Papers by Keyword: Cu CMP

Abstract: Due to the emergence of sub-7 nm technologies, next generation CMP slurry formulations have continued to increase in additive (nanoparticle and chemistry) complexity to meet stringent device specifications. Therefore, it is essential to probe the molecular level interactions at the nanoparticle/slurry chemistry/substrate interface and in turn correlate them to key performance metrics such as removal rate, post CMP defects, and planarization efficiency. This work will address key interactions through a series of case studies focusing on the role of supramolecular structure and cleaning method (i.e. contact vs. non-contact) during STI post-CMP cleaning, probing the impact of supramolecular structure and mode of cleaning relevant to Cu post-CMP, and development of a biomimetic matrix with chemical activity to act as a brush in STI post-CMP cleaning processes. Results show in both BEOL and FEOL post-CMP cleaning there is a strong correlation to the delivery and “soft” nature of the chemistry to allow for effective particle removal at low mechanical force and prevent further defect formation. Furthermore, this work shows a clear correlation between supramolecular structure and particle removal efficiency under both contact and non-contact post-CMP processes.

Abstract: Cu post-CMP clean is important to keep both Cu and low-k dielectric clean after polishing. In this paper, two Cu post-CMP clean solutions are analyzed in electrochemical, physical and electrical characterizations, based on the material and integration scheme of imec 65nm platform. It is shown that the combination of these two PCMP clean solutions can achieve both reasonable cleaning efficiencies and reliable low-k dielectric lifetime.

Abstract: The purpose of this study is to investigate the effects of slurry pH on the adhesion and removal of silica and ceria abrasive particles on the poly Si, TEOS, SiN and SAC (self aligned memory cell contact) and STI (shallow trench isolation) patterned wafer surfaces. The adhesion force of silica and ceria particles were theoretically and experimentally investigated in STI and poly Si CMP process. A stronger adhesion force was observed for silica particles on the poly Si wafer in acidic rather than in alkaline solutions. The adhesion force of ceria particle was lower than that of silica in investigated pH ranges. STI patterned wafer showed lower adhesion force than SAC patterned wafer. Lower adhesion force between particles and surface resulted in a lower level of particle contamination.

Abstract: Corrosion on specific Cu patterns was evaluated during Cu CMP. The corrosion was observed at isolated patterns and outer edge area of pad surrounded by oxide field after polishing and showed dependency on process. Two different commercial slurries were chosen and used for polishing after characterizing electrochemical and frictional properties. Stress simulations were conducted on these patterns. Higher stress was calculated on these patterns. The process temperature and friction behavior of Cu affected the magnitude of corrosion on Cu on these patterns.

Abstract: The adhesion force and removal of alumina particles on Cu, Ta, TEOS, SILKTM, Aurora and FSG wafer surfaces were experimentally and theoretically investigated in slurry solutions of different pHs. These wafer surfaces showed negative zeta potentials in the investigated pH ranges with exception of FSG and Ta. However, the zeta potentials of FSG surface drastically decreased with increasing pH. The lowest adhesion force and smallest number of alumina particles were measured between alumina particle and FSG surface in a slurry solution of pH 11. Alkaline slurry was much more desirable in controlling the level of particle contamination during Cu CMP. The pH of the slurry and zeta potentials of the surfaces played important roles in controlling the interaction force.