A Novel Method to Quantify Conditioner-to-Conditioner Variation and Predict Conditioner Lifetime and Process Failure Mode in Chemical Mechanical Planarization (CMP) Environment

In this study, we have developed a method to quantify inherent conditioner-to-conditioner variation using a mathematical model. Quantification of the lifetime of pad and conditioner in a chemical mechanical planarization (CMP) process using the model is also elucidated. Three conditioner types are selected based on their aggressiveness, and conditioning experiments are performed with five different conditioners of the same type to quantify the variation. Assuming exponential decay equation for pad wear rate (PWR), a simple model is developed and the model parameters, K and λ, are derived in numeric form. K, a measure of conditioner aggressiveness, can be used as a metric to assess conditioner-to-conditioner variation, while λ is a measure of conditioner lifetime. K and λ values are also used to predict the failure mode of a CMP process (conditioner or pad failure mode). Pad groove depth and PWR curves of five different conditioners of the same type as a function of time are plotted along with upper and lower limits. The limiting factor (low PWR due to conditioner decay or excess pad removal) is identified to predict the failure mode. An example for each failure mode (A122 and 8031C1 conditioners for conditioner and pad failure modes, respectively) is presented.