CUSHION FOR POLISHING PAD AND POLISHING PAD USING THE CUSHION
The present invention provides a polishing pad that is excellent in flatness of a surface to be polished and evenness of a film thickness after polishing and also excellent in a polishing rate, and can achieve excellent polishing in polishing uniformity of a material to be polished such as a insulating film, a metallic film, etc., and a cushion used for the polishing pad. A cushion for a polishing pad, wherein, when a dynamic compression viscoelasticity measurement is performed under conditions of 23°C, a static load of 27.6 kPa, a frequency of 11 Hz and an amplitude of 1 µm, (1) a phase difference between dynamic stress and deformation is 4° or less, and (2) a ratio of the maximum value of the deformation amount to the maximum value of the dynamic stress ([maximum value of deformation amount]/[maximum value of dynamic stress]) is 0.5 µm/kPa or more, and a polishing pad having a layer of the cushion for the polishing pad and a polishing layer, and a polishing pad having a layer of the cushion for a polishing pad and a polishing layer.