Coating processes – Direct application of electrical – magnetic – wave – or... – Plasma
Reexamination Certificate
1999-02-01
2001-02-06
Beck, Shrive (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Plasma
C427S255700, C427S240000, C438S680000, C438S692000, C438S699000, C438S723000
Reexamination Certificate
active
06183819
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 88100009, filed Jan. 4, 1999, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for a semiconductor device fabrication. More particularly, the present invention relates to a method for processing a poly defect.
2. Description of the Related Art
In semiconductor manufacturing process, polysilicon is widely used to form a conductive layer, especially a gate conductive layer. However, defects are often formed on a polysilicon layer, called poly defects, while forming the polysilicon layer. The poly defects usually affect the subsequent photolithography and etching process, so that the device yield is decreased because of the poly defects. The defects are mostly formed by impurities left in a chamber used for forming the polysilicon layer. Most of the impurities are polysilicon particles left by the process for forming the polysilicon layer. When the reaction temperature is high or the concentration of the silicon source gas is high, the polysilicon particles are easily formed and adsorbed on the wall of the chamber. When too many polysilicon particles have been adsorbed, the polysilicon particles fall on chips and pollute them. The problem of impurities is avoided by cleaning the chamber, but the cleaning process takes one and a half to two days. Therefore, the throughput of devices is decreased when the reaction chamber is idle.
Conventionally, the poly defects are removed by a scrubber or a sprayer. However, the scrubber or sprayer generates stress, so that a recess or vacancy is generated and the oxide layer formed in the previous process is exposed. This recess or vacancy causes leakage current and open circuit or short circuit generation to result in the failure of the whole chip.
FIGS. 1A through 1B
are schematic, cross-sectional views showing the conventional processing steps for removing a poly defect. Referring to
FIG. 1A
, a substrate
10
is provided, and an oxide layer
12
including a gate oxide layer and a field oxide layer is formed on the substrate
10
. A polysilicon layer
14
is formed on the oxide layer
12
. A poly defect
16
is formed on the polysilicon layer
14
surface simultaneous with the formation of the polysilicon layer
14
. The height of the poly defect
16
is about 0.5-3 micrometer.
Referring to
FIG. 1B
, the poly defect
16
is removed by scrubber or sprayer. The scrubber or sprayer generates stress, so that a recess or vacancy
18
is generated and the oxide layer
12
formed in the previous process is exposed. Therefore, the poly defect
16
causes a leakage current and an open circuit or a short circuit which result in the failure of the whole chip. The effect of removing the poly defect
16
by scrubber or sprayer is limited.
SUMMARY OF THE INVENTION
Accordingly, the purpose of the present invention is to provide a method for removing a poly defect. The method can effectively process the poly defect and avoid creating a recess or vacancy on the polysilicon layer.
Another object of the present invention is to provide a method for processing a poly defect. The method does not affect the previous structure and can increase yield to reduce capital expenditure.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a method for removing a poly defect. A substrate is provided, and a first oxide layer is formed on the substrate. A polysilicon layer is formed on the first oxide layer. A poly defect is formed on the polysilicon layer surface simultaneous with polysilicon layer formation. A second oxide layer is formed conformal to the substrate, the second oxide layer and the poly defect are removed by polishing until a thin second oxide layer and a thin poly defect are left. Finally, the thin second oxide layer is removed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4616404 (1986-10-01), Wang et al.
patent: 4981811 (1991-01-01), Feygenson et al.
patent: 5336365 (1994-08-01), Goda et al.
patent: 5677204 (1997-10-01), Imai et al.
patent: 5837595 (1998-11-01), Ahn et al.
patent: 5963818 (1998-11-01), Kao et al.
Feng Yung-Hui
Tsai Chen-Chih
Beck Shrive
Chen Bret
Huang Jiawei
J.C. Patents
United Semiconductor Corp.
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