NEXT-GENERATION MATERIALS FOR CMP RETAINING RINGS

摘要

Developments in Chemical Mechanical Planarization (CMP) systems and technology have enabled the advancement in semiconductor micro-processors by helping move towards smaller devices that require extremely tight process control, tight tolerances, higher quality of surface topography and planarity. A critical component of these CMP systems continues to be the retaining ring. The function of the retaining ring is to contain and position the wafer as it is being planarized. With proper material selection and design these rings can offer low polishing rates, uniform surface finish with a tight flatness tolerance and absence of large-scale topography in addition to high material stability with low vibration characteristics. All of these performance characteristics are related to the polymer materials' intrinsic surface properties and have a direct correlation to the wear resistance of the finished retaining ring. Based on a prescreening of over 30 polymer compounds, a study was undertaken by Greene, Tweed & Co.'s Semiconductor Product Engineering Group that compared two (2) of the most commonly used materials for CMP retaining rings to three (3) Arlon~(~R) PEEK (polyetheretherketone) based compounds. All five (5) materials and compounds were characterized by coefficient of friction, mean square error (vibration), and weight loss using a Center for Tribology, Inc. (CETR) polishing Micro-Tribometer model PMT.