Disk carrier

Details Disk carrier Disk carrier

2001-03-17

2003-03-04

VerSteeg, Steven H. (Department: 1753)

Coating processes

Miscellaneous

C204S298150, C204S192100, C118S500000, C269S015000, C269S037000, C269S047000, C269S050000, C269S055000

Reexamination Certificate

active

06528124

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention pertains to structures for holding disks during sputtering. This invention also pertains to methods and apparatuses for manufacturing magnetic disks.
Magnetic disks are typically manufactured by sputtering an underlayer, a magnetic alloy film and a protective overcoat, in that order, on a disk-shaped substrate. An example of such a process is described in U.S. patent application Ser. No. 08/984,753, filed by Bertero et al. on Dec. 4, 1997 (now U.S. Pat. No. 6,150,015, issued Nov. 21, 2000), incorporated herein by reference.
During sputtering, the following steps are typically performed:
1. A disk-shaped substrate is placed in a “disk carrier”. (The substrate can be glass, glass ceramic, aluminum plated with a nickel-phosphorus alloy, or other appropriate material. The nickel-phosphorus alloy is sometimes referred to as “NiP”.)
2. In some (but not all) manufacturing processes, the disk carrier carries the substrate past a heating element for heating the substrate.
3. The disk carrier carries the substrate through sputtering apparatus, past several sets of sputtering targets.
4. The substrates are then removed from the disk carrier.
Various types of disk carriers are known in the art. For examples of disk carriers used during low temperature sputtering processes see U.S. Pat. Nos. 5,244,555; 5,296,118; and 4,595,481, each assigned to Komag, Inc. and incorporated herein by reference. These disk carriers include a vertical plate with a substantially circular opening for receiving a disk-shaped substrate. A groove is provided in the bottom of the circular opening for receiving and holding the outer edge of the substrate. During low temperature sputtering processes, the substrate is placed within the carrier and carried past a set of sputtering targets. The substrate is typically not carried past a heating element prior to sputtering. Therefore, the carrier need not accommodate much thermal expansion of the substrate relative to the carrier.
U.S. patent application Ser. No. 09/428,301, filed Oct. 27, 1999 abandoned and assigned to Komag, Inc., teaches and claims several types of disk carriers used in a high temperature sputtering process. (The '301 application, which is now abandoned, is incorporated herein by reference.) The '301 carriers also include a vertical plate with a circular opening for receiving a substrate. For example, in '301
FIGS. 2A
to
2
E (
FIGS. 1A
to
1
E of the present application), the '301 application shows an embodiment of a disk carrier
100
comprising a vertical plate
102
having a substantially circular opening
104
for receiving a disk-shaped substrate
106
. During a high temperature sputtering process, carrier
100
carries substrate
106
past a heating element prior to sputtering. Because substrate
106
has a much lower thermal mass than carrier
100
, the temperature of substrate
106
can exceed the temperature of carrier
100
by 200° C. or more. Accordingly, carrier
100
has the following characteristics.
1. Opening
104
has a size and shape such that it can hold substrate
106
when substrate
106
and carrier
100
are both at room temperature.
2. Opening
104
can hold substrate
106
when substrate
106
is at an elevated temperature with respect to carrier
100
without having carrier
100
pressing against substrate
106
so as to cause substrate
106
to bend or bow.
Substrate
106
is disk-shaped and has a diameter of 95.025 mm (e.g. a radius of about 47.513 mm) at room temperature, a thickness of 0.80 mm at room temperature, a diameter of 95.572 mm at 300° C. and a thickness of 0.890 at 300° C. Substrate
106
has a central aperture
107
formed therein. Substrate
106
typically comprises an aluminum alloy plated with a NiP.
Opening
104
of carrier
100
comprises an upper circular portion
104
u
and a lower circular portion
104
l
. Upper circular portion
104
u
has a radius R
1
equal to about 48.82 mm about a center C. (Radius R
1
is greater than the room temperature substrate radius.)
Lower portion
104
l
of opening
104
extends about an arc of approximately 176°. Within lower circular portion
104
l
is a groove
108
(
FIGS. 1C
to
1
E) for receiving an outer edge
106
a
of substrate
106
. Groove
108
extends continuously along the length of circular portion
104
l
. Groove
108
includes side walls
108
a
,
108
b
(
FIG. 1E
) which form an angle &agr;l of about 100° and a floor
108
c
having a width W
1
of about 0.25 mm. The distance D
1
(
FIG. 1A
) between the center C of opening
104
and the top
108
t
of groove
108
is typically between 47.424 and 47.454 mm (i.e. less than the substrate radius). The distance between the center C of opening
104
and floor
108
c
of groove
108
is typically between 47.907 and 47.937 mm (i.e. greater than the substrate radius). Groove
108
terminates when it reaches points
109
a
,
109
b
(FIG.
1
A). Points
109
a
,
109
b
are about 2° below the horizontal diameter of opening
104
.
At room temperature substrate
106
has a radius of 47.513 mm and a thickness of 0.800 mm. Thus, when substrate
106
is at room temperature and rests in groove
108
, edge
106
a
of substrate
106
is a distance D
2
of about 0.12 mm from floor
108
c
of groove
108
(FIG.
1
E′). At a substrate temperature of 300° C., edge
106
a
is about 0.16 mm from floor
108
c
. Substrate
106
is adequately supported by groove
108
when substrate
106
is at room temperature (about 20° C.). However, because the radius of floor
108
c
of groove
108
is greater than the substrate radius at room temperature, carrier
100
can accommodate thermal expansion of substrate
106
without causing substrate
106
to bow outwardly. During some high temperature processes, substrate
106
is heated to a temperature of about 200° C. before sputtering.
Above points
109
a
,
109
b
, groove
108
terminates, and a recess
112
having a depth D
4
of about 6.35 mm (
FIG. 1D
) is formed in a side
114
of carrier
100
. (Carrier
100
has a width D
5
of about 11 mm.) The walls of recess
112
include first and second portions
112
a
,
112
b
(
FIG. 1A
) which extend in a linear direction, and a third, curved portion
112
c
. Recess
112
permits loading and removal of substrate
106
from side
114
of carrier
100
. (However, it is not feasible to load substrate
106
from the other side
117
of carrier
100
.) Curved portion
112
c
of the wall of recess
112
is circular, and has a radius R
2
of about 53.80 mm from a point C′ that is a distance D
3
about 4.44 mm above center point C. Linear walls
112
a
and
112
b
are a distance D
4
of about 52.10 mm from point C′.
A bevel
116
is formed on side
114
of carrier
100
to facilitate exposure of substrate
106
to plasma during sputtering. Similarly, a bevel
118
is formed on side
117
of carrier
100
, also to facilitate exposure of plasma to substrate
106
during sputtering. Bevels
116
and
118
form an angle &ggr;
1
of 26° (
FIG. 1E
) with the side of carrier
100
. Bevels
116
and
118
are circular, with a radius R
3
of about 57.16 mm from center C (FIG.
1
A).
FIG. 1C
is an expanded view of a portion P
1
of
FIG. 1A
where groove
108
terminates. As can be seen, below wall
112
a
, a wall
112
d
that curves downward and to the right toward opening
104
bounds recess
112
. The radius of curvature R
4
of wall
112
is about 4 mm.
The '301 application teaches and claims several other types of substrate carriers, e.g. as shown in '301
FIGS. 3A
to
3
C and
4
A to
4
D. The embodiment of '301
FIGS. 3A
to
3
C permits a substrate to be loaded and unloaded from either side of the disk carrier. The embodiment of '301
FIGS. 4A
to
4
D has a groove that is shallower at the lowest point of the opening (e.g. near point
109
c
) than away from the lowest point of the opening (e.g. near points
109
a
,
109
b
). This makes it easier for the carrier to hold the substrate when the substrate is at room temperature without having the substr

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