Identifying Performance-Critical Defects in the High-k/Metal Gate Stacks

Applied Physics Letters

et al. 2009

Internal multiphoton photoemission (IMPE) and time-dependent electrostatic field-induced second-harmonic (TD-EFISH) generation are used to probe charge trapping kinetics in Si/SiO2/Hf1−xSixO2 films. For as-deposited Si/SiO2/HfO2 samples, we observe a unique resonant TD-EFISH response to IMPE charging at incident photon energies near 1.6 eV: a delayed TD-EFISH decay not observed at off resonant energies or in x≠0 samples. We explain the TD-EFISH decay by resonant two-photon ionization of point defects and subsequent tunneling of the photoelectrons to the Si substrate. Hysteresis in the resonant TD-EFISH response shows that the photoionized defects are rechargeable and located within the HfO2 bulk.

Resonant photoionization of defects in Si/SiO2/HfO2 film stacks observed by second-harmonic generation

Price

Applied Physics Letters

et al. 2009

Identification of electrically active defects in thin dielectric films by spectroscopic ellipsometry

Price¹,

Bersuker²,

Journal of Applied Physics

2012

A study of resonant photo-absorption features in high-k dielectric film stacks using vacuum ultraviolet spectroscopic ellipsometry demonstrates that all optically observable dielectric-related defects are located in the interfacial SiO2 layer rather than in the bulk high-k film. The defects, located at 2.9 eV, 3.6 eV, 3.9 eV, and 4.75 eV within the bandgap of this bottom interface, are found to be strongly affected by processing conditions. These results are supported by both electrical and physical characterization measurements that identify a consistent trend in the evolution of charge trapping defects for samples subjected to identical processing conditions. In addition, evidence is provided correlating the optically active 2.9 eV defect to positively charged oxygen vacancies in the bottom interfacial layer that have recently been proposed as contributing to the flatband voltage roll-off phenomenon. The close connection between these results and both ab initio calculations and experimental findings substantiate the use of spectroscopic ellipsometry as a unique characterization method for identifying process-induced defects during development and fabrication of dielectric film stacks.

Charge trapping defects in Si/SiO2/Hf(1−x)SixO2 film stacks characterized by spectroscopic second-harmonic generation

Price¹,

Lei²,

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

et al. 2011

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