PATTERN DEPENDENT POLISH RATE BEHAVIOR IN OXIDE CHEMICAL MECHANICAL POLISHING

摘要

We have observed that the polish rate behavior of oxide thickness monitor structures exhibits a strong dependence on the overall pattern density of the die. In order to fully exploit this in a pilot wafer polish time estimation system, we have evaluated two models for the polish rate behavior. One is a phenomenological fit to the data based on an initial parabolic removal regime transitioning to linear removal after planarization is achieved. The other is a physical model based on the elastic properties of the polish pad. The benefits and limitations of the models are discussed.