JP2017196725A - Wrapping polishing surface plate and device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wrapping polishing surface plate and a polishing device that are capable of reducing affected layers and improving processing efficiency by cooling and cleaning the polished surface of a polished material and the polishing surface plate.SOLUTION: In the polishing surface plate and the polishing device that polish a wrapping by using a polishing liquid including grinding abrasive grains, the polishing surface plate is characterized in that metal particles 101 are connected by sintering or the like, or connected under the presence of a resin connection agent 103, and formed as a porous body having pores 102 communicated from a surface plate back surface to a polished surface, and the polishing device is characterized in that flowing-out of a gas, a cooling agent or cleaning water through the pores 102, surface pressure between the polished material and the polishing surface plate, a polishing speed, and roughness of the polished surface are controlled.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a lapping polishing surface plate for an object to be polished such as ceramics, glass, crystal, metal, etc. used for electronic parts such as silicon wafers and optical parts, and an apparatus therefor.

  Glass, metal, and the like used for silicon wafers and optical parts used in recent electronic parts are required to have high surface accuracy as well as high surface smoothness. In polishing these materials, mirror polishing is performed using a soft and elastic polishing cloth such as a well-known pad or felt, and high surface smoothness is obtained. However, in mirror polishing using a polishing cloth, the polishing speed is slow, the amount of polishing in the peripheral portion is larger than the central portion of the material to be polished, and a problem called edge fringing occurs.

On the other hand, according to the polishing using a polishing plate having high rigidity such as cast iron, the above-mentioned edging hardly occurs and high surface (dimension) accuracy can be obtained. However, in the polishing using the polishing plate, sufficient surface roughness such as a mirror surface cannot be obtained, and a problem that a deteriorated layer is easily formed on the processed surface also occurs. In this method, in order to increase the polishing speed, in order to improve the fixability of the abrasive grains in the slurry, in order to attach a technical ring to the surface or reduce the effective surface area, the surface plate is cut into a spiral shape. Or the area is cut concentrically.
As a technique for solving these problems, there is a polishing technique in which a fine powder of soft metal such as copper or tin is dispersed in a synthetic resin and a polishing plate made of a porous body is used (Patent Document 1, Patent Document 2, Patent Document). 3).

JP-A-3-060970 JP-A-8-025213 JP 2005-88174 A

  However, in the case of Patent Document 1, a porous polishing surface plate of a thermosetting resin having continuous pores in which fine powder of copper or tin is dispersed is proposed. In the case of Patent Document 2, a soft metal is included in the resin. Are dispersed in the polishing plate in a solid state, and a polishing liquid is allowed to flow into the polishing surface to form a large number of independent pores on the polishing plate plane. In Patent Document 3, cerium oxide is dispersed in a resin to form abrasive grains, and polishing is performed with an abrasive that does not contain free abrasive grains.

  In the case of Patent Document 1, since there are pores communicating with the polishing plate, heat accompanying the polishing is effectively dissipated, and polishing debris is captured in the pores and expected to prevent clogging, but the polishing plate is synthesized. Even if it is fixed to a high backup material, there is a problem that high surface accuracy cannot be obtained because the thermosetting resin itself is largely deformed. Patent Document 2 solves these problems, but has a problem that it is difficult to obtain a desired high polishing speed. Further, Patent Document 3 disperses cerium oxide fine particles as abrasive grains in a resin, so that it is possible to supply a constant abrasive grain. As a result, a method of supplying a polishing liquid containing abrasive grains results in the following. Fast polishing speed can be obtained. However, compared with diamond abrasive grains, the polishing speed decreases. On the other hand, since both are based on resin, the problem of deformation of thermosetting resin is not completely solved. In addition, when a new polishing operation is performed, a considerable amount of time is required to remove polishing debris clogged in the pores and perform cleaning. The present invention has been made to solve these problems.

  The present invention has been made in consideration of such conventional problems, and can be easily removed by applying pressure from behind the polishing platen to remove the workpiece that has been in close contact with the polishing plate. The cleaning liquid is easily discharged from the nozzle so that the cleaning can be easily performed and the next polishing can be easily performed. In addition, since the polishing machine can use diamond abrasive grains, the polishing efficiency can be made larger than when cerium oxide of Patent Document 2 is used.

    In order to achieve the above-mentioned object, the present invention has been made as a result of intensive studies on the structure of a polishing surface plate for lapping polishing using a grinding liquid containing grinding abrasive grains. It is the following contents as described in the scope of claims.

(1) In a polishing surface plate for lapping polishing using a polishing liquid containing abrasive grains, metal particles are connected by sintering or in the presence of a resin binder, and communicated from the back surface of the surface plate to the polishing surface. A polishing surface plate characterized by being formed as a porous body having pores.
(2) The average diameter of the abrasive grains is 1 μm or more, the average pore diameter is 0.5 μm or more and 20 μm or less, and the average pore diameter is 2/3 or less of the average diameter of the abrasive grains ( 1) The polishing surface plate as described.
(3) When polishing while supplying a polishing liquid containing abrasive grains, a part of the abrasive grains is trapped in the pores of the polishing platen and acts on the material to be ground (1) The polishing surface plate and polishing apparatus described.
(4) During polishing, the back of the polishing platen is set to a positive pressure so that a gas or coolant flows out to the surface of the material to be polished, or the negative abrasive pressure is fixed to the pores by reducing the pressure or pressure. The polishing surface plate according to (1) and the surface pressure between the material to be polished and the polishing surface plate, and the polishing speed and the roughness of the polishing surface can be controlled. Polishing equipment.
(5) The method according to (1) or (4), wherein removal of polishing chips, abrasive grains, etc. between the polishing surface plate and the material to be ground is performed by discharging gas or washing water from the porous body. Polishing surface plate and polishing apparatus.
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According to the present invention (1), in a polishing surface plate for lapping polishing using a grinding liquid containing abrasive grains, metal particles are connected by sintering or resin as a binder, and communicated from the back surface of the surface plate to the polishing surface. It is formed as a porous body having pores. Since this surface plate is based on a metal rather than a resin, it is superior in heat resistance, and the surface plate is less likely to be deformed at the time of polishing, so that more accurate polishing can be performed.
According to the present invention (2), the average diameter of the abrasive grains is 1 μm or more, the average pore diameter is 0.5 μm or more and 20 μm or less, and the average pore diameter is 2/3 or less of the average diameter of the abrasive grains. Therefore, some of the free abrasive grains contained in the polishing liquid can be trapped in the pores and act on the surface to be ground in that form.
According to the present invention (3), when polishing while supplying a polishing liquid containing abrasive grains, a part of the abrasive grains is trapped in the pores of the polishing platen and acts on the material to be polished. Perform lapping polishing. Since the pores are surrounded by the metal particles, the loose abrasive grains are fixed by the plastic deformation of the metal, firmly fixed and polished. In addition, a normal polishing surface plate requires a spiral groove or a concentric groove to reduce the effective area, but the surface plate of the present invention is not necessary because it is a porous body, and groove processing is unnecessary. It is. However, in the case of a normal polishing surface plate, the area reduction effect is about one-half for stabilizing the surface accuracy. However, the surface accuracy can be stabilized by grooving the polishing surface plate of the present invention. It is also possible to reduce the effective area to about one quarter at a time while maintaining the properties.

    According to the present invention (4), during polishing, the back of the polishing platen is set to a positive pressure and a gas or coolant is injected into the surface of the material to be polished, and the distance and surface pressure between the material to be polished and the polishing platen, etc. The polishing speed and the roughness of the polished surface can be controlled. By this control, the roughness of the polished surface can be accurately controlled, and cooling can be performed through the communicating pores, so that a work-affected layer unique to the metal surface plate can be prevented.

    According to the present invention (5), the removal of polishing chips, loose abrasive grains, etc. between the polishing surface plate and the material to be ground can be performed by discharging gas or washing water from the porous body. As a result, the cleaning time is greatly shortened and the polishing efficiency of the entire polishing apparatus is greatly improved.

    According to the present invention, although it is a metal surface plate, there are few work-affected layers on the material to be polished, surface roughness close to that of the resin surface plate can be secured, and a significant improvement in the processing efficiency of the entire polishing apparatus can be achieved And has a significant industrially useful effect.

The top view (a) and sectional drawing (b) of the polishing surface plate of one Example of this invention are shown. Enlarged sectional view during workpiece polishing Relationship between polishing surface plate and polishing equipment

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view (a) and a cross-sectional view (b) of a polishing surface plate 10 illustrating an embodiment of the present invention. Sectional drawing (b) is AA sectional drawing of top view (a).
A normal polishing surface plate needs a spiral groove or a concentric groove to reduce the effective area, but the surface plate of the present invention is a porous body. There is no need for this, and groove processing is unnecessary.
The metal polishing surface plate is composed of metal particles, and is formed by sintering or joining metal particles with a resin. The kind of metal used may be a material used for a normal chemet plate or a harder material (carbon steel). 11 is a polishing surface, and 12 is its back surface. Reference numeral 14 denotes a bolt hole which is connected to a surface plate holder 20 disposed on a surface in contact with 12 and a bolt 13 (see FIG. 3).

      2 is an enlarged perspective view of a part of the cross-sectional view of FIG. 1B. The surface plate 11 is formed in a porous shape, and the front and back surfaces of the surface plate 11 are connected by communicating pores. As a method for forming the polishing platen 11, it is possible to form a porous structure by sintering or bonding particles by resin, but in order to control the size of pores, a resin or the like is used between metal particles. You may form with the binder of. In FIG. 2, 101 is a metal particle, 102 is a pore, 103 is a residual resin. Reference numeral 104 denotes abrasive grains, 105 denotes a movement direction of the work relative to the surface plate, and 106 denotes a rotation direction of the polishing surface plate. Reference numeral 107 denotes a state where abrasive grains are trapped in the pores. The average pore diameter of the pores is preferably smaller than the free abrasive average diameter, and more preferably about 2/3 or more. The size of the metal particles used as the raw material for the polishing platen is determined by the required pore size. Examples of the resin used as a part of the raw material include polyethylene.

    FIG. 3 is a cross-sectional view of the polishing surface plate attached to the polishing apparatus. The object to be polished will be described by taking a silicon wafer as an example.

    The polishing surface plate 10 shown in FIG. 1 has a disk shape, one end surface is a polishing surface 11, and the back surface is 12. As shown in FIG. 2, the surface plate 10 is attached to the surface plate holder 20, and the polishing surface plate 10 is rotated by the surface plate holder 20. The polishing surface plate 10 is attached to the surface plate holder 20 with bolts 13 that pass through mounting holes 14 formed in the outer peripheral portion and are screwed to the surface plate holder 20. Further, the surface plate holder 20 is hollow, and is supported by a plurality of rings so that the polishing surface plate is not deformed. The plurality of rings have through holes 16 at several places around the ring, and are connected to the hollow portion of the rotating shaft and the fluid guide passage 23. The surface plate holder 20 is connected to the rotary shaft 22 via bolts 17.

    As shown in FIG. 3, the surface plate 10 is attached to the rotating shaft 22 of the polishing apparatus via a surface plate holder, and the polishing surface plate 10 is attached to the surface plate holder by a motor (not shown) that drives the rotating shaft 22. 20 is rotated. A hollow fluid guide passage 23 formed in the rotary shaft 22 is connected to a vacuum pump 25 via a rotary joint 24. Accordingly, when the vacuum pump 25 is operated, the pores on the polishing surface of the polishing surface plate 10 communicate with the vacuum pump 25 through the fluid guide passage 23 and become a vacuum state lower than the atmospheric pressure, that is, a negative pressure state. Is attracted to the polishing surface to increase the polishing speed. In this case, the porous body has a high evacuation impedance and can eliminate the problem of vacuum leakage from a portion where the workpiece is not in contact.

    A pressure pump 29 is connected to the rotary joint 24. The pressurizing pump 29 pressurizes and discharges a liquid such as a polishing liquid contained in the container 30, and the liquid such as the polishing liquid enters the pores of the polishing surface plate 10 through the fluid guide passage 23 and flows out from the processing surface. Will do. At this time, because the porous body has high outflow impedance, the liquid flows directly under the work, and the distance between the work and the polishing machine is adjusted to improve the surface smoothness while maintaining the surface accuracy, and the work W can be directly cooled. Become. Moreover, if it is after completion | finish of grinding | polishing, an abrasive grain will be discharge | released and the grinding | polishing surface of the polishing surface plate 10 will be cleaned. The liquid delivered by the pressure pump is not limited to the polishing liquid, and may be water or gas depending on the purpose.

Above the polishing surface plate 10, a work holding unit that applies a load 33 to an object to be polished such as a silicon wafer and the work W and rotates the work W is mounted. A workpiece rotating shaft or a rotating rubber belt (not shown) is provided on the workpiece, and the workpiece holding unit and the workpiece W are rotated. These W and load 33 can move to any position on the surface plate that revolves around the rotating shaft 22 at the same time as it rotates.

    A polishing liquid containing abrasive grains is supplied from the supply port 15 to the surface plate surface 11. The abrasive material is preferably superabrasive such as diamond, but may be alumina, carborundum, or the like. The polishing liquid is preferably an emulsion liquid, but may be water.

DESCRIPTION OF SYMBOLS 10 Polishing surface plate 11 Polishing surface of polishing surface plate 12 Back surface of 11 13 Bolt which connects polishing surface plate and surface plate holder 14 Bolt hole of 13 15 Polishing liquid supply port 16 Through hole of surface plate support ring 17 Rotating shaft and constant Bolt for connecting the panel holder 22 Rotating shaft 23 Hollow portion of the rotating shaft 24 Rotary joint 25 Vacuum pump 26a Connection path to the vacuum pump 26b Connection path to the pressure pump 29 Pressure pump 30 Liquid etc. on which the pressure pump acts 33 Load 101 supporting workpiece 101 Metal particles 102 Pore 103 Residual resin 104 Abrasive grain 105 Direction of movement of workpiece on platen 106 Direction of rotation of platen 107 Plastic deformation part of metal particle with abrasive grains trapped in pores

Claims (5)

  In a polishing surface plate for lapping polishing using a polishing liquid containing abrasive grains, metal particles are connected by sintering or in the presence of a resin binder, and pores communicating from the back surface of the surface plate to the polishing surface are provided. A polishing surface plate characterized by being formed as a porous body.   The average diameter of the abrasive grains is 1 μm or more, the average pore diameter is 0.5 μm or more and 20 μm or less, and the average pore diameter is 2/3 or less of the average diameter of the abrasive grains (1) Polishing surface plate.   2. The polishing according to claim 1, wherein when polishing is performed while supplying a polishing liquid containing polishing abrasive grains, a part of the polishing abrasive grains is captured by pores of the polishing platen and acts on the material to be polished. Surface plate and polishing equipment.   During polishing, the back of the polishing platen is set to a positive pressure so that a gas or coolant flows out to the surface of the material to be polished, and pressure reduction or pressurization can be performed, and the surface pressure between the material to be polished and the polishing surface plate and The polishing surface plate and polishing apparatus according to claim 3, wherein the polishing rate and the roughness of the polishing surface can be controlled.   The polishing according to any one of claims 1 to 4, wherein removal of polishing chips, loose abrasive grains, etc. between the polishing surface plate and the material to be polished is performed by discharging gas or washing water from the porous body. Surface plate and polishing equipment.

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