Effect of microwave annealing on electrical characteristics of TiN/Al/TiN/HfO2/Si MOS capacitors

Abstract

In this letter, microwave annealing over a wide range of power (300–2700 W) in nitrogen ambient was performed on TiN/Al/TiN/HfO2/Si metal-oxide-semiconductor capacitors. Capacitors with rapid thermal annealing at 500 °C were also fabricated for comparison at the same wafer temperature measured during microwave annealing at 2700 W. For microwave annealed capacitors, key parameters such as equivalent oxide thickness, interface state density, oxide trapped charge, leakage current density, and breakdown voltage were all improved with increasing microwave annealing power. For the capacitor with rapid thermal annealing at 500 °C, diffusion of Al into TiN and growth of the interfacial oxide layer are detected, leading to the shift in flat-band voltage and increase in equivalent oxide thickness, respectively. The results further indicate that it is more effective to remove the charged traps by microwave annealing than by rapid thermal annealing, and the reduction in leakage current density after microwave annealing corresponds to the reduction in charge traps based on a trap-assisted tunneling model. With no trade-off relationship between the electrical characteristics and no undesired effect such as diffusion of species, microwave annealing demonstrates great potential for the post-metallization annealing process for the high-k/metal gate structure.

Half-volt operation of IGZO thin-film transistors enabled by ultrathin HfO2 gate dielectric

“…The breakdown electric field strength is comparable to other reports about HfO2. 29,30 There are a few possible electron transport mechanisms including direct tunneling, Poole-Frenkel (P-F) emission, Fowler-Nordheim (F-N) tunneling, and Schottky emission, etc.…”

Microwave plasma annealing of sol-gel deposited tantalum oxide and zinc oxide films

“…The effects of MW plasma treatment on exposed materials/substrates require intricate evaluations, since electrical and thermal conductivity play an outstanding role during processing. In this sense, conductive materials can be annealed through excitation of electron mobility by exposure to microwaves even without plasma ignition [19,20] and the dissipation of thermal energy is thus clue.…”

Effects of Chamber Pressures on the Passivation Layer of Hydrogenated Nano-Crystalline Silicon Mixed-Phase Thin Film by Using Microwave Annealing

“…The effects are ascribed to the details of microwave absorption, which selectively affects Si-H bonds, and thus hydrogen bonds were restructured [31]. Some studies have reported microwave annealing in the thin-film coating technology [32][33][34][35]. The MWA has two major microwave heating processes: ohmic conduction and dielectric polarization losses, mainly influenced by the thickness and conductivity of the thin films; and the other is the dielectric permittivity of the thin film materials [36].…”