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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 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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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 technology of forming the carbon emitters for the integrated field emission elements has been developed. The studies have revealed the modes of preparing various film structures of carbon: diamond, graphite, graphene-like. The low-temperature method for producing the ultrafine diamonds has been developed. The high-emission properties of the nanodiamond-graphite emitters have been provided due to the effect of self-organization of diamond nanocrystals in graphite films during deposition at low pressure vapor of ethanol using a highly-nonequilibrium microwave plasma.
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The tricky optimization procedure of silicon-on-sapphire heteroepitaxy is one of the restricting factors to widespread utilization of the silicon-on-sapphire (SOS) wafers. In order to eliminate the given technological barrier in the work the process of gas-phase forming the silicon initial layer on the sapphire R-plane has been investigated. The parameters of the manufactured layers have been analyzed using the production methods of the quality control as well as by XRD, SEM and Raman spectroscopy. The resistivity profiles of the SOS layers have been obtained by the specific resistance spreading method (SPR). It has been shown that the execution of the initial stage of growing at 910–930 °C results in reduction of the silicon layer autodoping by aluminum from the substrate. The heat treatment of the initial layer, formed at 945–965 °C enables to obtain the SOS structures of high structural quality in a wide temperature range of the main layer deposition 960–1005 °C. A comparison of the SOS structures, obtained at the optimal parameters of the investigated technique and in the standard process has demonstrated a reduction of the full width half maximum of rocking curve to ~0.24, the reduction of mechanical stresses of compression up to 0.8–1.96 GPa, the homogeneity of the specific resistance profile up to 180–350 nm depth. Due to the application of the developed technological techniques the homogeneity of the SOS control parameters within the process significantly has increased, which has enabled to improve the productivity of the manufacturing process.
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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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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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Manufacturers of plastic packages use high silica filler epoxy molding compounds to reduce the difference in coefficient of thermal expansion between the die and the encapsulation material. However, in addition to the die, commutation substrate has a significant effect on the thermo-mechanical stresses level in the package. Three-dimensional integration makes it possible to combine several substrates, which can be made from various dielectrics, in a one microassembly with the help of a vertical volume commutation. This work shows that the use of capsulation materials with different thermal expansion coefficient in the outer and inner parts of the product can reduce the level of temperature stresses in such a structure. The dependences of the thermo-mechanical stress and deformation on the number of levels and the amount of filler in the external compound were established. This study was carried out by means of computer simulation for various designs of microassemblies capsulated with compounds characterized by different values of temperature and mechanical parameters. The dependences obtained in the article allow us to establish optimal values of filler content in the external and internal compounds to ensure minimal thermal and mechanical (under the influence of acceleration) deformation of microassemblies with different levels.
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In this work, a lot of attention has been paid to the study of the processes of degradation, failure mechanisms, analysis of the processes of chemical kinetics and its effective models for determining the reliability of products microsystem technology (MST) from the viewpoint of statistical thermodynamics. The first attempt to use a modified Gibbs equation in the form Semenchenko for the objectives of the study of mechanisms failures MST products has been made.
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The possibility of applying porous silicon in creation of varicaps with high capacitance ratio, satisfying the requirements of microelectronic and macrosystem technology, has been investigated. The capacitor structures using the copper galvanic deposition to porous silicon pores have been presented. The morphological features of the experimental structures have been studied, the specific capacitance of varicaps has been determined. The obtained results demonstrate the prospects of application of varicaps based on porous silicon in integrated electronics.
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The possibility of using the macroscopic laws of (classical) thermohydrodynamics and its space-time limitations in modeling heat transfer from micron-sized MEMS micromirror elements of different geometry has been discussed. The main objectives of the modeling is to determine the performance of MEMS micromirror and the direction of ways to optimize these parameters. An example of practical testing of heat transfer model of thermo-mechanical actuator, which is a part of the micromirror MEMS, has been provided. The modelling results have been justified by the adequacy with the experimental testing.
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