U.S. patent application number 12/133128 was filed with the patent office on 2009-07-23 for method of storing data using a micro-electromechanical system based data storage system.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Urs T. Duerig, Bernd W. Gotsmann, Armin W. Knoll.
Application Number | 20090185474 12/133128 |
Document ID | / |
Family ID | 39589632 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090185474 |
Kind Code |
A1 |
Duerig; Urs T. ; et
al. |
July 23, 2009 |
METHOD OF STORING DATA USING A MICRO-ELECTROMECHANICAL SYSTEM BASED
DATA STORAGE SYSTEM
Abstract
A method of storing data using data storage system having a
positioning system for a micro-electromechanical system ("MEMS")
based data storage is provided. The method includes a moving
MEMS-based scanner that interacts with a polymer medium to read,
write and erase data. A first positioning system is coupled to the
MEMS scanner to allow the storage of data over a defined area. A
second positioning system is coupled to the first positioning
system and the MEMS scanner to allow the use of a larger polymer
medium. A plurality of storage modules is also provided to allow
scalability of data storage.
Inventors: |
Duerig; Urs T.;
(Rueschlikon, CH) ; Gotsmann; Bernd W.; (Horgen,
CH) ; Knoll; Armin W.; (Adliswil, CH) |
Correspondence
Address: |
Cantor Colburn LLP-IBM Europe
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
39589632 |
Appl. No.: |
12/133128 |
Filed: |
June 4, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12017791 |
Jan 22, 2008 |
7397754 |
|
|
12133128 |
|
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|
Current U.S.
Class: |
369/126 |
Current CPC
Class: |
G11B 9/1454 20130101;
G11B 9/04 20130101; B82Y 10/00 20130101 |
Class at
Publication: |
369/126 |
International
Class: |
G11B 9/00 20060101
G11B009/00 |
Claims
1. A method of storing data using a micro-electromechanical system
(MEMS) based data storage system having a storage module, said
method comprising: arranging an array of MEMS cantilever devices
adjacent a stationary data surface in said storage module, wherein
each of said MEMS cantilever devices includes an associated tip;
coupling a CMOS device to said array of MEMS cantilever devices;
coupling circuits associated with said CMOS device to receive
signals from said MEMS cantilever devices; moving said CMOS device
with a motion generator over an area of 100 .mu.m.times.100 .mu.m;
sliding said motion generator on a first guide rail; magnetically
coupling a first magnetic actuator associated with said first guide
rail to said motion generator, wherein said first magnetic actuator
is arranged to linearly move said motion generator up to 10 cm in a
first direction relative to said data surface; coupling said motion
generator to a second guide rail, wherein said second guide rail is
arranged generally perpendicular to said first guide rail;
magnetically coupling a second magnetic actuator associated with
said second guide rail to said array of MEMS cantilever devices,
wherein said second magnetic actuator is arranged to linearly move
said array of MEMS cantilever devices up to 10 cm in a second
direction relative to said data surface wherein said second
direction is perpendicular to said first direction and in a plane
parallel to said data surface; and, moving said array of MEMS
cantilever devices on said first guide rail and second guide rail
independently in said first and second direction simultaneously.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/017791 entitled "Micro-electromechanical
System Based Data Storage System" filed on Jan. 22, 2008, which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a micro-electromechanical
system (MEMS) based data storage system, and in particular to MEMS
based data storage systems having coarse and fine positioning
arrangements.
[0003] A MEMS based system can be utilized to generate
nanometer-scale motion. Such systems can take advantage of this
motion to build the capability of spanning micrometer-scale areas
in an x-y plane. An important application of this type of system is
in the area of atomic force microscopy ("AFM") storage
applications.
[0004] In this application, a polymer medium is used for recording
information with a MEMS scanner. Typically, the scanner includes an
array of MEMS devices that are able to read, write and erase data
on the polymer medium. Each of the MEMS devices includes a
micrometer scale tip that can be used to scan the surface of the
polymer medium. The tip is heated to a specified temperature and
force is applied for writing information in the form of indents and
the resistance of the electrical heater is measured to read back
the data on the polymer medium. Due to their small size of the tip
apex, typically 10 nm, the use of the MEMS scanning devices allows
a high data storage density to be achieved.
[0005] In general, some form of positioning device is needed to
ensure proper alignment of the tip with the medium and to allow a
single tip to scan over a broader area. However, due to the level
of precision needed and the amount of data output required, the
amount of area a single MEMS device could write to is relatively
limited. Therefore, to increase the capacity, or scale the amount
of data stored with such MEMS based systems requires either the
increase in size of the array, or the use of multiple arrays. While
each of these techniques has allowed the amount of storage to be
increased, it has also increased manufacturing costs as well.
[0006] While current data storage systems are suitable for their
intended purposes, there exists a need for improvements of high
capacity data storage system to allow scalability in the amount of
data stored and retrieved with MEMS based devices.
BRIEF DESCRIPTION OF THE INVENTION
[0007] A method of storing data using a micro-electromechanical
system (MEMS) based data storage system having a storage module is
provided. An array of MEMS cantilever devices is arranged adjacent
a data surface, wherein each of the MEMS cantilever devices
includes an associated tip. A CMOS device is coupled to the array.
Circuits associated with the CMOS device are coupled to receive
signals from the MEMS cantilever devices. The CMOS device is moved
with a motion generator over an area of 100 .mu.m.times.100 .mu.m.
The motion generator slides on a first guide rail and is
magnetically coupled a first magnetic actuator associated with the
first guide rail, wherein the first magnetic actuator is arranged
to linearly move the motion generator up to 10 cm in a first
direction relative to the data surface. The motion generator is
also coupled to a second guide rail, wherein the second guide rail
is arranged generally perpendicular to the first guide rail. A
second magnetic actuator associated with the second guide rail is
magnetically coupled to the array of MEMS cantilever devices,
wherein the second magnetic actuator is arranged to linearly move
the array of MEMS cantilever devices up to 10 cm in a second
direction relative to the data surface. The second direction is
perpendicular to the first direction and in a plane parallel to the
data surface. Finally the array of MEMS cantilever devices are
moved on the first and second guide rails independently in the
first and second direction simultaneously.
[0008] In another embodiment, the array of MEMS cantilever devices
is positioned on an angle relative to the first direction. The
angle of the array of MEMS cantilever devices is approximately 1/n
where n equals the number of the MEMS cantilever devices in a row
of the array. The data tracks are separated by a distance
approximately D/n where D is the row period of the MEMS array.
Finally, the CMOS device is configured to wirelessly receive and
transmit signals to a drive having a power supply circuit and a
control circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
objects, features, and advantages of the invention are apparent
from the following detailed description taken in conjunction with
the accompanying drawings in which:
[0010] FIG. 1 is a schematic illustration of an exemplary
embodiment micro-electromechanical system (MEMS) cantilever device
used with data storage;
[0011] FIG. 2 illustrates a schematic representation of a MEMS
based scanner arrangement for a data storage device having an array
of the MEMS cantilever devices of FIG. 1;
[0012] FIG. 3 illustrates a top plan view of an exemplary
embodiment data storage module using the MEMS based scanner of FIG.
2;
[0013] FIG. 4 is a schematic representation of an alternate
embodiment array of MEMS cantilever devices arranged on an angle
relative to the direction of travel;
[0014] FIG. 5 is a plan view of a storage medium having a plurality
of sub-bands formed by the array of MEMS cantilever devices of FIG.
4.
[0015] FIG. 6 is a perspective view illustration of data storage
system having a plurality of the data storage devices of FIG.
3.
[0016] The detailed description explains exemplary embodiments,
together with advantages and features, by way of example with
reference to the drawings.
DETAILED DESCRIPTION
[0017] Micro-electromechanical systems (MEMS) based storage systems
that utilize a MEMS cantilever device are desirable due to their
ability to store data at a high level of density, exceeding 1
terabit/in.sup.2. An exemplary embodiment of such a system is shown
in FIG. 1 and FIG. 2. The individual MEMS cantilever device 10
includes a pair of cantilever arms 12 that are supported by a
structure 14. The arms 12 are connected by a heater 16 that is
coupled to a probe tip 18. The arms 12 and heater 16 cooperate to
form a current path during operation.
[0018] The probe tip 18 is arranged adjacent to a polymer layer 20
that is formed on a substrate 22. The polymer layer 20 and
substrate 22 forms a stationary storage medium 26 that is used to
store data in the storage system. During a write operation, the
probe tip 18 is heated by passing current through the arms 12 and
into the heater 16. The heat generated by heater 16 is conducted
into the probe tip 18 to a temperature sufficient to form indents
or pits 24 in the polymer layer 20. The pits 24 are then formed by
moving the probe tip 18 into contact with the polymer layer 20.
Typically, to form a pit 24, the heater 16 of the probe tip 18 is
heated to a temperature of approximately 400.degree. C. These pits
24 correspond to a data bit with a single pit 24 typically
representing a logic "1", and the absence of a pit in a particular
location being a logic "0".
[0019] The heater 16 and probe tip 18 are also a sensor for reading
data from the storage medium 26. For data reading operation,
current is passed through the arms 12 and into the heater 16,
resulting in an increase in the temperature of the probe tip 18.
The increase in temperature, unlike the write operations, is not
sufficient to deform the polymer layer 20 to form a pit 24. The
temperature of the heater 16 during read operations is typically on
the order of about 200.degree. C. It should be appreciated that the
thermal conductance between the heater 16 and the polymer layer 20
varies depending on the distance between the heater 16 and polymer
layer 20. During a read operation, the probe tip 18 is moved across
the surface of polymer layer 20. When the probe tip 18 is moved
into a region having a pit 24, the distance between the heater 16
and the polymer layer 20 changes resulting in a change in
temperature. Since resistance is dependent on temperature, by
monitoring the resistance of the heater 16 as the tip is placed
adjacent a data location, the presence or lack of presence of a pit
24 may be determined. Thus the change in resistance is detected.
The change in resistance represents information (a "1" or "0" bit).
The data rate for a single MEMS device 10 is typically between 100
kbits/s to 1 Mbit/s.
[0020] By arranging the MEMS device 10 into an array of devices, a
storage system having a high storage capacity may be achieved.
Referring now to FIG. 2, an exemplary embodiment array 28 having
MEMS devices 10 is illustrated. In the exemplary embodiment, the
array 28 may have between 1000 and 10,000 MEMS devices 10. An array
with 1000 MEMS devices would have an area of approximately 3
mm.times.3 mm. Time multiplexed electronics control the
read/write/erase functions needed by the storage system to operate
the MEMS device 10. In the embodiment illustrated in FIG. 2, the
array 28 is assembled with an electronics circuit 30. In the
exemplary embodiment, the circuit 30 is complementary metal-oxide
semiconductor ("CMOS") based circuit having an area of about 12
mm.times.12 mm. The array 28 and CMOS circuit 30 are assembled on
to a motion generator or scanner 32 to form a laminated MEMS
scanner assembly 34. The scanner 32 is coupled to one or more
actuators 36, 38, 40 that can move the circuit 30 and array 28 in
the x, y, and z direction relative to the storage medium 26. In the
exemplary embodiment, the scanner 32 provides movement over an area
up to about 100 .mu.m.times.100 .mu.m to allow an accurate level of
positioning control.
[0021] During operation, the circuit 30 reads the value of the
resistance in the heater 16 and translates the value into an analog
signal. The analog signal of the array 28 is multiplexed to an
analog to digital ("A/D") converter 42. In the exemplary
embodiment, there is one A/D converter 42 for each group of 64 MEMS
devices 10. Where multiple A/D converters 42 are utilized, the
signals from these converters 42 are further multiplexed in the
digital domain (not shown). This allows the transmission of a
single data stream to a drive controller 44. The transmission of
the data from the MEMS scanner assembly 34 to the drive 44 may be
performed using high bandwidth cabling, or, preferably through a
short range wireless technology including but not limited to
Bluetooth, 802.11 (WiFi), direct sequence-UWB, WiMedia Alliance and
Multiband OFDM Alliance ("MBOA") UWB, wireless USB, IEEE 1394. In
the exemplary embodiment, this arrangement is capable of
transmitting an aggregate data rate between 800 MB/s to 1 GB/s. As
will be discussed in more detail below, the drive 44 includes
circuitry that aggregates and controls the flow of data from
multiple MEMS arrays 28 that are associated with respective storage
mediums to provide data from the storage system to the end user at
a high data transfer rate. Drive 44 may further include power
supply circuitry and controls for providing electrical power to
MEMS arrays 28.
[0022] The scanner 32 provides the fine positioning needed to
quickly, accurately and repetitively read, write and erase date
from the storage medium 26. However, to scale the amount of data
stored on a storage medium 26, either additional MEMS scanner
assemblies 34 would be needed, or the MEMS scanner assembly 34
would need to be moved over a larger range relative to the storage
medium 26. An exemplary embodiment storage module 46 is illustrated
in FIG. 3. In this embodiment, the MEMS scanner assembly is
slidably mounted on first 48 and second 50 guide assemblies by a
set of bearings 52.
[0023] The first guide assembly 48 includes a first and second
guide rail 54, 56 that extend transversely across the surface of
the storage medium 26. A pair of cross members 58, 60 connects the
first and second guide rails 54, 56 at each end. Bearings 64, 66
are coupled to the cross members 58, 60 to allow the first guide
assembly 48 to linearly slide relative to the storage medium 26 in
a direction represented by arrow 62. The arrow 62 is generally
perpendicular to the length of the first guide assembly 48. The
bearings 64, 66 are supported by guides (not shown) that extend
parallel to the edge of storage medium 26 (shown in FIG. 1) in the
direction of arrow 62.
[0024] An actuator 68 is coupled to each cross member 58, 60. In
the exemplary embodiment, the actuator 68 uses magnetic force
transduction to cause the movement of the first guide assembly 48.
In this embodiment, an armature 70 is mounted to each cross member
58, 60. The armature 70 interacts with a magnetic field generated
by field member 72. As the field member 72 is moved in the
direction of arrow 62, the first guide assembly is also moved under
the influence of the magnetic field. As the first guide assembly 48
is moved, the MEMS scanner assembly 34 will also move in the same
direction. The first guide assembly 48 allows the MEMS scanner
assembly 34 to travel the full length of the storage medium 26. In
the exemplary embodiment, the storage medium is sized to fit within
a storage cassette having dimensions of 10 cm.times.10 cm.times.2
cm. It should be appreciated that the use of a magnetic actuator 68
and wireless data transmission provides advantages in that the
storage module 46 may be operated in hermetically sealed within a
housing (not shown) having no openings or feed-through. Since the
pits 24 in the polymer layer 20 are approximately 10 nm wide and 1
nm deep, the use of a hermetically sealed housing would aid in
preventing contamination of the MEMS scanner assembly 34 and the
storage medium 26.
[0025] The second guide assembly 50 is constructed in a similar
manner to first guide assembly 48 except that the second guide
assembly has a range of motion in the direction indicated by arrow
74. The second guide assembly 48 includes first and second rails
76, 78 that are connected at each end by cross members 80, 82. A
pair of bearings 84, 86 is mounted to each cross member 80, 82 to
allow the second guide assembly 50 to move linearly relative to the
storage medium 26 in the direction indicated by arrow 74. The
bearings are supported by guides (not shown) that extend parallel
to the edge of storage medium 26 in the direction of arrow 74. A
second pair of actuators 88 is coupled to cross members 80, 82. As
discussed above, in the exemplary embodiment, the actuators 88 use
magnetic force transduction to cause the movement of the second
guide assembly 50. As the second guide assembly 50 is moved, the
MEMS scanner assembly 34 will also move in the same direction. The
second guide assembly 50 allows the MEMS scanner assembly 34 ton
travel the full length of the storage medium 26. As discussed
above, in the exemplary embodiment, the storage medium is sized to
fit within an storage cassette having dimensions of 10 cm.times.10
cm.times.2 cm. The exemplary actuator 88 includes armatures 90 that
are coupled to each cross member 80, 82 and field members 92 that
are mounted adjacent to the armatures 90. A magnetic field
generated by the field members 92 acts on the armatures 90 to cause
movement of the second guide assembly 50.
[0026] By slidably coupling the MEMS scanner assembly 34 to the
first and second guide assemblies 48, 50, the MEMS scanner assembly
34 may be positioned anywhere on the storage medium 26. Further,
the first and second guide assemblies 48, 50 may simultaneously
move the MEMS scanner assembly 34 independently from each other
allowing the MEMS scanner assembly 34 to be quickly positioned in
the location of the desired data. In operation, the guide
assemblies translate the MEMS scanner assembly 34 to the desired
location on the storage medium 26 and the scanner 32 uses actuators
36, 38, 40 to adjust the position of the MEMS array 28 to the
location of the data with a high level of precision. Thus, the
amount of data that may be stored is scalable by increasing the
size of the storage medium 26 without increasing the number of
scanner assemblies 34, which reduces manufacturing costs and the
complexity of the system.
[0027] In operation, the data may be accessed from the storage
medium in several ways. The first method involves using the guide
assemblies 48, 50 to position the MEMS scanner assembly 34 in the
general area of the desired data. Once the scanner assembly 34 is
positioned, the scanner 32 can raster scan in the x and y
directions to access the data.
[0028] Alternatively, the scanner assembly 34 may be oriented on an
angle relative to the direction of travel 74 as shown in FIG. 4. In
this embodiment, the MEMS array 28 is rotated to an angle and the
scanner assembly is moved longitudinally along the length of the
guide assembly 48. As a result, each MEMS device 10 has a data
track along the length of the row. For example, MEMS device 96 is
oriented to align with line 94. Line 94 represents a line of data,
e.g., pits 24, which is parallel to the direction of travel 74. If
the angle is on the order of 1/n rad (angular units, 360 deg
corresponding to 2 pi), where n denotes the number of cells in a
row, the overlapping of data tracks may be avoided. Thus, only MEMS
device 96 will read, write and erase data in track 94 and only MEMS
device 98 will read write and erase data in track 100. This
continues across the MEMS array 28 with each MEMS device having a
unique data track. The data tracks are separated by a distance D/n,
where D is the row-period of the MEMS array (distance between two
adjacent probe tips measured along the row direction, see FIG. 4).
The area enclosed by two adjacent tracks forms a sub-band 102 as
shown in FIG. 5 in which one MEMS device 96 for the sub-band
enclosed by tracks 94, 100, can write multiple tracks of data
without interfering with other MEMS devices. In the exemplary
embodiment, D=100 .mu.m and n=32, the sub-band 102 has a width "t"
of approximately 2.5 .mu.m. Further, a grace distance "d" of
approximately 0.5 .mu.m separates each sub-band.
[0029] The alternate embodiment illustrated in FIGS. 4 and 5
provides additional advantages. Since the data is arranged in
linear rows or data tracks, the guide assembly 48 may move the
scanner assembly 34 along the track to acquire data rather than
merely positioning the scanner assembly 34 on a gross or coarse
level. This reduces the requirements and need for the scanner 32.
While the embodiment may eliminate the need for an actuator, e.g.,
actuator 36, in the direction of travel, it is expected that some
amount of fine adjustment may be needed to calibrate the
positioning of the scanner assembly 34 and correct errors in the
positioning by the guide assemblies 48, 50.
[0030] Referring now to FIG. 6, a storage system 101 utilizing
multiple storage modules 46 are shown. In this embodiment, the
storage modules 46 are positioned in stacked arrangement within a
housing 104. In the exemplary embodiment, there are 7 storage
modules 46 arranged within the housing 104, which is sized to fit
and be compatible with existing archival storage cartridge ("ASC")
systems. An ASC will generally have a dimension of about 10
cm.times.10 cm.times.2 cm. A sealed housing 106 may protect each
the individual storage modules 46. The housing 106 maintains the
interior environment to keep contaminants from the storage medium
and MEMS scanner assembly. The use of individually packaged storage
modules 46 provides an advantage in that if a single storage module
needs repair or maintenance, it may be removed without disrupting
the operation of the other modules. Alternatively, the housing 106
may be eliminated and the housing 104 may be hermetically sealed to
protect the internal components. This would allow a decrease in
manufacturing labor, material and assembly costs. Further, the
storage system 101 may also be arranged as a redundant array of
independent disks (commonly referred to as "RAID") where data is
divided and replicated among the multiple storage modules to
increase data reliability and performance.
[0031] As discussed above, each of the storage modules 46 are
coupled to a drive circuitry 108. The drive 108 may be located
internal to the housing 104 or alternatively external to the
housing. In another embodiment, the housing 14 is sized and
configured to be received in an archival cartridge storage system.
This provides additional advantages in that it allows the storage
system 101 to used in existing data storage systems. It is also
contemplated that the drive 108 may be incorporated into the
archival system to allow further increases in scalability while
decreasing manufacturing costs.
[0032] The diagrams depicted herein are just examples. There may be
many variations to these diagrams or the steps (or operations)
described therein without departing from the spirit of the
invention. For instance, the steps may be performed in a differing
order, or steps may be added, deleted or modified. All of these
variations are considered a part of the claimed invention.
[0033] While exemplary embodiments have been described, it will be
understood that those skilled in the art, both now and in the
future, may make various improvements and enhancements which fall
within the scope of the claims which follow. These claims should be
construed to maintain the proper protection for the invention first
described.
* * * * *