U.S. patent application number 13/338182 was filed with the patent office on 2012-04-19 for system and method for commercial fabrication of patterned media.
This patent application is currently assigned to INTEVAC, INC.. Invention is credited to Michael S. Barnes, Terry Bluck, Kevin P. Fairbairn, Ralph Kerns, Charles Liu, Ren Xu.
Application Number | 20120090992 13/338182 |
Document ID | / |
Family ID | 40718210 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120090992 |
Kind Code |
A1 |
Fairbairn; Kevin P. ; et
al. |
April 19, 2012 |
SYSTEM AND METHOD FOR COMMERCIAL FABRICATION OF PATTERNED MEDIA
Abstract
A system is provided for etching patterned media disks for hard
drive. The modular system may be tailored to perform specific
processes sequences so that a patterned media disk is fabricated
without removing the disk from vacuum environment. In some sequence
the magnetic stack is etched while in other the etch is performed
prior to forming the magnetic stack. In a further sequence ion
implantation is used without etching steps. For etching a movable
non-contact electrode is utilized to perform sputter etch. The
cathode moves to near contact distance to, but not contacting, the
substrate so as to couple RF energy to the disk. The substrate is
held vertically in a carrier and both sides are etched serially.
That is, one side is etched in one chamber and then in the next
chamber the second side is etched.
Inventors: |
Fairbairn; Kevin P.; (Los
Gatos, CA) ; Barnes; Michael S.; (San Ramon, CA)
; Bluck; Terry; (Santa Clara, CA) ; Xu; Ren;
(San Jose, CA) ; Liu; Charles; (Los Altos, CA)
; Kerns; Ralph; (San Carlos, CA) |
Assignee: |
INTEVAC, INC.
Santa Clara
CA
|
Family ID: |
40718210 |
Appl. No.: |
13/338182 |
Filed: |
December 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12329462 |
Dec 5, 2008 |
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13338182 |
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61052131 |
May 9, 2008 |
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60992972 |
Dec 6, 2007 |
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Current U.S.
Class: |
204/298.25 |
Current CPC
Class: |
G11B 5/855 20130101;
G11B 5/84 20130101; H01J 37/3438 20130101 |
Class at
Publication: |
204/298.25 |
International
Class: |
C23C 14/34 20060101
C23C014/34 |
Claims
1. A system for fabricating patterned media disks, comprising: a
plurality of processing chambers, each having an independent vacuum
environment; a plurality of valves, each positioned between two
processing chambers; a transport system for transporting a disk
carrier from one chamber to directly the next through the valves;
wherein the plurality of processing chambers comprises: at least
one etching chamber; at least one refill sputtering chamber; and,
at least one etch back chamber.
2. The system of claim 1, further comprising a cooling chamber
positioned following the etch chamber.
3. The system of claim 1, wherein the etch chamber comprises: a
main chamber body having a first side and a second side opposite
the first side; a precursor gas delivery assembly coupled to the
first side; a movable cathode assembly coupled to the second
side.
4. The system of claim 3, wherein the movable cathode assumes a
retractable position during disk transport and assumes an extended
position during etch process.
5. The system of claim 3, wherein the transport system comprises
tracks positioned within the main chamber body and configured for
supporting the disk carrier, such that a disk held by the disk
carrier is positioned between the precursor gas delivery assembly
and the movable cathode assembly.
6. The system of claim 5, wherein the tracks are positioned such
that during etching the movable cathode assembly is moved close to
the disk, but does not touch it.
7. The system of claim 6, wherein the tracks are configured to
transport a disk carrier such that the disk is held in a vertical
orientation during transport and during processing.
8. The system of claim 1, wherein the plurality of processing
chambers comprise at least a first and a second etch chambers,
wherein: the first etch chamber comprises: a first main chamber
body having a first side and a second side opposite the first side;
a first precursor gas delivery assembly coupled to the first side;
a first movable cathode assembly coupled to the second side; and,
the second etch chamber follows the first etch chamber and
comprises: a second main chamber body having a third side and a
fourth side, the third side being opposite the second side and the
fourth side being opposite the first side; a second precursor gas
delivery assembly coupled to the fourth side; a second movable
cathode assembly coupled on the third side.
9. The system of claim 8, wherein the transport system is
configured to transport the disk carrier such that the disk is held
in a vertical orientation during transport and during processing,
wherein one surface of the disk is etched in the first etch chamber
and the opposite surface of the disk is etched in the second etch
chamber.
10. The system of claim 9, further comprising a cooling chamber
positioned between the first and the second etch chambers.
11. The system of claim 10, further comprising a second cooling
chamber positioned after the second etch chamber.
12. The system of claim 9, further comprising a cooling chamber
positioned after the second etch chambers.
13. The system of claim 1, further comprising a hard mask
sputtering chamber.
14. The system of claim 1, further comprising a hard mask etching
chamber.
15. The system of claim 1, further comprising at least one cooling
chamber.
16. The system of claim 1, wherein the etching chamber is
configured for magnetic layer etching to thereby form patterned
magnetic layer, the refill sputtering chamber is configured for
depositing carbon refill layer to fill the patterned magnetic
layer, and the etch back chamber is configured for etching back the
carbon refill layer to form a relatively flat top surface.
17. The system of claim 1, further comprising a sputtering chamber
configured for forming a hard protective layer over the flat top
surface.
18. The system of claim 17, wherein the sputtering chamber is
configured for forming a hard protective layer by depositing a
carbon overcoat.
19. The system of claim 16, further comprising a hard mask etching
chamber positioned ahead of the etching chamber and configured for
etching a hard mask.
20. The system of claim 19, further comprising a resist trim
chamber positioned ahead of the hard mask etching chamber.
Description
RELATED APPLICATIONS
[0001] This is a Divisional Application of U.S. patent application
Ser. No. 11/375,019, which claims priority from U.S. Provisional
Application Ser. No. 61/052,131, filed May 9, 2008, and from U.S.
Provisional Application Ser. No. 60/992,972, filed Dec. 6, 2007,
the disclosure of both of which is incorporated herein in its
entirety.
[0002] This application also relates to U.S. application Ser. No.
12/329,447, and U.S. application Ser. No. 12/329,457, both filed on
Dec. 5, 2008.
BACKGROUND
[0003] 1. Filed of the Invention
[0004] This invention relates to the art of substrates, e.g., disk,
micro-fabrication and, more particularly, to patterning of
substrates, e.g., the magnetic layers of a hard disk for hard disk
drives.
[0005] 2. Related Arts
[0006] Micro-fabrication of substrates is a well know art employed
in, for example, fabrication of semiconductors, flat panel
displays, light emitting diodes (LED's), hard disks for hard disk
drives (HDD), etc. As is well known, fabrication of semiconductors,
flat panel displays and LED's involves various steps for patterning
the substrate. On the other hand, traditional fabrication of hard
disks, generally referred to as longitudinal recording technology,
does not involve patterning. Similarly, fabrication of disks for
perpendicular recording technology does not involve patterning.
Rather uniform layers are deposited and memory cells are generally
defined by the alternating change of magnetic flux induced by the
recording head, with each recording bit encompassing multiple
grains within the un-patterned magnetic layers.
[0007] It has been demonstrated that non-patterned disks would fail
to satisfy the needs of the market, in terms of area bit density
and costs, in order to remain competitive with other forms of
storage. Consequently, it has been proposed that next generation
disks should be patterned. It is envisioned that the patterning
process may utilize photolithography, although currently there is
no certainty which lithography technology may be commercialized,
and no commercial system is yet available for commercial
manufacturing of patterned media. Among contenders for
photolithography are interference photolithography, near field
lithography and nano-imprint lithography (NIL). Regardless of the
lithography technology utilized, once the photoresist is exposed
and developed, the disk needs to be etched and fabricated according
to the desired pattern. However, to date much of the development
efforts has been focused on the patterning step and no technology
has been proposed for fabricating a patterned disk in a
commercially viable environment.
[0008] To be sure, etch, sputtering, and other fabrication
technologies are well known and well developed for semiconductor,
flat panel display, LED's, etc. However, no system has been
proposed for integrating these technology to enable fabrication of
disks for HDD. Moreover, unlike HDD disks, in all of these
applications only one side of the substrate needs to be
etched--allowing a chuck to hold the substrate from the backside
during fabrication. On the other hand, HDD disks need to be
fabricated on both sides, preventing the use of a chuck. Indeed, in
HDD disk fabrication no part of the fabrication system may contact
any surface of the disk. Also, while HDD manufactures expect the
system to have a throughput on the order of 1000 disks per hour,
fabricators of semiconductors employ systems having throughputs of
only tens of substrates per hour.
[0009] In view of the above, a method and system are required to
enable fabrication of hard disks to provide patterned media for
HDD.
SUMMARY
[0010] The following summary is included in order to provide a
basic understanding of some aspects and features of the invention.
This summary is not an extensive overview of the invention and as
such it is not intended to particularly identify key or critical
elements of the invention or to delineate the scope of the
invention. Its sole purpose is to present some concepts of the
invention in a simplified form as a prelude to the more detailed
description that is presented below.
[0011] Methods and systems are provided for integrated fabrication
of disks to be used in HDD in a commercially viable manner. Various
processing steps are outlined and their sequence is designed to
result in a functional patterned media disk. The system may be
constructed by modifying a commercial processing system, such as
the 200 Lean.RTM. available from Intevac, of Santa Clara,
Calif.
[0012] As noted above, the fabrication of patterned media requires,
among others, incorporating etching technology to the disk
fabrication. In considering the application of plasma etching
technology to hard disks, the subject inventors have recognized
that standard plasma etching technology is problematic for etching
patterned hard disks. Unlike semiconductors and other applications,
the disks need to be etched on both sides. Therefore, conventional
systems having plasma etch on only one side are not workable for
hard disks. Also, since both sides of the disks are fabricated, no
element of the fabrication machine can be allowed to touch either
surface of the disk. Therefore, prior art systems utilizing
conventional chucks cannot be used for processing hard disks, as
they touch the backside. This raises another problem in that, if no
chuck can be used to hold the disk, how can a bias potential be
applied to cause species of the plasma to impinge on the surface of
the disk?
[0013] The subject inventors have provided solutions to the above
problems and developed a patterned media fabrication system that is
commercially viable. The fabrication system includes an etching
system and method that enable etching of both sides of the disks,
without touching any surface of the disk. Embodiments of the
invention also enable applying bias potential to cause the plasma
species to impinge the surface of the disk without attaching the
disk to a chuck.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings, which are incorporated in and
constitute a part of this specification, exemplify the embodiments
of the present invention and, together with the description, serve
to explain and illustrate principles of the invention. The drawings
are intended to illustrate major features of the exemplary
embodiments in a diagrammatic manner. The drawings are not intended
to depict every feature of actual embodiments nor relative
dimensions of the depicted elements, and are not drawn to
scale.
[0015] FIG. 1 illustrates a flow chart of a complete process for
fabricating HDD patterned media disks according to one generic
embodiment of the invention.
[0016] FIG. 2 illustrates a cross section of a patterned media
undergoing a general process flow according to one generic
embodiment of the invention.
[0017] FIG. 3 illustrates an example of a patterning system
according to an embodiment of the invention.
[0018] FIG. 4 illustrates another process for fabricating a
patterned media disk according to an embodiment of the
invention.
[0019] FIG. 5 illustrates a general architecture of a system
tailored for executing the process of FIG. 4.
[0020] FIG. 6 illustrates another process for fabricating a
patterned media disk, according to an embodiment of the
invention.
[0021] FIG. 7 illustrates a general architecture of a system
tailored for executing the process of FIG. 6.
[0022] FIG. 8 illustrates part of a system for fabricating a
patterned hard disk according to an embodiment of the
invention.
[0023] FIG. 9 illustrates a cross section along lines A-A in FIG.
8.
[0024] FIG. 10 illustrates a cross section along lines B-B in FIG.
8.
[0025] FIG. 11A is a partial isometric view shown the movable
cathode in a position away from the disk, while
[0026] FIG. 11B is a partial isometric view showing the movable
cathode in a position proximate the disk.
[0027] FIG. 12 illustrates a disk etch chamber according to an
embodiment of the invention.
[0028] FIG. 13 illustrates an embodiment of a system having
alternating etch chambers and cooling stations.
[0029] FIG. 14 illustrate a flow of a process according to an
embodiment of the invention.
[0030] FIG. 15 illustrates an alternative embodiment of the system
according to the invention.
[0031] FIG. 16 illustrates certain alternative features according
to embodiments of the invention.
[0032] FIG. 17 is a flow chart illustrating an etch process
according to an embodiment of the invention.
[0033] FIG. 18 illustrates another process for fabricating a
patterned media disk according to an embodiment of the
invention.
[0034] FIG. 19 illustrates a general architecture of a system
tailored for executing the process of FIG. 18.
[0035] FIG. 20 illustrates an example for patterning-first process
according to an embodiment of the invention.
[0036] FIG. 21 illustrates another example for patterning-first
process according to an embodiment of the invention.
DETAILED DESCRIPTION
General Process
[0037] According to embodiments of the invention, system and
methods are provided for fabricating patterned media disks. FIG. 1
illustrates a flow chart of a complete process for fabricating HDD
patterned media disks, generally divided into four modules
(indicated by light broken-line boxes). In FIG. 1 solid-line box
indicates utilization of conventional continuous media fabrication
equipment, broken-line box indicates utilization of lithography
equipment, such as, e.g., nano-imprint lithography, and double-line
box indicates utilization of novel patterned media fabrication
equipment. In module 10 fabrication starts by cleaning the disks in
a cleaning apparatus 12. The disks are then moved to a conventional
processing system 14, such as the 200 Lean.RTM. for fabricating
non-patterned magnetic layers. Thereafter, the disks are moved to a
lithography module 16 to imprint the patterning. The lithography
module may be any of the technologies currently under
consideration, including, but not limited to, nano-imprint
lithography. Generally, in the lithography module the disk is
coated with a photoresist, the photoresist is "exposed" to the
required pattern (either by radiation or physical contact with a
master, i.e., imprinted), then the exposed resist is developed, or
cured under UV irradiation. Once the lithography processing is
completed, the disk is transferred to the patterning system 18.
[0038] In the patterning system 18 various processing are
performed, which may include de-scum, resist trim, hard mask
deposition and etch, resist strip, metal etching, planarization
(which may include carbon or metal or oxide refill and etch-back).
These processes are performed in a plurality of chambers, each
having an independent vacuum environment; however, once the disk
enters system 18 it never leaves the vacuum environment until
processing is completed. The details about these processes and the
various system elements used to perform them will be described
below. Once processing in the patterning system 18 is completed,
the disks are moved to modules 20 and 22, which are not relevant to
the subject disclosure.
[0039] FIG. 2 illustrates cross section of a patterned media
undergoing a general process flow according to an embodiment of the
invention. The disk arrives at the patterning system having the
structure illustrated as 200. The structure includes the substrate
205 upon which a soft underlayer (SUL) 210 is deposited. The SUL
layer is a "soft" or relatively low-coercivity magnetically
permeable underlayer that serves as a flux return path for the
field from the write pole to the return pole of the recording head.
A seed layer 215 is formed over the SUL, 210 and the magnetic layer
220 is formed over the seed layer. To protect the magnetic layer on
disk from mechanical wear by the flying head and environmental
chemical corrosion, a thin protective coat of diamond type carbon
(carbon overcoat, COC) layer 225 is applied over the magnetic layer
220. Then a patterning mask 230 is formed using, e.g., photoresist
or other masking material in a nano-imprinting step. The structure
shown as 200 then undergoes processing in the patterning system, as
generally shown by structures 240, 250, 260 and 270.
[0040] In 240 the COC layer has been etched so as to be used as a
hard mask. That is, once the COC layer has been etched, the
photoresist may be removed and the COC layer would maintain the
desired pattern. Then at 250 the magnetic layer is etched using the
COC layer as the hard mask. Each of these two etch steps may be
performed as sequential steps, i.e., etching one side of the disk
at a time. This would be explained more completely below. In 260 a
carbon refill layer is deposited to fill the patterned magnetic
layer, and then the carbon refill layer is etched back to form a
relatively flat top surface. At 170 a thin protective coat of
diamond-like carbon layer (generally referred to as NCT carbon) is
formed.
General System Architecture
[0041] FIG. 3 illustrates an example of a patterning system
according to an embodiment of the invention. The general structure
of the system may mimic that of the 200 Lean.RTM. available from
Intevac, of Santa Clara, Calif. In this example the system has two
elevators, 302 and 304, and sixteen processing chambers, labeled
1-16. In the system, each chamber has a lower part that functions
as transport chamber for transporting the carrier with the disk,
generally 306, and an upper processing chamber for performing the
process on the disk. While some chambers process both sides of the
disk simultaneously, others process only one side, and so are
provided in pairs to complete processing on both sides of the
disk.
[0042] In the example of FIG. 3, chamber 1 is a de-scum chamber,
which may also be used for trimming the photoresist. Note that when
the process involved hard mask patterning, this step may be
skipped, provided that the photo-resist is of a desired shape and
gross dimension, as the hard mask patterning would remove any
excess photo-resist. This chamber processes both sides of the disk
simultaneously. Chambers 2 and 3 are utilized for carbon hard mask
etch, i.e., for etching the COC layer. In the example of FIG. 3 the
etch process may be done by oxidation assisted soft etch using,
e.g., biased RF source or remote plasma using, e.g., oxygen gas. In
this example a biased RF plasma is used, so that each of chambers 2
and 3 etches one side of the disk. This can be accomplished with
the close-proximity-bias backing plate mechanism used in the
stations 4, 6, 8 and 9. If a non-biased plasma is used, e.g.,
remote plasma source, the process may be performed in a single
chamber, etching both sides simultaneously. In general, for this
step selectivity of the etch is the natural selectivity ratio that
exist between photoresist and carbon, which can be between 1:1 to
up to 1:10, depending on the carbon type and the resist type. Total
etch thickness may be about 10-1000 A, depending on the magnetic
layer thickness and the etch selectivity. For the examples shown
herein, the end point of the COC etch may be critical so as to
avoid oxygen poisoning of the magnetic layer. Therefore, in one
embodiment, towards the end of the hard mask-oxidation assisted
etch-process, oxygen flow is stopped, so that the process continues
with oxygen free plasma. In another embodiment, the oxidative
reactant used for the carbon hard mask etch, maybe that of a
reduced (mitigated) oxidation-power reagent, that effectively stops
at the metal surface and allows for differentiation of the two
process step.
[0043] Since in most applications the thickness of the photoresist
would exceed that of the COC layer, it is likely that some
photoresist would remain after completing the COC etch. Therefore,
a step of reductive strip of resist may also be performed in
chambers 2 and 3, or in subsequent chambers (not shown). This may
be also performed using soft plasma using H2/O2 source gas. Since
this process may also use oxygen, it is critical to avoid oxygen
poisoning of the magnetic layer. This may be done by timely
stopping flow of oxygen or by forming a passivation layer (e.g.,
Pt, Ta, Cr) over the magnetic layer before performing the strip
resist step.
[0044] Chambers 4-9 are used to alternatingly etch the magnetic
layer on one side of the disk and cool the disk after an etch
process. In this example, no cooling chamber is provided between
chambers 8 and 9, as in this example cooling between these two etch
processes is done in elevator 304. Of course, if necessary, another
cooling chamber may be added between these two chambers. In this
example the magnetic layer is etched using ion beam etch (IBE),
which requires biasing the disk. Therefore, each chamber is
structured to etch only one side of the disk. If a reactive ion
etch (RIE) is used, each chamber may be configured to etch both
sides simultaneously. The magnetic layer etch is performed using an
innovative etch chamber that will be described in details in the
section under the heading Etch Chamber.
[0045] The magnetic layer etch process should be designed so as to
avoid puncturing the carbon hard mask, so here selectivity is more
important. Total etch depth of this step is about 100-1000 A. It is
desired to leave some thickness of the COC layer on top of the
un-etched islands, which also helps preventing damage to the
magnetic layer.
[0046] Chamber 10 is used for forming a carbon refill layer to fill
the etched regions. This may be done by sputtering carbon, e.g.,
NCT or sputtered carbon, filling with SiO2, or other materials. The
thickness of the refill should be sufficient to allow follow-on
planarization. In the example of FIG. 3 the refill is performed in
two stages (chambers 10 and 12), with two follow-on planarization
steps (chamber 11 and 13). Of course, depending on the refill
material and technology used for the refill and planarization,
other arrangements and different number of chambers may be
utilized. Planarization may be done using etch back, e.g., using
soft etch. The refill--etch back processing is followed with a
cooling chamber 14. Chambers 15 and 16 are used to form a hard
protective layer over the planarized refill. An additional benefit
of the carbon refill is to effectively passivate the side-wall of
the etched magnetic features. This is critical for the magnetic
integrity of the critical feature of a patterned media. The
side-wall coverage and passivation of the patterned medial
side-walls, can be accomplished by the NCT stations that are
field-deployed in the HDD industry with zero-bias, effecting a
chemical vapor deposition environment for isotropic carbon
deposition and side-wall coverage and passivation as needed for the
patterned media.
Alternative Processes and System Architectures
[0047] FIG. 4 illustrates another process for fabricating a
patterned media disk, starting from a photo-resist-patterned disk
400 that is the same as 200 in FIG. 2. FIG. 5 illustrates a general
architecture of a system tailored for executing the process of FIG.
4. With respect to step 440, after a de-scum/trim step in chamber
1, the disk is moved to chamber 2 for etching the thin COC and
thereby create a hard mask with some photo-resist possibly still
remaining on top of the COC layer. In step 450 the magnetic layer
is etched. In this example, the magnetic layer etch step is
performed sequentially with interlacing cooling steps. This is
shown in FIG. 5, wherein the disk undergoes RIE (Reactive Ion Etch)
etch on one side in chamber 3, is cooled in chamber 4, undergoes
further etch on the same side with a following cooling step. Then
the process repeats for the opposite side. In this example some
photo-resist still remains after the completion of the magnetic
layer etch step on both sides of the disk. Thereafter, in step 460
a carbon refill step is performed, followed by etch back. This step
may be repeated in chambers 12 and 3. Then the carbon refill is
etched back so as to expose and strip the remaining photo-resist
(step 470). Finally, a carbon protective layer is formed over the
disk in chambers 15 and 16.
[0048] FIG. 6 illustrates another process for fabricating a
patterned media disk, starting from a photo-resist-patterned disk
600 that is the same as 200 in FIG. 2. FIG. 7 illustrates a general
architecture of a system tailored for executing the process of FIG.
6. After a de-scum/trim step in chamber 1, a hard mask layer, e.g,
a SnO2 or carbon hard mask, is deposited over the photo-resist in
step 640. This step may be performed using sputtering process in
chamber 2. Then the photo-resist is striped in chamber 3, so that
only the SnO2 hard mask remains--step 650. The hard mask is then
used to etch the magnetic layer using alternating etch and cooling
chambers 4-9 (step 660). When the magnetic layer etch steps have
been competed, the SnO2 hard mask may optionally be removed in
chamber 10 using, e.g., hydrogen gas. Alternatively, chamber 10 may
be a cooling chamber and instead of removing the hard mask,
alternating steps of carbon refill and etch back are performed over
the hard mask, with the last etch back used to planarize the
surface of the disk and remove the SnO2 hard mask. Then a
protective coating is formed over both sides of the disk in
chambers 15 and 16.
Etch Chamber
[0049] In the examples of fabricating patterned media disks
discussed so far an etch step is required to etch the magnetic
layer. In the following, a novel movable non-contact electrode is
described for performing sputter etch which is particularly
beneficial for sputtering of hard disks used in hard disk drives
(HDD). The electrode moves to near contact distance to, but not
contacting, the substrate so as to couple RF energy to the disk.
The material to be etched may be metal, e.g., Co/Pt/Cr or similar
metals. No surface contact is allowed by any part of the system.
The substrate is held vertically in a carrier and both sides must
be etched. In one embodiment, one side is etched in one chamber and
then the second side is etched in the next chamber. An isolation
valve is disposed between the two chambers and the disk carrier
moves the disks between the chambers. The carrier may be a linear
drive carrier, using, e.g., magnetized wheels and linear
motors.
[0050] In one embodiment the chamber has a showerhead on one side
and a movable electrode on the other side. The showerhead may be
grounded or biased, and has provisions for delivering gas into the
chamber, e.g., argon, and/or reactive gases, such as CxFy,
Cl.sub.2, Br.sub.2, etc. The chamber also has guides or rails for
the linear drive disk carrier. When the disk carrier assumes
processing position, the electrode is moved close to the disk, but
not touching it. An RF power, e.g., 13.56 MHz is coupled to the
electrode, which is capacitively coupled to the disk. A plasma is
then ignited in the void between the disk and the showerhead, to
thereby sputter material from the face of the disk. In the next
chamber, the exact arrangement is provided, except in the opposite
facing order, so that the opposing face of the disk is etched. A
cooling chamber may be interposed between the two chambers, or
after the two chambers.
[0051] An embodiment of the inventive etch chamber will now be
described with reference to the drawings. FIG. 8 illustrates part
of a system for fabricating a patterned hard disk according to an
embodiment of the invention, e.g., part of the system illustrated
in any of FIG. 3, 5, or 7. In FIG. 8, three processing chambers,
100, 105 and 110, are shown, but the three dots on each side
indicates that any number of chambers may be used. Also, while here
three specific chambers are shown, it is not necessary that the
chamber arrangement shown here would be employed. Rather, other
chamber arrangements may be used and other type of chambers may be
interposed between the chambers as shown.
[0052] For illustration purposes, in the example of FIG. 8 the
three chambers 100, 105 and 110 are etch chambers, each evacuated
by its own vacuum pump 102, 104, 106. Each of the processing
chambers has a transfer section, 122, 124 and 126, and a processing
section 132, 134 and 136. Disk 150 is mounted onto a disk carrier
120. In this embodiment the disk is held by its periphery, i.e.,
without touching any of its surfaces, as both surfaces are
fabricated so as to pattern both sides. The disk carrier 120 has a
set of wheels 121 that ride on tracks (not shown in FIG. 8). In one
embodiment, the wheels are magnetized so as to provide better
traction and stability. The disk carrier 120 rides on rails
provided in the transfer sections so as to position the disk in the
processing section. In one embodiment, motive force is provided
externally to the disk carrier 120 using linear motor arrangement
(not shown in FIG. 8).
[0053] FIG. 9 illustrates a cross section along lines A-A in FIG.
8. For simplicity, in FIG. 9 disk 250 is illustrated without its
carrier, but it should be appreciated that the disk remains on the
disk carrier throughout the processing performed in the system of
FIG. 8, and is transported from chamber to chamber by the disk
carrier, as illustrated by the arrow in FIG. 9. In this
illustrative embodiment, in each chamber, 200, 205 and 210, the
disk is fabricated on one side. As shown in FIG. 9, as the disk
moves from chamber to chamber the disk is fabricated on alternating
sides, however it should be appreciated that the order of surface
fabrication may be changed. Also shown in FIG. 9 are isolation
valves 202 206 that isolate each chamber during fabrication. Each
chamber includes a movable electrode (in this example a cathode)
242, 244, 246, mounted onto a movable support 242', 244', 246', and
a precursor gas delivery apparatus 262, 264, 266, such as a shower
head.
[0054] FIG. 10 illustrates a cross section along lines B-B in FIG.
8. Disk 350 is shown mounted onto carrier 320. Carrier 320 has
wheels 321, which ride on tracks 324. The wheels 321 may be
magnetic, in which case the tracks 324 may be made of paramagnetic
material. In this embodiment the carrier is moved by linear motor
326, although other motive forces and/or arrangements may be used.
Once the chamber is evacuated, precursor gas is supplied into the
chamber via, e.g., shower head 364. The shower head may be
grounded. Plasma is ignited and maintained by applying RF bias
energy to the movable cathode 344. While other means for igniting
and maintaining the plasma may be utilized, movable cathode
provides the bias energy necessary to attract the plasma species
and accelerate them towards the disk so as to sputter material from
the disk. That is, when the movable cathode 344 is moved very close
to one surface of the disk, it capacitively couples the RF bias
energy to the disk, so that plasma species are accelerated towards
the disk so as to etch the opposite surface. It should be
appreciated that while FIG. 8 is explained with respect to a
movable cathode 344, the same effect can be achieved by using a
moving anode, as will be explained with respect to FIG. 16.
[0055] FIG. 11A is a partial isometric view shown the movable
electrode in a position away from the disk, while FIG. 11B is a
partial isometric view showing the movable electrode in a position
proximal to the disk. FIG. 11A illustrates the situation when the
disk is just inserted into the chamber or is about to leave the
chamber, and no processing is performed. FIG. 11B illustrates the
situation of the chamber during processing, i.e., during etching of
the disk. Disk 450 is held by its periphery by clips 423 of carrier
420 (four clips are utilized in this example). The movable
electrode assembly 444 includes the electrode housing 441,
electrode cover 443, and electrode 447. In this example, electrode
cover 443 has notches 449 that match the clips 423, so that in its
proximal position, shown in FIG. 11B, the cover does not touch the
clips. Also, while a bit obscured, the electrode itself is in a
doughnut shape, matching the shape of the disk, i.e., having a
center hole matching the center hole of the disk.
[0056] FIG. 12 illustrates an etch chamber according to an
embodiment of the invention. In FIG. 12 some elements were cut and
some removed in order to expose elements that are relevant to
understanding the embodiment. The entire assembly is mounted on a
main chamber body 500, having lower part 522 serving as transport
chamber for carrier transport and upper part 532 dedicated for disk
fabrication, i.e., etch. In this figure, the tracks and linear
motor that normally reside in transport chamber 522 have been
removed to provide a clearer view. Precursor gas delivery is done
from one side of the main chamber body 500, while RF energy
coupling is provided from the other side. In this embodiment
precursor gas is delivered into the chamber using a showerhead
assembly 562. RF energy coupling is accomplished using a movable
electrode assembly that comes very close to, but does not touch the
disk. The electrode assembly is moved using motion assembly 585 so
as to be in a retracted mode during disk motion and in an extended
mode during etching (see FIGS. 11A and 11B).
[0057] RF energy coupling is done capacitively from a conductive
electrode to the disk and thence to the plasma. The electrode
assembly comprises an electrode 544 made of conductive material and
shaped to complement the surface of the disk. An electrode cover
543 is provided about the electrode, and extends beyond the
electrode 544 so that when the electrode is in its proximal,
energized position, the electrode cover 543 covers the edges of the
disk. In this position the electrode cover 543 prevents plasma
species from attacking the sides of the disk and prevents plasma
from reaching the backside surface of the disk, i.e., prevents
plasma from excaping the space between the surface facing the
electrode and the electrode.
[0058] For non-reactive etch, the precursor gas may be, for
example, argon. Since the magnetic metals generally utilized for
magnetic disks may be physically etched, i.e., by sputtering, argon
is a suitable precursor gas. During processing the chamber may be
maintained at reduced pressure, e.g., 10-80 millitorr (mT),
although certain processes may be performed at pressures of 1 mT to
10 torr. The RF energy may be set to, e.g., 100-3000 watts, at
frequency of, e.g., 13.56 MHz. In the example of FIG. 5 the
construction is made compact by coupling the RF match 580 to the
etch chamber. RF power from the match 580 is coupled to the
conductive electrode 544. In one embodiment, fluid pipes 547
provide fluid as a heat exchange medium to cool or heat the
electrode 544. Similarly, fluid pipes 569 may provide heat exchange
fluid to the showerhead.
[0059] In order to effectively couple the RF energy to the disk,
the electrode 544 must be place very close to the disk. In the
embodiments illustrated the distance between the disk and the
electrode may be set to between 0.02'' to 0.75''. In these examples
the placement may be done to an accuracy of .+-.0.005''. In one
example, the placement accuracy is enabled by using a proximity
sensor, such as, e.g., one or more optical sensors. As shown in
FIG. 12, fiber optic 582 provides optical path from the electrode
544 to an optical sensor 584. A plurality of fiber optics and
corresponding sensors may be used and various optical techniques
may be utilized to enhance placement accuracy and prevent collision
with the disk.
[0060] In one example, both the electrode and the showerhead are
made of hard anodized aluminum. Notably, unlike conventional etch
chambers, here the conductive surface of the electrode is exposed
and is not covered with an insulator. As in other examples, the
showerhead is grounded and is fixed, i.e., not movable. Insulating
parts may be made of alumina (where exposure to plasma may occur)
or Ultem. With the embodiments as described, etch rates higher than
10 nm per second may be achieved.
[0061] FIG. 13 illustrates an embodiment of a system having
alternating etch chambers and cooling stations. As indicated by the
three dotes on each side, the arrangement may repeat itself or be
coupled to other chambers performing other processes or to cooling
or transfer chambers. Notably, chamber 600 is positioned to etch
one surface of the disk 650. The isolation valve 602 is then opened
and the disk is moved to cooling chamber 600'. At the next round
valve 602' is opened and the disk is moved into etch chamber 605.
Etch chamber 605 is positioned to etch the opposite side of the
disk. Thereafter the disk is moved to another cooling station
605'.
[0062] FIG. 14 illustrate a flow of a process according to an
embodiment of the invention. At step 700 the isolation valves are
open and at step 705 the carrier is transported so as to place the
substrate in the proper position for processing. At step 710 the
isolation vales are closed and at step 715 the electrode moves to
its proximal position, i.e., near but not touching the substrate.
At step 720 gas is supplied to the chamber and at step 725 RF is
provided to the electrode to ignite and maintain the plasma. Note
that if another arrangement is used to ignite the plasma, e.g.,
inductive coils, remote microwave, etc., the RF to the electrode is
still needed in order to provide the bias potential to accelerate
plasma species towards the substrate. The gas and RF are supplied
as long as processing proceeds and, when process it terminated at
step 730, RF is terminated at 735, gas delivery is terminated at
740, and then the electrode is moved to its distal position, i.e.,
away from the substrate. The process may then be repeated to
process the next disk and move the current disk to another
chamber.
[0063] FIG. 15 illustrates an alternative embodiment of the system
according to the invention. In FIG. 15, the two etching chambers
800 and 805 are coupled without any cooling chamber in between
them. Rather, a cooling chamber 800' and 805' is provided between
each doublets of etch chambers, so that the substrate undergoes
etching on both sides before it enters a cooling chamber.
[0064] FIG. 16 illustrates certain alternative features according
to embodiments of the invention. For illustration purposes, the
chamber of FIG. 16 is similar to that of FIG. 10, highlighting the
following differences. For example, in the chamber of FIG. 16 one
or more gas injectors 972 are provided, rather than using a
showerhead. Conversely, the chamber may employ both a showerhead
and gas injectors. For example, the showerhead may provide one type
of gas, e.g., inactive gas, while the injector provide another type
of gas, e.g., reactive gas. Another feature of the chamber of FIG.
16 is the use of a movable anode. That is, in the chamber of FIG.
16, the RF power is coupled to a stationary electrode 964, which
may or may not be embedded in a showerhead. A movable anode 944 is
coupled to ground.
[0065] FIG. 17 is a flow chart illustrating a process according to
an embodiment of the invention. The process of FIG. 17 may be
utilized with any of the chambers structured according to the
subject invention. In step 1000, a substrate is moved into the
chamber. In step 1005 the movable electrode is moved to a position
proximal to, but not touching, the substrate. In step 1010 gas is
introduced into the chamber and in step 1015 power is coupled to
either the movable or stationary electrodes, so that in step 1020
plasma is ignited. In this condition the substrate is processed by,
e.g., physical and/or reactive ion etching. When processing step is
completed, either by timing or by detecting an end-point, the RF
power is turned off in step 1025, the electrode is retracted to its
distal position in step 1030, and the chamber is evacuated in step
1035. In step 1040 the substrate is removed and the process repeats
itself for another substrate. It should be noted that while
removing one substrate and introducing another substrate is shown
as two separate steps, these can be done concurrently, i.e., as one
substrate moves out the second one may be moved in.
Alternative Non-Etch Processes and System Architectures
[0066] FIG. 18 illustrates a non-etch process for fabricating a
patterned media disk according to an embodiment of the invention.
FIG. 19 illustrates a general architecture of a system tailored for
executing the process of FIG. 18. In this example ion implantation
is used to define the patterns of the magnetic layer. Following
de-scum/strip process in chamber 1, ion implementation is performed
at step 840. As shown in FIG. 19, in this example the ion
implantation process is performed one side at a time, with cooling
in between. The implementation may be of, e.g., He, N or Ar ions
that would disturb the magnetic layer so as to define pattern
therein. When implantation is completed, at step 850 the
photo-resist is stripped (chamber 8). Then, a protective layer is
formed at step 860 (chamber 11 and 12).
Alternative Patterning-First Processes and System Architectures
[0067] FIG. 20 illustrates an example for patterning-first process
according to an embodiment of the invention. The process of FIG. 20
starts by patterning a photoresist 2030 over the SUL layer 2010
which was formed on substrate 2005. This structure is then moved
into a system configured according to embodiments of the invention,
using any of the examples disclosed herein. At step 2040 a hard
mask 2032 is formed over the patterned photo-resist. In step 2050
the photo-resist is removed so as to leave only pattern formed by
the hard mask 2032. In step 2060 the SUL layer is etched using the
hard mask for patterning. This step may be performed by
sequentially etching each side of the disk, as described above. The
hard mask may then be removed (not shown) and then a seed layer
2072 and magnetic layer 2074 are formed over the etched pattern in
step 2070, which is then capped with carbon deposition/etch back
and a protective layer 2082 in step 2080.
[0068] FIG. 21 illustrates another example for patterning-first
process according to an embodiment of the invention. The process of
FIG. 21 starts by patterning a photo-resist 2030 directly over
substrate 2005. This structure is then moved into a system
configured according to embodiments of the invention, using any of
the examples disclosed herein. At step 2140 a hard mask 2132 is
formed over the patterned photo-resist. In step 2150 the
photo-resist is removed so as to leave only pattern formed by the
hard mask 2132. In step 2160 the substrate 2105 is etched using the
hard mask 2132 for patterning. This step may be performed by
sequentially etching each side of the disk, as described above. The
hard mask may then be removed (not shown) and then a SUL layer
2176, a seed layer 2172 and magnetic layer 2174 are formed over the
etched pattern in step 2070, which is then capped with a carbon
deposition/etch back and a protective layer 2182 in step 2180.
[0069] It should be appreciated that the processes and systems
described herein enable commercial fabrication of patterned media
disks for hard drives. Fast production and high yield are enabled
by the system wherein after the formation of the photo-resist
pattern the disk in moved into vacuum environment in the system and
the entire patterning fabrication is performed without removing the
disk from the vacuum environment.
[0070] It should be understood that processes and techniques
described herein are not inherently related to any particular
apparatus and may be implemented by any suitable combination of
components. Further, various types of general purpose devices may
be used in accordance with the teachings described herein. It may
also prove advantageous to construct specialized apparatus to
perform the method steps described herein. The present invention
has been described in relation to particular examples, which are
intended in all respects to be illustrative rather than
restrictive. Those skilled in the art will appreciate that many
different combinations of hardware, software, and firmware will be
suitable for practicing the present invention. Moreover, other
implementations of the invention will be apparent to those skilled
in the art from consideration of the specification and practice of
the invention disclosed herein. Various aspects and/or components
of the described embodiments may be used singly or in any
combination in the server arts. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
* * * * *