Polishing pad and method of fabricating semiconductor device using the same
Provided is a polishing pad including a polishing layer, wherein the nuclear magnetic resonance (NMR) 13 C spectrum of a processed composition prepared by adding 1 g of the polishing layer to a 0.3 M aqueous solution of potassium hydroxide (KOH) and allowing the mixture to react in a closed container at a temperature of 150° C. for 48 hours includes a first peak appearing at 15 ppm to 18 ppm, a second peak appearing at 9 ppm to 11 ppm, a third peak appearing at 138 ppm to 143 ppm, and a fourth peak appearing at 55 ppm to 65 ppm, and the softening control index calculated by Equation 1 is 0.10 to 0.45. The polishing pad includes the polishing layer having physical properties corresponding to the softening control index, and thus may exhibit a removal rate and defect prevention performance within desired ranges in polishing of a polishing target.
1. A polishing pad comprising a polishing layer, wherein a nuclear magnetic resonance (NMR) 13 C spectrum of a processed composition prepared by adding 1 g of the polishing layer to a 0.3 M aqueous solution of potassium hydroxide (KOH) and allowing the mixture to react in a closed container at a temperature of 150° C. for 48 hours includes a first peak appearing at 15 ppm to 18 ppm, a second peak appearing at 9 ppm to 11 ppm, a third peak appearing at 138 ppm to 143 ppm, and a fourth peak appearing at 55 ppm to 65 ppm, and
a softening control index calculated by Equation 1 below is 0.10 to 0.45,
wherein, the polishing layer comprises a cured product of a preliminary composition containing a urethane-based prepolymer,
wherein, the preliminary composition contains a reaction product of an isocyanate compound and a polyol compound, and
the isocyanate compound includes an aromatic diisocyanate and an alicyclic diisocyanate compound, and
the alicyclic diisocyanate compound is 5 parts by weight to 30 parts by weight based on 100 parts by weight of the aromatic diisocyanate,
Softening
control
index
=
I
4
100
+
I
2
+
I
3
[
Equation
1
]
wherein I2 is a ratio of the area of the second peak to the area of the first peak which is taken as 100.00, I3 is a ratio of the area of the third peak to the area of the first peak which is taken as 100.00, and I4 is a ratio of the area of the fourth peak to the area of the first peak which is taken as 100.00.
2. The polishing pad of claim 1 , wherein
a percentage of the area of the fourth peak relative to a total area of the first peak and the second peak is 30% to 75%, and
a percentage of the total area of the first peak and the second peak relative to a total area of the first peak, the second peak and the third peak is 60% to 70%.
3. The polishing pad of claim 1 , wherein
an area ratio of the third peak to the second peak is 1:1 to 5:1.
4. The polishing pad of claim 1 , wherein
an area ratio of the first peak to the second peak is 10:1 to 10:5.
5. The polishing pad of claim 1 , wherein
the polishing layer has a value of 1 to 2 as calculated according to Equation 2 below:
Mw
-
Mn
Mp
-
Mn
[
Equation
2
]
wherein Mw, Mn and Mp are molecular weights measured by gel permeation chromatography (GPC) for a depolymerized composition prepared by adding 1 g of the polishing layer to 15 ml of a 0.3 M aqueous solution of KOH and depolymerizing the polishing layer in a closed container at 150° C. for 48 hours,
Mw is the weight-average molecular weight of the depolymerized composition,
Mn is the number-average molecular weight of the depolymerized composition, and
Mp is the peak molecular weight of the depolymerized composition.
6. The polishing pad of claim 5 , wherein
the weight-average molecular weight (Mw) is 2,600 to 4,000, and
the number-average molecular weight (Mn) is 2,500 to 3,000.
7. The polishing pad of claim 1 , wherein,
a nuclear magnetic resonance (NMR) 13 C spectrum of the preliminary composition shows a fifth peak and a sixth peak in descending order of peak position (ppm) at 16 ppm to 20 ppm, and
an area ratio of the fifth peak to the sixth peak is 1:1 to 5:1.
8. The polishing pad of claim 7 , wherein,
an isocyanate group content of the preliminary composition is 5 wt % to 11 wt %,
and
the polyol compound comprises a low-molecular-weight polyol having a weight-average molecular weight (Mw) of about 100 g/mol to less than about 300 g/mol and a high-molecular-weight polyol having a weight-average molecular weight (Mw) of about 300 g/mol to about 1,800 g/mol.
9. The polishing pad of claim 7 , wherein
the aromatic isocyanate compound comprises 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI), and
the preliminary composition contains a urethane-based prepolymer comprising at least one of a first unit structure derived from 2,4-TDI subjected to urethane reaction at one end, and a second unit structure derived from 2,6-TDI subjected to urethane reaction at one end, and a third unit structure derived from 2,4-TDI subjected to urethane reaction at both ends, and further contains 2,6-TDI remaining unreacted at both ends.
10. The polishing pad of claim 1 , wherein the polishing layer has a tensile strength of 20 to 25 N/mm 2 and an elongation of 90 to 130%.