Porous polishing pad and process for producing the same all fees
Embodiments relate to a porous polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors and a process for preparing the same. According to the embodiments, the size and distribution of the plurality of pores contained in the porous polishing pad can be adjusted in light of the volume thereof. Thus, the plurality of pores have an apparent volume-weighted average pore diameter in a specific range, thereby providing a porous polishing pad that is excellent in such physical properties as polishing rate and the like.
1. A porous polishing pad, which comprises a urethane-based resin; and a plurality of pores,
wherein the plurality of pores have an apparent volume-weighted average pore diameter (AVWAPD) of 20 μm to 50 μm as calculated according to the following Equation 1:
Σ
(
diameter
of
pores
×
apparent
volume
of
pores
)
total
apparent
volume
of
pores
[
Equation
1
]
and wherein when the AVWAPD is X,
the plurality of pores comprises first pores having a diameter of greater than 0 μm to X μm and second pores having a diameter of greater than X μm, and
the total apparent volume of the first pores is greater than the total apparent volume of the second pores.
2. The porous polishing pad of claim 1 , wherein the AVWAPD is 30 μm to 45 μm.
3. The porous polishing pad of claim 1 , wherein the total apparent volume of the first pores is 55% by volume to 90% by volume based on the total apparent volume of the plurality of pores, and
the total apparent volume of the second pores is 10% by volume to 45% by volume based on the total apparent volume of the plurality of pores.
4. The porous polishing pad of claim 1 , wherein the first pores comprise first group of first pores having a diameter of greater than 0 μm to X−20 μm; second group of first pores having a diameter of greater than X−20 μm to X−10 μm; and third group of first pores having a diameter of greater than X−10 μm to X μm,
the total apparent volume of the first group of first pores is 5% by volume to 10% by volume based on the total apparent volume of the plurality of pores,
the total apparent volume of the second group of first pores is 15% by volume to 25% by volume based on the total apparent volume of the plurality of pores, and
the total apparent volume of the third group of first pores is 30% by volume to 45% by volume based on the total apparent volume of the plurality of pores.
5. The porous polishing pad of claim 1 , wherein the second pores comprise first group of second pores having a diameter of greater than X μm to X+10 μm; and second group of second pores having a diameter of greater than X+10 μm,
the total apparent volume of the first group of second pores is 5% by volume to 20% by volume based on the total apparent volume of the plurality of pores, and
the total apparent volume of the second group of second pores is 5% by volume to 25% by volume based on the total apparent volume of the plurality of pores.
6. The porous polishing pad of claim 1 , wherein the plurality of pores are derived from a solid phase foaming agent.
7. The porous polishing pad of claim 6 , wherein the solid phase foaming agent is a mixture of at least three solid phase foaming agents that have different particle diameter distributions.
8. The porous polishing pad of claim 7 , wherein the mixture of solid phase foaming agents comprises a first solid phase foaming agent;
a second solid phase foaming agent having a D50 greater than the D50 of the first solid phase foaming agent; and
a third solid phase foaming agent having a D50 greater than the D50 of the second solid phase foaming agent.
9. The porous polishing pad of claim 7 , wherein the mixture of solid phase foaming agents comprises the first solid phase foaming agent having a D50 of 5 μm to less than 20 μm,
the second solid phase foaming agent having a D50 of 10 μm to 30 μm, and
the third solid phase foaming agent having a D50 of 15 μm to 60 μm.
10. The porous polishing pad of claim 8 , wherein the mixture of solid phase foaming agents comprises 10% by weight to 40% by weight of the first solid phase foaming agent,
10% by weight to 30% by weight of the second solid phase foaming agent, and
30% by weight to 80% by weight of the third solid phase foaming agent, based on the total weight of the mixture of solid phase foaming agents.
11. The porous polishing pad of claim 1 , which has a total number of pores of 600 or more per unit area (mm 2 ) of the porous polishing pad.
12. The porous polishing pad of claim 1 , which has an average polishing rate (Å/min) of 3,100 or more as calculated by the following Equation 2 when a silicon wafer having a silicon oxide film is polished with a silica slurry:
Polishing rate=polished thickness of a silicon wafer (Å)/polishing time (minute) [Equation 2]
.
13. The porous polishing pad of claim 1 , which has an elastic modulus of 60 kgf/cm 2 or more.
14. The porous polishing pad of claim 1 , which has a withstand voltage of 14 kV to 23 kV,
a thickness of 1.5 mm to 2.5 mm,
a specific gravity of 0.7 g/cm 3 to 0.9 g/cm 3 ,
a surface hardness at 25° C. of 50 to 65 Shore D,
a tensile strength of 15 to 25 N/mm 2 , and
an elongation of 80% to 250%.
15. The porous polishing pad of claim 9 , wherein the mixture of solid phase foaming agents comprises 10% by weight to 40% by weight of the first solid phase foaming agent,
10% by weight to 30% by weight of the second solid phase foaming agent, and
30% by weight to 80% by weight of the third solid phase foaming agent, based on the total weight of the mixture of solid phase foaming agents.
16. A process for preparing the porous polishing pad of claim 1 , which comprises preparing a mixture of solid phase foaming agents by mixing at least three solid phase foaming agents that have different particle diameter distributions;
preparing a raw material mixture by mixing a urethane-based prepolymer, the mixture of solid phase foaming agents, and a curing agent; and
injecting the raw material mixture into a mold and molding it.
17. The process for preparing a porous polishing pad of claim 16 , wherein the raw material mixture comprises 0.5 part by weight to 10 parts by weight of the mixture of solid phase foaming agents per 100 parts by weight of the urethane-based prepolymer.
18. The process for preparing a porous polishing pad of claim 16 , wherein the mixture of solid phase foaming agents comprises a first solid phase foaming agent;
a second solid phase foaming agent having a D50 greater than the D50 of the first solid phase foaming agent; and
a third solid phase foaming agent having a D50 greater than the D50 of the second solid phase foaming agent.
19. The process for preparing a porous polishing pad of claim 18 ,
wherein the first solid phase foaming agent has a D50 of 5 μm to less than 20 μm,
the second solid phase foaming agent has a D50 of 10 μm to 30 μm, and
the third solid phase foaming agent has a D50 of 15 μm to 60 μm.
20. The process for preparing a porous polishing pad of claim 18 ,
wherein the mixture of solid phase foaming agents comprises 10% by weight to 40% by weight of the first solid phase foaming agent,
10% by weight to 30% by weight of the second solid phase foaming agent, and
30% by weight to 80% by weight of the third solid phase foaming agent, based on the total weight of the mixture of solid phase foaming agents.