Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2001-07-31
2003-08-26
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298090, C204S298150, C204S298330, C156S345520, C156S345530, C427S585000, C427S587000, C427S591000, C427S592000
Reexamination Certificate
active
06610180
ABSTRACT:
This application claims the priority of Japanese Patent Application No. 2000-233592 filed Aug. 1, 2000 in Japan, the entire contents of which are herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of Industry
The present invention pertains to a substrate processing device and processing method and, in particular, it relates to a substrate-processing device, employed in the field of semiconductors and magnetic films, in which substrates are continuously processed while being rotated in a highly purified atmosphere using a magnetic coupling-type rotation introduction mechanism.
2. Description of Related Art
In processes that involve the processing of substrates in a vacuum atmosphere, by way of example, in sputtering or the like, to increase film uniformity on the substrate surface, the film must be deposited while the substrate is being rotated. In addition, and in particular for the manufacture of film of a magnetic material in which the oxygen and carbon contained in the atmosphere must be removed as much as possible, the film must be deposited in a highly purified atmosphere.
In a substrate rotation introduction mechanism of the substrate processing device enables affords the deposition of a film of improved film-thickness uniformity in a highly purified atmosphere in this way, a can-seal type magnetic coupling-type rotation introduction mechanism—in which a rotating body is provided in a vacuum and another rotating body, separated from the rotating body thereof by a vacuum wall, is provided in the atmospheric side, and a magnetic coupling is effected therebetween to transmit the rotational movement from the atmospheric side—is employed. Because the can-seal type magnetic coupling-type rotation introduction mechanism is one in which rotational movement of an exterior rotating body is transmitted to an interior rotating body by way of magnetic coupling, without the employment of a rotating shaft that passes through the vacuum wall separating the vacuum and atmosphere, it is suitable for employment in substrate processing in an ultra-high vacuum and a highly purified atmosphere. A description is given, based on
FIG. 6
, of one example of a sputtering device in which a can-seal type magnetic coupling-type rotation introduction mechanism such as this is employed.
The device of
FIG. 6
is a sputtering device employed for the formation of a pin layer of a GME (Giant Magnetoresistive) structure used in magnetic heads and nonvolatile memory).
A substrate holder
5
, which holds a substrate
3
, and a sputtering target above this, but not shown in the diagram, is included within a vacuum chamber
1
. In addition, a magnet
212
, for imparting a magnetic field in a predetermined direction of the substrate during formation of the film, is attached to the circumference of the substrate holder
5
, and rotation is effected with the direction of the magnetic field and the predetermined direction of the substrate in alignment. The rotation of the substrate holder
5
and the magnet
212
is controlled by a can seal-type magnetic coupling-type rotation introduction mechanism.
The can seal-type magnetic coupling-type rotation introduction mechanism is separated into a vacuum part and an atmosphere part by a vacuum container
101
, and a rotating shaft
102
within the vacuum is supported by the vacuum container
101
by way of bearings
103
,
104
. A magnetic coupler
105
and an encoder magnetic ring
106
, for detection of the rotated position, are attached to the rotating shaft
102
. Meanwhile, a magnet
107
and yoke
108
are attached to the atmospheric side, and the atmospheric side magnet
107
and vacuum side magnetic coupler
105
are magnetically coupled whereby the rotational movement of the magnet
107
is transmitted to the rotating shaft
102
. The number of rotations and rotational angle of the rotating shaft
102
can be read by an encoder magnetic detector
109
provided on the atmospheric side.
First, exhaustion to 1.3 Pa is performed using a dry pump
231
by way of a regeneration valve
238
, after which the regeneration valve
238
is closed and a dry pump
236
is cold-driven to form a state in which ultra-high vacuum exhaust is possible. The vacuum chamber
1
is exhausted from atmospheric pressure using the dry pump
231
through a pull valve
237
and then, following the closure of the pull valve
237
, a main valve
235
is opened and exhaustion performed to 9.3×10
−7
Pa, which constitutes an ultra-high vacuum pressure, by the dry pump
236
.
Here, from an adjacent vacuum chamber not shown in the diagram, the substrate
3
is carried by a robot, through a slit valve
232
and, by the vertical motion of a lift pin
4
, is mounted on the substrate holder
5
.
The substrate
3
is rotated by the can-seal type magnetic coupling-type rotation introduction mechanism
2
together with the substrate holder
5
. At the stage at which the substrate has reached a predetermined rate of rotation, using a material that is spread from the sputtering target not shown in the diagram, a film is deposited on the substrate. In this way, using the rotation of the substrate, a substrate with improved film uniformity is deposited on the substrate surface. The operation is performed continuously and film is formed on a plurality of substrates.
However, a serious problem arises during the employment of a device such as that shown in
FIG. 6
in that, upon the continuous manufacture of a layered structure of a magnetic head NiMn and Cu film on a plurality of substrates, after several films have been manufactured, the desired magnetic characteristics of the film are not able to be obtained. During an examination of the various manufacturing conditions to ascertain the cause thereof, it was determined that the predetermined magnetic characteristics were able to be obtained if the film was formed following the lowering of the temperature of the substrate holder to room temperature by shutting down the device for an appropriate time. This is because the temperature of the substrate gradually increases when continuous manufacture of film is performed and, when the temperature rises, an alloy is formed at the interface of the NiMn layer and Cu layer and magnetic characteristics different to the designed value of a 2-layer structure are generated.
Thereupon, in order to investigate temperature history during continuous processing, a thermoelement was attached to the substrate and the substrate holder and the temperature shifts of the substrate holder and substrate, when 4 substrates were continuously processed, was measured. The results thereof are shown by the straight line and broken line, respectively, of FIG.
7
. Here, the horizontal axis represents the processing time and the vertical axis represents the temperature. It will be noted that the tests were performed with the substrate holder stationary. As is shown by
FIG. 7
, it is clear that, during processing from the 1
st
substrate to the 4
th
substrate, the temperature of the substrate holder gradually increased. In addition, although the temperature of the substrate was 20(C directly after being carried by the robot, it can be seen that changes occurred in the wake of changes in temperature of the substrate holder, and that the temperature during deposition of the 4
th
film, by comparison with the first, had risen.
It can be seen that, for this reason, there is a drawback in the continuous processing of a plurality of substrates using the device of the prior art in that sufficient time, which involves leaving and cooling the substrate holder to room temperature, must be taken for the processing of each substrate, wherein productivity is significantly lowered.
Another substrate rotating mechanism method that has been employed hitherto is shown in FIG.
8
. In this method, a direct-rotation drive shaft
401
passes through to the vacuum side from the atmospheric side, and vacuum sealing is performed using a magnetic fluid seal
402
. Although it is possible to cool the substrate holder by the provisi
Sakai Junro
Takahashi Nobuyuki
Anelva Corporation
Burns Doane , Swecker, Mathis LLP
McDonald Rodney G.
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