U.S. patent application number 12/648389 was filed with the patent office on 2011-03-31 for phase change memory device and fabrication method thereof.
This patent application is currently assigned to HYNIX SEMICONDUCTOR INC.. Invention is credited to Su Jin CHAE, Keum Bum LEE, Hye Jin SEO.
Application Number | 20110073826 12/648389 |
Document ID | / |
Family ID | 43779279 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110073826 |
Kind Code |
A1 |
LEE; Keum Bum ; et
al. |
March 31, 2011 |
PHASE CHANGE MEMORY DEVICE AND FABRICATION METHOD THEREOF
Abstract
A phase change memory device is provided that includes a
switching device, a bottom electrode contact in contact with the
switching device and a porous spacer formed on the bottom electrode
contact.
Inventors: |
LEE; Keum Bum; (Gyeonggi-do,
KR) ; CHAE; Su Jin; (Gyeonggi-do, KR) ; SEO;
Hye Jin; (Gyeonggi-do, KR) |
Assignee: |
HYNIX SEMICONDUCTOR INC.
Gyeonggi-do
KR
|
Family ID: |
43779279 |
Appl. No.: |
12/648389 |
Filed: |
December 29, 2009 |
Current U.S.
Class: |
257/3 ;
257/E21.068; 257/E47.001; 438/102 |
Current CPC
Class: |
H01L 45/126 20130101;
H01L 45/16 20130101; H01L 45/144 20130101; H01L 45/06 20130101;
H01L 45/1233 20130101; H01L 27/2409 20130101 |
Class at
Publication: |
257/3 ; 438/102;
257/E47.001; 257/E21.068 |
International
Class: |
H01L 47/00 20060101
H01L047/00; H01L 21/06 20060101 H01L021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2009 |
KR |
10-2009-0093603 |
Claims
1. A phase change memory device, comprising: a switching device; a
bottom electrode contact in contact with the switching device; and
a porous spacer formed on a portion of the bottom electrode
contact.
2. The phase change memory device of claim 1, wherein the porous
spacer is comprised of a germanium compound.
3. The phase change memory device of claim 2, wherein the germanium
compound comprises silicon-germanium.
4. The phase change memory device of claim 2, wherein the germanium
compound comprises silicon-germanium-nitride.
5. A method of manufacturing a phase change memory device,
comprising the steps of: forming a bottom electrode contact hole to
expose a switching device on a semiconductor substrate; forming an
insulating layer on a resultant structure of the semiconductor
substrate including the bottom electrode contact hole by using an
insulating compound having materials of different atomic sizes; and
forming an insulating spacer within the bottom electrode contact
hole by selectively etching the insulating layer.
6. The method of claim 5, wherein the step of forming an insulating
layer comprises repeatedly depositing a plurality of insulating
materials having different atomic sizes at least one or more times
in a pre-arranged order.
7. The method of claim 5, wherein the insulating compound comprises
a germanium compound.
8. The method of claim 7, wherein the germanium compound comprises
silicon-germanium.
9. The method of claim 8, wherein the step of forming an insulating
layer comprises repeatedly depositing a silicon layer and a
germanium layer at least one or more times in a pre-arranged
order.
10. The method of claim 8, wherein the insulating layer is a
Ge-rich insulating layer.
11. The method of claim 8, wherein the insulating layer is a
Si-rich insulating layer.
12. The method of claim 7, wherein the germanium compound comprises
silicon-germanium-nitride.
13. The method of claim 12, wherein the step of forming an
insulating layer comprises repeatedly depositing each of a silicon
layer, a germanium layer and a nitride layer at least one or more
time in a pre-arranged order.
14. The method of claim 13, wherein after forming the silicon
layer, the germanium layer and the nitride layer, further carrying
out purge processes, respectively, wherein a purge time of a purge
process carried out after forming the nitride layer is two to three
times longer than a purge time of a purge process carried out after
forming the silicon layer and the germanium layer.
15. The method of claim 12, wherein the insulating layer comprises
a Ge-rich insulating layer.
16. The method of claim 12, wherein the insulating layer comprises
a Si-rich insulating layer.
17. The method of claim 12, wherein the step of forming an
insulating layer comprises forming a Ge-rich insulating layer by
sequentially depositing a silicon layer, a germanium layer and a
nitride layer at least one or more times.
18. The method of claim 12, wherein the step of forming an
insulating layer comprises forming a Si-rich insulating layer by
sequentially depositing a silicon layer, a germanium layer and a
nitride layer at least one or more times.
19. The method of claim 12, wherein the step of forming an
insulating layer comprises forming a Ge-rich insulating layer by
sequentially depositing a silicon layer, a nitride layer and a
germanium layer at least one or more times.
20. The method of claim 12, wherein the step of forming an
insulating layer comprises forming a Si-rich insulating layer by
sequentially depositing a silicon layer, a nitride layer and a
germanium layer at least one or more times.
21. The method of claim 5, wherein the step of forming an
insulating layer comprises depositing a plurality of insulating
materials having different atomic sizes by using a chemical vapor
deposition method.
22. A method of manufacturing a phase change memory device,
comprising the steps of: forming a switching device on a
semiconductor substrate; forming a bottom electrode contact hole to
an upper portion of the switching device; and forming a porous
spacer on a portion of the bottom electrode contact hole.
23. The method of claim 22, wherein the step of forming a porous
spacer comprises; forming a porous insulating layer on a resultant
structure of the semiconductor substrate including the bottom
electrode contact hole; and space-etching the porous insulating
layer.
24. The method of claim 23, wherein the porous insulating layer is
formed by using a germanium compound.
25. The method of claim 24, wherein the germanium compound
comprises silicon-germanium.
26. The method of claim 25, wherein the step of forming a porous
insulating layer comprises sequentially depositing a silicon layer
and a germanium layer at least one or more times.
27. The method of claim 26, wherein the porous insulating layer
comprises a Ge-rich insulating layer.
28. The method of claim 26, wherein the insulating porous layer
comprises a Si-rich insulating layer.
29. The method of claim 24, wherein the germanium compound
comprises silicon-germanium-nitride.
30. The method of claim 29, wherein the porous insulating layer
comprises a Ge-rich insulating layer.
31. The method of claim 29, wherein the insulating layer comprises
a Si-rich insulating layer.
32. The method of claim 29, wherein after forming the silicon
layer, the germanium layer and the nitride layer, further
comprising carrying out purge processes respectively, wherein a
purge time of a purge process carried out after forming the nitride
layer is two to three times longer than a purge time of a purge
process carried out after the silicon layer and the germanium
layer.
33. The method of claim 23, wherein the step of forming a porous
insulating layer comprises depositing a plurality of insulating
materials having different atomic sizes by a chemical vapor
deposition method.
Description
CROSS-REFERENCES TO RELATED APPLICATION
[0001] The present application claims priority under 35 U.S.C.
119(a) to Korean application number 10-2009-0093603, filed on Sep.
30, 2009, in the Korean Patent Office, which is incorporated by
reference in its entirety as if set forth in full.
BACKGROUND
[0002] 1. Technical Field
[0003] The inventive concept relates to a semiconductor memory
device and, more particularly, to a phase change memory device and
a method of manufacturing the same.
[0004] 2. Related Art
[0005] A phase change material has a different status of an
amorphous state or a crystalline state depending on a temperature.
The phase change material has a lower resistance in a crystalline
state than in an amorphous state and has a regular atomic
arrangement. The phase change material may be a chalcogenide
(GST)-based material which is a compound comprised of germanium
(Ge), antimony (Sb) and tellurium (Te).
[0006] A phase change random access memory (PCRAM) is a memory
device which stores and reads information by using a status change
property of the change material and has a fast operation speed and
a high integration. The phase change material of the PCRAM is
phase-changed by the Joule's heat which is applied through a bottom
electrode contact (BEC) serving as a heater.
[0007] In particular, in a reset operation of the PCRAM which
phase-changes the phase change material in an amorphous state, an
enormous amount of current should be applied for a short time and
an amount of reset current affects a life span, a sensing margin
and shrinkage of the device.
[0008] To heighten the height of the BEC or to reduce the contact
area between the BEC and the phase change material, it is suggested
to reduce the reset current. In particular, the method for forming
a spacer on an inner side wall of the BEC to reduce the contact
area between the BEC and the phase change material layer is an
effective method to minimize the volume that the phase change
material is phase-changed to the crystalline state or an amorphous
state, thereby improving the operation speed and reducing the reset
current.
[0009] FIGS. 1a and 1b are sectional views illustrating a method of
manufacturing a conventional phase change memory device. First, as
shown in FIG. 1a, a semiconductor substrate 101 having a diode 105
as a switching device formed in a predetermined portion of a first
interlayer insulating layer 103, is prepared. A metal silicide
layer 107 is formed on the diode 105. Next, a second interlayer
insulating layer 109 is formed on the resultant structure of the
semiconductor substrate 101 and the BEC hole 111 is formed in the
second interlayer insulating layer 109 to expose the metal silicide
layer 107.
[0010] Next, as shown in FIG. 1b, an insulating layer is formed on
the resultant structure of the semiconductor substrate 101
including the BEC hole 111 and then etched back to form an
insulating spacer 113 on a side wall of the BEC hole 111.
[0011] The insulating spacer 113 is typically formed of a nitride
material. In a spacer etching process, the insulating spacer 113
formed of a nitride material is etched faster in an upper potion of
the BEC hole 111 than in the bottom portion of the BEC hole 111.
Therefore, the diameter of the upper portion of the BEC hole 111
may be different from that of the bottom portion of the BEC hole
111 due to the insulating spacer 113. Although the insulating
spacer 113 is formed to reduce the contact area between the BEC and
the phase change material layer, since the upper portion 115 of the
insulating spacer 113 is over etched due to the etch rate
difference, the diameter in the upper portion of the BEC hole can
not be reduced and therefore it can not obtain the desired
objective to reduce the reset current.
[0012] Meanwhile, the BEC serving as a heater should fast radiate
the heat applied in the reset operation.
[0013] FIG. 2 is a diagram explaining the heat radiation efficiency
of the phase change memory device. Referring to FIG. 2, the phase
change material layer 205 is phase-changed by the heating of the
BEC 203 and then the applied heat is radiated through the phase
change material layer 205 (A) or through the bottom (B) or the side
(C) of the BEC 203. The reference numeral 201 designates an
interlayer insulating layer.
[0014] The heat radiating through the phase change material layer
205 is 3 to 18% of the heat applied to the BEC 205 and the heat
radiating through the bottom of the BEC 203 is 60 to 72% of the
applied heat. The heat radiating through the side wall of the BEC
203 is 21 to 25% of the applied heat. Accordingly, if the
insulating spacer is formed in the BEC hole, approximately
one-fourth of the heat applied to the BEC 203 should be radiated to
the insulating spacer. However, the nitride material of the
insulating spacer is inefficient to radiate the heat because of the
nature of the material. Furthermore, as the thickness of the
insulating spacer is increased to reduce the diameter of the BEC,
the speed of the heat radiation becomes further delayed such that
the operation speed of the device is lowered.
SUMMARY
[0015] An embodiment of the inventive concept provides a phase
change memory device having a bottom electrode contact of excellent
heat radiation efficiency and a method of manufacturing the
same.
[0016] Another embodiment of the inventive concept provides a phase
change memory device being capable of refrigerating a phase change
material layer with high speed and a method of manufacturing the
same.
[0017] According to one aspect of an exemplary embodiment, a phase
change memory device includes a switching device, a bottom
electrode contact in contact with the switching device and a porous
spacer formed on an outer wall of the bottom electrode contact.
[0018] According to another aspect of another exemplary embodiment,
a method of manufacturing a phase change memory device includes
forming a bottom electrode contact hole to expose a switching
device on a semiconductor substrate which the switching device is
formed in, forming an insulating layer on a resultant structure of
the semiconductor substrate 201 including the bottom electrode
contact hole by using an insulating compound having materials with
different atomic sizes, and forming an insulating spacer within the
bottom electrode contact hole by selectively etching the insulating
layer.
[0019] According to still another aspect of another exemplary
embodiment, a method of manufacturing a phase change memory device
includes forming a switching device on the semiconductor substrate,
forming a bottom electrode contact hole to expose an upper surface
of the switching device, and forming a porous spacer on an inner
wall of the bottom electrode contact hole.
[0020] These and other features, aspects, and embodiments are
described below in the section entitled "DESCRIPTION OF EXEMPLARY
EMBODIMENT".
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above and other aspects, features and other advantages
of the subject matter of the present disclosure will be more
clearly understood from the following detailed description taken in
conjunction with the accompanying drawings, in which:
[0022] FIGS. 1a and 1b are sectional views illustrating a method of
manufacturing a conventional phase change memory device;
[0023] FIG. 2 is a diagram explaining an efficiency of a heat
radiation in the conventional phase change memory device; and
[0024] FIGS. 3 through 7 are sectional views illustrating a method
of manufacturing a phase change memory device according to an
exemplary embodiment.
DETAILED DESCRIPTION
[0025] Exemplary embodiments are described herein with reference to
cross-sectional illustrations that are schematic illustrations of
exemplary embodiments (and intermediate structures). 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, exemplary embodiments should not be construed as
limited to the particular shapes of regions illustrated herein but
may be to include deviations in shapes that result, for example,
from manufacturing. In the drawings, lengths and sizes of layers
and regions may be exaggerated for clarity. Like reference numerals
in the drawings denote like elements.
[0026] FIGS. 3 through 7 are sectional views illustrating a method
of manufacturing a phase change memory device according to an
exemplary embodiment. Referring to FIG. 3, a semiconductor
substrate 301 which a switching device 305 is formed on, is
prepared. The switching device 305, for example, may be formed by
forming a first interlayer insulating layer 303 on the
semiconductor substrate 301 which a junction region (not shown) is
formed in, patterning the first interlayer insulating layer 303 to
expose the junction region, growing a selective epitaxial growth
layer, and carrying out an ion implanting process to the selective
epitaxial growth layer.
[0027] In addition, a metal silicide layer 307 is formed on the
switching device 305. The metal silicide layer 307 may be formed by
a metal layer, for example a cobalt (Co)/titanium (Ti)/Titanium
nitride (TiN) (Co/Ti/TiN) layer, on a resultant structure of the
semiconductor substrate 301 including the switching device 305,
carrying out a first annealing process, removing an inactive
portion of the metal layer, and carrying out a second annealing
process, for example.
[0028] Although a diode is used as the switching device 305 in FIG.
3, it is not limited thereto and any semiconductor device working
as the switching device may be used. Furthermore, the metal
silicide layer 307 may be selectively formed as necessary.
[0029] Referring to FIG. 4, following forming the switching device
305 and the metal silicide layer 307, a second interlayer
insulating layer 309 is formed on a resultant structure of the
semiconductor substrate 301. Moreover, a bottom electrode contact
hole 311 having a desired diameter is formed to expose the metal
silicide layer 307 in the second interlayer insulating layer
309.
[0030] The bottom electrode contact hole 311 may be formed to have
a diameter larger than the desired diameter by 30 to 40 nm under
the consideration of a thickness of a spacer to be formed in the
subsequent process, for example. Accordingly, the process margin
for the bottom electrode contact hole 311 can be sufficiently
ensured and the etch efficiency can be also increased.
[0031] Next, referring to FIG. 5, a porous insulating layer 313 is
formed on a resultant structure of the semiconductor substrate 301
including the bottom electrode contact hole 311. The porous
insulating layer 313 may be formed at the same thickness as an
increment of a diameter (30 to 40 nm) by using a porous insulating
material, for example. The porous insulating material may comprise
an insulating compound having materials with different atomic
sizes, for example. The porous insulating material may comprise a
compound containing a germanium having a large atomic size,
preferably silicon germanium (SiGe) or silicon germanium nitride
(SiGeN), for example.
[0032] The porous insulating layer 313 may be formed, for example,
by an atomic layer deposition (ALD) method or a chemical vapor
deposition (CVD) method. During the ALD method, porous insulating
layer 313 is formed by repeatedly depositing each material having a
different atomic size at least one or more times in a pre-arranged
order. For example, when the porous insulating material is SiGe,
each material having a different atomic size is repeatedly
deposited at least one or more times in a pre-arranged order to
form the porous insulating layer 313. Or, the Ge-rich porous
insulating layer 313 is formed by increasing the deposition number
of the germanium layer having a larger atomic size than that of the
silicon layer, such that the efficiency of the heat radiation can
be further increased. Meanwhile, the Si-rich porous insulating
layer 313 is formed by increasing the deposition number of the
silicon having a higher thermal conductivity than that of the
germanium layer, such that the efficiency of the heat radiation can
be also increased.
[0033] When the porous insulating material is SiGeN, each material
having a different atomic size may be repeatedly deposited at least
one or more times in a pre-arranged order to form the porous
insulating layer 313. In addition, the Ge-rich porous insulating
layer 313 or the Si-rich porous insulating layer 313 may be also
formed. Furthermore, if the purge time of a purge process carried
out following the deposition of the nitride layer is controlled,
for example, to be two to three times longer than the purge time of
a purge process carried out following the deposition of the Si
layer or the Ge layer, the porous insulating layer 313 having
further excellent efficiency of the heat radiation may be
formed.
[0034] When the porous insulating layer 313 is formed by using
SiGeN through an ALD method, the Si layer/the germanium layer (Or
the silicon germanium layer)/the nitride layer may be sequentially
deposited or the silicon layer/the nitride layer/the germanium
layer may be sequentially deposited, for example.
[0035] In the exemplary embodiment, when the porous insulating
layer 313 is to be formed by an ALD method, source gas may be
injected by a shower head method or an injection method, for
example. The deposition temperature may be at 300 to 500.degree. C.
and GeH.sub.4 may be used as a Ge source gas and any one of DCS,
SiH.sub.4, or S.sub.2H.sub.6 may be used as a Si source gas, for
example.
[0036] Referring to FIG. 6, a porous spacer 313A may be formed on
an inner wall of the bottom electrode contact hole through a spacer
etching process. The porous insulating material has the etching
rate in an upper portion of the bottom electrode contact hole
almost equal to that in a lower portion of the bottom electrode
contact hole such that it can control the diameter of the upper
portion of the bottom electrode contact hole to be almost equal to
that of the lower portion of the bottom electrode contact hole.
Accordingly, a contact area between a bottom electrode contact and
a phase change material layer can be effectively reduced, thereby
minimizing a reset current.
[0037] Next, referring to FIG. 7, the bottom electrode contact 315
is formed. The ring type bottom electrode contact 315 is
illustrated in FIG. 7 in which an insulating material 317 is filled
within the bottom electrode contact 315. The shape of the bottom
electrode contact 315 is not limited thereto and the bottom
electrode contact may be embodied in a various shape such as a
pillar type or a cylinder type, for example.
[0038] Although not shown in drawings, after the bottom electrode
contact is formed for example, the phase change material layer may
be formed to be contacted with the bottom electrode contact and
then an upper electrode may be formed.
[0039] The heat applied to the bottom electrode contact 315, which
is a heater, by a reset operation such that the phase change
material layer is phase-changed into an amorphous state, is
radiated to the phase change material layer or to the side and
bottom of the bottom electrode contact 315. In particular, this
inventive concept forms the porous spacer 313A on the outer wall of
the bottom electrode contact such that the heat radiation speed can
be improved and therefore the operation speed of the device can be
improved.
[0040] Accordingly, the heat applied in the reset operation of the
phase change memory device can be radiated with a high speed such
that the reset current can be reduced and the total power
consumption can be lowered. Substantially, when the porous spacer
is formed, the aspect ratio of the bottom electrode contact, for
example, can be 1:3 in a design rule of 40 nm or below and the
amount of the reset current can be lowered below 0.2 to 0.25 mA,
for example. The bottom electrode contact of a various shape, such
as a pillar type or a ring type for example, can be formed due to
excellent step coverage of the porous insulating material.
[0041] While certain embodiments have been described above, it will
be understood that the embodiments described are by way of example
only. Accordingly, the devices and methods described herein should
not be limited based on the described embodiments. Rather, the
systems and methods described herein should only be limited in
light of the claims that follow when taken in conjunction with the
above description and accompanying drawings.
* * * * *