U.S. patent application number 13/021856 was filed with the patent office on 2012-09-27 for method of fabricating semiconductor die with through-hole via on saw streets and through-hole via in active area of die.
This patent application is currently assigned to STATS CHIPPAC, LTD.. Invention is credited to Linda Pei Ee Chua, Byung Tai Do, Heap Hoe Kuan.
Application Number | 20120244661 13/021856 |
Document ID | / |
Family ID | 40586523 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120244661 |
Kind Code |
A9 |
Do; Byung Tai ; et
al. |
September 27, 2012 |
Method of Fabricating Semiconductor Die with Through-Hole Via on
Saw Streets and Through-Hole Via in Active Area of Die
Abstract
A semiconductor wafer contains a plurality of die with contact
pads disposed on a first surface of each die. Metal vias are formed
in trenches in the saw street guides and are surrounded by organic
material. Traces connect the contact pads and metal vias. The metal
vias can be half-circle vias or full-circle vias. Metal vias are
also formed through the contact pads on the active area of the die.
Redistribution layers (RDL) are formed on a second surface of the
die opposite the first surface. Repassivation layers are formed
between the RDL for electrical isolation. The die are stackable and
can be placed in a semiconductor package with other die. The vias
through the saw streets and vias through the active area of the
die, as well as the RDL, provide electrical interconnect to the
adjacent die.
Inventors: |
Do; Byung Tai; (Singapore,
SG) ; Kuan; Heap Hoe; (Singapore, SG) ; Chua;
Linda Pei Ee; (Singapore, SG) |
Assignee: |
STATS CHIPPAC, LTD.
Singapore
SG
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20110124156 A1 |
May 26, 2011 |
|
|
Family ID: |
40586523 |
Appl. No.: |
13/021856 |
Filed: |
February 7, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11861251 |
Sep 25, 2007 |
7902638 |
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13021856 |
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11768844 |
Jun 26, 2007 |
7723159 |
|
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11861251 |
|
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11744657 |
May 4, 2007 |
7569421 |
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11768844 |
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Current U.S.
Class: |
438/107 ;
257/E21.499; 257/E21.602; 438/462 |
Current CPC
Class: |
H01L 24/82 20130101;
H01L 2224/04105 20130101; H01L 2224/48145 20130101; H01L 2225/06506
20130101; H01L 2224/48472 20130101; H01L 2224/2101 20130101; H01L
2225/06513 20130101; H01L 2224/48472 20130101; H01L 25/0657
20130101; H01L 2924/01074 20130101; H01L 2224/16227 20130101; H01L
2224/221 20130101; H01L 24/81 20130101; H01L 2224/73204 20130101;
H01L 2224/73265 20130101; H01L 2224/73265 20130101; H01L 2924/00014
20130101; H01L 2924/19107 20130101; H01L 2224/48091 20130101; H01L
2224/18 20130101; H01L 21/568 20130101; H01L 2224/16225 20130101;
H01L 2924/30105 20130101; H01L 2924/00014 20130101; H01L 2924/01023
20130101; H01L 2924/181 20130101; H01L 2924/18162 20130101; H01L
2224/16145 20130101; H01L 21/76898 20130101; H01L 24/73 20130101;
H01L 2924/181 20130101; H01L 2924/01013 20130101; H01L 2924/15311
20130101; H01L 2224/48227 20130101; H01L 24/48 20130101; H01L
2924/01033 20130101; H01L 2225/06527 20130101; H01L 2924/014
20130101; H01L 2224/215 20130101; H01L 2224/73204 20130101; H01L
2224/215 20130101; H01L 25/50 20130101; H01L 21/6835 20130101; H01L
2924/01029 20130101; H01L 2924/01078 20130101; H01L 24/19 20130101;
H01L 23/3128 20130101; H01L 2224/73265 20130101; H01L 2224/73265
20130101; H01L 2224/73265 20130101; H01L 2224/32225 20130101; H01L
2224/81801 20130101; H01L 2224/32145 20130101; H01L 2224/73267
20130101; H01L 2224/48472 20130101; H01L 2924/00014 20130101; H01L
2224/48091 20130101; H01L 2224/73204 20130101; H01L 2924/01005
20130101; H01L 2224/82039 20130101; H01L 2224/12105 20130101; H01L
2924/14 20130101; H01L 2224/32225 20130101; H01L 2224/45015
20130101; H01L 2224/48227 20130101; H01L 2224/45099 20130101; H01L
2224/32145 20130101; H01L 2224/48227 20130101; H01L 2224/73265
20130101; H01L 2924/00012 20130101; H01L 2924/01029 20130101; H01L
2224/48145 20130101; H01L 2924/00 20130101; H01L 2924/00012
20130101; H01L 2224/32225 20130101; H01L 2924/00 20130101; H01L
2224/48227 20130101; H01L 2224/48227 20130101; H01L 2224/48227
20130101; H01L 2924/00 20130101; H01L 2924/00 20130101; H01L
2924/00014 20130101; H01L 2224/48091 20130101; H01L 2924/207
20130101; H01L 2224/32145 20130101; H01L 2224/32225 20130101; H01L
2224/16225 20130101; H01L 2924/00 20130101; H01L 2224/48227
20130101; H01L 2924/00 20130101; H01L 2224/16145 20130101; H01L
2924/00 20130101; H01L 2224/32225 20130101; H01L 2924/00 20130101;
H01L 2224/48227 20130101; H01L 25/03 20130101; H01L 2224/32145
20130101; H01L 2224/48145 20130101; H01L 2225/06541 20130101; H01L
2924/15311 20130101; H01L 2924/01006 20130101; H01L 2224/48472
20130101; H01L 23/481 20130101 |
Class at
Publication: |
438/107 ;
438/462; 257/E21.602; 257/E21.499 |
International
Class: |
H01L 21/82 20060101
H01L021/82; H01L 21/50 20060101 H01L021/50 |
Claims
1. A method of forming a semiconductor device, comprising: forming
a semiconductor wafer having active areas separated from each other
by saw street guides; forming contact pads on a first surface of
the semiconductor wafer within the active areas; forming a trench
in the saw street guides; filling the trench with organic material;
forming first vias in the organic material; forming second vias
through the contact pads on the active area of the die; forming
conductive traces between the contact pads and first vias;
depositing conductive material in the first vias and second vias to
form first conductive vias and second conductive vias,
respectively; and singulating the semiconductor wafer along the saw
street guides to separate the active areas of the semiconductor
wafer into die.
2. The method of claim 1, further including: forming redistribution
layers (RDLs) on a second surface of the semiconductor wafer that
is opposite the first surface; and forming repassivation layers
between the RDLs.
3. The method of claim 1, further comprising: stacking the die; and
electrically interconnecting the die using the first and second
conductive vias.
4. The method of claim 1, wherein forming first vias in the organic
material comprises forming at least one of the first vias directly
between a first contact pad disposed in a first active area and a
second contact pad disposed in a second active area adjacent to the
first active area.
5. The method of claim 4, wherein singulating the semiconductor
wafer along the saw street guides comprises dicing through one of
the first conductive vias that is disposed in the at least one of
the first vias to form a third conductive via that is electrically
connected to the first contact pad by a first conductive trace and
a fourth conductive via that is electrically connected to the
second contact pad by a second conductive trace.
6. The method of claim 1, wherein forming first vias in the organic
material comprises forming two of the first vias side by side and
directly between a first contact pad disposed in a first active
area and a second contact pad disposed in a second active area
adjacent to the first active area.
7. The method of claim 6, wherein singulating the semiconductor
wafer along comprises cutting the semiconductor wafer between two
of the first conductive vias that are disposed in the two of the
first vias.
8. A method of fabricating a semiconductor package, comprising:
forming a semiconductor wafer including die, contact pads disposed
on first surfaces of the die, first conductive vias disposed
outside a perimeter of the die, second conductive vias disposed in
the die, and conductive traces electrically connecting the first
conductive vias to the contact pads; forming redistribution layers
(RDLs) on second surfaces of the die opposite the first surfaces;
forming repassivation layers between the RDLs on the second surface
of the die; singulating the semiconductor wafer to separate the
die; stacking the die; and electrically interconnecting the stacked
die using the first and second conductive vias.
9. The method of claim 8, wherein singulating the semiconductor
wafer comprises cutting through at least one of the first
conductive vias to form a third conductive via electrically
connected to a first contact pad by a first conductive trace and a
third conductive via electrically connected to a second contact pad
by a second conductive trace.
10. The semiconductor package of claim 8, wherein two of the first
conductive vias are formed side by side and directly between a
first contact pad disposed on a first die and a second contact pad
disposed on a second die adjacent to the first die.
11. The semiconductor package of claim 10, wherein singulating the
semiconductor wafer comprises cutting along a saw street guide
disposed between the two of the first conductive vias.
12. A method of fabricating a semiconductor package, comprising:
providing a first die having contact pads and first conductive vias
formed along a perimeter of the die, the first conductive vias
electrically connected to the contact pads by conductive traces,
the first die further including second conductive vias formed
through an active area of the die; providing a second die disposed
adjacent to the first die; and electrically connecting the first
and second die using bond wires and the first conductive vias.
13. The method of claim 12, wherein two of the first conductive
vias are formed side by side.
14. The method of claim 13, further comprising singulating the
semiconductor wafer along a saw street guide disposed between the
two of the first conductive vias.
15. A method of fabricating a semiconductor device, comprising:
providing a semiconductor wafer including die and contact pads
disposed on a first surface of an active area of each die, the
semiconductor wafer further including a saw street guide between
each die; forming a trench in the saw street guide; filling the
trench with an organic material; forming first conductive vias that
are surrounded by the organic material; forming second conductive
vias in the active area of the die; and connecting the contact pads
and the first conductive vias using conductive traces.
16. The method of claim 15, further including: forming
redistribution layers (RDLs) on a second surface of the die
opposite the first surface; and forming repassivation layers
between the RDLs on the second surface of the die.
17. The method of claim 15, further comprising: stacking the die;
electrically interconnecting the stacked die using the first and
second conductive vias.
18. The method of claim 15, wherein at least one of the first
conductive vias is formed directly between a first contact pad
disposed on a first die and a second contact pad disposed on a
second die that is adjacent to the first die.
19. The method of claim 18, further comprising singulating the
semiconductor wafer through the at least one of the first
conductive vias to form a third conductive via that is electrically
connected to the first contact pad by a first conductive trace and
to form a fourth conductive via that is electrically connected to
the second contact pad by a second conductive trace.
20. The method of claim 15, wherein two of the first conductive
vias are formed side by side and directly between a first contact
pad disposed on a first die and a second contact pad disposed on a
second die that is adjacent to the first die.
21. The method of claim 20, further comprising singulating the
semiconductor wafer along a saw street guide disposed between the
two of the first conductive vias.
22. The method of claim 15, further comprising forming conductive
bumps that are electrically connected to the RDL.
Description
CLAIM TO DOMESTIC PRIORITY
[0001] The present invention is a division of U.S. patent
application Ser. No. 11/861,251, filed Sep. 25, 2007, and claims
priority to the foregoing parent application pursuant to 35 U.S.C.
.sctn.120.
FIELD OF THE INVENTION
[0002] The present invention relates in general to semiconductor
packaging and, more particularly, to stackable semiconductor die
having through-hole vias formed along saw streets and through-hole
vias on the active silicon area of the die.
BACKGROUND OF THE INVENTION
[0003] Semiconductor devices are found in many products used in
modern society. Semiconductors find applications in consumer items
such as entertainment, communications, networks, computers, and
household items markets. In the industrial or commercial market,
semiconductors are found in military, aviation, automotive,
industrial controllers, and office equipment.
[0004] The manufacture of semiconductor devices involves formation
of a wafer having a plurality of die. Each die contains hundreds or
thousands of transistors and other active and passive devices
performing a variety of electrical functions. For a given wafer,
each die from the wafer typically performs the same electrical
function. Front-end manufacturing generally refers to formation of
the semiconductor devices on the wafer. The finished wafer has an
active side containing the transistors and other active and passive
components. Back-end manufacturing refers to cutting or singulating
the finished wafer into the individual die and then packaging the
die for structural support and/or environmental isolation.
[0005] Semiconductor manufacturers are increasingly adopting
packaging techniques which involve three-dimensional (3D)
interconnects between the semiconductor devices. The 3D
interconnects provide advantages such as size reduction, reduced
interconnect length, and integration of devices with different
functionality into an overall 3D package. One way of implementing
3D interconnects involves the use of through-hole vias (THV). THVs
are typically located around the perimeter of the die along its saw
street guides. Most, if not all, semiconductor packages use the
THVs to route signals between adjacent die. However, THVs on saw
streets alone limit signal routing options and reduce signal
routing density. Present day high density packaging require high
density and flexible interconnect capability, which is difficult to
achieve through the THVs on saw streets.
[0006] A need exists to increase signal routing options and density
in a semiconductor wafer having THVs.
SUMMARY OF THE INVENTION
[0007] In one embodiment, the present invention is a method of
forming a semiconductor device comprising forming a semiconductor
wafer having active areas separated from each other by saw street
guides, forming contact pads on a first surface of the
semiconductor wafer within the active areas, and forming a trench
in the saw street guides. The method further comprises filling the
trench with organic material, forming first vias in the organic
material, and forming second vias through the contact pads on the
active area of the die. The method further comprises forming
conductive traces between the contact pads and first vias,
depositing conductive material in the first vias and second vias to
form first conductive vias and second conductive vias,
respectively, and singulating the semiconductor wafer along the saw
street guides to separate the active areas of the semiconductor
wafer into die.
[0008] In another embodiment, the present invention is a method of
fabricating a semiconductor package comprising forming a
semiconductor wafer including die, contact pads disposed on first
surfaces of the die, first conductive vias disposed outside a
perimeter of the die, second conductive vias disposed in the die,
and conductive traces electrically connecting the first conductive
vias to the contact pads. The method further comprises forming
redistribution layers (RDLs) on second surfaces of the die opposite
the first surfaces, forming repassivation layers between the RDLs
on the second surface of the die, and singulating the semiconductor
wafer to separate the die. The method further comprises stacking
the die, and electrically interconnecting the stacked die using the
first and second conductive vias.
[0009] In yet another embodiment, the present invention is a method
of fabricating a semiconductor package comprising providing a first
die having contact pads and first conductive vias formed along a
perimeter of the die. The first conductive vias are electrically
connected to the contact pads by conductive traces, and the first
die further includes second conductive vias formed through an
active area of the die. The method further comprises providing a
second die disposed adjacent to the first die, and electrically
connecting the first and second die using bond wires and the first
conductive vias.
[0010] In still another embodiment, the present invention is a
method of fabricating a semiconductor device comprising providing a
semiconductor wafer including die and contact pads disposed on a
first surface of an active area of each die. The semiconductor
wafer includes a saw street guide between each die. The method
further includes forming a trench in the saw street guide, filling
the trench with an organic material, and forming first conductive
vias that are surrounded by the organic material. The method
further comprises forming second conductive vias in the active area
of the die, and connecting the contact pads and the first
conductive vias using conductive traces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIGS. 1a-1b illustrate top and side views of a semiconductor
wafer having a plurality of die separated by saw street guides;
[0012] FIGS. 2a-2b illustrate top and side views of the
semiconductor wafer with trenches formed in the saw street
guides;
[0013] FIGS. 3a-3b illustrate top and side views of expanding the
saw street guides;
[0014] FIGS. 4a-4b illustrate top and side views of the expanded
saw streets filled with organic material;
[0015] FIGS. 5a-5b illustrate top and side views of forming via
holes through the organic material in the saw streets and via holes
in an active area of the die;
[0016] FIGS. 6a-6b illustrate top and side views of depositing
conductive material in the via holes;
[0017] FIGS. 7a-7b illustrate top and side views of cutting the
metal vias on the saw streets into two half-circle vias;
[0018] FIGS. 8a-8b illustrate top and side views of a semiconductor
die with metal vias formed along the saw streets and metal vias
formed in the active area of the die;
[0019] FIGS. 9a-9b illustrate top and side views of a semiconductor
die with redistribution layers formed on a backside of the die;
[0020] FIGS. 10a-10b illustrate top and side views of two
side-by-side metal vias formed along the saw streets;
[0021] FIGS. 11a-11b illustrate top and side views of cutting the
organic material between the two side-by-side metal vias to
separate the die;
[0022] FIGS. 12a-12b illustrate top and side views of a
semiconductor die with full-circle vias along the saw streets and
vias formed in the active area of the die;
[0023] FIG. 13 illustrates die-to-die stacking using direct
metal-to-metal via bonding;
[0024] FIG. 14 illustrates die-to-die stacking using via bonding
with solder paste;
[0025] FIG. 15 illustrates the semiconductor die with metal vias
connected to a second die with wire bonds;
[0026] FIG. 16 illustrates the semiconductor die with metal vias
connected to a second die with bond wires and solder bumps;
[0027] FIG. 17 illustrates another embodiment of interconnecting
die using metal vias on saw streets and metal vias in the active
area of the die; and
[0028] FIG. 18 illustrates another embodiment of interconnecting
die using metal vias on saw streets and metal vias in the active
area of the die.
DETAILED DESCRIPTION OF THE DRAWINGS
[0029] The present invention is described in one or more
embodiments in the following description with reference to the
Figures, in which like numerals represent the same or similar
elements. While the invention is described in terms of the best
mode for achieving the invention's objectives, it will be
appreciated by those skilled in the art that it is intended to
cover alternatives, modifications, and equivalents as may be
included within the spirit and scope of the invention as defined by
the appended claims and their equivalents as supported by the
following disclosure and drawings.
[0030] The manufacture of semiconductor devices involves formation
of a wafer having a plurality of die. Each die contains hundreds or
thousands of transistors and other active and passive devices
performing one or more electrical functions. For a given wafer,
each die from the wafer typically performs the same electrical
function. Front-end manufacturing generally refers to formation of
the semiconductor devices on the wafer. The finished wafer has an
active side containing the transistors and other active and passive
components. Back-end manufacturing refers to cutting or singulating
the finished wafer into the individual die and then packaging the
die for structural support and/or environmental isolation.
[0031] A semiconductor wafer generally includes an active front
side surface having semiconductor devices disposed thereon, and a
backside surface formed with bulk semiconductor material, e.g.,
silicon. The active front side surface contains a plurality of
semiconductor die. The active surface is formed by a variety of
semiconductor processes, including layering, patterning, doping,
and heat treatment. In the layering process, semiconductor
materials are grown or deposited on the substrate by techniques
involving thermal oxidation, nitridation, chemical vapor
deposition, evaporation, and sputtering. Patterning involves the
use of photolithography to mask areas of the surface and etch away
undesired material to form specific structures. The doping process
injects concentrations of dopant material by thermal diffusion or
ion implantation. The active surface is substantially planar and
uniform with electrical interconnects, such as bond pads.
[0032] Flip chip semiconductor packages and wafer level chip scale
packages (WLP) are commonly used with integrated circuits (ICs)
demanding high speed, high density, and greater pin count. Flip
chip style packaging involves mounting an active area of the die
facedown toward a chip carrier substrate or printed circuit board
(PCB). The active area contains active and passive devices,
conductive layers, and dielectric layers according to the
electrical design of the die. The electrical and mechanical
interconnect is achieved through a solder bump structure comprising
a large number of individual conductive solder bumps or balls. The
solder bumps are formed on the bump pads which are disposed on the
active area. The bump pads connect to the active circuits by
conduction tracks or traces in the active area. The solder bumps
are electrically and mechanically connected to the contact pads on
the carrier substrate by a solder reflow process. The flip chip
semiconductor package provides a short electrical conduction path
from the active devices on the die to conduction tracks on the
carrier substrate in order to reduce signal propagation, lower
capacitance, and achieve overall better circuit performance.
[0033] In the present discussion, a WLP is provided having
through-hole vias (THV) formed along saw streets. The backside of
the wafer has redistribution layers (RDL) for interconnect
flexibility separated by repassivation layers. WLP with THV formed
along saw streets are described in U.S. patent application Ser. No.
11/744,657, entitled "Through-Hole Via on Saw Streets", and further
in U.S. patent application Ser. No. 11/768,844, entitled "Package
on Package Using Through-Hole Via Die on Saw Streets", which are
incorporated herein by reference.
[0034] Turning to FIG. 1a, a semiconductor wafer 30 is shown having
a plurality of die 32. The die are separated by inter die wafer
area 36, commonly known as saw street guides. The saw street guides
are routed around the wafer such that there is a saw street on
every side of each die on the wafer, i.e., around a perimeter of
the die. Each die 32 has a plurality to contact pads 38 formed on
silicon, i.e., formed in an active area of die 32 and not in saw
street guides 36. Contact pads 38 are made of aluminum, copper, or
aluminum/copper alloys. Contact pads 38 electrically connect to
active and passive devices through conduction tracks or layers
formed on die 32. The contact pads can be disposed side-by-side a
first distance from the edge of the die, as shown in FIG. 1a.
Alternately, the contact pads can be offset in multiple rows such
that a first row of contact pads are disposed a first distance from
the edge of the die, and a second row of contact pads alternating
with the first row are disposed a second distance from the edge of
the die. A solder bump or wire bond will later be formed to connect
to each metal contact pad for electrical and mechanical
interconnect to a chip carrier substrate or printed circuit board
(PCB).
[0035] FIG. 1b is a cross-sectional view of wafer 30, taken along
line 1b-1b in FIG. 1a, showing die 32 separated by saw street
guides 36. In one embodiment, die 32 may have dimensions ranging
from 2.times.2 millimeters (mm) to 15.times.15 mm. The saw streets
provide cutting areas to singulate the wafer into individual die. A
first die 32 is disposed to the left of the leftmost saw street 36.
A second die 32 is disposed between the saw streets 36. A third die
32 is disposed to the right of the rightmost saw street 36. Once
the wafer is singulated, each set of contact pads disposed on the
respective die will provide the electrical and mechanical
interconnect for that die.
[0036] In FIG. 2a, semiconductor wafer 30 is again shown with its
plurality of die 32, separated by saw street guides 36. Dicing tape
40 is applied to the back of semiconductor wafer 30 for structural
support of the wafer during the following manufacturing operations,
as shown in FIG. 2b which is a cross-sectional view taken along
line 2b-2b. Saw streets 36 are cut by cutting tool 44. In one
embodiment, cutting tool 44 can be a saw or laser. Note that the
cutting tool completely severs through wafer 30 to form a well or
trench 42. The bottom of trench 42 is defined by dicing tape 40.
The formation of trench 42 arises from a first singulation of wafer
30, which creates a trench width that is less than a width of the
channel of saw street guide 36.
[0037] In FIG. 3a, semiconductor wafer 30 is shown with its
plurality of die 32, separated by cut saw street guides 36. Wafer
30 undergoes a wafer expansion step to increase the width of saw
street guides 36. FIG. 3b is a cross-sectional view of wafer 30,
taken along line 3b-3b, showing the die being pulled using a wafer
expansion table as shown by directional arrows 46. Alternately, the
die can be picked and placed onto a wafer support system. In any
case, the die are positioned farther apart following the steps of
FIGS. 3a-3b to create wider saw street guides. In one embodiment,
the die separation increases from 50 micrometers (.mu.m) to 200
.mu.m. The expanded dimension depends on the design embodiment,
i.e. half via, full via, single row via, or double/multiple row
via.
[0038] In FIG. 4a, semiconductor wafer 30 is shown with its
plurality of die 32, separated by cut saw street guides 36. Organic
material 48 is deposited in trench 42 by spin-coating or needle
dispensing. Organic material 48 can be benzocyclobutene (BCB),
polyimide (PI), or acrylic resin. FIG. 4b is a cross-sectional view
of wafer 30, taken along line 4b-4b, showing organic material 48
deposited in trench 42. Organic material 48 fills trench 42 from
dicing tape 40 up to the top surface of die 32. The backside of
wafer 30 is transferred onto wafer support system 49, which is made
from glass, silicon substrate, or other wafer support material.
[0039] In FIG. 5a, semiconductor wafer 30 is shown with its
plurality of die 32, separated by saw street guides 36 filled with
organic material 48. A via hole 50 is cut into organic material 48
along saw streets 36. The via cutting operation uses a laser drill
or etching process. Via holes 50 are placed along die 32 adjacent
to contact pads 38. In one embodiment, contact pads 38 and via
holes 50 have a minimum separation distance of about 20 .mu.m to
150 .mu.m, depending on the diameter and depth of the via.
[0040] In FIG. 5b, the cross-sectional view of wafer 30, taken
along line 5b-5b, shows via holes 50 cut into organic material 48
down to wafer support system 49. The laser drilling operation is
centered about the channel of the saw street guide and makes a hole
having a diameter less than the width of trench 42, which leaves a
layer of organic material 48 surrounding via hole 50. The width of
trench 42 is dependent on the width of saw street width, but
typically smaller than the saw street width. The diameter of via
hole 50 is typically about 10 .mu.m to 100 .mu.m, depending on the
required via depth. In addition, via holes 53 are cut through
contact pads 38 down through wafer 30 to wafer support system 49.
The laser drilling operation is centered about contact pad 38 and
makes a hole having a diameter less than the width of the contact
pad, which leaves part of the contact pad surrounding via hole 53
at the top of die 32. Note that via holes 53 are formed on silicon,
i.e., through an active area of die 32.
[0041] A metal track or trace 52 is routed from each contact pad 38
to the corresponding via hole 50. Trace 52 is formed by a metal
patterning process to connect contact pads 38 to via holes 50,
which will be filled with conductive material in a later step.
Traces 52 are provided for each contact pad and via hole pairing as
shown. Some via holes 50 are dummy vias performing no electrical
function. Accordingly, metal trace 52 need not be routed to every
via depending on the device function.
[0042] In FIG. 6a, semiconductor wafer 30 is shown with its
plurality of die 32, separated by saw street guides 36 with
metal-filled vias 54 and 56. A conductive material is deposited
into via holes 50 through a deposition process such as plating or
plugging to form metal vias 54. The same conductive material is
also deposited into via holes 53 to form metal vias 56. Metal vias
56 are formed through an active area of die 32. The conductive
material can be copper (Cu), aluminum (Al), tungsten (W), or alloys
thereof, or mixtures of other conductive materials. Metal vias 54
are formed in and are surrounded by organic material 48. Metal vias
56 are formed in and are surrounded by contact pad 38 and the
active area of wafer 30. Metal via 54 electrically connects to
contact pad 38 by way of trace 52. Traces 52 are provided for each
contact pad and metal via pairing as shown. FIG. 6b is a
cross-sectional view of wafer 30, taken along line 6b-6b, showing
metal vias 54 electrically connecting to contact pads 38 through
traces 52, and metal vias 56 electrically connecting to contact
pads 38 directly. Wafer support system 49 is replaced with dicing
tape 58 for structural support of the wafer during the second or
final singulation to separate die 32. The bottom of metal vias 54
and 56 coincides with dicing tape 58.
[0043] A redistribution layer (RDL) can be formed on the backside
of wafer 30. The backside RDL operates as an intermediate
conductive layer to route electrical signals to various areas of
the die, including active and passive circuits, and provides
various electrical interconnect options during package integration,
such as shown in FIGS. 15-18. A repassivation layer is formed
between the individual nodes of the backside RDL for electrical
isolation. The formation of backside RDL and repassivation layer is
disclosed in U.S. Patent Application No. (Pending), Attorney Docket
No. 125155.00033, entitled "Semiconductor Wafer having Through Hole
Vias on Saw Streets with backside redistribution layer."
[0044] In FIGS. 7a-7b, metal vias 54 are cut through center area 68
by cutting tool 70. In one embodiment, cutting tool 70 can be a saw
or laser. The cut extends down to dicing tape 58 to completely
sever metal vias 54 into two equal half-circle vias 64. A pick and
place operation removes die 32 as individual units from dicing tape
58.
[0045] In FIG. 8a, semiconductor die 32 is shown with both metal
vias 64 on saw streets and through silicon metal vias 56. FIG. 8b
is a cross-sectional view of die 32, taken along line 8b-8b,
showing metal vias formed through silicon of die 32 and metal vias
on saw street configuration, as produced by the manufacturing steps
of FIGS. 1-7.
[0046] In FIG. 9a, semiconductor die 32 is shown with through
silicon metal vias 56 and further metal vias 64 on saw streets.
FIG. 9b is a cross-sectional view of die 32, taken along line
9b-9b, showing metal vias formed through silicon of die 32 and
metal vias on saw street configuration, as produced by the
manufacturing steps of FIGS. 1-7. RDL 74 and repassivation layer 76
are shown on the backside of die 32. RDL 74 can be made with nickel
(Ni), nickel vanadium (NiV), Cu, or Cu alloy. RDL 74 operates as an
intermediate conductive layer to route electrical signals to
various areas of the die, including active and passive circuits,
and provides various electrical interconnect options during package
integration, such as shown in FIGS. 15-18. Repassivation layer 76
is formed between the individual nodes of backside RDL 74 for
electrical isolation. The repassivation layer can be made with
silicon nitride (SiN), silicon dioxide (SiO2), silicon oxynitride
(SiON), polyimide, benzocyclobutene (BCB), polybenzoxazole (PBO),
or other insulating material.
[0047] In FIG. 10a, semiconductor die 32 is shown with contact pads
38 connected to metal vias 80 by traces 52. FIG. 10b is a
cross-sectional view of die 32, taken along line 10b-10b, showing
metal vias 80 along saw street 36. The metal via is produced by the
steps described in FIGS. 1-7, with the exception that two via holes
like 50 are formed side-by-side in organic material 48. The
side-by-side via holes 50 are separated by organic material 48.
Conductive traces 52 connect contact pads 38 and via holes 50. The
side-by-side via holes are filled with conductive material to form
metal vias 80.
[0048] In FIG. 11a, semiconductor die 32 is shown with contact pads
38 connected to metal vias 80 by traces 52. Dicing tape is applied
to the back of semiconductor wafer 30 for structural support of the
wafer during the final singulation to separate die 32, as shown in
FIG. 11b which is a cross-sectional view taken along line 11b-11b.
The second or final singulation to separate the plurality of die 32
is cut through organic material 48 along line 82 between the
side-by-side vias 80 with a cutting tool like 70. The singulation
between metal vias 80 results in the metal vias on saw street
configuration in combination with through silicon vias 56.
[0049] In FIG. 12a, semiconductor die 32 is shown with contact pads
38 connected to metal vias 80 by traces 52. FIG. 12b is a
cross-sectional view of die 32, taken along line 12b-12b, showing
metal vias on saw street configuration. The metal full-circle vias
are produced by the steps described in FIGS. 1-7 and 10-11. The
side-by-side via holes like 50 are separated by organic material
48. Conductive traces like 52 electrically connect the contact pads
and via holes. The side-by-side via holes are filled with
conductive material to form metal vias 80. The final singulation to
separate the plurality of die 32 is cut through organic material 48
between the side-by-side metal vias 80 resulting in the metal via
on saw street configuration in combination with through silicon
vias 56.
[0050] FIG. 13 illustrates direct die-to-die stacking using direct
via metal bonding. A plurality of die 32 is stacked as shown to
suit a particular application. Each of the metal half-vias 64 and
through silicon vias 56 can be joined together as shown by union 90
using a direct via metal bonding process. The combination of vias
64 and 56 provide greater interconnect flexibility and options for
electrically connecting the stacked die 32. Alternately,
semiconductor die 32 with metal full-vias 80 and through silicon
vias 56 can be joined together by union 90 using a direct via metal
bonding process.
[0051] FIG. 14 illustrates die-to-die stacking using via bonding
with solder paste 92. A plurality of die 32 is stacked as shown to
suit a particular application. Each of the metal vias 64 and
through silicon vias 56 can be joined together as shown by
reflowing solder paste 92 to create a strong metallurgical bond
between each of stacked die 32. The combination of vias 64 and 56
provide greater interconnect flexibility and options for
electrically connecting the stacked die 32. Alternately,
semiconductor die 32 with metal vias 80 and through silicon vias 56
can be joined together by solder paste 92 using a reflow
process.
[0052] In FIGS. 15-18 shows various packaging applications using,
in part, an interconnect technique with the THVs formed on saw
streets and THVs on silicon. FIG. 15 has semiconductor die 100
attached to die 32 with adhesive 102. Die 100 electrically connects
through wire bonds 104 to metal vias 64 on die 32. Die 32 is
supported by substrate 106. Metal vias 64 and 56 electrically
connect to solder bumps 108 through conductive layer 110. The
packages are sealed by epoxy encapsulant 112.
[0053] FIG. 16 shows semiconductor die 120 attached to die 122 with
adhesive 124. Die 120 electrically connects through wire bonds 126
to metal vias 64 on die 32. Die 122 electrically connects through
solder bumps 128 to metal vias 56 on die 32. Die 32 is supported by
substrate 130. Metal vias 64 and 56 electrically connect to solder
bumps 132 through conductive layer 134. The packages are sealed by
epoxy encapsulant 136.
[0054] FIG. 17 shows semiconductor die 140 electrically connected
to metal vias 64 or 80 on die 32 by way of bond wires 152.
Semiconductor die 154 electrically connects to metal vias 64 and 56
on die 32 by way of wire bonds 156 and conductive layer 158. Die 32
and 140 are supported by substrate 160. The entire assembly is
mounted to substrate 161. Wire bonds 162 from substrate 160 provide
the electrical connection to solder bumps 164 through conductive
layer 166. The packages are encased by epoxy encapsulant 168.
Molding compound 170 encapsulates die 154.
[0055] FIG. 18 shows semiconductor die 180 electrically connected
to die 32 with solder bumps 182. Passive devices 184 also connect
to metal vias 64 with solder paste 186. Die 32 is mounted to a
semiconductor package containing die 190 with adhesive 192. Die 190
electrically connects to solder bumps 200 through wire bonds 194,
conductive layer 196, and conductive layer 198. The assembly of
semiconductor die 32, 180, and 190 are supported by substrate 202.
Metal vias 56 electrically connect to solder bumps 200 through wire
bonds 204 and conductive layer 198. The packages are sealed by
epoxy encapsulant 206. An underfill material 208 provides stress
relief.
[0056] In summary, stackable semiconductor die has been described
with THVs formed in the saw streets and THVs formed on silicon. The
electrical interconnect is accomplished using the THVs on saw
streets and THVs on silicon, in addition to a redistribution layer,
separated by a repassivation layer, to increase signal routing
options and density. The THVs on saw streets and THVs on silicon,
in addition to the RDLs, provide more signal routing functionality
and flexibility within the package.
[0057] While one or more embodiments of the present invention have
been illustrated in detail, the skilled artisan will appreciate
that modifications and adaptations to those embodiments may be made
without departing from the scope of the present invention as set
forth in the following claims
* * * * *