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Wet-etch etchants and the TaN film method for dual-metal-gate integration are investigated.Both HF/HN O 3 /H 2 O and NH 4 OH/H 2 O 2 solutions can etch TaN effectively,but poor selectivity to the gate dielectric for the HF/HNO 3 /H 2 O solution due to HF being included in HF/HNO 3 /H 2 O,and the fact that TaN is difficult to etch in the NH 4 OH/H 2 O 2 solution at the first stage due to the thin TaO x N y layer on the TaN surface,mean that they are difficult to individually apply to dual-metal-gate integration.A two-step wet etching strategy using the HF/HNO 3 /H 2 O solu-tion first and the NH 4 OH/H 2 O 2 solution later can fully remove thin TaN film with a photo-resist mask and has high selectivity to the HfSiON dielectric film underneath.High-k dielectric film surfaces are smooth after wet etching of the TaN metal gate and MOSCAPs show well-behaved C-V and J g-V g characteristics,which all prove that the wet etching of TaN has little impact on electrical performance and can be applied to dual-metal-gate integration technology for removing the first TaN metal gate in the PMOS region.
Wet-etch etchants and the TaN film method for dual-metal-gate integration are investigated. Both HF / HN O 3 / H 2 O and NH 4 OH / H 2 O 2 solutions can etch TaN effectively, but poor selectivity to the gate dielectric for the HF / HNO 3 / H 2 O solution due to HF being included in HF / HNO 3 / H 2 O, and the fact that TaN is difficult to etch in the NH 4 OH / H 2 O 2 solution at the first stage due to the thin TaO x N y layer on the TaN surface, mean that they are difficult to individually apply to dual-metal-gate integration. A two-step wet etching strategy using the HF / HNO 3 / H 2 O solu- tion first and the NH 4 OH / H 2 O 2 solution later can fully remove thin TaN film with a photo-resist mask and has high selectivity to the HfSiON dielectric film underneath. High-k dielectric film surfaces are smooth after wet etching of the TaN metal gate and MOSCAPs show well-behaved CV and J gV g characteristics, which all prove that the wet etching of TaN has little impact on electrical performance and can be appli ed to dual-metal-gate integration technology for removing the first TaN metal gate in the PMOS region.