U.S. patent application number 15/878139 was filed with the patent office on 2019-07-25 for magnetic shielding of stt-mram in multichip packaging and method of manufacturing the same.
The applicant listed for this patent is GLOBALFOUNDRIES Singapore Pte. Ltd.. Invention is credited to Bharat BHUSHAN, Boo Yang JUNG, Danny Pak-Chum SHUM, Juan Boon TAN, Wanbing YI.
Application Number | 20190229068 15/878139 |
Document ID | / |
Family ID | 67300223 |
Filed Date | 2019-07-25 |
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United States Patent
Application |
20190229068 |
Kind Code |
A1 |
BHUSHAN; Bharat ; et
al. |
July 25, 2019 |
MAGNETIC SHIELDING OF STT-MRAM IN MULTICHIP PACKAGING AND METHOD OF
MANUFACTURING THE SAME
Abstract
Methodologies and an apparatus for enabling magnetic shielding
of stand alone MRAM are provided. Embodiments include placing MRAM
dies and logic dies on a first surface of a mold frame; forming a
top magnetic shield over top and side surfaces of the MRAM dies;
forming a mold cover over the MRAM dies, FinFET dies and mold
frame; removing the mold frame to expose a bottom surface of the
MRAM dies and FinFET dies; and forming a bottom magnetic shield
over the bottom surface of the MRAM dies.
Inventors: |
BHUSHAN; Bharat; (Singapore,
SG) ; TAN; Juan Boon; (Singapore, SG) ; JUNG;
Boo Yang; (Singapore, SG) ; YI; Wanbing;
(Singapore, SG) ; SHUM; Danny Pak-Chum;
(Singapore, SG) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GLOBALFOUNDRIES Singapore Pte. Ltd. |
Singapore |
|
SG |
|
|
Family ID: |
67300223 |
Appl. No.: |
15/878139 |
Filed: |
January 23, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 27/222 20130101;
H01L 21/78 20130101; H01L 23/49816 20130101; H01L 23/485 20130101;
H01L 24/96 20130101; H01L 2224/96 20130101; H01L 23/145 20130101;
H01L 21/561 20130101; H01L 21/4857 20130101; H01L 21/565 20130101;
H01L 23/5383 20130101; H01L 25/16 20130101; G11C 11/1695 20130101;
H01L 23/552 20130101; H01L 21/568 20130101; H01L 24/19 20130101;
H01L 2224/12105 20130101; H01L 23/3128 20130101; H01L 2224/96
20130101; G11C 11/161 20130101; H01L 2224/04105 20130101; H01L
2224/19 20130101 |
International
Class: |
H01L 23/552 20060101
H01L023/552; G11C 11/16 20060101 G11C011/16; H01L 27/22 20060101
H01L027/22; H01L 25/16 20060101 H01L025/16; H01L 23/485 20060101
H01L023/485; H01L 23/31 20060101 H01L023/31; H01L 21/48 20060101
H01L021/48; H01L 21/56 20060101 H01L021/56; H01L 21/78 20060101
H01L021/78 |
Claims
1. A method comprising: placing magnetoresistive random access
memory (MRAM) dies and Fin Field Effect Transistor (FinFET) dies on
a first surface of a mold frame; forming a top magnetic shield over
top and side surfaces of the MRAM dies; forming a mold cover over
the MRAM dies, FinFET dies and mold frame; removing the mold frame
to expose a bottom surface of the MRAM dies and FinFET dies; and
forming a bottom magnetic shield over the bottom surface of the
MRAM dies.
2. The method according to claim 1, further comprising: forming a
redistribution layer (RDL) over the mold cover, wherein the RDL
includes metal pillars.
3. The method according to claim 2, further comprising: solder
reflowing and forming solder bumps over the metal pillars, wherein
the metal pillars extend though patterned portions of the bottom
magnetic shield.
4. The method according to claim 3, further comprising: dicing the
mold to form multichips comprising at least one MRAM die and at
least one FinFET die embedded in the mold cover.
5. The method according to claim 4, wherein each multichip
comprises an MRAM die, a FinFET die, a micro-electromechanical
system (MEMS) die, NAND die, and a sensor die embedded in the mold
cover.
6. The method according to claim 5, further comprising: flipping
and bonding the multichip to a printed circuit board by way of the
solder bumps.
7. The method according to claim 1, wherein the FinFET dies
comprise logic FinFET dies and the MRAM dies comprise spin-transfer
torque (STT) MRAM.
8. The method according to claim 1, wherein the top and bottom
magnetic shield comprises a three-dimensional shield comprising a
nickel-iron ferromagnetic alloy, or an iron alloy having from zero
to 6.5% silicon (Si:5Fe).
9. A method comprising: placing magnetoresistive random access
memory (MRAM) dies and logic dies on a first surface of a mold
frame of a multichip fanout package; forming a top magnetic shield
over top and side surfaces of the MRAM dies; forming a mold cover
over the MRAM dies, logic dies and mold frame; removing the mold
frame to expose a bottom surface of the MRAM dies and logic dies;
and forming a bottom magnetic shield over the bottom surface of the
MRAM dies.
10. The method according to claim 9, further comprising: forming a
redistribution layer (RDL) over the mold cover, wherein the RDL
includes copper or aluminum pillars.
11. The method according to claim 10, further comprising: solder
reflowing and forming solder bumps over the copper or aluminum
pillars, wherein the copper or aluminum pillars extend though
patterned portions of the bottom magnetic shield.
12. The method according to claim 11, further comprising: dicing
the mold to form multichips comprising at least one MRAM die and at
least one logic die embedded in the mold cover, wherein the at
least one logic die comprises a Fin Field Effect Transistor
(FinFET) die.
13. The method according to claim 12, wherein each multichip
comprises an MRAM die, a FinFET die, a micro-electromechanical
system (MEMS) die, NAND die, and a sensor die embedded in the mold
cover.
14. The method according to claim 13, further comprising: flipping
and bonding the multichip to a printed circuit board by way of the
solder bumps.
15. The method according to claim 9, wherein the top and bottom
magnetic shield comprises a three-dimensional shield comprising a
nickel-iron ferromagnetic alloy, or an iron alloy having from zero
to 6.5% silicon (Si:5Fe).
16. A device comprising: magnetoresistive random access memory
(MRAM) dies and logic dies formed in a mold cover of a multichip
fanout package; and a redistribution layer (RDL) formed over the
mold cover in contact with the MRAM and logic dies, wherein a top
magnetic shield is formed over top and side surfaces of the MRAM
dies, wherein a bottom magnetic shield is formed over a bottom
surface of the MRAM dies, and wherein the RDL includes metal
pillars extending through patterned openings of the bottom magnetic
shield.
17. The device according to claim 16, wherein the logic dies
comprises Fin Field Effect Transistor (FinFET) dies and the MRAM
dies comprise spin-transfer torque (STT) MRAM.
18. The device according to claim 16, wherein mold further
comprises a micro-electromechanical system (MEMS) die, NAND die,
and a sensor die.
19. The device according to claim 16, further comprising solder
bumps formed over metal contacts formed in the RDL, wherein the
metal contacts and metal pillars comprise copper or aluminum.
20. The device according to claim 16, wherein the top and bottom
magnetic shield comprises a three-dimensional shield comprising a
nickel-iron ferromagnetic alloy, or and iron alloy having from zero
to 6.5% silicon (Si:5Fe).
Description
TECHNICAL FIELD
[0001] The present disclosure relates semiconductor packaging. In
particular, the present disclosure relates to magnetic shielding in
multichip fanout packaging.
BACKGROUND
[0002] Dynamic random-access memory (DRAM) is a type of random
access semiconductor memory that stores each bit of data in a
separate capacitor within an integrated circuit. Due to its need of
a system to perform refreshing, DRAM has more complicated circuitry
(e.g., high density) and timing requirements, but it is widely used
in the industry. Due to memory refresh cycles, DRAM consumes
relatively high amounts of power and due to the scaling issue of
DRAM, high latency issues are present. It is expected that
magnetoresistive random access memory (MRAM), which stores data
bits using magnetic states instead of the electrical charges used
by DRAM, will replace DRAM in the future. In particular,
spin-transfer torque (STT) is an effect in which the orientation of
a MRAM magnetic layer in a magnetic tunnel junction or spin valve
can be modified using a spin-polarized current. Magnetic shielding
of a standalone STT-MRAM presents challenges.
[0003] A need therefore exists for methodology enabling formation
of a standalone STT-MRAM with improved latency and power
consumption and the resulting device.
SUMMARY
[0004] An aspect of the present disclosure is to provide a
standalone STT-MRAM with improved system level power consumption
compared to DRAM and the method of manufacturing the same. Another
aspect of the present disclosure is to provide an integrated
technology with improved latency by arranging a memory die in close
proximity to a Fin Field Effect Transistor (FinFET) logic die. Yet
another aspect includes providing wafer-level magnetic shielding in
a multi-chip STT-MRAM fanout wafer level package and method of
manufacturing the same. A further aspect includes providing a
system level STT-MRAM integrated with other dies. Package thickness
is low since no package substrate is used.
[0005] Additional aspects and other features of the present
disclosure will be set forth in the description which follows and
in part will be apparent to those having ordinary skill in the art
upon examination of the following or may be learned from the
practice of the present disclosure. The advantages of the present
disclosure may be realized and obtained as particularly pointed out
in the appended claims.
[0006] According to the present disclosure, some technical effects
may be achieved in part by a method including: placing MRAM dies
and FinFET dies on a first surface of a mold frame; forming a top
magnetic shield over top and side surfaces of the MRAM dies;
forming a mold cover over the MRAM dies, FinFET dies and mold
frame; removing the mold frame to expose a bottom surface of the
MRAM dies and FinFET dies; and forming a bottom magnetic shield
over the bottom surface of the MRAM dies.
[0007] Aspects of the present disclosure include forming a
redistribution layer (RDL) over the mold cover, wherein the RDL
includes metal pillars. Other aspects include solder reflowing and
forming solder bumps over the metal pillars, wherein the metal
pillars extend though patterned portions of the bottom magnetic
shield. Additional aspects include dicing the mold to form
multichips including at least one MRAM die and at least one FinFET
die embedded in the mold cover. Further aspects include wherein
each multichip includes an MRAM die, a FinFET die, a
micro-electromechanical system (MEMS) die, NAND die, and a sensor
die embedded in the mold cover. Yet other aspects include flipping
and bonding the multichip to a printed circuit board by way of the
solder bumps. Other aspects include the FinFET dies including logic
FinFET dies and MRAM dies including STT-MRAM. Additional aspects
include the top and bottom magnetic shield including a
three-dimensional shield including a nickel-iron ferromagnetic
alloy, or iron alloy which may have from zero to 6.5% silicon
(Si:5Fe).
[0008] Another aspect of the present disclosure is a method
including placing MRAM dies and logic dies on a first surface of a
mold frame of a multichip fanout package; forming a top magnetic
shield over top and side surfaces of the MRAM dies; forming a mold
cover over the MRAM dies, logic dies and mold frame; removing the
mold frame to expose a bottom surface of the MRAM dies and logic
dies; and forming a bottom magnetic shield over the bottom surface
of the MRAM dies.
[0009] Aspects include forming a redistribution layer (RDL) over
the mold cover, wherein the RDL includes copper or aluminum
pillars. Other aspects include solder reflowing and forming solder
bumps over the copper or aluminum pillars, wherein the copper or
aluminum pillars extend though patterned portions of the bottom
magnetic shield. Additional aspects include dicing the mold to form
multichips including at least one MRAM die and at least one logic
die embedded in the mold cover, wherein the at least one logic die
includes a FinFET die. Other aspects include each multichip
including an MRAM die, a FinFET die, MEMS die, NAND die, and a
sensor die embedded in the mold cover. Yet further aspects include
flipping and bonding the multichip to a printed circuit board by
way of the solder bumps. Additional aspects include the top and
bottom magnetic shield having a three-dimensional shield including
a nickel-iron ferromagnetic alloy, or iron alloy which may has from
zero to 6.5% silicon (Si:5Fe).
[0010] According to the present disclosure, some additional
technical effects may be achieved in part by a device including
MRAM dies and logic dies formed in a mold cover of a multichip
fanout package; and a RDL formed over the mold cover in contact
with the MRAM and logic dies, wherein a top magnetic shield is
formed over top and side surfaces of the MRAM dies, wherein a
bottom magnetic shield is formed over a bottom surface of the MRAM
dies, and wherein the RDL includes metal pillars extending through
patterned openings of the bottom magnetic shield.
[0011] Aspects include wherein the logic dies being FinFET dies.
Other aspects include wherein mold further including a MEMS die,
NAND die, and a sensor die. Additional aspects include solder bumps
formed over metal contacts formed in the RDL, wherein the metal
contacts and metal pillars include copper or aluminum. Further
aspects include the top and bottom magnetic shield including a
three-dimensional shield having a nickel-iron ferromagnetic alloy,
or iron alloy which has from zero to 6.5% silicon (Si:5Fe).
[0012] Additional aspects and technical effects of the present
disclosure will become readily apparent to those skilled in the art
from the following detailed description wherein embodiments of the
present disclosure are described simply by way of illustration of
the best mode contemplated to carry out the present disclosure. As
will be realized, the present disclosure is capable of other and
different embodiments, and its several details are capable of
modifications in various obvious respects, all without departing
from the present disclosure. Accordingly, the drawings and
description are to be regarded as illustrative in nature, and not
as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present disclosure is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawing and in which like reference numerals refer to similar
elements and in which:
[0014] FIG. 1A illustrates, in top perspective side view, a
multichip fanout package, in accordance with an exemplary
embodiment;
[0015] FIG. 1B, illustrates, in cross sectional view along line
A-A', the multichip fanout package of FIG. 1A;
[0016] FIG. 2 illustrates a process diagram for producing a
multichip fanout wafer level package, in accordance with an
exemplary embodiment;
[0017] FIGS. 3A-3I illustrate a process flow for producing a
multichip fanout wafer level package, in accordance with an
exemplary embodiment.
DETAILED DESCRIPTION
[0018] In the following description, for the purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of exemplary embodiments. It
should be apparent, however, that exemplary embodiments may be
practiced without these specific details or with an equivalent
arrangement. In other instances, well-known structures and devices
are shown in block diagram form in order to avoid unnecessarily
obscuring exemplary embodiments. In addition, unless otherwise
indicated, all numbers expressing quantities, ratios, and numerical
properties of ingredients, reaction conditions, and so forth used
in the specification and claims are to be understood as being
modified in all instances by the term "about."
[0019] The present disclosure addresses and solves the current
problem of sufficient magnetic shielding in multichip fanout
packaging. In accordance with embodiments of the present
disclosure, a system level MRAM integration with other dies is
provided. A three-dimensional magnetic shield is formed during
wafer level processing.
[0020] Still other aspects, features, and technical effects will be
readily apparent to those skilled in this art from the following
detailed description, wherein preferred embodiments are shown and
described, simply by way of illustration of the best mode
contemplated. The disclosure is capable of other and different
embodiments, and its several details are capable of modifications
in various obvious respects. Accordingly, the drawings and
description are to be regarded as illustrative in nature, and not
as restrictive.
[0021] FIG. 1A illustrates, in top perspective side view, a
multichip fanout package. A mold 101 is formed over a printed
circuit board (PCB) 103. The mold 101 can include an epoxy resin
with high thermal conductivity and moldability. Embedded in the
mold, are dies including a MRAM die 105, a FinFET die 107, MEMS die
109, NAND die 111, and sensor die 113 which are embedded or
encapsulated in the mold 101. The mold 101 is attached to the PCB
103 by way of solder bumps 115.
[0022] FIG. 1B, illustrates the multichip fanout package, in cross
sectional view, along line A-A' of FIG. 1A. The MRAM die 105
includes a magnetic shield 117 formed in a three-dimensional manner
around the MRAM die 105. An RDL 121 is formed between the mold 101
and PCB 103. The RDL 121 includes metal wiring and metal pillars
123 on and within a polymer layer 119. The RDL in flip-chip designs
is an extra metal layer that redistributes input/output (I/O) pads
to bump pads without changing the I/O pad placement. The metal
wiring and metal pillars 123 of the RDL 121 can include a metal
such as copper (Cu), or aluminum (Al). The metal pillars 123 extend
through patterned openings of a bottom surface 117a of the magnetic
shield 117.
[0023] The three-dimensional magnetic shield 117 protects from all
directions except the patterned openings in the bottom surface 117a
of the magnetic shield 117. Magnetic tunneling junctions (MTJ) (not
shown for simplicity) of STT-MRAM are not to be formed near the
patterned openings in the bottom surface 117a of the magnetic
shield 117. The magnetic shield 117 can include a nickel-iron
ferromagnetic alloy (Mumetal.RTM.) or an iron alloy which may have
from zero to 6.5% silicon (Si:5Fe) (E-steel).
[0024] FIG. 2 illustrates a process diagram for producing a
multichip fanout wafer level package. Wafer 201 includes logic dies
107, such as FinFET logic dies 107. Wafer 203 includes MRAM dies
105, such as STT-MRAM dies 105. A dicing step is performed to
singulate the logic dies 107 and MRAM dies 105. A wafer
reconstruction is performed with the temporary attachment of the
dies 105 and 107 to a mold frame with an adhesive tape place on a
surface of the mold frame to form a temporary bond of the dies 105
and 107 to the mold frame. As shown in FIG. 1A, additional dies can
be embedded in the mold. Wafer level processing is performed to
form the magnetic shield over the MRAM dies 105. A wafer level
molding is formed by deposition of a mold 101, such as an epoxy
resin to encapsulate or embed the dies 105 and 107 and the mold 101
is cured at a temperature below 200.degree. C. The mold frame is
de-bonded and the mold 101 is flipped over for wafer level
processing of a bottom surface of the magnetic shield.
[0025] FIGS. 3A-3I illustrate a process flow for producing a
multichip fanout wafer level package of FIGS. 1A and 1B. In FIG.
3A, a mold frame 301 is provided and includes an adhesive tape 303
attached to an upper surface of the mold frame 301. MRAM dies 105
and logic dies 107 are placed in close adjacent one another and
attached to the mold frame 301 with the adhesive tape 303. Other
dies illustrated in FIG. 1A can be attached in a similar
manner.
[0026] In FIG. 3B, a wafer level processing is performed to form
the magnetic shield 117 over the MRAM dies 105. The magnetic shield
by be deposited with physical vapor deposition (PVD),
electroplating (ECP), or other suitable deposition process for
depositing the magnetic shield while the logic dies 107 are masked.
The magnetic shield is formed to a thickness of 0.3 .mu.m to 1
.mu.m on side and top surfaces of the MRAM dies 105.
[0027] In FIG. 3C, a wafer level processing is performed to form
the mold 101. The mold, which includes an epoxy resin, is deposited
and cured to embed or encapsulate the dies 105 and 107. The mold
can be deposited by way of dispensing and cured at a temperature
below 200.degree. C.
[0028] In FIG. 3D, the mold frame 301 and adhesive tape are
detached to expose a bottom surface of the dies 105 and 107 that
remain embedded in the mold 101. The mold 101 is then flipped
upside down, as shown in FIG. 3D.
[0029] In FIG. 3E, a wafer level processing is performed to form
the bottom portion 117a of the magnetic shield 117 over the MRAM
dies 105. Once deposited to a thickness of 0.3 .mu.m to the bottom
portion of the magnetic shield 117 is patterned/etched to form
openings 117b. Thickness of the deposited magnetic shield can be
adjusted by way of PVD and ECP.
[0030] FIG. 3F illustrates the formation of the RDL 121 on one or
more polymer layers 119. The polymer layer(s) 119 can include a
polyimide HD-4100 or polybenzoxazole HD-8930 over the mold 101. The
RDL 121 is an extra metal layer formed over the mold 101. The metal
wiring and metal pillars 123 form the RDL 119. In FIG. 3G, a solder
reflow at a temperature of 200 to 300.degree. C. (e.g., 260.degree.
C.) is performed to attach solder bumps or micro solder bumps to
contacts of the RDL 121. A dicing or cutting step is performed form
a plurality of multichip fanout packages 305. The multichip fanout
packages 305 are then flipped to connect to a PCB 103. As discussed
above the multichip fanout packages 305 can include additional dies
such as MEMS dies 109, NAND die 111, and sensor die 113 (FIG.
1A).
[0031] The embodiments of the present disclosure can achieve
several technical effects include overcoming the technical
challenges of shielding stand alone MRAM and STT-MRAM. An
integration is provided to improve latency by bringing memory dies
in close proximity to FinFET logic die in fanout packaging. Low
power consumption of the MRAM in a fanout packaging is obtained.
The present disclosure enjoys industrial applicability in any of
various industrial applications, e.g., microprocessors, smart
phones, mobile phones, cellular handsets, set-top boxes, DVD
recorders and players, automotive navigation, printers and
peripherals, networking and telecom equipment, gaming systems, and
digital cameras. The present disclosure therefore enjoys industrial
applicability in any of various types of highly integrated
semiconductor devices.
[0032] In the preceding description, the present disclosure is
described with reference to specifically exemplary embodiments
thereof. It will, however, be evident that various modifications
and changes may be made thereto without departing from the broader
spirit and scope of the present disclosure, as set forth in the
claims. The specification and drawings are, accordingly, to be
regarded as illustrative and not as restrictive. It is understood
that the present disclosure is capable of using various other
combinations and embodiments and is capable of any changes or
modifications within the scope of the inventive concept as
expressed herein.
* * * * *