Abrading – Abrading process – Abradant supplying
Reexamination Certificate
1999-04-15
2001-02-06
Scherbel, David A. (Department: 3723)
Abrading
Abrading process
Abradant supplying
C451S006000, C451S007000, C451S053000, C451S446000, C210S739000, C385S128000, C438S693000
Reexamination Certificate
active
06183351
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of supplying a chemical mechanical polishing liquid and an apparatus therefor.
Logic devices in the semiconductor devices are required to exhibit excellent high speed performances. In order to form multilevel interconnection structure, a process is necessary for carrying out a chemical mechanical polishing to a metal layer such as a tungsten layer, wherein an oxidizing agent is used for oxidizing the metal layer as a chemical polishing and subsequently removing the oxidized metal layer with polishing particles as a mechanical polishing. In order to rise the rate of the chemical and mechanical polishing, it is necessary to use an oxidizing agent as a solvent which has a large oxidizing capability.
The chemical mechanical polishing to the tungsten layer may be carried out by polishing agents. One of the available polishing agents which may, for example, comprise a mixing solution of hydrogen peroxide and iron nitrate as an oxidizing agent added with silica particles. Other available polishing agent comprises a polishing solution including KI03 as an oxidizing agent and alumina particles. Further another available polishing agent is an iron nitrate polishing solution showing a high polishing rate.
FIG. 1
is a schematic view illustrative of a conventional chemical mechanical polishing system, wherein an iron nitrate is used as a polishing liquid Iron Fe acts as a catalyst in the hydrogen peroxide solution for Fenton's oxidation to efficiently generate OH-radicals. Oxidizing power of the OH-radicals oxidizes tungsten to form WO
4
2-
ions which promotes chemical etching to tungsten, resulting in an increase in rate of the chemical mechanical polishing.
Heavy metal such as Fe is added in small amount into the solvent for increasing the oxidizing power. However, such heavy metal is likely to reside on the polishing surface of the device. This residual heavy metal contaminates the device thereby deterioration in performances and characteristics of the contaminated device, whereby the reliability of the semiconductor device is lowered. In addition the residual heavy metal on the device also results in a further contamination of the as a cross contamination of the production line or manufacturing line. The cross contamination is extremely serious problem when the logic device is manufactured in the common production lime to DRAM which requires an extremely high cleaning level.
In the above circumstances, it had been required to develop a novel method of chemical mechanical polishing to a metal layer in surface of a semiconductor device free from the above problems.
SUMMARY OF THE INVENTION
Accordingly; it is an object of the present invention to provide a novel method of chemical mechanical polishing to a metal layer in a surface of a semiconductor device free from the above problems.
It is a further object of the present invention to provide a novel method of chemical mechanical polishing to a metal layer in a surface of a semiconductor device free from a problem with a heavy metal contamination to the polished surface of the semiconductor device.
It is a still further object of the present invention to provide a novel chemical mechanical polishing to a metal layer in a surface of a semiconductor device using a polishing liquid which is free of added heavy metal and possessing a high cleaning power.
It is yet a further object of the present invention to provide a novel method of supplying a polishing liquid for carrying out a chemical mechanical polishing to a metal layer in a surface of a semiconductor device, which is free from the above problems.
It is a further more object of the present invention to provide a novel method of supplying a polishing liquid for carrying out a chemical mechanical polishing to a metal layer in a surface of a semiconductor device, which is free from a problem with a heavy metal contamination to the polished surface of the semiconductor device.
It is still more object of the present invention to provide a novel method of supplying a polishing liquid for carrying out a chemical mechanical polishing to a metal layer in a surface of a semiconductor device, wherein the polishing liquid is free of added heavy metal and possesses a high cleaning power.
It is moreover object of the present invention to provide a novel apparatus for chemical mechanical polishing to a metal layer in a surface of a semiconductor device free from the above problems.
It is another object of the present invention to provide a novel apparatus for chemical mechanical polishing to a metal layer in a surface of a semiconductor device free from a problem with a heavy metal contamination to the polished surface of the semiconductor device.
It is still another object of the present invention to provide a novel apparatus for chemical mechanical polishing to a metal layer in a surface of a semiconductor device using a polishing liquid which is free of added heavy metal and possessing a high cleaning power.
The present invention provides an apparatus for activating a polishing liquid including polishing particles and hydrogen peroxide for carrying out a chemical mechanical polishing method to a surface of a wafer to be polished, wherein the apparatus comprises an ultraviolet ray irradiation system for an irradiation of an ultraviolet ray to the polishing liquid. The polishing liquid is free of any heavy metal which provides contamination to the polished surface of the wafer. The hydrogen peroxide in the polishing liquid is activated by the ultraviolet ray irradiation to form or generate OH-radicals which possesses such a high oxidizing power as the conventional iron nitrate containing polishing liquid.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.
REFERENCES:
patent: 5703988 (1997-12-01), Oishi et al.
patent: 5787047 (1998-08-01), Tekawa
patent: 5922620 (1999-07-01), Shimomura et al.
patent: 6012967 (2000-01-01), Satake et al.
patent: 6040245 (2000-03-01), Sandhu et al.
NEC Corporation
Nguyen George
Scherbel David A.
Scully Scott Murphy & Presser
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