60 research outputs found
A new total reflection X-ray fluorescence vacuum chamber with sample changer analysis using a silicon drift detector for chemical analysis
No full textThere are several TXRF spectrometers commercially available for chemical analysis as well as for wafer surface analysis, but there is up
to now no spectrometer for chemical analysis available that allows to measure samples under vacuum conditions. Simply a rough vacuum of
10 2 mbar for the sample environment reduces the background due to scattering from air, thus to improve the detection limits. The
absorption of low energy fluorescence radiation from low Z elements is reduced and therefore extends the elemental range to be measured
down to Na. Finally evacuation of the chamber removes the Ar K-lines from the spectrum.
The new vacuum chamber for TXRF named WOBISTRAX is equipped with a 12-position sample changer, a 10-mm2 silicon drift
detector (SDD) with an 8-Am Be entrance window and electrical cooling by Peltier effect, so no LN2 is required. The chamber was designed
to be attached to a diffraction tube housing. WOBISTRAX can be operated with a 3 kW long fine focus Mo-X-ray tube and uses a Mo/Si
multilayer for monochromatization. The modified software is performing the motion control between sample changer and MCA features.
The performance is expressed in terms of detection limits which are 700 fg Rb for Mo Ka excitation with 50 kV, 40 mA excitation
conditions, 1000 s livetime. Using a Cr-X-ray tube for excitation of Al the achieved detection limits are 52 pg. So it could be shown that with
the same measuring chamber and using an SDD with 8 Am Be window and a Cr-tube for excitation, low Z elements can be also measured
with good detection limit
Grazing exit versus grazing incidence geometry for x-ray absorption near edge structure analysis of arsenic traces
No full textIn the presented study the grazing exit x-ray fluorescence was tested for its applicability to x-ray
absorption near edge structure analysis of arsenic in droplet samples. The experimental results have
been compared to the findings of former analyses of the same samples using a grazing incidence
GI setup to compare the performance of both geometries. Furthermore, the investigations were
accomplished to gain a better understanding of the so called self-absorption effect, which was
observed and investigated in previous studies using a GI geometry. It was suggested that a normal
incidence-grazing-exit geometry would not suffer from self-absorption effects in x-ray absorption
fine structure XAFS analysis due to the minimized path length of the incident beam through the
sample. The results proved this assumption and in turn confirmed the occurrence of the
self-absorption effect for GI geometry. Due to its lower sensitivity it is difficult to apply the GE
geometry to XAFS analysis of trace amounts few nanograms of samples but the technique is well
suited for the analysis of small amounts of concentrated sample
Influence of the sample morphology on total reflection X-ray fluorescence analysis
No full textTotal reflection X-ray fluorescence analysis (TXRF) is a method for qualitative and quantitative analysis of trace elements. In general TXRF is known to allow for linear calibration typically using an internal standard for quantification. For small sample amounts (low ng region) the thin film approximation is valid neglecting absorption effects of the exciting and the detected radiation. However, for higher total amounts of samples deviations from the linear relation between fluorescence intensity and sample amount have been observed. The topic of the presented work is an investigation of the parameters influencing the absorption phenomenom. Samples with different total amounts of arsenic have been prepared to determine the upper limit of sample mass where the linear relation between fluorescence intensity and sample amount is no longer guaranteed. It was found that the relation between fluorescence intensity and sample amount is linear up to ~100 ng arsenic. A simulation model was developed to calculate the influence of the absorption effects. Even though the results of the simulations are not satisfying yet it could be shown that one of the key parameters for the absorption effect is the density of the investigated element in the dried residues
Characterization of As Implants and Hf Layer with a new Spectrometer for Grazing Incidence XRF
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Distribution of Pb and Zn in slices of human bone by synchrotron -XRF
No full textSynchrotron radiation-induced micro x-ray fluorescence analysis (m-XRF) at HASYLAB beamline L was
used to determine the distribution of Pb and other trace elements in slices of human bone. Using a
focused synchrotron x-ray beam of about 15 μm in diameter it was found that Pb was mostly located at
the outer border of the cortical bone in various samples. Ratios of Pb intensities of cortical and trabecular
bone varied from 0.027 for hip head to 0.408 for proximal tibia. Additionally Ca, Zn and Sr distributions
were simultaneously recorded. A remarkable association between Pb and Zn content could be observed
A new spectrometer for grazing incidence X-ray fluorescence for the characterization of Arsenic implants and Hf based high-k layers
No full textGrazing Incidence X-ray Fluorescence Analysis (GIXRF) is a powerful technique for depth-profiling and characterization of thin layers in depths up to a few hundred nanometers. By measurement of fluorescence signals at various incidence angles Grazing Incidence X-ray Fluorescence Analysis provides information on depth distribution and total dose of the elements in the layers. The technique is very sensitive even in depths of a few nanometers. As Grazing Incidence X-ray Fluorescence Analysis does not provide unambigous depth profile information and needs a realistic input depth profile for fitting, in the context of the EC funded European Integrated Activity of Excellence and Networking for Nano and Micro-Electronics Analysis (ANNA) Grazing Incidence X-ray Fluorescence Analysis is used as a complementary technique to Secondary Ion Mass Spectrometry (SIMS) for the characterization of Ultra Shallow Junctions (USJ). A measuring chamber was designed, constructed and tested to meet the requirements of Grazing Incidence X-ray Fluorescence Analysis. A measurement protocol was developed and tested. Some results for As implants as well as Hf based high k layers on Silicon are shown. For the determination of the bulk As content of the wafers, Instrumental Neutron Activation Analysis has also been applied for comparison
Non destructive dose determination and depth profiling of arsenic ultrashallow junctions with total reflection X-ray fluorescence analysis compared to dynamic secondary ion mass spectrometry
No full textSecondary ion mass spectrometry (SIMS) has been the most widely used technique for the measurement of dopant distribution in Si
because of its ability of determining profile shape, junction depth, and dose with adequate depth resolution and detection limits. In the case of
ultrashallow implants though, SIMS is going towards its intrinsic limits; in fact, initial transient width and native oxide-induced matrix effects
affect the measurement in the first nanometres where a relevant part of the dopant is confined. Therefore, complementary techniques able to
give information on the dose and on the distribution in the first nanometres are required. In this work, total reflection X-ray fluorescence
analysis (TXRF) resolved in angle has been evaluated as a candidate, given its high sensitivity in the near surface region, its ability of a
quantitative analysis, its multielement capability, and its nondestructiveness. Three arsenic implanted Si samples have been analysed by
SIMS and TXRF. The SIMS measurements have been carried out by a magnetic sector instrument of new generation with a Cs+ primary
beam and by monitoring negative secondary ions. The TXRF measurements were performed at beamline 6-2 of the Stanford Synchrotron
Radiation Laboratory. For the fluorescence measurements, an absolute quantification by fundamental parameters and comparison with the Si
fluorescence signal has been adopted. The TXRF dose determination showed good agreement with other techniques. TXRF could also
evaluate the accuracy of the SIMS profile in the first nanometres
Grazing Incidence X-Ray Fluorescence characterisation of Ultra Shallow Junctions in the ANNA consortium
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