Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2002-11-12
2004-02-24
Chen, Jack (Department: 2813)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S250000, C438S396000
Reexamination Certificate
active
06696338
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for fabricating a capacitor of a semiconductor; and, more particularly, to a method for forming a ruthenium (Ru) storage node of a capacitor.
DESCRIPTION OF RELATED ART
The process of fabricating a capacitor in a semiconductor device with a linewidth no more than 0.1 &mgr;m adopts a metal-insulator-metal (MIM) structure. Here, many researches has been carried out on the method for forming a storage node, and ruthenium (Ru) is usually used as a material for a storage node.
When Ru is used for a storage node, there are such advantages that the capacity is increased and leakage current is reduced. In the formation of a storage node, a chemical vapor deposition (CVD) method is usually used. Therefore, a process window providing stable step coverage in a concave structure needs to be secured.
Referring to
FIGS. 1A and 1B
, which are cross-sectional views illustrating the conventional process for forming a Ru storage node of a semiconductor, a related-prior art is described herein.
First, as described in
FIG. 1A
, an oxide insulation layer
11
is formed on the substrate
10
that is already formed with various semiconductor constituents, and a plug
12
is formed thereon to penetrate the insulation layer
11
and contact the substrate
10
. The plug
12
contacts the impurity diffusion area (not shown) of the substrate
10
, which is source/drain, and includes a TiN barrier layer
12
A.
Subsequently, the upper surface of the insulation layer
11
is made planar by performing a chemical mechanical polishing (CMP) process. Then, a second insulation layer
13
is formed to a height of a storage node, and a concave part is formed to expose the surface of the barrier layer
12
A by etching the second insulation layer
13
selectively. Subsequently, a Ru layer
14
′ is formed along the profile of the second insulation layer
13
to form a storage node.
Subsequently, the concave part formed in the second insulation layer
13
is filled with a photoresist PR, as shown in FIG.
1
B.
Thereafter, a storage nodes
14
separated from neighboring storages node is formed by etching the Ru layer
14
′ without a mask. Subsequently, the remaining photoresist is removed by performing dry stripping, as shown in FIG.
1
C. That is, an etching process is applied to the Ru layer
14
′ and the photoresist with O
2
/CF
4
/H
2
O/N
2
or O
2
/N
2
, and then residual products and remaining photoresist are removed with solvent.
Subsequently, the substrate is thermally treated to recover the characteristics of the storage node
14
deteriorated during the above etching process, and then a short cleaning process is performed with buffered oxide etchant, prior to the formation of a dielectric layer for the purpose of removing the impurities.
Meanwhile, a series of process for forming a capacitor is completed by forming a dielectric layer and plate electrode on the storage node
14
, which are not illustrated in the drawings.
The conventional method for forming a capacitor storage node, as described above, has many disadvantages, which will be described hereinafter with reference to FIG.
2
.
In the conventional process described above, if dry stripping is performed with CF
4
gas to remove the remaining photoresist after the etching process to form the storage node
14
, the CF
4
gas penetrates to the storage node made of Ru, and damages the TiN barrier layer under the storage node.
In addition, due to the porous characteristic of a Ru layer, the photoresist still remains on the porous surface of the storage node. The remaining photoresist is not removed even in the subsequent cleaning process using solvent.
In the meantime, good storage node profile can be obtained from optimized gases, but this has a problem in reproducibility.
Besides CF
4
, O
2
gas also has these problems. As shown in
FIG. 2
, O
2
in the stripping gas is detected in the Ru storage node, too. Accordingly, it is hard to obtain stable characteristics of a storage node with the prior art.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for forming a stable ruthenium (Ru) storage node of a semiconductor device.
In accordance with an aspect of the present invention, there is provided a method for forming a Ru storage node of a semiconductor device, The method includes the steps of: a method for forming a ruthenium (Ru) storage node of a semiconductor device, comprising the steps of: etching an insulation layer on a substrate and forming openings; depositing a Ru layer along the profile of the insulation layer and the openings; filling a photoresist in the openings; performing an etching process until the insulation layer between neighboring openings is exposed and forming isolated Ru storage nodes with the Ru layer in the openings; and removing residual photoresist and polymers with a solution including H
2
SO
4
and H
2
O
2
.
The method of the present invention takes an advantage of the superior stability of Ru in acid environment to other metals, and removes residual polymers and photoresist remaining on the Ru storage node by performing cleaning with H
2
O
2
and H
2
SO
4
. At the same time, this method can protect the TiN barrier layer under the storage node from being damaged, and simplifies the process by incorporating the conventional three-step process into one step.
REFERENCES:
patent: 6130102 (2000-10-01), White, Jr. et al.
patent: 6211034 (2001-04-01), Visokay et al.
patent: 6274424 (2001-08-01), White, Jr. et al.
patent: 6274471 (2001-08-01), Huang
patent: 6436723 (2002-08-01), Tomita et al.
patent: 2003/0017686 (2003-01-01), Wada
Choi Geun-Min
Oh Kee-Joon
Chen Jack
Hynix / Semiconductor Inc.
Jacobson & Holman PLLC
LandOfFree
Method for forming ruthenium storage node of 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 for forming ruthenium storage node of semiconductor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for forming ruthenium storage node of semiconductor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3292745