US Patent 7300340 CMP pad having overlaid constant area spiral grooves

A circular chemical mechanical polishing pad that includes a polishing surface having a concentrically located origin. The polishing surface includes groove sets each containing grooves arranged in a pattern in which ones of the grooves in one groove set cross ones of the grooves in another set. The grooves in each groove set are configured and arranged so that the fraction of the polishing surface that is grooved, as measured along any circle that is concentric with the origin and crosses the grooves, is substantially constant, i.e., within about 25% of its average.