Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2002-01-28
2004-08-17
VerSteeg, Steven (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298080
Reexamination Certificate
active
06776879
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a backing plate and a sputtering method for fixing and cooling a target for sputtering which is used for a sputtering apparatus.
More particularly, the invention relates to a backing plate and a sputtering method, which are used for a sputtering apparatus in which a substrate having a large size of some hundreds of millimeters to 1 meter or more is coated with a thin film in a state that a substrate is not moved with respect to a target
2. Description of the Related Art
The sputtering apparatus is used to form a thin film on a surface of a substrate in steps of manufacturing semiconductor devices, electronic parts, liquid crystal panels and the like. More particularly, in liquid crystal panels and solar cell panels, a rectangular substrate to be formed with a thin film having a size of some hundreds of millimeters to 1 m or more is usually used.
The sputtering apparatus includes a film deposition chamber in which a substrate to be coated with a thin film and a base material of the thin film as a target are placed so as to be opposite to each other. The target is bonded to a backing plate. By applying a negative potential to the target by the backing plate, plasma is generated. Then, ions in plasma impinge onto the target, thereby sputtering particles are dispersed from the target. The sputtering particles emitted from the target are adhered to and deposited on the surface of the substrate. Finally, a thin film is formed on the substrate. Further, when ions in plasma collide with the target, the surface of the target is heated.
FIG. 6A
is a plan view showing a conventional backing plate
104
.
FIG. 6B
is a cross sectional view taken along the cross section line S
5
—S
5
in FIG.
6
A. The backing plate
104
is made of a metal such as copper or the like which is easily obtained and processed. Further, the backing plate
104
is formed so as to be mounted on the sputtering apparatus not shown in figure. The backing plate
104
provides the target
103
with a negative potential and also provided with a cooling means to prevent temperature increase.
When using the target
103
which is an inexpensive and easily processed material, it is possible to process the target
103
itself into the shape capable of being mounted on the sputtering apparatus. Further, it is possible to provide the cooling means for reducing excessive temperature increase due to collision of ions in plasma. However, in general, a thin-film material used for sputtering is required to be high purity, and the material is often expensive, for example, a ceramic which undergoes sintering, or has low heat-transfer. Accordingly, the target
103
in the actual use is formed in a simple planar shape. In addition to this, there are some cases that the target
103
has a circle figure, an oval figure, a rectangular figure, and small plates are combined with each other in a shape of tile so as to form the above mentioned figure.
The target
103
is bonded to the backing plate
104
by soldering (not shown) at the melting point of about 150° C. The backing plate
104
cools the target
103
by use of the cooling means to prevent excessive temperature increase of the target
103
and to prevent the target
103
from being peeled out from the backing plate
104
because the soldering is melted. Further, when the temperature of the target
103
excessively rises, in the extreme, the surface of the target
103
is melted or an arc discharge is generated due to the emission of thermal electrons from the heated portion, which causes local melting on the surface of the target
103
. Because of this, cluster in a splay form, so-called “splash” is adhered on the substrate to be formed with a thin film, which becomes a factor that deteriorates the production yield in the sputtering step. Further, in consideration of the difference between the backing plate
104
and the target
103
in thermal expansion, the backing plate
104
can reduce thermal stress distortion when the target
103
is bonded to the backing plate
104
.
The backing plate
104
is composed of two planar members
106
a
and
106
b
which are laminated each other in the direction of thickness. In the planar member
106
a
, one of the two planar members, continuous grooves in a stripe shape
107
are formed open to an opposed surface to the target bonding surface, and the planar member
106
b
, the other of the two planar members, is mated thereto to cover the grooves
107
. According to this, the grooves
107
become a cooling water flow passage
105
in which cooling water flows. The cooling water flow passage
105
is provided with a cooling water inlet
108
and a cooling water exit
109
and has a configuration capable of circulation of the cooling water flown from the outside. By the circulation of the cooling water, not only the backing plate
104
but also the target
103
bonded to the backing plate
104
is cooled. For example, Japanese Unexamined Patent Publication JP-A 6-172988 (1994) discloses an example of the conventional backing plate
104
.
FIG. 7A
is a plan view showing another conventional backing plate
110
.
FIG. 7B
is a cross sectional view taken along the cross section line S
6
—S
6
in FIG.
7
A. In the backing plate
110
, several through holes
113
which penetrate the planar member
111
are bored in a lattice shape from a side surface of the planar member
111
by using a gun drill or the like. To compose the predetermined cooling water flow passage
105
, the through holes
113
are covered with cap materials
112
, and then the cap materials
112
and the planar member
111
are welded with a silver solder or the like.
FIG. 8
is a plan view showing still another conventional backing plate
115
. The backing plate
115
has several cooling water flow passages
105
so as to be suitable for a large rectangular substrate
102
a
. Since the configuration of the backing plate
115
is much the same as the expansion of the backing plate
104
as shown in
FIGS. 6A-6B
, the same reference numerals are used ands detailed description will be omitted.
FIG. 9A
is a perspective view showing another conventional backing plate
161
.
FIG. 9B
is a bottom view of the backing plate
161
as shown in FIG.
9
A. The backing plate
161
is composed of a base part
162
where a target
103
is bonded to the surface and a planar cooling part
163
having a cooling medium flow passage
166
at the inside. Further, the base part
162
and the cooling part
163
are made of aluminum. The cooling part
163
is integrally lined to the surface opposite to the target bonding surface of the base part
162
by welding (welding parts W
1
, W
2
). The cooling part
163
is composed of a roll bond panel
164
to be formed with a swelled tube part
165
on the entire surface, so that manufacturing process can be simplified. Such a conventional backing plate
161
is disclosed in Japanese Unexamined Patent Publication JP-A 2000-73164 (2000).
These disclosed techniques can obtain effects which conform respective object. However, when forming a large substrate such as a liquid crystal panel, a solar cell, and the like, there arises a problem described below in order to form a film at high speed in a state where the substrate and the target relatively remain at rest, and to control uniformity of film thickness and film quality of a thin film to be formed on a substrate to a desired range.
In general, the sputtering is carried out by using a target which is somewhat larger than a substrate to form a thin film having even film thickness and film quality on a substrate. Although the size of the target is determined depending upon the distance between the target and the substrate, it is generally determined based on the size about 1.1 times to 1.5 times as large as one side of the substrate as a guide. Further, recently, the size of the substrate to be formed has a side of about 1 m. As the size of the substrate becomes larger, target also becomes larger proportional to the size of
Tadera Takamitsu
Yamamoto Tatsushi
Conlin, Esq. David G.
Roos, Esq. Richard J.
Sharp Kabushiki Kaisha
VerSteeg Steven
LandOfFree
Backing plate used for sputtering apparatus and sputtering... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Backing plate used for sputtering apparatus and sputtering..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Backing plate used for sputtering apparatus and sputtering... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3341301