U.S. patent application number 13/780760 was filed with the patent office on 2014-01-02 for method for manufacturing semiconductor device.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Hajime EDA, Yukiteru MATSUI, Gaku MINAMIHABA.
Application Number | 20140004775 13/780760 |
Document ID | / |
Family ID | 49778594 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140004775 |
Kind Code |
A1 |
EDA; Hajime ; et
al. |
January 2, 2014 |
METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE
Abstract
According to an embodiment, a method for manufacturing a
semiconductor device includes polishing a metal layer provided on a
surface of a wafer, while supplying slurry to a polishing pad and
spraying gas to the polishing pad. The slurry includes an inorganic
particle, a resin particle, an oxidant for oxidizing the metal
layer, a complexing agent for forming an organic complex on a
surface of the metal layer, and a surfactant for forming a
hydrophilic film on a surface of the organic complex. The resin
particle includes a functional group on a surface, the functional
group having a same kind of polarity as that of the inorganic
particle. The resin particle contains polystyrene incorporated at a
concentration of 0.001% by weight or more and 0.1% by weight or
less, and has an average particle diameter of 200 nm or more and 1
.mu.m or less.
Inventors: |
EDA; Hajime; (Kanagawa-ken,
JP) ; MINAMIHABA; Gaku; (Kanagawa-ken, JP) ;
MATSUI; Yukiteru; (Aichi-ken, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Tokyo |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Tokyo
JP
|
Family ID: |
49778594 |
Appl. No.: |
13/780760 |
Filed: |
February 28, 2013 |
Current U.S.
Class: |
451/56 |
Current CPC
Class: |
B24B 53/017 20130101;
B24B 37/044 20130101 |
Class at
Publication: |
451/56 |
International
Class: |
B24B 53/017 20060101
B24B053/017 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2012 |
JP |
2012-146030 |
Claims
1. A method for manufacturing a semiconductor device comprising:
polishing a metal layer provided on a surface of a wafer, while
supplying slurry to a polishing pad and spraying gas to the
polishing pad, the slurry including: an inorganic particle; a resin
particle including a functional group on a surface, the functional
group having a same kind of polarity as that of the inorganic
particle, the resin particle containing polystyrene incorporated at
a concentration of 0.001% by weight or more and 0.1% by weight or
less, and having an average particle diameter of 200 nm or more and
1 .mu.m or less; an oxidant for oxidizing the metal layer; a
complexing agent for forming an organic complex on a surface of the
metal layer; and a surfactant for forming a hydrophilic film on a
surface of the organic complex.
2. The method according to claim 1, wherein the average particle
diameter of the resin particle is larger than an average particle
diameter of the inorganic particle.
3. The method according to claim 1, wherein the metal layer
contains copper (Cu).
4. The method according to claim 3, wherein the oxidant is ammonium
persulfate or a hydrogen peroxide solution.
5. The method according to claim 4, wherein a concentration of the
oxidant is 0.1% by weight or more and 5% by weight or less.
6. The method according to claim 1, wherein the gas is air or
nitrogen gas.
7. The method according to claim 1, wherein the resin particle
includes at least one of a carboxylic group and a sulfonyl group on
the surface.
8. The method according to claim 1, wherein the inorganic particle
contains at least one selected from the group consisting of
colloidal silica, fumed silica, colloidal alumina, fumed alumina,
colloidal titania, and fumed titania.
9. The method according to claim 1, wherein the inorganic particle
has a primary particle diameter ranging from 10 to 50 nm and a
secondary particle diameter ranging from 10 to 100 nm.
10. The method according to claim 1, wherein the complexing agent
is at least one selected from the group consisting of quinaldinic
acid (quinoline carboxylic acid), quinolinic acid
(pyridine-2,3-dicarboxylic acid), benzotriazole (BTA), nicotinic
acid (pyridine-3-dicarboxylic acid), picolinic acid, malonic acid,
oxalic acid, succinic acid, maleic acid, citric acid, glycine,
alanine, and aqueous ammonia.
11. The method according to claim 1, wherein a concentration of the
complexing agent is 0.01 to 1% by weight.
12. The method according to claim 1, wherein the surfactant is at
least one selected from the group consisting of ammonium
dodecylbenzene sulfonate, potassium dodecylbenzene sulfonate,
polyvinyl pyrrolidone, polyvinyl alcohol, ammonium polyacrylate,
hydroxy cellulose, acetylene diol-based nonion, and polyoxyethylene
alkylene ether.
13. The method according to claim 1, wherein a concentration of the
surfactant is 0.01% by weight or more and 0.5% by weight or less.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2012-146030, filed on
Jun. 28, 2012; the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments are generally related to a method for
manufacturing a semiconductor device.
BACKGROUND
[0003] A Chemical Mechanical Polishing (CMP) method is used for
planarization of a wafer surface in processes such as multilayer
interconnection and device isolation in a procedure for
manufacturing a semiconductor device. For example, a silicon oxide
film and tungsten (W), copper (Cu), and aluminum (Al) films formed
on the wafer surface are polished to form interconnects and contact
plugs. Along with progress of miniaturization of a semiconductor
device, there is a demand for improvement in planarity, reduction
in surface defects, and improvement in productivity. Especially,
since surface defects such as corrosion and a metal residue have a
large influence on manufacturing yield, there is a strong demand
for reduction in the surface defects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a perspective view schematically illustrating a
polishing apparatus according to an embodiment;
[0005] FIGS. 2A to 2D are schematic cross-sectional views
illustrating a manufacturing procedure of interconnects according
to the embodiment;
[0006] FIGS. 3A and 3B are cross-sectional views schematically
illustrating a polishing procedure of interconnects according to
the embodiment;
[0007] FIGS. 4A and 4B are cross-sectional views schematically
illustrating another polishing procedure of interconnects according
to the embodiment;
[0008] FIGS. 5A to 5C are photos showing surfaces of interconnect
layers after polishing;
[0009] FIG. 6 is a graph showing a polishing characteristic;
and
[0010] FIG. 7 is a graph showing another polishing
characteristic.
DETAILED DESCRIPTION
[0011] According to an embodiment, a method for manufacturing a
semiconductor device includes polishing a metal layer provided on a
surface of a wafer, while supplying slurry to a polishing pad and
spraying gas to the polishing pad. The slurry includes an inorganic
particle, a resin particle, an oxidant for oxidizing the metal
layer, a complexing agent for forming an organic complex on a
surface of the metal layer, and a surfactant for forming a
hydrophilic film on a surface of the organic complex. The resin
particle includes a functional group on a surface, the functional
group having a same kind of polarity as that of the inorganic
particle. The resin particle contains polystyrene incorporated at a
concentration of 0.001% by weight or more and 0.1% by weight or
less, and has an average particle diameter of 200 nm or more and 1
.mu.m or less.
[0012] Hereinafter, embodiments will be described with reference to
the drawings. It is to be noted that identical components in the
drawings are shown with the same reference numerals, description of
the duplicate components is omitted, and different components are
described.
[0013] The embodiments relate to a method for manufacturing a
semiconductor device and more specifically relate to a method for
polishing a silicon insulating film or a metal interconnect layer
in an interconnection process for a memory, a system LSI (Large
Scale Integrated Circuit), a high-speed logic LSI, a merged
memory/logic LSI, or the like.
[0014] FIG. 1 is a perspective view schematically showing a
polishing apparatus 10 according to an embodiment. The polishing
apparatus 10 includes a polishing stage 3, a wafer holder 15, a
slurry nozzle 23, and a gas nozzle 27. To an upper surface of the
polishing stage 3 is attached a polishing pad 7. On a face of the
wafer holder 15 facing the polishing pad 7 is fixed a wafer. The
polishing stage 3 is rotated in parallel with a polishing face 7a,
and the wafer holder 15 abuts on a surface of the polishing pad 7,
to polish a metal layer formed on a surface of a wafer 20.
[0015] The surface of the polishing pad 7 is supplied with slurry
25 via the slurry nozzle 23. A polishing procedure according to the
embodiment is performed using CMP, and the slurry 25 includes an
inorganic particle, a resin particle, an oxidant, a complexing
agent, and a surfactant.
[0016] Examples of the inorganic particle to be used contain at
least one selected from the group consisting of colloidal silica,
fumed silica, colloidal alumina, fumed alumina, colloidal titania,
and fumed titania. The inorganic particle favorably has a primary
particle diameter ranging from 10 to 50 nm and a secondary particle
diameter ranging from 10 to 100 nm. In a case where the particle
diameters are out of these ranges, surface defects such as
corrosion and a scratch may be generated. The corrosion in this
context refers to a surface defect caused by progress of a local
chemical reaction on a surface of the metal layer, for example, and
is revealed as corrosion or a dent such as dishing.
[0017] The particle diameter of the inorganic particle can be
measured directly by a TEM (Transmission Electron Microscope) or an
SEM (Scanning Electron Microscope), for example.
[0018] The resin particle is made of a resin containing polystyrene
and has on a surface a functional group of a same kind of polarity
as that of the inorganic particle. By adding polystyrene, the resin
particle is formed to have appropriate hardness. The resin particle
also has on the surface at least either a carboxylic group or a
sulfonyl group, for example. This prevents aggregation of the
inorganic particle and the resin particle.
[0019] The resin particle is also incorporated at a concentration
of 0.001% by weight or more and 0.1% by weight or less and has an
average particle diameter of 200 nm or more and 1 .mu.m or less.
The average particle diameter of the resin particle can be derived
by measuring a surface area of the particle by a BET method,
causing this value to be subjected to spherical reduction to obtain
a particle diameter, and calculating an average of the particle
diameters, for example. Alternatively, a particle diameter may be
measured by the TEM or the SEM to calculate the average particle
diameter.
[0020] The oxidant oxidizes a surface of the metal layer, and the
complexing agent forms an organic complex combined with metal oxide
on the surface of the metal layer. The organic complex protects the
surface of the metal layer and restricts a chemical reaction of the
metal layer. The surfactant forms a hydrophilic film on a surface
of the hydrophobic organic complex. Polishing progresses as the
inorganic particle and the hydrophilic resin particle scrape away
the organic complex formed on the surface of the metal layer. That
is, in the procedure of the CMP, polishing progresses as the
organic complex is formed to protect the surface of the metal layer
while the organic complex is scraped away. This restricts
generation of corrosion to enable the metal layer to be polished
uniformly.
[0021] In a case where the metal layer is copper (Cu), ammonium
persulfate or a hydrogen peroxide solution can be used for the
oxidant, for example. To accelerate oxidation on the surface of the
Cu layer, a concentration of the oxidant is favorably at least 0.1%
by weight or more. On the other hand, in a case where the content
of the oxidant is excessive, the solubility of the organic complex
formed on the surface of the Cu layer increases, and corrosion may
be generated excessively. Thus, the upper limit of the
concentration is favorably 5% by weight or less.
[0022] Examples of the complexing agent to be used can be at least
one selected from the group consisting of quinaldinic acid
(quinoline carboxylic acid), quinolinic acid (pyridine-2,
3-dicarboxylic acid), benzotriazole (BTA), nicotinic acid
(pyridine-3-dicarboxylic acid), picolinic acid, malonic acid,
oxalic acid, succinic acid, maleic acid, citric acid, glycine,
alanine, and aqueous ammonia.
[0023] A concentration of the complexing agent is favorably
approximately 0.01 to 1% by weight. In a case where the
concentration is less than 0.01% by weight, the organic complex is
not formed sufficiently. On the other hand, in a case where the
concentration is more than 1% by weight, the organic complex
becomes thick, and polishing speed is lowered.
[0024] Examples of the surfactant include ammonium dodecylbenzene
sulfonate, potassium dodecylbenzene sulfonate, polyvinyl
pyrrolidone, polyvinyl alcohol, ammonium polyacrylate, hydroxy
cellulose, acetylene diol-based nonion, and polyoxyethylene
alkylene ether. To form a hydrophilic film on the surface of the
organic complex, a concentration of the surfactant is desirably at
least 0.01% by weight or more. Further, to avoid solution of the
organic complex, the upper limit of the concentration is favorably
0.5% by weight.
[0025] The polishing apparatus 10 also includes the gas nozzle 27,
and the metal layer is polished while gas 33 is sprayed to the
polishing face 7a of the polishing pad 7. Examples of the gas 33
are compressed air and nitrogen.
[0026] A temperature of the polishing face 7a rises by frictional
heat or reaction heat generated between the wafer 20 and the
polishing face 7a, for example. It may facilitate a chemical
reaction on the surface of the metal layer, causing corrosion to be
generated easily. Hence, the temperature is lowered in the
embodiment by spraying the gas 33 to the polishing pad 7 in order
to restrict the generation of corrosion.
[0027] Next, a method for manufacturing a semiconductor device
according to the embodiment will be described with reference to
FIGS. 2A to 2D. FIGS. 2A to 2D are schematic cross-sectional views
showing a procedure for forming interconnects on a surface of the
wafer 20.
[0028] As shown in FIG. 2A, an insulating layer 43 is formed on a
silicon substrate 13 which include transistors and the like (not
shown) formed thereon, for example. The insulating layer 43 is a
silicon oxide film, for example. Interconnect grooves 41 are formed
in the insulating layer 43. The interconnect grooves 41 include a
contact hole 42 communicating with a contact area 17 formed in the
silicon substrate 13.
[0029] Subsequently, as shown in FIG. 2B, a barrier metal (BM)
layer 45 is formed, which is a first metal layer covering an upper
surface of the insulating layer 43 and inner surfaces of the
interconnect grooves 41. For the BM layer 45, titanium (Ti),
tantalum (Ta), or nitride of one of these is used, for example. The
BM layer 45 contacts the contact area 17 on the bottom surface of
the contact hole 42.
[0030] Subsequently, a second metal layer 47 (hereinafter, a metal
layer 47) is formed on the BM layer 45. The metal layer 47 is an
electrolytic plating layer of copper (Cu), for example, fills
insides of the interconnect grooves 41, and covers a surface of the
BM layer 45.
[0031] Subsequently, as shown in FIG. 2C, the metal layer 47 formed
on the BM layer 45 is removed using a CMP method (main polishing).
The metal layer 47 remains in the insides of the interconnect
grooves 41. At this time, gas is sprayed to the polishing pad 7 to
cool the polishing pad 7.
[0032] Subsequently, as shown in FIG. 2D, the BM layer 45 formed on
an upper surface of the insulating layer 43 is removed using the
CMP method (touch-up polishing). Thus, the BM layer 45 and the
metal layer 47 on the upper surface of the insulating layer 43 are
removed to form interconnects 49 each containing the metal layer 47
and the BM layer 45 in the inside of the interconnect groove
41.
[0033] Next, a polishing method according to the embodiment will be
described with reference to FIGS. 3A to 3B and FIGS. 4A to 4B.
FIGS. 3A to 3B and FIGS. 4A to 4B are partial cross-sectional views
schematically illustrating interconnect layers 40 to 60 provided on
a surface of the wafer 20. Meanwhile, in each of FIGS. 3A to 4B,
the wafer illustrated in FIGS. 2A to 2D is shown upside down for
the purpose of showing a polishing procedure.
[0034] FIG. 3A shows a polishing procedure of removing the metal
layer 47 formed on an upper surface of the interlayer insulating
film 43 and leaving the metal layer 47 in the interconnect grooves
41 formed in the interlayer insulating film 43.
[0035] As shown in FIG. 3A, in a final phase of the polishing
procedure, there is a case in which an organic complex 51 remaining
thinly on a polishing face of the interconnect layer 40 cannot be
scraped away completely by an inorganic particle 53 having a small
particle diameter and remains as a metal residuum. Since the
organic complex 51 remaining on the interconnect layer is
conductive, the organic complex 51 short-circuits adjacent
interconnects. Thus, a resin particle 57 having a large particle
diameter is added to the slurry 25 to scrape away the organic
complex 51, which cannot be removed by the inorganic particle 53.
Thereby, the amount of metal residues remaining on the surface of
the interconnect layer 40 is reduced.
[0036] FIG. 3B shows a polishing procedure in the interconnect
layer 50. The interlayer insulating film 43 has interconnect
grooves 41a and 41b having different widths. As shown in FIG. 3B,
in a case where the slurry 25 to which the resin particle 57 having
a large particle diameter has been added is used, the wider
interconnect groove 41a is polished more deeply than the narrower
interconnect groove 41b. Thus, a step d.sub.s of a metal face 63 of
the interconnect groove 41a is larger than a step of a metal face
65 of the interconnect groove 41b.
[0037] In this manner, adding the resin particle 57 enable
polishing to follow a structure of a foundation. For example, the
interconnect layer has unevenness reflecting a device structure of
a lower layer. When the metal layer 47 formed on the surface of the
interconnect layer is to be removed, the metal layer 47 is
desirably polished along a shape of the unevenness.
[0038] The interconnect layer 60 shown in FIG. 4A has on a surface
a recess 71. The metal layer 47 formed on the recess 71 is similar
to the metal layer 47 filled in a wide interconnect groove, and the
polishing amount is larger than that on a polishing face 75 of a
narrow interconnect groove 41c. Thus, for example, polishing on a
metal face 73 in the recess 71 progresses more, and the metal layer
47 can be removed along the recess 71 of the interconnect layer 60
as shown in FIG. 4B. As a result, the amount of residues of the
metal layer 47 remaining on the surface of the recess 71 can be
reduced, and short between interconnects can be prevented.
[0039] In this manner, by adding a resin particle having a large
particle diameter to the slurry, followability of the polishing
amount to a foundation can be improved.
[0040] Next, an example will be described with reference to FIGS.
5A to 5C, FIG. 6, and FIG. 7. In the example, a foamable pad
manufactured by Nitta Haas (IC1000) was used as a polishing
pad.
[0041] Components of slurry are as follows:
[0042] inorganic particle: colloidal silica (0.4% by weight,
average particle diameter: 30 nm),
[0043] resin particle: polystyrene particle (0.1% by weight,
average particle diameter: 200 nm, the resin particle has on a
surface a carboxylic group and a sulfonyl group),
[0044] oxidant: ammonium persulfate (1.5% by weight),
[0045] complexing agent: quinaldinic acid (0.1% by weight), BTA
(0.0001% by weight), alanine (0.4% by weight), ammonium
dodecylbenzene sulfonate (0.02% by weight), aqueous ammonia (0.2%
by weight),
[0046] surfactant: acetylene diol ethylene oxide adduct (HLB value:
18, 0.1% by weight),
[0047] pH adjuster: a moderate amount of potassium hydroxide (pH9),
and
[0048] rest: water.
[0049] As Comparative Example 1, an example of using slurry to
which the resin particle among the above components is not added is
shown. Further, as Comparative Example 2, an example of not
spraying gas to the polishing pad is shown.
[0050] FIGS. 5A to 5C are photos showing surfaces of interconnect
layers after polishing. FIG. 5A shows the surface after polishing
with the slurry not including the resin particle according to
Comparative Example 1. FIG. 5B shows the surface after polishing
according to Comparative Example 2, in which air is not sprayed to
the polishing pad. FIG. 5C shows the surface after polishing
according to the example.
[0051] On the surface in Comparative Example 1 shown in FIG. 5A,
multiple white metal residues are seen on a surface of the metal
layer 47 and on a surface of the interlayer insulating film 43
surrounding the metal layer 47. These are the organic complexes 51,
which show polishing is insufficient. That is, the organic
complexes are not removed completely since the slurry in
Comparative Example 1 does not include a resin particle.
[0052] Conversely, as shown in FIGS. 5B and 5C, no organic
complexes 51 remain on the surfaces after polishing in the example
and Comparative Example 2. Further, since no differences are seen
between the surfaces shown in FIGS. 5B and 5C, whether or not gas
is sprayed results in no differences in polishing force in a case
of using the slurry to which the resin particle is added.
[0053] FIG. 6 is a graph showing planarity of the metal layer 47
relative to a line width (width). Graph A shows a characteristic in
the example, and Graphs B and C show characteristics in Comparative
Examples 1 and 2, respectively. Line density is 50%.
[0054] Graph C shows a height of a step increases when a line width
exceeds 10 .mu.m. On the other hand, in Graph A, a height of a step
increases when a line width exceeds 30 .mu.m. This difference is
caused by whether or not air is sprayed to the polishing pad and
shows that polishing force is lowered by cooling the surface of the
polishing pad. Further, in Graph B, a height of a step increases
when a line width exceeds 50 .mu.m.
[0055] When Graph C is compared with Graph B, Graph C remarkably
shows an increase in the height of the step resulting from addition
of the resin particle to the slurry. That is, in Comparative
Example 2, followability to a foundation shape is drastically
improved by the effect of the resin particle. On the other hand, in
the example, it can be said that followability to a foundation
shape is greater than that in Comparative Example 1 although it is
inferior to that in Comparative Example 2.
[0056] In addition, experiments were carried out by changing a kind
of the resin particle. Table 1 shows results of Experiments 1 to 4
using PMMA (polymethyl methacrylate resin) and PST (polystyrene
resin) as the resin particle. .largecircle.-mark in the table shows
"no Cu residue," "no Cu corrosion," and "good foundation
followability." Here, "no Cu residue" and "no Cu corrosion" include
states in which generation of Cu film residues and Cu corrosion is
in a practically problem-free level although Cu film residues and
Cu corrosion are generated. .times.-mark shows "Cu residue
generated," "Cu corrosion generated," and "poor foundation
followability."
[0057] As shown in Table 1, foundation followability is good in any
of the resin particles. However, in a result of Experiment 1 using
PMMA, Cu residues and Cu corrosion are generated. In a case of
Experiment 2 using PST, good results are obtained in terms of Cu
residues, but Cu corrosion is generated. On the other hand, as
shown in a result of Experiment 3, even using PST generates Cu
residues in a case where the PST has a functional group of a
different kind of polarity as that of the inorganic particle.
Further, as shown in Experiment 4, generation of Cu residues is
improved when PST is added to PMMA.
[0058] In this manner, it is found that using a resin particle
having a functional group of a same kind of polarity as that of the
inorganic particle and containing PST can improve foundation
followability and reduce the amount of Cu residues.
TABLE-US-00001 TABLE 1 Resin Functional Cu Cu Foundation Experiment
particle group residue corrosion followability 1 PMMA Same X X
.largecircle. polarity 2 PST Same .largecircle. X .largecircle.
polarity 3 Different X X .largecircle. polarity 4 PMMA- Same
.largecircle. X .largecircle. PST polarity
[0059] Next, experiments were carried out by changing a particle
diameter and a mixing concentration of PST. The diameter of the
resin particle was set to 150 nm, 200 nm, and 500 nm, and the
mixing concentration in respective cases was changed in a range of
0.0001% by weight (wt %) to 0.1% by weight.
[0060] Table 2 shows results of the experiments. Here,
.smallcircle. and .times. show equal evaluations to those in Table
1, and .DELTA. show that preferable results of certain degree are
seen but are still insufficient.
TABLE-US-00002 TABLE 2 Particle Experi- diameter Concentration Cu
Cu Foundation ment (nm) (wt %) residue corrosion followability 5
150 0.0001 X .largecircle. X 6 0.001 X .DELTA. X 7 0.01 .DELTA. X
.DELTA. 8 0.1 .DELTA. X .DELTA. 9 200 0.0001 X .DELTA. X 10 0.001
.largecircle. .DELTA. .largecircle. 11 0.01 .largecircle. X
.largecircle. 12 0.1 .largecircle. X .largecircle. 13 500 0.0001 X
.DELTA. X 14 0.001 .largecircle. .DELTA. .largecircle. 15 0.01
.largecircle. X .largecircle. 16 0.1 .largecircle. X
.largecircle.
[0061] As shown in Table 2, in cases of using PST having a particle
diameter of 150 nm (Experiments 5 and 6), generation of Cu residues
and foundation followability are improved as the concentration of
the resin particle is raised but do not reach sufficient levels. On
the other hand, Cu corrosion is generated more significantly as the
concentration of the resin particle is raised. In cases of using
PST having particle diameters of 200 nm and 500 nm (Experiments 9
to 16), results of no Cu residues and good foundation followability
are obtained at a concentration of 0.001% by weight or more. On the
other hand, there is still a tendency toward more significant
generation of Cu corrosion along with rising of the
concentration.
[0062] It is apparent from these results that using the resin
particle containing PST having a particle diameter of 200 nm or
more and having a mixing concentration of 0.001% by weight or more
can achieve a state of no Cu residues and good foundation
followability. On the other hand, Cu corrosion is generated more
significantly as the concentration of the resin particle is
raised.
[0063] FIG. 7 is a graph for comparison of corrosion count
generated on the metal layer 47 after polishing. When a corrosion
count in Comparative Example 1 and a corrosion count in Comparative
Example 2 shown in FIG. 7 are compared, it is found that corrosion
is generated more significantly in the polishing method according
to Comparative Example 2, in which the resin particle is added. The
reason for this may be that, since polishing force is improved by
the slurry including the resin particle, the extent of exposure of
a copper surface not covered with the organic complex is great, and
a chemical reaction is accelerated.
[0064] On the other hand, in the example, regardless of use of the
slurry including the resin particle, a corrosion count is less than
that of Comparative Example 2 and is in an equal level to that of
Comparative Example 1. The reason for this may be that spraying air
for cooling the polishing pad restricts a chemical reaction on the
surface of the metal layer 47, suppressing the generation of
corrosion.
[0065] Table 3 shows results in cases of spraying air to the
polishing pad (500 L of compressed air/minute) under equal
conditions to those in Experiments 10 to 12 and 14 to 16, in which
a concentration of the resin particle is 0.001% by weight or
more.
TABLE-US-00003 TABLE 3 Particle Experi- diameter Concentration Cu
Cu Foundation ment (nm) (wt %) residue corrosion followability 10
200 0.001 .DELTA. .largecircle. .DELTA. 11 0.01 .largecircle.
.largecircle. .largecircle. 12 0.1 .largecircle. .largecircle.
.largecircle. 14 500 0.001 .DELTA. .largecircle. .DELTA. 15 0.01
.largecircle. .largecircle. .largecircle. 16 0.1 .largecircle.
.largecircle. .largecircle.
[0066] In the results in which the mixing concentration is 0.001%
by weight (Experiments 10 and 14), Cu residues remain, and
foundation followability is slightly worse. However, in cases of
higher concentrations, good results are obtained in terms of Cu
residue and foundation followability. Generation of Cu corrosion is
restricted in any of the concentrations of 0.001% by weight or
more.
[0067] According to the above results, using the slurry to which
the resin particle is added can improve polishing force and reduce
metal residues (organic complexes) remaining on the surface of the
interconnect layer. The above results also show followability to a
foundation shape can be improved. However, improvement in polishing
force by addition of the resin particle causes a disadvantage of
easy generation of corrosion. The cooling method of spraying gas to
the polishing pad is effective to alleviate this conflicting
relation. In other words, by adding the resin particle to the
slurry and performing polishing while spraying gas to the polishing
pad, a polishing method in which the amount of metal residues is
reduced (clearness of metal residues), foundation followability is
improved, and generation of corrosion is restricted can be
achieved.
[0068] Further, to improve clearness of metal residues and
foundation followability, a resin particle having an average
particle diameter of 200 nm or more is desirably added to the
slurry. Further, the average particle diameter of the resin
particle is desirably 1 .mu.m or less. When the average particle
diameter exceeds 1 .mu.m, sedimentation occurs, which makes it
difficult to disperse the resin particles in the slurry
uniformly.
[0069] Furthermore, a concentration of the resin particle is
desirably 0.001% by weight or more and 0.1% by weight or less. When
the concentration of the resin particle is below 0.001% by weight,
clearness of metal residues and foundation followability are
degraded. On the other hand, when the concentration exceeds 0.1% by
weight, polishing force is excessive, and corrosion is generated
significantly.
[0070] As described above, the embodiment achieves a polishing
method in which generation of corrosion on the surface of the metal
layer is restricted, and clearness of metal residues and foundation
followability are improved. In a procedure of manufacturing a
semiconductor device with use of this polishing method, generation
of short-circuit between interconnects is suppressed, and
manufacturing yield can be improved.
[0071] Although the above example has been described taking CMP of
a Cu layer using slurry to which a resin particle is added as an
example, the embodiment is not limited to this. For example, the
embodiment can be applied to a procedure for forming aluminum
interconnect. Further, a method for cooling a polishing pad is not
limited to spraying gas, but it may be possible to supply cooled
slurry, for example.
[0072] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
invention.
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