Abstract:
The invention is directed to an improvement of reliability in a chip-size package type semiconductor device and a manufacturing method thereof. A semiconductor substrate formed with a pad electrode is prepared, and a first protection layer formed of epoxy resin is formed on a front surface of the semiconductor substrate. Then, a via hole is formed from a back surface of the semiconductor substrate to the pad electrode. A wiring layer is then formed from the via hole of the semiconductor substrate, being electrically connected with the pad electrode through the via hole. Then, a second protection layer and a conductive terminal are formed, and the semiconductor substrate is separated into individual semiconductor dies by dicing.

Description:
CROSS-REFERENCE OF THE INVENTION  
       [0001]     This invention is based on Japanese Patent Application No. 2004-130676, the content of which is incorporated by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to a semiconductor device and a manufacturing method thereof, particularly to a package type semiconductor device and a manufacturing method thereof.  
         [0004]     2. Description of the Related Art  
         [0005]     CSP (Chip Size Package) has been pursued as a package type semiconductor device. The CSP means a small package having almost the same outside dimensions as those of a semiconductor die packaged in it.  
         [0006]     Conventionally, a BGA (Ball Grid Array) type semiconductor device has been known as a kind of CSP. In this BGA type semiconductor device, a plurality of ball-shaped conductive terminals made of a metal such as solder is arrayed in a grid pattern on one surface of the package, and electrically connected with the semiconductor die mounted on the other side of the package. A manufacturing method of the BGA type semiconductor device of the conventional art will be described with reference to drawings next.  FIG. 6  is a cross-sectional view showing the manufacturing method of the semiconductor device of the conventional art.  FIG. 7  is a cross-sectional view showing the semiconductor device and the manufacturing method thereof of the conventional art.  
         [0007]     First, as shown in  FIG. 6 , a pad electrode  51  is formed on a front surface of a semiconductor substrate  50  formed with an electronic device (not shown), extending from the electronic device. A support substrate  60  is further formed on the front surface of the semiconductor substrate  50 . This support substrate  60  is made of, for example, a silicon substrate, a glass substrate, a ceramic substrate, or a metal substrate, supporting the semiconductor substrate  50  and preventing the semiconductor substrate  50  from cracking or warping. Then, a back surface of the semiconductor substrate  50  supported by the support substrate  60  is ground. The semiconductor substrate  50  is thinned to have a predetermined thickness by this backgrinding process.  
         [0008]     Then, the semiconductor substrate  50  is formed with a via hole  52  penetrating from its back surface to the pad electrode  51 . A wiring layer  53  is formed in the via hole  52 , being electrically connected with the pad electrode  51 . Between the semiconductor substrate  50  and the wiring layer  53 , an insulation film (not shown) is formed. A protection layer  54  is formed on the wiring layer  53  so as to partially expose the wiring layer  53 . On the exposed wiring layer  53 , a conductive terminal  55  is formed, which can be connected with an external printed circuit board and so on.  
         [0009]     Next, as shown in  FIG. 7 , dicing is performed along a dicing line (not shown) to separate the semiconductor substrate  50  into semiconductor dies  50 A. Then, the support substrate  60  attached to the front surface of the semiconductor die  50 A is peeled off or removed, thereby completing the package type semiconductor device. The relevant technology is disclosed in the Japanese Patent Application Publication No. 2003-309221.  
         [0010]     In the manufacturing method of the package type semiconductor device described above, however, the support substrate  60  used for supporting the semiconductor substrate  50  in the backgrinding process or the forming process of the via hole  52  need be removed from the semiconductor die  50 A after the processes. This causes a problem of making a manufacturing method of the semiconductor device complex and increasing a manufacturing cost.  
         [0011]     Furthermore, on the front surface of the semiconductor device after the support substrate  60  is removed, the semiconductor die  50 A is not sufficiently protected (from moisture permeation from outside and the like). This causes a problem of decreasing reliability of the semiconductor die. Alternatively, the front surface of the semiconductor die  50 A (or the semiconductor substrate  50 ) is processed again for protecting the semiconductor die  50 A. This causes a problem of making the manufacturing method complex and increasing the manufacturing cost.  
       SUMMARY OF THE INVENTION  
       [0012]     The Invention provides a semiconductor device that includes a semiconductor die having a first surface and second surface, and a pad electrode formed on the first surface. A via hole is formed between the pad electrode and the second surface. The device also includes a first protection layer attached to the first surface so as to cover the pad electrode, an insulation film disposed on an inside wall of the via hole, and a metal portion disposed in the via hole to be in contact with the pad electrode.  
         [0013]     The invention also provides a method of manufacturing a semiconductor device. The method includes providing a semiconductor substrate having a first surface and a second surface and including a pad electrode formed on the first surface, forming a first protection layer on the first surface to cover the pad electrode, forming a via hole from the second surface to reach the pad electrode, forming an insulation film on a sidewall of the via hole, and filling at least partially the via hole having the insulation film with a metal so that the metal is contact with the pad electrode, and cutting the semiconductor substrate so as to produce a semiconductor device having a corresponding portion of the first protection layer as a protection element of the semiconductor device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a cross-sectional view showing a manufacturing method of a semiconductor device of an embodiment of the invention.  
         [0015]      FIG. 2  is a cross-sectional view showing the manufacturing method of the semiconductor device of the embodiment of the invention.  
         [0016]      FIG. 3  is a cross-sectional view showing the manufacturing method of the semiconductor device of the embodiment of the invention.  
         [0017]      FIG. 4  is a cross-sectional view showing the manufacturing method of the semiconductor device of the embodiment of the invention.  
         [0018]      FIG. 5  is a cross-sectional view showing the semiconductor device and the manufacturing method thereof of the embodiment of the invention.  
         [0019]      FIG. 6  is a cross-sectional view showing a manufacturing method of a semiconductor device of a conventional art.  
         [0020]      FIG. 7  is a cross-sectional view showing the semiconductor device and the manufacturing method thereof of the conventional art. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     A manufacturing method of a semiconductor device of an embodiment of this invention will be described in detail with reference to drawings. FIGS.  1  to  5  are cross-sectional views showing the manufacturing method of the semiconductor device of the embodiment. It is noted that FIGS.  1  to  5  show a portion near a dicing line (not shown) in a semiconductor substrate forming the semiconductor device.  
         [0022]     First, a semiconductor substrate  10  formed with an electronic device (not shown) is prepared as shown in  FIG. 1 . The electronic device (not shown) is formed on a front surface of the semiconductor substrate  10 . A pad electrode  11  is formed on the front surface of the semiconductor substrate  10 , extending from the electronic device (not shown), which is also formed on the front surface of the semiconductor substrate  10 . The pad electrode  11  is covered with a passivation film (not shown) made of silicon nitride or the like.  
         [0023]     A first protection layer  20  is formed over the front surface of the semiconductor substrate  10  including on the electronic device (not shown) and on the pad electrode  11 . The first protection layer  20  has a function of protecting the front surface of the semiconductor substrate  10  including the electronic device (not shown) and the pad electrode  11  and supporting the semiconductor substrate  10 . The first protection layer  20  has a predetermined thickness that can support the semiconductor substrate  10 . Although the predetermined thickness of the first protection layer  20  is not limited particularly, it is preferable to have the same thickness or substantially the same thickness as that of the semiconductor substrate  10 . Alternatively, the predetermined thickness can be the thickness that can support the semiconductor substrate  10  after a backgrinding process described below is performed to a back surface of the semiconductor substrate  10 .  
         [0024]     The first protection layer  20  is formed by coating epoxy resin, for example, so as to have the predetermined thickness. The first protection layer  20  can be formed of any material besides the epoxy resin even if the material is transparent, semi-transparent, or opaque, as long as the material can protect the front surface of the semiconductor substrate  10  including the electronic device (not shown) and the pad electrode  11  and support the semiconductor substrate  10 .  
         [0025]     For example, the first protection layer  20  can be formed of a material of a resist layer used for patterning and the like in a general manufacturing method of a semiconductor device. In this case, the first protection layer  20  and the resist layer can be formed of the same material. This enables the formation of the first protection layer  20  without making a manufacturing process complex and with minimizing a manufacturing cost.  
         [0026]     Next, a protection tape  21  formed of a conductive material is attached to the front surface of the first protection layer  20  as shown in  FIG. 2 . This protection tape  21  is provided for keeping the semiconductor substrate  10  on a conveying device (not shown) such as an electrostatic chuck by electrostatic attachment when the semiconductor substrate  10  is moved or inverted by the conveying device (not shown). The protection tape  21  can be omitted when the semiconductor substrate  10  is moved or inverted by a mechanical conveying device such as a clamper.  
         [0027]     Then, by the conveying device (not shown), the front and back surfaces of the semiconductor substrate  10  are inverted so that a process can be performed to the back surface of the semiconductor substrate  10 , as shown in  FIG. 3 . Then, the back surface of the semiconductor substrate  10  is ground to have a predetermined thickness. That is, the backgrinding process is performed. In this process, since the semiconductor substrate  10  is protected and supported by the first protection layer  20  formed on the front surface thereof, cracking or warping of the semiconductor substrate  10  can be minimized even in a case where the thickness of the semiconductor substrate  10  is 130 μm or less, for example, when the backgrinding process is performed thereto. Furthermore, deterioration of electric characteristics of the electronic device (not shown) formed on the front surface of the semiconductor substrate  10  can be minimized.  
         [0028]     Next, a resist layer  30  is formed on the back surface of the semiconductor substrate  10 . The resist layer  30  has an opening  30 a on a part of the back surface of the semiconductor substrate  10  corresponding to the pad electrode  11 . Then, the semiconductor substrate  10  is etched using this resist layer  30  as a mask. By this process, a via hole  12  is formed penetrating the semiconductor substrate  10  from its back surface to the pad electrode  11 .  
         [0029]     Then, an oxide film INS is formed on a sidewall of the via hole  12  and on the back surface of the semiconductor substrate  10 , exposing a bottom portion of the via hole  12 , as shown in  FIG. 4 . Then, a wiring layer  13  formed of, for example, metal such as Cu (copper) is formed on a region from the via hole  12  to the back surface of the semiconductor substrate  10 . This wiring layer  13  is electrically connected with the pad electrode  11  exposed at the bottom portion of the via hole  12 . Alternatively, the wiring layer  13  can be formed only in the via hole  12  without extending to the back surface of the semiconductor die.  
         [0030]     Next, a second protection layer  14  is formed over the back surface of the semiconductor substrate  10  including on the wiring layer  13 . Then, a predetermined part of the second protection layer  14  is selectively removed to form an opening  14   a  exposing a part of the wiring layer  13  and to remove the second protection layer  14  in a region near the dicing line (not shown). Then, a conductive terminal  15  for connecting the semiconductor device to an external printed circuit board and the like is formed on the wiring layer  13  exposed at the opening  14   a.  It is noted that the semiconductor device of the embodiment is not necessarily of BGA type, and the conductive terminal  15  can be omitted when the semiconductor device is of LGA (land grid array) type.  
         [0031]     Lastly, a dicing is performed along the dicing line (not shown) and the protection tape  21  is peeled off, thereby completing package type semiconductor devices each formed of a semiconductor die  10 A, as shown in  FIG. 5 .  
         [0032]     In this embodiment, by forming the first protection layer  20  on the front surface of the semiconductor die  10 A, the semiconductor die  10 A (the semiconductor substrate  10  in the manufacturing process) can be supported and protected as described above. Particularly, in a case where the semiconductor die  10 A is formed having a small thickness (e.g. 130 μm or less), the first protection layer  20  effectively functions as a support layer necessary in the backgrinding process.  
         [0033]     Furthermore, since the first protection layer  20  has a function of protecting the semiconductor die  10 A, the first protection layer  20  need not be removed in the manufacturing process. Therefore, the manufacturing process of the package type semiconductor device can be performed more simply than conventional, so that the manufacturing cost can be minimized. Furthermore, since the front surface of the semiconductor die  10 A is protected by the first protection layer  20 , outside moisture can be prevented from permeating the semiconductor die  10 A through the front surface.  
         [0034]     As a result, in the package type semiconductor device and the manufacturing method thereof, the reliability can be improved without making the manufacturing process complex and with minimizing the manufacturing cost.