Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
1999-12-17
2001-09-11
Hail, III, Joseph J. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S288000, C451S287000, C451S285000
Reexamination Certificate
active
06287172
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to chemical-mechanical polishing, and more particularly using elimination solution to improve a multi-step chemical-mechanical polishing method during the chemical-mechanical polishing is operating.
2. Description of the Prior Art
Chemical-mechanical polishing (CMP) is conventionally used in semiconductor manufacturing to achieve global planarity, usually with planarity greater than 94%. Normally the operation of the chemical-mechanical polishing combines both of chemical and mechanical effects. The chemical-mechanical polishing generally includes rotating table, where slurry and polishing pad are applied. Conventionally typical polishing slurry comprises SiO
2
, alumna Al
2
O
3
in an alkali solution.
There generally will be many particles existing on the surface of wafer after tungsten chemical-mechanical polishing WCMP process. All particles usually distribute onto the surface edge of wafer. Due to the inherent drawbacks of the chemical-mechanical polishing mechanism, the slurry effect is clearly observed after the chemical-mechanical polishing, causing serious alkali or acid solution effect including SiO
2
and Al
2
O
3
slurry, which disadvantageously affects following manufacturing process. Normally solution effect will appear obviously if oxide wafer with oxide slurry buffing process is carried out. However, particles would not exist on tungsten wafer with oxide slurry buffing process. Due to the pH rate of tungsten slurry is about 2.3 and the pH rate of oxide slurry is about 11. Probably the neutralization of chemical reaction happens leading to the special morphologic particles existed as FIG.
1
A. And
FIG. 1B
shows for its close-up dramatic picture.
According to the foregoing reasons, a method is exactly needed for eliminating the solution effect during the chemical-mechanical polishing in order to improve and reduce either alkali or acid solution effecting the result of polishing process.
SUMMARY OF THE INVENTION
In one embodiment, In accordance with the present invention, an improved chemical-mechanical polishing (CMP) method is provided that substantially eliminates the solution effect during the CMP process, thereby improving the alkali or acid solution of polishing process.
Therefore this method for chemical-mechanical polishing process is obviously disclosed. The method comprises following steps. First, a wafer is placed on a first pad of a CMP system, wherein a head fixes the wafer on said first pad. Then, the head is rotated and the wafer is polished on the first pad by using a tungsten slurry. Next, the wafer is transferred to place on a second pad of the CMP system, wherein the head fixes the wafer on the second pad. Following, the head is rotated and the wafer is polished on the second pad by using the tungsten slurry. Then, the wafer is cleaned on the second pad by using a de-ionic water. Next, the wafer is transferred to place on a third pad of the CMP system, wherein the head fixes the wafer on said third pad. Following, the wafer is cleaned on the third pad by using the de-ionic water. Last, the head is rotated and the wafer is polished on the third pad by using an oxide slurry, wherein a pH value of the tungsten slurry and a pH value of the oxide slurry are opposite.
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Kuan Tong-Hua
Lan Chin-Kun
Wang Hui-Ling
Wang Ying-Lang
Hail III Joseph J.
Taiwan Semiconductor Manufacturing Co. Ltd.
Wilson Lee
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