Search

The Si[sup +] and O[sup +] signals, as obtained in secondary ion mass spectrometry (SIMS) analysis of silicon when using oxygen as the primary species, pass through an initial transient region before reaching the stationary state. We simulate this transient zone to check a phenomenological model for the secondary ionization of sputtered atoms. The simulation is split into two parts: the sputtering of neutrals obtained from implantation, sputtering, relocation/replacement, and diffusion, simulations and their subsequent ionization. The ionization phenomena are also described by some ad hoc fitting functions with which the SIMS measurements are better approached than with the model. The fitting functions and the model outputs are verified with experimental secondary ionization data. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Secondary ion mass spectrometry has become the preferred tool for impurity profiling primarily due to its excellent depth resolution and high detection sensitivity. Prerequisite in obtaining high detection sensitivity for positive secondary ions is the use of oxygen as primary ions. This leads to a high degree of oxidation of the sample surface, which is essential for a high secondary ion ionization efficiency. Unfortunately, this oxygen bombardment not only leads to the transformation of the original target surface into an oxidized layer but, as the latter requires a certain fluence before stationary state is reached, inherently causes some nonlinearities and transients in the secondary ion signal and the fluence-eroded depth relation. In this work a computer code implantation, sputtering, replacement/relocation, and diffusion (ISRD) has been optimized to predict the compositional changes of the sample surface (or altered layer formation), the sputter yields and the surface regression as a result of the interaction of oxygen beams with Si-targets. This article describes a careful reevaluation of the previously used version of ISRD (and the parameters contained in the program) in order to obtain a systematic agreement with experimental data on sputter yields, altered layer formation, and surface recession, and with other theoretical predictions. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The impact of the phosphorus concentration [P] on the solid-phase epitaxial regrowth rate of preamorphized p-type germanium has been studied by a combination of Rutherford backscattering, secondary ion mass spectrometry, and transmission electron microscopy. It will be shown that for P concentrations in the 1018–5×1019 cm-3 range, the regrowth rate is significantly enhanced compared with undoped germanium, while the opposite holds for [P] above about 4–5×1020 cm-3. This regrowth retardation is shown associated with segregation across the crystalline/amorphous boundary and snow plow of P in excess of the metastable solid solubility in the recrystallized material. [ABSTRACT FROM AUTHOR]

Interpretation of time-of-flight (TOF)-SIMS spectra of organic molecules could be difficult because of the presence of a high number of secondary ion peaks; this often requires the use of data analysis methods to simplify the TOF-SIMS measurements. In this study, we will demonstrate that the gentle-SIMS method could be applied to more easily interpret the TOF-SIMS spectra of organic solar cell materials. Various conditions of the primary ion beam were used to generate the gentle-SIMS spectra from pure layers of two materials, i.e. PC70BM and PCDTBT. It will be shown that by using specific conditions of the primary ion column, the corresponding molecular ion or characteristic peaks of the pure organic materials are highlighted. Results obtained on an organic layer prepared from a mixture of both materials will be also discussed. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Although the use of cesium (or oxygen) primary ions in secondary ion mass spectrometry (SIMS) enabled its success in microelectronics, issues arise at ultra-low energies, as required for extreme depth resolution, as the sputter yield becomes very small such that one enters the regime of ion beam deposition instead of material erosion. A potential solution is then to lower the Cs supply by using a Cs/Xe co-sputtering as introduced by ION-TOF and explored extensively by J. Brison. In this work, we describe a somewhat similar implementation in a Cameca SC Ultra and assess its performance and impact on ion yields. Because of the specific Cameca instrumental configuration, one alternates with short time intervals between Cs+ and Xe+ primary ions in the same ion column. Depending on the time intervals used, this approach leads to either quasi-simultaneous sputtering (intervals ~80 ms) or sequential (intervals >1 s) sputtering. An exponential variation of the Si− yield is observed when the Cs beam fraction varies from 0 (Xe) to 1 (Cs) and is ascribed to the corresponding increase in the near surface Cs concentration, CCs. Moreover, we observed detailed timing effects of the beams implying that the same nominal CCs may lead to different secondary ion yields suggesting effectively a different CCs. These effects are further investigated by observing the finer details of Cs accumulation and migration mechanisms in situ. Finally, when analysing SiGe/Si layers, it is found that with increasing Cs/Xe ratio, the decay lengths tend to decrease whereas matrix effects at interfaces show an opposite trend. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Accurate modeling of the enhancement of the ionization probabilities of secondary ions (positive and negative) by the presence of reactive species requires a precise determination of their concentration at the outermost surface and thus a fundamental understanding of their incorporation and release processes. In the present paper we discuss these processes for oxygen, cesium and cluster ion bombardment with a special emphasis on their importance at (very) low bombardment energies. At these energies the sputtering processes becomes very small and deposition instead of erosion is predicted while for some species such as oxygen and cesium, an additional process, i.e. desorption, becomes more important thereby enabling a stationary state without deposition. The desorption process is a property of the primary ion and element specific and can be predicted based on the sputter yields and heat of sublimation. For those species/conditions where desorption is not operational (such as for C60-beams), depth profiling at very low energies and with low sputter yields (<1) will not be possible and accumulation of the primary ion (thin film growth) is observed. The absence of deposition under oxygen, cesium and (SF5) n -bombardment and the positive impact of oxygen flooding on C60 bombardment can all be explained when the desorption mechanism is included in the balance equation. [Copyright &y& Elsevier]

Abstract: The application of secondary ion mass spectrometry in recent semiconductor applications has highlighted the need for extremely high depth resolution. The depth resolution limitations arise from the high dose, energetic interactions of the primary ion with the sample, leading to profile distortions due to the primary incorporation process and the collision cascades. Evolutionary and revolutionary approaches are presently proposed as potential solutions to achieve the ultimate in depth resolution. Evolutionary concepts are based on using extremely low bombardment energies (∼100eV) and/or cluster beams whereas revolutionary concepts such as zero-energy SIMS and the tomographic atomprobe remove the primary ion beam completely. [Copyright &y& Elsevier]

To study the dynamics of dopant redistribution during the silicidation process, accurate secondary-ion-mass spectroscopy (SIMS) profiles of the dopant and matrix elements are needed in partially Ni silicided gates. A point-to-point calibration method was developed to quantify the SIMS profiles, taking into account the strong dependence of the ionization probabilities of As and B on the Ni content. The Ni and Si intensities, which are needed to monitor the variation in matrix composition, are influenced strongly by the used SIMS conditions. The Ni is pushed forward very effectively by an O2+ beam, when low impact angles are used. But also the use of Cs+ beam induces a serious broadening of the Ni profile. To identify the potential artifacts the sample is analyzed from the front and the back side. The use of backside SIMS turns out to be necessary to obtain accurate SIMS profiles of the Ni. [ABSTRACT FROM AUTHOR]

Measuring HfO2/Si stacks-by secondary ion mass spectroscopy (SIMS) has become a common task in the semiconductor industry. Although the reliability of the SIMS-profiles from multilayer structures can be influenced by sputter yield and ionization yield variations in the interface region, the part of the dopant profile located beyond the interface can normally be obtained with excellent SIMS-characteristics.By comparing the SIMS-profiles from B-profiles in Si, measured with and without a HfO2-cap layer, it becomes clear that the high k film has a strong impact on the resulting dopant profiles. With the high k film present, a significant distortion of the depth and intensity scale can be observed and the B-profile (which is, in principle, fully contained in the Si) appears almost twice as deep when profiling through the HfO2-layer as compared to the uncapped sample. Normalizing the depth and concentration scale with the variations of the SiO-signals, seems to lead to an acceptable B-profile. The distortion results from a strong reduction in sputter yield due to the presence of (even small) amounts of Hf. Apparently, Hf segregates towards the surface forming a (fractional) layer, which shields the Si-atoms from sputtering. The sputter yield of this Hf-layer on the other hand is very low leading to a drastic reduction in average erosion rate. For conditions where normally no full oxidation is obtained (high energy, non-normal incidence beams on Si and Ge-substrates), this reduction leads to a temporary enhancement of the oxygen incorporation and the ionization probability. [Copyright &y& Elsevier]

For deep submicron technologies it is of crucial importance to grow ultra-thin (<3–4 nm) dielectrica with extreme quality and uniformity. It has been shown that the growth mode of these films (layer by layer versus island like) has a dramatic impact on the further integration with polysilicon and the electrical performance of the high k stack. Since a large number of process parameters need to be investigated, a rapid diagnostic tool for determining the growth mode is required. We show, based on a comparison between LEIS, XPS, and TOF-SIMS that TOF-SIMS surface spectra can be used to probe the layer structure (in particular for the detection of island growth). For this purpose, we have examined ZrO2/Si stacks grown by ALCVD for which it has already been reported that ZrO2 grows on HF-etched Si surfaces in an island growth mode. We have studied the possible matrix effects which could hamper the TOF-SIMS data interpretation and show that it is (fairly easily) possible to distinguish between different growth modes for ZrO2. [Copyright &y& Elsevier]

To get an insight in the diffusion behavior of boron after annealing and in particular its segregation characteristics towards the interface in oxide structures on silicon, it is necessary to probe the boron profile with very high accuracy and depth resolution. Sputter depth profiling as employed in secondary ion mass spectrometry (SIMS) is frequently used as the most suited tool for dopant profiling in view of its sensitivity and depth resolution. However, in order to determine the segregated boron peak, sub-nm depth resolution is required and artifacts such as beam induced broadening effects, potential ionization yield changes at interfaces, transient sputter yields need to be considered in detail. When reducing the primary beam energy the depth resolution can be improved and sub-nm depth sensitivity can be demonstrated. However, comparisons with high-resolution elastic recoil detection analysis demonstrate that even under those conditions no reliable depth profile can be obtained in the first nm near the surface nor even in the oxide part of the profile, where no ionization nor sputter yield transients are expected. Enhanced beam induced migration of boron during the initial phase of the bombardment needs to be invoked to explain the results. [Copyright &y& Elsevier]

A quantitative comparison is made of the junction depths determined by spreading resistance (SR) and secondary-ion mass spectrometry (SIMS) for submicron abrupt pn junctions (grown by molecular beam epitaxy) and Gaussian implants. The discrepancies between SR and SIMS are explained in terms of carrier spilling. From the comparison with a theoretical model, general trends can be adequately explained. In order to overcome the uncertainties imposed by the boundary conditions in this model, experimental diagrams are derived which can be used in routine analysis to assess the importance of carrier spilling effects in SR. [ABSTRACT FROM AUTHOR]

The use of an I+2 and I+ primary ion beam in secondary-ion mass spectrometry measurements was studied to investigate its depth profiling properties. A comparison with the results of a Cs+, O+2, and O+ primary beam was made. Experiments were performed with low impact energy (down to 1.7 keV) and glancing angle of incidence on molecular beam epitaxy AlGaAs-GaAs multilayer structures. The best obtainable decay length of the Al+ signal with an iodine primary beam is 1.1 nm. At low impact energies, no mass dependence on the depth resolution is observed. In these conditions, a useful yield for Al+ of approximately 5×10-5 was obtained with the Cs+ beam and 10-2 with the iodine and oxygen beams. [ABSTRACT FROM AUTHOR]

We present direct physical evidence supporting the mechanisms we proposed to explain low leakage (Jg) and low equivalent oxide thickness (EOT) in RuOx/TiOx/Sr-rich SrxTiyOz(STO)/TiN metal-insulator-metal capacitors which achieve Jg = 10-7 A/cm2 (1 V) at 0.45 nm EOT: (1) healing of STO traps by O incorporation from RuOx during STO crystallization anneal for low leakage and (2) TiOx/Sr-rich STO intermixing during STO crystallization anneal resulting in a higher Ti-content, higher k-value STO layer for low EOT. Proof of oxygen incorporation into the STO layer from the RuOx electrode as well as of TiOx/STO intermixing were obtained by secondary ion mass spectrometry performed on samples fabricated using O18 for Ru oxidation. We also show excellent match between measured leakage vs. voltage and simulations of trap-assisted leakage with asymmetric trap profiles due to STO trap healing next to RuOx, further supporting our model. [ABSTRACT FROM AUTHOR]

Abstract: Single and polycrystalline Si1−x Ge x samples have been bombarded using low energy oxygen ions to study the change in their surface morphologies and ripple formation. Both strained, relaxed and polycrystalline Si1−x Ge x samples grown on Si(001) were used to study the effect of crystallinity on ripple formation. Bombardment by 1keV oxygen ions shows completely different morphologies for the different samples under identical experimental conditions. Ripples on Si1−x Ge x samples appear much earlier than in Si. Moreover, the nature of the ripples for the polycrystalline sample is markedly different from those of the single crystals. The ripples on relaxed samples are greatly influenced by the location of the dislocation lines on the sample surface. The observations clearly show that rippling is affected not only by the layer constituents but also by its crystallinity and presence of regular structures that favour rippling in a specific direction. [Copyright &y& Elsevier]

Abstract: Nowadays, fundamental SIMS physics limits the quantitative compositional analysis of new semiconductor structures with high depth resolution and high spatial resolution. Therefore, a new concept (Zero-energy SIMS) is introduced which is based on electron beam inducted etching (EBIE) of the substrate surface and subsequent post-ionization of the volatile species by short high-power laser pulses. Silicon electron beam induced etching with SF6 as precursor species with an etching yield of 0.003 Si atoms/electron is demonstrated. Zero-energy SIMS experiments in a magnetic sector instrument with SF6 in positive mode show both electron-induced processes (ESD of fluorine) and collision-induced removal of Si atoms. These sputter events are caused by the impact of accelerated SF6 fragment anions which are formed by an electron-attachment process in the gas phase. In negative mode, a large contribution of cluster ions is observed due to the high flux of incoming polyatomic cations, formed by electron-impact ionization of SF6 molecules in the gas phase. The kinetic energy distributions of these particles are in agreement with the recombination model for cluster emission. [Copyright &y& Elsevier]

Abstract: To understand negative ion formation under Cs+ bombardment, we have studied the steady-state Cs depth distribution in Si and Ge with a focus on high-resolution analysis conditions i.e. Cs+ energies between 500eV and 5keV and impact angles from 0° to 60°. The in situ internal Cs depth profiles have been measured with a low energy O2 + beam (0.5–1keV) similar to the work of Yoshikawa [S. Yoshikawa, H. Morita, et al., Appl. Surf. Sci. 203–204 (2003) 252–255]. To minimize the distortions on Cs profiles, a non-oxidizing condition (at impact angle 60°) was chosen instead of an oxidizing condition. The internal Cs profiles in Si have a flat saturation region near the surface, with an intensity independent from the bombardment conditions. Only the profile width scales with impact angles and energies. Whereas in the Ge-case, a Gaussian profile is always obtained. Based on the internal Cs profiles, a possible near surface altered layer formation in Si and Ge under Cs bombardment is suggested. [Copyright &y& Elsevier]

Using Cs+ in the TOF-SIMS dual beam mode offers a semi-quantitative solution to depth profiling. Specifically, the use of these alkali ions strongly increases negative ion yields, decreases the positive ones and allows the formation of MCs+ and MCs2+ clusters. Recently, Niehuis and Grehl [Proceedings SIMS XII (2000) 49] developed a new approach consisting of co-sputtering Xe and Cs in order to control the Cs surface concentration, thus allowing the optimization of elemental and cluster ion yields.We applied that technique on different well-defined samples (e.g. Si, SiO2 and Al2O3) and we monitored positive ions (e.g. Si+, Al+, CsSi+, CsAl+, CsO+, Cs2O+, Cs2Si+, etc.) as a function of the sputtering beam Cs concentration.First, we observed the decrease of the elemental ions due to the work function lowering, as is predicted by the tunneling model. We then studied the behavior of the MCs+ and the MCs2+ clusters.The MCs+ yield exhibits a maximum at a given Cs/Xe beam concentration ratio, depending on the studied element M and also on its chemical environment (e.g. Si and SiO2), and on the energy of the Cs beam. In other words, it is hypothesized that this yield maximum is a consequence of the competition between the varying surface Cs coverage (direct concentration effect) and the decreasing ionization probability due to that varying Cs [Phys. Rev. Lett. 50 (1983) 127; Phys. Rev. B 29 (1984) 2311; K. Wittmaack, Proceedings SIMS VIII, (1992) 91]. Simple models based on the tunneling model were applied to interpret our results.The MCs2+ signal behaves in a very different way. As shown by Gao [Y. Gao, Y. Marie, F. Saldi, H.N. Migeon, Proc. SIMS IX, (1994) 382], these clusters are predominant for electronegative elements and increase in a monotonous way with Cs beam concentration. [Copyright &y& Elsevier]

Due to its numerous advantages ToF-SIMS profiling has often been used in the analysis of high-k dielectrics. However, profiling high-k gate stacks induces a number of artifacts such as preferential sputtering, tailing of the metal peak in the substrate, interfacial peaks, etc.In this work, we investigated a number of sputtering conditions (Ar, Xe, Ga, energy ranging from 350 eV to 15 keV) in order to determine the most favorable sputtering condition which minimizes these artifacts. The results show that the tail of the Hf in the Si is only marginally dependent on the sputtering conditions suggesting another mechanism than collisional mixing. It also shows that even if the influence on the tail is limited, Xe profiling is far superior to Ar profiling in terms of depth resolution for the rest of the profile. Finally, this work also shows that partially oxidizing sputtering conditions lead to heavily distorted profiles. [Copyright &y& Elsevier]

Measuring HfO2/Si stacks by secondary ion mass spectroscopy (SIMS) has become a common task in the semiconductor industry. However, when analyzing these stacks with an oxygen beam, a strong impact of the experimental conditions on the Hf+ signal as well on the Si signal can be observed. In order to understand these effects, we investigated the effect of oxygen on the depth profiling of these stacks using an Atomika 4500.In this paper, the ionization probability of Hf sputtered from a HfO2/Si stack as well a Hf implantation in Si is measured for different beam incidence angles and energies. It is shown that basically two physical mechanisms are responsible for the Hf signal intensities. The first part of the signal can be correlated with the impact of oxygen on the Hf ionization degree, in line with the classical bond-breaking theory. The second mechanism is more difficult to define, but appears linked to the emission of Hf into a different (neutral, molecules?) emission channel, thereby reducing the available Hf for detection as Hf+. Finally, a very strong influence of Hf on the Si and Si-cluster ions is reported. [Copyright &y& Elsevier]

Abstract: The laser-assisted Atom Probe has been proposed as a metrology tool for next generation semiconductor technologies requiring sub-nm spatial resolution. In order to assess its potential for the analysis of three-dimensional semiconductor structures like FinFETs, we have studied the Atom Probes lateral resolution on a silicon, silicon–germanium multilayer structure. We find that the interactions of the laser with the semiconductor materials in the sample distort the sample surface. This results in transient errors of the measured dimensions of the structure. The deformation of the sample furthermore leads to a degradation of the lateral resolution. In the experiments presented in this paper, the Atom Probe reaches a lateral resolution of 1-1.8nm/decade. In this paper we will discuss the reasons for the distortions of the tip and demonstrate that with the present state of data reconstruction severe quantification errors limit its applicability for the quantitative analysis of heterogeneous semiconductor structures. Our experiments show that reconstruction algorithms taking into account the time dependent nanostructure of the tip shape are required to arrive at accurate results. [Copyright &y& Elsevier]

Abstract: In advanced interconnect applications, the possibility to remove completely photoresist layers is one of the key points. To have the maximum removal efficiency, the selection of the needed chemistries is of first importance. To this end, the characterization of post-etched photoresists can be used to support that selection. The complete work includes the use of various spectroscopic and polymer characterization techniques. In the present paper, results obtained by time of flight-secondary ion mass spectrometry (ToF-SIMS), angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and Auger electron spectroscopy (AES) are presented for the characterization of post-etched photoresist used in photoresist mask patterning schemes. [Copyright &y& Elsevier]

Abstract: Reducing the energy of the primary ions will improve the depth resolution in SIMS depth profiling. At ultra low energies (<150eV) the sputtering yield is drastically reduced. In this report we will focus on Cs+ ions, which are commonly used for their enhancement of negative secondary ion formation, and discuss the impact of these extreme conditions on the steady state surface concentration of cesium. In contrary to what is found from sputtering-based retention models, the steady state surface concentration of (retained) cesium on silicon reaches a maximum value in the order of 15at%. [Copyright &y& Elsevier]

Abstract: In order to fabricate carrier profiles with a junction depth (∼15nm) and sheet resistance value suited for sub-32nm Si-CMOS technology, the usage of sub-melt laser anneal is a promising route to explore. As laser annealed junctions seem to outperform standard anneal approaches, a detailed assessment of the basics of laser induced activation seem appropriate. In this work the electrical activation is studied from a comparison between the dopant profiles as measured by Secondary Ion Mass Spectrometry, and the electrically active fraction as extracted from sheet resistance and mobility measurements. The latter is based on a large variety of techniques. For the sheet resistance we use conventional Four-Point Probe (FPP), Variable Probe Spacing (VPS), contactless junction photo voltage (JPV), Micro Four-Point Probe (M4PP) and an optical technique, namely Model Based Infra-red spectroscopic Reflectrometry (MBIR). For the sheet carrier density and sheet mobility extraction we use conventional Hall (without cloverleaf van der Pauw patterning, to reflect the need for fast turn-round sheet measurements), MBIR, and a recently developed new Hall-like capability using M4PP. By recognizing the interaction between the various parameters as they are not completely independent, it is possible to test the consistency of the various methods and to identify potential short comings. This concept is applied to the activation behavior of low and high implanted Boron doses and indicates that the obtained electrically active concentration level as well as the concurrent mobility is dependent on the dopant concentration level. This implies that the activation of B through the laser anneal process in the explored temperature–time space is governed by kinetic processes (i.e. the dissolution of B–I pairs) and not by the (temperature related) solid solubility. [Copyright &y& Elsevier]

Abstract: As CMOS is approaching the 22nm node, the importance of high-mobility materials such as Ge and GaAs is rapidly increasing. For the timely development of these new technologies accurate dopant and carrier-profiling solutions for source-drain extensions with these materials are required. Identical n-type-doped (Si, Se) layers on same and opposite type medium-doped layers on S.I. GaAs substrates will be investigated, with layer thicknesses ranging from 200 down to 50nm and doping concentration levels up to 1e20at/cm3. In this work, secondary ion mass spectrometry will be used for dopant profiling. For GaAs carrier profiling, conventional spreading resistance probe, as commonly used in Si-CMOS, fails. Hence, reliable alternatives need to be found for characterizing these high–low structures. Techniques to be discussed range from the more conventional approaches such as Hall or electrochemical capacitance–voltage (performed by different laboratories), over micro-Raman spectroscopy and photo-luminescence along a beveled surface, up to more advanced approaches using scanning spreading resistance microscopy. [Copyright &y& Elsevier]

Ultrathin (a few nm) mixed HfO2/Al2O3 oxides deposited by ALCVD on Si substrates were analyzed with low energy (250 eV) Cs+ and Xe+ ions by ToF-SIMS in the dual beam mode. The analysis beam was 15 keV Ga+. Several layers were measured, with different metal ratios (Hf:Al) and different number of deposition cycles. We observed a significant enhancement of the Al (and AlOx clusters) signal at the surface along with a Hf (and HfOx clusters) depletion at the film surface. However, the thinnest films were found to contain much more Hf than the thickest ones. Several ion ratios were used (e.g. HfO+/AlO+ or HfO2-/AlO2-) in order to quantify the Hf:Al concentration ratio in the films. We found that these ratios correlate well with each other, with the metal deposition ratio, and with XPS ratios, enabling us to reconstruct the Al and Hf composition variation in the film. [Copyright &y& Elsevier]

SIMS depth profiles obtained from a B implanted Si sample capped with a thin HfO2 film revealed the presence of several artifacts that make it problematic to determine the distribution and concentration of elements in the underlying Si substrate. The distribution of the B implant, normalized to 30Si+, was much broader than expected. Variations in the intensities of several matrix species under the HfO2 film were also observed. AFM measurements from the sputtered crater bottoms suggested that sputter-induced surface roughness is present under the high-k/Si interface. The roughness is partially responsible for reducing the sputter rate, which in turn lowers matrix ion intensities. The sputter rate variation can be corrected using the ratio of intensity loss of different matrix species. Use of the variation in the SiO+ intensity to correct the depth scale of the normalized B profile provided the best agreement with the original B implant-only sample. Rotating the sample while profiling improves the shape of the normalized B profile but some sputter rate correction was still necessary. The presence of 10% Hf (atomic) in the Si leads to slight reduction in the SiO+ intensity but the sputter rate does not need correcting. Under these conditions, point-by-point normalization of the B profile to a matrix species cancels out the ion yield variations. At Hf concentrations >10% the combination of ion yield and sputter rate variations complicates the depth profiles. [Copyright &y& Elsevier]

Using a 3 keV O2-beam in an in situ SIMS/RBS set-up, changes in sputter yield and ionization probability were measured in order to come to a better understanding of the behavior of the Si+ signal during the build up of the altered layer. Based on the RBS-spectra the evolution of the sputter yield within the transient region can be determined. When combined with complementary results from a low energy ion scattering (LEIS) experiment [T. Janssens, C. Huyghebaert, W. Vandervorst, A. Gildenpfennig, H.H. Brongersma, in these proceedings], the ionization probability enhancement as a function of the oxygen concentration at the surface can be calculated. [Copyright &y& Elsevier]

By combining in situ SIMS/RBS measurements, sputter yields variations and ionisation probability variations were measured in the transient region of a poly-Si0.8Ge0.2 layer bombarded with 12 keV O2+ at normal incidence. The goal of the experiment is to investigate if the prepeak in the Ge+ SIMS signal could be explained by sputter yield variations. The result of the experiment shows a minimum in the sputter yield variation of Ge during the build-up of the altered layer, which does not coincide with the minimum of the Ge+-signal. This suggests that the prepeak is not only a sputter yield effect but also due to a change in ionisation probability. [Copyright &y& Elsevier]