Title: Method of transferring a substantially disc-shaped workpiece, and device for carrying out this method
Abstract: Consistent with an embodiment of the present invention, there is a device for transferring a substantially disc-shaped workpiece from a workpiece carier. The workpiece is fastened along a first one of its main surfaces with a double-sided adhesive foil onto a carrier foil. The workpiece is fastened onto the carrier foil along a first one of its main surfaces with of a double-sided adhesive foil onto a carrier foil on whose surface the workpiece is to be provided and fastened along the first main surface in an at least substantially planar manner. The first double-sided adhesive foil is adhesively connected by a first adhesive layer provided on its first surface to a first surface of the workpiece carrier and by a second adhesive layer provided on its second surface to the workpiece along the first main surface thereof.
Patent Number: 6,997,226 Issued on 02/14/2006 to Anker
| Inventors:
|
Anker; Joachim (Hamburg, DE)
|
| Assignee:
|
Koninklijke Philips Electronics N.V. (Eindhoven, NL)
|
| Appl. No.:
|
480732 |
| Filed:
|
June 13, 2002 |
| PCT Filed:
|
June 13, 2002
|
| PCT NO:
|
PCT/IB02/02258
|
| 371 Date:
|
December 12, 2003
|
| 102(e) Date:
|
December 12, 2003
|
| PCT PUB.NO.:
|
WO03/001587 |
| PCT PUB. Date:
|
January 3, 2003 |
Foreign Application Priority Data
| Jun 15, 2001[DE] | 101 28 923 |
| Current U.S. Class: |
156/540; 156/584 |
| Current Intern'l Class: |
B32B 35/00 (20060101) |
| Field of Search: |
117/915
414/939,941,937,935
438/118,106,107,477,464,455-458
156/235,497,382,381,286,285,541,540,598,584,344,249,247,241,234,230,152
269/21
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Fiorilla; Chris
Assistant Examiner: Chan; Sing P.
Attorney, Agent or Firm: Zawliski; Peter
Claims
The invention claimed is:
1. A device for separating a substantially disc-shaped workpiece from a workpiece
carrier, on which the workpiece is fastened along a first of its main surfaces
by means of a first double-sided adhesive foil in an at least substantially planar
manner, onto a carrier foil on whose surface the workpiece is to be provided and
fastened along said first main surface in an at least substantially planar manner,
said first double-sided adhesive foil being adhesively connected by a first adhesive
layer provided on its first surface to a first surface of the workpiece carrier
and by a second adhesive layer provided on its second surface to the workpiece
along the first main surface thereof, which device further comprises:
a first retaining device for fastening the workpiece carrier to said first retaining device,
a second retaining device with a surface on which the workpiece is to be fastened
along its second main surface opposite to the first main surface by means of a
second double-sided adhesive foil in an at least substantially planar manner, such
that the second double-sided adhesive foil is adhesively connected by a third adhesive
layer provided on its first surface to the surface of the second retaining device
and by a fourth adhesive layer provided on its second surface to the workpiece
along the second main surface thereof; and the adhesive forces of the third and
the fourth adhesive layer are substantially greater than the adhesive force of
the second adhesive layer in its weakened state,
a pulling device for separating the workpiece from the first double-sided adhesive
foil along the weakened second adhesive layer through the application of a pulling
force which is at least partly perpendicular to the main surfaces of the workpiece
between the first and the second retaining device, the second retaining device
positioned with the workpiece above the carrier foil,
a device for acting on the second and the fourth adhesive layer for weakening
said adhesive layers through an at least partial decomposition of the adhesive
substance by which they are formed to a reduced adhesive force, and
a gas pressure device for separating the workpiece from the second double-sided
adhesive foil along the weakened fourth adhesive layer through the application
of a force, generated by gas pressure, between the second double-sided adhesive
foil adhering to the second retaining device and the workpiece.
2. A device as recited in claim 1, wherein the workpiece carrier is of an at
least substantially rigid construction.
3. A device as recited in claim 1, wherein the workpiece carrier is fastened
to the first retaining device by means of an adhesive whose adhesive force is substantially
greater than the adhesive force of the weakened second adhesive layer.
4. A device as recited in claim 1, wherein a construction of the workpiece carrier
with a ferromagnetic material and by a magnet device which can be energized and
de-energized, as desired, for fastening the workpiece carrier to the first retaining
device through magnetic attraction between the workpiece carrier and the first
retaining device with a magnetic force which is substantially greater than the
adhesive force of the weakened second adhesive layer.
5. A device as recited in claim 1 further comprises,
a sealing device for forming a substantially gastight seal between the second
retaining device and the carrier foil.
6. A device as recited in claim 1, wherein the workpiece is a semiconductor technology
product, preferably a semiconductor wafer, which is constructed along at least
its first main surface so as to form a plurality of electronic circuit bodies which
are to be mechanically separated substantially perpendicularly to the first main surface.
7. A device recited in claim 6, wherein the carrier foil is designed as a carrier
medium for the mechanical separation of the electronic circuit bodies, preferably
in the form of a sawing foil.
Description
The invention relates to a method of transferring a substantially disc-shaped
workpiece. The invention further relates to a device for carrying out this method.
A temporary gluing on so-termed workpiece carriers, in particular carrier discs
or carrier plates, is a suitable procedure in the case of one-sided or two-sided
surface treatments of substantially planar, in particular very thin and brittle
workpieces while this treatment is being carried out so as to avoid a deformation
of the workpieces or indeed fracture thereof. A very thin workpiece in the present
context should be understood to be a workpiece whose thickness is small in relation
to its length, width, or diameter.
The German patent document 198 50 873 laid open to public inspection discloses
a method of processing a substantially disc-shaped semiconductor technology product
which comprises a plurality of electronic circuit bodies along at least a first
main surface as well as a second main surface situated opposite the first main
surface. In this method of carrying out treatment processes on one of the main
surfaces of the product, a layer-type adhesive material is planarly provided on
the opposite main surface of the product, onto which material a dimensionally at
least substantially stable carrier element is provided so as to form a planar connection
to said opposite main surface of the product.
The invention has for its object to provide a method by which a simple and inexpensive
removal of a workpiece of the kind mentioned above from a workpiece carrier is
made possible. The invention further has the object of providing a device for carrying
out such a method.
According to the invention, this object is achieved by means of a method
of transferring a substantially disc-shaped workpiece from a workpiece carrier,
on which the workpiece is fastened along a first one of its main surfaces by means
of a double-sided adhesive foil in an at least substantially planar manner, onto
a carrier foil on whose surface the workpiece is to be provided and fastened along
said first main surface in an at least substantially planar manner, which first
double-sided adhesive foil is adhesively connected by a first adhesive layer provided
on its first surface to a first surface of the workpiece carrier and by a second
adhesive layer provided on its second surface to the workpiece along the first
main surface thereof. The method according to the invention for this purpose comprises
the following process steps:
- weakening the second adhesive layer by an at least partial decomposition
of the adhesive substance forming said second adhesive layer to a reduced adhesive
force which is substantially smaller than the adhesive force of the first adhesive layer,
- fastening the workpiece carrier to a first retaining device,
- fastening the workpiece along its second main surface opposite to the
first main surface to a surface of a second retaining device by means of a second
double-sided adhesive foil in an at least substantially planar manner, such that
the second double-sided adhesive foil is adhesively connected by a third adhesive
layer provided on its first surface to the surface of the second retaining device
and by a fourth adhesive layer provided on its second surface to the workpiece
along the second main surface thereof, and the adhesive forces of the third and
the fourth adhesive layer are substantially greater than the adhesive force of
the weakened second adhesive layer,
- separating the workpiece from the first double-sided adhesive foil along
the weakened second adhesive layer through the application of a pulling force between
the first and the second retaining device, which force is at least partly perpendicular
to the main surfaces of the workpiece
- positioning the workpiece adhesively connected to the second retaining
device and the carrier foil with respect to one another such that the first main
surface of the workpiece faces the surface of the carrier foil,
- weakening the fourth adhesive layer through an at least partial decomposition
of the adhesive substance by which it is formed to a reduced adhesive force which
is substantially smaller than the adhesive force of the third adhesive layer,
- placing the workpiece with its first main surface on the surface of
the carrier foil in an at least substantially planar manner, and
- separating the workpiece from the second double-sided adhesive foil
along the weakened fourth adhesive layer through the application of a force, generated
by gas pressure, between the second double-sided adhesive foil adhering to the
second retaining device and the workpiece.
The method according to the invention renders it possible in an inexpensive and
simple manner to transfer also mechanically vulnerable workpieces safely from a
workpiece carrier onto a carrier foil.
In particular, at least substantially rigidly constructed workpiece carriers
can
be used for this. The fastening of the workpiece carrier to the first retaining
device may be effected, as desired, by gluing or by magnetic force.
The adhesive layers which are to be weakened for the transfer may preferably
be prepared with an adhesive substance which is sensitive to heat or to ultraviolet
radiation. Weakening of the adhesive layers will then take place through the influence
of heat or ultraviolet radiation.
Further embodiments and particulars of the method according to the invention
are defined in the dependent claims following the main claim
1.
For carrying out the method according to the invention, furthermore, a device
is proposed for transferring a substantially disc-shaped workpiece from a workpiece
carrier, on which the workpiece is fastened along a first of its main surfaces
by means of a first double-sided adhesive foil in an at least substantially planar
manner, onto a carrier foil on whose surface the workpiece is to be provided and
fastened along said first main surface in an at least substantially planar manner.
The first double-sided adhesive foil is adhesively connected by a first adhesive
layer provided on its first surface to a first surface of the workpiece carrier
and by a second adhesive layer provided on its second surface to the workpiece
along the first main surface thereof. The device according to the invention further
comprises a first retaining device for fastening the workpiece carrier to said
first retaining device, a second retaining device with a surface on which the workpiece
is to be fastened along its second main surface opposite to the first main surface
by means of a second double-sided adhesive foil in an at least substantially planar
manner, such that the second double-sided adhesive foil is adhesively connected
by a third adhesive layer provided on its first surface to the surface of the second
retaining device and by a fourth adhesive layer provided on its second surface
to the workpiece along the second main surface thereof, and the adhesive forces
of the third and the fourth adhesive layer are substantially greater than the adhesive
force of the second adhesive layer in its weakened state.
The device according to the invention further comprises a pulling device for
separating the workpiece from the first double-sided adhesive foil along the weakened
second adhesive layer through the application of a pulling force which is at least
partly perpendicular to the main surfaces of the workpiece between the first and
the second retaining device, a device for acting on the second and the fourth adhesive
layer for weakening said adhesive layers through an at least partial decomposition
of the adhesive substance by which they are formed to a reduced adhesive force,
as well as a gas pressure device for separating the workpiece from the second double-sided
adhesive foil along the weakened fourth adhesive layer through the application
of a force, generated by gas pressure, between the second double-sided adhesive
foil adhering to the second retaining device and the workpiece.
The device according to the invention is of a simple construction and renders
possible a reliable, inexpensive, and thus rational manufacture.
Preferably, the device according to the invention is constructed with
a magnet device which can be energized or de-energized, as desired, for fastening
the workpiece carrier to the first retaining device, the workpiece carrier being
constructed from a ferromagnetic material. This renders possible a simple, fast,
and reliable fastening of the workpiece carrier to the first retaining device.
If so desired, the workpiece carrier is fastened to the first retaining device
by means of gluing.
To enhance the effectiveness of the gas pressure device, a sealing device may
be provided for forming a substantially gastight seal between the second retaining
device and the carrier foil.
Further particulars and embodiments of the device according to the invention
can be found in the dependent claims subsequent to the main patent claim
8.
An embodiment of the invention is shown in the drawing and will be described
in
more detail below. In the drawing:
FIG. 1 shows an example of a workpiece fastened to a workpiece carrier by means
of a first double-sided adhesive foil in a diagrammatic representation,
FIG. 2 diagrammatically shows the action of heat or ultraviolet radiation for
weakening the second adhesive layer between the first double-sided adhesive foil
and the workpiece,
FIG. 3 shows the workpiece carrier with the workpiece of FIGS. 1 and 2 after
fastening to a first retaining device,
FIG. 4 shows the arrangement of FIG. 3 after the workpiece has been additionally
fastened to a second retaining device,
FIG. 5 is an exploded view of the arrangement of FIG. 4,
FIG. 6 shows the arrangement of FIG. 4 after separation of the workpiece from
the workpiece carrier,
FIG. 7 shows the second retaining device with the workpiece positioned above
a carrier foil,
FIG. 8 shows the weakening of the adhesive layer by means of which the workpiece
is fastened to the second retaining device,
FIG. 9 shows the placing of the workpiece on the carrier foil,
FIG. 10 shows the separation of the workpiece from the second retaining device, and
FIG. 11 shows a modified embodiment of the device shown in FIGS. 3 to 10 with
a sealing device between the second retaining device and the carrier foil.
In the diagrammatic drawing of FIG. 1, a workpiece
1, in particular a
thin
semiconductor wafer, is fastened by its first main surface, which forms the lower
side in the position of the workpiece
1 shown here, to a workpiece carrier
2 by means of a double-sided adhesive foil
3 in a planar manner.
The first double-sided adhesive foil
3 is formed in a known manner by a
foil-type synthetic resin body whose two surfaces are coated with adhesive layers.
A first of these surfaces faces the workpiece carrier
2 with a first adhesive
layer, and a second of the surfaces faces the workpiece
1 with a second
adhesive layer. This arrangement is shown in FIG. 5.
FIG. 2 diagrammatically shows the configuration of FIG. 1 with heat or ultraviolet
radiation acting thereon, indicated by the reference numeral
4. This action
decomposes the second adhesive layer of the first double-sided adhesive foil
3
at least partly, thus weakening it, so that its adhesive force is reduced. For
this purpose, the second adhesive layer, unlike the first adhesive layer, of the
first double-sided adhesive foil
3 is made from a heat-sensitive or UV-sensitive material.
FIG. 3 diagrammatically shows the next process step in the embodiment. The workpiece
carrier
2 and the workpiece
1 fastened thereon by means of the first
double-sided adhesive foil
3 are fastened on a first retaining device
5
after the second adhesive layer has been weakened. This fastening may also be effected
through adhesion, or alternatively by means of a magnet device which is incorporated
in the first retaining device and which exerts a magnetic force on the workpiece
carrier
2. The workpiece carrier
2 will for this purpose be made
from a ferromagnetic material. The adhesive force of the first adhesive layer between
the first double-sided adhesive foil
3 and the workpiece carrier
2
as well as the adhesive force between the workpiece carrier
2 and the first
retaining device
5 are substantially greater here than the adhesive force
of the weakened second adhesive layer of the first double-sided adhesive foil
3
by means of which the latter still holds on to the workpiece
1 in the process
step shown here.
As is apparent from FIG. 3, the workpiece carrier
2 is preferably laid
with its entire surface on the first retaining device
5.
FIG. 4 diagrammatically shows the arrangement of the preceding Figures after
fastening of a second retaining device
6 by means of a second double-sided
adhesive foil
7 over a second main surface of the workpiece
1 in
a planar manner. This second main surface of the workpiece
1 is the upper
side thereof in the representation of FIG. 4.
Details of the arrangement shown in FIG. 4 are shown in the exploded view
of FIG. 5. This shows diagrammatically from top to bottom in that order: the second
retaining device
6, the second double-sided adhesive foil
7, the
workpiece
1, the first double-sided adhesive foil
3, the workpiece
carrier
2, an adhesive
8 for fastening the workpiece carrier
2
to the first retaining device
5, and this first retaining device
5
itself. The second double-sided adhesive foil
7 here carries a third adhesive
layer on its first surface
9 and a fourth adhesive layer on its second surface
11. The first main surface of the workpiece
1 is referenced
13.
The second main surface of the workpiece
1 is referenced
14. The
first double-sided adhesive foil
3 has the first adhesive layer
16
on its first surface
15 and the second adhesive layer
18 on its second
surface
17. The first surface of the workpiece carrier
2, on which
the workpiece is fastened by means of the first double-sided adhesive foil
3,
is referenced
19, while a second surface
20 of the workpiece carrier
2 opposite to said surface
19 serves to fasten said carrier to the
first retaining device
5.
The next process step in the embodiment shown is depicted diagrammatically in
FIG. 6. Herein, the arrangement of FIG. 4 or
5 is introduced into a pulling
device (not shown), and a pulling force is exerted thereby on the second retaining
device
6, indicated with an arrow referenced
21. Since the adhesive
forces of all adhesive elements or layers in the embodiment shown are substantially
greater than the adhesive force of the second adhesive layer
18, the application
of the pulling force
21 will separate the arrangement of FIG. 4 along said
second adhesive layer such that the workpiece
1 detaches itself by its first
main surface
13 from the second adhesive layer
18. This situation
is shown in FIG. 6.
In the next process step, the first retaining device
5 is removed complete
with the workpiece carrier
2 still fastened thereon, and the second retaining
device
6 is positioned with the workpiece above a carrier foil
22.
The carrier foil
22 is supported by a planar base surface
23 for
stabilization in the embodiment shown. The situation thus achieved is shown in
FIG. 7.
FIG. 8 shows the subsequent process step in which the second double-sided adhesive
foil
7 is exposed to heat or ultraviolet radiation, again referenced
4
here. The fourth adhesive layer
12 on the second surface
11 of the
second double-sided adhesive foil
7, by means of which the workpiece
1
adheres to this second double-sided adhesive foil
7, is prepared with an
adhesive substance which is sensitive to heat or ultraviolet radiation and which
can be decomposed through the action thereof. As a result, the fourth adhesive
layer
12 has its adhesive force reduced to well below the adhesive force
obtaining between the second double-sided adhesive foil
7 and the second
retaining device
6 in the process step shown in FIG. 8. The weakening of
the fourth adhesive layer
12 takes place before the workpiece
1 is
placed on the carrier foil
22 so as to avoid damage to the carrier foil
22.
In the next process step shown in FIG. 9, the workpiece
1 is provided
on
the carrier foil
22, for which purpose the second retaining device
6
complete with the workpiece
1 is lowered onto the carrier foil
22
in a movement indicated with the arrow
24. This process step is subject
to the condition that any temperature rise of the workpiece
1 caused by
the preceding process step has first been eliminated.
FIG. 10 diagrammatically shows the next process step of separating the workpiece
1 from the second double-sided adhesive foil
7 along the weakened
fourth adhesive layer
12, again with reference to the arrangement shown
in the preceding Figures. The second retaining device
6 for this purpose
comprises an inner space
25 to which a gas under pressure, preferably compressed
air, can be applied through a pressure inlet valve
28. Bores
26 are
provided in the portion of the second retaining device
6 forming the surface
27, on which the workpiece
1 was fastened by means of the second
double-sided adhesive foil
7, through which bores the compressed gas flowing
through the inlet
28 can flow out again. Matching holes are provided in
the second double-sided adhesive foil
7, so that the bores
26 are
not covered by the second double-sided adhesive foil
7. This renders it
possible for the gas pressure in the inner space
25 of the second retaining
device
6 to act directly on the workpiece
1, and the second double-sided
adhesive foil
7 does not detach itself from the surface
27 of the
second retaining device
6. It is ensured thereby that the workpiece
1
is separated from the second double-sided adhesive foil
7 and is deposited
on the carrier foil
22.
This depositing step is preferably supported in that a movement between the
second retaining device
6 and the second double-sided adhesive foil
7
connected thereto on the one hand and the carrier foil
22 with the work
piece
1 adhered thereto on the other hand is carried out during the separation
of the workpiece
1 from the second double-sided adhesive foil
7 at
least substantially simultaneously with the application of the force generated
by the gas pressure. This movement is effected so as to be at least in part perpendicular
to the main surfaces of the workpiece
1 and is indicated in FIG. 10 by the
arrows referenced
30. This movement
30 removes the second retaining
device
6 from the carrier foil
22 and the workpiece
1. The
simultaneous issuing of gas under pressure through the bores
26 is diagrammatically
indicated with the arrows
29 in FIG. 10.
After the process step described above has been completed, the workpiece
1
is present on the carrier foil
22 for further processing, which may take
place at its second main surface
14, said carrier foil being preferably
constructed as a sawing foil for the case in which the workpiece
1 is a
semiconductor technology product.
FIG. 11 shows a modification of the device described above which comprises a
sealing device
31 for forming a substantially gastight seal between the
second retaining device
6 and the carrier foil
22. When a gas pressure
is provided through the pressure gas inlet valve
28, the pressure on the
workpiece
1 can be increased for pressing the latter onto the carrier foil
22 because an overpressure
32 will be built up in the intermediate
space between the second retaining device
6 and the carrier foil
22.
The device shown in FIG. 11 further comprises bores
33 in the base support
23 for the carrier foil
22 for providing a vacuum suction of the
carrier foil
22 and the workpiece
1 against the base surface
23.
In a modified embodiment which is not shown, the workpiece carrier
2 may
be constructed from a ferromagnetic material, and the fastening of the workpiece
carrier
2 to the first retaining device
5 may be effected by a magnet
device. The adhesive
8 will be absent in such an embodiment. Furthermore,
such a workpiece carrier
2 formed from a ferromagnetic material may obviously
also be fastened to a first retaining device
5 of the kind shown in the
embodiment by means of the adhesive
8.
*
