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k dielectric stacks
Published in A. G. Cullis, P. A. Midgley, Microscopy of Semiconducting Materials 2003, 2018
A J Craven, M MacKenzie, D W McComb, D A Hamilton
termed hafnium silicate, is a co-deposition of the HfD2 and Si02 · Adding SiO2 to amorphous HfD2 increases the crystallisation temperature and suppresses B diffusion but reduces the k value. Thus insertion of a thin layer of HfSiO between HfD2 and the poly-Si gate electrode can improve overall performance. Spectrum imaging is a powerful technique with which to investigate the structure and chemistry of such gate stacks. This technique was proposed by Jeanguillaume and Colliex (1989) and has recently become commercially available. It uses computer control to position an electron beam and to record one or more spectra at each point. Here, electron energy loss spectra are recorded and the electron energy loss near edge structure (ELNES) is used to provide information on the chemical state of the elements at each point. Since the chemical state of the atom determines the ELNES, it is possible to separate out the contributions to an edge from atoms in different phases. This is carried out by modelling the edge shape as a linear combination of the shapes from appropriate standards.
Oxygen diffusion
Published in Michel Houssa, κ Gate Dielectrics, 2003
R M C de Almeida, I J R Baumvol
Oxygen exchange is the main reaction channel, although oxygen incorporation to complete the pseudobinary alloy stoichiometry and oxygen incorporation to oxidize the Si substrate are alternative, active reaction channels. All those instabilities are moderate for up to 30 s of RTA. For 60 s RTA times and above there is a sudden increase in the concentration and penetration depth of the oxygen propagating front, leading to a substantial increase in the thickness of the SiO2 interlayer. For 480 s RTA a complete collapse of the structure and interface abruptness of the film are observed. When compared to previous materials considered for SiO2 replacements as gate dielectric, such as Al2O3, ZrO2, Zr–Si–O, Zr–Al–O, Gd2O3, Gd–Si–O and others, the present hafnium silicate films present higher stability under annealing at 1000°C.
Effects of growth parameters on HfO2 thin-films deposited by RF Magnetron sputtering
Published in Radiation Effects and Defects in Solids, 2022
M. Dhanunjaya, N. Manikanthababu, S. Ojha, Soodkhet Pojprapai, A.P. Pathak, S.V.S. Nageswara Rao
Hafnium oxide (HfO2) films are well studied, understood and utilized in electronic and optical applications (1,2). HfO2 has a high refractive index (∼2), large bandgap (5.7 eV) (3) and wide transparent range from Ultra Violet (UV) to Infra-Red (IR) region. A fully oxidized HfO2 film doesn’t absorb radiation from 300 nm to about 10 µm. The transparency of hafnia in the near-ultraviolet (near-UV) to far-infrared (far-IR) region has various applications such as astronomical Si-based CCDs (4), night vision and IR optical devices (5), UV-IR protective layers (6,7), solar cells antireflection coatings (8) etc. In early 2007, Intel Corporation announced that HfO2 is more suitable than SiO2 as a gate dielectric material in metal oxide semiconductors for their next-generation 45 nm technology (9). Around the same time, in 2008, the IBM corporation also announced their plans to incorporate high-k dielectric material for their new products (10). Because of its superior properties in microelectronics, NEC electronics also announced the inclusion of hafnium Silicate Oxy Nitride compound (HfSiON) in their 55 nm ultra-low-power technology (11). HfO2 based Resistive Random-Access Memory (RRAM) is another emerging field in non-volatile memory applications (12–14). Irradiation experiments on HfO2 material and devices show that it may be used as a radiation-resistant material for space applications (15–18). As mentioned earlier, HfO2 is the state-of-the-art material in integrated circuit technology. Recent studies showed that the HfO2 and the doped HfO2 thin films have potential ferroelectric applications (19,20). Many of its properties still need thorough investigations even though it has seen high usage in modern integrated circuits to meet the market demands.