Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Removal of imaged layers
Reexamination Certificate
1999-08-13
2002-03-26
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Removal of imaged layers
C438S706000, C438S710000, C438S745000, C438S749000
Reexamination Certificate
active
06361929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of removing a photo-resist layer on a semiconductor wafer, and more particularly, to a method of removing a photo-resist layer in an environment without oxygen.
2. Description of the Prior Art
In the dual-damascene process of semiconductor, the metallic wire is formed within the inter-metal dielectrics (IMD) to connect the transistor and other devices on the semiconductor wafer. The formation of the metallic wire comprises forming a photo-resist layer on the IMD of the semiconductor wafer by using the photolithography process to define a recess or a contact hole. Then, the photo-resist layer is removed, and a metallic layer is formed in the recess or the contact hole to function as a metallic wire. The prior art method of removing the photo-resist layer destroys the profile of the recess or the contact hole and affects the subsequent process. Therefor, the method of removing the photo-resist layer must be improved in order to keep the quality of the dual-damascene process.
Please refer to FIG.
1
.
FIG. 1
is a schematic diagram of a prior art method of forming a contact hole
22
on a semiconductor wafer
10
. A prior art contact hole
22
is formed on an IMD
18
of a semiconductor wafer
10
. The IMD
18
comprises a barrier layer
12
, a dielectric layer with a low k (dielectric constant)
14
, and a cap layer
16
. The barrier layer
12
is made of SiN, SiON, or SiC, the dielectric layer with a low k
14
is made of fluorine-rich silicate glass, and the cap layer
16
is made of SiO, SiN, SiON or SiC. The dielectric constant (k) of the dielectric layer with a low k
14
is less than the dielectric constant of the barrier layer
12
and the cap layer
16
.
The prior art method of forming the contact hole
22
in the IMD
18
comprises coating a photo-resist layer on the IMD
18
, and performing a lithography and an etching processes to remove the IMD
18
whetein the IMD
18
not covered by the photo-resist layer is removed to a predetermined thickness. That means to remove the cap layer
16
, the dielectric layer with a low k
14
and the barrier layer
12
to form the contact hole
22
. Then, a cleaning process is performed to completely remove the photo-resist layer. The formation of the metallic wire by filling the contact hole
22
with metallic materials is then followed.
In the cleaning process according to the prior art, first a dry ashing process is performed by injecting oxygen as reactive gases of the plasma chemical reaction to remove most of the photo-resist layer. Next, organic or inorganic solution is utilized for damaging the structure of the photo-resist layer to completely remove the remaining photo-resist layer. During the dry ashing process, oxygen plasma reacts with the dielectric layer with a low k
14
to form a bowl-shape contact hole
22
, as shown in FIG.
1
. The metallic materials can not completely fill the bowl-shape contact hole
22
. Consequently, the metallic wire with voids insides is formed, which affect the electric performance of the semiconductor wafer
10
. Besides, the dielectric constant of the dielectric layer with a low k
14
will be changed by oxygen plasma, so that the insulation of electric signal of the IMD
18
will be reduced.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a method of removing a photoresist layer from a semiconductor wafer to solve the above mentioned problems.
In a preferred embodiment, the present invention relates to a method of removing a photo-resist layer from a semiconductor wafer, the semiconductor wafer comprising an inter-metal dielectric layer, and a photo-resist layer positioned on the inter-metal dielectric layer, the method comprising:
performing a dry cleaning process by injecting a nitrogen-containing gas into an oxygen-free environment and utilizing a plasma reaction to remove most of the photo-resist layer; and
performing a wet cleaning process to completely remove the photo-resist layer.
It is an advantage of the present invention that the cleaning process can avoid the contact hole being etched to form a blow-shape hole and the dielectric constant of the dielectric layer with a low k being changed.
These and other objective of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings.
REFERENCES:
patent: 5993916 (1999-11-01), Zhao et al.
patent: 6060397 (2000-05-01), Seamons et al.
Chen Tong-Yu
Chung Hsein-Ta
Hsu Yi-Yu
Yew Tri-Rung
Hsu Winston
Le Hoa Van
United Microelectronics Corp.
LandOfFree
Method of removing a photo-resist layer on a semiconductor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of removing a photo-resist layer on a semiconductor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of removing a photo-resist layer on a semiconductor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2876329