Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-02-22
2001-06-26
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298250, C204S298260, C204S298310, C204S298350, C216S037000, C216S063000, C216S066000, C118S620000, C118S503000, C134S001000, C134S001100, C134S066000
Reexamination Certificate
active
06251232
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Referenced-applications
The present application claims the priority of Japanese Patent Application No. 11-84855, filed on Mar. 26, 1999, and Japanese Patent Application No. 11-332874, filed on Nov. 24, 1999, the subject matter of both Japanese applications being hereby incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Description of Related Art
The formation of a prescribed thin film on the surface of a substrate is carried out frequently in the production of semiconductor devices such as LSI, display apparatus such as liquid crystal displays and information-recording disks such as hard disks. Film deposition apparatus of this type are furnished with substrate holders of a prescribed construction for holding the substrates in the prescribed position within the film deposition chambers in which film deposition is carried out. The thin film should in fact be deposited only on the substrates, but particles which accumulate to form a thin film are inevitably deposited not only on the surface of the substrate, but also on the surface of the substrate holders. Consequently thin films inevitably accumulate on the surface of the substrate holders as well. The accumulation of a film on the substrate holder surface in this way causes problems such as a loss of processing quality to arise. This is described below using the film deposition apparatus which is used with substrates for information-recording disk purposes as an example.
A plan view which shows the outline construction of a conventional film deposition apparatus for information-recording disk substrates is shown in FIG.
10
. The apparatus shown in
FIG. 10
comprises a plurality of vacuum chambers
1
,
2
,
501
which are connected in an airtight manner along a transfer path
80
. Furthermore, substrate holders
90
which hold the substrates
9
and a transfer mechanism (which is not shown in the drawing) which moves the substrate holders
90
along the transfer path
80
are provided.
A front outline view which shows the construction of the substrate holder
90
which is shown in
FIG. 10
is shown in FIG.
11
. The substrate holder
90
includes a plate-like holder body
92
and holding claws
91
which are fined to the holder body
92
. The holding claws
91
are arranged in groups of three so as to hold a single substrate
9
. Each holding claw
91
comprises a metal plate spring which has been bent into an L-shape. The holder body
92
, as shown in
FIG. 11
, has two circular openings which are slightly larger than the substrates
9
. The holder body
92
has roughly L-shaped openings extending from the circular openings and each holding claw
91
is located in such an opening.
The holding claws
91
are fixed to the holder body
92
with screws, and the tips engage with the circumferential edge of the substrate
9
. The tips of the holding claws
91
are V-shaped. Thus, the edges of the substrates
9
are dropped onto and enter the V-shaped tips.
Of the three such holding claws
91
, the holding claw
91
which is located on the lower side is a movable holding claw. That is to say, there is provided a lever
93
which presses down this holding claw
91
against its elasticity. When mounting the substrate
9
on the substrate holder
90
, the holding claw
91
on the bottom side is pressed down by means of the lever
93
and the substrate
9
is located in the circular opening in the middle of the holder body
92
. Then, the lever
93
is released and the lower side holding claw
91
is returned to its original state by means of its elasticity. As a result the substrate
9
is engaged by the three holding claws
91
, and a state in which two substrates
9
are being held on a single substrate holder
90
is achieved. The same procedure, but in reverse, is used to recover the substrates
9
from the substrate holder
90
.
Moreover, as is clear from
FIG. 11
, the substrates
9
are held on the substrate holder
90
in a vertically mounted state. The surfaces of the substrates
9
which are held on the substrate holder
90
are therefore arranged facing toward the side of the transfer path
80
.
One of the plurality of vacuum chambers shown in
FIG. 10
is a load-lock chamber
1
in which the substrates
9
are mounted onto the substrate holders
90
, and another is an unload-lock chamber
2
in which the substrates
9
are recovered from the substrate holders
90
. Furthermore, one of the vacuum chambers
501
is a film deposition chamber in which the prescribed thin film is formed on the surfaces of the substrates
9
. Moreover, the other vacuum chambers
501
may be constructed as heating chambers in which the substrates
9
are preheated or they may be constructed as second film deposition chambers in those cases where multilayer films are being deposited.
Moreover, in the apparatus shown in
FIG. 10
, a return mechanism, not shown in the drawing, which returns the substrate holders
90
from which the substrates
9
have been recovered in the unload-lock chamber
2
to the load-lock chamber
1
is established. Hence, the substrate holders
90
are circulated through the plurality of vacuum chambers
1
,
2
,
501
and the return mechanism so that they can be used to hold substrates
9
repeatedly.
2. Field of the Invention
The inventions of this application concern film deposition apparatus in which prescribed thin films are deposited on the surface of a substrate, and more precisely it concerns the removal of the films which accumulate on the surfaces of the substrate holders which hold the substrates in apparatus of this type.
BRIEF SUMMARY OF THE INVENTION
In conventional film deposition apparatus as described above, the substrates
9
are transferred into the film deposition chamber
501
in a state where they are being held by a substrate holder
90
and a film is deposited on the surfaces of the substrates
9
. Consequently, a thin film is deposited not just on the surfaces of the substrates
9
but it also accumulates on the surface of the substrate holder
90
. This results in a problem as described below. The point is described here with reference to FIG.
12
.
FIG. 12
is an explanatory drawing of the problem which arises with the conventional apparatus.
The tip of a holding claw
91
and the circumferential edge of a substrate
9
which has been engaged in this tip is shown in FIG.
12
(
1
). First of all, as shown in FIG.
12
(
1
), a thin film
94
is accumulated not just on the surface of the substrate
9
, but also on the surface of the holding claw
91
. In more practical terms, the thin film
94
is accumulated extending from the holding claw
91
up to the circumferential edge of the substrate
9
. Hence, when the substrate
9
is recovered from the substrate holder
90
after film deposition, the situation is as shown in FIG.
12
(
2
) where the thin film
94
remains on the surface of the V-shaped tip of the holding claw
91
, except in the part where the substrate
9
had been located. The substrate holder
90
is used to hold substrates
9
repeatedly, as mentioned earlier, but when the next substrate
9
is mounted it is not held in exactly the same position as the earlier substrate. That is to say, the circumferential edge of the substrate
9
is inevitably mounted in the accumulated thin film
94
, as shown in
FIG. 12
(
3
).
At this time the thin film
94
is peeled off by the impact of mounting the substrate
9
, and the peeled off thin film
94
forms particles
95
of a certain size, which are dispersed. If the particles
95
become attached to the surface of the substrate
9
, then this results in a local film thickness abnormality. A local film thickness abnormality is likely to cause a sector failure in the cases of an information-recording disk such as a hard disk.
With the latest information-recording disks in particular, even the region of the surface of the substrate
9
close to the circumferential edge is now b
Aruga Yoshiki
Maeda Koji
Anelva Corporation
Burns Doane , Swecker, Mathis LLP
Nguyen Nam
VerSteeg Steven H.
LandOfFree
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