Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
1993-10-27
2001-09-18
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298150, C204S298230, C204S298250, C118S719000, C414S217000, C414S222010, C414S222070
Reexamination Certificate
active
06290824
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a system for forming a magnetic film in a magnetic field and more particularly to a magnetic film forming system having a plurality of process chambers, and transport mechanisms for transporting substrates from one process chamber to another.
2. Description of the Related Art
A conventional inline film forming system is described with reference to FIG.
9
. The inline film forming system in
FIG. 9
comprises a substrate inlet chamber
2
, three process chambers
1
a
,
1
b
, and
1
c
, and a substrate outlet chamber
3
which are linked in order. Sluice valves
8
a
,
8
b
,
8
c
, and
8
d
are disposed between each of the chambers. Each of the process chambers
1
a
,
1
b
, and
1
c
is provided with a device (not shown) for performing one process such as heating a substrate before film forming, sputtering film forming, ion beam sputtering film forming, or film forming by evaporation. A transport line
5
for transporting a substrate
101
is extended through the substrate inlet chamber
2
, process chambers
1
a
,
1
b
, and
1
c
, and substrate outlet chamber
3
.
The sequence for forming a film by using the system will be described. First, a substrate
101
on which a film is to be formed is fed into the inlet chamber
2
, which is then evacuated by evacuation installation
9
a
. The process chambers
1
a
,
1
b
, and
1
c
, and the outlet chamber
3
are evacuated by evacuation installations
9
b
,
9
b
,
9
d
, and
9
e
respectively. After the inlet chamber
2
is evacuated, the separation valve
8
a
is opened and the transport line
5
is operated to transport the substrate
101
to the process chamber
1
a
, which has been already evacuated. In the process chamber
1
a
, predetermined steps such as heating the substrate before film formation and film formation are performed by the processing device installed in the chamber. After the predetermined steps are performed, the separation valve
8
b
is opened and the substrate
101
is transported to the following process chamber
1
b
over the transport line
5
. Upon completion of processing the substrate
101
in the process chamber
1
b
, the substrate
101
is transported to the process chamber
1
c
for further processing. After predetermined processing in the process chamber
1
c
is complete, the substrate
101
is transported to the outlet chamber
3
from which it is removed. A large number of substrates
101
can be fed in sequence into the substrate inlet chamber
2
and through the process chambers
1
a
,
1
b
, and
1
c
one after another for processing.
In order, to form a film whose magnetic orientation is aligned, a film forming method in a magnetic field is used by which a film is formed while magnetic orientation of film particles is being aligned by applying a magnetic field. An example of the film forming system in the related art is given in “Journal of Vacuum Science & Technology A (Composition distribution and magnetic characteristics of sputtered Permalloy films with substrate angle)” second series volume 7, number 3, May/June 1989. This article describes a technique in which a permanent magnet is attached to a substrate holder which is fixed to a film forming system and a substrate is mounted on the substrate holder.
To form a magnetic film in a magnetic field by a conventional inline film forming system, magnetic field generation means is fixed outside or inside a process chamber and a magnetic field is applied to a space within the process chamber where a substrate is placed.
An example of a conventional inline system in which magnetic field generation means is attached outside a sputter film forming process chamber will be described with reference to FIG.
7
. As shown here, Helmholtz magnetic coils
4
a
,
4
b
,
4
c
, and
4
d
are disposed outside a process chamber
1
d
which is provided with a magnetic target
3
and an RF power supply
2
for applying voltage to the magnetic target
3
. The Helmholtz magnetic coils
4
a
,
4
b
,
4
c
, and
4
d
form a magnetic field
6
in a space where a substrate
101
is placed. The substrate
101
is supported by a transport line (not shown). Magnetic sputter particles sputtered from the magnetic target
3
are affected by the magnetic field
6
to form a film magnetically oriented on the substrate
101
.
An example of a conventional inline system in which magnetic field generation means is attached inside a sputter film forming process chamber will be described with reference to FIG.
8
. As shown here, permanent magnets
4
e
and
4
f
are disposed at places around a substrate
101
carried in a process chamber
1
e
. The permanent magnets
4
e
and
4
f
are supported by magnetic support means
7
fixed to the process chamber
1
e
. Since the permanent magnets
4
e
and
4
f
form a magnetic field
6
in a space where the substrate
101
is supported by a transport line (not shown), sputter particles sputtered from the magnetic target
3
are affected by the magnetic field
6
to form a film magnetically oriented on the substrate
101
.
However, a conventional film forming system having such magnetic field generation means suffers from the problem that when a substrate is taken out from the film forming system after a film has been formed, it is placed out of the magnetic field of the magnetic field generation means. Thus, if the substrate is taken out from the film forming system in the state in which it is not completely cooled after the film has been formed, the magnetic orientation of the film is not aligned, there by degrading the magnetic characteristic. To prevent this inconvenience, the substrate must be left in the film forming system until it is completely cooled after film formation. It takes time until the substrate is completely cooled, substantially lowering the throughput of the system.
Forming a magnetic multilayer film by using the conventional inline system having such magnetic field generation means, suffers from the following problems:
(1) To form a multilayer film, a number of film forming process chambers which differ in film forming source must each be provided with magnetic field generation means. At the time, it is very difficult to completely match the various directions of magnetic fields applied to substrates by the magnetic field generation means in the process chambers. This causes the orientation of the magnetic film to vary from one layer to another, degrading the magnetic characteristic of the magnetic film. There are two main reasons why the directions of the magnetic fields in the process chambers cannot be matched are as follows. First, to completely match the directions of the magnetic fields generated by the magnetic field generation means in the film forming process chambers, the directions of coils and magnets must be matched completely. However, it is technically very difficult to completely match the directions of coils and magnets which are separated from each other and adjustment of the directions requires that the system be stopped over a long period of time. Second, when a substrate is transported, the substrate turns and its direction will vary.
(2) When the magnetic field generation means is installed outside each film forming process chamber, a magnetic field must be generated within the process chamber, thus a large magnetic field generation means needs to be installed, there by increasing costs.
(3) Process chambers must be located apart from each other to prevent magnetic fields generated by magnetic field generation means in the contiguous process chambers from affecting each other to become uneven magnetic fields. Thus, the line in the system is longer as compared with a normal inline system having no magnetic field generation means, leading to inconvenient installation of the former system.
(4) When a substrate is transported to the contiguous film forming process chamber after film formation, it is temporarily placed out of the magnetic field. Thus, if it is transported to the next process chamber in the state
Arimatsu Keiji
Hagiya Takashi
Ishikawa Yasushi
Ohkawa Hiroo
Ueda Fumiomi
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
McDonald Rodney G.
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