Abstract:
A reusable substrate structure and a method of handling the reusable substrate are disclosed. The reusable substrate structure comprises a substrate, at least one epitaxial layer and at least one inter layer. The method used in this invention is by employing a separating method in order to decompose the inter layer. Since the inter layer is decomposed, the substrate and the epitaxial layer will be separated. This achieves the goal of reusable substrate and then can save the material cost without additional wasting.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a reusable substrate structure, and a method to handle the reusable substrate. More particularly, it relates to the field of applying separating method in the inter layer in order to separate a substrate and an epitaxial layer, and then to achieve the goal of reusable substrate. 
       BACKGROUND OF THE INVENTION 
       [0002]    As is known in the art, the semiconductor manufacturing method is the process used to create the integrated circuits (IC) on the wafer. The processes contain several steps, included the photo-lithography, etching, physical vapor deposition (PVD) or chemical vapor deposition (CVD), polishing, ion-implanting and . . . etc. Generally, photo-lithography is the process used for transferring the geometric pattern onto the wafer. The physical vapor deposition (PVD) or chemical vapor deposition (CVD) is the process that used for adding another material onto the wafer. The etching process is used for removal material from the wafer. 
         [0003]    Overall, the semiconductor manufacturing method is the one combined with some of above in order to produce semiconductor devices. Since the devices have been completed, it will go on to the dicing step in order to do future assembly and testing. 
         [0004]    In recently years, the micro electromechanical (MEMS) technology, which refers to a process whereby micron-sized mechanical devices are fabricated on silicon wafers, has been developed after the semiconductor manufacturing methods. The micron-sized mechanical devices are included the optoelectronic components, sensor components and other micron-sized devices. 
         [0005]    However, there are still some difficulties are associated with fabricating a MEMS device. One of them is the entire substrate volume in a MEMS device, which is generally up to 80% or more. Therefore, a chemical mechanical polishing (CMP) are normally applied to polish the substrate in order to reduce the substrate thickness. This sometimes results in the substrate surface damage or debris. In this case, the substrate may hard to resist any chemical or physical impact and can not be used again. 
         [0006]    Another difficulty associated with fabricating a MEMS device is the high material cost. For example, the higher proportion cost for a light-emitting diode (LED) production is in its material cost, included the substrate, organic metals, special gases, epoxy resin and fluorescent powder, whereby the substrate used as function load here. To be more specific in the selected substrate type of optoelectronic field, the most popular used substrates are GaAs substrates, GaP substrates, sapphire substrates and Silicon carbide (SiC) substrates. The GaP substrates were used by the GaP, GaAsP binary or ternary light-emitting diodes (LED) or other optoelectronic components. The GaAs substrates were mainly used by AlGaAs, GaAsP, AlGaInP ternary or quaternary light-emitting diodes or optoelectronic components. The sapphire substrate and SiC substrates were mainly used in indium gallium nitride light-emitting diodes (LED) or photoelectric components. 
         [0007]    In generally, most of the substrate manufacturers have their attention on the type of substrate they are going to use, because the brightness, efficiency, and the life cycle time of the light-emitting devices were normally based on the choice of the substrate. The sapphire substrate is more general used in the GaN light-emitting diodes (LED) in production. The reason without choosing SiC substrate is because of its high price. 
         [0008]    However, the material prices for most substrates are still very high comparing to other costs. Therefore, the way to invent a reusable substrate can provide a method to lower down the cost and the application field for others can be then more extensive. 
         [0009]    The inventor of the present invention based on years of experience on related research and development of the optoelectronic component industry to invent a reusable substrate structure and a method of handling the reusable substrate. 
       SUMMARY OF THE INVENTION 
       [0010]    The object of the present invention is to provide a reusable substrate structure and a method of handing the reusable substrate in order to provide way of reusable substrate operation and then give advantage of lowering the cost of material down. 
         [0011]    According to the objective of the present invention, a reusable substrate structure has been presented, comprising a substrate; at least one epitaxial layer disposed over the substrate, wherein the epitaxial layer has at least one pattern on it; and at least one inter layer existed between the substrate and the epitaxial layer, wherein the inter layer was applied a separating methods to separate said substrate and said epitaxial layer. 
         [0012]    Furthermore, a method for handling the reusable substrate has also been presented which comprises: providing a substrate; forming an inter layer over said substrate; forming at least one epitaxial layer, wherein the epitaxial layer is fabricated at least one pattern; applying one cutting method to form at least one recess through said epitaxial layer to expose said inter layer, wherein the cutting is implemented along with the two different said pattern space; applying a one carrier to protect said pattern and provide stability and strength to the pattern function; and finally, applying an etchant, where the inter layer is decomposed by the etchant where starts from the contact areas between said recess and said inter layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a cross-sectional drawing of a reusable substrate structure; 
           [0014]      FIG. 2  is a cross-sectional drawing of the first example of a reusable substrate structure; 
           [0015]      FIG. 3  is a cross-sectional drawing of the second example of a reusable substrate structure; 
           [0016]      FIG. 4  is a cross-sectional drawing of the third example of a reusable substrate structure; and 
           [0017]      FIG. 5  shows a flow chart of the manufacturing process of the reusable substrate structure according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    To make it easier for our examiner to understand the objective of the invention, its innovative features and performance, a detailed description and technical characteristics of the present invention are described together with the drawings as following. 
         [0019]    Referring to  FIG. 1 , a cross-sectional drawing of a reusable substrate structure is illustrated. The reusable substrate structure comprises a substrate  11 , at least one epitaxial layer  12 , and at least one inter layer  13 . As is known in the art, the inter layer  13  can be fabricated over the substrate  11  by the Chemical vapor deposition (CVD) or physical vapor deposition (PVD). The epitaxial layer  12  over the substrate  11  is fabricated at least one pattern  121 , by the well-know technology of photolithography and etching process. Therefore, the inter layer  13  is formed between the substrate  11  and the epitaxial layer  12 . The material of inter layer  13  or the composition of inter layer  13  is different from the substrate  11  and the epitaxial layer  12  that the inter layer  13  can work as a separation interface. The carrier  14  mounts above the pattern  121 , where the pattern  121  are on the epitaxial layer  12 . The carrier  14  can work as a protection to the pattern  121  and provide stability and strength to the pattern  121  function. The separating method  15  can provide ways to decompose the inter layer  13  in order to separate the substrate  11  and the epitaxial layer  12 , where the material of inter layer  13  is different from the substrate  11  and the epitaxial layer  12 . 
         [0020]    The material of substrate  11  is one from varies of substrate type, included the sapphire substrate, GaAs substrate, SiC substrate, GaP substrate, ZnO substrate, InP substrate or Silicon Substrate. The pattern is formed for Integrated Circuit (IC). The epitaxial layer  12  contains at least one elements form the periodic table of group IIA, IIB, IIIA, IVA, VA and VIA, such as GaInP. The inter layer  13  comprise at least one group selected from Al(x)Ga(y)In(z)P, Al(x)Ga(y)As(z)P(v), Al(x)Ga(y)In(z)N, Al(x)Ga(y)In(z)Sb or Si(x)Ge(y)C(z). The group of Al(x)Ga(y)As is the most important in three elements alloy semiconductor because its lattice constant is small different from GaAs, therefore the Al(x)Ga(y)As can fabricate appropriately over the GaAs substrate. The carrier  14  can be polysilicon, glass, quartz, polymer, metal or any combination of the above mention carrier materials. 
         [0021]    The substrate  11  can comprise at least one layer of epitaxial. The separating method  15  can be one by etchant or one by reacted light. The reacted light can be a laser to give the sufficient energy to decompose the inter layer  13 . Or, the etchant can react with the inter layer  13 , and decompose the inter layer  13 . The etchant can be in a form of liquid or gas. Consequently, since the inter layer  13  is decomposed, the substrate  11  and the epitaxial layer  12  are separated. 
         [0022]    The carrier  14  has the character of penetration that the etchant can penetrate the carrier  14  to reach the inter layer  13 , and then decompose the inter layer  13 . As mention before that the material of a substrate  11  is different from the inter layer  13 , the reaction between the substrate  11  and the etchant is near to the ground, so that the substrate can be kept afterward. 
         [0023]    Referring to  FIG. 2 , it illustrates a cross-sectional drawing of the first example of a reusable substrate structure. In the preferred embodiment, the first example of a reusable substrate structure comprises a substrate  21 , at least one epitaxial layer  22 , a inter layer  23 , a carrier  24  and a laser  25 . As is known in the art, the inter layer  23  can be fabricated over the substrate  21  by the Chemical vapor deposition (CVD) or physical vapor deposition (PVD). The epitaxial layer  22  over the substrate  21  is fabricated at least one pattern  221 , by the well-know technology of photolithography and etching process. Therefore, the inter layer  23  is formed between the substrate  21  and the epitaxial layer  22 . The material of inter layer  13  is different from the substrate  21  and the epitaxial layer  22  that the inter layer  23  can work as a separation interface. The carrier  24  can work as a protection to the pattern  221  and provide stability and strength to the pattern  221  function. The separating method  25  can provide ways to decompose the inter layer  23  in order to separate the substrate  21  and the epitaxial layer  22 , where the material of inter layer  23  is different from the substrate  21  and the epitaxial layer  22 . The laser  25  can provide the sufficient energy to break off the binding energy of the inter layer  23 . Consequently, since the inter layer  23  is decomposed, the substrate  21  and the epitaxial layer  22  are separated. 
         [0024]    Referring to  FIG. 3 , it illustrates a cross-sectional drawing of the second example of a reusable substrate structure, according to an embodiment of the present invention. In the preferred embodiment, the second example of a reusable substrate structure comprises a GaAs substrate  31 , at least one GaAs epitaxial layer  32 , at least one GaInP inter layer  33 , a protection layer  34 , an etchant  35  and at least one cutting method  36 . As is known in the art, the GaInP inter layer  33  can be fabricated over the GaAs substrate  31  by the Chemical vapor deposition (CVD) or physical vapor deposition (PVD). The GaAs epitaxial layer  32  over the GaAs substrate  31  is fabricated at least one pattern  321 , by the well-know technology of photolithography and etching process. Therefore, the GaInP inter layer  33  is formed between the GaAs substrate  31  and the GaAs epitaxial layer  32 . The material of GaInP inter layer  33  is different from the GaAs substrate  31  and the GaAs epitaxial layer  32  that the GaInP inter layer  33  can work as a separation interface. 
         [0025]    A cutting method  36 , such as by diamond saw blade, laser, or etchant, is applied to form at least one recess  361  through GaAs epitaxial layer  32  to expose the GaInP inter layer  33 . Here, the recess  361  can be 100% through the GaInP inter layer  33  or less than 100%. The cutting is implemented along within the space between one of the pattern  321  and another pattern  321 . The protection layer  34  is needed when the etchant  35  impacts the pattern  321  or there is a reaction happened between the GaAs epitaxial layer  32  and the etchant  35 . On the other hand, the protection layer  34  does not have to apply when GaAs epitaxial layer  32  and the etchant  35  have no reaction. 
         [0026]    An etchant  35  is applied in order to decompose GaInP inter layer  33 . The decomposition starts from the contact areas between the recess  361  and the GaInP inter layer  33 . During the decomposition process, the GaAs substrate  31  can still keep remain without destruction because the impact from the etchant  35  (such as: HCl) is limited. Consequently, since GaInP inter layer  33  is decomposed, the GaAs substrate  31  and the GaAs epitaxial layer  32  are separated. Here, the etchant  35  takes HCl as an example because the HCl can decompose the GaInP inter layer  33 . 
         [0027]    A carrier, such as polysilicon, glass, polymer, or quartz, can be mounted on the GaAs epitaxial layer  32  or on the protection layer  34  to work as a protection to the pattern  321  and provide stability and strength to the pattern  321  function. The carrier is made by the small pore materials or the high porosity materials. The high porosity materials have the high penetrability that can give more contact area between the etchant  35  and the GaInP inter layer  33 , so that the etching speed can be increased. The small pore materials can be added one diversion hole or diversion channel on the carrier in order to increase the contact area between the etchant  35  and the GaInP inter layer  33 . 
         [0028]    The etchant  35  can be in a form of liquid or gas. The etchant  35  can be acid etchant or alkaline etchant. The acid etchant is selected from the group consisting of: sulfuric acid (H 2 SO 4 ), hydrochloric acid (HCl), Hydrofluoric acid (HF), Hydrogen cyanide (HCN), nitric acid (HNO 3 ), Acetic acid (CH 3 COOH), and Phosphoric acid (H 3 PO 4 ). The alkaline etchant is selected from the group consisting of: ammonium hydroxide (NH 4 OH), Potassium Hydroxide (KOH), Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH) 2 ), and Barium hydroxide (Ba(OH) 2 ). The gas etchant is selected from the group consisting atom of fluorine, chlorine, bromine, iodine, and sulfur. 
         [0029]    The hydrochloric acid (HCl) has the chemical reaction with the GaInP and the Ammonium hydroxide (NH 4 OH) has the chemical reaction with the GaAs. 
         [0030]    Referring to  FIG. 4 , it illustrates a cross-sectional drawing of the third example of a reusable substrate structure, according to an embodiment of the present invention. In the preferred embodiment, the third example of a reusable substrate structure comprises a GaAs substrate  41 , a GaAs inter layer  42 , a first GaInP epitaxial layer  43 , a carrier  44 , an etchant  45  and a laser  46 . The GaAs substrate  41  contains at least one layer of secondary GaInP epitaxial layer  411 . The GaAs inter layer  42  is deposited over the secondary GaInP epitaxial layer  411 . The first GaInP epitaxial layer  43  is over the GaAs inter layer  42 . The GaAs inter layer  42  is formed between the GaAs substrate  41  and the first GaInPs epitaxial layer  43 , where the material of GaAs inter layer  42  is different from the first GaInP epitaxial layer  43  and the secondary GaInP epitaxial layer  411 , that the GaAs inter layer  42  can work as a separation interface. 
         [0031]    The first GaInP epitaxial layer  43  can be fabricated at least one pattern  431  on it. A laser  46  is applied to form at least one recess  461  through the first GaInP epitaxial layer  43  to expose the GaAs inter layer  42 . Here, the recess  461  can be 100% through the GaAs inter layer  42  or less than 100%. The cutting is implemented along within the space between one of the pattern  431  and another pattern  431 . The carrier  44  is a high porosity material and the impact from the etchant  45  to the carrier  44  is limited, therefore, the high porosity material can increase the penetrability between the etchant  45  (such as, NH 4 OH) and the GaAs inter layer  42  that increased the etching speeds. The carrier  44  may applied on the first GaInP epitaxial layer  43  in the situations when the protection of the first GaInP epitaxial layer  43  are needed. 
         [0032]    The etchant  45  (such as, NH 4 OH) can penetrate through the carrier  44  to reach the recess  461  to decompose the GaAs inter layer  42 . After the GaAs inter layer  42  has been decomposed by etchant  45 , the second GaInP epitaxial layer  411  separate from the first GaInP epitaxial layer  43 . Besides, the second GaInP epitaxial layer  411  can be etched by the acid etchant (HCl) so as the second GaInP epitaxial layer  411  can be separated from the first GaAs substrate. Here, the etchant  45  take NaOH as an example because the alkaline etchant  45  can decompose the GaAs. Additionally, the GaAs substrate  41  can contain more layer of epitaxial layer. Here, the second GaInP epitaxial layer  411  is only as an example. 
         [0033]    If the first GaInP epitaxial layer  43  reacts with the etchant  45 , a protection layer (such as, photo resist) can be applied on the first GaInP epitaxial layer  43  and pattern  431  in order to avoid the damage from the etchant  45 , that can increase the stability and strength to the pattern  431  function. 
         [0034]    Referring to  FIG. 5 , it is a flow chart of the manufacturing process of the reusable substrate structure according to a preferred embodiment of the present invention. The method for handling the reusable substrate, comprising: 
         [0035]    Step  1 : providing a substrate; 
         [0036]    Step  2 : forming at least one inter layer over said substrate; 
         [0037]    Step  3 : forming at least one epitaxial layer, the epitaxial layer is fabricated at least one pattern; 
         [0038]    Step  4 : applying one separating method on inter layer, the inter layer is decomposed so that the substrate and the epitaxial layer are separated. 
         [0039]    After above working steps, the substrate keep remains and the epitaxial layer can still work for future device manufacturing. That achieves the goal of a reusable substrate and the cost can be therefore lowered down. 
         [0040]    While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures. 
         [0041]    In summation of the description above, the present invention is novel and useful and definite enhances the performance over the conventional structure and further complies with the patent application requirements and is submitted to the Patent and Trademark Office for review and granting of the commensurate patent rights