Holder for chemical mechanical polishing

Abstract

To provide a holder for chemical mechanical polishing that can be used for polishing under a severer polishing condition (such as strong acid slurry or high-polishing pressure) for hard-to-grind material polishing, in other word, has excellent chemical resistance and durability and can suppress detachment and chipping of a frame material.SOLUTION: A holder is configured to dispose a holding pad in a holding hole of a frame material including a frame part and a bottom and includes an integrated frame material part that is made of a predetermined resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a holder for chemical mechanical polishing (CMP) used for planarizing semiconductor materials, optical materials, metals, ceramics, and the like. [Background technology]

[0002] Generally, materials (workpieces) such as semiconductor devices and glass substrates for flat panel displays require highly accurate flatness, and are therefore polished using a polishing pad. In particular, in recent years, circuits have become increasingly miniaturized and precise, leading to an increased demand for high levels of flatness. Typically, these workpieces are polished using a single-sided polisher, which polishes each side of the workpiece at a time. In this single-sided polisher, the workpiece held on a holding platen (upper platen) is polished with a polishing pad attached to a polishing platen (lower platen). During polishing, a polishing liquid containing abrasive particles is supplied to the polishing area of ​​the polishing pad.

[0003] In polishing using a single-sided polisher, a holding sheet such as a soft cloth is attached to the holding platen to reliably hold the entire workpiece without causing contamination or defects and to ensure high in-plane uniformity. If the holding sheet does not hold the workpiece sufficiently, the workpiece will shift sideways or fall off during polishing, making it difficult to polish the workpiece flat.

[0004] To prevent this lateral shift or falling off, a holder is used, in which a frame material with a through hole formed therein into which the workpiece can be inserted is attached to a holding sheet. The workpiece is held by the holder attached to a holding platen and polished, and is then removed from the holder after polishing (Patent Document 1).

[0005] In recent years, there has been an increasing demand for polishing under harsher polishing conditions (strongly acidic slurry, high polishing pressure, etc.) to improve polishing efficiency and polish difficult-to-cut materials such as GaN and SiC. In this case, the adhesive that secures the frame material can deteriorate due to the slurry (polishing liquid), and the frame material can peel off due to horizontal impact from the object being polished inside the holding hole.

[0006] Patent Document 2 discloses a holder in which a polymer film is fixed inside a wafer holder via an adhesive. Furthermore, it discloses an embodiment in which the wafer holder has a bottom and a frame that are a single component and are made of a thermosetting / thermoplastic material. By using a holder in which a holding pad is placed inside a holding hole in a frame material in which the frame and bottom are connected as a single unit, even if the workpiece to be polished is impacted horizontally inside the holding hole, there is no adhesive (adhesive portion) to secure the frame material, and therefore separation of the frame material is suppressed.

[0007] However, if the conventionally used glass fiber reinforced epoxy resin (Glass Epoxy Resin) is used for the frame material, the Glass Epoxy resin itself can undergo delamination.Glass Epoxy resin is usually made by laminating thin plates, so it may not be able to withstand the impact with the workpiece under harsh polishing conditions. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2017-177266 [Patent Document 2] Patent Publication No. 2018-144222 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a chemical mechanical polishing holder that can be used for polishing difficult-to-cut materials under harsher polishing conditions (such as using a strongly acidic slurry or high polishing pressure), i.e., has excellent chemical resistance and durability, and can suppress peeling and chipping of the frame material. [Means for solving the problem]

[0010] In view of the above problems, the present inventors conducted extensive research and discovered that a chemical mechanical polishing holder having a frame material of a specific configuration has excellent chemical resistance and durability and can suppress peeling and chipping of the frame material, thereby arriving at the present invention. That is, the present invention includes the following. [1] A chemical mechanical polishing holder having a holding pad and a frame material, the frame material is substantially free of fibers and is made substantially of polyetherimide resin; the frame member has a frame portion that accommodates the object to be polished and a bottom portion that has a bottom surface to which the holding pad is fixed, The frame material is a seamless, one-piece structure. [2] The holder according to [1], wherein the flexural modulus of the polyetherimide resin measured in accordance with ISO178 is 2.5 GPa or more and 4.5 GPa or less. [3] The holder according to [1], wherein the bending yield stress of the polyetherimide resin measured in accordance with ISO178 is 100 MPa or more and 250 MPa or less. [4] The holder according to [1], wherein the thickness precision of the bottom portion is 40 μm or less. [5] The holder according to [1], wherein the resin constituting the frame material has a porosity of 1% or less. [6] A holder as described in [1], wherein the thickness of the bottom of the frame material is 0.1 mm or more and 3.0 mm or less. [7] The holder according to [1], wherein the holding surface of the holding pad is covered with a material different from the holding pad. [Effects of the Invention]

[0011] The chemical mechanical polishing holder of the present invention is a holder configured to accommodate a holding pad within a holding hole in a frame member having a frame portion and a bottom, and the one-piece frame member is made of a specific resin. This configuration allows it to be used for polishing difficult-to-cut materials under harsher polishing conditions (such as using a strongly acidic slurry or high polishing pressure), i.e., it has excellent chemical resistance and durability, and can suppress peeling and chipping of the frame member. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of a conventional chemical mechanical polishing holder (with a workpiece mounted thereon). [Figure 2] FIG. 2 is a cross-sectional view of a chemical mechanical polishing holder according to the present invention. [Figure 3] FIG. 3 is a cross-sectional view of the chemical mechanical polishing holder of the present invention (with a workpiece provided thereon). DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, the embodiments of the invention will be described, but the present invention is not limited to the embodiments of the invention.

[0014] <Chemical mechanical polishing holder> The chemical mechanical polishing holder R of the present invention (hereinafter referred to as holder R) will be described with reference to FIGS. 2 and 3. FIG. The holder R of the present invention includes a holding pad 1, a frame member 2, and, if necessary, a double-sided tape 31 for fixing the holding pad to position the holding pad 1. As shown in Fig. 3, the holder R holds the workpiece W when the workpiece W is polished by the polishing pad 5. 3, the object to be polished W is placed on the holding surface 11 so that the object to be polished W comes into contact with the polishing pad 5. The holding pad 1 is fixed to the bottom surface 23 of the holding hole 24 of the frame material 2 via the holding pad fixing double-sided tape 31. Here, the bottom surface 23 is the surface on which the workpiece W is placed via the holding pad 1 and the holding pad fixing double-sided tape 31. In other words, the holding pad 1 is fixed to the bottom surface 23 of the frame material 2 via the holding pad fixing double-sided tape 31 on the surface opposite to the holding surface 11 that holds the workpiece W. The holder R of the present invention is fixed to a holding surface plate (not shown) on the surface opposite to the bottom surface 23 of the frame material 2 via holder-fixing double-sided tape 32, but the method for fixing the holder R is not limited, and it may be fixed with a hook-and-loop fastener, an adhesive, or a screw (screw hole). When the holder-fixing double-sided tape 32 is used, it may be the same as or different from the holding pad-fixing double-sided tape 31 used when fixing the holding pad 1 to the bottom surface 23.

[0015] (Frame material) The frame material 2 of the holder R of the present invention does not substantially contain fibers such as glass fibers or carbon fibers. Therefore, fibers do not fall off even under harsh polishing conditions. Furthermore, because fibers exposed on the surface do not come into contact with the workpiece W, problems caused by these fibers do not occur.

[0016] The frame material 2 of the holder R of the present invention is made of polyetherimide resin. Polyetherimide resins are amorphous thermoplastic resins that combine imide bonds, which have excellent heat resistance and strength, with ether bonds, which have good processability, and are highly functional and exhibit excellent processability. Polyetherimide resins having a repeating unit represented by the following general formula (1) are preferred, where n is preferably 5 to 1500:

[0017] [Formula 1] JPEG2025139083000002.jpg36140

[0018] The frame material 2 of the holder R of the present invention may contain unintended impurities or trace amounts of components, but is composed of 95 wt% or more, preferably 98 wt% or more, and more preferably 99 wt% polyetherimide resin. If the polyetherimide resin content is less than 95 wt%, breakage or component elution may occur.

[0019] The flexural modulus (ISO178) of the polyetherimide resin constituting the frame material 2 of the holder R of the present invention is preferably 2.5 GPa or more and 4.5 GPa or less, more preferably 2.8 GPa or more and 4.0 GPa or less. If it is less than 2.5 GPa, deformation or breakage may occur due to collision with the workpiece W. If it exceeds 4.5 GPa, the flexibility is insufficient, and deformation or breakage may occur due to collision with the workpiece W.

[0020] The flexural yield stress (ISO178) of the polyetherimide resin constituting the frame material 2 of the holder R of the present invention is preferably 100 MPa or more and 250 MPa or less, more preferably 110 MPa or more and 210 MPa or less. If it is less than 100 MPa, deformation or breakage may occur due to collision with the workpiece W. If it exceeds 250 MPa, the flexibility is insufficient, and deformation or breakage may occur due to collision with the workpiece W. The force caused by impact with the workpiece W tends to concentrate at the area where the inner wall of the frame and the bottom surface 23 meet, and since the impact occurs repeatedly at irregular intervals, it is thought that the flexural modulus and flexural yield stress are suitable indicators for evaluating impact resistance.

[0021] The frame material 2 of the holder R of the present invention has a seamless, integrated structure that includes a frame portion 21 that houses the workpiece W and a bottom portion 22 that has a bottom surface 23 for fixing the holding pad. Therefore, when a conventional holder RC such as that shown in Fig. 1 is used, unlike the holder RC in which a frame material 2C having a through-hole 4C through which the workpiece W can be inserted is attached to a holding sheet 1C, there is no adhesive equivalent to 33C for fixing the frame material 2C to the holding sheet 1C, and the frame material does not peel off. In Fig. 2, the frame material 2 is formed by cutting a single plate to form a hole (holding hole 24) for accommodating the workpiece W. For convenience of explanation, Fig. 2 shows one holding hole 24, but there may be multiple holding holes 24 (for example, 2 to 7). Furthermore, multiple holders R with one holding hole 24 may be fixed to the holding surface plate.

[0022] The thickness precision of the bottom 22 of the frame material 2 of the holder R of the present invention is preferably 40 μm or less, more preferably 30 μm or less, and particularly preferably 25 μm or less. Higher thickness precision can improve polishing performance. The thickness precision can be calculated as (maximum thickness - minimum thickness) when measuring the bottom of the frame material at four or more points at intervals of 3 cm or more using a dial thickness gauge (manufactured by Ozaki Seisakusho Co., Ltd., product name: Peacock). The holder R of the present invention fixes the holding pad 1 to the bottom surface 23 of the frame material 2 via a holding pad fixing double-sided tape 31. Furthermore, since the frame material 2 is hard, the thickness accuracy of the bottom 22 of the frame material 2 affects the polishing accuracy of the workpiece W. If the thickness accuracy of the bottom 22 exceeds 40 μm, the polishing accuracy of the workpiece W may deteriorate. This effect is particularly noticeable when polishing difficult-to-cut materials that require high polishing pressure. As mentioned above, the holder R has a cross section that is concave, with the holding pad 1 positioned within it. This means that the polishing accuracy of the workpiece W is affected not only by the holding pad 1 but also by the thickness accuracy of the bottom surface of the frame material. While a soft holding pad 1 alone can absorb thickness variations to a certain extent, the hard bottom surface of the frame material can affect the workpiece even with minute irregularities. This effect is particularly noticeable when polishing difficult-to-cut materials, which require high polishing pressure. The thickness precision of the bottom portion 22 can be adjusted by cutting it in multiple stages.

[0023] The actual thickness of the bottom 22 of the frame material 2 of the holder R of the present invention is preferably 0.1 mm or more and 3.0 mm or less. More preferably, it is 0.1 mm or more and 2.0 mm or less, and particularly preferably, it is 0.1 mm or more and 1.0 mm or less. If it is less than 0.1 mm, it may bend when the workpiece W is attached or detached. If it exceeds 3.0 mm, the manufacturing cost may increase excessively.

[0024] The depth of the holding hole 24 in the frame material 2 of the holder R of the present invention is preferably smaller than the total thickness of the holding pad 1, the double-sided tape 31 for fixing the holding pad, and the workpiece W. In other words, it is preferable that the frame material 2 is not in contact with the polishing pad 5 when the workpiece W is being polished.

[0025] The porosity of the polyetherimide resin constituting the frame material 2 of the holder R of the present invention is preferably 3% or less, more preferably 1% or less. The porosity is the ratio of the total area of ​​bubbles observed in a cross section to the cross-sectional area. If the porosity exceeds 1%, chemical resistance and impact resistance may be reduced.

[0026] In the conventional holder RC (see Figure 1), the frame material 2C is made of a glass fiber-reinforced epoxy resin laminate, which has excellent workability and strength. However, as mentioned above, because it contains glass fibers, under harsh polishing conditions the fibers may fall off or the exposed fibers on the surface may come into contact with the workpiece W, which can cause defects. Furthermore, because it is a laminate, there is a possibility that the frame material itself may peel off and break. In contrast, the frame material 2 of the holder R of the present invention does not suffer from such defects and can be used under harsher polishing conditions for polishing difficult-to-cut materials (such as with a strongly acidic slurry or high polishing pressure). In other words, it has excellent chemical resistance and durability, and peeling and chipping of the frame material can be suppressed.

[0027] (holding pad) The holding pad 1 of the holder R of the present invention is used to place the workpiece W in the holding hole 24, and any conventionally known holding pad can be used. From the viewpoint of cushioning properties, it may be, for example, a foamed polyurethane sheet produced by a wet film-forming method, or from the viewpoint of chemical resistance, it may be, for example, a foamed polyurethane sheet produced by a molding method. To withstand harsh polishing conditions, the holding surface of the holding pad may be coated. The coating material is preferably selected from the viewpoints of chemical resistance, water repellency, and holding power, and examples thereof include fluororesin, urethane resin, and epoxy resin.

[0028] The thickness of the holding pad 1 of the holder R of the present invention is smaller than the depth of the holding hole 24 of the frame material 2 minus the thickness of the double-sided tape 31 fixing the holding pad, and is greater than the depth of the holding hole 24 of the frame material 2 minus the sum of the thicknesses of the double-sided tape 31 fixing the holding pad and the workpiece W to be polished.

[0029] (double-sided tape) The double-sided tape 31 for fixing the holding pad or the double-sided tape 32 for fixing the holding device R of the present invention can be any of the conventionally known tapes, for example, a tape having a support material made of a film such as polyethylene terephthalate and having an adhesive such as an acrylic adhesive or a rubber adhesive on both sides of the support material. [Example]

[0030] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0031] Example 1 A flat plate made of polyetherimide resin (ULTEM1000, manufactured by SABIC Innovative Plastics, Inc., thickness 1.30 mm, flexural modulus 3.3 GPa, flexural yield stress 160 MPa) was machined to create frame material A having a bottom surface and holding holes. The dimensions of frame material A were as follows: Frame diameter: 276mm Frame thickness: 1.20mm Holding hole diameter: 100.1mm Number of holding holes: 3 holes Retaining hole depth: 1.0 mm (actual depth excluding the retaining pad 1 and the double-sided tape 31 for fixing the retaining pad) Bottom thickness: 0.20mm The cutting process was carried out in three stages (low accuracy, medium accuracy, and high accuracy in that order). The dimensional accuracy was within ±10 μm. In other words, the thickness accuracy of the bottom was within 20 μm. The produced frame material A was cut and the cross section was observed under a microscope. No bubbles were observed in the cross section, and the bubble area ratio (void ratio) of the cross section was 1% or less (substantially no voids were included). Double-sided tape was placed on the bottom surface of the prepared frame material A, and a holding pad (wet solidification holding pad BP1450, manufactured by Fujibo Ehime Co., Ltd., polyurethane resin, thickness 0.7 mm, thickness includes double-sided tape fixing the holding pad) was placed on top of that. With the double-sided tape and holding pad in place, the depth at which the workpiece W was held was 0.3 mm.

[0032] (Comparative Example 1) Instead of a flat plate made of polyetherimide resin, a flat laminated plate made of glass fiber reinforced epoxy resin was machined to create frame material B with a bottom surface and holding holes. The dimensions of frame material B were the same as frame material A. The cutting process was carried out in one step, with a dimensional accuracy of approximately ±30 μm, meaning that the thickness accuracy of the bottom was approximately 60 μm. Frame material B was also cut and the cross section was magnified and observed under a microscope. No bubbles were observed in the cross section, and the bubble area ratio (void ratio) of the cross section was 1% or less (substantially no voids). Using frame material B, a holder of Comparative Example 1 was produced in the same manner as frame material A.

[0033] (Comparative Example 2) Instead of polyetherimide resin, a flat plate made of polycarbonate resin (manufactured by XX Co., Ltd., thickness XX mm, flexural modulus 2.2 Gpa, flexural yield stress 85 MPa) was machined to create Frame Material C, which has a bottom surface and holding holes. The dimensions of Frame Material C were the same as Frame Material A. The cutting process was carried out in three stages, similar to that of Frame Material A, with a dimensional accuracy of within ±10 μm. In other words, the thickness accuracy of the bottom was 20 μm or less. Frame material C was also cut and the cross section was magnified and observed under a microscope. No bubbles were observed in the cross section, and the bubble area ratio (void ratio) of the cross section was 1% or less (substantially no voids). Using frame material C, a holder of Comparative Example 2 was produced in the same manner as frame material A. The thickness accuracy of the bottom of the frame material of the holder of Example, Comparative Examples 1 and 2, the porosity of the resin, the flexural modulus, and the flexural yield stress are shown in Table 1 (the flexural modulus and flexural yield stress of Comparative Example 1 were not measured).

[0034] [Table 1]

[0035] A polishing test was carried out under the following polishing conditions using the holders of Example 1 and Comparative Examples 1 and 2, and the durability and polishing accuracy of the holders were evaluated. (polishing conditions) Polishing machine used: 32SPAW (manufactured by Speedfam, single-sided polishing machine) Polishing pad: 13M-C051V (Fujibo Ehime, hard urethane polishing pad) Polishing agent temperature: 25℃ Rotation speed: 50 rpm Polishing pressure: 525gf / cm 2 Polishing slurry: CS G3 (Integris, HNO3 slurry, pH 2) Polishing slurry flow rate: 10 ml / min Polishing time: 120min Polished object: 4-inch SiC wafer

[0036] (durability) A grinding test was carried out, and in Table 1, if the holder was damaged, it was marked with "X", and if not, it was marked with "O". No breakage occurred in the holders of the Examples. The holder of Comparative Example 1 was a laminate of thin plates made of glass fiber reinforced epoxy resin, so peeling occurred between the layers. The holder of Comparative Example 2 suffered chipping on the inner wall of the frame due to impact with the workpiece. Frame material C of the holder of Comparative Example 2 had a flexural modulus of 2.2 GPa and a flexural yield stress of 85 MPa, both of which were lower than frame material A of the Examples, and it is thought that deformation and breakage occurred due to impact with the workpiece.

[0037] (polishing precision) Of the polished objects obtained in the polishing tests using the holders of Example and Comparative Examples 1 and 2, the thickness accuracy of the polished objects that could be polished before the holder was damaged was measured. The thickness accuracy of the workpieces obtained in the polishing tests using the holders of Example and Comparative Example 2 was significantly better than that of Comparative Example 1. [Industrial Applicability]

[0038] The present invention provides a holder that is highly durable under severe polishing conditions, and therefore contributes to the manufacture and sale of holding pads, and has industrial applicability. [Explanation of symbols]

[0039] W Object to be polished RC Conventional holder (conventional technology) 1C Conventional holding pad (conventional technology) 11C Retaining sheet (conventional technology) 12C Base sheet (conventional technology) 13C Retaining surface (conventional technology) 2C Conventional frame material (conventional technology) 3C double-sided tape (conventional technology) 4C Retaining hole (conventional technology) R holder 1 Retaining Pad 11 Holding surface 2 Frame material 21 Frame 22 Bottom 23 bottom 24 Retaining hole 31 Double-sided tape for fixing the holding pad 32 Double-sided tape for fixing the holder 5 polishing pads

Claims

1. A chemical mechanical polishing holder having a holding pad and a frame, the frame material is substantially free of fibers and is made substantially of polyetherimide resin; the frame member has a frame portion that accommodates the object to be polished and a bottom portion that has a bottom surface to which the holding pad is fixed, The frame material is a seamless, one-piece structure.

2. 2. The holder according to claim 1, wherein the flexural modulus of the polyetherimide resin measured in accordance with ISO 178 is 2.5 GPa or more and 4.5 GPa or less.

3. 2. The holder according to claim 1, wherein the polyetherimide resin has a bending yield stress measured in accordance with ISO 178 of 100 MPa or more and 250 MPa or less.

4. The holder according to claim 1 , wherein the thickness precision of the bottom portion is 40 μm or less.

5. The holder according to claim 1 , wherein the resin constituting the frame material has a porosity of 1% or less.

6. The holder according to claim 1 , wherein the thickness of the bottom portion of the frame material is 0.1 mm or more and 3.0 mm or less.

7. The retainer of claim 1 , wherein the retaining surface of the retaining pad is coated with a material different from the retaining pad.

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