U.S. patent application number 10/572216 was filed with the patent office on 2007-03-08 for phase change film for semiconductor nonvolatile memory and sputtering target for forming phase change film.
This patent application is currently assigned to Mitsubishi Materials Corporation. Invention is credited to Kei Kinoshita, Satoru Mori, Sohei Nonaka.
Application Number | 20070053786 10/572216 |
Document ID | / |
Family ID | 34380303 |
Filed Date | 2007-03-08 |
United States Patent
Application |
20070053786 |
Kind Code |
A1 |
Nonaka; Sohei ; et
al. |
March 8, 2007 |
Phase change film for semiconductor nonvolatile memory and
sputtering target for forming phase change film
Abstract
A phase change film for a semiconductor nonvolatile memory and a
sputtering target for forming the phase change film. The phase
change film for a semiconductor nonvolatile memory and the
sputtering target for forming the phase change film have a
composition containing 10 to 25 atomic % of Ge, 10 to 25 atomic %
of Sb, 1 to 10 atomic % of Ga, and 10 atomic % or less of B, Al, C,
Si and lanthanoid elements, with the balance being Te and
inevitable impurities.
Inventors: |
Nonaka; Sohei; (Sanda-shi,
JP) ; Kinoshita; Kei; (Sanda-shi, JP) ; Mori;
Satoru; (Sanda-shi, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P. O. BOX 5257
NEW YORK
NY
10150-5257
US
|
Assignee: |
Mitsubishi Materials
Corporation
5-1, Otemachi 1-chome
Chiyoda-ku, Tokyo
JP
100-8117
|
Family ID: |
34380303 |
Appl. No.: |
10/572216 |
Filed: |
September 8, 2004 |
PCT Filed: |
September 8, 2004 |
PCT NO: |
PCT/JP04/13036 |
371 Date: |
October 19, 2006 |
Current U.S.
Class: |
420/579 ;
257/E45.002 |
Current CPC
Class: |
C23C 14/3414 20130101;
C23C 14/14 20130101; H01L 45/1625 20130101; H01L 45/06 20130101;
H01L 45/144 20130101 |
Class at
Publication: |
420/579 |
International
Class: |
C22C 28/00 20060101
C22C028/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2003 |
JP |
2003-324063 |
Mar 31, 2004 |
JP |
2004-102724 |
Claims
1. A phase change film for a semiconductor nonvolatile memory
having a composition comprising: 10 to 25 atomic % of Ge; 10 to 25
atomic % of Sb; 1 to 10 atomic % of Ga; and a balance of Te and
impurities.
2. A phase change film for a semiconductor nonvolatile memory
comprising: 10 to 25 atomic % of Ge; 10 to 25 atomic % of Sb; 1 to
10 atomic % of Ga; a total of 10 atomic % or less of at least one
or more elements selected from a group consisting of B, Al, C, Si
and lanthanoid elements; and a balance of Te and impurities.
3. The phase change film for a semiconductor nonvolatile memory
according to claim 2, wherein the lanthanoid elements are at least
one or more elements selected from a group consisting of Dy, Tb,
Nd, Sm, and Gd.
4. The phase change film for a semiconductor nonvolatile memory
according to claim 1, wherein the electric resistivity of the film
measured by a four-point probe method after crystallization is
5.times.10.sup.-3 to 5.times.10 .OMEGA.cm, and the melting point of
the film is 600.degree. C. or less.
5. A sputtering target for forming a phase change film for a
semiconductor nonvolatile memory having a composition according to
claim 1.
6. A sputtering target for forming a phase change film for a
semiconductor nonvolatile memory having a composition according to
claim 2.
7. The sputtering target for forming a phase change film for a
semiconductor nonvolatile memory according to claim 6, wherein the
lanthanoid elements are at least one or more elements selected from
a group consisting of Dy, Tb, Nd, Sm, and Gd.
8. The phase change film for a semiconductor nonvolatile memory
according to claim 2 wherein the electric resistivity of the film
measured by a four-point probe method after crystallization is
5.times.10.sup.-3 to 5.times.10 .OMEGA.cm, and the melting point of
the film is 600.degree. C. or less.
Description
CROSS-REFERENCE TO PRIOR APPLICATION
[0001] This is a U.S. National Phase Application under 35 U.S.C.
.sctn.371 of International Patent Application No. PCT/JP2004/013036
filed Sep. 8, 2004, and claims the benefit of Japanese Patent
Application Nos. 2003-324063 filed Sep. 17, 2003 and 2004-102724
filed Mar. 31, 2004, both of which are incorporated by reference
herein. The International Application was published in Japanese on
March 31, 2005 as WO 2005/029585 al under PCT Article 21(2).
TECHNICAL FIELD
[0002] The present invention relates to a phase change film for a
semiconductor nonvolatile memory and a sputtering target for
forming the phase change film.
BACKGROUND ART
[0003] Phase change films for semiconductor nonvolatile memory
(Phase Change RAM or PCRAM) has been used as recording layers. A
phase change material in a crystalline state is used for the
recording layers. In this case, rewrite is performed by rapidly
heating and melting a portion of the phase change material with a
heater, and then rapidly cooling the portion to make it partially
amorphous, or otherwise slowly heating an amorphous portion at the
temperature over its crystallization temperature and under its
melting point, to bring it back to a crystalline state. Meanwhile,
readout is performed due to difference between the electrical
resistances of the phase change material in a crystalline state and
a partially amorphous state. As one of the phase change films,
there is known a phase change film having a composition containing
10 to 25% of Ge and 10 to 25% of Sb, with the balance being Te and
inevitable impurities. There is also known a phase change film
formed by performing sputtering using a target with almost the same
component composition as the above phase-change recording layer.
For example, see JP-W No. 2001-502848, JP-W No. 2002-512439, JP-W
No. 2002-540605 "OYO BUTURI" (A monthly publication of The Japan
Society of Applied Physics, Vol. 71, No. 12, 2002, p. 1513 to
1517
[0004] [Non-Patent Document 2] "Nikkei Micro-devices", March issue
in 2003, p.104
[0005] As disclosed in "OYO BUTURI" at the time of writing/erasing,
it is first necessary to raise the temperature of crystal above a
melting point, particularly, in order to change a crystalline state
to an amorphous state (reset operation). In this case, if the
melting point is high, the value of a current which is allowed to
flow through a circuit should be large. As a consequence, the power
consumption increases, and large current flow increases the load to
a peripheral circuit, thereby to reduce the size of the circuit is
prevented.
DETAILED DESCRIPTION OF THE INVENTION
[0006] Therefore, the inventors of the present invention have
conducted research to solve such problems. As a result, the
following research results were obtained.
[0007] When 1 to 10% of Ga is contained in an ordinary phase change
film with a composition containing 10 to 25% of Ge and 10 to 25% of
Sb, with the balance being Te and inevitable impurities, the
melting point can be lowered and the electric resistivity of the
film in a crystalline state barely changes. Therefore, the amount
of the current needed for melting can be reduced. Thus, the power
consumption can be reduced and a burden to a peripheral circuit can
be relived.
[0008] Further, if the presence of B, Al, C, Si or a lanthanoid
element is 10% or less of the film, the electric resistivity rises,
and thus the amount of current needed for melting is further
reduced. Accordingly, the power consumption can be reduced.
[0009] Among the lanthanoid elements, Dy, Tb, Nd, Sm, and Gd are
particularly effective.
[0010] The present invention is achieved based on these research
results, and is characterized by:
[0011] A phase change film for a semiconductor nonvolatile memory
with a composition containing 10 to 25 atomic % of Ge, 10 to 25
atomic % of Sb, and 1 to 10 atomic % of Ga, with the balance being
Te and inevitable impurities, and
[0012] A phase change film for a semiconductor nonvolatile memory
with a composition 10 to 25 atomic % of Ge, 10 to 25 atomic % of
Sb, 1 to 10 atomic % of Ga, and a total of 10 atomic % or less of
at least one or more elements selected from a group consisting of
B, Al, C, Si and lanthanoid elements, with the balance being Te and
inevitable impurities.
[0013] Among the lanthanoid elements, Dy, Tb, Nd, Sm, and Gd are
particularly preferable. Accordingly, the present invention is
characterized by the phase change film for a semiconductor
nonvolatile memory as described above in which the lanthanoid
elements are at least one or more elements selected from a group
consisting of Dy, Tb, Nd, Sm, and Gd.
[0014] In the phase change film for a semiconductor nonvolatile
memory described above, preferably, the electric resistivity of the
film measured by the four-point probe method after crystallization
is 5.times.10.sup.-3 to 5.times.10 .OMEGA.cm, and the melting point
of the film is 600.degree. C. or less. Accordingly, the present
invention is characterized by a phase change film for a
semiconductor nonvolatile memory described above, wherein the
electric resistivity of the film measured by the four-point probe
method after crystallization is 5.times.10.sup.-3 to 5.times.10
.OMEGA.cm, and the melting point of the film is 600.degree. C. or
less.
[0015] The phase change film formed using the sputtering targets of
the present invention enables a low melting point to be obtained
without remarkably lowering resistance so much, and can reduce a
current value at the time of writing operation, contribute to the
reduction in power consumption and a miniaturization of devices,
and make a great contribution to the development of a new
semiconductor memory industry.
[0016] The reasons why the component compositions of the phase
change film for a semiconductor nonvolatile memory according to the
present invention are limited, as mentioned above, will be
described.
[0017] When Ga component is contained in a phase change film with a
composition containing 10 to 25% of Ge and 10 to 25% of Sb, with
the balance being Te and inevitable impurities, Ga component has a
function to further lower the melting point of the phase change
film. However, if less than 1% of Ga is contained, the effect of
lowering the melting point is little, which is not preferable. On
the other hand, if Ga is contained over 10%, the crystallization
temperature rises excessively, which is not preferable. A proper
rise in the crystallization temperature improves the stability of
an amorphous state which leads to improvement of the retention
characteristics. However, if the crystallization temperature rises
excessively, the electric power required for crystallization
increases, which is not preferable from the viewpoint of a reducing
power consumption. Accordingly, the amount of Ga to be contained in
the phase change film is set to be 1 to 10% (more preferably, 2 to
8%).
[0018] In addition, even if 1 to 10% of Ga is contained in the
phase change film of a semiconductor nonvolatile memory with a
composition containing 10 to 25% of Ge and 10 to 25% of Sb, with
the balance being Te and inevitable impurities, the electric
resistivity of the film in its crystallized state is not
lowered.
[0019] Further, the phase change film with a composition containing
10 to 25% of Ge and 10 to 25% of Sb, with the balance being Te and
inevitable impurities, has mainly two types of crystal structures,
i.e., a face-centered cubic crystal structure having a high
resistance and a hexagonal crystal structure having a low
resistance. The face-centered cubic crystal structure is created
when the film is crystallized at a relatively low temperature, and
the hexagonal crystal structure is created when the film is kept at
a relatively high temperature. Since the phase change rate from an
amorphous state to a face-centered cubic crystal state is rapid,
the crystal which is created when the film is phase-changed and
crystallized from an amorphous state is generally face-centered
cubic crystal. However, if Ga is added to the conventionally known
composition of Ge--Sb--Te, the face-centered cubic crystal
structure is stabilized up to a high temperature as compared with
the case of not adding Ga. Therefore, Ga also has an effect of
improving the temperature stability of the electric
resistivity.
[0020] Because B, Al, C, Si, and lanthanoid elements have a
function to further raise a resistance value in a crystalline state
of the phase change film by the addition of Ga, they are added, if
necessary. However, if these components are contained over 10%, the
rise in the crystallization temperature of the phase change film
increases excessively, which is not preferable. A proper rise in
the crystallization temperature improves the stability of an
amorphous state which leads to improvement of the retention
characteristics. However, if the crystallization temperature rises
excessively, the electric power required for crystallization
increases, which is not preferable from the viewpoint of reducing
power consumption. Accordingly, the content of these components are
set to be 10% or less. The range of the content is more preferably
0.5 to 8%. In addition, among the lanthanoid elements, Dy, Tb, Nd,
Sm, and Gd are particularly preferable.
[0021] Ge and Sb contained in the phase change film having a high
electrical resistance according to the present invention is
preferably 10 to 25% of Ge and 10 to 25% of Sb. The reason is based
on the fact that, if Ge is less than 10% and Sb is less than 10%
and if Ge is over 25% and Sb is over 25%, the resistance value
becomes low and the crystallization time becomes long, which are
not preferable.
[0022] The phase change film according to the present invention
requires the electric resistivity value measured by the four-point
probe method after crystallization to be 5.times.10.sup.-3
.OMEGA.cm or more (more preferably, 8.times.10.sup.-2 .OMEGA.cm or
more). The reason comes from the fact that, if the electric
resistivity value is less than 5.times.10.sup.-3 .OMEGA.cm, a large
current flows through a circuit, which therefore increases the
power consumption and becomes an obstacle in reducing the size of
the circuit, which are not preferable. Further, the electric
resistivity of a Ge--Sb--Te alloy in an amorphous state is
generally about 1.times.10.sup.2 .OMEGA.cm. It is preferable that
this alloy has a difference of about at least one and a half digits
between the resistivities of the alloy in a crystalline state and
an amorphous state for stable read-out. Therefore, the resistivity
value of the phase change film in a crystalline state is required
to be 5.times.10 .OMEGA.cm or less. Accordingly, the electric
resistivity measured by the four-point probe method after the
crystallization of the phase change film according to the present
invention is set to be 5.times.10.sup.-3 .OMEGA.cm to 5.times.10
.OMEGA.cm. Moreover, the melting point of the phase change film
according to the present invention is required to be 600.degree. C.
from the viewpoint of low power consumption.
[0023] A sputtering target for forming a phase change film for a
semiconductor nonvolatile memory with the composition, as described
above according to the present invention, can have a component
composition containing 10 to 26 atomic % of Ge, 10 to 26 atomic %
of Sb, and 1 to 11 atomic % of Ga, with the balance being Te and
inevitable impurities.
[0024] Further, a sputtering target for forming a phase change film
for a semiconductor nonvolatile memory with the composition, as
described above can have a composition 10 to 26 atomic % of Ge, 10
to 26 atomic % of Sb, 1 to 11 atomic % of Ga, and a total of 11
atomic % or less of at least one or more elements selected from a
group consisting of B, Al, C, Si and lanthanoid elements, with the
balance being Te and inevitable impurities.
[0025] Accordingly, the present invention includes includes a
sputtering target for forming a phase change film for a
semiconductor nonvolatile memory with a composition containing 10
to 26 atomic % of Ge, 10 to 26 atomic % of Sb, and 1 to 11 atomic %
of Ga, with the balance being Te and inevitable impurities.
[0026] Another sputtering target for forming a phase change film
for a semiconductor nonvolatile memory can include a composition 10
to 26 atomic % of Ge, 10 to 26 atomic % of Sb, 1 to 11 atomic % of
Ga, and a total of 11 atomic % or less of at least one or more
elements selected from a group consisting of B, Al, C, Si and
lanthanoid elements, with the balance being Te and inevitable
impurities, and a further sputtering target for forming a phase
change film for a semiconductor nonvolatile memory as described
above in which the lanthanoid elements are at least one or more
elements selected from a group consisting of Dy, Tb, Nd, Sm, and
Gd.
[0027] The sputtering target for forming a phase change film for a
semiconductor nonvolatile memory having the component composition,
as described above according to the present invention, is
manufactured by melting a Ge--Sb--Te based alloy with a
predetermined component composition in an Ar gas atmosphere, then
adding Ga to the molten metal, pouring the molten metal into molds
made of iron to manufacture an alloy ingot, pulverizing the alloy
ingot in an inert gas atmosphere to manufacture an alloy powder
having a particle size of 200 .mu.m or less, and finally hot
pressing the alloy powder in a vacuum. The vacuum hot pressing is
performed by keeping the alloy powder under the following
conditions: a pressure of 146 to 155 MPa, a temperature of 370 to
430.degree. C., and a duration of 1 to 2 hours, and thereafter
cooling the molds to a normal temperature at a cooling rate of 1 to
3.degree. C./min when the temperature of the molds has dropped to
270 to 300.degree. C.
[0028] Moreover, the sputtering target for forming a phase change
film for a semiconductor nonvolatile memory having the component
composition, as described above according to the present invention,
is manufactured by adding Ga to a Ge--Sb--Te based alloy, mixing
this alloy powder with one or more of the separately manufactured
powders of B, Al, C, Si, and lanthanoid elements (preferably, Dy,
Tb, Nd, Sm, and Gd) each having a particle size of 200 .mu.m or
less so as to have component compositions according to the present
invention, and hot-pressing the alloy powder in a vacuum. The
vacuum hot pressing is performed by keeping the alloy powder under
the following conditions: a pressure of 146 to 155 MPa, a
temperature of 370 to 430.degree. C., and a duration of 1 to 2
hours, and thereafter cooling the molds to a normal temperature at
a cooling rate of 1 to 3.degree. C./min when the temperature of the
molds has dropped to 270 to 300.degree. C.
EXAMPLES OF THE INVENTION
[0029] Ge, Sb, and Te were melted in an Ar gas atmosphere. Ga was
added to the obtained molten metal. An alloy ingot was manufactured
by casting the molten metal obtained by adding Ga. An alloy powder
having a particle size of 100 .mu.m or less was manufactured by
reducing the alloy ingot to powder in an Ar atmosphere. Mixed
powders were manufactured by mixing the alloy powder with the
respective elemental powders of B, Al, C, Si, Dy, Tb, Nd, Sm, and
Gd.
[0030] Hot pressed bodies were manufactured by hot-pressing the
alloy power and the respective mixed powders in a vacuum at a
temperature of 400.degree. C. and at a pressure of 146 MPa. Targets
1 to 21 according to the present invention, comparative targets 1
to 10, and conventional target 1 having the following dimensions: a
diameter of 125 mm and a thickness of 5 mm, a disk shape, and
component compositions as shown in Table 1 were manufactured by
performing grinding processing on the hot pressed bodies under the
condition of a lathe revolution speed of 200 rpm, using a carbide
turning tool. TABLE-US-00001 TABLE 1 Component Composition (Atomic
%) B, Al, C, Si, Target Ge Sb Ga Lanthanoid Element Te Present 1 22
22 1.2 -- Balance Invention 2 21.9 21.9 1.5 -- Balance 3 21.8 21.8
2 -- Balance 4 21.5 21.5 3 -- Balance 5 21.1 21.1 5 -- Balance 6
20.4 20.4 8 -- Balance 7 20 20 10 -- Balance 8 20.8 20.8 4 B: 2.5
Balance 9 20.2 20.2 5 Al: 3.8 Balance 10 19.8 19.8 8 Si: 3.0
Balance 11 20.9 20.9 4 C: 2.0 Balance 12 18.8 18.8 10 Dy: 5.5
Balance 13 19.7 19.7 7 Tb: 1.5 Balance 14 19.8 19.8 3 Nd: 8.0
Balance 15 20.3 20.3 5 Sm: 3.5 Balance Present 16 20 20 6 Gd: 4.0
Balance Invention 17 20.9 20.9 3 B: 0.5, Al: 1.0 Balance 18 20.0
20.0 4 Al: 5, C: 1 Balance 19 20.2 20.2 5 C: 1, Si: 5, Dy: 2
Balance 20 19.8 19.8 2 Sm: 2, Tb: 5, Al: 2 Balance 21 19.0 19.0 7
B: 2, Si: 2, Balance Dy: 0.5, Sm: 3, Balance Comparative 1 22.1
21.1 0.3* -- Balance 2 19.1 19.1 14* -- Balance 3 17.3 17.3 9 B:
13* Balance 4 17.5 17.5 8 Si: 13* Balance 5 18.8 18.8 3 Gd: 12*
Balance Comparative 6 17.8 17.8 5 C: 15* Balance 7 18.0 18.0 7 Al:
12* Balance 8 18.2 18.2 4 Dy: 14* Balance 9 18.7 18.7 2 Nd: 14*
Balance 10 17.8 17.8 7 Tb: 13* Balance Conventional 22.2 22.2 -- --
Balance Target 1 Asterisk (*) means a value out of the range of the
present invention.
[0031] Next, each of the targets 1 to 21 according to the present
invention, comparative targets 1 to 10, and conventional target 1
is bonded to a cooling backing plate made of copper, with an indium
solder material having a purity of 99.999% by weight. Then, the
resulting targets are loaded into a direct-current magnetron
sputtering apparatus within which the distance between the targets
and substrates (Si wafers on the surface of each of which an
SiO.sub.2 film having a thickness of 100 nm is formed) is set to be
70 mm. Thereafter, the sputtering apparatus is vacuumed until the
degree of an ultimate vacuum thereof becomes 5.times.10.sup.-5 Pa
or less. Thereafter, the sputtering apparatus is supplied with Ar
gas until the total pressure thereof become 1.0 Pa.
[0032] Substrate temperature: room temperature
[0033] Input power: 50 W (0.4 W/cm.sup.2)
[0034] Then, sputtering was performed under the above conditions,
thereby forming phase change films 1 to 21, comparative phase
change films 1 to 10, and conventional phase change film 1, which
have a thickness of 300 nm and have component compositions as shown
Tables 4 to 6 on the surfaces of the substrates.
[0035] The component compositions of the phase change films 1 to
21, comparative phase change films 1 to 10, and conventional phase
change film 1, which were obtained in this way, were measured by an
inductively coupled plasma (ICP) method. The results thereof are
shown in Table 2.2 Moreover, the phase change films 1 to 21
according to the present invention, conventional phase change
films, and conventional phase change film 1, which were obtained,
were kept and crystallized in a nitrogen flow at a temperature of
230.degree. C. for five minutes. Thereafter, electric resistivities
were measured by a four-point probe method. Further, a film having
a thickness of 3 .mu.m was formed on a polycarbonate substrate
having a diameter of 120 mm under the conditions described above.
All of the formed film was peeled off and powderized. Then, the
crystallization temperatures and melting points of the powdered
materials were measured under the following conditions: an Ar flow
rate of 200 ml/min and a rising temperature of 10.degree. C./min,
by a differential thermal analysis (DTA) method. The results
thereof are shown in Table 2.2 In addition, the masses of samples
used in this measurement are standardized as 15 mg. It should be
noted herein that an exothermic peak appearing in the vicinity of
160 to 340.degree. C. is used as the crystallization temperature
and an endothermic peak appearing in the vicinity of 540 to
620.degree. C. is used as the melting point. TABLE-US-00002 TABLE 2
Component Composition (Atomic %) Specific Crystallization Melting
Phase B, Al, C, Si, Lanthanoid Resistance .times. 10.sup.-2
Temperature Point Change Film Ge Sb Ga Element Te (.OMEGA. cm)
(.degree. C.) (.degree. C.) Present Invention 1 21.8 22.1 1.1 --
Balance 1.89 170.3 595.8 2 21.3 22.0 1.3 -- Balance 1.87 174.0
593.1 3 21.2 21.7 1.8 -- Balance 1.94 178.7 586.9 4 21.6 21.2 2.4
-- Balance 1.96 188.1 581.3 5 20.3 21.0 4.5 -- Balance 2.03 206.8
570.8 6 20.2 20.9 7.1 -- Balance 1.91 234.8 555.4 7 19.6 20.1 9.0
-- Balance 1.87 253.5 547.2 8 20.8 20.3 3.2 B: 2.1 Balance 7.98
199.4 575.2 9 19.9 20 4.6 Al: 3.0 Balance 10.3 210.1 565.1 10 19.8
20.1 7.9 Si: 2.5 Balance 9.95 246.8 544.7 11 20.5 20.2 3.5 C: 0.9
Balance 11.1 211.5 576.1 12 18.1 19 8.7 Dy: 4.7 Balance 31.3 286.2
536.3 13 19.9 20.2 6.8 Tb: 0.6 Balance 26.8 231.2 554.2 14 19.2
19.5 2.9 Nd: 7.1 Balance 57.9 202.7 574.1 15 20.4 20.1 4.3 Sm: 2.9
Balance 22 213.1 568.8 Present Invention 16 19.1 19.8 5.2 Gd: 3.1
Balance 25.6 236.6 562.4 17 21.3 20.8 3.1 B: 0.3, Al: 0.5 Balance
18.4 228.6 573.4 18 19.8 20.3 3.8 Al: 4.0, C: 0.7 Balance 20.7
241.2 562.4 19 20.4 20.2 4.7 C: 0.5, Si: 1.2, Balance 23.4 224.1
566.4 Dy: 0.6 20 19.9 20.1 1.8 Sm: 1.4, Tb: 4.1, Balance 31.9 255.5
584.3 Al: 1.7 21 19.1 18.6 6.2 B: 1.5, Si: 1.4, Balance 38.4 268.9
554.7 Dy: 0.4, Sm: 2.1 Comparative 1 22 21.5 0.2* -- Balance 1.88
167.5 606.5 2 18.3 19.5 12.8* -- Balance 1.97 337.4 538.2 3 17.5
17.3 8.6 B: 12.4* Balance 52.8 301.4 546.9 4 17.1 17.6 7.8 Si:
12.0* Balance 36.8 314.7 545.6 5 17.5 17.5 2.7 G: 11.8* Balance
94.3 315.4 578.3 6 17.5 18.1 4.7 C: 13.8* Balance 84.5 325.6 564.1
7 17.3 18.1 6.8 Al: 11.3* Balance 54.8 314.3 549.3 8 18.4 18.3 3.3
Dy: 13.9* Balance 103.5 309.1 572.1 9 18.4 19.0 1.3 Nd: 13.1*
Balance 124.7 312.4 586.4 10 17.5 17.1 6.5 Tb: 12.3* Balance 115.8
321.3 551.7 Conventional 22.3 21.7 -- -- Balance 1.74 162.3 613.4
Target 1 Asterisk (*) means a value out of the range of the present
invention.
[0036] It can be understood from the results shown in Table 2 that
the crystallized phase change films 1 to 21 according to the
present invention, which were obtained by performing sputtering
using the targets 1 to 21 according to the present invention, are
excellent phase change films having lower melting points and having
little drop in electric resistivities, as compared with the
conventional phase change film 1, which was obtained by performing
sputtering using the conventional target 1. However, it can be
understood that at least one unfavorable characteristic appears in
the comparative phase change films 1 to 10 containing additive
components out of the range of this invention.
* * * * *