Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1998-05-11
2001-09-25
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S317000, C216S049000
Reexamination Certificate
active
06294314
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority benefit of Taiwan application Serial No. 87106062, filed Apr. 21, 1998, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of fabricating an opening, and more particularly to a method of fabricating an opening formed by deep ultra-violet photoresist (DUV PR).
2. Description of the Related Art
Deep ultra-violet photoresist is necessary for the semiconductor process with the size of 0.25 &mgr;m or less. It can be employed in, for example, oxide layer etching. The DUV PR is exposed under a deep ultra-violet light and developed to define the oxide layer. An opening for a contact, via or damascene is then formed by developing the DUV PR. DUV PR is used to reduce the width of the opening but the material of the DUV PR is soft and not high temperature compatible. Thus erosion and reflow of the DUV PR easily occurs while etching the oxide layer which requires high ion energy. Thus, the side profile of the DUV PR isn't entirely vertical and it is difficult to precisely control the width of the opening. A commonly employed method of preventing overetching of the DUV PR is to increase the thickness of the DUV PR. However, the increment of the thickness prevents the photoresist from being properly exposed and successfully developed, because of focus of depth. Therefore increasing the thickness of the DUV PR as described above doesn't solve the problem.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to overcome the problem of erosion and reflow of the DUV PR. The width of the opening can be reduced as much as possible to follow the trend towards smaller size. The quality of the opening width can also be controlled in a stable fashion.
To achieve these objects and advantages, and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention is directed towards a method of fabricating an opening with deep ultra-violet photoresist. An insulating layer is formed over a substrate where devices are formed thereon. A DUV PR layer with a first opening is then formed on the insulating layer. A hard mask layer is formed on the DUV PR layer and a second opening is next formed within the insulating layer by using the first opening to define the insulating layer. The hard mask is used to protect the DUV PR layer. The DUV PR layer and the hard mask are removed to expose the insulating layer and a desired second opening is thus formed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
REFERENCES:
patent: 4999280 (1991-03-01), Hiraoka
patent: 5041362 (1991-08-01), Douglas
patent: 5217851 (1993-06-01), Kishimura et al.
patent: 5487967 (1996-01-01), Hutton
patent: 5863707 (1999-01-01), Lin
patent: 5876903 (1999-03-01), Ng et al.
patent: 5895740 (1999-04-01), Chien et al.
patent: 61-151533 (1986-07-01), None
Christie Parker & Hale LLP
Duda Kathleen
United Silicon Incorporated
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