Hideyuki Yamazaki

O3+ cluster primary ion bombardment for secondary ion mass spectrometry

Abstract The application of the oxygen cluster primary ion beam to Secondary Ion Mass Spectrometry (SIMS) was studied to obtain improved profiling qualities. In order to evaluate the analytical potential of the oxygen cluster beams, the decay length (λd), surface transient width (w) and sensitivity measured with the O3+ primary beam have been compared to O+ and O2+ data. The λd of B+ signal was determined by interface broadening of boron-doped amorphous- Si Si substrate. Further, secondary ion yield transient width (w) was observed. It was found that the O3+ primary beam gives the best depth resolution with excellent sensitivity among the three kinds of primary ions. Using the 8 keV O3+ beam with incidence angle of 37°, λd of 3.5 nm and w of 14 nm were observed. The results indicates that λd is proportional to 1 n 1 2 for primary beam of cluster size (n). This is in excellent agreement with Zalm-Vriezema model (Nucl. Instr. and Meth. B 67 (1992) 495). Moreover, we show that w varies in proportion to the impact energy per atom.

MATRIX EFFECTS IN SIMS ANALYSIS OF HIGH-DOSE BORON IMPLANTED SILICON WAFERS

Abstract Secondary ion emission from 11B+ implanted silicon wafers with dose of 1 × 1012−5 × 1016 cm−2 has been investigated. Experiments were performed using O2+ primary ions with an impact energy of 8.0 keV and an incident angle of 39° from the surface normal. The emission of 11B+ is enhanced and 28Si+ is suppressed at the peak region of boron profile for the high-dose sample, such as at doses ⩾ 5 × 1015 cm−2 (peak concentration ∼5 × 1020 cm−3). The secondary ion energy distribution of 11B+ is broadened and 28Si+ is sharpened with increasing the boron concentration. The mechanisms of these phenomena are also considered.

Influence of annealing ambient on oxygen out-diffusion in Czochralski silicon

The out-diffusion of oxygen in Czochralski grown silicon (100) wafers annealed at high temperature under a hydrogen or an argon ambient has been investigated by secondary ion mass spectrometry (SIMS). The wafers were annealed with three successive process: loading of wafers into furnace at 850 °C then ramping up, annealing at 1200 °C for 1 h, and ramping down from 1200 to 850 °C. It was found that oxygen diffusivities obtained from the above two kinds of samples showed almost the same values. Also, no difference in the oxygen concentration of the subsurface region in Si was observed between the above two kinds of samples within SIMS detection limit of 2×1016 atoms/cm3. The result indicates that there is no significant difference in oxygen diffusivity between the two annealing ambients of hydrogen and argon gases.

Quantitative secondary ion mass spectrometry analysis of the native oxide on silicon wafers

Quantitative analysis of the native oxide on silicon wafers has been investigated by secondary ion mass spectrometry (SIMS) combined with an encapsulation method. In the encapsulation technique, the sample surface is covered with a thin film whose material is identical to that of the substrate of the sample, and the analysis of the interface between the thin film and the original sample surface is performed. This technique enables quantitative analysis of the top surface of the original sample. The present study describes the optimization of the encapsulating film thickness, the reproducibility of the oxygen determination and the oxygen enhancement effects at the interface between the encapsulation film and the original sample surface. Results indicate that the minimum encapsulating film thickness is ∼130 nm when using a 14.5 keV Cs + primary ion beam. The highest oxygen areal density that can be determined with good accuracy at the interface between the encapsulation film and the original silicon surface was 8 x 10 14 atoms cm -2 .

Probing spatial heterogeneity in silicon thin films by Raman spectroscopy

Raman spectroscopy is a powerful technique for revealing spatial heterogeneity in solid-state structures but heretofore has not been able to measure spectra from multiple positions on a sample within a short time. Here, we report a novel Raman spectroscopy approach to study the spatial heterogeneity in thermally annealed amorphous silicon (a-Si) thin films. Raman spectroscopy employs both a galvano-mirror and a two-dimensional charge-coupled device detector system, which can measure spectra at 200 nm intervals at every position along a sample in a short time. We analyzed thermally annealed a-Si thin films with different film thicknesses. The experimental results suggest a correlation between the distribution of the average nanocrystal size over different spatial regions and the thickness of the thermally annealed a-Si thin film. The ability to evaluate the average size of the Si nanocrystals through rapid data acquisition is expected to lead to research into new applications of nanocrystals.

Characterization of Amorphous High-k Thin Films by EXAFS and GIXS

Silicon and nitrogen incorporated Hf oxide (HfSiON) is considered to be a promising alternative gate insulator for next‐generation MOSFETs. EXAFS and GIXS (Grazing Incidence X‐ray Scattering) have been applied to the characterization of amorphous HfSiON films at SPring‐8. Novel cluster models have been suggested based on the analogy to the ordered states for the Zr‐O‐N ternary system.

Improvement of detection limit for secondary-ion mass spectrometry depth profiling of argon in silicon by energy filtering

Abstract Secondary-ion mass spectrometry depth profiling of argon in Si has been investigated to achieve a lower detection limit. Depth profiling was performed by monitoring M+ or MCs+ secondary ions (M is the element to be analyzed), which were obtained with O2+ or Cs+ primary ions, respectively. The influence of carbonaceous mass interference ions on the detection of argon was clarified and described. It was confirmed that almost all Ar+ ions are formed in the vacuum within a distance of 100 μm from the sample surface, whereas the carbonaceous ions are formed at the surface. Using the energy-filtering (the sample voltage offsetting) technique, the detection of Ar+ ions formed above the surface and of those formed at the surface leads to increasing detecting sensitivity. The energy-filtering technique can also eliminate the influence of carbonaceous mass interference ions during analysis of Ar+. The secondary-ion mass spectrometry technique using O2+ primary ions combined with the energy filtering provides a better detection limit for depth profiling of argon in Si than does Cs+ primary-ion bombardment measurement.