CQs __ __ E!!B NOM zyxwvutsrqp B Beam Interactions w ith MaterialsB Atoms Nuclear Instruments and Methodsin Physics Research B 130 (1997) 219-223 ELSEVIER Improved high energy microbeam techniques A. Kumar a, A. Haberl aT*, H. Bakhru ‘, B. Rout b a zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Department zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Physics, Accelerator Laboratory, University at Albany, Albany, NY 12222. USA b Institute of Physics, Bhubaneswar, India zyxwvutsrqponmlkjihgfedcbaZYXWVU Abstract The University at Albany ion scanning microprobe has been usedfor many industrial applications in thin films. Of prime importance for rapid analysis,the beam shouldbe set-up and in-use very shortly after the beam is turned on. Rapid optic and electronic tune-up methods are discussed. Standard 1-2 micron, 2 MeV helium or proton beams are generally used with RBS (Rutherford Backscattering) and PIXE (ParticleInduced X-ray Emission) to obtain composition analysis in one- or two-dimensions. We demonstrate the use of 3-dimensionalanalysis in thin films, wherein film thicknessis the third dimension. 1. Introduction 2. OSTI system for beam analysis and adjustment For routine applications in materials analysis,data taking should normally be in progress within 15 min of accelerator cold startup. We expectthe microbeam to maintain the same state of readiness.Although mostly automated,the Albany system still requires some small amount of micro-alignment and focusing. The use of a rear transmission mode visual micro- scope makes adjustment easy for beam size down to about 2 pm, but difficult below that level. We have developed a new techniqueto aid in rapid focusing and micro-alignment. As part of a joint programs with the Center for Advanced Technology in Thin Films at the Univer- sity at Albany, scanningRBS has been tested for use in characterizing thin film uniformity. We report here on several of thetests. Focus and alignmentof the microbeam are nor- mally adjusted while viewing the beam spot on thin glass with a 200 power microscope.The microscope view is clear and easy to interpret for a beam spot of 2 p,rn or greater, but becomes increasinglydifficult as the spot size approaches 1 p.m. Final adjustments can be made by using the SEM (Secondary Electron Microscope) mode on a 2000mesh electronmicro- scope grid placednext to, and in the same plane with the test sample. Focus can also be adjusted during SEM scanning of the test sample, but only if the sample is electrically conductive and has sharply differentiated features in the SEM view. While the SEM scan view of the grid is usually adequate for adjusting focus, it is generally not helpful in fine-tuning for beam shape. Since the operator has only a general impression of overall “sharpness” of the grid image, coma, flare and distortion are not easily recognized. Flare and distor- tion tails can often be chopped off using scraper slits * Corresponding author. Fax: + l-518-442-4486; email: awhl3@cnsvax.albany.edu 0168-583X/97/$17.00 0 1997Elsevier Science B.V. All rights reserved. PI1 SO168-583X(97)00169-9 V. MICROPROBE ANALYTICAL TECHNIQUES