U.S. patent application number 10/139252 was filed with the patent office on 2002-11-14 for thin film including multi components and method of forming the same.
Invention is credited to Cho, Young-Jin, Kim, Dae-Sig, Lee, Jung-Hyun, Min, Yo-Sep.
Application Number | 20020168553 10/139252 |
Document ID | / |
Family ID | 26639056 |
Filed Date | 2002-11-14 |
United States Patent
Application |
20020168553 |
Kind Code |
A1 |
Lee, Jung-Hyun ; et
al. |
November 14, 2002 |
Thin film including multi components and method of forming the
same
Abstract
A thin film including multi components and a method of forming
the thin film are provided, wherein a method according to an
embodiment of the present invention, a substrate is loaded into a
reaction chamber. A unit material layer is formed on the substrate.
The unit material layer is a mosaic atomic layer composed of two
kinds of precursors containing components constituting the thin
film. The inside of the reaction chamber is purged, and the MAL is
chemically changed. The method of forming the thin film of the
present invention requires fewer steps than a conventional method
while retaining the advantages of the conventional method, thereby
allowing a superior thin film yield in the present invention than
previously obtainable.
Inventors: |
Lee, Jung-Hyun;
(Yongin-city, KR) ; Kim, Dae-Sig; (Seognam-city,
KR) ; Min, Yo-Sep; (Seoul, KR) ; Cho,
Young-Jin; (Incheon, KR) |
Correspondence
Address: |
LEE & STERBA, P.C.
Suite 2000
1101 Wilson Boulevard
Arlington
VA
22209
US
|
Family ID: |
26639056 |
Appl. No.: |
10/139252 |
Filed: |
May 7, 2002 |
Current U.S.
Class: |
428/697 ;
428/698; 428/699; 428/701; 428/702 |
Current CPC
Class: |
C23C 16/308 20130101;
C23C 16/45542 20130101; C23C 16/409 20130101; C23C 16/34 20130101;
C23C 16/40 20130101; C23C 16/45531 20130101 |
Class at
Publication: |
428/697 ;
428/701; 428/702; 428/699; 428/698 |
International
Class: |
B32B 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2001 |
KR |
2001-24684 |
Apr 29, 2002 |
KR |
2002-23297 |
Claims
What is claimed is:
1. A method of forming a thin film including multi components, the
method comprising: loading a substrate into a reaction chamber,
forming a unit material layer, which is a mosaic atomic layer (MAL)
composed of two kinds of precursors containing components
constituting a thin film, on the substrate; purging the inside of
the reaction chamber; and chemically changing the MAL.
2. The method as claimed in claim 1, wherein the MAL is formed by
supplying the two kinds of precursors at the same time.
3. The method as claimed in claim 1, wherein the MAL is formed by
sequentially supplying the two kinds of precursors by a
time-sharing method.
4. The method as claimed in claim 3, further comprising: supplying
first precursors selected from the two kinds of precursors into the
reaction chamber; firstly purging the reaction chamber; and
supplying second precursors selected from the two kinds of
precursors into the reaction chamber.
5. The method as claimed in claim 3, wherein each of the first and
second precursors is supplied in an amount less than that
sufficient for forming an atomic layer on the entire surface of the
substrate.
6. The method as claimed in claim 4, further comprising: secondly
purging the reaction chamber; and supplying third precursors
selected from the two kinds of precursors into the reaction
chamber.
7. The method as claimed in claim 1, wherein the MAL is a double
MAL composed of first and second MALs.
8. The method as claimed in claim 7, wherein the first MAL is
chemically changed before the second MAL is formed on the first
MAL.
9. The method as claimed in claim 7, wherein the first MAL is
formed of first and second precursors selected from the two kinds
of precursors.
10. The method as claimed in claim 8, wherein the first MAL is
formed of first and second precursors selected from the two kinds
of precursors.
11. The method as claimed in claim 9, wherein the second MAL is
formed of first and third precursors selected from the two kinds of
precursors.
12. The method as claimed in claim 10, wherein the second MAL is
formed of first and third precursors selected from the two kinds of
precursors.
13. The method as claimed in claim 9, wherein the second MAL is
formed of first and second precursors, of different
compositions.
14. The method as claimed in claim 10, wherein the second MAL is
formed of first and second precursors, of different
compositions.
15. The method as claimed in claim 9, wherein the first MAL is
formed by supplying the first and second precursors at the same
time.
16. The method as claimed in claim 10, wherein the first MAL is
formed by supplying the first and second precursors at the same
time.
17. The method as claimed in claim 9, wherein the first MAL is
formed by sequentially supplying the first and second precursors by
a time-sharing method.
18. The method as claimed in claim 10, wherein the first MAL is
formed by sequentially supplying the first and second precursors by
a time-sharing method.
19. The method as claimed in claim 11, wherein the second MAL is
formed by supplying the first and third precursors at the same
time.
20. The method as claimed in claim 12, wherein the second MAL is
formed by supplying the first and third precursors at the same
time.
21. The method as claimed in claim 11, wherein the second MALs are
formed by sequentially supplying the first and third precursors by
a time-sharing method.
22. The method as claimed in claim 12, wherein the second MALs are
formed by sequentially supplying the first and third precursors by
a time-sharing method.
23. The method as claimed in claim 1, wherein in chemically
changing the MAL, the MAL is oxidized, nitrified, or boronized.
24. The method as claimed in claim 23, wherein the MAL is oxidized
using plasma or ultraviolet-ozone using either H.sub.2O, O.sub.2,
O.sub.3, or H.sub.2O.sub.2 as a source of oxygen.
25. The method as claimed in claim 24, wherein the source of oxygen
is purged using an inert gas, wherein DC-bias is applied to the
substrate to make the inert gas into plasma so as to form inert
gaseous plasma which is used to remove by-products adsorbed on the
surface of the MAL.
26. The method as claimed in claim 24, wherein the plasma is formed
using radio frequency (RF) or microwave energy.
27. The method as claimed in claim 8, wherein the first MAL is
chemically changed by either an oxidation method, a nitrification
method, or a boronization method.
28. The method as claimed in claim 4, wherein the second precursors
are additionally supplied after the second precursors are
supplied.
29. The method as claimed in claim 6, wherein the third precursors
are additionally supplied after the third precursors are
supplied.
30. The method as claimed in claim 1, wherein the thin film is
either an oxide layer, a nitride layer, or a boride layer.
31. The method as claimed in claim 1, wherein the thin film is
either an STO layer, a PZT layer, a BST layer , a YBCO layer , an
SBTO layer, an HfSiON layer, a ZrSiO layer, a ZrHfO layer, a LaCoO
layer, or a TiSiN layer.
32. A method as claimed in forming a thin film including multi
components, the method comprising: loading a substrate into a
reaction chamber and sequentially forming a mosaic atomic layer
(MAL) composed of two kinds of precursors containing components
constituting the thin film and a non-mosaic atomic layer on the MAL
to form a unit material layer constituting the thin film on the
substrate; purging the inside of the reaction chamber; and
chemically changing the MAL.
33. The method as claimed in claim 32, wherein the MAL is formed by
supplying the two kinds of precursors at the same time.
34. The method as claimed in claim 32, wherein the MAL is formed by
supplying the two kinds of precursors by a time-sharing method.
35. The method as claimed in claim 34, further comprising:
supplying first precursors selected from the two kinds of
precursors into the reaction chamber; firstly purging the reaction
chamber; and supplying second precursors selected from the two
kinds of precursors into the reaction chamber.
36. The method as claimed in claim 35, further comprising: secondly
purging the reaction chamber; and supplying third precursors
selected from the two kinds of precursors into the reaction
chamber.
37. The method as claimed in claim 35, wherein the second
precursors are additionally supplied after the second precursors
are supplied.
38. The method as claimed in claim 36, wherein the third precursors
are additionally supplied after the third precursors are
supplied.
39. The method as claimed in claim 32, wherein the thin film is
either an oxide layer, a nitride layer, or a boride layer.
40. The method as claimed in claim 32, wherein the thin film is one
selected from the group consisting of an STO layer, a PZT layer, a
BST layer, a YBCO layer, an SBTO layer, an HfSiON layer, a ZrSiO
layer, a ZrHfO layer, a LaCoO layer, and a TiSiN layer.
41. The method as claimed in claim 32, wherein in chemically
changing the MAL, the MAL is oxidized, nitrified, or boronized.
42. The method as claimed in claim 41, wherein the MAL is oxidized
using plasma or ultraviolet-ozone using either O.sub.2, O.sub.3,
H.sub.2O, or H.sub.2O.sub.2 as a source of oxygen.
43. The method as claimed in claim 42, wherein the plasma is formed
using radio frequency (RF) or microwave energy.
44. The method as claimed in claim 42, wherein the source of oxygen
is purged using an inert gas, wherein the inert gas is made into
plasma to form inter gaseous plasma which is used to remove
by-products adsorbed on the surface of the MAL.
45. The method as claimed in claim 32, wherein when the MAL is
formed by supplying the two kinds of precursors by a time-sharing
method, each of the two kinds of precursors is supplied in an
amount less than that sufficient for covering the entire surface of
the substrate.
46. A thin film including multi components, containing at least two
components, wherein the thin film is composed of a plurality of
unit material layers and each of the unit material layers is an MAL
composed of different precursors related to the components.
47. The thin film including multi components as claimed in claim
46, wherein the MALs are double MALs which are composed of first
and second MALs.
48. The thin film including multi components as claimed in claim
47, wherein the first and second MALs are formed of the same
precursors, which have a different composition ratio for each of
the first and second MALs.
49. The thin film including multi components as claimed in claim
47, wherein the first MAL is composed of first and second
precursors selected from the different precursors.
50. The thin film including multi components as claimed in claim
49, wherein the second MAL is composed of the first precursors and
third precursors selected from the different precursors.
51. The thin film including multi components as claimed in claim
46, wherein the thin film is either an oxide layer, a nitride
layer, or a boride layer.
52. The thin film including multi components as claimed in claim
46, wherein the thin film is one selected from the group consisting
of an STO layer, a PZT layer, a BST layer, a YBCO layer, an SBTO
layer, an HfSiON layer, a ZrSiO layer, a ZrHfO layer, a LaCoO
layer, and a TiSiN layer.
53. A thin film including multi components, containing at least two
components, wherein the thin film is composed of a plurality of
unit material layers and each of the unit material layers is
composed of an MAL, wherein each MAL is composed of two precursors
selected from different precursors related to the components, and a
non-mosaic atomic layer composed of any precursor selected from the
different precursors.
54. The thin film including multi components as claimed in claim
53, wherein the non-mosaic atomic layer is formed on the MAL.
55. The thin film including multi components as claimed in claim
53, wherein the MAL is formed on the non-mosaic atomic layer.
56. The thin film including multi components as claimed in claim
53, wherein the MAL is a double layer.
57. The thin film including multi components as claimed in claim
54, wherein the MAL is a double layer.
58. The thin film including multi components as claimed in claim
55, wherein the MAL is a double layer.
59. The thin film including multi components of claim 56, wherein
the MAL is composed of a first MAL composed of all of the different
precursors and a second MAL composed of two precursors selected
from the different precursors.
60. The thin film including multi components of claim 57, wherein
the MAL is composed of a first MAL composed of all of the different
precursors and a second MAL composed of two precursors selected
from the different precursors.
61. The thin film including multi components of claim 58, wherein
the MAL is composed of a first MAL composed of all of the different
precursors and a second MAL composed of two precursors selected
from the different precursors.
62. The thin film including multi components of claim 56, wherein
the MAL is composed of a first MAL composed of all of the different
precursors.
63. The thin film including multi components of claim 57, wherein
the MAL is composed of a first MAL composed of all of the different
precursors.
64. The thin film including multi components of claim 58, wherein
the MAL is composed of a first MAL composed of all of the different
precursors.
65. The thin film including multi components of claim 56, wherein
the double layer is composed of the same precursors, which have a
different composition ratio for each of layers in the double
layer.
66. The thin film including multi components of claim 57, wherein
the double layer is composed of the same precursors, which have a
different composition ratio for each of layers in the double
layer.
67. The thin film including multi components of claim 58, wherein
the double layer is composed of the same precursors, which have a
different composition ratio for each of layers in the double
layer.
68. The thin film including multi components of claim 56, wherein
the double layer is composed of a first MAL, composed of first and
second precursors selected from the different precursors, and a
second MAL formed on the first MAL, composed of first and third
precursors selected from the different precursors.
69. The thin film including multi components of claim 57, wherein
the double layer is composed of a first MAL, composed of first and
second precursors selected from the different precursors, and a
second MAL formed on the first MAL, composed of first and third
precursors selected from the different precursors.
70. The thin film including multi components of claim 58, wherein
the double layer is composed of a first MAL, composed of first and
second precursors selected from the different precursors, and a
second MAL formed on the first MAL, composed of first and third
precursors selected from the different precursors.
71. The thin film including multi components of claim 53, wherein
the thin film is either an oxide layer, a nitride layer, or a
boride layer.
72. The thin film including multi components of claim 53, wherein
the thin film is one selected from the group consisting of an STO
layer, a PZT layer, a BST layer, a YBCO layer, an SBTO layer, an
HfSiON layer, a ZrSiO layer, a ZrHfO layer, a LaCoO layer, and a
TiSiN layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a thin film and a method of
forming the same. More particularly, the present invention relates
to a thin film including multi components composed of unit material
layers which are mosaic atomic layers (MALs) composed of components
constituting the thin film, and a method of forming the same.
[0003] 2. Description of the Related Art
[0004] Atomic layer deposition (ALD) is a thin film deposition
method which is very different from more conventional physical
deposition methods such as electron beam deposition, thermal
deposition, or sputter deposition. ALD is similar to chemical vapor
deposition (CVD) in that chemical reactions of reaction gases are
used. However, in general CVD, reaction gases are supplied at the
same time and react chemically on the surface of a thin film or in
the air. In ALD, different kinds of reaction gases are supplied
separately by a time-sharing method, and react with the surface of
a thin film. In ALD, if a different kind of reaction gas is
supplied when an organic metal compound containing a metallic
element (hereinafter referred to as "precursors") is adsorbed on
the surface of a substrate, the reaction gas reacts with the
precursors on the surface of the substrate. As a result, a thin
film is formed. Thus, precursors for ALD do not decompose by
themselves at a reaction temperature, and precursors adsorbed on
the surface of the substrate must be very rapidly reacted with a
supplied reaction gas on the surface of the substrate. ALD can
obtain the best uniformity of thickness and step coverage of the
thin film from the surface reaction.
[0005] In ALD, the same kinds of precursors are adsorbed on all
sites of a wafer surface on which chemisorption is possible. Even
if excessive precursors are supplied, physisorption of the
remaining precursors is performed on the chemisorbed precursors.
Here, physisorption has less cohesion force than chemisorption. The
physisorbed precursors are then removed using a purge gas. Next,
different kinds of precursors are supplied and chemisorbed on the
chemisorbed precursors. This process is repeated to grow a thin
film on the wafer surface at a predetermined speed.
[0006] For example, in ALD using precursors A and a reaction gas B,
a cycle of supplying precursors A, e.g., N.sub.2 (or Ar), purging,
and supplying a reaction gas B, i.e., N.sub.2 (or Ar) is repeated
to grow a thin film. The growth speed of the thin film represents
the thickness of the thin film deposited in one cycle. As a result,
the probability that molecules of precursors are adsorbed on any
exposed surface is similar, regardless of the roughness of the
exposed surface. Thus, if the supply of precursors is sufficient, a
thin film having a uniform thickness is deposited at a constant
speed regardless of the aspect ratio of the surface structure of
the substrate. Also, depositing one layer at a time allows precise
control of the thickness and composition of the thin film.
[0007] However, ALD also has the following problems. First, if a
thin film containing three components or more is formed, the
deposition rate in ALD is slower than the deposition rate in
existing CVD. For example, if an SrTiO.sub.3 layer is formed by
ALD, one cycle is composed of eight steps as shown in FIG. 1.
Precursors containing Sr are supplied in step 10. A purge gas is
supplied to purge a reaction chamber for the first time in step 20.
In step 30, a reaction gas containing oxygen is supplied to oxidize
the Sr atomic layer formed in step 10. A purge gas is supplied to
purge the reaction chamber for the second time in step 40.
Precursors containing Ti are supplied in step 50. A purge gas is
supplied to purge the reaction chamber for the third time in step
60. In step 70, a reaction gas containing oxygen is supplied to
oxidize the Ti atomic layer which is formed in step 50. A purge gas
is supplied to purge the reaction chamber for the fourth time in
step 80. Thus, the deposition rate in ALD is much slower than the
deposition rate in the existing CVD, in which components contained
in precursors constituting a thin film are all supplied at the same
time.
[0008] Second, it is difficult to obtain satisfactory crystal
phases of unit material layers constituting a thin film, and thus a
subsequent thermal treatment is required. In detail, in FIG. 2, the
horizontal axis represents Kelvin temperature (K) and the vertical
axis represents activity. Reference numerals G1 through G11
represent activities of TiO.sub.2, BaTiO.sub.2, SrTiO.sub.3,
Sr.sub.4Ti.sub.3O.sub.14, TiO.sub.2S, SrCO.sub.3, BaCO.sub.3,
H.sub.2, CO.sub.2, H.sub.2O, and Sr.sub.2TiO.sub.4,
respectively.
[0009] Referring to FIG. 2, each phase of SrO and TiO.sub.2 exists
stably up to more than 600K if SrO and TiO.sub.2 are alternately
stacked by existing ALD to deposit an SrTiO.sub.3 layer. As a
result, a desired SrTiO.sub.3 layer can be formed. In other words,
the SrTiO.sub.3 layer is only a combined state of SrO and
TiO.sub.2. Thus, an additional thermal treatment is required to
change SrO and TiO.sub.2 to a desired crystalline SrTiO.sub.3. This
result is commonly applied to above a ternary thin film. Therefore,
the thermal treatment is required to grow an oxide layer of a
separate metallic element as a compound layer when the oxide layer
is stabilized.
[0010] As described above, if a thin film containing three
components or more is formed by ALD, an additional thermal
treatment is required to form a thin film having a desired crystal
structure. Thus, the yield of the thin film process is considerably
reduced.
SUMMARY OF THE INVENTION
[0011] In an effort to solve the above-described problems, it is a
first feature of an embodiment of the present invention to provide
a method of forming a thin film including multi components which
does not require a subsequent thermal treatment for
crystallization, and which has increased yield by forming the thin
film at a rapid deposition rate compared to ALD and a crystal
phase.
[0012] It is a second feature of an embodiment of the present
invention to provide a thin film formed by the above-described
method.
[0013] Accordingly, to provide the first feature according to one
embodiment of the present invention, there is provided a method of
forming a thin film including multi components. In the method, a
substrate is loaded into a reaction chamber. A unit material layer,
which is a mosaic atomic layer (MAL) composed of two kinds of
precursors containing components constituting a thin film, is
formed on the substrate. The inside of the reaction chamber is
purged, and the MAL is chemically changed.
[0014] Here, the MAL may be formed by supplying the two kinds of
precursors at the same time or by a time-sharing method,
preferably, the two kinds of precursors are supplied by a time
sharing method after at least one kind of precursor is adsorbed on
the surface of the substrate by an amount less than that sufficient
for forming an atomic layer on the entire surface of the substrate,
i.e., less than when being saturated.
[0015] If the precursors are supplied by a time-sharing method as
described above, first precursors selected from the two kinds of
precursors are supplied into the reaction chamber and then the
reaction chamber is firstly purged. Then, second precursors
selected from the two kinds of precursors are supplied into the
reaction chamber. After initially supplying the second precursors,
additional second precursors may be supplied.
[0016] Preferably, the reaction chamber is secondly purged, and
third precursors selected from the two kinds of precursors are
supplied into the reaction chamber. After initially supplying the
third precursors, additional third precursors may be supplied. The
MAL may be a double MAL composed of first and second MALs.
Preferably, the first MAL is chemically changed before supplying
the second MAL on the first MAL.
[0017] The first MAL is preferably formed of first and second
precursors selected from the two kinds of precursors, and the
second MAL is preferably formed of first and third precursors
selected from the two kinds of precursors.
[0018] Alternatively, the second MAL may be formed of first and
second precursors of different compositions.
[0019] The first MAL may be formed by supplying the first and
second precursors at the same time or by sequentially supplying the
first and second precursors by a time-sharing method.
[0020] The second MAL may be formed by supplying the first and
third precursors at the same time or by sequentially supplying the
first and third precursors by a time-sharing method.
[0021] To provide the first feature according to another embodiment
of the present invention, there is provided a method of forming a
thin film including multi components. The thin film is formed
through a first step of loading a substrate into a reaction chamber
and sequentially forming a mosaic atomic layer (MAL) composed of
two kinds of precursors containing components constituting the thin
film and a non-mosaic atomic layer on the MAL to form a unit
material layer constituting the thin film on the substrate, a
second step of purging the inside of the reaction chamber, and a
third step of chemically changing the MAL. Here, the first, second,
and third steps constitute one cycle.
[0022] In the third step, the resultant material formed in the
first step is preferably oxidized by a supplied oxygen source. The
following step is performed to remove by-products generated after
the oxidation. In other words, in this embodiment, an inert gas is
made into plasma by supplying the inert gas into the chamber and
applying a DC bias to the substrate. As a result, inert gaseous
plasma is generated in the chamber, which is used to remove
by-products from the surface of the MAL.
[0023] Here, the MAL may be formed by supplying the two kinds of
precursors at the same time or by a time-sharing method. If the
precursors are supplied by a time-sharing method, first precursors
selected from the two kinds of precursors are supplied into the
reaction chamber and then the reaction chamber is firstly purged.
Then, second precursors selected from the two kinds of precursors
are supplied into the reaction chamber. After initially supplying
the second precursors, additional second precursors may be
supplied.
[0024] Preferably, the reaction chamber is secondly purged, and
third precursors selected from the two kinds of precursors are
supplied into the reaction chamber. After initially supplying the
third precursors, additional third precursors may be supplied.
[0025] If the MAL is formed by the time-sharing method, each of the
two kinds of precursors is preferably supplied in an amount less
than that sufficient for covering the entire surface of the
substrate.
[0026] In both embodiments, the MAL may be chemically changed by
being oxidized, nitrified or boronized. The MAL may be oxidized by
using plasma or ultraviolet-ozone using H.sub.2O, O.sub.2, O.sub.3
or H.sub.2O.sub.2 as a source of oxygen. The plasma may be formed
using radio frequency or microwave energy.
[0027] In the first embodiment, the source of oxygen may be purged
using an inert gas, wherein DC-bias is applied to the substrate to
make the inert gas into plasma so as to form inert gaseous plasma
which is used to remove by-products adsorbed on the surface of the
MAL.
[0028] In both embodiments, the thin film may be an oxide layer, a
nitride layer, or a boride layer. Additionally, the thin film may
be an STO layer, a PZT layer, a BST layer, a YBCO layer, an SBTO
layer, an HfSiON layer, a ZrSiO layer, a ZrHfO layer, a LaCoO
layer, or a TiSIN layer.
[0029] To provide the second feature of an embodiment of the
present invention, there is provided a thin film including multi
components, containing at least two components. Here, the thin film
is composed of a plurality of unit material layers and each of the
unit material layers is an MAL composed of different precursors
related to the components. The MALs are preferably double MALs
which are composed of first and second MALs. The first and second
MALs may be formed of the same precursors, which have a different
composition ratio for each of the first and second MALs, or the
first MAL may be composed of first and second precursors selected
from the different precursors, or the second MAL may be composed of
the first precursors and third precursors selected from the
different precursors.
[0030] To provide the second feature according to another
embodiment of the present invention, there is provided a thin film
including multi components, containing at least two components.
Here, the thin film is composed of a plurality of unit material
layers and each of the unit material layers is composed of an MAL,
wherein each MAL is composed of two precursors selected from
different precursors related to the components, and a non-mosaic
atomic layer composed of any precursor selected from the different
precursors. The non-mosaic atomic layer may be formed on the MAL,
or the MAL may be formed on the non-mosaic atomic layer.
[0031] The MAL is preferably a double layer. The double layer may
be an MAL composed of a first MAL composed of all of the different
precursors and a second MAL composed of two precursors selected
from the different precursors, an MAL composed of a first MAL
composed of all of the different precursors, or an MAL composed of
the same precursors, which have a different composition ratio for
each of layers in the double layer.
[0032] The double layer may also be composed of a first MAL,
composed of first and second precursors selected from the different
precursors, and a second MAL formed on the first MAL, composed of
first and third precursors selected from the different
precursors.
[0033] In both embodiments mentioned above in which a thin film is
provided, the thin film may be an oxide layer, a nitride layer or a
boride layer. The thin film may also be one selected from the group
consisting of an STO layer, a PZT layer, a BST layer, a YBCO layer,
an SBTO layer, an HfSiON layer, a ZrSiO layer, a ZrHfO layer, a
LaCoO layer, and a TiSiN layer.
[0034] In the method of forming a thin film including multi
components according to the present invention, the advantages of a
conventional method of forming atomic layers (ALs) may be secured,
yet fewer steps are required in the process of forming ALs
according to the present invention than in the conventional method.
As a result, the time required for forming a thin film may be
reduced. Also, since the thin film is formed and crystallized at a
low temperature, an additional thermal process for the
crystallization of the thin film after formation thereof is
unnecessary. As a result, the yield of the method of forming a thin
film of the present invention is remarkably higher than in the
prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The above features and advantages of the present invention
will become more apparent to those of ordinary skill in the art by
describing in detail preferred embodiments thereof with reference
to the attached drawings in which:
[0036] FIG. 1 illustrates a flowchart of steps constituting one
cycle of a method of forming a thin film including multi components
using ALD according to the prior art;
[0037] FIG. 2 illustrates a graph showing results of simulation of
thermodynamic equilibrium of an SrTiO.sub.3 layer, which is one
thin film including multi components;
[0038] FIG. 3 illustrates a flowchart of steps constituting one
cycle of a method of forming a thin film including multi components
according to a first embodiment of the present invention;
[0039] FIG. 4A illustrates a plan view of a mosaic atomic layer
(MAL) which is formed by adsorbing different kinds of components
constituting a thin film on the surface of a substrate after a
first purge in one cycle of a method of forming the thin film
according to the first embodiment of the present invention;
[0040] FIG. 4B illustrates a cross-sectional view taken along line
b-b' of FIG. 4A;
[0041] FIG. 5 illustrates a flowchart of steps constituting one
cycle of a method of forming a thin film including multi components
according to a second embodiment of the present invention;
[0042] FIGS. 6 through 8 illustrate plan views of an atomic layer
formed of first precursors containing first components of a thin
film, which are chemisorbed on a substrate after a first purge in
one cycle of a method of forming a thin film according to the
second embodiment of the present invention;
[0043] FIGS. 9 through 11 illustrate plan views of an MAL formed of
second precursors containing second components of a thin film,
which are adsorbed on portions of a substrate between the first
precursors containing the first components after a second purge in
one cycle of a method of forming a thin film according to the
second embodiment of the present invention;
[0044] FIG. 12 illustrates a graph explaining a region which is
supplied with a source gas for forming a thin film according to the
first and second embodiments of the present invention;
[0045] FIG. 13 illustrates a view of one cycle of a method of
forming a thin film including multi components according to a fifth
embodiment of the present invention;
[0046] FIGS. 14 and 15 respectively illustrate graphs comparing
X-ray diffraction analysis of a thin film formed by a conventional
atomic layer deposition method with X-ray diffraction analysis of a
thin film formed by a conventional atomic layer deposition
method;
[0047] FIGS. 16 and 17 illustrate graphs showing carbon content,
which is measured to observe the degree of oxidization of a thin
film including multi components according to the first and second
embodiments of the present invention; and
[0048] FIG. 18 through 20 illustrate cross-sectional views of a
thin film formed according to first through third embodiments of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0049] Korean patent application numbers 2001-24684 and 2002-23297,
filed May 7, 2001 and Apr. 29, 2002, respectively, are incorporated
by reference herein in their entireties.
[0050] Hereinafter, a thin film including multi components and a
method of forming the thin film according to embodiments of the
present invention will be described in detail with reference to the
attached drawings. Here, a substrate is regarded as being loaded
into a reaction chamber. Also, the reaction chamber is not
specially limited. In other words, any reaction chamber in which an
atomic layer may be deposited is suitable.
[0051] A method of forming a thin film will first be described.
Unit material layers of a thin film of the present invention are
mosaic atomic layers (MALs), described in first and second
embodiments.
FIRST EMBODIMENT
[0052] Referring to FIG. 3, MALs, which are unit material layers of
a thin film, are formed on a substrate in step 100. The MALs are
formed of precursors containing components constituting the thin
film. Thus, if the thin film is formed of three components, the
MALs are formed of three precursors each containing the three
components. If the thin film is formed of four or more components,
the MALs are formed of four or more precursors each containing the
four or more components.
[0053] To form the MALs, all components constituting the thin film
are supplied into a reaction chamber in a predetermined amount in
consideration of the composition ratio of the components and
chemisorbed on the substrate. The MALs are single atomic layers
composed of a plurality of components constituting the thin
film.
[0054] As a detailed example of forming the MALs, if the thin film
is a three component system oxide layer, e.g., an STO layer, the
MALs are formed of a precursor containing Sr and a precursor
containing Ti. In other words, a predetermined amount of the
precursor containing Sr and a predetermined amount of the precursor
containing Ti are supplied into the reaction chamber at a time.
Here, it is preferable that the two precursors are supplied in a
smaller amount than when the two precursors each form an atomic
layer. This will be described later.
[0055] If the thin film is a BST layer containing three metal
elements, the MALs are formed by supplying a predetermined amount
of a precursor containing Ba, a predetermined amount of a precursor
containing Sr, and a predetermined amount of a precursor containing
Ti into the reaction chamber at a time. Here, it is preferable that
the substrate is maintained at a predetermined reaction temperature
so that the three precursors are chemisorbed on the substrate.
[0056] The thin film may be an oxide layer, a nitride layer, or a
boride layer, as well as the STO layer and the BST layer. For
example, the thin film may be a PZT layer, a YBCO layer, an SBTO
layer, an HfSiON layer, a ZrSiO layer, a ZrHfO layer, a LaCoO
layer, or a TiSiN layer.
[0057] If the thin film is an oxide layer, a nitride layer, or a
boride layer, the MALs are not oxidized, nitrified, or boronized.
Thus, the MALs are oxidized, nitrified, or boronized in a
subsequent process. This will be described later.
[0058] Precursors remaining after the MALs are formed on the
substrate may be physisorbed on the MALs. The precursors
physisorbed on the MALs may serve as particles in a subsequent
process and prevent the MALs from being oxidized, nitrified, or
boronized in a subsequent oxidation, nitrification, or boronization
process. Thus, it is preferable that the precursors physisorbed on
the MALs are removed. To remove the precursors physisorbed on the
MALs, the reaction chamber is purged using an inert gas, e.g., a
nitride gas or an argon gas, after the MALs are formed in step 110.
As a result, the MALs, which are unit material layers constituting
the thin film, remain as single atomic layers on the substrate.
This is shown in FIG. 4.
[0059] FIG. 4A illustrates a plan view of the MALs and FIG. 4B
illustrates a cross-sectional view taken along line b-b' of FIG.
4A. Reference numerals 130, 132, and 134 represent precursors
containing first components constituting a thin film, precursors
containing second components constituting the thin film, and a
substrate, respectively. In FIGS. 4A and 4B, it is shown that the
MALs may be formed of different precursors 130 and 132 each
containing different components constituting the thin film.
[0060] The MALs are chemically changed by supplying a predetermined
reaction gas into the reaction chamber in step 120. For example,
the MALs are oxidized, nitrified, or boronized. Here, the substrate
is heated to a predetermined temperature to react the reaction gas
with the MALs.
[0061] The reaction gas may be supplied with external energy to
lower the temperature for heating the substrate and increase the
reaction activity of the reaction gas. The method of oxidizing,
nitrifying, or boronizing the MALs depends on the method of
supplying the external energy. For example, when the MALs are
oxidized, radio frequency (RF) energy, a DC voltage, or microwave
energy is applied to a reaction gas such as O.sub.2, O.sub.3,
H.sub.2O, and H.sub.2O.sub.2 containing oxygen during the supply of
the reaction gas into the reaction chamber. Thus, the reaction gas
is plasmatized. As a result, the MALs are oxidized using
plasma.
[0062] If the external energy is ultraviolet, the MALs are oxidized
by a reaction of decomposing O.sub.3 under ultraviolet radiation.
In other words, the MALs are oxidized in an ultraviolet-ozone
process.
[0063] After the chemical change of the MALs is completed, first
through third steps from forming to chemically changing the MALs
are repeated until the MALs are formed to a desired thickness.
SECOND EMBODIMENT
[0064] Unit material layers of a thin film are formed as MALs on a
substrate by supplying components constituting the thin film by a
time-sharing method. Here, the thin film is the same as the thin
film described in the first embodiment.
[0065] Referring to FIG. 5, first atomic layers (hereinafter,
referred to as "first discrete atomic layers) are formed of
precursors which are spaced apart from each other in step 200.
Specifically, conventional atomic layers are formed to completely
cover the entire surface of the substrate (on the entire surface of
the structure if a structure is formed on the substrate). Thus, the
conventional atomic layers are continuous atomic layers. However,
precursors containing first components of components constituting a
thin film are discrete on the substrate to form the first discrete
atomic layer. Here, the precursors are uniformly discrete on the
entire surface of the substrate. Second components constituting the
thin film, which will be supplied later, may be uniformly
chemisorbed between the first components. Here, it is preferable
that the substrate is maintained at a reaction temperature so that
the supplied components are chemisorbed on the substrate. The
components may be heated to the reaction temperature or a
temperature close to the reaction temperature in the course of
being supplied.
[0066] FIG. 6A illustrates a plan view of the first discrete atomic
layer formed of precursors containing the first components and FIG.
6B illustrates a cross-sectional view taken along line b-b' of FIG.
6A. Here, reference numeral 202 represents the first discrete
atomic layer, reference numeral 204 represents precursors
(hereinafter, referred to as "first precursors") containing the
first components constituting the first discrete atomic layer, and
reference numeral 206 represents a substrate on which the first
discrete atomic layer 202 is chemisorbed. A thin film, which is
formed on the substrate 206, contains at least three components. At
least two of the three components are chemisorbed on the substrate
206.
[0067] For example, if the thin film is a thin film including multi
components such as an SrTiO.sub.3 layer or a BaTiO.sub.3 layer
containing three components, the first precursors 204 contain
strontium (Sr), barium (Ba), or Titanium (Ti). The first discrete
atomic layer 202 is formed by chemisorbing the precursors
containing strontium (Sr) or barium (Ba) on the substrate 206.
[0068] Steps of forming the thin film containing the three
components are also applied to a thin film containing four
components. Here, if an oxygen component is contained in the four
components, the first precursors 204 contain any of the other four
components (i.e. not the oxygen component). Chemisorbing the
precursors on the substrate forms the first discrete atomic layer
202, which is uniformly discrete.
[0069] As shown in FIG. 6B, unlike the precursors constituting the
conventional continuous atomic layers, the first precursors 204
constituting the first discrete atomic layer 202 are widely
discrete on the substrate 206. Reference numeral 208 represents
second precursors, which will be formed between the first
precursors 204 in a subsequent process.
[0070] The distribution of the first precursors 204 may vary,
depending on the kinds of first precursors 204 and second
precursors 208. For example, as shown in FIGS. 7 and 8, the first
discrete atomic layer 202 (FIGS. 6A and 6B) may have a structure in
which precursors 204 are arranged in an oblique line, or in which
precursors 204 are arranged in a hexagonal shape with one precursor
in the center.
[0071] The characteristics of the shape of the first discrete
atomic layer 202, i.e., the distance between the first precursors
204, is determined by the amount of the first precursors 204
supplied. For example, if the thin film is an SrTiO.sub.3 layer,
the first discrete atomic layer 202 is formed of Sr precursors.
Also, the distribution of the first discrete atomic layer 202 is
determined by the amount of Sr precursors supplied into the
reaction chamber. Preferably, the Sr precursors are supplied in a
smaller amount than Sr precursors supplied to form an SrTiO.sub.3
layer by a conventional method of forming an atomic layer.
[0072] In detail, G12 of FIG. 12 is a graph showing changes in the
amount of Sr precursors with respect to time when an SrTiO.sub.3
layer is formed by the conventional method of an atomic layer.
Reference numeral S represents a saturated region. The saturated
region S represents a region in which a sufficient amount of the Sr
precursors is supplied so that the Sr precursors are adsorbed on
the entire surface of the substrate. Reference numeral S.sub.0 is
an initial region, in which the supply of Sr precursors begins, and
becomes the saturated region S as time passes. Thus, the amount of
Sr precursors supplied in the initial region S.sub.0 is smaller
than the amount of Sr precursors supplied in the saturated region
S. As a result, the substrate is not completely covered with only
the amount of Sr precursors supplied in the initial region S.sub.0.
There is no cause for the Sr precursors to be adsorbed onto only a
particular region of the substrate during the supply of Sr
precursors into the reaction chamber. In other words, the
probability that the Sr precursors supplied into the reaction
chamber are adsorbed on any particular region of the substrate in
any one step is equivalent to the Sr precursors. As a result, the
Sr precursors supplied in the initial region S.sub.0 are discrete
on the substrate.
[0073] As shown in FIGS. 6A and 6B, the first discrete atomic layer
202 containing the first components having various distribution
shapes as described above may be formed by controlling the amount
of precursors supplied on the substrate in the initial region
S.sub.0. Vacant regions 208, on which second precursors containing
second components may be adsorbed, exist between the first
precursors 204 on the substrate.
[0074] As described above, the shape of the first discrete atomic
layer 202 may be determined by limiting the amount of precursors
supplied into the reaction chamber to that of the initial region
S.sub.0 (FIG. 12). Even in this case, it is preferable that the
amount of precursors required for forming the first discrete atomic
layer 202 containing the first components varies according to the
number of components constituting the thin film, the composition
ratio of the components, and the order of forming the components,
i.e. which component is first formed.
[0075] For example, supposing that the first discrete atomic layer
202 containing the first components is formed during the formation
of a thin film containing three components, and reference numeral
A.sub.N of FIG. 12 represents the amount of precursors. The amount
of precursors supplied for forming an initial atomic layer on a
substrate during the formation of a thin film containing four or
more components may be smaller than or equal to the amount A.sub.N
depending on which one of the four components the initial atomic
layer contains, i.e., the composition of a component contained in
the precursors constituting the initial atomic layer occupying the
four components.
[0076] Referring to FIGS. 5 and 6, the reaction chamber is purged
for the first time in step 300. It is preferable that the first
precursors 204 are all used in forming the first discrete atomic
layer 202 containing the first components. However, a portion of
the first precursors 204 may not be used in forming the first
discrete atomic layer 202. If the first precursors 204 remain in
the reaction chamber, the first precursors 204 are mixed with other
precursors that may be supplied later. As a result, a thin film
having an unwanted shape may be formed. Thus, it is preferable that
any of the first precursors 204 which are not used in forming the
first discrete atomic layer 202 are discharged from the reaction
chamber. In other words, in step 300, the reaction chamber is
purged using an inert gas which does not react chemically, to
discharge precursors not used in forming the first discrete atomic
layer 202. Here, the inert gas is Ar, N.sub.2, or O.sub.2.
[0077] A second discrete atomic layer composed of precursors
containing second components is formed in step 400. Here, the
precursors (hereinafter, referred to as "second precursors")
constituting the second discrete atomic layer are chemisorbed on
portions of the substrate between the first precursors.
[0078] In detail, after the first purge in step 300, a
predetermined amount of the second precursors is supplied into the
reaction chamber. Here, the second precursors contain the second
components, which are selected from components constituting the
thin film, and may be chemisorbed on the substrate.
[0079] For example, if the thin film is a SrTiO.sub.3 layer or a
BaTiO.sub.3 layer, the second precursors contain Ti. If the first
precursors 204 contain Ti, the second precursors contain Sr or Ba.
This may be applied to a thin film containing four or more
components, three or more components of which are adsorbed on the
substrate.
[0080] It is preferable that the second precursors are supplied in
consideration of the following. If the second precursors contain
the last one of the components contained in the thin film which are
chemisorbed on the substrate, it is preferable that the second
precursors are sufficiently supplied so that the second precursors
are all adsorbed on vacant regions of the first discrete atomic
layer 202 containing the first components, i.e., on regions of the
substrate on which the first precursors are not adsorbed.
[0081] If the second precursors do not contain the last component,
third and fourth precursors which are chemisorbed are continuously
supplied after the second precursors are supplied. Thus, it is
preferable that first precursors are supplied in an amount
sufficient for leaving predetermined vacant regions on the
substrate between the first precursors on which subsequent
precursors are chemisorbed. As a result, subsequent precursors may
be chemisorbed between the first and second precursors even though
the first and second precursors are adsorbed on the substrate.
Thus, in the latter case, it is preferable that the second
precursors are supplied in the amount supplied in the initial
region S.sub.0 (FIG. 12) as when the first precursors are supplied.
However, the second precursors may be supplied in a larger or
smaller amount than the first precursors, according to the
composition ratio of the components contained in the second
precursors accounting for the thin film. In a case where the
component ratio of the components contained in the first precursors
is identical to the component ratio of the components contained in
the second precursors, and only the first and second precursors are
restricted as being chemisorbed, it is preferable that the amount
of the first precursors and the amount of the second precursors are
equal in the initial region S.sub.0. Referring to FIGS. 9A and 9B,
a mosaic atomic layer (MAL) 210, which is composed of the first
precursors 204 constituting the first discrete atomic layer 202 and
the second precursors 208 constituting the second discrete atomic
layer (and may be the same as the first discrete atomic layer 202
shown in FIG. 6), is formed on the substrate 206 as a unit material
layer constituting the thin film through the steps 200, 300, and
400 as shown in FIG. 5. If the MAL 210 of FIG. 9 is formed of only
the first and second precursors 204 and 208, it is preferable that
the first and second precursors 204 and 208 contact each other.
However, in FIG. 9, the first and second precursors 204 and 208 are
shown spaced apart from each other for convenience. This is applied
to various examples of the MAL 210 due to various arrangement
shapes of the first precursors 204 shown in FIGS. 10 and 11.
[0082] Referring again to FIG. 5, the reaction chamber is purged
for the second time in step 400. In other words, for the same
reason as in step 300, the reaction chamber is purged using an
inert gas after the MAL 210 of FIG. 9 is formed.
[0083] The MAL 210 is chemically changed in step 600. In other
words, the MAL 210 is oxidized, nitrified, or boronized using
several reaction gases. When bulky ligands are decomposed and
removed due to this chemical reaction, new chemisorbed points which
were covered by the ligands may be exposed.
[0084] To oxidize the MAL 210, reaction gas such as O.sub.2,
O.sub.3, H.sub.2O, and H.sub.2O.sub.2 is supplied into the reaction
chamber in a predetermined amount and reacts with the MAL 210.
Here, when the reaction gas is supplied into the reaction chamber,
radio frequency (RF) or microwave energy, or a DC voltage, may be
applied to the reaction gas, to increase the activity of the
reaction gases. Thus, the reaction gas may form plasma in the
reaction chamber. If the reaction gas is ozone, ultraviolet (UV) is
applied to the reaction gas to increase the activity of the
reaction gas. In other words, the MAL 210 is oxidized using
UV-O.sub.3.
[0085] The reaction chamber is purged for the third time in step
700. The gases remaining in the reaction chamber after step 500 are
purged using the inert gas.
[0086] Steps 200, 300, 400, 500, 600, and 700 are repeated until
the thin film is formed to a desired thickness.
[0087] If third and fourth precursors are further chemisorbed on
the substrate after the second purge in step 500, i.e., if the thin
film is not a nonoxide layer containing at least three components
or an oxide layer containing four or more components, a step of
forming an atomic layer composed of third precursors containing
third components, a third purge step, a step of forming an atomic
layer composed of four precursors containing four components, and a
fourth purge step, are sequentially performed before step 700.
[0088] When the formation of the MAL is repeated to form the thin
film, the compositions of the formed MALs may be different from
each other. In other words, when components constituting a
subsequent MAL are the same as components constituting a former
MAL, the composition of any one of precursors constituting the two
MALs, i.e., the composition of any one of components constituting
the thin film, may be different from the compositions of the other
components.
[0089] For example, if the thin film is an STO layer having a
predetermined thickness, the STO layer may be formed to a desired
thickness by repeatedly forming a unit material layer composed of
Sr precursors and Ti precursors, i.e., an Sr--Ti MAL. However, if
three Sr--Ti MALs are sequentially formed to form the STO layer,
the composition of precursors constituting a second or third Sr--Ti
MAL may be different from the composition of precursors
constituting a first Sr--Ti MAL. This composition may be controlled
by controlling the amount of precursors supplied into the reaction
chamber.
[0090] The second discrete atomic layer 210 may be formed by
supplying the second precursors two times in step 400. In other
words, the second discrete atomic layer is not completely formed by
suppling the second precursors only one time. Thus, the second
precursors are supplied for the first time in a predetermined
amount to form the second discrete atomic layer. Next, purging is
performed, and then the second precursors are supplied for the
second time in a predetermined amount, to complete the second
discrete atomic layer. If the second discrete atomic layer is not
completely formed after the second precursors are supplied for the
second time, the second precursors may be supplied for the third
time. Also, the amount of the second precursors may be different in
the first and second supplies.
[0091] This method may be applied to the thin films containing
three or more components described in the first embodiment as well
as the STO layer.
THIRD EMBODIMENT
[0092] A unit material layer is formed of a double MAL. In detail,
if a thin film to be formed contains at least three components, the
three components are divided into two and the two are each formed
as MALs.
[0093] For example, if the thin film contains three components,
i.e., A.sub.1X-YB.sub.XC.sub.Y, a first MAL (A.sub.1-XB.sub.X)
composed of precursors containing a component A (hereinafter,
referred to as "precursors A") and precursors containing a
component B (hereinafter, referred to as "precursors B") is formed
on a substrate. Next, a second MAL (A.sub.1-YC.sub.Y) composed of
the precursors A and precursors containing a component C
(hereinafter, referred to as "precursors C") is formed on the first
MAL (A.sub.1-XB.sub.X). Here, the first and second MALs may be
formed according to the first and second embodiments. Also, the
first MAL may be oxidized before the second MAL is formed so that
the second MAL is chemisorbed on the first MAL. The first MAL is
oxidized according the oxidation process described in the first or
second embodiment. It is preferable that purging is performed among
the steps of forming the second MAL. After the second MAL is
formed, the second MAL is oxidized according to the process of
oxidizing the first MAL. Thus, the first and second MALs are a unit
material layer constituting the thin film. Next, the processes of
forming the first and second MALs are repeated on the oxidized
second MAL, to form the thin film to a desired thickness.
[0094] The thin film formed by the method of forming a thin film
according to the third embodiment of the present invention may
correspond to all of the thin films described in the process of
forming a thin film according to the first embodiment.
[0095] As an example, if the thin film is a PZT layer, precursors
A, B, and C represent precursors containing Pb, precursors
containing Zr, and precursors containing Ti, respectively. The
first and second MALs are an MAL composed of the precursors
containing Pb and Zr and an MAL composed of the precursors
containing Pb and Ti, respectively. Also, if the thin film is a BST
layer, the precursors A, B, and C represent precursors containing
Ba, precursors containing Sr, and precursors containing Ti,
respectively, and the first and second MALs are an MAL composed of
the precursors Ba and Sr and an MAL composed of the precursors
containing Ba and Ti, respectively.
FOURTH EMBODIMENT
[0096] A thin film is formed of unit material layers, a portion of
which are MALs and the others are atomic layers (ALs) on the MALs.
In other words, unit material layers constituting the thin film are
formed of MALs and ALs. Here, the ALs are non-mosaic atomic
layers.
[0097] In detail, if the thin film contains three or more
components, e.g., components A, B, and C as described in the third
embodiment, an MAL is formed of precursors A and B each containing
the components A and B on a substrate to form the thin film. Here,
the MAL is formed by the methods described in the first, second,
and third embodiments. Next, a reaction chamber is purged. An AL is
formed of the precursors C containing the component C on the MAL.
Here, it is preferable that the AL is formed, preferably
chemisorbed, after the MAL is oxidized as described in the second
embodiment.
[0098] Thus, the unit material layer is formed of the MAL composed
of the precursors A and B and the AL composed of the precursors C
on the substrate. The MAL may be formed of the precursors A and C
instead of the precursors A and B. Thus, the AL may be formed of
the precursors B.
[0099] The AL is formed of the precursors C on the MAL and oxidized
by the same method as when oxidizing the MAL. The thin film is
formed to a desired thickness by repeating former steps on the
oxidized AL.
FIFTH EMBODIMENT
[0100] An oxidization gas or a deoxidization gas is supplied to
react an MAL with chemically adsorbed precursors in a process of
forming the MAL containing at least two kinds of components, e.g.,
Sr and Ti. By-products generated in this process, e.g.,
hydrocarbon-based by-products, may exist on the surface of the
MAL.
[0101] In a process of forming a thin film including multi
components containing at least two kinds of metallic atoms using an
MAL process or an ALD process, it is difficult to perform a
subsequent cycle of the MAL process or the ALD process due to these
by-products. Thus, it is necessary to remove the by-products, and
the fifth embodiment of the present invention is directed to this
removal.
[0102] In detail, referring to FIG. 13, three steps are
sequentially performed: supplying a source gas to form the MAL,
step 500; firstly purging remainder that is not adsorbed after the
supply of the source gas step 510; and supplying a reaction gas (an
oxidization or deoxidization gas) to oxidize or deoxidize the MAL,
step 520. Thereafter, a second purge step 530 is performed to
remove by-products generated due to the reaction of the MAL and the
reaction gas. In the second purge step 530, a purge gas is an inert
gas such as Ar, He, Ne, or N.sub.2. In the second purge step 530
using the purge gas, DC-bias is applied to the substrate to
increase of an efficiency of removing the by-products so as to make
the inert gas into plasma. In other words, inert gaseous plasma is
generated and used as the purge gas in the second purge step 530.
Positive ions of the inert gaseous plasma bombard against the
surface of the MAL, which results in the removal of the by-products
adsorbed on the surface of the MAL.
[0103] As described above, a thin film which is less contaminated
by impurities may be formed by using the inert gaseous plasma as
the purge gas after supplying the reaction gas. In particular, the
bombardment of ions having high energy against the by-products
adsorbed on the surface of the MAL can achieve a high temperature
deposition effect although the thin film is deposited at a low
temperature.
[0104] The fifth embodiment of the present invention, as described
above, may be applied to the ALD process containing two kinds of
components as well as the MAL deposition process.
[0105] X-ray diffraction analysis of a thin film formed by a method
of forming a thin film including multi components according to the
present invention and of a thin film formed by a conventional
atomic layer deposition method will be described. Here, the thin
films including multi components are SrTiO.sub.3 layers.
[0106] In detail, FIG. 14 shows the results of X-ray diffraction
analysis of a thin film formed according to the prior art. FIG. 15
shows the results of X-ray diffraction analysis of a thin film
formed according to the present invention.
[0107] In FIG. 14, peaks due to ruthenium (Ru) and silicon (Si) are
shown, and in FIG. 15, peaks due to ruthenium (Ru), silicon (Si),
and SrTiO.sub.3 are shown. Reference numeral Ps in FIG. 15 is the
peak due to SrTiO.sub.3.
[0108] Conventionally, there are no peaks showing the
crystallization of the thin film including multi components. In the
present invention, there are peaks showing the crystallization of
the thin film including multi components.
[0109] Accordingly, unlike the in conventional processes, after a
thin film including multi components is formed according to the
embodiments of the present invention, an additional thermal
treatment for the crystallization of the thin film is
unnecessary.
[0110] FIGS. 16 and 17 are graphs showing the analysis of titanium
content after a titanium layer is formed on a substrate and
oxidized, to observe the possibility of oxidization of a thin film
including multi components according to the first through fourth
embodiments of the present invention. FIG. 16 shows the result
after a titanium atomic layer is formed on a substrate, a titanium
layer is physisorbed on the titanium atomic layer, and a process of
oxidizing the resultant structure is repeated. FIG. 17 shows the
result after a titanium atomic layer is formed on a substrate and a
process of oxidizing the resultant structure is repeated. In FIGS.
16 and 17, reference numerals G.sub.o, G.sub.ti, G.sub.si, and
G.sub.c represent changes in the contents of oxygen, titanium,
silicon, and carbon, respectively. Here, it is noted that the whole
titanium layer is oxidized on a substrate, and the carbon component
is less than 0.5%. From this result, it is noted that the first and
second MALs may be formed and fully oxidized at the same time.
Also, at least two MALs may be formed on the substrate and oxidized
at the same time, as a cycle by which an atomic layer is formed on
the substrate.
[0111] A thin film formed by a method of forming a thin film
according to embodiments of the present invention will now be
described.
FIRST EMBODIMENT
[0112] As shown in FIG. 18, a thin film 800 is formed of a
plurality of unit material layers L on a substrate 206. The unit
material layers L are composed of first components P1 and second
components P2. Here, the thin film 800 is an oxide layer, a nitride
layer, or a boride layer. The thin film may be an STO layer, a PZT
layer, a BST layer, a YBCO layer, an SBTO layer, an HfSiON layer, a
ZrSiO layer, a ZrHfO layer, a LaCoO layer, or a TiSiN layer.
[0113] The unit material layers L are preferably MALs composed of
components of which the thin film is composed. Thus, if the thin
film is composed of first through third components, the unit
material layers L are MALs which are composed of the first through
third components. If the thin film is composed of first through
fourth components, the unit material layers L are MALs which are
composed of the first through fourth components.
SECOND EMBODIMENT
[0114] In the second embodiment, a thin film is formed of three
components having a predetermined composition. As shown in FIG. 19,
a thin film 900 is formed of a plurality of unit material layers
L1, which are each double MALs. In other words, a unit material
layer L1 is composed of a first MAL L1a and a second MAL L1b, which
are sequentially formed. The first MAL L1a is composed of first
components P21 and second components P22 of which the thin film 900
is composed. The second MAL L1b is composed of the first components
P21 and third components P23, of which the thin film 900 is
composed.
THIRD EMBODIMENT
[0115] As shown in FIG. 20, a thin film 1000 is formed of unit
material layers L2 which are composed of MALs L2a and atomic layers
L2b. The MALs L2a are composed of first and second components P31
and P32 of which the thin film 1000 is formed, and the atomic
layers L2b are composed of third components P33 of which the thin
film 1000 is formed.
[0116] In the first through third embodiments, any one of a single
MAL L and a double MAL L1 constituting a unit material layer of a
thin film, or the MAL L2a and an atomic layer L2b constituting a
unit material layer of a thin film, is an atomic layer composed of
at least two different components. Thus, though not shown in FIGS.
18 through 20, MALs constituting unit material layers of a thin
film according to each of the first through third embodiments may
be mosaic atomic layers composed of (precursors containing) three
or four different components depending on the number of components
constituting the thin film.
[0117] As described above, in the method of forming a thin film
including multi components according to the present invention, unit
material layers constituting a thin film are formed of single MALs
or double MALs containing components of which at least one is
different from the others. The unit material layers may be composed
of MALs and ALs containing only one of the components constituting
the thin film. Thus, the advantages of a conventional method of
forming ALs may be secured, and fewer steps are required in the
process of forming ALs according to the present invention than in
the conventional process of forming ALs. As a result, the time
required for forming a thin film may be reduced. Also, since the
thin film is formed and crystallized at a low temperature, an
additional thermal process for the crystallization of the thin film
after formation thereof is unnecessary. As a result, the yield of
the method of forming a thin film of the present invention is
remarkably higher than in the prior art.
[0118] Preferred embodiments of the present invention have been
disclosed herein and, although specific terms are employed, they
are used in a generic and descriptive sense only and not for the
purpose of limitation. For example, if the number of components
constituting a thin film is large, the thin film may be formed by a
dual method by one of ordinary skill in the art. In other words,
instead of forming and oxidizing MALs containing components
constituting a thin film, MALs containing a portion of the
components may be formed. For example, at least two MALs are formed
and oxidized and then MALs containing the other components are
formed and oxidized. Also, another embodiment, which is not
described in the detailed description, may be realized by a
combination of methods according to the embodiments of the present
invention. For example, a first MAL may be formed on a substrate by
a method of forming a thin film according to a first embodiment of
the present invention. Any one of subsequent MALs may be formed by
a method of forming a thin film according to a second embodiment of
the present invention. Accordingly, it will be understood by those
of ordinary skill in the art that various changes in form and
details of the above-described embodiments of the present invention
may be made without departing from the spirit and scope of the
present invention as set forth in the following claims.
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