Macromodel for changes in polishing pad surface condition caused by dressing and polishing

A macromodel for changes in a pad surface by dressing and polishing is proposed. A polishing pad is divided into small areas and it is assumed that each area takes an “H” (= high) or “L” (= low) condition. The condition is changed by dressing or polishing, and the total chemical mechanical planarization (CMP) performance is determined by the average pad condition. The results from equations are compared with experimental data, and good correspondence is confirmed. Various CMP behaviors are well explained by the equations, such as polishing rate stabilization by dummy running, the differences in the stability time and polishing rate between in situ dressing and ex situ dressing, and polishing rate behaviors for patterned wafers. This new model can be used to predict process performances, to optimize process conditions, or to indicate the direction of consumable development.