U.S. patent application number 15/820907 was filed with the patent office on 2018-04-05 for substrate attachment for attaching a substrate thereto.
This patent application is currently assigned to EV Group E. Thallner GmbH. The applicant listed for this patent is EV Group E. Thallner GmbH. Invention is credited to Andreas Fehkuhrer.
Application Number | 20180096962 15/820907 |
Document ID | / |
Family ID | 52282714 |
Filed Date | 2018-04-05 |
United States Patent
Application |
20180096962 |
Kind Code |
A1 |
Fehkuhrer; Andreas |
April 5, 2018 |
SUBSTRATE ATTACHMENT FOR ATTACHING A SUBSTRATE THERETO
Abstract
A method for bonding a first substrate with a second substrate,
characterized in that the first substrate and/or the second
substrate is/are thinned before the bonding.
Inventors: |
Fehkuhrer; Andreas;
(Senftenbach, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EV Group E. Thallner GmbH |
St.Florian am Inn |
|
AT |
|
|
Assignee: |
EV Group E. Thallner GmbH
St. Florian am Inn
AT
|
Family ID: |
52282714 |
Appl. No.: |
15/820907 |
Filed: |
November 22, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14917318 |
Mar 8, 2016 |
9859246 |
|
|
PCT/EP2014/078585 |
Dec 18, 2014 |
|
|
|
15820907 |
|
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 24/74 20130101;
H01L 2224/94 20130101; H01L 23/544 20130101; H01L 2224/0381
20130101; H01L 2224/80099 20130101; H01L 2224/80 20130101; H01L
24/80 20130101; H01L 2224/74 20130101; H01L 2224/80006 20130101;
H01L 24/94 20130101; H01L 2224/75704 20130101; H01L 21/6836
20130101; H01L 2224/80093 20130101; H01L 2224/80907 20130101; H01L
21/304 20130101; H01L 2224/75735 20130101; H01L 2224/92 20130101;
B32B 2457/14 20130101; H01L 2224/0224 20130101; H01L 2224/0382
20130101; H01L 2224/03831 20130101; H01L 2221/68381 20130101; H01L
21/67092 20130101; H01L 2224/75725 20130101; H01L 2224/8013
20130101; H01L 24/95 20130101; H01L 2223/54426 20130101; H01L
2225/06565 20130101; B32B 2309/105 20130101; H01L 2224/08121
20130101; H01L 2221/68368 20130101; H01L 2221/68327 20130101; H01L
2223/54453 20130101; H01L 2224/75701 20130101; H01L 25/0657
20130101; H01L 21/78 20130101; H01L 24/08 20130101; H01L 24/97
20130101; H01L 2224/7598 20130101; H01L 25/50 20130101; H01L
2224/0384 20130101; H01L 2224/08145 20130101; H01L 2224/75734
20130101; H01L 2224/8002 20130101; H01L 21/6831 20130101; H01L
2224/80003 20130101; H01L 2224/80132 20130101; H01L 2224/80047
20130101; H01L 24/75 20130101; H01L 2224/80201 20130101; H01L
2224/97 20130101; B32B 38/1841 20130101; H01L 2224/75744 20130101;
H01L 2224/75272 20130101; H01L 2224/80801 20130101; H01L 2224/80894
20130101; H01L 2224/80213 20130101; H01L 2224/80203 20130101; H01L
2224/75705 20130101; H01L 2224/8001 20130101; H01L 21/187 20130101;
H01L 2224/75724 20130101; H01L 2224/80011 20130101; H01L 2224/80051
20130101; H01L 2224/95 20130101; H01L 2224/75702 20130101; H01L
2224/80209 20130101; B32B 37/0046 20130101; B32B 38/1858 20130101;
H01L 2221/68363 20130101; H01L 2224/75251 20130101; H01L 21/6835
20130101; H01L 2224/75745 20130101; H01L 2224/94 20130101; H01L
2224/80 20130101; H01L 2224/95 20130101; H01L 2224/80 20130101;
H01L 2224/97 20130101; H01L 2224/80 20130101; H01L 2224/74
20130101; H01L 2224/80 20130101; H01L 2224/80894 20130101; H01L
2924/00014 20130101; H01L 2224/80801 20130101; H01L 2924/00014
20130101; H01L 2224/80003 20130101; H01L 2924/00012 20130101; H01L
2224/80047 20130101; H01L 2924/00014 20130101; H01L 2224/80011
20130101; H01L 2924/00014 20130101; H01L 2224/8001 20130101; H01L
2924/00014 20130101; H01L 2224/0382 20130101; H01L 2924/00014
20130101; H01L 2224/0384 20130101; H01L 2924/00014 20130101; H01L
2224/03831 20130101; H01L 2924/00014 20130101; H01L 2224/92
20130101; H01L 21/78 20130101; H01L 21/304 20130101; H01L 2224/80
20130101; H01L 2224/92 20130101; H01L 21/78 20130101; H01L
2221/68304 20130101; H01L 21/304 20130101; H01L 2224/80 20130101;
H01L 2224/92 20130101; H01L 21/78 20130101; H01L 2221/68304
20130101; H01L 21/304 20130101; H01L 2224/80 20130101; H01L
2221/68381 20130101; H01L 2224/80201 20130101; H01L 2924/00012
20130101; H01L 2224/80203 20130101; H01L 2924/00012 20130101 |
International
Class: |
H01L 23/00 20060101
H01L023/00; H01L 25/00 20060101 H01L025/00; B32B 37/00 20060101
B32B037/00; H01L 23/544 20060101 H01L023/544; H01L 21/683 20060101
H01L021/683; H01L 21/67 20060101 H01L021/67; H01L 21/304 20060101
H01L021/304; H01L 21/18 20060101 H01L021/18; B32B 38/18 20060101
B32B038/18; H01L 25/065 20060101 H01L025/065 |
Claims
1. A substrate attachment for fixing a substrate thereto,
comprising: a plate having a surface with attaching elements
integrated therein, the plate being configured to elastically
deform in response to a load applied to the surface of the plate,
the attaching elements being configured to fix the substrate to the
surface of the plate.
2. The substrate attachment according to claim 1, wherein the plate
is rigid in a state in which the plate is not supported.
3. The substrate attachment according to claim 1, wherein the
attaching elements comprise vacuum strips.
4. The substrate attachment according to claim 1, wherein the plate
comprises a vacuum valve disposed therein, the vacuum valve being
configured to maintain a vacuum within the attaching elements to
fix the substrate to the surface of the plate.
5. The substrate attachment according to claim 1, further
comprising: a control unit configured to control the attaching
elements to fix the substrate to the surface of the plate.
6. The substrate attachment according to claim 5, wherein the
control unit comprises a valve configured to maintain a vacuum
within the attaching elements to fix the substrate to the surface
of the plate.
7. The substrate attachment according to claim 5, wherein the
control unit comprises a feed line for electric current to control
the attaching elements to fix the substrate to the surface of the
plate.
8. The substrate attachment according to claim 7, wherein the
attaching elements are electrostatic elements, and wherein the feed
line for electric current is configured to control the
electrostatic elements to fix the substrate to the surface of the
plate.
9. The substrate attachment according to claim 7, wherein the
attaching elements are magnetic elements, and wherein the feed line
for electric current is configured to control the magnetic elements
to fix the substrate to the surface of the plate.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/917,318, filed Mar. 8, 2016, which is a U.S. National Stage
Application of PCT/EP2014/078585 filed Dec. 18, 2014, said patent
applications herein fully incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to a substrate attachment for
attaching a substrate thereto
BACKGROUND OF THE INVENTION
[0003] In the semiconductor industry, substrates are connected to
one another permanently or temporarily by so-called bonding
processes.
[0004] By a bonding process, for example, substrates with different
functional units, for example substrates with memory chips and
microcontrollers, can be stacked on top of one another. A substrate
stack with more complex properties is obtained by the stacking and
permanent attachment of multiple substrates with different
properties. The thus produced substrate stacks have a thickness of
a few hundred micrometers.
[0005] The bonding technology, however, can also be used for
temporary attachment of a substrate and/or a substrate stack. In
this case, a product substrate is attached under pressure and/or
temperature by means of an adhesive to a carrier substrate. After
the processing of the product substrate, the product substrate is
detached again from the carrier substrate.
[0006] The greatest problem in the state of the art consists in the
alignment and the permanent attachment of multiple extremely thin
substrates. The stacking of such thin substrates produces a
substrate stack, a so-called "multi-stack." In order to avoid the
difficult and cumbersome handling of thin substrates, the alignment
and bonding process is performed on substrates with a defined
standard thickness. After a second substrate is bonded to a first
substrate, the back-thinning of the second substrate is carried
out. By the back-thinning process, a thin substrate is produced
from a formerly thick substrate. Optionally, another, third, thick
substrate, whose thickness is reduced in another back-thinning
process, is to be bonded on this second, back-thinned substrate.
Substrate stacks of any functionality can thus be produced by the
process that theoretically can be repeated often at will.
[0007] One technical problem is that a permanent bond cannot be
reversed, so that in the case of a misalignment and/or damage, the
entire substrate stack constructed up to that point is unusable. A
substrate stack that is comprised of multiple substrates can be
worth tens of thousands of Euros.
SUMMARY OF THE INVENTION
[0008] This invention is based on the object of providing a method
that at least partially, preferably predominantly, solves the
above-mentioned problems. In addition, an object of this invention
includes making possible a production of bonds that is economical
and in particular as scrap-free as possible.
[0009] This object is achieved with the features of the independent
claim(s). Advantageous further developments of the invention are
indicated in the subclaims. Falling within the scope of the
invention are also all combinations of at least two of the features
indicated in the specification, the claims, and/or the figures. In
the indicated ranges of values, values as boundary values that lie
within the above-mentioned limits are also to be disclosed and can
be claimed in any combination.
[0010] The basic idea of this invention is to back-thin at least
one, and preferably all, of the substrates to be bonded, in a
departure from the previous practice, before the, in particular
permanent, bonding.
[0011] The invention thus relates in particular to a method for
bonding already thinned substrates. In this case, the invention is
preferably based on the idea of attaching--and in this state
transporting, aligning and bonding-thinned substrates, preferably
wafers, to a carrier, in particular a film, which was stretched on
a frame (substrate attachment). The substrate is therefore thinned
preferably to its intended thickness during transport, and/or
alignment, and/or the bonding process. In special embodiments
according to the invention, thick substrates are attached to the
carrier and are back-thinned only immediately before the alignment
(preferred) or immediately before the bonding, so that a transport
of thicker substrates is also possible over a certain distance.
Hereinafter, for the sake of simplicity, it is assumed that the
substrates are already thinned at all times, unless another state
is explicitly described.
[0012] In a preferred embodiment, a thinned substrate can be bonded
to a substrate that is not thinned or--even more preferably--to a
substrate stack. For even better avoidance of scrap-containing
substrate stacks, only thinned substrates according to the
invention can be bonded to one another.
[0013] According to an advantageous embodiment of the invention,
the first substrate and/or the second substrate is/are thinned to a
thickness of less than 1,000 .mu.m, in particular less than 500
.mu.m, preferably less than 100 .mu.m, even more preferably less
than 50 .mu.m, and most preferably less than 30 .mu.m.
[0014] In further development of this invention, it is provided
that the first substrate and/or the second substrate for thinning
and/or bonding is/are attached on a carrier surface of a carrier
that has in particular a ring-shaped frame. In particular, when
using the same carrier for thinning and bonding, an exchange of the
carrier can be eliminated, so that the thin substrate always has a
support, and thus wastage, in particular after thinning, is
prevented.
[0015] Advantageously, according to an embodiment of this
invention, it is provided that the first substrate and/or the
second substrate is/are preferably completely congruent in shape,
in particular at least in relation to a cross-sectional surface of
the first substrate and/or the second substrate in each case
parallel to a bonding surface, and/or have similar geometric
dimensions. In particular, this invention is applied as a
wafer-to-wafer (W2W) method, leading to advantages in terms of
processing speed and throughput.
[0016] To the extent that the first substrate and the second
substrate are aligned with one another and then are pre-attached,
in particular magnetically, before the bonding based on
corresponding alignment markings of the substrates, in particular
with an alignment accuracy of better than 100 .mu.m, preferably
better than 50 .mu.m, even more preferably better than 1 .mu.m,
most preferably better than 500 nm, and all the more preferably
better than 200 nm, influences on the alignment of the carriers on
one another can be virtually eliminated.
[0017] It would also be conceivable, however, that multiple small
second substrates are arranged, in particular regularly, on a
carrier, and in particular were also back-thinned in order to bond
simultaneously to a first substrate. As a result, a die-to-wafer
(D2W) method according to the invention is obtained, whereby the
small substrates, following the nomenclature in the semiconductor
industry, are referred to as chips (or die), although they do not
necessarily have to be chips, i.e., they do not necessarily have to
have an electrical functionality. The small substrates are
back-thinned according to the invention, in particular before
bonding.
[0018] In a special third embodiment according to the invention,
even the simultaneous bonding of multiple small substrates to
multiple small substrates would be possible, which would correspond
to a chip-to-chip (C2C) method. The small substrates are
back-thinned according to the invention in particular before the
bonding.
[0019] Hereinafter, for the sake of simplicity, reference is to be
made exclusively to two large substrates that are in particular
congruent in shape and that are handled according to the
invention.
[0020] Advantageously, thinned substrates according to the
invention can be bonded directly. Even more preferably, one or more
of the subsequent treatment steps is/are performed before transport
and/or before alignment and/or before bonding:
[0021] Grinding, and/or
[0022] Polishing, and/or
[0023] Etching, and/or
[0024] Separating (English: dicing)
[0025] Cleaning
[0026] Coating, in particular by [0027] Physical methods, in
particular [0028] PVD [0029] Chemical methods, in particular [0030]
CVD, PE-CVD
[0031] Functionalizing, provided in particular with electronic
structures, and/or in particular [0032] Enameling [0033]
Lithography [0034] Embossing [0035] Developing
[0036] Testing.
[0037] Only intact (i.e., tested after the above-mentioned steps)
thinned substrates are preferably part of a new substrate stack
that is to be bonded. Thinned substrates that have defects, in
particular functionalized, thinned substrates, in which a
predominant part or even all functional units do not function, can
be removed from the process chain. As a result, the probability
that the entire substrate stack is destroyed is drastically
reduced. By the process according to the invention, the destruction
of the substrate stack can be carried out henceforth only in the
alignment and/or bonding step. These two steps, however, are also
used in the state of the art in order to produce substrate stacks
and therefore do not represent any additional process steps after
the bonding.
[0038] According to the invention, in particular a substrate
attachment is provided, which is thus designed to attach a thinned
substrate in particular to a carrier of the substrate
attachment.
Types of Substrates
[0039] According to the invention, all standard types of substrates
are suitable, in particular wafers. The substrates can have any
shape, but are preferably circular. The diameter of the substrates
is in particular industrially standardized. For wafers, the
industry-standard diameters are 1 inch, 2 inches, 3 inches, 4
inches, 5 inches, 6 inches, 8 inches, 12 inches and 18 inches. The
method according to the invention could also be especially
advantageous for processing rectangular substrates, in particular
glass or sapphire substrates.
[0040] The substrates can be semiconductor substrates, metal
substrates, ceramic substrates, mineral substrates, in particular
sapphire substrates, glass substrates or polymer substrates. In the
case of ceramic or mineral substrates, preferably sapphire
substrates are used.
[0041] According to the invention, the attachment of thinned
substrates or the attachment of substrate stacks, which are built
up from multiple thinned substrates that are already aligned with
one another and bonded to one another, is possible. Hereinafter,
therefore, substrate is also understood to be a synonym for
substrate stack.
Substrate Attachment
[0042] In a further development of the invention, the substrate
attachment includes a frame and an elastic film (or tape) that is
stretched over the frame as a carrier.
[0043] The film forms in particular an adhesive substrate attaching
surface, to which the substrate can be attached. The film
represents an attaching element. The frame forms a carrier
attaching surface (carrier attaching area), which in particular
acts magnetically, for attaching the substrate attachment to a
second, in particular corresponding, substrate attachment.
[0044] In a first preferred embodiment, the substrate attachments
can therefore be attached to one another magnetically. The frame is
therefore preferably magnetic or magnetizable. The magnetic flux
density of the frame is in particular greater than 10.sup.-5 T,
preferably greater than 10.sup.-4 T, even more preferably greater
than 10.sup.-3 T, most preferably greater than 10.sup.-1 T, and all
the more preferably greater than 1 T.
[0045] Advantageously, the pressure that is produced on the contact
surfaces of the substrates by two frames that adhere magnetically
to one another is greater than 10.sup.-5 N/m.sup.2, preferably
greater than 10.sup.-3 N/m.sup.2, even more preferably greater than
1 N/m.sup.2, most preferably greater than 10.sup.1 N/m.sup.2, and
all the more preferably greater than 10.sup.3 N/m.sup.2.
[0046] In a second embodiment according to the invention, the
substrate attachments, in particular from the outer side, can be
attached to one another via clamps.
[0047] In a third embodiment according to the invention, the
substrate attachments can be attached to one another via a plug-in
system. The plug-in system is preferably expanded so that plug-in
elements and recesses, which serve to receive the plug-in elements
of the opposite substrate attachment, alternate along a periphery
in its entirety.
[0048] In a fourth embodiment according to the invention, the
substrate attachments can be attached to one another
electrostatically. In this case, corresponding plates, which can be
brought to an electrical potential, are located distributed
uniformly along the substrate attachment. The plates are preferably
electrically insulated by the remaining substrate attachment.
[0049] In a further development of the invention, the substrate
attachment has a solid base element with in particular controllable
attaching elements for attaching the substrate to a flat substrate
attaching surface of the base element. In addition, the substrate
attachments can be attached below one another according to the
above-described embodiments according to the invention.
[0050] In a further development, the substrate attachments can be
attached to one another magnetically. The base element is therefore
in particular magnetic or magnetizable on its substrate attaching
surface. The magnetic flux density of the base element, in
particular in the carrier attaching area, is in particular greater
than 10.sup.-5 T, preferably greater than 10.sup.4 T, even more
preferably greater than 10.sup.-3 T, most preferably greater than
10.sup.-1 T, and all the more preferably greater than 1 T.
[0051] Advantageously, the pressure that is produced on the contact
surfaces of the substrates by two substrate attachments that adhere
magnetically to one another is greater than 10.sup.-5 N/m.sup.2,
preferably greater than 10.sup.-3 N/m.sup.2, even more preferably
greater than 1 N/m.sup.2, most preferably greater than 10.sup.3
N/m.sup.2, and all the more preferably greater than 10.sup.3
N/m.sup.2.
[0052] The attaching, in particular magnetic, properties of the
base element, frame and/or substrate attachment for adhesion
between two related base elements, frame and/or substrate
attachment, in particular on the carrier attaching surface or a
carrier attaching area, are preferably independent of the attaching
properties, mentioned below, of the attaching elements for
attaching substrates.
[0053] According to a first embodiment according to the invention,
the attaching element is at least an adhesive surface. The adhesive
surface is preferably switchable electrically and/or magnetically,
so that it is possible to alternate between a state of high
adhesion and a state of low adhesion, in particular by means of a
control system.
[0054] In a second embodiment according to the invention, the
attachment element is at least one vacuum attachment to the
substrate attaching surface. The vacuum attachment preferably
includes multiple vacuum feed lines, which run through the carrier
surface. The vacuum feed lines are preferably connected to a vacuum
chamber located in the substrate attachment or in the carrier. The
vacuum chamber can be sealed via a feed line, which can be
separated from the surrounding area in a fluid-dynamic manner via a
valve, preferably by a control system. As a result, it is possible
according to the invention to attach in particular a back-thinned
substrate to the carrier surface by applying a vacuum and to close
the valve during the evacuation process. As a result, a permanent
underpressure is produced in the vacuum feed lines and the vacuum
chamber. The normal pressure that acts from outside thus represents
an overpressure relative to the underpressure area in the carrier,
and the substrate thus attaches to the carrier.
[0055] In a third embodiment according to the invention, the
attaching element is at least an electrostatic attachment. The
electrostatic attachment is comprised in particular of multiple
specially formed electrodes that are aligned and oriented to one
another, on which a defined potential can be set by an electric
line. In the electrically conductive areas of a substrate that is
to be attached, a separation of charge, in particular an electric
induction, can be produced by the generated separation of charge,
which induction results in an electrostatic attraction between the
carrier on the substrate attaching surface and the substrate. This
can be controlled in particular by a control system.
[0056] In a fourth embodiment according to the invention, the
attachment element is at least a magnetic attachment. The magnetic
attachment is preferably switchable and is distinguished from the
in particular permanent magnetization of the base element. The
switchable magnetic attachment is preferably magnetic coils, which
build up a magnetic field by a current flux for attaching the
substrate to the substrate attaching surface. Accordingly, the
substrate that is to be attached has at least partial magnetic
properties.
[0057] In the case of a fifth embodiment according to the
invention, the attaching element is at least a mechanical
attachment. The mechanical attachment is comprised in particular of
clamping elements. The clamping elements attach the substrate along
the substrate surface that is to be bonded. The clamping elements
can remain in the attaching position during the alignment process
according to the invention and even also when the two substrates
are being moved toward one another. The clamping elements can then
be removed shortly before, during or even after the substrates make
contact.
[0058] The substrate attachments thus preferably have a substrate
attaching surface and a carrier attaching surface (or carrier
attaching area) that surrounds the substrate attaching surface.
[0059] The substrate can be back-thinned before and/or after the
attaching to the substrate attachment. If the substrate is
back-thinned before the attachment to the substrate attachment, the
substrate attachment is not contaminated. However, a transfer of a
back-thinned substrate to the substrate attachment must then be
carried out. If the substrate is back-thinned after the attachment
to the substrate attachment, the substrate attachment is preferably
cleaned after the back-thinning. Because of the immediate
attachment of the substrate that is to be back-thinned, however,
advantages of stability will emerge. In addition, there is no need
for the transferring of a back-thinned substrate to the substrate
attachment according to the invention.
The Process
[0060] According to a first embodiment of the process according to
the invention, the two thinned substrates that are to be bonded by
means of a first attachment according to the invention are arranged
at a distance to one another, without the contact surfaces of the
substrates first making contact or being connected temporarily
(pre-bonding). The substrates are accordingly attached in each case
to in particular corresponding, opposite substrate attaching
surfaces of substrate attachments.
[0061] In a first process step, an alignment of two substrates to
one another is carried out based on alignment markings of the
substrates. Despite the alignment of the substrates, attached to
the substrate attachments according to the invention, based on
their alignment markings, an alignment of the substrate attachments
to one another according to the invention that is not completely
perfect can result if the latter are not aligned identically with
the respective substrates. The alignment can be carried out, for
example, with one of the attachments from U.S. Pat. No. 6,214,692
B1, PCT/EP 2013/075831 or PCT/EP 2013/062473. In the case of the
alignment of multiple smaller substrates to a large substrate or
the alignment of multiple smaller substrates to multiple small
substrates, the alignment process can also be subject to an error
minimization process, in which the optimal alignment of the
substrate attachments and thus the small substrates that are
located thereon is carried out by an error minimization. Such
processes are described in the publication WO2013/182236A1.
[0062] In particular, the further processing is carried out when an
orienting angle around the normal of the two corresponding
substrate attachments to one another is in particular less than
5.degree., preferably less than 1.degree., even more preferably
less than 0.1.degree., most preferably less than 0.01.degree., and
all the more preferably less than 0.0001.degree., and/or a
translatory shifting of the two corresponding substrate attachments
to one another is in particular less than 5 mm, preferably less
than 1 mm, even more preferably less than 100 .mu.m, most
preferably less than 1 .mu.m, and all the more preferably less than
100 nm. The above-mentioned values can be determined with a testing
system.
[0063] In a second process step according to the invention, moving
the substrate attachments according to the invention toward one
another is carried out. In the case of bringing objects together,
optionally a continuous control of the alignment markings and/or
characteristic features of the substrates to one another or to
other features can be carried out, so that a continuous checking of
the positions of the substrates during the bringing-together phase
can take place. As a result, it is ensured that during the
bringing-together phase, no shifting of the two substrates toward
one another is carried out. At the end of the process step, the
surfaces of the in particular magnetic substrate attachment, here
the frame, make contact with the carrier attaching surfaces. The
frames are attached to one another. The attachment is preferably
carried out via an in particular inherent magnetization of at least
one of the two frames at least on the carrier attaching surfaces.
The attachment by means of an adhesive, which is applied to at
least one of the carrier attaching surfaces, is also conceivable,
however. Another conceivable attachment option is clamping by means
of clamping elements applied on the outside.
[0064] In a third process step according to the invention, a
prebonding or bonding process is carried out by bringing the two
substrates toward one another, which substrates are attached to the
substrate attaching surfaces on the carriers. The bonding process
by moving the two substrates toward one another can also be carried
out in particular by means for bringing objects together, in
particular a centrically-oriented pressure device, in particular by
a mandrel, from the reverse side of the substrate attachment
according to the invention. Such means for bringing objects
together and in particular specimen holders that were suitable for
holding the substrate attachments are described in more detail in
the publication PCT/EP 2011/064353.
[0065] In this embodiment, the bringing-together of objects is
carried out by deformation of the carrier, in particular the film
that is stretched in the frame. The film can be deformed by a
centrically-oriented pressure device or by a roller of the film on
the side facing away from the substrate. In the publication
WO2014037044A1, a device with a roller is described, with whose
help an embossing can be performed. One skilled in the art could
build an attachment from the device in the publication
WO2014037044A1, which attachment generates a corresponding
line-shaped loading of the substrate attachment according to the
invention, in particular the film, and thus initiates a
corresponding contacting and/or bonding process. In special
embodiments according to the invention, it may be appropriate to
make one of the two substrates move toward, by deformation of the
carrier, the second substrate that is held in an especially planar
manner. Primarily a centric load is conceivable in particular using
a pin for initiating a bonding wave that automatically propagates.
This embodiment according to the invention is suitable primarily
for prebonding or bonding substrates, which are to be connected to
one another by a fusion-bonding process.
[0066] In a second embodiment of the process according to the
invention, the two substrates are attached to one another by means
of the second, above-described substrate attachment.
[0067] In a first process step, an alignment of two substrates is
carried out based on their alignment markings with one another. The
above remarks regarding the first embodiment of the process apply
primarily for the second embodiment. While in the first embodiment,
a shifting of the substrate relative to the frame that occurs after
the attachment of the substrate can occur when the film is
distorted by mechanical and/or thermal stress, this is virtually
ruled out in the case of the second embodiment.
[0068] The second process step is carried out analogously to the
first embodiment, whereby the attachment of the substrate
attachments preferably to a carrier attaching area (instead of
directly by making contact on a carrier attaching surface) is
carried out preferably magnetically, in particular at a distance to
one another.
[0069] Should the two substrates have been pre-attached to one
another by a prebonding, it can be provided according to the
invention to perform an additional full-surface bonding before
and/or during a heat treatment in order to exert an additional, in
particular full-surface and uniform, pressure loading on the two
substrates. The applied force is in this case in particular greater
than 100 N, preferably greater than 1 kN, even more preferably
greater than 10 kN, most preferably greater than 100 kN, and all
the more preferably greater than 1,000 kN. The pressures are
calculated by the division of the applied force by the surface of
the substrate that is to be bonded. The pressure that acts on a
circular 200 mm substrate is therefore approximately 3.2 Pa bar at
a pressure loading of 1 N and approximately 320,000 Pa at a
pressure loading of 10 kN.
[0070] The substrate attachments can be handled with a specimen
holder and/or a robot and transported between various processes and
stations.
The Heat Treatment
[0071] All embodiments of the substrate attachments according to
the invention are preferably suitable to withstand a heat treatment
process, in particular for bonding. The first embodiment, however,
can be limited by a maximum operating temperature of the carrier or
the substrate attachment, in particular when the carrier is a
film.
[0072] The substrates can be subjected to a heat treatment in order
to provide a permanent connection (permanent bond). The bonding
strength of the permanent bond is in particular greater than 1.0
J/m2, preferably greater than 1.5 J/m2, even more preferably
greater than 2.0 J/m2, and most preferably greater than or equal to
2.5 J/m2. In this case, it is advantageous according to the
invention when the substrates are located on the substrate
attachments according to the invention. As a result, it is namely
made possible to heat the substrate attachments in a mass process
(batch process). The heating is preferably carried out in a
continuous furnace. In the case of an alternative embodiment, the
heat treatment is carried out in a module of a cluster that
includes a number of modules. The bonding to a hot plate is also
conceivable according to the invention. The temperature that is
used in such a heat-treatment process is in particular less than
700.degree. C., preferably less than 500.degree. C., even more
preferably less than 300.degree. C., most preferably less than
100.degree. C., and all the more preferably less than 50.degree. C.
In special cases, in which the attached substrates have specially
prepared surfaces, the substrates can already be tightly bonded to
one another when making contact at room temperature in such a way
that an additional heat treatment is no longer necessary.
[0073] If the substrate attachments according to the invention have
a ferromagnetic material, the Curie temperature is preferably not
exceeded in order not to lose the magnetic properties of the
substrate attachment according to the invention.
[0074] In another embodiment according to the invention, however,
specifically the disappearance of the ferromagnetism of the
substrate attachments according to the invention in the exceeding
of the Curie temperature can describe another aspect according to
the invention. If the bonding strength of the permanent bond
between two substrates achieves its maximum only above a certain
temperature, and this temperature is at least close to the Curie
temperature, an automatic separation of the substrate attachments
by loss of ferromagnetism can be carried out by another heating
above the Curie temperature. Advantageously, the substrate holding
devices according to the invention are then separated before the
temperature drops below the Curie temperature again, which leads to
a return of ferromagnetism, or at least are separated from one
another by additional separating elements in such a way that when
falling short of the Curie temperature, they at least are no longer
connected to one another or at least can more easily separate. Such
automatic separating processes are advantageous primarily in fully
automatic batch processes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0075] Further advantages, features and details of the invention
follow from the subsequent description of preferred embodiments and
based on the drawings; the latter show in diagrammatic view in each
case:
[0076] FIG. 1a a diagrammatic cross-sectional depiction, not to
scale, of a first embodiment of a device according to the
invention,
[0077] FIG. 1b a diagrammatic cross-sectional depiction, not to
scale, of a second embodiment of the device according to the
invention,
[0078] FIG. 2a a diagrammatic cross-sectional depiction, not to
scale, of a first process step of a first embodiment of the process
according to the invention,
[0079] FIG. 2b a diagrammatic cross-sectional depiction, not to
scale, of a second process step of the first embodiment,
[0080] FIG. 2c a diagrammatic cross-sectional depiction, not to
scale, of a third process step of the first embodiment,
[0081] FIG. 3a a diagrammatic cross-sectional depiction, not to
scale, of a first process step of a second embodiment of the
process according to the invention, and
[0082] FIG. 3b a diagrammatic cross-sectional depiction, not to
scale, of a second process step of the second embodiment.
[0083] In the figures, the same components or components with the
same function are identified with the same reference numbers.
DETAILED DESCRIPTION OF THE INVENTION
[0084] The first embodiment according to FIG. 1a involves a
substrate attachment 1 formed from a frame 2 and a carrier 3 (here,
an elastic film) that is stretched over the frame 2. It is also
conceivable that the stretched carrier 3 is a very thin, but rigid
plate in the unsupported state that therefore cannot be interpreted
as film. The carrier 3 can then in particular also be elastically
deformed by loading its carrier surface 3o. On its carrier surface
3o, the substrate attachment 1 has a substrate attaching surface 9
(or substrate attaching area) and in particular a ring-shaped
carrier attaching surface 8 (or carrier attaching area) that
surrounds the substrate attaching surface 9.
[0085] The frame 2 and the carrier 3 together form a receiving area
for receiving an in particular thinned first substrate 4, whereby a
side of the first substrate 4 facing away from the carrier 3 is
preferably set back relative to the carrier attaching surface
8.
[0086] The back-thinned first substrate 4 is attached to the
substrate attaching surface 9 (here a film surface) of the carrier
3 (here, an elastic film) that is stretched over the frame 2. The
carrier surface 3o is adhesive for attaching the first substrate 4
and for attaching the carrier 3 to the frame 2.
[0087] In the embodiment according to FIG. 1b, an in particular
monolithic substrate attachment 1' is shown. The latter has a rigid
carrier 3' with a carrier surface 3o', which has a vacuum
attachment as an attaching element 5.
[0088] The attaching element 5 can have vacuum strips (as shown);
instead of this, however, it can also have electrostatic
attachments, magnetic attachments, adhesive surfaces, or mechanical
clamps. In particular, the attaching elements 5 also act over wide
distances/long times in the case of a transport of the carrier 3'.
When using a vacuum for attaching the first substrate 4, the vacuum
can be maintained within a vacuum chamber and/or the vacuum strips
by closing a valve 6. In the case of other attachments according to
the invention, the valve 6 can be interpreted in general as a
control unit that is controlled via a control system. Instead of
this, a feed line for electric current would also be conceivable in
the case of an electrostatic and/or magnetic attachment.
[0089] The layer thickness of the thinned first substrate 4 is
small so that a stabilization of the first substrate 4 by a carrier
3, 3' according to the invention is advantageous in order to avoid
damage to the first substrate 4.
[0090] What is stated above for the first substrate analogously
applies for a second substrate 4' or other substrates if the latter
are designed identically. Combinations of the described substrate
attachments 1, 1' can also be used for the second or other
substrates.
[0091] In the following figures, the process according to the
invention is explained based on two examples, whereby the
substrates that are to be bonded (first, second, and some other
substrates) and substrate attachments are designed identically in
each case. It is conceivable according to the invention to use
different substrate attachments and/or substrates for the first
substrate 4 and the second substrate 4' or other substrates.
[0092] FIG. 2a shows an alignment process in which the two
substrates 4, 4' are attached in each case to carriers 3 of the
substrate attachments 1 that are arranged on opposite sides and are
aligned with one another. The alignment is preferably carried out
via an alignment unit (aligner), not shown. The alignment is
carried out in a way that is known in the art, preferably between
corresponding alignment markings on the substrate surfaces 4o, 4o'
of the substrates 4, 4'.
[0093] Since the alignment is carried out on alignment markings of
the substrates 4, 4', the substrate attachments 1 can be shifted
toward one another. This shifting is normally marginal and
negligible, however. In particular, the shifting according to the
invention is less than 5 mm, preferably less than 1 mm, even more
preferably less than 100 .mu.m, most preferably less than 10 .mu.m,
and all the more preferably less than 1 .mu.m. In this connection,
it is decisive that the corresponding carrier attaching areas or
carrier attaching surfaces 8 lie opposite one another in such a way
that an adequate transfer of force for mutual attachment of the
substrate attachments 1 is made possible.
[0094] FIG. 2b shows a contacting process, in which the surfaces 2o
(carrier attaching surfaces 8) of the two frames 2 make contact
with one another. The two frames 2 are directly attached to one
another in particular by inherent magnetic forces (depicted by
magnetic field lines 7). It is also conceivable that the substrate
surfaces 4o lie above the surfaces 2o. In this case, the substrate
surfaces 4o make contact before the surfaces 2o. The surfaces 2o
are independently drawn to one another, in particular by magnetic
forces.
[0095] In the process step according to FIG. 2c, a contact between
the two substrates 4, 4' takes place. The making of contact can be
done by any elements that impose force on the substrates 4, 4' in
opposite directions, in particular by centric and
radially-symmetric pressure elements or by rollers. By imposing
force, the elastic carrier 3 is expanded in the direction of the
opposite carrier 3. In particular, it is conceivable, as depicted,
to deform both carriers 3 against one another. If the substrate
surfaces 4o project over the surfaces 2o, a contact of the outer
frame 2 is carried out in this process step. In particular in the
case of the magnetic frames, the making of contact is done
independently by their magnetic attraction.
[0096] In FIG. 3a, an alignment process is shown analogously to
FIG. 2a with substrate attachments 1' according to FIG. 1b.
[0097] In FIG. 3b, a contacting process is depicted, in which the
substrate surfaces 4o, 4o' of the two substrates 4, 4' make contact
with one another before the substrate attachments 1' can come into
contact. In this embodiment, the substrate attachments 1' therefore
operate without contact. The thus formed substrate stack is
attached in particular by inherent magnetic forces of the carrier
3'.
[0098] According to the invention, at least one of the two
substrates 4, 4' is a thinned substrate 4, 4'. The bonding process
is thus no longer limited to the use of thick, dimensionally-stable
substrates.
LIST OF REFERENCE SYMBOLS
[0099] 1, 1' Substrate attachment [0100] 2 Frame [0101] 2o Surface
[0102] 3, 3' Carrier [0103] 3o, 3o' Carrier surface [0104] 4, 4'
Substrate [0105] 4o, 4o' Substrate surface [0106] 5 Attaching
element, in particular vacuum attachment [0107] 6 Control unit, in
particular valve [0108] 7 Magnetic field lines [0109] 8 Carrier
attaching area/carrier attaching surface [0110] 9 Substrate
attaching surface
* * * * *