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Publication numberUS20030216111 A1
Publication typeApplication
Application numberUS 10/151,783
Publication dateNov 20, 2003
Filing dateMay 20, 2002
Priority dateMay 20, 2002
Also published asWO2003097298A1
Publication number10151783, 151783, US 2003/0216111 A1, US 2003/216111 A1, US 20030216111 A1, US 20030216111A1, US 2003216111 A1, US 2003216111A1, US-A1-20030216111, US-A1-2003216111, US2003/0216111A1, US2003/216111A1, US20030216111 A1, US20030216111A1, US2003216111 A1, US2003216111A1
InventorsHisatomo Ohno, Jun Watanabe, Toshihiro Izumi, Yasushi Yoshizawa
Original AssigneeNihon Microcoating Co., Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Non-foamed polishing pad and polishing method therewith
US 20030216111 A1
Abstract
A polishing pad made of a non-foamed resin material has surface roughness Ra in the range of 0.1-10 μm, or preferably 0.5-1.5 μm and variations in thickness less than 50 μm, or preferably less than 30 μm. Its Shore D hardness is greater than 60 degrees, or preferably 68 degrees. Its compressibility is less than 3%, or preferably less than 1% and its elasticity is greater than 30%, or preferably 50%, as measured by specified methods. Grooves may be formed over 30%-70%, or preferably 40%-60% of the total area of the polishing surface. When the polishing surface is subjected to a dressing process, its surface roughness Ra is restored to 0.1-10 μm, or preferably 0.5-1.5 μm.
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Claims(20)
What is claimed is:
1. A polishing pad consisting substantially of a non-foamed resin material having a polishing surface with surface roughness Ra in the range of 0.1-10 μm and variations in thickness less than 50 μm.
2. The polishing pad of claim 1 having surface roughness Ra in the range of 0.5-1.5 μm and variations in thickness less than 30 μm.
3. The polishing pad of claim 1 wherein said resin material has Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30%.
4. The polishing pad of claim 2 wherein said resin material has Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30%.
5. The polishing pad of claim 3 wherein said resin material has Shore D hardness greater than 68 degrees, compressibility less than 1% and elasticity greater than 50%.
6. The polishing pad of claim 4 wherein said resin material has Shore D hardness greater than 68 degrees, compressibility less than 1% and elasticity greater than 50%.
7. The polishing pad of claim 4 wherein said polishing surface has grooves formed thereon over 30%-70% of the area of said polishing surface.
8. The polishing pad of claim 7 wherein said polishing surface has grooves formed thereon over 40%-60% of the area of said polishing surface.
9. A method of polishing a target surface of an object, said method comprising the steps of:
preparing a polishing pad consisting substantially of a non-foamed resin material having a polishing surface with surface roughness Ra in the range of 0.1-1.10 μm and variations in thickness less than 30 μm; and
pressing said polishing surface of said polishing pad against said target surface and causing a relative motion between said polishing pad and said target surface.
10. The method of claim 9 wherein said polishing surface has surface roughness Ra in the range of 0.5-1.5 μm and variations in thickness of said polishing pad is less than 10 μm.
11. The method of claim 9 further comprising the step of subjecting said polishing surface of said polishing pad to a dressing process such that the surface roughness Ra of said polishing surface returns to the range of 0.1-10 μm and variations in thickness of said polishing pad return to less than 30 μm.
12. The method of claim 10 further comprising the step of subjecting said polishing surface of said polishing pad to a dressing process such that the surface roughness Ra of said polishing surface returns to the range of 0.5-1.5 μm and variations in thickness of said polishing pad return to less than 10 μm.
13. The method of claim 9 wherein said resin material has Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30%.
14. The method of claim 10 wherein said resin material has Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30%.
15. The method of claim 11 wherein said resin material has Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30%.
16. The method of claim 12 wherein said resin material has Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30%.
17. The method of claim 13 wherein said resin material has Shore D hardness greater than 68 degrees, compressibility less than 1% and elasticity greater than 50%.
18. The method of claim 14 wherein said resin material has Shore D hardness greater than 68 degrees, compressibility less than 1% and elasticity greater than 50%.
19. The method of claim 15 wherein said resin material has Shore D hardness greater than 68 degrees, compressibility less than 1% and elasticity greater than 50%.
20. The method of claim 16 wherein said resin material has Shore D hardness greater than 68 degrees, compressibility less than 1% and elasticity greater than 50%.
Description
    BACKGROUND OF THE INVENTION
  • [0001]
    This invention relates to a polishing pad comprised of a non-foamed resin material, as well as a polishing method by using such a pad.
  • [0002]
    Pads made of different materials with different physical characteristics have been used for the so-called planarization polishing of the surface of electronic devices such as semiconductor substrates and magnetic disk substrates. Foamed urethane pads have been commonly used for the chemical mechanical polishing (CMP) of semiconductor devices because foamed pads with air bubbles inside have certain advantages such as their ability to take in particles scraped off from the polished surface inside such internally formed bubbles. Pads made of a foamed material such as foamed urethane, however, have certain disadvantages such as the difficulty in controlling the thickness and providing a uniform abrading surface and the inability to carry out a very fine polishing work.
  • SUMMARY OF THE INVENTION
  • [0003]
    It is therefore a general object of this invention to provide a polishing pad without such disadvantages which are common to pads made of a foamed material and hence better suited for the fine polishing.
  • [0004]
    It is another object of this invention to provide a method of using such a polishing pad to perform an improved polishing work.
  • [0005]
    This invention is based on the discovery by the present inventors that polishing pads made of a non-foamed material and having certain physical characteristics can accomplish the above and other objects. In particular, a polishing pad embodying this invention may be characterized as substantially comprising a non-foamed resin material such as non-foamed acrylic resin, urethane and polyesters and having surface roughness Ra in the range of 0.1-10 μm, or preferably 0.5-1.5 μm and variations in thickness less than 30 μm, or preferably less than 10 μm. Such conditions are normally not satisfied by a pad made of a foamed material such as prior art foamed urethane pads. Polishing pads according to a preferred embodiment of this invention may be further characterized as having Shore D hardness greater than 60 degrees, compressibility less than 3% and elasticity greater than 30% as measured by specified methods.
  • [0006]
    The polishing surface of the pad may be grooved, such grooves being formed over 30%-70%, or preferably 40%-60% of the total area of the polishing surface.
  • [0007]
    The polishing pad of this invention thus characterized may be used in a conventional way, being pressed against a target surface to be polished and caused to move relative to the target surface, say, by means of a polishing machine of a known kind. A so-called dressing process of a known kind may be carried out to restore the initial condition of the polishing surface. The dressing process carried out in a method embodying this invention is characterized in that the surface roughness Ra of the polishing surface after the dressing process is again in the range of 0.1-10 μm, or preferably 0.5-1.5 μm.
  • DETAILED DESCRIPTION OF THE INVENTION
  • [0008]
    Polishing pads according to this invention, which may be used for fine polishing of semiconductor devices such as semiconductor substrates and magnetic disk substrates, are characterized firstly as being made of a non-foamed resin material such as non-foamed acrylic resin, urethane and polyesters and secondly as having a polishing surface with surface roughness Ra in the range of 0.1-10 μm or preferably 0.5-1.5 μm and variations in thickness less than 30 μm or preferably less than 10 μm.
  • [0009]
    Pads with surface roughness in such ranges can be prepared by using a rotary belt for a buffing process, by a facing process or by using a diamond grinder. Pads with such uniformity in thickness can be produced by a grinding process. Such pads are advantageous because their use can be started without initially subjecting them to a so-called dressing process, which is a process for conditioning the polishing surface of a polishing pad, say, by removing particles clogging the polishing surface. This process is usually time-consuming.
  • [0010]
    With a polishing pad made of a foamed material, the size and positions of air bubbles are not uniform, and some air bubbles are at the polishing surface, opening to the exterior. Thus, the surface roughness is usually much greater, and it is much more difficult to control its uniformity. In other words, polishing pads made of a non-foamed material according to this invention are better suited for fine polishing of device surfaces requiring a higher degree of precision.
  • [0011]
    Another advantage of using a non-foamed material is that non-foamed materials generally have a better thermal conductivity than foamed materials because foamed materials have air bubbles inside and air is a poor thermal conductor. Heat is generated as a polishing pad is used for polishing a target surface, and although the rate of chemical mechanical polishing may be improved by raising temperature, a strict temperature control is necessary for reducing variations in the rate of polishing. Table 1 shows a result of an experiment for comparing the thermal conductivity of foamed and non-foamed pads of a same material and a same thickness of 1.0 cm. In this experiment, these pads were placed on a plate maintained at 55 C. and the changes in the temperatures at their top surfaces were measured at intervals of 5 minutes. Table 1 clearly shows that a pad made of a non-formed material has a much higher heat conductivity and hence is better suited for the temperature control in chemical physical polishing.
    TABLE 1
    Heating
    time Surface temperature of a Surface temperature of
    (minute) non-foamed pad ( C.) a formed pad ( C.)
    0 23.8 23.8
    5 28.9 27.5
    10 31.5 29.2
    15 31.7 29.5
    20 33.7 30.2
    25 34.7 30.4
    30 37.9 29.2
    35 42.5 36.5
    40 43.2 37.0
    45 43.9 37.3
  • [0012]
    Polishing pads made of a foamed material have air bubbles opening on the polishing surface and hence abraded particles can be stored in them. This cannot be done with a pad made of a non-foamed material. Thus, the polishing process with a non-foamed pad can proceed quickly if the target surface being polished is uneven, having protrusions and indentations, but the process slows down after the target surface becomes flat. In the chemical mechanical polishing of an oxide layer formed on a circuit wiring, the process is stopped when the oxide layer is planarized but it is a common practice to continue the polishing until the entire surface is planarized. Since the polishing with a non-foamed pad becomes slower at planarized parts, the thickness of the oxide layer is reduced so as to reduce the burden on the chemical mechanical polishing. If the pad is too soft, the processing becomes too dependent on the wiring pattern. In order to overcome this problem, it is preferable that the Shore D hardness of the pad be greater than 60 degrees, and more preferably greater than 68%.
  • [0013]
    In terms of compressibility and elasticity, a non-foamed pad of this invention may be characterized as having compressibility less than 3%, or preferably less than 1%, and elasticity greater than 30%, or preferably greater than 50%. The compressibility and elasticity are the values obtained from a sample piece of a suitable size by measuring its thickness T0 while compressing it with an initial load of 80 g, further adding an extra load of 800 g for 5 minutes and measuring its thickness T1 afterward, removing this total load of 880 g and thereafter subjecting it to the initial load of 80 g for 30 seconds to measure its thickness T0′ again. The compressibility is calculated as 100(T0−T1)/T0 and the compressive elasticity is calculated as 100(T0′−T1)/(T0−T1).
  • [0014]
    The polishing surface may be provided with grooves not only for collecting polished off particles but also for stabilizing the slurry flow and distribution pressure uniformly. If the ratio of the portion of the polishing surface where grooves are formed is too large, however, the contact area with the target surface to be polished may become insufficient and efficiency of the polishing is adversely affected. This ratio is preferably 30%-70%, and more preferably 40-60%.
  • [0015]
    A polishing pad as described above may be used in combination with a polishing machine of a known kind such that its polishing surface is compressed against the target surface to be polished and is caused to move relative to the target surface. After the condition of the polishing surface of a polishing pad has been sufficiently deteriorated by use, it has been known to rejuvenate the pad, for example, by removing the particles that are clogging the polishing surface. The process of bringing back the initial condition of the polishing surface, say, by using a diamond conditioner for polishing, is variously called a dressing process, a conditioning process or a seasoning process. Such a process may also be included as a part of a method according to the invention. The dressing process in a method embodying this invention is characterized in that the polishing surface of a pad made of a non-foamed material, after being subjected to such a dressing process, has surface roughness Ra in the range of 0.1-10 μm, or preferably 0.5-1.5 μm.
Patent Citations
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US20030181155 *Mar 24, 2003Sep 25, 2003West Thomas E.Smooth pads for CMP and polishing substrates
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7241206 *Feb 17, 2006Jul 10, 2007Chien-Min SungTools for polishing and associated methods
US7494404Jul 6, 2007Feb 24, 2009Chien-Min SungTools for polishing and associated methods
US7544117Jul 25, 2007Jun 9, 2009Chien-Min SungTools for polishing and associated methods
US20050020188 *Jun 14, 2004Jan 27, 2005Mitsuru SaitoPolishing pad, method of producing same, and polishing method
US20050239380 *Apr 21, 2005Oct 27, 2005Jsr CorporationChemical mechanical polishing pad, manufacturing process thereof and chemical mechanical polishing method
US20070161720 *Nov 21, 2006Jul 12, 2007Applied Materials, Inc.Polishing Pad with Surface Roughness
US20070289223 *Jul 6, 2007Dec 20, 2007Chien-Min SungTools for polishing and associated methods
US20080014846 *Jul 25, 2007Jan 17, 2008Chien-Min SungTools for polishing and associated methods
US20080209816 *Jun 26, 2007Sep 4, 2008Chien-Min SungTools for polishing and associated methods
Classifications
U.S. Classification451/56, 451/456
International ClassificationB24B37/24, B24D11/00, B24D13/14
Cooperative ClassificationB24B37/24
European ClassificationB24B37/24
Legal Events
DateCodeEventDescription
May 20, 2002ASAssignment
Owner name: NIHON MICROCOATING CO., LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OHNO, HISATOMO;WATANABE, JUN;IZUMI, TOSHIHIRO;AND OTHERS;REEL/FRAME:012926/0422;SIGNING DATES FROM 20020501 TO 20020509
Oct 14, 2003ASAssignment
Owner name: NIHON MICROCOATING CO., LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OHNO, HISATOMO;WATANABE, JUN;IZUMI, TOSHIHIRO;AND OTHERS;REEL/FRAME:014593/0200
Effective date: 20030910