Abrading – Machine – Combined
Reexamination Certificate
2000-02-22
2003-05-20
Eley, Timothy V. (Department: 3724)
Abrading
Machine
Combined
C451S060000, C451S446000
Reexamination Certificate
active
06565422
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus for fabricating a wiring substrate and a fabrication method of a wiring substrate using such apparatus, particularly to a polishing apparatus and a polishing method for fabricating metal wirings for a semiconductor device by using a polishing operation.
In recent years, importance is given to planarizing of a surface of a wiring substrate for a large scale semiconductor integrated circuit (hereinafter, described as LSI). A method of Chemical Mechanical Polishing (CMP, hereinafter, described as polishing so far as the description is not specified otherwise) is regarded as one of the representative technologies.
Further, as a method of fabricating copper or a copper-based alloy (Here, a copper-based alloy means an alloy in which the weight percentage of Cu in the materials which compose the alloy is larger than the weight percentage of any other material in the alloy; hereinafter, described as copper alloy.) for interconnect metal lines, a method referred to as the damascene method attracts attention and is disclosed in, for example, JP-A-2-278822. Here, a single damascene method is described in U.S. Pat. No. 6,004,880, the contents of which are incorporated herein by reference in their entirety. And a dual damascene method is described in U.S. Pat. No. 6,004,188, the contents of which are incorporated herein by reference in their entirety. Among the methods, in respect of polishing a copper alloy, a detailed description has been given in JP-A-8-83780.
Methods of polishing are roughly classified into methods of using abrasive powders and methods of substantially not using abrasive powders. The former is mainly used for planarizing a surface of a predetermined substrate or removing projected portions of thin films. The latter has mainly been used for removing damaged or degraded portions of a surface after polishing using abrasive powders as described in, for example, JP-A-9-306881. Further, conventionally, according to the polishing operation of not using abrasive powders, generally polishing speed is extremely low and therefore, although there has been a technology of polishing without using abrasive grains with an object of removing a predetermined layer after a polishing using abrasive powders and thereafter removing mainly a damaged layer of the surface, it has been regarded as practically difficult to remove the predetermined layer by the polishing of not using abrasive grains. For example, in respect of polishing of aluminum, there has been proposed a method of using an alkaline polishing solution without including abrasive powders in Japanese Laid Open No.2-580939. However, according to the method, the polishing speed is as low as 30 nm/min at maximum. Further, in a practical point of view, polishing with high accuracy is difficult unless the ratio of polishing rate to etching rate is larger than 20 hereinafter, described as selectivity ratio), but the selectivity ratio of the proposed method is as small as 3 or smaller. Further, there has been carried out a trial in which a copper alloy is polished by an abrasive free solution. A description has been given to an example of using nitric acid or a mixture solution of nitric acid and hydrogen peroxide which does not include abrasive in Proceedings of Abrasive Fabrication Society 1997, volume 41, pp. 231-233. However, nitric acid is a chemical used in etching copper and according to the solution, the etching rate is as large as the polishing speed and therefore, although an effect of smoothing a polished face can be expected, in using it in a process of so-to-speak damascene wiring the process is devoid of consideration in respect of the etching rate and is not suitable for practical use.
Further, there is disclosed a method of polishing a silicon wafer or a glass substrate by a method of not including abrasive powder in a polishing solution by using a polishing pad (described as grindstone) including fixed abrasive powders of silica, cerium oxide or the like in place of a polishing pad made of polymer resin in JP-A-10-125880 or JP-A-8-64562. Further, Proceedings of SEMI Technology Symposium, 1998 edition p. 5-72 to p. 5-78, describes also a method of polishing a copper alloy by using a similar grindstone. However, the specific content of the grindstone or the polishing solution used is not disclosed and the grindstone and the polishing solution are supplied together from the supplier of the consumables.
Paying attention to an aspect of polishing characteristics, slurries are roughly classified into alkaline slurries (described as mechanical effect slurry) mainly realizing the polishing characteristics by mechanical effects and polishing liquids (solutions) enhancing a role of chemical reaction. The former is mainly used in polishing silicon oxide or silicon. In contrast thereto, a chemical effect suspension is mainly used in selective polishing. According to the chemical effect suspension, normally, in addition to abrasive powder and a dispersant, a chemical effect suspension including acids or salts of these is mixed with an oxidant immediately before the use to thereby constitute a slurry and the slurry is used in polishing by injecting it to a platen for polishing. As the oxidant, ferric nitrate, hydrogen peroxide, potassium iodate or aqueous solutions of these are known. Hereinafter, in respect of the chemical effect slurry, a liquid before mixing with an oxidant is referred to as a suspension and a liquid after having mixed with an oxidant is referred to as a slurry as a discrimination therebetween when the discrimination becomes necessary.
However, in the case of a chemical effect suspension, abrasive powders are liable to aggregate in the suspension and it is difficult to provide uniformly dispersed suspension. Further, even in the case of a suspension which has once dispersed, the suspension is liable to become a nonuniform suspension or slurry by the aggregation or settling of the powders. When a slurry in a nonuniformly dispersed state is used, polishing scratches are made on the surface of a metal film or insulating layer and results in a failure, and therefore, technologies for preventing these, for example, technologies for providing a uniformly dispersed suspension by, for example, a kind and a concentration of a dispersant or by stirring a solvent including abrasive powder and chemical components for a predetermined period of time while maintaining at a predetermined temperature, become an important problem in the technical aspect for polishing suspensions.
Further, a chemical effect suspension is produced by mixing abrasive powder and a dispersant thereof, further, a plurality of kinds of acid or complex salt, or a protective layer forming agent and so on under strict composition control and therefore, it is extremely difficult for a user to control the chemical components. Such a chemical effect slurry including abrasive powder requires complicated and delicate production steps and a long period of time seems to be required in the production.
As mentioned above, in the case of the chemical effect suspension, the composition is complicated and therefore, in using the chemical effect suspension continuously in fabricating interconnect substrates, a chemical effect suspension is transported from a production site to a site of using the chemical effect suspension, contained in a predetermined reception apparatus and thereafter, mixed with an oxidant at a predetermined rate and supplied and used in a polishing apparatus as a chemical effect slurry. The reception apparatus mentioned here indicates a suspension or slurry supply unit for an individual polishing apparatus, a concentrated reception apparatus for supplying the suspension or slurry to a plurality of polishing apparatuses or the like. In this way, according to a polishing method using a chemical effect suspension, chemical components of a slurry are complicated and the composition control is also difficult and therefore, there poses a problem in which in addition to the
Hom-ma Yoshio
Kimura Takeshi
Kondo Seiichi
Nezu Hiroki
Sakuma Noriyuki
Antonelli Terry Stout & Kraus LLP
Eley Timothy V.
LandOfFree
Polishing apparatus using substantially abrasive-free liquid... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polishing apparatus using substantially abrasive-free liquid..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polishing apparatus using substantially abrasive-free liquid... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3019596