Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – Insulated gate formation
Reexamination Certificate
1999-12-31
2004-12-21
Wilczewski, Mary (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
Insulated gate formation
C438S592000
Reexamination Certificate
active
06833315
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to remove silicon oxynitride on semiconductor substrate, more particularly to remove silicon oxynitride without effecting the shape of the gate portions.
2. Description of the Prior Art
Using silicon oxynitride (SiON) as the bottom anti-reflection coating layer for the deep sub-micro device is the well-known process to SRAM technique. Normally, the conventional process can be indicated as the following statement.
First of all,
FIG. 1A
shows that there semiconductor substrate
10
, gate oxide
11
, undo-type polysilicon
12
, N+ type polysilicon
13
and silicon oxynitride
14
are all provided.
Then, silicon oxynitride
14
is removed by the, hot H
3
PO
4
solution as FIG.
1
B. However, unfortunately it is found at this step that the implanted N+-type polysilicon gate will be damaged by the hot H
3
PO
4
solution. Especially, shape of the implanted N+-type polysilicon gate is not shown as the purpose shape.
Thus, a new improvement technology is indeed necessary according to the above statement.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method is provided for removing silicon oxynitride that substantially keeps the purpose shape of the underlying gate.
In one embodiment, a method for removing silicon oxynitride of polysilicon gates in fabricating integrated circuits will be the following. A semiconductor substrate is provided over which a doped polysilicon gate and an undoped polysilicon gate are formed, and an oxynitride layer used as an anti-reflective coating (ARC) is formed on the surface of the polysilicon gates. Then, a photoresist layer is coated over the substrate and the oxynitride layer. A reverse mask is utilized to remove the photoresist on a major portion of the surface of the undoped polysilicon gate. A portion of the photoresist layer is etched back such that the sidewall and surface of the oxynitride layer are exposed. The oxynitride layer is dry etched, wherein the doped and the undoped polysilicon gates are protected by the remaining photoresist layer while removing the oxynitride layer. The remaining photoresist layer is removed until the surface of the substrate is exposed. Finally, the surfaces of the doped and the undoped polysilicon gates and the substrate are all cleaned.
REFERENCES:
patent: 5700737 (1997-12-01), Yu
patent: 5856225 (1999-01-01), Lee
patent: 6074905 (2000-06-01), Hu
patent: 6103634 (2000-08-01), Dunton
patent: 6165881 (2000-12-01), Tao
patent: 6191046 (2001-02-01), Singh
patent: 6200886 (2001-03-01), Yu
Powell Goldstein Frazer & Murphy LLP
United Microelectronics Corp.
Wilczewski Mary
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