Polishing pad, method for producing the same and method of fabricating semiconductor device using the same
The present invention relates to a polishing pad, a method for producing the same, and a method of fabricating a semiconductor device using the same. According to the present invention, it is possible to prevent defects from occurring due to an inorganic component contained in a polishing layer during a polishing process, by limiting the content range of the inorganic component contained in the polishing layer. In addition, an unexpanded solid foaming agent is contained in a polishing composition for producing a polishing layer and is expanded during a curing process to form a plurality of uniform pores in the polishing layer, and the content range of the inorganic component contained in the polishing layer, thereby preventing defects from occurring during the polishing process.
1 . A polishing pad comprising a polishing layer,
wherein the polishing layer comprises a cured product of a prepolymer composition containing a polyurethane-based prepolymer,
wherein the polyurethane-based prepolymer has a weight-average molecular weight (Mw) of about 500 g/mol to about 3,000 g/mol,
wherein a viscosity of the prepolymer composition is from 100 cps to 1,000 cps at 80° C.,
wherein the polishing layer contains: a plurality of micropores each having a shell; and an inorganic component,
wherein the shell is derived from an expandable solid foaming agent,
wherein the micropores have a value of 0.7 to 0.8 as calculated according to the following ratio:
D
10
D
50
wherein
D10 represents a diameter of pores in a 10% volume cumulative distribution, and
D50 represents a diameter of pores in a 50% volume cumulative distribution,
wherein the micropores have a standard deviation of 4 to 10 for measured values of D10 to D100, and
wherein the inorganic component is Mg and is contained in an amount of 0.01 to 1 ppm based on the total weight of the polishing layer.
2 . The polishing pad of claim 1 , wherein the polishing layer satisfies the following equation:
0
≤
DS
×
D
Mg
RR
≤
1.5
wherein
DS represents the number of defects and scratches, measured after performing a polishing process on a silicon oxide layer using a CMP polishing apparatus under a polishing load of 4.0 psi for 60 seconds while injecting a calcined ceria slurry at a rate of 250 ml/min and rotating a surface plate having the polishing pad attached thereto at a rotating speed of 150 rpm;
RR represents a removal rate (A/min) of the silicon oxide layer during the polishing process;
DMg is a content (ppm) of Mg based on the total weight of the polishing layer; and
DS×DMg/RR is a ratio between values excluding units.
3 . The polishing pad of claim 1 , wherein a D50 of the micropores is 15 μm to 40 μm.
4 . The polishing pad of claim 1 , wherein the expandable solid foaming agent has a pH of 8 or less.
5 . The polishing pad of claim 1 , wherein the expandable solid foaming agent has a particle diameter of 9 μm to 24 μm before foaming.
6 . The polishing pad of claim 1 , wherein the expandable solid foaming agent comprises magnesium hydroxide (Mg(OH) 2 ).
7 . The polishing pad of claim 1 , wherein an expansion start temperature of the expandable solid foaming agent is 80° C. to 120° C.
8 . The polishing pad of claim 1 , wherein the expandable solid foaming agent is thermally expanded, and the thermally expanded solid foaming agent has a particle size of 5 μm to 100 μm.
9 . The polishing pad of claim 1 , wherein the shell comprises at least one selected from the group consisting of a vinylidene chloride-based copolymer, an acrylonitrile-based copolymer, a methacrylonitrile-based copolymer, and an acrylic copolymer.
10 . The polishing pad of claim 1 , wherein, when a polishing process is performed on a silicon oxide layer using a CMP polishing apparatus under a polishing load of 4.0 psi for 60 seconds while injecting a calcined ceria slurry at a rate of 250 ml/min and rotating a surface plate having the polishing pad attached thereto at a rotating speed of 150 rpm, a removal rate of the silicon oxide layer by the polishing process is 2,000 to 4,000 Å/min.
11 . The polishing pad of claim 1 , wherein the polishing pad exhibits a cut rate of 20 μm/hr or less, which is a change in thickness during a process in which the polishing pad is conditioned under a pressure of 6 lbf at a rotating speed of 100 to 110 rpm for 1 hour while deionized water is sprayed thereto for 1 hour after the polishing pad is initially pre-conditioned with deionized water for 10 minutes.