U.S. patent application number 13/939912 was filed with the patent office on 2013-11-14 for vertical structure nonvolatile memory device.
The applicant listed for this patent is Sung-il Chang, Byeong-In Choe, Chang-seok Kang, Jin-soo Lim. Invention is credited to Sung-il Chang, Byeong-In Choe, Chang-seok Kang, Jin-soo Lim.
Application Number | 20130301350 13/939912 |
Document ID | / |
Family ID | 45063809 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130301350 |
Kind Code |
A1 |
Choe; Byeong-In ; et
al. |
November 14, 2013 |
Vertical Structure Nonvolatile Memory Device
Abstract
A vertical structure nonvolatile memory device can include a
channel layer that extends in a vertical direction on a substrate.
A memory cell string includes a plurality of transistors that are
disposed on the substrate in the vertical direction along a
vertical sidewall of the channel layer. At least one of the
plurality of transistors includes at least one recess in a gate of
the transistor into which at least one protrusion, which includes
the channel layer, extends.
Inventors: |
Choe; Byeong-In; (Yongin-si,
KR) ; Chang; Sung-il; (Hwaseong-si, KR) ;
Kang; Chang-seok; (Seongnam-si, KR) ; Lim;
Jin-soo; (Yongin-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Choe; Byeong-In
Chang; Sung-il
Kang; Chang-seok
Lim; Jin-soo |
Yongin-si
Hwaseong-si
Seongnam-si
Yongin-si |
|
KR
KR
KR
KR |
|
|
Family ID: |
45063809 |
Appl. No.: |
13/939912 |
Filed: |
July 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13152684 |
Jun 3, 2011 |
8513729 |
|
|
13939912 |
|
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Current U.S.
Class: |
365/184 ;
257/324 |
Current CPC
Class: |
H01L 29/7926 20130101;
H01L 27/11578 20130101; H01L 29/66825 20130101; H01L 27/11556
20130101; H01L 29/7889 20130101; H01L 27/11551 20130101; G11C
16/0483 20130101; H01L 29/66833 20130101; H01L 29/7827 20130101;
H01L 29/66666 20130101; G11C 16/0466 20130101 |
Class at
Publication: |
365/184 ;
257/324 |
International
Class: |
H01L 29/78 20060101
H01L029/78; G11C 16/04 20060101 G11C016/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2010 |
KR |
10-2010-0052366 |
Claims
1. A vertical structure nonvolatile memory device comprising: a
channel layer extending in a vertical direction on a substrate; and
a memory cell string comprising a plurality of transistors disposed
on the substrate in the vertical direction along a vertical
sidewall of the channel layer, wherein at least one of the
plurality of transistors includes at least one recess in a gate of
the transistor into which at least one protrusion, comprising the
channel layer, extends.
2. The vertical structure nonvolatile memory device of claim 1,
wherein the plurality of transistors of the memory cell string
comprise a plurality of memory cell transistors, and at least one
selection transistor disposed at one end or at both ends of the
memory cell string.
3. The vertical structure nonvolatile memory device of claim 2,
wherein the at least one recess and at least one protrusion are
included in the at least one selection transistor.
4. The vertical structure nonvolatile memory device of claim 1,
wherein an entire width of the channel layer protrudes into the
recess and is conformally on a surface of the recess.
5. The vertical structure nonvolatile memory device of claim 1,
wherein the at least one protrusion only protrudes into a middle
region of the gate between uppermost and lowermost surfaces of the
gate adjacent to respective interlayer insulating layers.
6. The vertical structure nonvolatile memory device of claim 5,
wherein the recess has a vertical dimension that is greater than
all of a remaining vertical dimension of the gate outside the
recess.
7. The vertical structure nonvolatile memory device of claim 5,
wherein the at least one recess and the at least one protrusion
comprises first and second recesses and first and second
protrusions disposed in first and second regions of the gate.
8. The vertical structure nonvolatile memory device of claim 1, the
structure further comprising: a first interlayer insulating layers
between immediately adjacent gates; and a second interlayer
insulating layer in the recess between a gate electrode of the gate
and the channel the channel layer.
9. The vertical structure nonvolatile memory device of claim 10,
wherein the second interlayer insulating layer between the channel
layer and the gate electrode has an etch selectivity different from
that of the first interlayer insulating layers.
10. The vertical structure nonvolatile memory device of claim 1,
wherein the first interlayer insulating layers are recessed from
sides of the gates adjacent to the channel layer, in the same
direction as the direction in which the at least one protrusion
extends into the recess.
11. The vertical structure nonvolatile memory device of claim 1,
wherein the gate comprises: a tunneling insulating layer, a charge
storage layer and a blocking insulating layer that are sequentially
stacked on the channel layer; and a gate electrode.
12. The vertical structure nonvolatile memory device of claim 11,
wherein the charge storage layer comprises at least one selected
from the group consisting of silicon nitride, polysilicon and fine
particles of a conductor in insulator.
13. The vertical structure nonvolatile memory device of claim 11,
wherein the tunneling insulating layer and the blocking insulating
layer comprise materials having a larger bandgap than a material of
the charge storage layer, and the blocking insulating layer has a
dielectric constant higher than that of the tunneling insulating
layer.
14. The vertical structure nonvolatile memory device of claim 1,
wherein the channel layer comprises an annular pillar region, and
the annular pillar region of the channel layer is filled with an
insulating pillar.
15. The vertical structure nonvolatile memory device of claim 1,
further comprising: a bit line coupled to one terminal of the
memory cell string; and a common source line coupled to a terminal
of the memory cell string opposite to the terminal coupled to the
bit line.
16. The vertical structure nonvolatile memory device of claim 1,
further comprising: a plurality of conductive lines disposed
between adjacent memory cell strings; and spacers disposed on
sidewalls of the memory cell strings to insulate the conductive
lines from the memory cell strings.
17. A vertical structure nonvolatile memory device comprising: a
plurality of transistors in a memory cell string, each including a
respective gate electrode; a recess in at least one of the gate
electrodes defining a portion of a non-planar surface of the at
least one gate electrode; and a channel layer protruding into the
recess and conformally on the portion of the non-planar
surface.
18. The vertical structure nonvolatile memory device according to
claim 17 wherein the at least one of the gate electrodes comprises
only first and second selection transistors at both ends of the
memory cell string.
19. The vertical structure nonvolatile memory device according to
claim 17, wherein the recess comprises a first recess and the
portion comprises a first portion, the device further comprising: a
second recess in the least one of the gate electrodes including the
at least one recess defining a second portion of the non-planar
surface therein, wherein the channel layer protrudes into the
second recess and is conformally on the second portion of the
non-planar surface.
20. A system comprising: a memory including a vertical structure
nonvolatile memory device comprising: a plurality of transistors in
a memory cell string, each including a respective gate electrode; a
recess in at least one of the gate electrodes defining a portion of
a non-planar surface of the at least one gate electrode; and a
channel layer protruding into the recess and conformally on the
portion of the non-planar surface, the system further comprising: a
processor configured to communicate with the memory via a bus; and
an input/output unit configured to communicate with the bus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority as a
continuation of U.S. application Ser. No. 13/152,684 filed Jun. 3,
2011, which claims the benefit of Korean Patent Application No.
10-2010-0052366, filed on Jun. 3, 2010. The disclosures of all of
the above referenced applications are hereby incorporated herein in
their entireties by reference.
BACKGROUND
[0002] The inventive concept relates to nonvolatile memory devices,
and more particularly, to nonvolatile memory devices having a
vertical channel structure.
[0003] Electronic appliances are becoming smaller in size, while
maintaining high data throughput. Non-volatile memory devices may
use a vertical transistor structure to increase integration
levels.
SUMMARY
[0004] Embodiments according to the inventive concept can provide
vertical structure nonvolatile memory devices. Pursuant to these
embodiments, a vertical structure nonvolatile memory device can
include a channel layer that extends in a vertical direction on a
substrate. A memory cell string includes a plurality of transistors
that are disposed on the substrate in the vertical direction along
a vertical sidewall of the channel layer. At least one of the
plurality of transistors includes at least one recess in a gate of
the transistor into which at least one protrusion, which includes
the channel layer, extends.
[0005] In some embodiments according to the inventive concept, the
plurality of transistors of the memory cell string can include a
plurality of memory cell transistors, and at least one selection
transistor that is disposed at one end, or at both ends, of the
memory cell string. In some embodiments according to the inventive
concept, the at least one recess and at least one protrusion are
included in the at least one selection transistor. In some
embodiments according to the inventive concept, an entire width of
the channel layer protrudes into the recess and is conformally on a
surface of the recess. In some embodiments according to the
inventive concept, the at least one protrusion only protrudes into
a middle region of the gate between uppermost and lowermost
surfaces of the gate adjacent to respective interlayer insulating
layers.
[0006] In some embodiments according to the inventive concept, the
recess has a vertical dimension that is greater than all of a
remaining vertical dimension of the gate outside the recess. In
some embodiments according to the inventive concept, the at least
one recess and the at least one protrusion includes first and
second recesses and first and second protrusions that are disposed
in first and second regions of the gate.
[0007] In some embodiments according to the inventive concept, the
structure can also include a first interlayer insulating layers
located between immediately adjacent gates. A second interlayer
insulating layer can be in the recess between a gate electrode of
the gate and the channel the channel layer. In some embodiments
according to the inventive concept, the second interlayer
insulating layer is between the channel layer and the gate
electrode and has an etch selectivity that is different from that
of the first interlayer insulating layers.
[0008] In some embodiments according to the inventive concept, the
first interlayer insulating layers are recessed from sides of the
gates adjacent to the channel layer, in the same direction as the
direction in which the at least one protrusion extends into the
recess. In some embodiments according to the inventive concept, the
gate can include a tunneling insulating layer, a charge storage
layer and a blocking insulating layer that are sequentially stacked
on the channel layer and a gate electrode
[0009] In some embodiments according to the inventive concept, a
vertical structure nonvolatile memory device can include a
plurality of transistors in a memory cell string, where each
includes a respective gate electrode. A recess can be included in
at least one of the gate electrodes to define a portion of a
non-planar surface of the at least one gate electrode. A channel
layer can protrude into the recess and is conformally on the
portion of the non-planar surface. In some embodiments according to
the inventive concept, the at least one of the gate electrodes is
only first and second selection transistors at both ends of the
memory cell string.
[0010] In some embodiments according to the inventive concept, the
recess is a first recess and the portion is a first portion where
the device further includes a second recess in the least one of the
gate electrodes including the at least one recess that defines a
second portion of the non-planar surface therein. The channel layer
protrudes into the second recess and is conformally on the second
portion of the non-planar surface.
[0011] In some embodiments according to the inventive concept, a
system can include a memory that includes a vertical structure
nonvolatile memory device which can include a plurality of
transistors in a memory cell string, where each includes a
respective gate electrode. A recess can be included in at least one
of the gate electrodes to define a portion of a non-planar surface
of the at least one gate electrode. A channel layer can protrude
into the recess and can be conformally on the portion of the
non-planar surface. The system can further include a processor
configured to communicate with the memory via a bus and an
input/output unit that can be configured to communicate with the
bus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an equivalent circuit diagram of a memory cell
array of a nonvolatile memory device in some embodiments according
to the inventive concept.
[0013] FIG. 2 is a cross-sectional view of a vertical structure
nonvolatile memory device in some embodiments according to the
inventive concept.
[0014] FIGS. 3 through 10 are cross-sectional views describing
methods of fabricating the nonvolatile memory device in some
embodiments according to the inventive concept.
[0015] FIGS. 11 and 12 are plan views illustrating the relative
positions of channel layers with respect to bit lines in the
vertical structure nonvolatile memory device in some embodiments
according to the inventive concept.
[0016] FIG. 13 is a cross-sectional view of a vertical structure
nonvolatile memory device in some embodiments according to the
inventive concept.
[0017] FIGS. 14 through 16 are graphs illustrating the results of
simulation of potential distribution in the vertical structure
nonvolatile memory device of FIG. 13.
[0018] FIG. 17 is a cross-sectional view of a vertical structure
nonvolatile memory device in some embodiments according to the
inventive concept.
[0019] FIG. 18 is a cross-sectional view of a vertical structure
nonvolatile memory device in some embodiments according to the
inventive concept.
[0020] FIG. 19 is a cross-sectional view of a vertical structure
nonvolatile memory device in some embodiments according to the
inventive concept.
[0021] FIGS. 20 through 23 are cross-sectional views for describing
a method of fabricating the vertical structure nonvolatile memory
device of FIG. 19.
[0022] FIG. 24 is a block diagram of a nonvolatile memory device in
some embodiments according to the inventive concept.
[0023] FIG. 25 is a schematic view illustrating a memory card
according in some embodiments according to the inventive
concept.
[0024] FIG. 26 is a block diagram of an electronic system in some
embodiments according to the inventive concept.
DESCRIPTION OF EMBODIMENTS ACCORDING TO THE INVENTIVE CONCEPT
[0025] The inventive concept will now be described more fully with
reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown.
[0026] This invention may, however, be embodied in many different
forms and should not be construed as limited to the exemplary
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete, and
will fully convey the scope of the invention to those of ordinary
skill in the art.
[0027] It will be understood that when an element or layer is
referred to as being "on" another element or layer, the element or
layer can be directly on another element or layer or intervening
elements or layers. In contrast, when an element is referred to as
being "directly on" another element or layer, there are no
intervening elements or layers present. In the drawings, lengths
and sizes of layers and regions may be exaggerated for clarity.
Like reference numerals refer to like elements throughout. As used
herein, the term "and/or" includes any and all combinations of one
or more of the associated listed items.
[0028] The terms used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, components, and/or groups thereof, but
do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof.
[0029] It will be understood that, although the terms first,
second, third, etc., may be used herein to describe various
elements, components, regions, layers and/or sections, these
elements, components, regions, layers and/or sections should not be
limited by these terms. These terms are only used to distinguish
one element, component, region, layer or section from another
region, layer or section. Thus, a first element, component, region,
layer or section discussed below could be termed a second element,
component, region, layer or section without departing from the
teachings of the inventive concept.
[0030] Embodiments of the invention are described herein with
reference to illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures) of the
invention. As such, variations from the shapes of the illustrations
as a result, for example, of manufacturing techniques and/or
tolerances, are to be expected. Thus, embodiments of the invention
should not be construed as limited to the particular shapes of
regions illustrated herein but are to include deviations in shapes
that result, for example, from manufacturing.
[0031] Hereinafter, embodiments of vertical structure nonvolatile
semiconductor memory devices according to the inventive concept
will be described with reference to nonvolatile NAND flash memory
devices. Vertical structure nonvolatile memory devices can retain
stored data even when power is not supplied.
[0032] FIG. 1 is an equivalent circuit diagram of a memory cell
array of a nonvolatile memory device in some embodiments according
to the inventive concept.
[0033] Referring to FIG. 1, the memory cell array 10 includes a
plurality of memory cell strings 11. Each memory cell string 11 may
have a vertical structure extending substantially perpendicular to
a main surface of a substrate. The plurality of memory cell strings
11 may constitute a memory cell block 13.
[0034] Each of the plurality of memory cell strings 11 includes a
plurality of memory cells MC1-MCn, a string selection transistor
SST, and a ground selection transistor GST. The ground selection
transistor GST, the memory cells MC1-MCn, and the string selection
transistor SST of each of the memory cell strings 11 may be
serially arranged in a vertical direction. The plurality of memory
cells MC1-MCn may store data. A plurality of word lines WL1-WLn are
connected to the memory cells MC1-MCn, respectively, to control the
memory cells MC1-MCn. The number of memory cells MC1-MCn may vary
according to the capacity of the nonvolatile memory device.
[0035] The memory cell strings 11 are respectively arranged in
1.sup.st-m.sup.th columns of the memory cell block 13. One end of
each of the memory cell strings 11, for example drain sides of the
respective string selection transistors SST, may be respectively
coupled to a plurality of bit lines BL1-BLm. The other end of each
of the memory cell strings 11, for example source sides of the
ground selection transistors GST, may be coupled to a common source
line CSL.
[0036] A plurality of word lines WL1-WLn may be respectively
coupled to rows of the memory cells MC1-MCn of the plurality of
memory cell strings 11. Data may be written to or may be read (or
erased) from the plurality of memory cells MC1-MCn upon activation
of the word lines WL1-WLn.
[0037] The string selection transistors SST of the memory cell
strings 11 may be arranged between the corresponding bit lines
BL1-BLm and the memory cells MC1-MCn. String selection lines SSLs
are respectively coupled to the gates of the string selection
transistors SST, and thus may control data transfer between the bit
lines BL1-BLm and the memory cells MC1-MCn in the memory cell block
13.
[0038] The ground selection transistors GST may be arranged between
the common source line CSL and the plurality of memory cells
MC1-MCn. Ground selection lines GSL are respectively coupled to the
gates of the ground selection transistors GST, and thus may control
data transfer between the common source line CSL and the memory
cells MC1-MCn in the memory cell block 13.
[0039] FIG. 2 is a cross-sectional view of a vertical structure
nonvolatile memory device in some embodiments according to the
inventive concept.
[0040] Referring to FIG. 2, the nonvolatile memory device 1
includes a substrate 100 whose main surface extends in a first
direction (i.e., an x-axis direction in FIG. 2). The substrate 100
may contain a semiconductor material, for example, a Group IV
semiconductor, a Group III-V compound semiconductor, or a Group
II-VI oxide semiconductor. Examples of the Group IV semiconductor
include silicon, germanium, and silicon-germanium. The substrate
100 may be a bulk wafer or an epitaxial layer.
[0041] A channel layer 140, including a protrusion, extends on the
substrate 100 in a second direction (i.e., a y-axis direction of
FIG. 2) substantially perpendicular to the first direction in which
the main surface of the substrate 100 extends. A gate insulating
layer 157 is disposed on a portion of the channel layer 140. The
channel layer 140 may be in the form of an annular pillar filled
with a channel hole insulating layer 115.
[0042] A plurality of transistors 170 are vertically disposed on an
upper surface of the substrate 100 in the second direction (i.e.,
the y-axis direction of FIG. 2) along the channel layer 140. One
channel layer 140 and the plurality of transistors 170, which are
disposed in the second direction along the channel layer 140
constitute one of the memory cell strings 11 (see FIG. 1).
[0043] Each of the memory cell strings 11 (see FIG. 1) includes a
plurality of first transistors 172, which constitute a plurality of
memory cells, and second transistors 176 and 178, which constitute
selection transistors. In the nonvolatile memory device 10 having
the configuration of FIG. 1, the second transistors 176 and 178 of
each of the memory cell strings 11 may include one ground selection
transistor 176 and one string selection transistor 178.
[0044] A bit line may be coupled to the string selection transistor
178, which constitutes the second transistors 176 and 178, as
illustrated in FIG. 1. The bit line may extend in a linear pattern
in the first direction (the x-axis direction of FIG. 2). The bit
line may be coupled to one of the selection transistors 176 and
178, for example, the string selection transistor 178, via a
contact.
[0045] The channel layers 140 have protrusions extending in the
first direction (the x-axis direction in FIG. 2). Gates 150,
including the gate insulating layer 157 and a gate electrode 159,
have uneven structures conforming to the protrusions of the channel
layers 140. As used herein, the term "uneven structure" refers to
both a protrusion and a recess having an opposite pattern to the
protrusion. The protrusions of the channel layers 140 may be
located in the middles of the gates 150, i.e., between upper and
lower portions of the gates 150 disposed on the substrate 100 in a
vertical direction. The protrusions may have a vertical dimension
that is larger than those of upper and lower portions of the gates
150 divided by the protrusions. The protrusions of the channel
layers 140 may also extend in a third direction (i.e., a z-axis
direction of FIG. 2). The protrusions of the channel layers 140 may
have dimensions in the first direction (the x-axis direction of
FIG. 2) that are smaller than the dimensions of the transistors
170. The uneven structures of the gates 150 may have any of various
lengths and shapes, and are not limited to the exemplary embodiment
illustrated in FIG. 2.
[0046] It will be understood that the uneven structure can define
at least one recess in the surface of the gate 150 where the
channel layer 140 conformally protrudes into the recess. The
recess, therefore, defines the profile of the gate surface at the
channel layer 140 as being non-planar.
[0047] The plurality of first transistors 172 among the plurality
of transistors 170, which constitute the plurality of memory cells,
may respectively include the gates 150, which include the gate
insulating layer 157 and the gate electrode 159 sequentially
disposed on a sidewall of the channel layers 140.
[0048] The selection transistors 176 and 178 among the plurality of
transistors 170 may respectively include the gates 150, which
include the gate insulating layer 157 and the gate electrode 159
sequentially disposed on the sidewall of the channel layers
140.
[0049] The gate insulating layer 157 may have a stack structure in
which a tunneling insulating layer 152, a charge storage layer 154
and a blocking insulating layer 156 are sequentially stacked on the
sidewall of the channel layers 140 in the order stated.
[0050] The tunneling insulating layer 152 may be a single layer or
a multi-layer including at least one material selected from the
group consisting of silicon oxide (SiO.sub.2), silicon nitride
(Si.sub.3N.sub.4), silicon oxynitride (SiON), hafnium oxide
(HfO.sub.2), hafnium silicon oxide (HfSi.sub.xO.sub.y), aluminum
oxide (Al.sub.2O.sub.3), and zirconium oxide (ZrO.sub.2).
[0051] The charge storage layer 154 may be a charge trapping layer
or a floating gate conductive layer. When the charge storage layer
154 is a floating gate conductive layer, the charge storage layer
154 may be formed using chemical vapor deposition (CVD). For
example, the charge storage layer 154 may be formed by causing a
SiH.sub.4 or Si.sub.2H.sub.6 gas and a PH.sub.3 gas to flow by
using low-pressure chemical vapor deposition (LPCVD) to deposit
polysilicon. When the charge storage layer 154 is a charge trapping
layer, the charge storage layer 154 may be formed as a single layer
or a multi-layer including at least one material selected from the
group consisting of silicon oxide (SiO.sub.2), silicon nitride
(Si.sub.3N.sub.4), silicon oxynitride (SiON), hafnium oxide
(HfO.sub.2), zirconium oxide (ZrO.sub.2), tantalum oxide
(Ta.sub.2O.sub.3), titanium oxide (TiO.sub.2), hafnium aluminum
oxide (HfAl.sub.xO.sub.y), hafnium tantalum oxide
(HfTa.sub.xO.sub.y), hafnium silicon oxide (HfSi.sub.xO.sub.y),
aluminum nitride (Al.sub.xN.sub.y), and aluminum gallium nitride
(AlGa.sub.xN.sub.y). The charge storage layer 154 may include
quantum dots or nanocrystals. In this regard, the quantum dots or
nanocrystals may include fine particles of a conductor, such as a
metal or a semiconductor.
[0052] The blocking insulating layer 156 may be formed as a single
layer or a multi-layer including at least one material selected
from the group consisting of silicon oxide (SiO.sub.2), silicon
nitride (Si.sub.3N.sub.4), silicon oxynitride (SiON), and a high-k
dielectric material. The blocking insulating layer 156 may be
formed of a higher-k dielectric material than the tunneling
insulating layer 152. The higher-k dielectric material may include
at least one material selected from the group consisting of
aluminum oxide (Al.sub.2O.sub.3), tantalum oxide (Ta.sub.2O.sub.3),
titanium oxide (TiO.sub.2), yttrium oxide (Y.sub.2O.sub.3),
zirconium oxide (ZrO.sub.2), zirconium silicon oxide
(ZrSi.sub.xO.sub.y), hafnium oxide (HfO.sub.2), hafnium silicon
oxide (HfSi.sub.xO.sub.y), lanthanum oxide (La.sub.2O.sub.3),
lanthanum aluminum oxide (LaAl.sub.xO.sub.y), lanthanum hafnium
oxide (LaHf.sub.xO.sub.y), hafnium aluminum oxide
(HfAl.sub.xO.sub.y), and praseodymium oxide (Pr.sub.2O.sub.3).
[0053] The gate electrode 159 may be formed as a single layer or a
multi-layer including at least one material selected from the group
consisting of polysilicon, aluminum (Al), gold (Au), beryllium
(Be), bismuth (Bi), cobalt (Co), hafnium (Hf), indium (In),
manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), palladium
(Pd), platinum (Pt), rhodium (Rh), rhenium (Re), ruthenium (Ru),
tantalum (Ta), tellurium (Te), titanium (Ti), tungsten (W), zinc
(Zn), and zirconium (Zr).
[0054] Impurity regions 105 may be defined in the upper surface of
the substrate 100. The impurity regions 105 may be coupled to the
common source line (CSL) 180. The impurity regions 105 may also
form PN junctions with other regions of the substrate 100. The
length of the common source lines (CSL) 180 in the second direction
(the y-axis direction of FIG. 2) are not limited to the exemplary
embodiment illustrated in FIG. 2. For example, the common source
lines (CSL) 180 may be shorter than those illustrated in FIG. 2.
Spacers 117 of an insulating material may be disposed on the
sidewalls of the common source lines (CSL) 180.
[0055] The channel layers 140 may be sequentially doped with
impurities having the same conductivity type to define a series of
wells or channels that contribute to the operation of the plurality
of memory cells MC1-MCn. In this case, during a writing or reading
operation, the memory cells MC1-MCn may be connected via field
effect sources/drains. Surfaces of the channel layers 140 between
the memory cells MC1-MCn may be turned on using a lateral electric
field, i.e., a fringing field, of the gate electrodes 159. This may
also apply to the channel layers 140 between the string selection
transistors 178, and to the channel layers 140 between the ground
selection transistors 176.
[0056] Interlayer insulating layers 110 may be disposed on the
channel layers 140 between the plurality of transistors 170,
including the first transistors 172 and the second transistors 176
and 178.
[0057] In the vertical structure nonvolatile memory device 1
according to the current embodiment, the gates 150 are configured
to have uneven (or non-planar) structures to increase lengths of
the channel layers 140, without increasing transistor size. Thus,
reductions in memory cell string current and threshold voltage, may
reduce short channel effects in the device.
[0058] FIGS. 3 through 10 are cross-sectional views for describing
a method of fabricating the nonvolatile memory device 1 of FIG. 2,
according to an exemplary embodiment.
[0059] Referring to FIG. 3, a plurality of interlayer insulating
layers 110 and a plurality of sacrificial layers 120 are
alternately stacked on the substrate 100. Each of the sacrificial
layers 120 includes a first sacrificial layer 124 and two second
sacrificial layers 122 stacked respectively on upper and lower
surfaces of the first sacrificial layer 124. The interlayer
insulating layers 110, the first sacrificial layers 124 and the
second sacrificial layers 122 may be formed of materials having
different etch selectivity with respect to adjacent sacrificial
layers. The etch selectivity may be quantified as an etch rate of
one layer to another. In the current embodiment, the interlayer
insulating layers 110 and the second sacrificial layers 122 may be
formed of materials having an etch selectivity of about 1:10 to
about 1:200 with respect to the first sacrificial layers 124. The
interlayer insulating layers 110 may be formed of a material having
an etch selectivity of about 1:10 to about 1:200 with respect to
the second sacrificial layers 122. For example, the plurality of
interlayer insulating layers 110 may be formed of a silicon oxide
layer. The plurality of first sacrificial layers 124 may be formed
of a silicon nitride layer. The plurality of second sacrificial
layers 122 may be formed of a silicon carbide layer or an amorphous
carbon layer (ACL).
[0060] The number of sacrificial layers 120 may be varied according
to the memory device to be fabricated. The larger the number of
sacrificial layers 120, the more the memory cells per unit area.
The thicknesses of the individual interlayer insulating layers 110
and the individual sacrificial layers 120 may not be completely the
same. The uppermost interlayer insulating layer among the plurality
of interlayer insulating layers 110 may have a thickness larger
than the thicknesses of the underlying interlayer insulating layers
110.
[0061] Referring to FIG. 4, the plurality of interlayer insulating
layers 110 and the plurality of sacrificial layers 120 may be
etched using photolithography to form a plurality of channel holes
132 exposing the substrate 100. The channel holes 132 may be
isolated from each other in the first and second directions (the
x-axis and y-axis directions of FIG. 2).
[0062] Forming the plurality of channel holes 132 may be provided
by forming a predetermined mask pattern on the uppermost interlayer
insulating layer 110 to define the locations of the channel holes
132, and anisotropically etching the stacked structure, including
the interlayer insulating layers 110 and the sacrificial layers
120, by using the mask pattern as an etch mask. Side walls of the
plurality of channel holes 132 may not be completely perpendicular
to the upper surface of the substrate 100, since the stacked
structure includes at least three different kinds of materials
layers. For example, the closer to the substrate 100, the smaller
the width of the channel holes 132 may be. If the stack structure
on the substrate 100 is over-etched during the anisotropic etching
process to define the channel holes 132, the upper surface of the
substrate 100 may be recessed to a predetermined depth, as
illustrated in FIG. 4.
[0063] Referring to FIG. 5, the first sacrificial layers 124
exposed by the plurality of channel holes 132 are partially
recessed beyond sidewalls of the channel hole 132. This process may
be performed using an etchant that may selectively etch only the
first sacrificial layers 124 with respect to the interlayer
insulating layers 110 and the second sacrificial layers 122. The
dimensions of the protrusions of the channel layers 140 (see FIG.
2) extending in the first direction (the x-axis direction of FIG.
2) are determined according to the extent to which the first
sacrificial layers 124 are etched. As a result of the etching
process, the channel holes 132 are formed having uneven
(non-planar) shapes.
[0064] Referring to FIG. 6, a semiconductor material and an
insulating material are sequentially deposited in the channel holes
132, followed by a planarization process in which the semiconductor
material and the insulating material covering the uppermost
interlayer insulating layer 110 are removed until the uppermost
interlayer insulating layer 110 is exposed to provide channel
layers 140 and channel hole insulating layer 115. For example, the
planarization process may be performed using chemical mechanical
polishing (CMP) or an etch-back process. For example, the channel
layers 140 may be formed of silicon. The channel layers 140 may be
formed as polycrystalline or monocrystalline Si epitaxial layers.
The channel hole insulating layers 115 may include an oxide layer
such as Undoped Silica Glass (USG), Spin On Glass (SOG) or Tonen
SilaZene (TOSZ).
[0065] A conductive layer may be formed on the uppermost channel
layer 140 to define metal contacts or plugs to be coupled to the
bit lines. For example, the channel hole insulating layers 115 may
be etched from their top regions to a predetermined thickness to
form trenches, and the trenches may be filled with conductive
layers.
[0066] Referring to FIG. 7, the interlayer insulating layers 110
and the sacrificial layers 120 between each two adjacent channel
layers 140 are etched to form a plurality of openings 134 exposing
the upper surface of the substrate 100. Only one of the plurality
of openings 134 is illustrated in FIG. 7. The plurality of openings
134 may be formed using photolithography.
[0067] Referring to FIG. 8, the second sacrificial layers 122 and
the first sacrificial layers 124 exposed by the plurality of
openings 134 are removed.
[0068] For example, the second and first sacrificial layers 122 and
124 may be removed using isotropic etching. An etchant may be
permeated between the plurality of interlayer insulating layers 110
through the openings 134. The isotropic etching process may be wet
etching or chemical dry etching (CDE). The second sacrificial
layers 122 and the first sacrificial layers 124 may be
simultaneously etched using the same kind of etchant.
Alternatively, the second sacrificial layers 122 and the first
sacrificial layers 124 may be separately etched one after another
using different etchants.
[0069] As a result of removing the plurality of first sacrificial
layers 124 and the plurality of second sacrificial layers 122 from
between the plurality of interlayer insulating layers 110, a
plurality of tunnels 134T in the openings 134 are formed between
the plurality of interlayer insulating layers 110. The plurality of
tunnels 134T expose the sidewalls of the channel layers 140.
[0070] Referring to FIG. 9, the gate insulating layer 157 is formed
to cover the surfaces of the plurality of interlayer insulating
layers 110 and the channel layers 140 exposed by the plurality of
openings 134. The gate insulating layer 157 may have a stacked
structure in which a tunneling insulating layer 152, a charge
storage layer 154 and a blocking insulating layer 156 are
sequentially stacked on a sidewall of the channel layers 140 in the
order stated. Then, a conductive material is deposited into the
openings 134 so as to completely fill the plurality of tunnels
134T, which are interconnected with the openings 134, on the
sidewalls of the channel layers 140, followed by removing the
unnecessary conductive material from the openings 134 until the
conductive material remains only within the plurality of tunnels
134T, thus resulting in the gate electrodes 159.
[0071] The gate insulating layer 157 and the gate electrodes 159
may be formed using chemical vapor deposition (CVD) or
electroplating. For example, the gate electrodes 159 may be formed
of tungsten.
[0072] The gates 150 of the plurality of transistors 170 may be
respectively coupled to the string selection lines SSL, the ground
selection lines GSL and the word lines WL0-WLn via contact plugs in
the periphery of cell memory regions. Since the selection
transistors 176 and 178 includes only one selection transistor,
i.e., respectively, a single ground selection transistor GST and a
single string selection transistor SST, instead of a pair of
transistors, it is sufficient to connect only one contact plug to
each of the string selection line SSL and the ground selection line
GSL. Thus, the overall process may be simplified compared to when a
pair of transistors should be connected to each of the selection
lines.
[0073] Referring to FIG. 10, the upper surface of the substrate 100
exposed by the plurality of openings 134 may be doped with
impurities to form impurity regions 105. The impurity regions 105
may be heavily-doped impurity regions formed by injecting
N.sup.+-type impurity ions. The process of forming the impurity
regions 105 in the upper surface of the substrate 100 exposed by
the openings 134 may be performed in any preceding or subsequent
processes. The impurity regions 105 may function as common source
regions. The spacers 117 may be formed on the sidewalls of the
openings 134 defined in the substrate 100. The spacers 117 may be
formed to cover the parts of the gate insulating layers 157 and the
gate electrodes 159 exposed by the openings 134. The spacers 117
may be formed by depositing an insulating layer on the surfaces of
the channel hole insulating layers 115 so as to fill the openings
134, and etching the insulating layer using, for example, an
etch-back process. The insulating layer for forming the spacers 117
may include a silicon nitride layer.
[0074] Then, a conductive material is deposited between the spacers
117 in the openings 134 to form conductive lines. The conductive
lines may constitute the common source lines (CSL) 180 of FIG. 2
connected to the impurity regions 150, and may be coupled to
sources of the ground selection transistors 176. The nonvolatile
memory device 1 of FIG. 2 may be fabricated through the processes
described above.
[0075] FIGS. 11 and 12 are plan views illustrating the relative
positions of the channel layers 140 with respect to the bit lines
190, according to exemplary embodiments, in the vertical structure
nonvolatile memory device.
[0076] In some embodiments according to the inventive concept, the
channel layers 140 may be in the form of annular pillars filled
with the channel hole insulating layers 115, as illustrated in FIG.
11. The bit lines 190 may be disposed to completely cover upper
ends of the channels layers 140, as illustrated in FIG. 1.
Alternatively, the bit lines 190 may be disposed to partially cover
the upper ends of the channel layers 140, as illustrated in FIG.
12. Furthermore, as described above with reference to FIG. 6, the
channel layers 140 may be coupled to the bit lines 190 via metal
contacts or plugs formed from the conductive layers deposited on
the channel layers 140.
[0077] FIG. 13 is a cross-sectional view of a vertical structure
nonvolatile memory device 2 according to another embodiment of the
present inventive concept.
[0078] Referring to FIG. 13, the channel layers 140 have
protrusions only in regions adjacent to the gates 150 of the string
selection transistor 178 and the ground selection transistor 176.
This configuration may be implemented if, for example, in the
fabrication processes described with reference to FIGS. 3 to 10,
the first sacrificial layer 124 is deposited only between the
uppermost pair and between the lowermost pair of second sacrificial
layers 122 in which the selection transistors 176 and 178 are to be
defined, during the process described above with reference to FIG.
3. In the nonvolatile memory device 2, the selection transistors
176 and 178 have extended channel lengths. Thus, a larger amount of
current may flow in the memory cell strings.
[0079] FIGS. 14 through 16 are graphs illustrating the results of
simulation of potential distribution in the vertical structure
nonvolatile memory device 2 of FIG. 13.
[0080] FIG. 14 illustrates the distributions of potential in the
gate of a selection transistor having the uneven structure
illustrated in FIG. 13 in the first and second directions (x-axis
and y-axis directions of FIG. 14), as opposed to the distributions
of potential in the two gates of a paired-selection transistor
structure consisting of a pair of transistors. The paired-selection
transistor structure refers to a selection transistor configuration
consisting of a pair of separate transistors that are serially
disposed. FIG. 14 illustrates the distributions of potential when a
voltage of 6V was applied to the selection translator structures
whose channel layers include an insulating layer, a channel layer,
and a gate insulating layer, shown from left to right in FIG. 14,
which are stacked upon one another. For the selection transistor
having the uneven structure of FIG. 13, a higher level of potential
was distributed in the middle region (B) of the uneven structure in
the second direction (the y-axis direction of FIG. 14), compared to
the paired-selection transistor structure. In particular, in the
region of the uneven structure in the coordinates of about 0.08 um
or more in the first direction (the x-axis direction of FIG. 14),
the potential was maintained as high as 6.0V or greater.
[0081] FIG. 15 is a graph illustrating the distributions of
potential in an upper region (A) and middle region (B) of each of
the selection transistor structures in the first direction (the
x-axis direction of FIG. 14). Referring to FIG. 15, in the upper
regions (A), there was substantially no potential difference
between the selection transistor having the uneven structure and
the paired-selection transistor structure. However, in the middle
region (B) of the selection transistor having the uneven structure,
the potential level was higher than the paired-selection transistor
structure.
[0082] FIG. 16 is a graph illustrating the distributions of
potential in the selection transistor structures in the second
direction (the y-axis direction of FIG. 14). Referring to FIG. 16
the selection transistor having the uneven structure had a higher
potential distribution in the middle region (B) than the
paired-selection transistor structure. Therefore, the vertical
structure nonvolatile memory device, according to embodiments of
the inventive concept, having the uneven structure between the gate
of the selection transistor and the channel may improve the control
ability of the gate. In addition, the switching performance of the
selection transistor may be improved.
[0083] FIG. 17 is a cross-sectional view of a vertical structure
nonvolatile memory device 3 according to another embodiment.
[0084] Referring to FIG. 17, in the nonvolatile memory device 3,
the sides of the interlayer insulating layers 110 adjacent to the
channel layers 140 are recessed in the first direction (an x-axis
direction of FIG. 7) with respect to the gates 150 of the
transistors 170 so as to expose surface edge portions of the gates
150. The exposed surface edge portions of the gates 150 are covered
by the channel layers 140. This configuration may be implemented
if, for example, in the fabrication processes described with
reference to FIGS. 3 to 10, the first sacrificial layers 124 and
the interlayer insulating layers 110 are formed of the same
material or materials having substantially the same etch
selectivity in an etchant with respect to the second sacrificial
layers 122, and the interlayer insulating layers 110 are partially
removed together with the first sacrificial layers 124 in the
etching process described with reference to FIG. 5. In the
nonvolatile memory device 3 according to the current embodiment,
the transistors 170 may have further extended channel lengths.
[0085] FIG. 18 is a cross-sectional view of a vertical structure
nonvolatile memory device 4 according to another embodiment.
[0086] Referring to FIG. 18, in the nonvolatile memory device 4,
portions of the channel layers 140 associated with the selection
transistors 176 and 178, have uneven structures in regions adjacent
to the gates 150, which include the gate insulating layers 157 and
the gate electrodes 159. Each uneven structure includes two
protrusions in upper and lower regions of the channel layer 140.
This configuration may be implemented if, for example, in the
fabrication processes described with reference to FIGS. 3 to 10,
the second sacrificial layers 122 on the upper and lower surfaces
of the first sacrificial layers 124 are partially removed, instead
of the first sacrificial layers 124, during the process described
with reference to FIG. 5. Though only the selection transistors 176
and 178 have the uneven structures in FIG. 18, the inventive
concept is not limited thereto. For example, the second transistors
172 may also have such uneven structures, with multiple protrusions
per gate.
[0087] FIG. 19 is a cross-sectional view of a vertical structure
nonvolatile memory device 5 according to another embodiment.
[0088] Referring to FIG. 19, in the nonvolatile memory device 5,
the gates 150 of the selection transistors 176 and 178, which
include the gate insulating layers 157 and the gate electrodes 159,
have uneven structures each including a recess in the middle of the
gate 150 that deepens in the first direction (an x-axis direction
of FIG. 9). Spaces between the recesses of the gates 150 and the
channel layers 140 are filled with second interlayer insulating
layers 112. The second interlayer insulating layers 112 may contain
a material having a different etch selectivity from the first
interlayer insulating layers 110 disposed between the plurality of
first transistors 172 and between one of the first transistors 172
and the selection transistors 176 and 178. The recesses may be
located in the middles of the gates 150 of the transistors 170 in
the second direction (a y-axis direction of FIG. 19, and may also
extend in a third direction (a z-axis direction of FIG. 9). The
recesses may have a dimension in the first direction (the x-axis
direction of FIG. 9) that is smaller than the dimension of the
transistors 170. Though only the selection transistors 176 and 178
have the uneven structures in FIG. 19, the inventive concept is not
limited thereto. For example, the second transistors 172 may also
have such uneven structures including insulating layers between the
gates 150 and the channel layers 140.
[0089] In the vertical structure nonvolatile memory device 5
according to the current embodiment, each of the selection
transistors 176 and 178 is configured to include at least two parts
interconnected so as to be filled with an electrode material
without a void, unlike in a single transistor without recesses, to
form the gate electrode 159 between the first interlayer insulating
layers 111. In addition, since the gate electrodes 159 are
connected within memory cell strings, wiring processes may be
simplified, compared to the configuration in which each selection
transistor includes a pair of serially disposed transistors.
[0090] FIGS. 20 through 23 are cross-sectional views for describing
a method of fabricating the vertical structure nonvolatile memory
device 5 of FIG. 19, according to an exemplary embodiment.
[0091] Referring to FIG. 20, the plurality of first and second
interlayer insulating layers 111 and 112, and the plurality of
sacrificial layers 125 are alternately stacked on the substrate 100
in substantially the same manner as described above with reference
to FIG. 3, except that the second interlayer insulating layers 112
are stacked as the second end insulating layers from the upper and
lower surfaces of the stack structure on the substrate 100, while
the first interlayer insulating layers 111 constitute the other
insulating layers. The first interlayer insulating layers 111 and
the second interlayer insulating layers 112 may contain materials
having different etch selectivity.
[0092] Referring to FIG. 21, the plurality of first interlayer
insulating layers 111, the plurality of second interlayer
insulating layers 112, and the plurality of sacrificial layers 125
are etched in the same manner as described with reference to FIG.
4, to form the plurality of channel holes 132 (see FIG. 4). Then, a
semiconductor material and an insulating material are sequentially
deposited in the channel holes 132, followed by chemical mechanical
polishing (CMP) or performing an etch-back process to form the
channel layers 140 and the channel hole insulating layers 115 in
the channel holes 132. For example, the channel layers 140 may be
formed as polycrystalline or monocrystalline Si epitaxial
layers.
[0093] Referring to FIG. 22, the plurality of first interlayer
insulating layers 111, the plurality of second interlayer
insulating layers 112 and the plurality of sacrificial layers 125
between each two adjacent channel layers 140 are etched to form a
plurality of openings 134 exposing the upper surface of the
substrate 100. Then, the plurality of sacrificial layers 125
exposed by the plurality of openings 134 are removed, and the
second interlayer insulating layers 112 are partially removed. The
sacrificial layers 125 and the second interlayer insulating layers
112 may be simultaneously etched using the same kind of etchant.
Alternatively, the sacrificial layers 125 and the second interlayer
insulating layers 112 may be separately etched one after another
using different kinds of etchants.
[0094] As a result, a plurality of tunnels 134T interconnected with
the openings 134 are formed between adjacent first interlayer
insulating layers 111. Sidewalls of the channel layers 140 are
exposed by the tunnels 134T. The second interlayer insulating
layers 112 may be partially etched to have dimensions in the first
direction (the x-axis direction of FIG. 19) that are smaller than
the dimensions of the first interlayer insulating layers 111.
[0095] Referring to FIG. 23, after the processes described above
with reference to FIG. 9 are performed, the upper surface of the
substrate 100 exposed by the openings 134 is doped with impurities
in a similar manner as described above with reference to FIG. 10,
to form impurity regions 105. Then, an insulating layer is
deposited to form spacers 117 on the sidewalls of the openings 134
defined in the substrate 100. The insulating layer for forming the
spacers 117 may include a silicon nitride layer.
[0096] Then, a conductive material is deposited between the spacers
117 in the openings 134 to form conductive lines 180 (see FIG. 19).
The conductive lines 180 may constitute the common source lines
(CSL) 180 of FIG. 19, and may be coupled to sources of the ground
selection transistors 172. The nonvolatile memory device 5 of FIG.
19 may be fabricated through the processes described above.
[0097] In the nonvolatile memory device according to embodiments of
the present inventive concept, channel layers may have a
macaroni-like cylindrical structure surrounding an insulating
pillar. However, the inventive concept is not limited to the
structure of the channel layers. For example, channel layers may be
in the form of lines. For example, linear channel layers may be
formed on the sidewalls of insulating pillars.
[0098] FIG. 24 is a block diagram illustrating a nonvolatile memory
device 700 according to an exemplary embodiment.
[0099] Referring to FIG. 24, in the nonvolatile memory device 700,
a NAND cell array 750 may be coupled to a core circuit unit 770.
For example, the NAND cell array 750 may include at least one of
the nonvolatile memory devices 1-5 respectively described above
with reference to FIGS. 2, 13, 17, 18 and 19. The core circuit unit
770 may include a control logic 771, a row decoder 772, a column
decoder 773, a sense amplifier 774, and a page buffer 775.
[0100] The control logic 771 may communicate with the row decoder
772, the column decoder 773, and the page buffer 775. The row
decoder 772 may communicate with the NAND cell array 750 via a
plurality of string selection lines SSL, a plurality of word lines
WL, and a plurality of ground selection lines GSL. The column
decoder 773 may communicate with the NAND cell array 750 via a
plurality of bit lines BL. The sense amplifier 774 may be connected
to the column decoder 733 to receive an output from the column
decoder 773 when a signal is output from the NAND cell array
750.
[0101] For example, the control logic 771 may transmit a row
address signal to the row decoder 772, and the row decoder 772 may
decode the row address signal and transmit the same to the NAND
cell array 750 via the string selection lines SSL, the word lines
WL, and the ground selection lines GSL. The control logic 771 may
transmit a column address signal to the column decoder 773 or the
page buffer 775, and the column decoder 773 may decode the column
address signal and transmit the same to the NAND cell array 750 via
the bit lines BL. Signals from the NAND cell array 750 may be
transmitted to the sense amplifier 773 via the column decoder 774,
and be amplified in the sense amplifier 773 and transmitted through
the page buffer 775 to the control logic 771.
[0102] FIG. 25 is a schematic view illustrating a memory card 800
according to an exemplary embodiment.
[0103] Referring to FIG. 25, the memory card 800 may include a
controller 810 and a memory unit 820, which are installed in a
housing 830. The controller 810 and the memory unit 820 may
exchange electrical signals. For example, the memory unit 820 and
the controller 810 may exchange data according to a command from
the controller 810. The memory card 800 may store data in the
memory unit 820 or may externally output data from the memory unit
820.
[0104] For example, the memory unit 820 may include at least one of
the nonvolatile memory devices 1-5 respectively described above
with reference to FIGS. 2, 13, 17, 18 and 19. The memory card 800
may be used as a data storage medium of various types of portable
appliances. For example, the memory card 800 may include a
multimedia card (MMC) or a secure digital (SD) card.
[0105] FIG. 26 is a block diagram illustrating an electronic system
900 according to an exemplary embodiment.
[0106] Referring to FIG. 26, the electronic system 900 may include
a processor 910, an input/output unit 930, and a memory unit 920.
Data communication between the processor 910, the input/output unit
930 and the memory unit 920 may be conducted via a bus 940. The
processor 910 may execute programs and control the electronic
system 900. The input/output unit 930 may be used to input data to
or output data from the electronic system 900. The electronic
system 900 may be connected to an external device, for example, a
personal computer or a network, via the input/output unit 930 to
exchange data with the external device. The memory unit 920 may
store codes and data for operating the processor 910. For example,
the memory unit 920 may include at least one of the nonvolatile
memory devices 1-5 respectively described above with reference to
FIGS. 2, 13, 17, 18 and 19.
[0107] The electronic system 900 may constitute various types of
electronic controllers including the memory unit 920. For example,
the electronic system 900 may be used in a mobile phone, an MP3
player, a navigation device, a solid state disk (SSD), or other
household appliances.
[0108] While the inventive concept has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood that various changes in form and details may be made
therein without departing from the spirit and scope of the
following claims.
* * * * *