconductor epitaxial stacks to form a plurality of semiconductor device structures.

Description:
TECHNICAL FIELD 
     The disclosure relates to the semiconductor device structures and the separating methods thereof, especially relates to the semiconductor device structures with high light extraction efficiency and the separating methods thereof. 
     REFERENCE TO RELATED APPLICATION 
     This application claims the right of priority based on TW application Serial No. 100120295, filed on Jun. 9, 2011, and the content of which is hereby incorporated by reference in its entirety. 
     DESCRIPTION OF BACKGROUND ART 
     As the technology improves day by day, the semiconductor optoelectronic device makes large contribution in data transmission and in energy conversion. Take the systematic application as an example, the semiconductor optoelectronic device can be applied to the optical-fiber communication, the optics storage, and the military affairs. Classified by the way of conversion of the energy, the semiconductor optoelectronic device can be separated into three types: converting the electrical power into the light emission, such as the light-emitting diode and the laser diode; converting the light signal into the electrical power, such as the light detector; converting the light radiation energy into the electrical power, such as the solar cell. 
     For the semiconductor optoelectronic devices, the growth substrate plays a very important role. The essential semiconductor epitaxial structures which are used to form the semiconductor optoelectronic device are formed on the growth substrate. Therefore, how to choose a suitable growth substrate often becomes an important issue which could determine the quality of the semiconductor optoelectronic device. 
     However, sometimes a substrate suitable for device growth thereon is not a suitable substrate for device operation. Take the light emitting diode device for example, in the conventional red light emitting diode device manufacturing process, in order to improve the device growth quality, the opaque GaAs substrate which has the lattice constant close to that of the semiconductor epitaxial structure is often chosen to be the growth substrate. However, for the light emitting diode device which is operated to emit light, the opaque growth substrate degrades the light emitting efficiency during operation. 
     In order to satisfy the different requirements for the growth substrate and the operating substrate of the semiconductor optoelectronic device, the substrate transferring technology is developed. In other words, the semiconductor epitaxial structure grows from the growth substrate first, and the semiconductor epitaxial structure is transferred to the operating substrate for device operation later. Then, cutting and separating the semiconductor epitaxial structure to form the individual semiconductor optoelectronic devices after adhering the semiconductor epitaxial structure to the operating substrate. 
     The conventional method of cutting the growth substrate and separating the semiconductor epitaxial structure proceeds mainly by laser cutting. However, while cutting the growth substrate and separating the semiconductor epitaxial structure by laser, the opaque side product is formed because of the chemical reaction between the laser beam and the substrate and/or between the laser beam and the semiconductor epitaxial structure. The side product causes the degradation of the illumination efficiency of the semiconductor optoelectronic devices. If we remove the side products by the etchant, the surfaces of the semiconductor epitaxial structure can be destroyed simultaneously, and the yield of the structure goes down accordingly. Presently, how to cut the substrate and separate the semiconductor epitaxial structure effectively is one of the important research directions. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with the description above, the present disclosure provides a semiconductor device structure and the separating method thereof, especially relates to a semiconductor device structure with high light extraction efficiency and the separating method thereof. 
     A method of separating semiconductor device structures in accordance with one embodiment of the disclosure is disclosed, which includes providing a substrate comprising a first surface and a second surface opposite to the first surface; forming a plurality of semiconductor epitaxial stacks on the first surface; forming a patterned resist layer and exposing part of the first surface, or covering the second surface corresponding to the semiconductor epitaxial stacks; performing a physical etching process to directly server the substrate apart from an area of the first surface or the second surface not covered by the patterned resist layer; and separating the semiconductor epitaxial stacks to form a plurality of semiconductor device structures. 
     A semiconductor device structure in accordance with one embodiment of the disclosure is disclosed, which includes a substrate comprising a first surface and a plurality of sidewalls adjacent to the first surface; a semiconductor epitaxial stack layer formed on the first surface, comprising a first semiconductor material layer with a first electrical conductivity, a second semiconductor material layer with a second electrical conductivity, and an active layer positioned between the first semiconductor material layer and the second semiconductor material layer; wherein all of the sidewalls are roughened by microblasting. 
     A package type semiconductor device structure in accordance with another embodiment of the disclosure is also disclosed, which includes a substrate comprising a first surface, a second surface opposite to the first surface, and a plurality of the first sidewalls adjacent to the first surface; a semiconductor epitaxial stack layer formed on the first surface, comprising a first semiconductor material layer with a first electrical conductivity, a second semiconductor material layer with a second electrical conductivity, an active layer positioned between the first semiconductor material layer and the second semiconductor material layer, and a third surface facing the first surface and a plurality of the second sidewalls adjacent to the third surface; and a protecting layer covering the second surface, the first sidewalls, and the second sidewalls. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a flow chart of separating the semiconductor device structures in accordance with an embodiment of the disclosure; 
         FIG. 2A  illustrates a structure of the first step of separating the semiconductor device structures in accordance with an embodiment of the disclosure; 
         FIG. 2B  illustrates a structure of the second step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 2C  illustrates a structure of the third step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 2D  illustrates a structure of the fourth step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 2E  illustrates a structure of the fifth step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 2F  illustrates a structure of the sixth step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 2G  illustrates a structure of the seventh step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 3A  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3B  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3C  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3D  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3E  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3F  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3G  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 3H  illustrates a top view of a substrate of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 4  illustrates a flow chart of separating the semiconductor device structures in accordance with another embodiment of the disclosure; 
         FIG. 5A  illustrates a structure of the first step of separating the semiconductor device structures in accordance with another embodiment of the disclosure; 
         FIG. 5B  illustrates a structure of the second step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 5C  illustrates a structure of the third step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 5D  illustrates a structure of the fourth step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 5E  illustrates a structure of the fifth step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 5F  illustrates a structure of the sixth step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 5G  illustrates a structure of the seventh step of separating the semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 6A  illustrates a side view of the semiconductor device structure in accordance with an embodiment of the disclosure; 
         FIG. 6B  illustrates a side view of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 7A  illustrates a structure of the semiconductor device structure in accordance with the embodiment of the disclosure; 
         FIG. 7B  illustrates an enlarged side view of the semiconductor device structure as shown in  FIG. 7A ; 
         FIG. 8  illustrates a structure of the flip-chip semiconductor device structure in accordance with another embodiment of the disclosure; 
         FIG. 9A  illustrates a structure of the first step of separating the package type semiconductor device structures in accordance with another embodiment of the disclosure; 
         FIG. 9B  illustrates a structure of the second step of separating the package type semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 9C  illustrates a structure of the third step of separating the package type semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 9D  illustrates a structure of the fourth step of separating the package type semiconductor device structures in accordance with the embodiment of the disclosure; 
         FIG. 9E  illustrates a structure of the fifth step of separating the package type semiconductor device structures in accordance with the embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a flow chart of separating the semiconductor device structures such as the light emitting diode devices is disclosed in accordance with the first embodiment in the disclosure.  FIGS. 2A to 2G  illustrate the structures of each step in the flow chart. 
     Referring to  FIG. 2A , the first step is to provide a substrate  101 . For example, the substrate  101  could be a GaAs substrate in the present embodiment. The material of the substrate  101  could also be but not limited to SiC, AlGaAs, GaAsP, ZnSe, group III nitride (such as GaN), Sapphire, Si, spinel, ZnO, or glass. Then, as shown in  FIG. 2B , forming a semiconductor epitaxial stack layer  10  on the substrate  101  by epitaxial growth or by bonding method. Take the light emitting diode devices as shown in the embodiment for example, the semiconductor epitaxial stack layer  10  includes a buffer layer  103 , an n-type semiconductor material layer  105 , a light-emitting layer  107 , a p-type semiconductor material layer  109 , a window layer  111 , wherein the n-type semiconductor material layer  105  and the p-type semiconductor material layer  109  could be but not limited to made of AlGaInP series material or the group III nitride series material. The structure of the light-emitting layer  107  could be but not limited to a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), a single quantum well (SQW), or a multi quantum well (MQW) structure. The window layer  111  could be made of GaP. Besides, in order to enhance the current spreading efficiency, a transparent conductive layer (not shown) could also be optionally formed on the semiconductor epitaxial stack layer  10 , and the transparent conductive layer could be made of ITO, IZO, ZnO, CTO, In 2 O 3 , SnO 2 , MgO, CdO, or other transparent conductive oxide material. The semiconductor epitaxial stack layer  10  could be formed on the substrate  101  by the method such as metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), liquid phase epitaxy (LPE), vapour phase epitaxy (VPE), direct bonding, bonding with connecting layer(s), eutectic bonding, and other conventional techniques. The connecting layer is omitted and not shown in the figures. Then, as shown in  FIG. 2C , by the conventional photolithography and etching technology, the semiconductor epitaxial stack layer  10  is divided into a plurality of divided semiconductor epitaxial stacks  11 , the n electrodes  112  are formed on the n-type semiconductor material layers  105 , and the p electrodes  114  are formed on the p-type semiconductor material layers  109 . Then, as shown in  FIG. 2D , a protecting layer  111  covering the surfaces of the plurality of the divided semiconductor epitaxial stacks  11  is formed in order to protect the divided semiconductor epitaxial stacks from being damaged by the following manufacturing processes. Wherein, the structure of the protecting layer  111  could be a photoresist layer and could be removed by certain weak basic solution in the following step. Then, as shown in  FIG. 2E , forming a patterned dry film photoresist  113  on the backside surface of the substrate  101 . In order to protect part of the backside surface of the substrate  101  from being damaged by the microblasting method, the dry film photoresist  113  is preferred to be the resin composite with higher resilience. The dry film photoresist  113  is formed on part of the backside of the substrate  101  and exposes part of the backside surface corresponding to the space  115  between the divided semiconductor epitaxial stacks  11 . Then, as shown in  FIG. 2F , by taking advantage of the dry film photoresist  113  to be the protecting layer, bombarding the backside surface of the substrate  101  by the microblasting method. Because the hardness of the microblasting particles  300  is larger than the hardness of the substrate  101 , the part the backside surface of the substrate  101  not covered by the dry film photoresist  113  is eroded by the microblasting method, which is a physical etching method, and the crack and the depression are formed accordingly. Wherein, by selecting the sizes and the materials of the microblasting particles  300 , the ratio the etching rate the microblasting particles  300  etching the substrate over the etching rate the microblasting particles  300  etching the patterned photoresist could be larger than 10. Finally, after the backside surface of the substrate  101  is etched by the microblasting particles  300  over a period of time, the substrate  101  is punched through. By removing the protecting layer  111  and the dry film photoresist  113 , the semiconductor epitaxial stacks  11  are divided into a plurality of semiconductor device structures  11 ′, as shown in  FIG. 2G . 
     Noticeably, the shapes of the semiconductor device structures (the top view of the substrates and/or the semiconductor epitaxial stacks) formed in the embodiment, considering the light extraction efficiency, are not limited to the conventional squares or rectangles. By the patterned photoresist and the microblasting technology, the shapes of the semiconductor device structures (the top view of the substrates and/or the semiconductor epitaxial stacks) could be triangles, irregular quadrangles, polygons with more than five sides, circles, ellipses, or other shapes with part of curved boundaries, as shown in  FIGS. 3A to 3H . The person with ordinary skills in the art could realize the shapes of the structures are not limited to what mentioned above. 
       FIG. 4  shows another flow chart of separating the semiconductor device structures such as the light emitting diode devices is disclosed in accordance with the second embodiment in the disclosure.  FIGS. 5A to 5G  illustrate the structures of each step in the flow chart. 
     Referring to  FIG. 5A , the first step is to provide a substrate  201 . For example, the substrate  201  could be a GaAs substrate in the present embodiment. The material of the substrate  201  could also be but not limited to SiC, AlGaAs, GaAsP, ZnSe, group  111  nitride (such as GaN), Sapphire, Si, spinel, ZnO, or glass. Then, as shown in  FIG. 5B , forming a semiconductor epitaxial stack layer  20  on the first surface  219  of the substrate  201  by epitaxial growth or by bonding method. Take the light emitting diode devices as shown in the embodiment for example, the semiconductor epitaxial stack layer  20  includes a buffer layer  203 , an n-type semiconductor material layer  205 , a light-emitting layer  207 , a p-type semiconductor material layer  209 , a window layer  211 , wherein the n-type semiconductor material layer  205  and the p-type semiconductor material layer  209  could be but not limited to made of the AlGaInP series material or the group III nitride series material. The structure of the light-emitting layer  207  could be but not limited to a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), a single quantum well (SQW), or a multi quantum well (MQW) structure. The window layer  211  could be made of GaP. Besides, in order to enhance the current spreading efficiency, a transparent conductive layer (not shown) could also be optionally formed on the semiconductor epitaxial stack layer  20  and the transparent conductive layer could be made of ITO, IZO, ZnO, CTO, In 2 O 3 , SnO 2 , MgO, CdO, or other transparent conductive oxide material. The semiconductor epitaxial stack layer  20  could be formed on the first surface of the substrate  201  by the method such as metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), liquid phase epitaxy (LPE), vapour phase epitaxy (VPE), direct bonding, bonding with connecting layer(s), eutectic bonding, and other conventional techniques. The connecting layer is omitted and not shown in the figures. Then, as shown in  FIG. 5C , by the conventional photolithography and etching technology, the semiconductor epitaxial stack layer  20  is divided into a plurality of divided semiconductor epitaxial stacks  21 , the n electrodes  212  are formed on the n-type semiconductor material layers  205 , and the p electrodes  214  are formed on the p-type semiconductor material layers  209  or the window layers  211  respectively. Then, as shown in  FIG. 5D , a patterned dry film photoresist  213  covering the surfaces of the divided semiconductor epitaxial stacks  21  is formed to be a protecting layer, and the materials could be resin composite and so on. Meanwhile, part of the first surfaces  219  where no semiconductor epitaxial stacks  21  located is exposed. Then, as shown in  FIG. 5E , a supporting layer  215  is formed on the backside surface of the substrate  201  for supporting and holding the whole structure after the substrate  201  is separated. The material of the supporting layer  215  could be the UV adhesive tape, the acrylic tape, the acid-base resist tape, the heat resist tape, or the ordinary blue tape and so on. Then, as shown in  FIG. 5F , bombarding the first surface of the substrate  201  by the microblasting method. Because the hardness of the microblasting particles  500  is larger than the hardness of the substrate  201 , the part the first surface  219  of the substrate  201  not covered by the dry film photoresist  213  is eroded by the microblasting method, which is a physical etching method, and the crack and the depression are formed accordingly. Wherein, by selecting the sizes and the materials of the microblasting particles  500 , the ratio the etching rate the microblasting particles  500  etching the substrate  201  over the etching rate the microblasting particles  500  etching the patterned photoresist  213  could be larger than 10. Finally, after the first surface  219  of the substrate  201  is etched by the microblasting particles  500  over a period of time, the part the substrate  201  not covered by the dry film photoresist  213  is punched through and the semiconductor epitaxial stack layer  21  is separated into a plurality of divided semiconductor epitaxial structures  21 ′ which are adhered on the supporting layer  215 . By removing the supporting layer  215  and the dry film photoresist  213 , a plurality of semiconductor device structures  21 ′ are formed as shown in  FIG. 5G . 
     Similarity, the shapes of the semiconductor device structures (the top view of the substrates and/or the semiconductor epitaxial stacks) formed in the embodiment, considering the light extraction efficiency, are not limited to the conventional squares or rectangles. By the patterned photoresist and the microblasting technology, the shapes of the semiconductor device structures (the top view of the substrates and/or the semiconductor epitaxial stacks) could be triangles, irregular quadrangles, polygons with more than five sides, circles, ellipses, or other shapes with part of curved boundaries, as shown in  FIGS. 3A to 3H . The person with ordinary skills in the art could realize the shapes of the structures are not limited to what mentioned above. 
     Besides, as shown in  FIGS. 6A and 6B , because the microblasting process is a kind of physical etching method, most of the sidewalls  117  and  217  of the substrate of the semiconductor device structures  11 ′ and  21 ′ are rough because of the bombardment of the microblasting particles. The surface roughness ranges from 1 micrometer to 40 micrometers in accordance with the different radius of the microblasting particles. Because of the rough surfaces on the substrate, a larger portion of the light emitted from the semiconductor device structures  11 ′ and  21 ′ could be extracted to outside through different extraction angles of the substrate so a higher light extraction efficiency could be achieved. As shown in  FIG. 7A , the surface roughness formed by the bombardment of the microblasting particles of the sidewall  317  of the semiconductor device structure  31 ′ is disclosed.  FIG. 7B  is the local enlarged view of the sidewall  317  of the substrate  31 ′. 
     Furthermore, the separation methods of the semiconductor device structures in the present disclosure are also applicable to the flip-chip light emitting diode devices  40  as illustrated in  FIG. 8 . Because the light emitting surface of the flip-chip light emitting diode device  40  is opposite to the surface where the semiconductor epitaxial stacks  41  is formed on, in order to enhance the light extraction efficiency of the flip-chip light emitting devices  40 , the roughening process could be applied to the light emitting surface  42  of the substrate which is opposite to the surface where the semiconductor epitaxial stacks  41  is formed on as shown in  FIG. 8 . 
     Besides, in order to enhance the protection for the devices, after the semiconductor device structures  41 ′ are formed, the divided semiconductor device structures are adhered to a temporary substrate  301  by a flip-chip method. The material of the temporary substrate could be silicone resin as shown in  FIG. 9A . Then, as shown in  FIG. 9B , covering all the substrate surfaces and sidewalls of the semiconductor device structures  41  with the liquid silicone resin  119  by the spin coating method, and curing the silicone resin  119  by heating. Then, as shown in  FIG. 9C , forming the patterned dry film photoresist  413  on the backside surfaces of the temporary substrate or the surfaces of the silicone resin  119  corresponding to where the semiconductor device structures located. Finally, the cured thermosetting resin is divided by the microblasting method to separate the semiconductor device structures again. As shown in  FIG. 9D , when the final structures removed from the temporary substrate, the structure could be the same as the package type semiconductor device structure  41 ″ which is protected by the surrounding resin shown in  FIG. 9E . 
     The embodiments mentioned above are used to describe the technical thinking and the characteristic of the invention and to make the person with ordinary skill in the art to realize the content of the invention and to practice, which could not be used to limit the claim scope of the present application. Any modification or variation according to the spirit of the present application should also be covered in the claim scope of the present disclosure.