Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
2001-08-17
2003-07-15
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298070, C204S298140, C204S298150, C204S298250
Reexamination Certificate
active
06592729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to sputtering apparatuses used for forming metal thin films, piezoelectric thin films, dielectric thin films, and other thin films, and more specifically, the present invention relates to an in-line sputtering apparatus in which a thin film is formed while a substrate is being transferred in front of a plurality of targets.
2. Description of the Related Art
Conventionally, various kinds of sputtering apparatuses for forming various kinds of thin films such as metal thin films and piezoelectric thin films, have been proposed. Generally, the thicknesses of thin films formed by sputtering apparatuses must be uniform.
In Japanese Unexamined Patent Application Publication No. 9-125240, an example of a sputtering apparatus that controls the thickness of a thin film is disclosed.
FIG. 11
is a schematic diagram of a sputtering apparatus disclosed in the JP 9-125240, and
FIG. 12
is a schematic plan view for explaining a thickness distribution correcting member.
As shown in
FIG. 11
, a sputtering apparatus
101
includes a deposition chamber
102
, in which a substrate holder
103
is disposed. A substrate
104
is fixed on a surface of the substrate holder
103
.
A target
105
is arranged such that the target
105
opposes the substrate
104
, and a thickness distribution correcting member
106
is disposed above the target
105
.
As shown in
FIG. 12
by a plan view, the thickness distribution correcting member
106
includes a pair of supporting plates
106
a
and
106
b
which are fixedly disposed. The supporting plates
106
a
and
106
b
are arranged such that the supporting plates
106
a
and
106
b
oppose each other with the target
105
disposed therebetween and extend parallel to each other. In addition, the supporting plates
106
a
and
106
b
are linked with a plurality of correcting plates
106
c
and
106
d
, respectively. The correcting plates
106
c
and
106
d
are constructed to be movable in the direction shown by the arrow in the figure.
As shown in
FIG. 11
, in the sputtering apparatus
101
, target particles
105
a
are sputtered away from the target by ions A, move toward the substrate
104
, and are deposited on the exposed surface of the substrate
104
. Accordingly, a thin film is formed. In this case, thickness uniformity of the thin film formed on the substrate
104
depends on the flatness, attachment angles, and other characteristics of the substrate
104
and the target
105
. As a result, the thickness of the thin film may not be uniform. Thus, in order to ensure thickness uniformity of the thin film, the thickness distribution correcting member
106
is used in the sputtering apparatus
101
. In the thickness distribution correcting member
106
, the size of the opening B surrounded by the inner ends of the correcting plates
106
c
attached to the supporting plate
106
a
and the inner ends of the correcting plates
106
d
attached to the supporting plate
106
b
is adjusted so that the thickness distribution of the thin film can be corrected. More specifically, when some of the correcting plates
106
c
and
106
d
are moved to reduce the gaps therebetween, the movement of the target particles
105
a
toward the substrate
104
is impeded, and the thickness of the corresponding portion of the thin film is reduced.
In the sputtering apparatus
101
, when positions of the correcting plates
106
c
and
106
d
of the thickness distribution correcting member
106
are to be adjusted, the deposition chamber
102
is first vented to the atmosphere. Then, correcting plates
106
c
and
106
d
are moved and are fixed at desired positions, such that the gaps therebetween are adjusted, and the pressure in the deposition chamber
102
is reduced again.
On the other hand, an in-line sputtering apparatus including a thickness controlling plate is disclosed in Japanese Unexamined Utility Model Application Publication No. 62-162255. As shown in
FIG. 13
, according to JP 62-162255, a sputtering apparatus
111
includes a deposition chamber
112
, in which a substrate holder
113
is disposed. A substrate
114
is fixed on the substrate holder
113
. Targets
116
are disposed on an inwardly facing surface of a covering member
115
, which is provided for covering the deposition chamber
112
. The substrate
114
is moved along with the substrate holder
113
in the direction shown by the arrow C in the figure, so that, while the substrate
114
is being transferred in front of the targets
116
, target particles continuously accumulate on the substrate
114
to form a thin film.
The sputtering apparatus
111
is provided with a thickness controlling member
117
, which is schematically shown in FIG.
13
. The actual shape of the thickness controlling member
117
as seen from the front is shown in FIG.
14
. The thickness controlling member
117
includes a supporting plate
118
having a rectangular shape which is provided with a rectangular opening. Correcting plates
119
and
120
constructed of metal are fixed to the supporting plate
118
at two sides thereof so as to oppose each other in the lateral direction. Inner edges
119
a
and
120
a
of the correcting plates
119
and
120
oppose each other, and the shapes thereof are determined in accordance with the correction of the thickness distribution of the thin film. The shapes of the inner edges
119
a
and
120
a
of the correcting plates
119
and
120
, respectively, are adjusted by cutting metal plates, and vary along the vertical direction as shown in the figure. When the substrate
114
is transferred in the direction shown by the arrow C (FIG.
13
), the movement of the target particles knocked away from the target
116
is impeded by the correcting plates
119
and
120
. Accordingly, the thickness distribution is corrected such that the thickness of the thin film is reduced at portions where the gap between the inward edges
119
a
and
120
a
is narrow, and is increased at portions where the gap therebetween is wide.
As described above, according to the sputtering apparatus shown in
FIGS. 11 and 12
, which is disclosed in Japanese Unexamined Patent Application Publication No. 9-125240, the thickness distribution is corrected by adjusting the widths of the gaps between the correcting plates
106
c
and
106
d
. However, there is a problem in that the relationship between the change of the sizes of the gaps and the change of the thickness distribution of the thin film formed is not reliable, and it is difficult to control the thickness distribution of the thin film with high accuracy.
In a sputtering process, an erosion region of the target is sputtered, and target particles are knocked away from the target and accumulated on a substrate so that a thin film is formed. The thickness of the thin film formed on the substrate varies depending on the coverage of the erosion region of the target by the correcting plates
106
c
and
106
d
. In the above-described conventional technique, although the gaps between the correcting plates
106
c
and
106
d
are adjusted, the coverage of the erosion region of the target is not determined.
Thus, as schematically shown in
FIGS. 15A and 15B
, the correcting plates
106
c
and
106
d
cover the erosion region of the target
105
asymmetrically. Accordingly, although the thickness of the thin film may be reduced by reducing the gaps between the correcting plates
106
c
and
106
d
, a reliable relationship between the displacements of the correcting plates
106
c
and
106
d
and the thickness variation of the thin film cannot be obtained. Thus, in order to make the thickness uniform, processes of adjusting the positions of the correcting plates
106
c
and
106
d
and measuring the thickness distribution of the formed thin film must be performed several times.
Thus, in the method according to the above-described conventional technique, only the gaps between the correcting plates
106
c
and
106
d
are adjusted, and the correcting plates
106
c
and
106
d
are not moved
Funato Ken
Kadota Michio
Shimoda Kazunori
Takata Eiichi
Keating & Bennett LLP
McDonald Rodney G.
Murata Manufacturing Co. Ltd.
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