JP2014063919A - Wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer processing method capable of surely removing a resin protruding from an outer periphery of a wafer.SOLUTION: A wafer processing method includes at least the steps of: wholly removing a chamfering part C of a wafer W; disposing a carrier plate on a surface WS of the wafer via a resin; removing the resin protruding from the outer periphery of the wafer W by dissolving it with a solvent; and thinning the wafer by grinding a rear surface WR of the wafer to such an extent that a Via electrode E is not exposed to the rear surface WR.

Description

  The present invention relates to a method for processing a wafer such as a semiconductor.

  In recent years, as a new three-dimensional mounting technique, a stacking technique for stacking a plurality of semiconductor chips, forming through electrodes penetrating the stacked semiconductor chips, and connecting the semiconductor chips is being developed (for example, see Patent Documents 1 and 2). ).

JP 2004-207606 A JP 2004-241479 A

  In the process of forming such a through electrode, the wafer is processed in a state of being fixed to a substrate called a carrier plate with a resin as an adhesive so that it can be easily conveyed and held in each process. The resin for adhering the wafer to the carrier plate is usually applied by pressing the resin to the carrier plate after applying the resin to the device surface side where the bumps are arranged without any gaps. At that time, the resin always protrudes from the outer periphery of the device region of the wafer. The protruding resin adheres to a grinding wheel or polishing cloth in a grinding or polishing step and causes clogging. Therefore, the resin on the outer periphery is removed by dissolving with a solvent before grinding or polishing. However, since the chamfered portion of the wafer is usually partially removed by circular cutting, the resin on the outer periphery of the device region to be removed is sandwiched between the stepped portion generated by the chamfering of the wafer and the carrier plate, and is dissolved by the solvent. It takes time and is difficult to remove reliably.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer processing method capable of reliably removing the resin protruding from the outer periphery of the device region.

  In order to solve the above-described problems and achieve the object, a wafer processing method according to the present invention includes an embedded electrode embedded at a depth exceeding a finished thickness from a device formed on the front surface toward the back surface. A wafer processing method for thinning a wafer having a chamfered portion at the outer peripheral edge, wherein a chamfered portion is removed by positioning a cutting blade on the outer peripheral edge of the wafer and cutting the wafer into a circular shape. After the step and the chamfer removing step, a carrier plate disposing step for disposing a carrier plate on the surface of the wafer via a resin, and removing the resin protruding from the outer periphery of the wafer by dissolving with a solvent. And at least a back grinding step of grinding and thinning the back surface of the wafer to such an extent that the embedded electrode is not exposed on the back surface. And features.

  In the processing method of the present invention, since the chamfered portion is completely removed in the chamfered portion removing step, the resin that protrudes from the outer periphery of the device region is not sandwiched between the wafer and the carrier plate, and the solvent easily protrudes. Acts on the resin. Therefore, the resin protruding from the outer periphery of the device region can be reliably dissolved and removed.

  Furthermore, compared to the case where the resin protruding from the outer periphery of the device area is melted and removed in the back grinding step, the resin sticks to the grinding wheel during grinding because the resin that protrudes before the back grinding step is melted and removed. The problem of clogging the grinding wheel can also be solved.

FIG. 1 is a view showing a wafer to be processed by the wafer processing method according to the embodiment. FIG. 2 is a cross-sectional view showing a chamfer removal step of the wafer processing method according to the embodiment. FIG. 3 is a cross-sectional view showing a carrier plate disposing step of the wafer processing method according to the embodiment. FIG. 4 is a cross-sectional view showing a resin removal step of the wafer processing method according to the embodiment. FIG. 5 is a cross-sectional view showing a Via electrode detection step of the wafer processing method according to the embodiment. FIG. 6 is a cross-sectional view showing the back grinding step of the wafer processing method according to the embodiment. FIG. 7 is a cross-sectional view showing an etching step of the wafer processing method according to the embodiment. FIG. 8 is a cross-sectional view showing an insulating film coating step of the wafer processing method according to the embodiment. FIG. 9 is a sectional view showing a finishing step of the wafer processing method according to the embodiment. FIG. 10 is a cross-sectional view showing a bump disposing step of the wafer processing method according to the embodiment. FIG. 11 is a cross-sectional view showing a transfer step of the wafer processing method according to the embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

  A wafer processing method (hereinafter simply referred to as a processing method) according to the present embodiment will be described with reference to FIGS. Fig.1 (a) is a perspective view which shows the outline | summary of the wafer processed by the processing method which concerns on embodiment, FIG.1 (b) is the outline | summary of the wafer which follows the IB-IB line in Fig.1 (a). 2 (a) is a cross-sectional view showing an outline of a chamfered portion removing step for removing the chamfered portion of the wafer shown in FIG. 1 (a), and FIG. FIG. 3 is a cross-sectional view showing an outline of the wafer after the chamfered portion removing step shown in FIG. 2A, and FIG. 3 shows an outline of the carrier plate arranging step in which the carrier plate is attached to the wafer shown in FIG. 4A is a cross-sectional view showing an outline of a resin removal step for removing the resin protruding from the outer periphery of the wafer shown in FIG. 3, and FIG. 4B is a cross-sectional view of FIG. Outline of wafer after resin removal step shown in (a) FIG. 5 is a cross-sectional view showing an outline of the Via electrode detection step for detecting the depth of the Via electrode of the wafer shown in FIG. 4B. FIG. FIG. 6B is a cross-sectional view showing an outline of a back surface grinding step for grinding the back surface of the wafer on which the carrier plate shown in FIG. 5 is disposed, and FIG. 6B is a diagram after the back surface grinding step shown in FIG. FIG. 7 is a cross-sectional view showing the outline of the wafer of FIG. 6, FIG. 7 is a cross-sectional view showing the outline of the etching step for etching the back surface of the wafer shown in FIG. 6 (b), and FIG. FIG. 9 is a cross-sectional view showing an outline of an insulating film coating step for covering an insulating film on the back surface of the wafer, and FIG. 9 is a cross-sectional view showing an outline of a finishing step for exposing the head of the Via electrode of the wafer shown in FIG. FIG. 10 is a diagram illustrating the configuration shown in FIG. FIG. 11 is a cross-sectional view showing an outline of a bump disposing step for disposing a bump on the head of a via electrode of a wafer, and FIG. 11 shows an outline of a transferring step for transferring the wafer shown in FIG. 10 to a dicing tape. It is sectional drawing.

  The processing method according to the present embodiment is a processing method for thinning the wafer W shown in FIG. 1 to a finish thickness Ta (shown in FIG. 7 and the like) of 50 μm or less, for example.

  In this embodiment, the wafer W as a processing target to be thinned by the processing method according to the present embodiment is a disk-shaped semiconductor wafer or optical device wafer having silicon, sapphire, gallium, or the like as a base material. . In the wafer W, as shown in FIG. 1A, a plurality of devices D formed on the surface WS are partitioned by division planned lines S. Further, as shown in FIG. 1B, the wafer W is a Via electrode E (corresponding to an embedded electrode) embedded in a depth exceeding the finishing thickness Ta of the wafer W from the electrode of the device D toward the back surface WR. ) And a chamfered portion C on the outer peripheral edge. The Via electrode E is made of a metal such as copper, the end surface of the wafer W is exposed on the surface WS of the wafer W, and the surface WS of the wafer W (shown in FIG. 1A, etc.) before being thinned to the finished thickness Ta. From the back to the back WR, it is buried at a depth exceeding the finishing thickness Ta. Further, bumps V are provided on the surface of the device D.

  The processing method according to the present embodiment includes a chamfered portion removing step, a carrier plate arranging step, a resin removing step, a Via electrode detecting step, a back grinding step, an etching step, an insulating film covering step, and a finishing step. And a bump disposing step and a transfer step.

  In the processing method according to the present embodiment, first, in the chamfered portion removing step, as shown in FIG. 2A, the dicing tape Tb is attached to the back surface WR of the wafer W, and the back surface of the wafer W is passed through the dicing tape Tb. The WR is placed on the chuck table 2 of the cutting apparatus 1, and the wafer W is held on the chuck table 2. Then, the chuck table 2 of the cutting device 1 is rotated around the axis together with the wafer W, and the cutting blade 3 is rotated by a spindle (not shown) of the cutting device 1. Then, the cutting blade 3 is positioned on the chamfered portion C on the outer peripheral edge of the wafer W, the cutting blade 3 is lowered by a predetermined depth, and the wafer W is cut into a circular shape, as shown in FIG. All the chamfered portions C are removed. In the present embodiment, the chamfered portion C is removed by cutting the cutting blade 3 beyond the chamfered portion C of the wafer W to the center of the thickness of the dicing tape Tb. And it progresses to a carrier plate arrangement | positioning step.

  In the carrier plate arranging step, after the chamfered portion removing step, as shown in FIG. 3, a resin J having adhesiveness is applied to the surface WS of the wafer W, and the resin J is made of glass, silicon, or the like. A rigid and flat carrier plate P is crimped. Further, in the carrier plate arrangement step, the dicing tape Tb is peeled off from the back surface WR of the wafer W. Thus, the carrier plate P is disposed on the surface WS of the wafer W via the resin J. In addition, as a material constituting the resin J, for example, a UV curing type that cures when irradiated with ultraviolet rays, an epoxy resin or an acrylic resin that cures when heated, and the carrier plate P has a chamfered outer diameter is removed. It is formed in a disk shape larger than the outer diameter of the wafer W after the step. Further, when the carrier plate P is disposed on the surface WS of the wafer W via the resin J, as shown in FIG. 3, a part of the resin J (the protruding resin is replaced with another resin). Are indicated by reference numeral Ja below) and protrude from the outer periphery of the wafer W (that is, the device region) after all the chamfered portions C are removed. The thickness of the resin Ja protruding from the outer periphery of the wafer W is thicker than the finishing thickness Ta. Then, the process proceeds to the resin removal step.

  In the resin removing step, as shown in FIG. 4A, the back surface WR of the wafer W is placed on the chuck table 11 of the resin removing device 10 via the carrier plate P or the like, and the wafer W is held on the chuck table 11. . Then, the chuck table 11 of the resin removing device 10 is rotated around the axis together with the wafer W, and the solvent Y is sprayed from the solvent spray nozzle 12 of the resin removing device 10 toward the resin Ja protruding from at least the outer periphery of the wafer W for a predetermined time. Let The solvent Y sprayed by the solvent spray nozzle 12 is a solvent such as alcohol that melts the resin J, and for example, a solvent such as tetrahydrofuran or dimethylformamide is used. Then, the resins Ja and J are gradually melted from the outer peripheral surface side, and the melted resins Ja and J are discharged out of the resin removing device 10 through a discharge port (not shown) of the resin removing device 10.

  Further, by injecting the solvent Y from the injection port of the solvent injection nozzle 12 for a certain period of time, as shown in FIG. 4B, at least a part of the resin Ja that protrudes from the outer periphery of the wafer W is removed as the solvent. Dissolve with Y and remove. In the present invention, if the solvent injection nozzle 12 injects the solvent Y toward the resin Ja, and the resin Ja protruding from the outer periphery of the wafer W in the resin J can be dissolved and removed by the solvent Y, the wafer W Even if the outer peripheral portion of the resin J sandwiched between the wafer W and the carrier plate P is melted with the solvent Y and does not protrude from the outer periphery of the wafer W in the resin J within a range in which the carrier plate P is not displaced. good. In short, in the present invention, at least the resin Ja protruding from the outer periphery of the wafer W may be dissolved and removed by the solvent Y. Then, the process proceeds to the Via electrode detection step.

  In the Via electrode detection step, as shown in FIG. 5, the carrier plate P disposed on the wafer W via the resin J is placed on the chuck table 21 of the electrode detection device 20, and the wafer W is held on the chuck table 21. To do. Then, near-infrared light or infrared light that passes through the wafer W is irradiated from the scanner unit 22 of the electrode detection device 20 toward the back surface WR of the wafer W, and the front surface WS of the wafer W and the back surface WR side of the Via electrode E The scanner unit 22 is moved along the back surface WR while receiving light reflected from the end surface Ea of the wafer W and the back surface WR of the wafer W. Then, based on the refractive index of the wafer W, the depth H of the end surface Ea on the back surface WR side of the Via electrode E from the back surface WR of the wafer W is detected. And it progresses to a back surface grinding step.

  In the back grinding step, as shown in FIG. 6A, the carrier plate P disposed on the wafer W via the resin J is placed on the chuck table 31 of the grinding device 30, and the wafer W is placed on the chuck table 31. Hold. Then, the chuck table 31 of the grinding device 30 is rotated around the axis together with the wafer W, and the grinding wheel 32 of the grinding device 30 is brought into contact with the back surface WR of the wafer W while rotating around the axis in the same direction as the chuck table 31. . Then, based on the depth H of the end surface Ea on the back surface WR side of the Via electrode E detected in the Via electrode detection step, the grinding wheel 32 is fed at a predetermined feed rate so that the end surface Ea of the Via electrode E is not exposed to the back surface WR. Then, the wafer W is ground by a predetermined amount, and the back surface WR of the wafer W is ground by the grinding wheel 32 to thin the wafer W. Then, as shown in FIG. 6B, about half of the thickness of the wafer W is removed, and the process proceeds to the etching step.

  In the etching step, the back surface WR side of the wafer W ground by the back surface grinding step is subjected to etching such as plasma etching, and the end surface Ea of the Via electrode E is made to be more than the back surface WR of the wafer W as shown in FIG. Make it protrude. Then, the process proceeds to the insulating film coating step.

  In the insulating film coating step, as shown in FIG. 8, the back surface WR of the wafer W is coated with an insulating film Z that covers the back surface WR and the end surface Ea of the Via electrode E. Note that the thickness of the insulating film Z is uniform. Then proceed to the finishing step.

  In the finishing step, the carrier plate P disposed on the wafer W via the resin J is placed on the chuck table of the polishing apparatus, and the wafer W is held on the chuck table. Then, the insulating film Z on the end surface Ea of the via electrode E and the via electrode E protruding from the back surface WR are polished by a polishing cloth or the like of the polishing apparatus, and the via electrode E is removed from the insulating film Z as shown in FIG. The head Eb of the Via electrode E is finished on the same surface as the insulating film Z while being exposed. Then, the process proceeds to the bump arrangement step.

  In the bump disposing step, the bump V is disposed on the head Eb of each Via electrode E as shown in FIG. Then, the process proceeds to the transfer step. In the transfer step, the wafer W is reversed for each carrier plate P, and the dicing tape T with the annular frame F attached to the outer edge portion is attached to the back surface WR of the wafer W via the bumps V. Then, the resin J is cured, for example, and the carrier plate P is removed together with the resin J from the surface WS of the wafer W, and the wafer W is transferred from the carrier plate P to the dicing tape T as shown in FIG. Thereafter, the wafer W is divided into individual devices D by cutting or laser processing.

  As described above, in the processing method according to the present embodiment, the chamfered portion C is completely removed in the chamfered portion removing step. Therefore, the resin Ja that protrudes from the outer periphery of the wafer W (that is, the device region) is the wafer W. The solvent Y easily acts on the resin Ja. Therefore, the resin Ja that protrudes from the outer periphery of the wafer W (that is, the device region) can be reliably dissolved and removed.

  Furthermore, compared with the case where the resin Ja is dissolved and removed by the solvent Y in the back surface grinding step, the resin Ja is dissolved and removed by the solvent Y before the back surface grinding step, so the resin Ja adheres to the grinding wheel 32 during grinding. The problem of clogging of the grinding wheel 32 can also be eliminated.

  In the processing method according to the present embodiment, the resin Ja protruding from the outer periphery of the wafer W chamfered in the chamfered portion removing step is removed, but the resin J is within a range in which the wafer W and the carrier plate P are not misaligned. The outer peripheral portion of the resin J sandwiched between the wafer W and the carrier plate P may be removed without protruding from the outer periphery of the wafer W. In short, in the present invention, at least the resin Ja protruding from the outer periphery of the wafer W may be removed in the cleaning step.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

3 Cutting blade W Wafer WS Front WR Back J, Ja Resin P Carrier plate D Device E Via electrode (embedded electrode)
C Chamfered part Y Solvent Ta Finish thickness

Claims (1)

A wafer processing method for thinning a wafer having an embedded electrode embedded in a depth exceeding a finishing thickness from a device formed on a front surface toward a back surface, and having a chamfered portion on an outer peripheral edge,
A chamfered portion removing step of positioning a cutting blade on the outer peripheral edge of the wafer and cutting the wafer into a circular shape to remove all the chamfered portions;
A carrier plate disposing step of disposing a carrier plate on the surface of the wafer via a resin after the chamfered portion removing step;
A resin removal step of removing the resin protruding from the outer periphery of the wafer by dissolving with a solvent;
A wafer processing method including at least a back grinding step of grinding and thinning the back surface of the wafer to such an extent that the embedded electrode is not exposed on the back surface.

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