Abstract:
A method of manufacturing semiconductor chips includes adhering a sheet that is to be tensioned to a reverse side of a semiconductor wafer on a front side of which an integrated circuit has been formed; separating individual semiconductor chips from the semiconductor wafer by dicing the semiconductor wafer from the front side along dicing lines; applying a sealing resin layer of an uncured sealing resin on upper surfaces of the semiconductor chips and in gaps between adjacent semiconductor chips, with the individual semiconductor chips joined by the sheet, thereby sealing the semiconductor chips; and tensioning the sheet, thereby dividing the uncured sealing resin layer into separate pieces along the dicing lines.

Description:
FIELD OF THE INVENTION 
     The present invention relates a method of manufacturing semiconductor chips by which reliable semiconductor chips can be manufactured easily, at a low cost, and with a high chip yield. 
     BACKGROUND OF THE INVENTION 
     In order to advance the ability to make portable electronic equipment, such as digital video cameras, digital cellular telephones, notebook personal computers, and the like, more compact, thinner, and lighter, an important aspect is to improve the surface packaging density of electronic parts within the equipment. For the packaging of semiconductor chips which are one type of electronic part, various SOPs (Small Outline Packages), whose outer configuration dimensions are close to the dimensions of a chip main body due to contrivances made with respect to the internal structure of the package, have been proposed. 
     One example of a conventional method of manufacturing such a SOP will be described with reference to FIG. 7A to FIG.  7 D. First, a semiconductor wafer  101 , for which all of the integrated circuit forming processes have been completed, is adhered onto a scribe sheet  201  (see FIG. 7A) Next, from the electrode surface side of the semiconductor wafer, by using a dicing saw  301 , the semiconductor wafer is cut along dicing lines  102  into individual semiconductor chips  101   a  (see FIG.  7 B). 
     After the cutting of the semiconductor wafer along the dicing lines  102  into the individual semiconductor chips  101   a  is finished, with the semiconductor chips  101   a  still adhered on the scribe sheet  201 , the upper surfaces of the semiconductor chips  101   a  and the gaps between adjacent semiconductor chips  101   a  are sealed by a sealing resin  104  (see FIG.  7 C). 
     After the sealing resin  104  has been cured, a second dicing is carried out along the previous dicing lines, but at a width B which is narrower than the previous dicing width A. The semiconductor chips  101   a , which are made integral through the sealing resin  104 , are cut into the individual semiconductor chips  101   a  (see FIG.  7 D). 
     However, in the above-described method, because a total of two dicings are required at the time of semiconductor wafer separation and sealing resin separation, a problem arises in that the manufacturing cost is high. Further, after dicing the wafer, in order to carry out the second dicing at the width B which is narrower than the wafer dicing width A, the dicing width A for the time of wafer dicing must be made large. A problem arises in that the effective number of chips which can be obtained from one semiconductor wafer is low, and the chip yield is low. 
     Furthermore, because dicing is carried out after resin sealing, when the entire surface is merely covered by the sealing resin, the positions of the dicing lines are unclear, the dicing lines cannot be directly confirmed, and it is difficult to improve the precision of dicing. Thus, a transparent resin must be used as the sealing resin, or marks must be provided in advance on extensions of the dicing lines. 
     Moreover, in the technique for carrying out dicing after resin sealing, at the time of dicing the sealing resin, the interface between the sealing resin and the semiconductor chip separates, and a problem arises in that the reliability of the semiconductor chip deteriorates. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method of manufacturing semiconductor chips in which, by a single dicing, reliable semiconductor chips can be manufactured easily and at low cost and at a high chip yield. 
     The method of manufacturing semiconductor chips according to one aspect of the invention comprises the steps of: adhering a sheet that is to be drawn to a reverse side of a semiconductor wafer on which an integrated circuit has been formed; separating individual semiconductor chips from the semiconductor wafer by dicing the semiconductor wafer from a front side along dicing lines; providing a sealing resin layer formed from an uncured sealing resin on upper surfaces of the semiconductor chips and in gaps between adjacent semiconductor chips, with the individual semiconductor chips maintained in a collected state, thereby sealing the semiconductor chips; and drawing the sheet, thereby separating the uncured sealing resin along the dicing lines. 
     According to the above-mentioned aspect, at the time when the resin filled on the diced semiconductor chips is in an uncured state, the sheet is drawn in a two dimensional plane with the semiconductor chips adhered on the sheet. In this way, the gaps between the semiconductor chips widen, and the sealing resin, which is filled into the gaps between the semiconductor chips and which is in an uncured state, is cut. The semiconductor chips, which were integral through the sealing resin, are separated into individual semiconductor chips. 
     The method of manufacturing semiconductor chips according to another aspect of the invention comprises the steps of: adhering a sheet that is to be drawn to a reverse side of a semiconductor wafer on which an integrated circuit has been formed; separating individual semiconductor chips from the semiconductor wafer by dicing the semiconductor wafer from a front side along dicing lines; providing a sealing resin layer formed from an uncured sealing resin on upper surfaces of the semiconductor chips and in gaps between adjacent semiconductor chips, with the individual semiconductor chips maintained in a collected state, thereby sealing the semiconductor chips transforming the uncured sealing resin into a semi-cured state; and drawing the sheet, thereby separating the sealing resin in the semi-cured state along the dicing lines. 
     According to the above-mentioned aspect, at the time when the resin filled on the diced semiconductor chips is in a semi-cured state after a preliminary curing, the sheet is drawn in a two dimensional plane with the semiconductor chips adhered on the sheet. In this way, the gaps between the semiconductor chips widen, and the sealing resin, which is filled into the gaps between the semiconductor chips and which is in a semi-cured state, is cut. The semiconductor chips, which were integral through the sealing resin, are separated into individual semiconductor chips. 
     Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A to FIG. 1F are sectional views for explaining the method of manufacturing semiconductor chips according to a first embodiment of the present invention; 
     FIG. 2 is a schematic perspective view showing a process of dicing a semiconductor wafer adhered on a scribe sheet; 
     FIG. 3 is a schematic perspective view showing a state in which a scribe sheet is drawn; 
     FIG. 4A to FIG. 4E are sectional views for explaining the method of manufacturing semiconductor chips according to a second embodiment of the present invention; 
     FIG. 5A to FIG. 5E are sectional views for explaining the method of manufacturing semiconductor chips according to a third embodiment of the present invention; 
     FIG. 6 is an enlarged sectional view showing a peripheral section of a bump of a semiconductor chip manufactured by the third embodiment of the present invention; and 
     FIG. 7A to FIG. 7D are sectional views for explaining the method of manufacturing semiconductor chips according to a conventional technique. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the method of manufacturing semiconductor chips relating to the present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 1A to FIG. 1F are sectional views for explaining the method of manufacturing semiconductor chips according to the first embodiment of the present invention. 
     The scribe sheet  201 , which is for assisting in wafer division and which is made from a synthetic resin which has an extensibility, is adhered to the reverse surface of the semiconductor wafer  101  at which all integrated circuit forming processes have been completed (see FIG.  1 A). Next, from the electrode surface side of the semiconductor wafer  101 , by using the dicing saw  301 , the semiconductor wafer  101  is cut along the dicing lines  102  into the individual semiconductor chips  101   a  (see FIG.  1 B). FIG. 2 is a perspective view of the entire semiconductor wafer at the time of the semiconductor wafer cutting process. 
     After the cutting of the semiconductor wafer along the dicing lines  102  into the individual semiconductor chips  101   a  is finished, with the semiconductor chips  101   a  still adhered on the scribe sheet  201 , the uncured sealing resin  104  is applied. Namely, by applying the sealing resin  104 , while the state in which the individual semiconductor chips are collected together is maintained by the scribe sheet  201 , the sealing resin layer  104  is formed on the upper surfaces of the semiconductor chips  101   a  and in the gaps between adjacent semiconductor chips  101   a  (see FIG.  1 C). 
     A thermosetting resin, a UV-setting resin or the like, which are generally used as sealing materials for semiconductor chips, can be used, without any particular limitation, as the sealing resin  104 . As needed, by a curing method such as heating, ultraviolet irradiation, or the like which corresponds to the type of the sealing resin  104 , the uncured sealing resin  104  is set in a semi-cured state (see FIG. 1D) Here, the semi-cured state may be a hardness of a degree such that, when the scribe sheet  201  is drawn in a later process, the sealing resin  104  does not peel off from the semiconductor chips  101   a  and cracks do not form in the sealing resin  104 . 
     With the semiconductor chips  101   a  adhered on the scribe sheet  201 , the scribe sheet  201  is drawn in a two dimensional plane. FIG. 3 is a perspective view of the entire semiconductor wafer at the time of drawing the scribe sheet. By drawing the scribe sheet  201 , the gaps between the semiconductor chips  101   a  are widened, and the sealing resin  104  filled into the gaps between the semiconductor chips  101   a  is cut. The semiconductor chips  101   a , which were integral through the sealing resin  104 , are separated into the individual semiconductor chips  101   a  (see FIG.  1 E). 
     By setting the semi-cured sealing resin  104  in a cured state by applying a curing method such as heating, ultraviolet irradiation, or the like which corresponds to the type of the sealing resin  104 , the semiconductor chips are completed (see FIG.  1 E). Due to the scribe sheet  201  being drawn even further, the completed semiconductor chips can be easily peeled off from the scribe sheet  201  (see FIG. 1F) 
     In this way, according to the first embodiment, the semiconductor chips are separated into the individual semiconductor chips due to the sealing resin being filled on the individually separated semiconductor chips and the scribe sheet  201  being drawn when the sealing resin is in a semi-cured state. Thus, even if dicing is not carried out again after dicing the semiconductor wafer, the semiconductor chips can easily be separated into the individual semiconductor chips, and therefore, costs accompanying dicing can be decreased. Further, because there is no need to set the dicing width wide, the chip yield can be increased. Moreover, because there is no cutting in the state in which the semiconductor chips and the sealing resin are joined together, the risks of the sealing resin being peeled off from the semiconductor chips and the sealing resin cracking can be kept to a minimum. 
     The second embodiment of the present invention will now be described. In the first embodiment, after dicing the semiconductor wafer and sealing the chips, in that state, the scribe sheet  201  is drawn and the semiconductor chips are separated into the individual semiconductor chips  101   a . However, the second embodiment is characterized in that, after sealing the chips, grooves are formed in advance along dicing lines in the surface of the sealing resin before the semiconductor chips are separated. 
     FIG. 4A to FIG. 4E are sectional views for explaining the method of manufacturing semiconductor chips according to a second embodiment of the present invention. Numerals which are the same as those of the first embodiment denote the same structures. Note that, here, the processes after the sealing resin layer  104  is formed on the semiconductor chips will be described, and the processes up until before formation of the sealing resin layer  104  are omitted. 
     After the sealing resin layer  104  is formed (see FIG. 4A) by applying the uncured sealing resin  104  with the semiconductor chips  101   a  adhered on the scribe sheet  201 , grooves  104   a  along the dicing lines are formed by a tooling process or the like in the upper surface of the sealing resin layer  104  (see FIG.  4 B). Further, as needed, before forming the grooves, it is possible to carry out preliminary curing of the sealing resin layer  104  such that the sealing resin layer  104  is set in a semi-cured state. 
     With the semiconductor chips  101   a  adhered on the scribe sheet  201 , the scribe sheet  201  is drawn in a two dimensional plane. Due to the scribe sheet  201  being drawn, the gaps between the semiconductor chips  101   a  widen, and the sealing resin  104  filled into the gaps between the semiconductor chips  101   a  is cut. The semiconductor chips  101   a , which were integral through the sealing resin  104 , are separated into the individual semiconductor chips  101   a  (see FIG.  4 C). Here, because the grooves  104   a  are formed along the dicing lines in the upper surface of the sealing resin layer  104 , the semiconductor chips  101   a , which are made integral through the sealing resin, are easily separated along the dicing lines. 
     Due to the uncured or semi-cured sealing resin  104  being set in a cured state by applying a curing method such as heating, ultraviolet irradiation, or the like which corresponds to the type of the sealing resin  104 , the semiconductor chips are completed (see FIG.  4 D). Due to the scribe sheet  201  being drawn further, the completed semiconductor chips can be easily peeled off from the scribe sheet  201  (see FIG.  4 E). Note that the method of leading the electrodes to the exterior can be carried out by grinding or polishing of the electrode surface of the semiconductor. 
     In this way, in the second embodiment, because grooves along the dicing lines are formed in the upper surface of the sealing resin layer  104 , the semiconductor chips  101   a , which are made integral through the sealing resin, are easily separated along the dicing lines when the scribe sheet is drawn. Accordingly, the separated configurations of the semiconductor chips  101   a  can be stabilized more. Further, the risks of the sealing resin peeling off from the semiconductor chips and the sealing resin cracking can be decreased even more. 
     The third embodiment of the present invention will now be described. The third embodiment is characterized in that an anisotropic conductive resin, in which conducive particles are dispersed in an insulating resin, is used as the sealing resin. By using such an anisotropic conductive resin and by compression molding semiconductor chips on whose surfaces bumps are formed in advance, electrode molding can be realized easily. 
     FIG. 5A to FIG. 5E are sectional views for explaining the method of manufacturing semiconductor chips according to a third embodiment of the present invention. 
     The semiconductor wafer  101 , for which all of the integrated circuit forming processes have been completed, is adhered onto the scribe sheet  201  which is formed from a synthetic resin having extensibility (see FIG.  5 A). In the third embodiment, bumps  105  are formed on a bonding pad (not illustrated) which is formed on the upper surface of the semiconductor wafer  101  at which an IC has been formed in advance. 
     From the electrode surface side of the semiconductor wafer, the semiconductor wafer is cut into the individual semiconductor chips  101   a  along the dicing lines  102  by the dicing saw  301  (see FIG.  5 B). 
     After the cutting of the semiconductor wafer into the individual semiconductor chips  101   a  along the dicing lines  102  is completed, with the semiconductor chips  101   a  adhered on the scribe sheet  201 , the uncured sealing resin  104  is applied (see FIG.  5 C). At the time the sealing resin is applied onto the semiconductor chips  101   a , the height of the sealing resin layer  104  is slightly higher than the height of the bumps  105 . 
     As shown in FIG. 6, an anisotropic conductive resin, in which minute conductive particles  103   a  are dispersed in an insulating resin  103   b , is used as the sealing resin  104 . Here, a thermosetting resin, UV-setting resin, or the like may be used, without any particular limitations, as the insulating resin  103   b . However, a thermosetting resin is preferably used, and in particular, a thermosetting epoxy resin is preferably used. 
     Examples of the conductive particles  103   a  which are dispersed in the insulating resin  103   b  are resin particles which are gold plated, nickel particles, nickel particles which are gold plated, silver particles which are coated with an insulating resin, and the like, and there are various particle diameters. By applying pressure, or pressure and temperature, to the anisotropic conductive resin, simultaneously with the adhesion, an electrically connected state in the longitudinal direction and an insulated state in the transverse direction can be obtained via the conductive particles  103   a  which are disposed between electrodes. 
     As needed, by a curing method such as heating, ultraviolet irradiation, or the like which corresponds to the type of the sealing resin  104 , the uncured sealing resin  104  is set in a semi-cured state (see FIG.  5 D). 
     With the semiconductor chips  101   a  adhered on the scribe sheet  201 , the scribe sheet  201  is drawn in a two dimensional plane. Due to the scribe sheet  201  being drawn, the gaps between the semiconductor chips  101   a  widen, and the sealing resin  104  filled into the gaps between the semiconductor chips  101   a  is cut. The semiconductor chips  101   a , which were integral through the sealing resin  104 , are separated into the individual semiconductor chips  101   a  (see FIG.  5 E). Next, due to the uncured or semi-cured sealing resin  104  being set in a cured state by applying a curing method such as heating, ultraviolet irradiation, or the like which corresponds to the type of the sealing resin  104 , the semiconductor chips are completed. 
     Due to the scribe sheet  201  being drawn further, the semiconductor chips  101   a  are peeled off from the scribe sheet  201 . According to the third embodiment, the sealing resin  104  is used. Thus, if the semiconductor chips  101   a  are peeled off the scribe sheet  201  and the sealing resin  104  (anisotropic conductive resin) after compression molding of the semiconductor chips  101   a  is cured, the conductive particles  103   a  are electrically connected to each other at the places of the bumps  105 . Thus, the bumps  105  can be made continuous with external wiring. Note that, in a case in which a thermosetting resin is used as the sealing resin, the sealing resin  104  in a semi-cured state may be cured by heating the semiconductor chips at the same time as the compression molding. 
     In this way, at the time of sealing the semiconductor chips having external connection terminals such as bumps or the like, by using an anisotropic conductive resin as the sealing resin, electrode molding can easily be realized merely by, for example, compression molding the semiconductor chips which have been separated into the individual chips. 
     As described above, according to one aspect of this invention, when the sealing resin filled onto the diced semiconductor chips is in an uncured state, the sheet is drawn in a two dimensional plane with the semiconductor chips adhered on the sheet. The semiconductor chips, which were integral through the sealing resin, are thereby separated into the individual semiconductor chips. Therefore, the semiconductor chips can be easily separated into the individual semiconductor chips, and costs accompanying dicing can be decreased. Further, because there is no need to set the dicing width to be wide, the chip yield can be increased. Further, because cutting is not carried out in a state in which the semiconductor chips and the sealing resin are joined, the risks that the sealing resin will peel off the semiconductor chips and that cracks will form in the sealing resin can be kept to a minimum. 
     According to another aspect, when the sealing resin filled onto the diced semiconductor chips is in a semi-cured state, the sheet is drawn in a two dimensional plane with the semiconductor chips adhered on the sheet. The semiconductor chips, which were integral through the sealing resin, are thereby separated into the individual semiconductor chips. Therefore, the semiconductor chips can be easily separated into the individual semiconductor chips, and costs accompanying dicing can be decreased. Further, because there is no need to set the dicing width to be wide, the chip yield can be increased. Further, because cutting is not carried out in a state in which the semiconductor chips and the sealing resin are joined, the risks that the sealing resin will peel off the semiconductor chips and that cracks will form in the sealing resin can be kept to a minimum. Moreover, grooves are formed in the surface of the sealing resin along the dicing lines before the sheet is drawn and the individual semiconductor chips are separated. Thus, the semiconductor chips are easily cut along the dicing lines when the sheet is drawn. Further, the resin configurations at the time of separating the semiconductor chips into the individual semiconductor chips can be stabilized more. 
     Furthermore, an anisotropic conductive resin, in which conductive particles are dispersed in an insulating resin, is used as the sealing resin. Therefore, there is the effect that electrode molding can be easily realized. 
     Moreover, due to semiconductor chips, on whose surfaces external connection terminals are provided in advance, being compression molded, there is the effect that the external connection terminals of the semiconductor chips can be made continuous with external wiring through the anisotropic conductive resin. 
     Furthermore, bumps are formed as the external connection terminals. Thus, there is the effect that, if the semiconductor chips are compression molded, the bumps can be easily made continuous with the external wiring through the anisotropic conductive resin. 
     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.