U.S. patent application number 13/946490 was filed with the patent office on 2013-11-14 for material sheet handling system and processing methods.
This patent application is currently assigned to CORNING INCORPORATED. The applicant listed for this patent is CORNING INCORPORATED. Invention is credited to Chester Hann Huei Chang, Michael John Moore, Michael Yoshiya Nishimoto, Chunhe Zhang.
Application Number | 20130302971 13/946490 |
Document ID | / |
Family ID | 41820232 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130302971 |
Kind Code |
A1 |
Chang; Chester Hann Huei ;
et al. |
November 14, 2013 |
MATERIAL SHEET HANDLING SYSTEM AND PROCESSING METHODS
Abstract
Methods and apparatus provide for delivering a controlled supply
of gas to at least one aero-mechanical device to impart a gas flow
to suspend a material sheet; preventing lateral movement of the
material sheet in at least one direction when suspended; and
imparting a stream of water, from a side of the material sheet
opposite the at least one aero-mechanical device, to dice the
material sheet when suspended.
Inventors: |
Chang; Chester Hann Huei;
(Painted Post, NY) ; Moore; Michael John;
(Corning, NY) ; Nishimoto; Michael Yoshiya;
(Horseheads, NY) ; Zhang; Chunhe; (Horseheads,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CORNING INCORPORATED |
CORNING |
NY |
US |
|
|
Assignee: |
CORNING INCORPORATED
CORNING
NY
|
Family ID: |
41820232 |
Appl. No.: |
13/946490 |
Filed: |
July 19, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12364183 |
Feb 2, 2009 |
8528886 |
|
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13946490 |
|
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Current U.S.
Class: |
438/460 |
Current CPC
Class: |
Y10T 83/0591 20150401;
H01L 21/67092 20130101; B28D 5/0052 20130101; B33Y 80/00 20141201;
H01L 21/67017 20130101; Y10T 83/364 20150401; H01L 21/78 20130101;
H01L 21/6838 20130101; B28D 5/0047 20130101 |
Class at
Publication: |
438/460 |
International
Class: |
H01L 21/78 20060101
H01L021/78 |
Claims
1-10. (canceled)
11. A method, comprising: delivering a controlled supply of gas to
at least one aero-mechanical device to impart a gas flow to suspend
a material sheet; preventing lateral movement of the material sheet
in at least one direction when suspended; and imparting a stream of
water, from a side of the material sheet opposite the at least one
aero-mechanical device, to dice the material sheet when
suspended.
12. The method of claim 11, wherein the material sheet is a
substantially round sheet of semiconductor material.
13. The method of claim 12, further comprising: preventing lateral
movement of the material sheet in a first direction when suspended;
and imparting streams of water to dice respective opposing lateral
pieces from the material sheet in the first direction.
14. The method of claim 13, further comprising: preventing lateral
movement of the material sheet in a second direction, transverse to
the first direction; and imparting streams of water to dice
respective further opposing lateral pieces from the material sheet
in the second direction such that the remaining material sheet is
substantially rectangular.
15. The method of claim 14, further comprising: preventing lateral
movement of the material sheet in the first direction when
suspended; and imparting streams of water to chamfer respective
opposing edges of the material sheet in the first direction.
16. The method of claim 15, further comprising: preventing lateral
movement of the material sheet in the second direction, transverse
to the first direction; and imparting streams of water to chamfer
respective further opposing lateral edges of the material sheet in
the second direction.
17. The method of claim 16, further comprising: flipping the
material sheet over; preventing lateral movement of the material
sheet in the first direction when suspended; and imparting streams
of water to chamfer respective opposing edges of the material sheet
in the first direction.
18. The method of claim 17, further comprising: preventing lateral
movement of the material sheet in the second direction, transverse
to the first direction; and imparting streams of water to chamfer
respective further opposing lateral edges of the material sheet in
the second direction.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to the manufacture and
handling of material sheets and/or structures, such as
semiconductor wafers and tiles, for use in making intermediate
structures.
[0003] 2. Technical Background
[0004] Semiconductor on insulator devices are becoming more
desirable as market demands continue to increase. SOI technology is
becoming increasingly important for high performance thin film
transistors (TFTs), solar cells, and displays, such as, active
matrix displays, organic light-emitting diode (OLED) displays,
liquid crystal displays (LCDs), integrated circuits, photovoltaic
devices, etc. SOI structures may include a thin layer of
semiconductor material, such as silicon, on an insulating
material.
[0005] Various ways of obtaining SOI structures include epitaxial
growth of silicon (Si) on lattice matched substrates, and bonding a
single crystal silicon wafer to another silicon wafer. Further
methods include ion-implantation techniques in which either
hydrogen or oxygen ions are implanted either to form a buried oxide
layer in the silicon wafer topped by Si in the case of oxygen ion
implantation or to separate (exfoliate) a thin Si layer to bond to
another Si wafer with an oxide layer as in the case of hydrogen ion
implantation.
[0006] U.S. Pat. No. 7,176,528 discloses a process that produces an
SOG (semiconductor on glass) structure. The steps include: (i)
exposing a silicon wafer surface to hydrogen ion implantation to
create a bonding surface; (ii) bringing the bonding surface of the
wafer into contact with a glass substrate; (iii) applying pressure,
temperature and voltage to the wafer and the glass substrate to
facilitate bonding therebetween; and (iv) separating the glass
substrate and a thin layer of silicon from the silicon wafer.
[0007] The above manufacturing process, as well as many other
processes for fabricating, for example SOI structures, may require
the availability of high quality semiconductor material sheets (or
wafers), such as single crystal silicon wafers. The semiconductor
wafers are usually round and, in some applications, must be
processed to achieve rectangular tiles. Semiconductor tiles are
often required to have strict dimensional tolerances, good
crystalline orientation alignment and high form accuracy such as
straightness, parallelism and perpendicularity. The semiconductor
tiles may also need to be rounded on all four corners and chamfered
to a specified profile along the four edges of each side in order
to survive ion implantation/exfoliation re-use cycles. In addition,
the semiconductor tiles must be free of contamination, foreign
particles, heat-damage, chipping, micro-cracks, and any other
subsurface damage or characteristics that would limit fracture
strength.
[0008] The traditional processes for preparation of the
semiconductor tiles employ diamond dicing, edge grinding, and
polishing of tile edges. These processes are considered to be
relatively costly because of the number of separate process steps
involved, including significant cleaning steps to ensure
contamination is minimized.
[0009] Accordingly, there is a need in the art for new methods and
apparatus for handling and processing sheet material (such as SOI
structures).
SUMMARY
[0010] An alternative approach to dicing a circular semiconductor
wafer, rounding the corners and chamfering the edges for
preparation of a semiconductor tile may employ water jet laser
dicing and chamfering. In this new technology, both dicing and
chamfering processes may be carried out on a single machine,
eliminating additional and costly cleaning steps.
[0011] One approach may include employing a conventional vacuum
chuck to hold the semiconductor wafer during the dicing, rounding
and chamfering processes. The first step may include cutting a
round semiconductor wafer into a rectangular tile using the water
jet laser with a bottom side of the semiconductor wafer held in the
vacuum chuck. The second step may include chamfering the four top
edges of the rectangular tile, again with the bottom side of the
semiconductor tile held in the vacuum chuck. Next, the
semiconductor tile is flipped over such that a top side of the
semiconductor tile is held in the vacuum chuck and the four bottom
edges are chamfered using the water jet laser. Semiconductor tiles
produced in the aforementioned way may meet the dimension and
alignment requirements and may be free of subsurface cracks. It is
possible, however, that in some applications, the physical contact
between the semiconductor wafer/tile surfaces and the vacuum chuck
may contaminate the top and bottom surfaces of the resulting
semiconductor tile, such as by introducing excessive foreign
particles. Experiments have shown that it may be difficult to
remove such particles, even via separate cleaning steps. Remnant
contamination on the surfaces of the semiconductor tile should be
avoided as such may lead to tile breakage and semiconductor-glass
bonding failure.
[0012] A class of material handling devices, known as Bernoulli
wands, has been employed for transporting semiconductor wafers.
Bernoulli wands (e.g., formed of quartz) are useful for
transporting semiconductors wafers between high temperature
chambers. The advantage provided by the Bernoulli wand is that the
hot semiconductor wafer generally does not contact the pickup wand,
except perhaps at one or more small locators positioned outside the
wafer edge on the underside of the wand, thereby minimizing contact
damage to the wafer caused by the wand.
[0013] When positioned above a semiconductor wafer, the Bernoulli
wand uses jets of gas to create a gas flow pattern above the
semiconductor wafer that causes the pressure immediately above the
semiconductor wafer to be less than the pressure immediately below
the semiconductor wafer. Consequently, the pressure imbalance
causes the semiconductor wafer to experience an upward "lift"
force. Moreover, as the semiconductor wafer is drawn upward toward
the wand, the same jets that produce the lift force produce an
increasingly larger repulsive force that prevents the semiconductor
wafer from contacting the Bernoulli wand. As a result, it is
possible to suspend the semiconductor wafer below (or above) the
wand in a substantially non-contacting manner.
[0014] Although the use of the Bernoulli wand has been helpful in
transporting relatively small sized semiconductor wafers (e.g., in
the 200-300 mm diameter range), the conventional usages of same are
not suited to handling and transport of larger structures. Indeed,
as the area of a material sheet increases, the use of conventional
Bernoulli wand technology may result in excessive warping, sagging,
etc. In addition, conventional Bernoulli wand technology may not be
suited for use with a water jet laser system as the excess water
may disturb the gas flow patterns that hold the material sheet.
Further, conventional Bernoulli wand technology does not provide
any significant lateral restraint on the material sheet. Various
aspects of the present invention however address these and other
issues in connection with dicing and chamfering a circular
semiconductor wafer for preparation of a semiconductor tile.
[0015] For ease of presentation, the following discussion will at
times be in terms of SOT structures. The references to this
particular type of SOT structure are made to facilitate the
explanation of the invention and are not intended to, and should
not be interpreted as, limiting the invention's scope in any way.
The SOI abbreviation is used herein to refer to
semiconductor-on-insulator structures in general, including, but
not limited to, silicon-on-insulator structures. Similarly, the SOI
abbreviation is used to refer to semiconductor-on-glass structures
in general, including, but not limited to, silicon-on-glass
structures (SiOG). The abbreviation SOI encompasses SiOG
structures.
[0016] In accordance with one or more embodiments of the present
invention, an apparatus includes: a base; at least one
aero-mechanical device depending from, or otherwise coupled to, or
connected to, the base and operating to impart a gas flow to a
material sheet, such that the material sheet is suspended, in
response to a controlled supply of gas; at least one retaining
clamp depending from the base and operating to prevent lateral
movement of the material sheet in at least one direction when
suspended; and a water jet source operating to provide a stream,
from a side of the material sheet opposite the at least one
aero-mechanical device, to dice and/or chamfer the material sheet
when suspended.
[0017] The at least one aero-mechanical device may include at least
one of Bernoulli chucks, air bearings, etc. A controller operates
to program the controlled supply of gas to the plurality of
Bernoulli chucks (and/or air bearings).
[0018] In accordance with a preferred dicing procedure, a dicing
process is divided into two basic phases: (i) using the water jet
laser to dice away respective left and right portions of the
material sheet (e.g., a semiconductor wafer), and (ii) holding the
resulting left and right edges of the wafer/tile and using the
water jet laser to dice away respective remaining portions of the
semiconductor wafer, thereby resulting in a rectangular tile.
[0019] In accordance with a preferred chamfering procedure, a
chamfering process is also divided into two basic phases: (i)
holding the top and bottom edges of the semiconductor tile and
using the water jet laser to chamfer respective left and right
edges of the semiconductor tile, and (ii) holding the left and
right edges of the semiconductor tile and using the water jet laser
to chamfer respective top and bottom edges of the semiconductor
tile. The semiconductor tile is then flipped over and the
chamfering process is repeated to process all eight edges.
[0020] Other aspects, features, advantages, etc. will become
apparent to one ordinarily skilled in the art when the description
of the invention herein is taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] For the purposes of illustrating the various aspects of the
invention, there are shown in the drawings forms that are presently
preferred, it being understood, however, that the invention is not
limited to the precise arrangements and instrumentalities
shown.
[0022] FIG. 1 is a perspective schematic view of an apparatus
suitable for dicing and chamfering a circular semiconductor wafer
for preparation of a semiconductor tile in accordance with one or
more embodiments of the present invention;
[0023] FIG. 2 is a perspective schematic view of an apparatus in
which a mechanism for holding the semiconductor wafer/tile includes
an array of air bearings or Bernoulli chucks and a system for
preventing lateral movement of the semiconductor wafer/tile;
[0024] FIGS. 3A and 3B illustrate a rear view and a front view,
respectively, of a Bernoulli chuck suitable for use in connection
with one or more embodiments of the present invention;
[0025] FIGS. 4-5 are perspective views of the apparatus during the
process of dicing a circular semiconductor wafer to prepare a
rectangular semiconductor tile;
[0026] FIGS. 6-7 are perspective views of the apparatus during the
process of chamfering respective edges of the semiconductor
tile;
[0027] FIG. 8 is a cross-sectional view through a Bernoulli chuck
employing an alternative fluid drainage feature;
[0028] FIG. 9 is a side schematic view of a mechanism for
deploying, retracting and translating lateral retention elements
that prevent lateral movement of the semiconductor wafer/tile;
[0029] FIG. 10 is a block diagram of a control system suitable for
implementing one or more embodiments of the present invention;
[0030] FIG. 11 is a top view of an alternative disengagement
feature that may be integrated with the Bernoulli chuck of FIGS.
3A, 3B; and
[0031] FIG. 12 is a graph illustrating test results as to a level
of contamination on a surface of a semiconductor wafer resulting
from a process of holding the semiconductor wafer in an apparatus
of the present invention.
DETAILED DESCRIPTION
[0032] With reference to the drawings, wherein like numerals
indicate like elements, there is shown in FIG. 1 an apparatus 100
for dicing and chamfering a non-rectangular (e.g., circular)
material sheet, such as a semiconductor wafer 10 for preparation of
a semiconductor tile. The apparatus 100 includes a base 102 and at
least one aero-mechanical device 104 depending from the base 102
and operating to impart a gas flow to the semiconductor wafer 10,
such that the semiconductor wafer 10 is suspended, in response to a
controlled supply of gas. One or more retaining clamps 106 depend
from the base 102 (or other intermediate structure) and operate to
prevent lateral movement of the semiconductor wafer 10 in at least
one direction when suspended. A water jet source 110 operates to
provide a stream, from a side of the semiconductor wafer opposite
to the aero-mechanical device 104, to dice and/or chamfer the
semiconductor wafer 10 when suspended.
[0033] As illustrated in FIG. 2, in one or more embodiments, the at
least one aero-mechanical device 104 includes one or more air
bearings, which are operable to provide a cushion of air (or other
gas) under the semiconductor wafer 10 in order to suspended same
within the apparatus 100. Such air bearings may be obtained
commercially, for example from New Way Air Bearings, Aston, Pa.,
USA. In one or more alternative embodiments, the at least one
aero-mechanical device 104 includes at least one Bernoulli chuck,
and preferably a plurality of Bernoulli chucks. Suitable Bernoulli
chucks for implementing a practical device may be obtained
commercially from Solar Research Laboratory, Toyonaka-city, Osaka,
Japan.
[0034] With reference to FIGS. 3A and 3B, top and bottom views of a
suitable Bernoulli chuck 150 are illustrated in perspective. Each
Bernoulli chuck 150 is operable to create a repelling and/or
attracting force to the semiconductor wafer 10, depending on its
relative normal position, in response to a controlled supply of gas
thereto. In the case of holding a relatively small semiconductor
wafer 10, relatively few Bernoulli chucks 150 are needed. For
relatively larger semiconductor wafers 10, a larger number of
Bernoulli chucks 150 are needed to ensure that warping, sagging,
and/or breakage is avoided. Each Bernoulli chuck 150 includes one
or more gas inlets 154, optionally one or more gas outlets
(exhaust) 156, and optionally one or more annular gas flow
apertures 158. When positioned below the semiconductor wafer 10,
the Bernoulli chuck 150 establishes a stream of gas to create a gas
flow pattern below the semiconductor wafer 10 that causes the
pressure immediately below the semiconductor wafer 10 to be higher
than the pressure immediately above semiconductor wafer 10. The
pressure imbalance causes the semiconductor wafer 10 to experience
an upward "lift" force. The one or more Bernoulli chucks 150 are
operable to permit the semiconductor wafer 10 to be oriented
horizontally, vertically, and/or orientations therebetween. In the
illustrated embodiments, the semiconductor wafer 10 is in a
generally horizontal orientation. The structure and control of the
Bernoulli chucks 150 may be established such that any desired or
required holding distance and holding force within the operating
range of chuck can be achieved.
[0035] With reference to FIGS. 4-5, the apparatus 100, may be used
to hold the semiconductor wafer 10 and dice the edges thereof to
produce a rectangular tile. In this regard, the aeromechanical
device 104 (whether of Bernoulli chucks, air bearings, or other
mechanisms) is activated to create a gas flow that is suitable for
suspending and/or holding the semiconductor wafer 10 in a
non-contact fashion. In this example, the number of Bernoulli
chucks or air bearings are arranged such that about six such
devices support an inside portion of the semiconductor wafer 10
(which will become the tile) and about another four devices are
deployed around a peripheral edge of the semiconductor wafer 10 to
support a scrap part of the wafer 10 which will be cut away during
the dicing process.
[0036] In accordance with a preferred dicing procedure, the dicing
process is divided into two basic phases: (i) using the water jet
laser 110 to dice away respective left and right portions of the
semiconductor wafer 10, and (ii) holding the resulting left and
right edges of the wafer/tile 10 and using the water jet laser 110
to dice away respective remaining portions of the semiconductor
wafer 10, thereby resulting in a rectangular tile.
[0037] In the first phase, the retaining clamps 106 (in this case
four such clamps 106-1, 106-2, 106-3, 106-4) engage edges of the
semiconductor wafer 10 to prevent lateral movement thereof in at
least one first direction (e.g., along a Y axis as labeled) when
suspended. Notably, the retaining clamps 106 do not engage either
of two spaced apart major surfaces of the semiconductor wafer 10.
While the illustrated clamps 106 are in the shape of respective
pins, pairs of linear contact blocks may be employed, or other
mechanical configurations. As will be discussed later herein, the
retaining clamps 106 may be actuated by mechanical, pneumatic, or
other automated drives to achieve the desired position about the
semiconductor wafer 10. In addition, the clamping force is
controlled to a required magnitude such as not to cause any
deformation of or damage to the edge of the wafer 10 and/or the
later resulting tile.
[0038] The water jet source 110 produces a beam 112 (stream of
water), from a side of the semiconductor wafer 10 opposite to the
aero-mechanical device 104, to dice the semiconductor wafer 10
along the illustrated dotted lines in the Y direction. Notably, the
retaining clamps 106 engage edges of the semiconductor wafer 10
that prevent lateral movement that would otherwise result from the
impact of the beam 112 or other forces that would destroy the tight
tolerances desired during the dicing process. During the dicing
step, it may be advantageous to employ grippers (not shown) to
prevent the scrap portion from colliding with and damaging the edge
of the wafer/tile 10.
[0039] In the second phase of the dicing process, a further set of
retaining clamps 106 (in this case four such clamps 106-5, 106-6,
106-7, 106-8) engage newly formed straight edges 12, 14 of the
semiconductor wafer 10 and the retaining clamps 106-1, 106-2,
106-3, 106-4 may be retracted (e.g., into the base 102). The clamps
106-5, 106-6, 106-7, 106-8) prevent lateral movement of the
semiconductor wafer 10 in at least one second direction (e.g.,
along an X axis as labeled, transverse to the Y axis). Again, the
retaining clamps 106 do not engage either of two spaced apart major
surfaces of the semiconductor wafer 10. The water jet source 110
produces the beam 112 to dice the semiconductor wafer 10 along the
illustrated dotted lines in the X direction, resulting in a
rectangular semiconductor
[0040] With reference to FIGS. 6-7, in accordance with a preferred
chamfering procedure, the chamfering process is also divided into
two basic phases: (i) holding the top and bottom edges 16, 18 of
the semiconductor tile 10A and using the water jet laser 110 to
chamfer respective left and right edges 12, 14 of the semiconductor
tile 10A, and (ii) holding the left and right edges 12, 14 of the
semiconductor tile 10A and using the water jet laser 110 to chamfer
respective top and bottom edges 16, 18 of the semiconductor tile
10A.
[0041] In the first phase of the chamfering process, the retaining
clamps 106-1, 106-2, 106-3, 106-4 engage the straight edges 16, 18
of the semiconductor tile 10A, and prevent lateral movement of the
semiconductor tile 10A in the first direction (e.g., along a Y
axis) and in the second direction (e.g., along an X axis). The
retaining clamps may simultaneously prevent movement of the
semiconductor tile 10A in a direction normal to the plane of the
tile (e.g., along a Z axis). Again, the retaining clamps 106 do not
engage either of two spaced apart major surfaces of the
semiconductor tile 10A. The water jet source 110 produces the beam
112 to chamfer the left and right edges 12, 14 of the semiconductor
tile 10A.
[0042] In the second phase of the chamfering process, the second
set of clamps 106-5, 106-6, 106-7, 106-8 engage the straight edges
12, 14 of the semiconductor tile 10A and prevent lateral movement
of the semiconductor tile 10A in the second direction (e.g., along
an X axis) and in the first direction (e.g., along a Y axis), then
the retaining clamps 106-1, 106-2, 106-3, 106-4 are retracted. The
water jet source 110 then produces the beam 112 to chamfer the top
and bottom edges 16, 18 of the semiconductor tile 10A.
[0043] The semiconductor tile 10A may then be flipped over and the
two phase chamfering process described above may be repeated to
chamfer the other edges.
[0044] With reference to FIG. 8, the use of the water jet laser
source 110 presents special challenges in connection with managing
run-off of the water that may accumulate in parts of the apparatus
100. For example, when one or more Bernoulli chucks 150 are
employed to implement the aero-mechanical device 104, water may
accumulate in an upwardly directed cup 180 thereof. In this regard,
the Bernoulli chuck 150 may include one or more drainage ports 182
that operate to permit the run-off water to exit the cup 180 of the
chuck 150. Note these ports must be closed during operation of the
Bernoulli chuck so as to not disturb the airflow pattern required
for desired operation.
[0045] In an alternative arrangement, when the aero-mechanical
device 104 includes a plurality of Bernoulli chucks 150, the chucks
150 may repel and/or attract the semiconductor wafer 10. This
permits non-horizontal (transverse) orientations of the
semiconductor wafer 10 during dicing and/or chamfering. One such
orientation is a completely vertical orientation, where the water
jet source 110 operates to impart the stream substantially
horizontally to the semiconductor wafer 10. This configuration (as
well as other transverse configurations) would permit the run-off
water to naturally drain from the apparatus 100 by way of
gravity.
[0046] With reference to FIG. 9, and as discussed above, the
retaining clamps 106 may be actuated by mechanical, pneumatic, or
other automated drives 120 to achieve the desired position about
the semiconductor wafer 10. The drive 120 is preferably located
within the base 102 and includes a void, which the clamp may be
retracted (partially or entirely) into, and deployed from, in the Z
direction as indicated by the arrow. In addition, the drive 120
operates to permit the retaining clamp 106 to be laterally
adjustable such that various sizes of semiconductor wafers 10 and
the changing lateral dimensions thereof due to dicing, etc. may be
accommodated. In addition, the clamping force is controlled to a
required magnitude such as not to cause any deformation of the
wafer 10 and/or the later resulting tile. The clamping force is
also controlled such as not to cause any damage to the edge of the
wafer 10 and/or the resulting tile. Those skilled in the art will
appreciate the various specific ways that such drives may be
implemented using mechanical, pneumatic, and/or other
manual/automated mechanisms.
[0047] With reference to FIG. 10, the apparatus 100 may further
include one or more of: a controller 160, a gas pressure and flow
regulator 162 for receiving and regulating a flow of gas 163 from
source of gas (not shown), and a 1.times.N manifold 166. The
controller 160 is operable to program one or more elements of the
apparatus 100. The controller 160 may be implemented using suitable
microprocessor systems, or using any of the known, or hereinafter
developed, technology. For example, the controller 160 may be
coupled to the gas pressure and flow regulator 162. The gas
pressure and flow regulator 162 is operable to respond to
electrical commands from the controller 160 by providing a
controlled supply of gas to the aero-mechanical device 104 (such as
the one or more Bernoulli chucks 150, air bearings, etc.). The gas
pressure and flow regulator 162 may be implemented using any of the
known, or hereinafter developed, technologies. The 1.times.N
manifold 166 may be employed to direct the source of gas to the
aero-mechanical device 104. Thus, in one example, when working with
a semiconductor wafer 10 of significant size, a number (N) of
Bernoulli chuck(s) 150 and/or air bearings may be required. Then
the 1.times.N manifold 166 would provide gas to each of the N
Bernoulli chucks, etc. Preferably, more than one 1.times.N manifold
166 would provide gas to groups of Bernoulli chucks, etc. The
controller 160 may also be operable to provide control signals to
the drives 120 in order to achieve the aforementioned retraction,
deployment and translational functionality.
[0048] An alternative or additional feature may be employed by the
apparatus 100, for example, at least one gas jet 170 located
proximate to a junction of the semiconductor wafer 10 and the
aero-mechanical device 104. The one or more gas jets 170 are
operable to impart a stream of gas to the semiconductor wafer 10 to
promote removal or disengagement thereof from the aero-mechanical
device 104. This has particular use when the aero-mechanical device
104 is implemented by way of one or more Bernoulli chucks 150, in
order to break the attractive force imparted by the chucks 150 on
the semiconductor wafer 10. In such an embodiment, the 1.times.N
manifold 166 may be employed to direct the source of gas to the one
or more Bernoulli chuck(s) 150 and to the one or more gas jets 170.
The provision of gas to the one or more gas jets 170 may also be
facilitated by way of the controller 160 programming the 1.times.N
manifold 166. In this arrangement, the 1.times.N manifold can
separately control the gas flow to each of its N outputs. This
additional feature also facilitates loading a wafer 10 into the
apparatus 100 by adding to the suspension force.
[0049] In an alternative embodiment, the function of the at least
one gas jet 170 may be accomplished using a low-speed gas flow
emanating from a porous medium and/or a repelling magnetic
field.
[0050] With reference to FIG. 11, one or more of the Bernoulli
chucks 150 may be provided with air blowing holes 184 arranged
around a periphery thereof. The air blowing holes 184 are operable
to provide air flow before the Bernoulli chuck 150 is deactivated,
such that the risk of physical contact between the semiconductor
wafer 10 and the chuck 150 is avoided during the release of the
wafer 10 or the tile 10A. Air provided in this manner also reduces
the risk of physical contact between the semiconductor wafer 10 or
the tile 10A during loading of the semiconductor wafer 10 or the
tile 10A into apparatus 100.
[0051] Advantages of one or more aspects of the invention include:
(i) that the apparatus 100 can eliminate the physical contact
between the surface of the semiconductor wafers 10 or tiles 10A and
the holding mechanism, such as a Bernoulli chuck, and avoid
contact-related damage, contamination, and particles; (ii) that the
method of water jet laser dicing and chamfering rectangular silicon
tiles produce, e.g., silicon tiles, which not only meet dimension,
form, alignment requirements, but also satisfy tile cleanliness
requirements; and (iii) that the non-contact holding apparatus and
the method of tile production enable double-sided chamfering with
attendant double-sided cleanliness. Thus, various aspects of the
invention may reduce and possibly eliminate the need for cleaning
after tile dicing and chamfering.
[0052] With reference to FIG. 12, experimentation was carried out
in accordance with one or more aspects of the present invention. A
prototype apparatus employing a non-contact air bearing chuck was
constructed in accordance with clean-room requirements. The chuck
itself included a porous plastic (Porex.TM. X-5085) disk located in
a housing made of Waterclear.TM. resin by stereolithography. The
chuck body was formed using a round 58 mm diameter air bearing to
support a 100 mm silicon wafer. The prototype included four stop
pillars to prevent lateral movement of the wafer during test.
Elevation tests were conducted with using a highly filtered
nitrogen source at flow rates of about 1.4 cfm at less than 2 psi,
such that a clean gap was visible between the wafer and the chuck.
Candela CS-10 (KLA-Tencor, California, USA) was used to compare the
cleanliness of the wafer before and after respective five minute
elevation cycles. An SSEC ML3400 (Solid State Equipment
Corporation, PA, USA) was used to clean the wafer with a mild
recipe (only ozone and dilute SCI). The Candela CS-10 was used
again to inspect for cleanliness after the SSEC cleaning cycle.
[0053] In one test cycle (not shown in FIG. 12) an arc of dots
(which indicated contamination) in the upper left quadrant of the
scan was visible after an elevation cycle but before cleaning. The
circular shape of the arc appeared to be of similar diameter to the
chuck. While the operator attempted to place the wafer onto the
chuck without touching, there may have been slight contact between
the chuck and wafer during unloading. Thus, this one test cycle was
believed to be an anomaly. The result of the test cycle illustrated
in FIG. 12 was indicative of numerous other test cycles and is
believed to represent the capabilities of the apparatus 100. The
result clearly shows that the non-contact chuck produces a
relatively low level of chuck-induced contamination. A comparison
of the wafer particle counts before and after interaction with the
chuck shows that few particles were added to the wafers as a result
of elevation using the chuck. In addition, after a rather mild
cleaning, the particle map of the wafers appeared to be very
similar to those of the original states of the wafers.
[0054] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
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