JP6165020B2 - Processing method - Google Patents

Description

  The present invention relates to a processing method for processing a plate-shaped workpiece.

  A package substrate such as a WL-CSP (Wafer Level-Chip Size Package) wafer includes a plate-shaped base material and a sealing resin layer (sealing resin layer) formed on the base material. By dividing the package substrate into device units, a plurality of semiconductor packages in which the semiconductor chip is covered with the sealing resin layer can be obtained.

  In recent years, in order to further reduce the thickness and weight of a semiconductor package, it has been desired to make the sealing resin layer included in the package substrate thinner. However, when a thin sealing resin layer is formed on the base material from the beginning, bubble-like defects called voids are likely to occur inside the sealing resin layer.

  Then, after forming the sealing resin layer with a certain thickness, the method of processing the sealing resin layer thinly by grinding is examined (for example, refer patent document 1). According to this method, a thin sealing resin layer can be realized by forming a thick sealing resin layer and suppressing the generation of voids while reducing the thickness by grinding.

JP 2004-335540 A

  By the way, the above-mentioned sealing resin layer is mixed with fillers (fine particles) for adjusting physical properties such as a coefficient of thermal expansion. Since the hardness of the filler is usually higher than the hardness of the resin serving as the base of the sealing resin layer, this filler hinders grinding and cannot necessarily process the sealing resin layer appropriately. In addition, when such a sealing resin layer is ground, the amount of wear of the grindstone (grinding grindstone) increases, and the cost required for processing increases.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a processing method of a workpiece that can easily form a thin sealing resin layer at low cost.

According to the present invention, a sealing resin layer is formed on a substrate, and a processing method of a workpiece in which a plurality of semiconductor chips are embedded in the sealing resin layer, the substrate side of the workpiece being held. A holding step for exposing the sealing resin layer by the means, and a jetting means for jetting a fluid containing abrasives on the upper surface of the sealing resin layer of the workpiece held by the holding means from the jetting means. and to expose the and said holding means horizontally moved relative thinning the sealing resin layer in the fluid wherein the semiconductor chip, the upper surface of the upper surface of the sealing resin layer of the exposed the semiconductor chip a thinning step of Ru is projected, after implementing the thin step, a grinding step of thinning the predetermined thickness by grinding the semiconductor chip, processing method characterized by comprising a are provided.

  In the processing method of the present invention, since the sealing resin layer is thinly processed by spraying a fluid containing an abrasive on the upper surface of the sealing resin layer, the sealing resin layer can be easily processed regardless of the presence or absence of the filler. Moreover, since the processing method of this invention does not grind the sealing resin layer using a grinding wheel, it can prevent an increase in processing cost due to wear of the grinding wheel. Thus, according to the present invention, there is provided a method for processing a workpiece that can easily form a thin sealing resin layer at low cost.

It is a partial cross section side view which shows a holding step typically. It is a partial cross section side view which shows a thinning step typically. It is sectional drawing which shows typically the to-be-processed object thinly processed by the thinning step. It is a partial cross section side view which shows a grinding step typically.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The processing method according to the present embodiment includes a holding step (see FIG. 1) and a thinning step (see FIGS. 2 and 3).

  In the holding step, the base material side of the workpiece including the base material (substrate) and the sealing resin layer is held on the holding table (holding means). In the thinning step, a fluid containing an abrasive is sprayed toward the sealing resin layer of the workpiece held on the holding table to thin the sealing resin layer. Hereinafter, the processing method according to the present embodiment will be described in detail.

  FIG. 1 is a partial cross-sectional side view schematically showing a holding step according to the processing method of the present embodiment. As shown in FIG. 1, the processing apparatus 2 used in the processing method of the present embodiment includes a holding table (holding means) 4 that holds a plate-like workpiece 11.

  The holding table 4 is moved in the horizontal direction by a moving mechanism (not shown) provided below. The upper surface of the holding table 4 serves as a holding surface 4 a that holds the workpiece 11 by suction. The holding surface 4 a is connected to a suction source (not shown) through a flow path (not shown) formed inside the holding table 4.

  In the processing method according to the present embodiment, first, a holding step of holding the workpiece 11 on the holding table 4 described above is performed. As shown in FIG. 1, the workpiece 11 is a package substrate manufactured by a COW (Chip On Wafer) process, and includes a disk-shaped base material (substrate) 13.

  A plurality of semiconductor chips 15 are arranged in a lattice pattern on the surface 13 a side of the base material 13. The base material 13 and each semiconductor chip 15 are electrically connected via electrode pads 13 c formed on the surface 13 a of the base material 13 and spherical bumps 15 a provided on the semiconductor chip 15.

  A sealing resin layer 17 that covers the plurality of semiconductor chips 15 is provided on the surface 13 a side of the substrate 13. That is, a plurality of semiconductor chips 15 are embedded in the sealing resin layer 17.

  The sealing resin layer 17 is formed of, for example, a material in which a filler (fine particles) is mixed with an epoxy resin or the like. The thermal expansion coefficient of the sealing resin layer 17 is equal to the thermal expansion coefficient of the base material 13 by the filler. It is adjusted equally.

  In the holding step, the workpiece 11 is placed on the holding table 4 and held while the base material 13 side of the workpiece 11 (the back surface 13b side of the base material 13) faces the holding surface 4a of the holding table 4. A negative pressure of a suction source is applied to the surface 4a. Thereby, the workpiece 11 is sucked and held on the holding table 4. In this state, the sealing resin layer 17 side of the workpiece 11 is exposed upward.

  After the holding step is completed, a thinning step for thinning the sealing resin layer 17 is performed. FIG. 2 is a partial cross-sectional side view schematically showing the thinning step. As shown in FIG. 2, an injection nozzle (injecting means) 6 that injects the fluid F toward the workpiece 11 held on the holding table 4 is arranged above the holding table 4.

The fluid F ejected from the ejection nozzle 6 is typically compressed air. The fluid F contains an abrasive (abrasive) for processing the sealing resin layer 17. As the abrasive contained in the fluid F, for example, calcium carbonate (CaCO ₃ ) having a particle size measured by a sieving method of about 5 μm to 40 μm can be used.

  In the thinning step according to the present embodiment, the sealing resin layer 17 is processed by spraying the fluid F containing such an abrasive. Specifically, the holding table 4 and the ejection nozzle 6 are relatively moved in the horizontal direction while ejecting the fluid F containing the abrasive material from the ejection nozzle 6 toward the upper surface of the sealing resin layer 17.

  Thereby, the upper part of the sealing resin layer 17 is removed, and the sealing resin layer 17 can be processed thinly. The injection port of the injection nozzle 6 is typically constituted by a single opening, but may be constituted by a plurality of openings arranged in a line or plane. By forming the injection port of the injection nozzle 6 with a plurality of openings arranged in a line or plane, a large area can be processed in a short time.

  In the present embodiment, only the holding table 4 is moved in the horizontal direction by the moving mechanism, but the present invention is not limited to this. The injection nozzle 6 may be moved, or the holding table 4 and the injection nozzle 6 may be moved together.

Further, the configurations of the fluid F and the abrasive used in the thinning step are not particularly limited. For example, a liquid such as water may be used as the fluid F. Further, as the abrasive material, baking powder (NaHCO ₃₎ or ceria _(CeO 2), silica can also be used (SiO ₂₎ or the like. The particle size of the abrasive is also arbitrary.

  In the thinning step of the present embodiment, as described above, the fluid F containing the abrasive is sprayed onto the sealing resin layer 17, so that the filler contained in the sealing resin layer 17 is likely to drop off due to collision with the abrasive. Become. Thereby, the sealing resin layer 17 containing a filler can be processed easily. The used abrasive material is collected and reused.

  The removal thickness of the sealing resin layer 17 in the thinning step can be, for example, about several hundred μm. However, the removal thickness of the sealing resin layer 17 can be changed according to the process performed after the thinning step. FIG. 3 is a cross-sectional view schematically showing the workpiece 11 thinly processed in the thinning step.

  In the thinning step described above, for example, as shown in FIG. 3A, the sealing resin layer 17 is processed so as to maintain the semiconductor chip 15 embedded in the sealing resin 17. In addition, as shown in FIGS. 3B and 3B, the sealing resin layer 17 may be processed so that the upper surface of the semiconductor chip 15 is exposed. In this case, it is preferable to select a fluid F and an abrasive that have low processability for the semiconductor chip 15.

  For example, in FIG. 3B, the height position of the upper surface of the semiconductor chip 15 and the height position of the upper surface of the sealing resin layer 17 after processing are the same. On the other hand, in FIG. 3C, the height position of the upper surface of the semiconductor chip 15 is above the height position of the upper surface of the sealing resin layer 17 after processing. That is, the semiconductor chip 15 protrudes above the sealing resin layer 17.

  As shown in FIG. 3C, when the semiconductor chip 15 protrudes above the sealing resin layer 17 in the thinning step, a grinding step for thinning the semiconductor chip 15 is performed thereafter. Also good. FIG. 4 is a partial cross-sectional side view schematically showing the grinding step.

  As shown in FIG. 4, the grinding apparatus 8 used in the grinding step of the present embodiment includes a holding table 10 that holds the workpiece 11 by suction. A rotation mechanism (not shown) is provided below the holding table 10, and the holding table 10 rotates around the vertical axis by this rotation mechanism.

  The upper surface of the holding table 10 is a holding surface 10 a that holds the workpiece 11 by suction. A negative pressure of a suction source (not shown) acts on the holding surface 10a through a flow path (not shown) formed inside the holding table 10, and a suction force for sucking the workpiece 11 is generated.

  A grinding mechanism (grinding means) 12 is disposed above the holding table 10. The grinding mechanism 12 includes a spindle 14 that rotates about a vertical axis. The spindle 14 is lifted and lowered by a lifting mechanism (not shown).

  A disc-shaped wheel mount 16 is fixed to the lower end side of the spindle 14, and a grinding wheel 18 is attached to the wheel mount 16. The grinding wheel 18 includes a wheel base 18a formed of a metal material such as aluminum or stainless steel. A plurality of grinding wheels 18b are fixed to the annular lower surface of the wheel base 18a over the entire circumference.

  In the grinding step, first, the base material 13 side of the workpiece 11 is brought into contact with the holding surface 10a of the holding table 10 to apply a negative pressure of the suction source. Thereby, the workpiece 11 is sucked and held on the holding table 10. In this state, the sealing resin layer 17 side of the workpiece 11 is exposed upward.

  Next, the spindle 14 is lowered while rotating the holding table 10 and the spindle 14 in predetermined rotation directions, respectively, and as shown in FIG. 4, the grinding wheel 18 b on the sealing resin layer 17 side of the workpiece 11. Contact. In the present embodiment, since the semiconductor chip 15 protrudes above the sealing resin layer 17, the grinding wheel 18 b comes into contact with the upper surface of the semiconductor chip 15.

  As a result, the semiconductor chip 15 exposed from the sealing resin layer 17 is thinly processed by grinding. When the semiconductor chip 15 is ground to an arbitrary thickness, the grinding step ends. In this grinding step, since the semiconductor chip 15 is processed thinly, the semiconductor package can be further reduced in thickness and weight.

  As described above, in the processing method according to the present embodiment, the sealing resin layer 17 is thinly processed by spraying the fluid F containing the abrasive material on the upper surface of the sealing resin layer 17. The sealing resin layer 17 can be easily processed.

  Moreover, since the processing method according to the present embodiment does not grind the sealing resin layer 17 using a grinding wheel, it is possible to prevent an increase in processing cost due to wear of the grinding wheel. Thus, according to this Embodiment, the processing method of the to-be-processed object 11 which can form the thin sealing resin layer 17 easily at low cost is provided.

  In addition, this invention is not limited to description of the said embodiment, A various change can be implemented. For example, in the above embodiment, the processing apparatus 2 that processes the sealing resin layer 17 thinly and the grinding apparatus 8 that grinds the semiconductor chip 15 are separated, but these may be integrated.

  Moreover, in the said embodiment, although the package substrate manufactured by the COW process is used as the to-be-processed object 11, the to-be-processed object 11 may be a WL-CSP wafer. In this case as well, in the thinning step, the sealing resin layer may be processed so as to maintain the semiconductor chip embedded state or to expose the upper surface of the semiconductor chip.

  In addition, the configurations, methods, and the like according to the above-described embodiments can be changed as appropriate without departing from the scope of the object of the present invention.

11 Workpiece 13 Base Material (Substrate)
13a surface 13b back surface 13c electrode pad 15 semiconductor chip 15a bump 17 sealing resin layer 2 processing apparatus 4 holding table (holding means)
4a Holding surface 6 Injection nozzle (injection means)
8 Grinding device 10 Holding table 10a Holding surface 12 Grinding mechanism (grinding means)
14 Spindle 16 Wheel mount 18 Grinding wheel 18a Wheel base 18b Grinding wheel F Fluid

Claims (1)

A sealing resin layer is formed on a substrate, and a processing method of a workpiece in which a plurality of semiconductor chips are embedded in the sealing resin layer,
A holding step of holding the substrate side of the workpiece with a holding means to expose the sealing resin layer; and
While ejecting a fluid containing abrasive on the upper surface of the sealing resin layer of the workpiece held by the holding means from the jetting means, the jetting means and the holding means are moved relative to each other in the horizontal direction. to expose the thinning of the sealing resin layer the semiconductor chip, a thinning step of Ru protrudes from the upper surface of the upper surface of the sealing resin layer of the exposed the semiconductor chip,
And a grinding step of grinding the semiconductor chip to a predetermined thickness after performing the thinning step .

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