White light interferometry for quantitative surface characterization in ion sputtering experiments

• Published in: Applied surface science Vol. 258; no. 18; pp. 6963 - 6968
• Main Authors: Baryshev, S.V., Zinovev, A.V., Tripa, C.E., Erck, R.A., Veryovkin, I.V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2012; Elsevier
• Subjects: CALIBRATION; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Craters; Cross-disciplinary physics: materials science; rheology; CURRENT DENSITY; Depth profiling; ELECTRONS; Exact sciences and technology; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; Genesis; GEOMETRY; INTERFEROMETRY; ION BEAMS; Ion sputtering; Mass spectrometry; MORPHOLOGY; ORIGIN; Physics; RESOLUTION; Scanning electron microscopy; Silicon; SPUTTERING; Three dimensional; White light interferometry; 79.20.Rf; White light interferometry; 07.60.Ly; Genesis; 06.30.Bp; 61.80.Jh; Depth profiling; Mass spectrometry; Ion sputtering; Light interferometry; Depth profiles; Sputtering
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.03.144

► Ion beam profiles and crater shapes, yielding accurate sputtering yields, are quantitatively characterized by white light interferometry. ► A dual-beam mass spectrometric system utilizing overlap of multiple ion beams is precisely aligned by means of white light interferometry. ► Time-to-depth calibration in sputter depth profiling experiments is performed by white light interferometry. ► Precise characterization of shallow (∼10nm in depth) surface processing of a Si Genesis collector coupon by a gas cluster Ar2000+ ion beam is carried out by white light interferometry. White light interferometry (WLI) can be used to obtain surface morphology information on dimensional scale of millimeters with lateral resolution as good as ∼1μm and depth resolution down to 1nm. By performing true three-dimensional imaging of sample surfaces, the WLI technique enables accurate quantitative characterization of the geometry of surface features and compares favorably to scanning electron and atomic force microscopies by avoiding some of their drawbacks. In this paper, results of using the WLI imaging technique to characterize the products of ion sputtering experiments are reported. With a few figures, several example applications of the WLI method are illustrated when used for (i) sputtering yield measurements and time-to-depth conversion, (ii) optimizing ion beam current density profiles, the shapes of sputtered craters, and multiple ion beam superposition and (iii) quantitative characterization of surfaces processed with ions. In particular, for sputter depth profiling experiments of 25Mg, 44Ca and 53Cr ion implants in Si (implantation energy of 1keV per nucleon), the depth calibration of the measured depth profile curves determined by the WLI method appeared to be self-consistent with TRIM simulations for such projectile-matrix systems. In addition, high depth resolution of the WLI method is demonstrated for a case of a Genesis solar wind Si collector surface processed by gas cluster ion beam: a 12.5nm layer was removed from the processed surface, while the transition length between the processed and untreated areas was 150μm.