Nuclear Reaction Analysis of Shallow B And Bf2 Implants in Si

1987 ◽  
Vol 92 ◽  
Author(s):  
Mark C. Ridgway ◽  
P J. Scanlon ◽  
J.L. Whitton
Keyword(s):  
Nuclear Reaction ◽  
Secondary Ion Mass Spectrometry ◽  
Matrix Effects ◽  
Depth Profiling ◽  
Impurity Diffusion ◽  
System Model ◽  
Nuclear Reaction Analysis ◽  
Near Surface ◽  
Annealing Conditions ◽  
Secondary Ion

ABSTRACTImpurity diffusion induced by rapid thermal annealing (RTA) has been investigated for low energy B and BF2 implants in crystalline and preamorphized Si. A 50 keV 2×1015/cm2 Si self-implant was used for preamorphization. Samples were annealed with an oxide cap in an AG Associates HEATPULSE system (model 210T). Prior to the impurity depth profiling measurements, the SiO2 was removed with dilute HF. Significant B diffusion to theSiO2/Si interface was observed for a 1050°C/10 s anneal of 10 keV 3×1015/cm2 implanted;11B in crystalline and preamorphized Si. B interfacial concentrations were comparableto peak concentrations in unannealed samples. Diffusion of B and F to the SiO2/Si interface, and impurity gettering by ion straggling damage were observed for a 1050°C/10 s anneal of 45 keY 3×1O15/cm2 implanted 49BF2 in crystalline Si.though a loss F was apparent.Depth profiles were determined with nuclear reaction analysis (NRA) [1-3], specifically the 11B(ρ,α0)8 Be(ER=163 key) [4] and 19F(ραγ)160 (ER - 340 keV) [5] reactions for 1lB and 19F profiling, respectively. This technique is sensitive to impurities at or near the surface and can reveal impurity diffusion to near-surface regions not usually detectable with secondary ion mass spectrometry (SIMS). NRA depth profiling has shownthat RTA can result in significant impurity diffusion to the SiO2/Si interface for B implanted in crystalline and preamorphized Si, and BF2 implanted in crystalline Si. Impurity concentrations at the interface are estimated to be in excess of 1020/cm3 for the implantation and annealing conditions used in this report. BF2 implanted in preamorphized Si showed greatly reduced impurity concentrations at the interface. A knowledge of the impurity concentrations at the substratesurface or the SiO2/Si interface becomes increasingly important as device dimensions decrease. Matrix effects make such measurements difficult with SIMS.

SIMS Depth Profiling Free of Martix Effects

2005 ◽  
Vol 908 ◽  
Author(s):  
Peter Huber ◽  
Helmut Karl ◽  
Bernd Stritzker
Keyword(s):  
Elemental Concentration ◽  
Secondary Ion Mass Spectrometry ◽  
Matrix Effects ◽  
Depth Profiling ◽  
High Dose ◽  
Concentration Depth Profile ◽  
The Matrix ◽  
Elemental Depth ◽  
Secondary Ion ◽  
Sims Depth Profiling

AbstractWe present a method of determining elemental depth profiles with secondary ion mass spectrometry (SIMS) corrected by all non-linearities between the SIMS countrate and the elemental concentration caused by chemical matrix effects, resulting in an absolute concentration depth profile. The key to this method is a low dose ion implantation step of corresponding reference isotopes prior to SIMS depth profiling. Spectra evaluation is performed on the basis of a selfconsistent evaluation in which the depth dependent influence of the matrix is determined. The technique is demonstrated for sequentially high dose ion implanted Cd and Se in SiO2.

Near-Surface and Interfacial Profiling by Neutron Depth Profiling (NDP) and Secondary Ion Mass Spectrometry (SIMS)

1983 ◽  
Vol 25 ◽  
Author(s):  
R. G. Downing ◽  
R. F. Fleming ◽  
J. T. Maki ◽  
D. S. Simons ◽  
B. R. Stallard
Keyword(s):  
Thin Film ◽  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Depth Profiling ◽  
Neutron Depth Profiling ◽  
Absolute Concentration ◽  
Near Surface ◽  
Ion Mass Spectrometry ◽  
Non Destructive ◽  
Secondary Ion

ABSTRACTInformation relating the spatial arrangement and concentration of intentional and intrinsic dopants is commonly required to fully understand the properties of a material, whether the application is chemical, electrical, or physical. We have synergistically coupled the near-surface techniques of thermal neutron depth profiling (NDP) and secondary ion mass spectrometry (SIMS) for the purpose of better determining the distribution of a few key elements in a number of matrices and thin-film interfacial applications.The NDP facility, unique in the U.S., allows virtually non-destructive measurements of the absolute concentration of specific elements (e.g,, He, Be, Li, B, Na, Bi . . .) to be made versus their depth distribution in a specific matrix [1]. The quantitative information is derived from the number and the residual energy of emitted charged particles that are produced in situ by uniformly illuminating a sample volume with thermalized neutrons. Sensitivity, depth of view, and resolution are dependent upon the reaction cross-section for the element of interest and the characteristic energy loss for the elemental components of the matrix. However, experimental parameters, such as the sample angle relative to the detector, can be adjusted to extract the maximum depth or the best resolution information from the measurement [2]. Since the technique is non-destructive, samples can be subjected to a series of treatments and profiled after each step [3].The more mature SIMS technique is able to detect most of the elements listed above with greater relative sensitivity but without an absolute concentration calibration. Therefore, by utilizing the abundance information obtained by NDP, a concentration scale can be established for the SIMS profile. SIMS is also useful in probing smaller surface areas, a few tens of micrometers square as opposed to a few millimeters square for NDP. The advantage in coupling the two techniques lies principally with the role NDP plays in distinguishing experimental artifacts from real concentration variations [4]. While some matrices and interfacial areas of a sample give rise to variable sensitivities in SIMS measurements. NDP, however, counts every event that emitted a charged particle within the solid angle subtended by the detector, thereby, making it more reliable for reporting the concentration information.Shown in Figure 1 is a comparison of NDP and SIMS profiles determined for a boron-10 implant in a single-crystal silicon, a common processing step for semiconductor materials. The agreement between techniques is good. Possible sources of discrepancies between the two methods are briefly discussed by Ehrstein et al. [3].The combined effort of SIMS-NDP is currently being utilized to study diffusion and boundary segregation in thin-film semiconductor applications. Accurate depth profiles have been difficult to obtain by other analytical approaches for such material systems. The ability of SIMS-NDP to profile across interfacial regions and thin films will allow many other electrical devices and material problems to be addressed more reliably.

Study of Layer Disordering in MeV Si Implanted GaAs/AlGaAs Superlattices.

1988 ◽  
Vol 144 ◽  
Author(s):  
Samuel Chen ◽  
S.-Tong Lee ◽  
G. Braunstein ◽  
G. Rajeswaran
Keyword(s):  
Molecular Beam ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Region ◽  
Defect Band ◽  
Implantation Energy ◽  
Near Surface ◽  
Free Zone ◽  
Annealing Conditions ◽  
Transmission Electron ◽  
Secondary Ion

ABSTRACTLayer intermixing in MeV Si-implanted quantum well superlattices (SLs) has been studied by transmission electron microscopy, secondary ion mass spectrometry and Rutherford backscattering spectroscopy. Molecular beam epitaxially grown GaAs(200Å) - Al0. 5Ga0.5As(200Å) SLs were implanted with 1 MeV Si+ at doses between 3 × 1014 and 1 × 1016/cm2. The implanted SLs were either furnace annealed at 850°C for 3 hr or rapid thermally annealed at 1050°C for 10 sec, both under GaAs proximity capping conditions. Totally mixed regions were observed only for the SLs implanted with 1 × 1016 Si/cm2 and then furnace annealed at 850°C for 3 hr. For the same dose, the RTA annealed SLs only showed slight layer intermixing. At lower doses, no appreciable intermixing was detected in either furnace or RTA annealed samples. By contrast, under either annealing condition extensive intermixing has been demonstrated for lower energy (220 keV) implantation, but at doses almost two orders of magnitude lowerl XTEM showed that in all the annealed samples, a defect-free zone existed in the near-surface region, followed by a band of secondary defects, with the maximum density located at about 1 μm below the surface. In the disordered samples, the position of the intermixed layers correlated with the defect band maximum. Under both annealing conditions, Si concentration profiles only showed slight broadening, and they correlated with the distribution of secondary defects as well as with the depth of the intermixed layers. The effects of dynamic annealing and surface on the implantation energy dependence, i.e., MeV vs. keV, of layer intermixing are discussed.

Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

1985 ◽  
Vol 43 ◽  
pp. 368-369
Author(s):  
S. H. Chen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Cross Section ◽  
Electron Spectroscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Specimen Preparation ◽  
Near Surface ◽  
Gaas Films ◽  
Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

Oxygen isotope (δ18O) trends measured from Ordovician conodont apatite using secondary ion mass spectrometry (SIMS): Implications for paleo-thermometry studies

2021 ◽  
Author(s):  
Cole T. Edwards ◽  
Clive M. Jones ◽  
Page C. Quinton ◽  
David A. Fike
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Matrix Effects ◽  
Analytical Techniques ◽  
Upper Ordovician ◽  
Bulk Analysis ◽  
Middle Ordovician ◽  
Ion Mass Spectrometry ◽  
Oxygen Isotopic ◽  
Secondary Ion

The oxygen isotopic compositions (δ18O) of minimally altered phosphate minerals and fossils, such as conodont elements, are used as a proxy for past ocean temperature. Phosphate is thermally stable under low to moderate burial conditions and is ideal for reconstructing seawater temperatures because the P-O bonds are highly resistant to isotopic exchange during diagenesis. Traditional bulk methods used to measure conodont δ18O include multiple conodont elements, which can reflect different environments and potentially yield an aggregate δ18O value derived from a mixture of different water masses. In situ spot analyses of individual elements using micro-analytical techniques, such as secondary ion mass spectrometry (SIMS), can address these issues. Here we present 108 new δ18O values using SIMS from conodont apatite collected from four Lower to Upper Ordovician stratigraphic successions from North America (Nevada, Oklahoma, and the Cincinnati Arch region of Kentucky and Indiana, USA). The available elements measured had a range of thermal alteration regimes that are categorized based on their conodont alteration index (CAI) as either low (CAI = 1−2) or high (CAI = 3−4). Though individual spot analyses of the same element yield δ18O values that vary by several per mil (‰), most form a normal distribution around a mean value. Isotopic variability of individual spots can be minimized by avoiding surficial heterogeneities like cracks, pits, or near the edge of the element and the precision can be improved with multiple (≥4) spot analyses of the same element. Mean δ18O values from multiple conodonts from the same bed range between 0.0 and 4.3‰ (median 1.0‰), regardless of low or high CAI values. Oxygen isotopic values measured using SIMS in this study reproduce values similar to published trends, namely, δ18O values increase during the Early−Middle Ordovician and plateau by the mid Darriwilian (late Middle Ordovician). Twenty-two of the measured conodonts were from ten sampled beds that had been previously measured using bulk analysis. SIMS-based δ18O values from these samples are more positive by an average of 1.7‰ compared to bulk values, consistent with observations by others who attribute the shift to carbonate- and hydroxyl-related SIMS matrix effects. This offset has implications for paleo-temperature model estimates, which indicate that a 4 °C temperature change corresponds to a 1‰ shift in δ18O (‰). Although this uncertainty precludes precise paleo-temperature reconstructions by SIMS, it is valuable for identifying spatial and stratigraphic trends in temperature that might not have been previously possible with bulk approaches.

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