Patent Application
20100146863
1. Field of the Invention
The present invention relates to a polishing pad and a method for making the same, and particularly, to a polishing pad having an insulation layer and a method for making the same.
2. Description of the Related Art
Polishing generally refers to abrading a rough surface in a chemical mechanical polishing (CMP) process, in which a slurry containing abrasive grains is uniformly dispersed on a surface of a polishing pad, and meanwhile a workpiece to be polished is pressed against the polishing pad and then rubbed repeatedly and regularly. The workpiece to be polished is an object such as a semiconductor, a storage medium substrate, an integrated circuit (IC), an LCD flat glass, an optical glass, or a photoelectric panel.
In the prior art, a polishing pad is mostly fabricated by multi-layer adhesion. For example, an abrasive layer is adhered to a bottom layer with a glue (referring to a multi-layer polishing pad disclosed in Taiwan Patent Publication No. M269996); or an abrasive layer formed by a plurality of thin layers adhered together is further adhered to a bottom layer with a glue (referring to a multi-layer polishing pad for CMP disclosed in Taiwan Patent Publication No. 200513348).
After the above-mentioned polishing pads in the prior art are immersed in the slurry, a stress may easily occur as the abrasive layer and the bottom layer that are made of different materials and the glue used for adhesion have different compression ratios. In addition, the glue's adhesive strength may be gradually degraded if immersed in the slurry for a long time, resulting in poor flatness of the surface of the polishing pad. Moreover, during the polishing process, when a polishing machine applies a force to an object to be polished, a protruding portion of the surface of the polishing pad may severely abrade or scratch the surface of the object to be polished.
Therefore, it is necessary to provide a polishing pad having an insulation layer and a method for making the same, so as to solve the above problems.
The present invention is directed to a polishing pad having an insulation layer. The polishing pad comprises a bottom layer, an insulation layer, and an abrasive layer. The bottom layer comprises a fabric layer wrapped in a high polymer. The insulation layer is disposed on the bottom layer. The abrasive layer is disposed on the insulation layer. The abrasive layer is a high polymeric elastomer and has a plurality of columnar-like cells.
The present invention is further directed to a method for making a polishing pad. The method comprises the steps of: (a) providing a bottom layer, in which the bottom layer comprises a fabric layer wrapped in a high polymer and has a surface; (b) forming an insulation layer on the surface of the bottom layer; (c) forming a high polymeric elastomer on the insulation layer; (d) curing the high polymeric elastomer to form an abrasive layer, in which the abrasive layer has a plurality of columnar-like cells; and (e) abrading a surface of the abrasive layer so that the abrasive layer has a plurality of surface openings.
In the present invention, the insulation layer prevents the slurry from infiltrating into the bottom layer during the polishing process so as to improve polishing effect and quality. In a preferred embodiment, the columnar-like cells are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer, and the depth of the columnar-like cells is greater than one half of the overall thickness of the abrasive layer. Therefore, when applied in the polishing process, the polishing pad may store a large amount of the slurry and scraps generated during abrasion, thus improving the polishing efficiency and preventing the surface of the workpiece to be polished from being scratched. Moreover, the polishing pad is more effectively buffered when put under a large downward force.
The present invention provides a polishing pad, which is applied in a chemical mechanical polishing (CMP) process to abrade or polish a workpiece to be polished. The workpiece to be polished comprises, but is not limited to, a semiconductor, a storage medium substrate, an integrated circuit (IC), an LCD flat glass, an optical glass, or a photoelectric panel.
The insulation layer 60 is disposed on the bottom layer 50. The insulation layer 60 is made of PU, PP, PET, a high-polymer resin, a thin metal layer, a metal powder, or any other material that can be used for insulation. In this embodiment, the insulation layer 60 comprises PU, dimethylformamide (DMF), and methyl ethyl ketone (MEK). The insulation layer 60 is coated (for example, roll-coated or blade-coated) on the bottom layer 50; however, it should be understood that, the insulation layer 60 may also be formed on the bottom layer 50 by roll-printing, transferring, or other manner. Therefore, the insulation layer 60 is bonded to the bottom layer 50 without using adhesive. Preferably, the bottom layer 50 has a surface 53 which is flat. A fiber portion 54 of the fabric layer 52 is exposed to the surface 53, such that the insulation layer 60 further enwraps the exposed fiber portion 54, resulting in an improved bond between the insulation layer 60 and the bottom layer 50.
The abrasive layer 70 is disposed on the insulation layer 60, and has a plurality of columnar-like cells 72. The abrasive layer 70 is a high polymeric elastomer 71, and is coated (for example, roll-coated or blade-coated) on the insulation layer 60; however, it should be understood that, the abrasive layer 70 may also be formed on the insulation layer 60 by roll-printing, transferring, or other manner. Therefore, the abrasive layer 70 is bonded to the insulation layer 60 without using adhesive. The abrasive layer 70 is made of PU, PP, PET, a high-polymer resin, or a mixer thereof. In this embodiment, the abrasive layer 70 is made of PU. The columnar-like cells 72 are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer 70. In this embodiment, the columnar-like cells 72 are columnar-shaped, and the depth of the columnar-like cells 72 is greater than one half of the overall thickness of the abrasive layer 70. The columnar-like cells 72 properly communicates with each other.
In this embodiment, the polishing pad 4 has a compression ratio of 5% to 50%, a compression-recovery ratio greater than 80%, a thickness of 0.5 to 3.0 mm, and a density of 0.2 to 0.6 g/cm3.
Then, the fabric layer 52 is immersed in a high-polymer solution, such that the high-polymer solution enwraps the fabric layer 52. The high-polymer solution may be a PU solution, a PP solution, a PET solution, a high-polymer resin solution, or a mixer thereof. In this embodiment, the high-polymer solution is a PU solution, containing 13% PU resin, 3% surfactant, 9% pigment, and 75% DMF. Finally, the high-polymer solution is cured to form the bottom layer 50.
Referring to Step S32, an insulation layer 60 is formed on the surface 53 of the bottom layer 50. In this embodiment, the insulation layer 60 is formed on the bottom layer 50 by coating (for example, roll-coating or blade-coating); however, it should be understood that, the insulation layer 60 may also be formed on the bottom layer 50 by roll-printing, transferring, or other manner. The insulation layer 60 is made of PU, PP, PET, a high-polymer resin, a thin metal layer, a metal powder, or other insulation material. In this embodiment, the insulation layer 60 comprises 17% PU and 83% MEK.
Preferably, a fiber portion 54 of the fabric layer 52 in Step S31 is exposed to the surface 53 so that the insulation layer 60 in Step S32 further enwraps the exposed fiber portion 54, resulting in a stronger bond between the insulation layer 60 and the bottom layer 50. It should be noted that the insulation layer 60 is bonded to the bottom layer 50 without using adhesive.
Referring to Step S33, a high polymeric elastomer 71 is formed on the insulation layer 60. In this embodiment, the high polymeric elastomer 71 is formed on the insulation layer 60 by coating (for example, roll-coating or blade-coating); however, it should be understood that, the high polymeric elastomer 71 may also be formed on the insulation layer 60 by roll-printing, transferring, or other manner. The high polymeric elastomer 71 may be a PU solution, a PP solution, a PET solution, a high-polymer resin solution, or a mixer thereof. In this embodiment, the high polymeric elastomer 71 is a PU solution, containing 15% PU resin, 3% surfactant, 15% pigment, and 67% DMF.
Referring to Step S34, the bottom layer 50, the insulation layer 60, and the high polymeric elastomer 71 are immersed in a curing solution so as to cure the high polymeric elastomer 71 to form an abrasive layer 70, and generate a plurality of columnar-like cells 72 in the abrasive layer 70. The columnar-like cells 72 properly communicate with each other. In this embodiment, the curing solution comprises DMF and water, and has a concentration of 15%.
Referring to Step S35, DMF is rinsed with hot water. Then, referring to Step S36, a drying step is carried out so as to obtain a semi-finished polishing pad having no exposed surface openings. Finally, referring to Step S37, a surface of the abrasive layer 70 is abraded such that the abrasive layer 70 has a plurality of surface openings, and scraps are removed by vacuum suction, so as to fabricate the polishing pad 4.
The polishing pad 4 fabricated according to this embodiment has a compression ratio of 28.30%, a compression-recovery ratio of 95.56%, a thickness of 1.6 mm, a density of 0.29 g/cm3, and a hardness of 36 Shore A.
In the present invention, the insulation layer 60 prevents the slurry from infiltrating into the bottom layer 50 during the polishing process, so as to improve the polishing effect and quality. Moreover, the columnar-like cells 72 are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer 70, and the depth of the columnar-like cells 72 is greater than one half of the overall thickness of the abrasive layer 70. Therefore, when applied in the polishing process, the polishing pad 4 may store a large amount of the slurry and scraps generated during the abrasion, thus improving the polishing efficiency and preventing the surface of the workpiece to be polished from being scratched. Moreover, the polishing pad 4 is more effectively buffered when put under a large downward force.
While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of the present invention are within the scope defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 097148792 | Dec 2008 | TW | national |
