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SIMS-EDX system for a standard-free analysis Yu. Kudriavtsev, R. Asomoza Sección Electrónica del Estado Solido, Departamento Ingeniería Eléctrica, CINVESTAV-IPN, Av. IPN #2508, México, DF 07360, México yuriyk@cinvestav. mx
Introduction SIMS as any other technique has advantage as well as weak points. The most important disadvantage is poor quantification of SIMS data: by using implanted standards quantification can be done with an experimental error of around ± 20%. SIMS analysis of main elements (the concentration range of 1%-100%) cannot be quantified by SIMS using implanted standards; a special calibration procedure should be performed, because of non-linear dependence between concentration of the element of interest and experimental secondary ion current, monitored for it. Energy dispersive X-ray spectroscopy ideally complements SIMS, because of standard free quantitative analysis of most of the elements with the concentration from 0. 01 atomic % to 100 atomic %.
General idea: Utilize an Electron Gun of any SIMS instrument, used typically for charge compensation, to excite characteristic X-Ray emission from analyzed sample to realize Energy Dispersive X-ray spectroscopy method with the SIMS instrument.
Installation of EDD at ims-6 f instrument Si crystal of EDD Primary ion trap EDX detector: Exterior view
A modified Strip: the closed window protect EDD in the SIMS mode
Application of EDX-SIMS instrument: I. Semiconductors 1. Quantitative analysis of solid solutions: bulk, thick films, thin films. See Poster Section: Tue-pos-43 2. Calibration of SIMS (RSFs) for main element analysis in complex materials. 3. Shallow junction analysis (LEXES “inside“). II. Metals and alloys: Quantitative analysis of bulk, thick films and thin films. III. Glass (including natural), ceramics, minerals, etc. Quantitative analysis of bulk, thick films and thin films. X-ray spectrum of obsidian
Two different strategies: I. Perform a quantification of main elements by EDX , then analyze dopants and contamination by SIMS MBE grown 1 micron epi-layer of Al 0. 2 Ga 0. 8 N: EDX spectrum and SIMS depth profile
II. “Internal calibration” of SIMS
Elemento Ti* Al* V Mo Zr Fe Si Concentración, % atómicos 83. 2 9. 2 4. 5 3. 0 0. 1 EDX spectrum and found composition of Ti allow Fig. RSFs as a function of Ionization potential of element. Points show experimental RSFs, found by SIMS with using of EDX data.
Fragments of mass- spectrum, acquired by SIMS for Ti allow
Table 1 Composition of Ti allow, defined by EDX/SIMS in comparison with Certificate of the provider. Elemento Certificate EDX SIMS Falla, % H 0. 072% n/d 0. 091% <26% B n/d 3 E-4% n/d C 0. 044% n/d 0. 050% <15% N 0. 028% n/d 0. 062% x 2 Na n/d 4 E-4% n/d Al 2. 72% 9. 2%* 2. 72%* n/d Si 0. 12% 0. 1% <15% K n/d 3 E-6% n/d Ca n/d 6 E-5% n/d Ti 87. 4% 83. 2%* 87. 4% n/d V 4. 2% 4. 5% <7% Cr Suma: 0. 03% n/d 0. 027% n/d 0. 011% n/d Mn Fe 0. 095 0. 1% <5% Ni Suma: 0. 03% n/d 0. 002% n/d n/d Cu Zr 0. 058 n/d 0. 06% <4% Mo 2. 7% 3. 0% <10% In n/d 1. 4 E-4% n/d * Rose rows corresponds to elements used for SIMS calibration.
Conclusions: 1. EDX technique ideally complements SIMS for a quantitative analysis of complex materials. 2. Any SIMS instrument, equipped by an Electron Gun, can be “modified” to perform EDX analysis. 3. Energy of primary electron beam can be varied from 0 to 10 ke. V, this means we can vary thickness of the analyzed layer from several microns down to a hundred nanometers. 4. Standard-free analysis in the “full” range of concentration: from 100 atomic % down to 10 -7 atomic %, can be realized with a reasonable accuracy. THANK YOU FOR YOUR ATTENTION!