Polishing pad, process for preparing the same, and process for preparing a semiconductor device using the same
Embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors, a process for preparing the same, and a process for preparing a semiconductor device using the same. In the polishing pad according to the embodiment, the size (or diameter) and distribution of a plurality of pores are adjusted, whereby the polishing performance such as polishing rate and within-wafer non-uniformity can be further enhanced.
1. A polishing pad, which comprises a polishing layer comprising a plurality of pores,
wherein, in a diameter distribution of the plurality of pores, a number average diameter (Da) of the plurality of pores, defined as an average value obtained by dividing a sum of diameters of the plurality of pores by a number of the pores, ranges from 15 μm to 50 μm, and
an area ratio, defined as a percentage of an area (Au) of pores having a diameter at least 200% greater than the number average diameter of the plurality of pores to a total area of the polishing surface ranges from 0.9% to less than 12%,
wherein a diameter (Du) of pores having the diameter at least 200% greater than the number average diameter of the plurality of pores is 100 μm or more.
2. The polishing pad of claim 1 , wherein a total area ratio of the plurality of pores, defined as a percentage of a total area of the plurality of pores to the total area of the polishing surface, ranges from 30% to 55%.
3. The polishing pad of claim 1 , wherein a pore diameter at a maximum peak in the diameter distribution of the plurality of pores ranges from 60 μm to 150 μm.
4. The polishing pad of claim 1 , wherein, when polishing a substrate having a tungsten layer and an oxide layer with a polishing rate ranging from 610 Å/min to 900 Å/min for the tungsten layer and, a polishing rate ranging from 2,860 Å/min to 3,250 Å/min for the oxide layer, the polishing of the substrate occurs with a within-wafer non-uniformity of less than 10% for the tungsten layer, and a within-wafer non-uniformity of less than 12% for the oxide layer.
5. The polishing pad of claim 1 , wherein the polishing layer comprises a cured product of a composition comprising a urethane-based prepolymer, a curing agent, and a solid phase foaming agent, and the solid phase foaming agent has a D50 ranging from 20 μm to 50 μm, wherein D50 is a volume fraction of a 50th percentile of a particle diameter distribution.
6. The polishing pad of claim 5 , wherein the solid phase foaming agent is a fine hollow particle having a shell, and the glass transition temperature (Tg) of the shell is 70° C. to 110° C.