Flexible Fiber Conditioner for Fine Conditioning of Polishing Pad and its Evaluation in Chemical Mechanical Polishing: Verification of SUS-FFC on Soft Urethane Foam Pad and Proposal of PEEK-FFC

Abstract

Polishing pad conditioning is essential for achieving stable chemical mechanical polishing (CMP). While diamond disk conditioners (DDCs) are often applied, flexible fiber conditioners (FFCs) have been proposed as a new conditioning tool. FFCs are intended for roughening the pad surface appropriately by bundling fine wire fibers. Our previous study demonstrated the fine conditioning characteristics of FFCs for a hard urethane foam pad. In this study, the conditioning characteristics of an FFC are compared with those of a DDC. First, we evaluate the conditioning performance of an FFC using SUS fibers on a soft urethane foam pad. The result indicates that on a soft pad, the SUS-FFC can restore the pad surface asperities more finely, as confirmed via the stabilized number of contact points based on contact image and luminance value distribution analyses. Subsequently, for a metal-contamination-free FFC process intended for semiconductor CMP, we develop an FFC fabricated using polyether ether ketone (PEEK) and verify its performance via the CMP test of a silicon oxide film. It is shown that the hard pad can be conditioned using the developed PEEK-FFC; this implies that a stable removal rate can be realized immediately after pad break-in conditioning.