POLISHING PAD WITH REDUCED DEFECT AND METHOD OF PREPARING A SEMICONDUCTOR DEVICE USING THE SAME
In the polishing pad according to an embodiment, the particle size of debris obtained during conditioning and the zeta potential of a debris solution are adjusted to specific ranges. As a result, it is possible to minimize the occurrence of defects and scratches during a CMP process while reducing the size of debris, thereby maintaining excellent physical properties and performance of the polishing pad.
1 . A polishing pad, which comprises a polishing layer, wherein the polishing layer comprises a urethane-based prepolymer, a foaming agent, and a curing agent; when the polishing layer is conditioned for 10 minutes while deionized water is supplied at 300 cc/minute under the conditions of a platen speed of 93 rpm, a conditioner load of 9 lbs, a conditioner speed of 64 rpm, and a sweep of 19 times/minute, the D50 particle size of the debris obtained is 50 μm or less at a pH of 5.5; and the zeta potential of an aqueous solution containing the debris at a concentration of 0.01% by weight is −20 mV to 30 mV at a pH of 5.5.
2 . The polishing pad of claim 1 , wherein the D50 particle size of the debris obtained during conditioning of the polishing layer is 25 μm or less at a pH of 5.5 and 22.3 μm or less at a pH of 10.
3 . The polishing pad of claim 1 , wherein the zeta potential of an aqueous solution containing debris obtained when the polishing layer is conditioned for 10 minutes at a concentration of 0.01% by weight is −50 mV to −10 mV at a pH of 10.
4 . The polishing pad of claim 1 , wherein the value of the following Equation (1) is −10 μm/mV to 20 μm/mV:
D
50
[
5.5
]
/
Zp
[
5
.5
]
(
1
)
wherein D50 [5.5] is the D50 particle size (μm) of debris obtained during conditioning of the polishing layer at a pH of 5.5, and Zp [5.5] is the zeta potential (mV) of an aqueous solution containing debris obtained during conditioning of the polishing layer at a concentration of 0.01% by weight at a pH of 5.5.
5 . The polishing pad of claim 1 , wherein the value of the following Equation (2) is 70% to 110%:
(
D
50
[
5.5
]
/
D
50
[
10
]
)
×
100
(
2
)
wherein D50 [5.5] is the D50 particle size (μm) of debris obtained during conditioning of the polishing layer at a pH of 5.5, and D50 is the D50 particle size (μm) of debris obtained during conditioning of the polishing layer at a pH of 10.
6 . The polishing pad of claim 1 , wherein the value of the following Equation (3) is 35.5 mV to 60 mV:
Z
p
[
5
.
5
]
-
Zp
[
10
]
(
3
)
wherein Zp [5.5] is the zeta potential (mV) of an aqueous solution containing debris obtained during conditioning of the polishing layer at a concentration of 0.01% by weight at a pH of 5.5, and Zp is the zeta potential (mV) of an aqueous solution containing debris obtained during conditioning of the polishing layer at a concentration of 0.01% by weight at a pH of 10.
7 . The polishing pad of claim 1 , wherein the foaming agent comprises a solid phase foaming agent, and the solid phase foaming agent comprises at least one selected from the group consisting of an acrylonitrile-based copolymer, a methyl methacrylate-based copolymer, a methacrylonitrile-based copolymer, and an acrylic-based copolymer, and
wherein the curing agent comprises at least one selected from the group consisting of diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 1,3-propanediol bis(4-aminobenzoate) (PDPAB), N,N′-bis(sec-butylamino) diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-benzenediamine, 4-(4-aminobenzoyl)oxyphenyl 4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl 4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy] butyl 4-aminobenzoate, and methylene bis-methylanthranilate (MBNA).
8 . The polishing pad of claim 1 , wherein the polishing layer has a hardness of 50 Shore D to 65 Shore D, a tensile strength of 15 N/mm 2 to 25 N/mm 2 , and an elongation of 90% to 130%.
9 . The polishing pad of claim 1 , wherein, when the silicon oxide layer of a silicon wafer is polished with a ceria slurry using the polishing pad, the polishing rate according to the following Mathematical Equation 1 is 2,200 Å/minute to 2,600 Å/minute:
Polishing
rate
(
Å
/
minute
)
=
difference
in
thickness
before
and
after
polishing
(
Å
)
/
polishing
time
(
minute
)
.
[
Mathematical
Equation
1
]
10 . A polishing pad, which comprises a polishing layer comprising a polyurethane resin, wherein, when the polishing layer is conditioned while a ceria slurry is supplied at 250 ml/minute under the conditions of a platen speed of 93 rpm, a conditioner load of 9 lbs, a conditioner speed of 64 rpm, and a sweep of 19 times/minute, followed by irradiation with UV light with a wavelength of 100 nm to 380 nm at an intensity of 1 kW from a distance of 5 cm, the debris obtained satisfies the following Relationship (1):
D
50
[
0
min
]
>
D
50
[
4
min
]
(
1
)
wherein D50 [0 min] is the D50 particle size of the debris obtained in the conditioning before the irradiation with UV light, and D50 [4 min] is the D50 particle size of the debris obtained upon the irradiation with UV light for 4 minutes after the conditioning.
11 . The polishing pad of claim 10 , wherein ΔD50 [0-4 min] calculated according to the following equation is 10 μm or more:
Δ
D
5
0
[
0
-
4
min
]
=
D
5
0
[
0
min
]
-
D
5
0
[
4
min
]
wherein D50 [0 min] is the D50 particle size of the debris obtained in the conditioning before the irradiation with UV light, and D50 [4 min] is the D50 particle size of the debris obtained upon the irradiation with UV light for 4 minutes after the conditioning.
12 . The polishing pad of claim 10 , wherein D50 [4 min] is 30 μm or less.
13 . The polishing pad of claim 10 , wherein the polishing pad satisfies the following Relationship (2):
D
50
[
4
min
]
<
D
50
[
8
min
]
(
2
)
wherein D50 [4 min] is the D50 particle size of the debris obtained upon the irradiation with UV light for 4 minutes after the conditioning, and D50 [8 min] is the D50 particle size of the debris obtained upon the irradiation with UV light for 8 minutes after the conditioning.
14 . The polishing pad of claim 10 , wherein the polishing pad satisfies the following Relationship (3):
(
D
90
[
0
min
]
-
D
1
0
[
0
min
]
)
>
(
D
90
[
4
min
]
-
D
1
0
[
4
min
]
)
(
3
)
wherein D10 [0 min] and D90 [0 min] are each the D10 and D90 particle sizes of the debris obtained in the conditioning before the irradiation with UV light, and D10 [4 min] and D90 [4 min] are each the D10 and D90 particle sizes of the debris obtained upon the irradiation with UV light for 4 minutes after the conditioning.
15 . The polishing pad of claim 10 , wherein the polyurethane resin is formed from a composition comprising a urethane-based prepolymer, a foaming agent, and a curing agent, and the urethane-based prepolymer is prepared by reacting an isocyanate compound with a polyol,
wherein the foaming agent comprises a solid phase foaming agent, and the solid phase foaming agent comprises at least one selected from the group consisting of an acrylonitrile-based copolymer, a methyl methacrylate-based copolymer, a methacrylonitrile-based copolymer, and an acrylic-based copolymer, and
the curing agent comprises at least one selected from the group consisting of diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 1,3-propanediol bis(4-aminobenzoate) (PDPAB), N,N′-bis(sec-butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-benzenediamine, 4-(4-aminobenzoyl)oxyphenyl 4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl 4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl 4-aminobenzoate, and methylene bis-methylanthranilate (MBNA).
16 . The polishing pad of claim 10 , wherein the polishing layer has a hardness of 50 Shore D to 65 Shore D, a tensile strength of 15 N/mm 2 to 25 N/mm 2 , and an elongation of 90% to 130%.
17 . The polishing pad of claim 10 , wherein, when the silicon oxide layer of a silicon wafer is polished with a ceria slurry using the polishing pad, while irradiated with UV light with a wavelength of 100 nm to 380 nm at an intensity of 1 kW from a distance of 5 cm, the polishing rate according to the following Mathematical Equation 1 is 1,800 Å/minute to 2,200 Å/minute:
Polishing
rate
(
Å
/
minute
)
=
difference
in
thickness
before
and
after
polishing
(
Å
)
/
polishing
time
(
minute
)
.
[
Mathematical
Equation
1
]
18 . The polishing pad of claim 10 , wherein, when the polishing pad is tested at a conditioning pressure of 6 lbf and a rotation speed of 100 to 110 rpm, the pad wear rate (PWR) is 15 μm/hr to 40 μm/hr.
19 . A process for preparing a semiconductor device, which comprises polishing the surface of a semiconductor substrate using the polishing pad of claim 1 .
20 . A process for preparing a semiconductor device, which comprises conditioning the polishing layer of the polishing pad with irradiation of UV light with a wavelength of 100 nm to 380 nm while chemically and mechanically polishing a semiconductor substrate using the polishing pad of claim 10 .