JP2010238901A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicon substrate having a thickness thinner than before when manufacturing a semiconductor device having a structure which covers the side surface of the silicon substrate with a sealing film and covers the lower surface of the substrate with a lower layer protection film. <P>SOLUTION: A semiconductor wafer 21 except for its periphery is thinned by steps of: forming the sealing film 11 on the wafer 21, and forming a recessed portion 31 in the wafer by grinding its bottom surface side except for its periphery using a rotational grinding stone 30. In this case, the presence of the sealing film 11 and the removal of the periphery of the wafer 21 enable the semiconductor wafer 21 to hardly be broken even if the wafer 21 is thinned than before, that is, enable the thickness of the silicon substrate 1 to be thinner than before. For example, the thickness of the silicon substrate 1 can significantly be thinned to be 20 to 30 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device.

  A conventional semiconductor device is known as a CSP (Chip Size Package) (see, for example, Patent Document 1). In this semiconductor device, a plurality of wirings are provided on the upper surface of the insulating film provided on the semiconductor substrate, a columnar electrode is provided on the upper surface of the connection pad portion of the wiring, and a sealing film is provided on the upper surface of the insulating film including the wiring. The upper surface is provided so as to be flush with the upper surface of the columnar electrode. In this case, in order to protect the side surface and the lower surface of the semiconductor substrate, the side surface of the semiconductor substrate is covered with a sealing film, and the lower surface is covered with a lower layer protective film.

Japanese Patent Laid-Open No. 2001-144121 (FIG. 15)

  By the way, in the above conventional semiconductor device manufacturing method, first, a semiconductor substrate having a wafer state (hereinafter referred to as a semiconductor wafer) on which an insulating film, wiring, and columnar electrodes are formed is prepared. Next, the lower surface of the semiconductor wafer is attached to the upper surface of a lower protective film provided on the upper surface of the dicing tape via a release layer.

  Next, a groove having a predetermined width is formed from the insulating film side to each intermediate position in the thickness direction of the lower protective film by half-cutting between the semiconductor device formation regions. In this state, the semiconductor wafer is separated into individual semiconductor substrates by forming the grooves. Next, a sealing film is formed in and above the groove and on the upper surface of the insulating film including the wiring and the columnar electrode. Next, the sealing film and the lower protective film are cut at the center in the width direction of the groove.

  Next, a support tape is attached to the upper surfaces of the columnar electrode and the sealing film. Next, the dicing tape and the release layer are peeled off, and the lower protective film is left as it is. Next, the support tape is peeled off. Thus, a semiconductor device having a structure in which the side surface of the semiconductor substrate is covered with the sealing film and the lower surface is covered with the lower protective film is obtained.

  By the way, in the conventional method for manufacturing a semiconductor device, when the thickness of the semiconductor substrate is reduced, the lower surface of the semiconductor wafer is ground before the lower surface of the semiconductor wafer is attached to the upper surface of the lower protective film. . However, since the sealing film is not formed on the upper surface side when the lower surface of the semiconductor wafer is ground, if the thickness of the semiconductor wafer is made too thin, the semiconductor wafer is likely to be cracked. There is a problem that there is a limit to thinning.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device in which the thickness of a semiconductor substrate can be further reduced.

According to the first aspect of the present invention, the bottom surface of the semiconductor wafer on which the electrode connection pad portion connected to the integrated circuit and the external connection bump electrode connected to the electrode connection pad portion are formed on one surface is ground. Then, after forming the lower layer protective film on the bottom surface of the semiconductor wafer, in the manufacturing method of the semiconductor device separated into individual semiconductor devices, the bottom surface side except the peripheral portion of the semiconductor wafer is ground to form a recess, A step of thinning a portion excluding the peripheral portion of the semiconductor wafer; a step of forming a lower protective film in the recess; and a peripheral portion of the semiconductor wafer by grinding the peripheral portion of the semiconductor wafer and the lower protective film And a step of thinning the lower protective film.
According to a second aspect of the present invention, in the first aspect of the present invention, before the step of thinning the portion excluding the peripheral portion of the semiconductor wafer, the one surface of the semiconductor wafer in the dicing street and portions corresponding to both sides thereof A step of forming a groove on the side, and a step of forming a sealing film around the external connection bump electrode.
According to a third aspect of the present invention, in the invention of the second aspect, after the step of thinning the lower protective film, the sealing film and the lower protective film are cut along the dicing street, And a step of separating the semiconductor device.
According to a fourth aspect of the invention, in the third aspect of the invention, after the step of forming a sealing film around the external connection bump electrode, the external connection bump electrode and the sealing film are formed. A step of affixing a first protective tape, and a step of peeling the first protective tape after the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form a recess. It is what.
The invention according to claim 5 is the invention according to claim 4, wherein after the step of forming a lower protective film in the recess, a second protective tape is formed on the external connection bump electrode and the sealing film. And a step of peeling off the second protective tape after the step of grinding the peripheral portion of the semiconductor wafer and the lower protective film.
According to a sixth aspect of the present invention, in the first aspect of the present invention, after the step of forming a lower protective film in the recess, before the step of thinning the peripheral portion of the semiconductor wafer and the lower protective film And a step of forming a groove on one surface side of the semiconductor wafer in a portion corresponding to the dicing street and both sides thereof, and a step of forming a sealing film around the bump electrode for external connection. is there.
The invention according to claim 7 is the invention according to claim 6, wherein after the step of thinning the peripheral portion of the semiconductor wafer and the lower protective film, the sealing film and the lower protective layer along the dicing street It has a step of cutting the film and separating it into individual semiconductor devices.
According to an eighth aspect of the present invention, in the invention according to the seventh aspect, before the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form a recess, the electrode connection pad portion and the external portion are formed. A step of affixing a first protective tape on the insulating film including the bump electrode for connection; and a step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form a recess. It has the process of peeling a protective tape, It is characterized by the above-mentioned.
The invention according to claim 9 is the invention according to claim 8, wherein after the step of forming a sealing film around the external connection bump electrode, the external connection bump electrode and the sealing film are formed. A step of applying a second protective tape, and a step of peeling the second protective tape after the step of grinding the peripheral portion of the semiconductor wafer and the lower protective film. is there.
According to a tenth aspect of the present invention, in the first aspect of the invention, the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form the concave portion is disposed inside the peripheral portion of the semiconductor wafer. This is a step of revolving around the center of the semiconductor wafer while rotating the disk-shaped grinding wheel portion and gradually lowering it.
According to an eleventh aspect of the present invention, in the invention according to the tenth aspect, the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form the concave portion includes the thickness of the portion excluding the peripheral portion of the semiconductor wafer. It is a process which makes thickness 20-30 micrometers.
The invention according to claim 12 is the invention according to claim 9, wherein the depth of the groove is set to the thickness of the semiconductor substrate plus 30 to 50 μm below the upper surface of the semiconductor substrate. Is.
The invention described in claim 13 is the invention described in claim 10, wherein the width of the peripheral portion of the semiconductor wafer is 2 to 3 mm.
According to a fourteenth aspect of the present invention, in the first aspect of the invention, the step of grinding the peripheral portion of the semiconductor wafer and the lower protective film is a disc-like shape in which a part is disposed outside the semiconductor wafer. This is a step of revolving around the center of the semiconductor wafer while rotating the grinding wheel portion and gradually lowering it.
According to a fifteenth aspect of the present invention, in the first aspect of the invention, after the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form a concave portion, a light shielding film is formed on the inner surface of the concave portion. It has the process, It is characterized by the above-mentioned.
The invention described in claim 16 is characterized in that, in the invention described in claim 14, the light shielding film is formed of a metal.
According to a seventeenth aspect of the present invention, in the first aspect of the invention, the method includes a step of forming an insulating film on one surface of the semiconductor wafer, and the electrode connection pad portion is formed on the insulating film. It is a connection pad portion of the wiring.

  According to the present invention, the bottom surface side excluding the peripheral portion of the semiconductor wafer is ground to form the concave portion, and the portion excluding the peripheral portion of the semiconductor wafer is thinned. Even if the thickness of the wafer is further reduced, it is possible to make the semiconductor wafer difficult to break, and thus the thickness of the semiconductor substrate can be further reduced.

Sectional drawing of an example of the semiconductor device manufactured by the manufacturing method as 1st Embodiment of this invention. Sectional drawing of what was initially prepared in an example of the manufacturing method of the semiconductor device shown in FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. FIG. 9 is a cross-sectional view of the process following FIG. 8. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. Sectional drawing of the process following FIG. FIG. 15 is a sectional view of a step following FIG. 14. FIG. 16 is a cross-sectional view of the process following FIG. 15. Sectional drawing of an example of the semiconductor device manufactured by the manufacturing method as 2nd Embodiment of this invention. FIG. 18 is a cross-sectional view of a predetermined step in the example of the method for manufacturing the semiconductor device shown in FIG. 17. FIG. 19 is a cross-sectional view of the process following FIG. 18. FIG. 20 is a cross-sectional view of the process following FIG. 19. FIG. 21 is a cross-sectional view of the process following FIG. 20. FIG. 22 is a sectional view of a step following FIG. 21. FIG. 23 is a sectional view of a step following FIG. 22; FIG. 24 is a sectional view of a step following FIG. 23. FIG. 25 is a sectional view of a step following FIG. 24. FIG. 26 is a sectional view of a step following FIG. 25. FIG. 27 is a sectional view of a step following FIG. 26; FIG. 28 is a sectional view of a step following FIG. 27. FIG. 29 is a sectional view of a step following FIG. 28. FIG. 30 is a sectional view of a step following FIG. 29; FIG. 31 is a sectional view of a step following FIG. 30. Sectional drawing of an example of the semiconductor device manufactured by the manufacturing method as 3rd Embodiment of this invention. FIG. 31 is a cross-sectional view of a predetermined step in the example of the method for manufacturing the semiconductor device shown in FIG. 30.

(First embodiment)
FIG. 1 shows a cross-sectional view of an example of a semiconductor device manufactured by the manufacturing method as the first embodiment of the present invention. This semiconductor device is generally called a CSP and includes a silicon substrate (semiconductor substrate) 1. On the upper surface of the silicon substrate 1, elements constituting an integrated circuit having a predetermined function, for example, elements (not shown) such as a transistor, a diode, a resistor, and a capacitor are formed. A connection pad 2 made of an aluminum-based metal or the like connected to each element is provided. Although only two connection pads 2 are shown in the figure, a large number are actually arranged around the upper surface of the silicon substrate 1.

  A passivation film (insulating film) 3 made of silicon oxide or the like is provided on the upper surface of the silicon substrate 1 excluding the central part of the connection pad 2, and the central part of the connection pad 2 is provided through an opening 4 provided in the passivation film 3. Is exposed. A protective film (insulating film) 5 made of polyimide resin or the like is provided on the upper surface of the passivation film 3. An opening 6 is provided in the protective film 5 in a portion corresponding to the opening 4 of the passivation film 3.

  A wiring 7 is provided on the upper surface of the protective film 5. The wiring 7 has a two-layer structure of a base metal layer 8 made of copper or the like provided on the upper surface of the protective film 5 and an upper metal layer 9 made of copper provided on the upper surface of the base metal layer 8. One end of the wiring 7 is connected to the connection pad 2 through the opening 6 of the protective film 5 and the opening 4 of the passivation film 3.

  A columnar electrode (external connection bump electrode) 10 made of copper is provided on the upper surface of the connection pad portion (electrode connection pad portion) of the wiring 7. A sealing film 11 made of epoxy resin or the like is provided on the upper surface of the protective film 5 including the wiring 7 around the columnar electrodes 10 and on the side surfaces of the silicon substrate 1, the passivation film 3, and the protective film 5. The columnar electrode 10 is provided so that the upper surface thereof is flush with the upper surface of the sealing film 11 by several μm. A solder ball 12 is provided on the upper surface of the columnar electrode 10.

  Here, the lower surface of the sealing film 11 provided on the side surfaces of the silicon substrate 1, the passivation film 3, and the protective film 5 is flush with the lower surface of the silicon substrate 1. A lower protective film 13 made of epoxy resin or the like is provided on the lower surface of the silicon substrate 1 and the lower surface of the sealing film 11 provided on the side surfaces of the silicon substrate 1, the passivation film 3 and the protective film 5. In this state, the side surface of the silicon substrate 1 is covered with the sealing film 11, and the lower surface of the silicon substrate 1 and the lower surface of the sealing film 11 are covered with the lower protective film 13.

  Here, the thickness of the semiconductor device is not limited, but the thickness from the lower surface of the silicon substrate 1 to the upper surface of the sealing film 11 is about 100 μm, and the height of the columnar electrode 10 is 50 μm. The thickness of the silicon substrate 1 is quite thin, 20-30 μm.

  Next, an example of a method for manufacturing this semiconductor device will be described. First, as shown in FIG. 2, on a silicon substrate in a wafer state (hereinafter referred to as a semiconductor wafer 21), two layers comprising a connection pad 2, a passivation film 3, a protective film 5, a base metal layer 8 and an upper metal layer 9 are formed. A structure in which the structure wiring 7 and the columnar electrode 10 are formed is prepared.

  In this case, the thickness of the commercially available semiconductor wafer 21 is considerably thicker than the thickness (20 to 30 μm) of the silicon substrate 1 shown in FIG. For example, when the diameter of the semiconductor wafer 21 is 300 mm (12 inches) and 200 mm (8 inches), the thickness is considerably thick, such as about 775 μm and 670 μm. Of course, the present invention can be manufactured by using a semiconductor wafer other than a commercially available product, and the thickness of the semiconductor wafer 21 can also be adapted to the manufacturing method shown below. The thickness of the commercially available semiconductor wafer 21 is merely a reference. Here, in FIG. 2, the area | region shown with the code | symbol 22 is a dicing street. Although only three semiconductor device formation regions surrounded by the dicing streets 22 are shown in the figure, a large number are actually arranged in the row direction and the column direction of the region excluding the peripheral portion of the semiconductor wafer 21.

2 is prepared, next, as shown in FIG. 3, the blade 23 is prepared. The blade 23 is made of a disc-shaped grindstone, the cutting edge has a semicircular cross-sectional shape, and its thickness is somewhat thicker than the width of the dicing street 22. For example, the thickness of the blade 23 is 30 to 60 μm, and the length of the semicircular portion of the blade edge is 15 to 30 μm.

Then, using this blade 23, grooves 24 are formed in the protective film 5, the passivation film 3, and the semiconductor wafer 21 in the portions corresponding to the dicing street 22 and both sides thereof. In this case, the depth of the groove 24 below the upper surface of the semiconductor wafer 21 is slightly deeper than the sum of the thickness of the silicon substrate 1 and the length of the semicircular portion of the blade edge of the blade 23 shown in FIG. Thickness (20-30 μm) plus 30-50 μm.

  Here, when the diameter of the semiconductor wafer 21 is 300 mm (12 inches) and 200 mm (8 inches), the initial thickness is about 775 μm and about 670 μm, whereas the groove 24 below the upper surface of the semiconductor wafer 21 is formed. When the depth is set to the thickness of the silicon substrate 1 (20 to 30 μm) plus 30 to 50 μm, the depth of the groove 24 is considerably shallower than the initial thickness of the semiconductor wafer 21. Thus, when the depth of the groove 24 is considerably shallow, even if the groove 24 is formed, the semiconductor wafer 21 is hardly warped, and the strength is not easily lowered.

  Next, as shown in FIG. 4, a thermosetting resin made of an epoxy resin or the like is applied to the upper surface of the protective film 5 including the wiring 7 and the columnar electrode 10 in and above the groove 24 by spin coating or screen printing. The sealing film 11 is formed so as to have a thickness greater than the height of the columnar electrode 10 by applying and curing by, for example. Therefore, in this state, the upper surface of the columnar electrode 10 is covered with the sealing film 11.

  Next, the upper surface side of the sealing film 11 is appropriately ground to expose the upper surface of the columnar electrode 10 and the sealing film 11 including the exposed upper surface of the columnar electrode 10 as shown in FIG. Flatten the top surface. If burrs or oxide films are formed on the upper surface of the columnar electrode 10, the upper surface of the columnar electrode 10 is etched by several μm to remove them. Next, as shown in FIG. 6, the first protective tape 25 in which the adhesive 27 is provided on the lower surface of the base film 26 is attached to the upper surfaces of the columnar electrode 10 and the sealing film 11.

  Next, the one shown in FIG. 6 is turned upside down, and the bottom surface of the semiconductor wafer 21 (the surface opposite to the surface on which the sealing film 11 and the like are formed) is directed upward as shown in FIG. Next, as shown in FIG. 8, a grinding device 28 is prepared. The grinding device 28 has a grinding wheel portion 30 that is slightly larger than the rotating disk 29 on the lower surface of the rotating disk 29, and the rotating disk is driven by driving means (not shown). The grinding wheel 30 is rotated together with 29.

  Then, the lower surface of the grinding wheel 30 is brought into contact with the bottom surface of the semiconductor wafer 21. In this case, the predetermined circumferential side surface of the grinding wheel 30 is positioned slightly inside (for example, 2 to 3 mm inside) than the predetermined circumferential side surface of the semiconductor wafer 21. If the diameter of the grinding wheel portion 30 is too small, the processing efficiency is lowered. Therefore, although not limited, the diameter of the semiconductor wafer 21 or the diameter of the groove 31 formed by processing is described below. About 1/4 to 3/4 is desirable.

  Then, while rotating the grinding wheel 30 together with the rotating disk 29, it revolves around the center of the semiconductor wafer 21 and is set at a preset height position (at least the virtual lower surface of the semicircular section of the groove 24). 9, the sealing film 11 formed in the bottom surface side and the groove 24 except for the peripheral portion of the semiconductor wafer 21 is ground by the grinding wheel 30 to form a recess 31 as shown in FIG. The

The recess 31 is formed to a depth at which the thickness of the semiconductor wafer 21 is, for example, about 20 to 30 μm, exceeds the semicircular portion of the groove 24 formed in the semiconductor wafer 21, and is intermediate between the linear portions of the groove 24. Form to reach the position. In this state, the semiconductor wafer 21 is separated into individual silicon substrates 1 except for the peripheral portion of the semiconductor wafer 21 by forming the recesses 31. Further, since the semiconductor wafer 21 is removed up to the intermediate position of the linear portion of the groove 24 filled with the sealing film 11, the side surfaces of the individually separated silicon substrates 1 become vertical planes.

In this case, since the sealing film 11 is formed, the bottom surface side excluding the peripheral portion of the semiconductor wafer 21 is ground to form the concave portion 31, and the portion excluding the peripheral portion of the semiconductor wafer 21 is thinned. Due to the presence of the film 11 and the remaining part of the periphery of the semiconductor wafer 21, even if the thickness of the semiconductor wafer 21 is further reduced, the semiconductor wafer 21 can be prevented from cracking. As a result, the thickness of the silicon substrate 1 can be reduced. It can be made even thinner. That is, the thickness of the portion excluding the peripheral portion of the semiconductor wafer 21, that is, the thickness of the silicon substrate 1, can be considerably reduced to 20 to 30 μm. The width of the peripheral portion of the semiconductor wafer 21 remaining around the groove 31 is, for example, 2 to 3 mm.

  Here, the semiconductor wafer 21 includes a semiconductor wafer 21 having a positioning notch formed on its outer peripheral portion and a semiconductor wafer 21 having an orientation flat portion (a portion having a linear outer peripheral shape). In the case of the semiconductor wafer 21 in which the notch is formed, if the length of the notch in the diameter direction of the semiconductor wafer 21 is less than 2 mm, a part of the peripheral portion of the semiconductor wafer 21 is missing when the recess 31 is formed. There is nothing.

  On the other hand, in the case of the semiconductor wafer 21 having the orientation flat portion, if the thickness from the outer peripheral side surface of the semiconductor wafer 21 to the inner surface of the concave portion 31 is too thin, when the concave portion 31 is formed, the semiconductor wafer 21 is in the orientation flat portion. Although a part of the side surface is missing, the semiconductor wafer 21 can still be prevented from cracking. Further, even in the case of the semiconductor wafer 21 having the orientation flat portion, the thickness from the outer peripheral side surface of the semiconductor wafer 21 to the inner surface of the recess 31 is adjusted so that the side surface is not chipped even in the orientation flat portion. You can also.

Next, the first protective tape 25 is peeled from the lower surfaces of the columnar electrode 10 and the sealing film 11. Next, as shown in FIG. 10, a thermosetting resin made of epoxy resin or the like is applied to the upper surface of the silicon substrate 1 in the recess 31 and the upper surface of the sealing film 11 formed therearound by a printing method or a dispenser method. The lower protective film 13 is formed by applying and curing the film. In this case, since the upper surface of the lower protective film 13 is ground in a subsequent process, it may be flush with the upper surface of the semiconductor wafer 21 or on the upper side or the lower side.

Next, as shown in FIG. 11, a second protective tape 32 provided with an adhesive 34 on the upper surface of the base film 33 is attached to the lower surfaces of the columnar electrode 10 and the sealing film 11. Here, after the first protective tape 25 shown in FIG. 9 is peeled off and the lower protective film 13 is formed, the second protective tape 32 is applied again when the lower protective film 13 is cured and formed. This is because the first protective tape 25 cannot withstand the curing temperature at that time.

Next, as shown in FIG. 12, a rotating wheel 35 having a grinding wheel portion 36 slightly smaller than the rotating disk 35 is prepared on the lower surface. Then, the lower surface of the grinding wheel portion 36 is brought into contact with the upper surfaces of the semiconductor wafer 21 and the lower protective film 13. In this case, the predetermined peripheral side surface of the grinding wheel portion 36 is positioned slightly outside the predetermined peripheral side surface of the semiconductor wafer 21. Also in this case, the diameter of the grinding wheel 30 is preferably about ¼ to ¾ of the diameter of the semiconductor wafer 21.

Then, while rotating the grinding wheel portion 36 together with the rotating disk 35, it revolves around the center of the semiconductor wafer 21, and is set to a preset height position (a height corresponding to the thickness of the lower protective film 13 to be left). When the film is gradually lowered to the position, as shown in FIG. 13, the lower protective film 13 and the semiconductor wafer 21 are ground by the grinding wheel portion 36, and the thickness of the lower protective film 13 becomes a preset thickness.

  In this case, since the semiconductor wafer 21 made of silicon and the lower protective film 13 made of resin are ground at the same time, the grinding wheel 36 has a mesh size # 360 (average particle size of 40 to 60 μm) at the time of finishing. It is desirable to use a # 1500 (average particle diameter of 5 to 10 μm) grindstone. A grindstone finer than this is not preferable because the abrasive grains are clogged by the influence of the resin, and grinding cannot be performed. On the other hand, a grindstone rougher than this is not preferable because the finish becomes dirty.

  Next, the second protective tape 32 is peeled from the lower surfaces of the columnar electrode 10 and the sealing film 11. Next, after the second protective tape 32 is peeled off, the one shown in FIG. 13 is turned upside down, and the surface on which the columnar electrode 10 and the sealing film 11 are formed faces upward as shown in FIG. . Next, as shown in FIG. 15, solder balls 12 are formed on the upper surface of the columnar electrode 10. Next, as shown in FIG. 16, when the sealing film 11 and the lower protective film 13 are cut along the dicing street 22, a plurality of semiconductor devices shown in FIG. 1 are obtained.

  In the above semiconductor device manufacturing method, as shown in FIG. 3, after forming the groove 24 by half-cut on the upper surface side of the semiconductor wafer 21, as shown in FIG. 7 and the columnar electrode 10 are formed on the upper surface of the protective film 5, that is, the sealing film 11 is formed in a state where the strength of the semiconductor wafer 21 is slightly reduced by the formation of the groove 24. Therefore, when the sealing film 11 made of a thermosetting resin such as epoxy resin is cured and formed, the semiconductor wafer 21 warps due to a difference in thermal expansion coefficient between the sealing film 11 and the semiconductor wafer 21. Cheap. Therefore, next, an embodiment in which the semiconductor wafer 21 can be prevented from warping when the sealing film 11 made of a thermosetting resin such as an epoxy resin is cured and formed will be described.

(Second Embodiment)
FIG. 17 is a sectional view showing an example of a semiconductor device manufactured by the manufacturing method according to the second embodiment of the present invention. This semiconductor device differs from the semiconductor device shown in FIG. 1 in that a lower protective film 13 is provided only on the lower surface of the silicon substrate 1 and the side surfaces of the silicon substrate 1, the passivation film 3, the protective film 5 and the lower protective film 13 are sealed. This is the point covered with the stop film 11. In this case, the lower surface of the sealing film 11 provided on the side surfaces of the silicon substrate 1, the passivation film 3, the protective film 5, and the lower protective film 13 is flush with the lower surface of the lower protective film 13.

Next, an example of a method for manufacturing this semiconductor device will be described. In this case, after preparing what is shown in FIG. 2, as shown in FIG. 18, the adhesive 43 is provided on the lower surface of the base film 42 on the upper surface of the wiring 7, the columnar electrode 10, and the protective film 5. A protective tape 41 is affixed. Next, the one shown in FIG. 18 is turned upside down so that the bottom surface of the semiconductor wafer 21 (the surface opposite to the surface on which the sealing film 11 and the like are formed) faces upward as shown in FIG.

Next, as shown in FIG. 20, the rotating disk 29 and the grinding wheel portion 30 similar to those shown in FIG. 9 are revolved around the center of the semiconductor wafer 21 while rotating, and a predetermined height is set. When gradually lowered to the vertical position, the bottom surface side excluding the peripheral portion of the semiconductor wafer 21 is ground by the grinding wheel 30 to form a recess 31.

  In this case, the bottom surface side excluding the peripheral portion of the semiconductor wafer 21 is ground to form the recess 31, and the portion excluding the peripheral portion of the semiconductor wafer 21 is thinned. Even if the thickness of the semiconductor wafer 21 is further reduced, it is possible to make the semiconductor wafer 21 difficult to break, and thus the thickness of the silicon substrate 1 shown in FIG. 17 can be further reduced. That is, the thickness of the portion (silicon substrate 1) excluding the peripheral portion of the semiconductor wafer 21 can be made considerably thin as 20 to 30 μm. The width of the peripheral portion of the semiconductor wafer 21 remaining around the groove 31 is, for example, 2 to 3 mm.

Next, the first protective tape 41 is peeled off from the lower surface of the wiring 7, the columnar electrode 10 and the protective film 5. Next, as shown in FIG. 21, a lower layer protective film is formed by applying and curing a thermosetting resin made of epoxy resin or the like on the upper surface of the semiconductor wafer 21 in the recess 31 by a printing method, a dispenser method, or the like. 13 is formed. Next, if necessary, the upper surfaces of the lower protective film 13 and the semiconductor wafer 21 are lightly ground to flatten the upper surfaces of the lower protective film 13 and the semiconductor wafer 21. Next, the one shown in FIG. 21 is turned upside down, and the surface on which the columnar electrode 10 is formed faces upward as shown in FIG.

Next, as shown in FIG. 23, using the same blade 23 as shown in FIG. 3, the protective film 5, passivation film 3, semiconductor wafer 21 and lower layer protective film in the dicing street 22 and portions corresponding to both sides thereof are used. A groove 24 is formed in 13. In this state, the semiconductor wafer 21 is separated into the individual silicon substrates 1 except for the peripheral portion by the formation of the grooves 24. In this case, the depth of the groove 24 below the upper surface of the silicon substrate 1 is slightly deeper than the sum of the thickness of the silicon substrate 1 and the length of the semicircular portion of the blade 23, for example, the thickness of the silicon substrate 1 ( 20-30 μm) plus 30-50 μm.

  Here, after the lower protective film 13 made of a thermosetting resin such as an epoxy resin is cured and formed, the protective film 5, the passivation film 3, the semiconductor wafer 21 and the lower protective film on the dicing street 22 and portions on both sides thereof are formed. 13, that is, the lower protective film 13 is cured and formed in a state where the groove causing the strength reduction is not formed on the upper surface side of the semiconductor wafer 21, and then the upper surface of the semiconductor wafer 21 is formed. Since the groove 24 is formed on the side, when the lower protective film 13 made of a thermosetting resin such as an epoxy resin is cured and formed, the semiconductor wafer 21 can be prevented from warping.

  Next, as shown in FIG. 24, a thermosetting resin made of epoxy resin or the like is applied to the upper surface of the protective film 5 including the wiring 7 and the columnar electrode 10 in and above the groove 24 by spin coating or screen printing. The sealing film 11 is formed so as to have a thickness greater than the height of the columnar electrode 10 by applying and curing by, for example. Therefore, in this state, the upper surface of the columnar electrode 10 is covered with the sealing film 11.

  In this case, since a relatively thick lower layer protective film 13 made of a thermosetting resin such as an epoxy resin is already formed on the lower surface of the silicon substrate 1, a thermosetting of an epoxy resin or the like is performed on the upper surface side of the silicon substrate 1. When the relatively thin sealing film 11 made of the conductive resin is cured and formed, the semiconductor wafer 21 can be made difficult to warp. Here, the material of the lower protective film 13 is preferably the same as the material of the sealing film 11.

  Next, the upper surface side of the sealing film 11 is appropriately ground to expose the upper surface of the columnar electrode 10 and the sealing film 11 including the exposed upper surface of the columnar electrode 10 as shown in FIG. Flatten the top surface. If burrs or oxide films are formed on the upper surface of the columnar electrode 10, the upper surface of the columnar electrode 10 is etched by several μm to remove them. Next, as shown in FIG. 26, a second protective tape 44 in which an adhesive 46 is provided on the lower surface of the base film 45 is attached to the upper surfaces of the columnar electrode 10 and the sealing film 11.

  Next, as shown in FIG. 27, the surface shown in FIG. 26 is turned upside down so that the surface side on which the lower protective film 13 is formed faces upward. Next, as shown in FIG. 28, the rotating disk 35 and the grinding wheel portion 36 similar to those shown in FIG. 12 are rotated around the center of the semiconductor wafer 21 while rotating, and a predetermined height is set. When it is gradually lowered to the position (height position corresponding to the thickness of the lower protective film 13 to be left), the lower protective film 13 and the semiconductor wafer 21 are ground by the grinding wheel 36, and the thickness of the lower protective film 13 is reached. Is a preset thickness.

  Next, the second protective tape 44 is peeled from the lower surfaces of the columnar electrode 10 and the sealing film 11. Next, after the second protective tape 44 is peeled off, the one shown in FIG. 28 is turned upside down, and the surface on which the columnar electrode 10 and the sealing film 11 are formed faces upward as shown in FIG. . Next, as shown in FIG. 30, solder balls 12 are formed on the upper surface of the columnar electrode 10. Next, as shown in FIG. 31, when the sealing film 11 is cut along the dicing street 22, a plurality of semiconductor devices shown in FIG. 17 are obtained.

(Third embodiment)
FIG. 32 is a sectional view showing an example of a semiconductor device manufactured by the manufacturing method according to the third embodiment of the present invention. This semiconductor device is different from the semiconductor device shown in FIG. 1 in that the light shielding film 14 made of a metal such as copper is provided between the lower surface of the silicon substrate 1 and the sealing film 11 provided around the silicon substrate 1 and the lower protective film 13. This is the point. The light shielding film 14 is for preventing malfunction of the integrated circuit due to light irradiation from the bottom surface side of the silicon substrate 1.

Next, an example of a method for manufacturing this semiconductor device will be described. In this case, after the step shown in FIG. 9, as shown in FIG. 33, the upper surface of the silicon substrate 1 in the recess 31 and the upper surface of the sealing film 11 formed around it, the inner wall surface of the groove 31, and the outer periphery of the groove 31 A light shielding film 14 made of a metal such as copper is formed on the upper surface of the semiconductor wafer 21 in the portion by sputtering, vacuum deposition, or the like. Thereafter, through the same steps as in the first embodiment, a plurality of semiconductor devices shown in FIG. 32 are obtained.

In the case of the second embodiment as well, a light shielding film can be provided between the silicon substrate 1 and the lower protective film 13. In the manufacturing method in that case, a light shielding film may be formed on the entire upper surface of the semiconductor wafer 21 after the step shown in FIG. Thereafter, when the steps of FIGS. 21 to 30 are performed, a light-shielding film having the same outer shape as both members is provided between the silicon substrate 1 and the lower protective film 13, as will be described with reference to FIG. A semiconductor device in which the outer peripheral side surfaces of the silicon substrate 1, the light shielding film, and the lower protective film 13 are covered with the side surfaces of the sealing film 11 is obtained.

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Connection pad 3 Passivation film 5 Protective film 7 Wiring 10 Columnar electrode 11 Sealing film 12 Solder ball 13 Lower layer protective film 14 Light-shielding film 21 Semiconductor wafer 22 Dicing street 23 Blade 24 Groove 25, 41 First protective tape 30 36 Grinding wheel 31 Recess 32, 44 Second protective tape

Claims (17)

The bottom surface of the semiconductor wafer on which the electrode connection pad portion connected to the integrated circuit and the external connection bump electrode connected to the electrode connection pad portion are formed on one surface is ground, and a lower layer is formed on the bottom surface of the semiconductor wafer. In a method for manufacturing a semiconductor device in which a protective film is formed and then separated into individual semiconductor devices,
Grinding the bottom side excluding the peripheral part of the semiconductor wafer to form a recess, and thinning the part excluding the peripheral part of the semiconductor wafer;
Forming a lower protective film in the recess;
Grinding the peripheral portion of the semiconductor wafer and the lower protective film, and thinning the peripheral portion of the semiconductor wafer and the lower protective film;
A method for manufacturing a semiconductor device, comprising:   In the invention according to claim 1, before the step of thinning the portion excluding the peripheral portion of the semiconductor wafer, forming a groove on one surface side of the semiconductor wafer in the dicing street and portions corresponding to both sides thereof; A method of manufacturing a semiconductor device, comprising a step of forming a sealing film around the external connection bump electrode.   3. The method according to claim 2, further comprising a step of cutting the sealing film and the lower protective film along the dicing street and separating them into individual semiconductor devices after the thinning of the lower protective film. A method for manufacturing a semiconductor device.   In the invention according to claim 3, after the step of forming a sealing film around the external connection bump electrode, a step of attaching a first protective tape on the external connection bump electrode and the sealing film A method of manufacturing a semiconductor device, comprising: a step of peeling the first protective tape after a step of grinding a bottom surface side excluding a peripheral portion of the semiconductor wafer to form a recess.   The invention according to claim 4, further comprising a step of attaching a second protective tape on the external connection bump electrode and the sealing film after the step of forming a lower protective film in the recess. A method for manufacturing a semiconductor device, comprising: a step of peeling the second protective tape after a step of grinding a peripheral portion of a semiconductor wafer and the lower protective film.   In the invention according to claim 1, after the step of forming a lower protective film in the recess, and before the step of thinning the peripheral portion of the semiconductor wafer and the lower protective film, it corresponds to the dicing street and both sides thereof. A method of manufacturing a semiconductor device, comprising: forming a groove on one side of the semiconductor wafer in a portion; and forming a sealing film around the external connection bump electrode.   8. The semiconductor device according to claim 6, wherein after the step of thinning the peripheral portion of the semiconductor wafer and the lower protective film, the sealing film and the lower protective film are cut along the dicing street to obtain individual semiconductors. A method for manufacturing a semiconductor device, comprising a step of separating the device.   8. The insulating film including the electrode connection pad portion and the external connection bump electrode before the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form a recess. A step of affixing a first protective tape thereon, and a step of removing the first protective tape after the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form a recess. A method of manufacturing a semiconductor device.   The process according to claim 8, wherein after the step of forming a sealing film around the external connection bump electrode, a step of attaching a second protective tape on the external connection bump electrode and the sealing film And a step of peeling the second protective tape after the step of grinding the peripheral portion of the semiconductor wafer and the lower protective film.   In the invention according to claim 1, the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form the concave portion includes a disk-shaped grinding wheel portion disposed inside the peripheral portion of the semiconductor wafer. A method of manufacturing a semiconductor device, comprising the step of revolving around the center of the semiconductor wafer while rotating and gradually lowering the semiconductor wafer.   In the invention according to claim 10, the step of forming the concave portion by grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer is a step of setting the thickness of the portion excluding the peripheral portion of the semiconductor wafer to 20 to 30 μm. A method for manufacturing a semiconductor device, comprising:   10. The method of manufacturing a semiconductor device according to claim 9, wherein the depth of the groove is a thickness of the semiconductor substrate plus 30 to 50 [mu] m below the upper surface of the semiconductor substrate.   11. The method of manufacturing a semiconductor device according to claim 10, wherein the width of the peripheral portion of the semiconductor wafer is 2 to 3 mm. In the invention according to claim 1, in the step of grinding the peripheral portion of the semiconductor wafer and the lower protective film, a part of the disc-shaped grinding wheel disposed on the outside of the semiconductor wafer is rotated. A method for manufacturing a semiconductor device, comprising a step of revolving around a center of a semiconductor wafer and gradually lowering the semiconductor wafer. 2. The semiconductor device according to claim 1, further comprising a step of forming a light shielding film on an inner surface of the recess after the step of grinding the bottom surface side excluding the peripheral portion of the semiconductor wafer to form the recess. Device manufacturing method. 15. The method of manufacturing a semiconductor device according to claim 14, wherein the light shielding film is formed of a metal.   The invention according to claim 1, further comprising a step of forming an insulating film on one surface of the semiconductor wafer, wherein the electrode connection pad portion is a connection pad portion of a wiring formed on the insulating film. A method of manufacturing a semiconductor device.

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