Semiconductor device manufacturing: process – Chemical etching – Combined with the removal of material by nonchemical means
Reexamination Certificate
2000-02-21
2001-09-04
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Chemical etching
Combined with the removal of material by nonchemical means
C438S712000
Reexamination Certificate
active
06284659
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for minimizing defect sources that are located inside a high density plasma reactor. Particularly, the present invention relates to a method for cleaning the high density plasma reactor by a cycle purge process in which defect sources are clean up by gas.
2. Description of the Prior Art
Currently, the high density plasma reactor has become an important piece of equipment for high density plasma provides an efficient way to overcome many disadvantages of both conventional chemical vapor deposition (CVD) and conventional physical vapor deposition (PVD) process. Further, owing to the fact that the reaction of high density plasma process comprises both depositing reaction and etching reaction at the same time, it is natural that high density plasma also provides an efficient way of performing the etching process.
However, because the density of high density plasma is larger than both conventional CVD and conventional PVD, the quantity of defect sources inside the high density plasma reactor is larger than that of a conventional reactor. Significantly, because the etching process will remove something from the wafer, the quantity of defect sources is further increased. Thus, when a high density plasma reactor is used to continuously process numerous wafers or to continuouly perform numerous processes, the risk that the reactor is contaminated by defect sources cannot be neglected.
A practical example is the high density plasma etcher that is used to perform a W (tungsten) etching back process. Whenever numerous wafers are processed in regular order, it is unavoidable that defect sources continuouly accumulated and some defect sources will drop on top of the surface of the wafer. In other words, some invidual external defects are formed on the wafer, and according to practical experience, these external defects are inclined to collect at the center of the wafer.
Therefore, in order to enhance the practicality of high density plasma, it is desired for a method of cleaning the high density plasma reactor is to eliminate (or at least minimize) the risk of defects. Furthermore, in order not to degrade performance of the high density plasma, the required method should not be accomplished by changing the parameters of high density plasma such as density, temperature and so on.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a method for minimizing defect sources inside a high density plasma reactor, especially the high density plasma etcher.
A concrete object of the invention is to provide a method that enhances performance of high density plasma without any modification on parameters of high density plasma.
A further object of the invention is to overcome an the obvious disadvantages of the conventional high density plasma reactor where the quality of the wafer is degraded by unavoidable external defects.
Another object of this invention is to provide a practical and simple method to minimize defects that are induced by high density plasma.
First preferred embodiment is a method of minimizing defect sources inside a high density plasma reactor. The present method comprises the following steps. First, numerous semiconductor processes are performed by the high density plasma reactor and a cumulative operating duration of the high density plasma reactor is recorded. Second, whenever the cumulative operating duration does not exceed a predetermined limitation, numerous semiconductor processes are continuously performed by the high density plasma reactor excesses. Third, whenever the cumulative operation duration exceeds the predetermined limitation, operation of the high density plasma reactor is stopped and a cycle purge process is performed to minimize the quantity of defect sources inside the high density plasma reactor. The so-called cycle purge process comprises following basic steps. First, the high density plasma reactor is filled by a cleaning gas. Second, the cleaning gas is pumped out of the high density plasma reactor, wherein some defect sources inside the high density plasma reactor are carried out with the cleaning gas. After the so-called cycle purge process is finished, the cumulative operating duration is reset to zero and the first step of the method of the present invention is performed again.
Another preferred embodiment of the present invention is a method of cleaning a high density plasma etcher. The embodiment comprises two essential steps. First, the high density plasma etcher is filled by a cleaning gas. Second, the cleaning gas is pumped out of the high density plasma etcher, wherein numerous defect sources that arise inside the high density plasma etcher are carried out with the cleaning gas.
REFERENCES:
patent: 4902638 (1990-02-01), Muto
patent: 5846373 (1998-12-01), Pirkle et al.
patent: 6077386 (2000-06-01), Smith, Jr. et al.
patent: 6093655 (2000-07-01), Donohoe et al.
Dang Phuc T.
Nelms David
United Microelectronics Corp.
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