Electrical and Material Evaluation of the MOCVD TiN as Metal Gate Electrode for Advanced CMOS Technology
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0917-E12-02
Electrical and Material Evaluation of the MOCVD TiN as Metal Gate Electrode for Advanced CMOS Technology Raghunath Singanamalla1,2, Judit Lisoni1, Isabelle Ferain1,2, Olivier Richard1, Laure Carbonell1, Tom Schram1, HongYu Yu1, Stefan Kubicek1, Stefan de Gendt1,3, Malgorzata Jurczak1, and Kristin de Meyer1,2 1 IMEC, Leuven, 3001, Belgium 2 ESAT, University of Leuven, Leuven, 3001, Belgium 3 Chemistry, University of Leuven, Leuven, 3001, Belgium ABSTRACT The electrical and material characterization of Ti(C)N deposited by metal organic chemical vapor deposition (MOCVD) technique, as metal gate electrode for advanced CMOS technology is investigated. The effects of the plasma treatment, post anneal treatment and the thickness variation of the Ti(C)N film on the flat band voltage (VFB) and effective work function (WF) of the Poly-Si/Ti(C)N/SiO2 Poly-Si/Ti(C)N/SiO2 gate stack s are reported. We found that both the in-situ plasma treatment and post anneal treatment help in reducing the carbon content (organic) in the film making it more metallic compared to the as-deposited films. However, the post anneal treatment was found to be a better option for getting rid of hydrocarbons as compared to plasma treatment from the gate dielectric integrity point of view. The thickness variation of post annealed Ti(C)N film ranged from 2.5 nm to 10 nm lead to WF shift of upto ~350 mV for both Poly-Si/Ti(C)N/SiO2 and Poly-Si/Ti(C)N/HfO2 gate stacks. INTRODUCTION To meet the ITRS specification for the 45 nm node and beyond the poly-Si gates will have to be replaced by metal gate electrodes [1]. Metal gate electrodes not only eliminate the gate depletion and dopant penetration problems in CMOS transistors, but also reduce the gate sheet resistance. The possibility to modulate their WF through the nitrogen content has already been reported [2]. In this work the Ti(C)N film is deposited by Metal Organic Chemical Vapor Deposition (MOCVD) technique. The Ti(C)N deposited is highly porous and has high sheet resistance because of high amounts of hydrocarbon compounds (precursor residues). These organic compounds can be reduced either by insitu plasma or ex-situ anneal treatments. In this paper, we investigate the effect of these treatments on the VFB and the gate dielectric integrity. We also report the micro-structural characterization of the TiN films before and after the plasma and post anneal treatments. WF modulation of the post annealed (@ 700 oC, 5 min. in N2) Poly-Si/Ti(C)N/SiO2 and Poly-Si/Ti(C)N/HfO2 gate stacks as a function of thickness variation of Ti(C)N are also reported.
EXPERIMENTAL Metal oxide Semiconductor capacitors (MOSCAPs) with Poly-Si/TiN/SiO2, PolySi/TiN/HfO2 gate stacks were fabricated on p-type Si (100) wafers. Standard Local oxidation LOCOS or Shallow trench isolation (STI) techniques were used to isolate the active and field regions. This was followed by gate dielectric deposition. HfO2, SiO2, SiON were chosen as three gate dielectrics. A slanted SiO2 layer was formed after thermally grown SiO2 was wet-
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