№-0122

Full Title:	Development of Quantitative Methods in SEM for Nondestructive Analysis of Surface and Nearsurface Layers of Solid-State Structures
Technology Field(s):	PHY-SSP: Physics / Solid State Physics INS-MEA: Instrumentation / Measuring Instruments

Contributors

Vasily A Shelokov

CCB "ALMAZ" (ALMAZ) 80, Leningradskii pr., Moscow, 111024, Russia Phone: 7+095+1759410; 7+095+2619581 Fax: 7+095+1585671; 7+095+2619581

Present Status of Research

Brief Description of Research

The goals of the project are the development of nondestructive quantitative methods for the analysis of surface and nearsurface layers of solid-state structures in SEM (scanning electron microscopy) using various signals (electron-beam-induced current (EBIC), secondary and backscattered electrons, etc.); the elaboration of signal formation models, and development of software for signal simulation and solving the inverse problems.

Under linear dimension measurements in SEM, a spatial resolution of about a few nm has been achieved, but for the development of metrology, it is necessary to have a more accurate description of signal formation mechanisms from the profiled surface and to develop programs for signal simulation and solving the inverse problems. Under investigations of the distribution of electrical properties by SEM techniques, the spatial resolution is in the electron range; in thin layers, only diffusion lengths smaller than the layer thickness can be measured.

New modulation SEM methods allowing the spatial resolution to be improved and large diffusion lengths in thin layers to be measured have been proposed. A program for the simulation of backscattering of electron signals from a profiled surface for registration in a limited range of energy and take-off angles has been developed. A backscattering electron spectrometer with the high energy resolution has been developed. A new approach to electron beam tomography has been developed.

The method of modulated EBIC (in contrast to conventional EBIC) allows depth resolution to be improved and a resolution with a better electron range to be obtained. The dependence of the backscattered electron spectra on the surface profile has been observed. By taking into account this dependence, it is possible to improve the reliability of reconstructing the surface profile.

Scientific Papers

Oxford Conference on Electron Microscopy 1995, BIADS 1993 (Italy), BIADS 1996 (Spain).

O.V. Kononchuk, N.G. Ushakov, and E.B. Yakimov, Determination of the Diffusion Length Profile by Variation in a Depleted Layer Width, Izv. Akad. Nauk USSR, Ser. Fiz., 1992, vol. 56, no. 3, pp. 53–57 (Transl. in Bulletin of the Russian Academy of Sciences, 1992, vol. 56, no. 3, p. 330).

N.N. Dryomova, A.P. Drokin, S.I. Zaitsev, E.I. Rau, and E.B. Yakimov, Multilayer Microstructure and Surface Relief Characterization in Backscattering Electrons in Scanning Electron Microscopy, Izv. Akad. Nauk, Ser. Fiz., 1993, vol. 57, no. 8, pp. 9–14.

V.V. Aristov, N.N. Dryomova, V.A. Kireev, I.I. Razgonov, and E.B. Yakimov, SEM Characterization of Multilayer Structures. Acta Phys. Polon. A, 1993, vol. 83, no. 1, pp. 81–86.

E. Yakimov, Modulated Electron-Beam-Induced Current and Cathodoluminescence, Mater. Sci. Eng., 1994, vol. B24, pp. 23–27.

O.V. Kononchuk and E.B. Yakimov, Measurements of Large Diffusion Length by the EBIC with Depletion Region Modulation, Izv. Akad. Nauk, Ser. Fiz., 1995, vol. 59, pp. 82–86.

V.V. Aristov, N.N. Dryomova, V.A. Kireev, O.V. Kononchuk, I.I. Razgonov, and E.B. Yakimov, Nondestructive Methods for SEM-Diagnostics of Planar Structures, Mikroelektronika, 1995, vol. 24, no. 1, pp. 71–76.

O.V. Kononchuk, G.A. Rozgonyi, and E.B. Yakimov, Measurements of Diffusion Length in Si–SiGe Structures, Solid State Phenomena, H. Richter, M. Kittler, and C. Claeys, Eds., Scitech. Public. Ltd., vol. 47/48, 1995, pp. 601–605.

V.V. Aristov, E.I. Rau, and E.B. Yakimov, Apparatus Electron Beam Microtomography in SEM. Phys. Status. Solidi A., 1995 vol. 150, pp. 211–219.

V.V. Aristov, E.I. Rau, and E.B. Yakimov, SEM Characterization of Multilayers, Inst. Phys. Conf. Ser., 1995, no. 146, pp. 675–680.

N.N. Dryomova, E.I. Rau, and E.B. Yakimov, Some Aspects of SEM-Profilometry in Backscattering Electrons, Izv. Akad. Nauk, Ser. Fiz., 1996, vol. 60, pp. 101–104.

E.B. Yakimov, SEM-EBIC Investigations of Thin Films and Low-Dimensional Defects, Phys. Low-Dimens. Structures, 1996, vol. 1/2, pp. 1–182.13. E.I. Rau and E.B. Yakimov, E-beam Tomography of Planar Semiconductor Structures, Mater. Sci. Eng., 1996, vol. 42, no. 1/3, p. 52.

№ -0123 Microscopic X-Ray Fluorescent Tomography Based on X-Ray Optics

Full Title:	Development of Methods and Devices for Microscopic X-Ray Fluorescent Tomography Based on the Use of X-Ray Optics
Technology Field(s):	PHY-OPL: Physics / Optics and Lasers CHE-RAD: Chemistry / Photo and Radiation Chemistry

Contributors

Vasily A Shelokov

CCB "ALMAZ" (ALMAZ) 80, Leningradskii pr., Moscow, 111024, Russia Phone: 7+095+1759410; 7+095+2619581 Fax: 7+095+1585671; 7+095+2619581

Present Status of Research

Brief Description of Research

It is proposed to elaborate nondestructive methods for 3D reconstruction of the distribution of some admixture in a sample on the basis of processing X-ray fluorescent signals obtained by scanning on the sample with a focused X-ray beam. This includes methods which exclude the necessity of rotating the sample. The admixture may have a continuous distribution in the sample or be in the form of a set of particles or clusters.

At present, some models of X-ray fluorescent signal formation have been created for various types of objects including objects containing spatially distributed nonhomogeneities. Some approaches have been worked out for solving the corresponding inverse problems (see [5]–[8]).

The possibility for nondestructive analysis of nearsurface layers will be achieved for bulk samples, to which traditional tomographic methods cannot be applied.

Local nondestructive analysis of small concentrations of an admixture and exclusion of mechanical movement (rotation) of the investigated sample for 3D reconstruction of its interior structure will also be achieved.