U.S. patent application number 11/903677 was filed with the patent office on 2008-03-27 for semiconductor device having sealing film and manufacturing method thereof.
This patent application is currently assigned to Casio Computer Co., Ltd.. Invention is credited to Junji Shiota.
Application Number | 20080073785 11/903677 |
Document ID | / |
Family ID | 39224067 |
Filed Date | 2008-03-27 |
United States Patent
Application |
20080073785 |
Kind Code |
A1 |
Shiota; Junji |
March 27, 2008 |
Semiconductor device having sealing film and manufacturing method
thereof
Abstract
A semiconductor device includes a plurality of wiring lines
which are provided on an upper side of a semiconductor substrate
and which have connection pad portions, Columnar electrodes are
provided on the connection pad portions of the wiring lines. A
first sealing film is provided around the columnar electrodes on
the upper side of the semiconductor substrate and on the wiring
lines. A second sealing film is provided on the first sealing film.
The first sealing film is made of a resin in which fillers are not
mixed, and the second sealing film is made of a material in which
fillers are mixed in a resin.
Inventors: |
Shiota; Junji; (Hamura-shi,
JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 Fifth Avenue, 16TH Floor
NEW YORK
NY
10001-7708
US
|
Assignee: |
Casio Computer Co., Ltd.
Tokyo
JP
|
Family ID: |
39224067 |
Appl. No.: |
11/903677 |
Filed: |
September 24, 2007 |
Current U.S.
Class: |
257/738 ;
257/E21.476; 257/E23.023; 438/465 |
Current CPC
Class: |
H01L 21/6715 20130101;
H01L 21/561 20130101; H01L 21/67745 20130101; H01L 2224/16
20130101; H01L 24/02 20130101; H01L 2924/01013 20130101; H01L
2924/01014 20130101; H01L 2224/0231 20130101; H01L 24/05 20130101;
H01L 2924/01033 20130101; H01L 2224/0401 20130101; H01L 2224/13024
20130101; H01L 24/03 20130101; H01L 2924/01006 20130101; H01L
23/3114 20130101; H01L 2924/14 20130101; H01L 21/67207 20130101;
H01L 2224/13099 20130101; H01L 2224/02377 20130101; H01L 2224/05008
20130101; H01L 2924/014 20130101; H01L 24/11 20130101; H01L
2224/05569 20130101; H01L 2924/01029 20130101; H01L 24/12 20130101;
H01L 2924/01004 20130101; H01L 24/13 20130101 |
Class at
Publication: |
257/738 ;
438/465; 257/E23.023; 257/E21.476 |
International
Class: |
H01L 23/488 20060101
H01L023/488; H01L 21/44 20060101 H01L021/44 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2006 |
JP |
2006-260349 |
Claims
1. A semiconductor device comprising: a semiconductor substrate; a
plurality of wiring lines which are provided on an upper side of
the semiconductor substrate and which have connection pad portions;
a plurality of columnar electrodes provided on the connection pad
portions of the wiring lines; a first sealing film provided around
the columnar electrodes on the upper side of the semiconductor
substrate and on the wiring lines; and a second sealing film
provided on the first sealing film, wherein the first sealing film
is made of a resin in which fillers are not mixed, and the second
sealing film is made of a material in which fillers are mixed in a
resin.
2. The semiconductor device according to claim 1, wherein an upper
surface of the first sealing film is substantially flat.
3. The semiconductor device according to claim 1, wherein a solder
ball is provided on each of the columnar electrodes.
4. The semiconductor device according to claim 1, wherein an
insulating layer is interposed between the semiconductor substrate
and the wiring lines.
5. The semiconductor device according to claim 4, wherein the
insulating layer includes an insulating film made of an inorganic
material, and a protective film made of an organic material formed
on the insulating film.
6. The semiconductor device according to claim 1, wherein the first
sealing film has a thickness of several .mu.m.
7. The semiconductor device according to claim 6, wherein the
second sealing film has a thickness of several ten .mu.m or
more.
8. A semiconductor device manufacturing method comprising: forming
a plurality of wiring lines on an upper side of a semiconductor
wafer, and respectively forming columnar electrodes on connection
pad portions of the wiring lines; forming a first sealing film
formation film made of a liquid resin on an upper side of the wafer
in the atmosphere to fill a gap between the wiring lines; carrying
out vacuum deaeration for the first sealing film formation film;
forming a second sealing film formation film made of a liquid resin
containing fillers on the first sealing film formation film in the
atmosphere; carrying out the vacuum deaeration for the second
sealing film formation film; hardening the first and second sealing
film formation films by a thermal treatment to form first and
second sealing films; and cutting the semiconductor wafer and the
first and second sealing films to obtain a plurality of
semiconductor devices.
9. The semiconductor device manufacturing method according to claim
8, wherein the forming the first sealing film formation film
includes forming the first sealing film formation film so that the
wiring lines are covered and so that an upper surface of this first
sealing film formation film is flat.
10. The semiconductor device manufacturing method according to
claim 8, wherein the first sealing film formation film is formed by
spin coating.
11. The semiconductor device manufacturing method according to
claim 8, wherein the second sealing film formation film is formed
by screen printing.
12. The semiconductor device manufacturing method according to
claim 8, further comprising polishing the second sealing film and
upper sides of the columnar electrodes after forming the first and
second sealing film formation films.
13. The semiconductor device manufacturing method according to
claim 12, further comprising forming a solder ball on each of the
columnar electrodes after the polishing.
14. The semiconductor device manufacturing method according to
claim 8, wherein said carrying out the vacuum deaeration for the
first sealing film formation film includes simultaneously carrying
out the vacuum deaeration for the plurality of semiconductor wafer
in each of which the columnar electrodes are formed on the
connection pad portions of the wiring lines.
15. The semiconductor device manufacturing method according to
claim 14, wherein said carrying out the vacuum deaeration for the
first sealing film formation film includes simultaneously carrying
out the vacuum deaeration for the plurality of semiconductor wafers
to each of which the first sealing film formation films is
provided.
16. The semiconductor device manufacturing method according to
claim 8, wherein said carrying out the vacuum deaeration for the
second sealing film formation film includes simultaneously carrying
out the vacuum deaeration for the plurality of semiconductor wafers
to each of which the second sealing film formation film is
provided.
17. semiconductor device manufacturing method according to claim 8,
the first sealing film formation film does not include any fillers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2006-260349,
filed Sep. 26, 2006, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a semiconductor device having a
sealing film and a manufacturing method thereof.
[0004] 2. Description of the Related Art
[0005] There has been known a semiconductor device called a chip
size package (CSP) described in, for example, Jpn. Pat. Appln.
KOKAI Publication No. 2000-22052. The semiconductor device
described in this Jpn. Pat. Appln. KOKAI Publication has a
structure in which wiring lines are provided on a semiconductor
substrate, and columnar electrodes are provided on the upper
surface of connection pad portions of the wiring lines, and then a
sealing film covers the semiconductor substrate except for these
columnar electrodes. In this case, in order to reduce stress caused
by the difference between the thermal expansion coefficients of the
semiconductor substrate and the sealing film, the sealing film has
a three-layer structure which includes, starting from the side of
the semiconductor substrate, a lower sealing film or layer having a
large amount of silica particles mixed in epoxy resin, an
intermediate sealing film or layer having a small amount of silica
particles mixed in epoxy resin, and an upper sealing film or layer
made of epoxy resin alone.
[0006] In a general sealing film forming method that is known, a
sealing film formation film made of liquid epoxy resin with or
without silica particles therein is formed on the semiconductor
substrate by screen printing, and the liquid epoxy resin in the
formation film is heated and hardened to form a sealing film.
[0007] On the other hand, if the screen printing is carried out in
the atmosphere, the liquid resin is pressed on a screen by a
squeegee, so that air is caught into the formation film as air
bubbles. If such a film is hardened as it is, its strength and
moisture resistant properties deteriorate because the air bubbles
are scattered in the sealing film. Therefore, it is possible to
carry out vacuum deaeration in a vacuum chamber after the screen
printing, in order to remove the air bubbles scattered in the
formation film.
[0008] However, in the conventional semiconductor device described
above, the lower sealing layer of the sealing film is formed by the
material having a large amount of silica particles mixed in the
epoxy resin, so that when the diameter of the silica particle is
greater than the distance between the wiring lines, the silica
particle may not be contained between the wiring lines and may be
placed to extend over the adjacent wiring lines. In such a case,
when the formation film is formed by the screen printing, there is
a problem that air tends to remain as air bubbles in a gap under
the silica particles placed to extend over the adjacent wiring
lines, and the air bubbles are not easily removed by the vacuum
deaeration and remain as they are between the wiring lines.
BRIEF SUMMARY OF THE INVENTION
[0009] This invention is directed to provide a semiconductor device
and a manufacturing method thereof which can prevent air bubbles
resulting from fillers from remaining between wiring lines even
when a sealing film is formed by a resin containing the fillers
such as silica particles.
[0010] According to a first aspect of the invention there is
provided a semiconductor device comprising: a semiconductor
substrate; a plurality of wiring lines which are provided on an
upper side of the semiconductor substrate and which have connection
pad portions; columnar electrodes provided on the connection pad
portions of the wiring lines; a first sealing film provided around
the columnar electrodes on the upper side of the semiconductor
substrate and on the wiring lines; and a second sealing film
provided on the first sealing film, wherein the first sealing film
is made of a resin in which fillers are not mixed, and the second
sealing film is made of a material in which fillers are mixed in a
resin.
[0011] Furthermore, according to a second aspect of the invention
there is provided a semiconductor device manufacturing method
comprising:
[0012] forming a plurality of wiring lines on an upper side of a
semiconductor wafer, and respectively forming columnar electrodes
on connection pad portions of the wiring lines;
[0013] forming a first sealing film formation film made of a liquid
resin on an upper side of the wafer in the atmosphere to fill a gap
between the wiring lines;
[0014] carrying out vacuum deaeration for the first sealing film
formation film;
[0015] forming a second sealing film formation film made of a
liquid resin containing fillers on the first sealing film formation
film in the atmosphere;
[0016] carrying out the vacuum deaeration for the second sealing
film formation film;
[0017] hardening the first and second sealing film formation films
by a thermal treatment to form first and second sealing films;
and
[0018] cutting the semiconductor wafer and the first and second
sealing films to obtain a plurality of semiconductor devices.
[0019] Additional objects and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0020] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention, and together with the general description given
above and the detailed description of the embodiments given below,
serve to explain the principles of the invention.
[0021] FIG. 1 is a sectional view of a semiconductor device as one
embodiment of this invention;
[0022] FIG. 2 is a sectional view of initially prepared components
for the manufacture of the semiconductor device shown in FIG.
1;
[0023] FIG. 3 is a sectional view for a step following FIG. 2;
[0024] FIG. 4 is a sectional view for a step following FIG. 3;
[0025] FIG. 5 is a sectional view for a step following FIG. 4;
[0026] FIG. 6 is a sectional view for a step following FIG. 5;
[0027] FIG. 7 is a sectional view for a step following FIG. 6;
[0028] FIG. 8 is a schematic plan view of one example of a sealing
film forming unit for forming first and second sealing films of the
semiconductor device shown in FIG. 1;
[0029] FIG. 9 is a schematic sectional view substantially along the
IX-IX line in FIG. 8;
[0030] FIG. 10 is a schematic plan view of an initial step in
forming the first and second sealing films using the sealing film
forming unit shown in FIGS. 8 and 9;
[0031] FIG. 11 is a schematic sectional view substantially along
the XI-XI line in FIG. 10;
[0032] FIG. 12 is a schematic plan view for a step following FIGS.
10 and 11;
[0033] FIG. 13 is a schematic sectional view substantially along
the XIII-XIII line in FIG. 12;
[0034] FIG. 14 is a schematic plan view for a step following FIGS.
12 and 13;
[0035] FIG. 15 is a schematic sectional view substantially along
the XV-XV line in FIG. 14;
[0036] FIG. 16 is a schematic sectional view for a step following
FIGS. 14 and 15;
[0037] FIG. 17 is a schematic sectional view for a step following
FIG. 16;
[0038] FIG. 18 is a schematic plan view for a step following FIG.
17;
[0039] FIG. 19 is a schematic sectional view substantially along
the IXX-IXX line in FIG. 18;
[0040] FIG. 20 is a schematic plan view for a step following FIGS.
18 and 19;
[0041] FIG. 21 is a schematic plan view for a step following FIG.
20;
[0042] FIG. 22 is a schematic sectional view substantially along
the XXII-XXII line in FIG. 21;
[0043] FIG. 23 is a schematic plan view for a step following FIGS.
21 and 22;
[0044] FIG. 24 is a schematic sectional view substantially along
the XXIV-XXIV line in FIG. 23;
[0045] FIG. 25 is a schematic plan view for a step following FIGS.
23 and 24;
[0046] FIG. 26 is a schematic sectional view substantially along
the XXVI-XXVI line in FIG. 25;
[0047] FIG. 27 is a schematic plan view for a step following FIGS.
25 and 26;
[0048] FIG. 28 is a schematic sectional view substantially along
the XXVIII-XXVIII line in FIG. 27;
[0049] FIG. 29 is a schematic sectional view for a step following
FIGS. 27 and 28;
[0050] FIG. 30 is a schematic sectional view for a step following
FIG. 29;
[0051] FIG. 31 is a schematic sectional view for a step following
FIG. 30;
[0052] FIG. 32 is a schematic sectional view for a step following
FIG. 31;
[0053] FIG. 33 is a schematic sectional view for a step following
FIG. 32;
[0054] FIG. 34 is a schematic plan view for a step following FIG.
33;
[0055] FIG. 35 is a schematic plan view for a step following FIG.
34; and
[0056] FIG. 36 is a schematic sectional view substantially along
the XXXVI-XXXVI line in FIG. 35.
DETAILED DESCRIPTION OF THE INVENTION
[0057] FIG. 1 is a sectional view of a semiconductor device as one
embodiment of this invention. This semiconductor device comprises a
silicon substrate (semiconductor substrate) 1. An integrated
circuit (not shown) with a predetermined function is provided on
the upper surface of the silicon substrate 1, and a plurality of
connection pads 2 made of, for example, an aluminum-based metal are
provided in the peripheral part of the upper surface so that these
connection pads are electrically connected to the integrated
circuit.
[0058] An insulating film 3 made of, for example, an organic
material or an inorganic material such as silicon oxide is provided
on the connection pads 2 except for their centers and on the upper
surface of the silicon substrate 1. The centers of the connection
pads 2 are exposed via openings 4 formed in the insulating film 3.
A protective film 5 made of polyimide-based resin is provided on
the upper surface of the insulating film 3. The protective film 5
is not mixed with fillers such as silica particles. Openings 6 are
provided in parts of the protective film 5 corresponding to the
openings 4 of the insulating film 3.
[0059] A foundation metal layer 7 made of, for example, copper is
provided on the upper surface of the protective film 5. A wiring
line 8 made of copper is provided on the entire upper surface of
the foundation metal layer 7. One end of the wiring line 8
including the foundation metal layer 7 is electrically connected to
the connection pad 2 via the openings 4 and 6 of the insulating
film 3 and the protective film 5. A columnar electrode 9 made of
copper is provided on the upper surface of the connection pad
portion of each of the wiring lines 8. The columnar electrode 9 is
not exclusively limited to but is typically about 30 to 120 .mu.m
in height.
[0060] First and second sealing films 10 and 11 are provided in
this order on the upper surfaces of the wiring line 8 and the
protective film 5 so that these films are located around the
columnar electrodes 9. The first sealing film 10 is made of a
synthetic resin such as epoxy resin (no fillers mixed therein) in
which any additional material as fillers is mixed, completely
covers the wiring line 8, and is provided so that its upper surface
may be flat. The second sealing film 11 is made of a material in
which fillers 11b such as silica particles are mixed or distributed
in a resin 11a such as epoxy resin. The second sealing film 11 is
provided so that its upper surface may be flush with the upper
surfaces of the columnar electrodes 9. A solder ball 12 is provided
on the upper surface of the columnar electrode 9.
[0061] In this specification, the filler indicates a mixture for
bringing the thermal expansion coefficient of the sealing film
formed of the resin closer to the thermal expansion coefficient of
the semiconductor substrate than when no fillers are present.
[0062] Next, one example of a method of manufacturing this
semiconductor device will be described. First, as shown in FIG. 2,
an assembly is prepared wherein: the connection pads 2 made of the
aluminum-based metal are provided on the upper surface of the
silicon substrate (hereinafter referred to as a wafer 1A) in a
wafer state; the insulating film 3 made of, for example, silicon
oxide, and the protective film 5 made of, for example,
polyimide-based resin are provided in a region of the upper
surfaces of the wafer 1A and the connection pads 2 except for the
centers of the connection pads 2; the foundation metal layers 7
made of, for example, copper is provided on the upper surface of
the protective film 5 including the upper surfaces of the
connection pads 2 exposed via the openings 4 and 6 provided in the
insulating film 3 and the protective film 5; the wiring lines 8
made of copper are respectively provided on the entire upper
surface of the foundation metal layers 7; and the columnar
electrodes 9 made of copper are provided on the upper surfaces of
the connection pad portions of the wiring line 8. In FIG. 2,
regions indicated by a numeral 13 correspond to dicing lines.
[0063] Next, as shown in FIG. 3, a first sealing film formation
film 10A made of, for example, liquid epoxy-based resin in which
any additional material as fillers is not mixed is formed by spin
coating described later around the columnar electrodes 9 on the
upper surface of the protective film 5 and the wiring lines 8 to
cover the wiring lines 8, so that a gap between the wiring lines 8
is completely filled with the synthetic resin film 10A, and so that
the upper surface of the first sealing film formation film 10A is
substantially flat. In this case, the first formation film 10A has
only to fill the gap between the wiring lines 8 and have a flat
upper surface, and the thickness of this film on the protective
film 5 is preferably about a few or several .mu.m. As the spin
coating is carried out in the atmosphere as described later, air is
caught into the first sealing film formation film 10A as air
bubbles. Therefore, the air bubbles caught in the first formation
film 10A are then removed by vacuum deaeration described later.
Next, as shown in FIG. 4, a second sealing film formation film 11A
made of the resin 11a such as liquid epoxy resin containing the
fillers 11b such as silica particles at 60 to 95 weight percent is
formed on the upper surface of the first formation film 10A and the
columnar electrodes 9 by screen printing described later so that
the upper surface of the second formation film 11A is slightly
higher than the upper surface of the columnar electrode 9.
Therefore, in this condition, the upper surfaces of the columnar
electrodes 9 are completely covered with the second formation film
11A.
[0064] In this case, the gap or space between the wiring lines 8 is
completely filled by the first formation film 10A. Thus, even when
the diameter of the filler 11b made of, for example, the silica
particle is larger than the distance between the wiring lines 8,
and the filler 11b is placed to extend over the adjacent wiring
lines 8, no space is formed between the adjacent wiring lines 8
under the placed filler 11b, thus ensuring that the production of
air bubbles due to this space can be prevented. Thus, even if the
second sealing film formation film 11A is formed by the resin 11a
containing the fillers 11b such as the silica particles, air
bubbles due to the fillers 11b can be prevented from remaining
between the wiring lines 8.
[0065] Since the above-mentioned screen printing is carried out in
the atmosphere as described later, air is caught into the second
formation film 11A as air bubbles. Therefore, the air bubbles
caught in the second formation film 11A are then removed by the
vacuum deaeration described later. Then, the first and second
formation films 10A and 11A are hardened by a thermal treatment to
form the first and second sealing films 10 and 11.
[0066] Next, the upper sides of the second sealing film 11 and the
columnar electrodes 9 are polished, such that the upper surfaces of
the columnar electrodes 9 are exposed, and the upper side of the
second sealing film 11 and the exposed upper sides of the columnar
electrodes 9 are planarized, as shown in FIG. 5. Then, as shown in
FIG. 6, the solder balls 12 are formed on the exposed upper
surfaces of the columnar electrodes 9. Then, as shown in FIG. 7,
the wafer 1A, the insulating film 3, the protective film 5 and the
first and second sealing films 10 and 11 are cut along the dicing
lines 13, thereby obtaining a plurality of semiconductor devices
shown in FIG. 1.
[0067] Next will be described a sealing film forming unit for
forming the first and second sealing films 10 and 11 of the
semiconductor device shown in FIG. 1. FIG. 8 is a schematic plan
view of one example of the sealing film forming unit, and FIG. 9 is
a schematic sectional view substantially along the IX-IX line in
FIG. 8. This sealing film forming unit is equipped with wafer
transferring means 21.
[0068] The wafer transferring mechanism or means 21 comprises a
vertical support shaft 22 disposed movably in a vertical direction
by a suitable driving mechanism. The proximal end of a first
horizontal arm 23 is pivotally attached to the upper surface of the
support shaft 22 via a pivot mechanism (not shown). The proximal
end of a second horizontal arm 24 is pivotally attached to the
upper surface of the distal end of the first arm 23 via a pivot
mechanism (not shown). The proximal end of a third horizontal arm
25 is pivotally attached to the upper surface of the distal end of
the second arm 24 via a pivot mechanism (not shown). The third arm
25 has a structure in which a vacuum suction mechanism (not shown)
described later for vacuum-sucking the wafer 1A on the upper
surface of the distal end of this third arm 25 is provided.
[0069] In FIGS. 8 and 9, a wafer cassette 26 is designed to be
disposed at a predetermined position in the vicinity of the left
side of the wafer transferring means 21. The wafer cassette 26 is
open in one side (right side) at which the wafers 1A are inserted
into the cassette 26 and taken out therefrom, The plurality of (in
FIG. 9, five for convenience) wafers 1A are horizontally kept and
placed at intervals in a vertical direction in the wafer cassette
26. The wafer 1A referred to here means a component in which the
columnar electrode 9 is provided on the upper surface of the
connection pad portion of each of the wiring lines 8 provided on
the wafer 1A, as shown in FIG. 2.
[0070] In FIG. 8, a spin coater 27 is disposed in the vicinity of
the upper side of the wafer transferring means 21 (in the drawing).
The spin coater 27 comprises a cup 28, as is also shown in FIG. 13.
A rotation vertical shaft 29 is inserted through the center of the
bottom of the cup 28 in a rotatable and vertically movable manner.
A spin coat stage 30 is provided at the top of the rotation shaft
29. The spin coat stage 30 is structured to have a vacuum suction
mechanism (not shown) for vacuum-sucking the wafer 1A on the upper
surface of the stage 30, and to have a plurality of, for example,
four support pins 31 which can appear on the upper side of this
stage and is movable in a vertical direction.
[0071] A resin drop nozzle arm 32 is disposed pivotally with its
support shaft 33 at a predetermined place outside the cup 28. An
edge rinse nozzle arm 34 is disposed pivotally with its support
shaft 35 at another predetermined place outside the cup 28. Then,
in an initial condition shown in FIG. 8, the spin coat stage 30 is
located at an upper limit position together with the rotation shaft
29, and the support pins 31 protrude from the upper surface of the
stage, and moreover, both of the nozzle arms 32 and 34 are located
outside the cup 28.
[0072] In FIGS. 8 and 9, a print stage 36 is disposed in the
vicinity of the right side of the wafer transferring means 21 (in
the drawing). The print stage 36 has a vacuum suction mechanism
(not shown) for vacuum-sucking the wafer 1A on the upper surface of
the stage 36, and has a plurality of, for example, four vertical
support pins 37 which can appear on the upper side of this stage.
In FIGS. 8 and 9, the print stage 36 is horizontally movable in
left and right directions. In the initial state shown in FIGS. 8
and 9, by a suitable driving means (not shown), the print stage 36
is located at a leftward movement limit position, and the support
pins 37 protrude from the upper surface of the stage.
[0073] In FIGS. 8 and 9, a metal mask 38 having a circular opening
39 is vertically (in a direction normal to the paper surface of the
drawing) movably disposed in the vicinity of the right side of the
print stage 36. A squeegee 40 is disposed on the upper side of the
metal mask 38 movably in a predetermined direction (right and left
directions in the drawing). Then, in the initial condition shown in
FIGS. 8 and 9, by a suitable driving means (not shown), the metal
mask 38 is located at an upper limit position together with the
squeegee 40.
[0074] In FIG. 8, a vacuum deaerating case 41 is provided in the
vicinity of the lower side of the wafer transferring means 21 (in
the drawing). The vacuum deaerating case 41 can be entirely sealed
when its door 42 is closed, and a vacuum is kept in the vacuum
deaerating case 41 during an unshown vacuum pump is driven. Inside
the vacuum deaerating case 41, a deaerating wafer cassette 43
having the same configuration as that of the wafer cassette 26 is
disposed so that its open one side is located on the side of the
door 42.
[0075] Next, the operation of this sealing film forming unit will
be described. First, as shown in FIGS. 8 and 9, the wafer cassette
26 is disposed at a predetermined position on the left side of the
wafer transferring means 21. In this case, a plurality of wafers 1A
are placed at intervals in the vertical direction in the wafer
cassette 26. Moreover, the door 42 of the vacuum deaerating case 41
is opened as indicated by a chain line in FIG. 8. In this case, no
wafer is placed in the deaerating wafer cassette 43.
[0076] Next, as shown in FIGS. 10 and 11, the support shaft 22 of
the wafer transferring means 21 is vertically moved, and the first
to third arms 23 to 25 properly move within a horizontal plane,
such that the distal end of the third arm 25 is located under the
center of the lower surface of the wafer 1A placed at the top in
the wafer cassette 26, and the center of the lower surface of the
wafer 1A is vacuum-sucked onto the upper surface of the distal end
of the third arm 25.
[0077] Next, as shown in FIGS. 12 and 13, the support shaft 22 and
the first to third arms 23 to 25 of the wafer transferring means 21
properly move such that the lower surface of the wafer 1A
vacuum-sucked onto the upper surface of the distal end of the third
arm 25 is positioned and mounted on the plurality of support pins
31 protruding on the upper side of the spin coat stage 30. Then,
the vacuum suction of the wafer 1A by the upper surface of the
distal end of the third arm 25 is cancelled.
[0078] Next, as shown in FIGS. 14 and 15, the first to third arms
23 to 25 of the wafer transferring means 21 properly move and are
located at initial positions shown in FIG. 8 in a planar view. The
plurality of support pins 31 protruding on the upper side of the
spin coat stage 30 descend and are completely inserted in the spin
coat stage 30 such that the wafer 1A is mounted and vacuum-sucked
onto a predetermined place or center of the upper surface of the
spin coat stage 30.
[0079] Next, as shown in FIG. 16, the spin coat stage 30 descends
by moving the rotation shaft 29 in a lower direction and is located
at a lower limit position. Then, the resin drop nozzle arm 32
rotates by the limited rotation of the support shaft 33, thus
bringing its distal end above the center of the wafer 1A
vacuum-sucked onto the upper surface of the spin coat stage 30.
Then, the shaft 29 is rotated to also rotate the spin coat stage 30
and thus the wafer 1A vacuum-sucked onto its upper surface, and a
predetermined amount of a liquid resin is dropped onto the center
of the wafer 1A from the distal end opening of the resin drop
nozzle arm 32, so that the liquid resin is spread over the wafer 1A
for forming the first formation film 10A on the entire upper
surface of the wafer 1A (see FIG. 3).
[0080] In this case, while the thickness (thickness on the
protective film 5 shown in FIG. 3) of the first formation film 10A
is determined by the viscosity of the liquid resin, a rotation
number, the amount of a solvent in the liquid resin, etc., it is
only necessary that the gap between the wiring lines 8 shown in
FIG. 3 be completely filled and the upper surface of the filled
material be flat, and the thickness of the first formation film 10A
is preferably about several .mu.m. Further, the viscosity of the
liquid resin is preferably 2000 cp or less. Moreover, in this case,
as the first formation film 10A is formed in the atmosphere, air is
caught into the second formation film 11A as air bubbles.
[0081] Next, as shown in FIG. 17, the resin drop nozzle arm 32 is
rotated by the support shaft 33 to return to an initial position
outside the cup 28. Then, the edge rinse nozzle arm 34 is rotated
by the support shaft 35b so that its distal end is located above
the peripheral part of the first formation film 10A on the wafer 1A
supported by the stage 30. Then, the stage and thus the wafer 1A
are rotated, and a rinse agent made of, for example, the same
solution as the solution in the liquid resin is supplied onto the
peripheral part of the first formation film 11A from the distal end
port of the edge rinse nozzle arm 34. Thus the peripheral part of
the first formation film 10A is removed, such that the peripheral
part on the wafer 1A is exposed for use in alignment in the
subsequent step. Thereafter, the edge rinse nozzle arm 34 is
rotated by the support shaft 35 to return to an initial position
outside the cup 28, and the rotation shaft 29 stops.
[0082] Next, as shown in FIGS. 18 and 19, the spin coat stage 30 is
moved in an upper direction by the rotation shaft 29, and is
located at an upper limit position. Then, the plurality of support
pins 31 are upwardly protruded from the upper surface of the spin
coat stage 30, so that the wafer 1A is properly lifted and
supported by the support pins 31 above the upper surface of the
spin coat stage 30. Then, the first to third arms 23 to 25 of the
wafer transferring means 21 are properly moved such that the distal
end of the third arm 25 is located under the center of the lower
surface of the wafer 1A supported by the plurality of support pins
31, and the center of the lower surface of the wafer 1A is
vacuum-sucked onto the upper surface of the distal end of the third
arm 25.
[0083] Next, as shown in FIG. 20, the support shaft 22 and the
first to third arms 23 to 25 of the wafer transferring means 21
properly move such that the distal end of the third arm 25 and thus
the wafer 1A thereon are transferred into the vacuum deaerating
case 41 and further into a predetermined place within the
deaerating wafer cassette 43, and then the wafer 1A vacuum-sucked
onto the upper surface of the distal end of the third arm 25 is
placed at the top (uppermost shelf) in the deaerating wafer
cassette 43. Then, the vacuum suction of the wafer 1A by the upper
surface of the distal end of the third arm 25 is cancelled.
[0084] Next, as shown in FIGS. 21 and 22, the support shaft 22 and
the first to third arms 23 to 25 of the wafer transferring means 21
are properly moved and located at the initial positions shown in
FIG. 8 in a planar view. In this case, the height of the support
shaft 22 is adjusted so that the distal end of the third arm 25 is
located at a position at which it is located under the next wafer
1A placed at the second position from the top in the wafer cassette
26.
[0085] Furthermore, the operation as described above is repeated,
such that the wafer 1A placed at the second position from the top
in the wafer cassette 26 is taken out, and the first sealing film
formation film 10A is formed on this wafer 1A taken out, and then
this wafer 1A is placed at the second position from the top in the
deaerating wafer cassette 43. Subsequently, similar operations are
repeated, such that the wafers 1A placed at the third and
subsequent positions from the top in the wafer cassette 26 are
sequentially taken out, and the first sealing film formation films
10A are formed on these wafers 1A taken out, and then these wafers
1A are placed at the third and subsequent positions from the top in
the deaerating wafer cassette 43.
[0086] Then, the door 42 is closed, so that the vacuum deaerating
case 41 is sealed. Further, the vacuum pump (not shown) is driven
to evacuate the inner space of the vacuum deaerating case 41,
thereby removing at a time air bubbles scattered within the first
formation films 10A on all the wafers 1A placed in the deaerating
wafer cassette 43. Then, the vacuum pump is stopped, and the air is
brought back into the vacuum deaerating case 41.
[0087] Here, the time for forming the first formation film 10A by
the spin coating is about 60 seconds at most, but the sum of
exhaust time by the vacuum pump and the time for bringing the air
back into the vacuum deaerating case 41 is relatively long and
about 3 to 20 minutes, so that deaerating the plurality of wafers
1A at a time can reduce the whole processing time.
[0088] Then, the door 42 is opened. Further, the support shaft 22
and the first to third arms 23 to 25 of the wafer transferring
means 21 are properly moved to sequentially take out all the wafers
1A placed in the deaerating wafer cassette 43, and these wafers 1A
taken out are returned to the original positions in the wafer
cassette 26.
[0089] Then, as shown in FIGS. 23 and 24, the support shaft 22 and
the first to third arms 23 to 25 of the wafer transferring means 21
are properly moved to locate the distal end of the third arm 25
under the center of the lower surface of the wafer 1A placed at the
top in the wafer cassette 26, and the center of the lower surface
of the wafer 1A is vacuum-sucked onto the upper surface of the
distal end of the third arm 25.
[0090] Then, as shown in FIGS. 25 and 26, the support shaft 22 and
the first to third arms 23 to 25 of the wafer transferring means 21
are properly moved such that the lower surface of the wafer 1A
vacuum-sucked onto the upper surface of the distal end of the third
arm 25 is positioned and mounted on the plurality of support pins
37 protruding on the upper side of the print stage 36. Then, the
vacuum suction of the wafer 1A by the upper surface of the distal
end of the third arm 25 is cancelled.
[0091] Next, as shown in FIGS. 27 and 28, the first to third arms
23 to 25 of the wafer transferring means 21 are properly moved and
located at the initial positions shown in FIG. 8 in a planar view.
Then, the plurality of support pins 37 protruding on the upper side
of the print stage 36 descend and are located within the print
stage 36 such that the wafer 1A is mounted and vacuum-sucked onto a
predetermined place of the upper surface of the print stage 36.
[0092] Next, as shown in FIG. 29, the print stage 36 is moved
rightward and located at a rightward movement limit position under
the metal mask 38 located at the upper limit position. In this
condition, a sealing material 44 made of a liquid resin containing
fillers is supplied, by unshown liquid resin supply means, to the
upper surface of the metal mask 38 on the right of the squeegee 40
located at a leftward movement limit position.
[0093] Next, as shown in FIG. 30, the metal mask 38 descends
together with the squeegee 40 by a suitable driving means, and the
lower surface of the metal mask 38 around the opening 39 is mounted
on the upper surface of the peripheral part of the wafer 1A
vacuum-sucked onto the print stage 36. In this case, the planar
size of the opening 39 of the metal mask 38 is the same as the
planar size of the first formation film 10A formed on the wafer 1A.
Thus, the first formation film 10A is disposed within the opening
39 of the metal mask 38.
[0094] Next, as shown in FIG. 31, the squeegee 40 is moved
rightward on the metal mask 38, such that the second formation film
11A made of the sealing material 44 is formed on the upper surface
of the first formation film 10A within the opening 39 of the metal
mask 38 (see FIG. 4). In this case, since the screen printing is
carried out in the atmosphere, air is caught into the second
formation film 11A as air bubbles.
[0095] Next, as shown in FIG. 32, the metal mask 38 ascends
together with the squeegee 40 back to the initial upper limit
position. In this case, the squeegee 40 moves leftward at an
appropriate point and returns to the initial leftward movement
limit position. Further, the print stage 36 is moved leftward and
returned to the initial leftward movement limit position.
[0096] Next, as shown in FIG. 33, the plurality of support pins 37
protrude onto the upper side of the print stage 36, and the wafer
1A is properly lifted by and supported on the support pins 37.
Then, the first to third arms 23 to 25 of the wafer transferring
means 21 are properly moved such that the distal end of the third
arm 25 is located under the center of the lower surface of the
wafer 1A supported by the plurality of support pins 37, and the
center of the lower surface of the wafer 1A is vacuum-sucked onto
the upper surface of the distal end of the third arm 25.
[0097] Next, as shown in FIG. 34, the support shaft 22 and the
first to third arms 23 to 25 of the wafer transferring means 21 are
properly moved such that the distal end of the third arm 25 moves
into the vacuum deaerating case 41 and further into a predetermined
place within the deaerating wafer cassette 43, and the wafer 1A
vacuum-sucked onto the upper surface of the distal end of the third
arm 25 is placed at the top in the deaerating wafer cassette 43.
Then, the vacuum suction of the wafer 1A onto the upper surface of
the distal end of the third arm 25 is cancelled.
[0098] Next, as shown in FIGS. 35 and 36, the support shaft 22 and
the first to third arms 23 to 25 of the wafer transferring means 21
are properly moved and located at the initial positions shown in
FIG. 8 in a planar view. In this case, the third arm 25 is located
at a position at which it can move onto the lower side of the wafer
1A placed at the second position from the top in the wafer cassette
26.
[0099] Furthermore, the operation as described above is repeated,
such that the wafer 1A placed at the second position from the top
in the wafer cassette 26 is taken out, and the second formation
film 11A is formed on the first formation film 10A on this wafer 1A
taken out, and then this wafer 1A is placed at the second position
from the top in the deaerating wafer cassette 43. Subsequently,
similar operations are repeated, such that the wafers 1A placed at
the third and subsequent positions from the top in the wafer
cassette 26 are sequentially taken out, and the second formation
films 11A are formed on the first formation films 10A on these
wafers 1A taken out, and then these wafers 1A are sequentially
placed at the third and subsequent positions from the top in the
deaerating wafer cassette 43.
[0100] Then, the door 42 is closed, and the vacuum deaerating case
41 is sealed. Further, the vacuum pump (not shown) is driven to
form a vacuum in the vacuum deaerating case 41, thereby removing at
a time air bubbles scattered within the second formation films 11A
on the plurality of wafers 1A placed in the deaerating wafer
cassette 43. Then, the vacuum pump is stopped, and the air is
brought back into the vacuum deaerating case 41.
[0101] Here, the time for forming the second formation film 11A by
the screen printing is about 60 seconds at most, but the sum of
exhaust time by the vacuum pump and the time for bringing the air
back into the vacuum deaerating case 41 is relatively long and
about 3 to 20 minutes, so that deaerating the plurality of wafers
1A at a time can reduce the whole processing time.
[0102] Then, the door 42 is opened. Further, the support shaft 22
and the first to third arms 23 to 25 of the wafer transferring
means 21 are properly moved to sequentially take out the plurality
of wafers 1A placed in the deaerating wafer cassette 43, and these
wafers 1A taken out are returned to the original positions in the
wafer cassette 26. Then, the wafer cassette 26 is transferred to a
thermal treatment unit (not shown) where the first and second
formation films 10A and 11A on the plurality of wafers 1A placed in
the deaerating wafer cassette 43 are hardened at a time by a
thermal treatment to form the first and second sealing films 10 and
11 (see FIG. 4).
[0103] When the second formation film 11A alone is formed without
forming the first formation film 11A in contrast to what has been
described above, the amount of air caught as air bubbles into the
second formation film 11A is large because the surface forming the
second formation film 11A is an uneven surface formed by the upper
surface of the protective film 5 including the wiring lines 8.
Thus, when the air bubbles which have reached and come out of the
surface of the second formation film 11A expand and vanish, a large
number of bubble traces which are crater-shaped depressions formed
on the surface of the second formation film 11A are produced and
may remain on the surface of the second sealing film 11 even after
the subsequent polishing step shown in FIG. 5, which leads to, for
example, the decrease of strength.
[0104] On the contrary, when the first formation film 10A is formed
and the second formation film 11A is formed on this first formation
film 10A, the amount of air caught as air bubbles into the second
formation film 11A is small because the upper surface of the first
formation film 10A is flat. Thus, when the air bubbles which have
reached and come out of the surface of the second formation film
11A expand and vanish, the production of bubble traces which are
crater-shaped depressions formed on the surface of the second
formation film 11A is reduced. After the subsequent polishing step
shown in FIG. 5, the rate of bubble traces remaining on the surface
of the second sealing film 11 can be decreased.
[0105] In the embodiment described above, a resin supply spray
nozzle capable of scanning in XY directions may be used instead of
the resin drop nozzle arm 32. In this case, the resin supply spray
nozzle scans in the XY directions with the wafer 1A in a fixed
state to apply the liquid resin, so that the edge rinse nozzle arm
34 can also be omitted if a portion of the peripheral part on the
wafer 1A for use in alignment in the subsequent step is covered
with a mask. Moreover, the vacuum deaerating case 41 may be
composed of a lower case and an upper case, and the upper case may
be vertically moved to open/close the vacuum deaerating case
41.
[0106] As described above, according to this invention, the first
sealing film formation film made of the liquid resin alone is
formed to fill the gap between the wiring lines, so that even if
the second sealing film formation film is formed by the liquid
resin containing the fillers such as the silica particles, air
bubbles due to the fillers can be prevented from remaining between
the wiring lines.
[0107] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *