Electromagnetic impedance method of monitored semiconducting layers and studying biological objects

Abstract

A description is given of the chief stages and principles of the development (over more than a decade) of an electromagnetic impedance method for the investigation and parameter control of semiconducting layersepitaxial, diffusion structures, and metal film dielectric systems of electronic engineering -during their interaction with the fields of coaxial, waveguide, and capacitative-inductive radiators of various configurations in the millimeter, centimeter, and meter wavelength ranges.In the laboratory of nondestructive physical monitoring methods of the Physics-Power Engineering Institute of Latvian Academy of Sciences, work is being carried out during more than a decade on the foundation of radiowave eddy-current methods and equipment for the control and diagnostics of the formation of multilayer structures for semiconductor instruments, film materials and also components of UHF thin-film electronics. By means of it the impedance method of a comparative analysis of radiator fields, the authors have developed scientific foundations for the interaction of radiator fields with multilayer systems. This work has taken account of the wide range of variations in their thicknesses (0.01-100 /~m), and also their properties (dielectric, semiconductor and metal), and the necessity for using millimetric (instrument series PKP, SVP, SHF), centrimetric (SVPT, SIMP), decimetric (VEIS, VIIS), and metric (VTMS, VITN, VIP, VIMP) wavelength ranges.Well-known in radiowave, optical, and acoustic forms of monitoring, and widely used, are methods associated with reflected and scattered radiation. These methods are characterized by the use of wavelengths which are appreciably smaller than the distance to defective regions or to the boundaries being determined in the medium. However, with the use of waves the wavelengths of which exceed the distance between surface boundaries, there emerges a qualitatively different character in the interaction of physical fields with objects being monitored. The interaction may be determined by the input impedance, i.e., by the resistance to a flow of the appropriate form of energy [1][2][3].The development of the method includes theoretical computations of the dependences of the impedance for various layered structures and expressions for them, and also the development of methods for determining the necessary parameters from the measured impedance, and circuit solutions for the processing of the primary information, the construction of measuring instruments and a study of the methods in a stage by stage application of the range of instruments for controlling the processes of formation of structures with specified parameters [4].Computation of the electromagnetic impedance of nonuniform structures, determined by the ratio of the complex amplitudes of the tangential components of the electric and magnetic field intensities on its surface, reduces (after transformation of the general electromagnetic wave equation) to a computation of the Riccati equation. Staff members of the institute have developed a ...