JP2012081566A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of not only executing highly accurate polish finishing which requires extremely high smoothness and flatness but also improving polishing efficiently much higher than a conventional pad.SOLUTION: The polishing pad polishes an article to be processed by relatively moving an article relative to itself while supplying a slurry containing a polishing material between the article and itself. A polishing pad base material which is an epoxy resin and has a hardness (JIS-A) of 70 to 100° is used.

Description

  The present invention is a polishing pad for polishing a workpiece with high accuracy by relatively moving the workpiece while supplying a slurry containing an abrasive between the workpiece and a polishing pad currently used. The present invention relates to a polishing pad that can improve the polishing efficiency that is remarkably superior to that of the polishing pad.

  Conventionally, liquid crystal glass for displays, plate glass, optical lens prisms, and surfaces and end faces of workpieces such as semiconductor wafers are required to have extremely high smoothness and flatness. In addition, there is a demand for shortening the polishing time due to high polishing efficiency.

  Therefore, for example, by supplying a slurry containing an abrasive having a particle size of about 0.5 to 2.0 μm to the workpiece while moving the workpiece relative to the polishing pad to polish the workpiece. Polishing methods are known.

  And means for improving the flatness of the processed surface by eliminating the difference between the polishing by the polishing slurry and the polishing rate by the polishing pad by setting the particle size of the abrasive contained in the polishing pad in the same range. It is presented in 2007-250166.

  However, in order to polish the surface of a work part that requires a high degree of smoothness and flatness as described above, a polishing slurry having a particle size of about 0.5 to 2.0 μm is passed as described above, and a urethane foam resin or A polishing method using a polishing pad such as a foam urethane resin suede is one of the two layers, but since there is no significant difference in the base material of the polishing pad used in this way, Although there is a slight difference in polishing efficiency depending on the characteristics of the polishing pad, there is no significant difference in polishing efficiency itself, and since a base material made of foamed urethane resin is used, there is a limit to further improving the polishing efficiency. There is.

  Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-177945, a polishing pad that improves polishing efficiency by forming a certain groove on the surface of the polishing region of the polishing pad to improve the flow of the polishing slurry is presented. Has been.

  However, the polishing pad having the groove has a problem that the shape of the groove is transferred to the workpiece to cause undulation.

JP 2007-250166 A JP 2005-177945 A

  The present invention has been made in order to solve the problems of the conventional urethane polishing pad, and it goes without saying that high-precision polishing finishing that requires extremely high smoothness and flatness is performed. However, it is an object of the present invention to provide a polishing pad that makes it possible to improve the polishing efficiency far superior to conventional polishing pads.

  The present invention made to solve the above problems is a polishing pad for polishing a workpiece by relatively moving the workpiece while supplying a slurry containing an abrasive to the workpiece. The base material is an epoxy resin, and a polishing pad base material having a hardness of 70 to 100 ° is used. The reason why the hardness is in the range of 70 to 100 ° is that the shape accuracy deteriorates when the hardness is 70 ° or less, and wear increases when the hardness is 100 ° or more.

  In the present invention, the polishing pad base material used can increase the holding power of the slurry and improve the polishing efficiency by using an epoxy resin base material having a large dynamic friction coefficient when the slurry is added.

  The polishing pad of the present invention has a large dynamic friction coefficient at the time of slurry addition and a high retention force of abrasive grains compared to a urethane polishing pad which is said to be excellent as a polishing pad currently on the market. The polishing efficiency is greatly improved by increasing the relative speed of the workpiece and the abrasive grains.

The perspective view which shows preferable embodiment of this invention. The photograph which shows the external appearance of the polishing pad which is an Example of this invention. The optical microscope photograph about the surface of the polishing pad which is an Example of this invention. The relationship figure of the foaming agent and foaming auxiliary agent addition amount and pad hardness about the Example of this invention. The related figure which shows the dynamic friction coefficient about the Example of this invention and the polishing pad which uses a commercially available urethane resin as a base material. The relationship figure of the retention property of the polishing pad which uses the Example of this invention and a commercially available urethane resin as a base material. The relationship figure of the foaming agent and foaming auxiliary agent addition amount and polishing efficiency in the Example of this invention.

  Next, the best mode of the present invention will be described with reference to the drawings.

FIG. 1 shows a preferred embodiment of a polishing pad according to the present invention which is attached to a rotary polishing table. A polishing pad 1 is composed of a thin cylindrical substrate 2 made of a foamed epoxy resin. The pores 3 having a diameter of 0.01 to 3 mm are formed at least on the surface.

  In the present embodiment, a mixture of a thermosetting epoxy resin and a foaming agent as a base material, a curing agent is added and foamed in a mold and cured, then released, and secondarily dried at room temperature, Thereafter, it is sliced to a predetermined thickness to form a thin sheet-like product.

An example will be described in more detail. A curing agent (Japan Epoxy Resin, JER Cure FL052) is 38 with respect to 70.0 g of epoxy resin (Japan Epoxy Resin Co., Ltd., JER834) preheated at 120 ° C. to reduce the viscosity. Added 0.5 g. Further, in order to form pores in the polishing pad, a foaming agent (Yewa Kasei Cellular D) and a foaming assistant (manufactured by Eiwa Kasei Co., Ltd., Cellbest M3) were added. The same amount of foaming agent and foaming aid are added, and the amount added is 2.5-4.
It was changed in the range of 1 g. After mixing these materials, the mixture was stirred and poured into a mold. Then, it heated and hardened and foamed with resin. The temperature was kept at 120 ° C. for 45 minutes or higher. FIG. 2 shows an external view of the manufactured polishing pad (outer diameter 210 mm). FIG. 3 shows an optical microscope image of the pad surface. It can be seen that a large number of pores are formed on the surface of the polishing pad by adding the foaming agent. FIG. 4 shows the relationship between the added amount of the foaming agent and foaming aid and the hardness (JIS-A) of the manufactured polishing pad.

  Next, the dynamic friction coefficient of the polishing pad was evaluated with a tribo tester as an index related to the holding force of the abrasive grains. The evaluation was performed in a dry state and at the time of slurry addition. FIG. 5 shows the dynamic friction coefficient measurement results of a commercially available urethane resin polishing pad and the epoxy resin polishing pad of the present invention. In the dry state, the epoxy resin polishing pad showed a friction coefficient which was about half that of the urethane resin polishing pad. However, when a slurry in which cerium oxide was dispersed in 3 wt% pure water was added and measured, the urethane resin polishing pad had a slightly increased coefficient of friction, whereas the epoxy resin polishing pad. In the case of, a large coefficient of friction exceeding 0.6 was shown.

Next, in order to confirm the retention of the slurry, the state of the slurry flowing was observed by tilting the polishing pad to which 60 μL of slurry in which cerium oxide was dispersed in 3 wt% pure water was dropped. At an inclination angle of 25 degrees, the slurry did not flow down and remained on the polishing pad. However, in the case of the urethane resin polishing pad, the liquid droplets protruded downward. When the tilt angle was set to 30 degrees, the liquid droplets on the urethane resin polishing pad slipped, but the liquid droplets on the epoxy resin polishing pad did not drop at all even if the tilt angle was 55 degrees, and the slurry stayed. It was confirmed that it was very expensive. FIG. 6 shows the relationship between the retention property of the urethane resin polishing pad and the epoxy resin polishing pad.

  Next, glass polishing experiments were conducted using the obtained polishing pad and cerium oxide abrasive grains. Table 1 shows the polishing experimental conditions. Since the manufactured polishing pad had irregularities on the surface, cutting (facing) was performed on the polishing machine.

Soda glass was used for the workpiece, the polishing pressure was 20 KPa, and the rotation speed of the polishing pad and the workpiece was 60 rpm. Further, cerium oxide (SHOROX A-10, manufactured by Showa Denko) having an average particle diameter of 1.2 μm was used as the abrasive grains and dispersed in pure water. For comparison, a polishing experiment was performed under the same conditions using a commercially available foamed urethane polishing pad containing cerium oxide (KAP66A manufactured by Kuju Electric).

  The surface roughness after polishing was evaluated by a white interference microscope (ZygoNewView 5032), and the polishing efficiency was evaluated by the mass difference between the workpieces before and after polishing. FIG. 7 shows the relationship between the addition amount of the foaming agent and foaming aid, the polishing efficiency, and the surface roughness of the workpiece after processing during the production of the polishing pad.

The polishing efficiency is improved with the increase of the addition amount up to 3.9 g of the foaming agent and the foaming aid. Since the polishing pad added with 4.0 g or more had a large porosity, the pad was brittle and the polishing efficiency was lowered. A polishing pad having an added amount of 3.9 g and having a hardness 78 similar to that of a commercially available pad showed the maximum polishing efficiency, and a polishing efficiency approximately twice that of a commercially available urethane polishing pad was obtained. Moreover, the surface roughness of the workpiece after processing was comparable to that of a commercially available urethane polishing pad, and it was confirmed that the workpiece had a high polishing efficiency while maintaining the roughness.

  This is a polishing pad using an epoxy resin as a base material according to the present invention, and has a larger dynamic friction coefficient at the time of slurry addition than a polishing pad using a urethane resin as a commercially available base material, and the holding power of abrasive grains is increased. This is the result obtained when the relative speed between the workpiece and the abrasive is increased to increase the polishing efficiency and to increase the polishing efficiency.

  From these facts, the epoxy resin of the present invention is compared with a polishing pad (including suede) using a urethane resin, which has been said to be effective as a base material, and a polishing pad using a urethane resin with a groove formed as a base material. It is confirmed that the polishing pad using the base material is effective in improving the polishing efficiency.

1 Entire polishing pad 2 Thermosetting epoxy resin base material 3 Air bubbles

Claims (4)

  A polishing pad for polishing a workpiece by relatively moving the workpiece while supplying a slurry containing an abrasive between the workpiece and a workpiece having a hardness of 60 to 100 ° (preferably 70 to A polishing pad formed of an epoxy resin of 100 °.   The polishing pad according to claim 1, wherein the base material has an expansion ratio of 0 to 70%.   The polishing pad according to claim 1 or 2, wherein 1 to 30% of abrasive grains having a diameter of about 0.5 to 500 µm are blended in the base material.   4. The polishing pad according to claim 1, wherein a lattice-like groove is formed on the surface of the substrate.