scholarly journals Numerical investigation of depth profiling capabilities of helium and neon ions in ion microscopy

2016 ◽  
Vol 7 ◽  
pp. 1749-1760 ◽  
Author(s):  
Patrick Philipp ◽  
Lukasz Rzeznik ◽  
Tom Wirtz
Keyword(s):  
3D Imaging ◽  
Secondary Ion Mass Spectrometry ◽  
Depth Profiling ◽  
Lateral Resolution ◽  
Cluster Ions ◽  
Depth Information ◽  
Preferential Sputtering ◽  
Atomic Mixing ◽  
Primary Ions ◽  
Ion Species

The analysis of polymers by secondary ion mass spectrometry (SIMS) has been a topic of interest for many years. In recent years, the primary ion species evolved from heavy monatomic ions to cluster and massive cluster primary ions in order to preserve a maximum of organic information. The progress in less-damaging sputtering goes along with a loss in lateral resolution for 2D and 3D imaging. By contrast the development of a mass spectrometer as an add-on tool for the helium ion microscope (HIM), which uses finely focussed He+ or Ne+ beams, allows for the analysis of secondary ions and small secondary cluster ions with unprecedented lateral resolution. Irradiation induced damage and depth profiling capabilities obtained with these light rare gas species have been far less investigated than ion species used classically in SIMS. In this paper we simulated the sputtering of multi-layered polymer samples using the BCA (binary collision approximation) code SD_TRIM_SP to study preferential sputtering and atomic mixing in such samples up to a fluence of 1018 ions/cm2. Results show that helium primary ions are completely inappropriate for depth profiling applications with this kind of sample materials while results for neon are similar to argon. The latter is commonly used as primary ion species in SIMS. For the two heavier species, layers separated by 10 nm can be distinguished for impact energies of a few keV. These results are encouraging for 3D imaging applications where lateral and depth information are of importance.

scholarly journals Experimental and simulation-based investigation of He, Ne and Ar irradiation of polymers for ion microscopy

2016 ◽  
Vol 7 ◽  
pp. 1113-1128 ◽  
Author(s):  
Lukasz Rzeznik ◽  
Yves Fleming ◽  
Tom Wirtz ◽  
Patrick Philipp
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Bubble Formation ◽  
Md Simulations ◽  
Rare Gas ◽  
Preferential Sputtering ◽  
Rare Gas Atoms ◽  
Impact Energies ◽  
Primary Ions ◽  
The Impact ◽  
Ion Species

Secondary ion mass spectrometry (SIMS) on the helium ion microscope (HIM) promises higher lateral resolution than on classical SIMS instruments. However, full advantage of this new technique can only be obtained when the interaction of He+ or Ne+ primary ions with the sample is fully controlled. In this work we investigate how He+ and Ne+ bombardment influences roughness formation and preferential sputtering for polymer samples and how they compare to Ar+ primary ions used in classical SIMS by combining experimental techniques with Molecular Dynamics (MD) simulations and SD_TRIM_SP modelling. The results show that diffusion coefficients for He, Ne and Ar in polymers are sufficiently high to prevent any accumulation of rare gas atoms in the polymers which could lead to some swelling and bubble formation. Roughness formation was also not observed. Preferential sputtering is more of a problem, with enrichment of carbon up to surface concentrations above 80%. In general, the preferential sputtering is largely depending on the primary ion species and the impact energies. For He+ bombardment, it is more of an issue for low keV impact energies and for the heavier primary ion species the preferential sputtering is sample dependent. For He+ steady state conditions are reached for fluences much higher than 1018 ions/cm2. For Ne+ and Ar+, the transient regime extends up to fluences of 1017–1018 ions/cm2. Hence, preferential sputtering needs to be taken into account when interpreting images recorded under He+ or Ne+ bombardment on the HIM.

A new method for the determination of the diffusion-induced concentration profile and the interdiffusion coefficient for thin film systems by Auger electron spectroscopical sputter depth profiling

2004 ◽  
Vol 19 (11) ◽  
pp. 3389-3397 ◽  
Author(s):  
J.Y. Wang ◽  
E.J. Mittemeijer
Keyword(s):  
Concentration Profile ◽  
Interdiffusion Coefficient ◽  
Auger Electron ◽  
Depth Profiling ◽  
Interface Roughness ◽  
Diffusion Annealing ◽  
Multilayered Structures ◽  
Preferential Sputtering ◽  
Atomic Mixing ◽  
Fitting In

A new Auger electron spectroscopical sputter depth profiling method was developed to determine the interdiffusion coefficient for the initial stage of diffusion annealing of thin films. The method is based on (i) adoption of an interdiffusion model appropriate for the specimen investigated and (ii) convolution of an accordingly calculated diffusion-induced concentration profile with the smearing effects due to atomic mixing, surface/interface roughness, escape depth of the Auger electrons, and preferential sputtering. The diffusion-induced concentration profile and the interdiffusion coefficient are determined by fitting in an iterative least-squares procedure of the calculated Auger electron spectroscopical depth profile to the measured one. The method was applied to bilayered and multilayered structures, exhibiting dominant grain-boundary diffusion and dominant volume diffusion, respectively. A very small extent of interdiffusion, characterized by diffusion distances as small as 1 nm, could be quantified.

Absolute Calibration of Sims Depth Profiles of a-SiNx:H/a-Si:H and a-SiOx:H/a-Si:H Multilayers

1995 ◽  
Vol 382 ◽  
Author(s):  
Jianwei Li ◽  
Jan M. Chabala ◽  
Riccardo Levi-Setti
Keyword(s):  
Cross Sections ◽  
Secondary Ion Mass Spectrometry ◽  
High Spatial Resolution ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Absolute Calibration ◽  
Ion Microprobe ◽  
Depth Profiles ◽  
Atomic Mixing ◽  
Secondary Ion

ABSTRACTWe calibrated secondary ion mass spectrometry (SIMS) depth profiles of a-SiNx:H/a-Si:H and a-SiOx:H/a-Si:H multilayer samples by comparing them to high-spatial-resolution SIMS maps of cross sections through the layers. Both profiles and images were acquired with a focused scanning 45 keV Ga+ ion microprobe. During depth profiling an area gating technique was used to improve depth resolution. At the beginning of the profile the resolution was 8 nm. By cutting the multilayer films at a small angle through the layers, we obtained SIMS images of cross sections through thesemultilayer samples. The resolution along the expanded direction is about 10 nm. By comparing the depth profiles and the cross section images, we determined the ionbeam-induced atomic mixing in the samples, as a function of depth and the sputtering yield for each layer.

Characterization of the Substrate/Film Interface in GaN Films by Image Depth Profiling Secondary Ion Mass Spectrometry (Sims)

1997 ◽  
Vol 468 ◽  
Author(s):  
Salman Mitha ◽  
Robert Clark-Phelps ◽  
Jon W. Erickson ◽  
Y. Gao ◽  
Wook Kim ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Film Growth ◽  
Depth Profiling ◽  
Depth Information ◽  
Lattice Match ◽  
Growth Defects ◽  
Secondary Ion ◽  
Image Depth

Epitaxial GaN films are normally grown on substrates, such as sapphire, that are not an exact lattice match for GaN. Thus during the early stages of film growth, defects may be introduced in the film. These defects can lead to islanding and form voids or other defects just above the interface. These defects produce nonuniformity in the films and affect the quality of the final film. SIMS depth profiling is a widely used to characterize GaN films. The normal SIMS depth profiles provide chemical and depth information but do not provide any lateral information. We show that image depth profiling with SIMS is a technique that can be used to identify the defects and also chemically identify other interface features with lateral dimensions down to 1 μm.

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