U.S. patent application number 15/822301 was filed with the patent office on 2018-10-04 for fabrication method of all solid-state thin-film battery.
The applicant listed for this patent is International Business Machines Corporation. Invention is credited to Joel P. de Souza, Yun Seog Lee, Kunal Mukherjee, Devendra K. Sadana.
Application Number | 20180287188 15/822301 |
Document ID | / |
Family ID | 63669871 |
Filed Date | 2018-10-04 |
United States Patent
Application |
20180287188 |
Kind Code |
A1 |
de Souza; Joel P. ; et
al. |
October 4, 2018 |
FABRICATION METHOD OF ALL SOLID-STATE THIN-FILM BATTERY
Abstract
A method of forming an all solid-state thin-film battery that
can be scaled down and be integrated into a CMOS process is
provided. The method includes a lift-off process in which battery
material layers formed upon a patterned sacrificial material are
removed from a bottom electrode, while battery material layers that
are formed directly on a surface of the bottom electrode remain
after performing the lift-off process. In some embodiments, a
solid-state lithium based battery can be formed that includes a
thin lithiated cathode material layer (thickness of less than 200
nm) composed of LiCoO.sub.2. Such a solid-state lithium based
battery exhibits enhanced battery performance in terms of charge
rate and specific charge capacity.
Inventors: |
de Souza; Joel P.; (Putnam
Valley, NY) ; Lee; Yun Seog; (White Plains, NY)
; Mukherjee; Kunal; (Goleta, CA) ; Sadana;
Devendra K.; (Pleasantville, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Family ID: |
63669871 |
Appl. No.: |
15/822301 |
Filed: |
November 27, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15474570 |
Mar 30, 2017 |
|
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15822301 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/0562 20130101;
H01M 2220/30 20130101; H01M 10/0585 20130101; H01M 4/525 20130101;
H01M 2300/0068 20130101; Y02E 60/10 20130101; H01M 10/0436
20130101; H01M 10/0525 20130101 |
International
Class: |
H01M 10/04 20060101
H01M010/04; H01M 10/0562 20060101 H01M010/0562; H01M 4/525 20060101
H01M004/525; H01M 10/0525 20060101 H01M010/0525 |
Claims
1. A solid-state lithium-based battery comprising: a bottom
electrode; a lithiated cathode material layer on the bottom
electrode, wherein the lithiated cathode material layer comprises
LiCoO.sub.2 and has a thickness of less than 200 nm; a
lithium-based solid-state electrolyte layer located on the
lithiated cathode material layer; and a top electrode located above
the lithium-based solid-state electrolyte layer.
2. The solid-state lithium-based battery of claim 1, further
comprising an air and/or moisture impermeable structure located on
physically exposed surfaces of the bottom electrode and surrounding
each of the lithiated cathode material layer, the lithium-based
solid-state electrolyte layer, and the top electrode.
3. The solid-state lithium-based battery of claim 1, wherein the
bottom electrode is located on a textured surface of a
substrate.
4. The solid-state lithium-based battery of claim 1, wherein the
bottom electrode is located on a non-textured surface of a
substrate.
5. The solid-state lithium-based battery of claim 1, wherein the
lithiated cathode material layer, the lithium-based solid-state
electrolyte layer, and the top electrode have sidewall surfaces
that are vertically aligned to each other.
6. The solid-state lithium-based battery of claim 1, further
comprising a lithium accumulation region located between the
lithium-based solid-state electrolyte layer and the top
electrode.
7. The solid-state lithium-based battery of claim 1, wherein the
thickness of the lithiated cathode material layer is from 40 nm to
90 nm.
8. The solid-state lithium-based battery of claim 1, wherein the
solid-state lithium-based battery has a charge rate of greater than
10 C, and a specific charge capacity of greater than 100 mAh/g.
Description
BACKGROUND
[0001] The present application relates to an all solid-state thin
film battery and a method of forming the same. More particularly,
the present application relates to a method of forming an all
solid-state thin film battery and a solid-state lithium-based
battery having enhanced performance. The method can be used to
fabricate micrometer scale sized batteries.
[0002] In recent years, there has been an increased demand for
portable electronic devices such as, for example, computers, mobile
phones, tracking systems, scanners, medical devices, smart watches,
and fitness devices. One drawback with portable electronic devices
is the need to include a power supply within the device itself.
Furthermore, it is also useful to scale the battery device size
down to the micron level to integrate the batteries into small
scale devices such as, microprocessors, sensors, or IoT (internet
of things) systems. Typically, a battery is used as the power
supply of such portable electronic devices. Batteries must have
sufficient capacity to power the portable electronic device for at
least the length that the device is being used. Sufficient battery
capacity can result in a power supply that is quite heavy and/or
large compared to the rest of the portable electronic device. As
such, smaller sized and lighter weight power supplies with
sufficient energy storage are desired. Such power supplies can be
implemented in smaller and lighter weight portable electronic
devices.
[0003] Another drawback of conventional batteries is that some of
the batteries contain potentially flammable and toxic materials
that may leak and may be subject to governmental regulations. As
such, it is desired to provide an electrical power supply that is
safe, solid-state and rechargeable over many charge/discharge life
cycles.
[0004] One type of an energy-storage device that is small and light
weight, contains non-toxic materials and that can be recharged over
many charge/discharge cycles is a solid-state, lithium-based
thin-film battery. Lithium-based thin-film batteries are storage
batteries that include two electrodes implementing lithium. Such
lithium-based thin-film batteries are typically patterned utilizing
photolithography and etching.
[0005] There is a need for providing a method of forming
lithium-based thin-film batteries, and other types of all
solid-state thin-film batteries, that avoids utilizing
liquid-containing materials such as conventional liquid-based
electrolytes to form the battery material stack. Moreover, there is
a need for providing a method of forming a solid-state thin film
battery that is compatible with existing CMOS (complementary metal
oxide semiconductor) processes and which can be monolithically
integrated to other microelectronic devices. Also, there is a need
for providing a lithium-based thin-film battery that has improved
device performance at fast charging speeds.
SUMMARY
[0006] A method of forming an all solid-state thin-film battery
that can be scaled down and be integrated into a CMOS process is
provided. The term "thin-film battery" is used throughout the
present application to denote a battery whose thickness is 100
.mu.m or less. The term "all solid-state" denotes a battery that is
entirely composed of solid materials. The method includes a
lift-off process in which a battery material stack formed upon a
patterned sacrificial material is removed from a bottom electrode,
while a battery material stack that is formed directly on a surface
of the bottom electrode remains after performing the lift-off
process. In some embodiments, a solid-state lithium based battery
can be formed that includes a thin lithiated cathode material layer
(thickness of less than 200 nm) composed of LiCoO.sub.2. Such a
solid-state lithium based battery exhibits enhanced battery
performance in terms of charge rate and specific charge
capacity.
[0007] One aspect of the present application relates to a
non-photolithographic method of forming an all solid-state
thin-film battery. In one embodiment, the method includes forming a
patterned sacrificial material on a surface of a bottom electrode,
wherein the patterned sacrificial material contains an opening that
physically exposes a portion of the surface of the bottom
electrode. Next, an all solid-state battery stack such as, for
example, a solid-state lithium-based battery stack, is formed on
the patterned sacrificial material and on the physically exposed
portion of the bottom electrode in the opening. A lift-off process
is then performed to remove the patterned sacrificial material and
the all solid-state battery stack formed on the patterned
sacrificial material from the bottom electrode, while maintaining
the all solid-state battery stack on the physically exposed portion
of the surface of the bottom electrode.
[0008] Another aspect of the present application relates to a
solid-state lithium battery that has enhanced battery performance.
In one embodiment, the solid-state lithium based battery includes a
bottom electrode, a lithiated cathode material layer on the bottom
electrode, wherein the lithiated cathode material layer comprises
LiCoO.sub.2 and has a thickness of less than 200 nm, a
lithium-based solid-state electrolyte layer located on the
lithiated cathode material layer, and a top electrode located above
the lithium-based solid-state electrolyte layer. Such a solid-state
lithium based battery may have a charge rate of greater than 10 C
(wherein C is the total charge capacity per hour), and a specific
charge capacity of greater than 100 mAh/g.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0009] FIG. 1 is a cross sectional view of an exemplary structure
including a bottom electrode located on a surface of a substrate
that can be employed in accordance with an embodiment of the
present application.
[0010] FIG. 2 is a cross sectional view of the exemplary structure
of FIG. 1 after forming a patterned sacrificial material on a
surface of the bottom electrode, wherein the patterned sacrificial
material includes an opening that physically exposes a portion of
the surface of the bottom electrode.
[0011] FIG. 3A is a cross sectional view of the exemplary structure
of FIG. 2 after forming an all solid-state battery stack on the
patterned sacrificial material and on the physically exposed
portion of the bottom electrode in the opening.
[0012] FIG. 3B is a cross sectional view of an exemplary all
solid-state battery stack that can be employed in the present
application.
[0013] FIG. 4 is a cross sectional view of the exemplary structure
of FIG. 3A after performing a lift-off process in which the
patterned sacrificial material and the all solid-state battery
stack formed thereon are removed from the bottom electrode, while
maintaining the all solid-state battery stack on the bottom
electrode.
[0014] FIG. 5 is a cross sectional view of the exemplary structure
of FIG. 4 after forming an air and/or moisture impermeable
structure.
[0015] FIGS. 6A and 6B are cross sectional views of an all
solid-state lithium-based battery of the present application prior
to and after charging, respectively.
[0016] FIG. 7 is a graph of specific charge capacity (mAh/g) vs.
charge rate, C, of various solid-state lithium-based batteries
containing cathode layers having different thicknesses.
DETAILED DESCRIPTION
[0017] The present application will now be described in greater
detail by referring to the following discussion and drawings that
accompany the present application. It is noted that the drawings of
the present application are provided for illustrative purposes only
and, as such, the drawings are not drawn to scale. It is also noted
that like and corresponding elements are referred to by like
reference numerals.
[0018] In the following description, numerous specific details are
set forth, such as particular structures, components, materials,
dimensions, processing steps and techniques, in order to provide an
understanding of the various embodiments of the present
application. However, it will be appreciated by one of ordinary
skill in the art that the various embodiments of the present
application may be practiced without these specific details. In
other instances, well-known structures or processing steps have not
been described in detail in order to avoid obscuring the present
application.
[0019] It will be understood that when an element as a layer,
region or substrate is referred to as being "on" or "over" another
element, it can be directly on the other element or intervening
elements may also be present. In contrast, when an element is
referred to as being "directly on" or "directly over" another
element, there are no intervening elements present. It will also be
understood that when an element is referred to as being "beneath"
or "under" another element, it can be directly beneath or under the
other element, or intervening elements may be present. In contrast,
when an element is referred to as being "directly beneath" or
"directly under" another element, there are no intervening elements
present.
[0020] Referring first to FIG. 1, there is illustrated an exemplary
structure that can be employed in accordance with an embodiment of
the present application. The exemplary structure of FIG. 1 includes
a bottom electrode 12 located on a surface of a substrate 10. As is
shown, the bottom electrode 12 is typically a continuous layer
(without any intentionally formed gaps or breaks) that is present
on an entirety of the substrate 10.
[0021] The substrate 10 that can be employed in the present
application includes any conventional material that is used as a
substrate for a solid-state lithium-based battery. In one
embodiment, the substrate 10 may include one or more semiconductor
materials. The term "semiconductor material" is used throughout the
present application to denote a material having semiconducting
properties.
[0022] Examples of semiconductor materials that may be employed as
substrate 10 include silicon (Si), germanium (Ge), silicon
germanium alloys (SiGe), silicon carbide (SiC), silicon germanium
carbide (SiGeC), III-V compound semiconductors or II-VI compound
semiconductors. III-V compound semiconductors are materials that
include at least one element from Group III of the Periodic Table
of Elements and at least one element from Group V of the Periodic
Table of Elements. II-VI compound semiconductors are materials that
include at least one element from Group II of the Periodic Table of
Elements and at least one element from Group VI of the Periodic
Table of Elements.
[0023] In one embodiment, the semiconductor material that may
provide substrate 10 is a bulk semiconductor substrate. By "bulk"
it is meant that the substrate 10 is entirely composed of at least
one semiconductor material, as defined above. In one example, the
substrate 10 may be entirely composed of silicon. In some
embodiments, the bulk semiconductor substrate may include a
multilayered semiconductor material stack including at least two
different semiconductor materials, as defined above. In one
example, the multilayered semiconductor material stack may
comprise, in any order, a stack of Si and a silicon germanium
alloy.
[0024] In another embodiment, substrate 10 is composed of a topmost
semiconductor material layer of a semiconductor-on-insulator (SOI)
substrate. The SOI substrate would also include a handle substrate
(not shown) including one of the above mentioned semiconductor
materials, and an insulator layer (not shown) such as a buried
oxide below the topmost semiconductor material layer.
[0025] In any of the embodiments mentioned above, the semiconductor
material that may provide the substrate 10 may be a single
crystalline semiconductor material. The semiconductor material that
may provide the substrate 10 may have any of the well known crystal
orientations. For example, the crystal orientation of the
semiconductor material that may provide substrate 10 may be {100},
{110}, or {111}. Other crystallographic orientations besides those
specifically mentioned can also be used in the present
application.
[0026] In another embodiment, the substrate 10 is a metallic
material such as, for example, aluminum (Al), aluminum alloy,
titanium (Ti), tantalum (Ta), tungsten (W), or molybdenum (Mo).
[0027] In yet another embodiment, the substrate 10 is a dielectric
material such as, for example, doped or non-doped silicate glass,
silicon dioxide, or silicon nitride. In yet a further embodiment,
the substrate 10 is composed of a polymer or flexible substrate
material such as, for example, a polyimide, a polyether ketone
(PEEK) or a transparent conductive polyester. In yet an even
further embodiment, the substrate 10 may be composed of a
multilayered stack of at least two of the above mentioned substrate
materials, e.g., a stack of silicon and silicon dioxide.
[0028] The substrate 10 that can be used in the present application
can have a thickness from 10 .mu.m to 5 mm. Other thicknesses that
are lesser than, or greater than, the aforementioned thickness
values may also be used for substrate 10.
[0029] In some embodiments, the substrate 10 may have a
non-textured (flat or planar) surface. The term "non-textured
surface" denotes a surface that is smooth and has a surface
roughness on the order of less than 100 nm root mean square as
measured by profilometry. In yet another embodiment, the substrate
10 may have a textured surface. In such an embodiment, the surface
roughness of the textured substrate can be in a range from 100 nm
root mean square to 100 .mu.m root mean square as also measured by
profilometry. Texturing can be performed by forming a plurality of
etching masks (e.g., metal, insulator, or polymer) on the surface
of a non-textured substrate, etching the non-textured substrate
utilizing the plurality of masks as an etch mask, and removing the
etch masks from the non-textured surface of the substrate. In some
embodiments, the textured surface of the substrate is composed of a
plurality of pyramids. In yet another embodiment, the textured
surface of the substrate is composed of a plurality of cones. In
some embodiments, a plurality of metallic masks are used, which may
be formed by depositing a layer of a metallic material and then
performing an anneal. During the anneal, the layer of metallic
material melts and balls-ups such that de-wetting of the surface of
the substrate occurs.
[0030] The bottom electrode 12 may include any metallic electrode
material such as, for example, titanium (Ti), platinum (Pt), nickel
(Ni), aluminum (Al) or titanium nitride (TiN). In one example, the
bottom electrode 12 includes a stack of, from bottom to top,
titanium (Ti), platinum (Pt) and titanium (Ti). The bottom
electrode 12 may be formed utilizing a deposition process
including, for example, chemical vapor deposition (CVD), plasma
enhanced chemical vapor deposition (PECVD), evaporation,
sputtering, or plating. The bottom electrode 12 may have a
thickness from 10 nm to 500 nm. Other thicknesses that are lesser
than, or greater than, the aforementioned thickness values may also
be used for the bottom electrode 12.
[0031] Referring now to FIG. 2, there is illustrated the exemplary
structure of FIG. 1 after forming a patterned sacrificial material
14 on the surface of the bottom electrode 12, wherein the patterned
sacrificial material 14 includes an opening 16 that physically
exposes a portion of the surface of the bottom electrode 12. The
opening 16 defines an area in which an all solid-state thin-film
battery will be subsequently formed. Although the present
application describes and illustrates a single opening 16, a
plurality of openings 16 can be formed in which each opening of the
plurality of openings 16 can define an area for subsequent
formation of an all solid-state thin-film battery.
[0032] The patterned sacrificial material 14 can be formed by first
applying a sacrificial material (not shown) to the physically
exposed surface of the bottom electrode 12. In one embodiment, the
sacrificial material is a photoresist material. In such an
embodiment, the photoresist material may be a positive-tone
photoresist material, a negative-tone photoresist material or a
hybrid-tone photoresist material. The sacrificial material may be
formed utilizing a deposition process such as, for example, spin-on
coating or blade coating, followed by a bake step to evaporate any
residual solvent(s). The sacrificial material may have a thickness
from 100 nm to 20 .mu.m. Other thicknesses that are lesser than, or
greater than, the aforementioned thickness values may also be used
for the sacrificial material.
[0033] The deposited sacrificial material is then patterned. In one
embodiment and when the sacrificial material is a photoresist
material, the photoresist material may be patterned by exposing the
photoresist material to a desired pattern of radiation, and
thereafter the exposed photoresist material is developed utilizing
a conventional resist developer to provide a patterned sacrificial
material 14. When non-photoresist sacrificial materials are used,
the non-photoresist sacrificial materials can be patterned by
lithography and etching.
[0034] In another embodiment, the sacrificial material that
provides the patterned sacrificial material 14 is a shadow mask. In
such an embodiment, the shadow mask may be a pre-patterned metallic
material or a pre-patterned polymeric material. The pre-patterned
shadow mask material is attached to the structure shown in FIG. 1
by mechanical force or a removable adhesive.
[0035] Referring now to FIG. 3A, there is illustrated of the
exemplary structure of FIG. 2 after forming an all solid-state
battery stack 18 on the patterned sacrificial material 14 and on
the physically exposed portion of the bottom electrode 12 in the
opening 16. The all solid-state battery stack 18 can be formed
utilizing various deposition techniques well known to those skilled
in the art. Also, the all solid-state battery stack 18 includes
conventional materials that are also well known to those skilled in
the art. For example, the all solid-state battery stack 18
comprises, from bottom to top, a cathode layer, a solid-state
electrolyte layer and a top electrode. In some embodiments, the
solid-state battery stack 18 may further comprise an anode region
located between the solid-state electrolyte layer and the top
electrode. The anode region may or may not be continuously present
between the solid-state electrolyte layer and the top electrode.
The anode region may be a deposited anode material, or it may be
generated during a charging/recharging process. In a further
embodiment, the solid-state battery stack may even further comprise
a liner located between the solid-state electrolyte layer and the
anode region.
[0036] An exemplary all solid-state battery stack 18 that can be
employed in the present application is shown in FIG. 3B. Notably,
the all solid-state battery stack 18 shown in FIG. 3B is a
solid-state lithium-based battery stack. Although a solid-state
lithium-based battery stack is exemplified herein as the all
solid-state battery stack 18, other types of all solid-state
battery stacks can be employed in the present application. The all
solid-state battery stack 18 shown in FIG. 3B includes, from bottom
to top, a cathode layer 20, a solid-state electrolyte layer 22, an
optional liner 24, an anode region 26 and a top electrode 28. As
stated above, the anode region 26 may be a deposited anode
material, or it may be generated during a charging/recharging
process.
[0037] The cathode layer 20 of the lithium-based battery stack may
include a lithiated material such as, for example, a lithium-based
mixed oxide. Hence, the cathode layer 20 of the lithium-based
battery stack may be referred to as a lithiated cathode material
layer. Examples of lithium-based mixed oxides that may be employed
as the cathode layer 20 of the lithium-based battery stack include,
but are not limited to, lithium cobalt oxide (LiCoO.sub.2), lithium
nickel oxide (LiNiO.sub.2), lithium manganese oxide
(LiMn.sub.2O.sub.4), lithium vanadium pentoxide (LiV.sub.2O.sub.5)
or lithium iron phosphate (LiFePO.sub.4).
[0038] The cathode layer 20 of the lithium-based battery stack may
be formed utilizing a deposition process such as, sputtering or
plating. In one embodiment, the cathode layer 20 of the
lithium-based battery stack is formed by sputtering utilizing any
conventional precursor source material or combination of precursor
source materials. In one example, a lithium precursor source
material and a cobalt precursor source material are employed in
forming a lithium cobalt mixed oxide. Sputtering may be performed
in an admixture of an inert gas and oxygen. In such an embodiment,
the oxygen content of the inert gas/oxygen admixture can be from
0.1 atomic percent to 70 atomic percent, the remainder of the
admixture includes the inert gas. Examples of inert gases that may
be used include argon, helium, neon, nitrogen or any combination
thereof.
[0039] The cathode layer 20 of the lithium-based battery stack may
have a thickness from 10 nm to 20 .mu.m. Other thicknesses that are
lesser than, or greater than, the aforementioned thickness values
may also be used for cathode layer 20 of the lithium-based battery
stack.
[0040] The solid-state electrolyte layer 22 of the lithium-based
battery stack includes a material that enables the conduction of
lithium ions; the solid-state electrolyte layer 22 of the
lithium-based battery stack may be referred to as a lithium-based
solid-state electrolyte layer. Such materials may be electrically
insulating or ionic conducting. Examples of materials that can be
employed as the solid-state electrolyte layer 22 of the
lithium-based battery stack include, but are not limited to,
lithium phosphorus oxynitride (LiPON) or lithium phosphosilicate
oxynitride (LiSiPON).
[0041] The solid-state electrolyte layer 22 of the lithium-based
battery stack may be formed utilizing a deposition process such as,
sputtering or plating. In one embodiment, the solid-state
electrolyte layer 22 of the lithium-based battery stack is formed
by sputtering utilizing any conventional precursor source material.
Sputtering may be performed in the presence of at least a
nitrogen-containing ambient. Examples of nitrogen-containing
ambients that can be employed include, but are not limited to,
N.sub.2, NH.sub.3, NH.sub.4, NO, or NH.sub.x wherein x is between 0
and 1. Mixtures of the aforementioned nitrogen-containing ambients
can also be employed. In some embodiments, the nitrogen-containing
ambient is used neat, i.e., non-diluted. In other embodiments, the
nitrogen-containing ambient can be diluted with an inert gas such
as, for example, helium (He), neon (Ne), argon (Ar) and mixtures
thereof. The content of nitrogen (N.sub.2) within the
nitrogen-containing ambient employed is typically from 10% to 100%,
with a nitrogen content within the ambient from 50% to 100% being
more typical.
[0042] The solid-state electrolyte layer 22 of the lithium-based
battery stack may have a thickness from 10 nm to 10 .mu.m. Other
thicknesses that are lesser than, or greater than, the
aforementioned thickness values may also be used for the
solid-state electrolyte layer 22 of the lithium-based battery
stack.
[0043] The liner 24 that may be present in the lithium-based
battery stack is a continuous layer that covers the entirety of the
solid-state electrolyte layer 22. In one embodiment, the liner 24
that may be present in the lithium-based battery stack shown in
FIG. 3B is a lithium nucleation enhancement liner. In such an
embodiment, the lithium nucleation enhancement liner includes a
material that can facilitate the subsequent nucleation of lithium
upon performing a charging/recharging process. In one embodiment,
lithium nucleation enhancement liner that can be used as liner 24
is composed of gold (Au), silver (Ag), zinc (Zn), magnesium (Mg),
tantalum (Ta), tungsten (W), molybdenum (Mo), a
titanium-zirconium-molybdenum alloy (TZM), or silicon (Si). In
another embodiment, liner 24 is a barrier material such as, for
example, LiF.
[0044] The liner 24 can be formed utilizing a deposition process.
Examples of deposition processes than can be used in forming the
liner 24 include chemical vapor deposition (CVD), plasma enhanced
chemical vapor deposition (PECVD), evaporation, sputtering or
plating. The liner 24 typically has a thickness that is greater
than 1 nm. In one embodiment, the liner 24 has a thickness from 2
nm to 20 nm.
[0045] The anode region 26 of the lithium-based battery stack
includes any material that is a lithium ion generator or lithium
intercalation active material. Examples of materials that may be
used as anode region 26 include, but are not limited to, lithium
metal, a lithium-base alloy such as, for example, Li.sub.xSi, or a
lithium-based mixed oxide such as, for example, lithium titanium
oxide (Li.sub.2TiO.sub.3). The anode region 26 may be a continuous
layer or it may be composed of a plurality of non-continuous
islands.
[0046] In some embodiments, the anode region 26 is formed prior to
performing a charging/recharging process. In such an embodiment,
the anode region 26 can be formed utilizing a deposition processes
such as, for example, chemical vapor deposition (CVD), plasma
enhanced chemical vapor deposition (PECVD), evaporation, sputtering
or plating. In other embodiments, the anode region 26 is a lithium
accumulation region that is formed during a charging/recharging
process.
[0047] The top electrode 28 of the lithium-based battery stack may
include any metallic electrode material such as, for example,
titanium (Ti), platinum (Pt), nickel (Ni), copper (Cu) or titanium
nitride (TiN). In one example, the top electrode 26 includes a
stack of, from bottom to top, nickel (Ni) and copper (Cu). In one
embodiment, the metallic electrode material that provides the top
electrode 28 may be the same as the metallic electrode material
that provides the bottom electrode 12. In another embodiment, the
metallic electrode material that provides the top electrode 28 may
be different from the metallic electrode material that provides the
bottom electrode 12. The top electrode 28 may be formed utilizing
one of the deposition processes mentioned above for forming the
bottom electrode 12. The top electrode 28 may have a thickness
within the range mentioned above for the bottom electrode 12.
[0048] Referring now to FIG. 4, there is illustrated the exemplary
structure of FIG. 3A after performing a lift-off process in which
the patterned sacrificial material 14 and all materials (i.e.,
battery material stack) formed thereon are removed from the bottom
electrode 12, while maintaining the battery material stack 18 on
the bottom electrode 12. In one embodiment, the lift-off process
includes removing the patterned sacrificial material 14 utilizing a
solvent or etchant that is selective for removing the sacrificial
material. In one example, the solvent is a non-aqueous solvent such
as, for example, acetone.
[0049] In another embodiment, the removing does not include the use
of a solvent, but instead, the mechanical force is released or
release occurs by peeling the patterned sacrificial material 14
from the removable adhesive. When patterned sacrificial material 14
is removed, the materials on the top of the patterned sacrificial
material 14 are also removed from the structure. The material
stack, i.e., the battery stack material stack 18, that is present
on the surface of the bottom electrode 12 remains. The various
material layers of the battery stack material stack 18 that remains
on the surface of the bottom electrode have sidewall surfaces that
are vertically aligned to each other. For example, the material
layers of the lithium-based battery stack 18 shown in FIG. 3B that
remain on the surface of the bottom electrode have sidewall
surfaces that are vertically aligned to each other.
[0050] Referring now to FIG. 5, there is illustrated the exemplary
structure of FIG. 4 after forming an air and/or moisture
impermeable structure. The air and/or moisture impermeable
structure 30 includes any air and/or moisture impermeable material
or multilayered stack of such materials. Examples of air and/or
moisture impermeable materials that can be employed in the present
application include, but are not limited to, parylene, a
fluoropolymer, silicon nitride, and/or silicon dioxide. The air
and/or moisture impermeable structure 30 may be formed by first
depositing the air and/or moisture impermeable material and
thereafter patterning the air and/or moisture impermeable material.
In one embodiment, patterning may be performed by lithography and
etching. The air and/or moisture impermeable structure 30 is
located surrounding at least the sidewall surfaces of the battery
material stack 18.
[0051] The all solid-state battery of the present application may
be charged/recharged utilizing conventional techniques well known
to those skilled in the art. For example, the all solid-state
battery can be charged/recharged by connecting the all solid-state
to an external power supply. In some embodiments and for
solid-state lithium based batteries, the battery may have a fast
charge rate C, wherein C is the total charge capacity/hr. By "fast
charge rate C" it is meant a charge rate of 3 C or greater.
[0052] Referring now to FIGS. 6A and 6B, there are illustrated a
solid-state lithium-based battery of the present application prior
to and after charging, respectively. Each of the solid-state
lithium-based batteries shown in FIGS. 6A and 6B includes substrate
10 (as defined above), bottom electrode 12 (as defined above),
cathode layer 20A (i.e., a lithiated cathode material layer) of
LiCoO.sub.2 that has a thickness of less than 200 nm, a
lithium-based solid-state electrolyte layer 22A, and a top
electrode 28 (as defined above). A typically thickness range for
the LiCoO.sub.2 cathode is from 40 nm to 90 nm. In this embodiment
of the present application, the thickness of the lithiated cathode
material layer is typically less than 200 nm, with a range from 50
nm to 150 nm being more typical for the lithiated cathode material
layer.
[0053] During a charge/recharge process, anode region 26 (i.e., a
lithium accumulation region) as shown in FIG. 6B forms between the
top electrode 28 and the lithium-based solid-state electrolyte
layer 22A. The anode region 26 may, or may not, be a continuous
layer. Solid-state lithium-based batteries that contain a cathode
layer 20A of LiCoO.sub.2 that has a thickness of less than 200 nm
exhibit enhanced battery performance in terms of charge rate and
specific charge capacity. Notably, solid-state lithium-based
batteries that contain a cathode layer 20A of LiCoO.sub.2 that has
a thickness of less than 200 nm exhibit a charge rate of greater
than 10 C, and a specific charge capacity of greater than 100
mAh/g.
[0054] Referring now to FIG. 7, there is a graph of specific charge
capacity (mAh/g) vs. charge rate, C, of various solid-state
lithium-based batteries containing cathode layers having different
thicknesses. Notably, "A" represents a state lithium-based battery
as shown in FIG. 6A including a bottom electrode of Ti/Pt/Ti (5
nm/50 nm/5 nm), a lithiated cathode material layer of LiCoO.sub.2
that has a thickness of 45 nm, a lithium-based solid-state
electrolyte layer composed of LiPON having a thickness of 80 nm,
and a top electrode of Ni/Cu (50 nm/50 nm), "B" represents another
state lithium-based battery as shown in FIG. 6A including a bottom
electrode of Ti/Pt/Ti (5 nm/50 nm/5 nm), a lithiated cathode
material layer of LiCoO.sub.2 that has a thickness of 85 nm, a
lithium-based solid-state electrolyte layer composed of LiPON
having a thickness of 80 nm, and a top electrode of Ni/Cu (50 nm/50
nm), and "C" represents a comparative state lithium-based battery
including a bottom electrode of Ti/Pt/Ti (5 nm/50 nm/5 nm), a
lithiated cathode material layer of LiCoO.sub.2 that has a
thickness of 210 nm, a lithium-based solid-state electrolyte layer
composed of LiPON having a thickness of 80 nm, and a top electrode
of Ni/Cu (50 nm/50 nm). As can be seen in FIG. 7, batteries A and B
that contain a thin layer of LiCoO.sub.2 (less than 200 nm) as the
cathode layer have a charge rate of greater than 10 C, and a
specific charge capacity of greater than 100 mAh/g, while battery C
exhibited a lower specific charge capacity than either batter A or
battery B.
[0055] While the present application has been particularly shown
and described with respect to preferred embodiments thereof, it
will be understood by those skilled in the art that the foregoing
and other changes in forms and details may be made without
departing from the spirit and scope of the present application. It
is therefore intended that the present application not be limited
to the exact forms and details described and illustrated, but fall
within the scope of the appended claims.
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