Abstract-In this study, various cleaning solutions containing chelating agents with carboxyl acid group ( COOH), such as ethylenediaminetetraacetic acid, citric acid and oxalic acid, were developed for post-poly-Si CMP cleaning. The chelating agent and tetramethylammonium hydroxide (TMAH) were simultaneously added into 2% ammonium hydroxide alkaline solution to promote the removal efficiency on particles and metallic impurities. The effectiveness of various cleaning recipes and their interaction mechanism with poly-Si surface were studied. We could explain the surface behavior of various cleaning solutions by the different molecular size and charge of chelating agents. Based on the mechanism, the behavior of surface particle and metallic impurity can be realized. The co-existence of TMAH with citric acid or oxalic acid in the alkaline cleaning solutions can significantly enhance the electrical property for the capacitor.

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The positive bias temperature instability (PBTI) characteristics of contact-etch-stop-layer (CESL)-strained HfO 2 nMOSFET are thoroughly investigated. For the first time, the effects of CESL on an HfO 2 dielectric are investigated for PBTI characteristics. A roughly 50% reduction of V TH shift can be achieved for the 300-nm CESL HfO 2 nMOSFET after 1000-s PBTI stressing without obvious HfO 2 /Si interface degradation, as demonstrated by the negligible charge pumping current increase (< 4%). In addition, the HfO 2 film of CESL devices has a deeper trapping level (0.83 eV), indicating that most of the shallow traps (0.75 eV) in as-deposited HfO 2 film can be eliminated for CESL devices.Index Terms-Contact etch stop layer (CESL), HfO 2 , positive bias temperature instability (PBTI).

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