Yoshimasa Horii

New diffractometer for thin‐film structure analysis under grazing incidence condition

We designed and constructed a new x‐ray diffractometer under grazing incidence condition. This diffractometer is mainly composed of two goniometers; (1) a goniometer for grazing incidence angle control and (2) a goniometer for a sample rotation. The axes of the goniometers are orthogonal to each other. Furthermore, a detector moves parallel and vertical to the sample surface. Therefore, lattice constants of vertical and parallel components can be identified. We will describe components and accuracy of our designed diffractometer for grazing incidence x‐ray diffraction and show applications for TiSi2 (several 10 nm thickness) and GaAs (20 monolayer) on Si.

IrO2/Pb(Zr,Ti)O3/Pt Capacitor Degradation with D2 Gas at Elevated Temperature

The degradation of Pb(Zr,Ti)O3 [PZT] ferroelectric capacitors with IrO2 top electrode and Pt bottom electrode was evaluated by baking at 200°C in 3% D2/N2 gas at 4.5 Torr up to 20 min. The polarization of the capacitor decreased by more than 60% and the hysteresis loop shifted to positive side when baked for 15 min or more in D2/N2 gas. Auger Electron Spectroscopy indicated that the surface of the IrO2 was reduced to Ir metal during D2 baking. Secondary ion mass-spectroscopy (SIMS) of the PZT capacitor revealed that the degraded PZT contained a D concentration of 5×19 atoms/cm3. The degradation of the capacitor followed a three step mechanism: 1) reduction of the IrO2 top electrode surface to Ir, 2) Deuterium dissociation into to D+ ions on the Ir surface and 3) diffusion of D+ into the PZT film.

Suppression of the Phase Transition to C54 TiSi2 due to Epitaxial Growth of C49 TiSi2 on Si(001) Substrates in Silicidation Process

The epitaxial C49 TiSi2 formed after annealing of Ti films deposited on Si(001) substrates has been studied by grazing-incidence X-ray diffraction. The relations C49 TiSi2(10\bar1)?Si(001), C49 TiSi2(100)?Si(001), and C49 TiSi2(010)?Si(001) are observed on a highly BF2-implanted substrate, and the a or b face of C49 is sharply orientated toward the directions deviating ?5? from Si on a clean substrate in ultrahigh vacuum (UHV). These epitaxial C49 grains are thermally stable and difficult to transform into the C54 phase even after annealing at high temperature. In contrast, ramdomly distributed C49 grains have been observed on unimplanted and low-dosed substrates and for thick Ti films in UHV. These polycrystalline C49 grains are thermally unstable and easily transformed into the C54 phase. The influence of implantation and UHV process on the growth of the epitaxial C49 and the phase transition of C49 to C54 are discussed.

Grazing Incidence X-Ray Diffraction Study on Effect of Implanted BF+2 and Linewidth on Titanium Silicidation

The C49 and C54 fractions in TiSi2 are examined quantitatively by the grazing incidence X-ray diffraction method in order to study the effect of BF+2 implanted in Si substrates and linewidth on TiSi2 silicidation and the phase transition from C49 to C54. BF+2 implantation suppresses both silicidation and the phase transition, and the phase transition is also markedly suppressed on narrow lines. As a result, all the C49 TiSi2 remains for 0.5 µ m lines with BF+2 dose of 2×1015 cm-2 after the 2nd rapid thermal annealing (800° C, 30 s). Furthermore, we have found that the grains of C49 TiSi2 are preferentially oriented to highly implanted substrates. This indicates that the phase of these grains is stable thermally and difficult to transform to C54 phase.