Innovative CMP Solution for Advanced STI Process

With feature size of ICs shrinking to below 20 nm, it is increasingly difficult to strike a balance between removal rate and defectivity in Chemical Mechanical Planarization (CMP) processes of semiconductor wafer fabrication. In Shallow Trench Isolation (STI) CMP processes for advanced technology nodes, the use of ceria slurry significantly elevates oxide removal rate and oxide-nitride selectivity. However, there are still challenges in the STI CMP process such as narrow process windows and high defectivity. Scratch defects in particular tend to have significant impact on circuit probing yield. As a result, CMP consumables need to meet more stringent requirements for advanced STI process. Innovation in pad materials has been important when it comes to the design of products for advanced CMP processes. The development of IKONIC(TM) 4000 series polishing pads by Dow was aimed at delivering high removal rate and low defectivity at the same time. The design of pad material and groove pattern facilitates conditioning efficiency and removal of pad debris during polishing. In this paper, we investigated the effect of different conditioners and conditioning methods in ceria slurry with an IKONIC(TM) 4000 series polishing pad. We have successfully optimized the conditioning and polishing recipe for this platform, which displayed outstanding performance against Pad A on advanced pattern wafer polishing. Through process optimization, the same polishing pad was successfully adopted in both Platen 1 (fumed silica slurry process) and Platen 2 (ceria slurry process) for an advanced STI process. Keywords: CMP consumables, STI, pads, IKONIC(TM) 4000 series pad