JP5655584B2 - Semiconductor device manufacturing method and polishing sheet - Google Patents

Description

  The present invention relates to a semiconductor device manufacturing method and a polishing sheet, for example, a semiconductor device manufacturing method and a polishing sheet for polishing a retainer ring.

  In the manufacturing process of a semiconductor device, a polishing apparatus such as a CMP (Chemical Mechanical Polish) apparatus is used. In the polishing apparatus, the wafer is polished using loose abrasive grains such as slurry. The polishing apparatus includes a retainer ring that fixes the wafer around the wafer. If a large number of wafers are polished, the retainer ring surface is consumed due to wear. For this reason, the retainer ring is changed regularly or irregularly. When replacing with a new retainer ring, the retainer ring is polished by lapping. By polishing the surface of the retainer ring, deburring generated at the corners of the new retainer ring is performed. In addition, the mounting error of the retainer ring after replacement of the retainer ring and the contact state with the surface plate are adjusted.

  As a method for polishing a retainer ring, it is known to use a polishing mechanism different from a platen for polishing a wafer.

JP 2008-149408 A JP 2009-260142 A

  When the retainer ring is polished using a pad on a platen that performs wafer polishing, it takes a long time to polish the retainer ring. For this reason, the pad is consumed and the slurry is consumed. These increase costs.

  On the other hand, when the polishing of the retainer ring is performed using a polishing mechanism different from the platen for polishing the wafer, the polishing mechanism for polishing the retainer ring is different from the platen for polishing the wafer. For this reason, the upper surface of the platen and the lower surface of the retainer ring may not be completely parallel. In this case, the retainer ring is polished again on the platen for polishing the wafer. Eventually, the cost will increase.

  The manufacturing method and polishing sheet of the present semiconductor device aim to reduce the cost when lapping the surface of the retainer ring.

  For example, a step of exchanging a retainer ring provided on a head for holding a wafer, a step of attaching a polishing sheet on a pad provided on a platen, and a lower surface of the retainer ring are polished using the polishing sheet. A method of manufacturing a semiconductor device, comprising: a step, a step of peeling off the polishing sheet, and a step of polishing the lower surface of the wafer using the pad is used.

  For example, a polishing sheet comprising an adhesive layer attached to a pad of a polishing apparatus for polishing a wafer, and a polishing layer formed on the adhesive layer and polishing a lower surface of a retainer ring is used. .

    The manufacturing method and polishing sheet of the present semiconductor device can reduce the cost for lapping the surface of the retainer ring.

FIG. 1A is a plan view of the polishing apparatus, FIG. 1B is a bottom view of the polishing head, and FIG. 1C is a cross-sectional view taken along line AA of FIG. FIG. 2 is a flowchart illustrating the method for manufacturing the semiconductor device according to the first embodiment. FIG. 3A to FIG. 3C are cross-sectional views (part 1) of the polishing apparatus. FIG. 4A to FIG. 4C are cross-sectional views (part 2) of the polishing apparatus. FIG. 5 is a cross-sectional view of the polishing sheet according to the second embodiment. FIG. 6A and FIG. 6B are top views of the polishing tape.

  Embodiments will be described below with reference to the drawings.

  Example 1 is an example in which a CMP apparatus is used as a polishing apparatus. FIG. 1A is a plan view of the polishing apparatus, FIG. 1B is a bottom view of the polishing head, and FIG. 1C is a cross-sectional view taken along line AA of FIG. As shown in FIG. 1A and FIG. 1C, a pad 12 (for example, a polishing cloth) is pasted on a platen 10 (for example, a surface plate). The rotating shaft 14 rotates the platen 10. The wafer 22 is held on the lower surface of the head 30 via a wafer holding pad 32. A retainer ring 20 is provided around the wafer 22. The rotating shaft 34 rotates the head 30. The nozzle 40 supplies a slurry (for example, an abrasive) onto the pad 12. The wafer 22 is brought into contact with the pad 12 while the platen 10 and the head 30 are rotated. Thereby, the lower surface of the wafer 22 is polished.

  For the platen 10 and the head 30, for example, a hard material such as stainless steel is used. For the pad 12, for example, a material such as a resin such as a urethane resin, an acrylic resin, or an epoxy resin is used. The wafer 22 is held on the pad 12 by vacuum suction or the like. At this time, a soft material such as silicon rubber is used for the wafer holding pad 32 in order to protect the surface of the wafer 22. As the retainer ring 20, for example, Teflon (registered trademark) or PPS (Polyphenylene Sulfide) is used. The retainer ring 20 has functions of protecting the edge of the wafer 22 and adjusting the polishing distribution of the wafer 22. The polishing apparatus may include a plurality of platens 10 and heads 30. Thereby, a plurality of wafers can be polished simultaneously.

  FIG. 2 is a flowchart illustrating the method for manufacturing the semiconductor device according to the first embodiment. FIG. 3A to FIG. 4C are cross-sectional views of the polishing apparatus. As shown in FIGS. 2 and 3A, when the retainer ring 20 is worn, the retainer ring 20 is replaced with a new retainer ring 20a (step S10). A polishing sheet 50 (for example, a polishing tape) is pasted on the pad 12 (step S12). When the pad 12 contains moisture, it is preferable to attach the polishing sheet 50 after rotating the platen 10 to remove moisture from the pad 12 to some extent.

  As shown in FIGS. 2 and 3B, the lower surface of the retainer ring 20 a is polished using the polishing sheet 50. In this polishing, for example, water (for example, pure water) is used without using slurry. Further, the retainer ring 20a may be polished while the head 30 holds the dummy wafer 22a. By polishing the retainer ring 20a, the lower surface of the retainer ring 20a becomes flat. Further, protrusions and the like on the edge portion of the retainer ring 20a are removed. This is because if the protrusions at the edge portions of the retainer ring 20a remain on the pad 12, the surface of the wafer 22 may be damaged when the wafer 22 is polished.

  As shown in FIGS. 2 and 3C, when the polishing of the retainer ring 20a is completed, the polishing sheet 50 is peeled off (step S16). At this time, the polishing sheet 50 may be peeled from the pad 12.

  As shown in FIGS. 2 and 4A, when the pad 12 is peeled off in step S16, a new pad 12a is pasted on the platen 10 (step S18). As shown in FIG. 2 and FIG. 4B, the conditioning disk 60 rotates around the rotation shaft 62 to polish the upper surface of the new pad 12 a using the conditioning disk 60. Thus, the surface of the pad 12a is conditioned so that the wafer 22 can be easily polished. When polishing the wafer 22 using the head 30, the conditioning disk 60 is retracted from above the platen 10. The conditioning disk 60 is disposed on the platen 10 when the upper surface of the pad 12a is polished. When polishing the pad 12 a using the conditioning disk 60, the head 30 is retracted from above the platen 10. For example, diamond particles are attached to the surface of the conditioning disk 60 in contact with the pad 12 by an electrodeposition method such as nickel electrodeposition. When polishing the pad 12a, an abrasive 46 is supplied from the nozzle 40 to the upper surface of the pad 12a. The abrasive 46 may be the same as or different from the slurry 42 used when polishing the wafer 22.

  As shown in FIGS. 2 and 4C, the surface of the pad 12a is smoothed using a dummy wafer (step S22). A dummy wafer is used to inspect the polishing rate and dust during polishing (step S24). If the inspection is passed, the semiconductor wafer for forming the product is polished (step S26). For example, an insulating film such as a silicon oxide film, a metal such as copper or tungsten, or the like is formed on the surface of the semiconductor wafer to be polished using the CMP apparatus (the lower surface in FIGS. 2 and 4C).

  According to the first embodiment, the retainer ring 20 provided in the head 30 is replaced as in step S10 of FIG. As in step S <b> 12, the polishing sheet 50 is attached on the pad 12 provided on the platen 10. As in step S <b> 14, the lower surface of the retainer ring 20 is polished using the polishing sheet 50. As in step S16, the polishing sheet 50 is peeled off. Thereafter, the lower surface of the wafer 22 is polished using the pad 12a.

  Thus, the retainer ring 20 is polished by attaching the polishing sheet 50 onto the pad 12 for polishing the wafer 22. Accordingly, the upper surface of the platen 10 and the lower surface of the retainer ring 20 can be made more parallel than when the retainer ring 20 is polished using a polishing mechanism different from that of the platen 10 that polishes the wafer 22. Therefore, it is not necessary to polish the extra retainer ring 20.

  When polishing the wafer 22 using the pad 12, importance is placed on the flatness of the wafer surface and the suppression of scratches on the polishing surface rather than the polishing rate. For this reason, when polishing the retainer ring 20 using the pad 12, processing time is required, and the consumption of the pad 12 and the consumption of slurry increase. According to the first embodiment, the polishing sheet 50 can be selected with an emphasis on the polishing processing time as compared with the case where the pad 12 and the slurry are used. Therefore, consumption of the pad 12 and consumption of the slurry can be suppressed. Further, by using the polishing sheet 50, there is no variation in the polishing rate between processes for polishing the retainer ring 20. As a result, the polishing cost of the retainer ring 20 can be reduced.

  In step S16 in FIG. 2, the pad 12 is not peeled off, and a new pad 12a does not have to be attached to the platen 10 in step S18. However, when removing the polishing sheet 50, it is preferable to remove the polishing sheet 50 and the pad 12 from the platen 10. Thereby, it is not necessary to use the pad 12 contaminated by the adhesive layer 58 of the polishing sheet 50 or the like.

  The retainer ring 20 is preferably polished using a fixed abrasive such as abrasive particles provided on the polishing sheet 50. When fixed abrasive grains are used, contact efficiency between the lower surface of the retainer ring 20 and the abrasive grains is better than when free abrasive grains such as slurry are used. Therefore, the mechanical grinding effect is improved and the lapping process of the retainer ring 20 can be performed effectively. Thereby, the lapping process of the lower surface of the retainer ring 20 can be efficiently performed in a shorter time than when polishing using loose abrasive grains. Therefore, the processing time can be shortened. Further, when polishing the lower surface of the retainer ring 20, it is preferable to use water without using slurry. Thereby, it is not necessary to use an expensive slurry, and the cost can be suppressed.

  Example 2 is an example of an abrasive sheet. FIG. 5 is a cross-sectional view of the polishing sheet according to the second embodiment. As shown in FIG. 5, the polishing sheet 50 is formed by laminating a peeling film 59, an adhesive layer 58, a base material sheet 56 and a polishing layer 54. The abrasive layer 54 includes abrasive particles 52 that are fixed abrasive grains and a binder 53 that holds the abrasive particles 52. The adhesive layer 58 is a layer for adhering to the pad 12. When the polishing sheet 50 is attached to the pad 12, the peeling film 59 is peeled off and the polishing sheet 50 is attached onto the pad 12. The polishing layer 54 is a layer for polishing the lower surface of the retainer ring 20.

  For the base sheet 56, for example, resins such as polyethylene, polystyrene, polyvinyl alcohol, polyvinyl chloride, and fluororesin can be used. Other materials may be used. The film thickness of the base material sheet 56 can be 10 micrometers-300 micrometers, for example. Preferably, it is 50 micrometers-150 micrometers.

  The thickness of the polishing layer 54 is preferably 20 μm or less. As the abrasive particles 52, one kind or a mixture of metal oxide particles such as fumed silica, colloidal silica, α-alumina, θ-alumina, γ-alumina, fumed alumina, zirconia, germania, titania and ceria. Can be used. It is preferable to use a material having the same particle characteristics as the slurry used for polishing the wafer. Thereby, contamination of the apparatus can be suppressed. For example, it is preferable to use generally used silica or the like. The average particle size of the abrasive particles 52 is preferably 10 nm or more and 10 μm or less in terms of secondary particle size. When the average particle size is large, the processing accuracy of the retainer ring is lowered, and burrs and processing strains cannot be removed. In addition, scratches may be induced and a highly accurate machining surface may not be obtained. As the particle shape, for example, agglomerated silica particles (secondary particles) composed of an interparticle combination of amorphous silica particles (primary particles) may be used.

  As the binder 53, resins such as polyurethane, polyester, polyester urethane, phenol, vinyl chloride, acrylic, and epoxy can be used. A thermoplastic resin or a thermosetting resin may be used, and these may be mixed and used. As the thermoplastic resin, a polyester resin, an acrylic-polyester resin, an acrylic-urethane resin, a polyester-urethane resin, or the like can be used.

  As the adhesive used for the pressure-sensitive adhesive layer 58, resins such as polyurethane, polyester, polyester urethane, phenol, vinyl chloride, acrylic, and epoxy can be used. For the formation of the adhesive layer 58, a wire bar coater, a gravure coater, a reverse coater, a knife coater, a nozzle coater, a die coater, a screen coater, a gravure coater, a gravure offset coater, or the like can be used. The thickness of the adhesive layer 58 is preferably 0.1 μm to 50 μm. If the adhesive layer 58 is thin, adhesion strength cannot be obtained, and the polishing layer is easily peeled off. The pad 12 may contain moisture. Therefore, the adhesive used for the pressure-sensitive adhesive layer 58 in order to increase the adhesive effect preferably includes a polar group such as a carboxylic acid group as a substituent.

  The release film 59 is preferably used for protecting the adhesive layer 58. As the peeling film 59, polyethylene terephthalate, polypropylene, polycarbonate, polymethyl methacrylate, or the like can be used. The thickness of the peeling film 59 can be set to 1 μm to 100 μm, for example.

  FIG. 6A and FIG. 6B are top views of the polishing tape. As shown in FIG. 6A, the polishing layer 54 may be formed on the entire upper surface of the base sheet 56. Further, as shown in FIG. 6B, the polishing layer 54 may be formed concentrically on the base sheet 56. Thereby, the foreign material at the time of grind | polishing the retainer ring 20 can be discharged | emitted effectively. The polishing layer 54 may be formed in a spiral shape on the substrate sheet 56.

  According to the second embodiment, the adhesive layer 58 is attached to the pad 12 of the polishing apparatus that polishes the wafer 22. The polishing layer 54 is formed on the adhesive layer 58 and polishes the lower surface of the retainer ring 20. By using such a polishing sheet, the cost for polishing the retainer ring 20 can be reduced as in the first embodiment. In addition, it is preferable to provide the base material sheet | seat 56 which hold | maintains the grinding | polishing layer 54 and the adhesion layer 58 like Example 2. FIG.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

10 Platen 12 Pad 20 Retainer Ring 22 Wafer 30 Head 50 Polishing Sheet 54 Polishing Layer 58 Adhesive Layer

Claims (5)

Replacing the retainer ring provided on the head holding the wafer;
A process of attaching an abrasive sheet on a pad provided on a platen;
Polishing the lower surface of the retainer ring using the polishing sheet;
Removing the abrasive sheet;
Polishing the lower surface of the wafer using the pad;
A method for manufacturing a semiconductor device, comprising: The step of peeling the polishing sheet is a step of peeling the polishing sheet and the pad from the platen,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the step of polishing the lower surface of the wafer is a step of polishing the lower surface of the wafer using a new pad attached on the platen.   The method for manufacturing a semiconductor device according to claim 1, wherein the polishing sheet polishes the retainer ring using fixed abrasive grains.   The method for manufacturing a semiconductor device according to claim 1, wherein the step of polishing the lower surface of the retainer ring uses water instead of slurry. An adhesive layer that sticks onto a pad of a polishing apparatus for polishing a wafer;
A polishing layer formed on the adhesive layer and polishing the lower surface of the retainer ring;
A polishing sheet comprising:

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