Polishing pad and preparing method of semiconductor device using the same

A method for preparing a semiconductor device, the method comprising:

• providing a polishing pad on a surface plate, the polishing pad including a polishing layer having a polishing surface;
• and
• polishing a polishing object while rotating the polishing pad and the polishing object relative to each other under a pressure condition after arranging a polished surface of the polishing object to be in contact with the polishing surface,
• wherein the polishing layer includes a polishing variable layer having the polishing surface, and a polishing constant layer disposed on a rear surface side of the polishing variable layer opposite to the polishing surface,
• wherein the polishing variable layer refers to a region of which physical and/or chemical characteristics change during a polishing process using the polishing pad,
• wherein the polishing constant layer refers to a region of which physical and/or chemical characteristics do not change during a polishing process using the polishing pad,
• wherein an interface between the polishing variable layer and the polishing constant layer is a separable interface,
• wherein a ratio of shore D hardness of the polishing variable layer and shore D hardness of the polishing constant layer is from 0.50 to 1.50,
• wherein the polishing variable layer is from 30% to 60% by volume of a total volume of the polishing layer, and
• wherein a first polishing variability index of the polishing variable layer according to Equation 1 below is from 0.1 to 11.0:
• (
• Ri
• -
• Rf
• )
• ·
• Ti
• (
• Ti
• -
• Tf
• )
• ·
• Ri
• [
• Equation
• ⁢
• 1
• ]
• wherein Ri is a surface roughness (Ra) of the polishing surface at a lifespan introduction time of the polishing variable layer, Rf is a surface roughness (Ra) of the polishing surface at a lifespan end time of the polishing variable layer, Ti is a total thickness of the polishing pad at the lifespan introduction time of the polishing variable layer, and Tf is the total thickness of the polishing pad at the lifespan end time of the polishing variable layer.