Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Reexamination Certificate
2002-02-25
2004-02-03
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
C442S281000, C442S110000, C442S117000, C442S148000, C442S164000, C442S168000, C442S169000, C442S172000, C442S175000, C442S180000, C442S268000, C442S277000, C442S278000
Reexamination Certificate
active
06686023
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polished-piece holder and more particularly to a holder for holding a piece to be polished (hereinafter referred to as “polished piece”), such as a silicon wafer and hard disk, and also to a method of manufacturing the polished-piece holder.
A process of manufacturing silicon wafers and hard disks includes a step of polishing surfaces of polished pieces such as silicon wafers and hard disks. The polished pieces are held in the polished-piece holder for polishing operations. The polished-piece holder is shaped like a disk which has a gear formed on its outer circumference for driving it to rotate and also has one or more through-holes in which to fit and hold the polished pieces. The polished-piece holder with one or more polished pieces fitted in the through-holes is mounted in a polishing apparatus. The polished-piece holder is rotated in a plane including the surface of the disk while being driven in a planetary motion about a sun gear of the polishing apparatus as a center.
General conventional polished-piece holders are made by processing a disk formed of a laminated plate impregnated with thermosetting resin. Among the thermosetting resin impregnated laminated plates are a laminated plate of a glass fiber fabric substrate impregnated with epoxy resin, a laminated plate of an aramid fiber nonwoven fabric substrate impregnated with epoxy resin, and a laminated plate of cotton cloth substrate impregnated with phenol resin. The resin to be impregnated is generally a thermosetting resin not containing inorganic or organic particles.
U.S. Pat. No. 6,291,373 discloses a technique for manufacturing a polished-piece holder which involves impregnating an aramid fiber nonwoven fabric substrate with epoxy resin and drying it to form prepregs, laminating one or more prepregs to form a laminated sheet, and molding it under heat and pressure into the holder.
In performing the polishing operation, the polished-piece holder is mounted on the polishing apparatus and the polished pieces are fitted in the through-holes of the polished-piece holder. Then, a water-based polishing liquid having silica (SiO
2
), alumina (Al
2
O
3
) and ceria (CeO
2
) dispersed therein is supplied onto the surfaces of the polished pieces while rotating the holder and a polishing pad (held in an upper block of the polishing apparatus) arranged on the surfaces of the polished pieces relative to each other to polish the surfaces of the polished pieces.
When the polished-piece holder is to be mounted on or dismounted from the polishing apparatus as during the polished-piece holder replacement, this is done manually or by an automated machine. In recent years, this replacement operation is often performed by an automated machine. The removal of the polished pieces from the holder and the installing of unprocessed polished pieces on the holder are being performed by an automated machine with increasing frequency.
The polishing operation uses a water-based polishing liquid as described above, so that the polished-piece holder is likely to adhere to the polishing pad of the polishing apparatus through the water-based polishing liquid. As a result, when the upper block is lifted to take out the polished pieces from the holder or to replace the holder, the polished-piece holder may remain sticking to the polishing pad and be lifted together with the pad or even the polished pieces may be lifted up together with the holder. Such an incident may not pose a serious problem when the mounting or dismounting of the polished-piece holder and the removal or installing of the polished pieces are performed manually. When these operations are done by an automated machine, however, such an incident will cause the production line to stop.
It is therefore an object of the present invention to provide a polished-piece holder which does not easily adsorb or stick to a polishing pad of a polishing apparatus.
Another object of the present invention is to provide a polished-piece holder which can diminish possibilities of failure of polished pieces due to production line troubles.
Still another object of the present invention is to provide a polished-piece holder which can enhance an efficiency of a polishing operation.
A further object of the present invention is to provide a method of manufacturing a polished-piece holder which does not easily adhere or stick to a polishing pad of a polishing apparatus.
SUMMARY OF THE INVENTION
The present invention relates to an improvement on a polished-piece holder formed from a thermosetting resin impregnated fiber plate with a surface layer. The fiber plate comprises a single sheet of thermosetting resin impregnated fiber substrate or a laminated sheet formed by laminating a plurality of sheets of thermosetting resin impregnated fiber substrate. The single sheet or laminated sheet is heated and pressurized to form the fiber plate.
The thermosetting resin impregnated fiber plate used in this invention is characterized in that the surface layer has over its almost entire area a surface roughness with a maximum wave height Ry of 10 &mgr;m or greater. The maximum wave height Ry is determined in an evaluation portion of a wave curve by summing a height Rp of a highest crest and a depth Rv of a deepest trough or valley from an average line of the wave curve. The evaluation portion has a certain length in a direction of the average line. The wave curve is taken from a cross-sectional curve obtained by a surface roughness measuring device.
It is considered that the cross-sectional curve obtained by the surface roughness measuring device comprises a “surface waviness curve” or a “wave curve” with a low frequency, i.e., a long wavelength, and a “roughness curve” with a short wavelength, i.e., a high frequency, which is obtained by removing the wave curve component from the cross-sectional curve. Generally, the wavelength of the wave curve is 30 to 100 times that of the roughness curve.
The “average line” of the wave curve means an imaginary straight line as a centerline along which a converted wave curve extends. The converted curve is obtained by converting the wave curve in such a manner that the converted wave curve extends along the centerline. The evaluation portion having a certain length in the direction of the average line and extracted from the wave curve needs to be long enough for the state of the surface layer to be measured correctly. It is generally said that the evaluation portion preferably has a length four or five times the cutoff value that is set when the measurement is made by the surface roughness measuring device.
The “crest” in the wave curve is that portion of the curve situated between adjoining two of a plurality of intersections between the average line and the wave curve which lies above the average line. The “trough” in the wave curve is that portion of the curve situated between adjoining two of a plurality of intersections between the average line and the wave curve which lies below the average line.
In making the polished-piece holder, the use of the thermosetting resin impregnated fiber plate whose surface layer has the maximum wave height Ry—a parameter used to evaluate the surface roughness—of 10 &mgr;m or higher over an almost entire area offers an advantage of being able to prevent the polished-piece holder from easily adhering or sticking to the polishing pad of the polishing apparatus without affecting the polishing result. An upper limit of this parameter is a value that does not adversely affect the polishing operation on the polished pieces. This value varies depending on the material and surface state of the polishing pad used in the polishing apparatus and on the property of the water-based polishing agent. Studies conducted by this inventor have found that the maximum wave height Ry ranging from 10 &mgr;m to 30 &mgr;m, both inclusive, leads to a satisfactory polishing result almost without being affected by the material and surface state of the polishing pad and the property of the water-based polishing
Hiraoka Hirokazu
Noda Masayuki
Takahashi Katsuji
Nordmeyer Patricia L.
Pearne & Gordon LLP
Pyon Harold
Shin-Kobe Electric Machinery Co. Ltd.
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