Microbeam analysis technique

It is expected that the geometrical dimensions of IC devices will continue to decrease through the use of electron beam and x-ray lithography. Analysis of these small geometries presents additional challenges since a tradeoff exists between analysis area, and detection limits for the microbeam analysis techniques, AES and SIMS. The other surface analysis techniques of XPS and RBS already have very limited spatial resolution with respect to the current geometrical dimensions of IC s. The fabrication of denser and more complicated IC s also increases the value of each wafer which increases the need for additional process characterization and control. The increased application of surface analysis to semiconductor problems will provide a better understanding of these processes and will stimulate the further development of instrumental surface analysis techniques. 

Sample preparahon requires auxiUaries which are not required for macrotechniques. Sample preparation is parhcularly important in order to reduce artefacts by handling. The need for leUable standards for both microanalysis and imaging is great. Cer-tihed PS particle size standards (100 nm-30 u.m) are available for calibrahon (TEM, SEM, OM). For the current status on standardisahon in microbeam analysis techniques (EPMA, SEM, AEM, EDS), cfr ref. [8]. 

L. Van Vaeck and R. Gijbels. in Microbeam Analysis-1989 (P. E. Russell, ed.) San Francisco Press, San Francisco, xvii, 1989. A synopsis of laser-based mass spectrometry anal)n ical techniques. 

The utility of ANNs as a pattern recognition technique in the field of microbeam analysis was demonstrated by Ro and Linton [99]. Back-propagation neural networks were applied to laser microprobe mass spectra (LAMMS) to determine interparticle variations in molecular components. Selforganizing feature maps (Kohonen neural networks) were employed to extract information on molecular distributions within environmental microparticles imaged in cross-section using SIMS. 

RH Atalla and UP Agarwal. Raman Microprobe Optimization and Sampling Technique for Studies of Plant Cell Walls. In AD Romig and DI Goldstein, eds. Microbeam Analysis. San Francisco San Francisco Press, 1984, pp. 125-126. 

Other techniques (AES, XPS, PIXE, GD-OES, SIMS, recoil spectrometry) yield similar information as RBS. Table 4.14 summarises some essential features of the high-energy microbeam analysis methods RBS and PIXE. RBS has the ability to analyse for the lightest elements, which PIXE cannot deal with. 

Table 5.8 lists the qualifying parameters for the main microprobe techniques. Microbeam analysis usually involves depths of up to 10 /rm and a surface area of less than 100 Current highlights of optical microanalysis (UV, VIS, NIR, MIR) are near-held microscopy (towards sub- um or nanoworld)... 

Table 2 Sample preparation techniques for nuclear microbeam analysis ...

PIXE has also been used for pigment analysis in furniture and interior painting [301a], The growing use of piPIXE and associated beam techniques in art and archaeometry is noticeable [302,303], Even delicate materials such as paper and parchment are unaffected by microbeams. 

Very thin films exhibit special structure because of their confined geometry between substrate and surface. Their structure cannot be studied in a normal setup. In order to obtain enough photons on the detector, the X-ray beam must impinge on them under grazing incidence (Cf. Sects. 7.6.3.1,1.63.2, 8.8). This technique is suitably combined with microbeams. Current effort is focusing both on progress of the instrumentation and on the development of adapted analysis methods. 

In the first section will be presented XAS from the physical principles to data analysis and measurements. Then section 2 will be devoted to a discussion of a few examples to illustrate the power and limitations of XAS for gaining structural information. Examples are focused on EXAFS studies on nanocrystalline materials. Detailed reviews for applications on other fields of materials science or for presenting the complementary information available by the study of the X-ray Absorption Near Edge Structure (XANES) part of the X-ray absorption spectrum can be found in a number of books [3-5], A brief overview of the recent development of the technique regarding the use of X-ray microbeams available on the third generation light sources will be finally presented in the last section. 

In this chapter, we present in some detail gas adsorption techniques, by reviewing the adsorption theory and the analysis methods, and present examples of assessment of PSDs with different methods. Some examples will show the limitations of this technique. Moreover, we also focus on the use of SAXS technique for the characterization of porous solids, including examples of SAXS and microbeam small-angle x-ray scattering (pSAXS) applications to the characterization of activated carbon fibers (ACFs). We remark the importance of combining different techniques to get a complete characterization, especially when not accessible porosity exists. 

Sweeney R. J., Prozesky V. M., and Springhorn K. A. (1997) Use of the elastic recoil detection analysis (ERDA) microbeam technique for the quantitative determination of hydrogen in materials and hydrogen partitioning between olivine and melt at high pressures. Geochim. Cosmochim. Acte 61, 101-113. 

Modes of occurrence of the elements in coal can be determined using a variety of procedures. Perhaps the most effective method is the use of scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). This method can detect and analyze minerals as small as 1 pm in diameter (Figure 14). The SEM-EDX also provides useful information on the textural relationships of the minerals. Other microbeam techniques, such as the electron microprobe analyzer, ion microprobe, laser mass analyzer, and transmission electron microscopy, have also been used to determine modes of occurrence of elements in coal. 

This overview covers the major techniques used in materials analysis with MeV ion beams Rutherford backscattering, channelling, resonance scattering, forward recoil scattering, PIXE and microbeams. We have not covered nuclear reaction analysis (NRA), because it applies to special incident-ion-target-atom combinations and is a topic of its own [1, 2]. 

X-ray fluorescence analysis has a long history as a standard technique for analysis of mm to cm specimens using a hot-cathode X-ray source. However, the X-ray flux from a hot-cathode source is too divergent (isotropic emission) to permit efficient focusing. Thus, the niche of the synchrotron X-ray beam is in microbeam applications of the XRF technique, the inherent collimation and polarization of synchrotron radiation is well suited to use in an XRF microprobe. Details of synchrotron radiation generation are given in an accompanying chapter (Sham and Rivers, this volume). 

Microbeam Particle Induced X-ray Emission (PIXE), often called micro-PIXE, was used for single particle analysis. The greatest advantage of this system is excellent detection limits in the order of 10 -10 g. It also has the merit of a multielement non-destmctive technique with a wide range of elements for various samples. 

As mentioned above, it is possible to maintain insoluble particles, which were scavenged by raindrop, on individual raindrop replicas by collodion film technique. These insoluble particles are the target of micro-PIXE analysis. An example of the elemental map for Si, S, Cl, K, Ca, and Fe is drawn in Fig. 8. Each elemental map was drawn on the 128 x 128 pixels by scanning of about 1 pm micro beam on the sample surface. Because the residual particles were retained on a raindrop replica as several clusters, we could not radiate the microbeam to individual residual particles. However, the visualized elemental maps of six element types in several particle clusters enable us to estimate the chemical mixing state of raindrop residual particles. In addition, it is also presumed that the chemical transformation of dust particles is made by wet scavenging processes. 

Shepherd, T. J., C. Ayora, D. I. Cendon, S. R. Chenery A. Moissette, 1998. Quantitative solute analysis of single fluid inclusions in halite by LA-ICP-MS and cryo-SEM-EDS complementary microbeam techniques. European Journal of Mineralogy 10 1097-1108. 

---