Paper PS-TuP11
Dry Etching Properties of TiN for Metal/High-k Gate Stack by using BCl₃-based Inductively Coupled Plasma

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Transistor has been scaled down since they were introducing, continually. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. This can be achieved by using an insulator that has a high dielectric constant. Recently, high dielectric materials like Al₂O₃, ZrO2, and HfO₂2 are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. So, it is a good barrier-layer material for interconnection. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled BCl₃-based plasma system and adding O₂, Ne, and N₂. Dry etching of the TiN was studied by varying the etching parameters including BCl₃/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, substrate temperature and gas addition. The plasmas were characterized by optical emission spectroscopy analysis and quadrupole mass spectrometer measurements. The chemical reaction on the surface of the etched TiN was investigated with X-ray photoelectron spectroscopy. Scanning electron microscopy was used to investigate the etching profile.