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  Polishing apparatusUSPTO Application #: 20070032174Title: Polishing apparatus Abstract: The present invention relates to a polishing apparatus for polishing a workpiece such as a semiconductor wafer to form a flat surface thereon. The polishing apparatus includes a polishing table (20), a polishing tool (1) attached to an upper surface of the polishing table (20), and a fluid passage (40) having openings on the upper surface of the polishing table (20). The apparatus is operable to bring a workpiece (W) into sliding contact with the polishing tool (1) to polish the workpiece while supplying a polishing liquid onto the polishing tool (1). The polishing tool (1) is fixed to the polishing table (20) by a vacuum produced in the fluid passage (40). (end of abstract)
Agent: Wenderoth, Lind & Ponack, L.L.P. - Washington, DC, US Inventor: Satoshi Nagai USPTO Applicaton #: 20070032174 - Class: 451041000 (USPTO) Related Patent Categories: Abrading, Abrading Process, Glass Or Stone Abrading The Patent Description & Claims data below is from USPTO Patent Application 20070032174. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a polishing apparatus, and more particularly to a polishing apparatus for polishing a workpiece such as a semiconductor wafer to form a flat surface thereon. BACKGROUND ART [0002] Planarizing a surface of a semiconductor device is becoming increasingly important in a semiconductor device fabrication process. One of the most important planarization techniques is chemical mechanical polishing (CMP). The chemical mechanical polishing is performed using a polishing apparatus. Specifically, a substrate, such a semiconductor wafer, is brought into sliding contact with a polishing surface while a polishing liquid containing abrasive particles such as silica (SiO.sub.2) is supplied onto the polishing surface, so that the substrate is polished. [0003] This kind of polishing apparatus comprises a polishing table having a cloth (polishing pad) attached to an upper surface thereof with an adhesive or the like, and a substrate holder, which is called a top ring or carrier head, for holding a semiconductor wafer. The polishing apparatus polishes a semiconductor wafer as follows. The substrate holder holds the semiconductor wafer and presses the semiconductor wafer against the polishing table at a predetermined pressure. At this time, a polishing liquid is supplied onto a polishing surface formed on an upper surface of the cloth, and the polishing table and the substrate holder are moved relative to each other to bring the semiconductor wafer into sliding contact with the polishing surface, whereby the semiconductor wafer is polished to have a flat and mirror-finished surface. [0004] In the above-mentioned polishing apparatus, the cloth (polishing pad) on the turn table is replaced as follows. Firstly, the operation of the polishing apparatus is stopped, and the cloth is removed from the polishing table. Next, adhering substances, such as the adhesive, and the polishing liquid remaining on the polishing table are washed away, and then the polishing table is dried. Thereafter, a new cloth is attached directly to the upper surface of the polishing table with the adhesive or the like, whereby replacement of the cloth is completed. [0005] Replacing the cloth in this manner is problematic because the cloth is replaced through various steps, which lower workability. Further, since the operation of the polishing apparatus should be stopped during replacement of the cloth, a longer replacement time results in a lower production lot per unit time. [0006] In order to solve such drawbacks, there has been known a method in which a cloth cartridge, having a pedestal (base) made of metal or the like and a cloth (polishing cloth), is detachably fixed to a polishing table with bolts, as disclosed in Japanese laid-open patent publication No. 8-118231. According to this method, the cloth can be replaced simply by changing the cloth cartridge, and hence an operation time for replacing the cloth can be shortened. Therefore, the polishing apparatus is only stopped for a short time, thus increasing the production lot per unit time. [0007] However, as the diameter of the semiconductor wafer, which is a workpiece to be polished, becomes large, the diameter of the cloth cartridge also becomes large, resulting in difficulty in handling the cloth cartridge. DISCLOSURE OF INVENTION [0008] The present invention has been made in view of the above drawbacks. It is, therefore, an object of the present invention to provide a polishing apparatus which can allow efficient replacement of the polishing pad to be disposed on the upper surface of the polishing table. [0009] In order to achieve the above object, according to an aspect of the present invention, there is provided a polishing apparatus comprising a polishing table, a polishing tool attached to an upper surface of the polishing table, and a fluid passage having openings on the upper surface of the polishing table. The polishing apparatus is operable to bring a workpiece into sliding contact with the polishing tool to polish the workpiece while supplying a polishing liquid onto the polishing tool. The polishing tool is fixed to the polishing table by a vacuum produced in the fluid passage. [0010] In a preferred aspect of the present invention, the polishing tool comprises a polishing pad, and a base on which the polishing pad is placed. The polishing tool is divided into a plurality of segments. [0011] According to the present invention having such structure, the polishing tool can be easily removed from the polishing table by releasing the vacuum produced in the fluid passage. Further, because the segments can be removed and attached one by one, the polishing tool (i.e., the polishing pad and the base) can be easily replaced, and hence operation efficiency can be improved. [0012] In a preferred aspect of the present invention, the base is made of resin or metal. [0013] According to the present invention having such structure, the used polishing tool (i.e., the polishing pad and the base) can be discarded as it is. Accordingly, replacement operation, which is to be performed in a manner such that the used polishing pad is removed and a new polishing pad is attached to the base, can be eliminated. Such operation may cause distortions of the base. [0014] In a preferred aspect of the present invention, the polishing pad and the base are made of the same material. [0015] According to the present invention having such structure, the polishing pad and the base are not required to be separated when the polishing tool is discarded. [0016] In a preferred aspect of the present invention, the polishing apparatus further comprises a gas-liquid separator for separating the polishing liquid and a gas from each other. The gas-liquid separator is disposed between the fluid passage and a vacuum source for producing the vacuum in the fluid passage. [0017] As described above, the polishing tool comprising the plurality of segments is fixed to the polishing table by the vacuum produced in the fluid passage. In this structure, however, the polishing liquid may be sucked together with an ambient gas into the fluid passage and the vacuum source. According to the present invention, even in a case where the polishing liquid flows into the fluid passage, the polishing liquid is collected by the gas-liquid separator before being sucked into the vacuum source. Therefore, the polishing liquid can be prevented from entering the vacuum source. [0018] In a preferred aspect of the present invention, the polishing apparatus further comprises a plurality of polishing liquid supply ports for supplying plural kinds of polishing liquids. [0019] Generally, it is necessary to switch the polishing liquid when switching the polishing process, and to replace the polishing tool according to the polishing process for the purpose of preventing cross contamination. Therefore, it is difficult for the conventional polishing apparatus to perform plural polishing processes. According to the present invention having the above structure, the polishing pad can be easily replaced according to the polishing processes. Therefore, by supplying desirable polishing liquids onto the polishing tool through the polishing liquid supply ports, the polishing apparatus can perform plural polishing processes by itself. BRIEF DESCRIPTION OF DRAWINGS [0020] FIG. 1 is a schematic cross-sectional view showing a polishing apparatus according to a first embodiment of the present invention; Continue reading... Full patent description for Polishing apparatus Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Polishing apparatus patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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