Method for manufacturing polishing pad

Abstract

To suppress falling-off of an end point detection window from a polishing layer or sticking of an organic residue to a polished article.SOLUTION: A mold release agent 101 is applied on an inner surface of a bottomed hole 100A of a mold form 100, and then a mixture 102 of a pre-polymer and a curative is poured into the bottomed hole 100A to be cured. Thus, a cylindrical element 103 which subsequently becomes an end point detection window 3B is made (Figs. 4(a) and 4(b)). Then, the cylindrical element 103 is dipped in an organic solvent 104 to remove the mold release agent 101 stuck to the cylindrical element 103 (Fig. 4(c)). Then, the cylindrical element 103 is installed in a mold form 107, a mixture 108 of a polyisocyanate, a curative, and hollow fine particles is poured into the mold form 107 to be cured, and an urethane block 109 is made (Fig. 4(d)). Then, the urethane block 109 is horizontally cut to make a sheet-like member 111, thereby making a polishing layer 3C having the end point detection window 3B (FIG. 4(e)).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a polishing pad, and more particularly to a method for manufacturing a polishing pad having an end point detection window for detecting the end point of a polishing process. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a method for manufacturing a polishing pad provided with an end point detection window for detecting the end point of a polishing process has been publicly known (for example, Patent Document 1). In the manufacturing method of Patent Document 1, the polishing layer of the polishing pad is manufactured as follows. That is, a window member that will later become the end point detection window is fixed in advance at a predetermined position in a mold, and in this state, a resin that will become the polishing layer is poured into the mold to produce a molded body. Thereafter, the molded body is sliced ​​to the required thickness to produce a polishing layer integrated with the end point detection window. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-001647 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the polishing pad of Patent Document 1 has the following problem in the manufacturing process of the polishing layer: In the manufacturing method of Patent Document 1, a window member composition is first molded in a mold to produce the window member, but in order to make it easier to remove the molded window member, a release agent is applied in advance to the recess for molding the window member in the mold. Therefore, when the molded window member is removed from the recess, the release agent applied to the recess remains attached to the outer surface of the molded window member. Therefore, when the polishing layer is subsequently produced in the above-mentioned manufacturing process, the release agent remains between the outer peripheral surface of the end point detection window made of the window member and the polishing layer in contact with it, so there is a risk that the end point detection window will fall off from the polishing layer during polishing with the polishing pad after completion. Moreover, if the remaining release agent adheres to the end point detection window during polishing of the polished object, the release agent will adhere to the polished object as an organic residue, and there is a risk that defects will occur in the polished object. [Means for solving the problem]

[0005] In view of the above circumstances, the present invention provides a method for manufacturing a polishing pad comprising a polishing layer having a polishing surface for polishing an object to be polished, and an end point detection window provided in the polishing layer and allowing an inspection light and a reflected light from the object to pass therethrough, the method comprising the steps of: a release agent application step of applying a release agent to a recess of a first mold for molding a window material that will become the endpoint detection window; a window material forming step of pouring a mixture for forming the window material into the recess of the first mold, hardening the mixture, and removing the window material from the recess of the first mold; The window material removed from the first mold is soaked in an organic solvent. The release agent adhering to the surface of the window member is removed by washing with A cleaning process for a molded body forming step of pouring a mixture for forming the polishing layer into a second mold for forming the polishing layer in a state in which the window material is placed in the second mold and hardening the mixture, and then removing a molded body in which the window material is embedded from the second mold; and a cutting step of cutting the molded body to a required thickness so as to include the portion in which the window material is embedded, thereby creating a polishing layer having the end point detection window. Effect of the Invention

[0006] With this configuration, the window material is washed with an organic solvent in the cleaning process, so even if release agent is present on the outer surface of the window material when it is removed from the recess of the first form, the release agent can be removed in the cleaning process. Then, in the subsequent molding process, the window material and the surrounding molding are hardened in a state of tight adhesion with no gaps. In other words, when the polishing layer is completed, the outer surface of the end point detection window and the surrounding polishing layer are in a tight adhesion state without any release agent between them. Therefore, it is possible to effectively prevent the end point detection window from falling off the polishing layer during the polishing process of the polished object by the polishing pad after completion. In addition, it is possible to prevent the end point detection window and the polished object from being adversely affected by the residue of the release agent during the polishing process, and to prevent defects in the polished object from occurring. [Brief description of the drawings]

[0007] [Figure 1] 1 is a configuration diagram of a polishing apparatus showing an embodiment of the present invention. [Diagram 2] FIG. 2 is a longitudinal cross-sectional view of the main parts taken along line II-II in FIG. [Diagram 3] 3 is a cross-sectional view of the polishing layer of the polishing pad of FIG. 2. [Figure 4] 4A to 4C are diagrams showing a manufacturing process of the polishing pad shown in FIGS. 1 to 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1 to 3, reference numeral 1 denotes a polishing apparatus that polishes a thin plate-like object to be polished 2 (e.g., a semiconductor wafer) with a polishing pad 3. When polishing the object to be polished 2, the polishing apparatus 1 irradiates an inspection light L1 toward a surface to be polished 2A of the object to be polished 2 and obtains a reflected light L2, thereby making it possible to detect the progress of the polishing and the end point of the polishing process. The polishing apparatus 1 is equipped with a polishing platen 4 located on the lower side and having a polishing pad 3 fixed on its upper surface, a holding platen 5 located on the upper side and holding the workpiece 2 to be polished on its lower surface, a slurry supply mechanism 6 that supplies slurry S (polishing liquid) between the workpiece 2 to be polished and the polishing pad 3, and a detection mechanism 7 that uses an inspection light L1 to detect the progress of polishing of the workpiece 2 and the end point of the processing. The object 2 to be polished by the polishing apparatus 1 is an optical material, a silicon wafer, a glass substrate for liquid crystal, a semiconductor substrate, and a plate-like object such as glass, metal, ceramic, etc. As the slurry S to be supplied by the slurry supply mechanism 6, a suitable conventionally known material can be used depending on the object 2 to be polished and the required processing accuracy. The polishing platen 4 and the holding platen 5 are each substantially disk-shaped and are adapted to rotate in the direction of the arrow by a drive mechanism (not shown), and the holding platen 5 is provided so as to be movable up and down. When polishing the object 2, the holding platen 5 presses the polished surface 2A (lower surface) of the object 2 against the polishing surface 3A of the polishing pad 3 at a set pressure while they are rotated relative to each other, and a slurry S is supplied from a slurry supply mechanism 6 between the polished surface 2A of the object 2 and the polishing surface 3A of the polishing pad 3. A plurality of annular grooves 3Aa are formed at equal pitches in the radial direction concentrically around the center (center of rotation) of the polishing pad 3 on the polishing surface 3A of the polishing pad 3 (see FIG. 3). These annular grooves 3Aa serve as slurry holding grooves for holding the slurry S, and the slurry S discharged from the slurry supply mechanism 6 flows into these annular grooves 3Aa and is supplied to the entire polishing surface 3A.

[0009] When polishing the workpiece 2, it is necessary to detect the progress of the polishing of the workpiece 2 and the end point of the polishing. Therefore, the polishing device 1 is provided with a detection mechanism 7 that irradiates an inspection light L1 from below upward and detects the progress of the polishing and the end point of the polishing based on the reflected light L2 from the polished surface 2A of the workpiece 2. A transparent end point detection window 3B is provided at a predetermined position of the polishing pad 3, which transmits the inspection light L1 and the reflected light L2 from the polished surface 2A of the workpiece 2. The polishing pad 3 is composed of a disk-shaped polishing layer 3C located on the upper side and a disk-shaped support layer 3D (cushion layer) attached to the lower surface 3Cb of the polishing layer 3C with adhesive or double-sided tape (see FIG. 2). A disk-shaped transparent end point detection window 3B is provided at a predetermined position of the polishing layer 3C, and a through hole 3Da is drilled at the position of the support layer 3D below the end point detection window 3B to allow the inspection light L1 and the reflected light L2 from the polished object 2 to pass through. Both the polishing layer 3C and the end point detection window 3B provided therein are made of an elastic resin such as polyurethane. Note that the end point detection window 3B needs to be structured to avoid foaming that would hinder the transmission of the inspection light L1 and the reflected light L2. Therefore, more specifically, an elastic resin such as polyurethane that does not form voids inside is preferable. A through hole 3Ca is formed in the polishing layer 3C in a predetermined position, and the disk-shaped end point detection window 3B is fitted into the through hole 3Ca without any gap. In other words, the entire outer peripheral surface 3Ba of the end point detection window 3B is in close contact with the through hole 3Ca without any gap. The upper surface 3Bb of the end point detection window 3B and the polishing surface 3A of the polishing layer 3C are flush with each other, and the lower surface 3Bc of the end point detection window 3B and the lower surface 3Cb of the polishing layer 3C are flush with each other. The upper surface of the support layer 3D is adhered to the lower surface 3Cb of the polishing layer 3C with an adhesive or double-sided tape. The polishing pad 3, which is made up of the polishing layer 3C and the support layer 3D integrated from top to bottom, has its lower surface (the lower surface of the support layer 3D) fixed to the upper surface 4A of the polishing platen 4 with an adhesive or double-sided tape (see FIG. 2). The polishing table 4 is provided with a light-emitting unit 7A that irradiates inspection light L1 upward and a light-receiving unit 7B that receives reflected light from the polished object 2, below the end-point detection window 3B of the polishing pad 3 and the through-hole 3Da of the support layer 3D. The detection mechanism 7 includes the light-emitting unit 7A and the light-receiving unit 7B, as well as a control unit 7C that controls their operation and detects the progress of polishing during the polishing process and the end point where the process ends. During the polishing process on the workpiece 2, the inspection light L1 is emitted upward from the light emitting unit 7A of the detection mechanism 7, and the inspection light L1 passes through the transparent end point detection window 3B and is irradiated onto the polished surface 2A of the workpiece 2. Then, the inspection light L1 is reflected downward by the polished surface 2A of the workpiece 2, and the reflected light L2 passes through the transparent end point detection window 3B and is detected by the light receiving unit 7B. The reflected light L2 detected by the light receiving unit 7B is transmitted to the control unit 7C. As the polishing of the workpiece 2 progresses and the polishing surface 2A of the workpiece 2 is gradually polished, the intensity of the reflected light L2 detected by the light receiving unit 7B changes. When the intensity of the reflected light L2 detected by the light receiving unit 7B reaches a preregistered intensity, the control unit 7C determines that the polishing surface 2A has reached the end point of polishing, and stops the polishing. Then, the drive mechanism is stopped, so that the rotation of the polishing platen 4 and the holding platen 5 stops, and the supply of the slurry S from the slurry supply mechanism 6 is also stopped. In this way, the end point of polishing can be detected by using the inspection light L1 of the detection mechanism 7 when the workpiece 2 is polished. Note that the configuration of the detection mechanism 7 using such inspection light L1 is already known.

[0010] Next, one embodiment of a method for manufacturing the polishing pad 3 will be described with reference to Fig. 4. This embodiment is characterized in that, when manufacturing the polishing pad 3, first, a cylindrical material 103 that will become the end point detection window 3B is produced, and the cylindrical material 103 is washed with an organic solvent 104, thereby making it possible to prevent the end point detection window 3B from falling off from the polishing pad 3 during polishing after completion, and to prevent defects caused by organic residue adhering to the workpiece. That is, in this embodiment, first, as the first step, a form 100 having a cylindrical bottomed hole 100A is prepared, and a release agent 101 (e.g., Mirax RS-102 (Miyoshi Oil Co., Ltd.)) is applied to the entire inner surface of the bottomed hole 100A of the form 100 (see Figure 4(a): release agent application step). Note that, although the end point detection window 3B is circular in this embodiment, it can be various other shapes such as a rectangle, a square, a polygon, an ellipse, etc. By using a form 100 in which a bottomed hole 100 is formed according to the desired shape and producing a window material in the shape of a rectangular column or an elliptical column, the end point detection window 3B can be formed in a rectangular, square, polygonal, elliptical, etc. shape. Next, the cylindrical material 103 in this embodiment is made of an elastic resin such as polyurethane, so the material is prepared. Polyisocyanate is prepared as the material, and a hardener is mixed with it to produce a mixed liquid 102. Then, after degassing the mixed liquid 102 as necessary, it is poured into the bottomed hole 100A of the mold 100 and hardened. This produces a cylindrical material 103 that matches the shape of the bottomed hole 100A, which is then removed from the bottomed hole 100A of the formwork 100 (FIG. 4(b): window material molding process). As described above, the release agent 101 has been applied to the entire inner surface of the bottomed hole 100A in advance, so the cylindrical material 103 can be smoothly removed from the bottomed hole 100A. However, the release agent 101 remains attached to the outer peripheral surface 103A and bottom surface of the removed cylindrical material 103. Therefore, in this embodiment, a cleaning process is provided to remove the release agent 101 attached to the cylindrical material 103. That is, a cleaning tank 105 in which an organic solvent 104 is stored in advance is prepared, and the cylindrical material 103 is immersed in the organic solvent 104 in the cleaning tank 105 for a required time (5 minutes) to be cleaned (FIG. 4(c): cleaning process). If the immersion time in the organic solvent 104 is short, the release agent 101 may remain in the cylindrical material 103, so it is preferable that the cylindrical material 103 is immersed in the organic solvent 104 for 5 minutes or more. As the organic solvent 104, for example, any one of ethanol, acetone, chloroform, methanol, isopropyl alcohol, and ethyl acetate is used. In particular, it is preferable to use acetone in combination with the release agent 101. In this way, the release agent 101 attached to the surface of the cylindrical material 103 is removed by immersing the cylindrical material 103 in the organic solvent 104 and cleaning it. Note that ultrasonic cleaning may be further performed while the columnar material 103 is immersed in the organic solvent 104. By performing ultrasonic cleaning, the release agent 101 adhering to the surface of the columnar material 103 can be removed more reliably. Thereafter, the columnar material 103 is taken out of the cleaning tank 105, and its surface is wiped and dried. The subsequent steps are the same as those of the conventionally known manufacturing process of polishing layers and polishing pads. That is, after this, a rectangular box-shaped mold 107 is prepared, and the cylindrical material 103 is placed vertically in a predetermined position of the mold 107 (FIG. 4(d)). In this embodiment, one cylindrical material 103 is placed, but it is possible to place multiple cylindrical materials according to the number of endpoint detection windows 3B provided in the polishing pad 3. Next, polyisocyanate, which is the material of the abrasive layer 3C, a curing agent, and hollow microparticles for forming a foam structure are mixed to prepare a mixture 108, and the mixture 108 is poured into the mold 107 and cured (Figure 4(d)). In this curing process, the liquid mixture 108 adheres without any gaps to the entire outer circumferential surface of the cylindrical material 103, which will later become the end point detection window 3B. At this time, since the release agent 101 has been removed from the outer circumferential surface 103A of the cylindrical material 103 in the above-mentioned washing step, the mixture 108 around the entire outer circumferential surface 103A of the cylindrical material 103 can adhere firmly without any gaps to the entire outer circumferential surface 103A of the cylindrical material 103. This forms a urethane block 109 (molded body) with the cylindrical material 103 embedded therein (FIG. 4(d): molded body forming step). This urethane block 109 becomes part of the abrasive layer 3C. Thereafter, the urethane block 109 is removed from the formwork 107, and then cut out as a sheet-like member 111 by thinly cutting along a horizontal plane to a required thickness so as to include the portion of the urethane block 109 where the cylindrical material 103 is embedded (see FIG. 4(e): cutting process). Thereafter, the surface of the sheet-like member 111 that will become the polishing surface 3A is ground (buffed) as necessary from the viewpoint of thickness correction and fine unevenness formation (sharpening). Then, double-sided tape or the like is attached to the lower surface 3Cb of the polishing layer 3C, which is the opposite side to the polishing surface 3A of the sheet-like member 111 (polishing layer 3C). As a result, the sheet-like member 111 becomes the polishing layer 3C, and the upper surface of the sheet-like member 111 becomes the polishing surface 3A. In addition, the portion of the cylindrical material 103 becomes the end point detection window 3B, and its upper surface 3Bb is flush with the polishing surface 3A, and its lower surface 3Bc is flush with the lower surface 3Cb of the polishing layer 3C (FIG. 4(e): cutting process). Thereafter, the plurality of annular grooves 3Aa are formed by cutting at concentric positions on the polishing surface 3A of the polishing layer 3C (sheet-like member 111) (FIG. 4(f): groove forming step). This completes the polishing layer 3C of the polishing pad 3. When the polishing layer 3C is completed in this way, the support layer 3D (cushion layer) in which the through holes 3Da are formed in advance is attached to the lower surface 3Cb of the polishing layer 3C with an adhesive or double-sided tape. Finally, the laminate of the sheet-like member 107 (polishing layer 3C) and the support layer 3D is cut into a disk shape. This completes the polishing pad 3 of this embodiment (FIG. 4(f)). The polishing pad 3 thus manufactured has its lower surface (the lower surface of the support layer 3D) fixed to the upper surface 4A of the polishing platen 4 by means of double-sided tape, adhesive or the like.

[0011] As described above, in the manufacturing method of this embodiment, after the cylindrical material 103 that will later become the end point detection window 3B is produced, the cylindrical material 103 is immersed in the organic solvent 104 in the subsequent cleaning step. This makes it possible to remove the release agent 101 that has adhered to the outer circumferential surface 103A, the bottom surface, etc. of the cylindrical material 103. Therefore, when the cylindrical material 103 is embedded to produce the urethane block 109 (molded body), no gap is generated between the outer peripheral surface 103 of the cylindrical material 103 (the outer peripheral surface 3Ba of the end point detection window 3B) and the surrounding portion of the urethane block 109 (the inner peripheral surface of the through hole 3Ca), and the two are firmly adhered to each other. Therefore, it is possible to effectively prevent the end point detection window 3B from falling off from the polishing layer 3C during polishing by the completed polishing pad 3. In addition, it is possible to prevent the end point detection window 3B and the object to be polished 2 from being adversely affected by the residue of the release agent during polishing, thereby preventing the object to be polished 2 from being defective. In the above embodiment, in the cleaning step of the cylindrical material 103, ultrasonic cleaning may be performed while the cylindrical material 103 is immersed in an organic solvent. By performing ultrasonic cleaning, the release agent 101 adhering to the surface of the cylindrical material 103 can be more reliably removed, and similarly to the above, the occurrence of defects due to the falling off of the end point detection window 3B during polishing and the adhesion of organic residues of the release agent to the polished object can be suppressed. In the present embodiment, the polishing layer 3C and the end point detection window 3B are made of polyisocyanate and a hardening agent, but the polyisocyanate may be prepolymerized with polyol or the like. Any hardening agent having a plurality of functional groups such as hydroxyl groups and amino groups that react with isocyanate may be used, and polyol or polyamine chain-extended with polyisocyanate or the like may be used. Furthermore, in the present embodiment, in order to form a foam structure in the polishing layer 3C, the hollow fine particles may be, for example, vinylidene chloride-acrylonitrile copolymer, and chemical foaming agents such as water or inert gases may be used alone or in combination. [Explanation of symbols]

[0012] 1‥Polishing device 2‥Object to be polished 3. Polishing pad 3A. Polishing surface 3B: Window for end point detection 3C: Polishing layer 100...Formwork 100A...Bottom hole (recess) 101... Release agent 102... Mixture 103...Cylindrical material (window material) 104...Organic solvent 107...Formwork 108...Mixture 109... urethane block (molded body) 111... sheet-like member

Claims

1. A method for manufacturing a polishing pad comprising: a polishing layer having a polishing surface for polishing an object to be polished; and an end point detection window provided in the polishing layer for transmitting an inspection light and a reflected light from the object to be polished, comprising: a release agent application step of applying a release agent to a recess of a first mold for molding a window material that will become the end point detection window; a window material forming step of pouring a mixture for forming the window material into the recess of the first mold, hardening the mixture, and removing the window material from the recess of the first mold; a cleaning step of cleaning the window material removed from the first mold with an organic solvent to remove the release agent adhering to the surface of the window material; a molded body forming step of pouring a mixture for forming the polishing layer into a second mold for forming the polishing layer in a state in which the window material is placed in the second mold and hardening the mixture, and further removing a molded body in which the window material is embedded from the second mold; A method for manufacturing a polishing pad, comprising a cutting step of cutting the molded body to the required thickness to include the area where the window material is embedded, thereby creating a polishing layer having the end point detection window.

2. 2. The method for producing a polishing pad according to claim 1, wherein the organic solvent used in the cleaning step is any one of ethanol, acetone, chloroform, methanol, isopropyl alcohol, and ethyl acetate.

3. 3. The method for manufacturing a polishing pad according to claim 1, wherein in the cleaning step, the window material removed from the recess of the first mold is immersed in the organic solvent and ultrasonically cleaned.

4. A method for manufacturing a polishing pad as described in any one of claims 1 to 3, characterized in that in the cleaning process, the window material removed from the recess of the first formwork is immersed in the organic solvent for at least 5 minutes and then cleaned.

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