CMOS compatible dual metal gate integration with successful Vth adjustment on high-k HfTaON by high-temperature metal intermixing |
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Authors: | C Ren DSH Chan WY Loh GQ Lo N Balasubramanian D-L Kwong |
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Affiliation: | aInstitute of Microelectronics, Science Park II, Singapore 117685, Singapore;bSilicon Nano Device Lab, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore |
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Abstract: | In this paper, we report for the first time a novel dual metal gate (MG) integration process for gate-first CMOS platform by utilizing the intermixing (InM) of laminated ultra-thin metal layers during high-temperature annealing at 1000 °C. In this process, an ultra-thin ( 2 nm) TaN film is first deposited on gate dielectric as a buffer layer. Preferable laminated metal stacks for NMOS and PMOS are then formed on a same wafer through a selective wet-etching process in which the gate dielectric is protected by the TaN buffer layer. Dual work function for CMOS can finally be achieved by the intermixing of the laminated metal films during the S/D activation annealing. To demonstrate this process, prototype metal stacks of TaN/Tb/TaN (NMOS) and TaN/Ti/HfN (PMOS) has been integrated on a single wafer, with WF of 4.15 and 4.72 eV achieved, respectively. Threshold voltage (Vth) adjustment and transistor characteristics on high-k HfTaON dielectric are also studied. |
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Keywords: | CMOS Metal gate Dual work function Integration Intermixing |
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