Сергей Петрович Тимошенков
Dr. Sci. (Eng.) Prof., Director of the Institute of Nano- and Microsystem Technology, National Research University of Electronic Technology (Russia, 124498, Moscow, Zelenograd, Shokin sq., 1)

Article author

The dependencies of deep silicon etching performances on the process parameters have been investigated. To find the optimal recipes, which provide a high selectivity to a mask and the ARDE decrease, the method of planning the multifactorial experiments has been utilized. The investigation results have been used for manufacturing the MEMS real structures.

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The surface of silicon on sapphire (SOS) epitaxial layers have been investigated by the atomic-force and UV scattering methods. The X-Ray-structural analysis of SOS has been performed. The transient area silicon-sapphire has been studied by photo-EMF method. The problem of accumulating the silicon synthesis secondary products has been considered and experimentally confirmed. It has been found that the addition of the chlorides containing reagents into the epitaxy process permits to exclude the influence of these products on the growing layer and, also, to modify the surface microrelief. The studies on the SOS surface and layers structure have enabled to determine that the growth of films is realized according to the Stranski-Krastanov mechanism. It has been shown that the combined method contained in the preliminary growing of the SOS layer of 30-60 nm thickness from pure SiH and further layer growing with the ratio of gas components consumptions 2SiH:1SiC1 is a more preferable method of manufacturing SOS with the layer thickness from 300 nm and more.

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The main factors determining the requirements for packaging of micromechanical devices and systems (MEMS) have been shown. The methods of processing materials and creating three-dimensional structures, used in the microsystem engineering, have been analyzed in connection with MEMS packaging. Various technological options for vacuum packaging of Microsystems and the tendencies in this field development have been considered.

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Currently, the traditional use of varnish-foil dielectrics for manufacturing resistors, resistive assemblies and heating elements has been supplemented by their application in production of thermal resistors, the membranes of acoustic and photoelectric transformers. As a rule, the non-adhesive foil dielectrics sustain the affect of high temperatures, permit to significantly increase the density of elements and have better quality characteristics, because the adhesives have negative effect upon the electrical characteristics of the materials, manufactured with their application. Also, the adhesives have comparatively low thermal resistance, which manifests on the total thermal resistance of foil dielectric and the items manufactured on it, especially in case when as a base polyimide is used. In the paper the flexible foil dielectrics for electronic equipment and their manufacturing technology have been considered. The advantages of the non-adhesive foil dielectrics with complete imidization of the polymer base have been shown. The technology of manufacturing the varnish-foil dielectrics, used in manufacturing highly reliable microcircuits of modification 2 and of highly technological membranes of acoustic transformers, has been developed. The polyimide base of the dielectrics has high adhesion to foil and the guaranteed uniformity of the imidization extent 95-100 %. This provides the stability of technological conditions in the process of manufacturing the items from the given materials, as well as an increase of the storage life of the varnish-foil dielectrics up to 12 months.

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The most significant factors of reliability and durability of a microelectronic module are the design and technology of brazed and adhesive bonding, the elastic strength and plastic properties of the materials of silicon crystal, solder and glue joint. The construction to be created is designed to reduce the weight and size characteristics, to increase the reliability and to ensure the efficient heat dissipation. In the work, when simulating the stress-strain state of the microconnections of microelectronic modules, it has been determined that in tin- bismuth solder the stresses in the assembly materials are distributed more evenly and their value is significantly lower than when using SnPb and SnZn solder: in silicon by 5-30%, in copper conductor by 20-90%. It has been determined that under operating conditions and tests at the elevated temperatures, the voltage in the SnBi solder is 1.5 and 2.2 times lower than in the SnPb and SnZn solder, respectively. It has been shown that the epoxy glue cold curing has good adhesion to various structural materials, low labor intensity of the process and high durability. The rational thickness of glue seam 50-200 microns and a copper conductor of 20 microns has been determined. The recommendations on the design of microconnections of microelectronic modules have been given.

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