Polishing pad and preparing method of semiconductor device using the same

A polishing pad comprising:

• a polishing layer,
• wherein the polishing layer includes:
• a polishing variable layer having a 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 constant layer includes a cured product of a first composition including a first urethane-based prepolymer, and the polishing variable layer includes a cured product of a second composition including a second urethane-based prepolymer,
• wherein the first urethane-based prepolymer is a reaction product of a first alcohol component including a first polyol having a hydroxyl value (Hydroxyl number, OH-Value) of about 200 mgKOH/g to about 900 mgKOH/g, a first curing agent, and a first isocyanate component,
• wherein the second urethane-based prepolymer is a reaction product of a second alcohol component including a second polyol having a hydroxyl value (Hydroxyl number, OH-Value) of 50 mgKOH/g or more and less than 200 mgKOH/g, a second curing agent, and a second isocyanate component,
• wherein the first curing agent includes a compound having a hydroxyl group (—OH) as a reactive group, and the second curing agent includes a compound having an amine group (—NH2) as a reactive group, and
• wherein a content of isocyanate group (—NCO) in the first composition is greater than a content of isocyanate group (—NCO) in the second composition.