The article considers the physical-technological foundations of formation of the silicon dioxide (SiO 2 ) based electret for use in devices of MEMS technology. Studies have shown that the best electret properties are in SiO 2 obtained in «wet» oxygen medium as compared to samples obtained by other oxidation methods. This is probably due to the large number of Si-OH groups on the surface of the oxide in the «wet» SiO 2 , which increases the effectiveness of the hydrophobic coatings during the modification of the SiO 2 surface. It has been found that other methods of obtaining oxide, for example, electrochemical or plasmachemical, do not make it possible to obtain SiO 2 with good electret properties. The decrease of the charge injected into an electret can occur due to the presence of volume or surface conductivity, as well as the screening of this charge by opposite charges from the medium, leading to significant decrease of electret surface potential at high ambient humidity. To increase the stability of the electret effect, it is necessary to perform water-repellency treatment of SiO 2 surface by applying thin (nanosized) water-repellent coatings. Experimental results on the stability of the electret surface potential are presented for usage of various water repellents. The most promising water repellents are high-temperature photoresist FPT-1-40 and polyimide nanolayer compositions – Langmuir-Blodgett films.
Modeling ideas of physical and chemical processes when using an anodic bonding for materials connection are developed. The kinetics of a charge accumulation in an electrode region in a dielectric is considered. The thickness of a charge layer, electric fields strength and value of the ponderomotive pressure providing connection of materials are calculated. It is shown that the necessary ponderomotive pressure resulting in a dielectric-to-conductor seal is normally about ten megapascal and the time required is about ten minutes. The appearance of great pulling electric fields at anodic bonding process with a conductor surface to dielectric turns out to be possible due to the interlayer polarization developing in dielectric under the action of electric voltage. This results in a negative charge accumulation in a layer of small thickness beside anode. Thus applied electric voltage is distributed not through the whole thickness of a dielectric, but in fact is applied to a narrow area of the three-dimensional charge be-side anode. Arising strong electric fields force the connected materials to unite. The physical and mathematical models for force characteristics of non-uniform electric field are developed. Dependences of parameters of anodic bonding junction on time are considered. The expressions allowing to choose well-founded time of formation of anodic bonding junction are obtained, intensity of electrostatic fields and forces in dynamics is calculated. Research of a charge intermittence influence on electrostatic field strength has shown a considerable differences on small distances to the charged surface between carried out and traditional ways of calculation.
In this work a device for measurement at a constant voltage of the basic electric characteristics of high-resistance dielectric materials and products from them – their electric capacitance and resistance – is developed. The principle of work of the device is based on use of transients in connected in sereies elements having electric capacity and resistance. In the electric circuit of the device the mosfet with high entrance resistance is used. Possibilities of practical use of the device for measurement of surface electret potential, for rejection of potentially unreliable condensers, for diagnostics of corrosion of metal under a pro-tective dielectric covering are considered, etc.
The paper presents a number of experimental techniques for detecting in amorphous tantalum oxide films structural defects, which accelerate film destruction processes in a strong electric field and thus are potentially dangerous under prolonged thermoelectric stresses applied to capacitor structures. It is shown that the anomalous frequency dependence of dielectric losses and increase of the leakage current over time can identify potentially unreliable capacitors.
Physical processes that lead to the emergence of large forces of attraction between bodies, joined by anodic bonding technology result from the large electric fields strengths at the contact interface. Nondestructive method of monitoring the strength of obtained conductor-to ionic dielectric anodic bonding seals is based on the relationship between the dependence of current versus time flowing in the formation of seals and the strength of the resulting seals. Theoretically justified a new technological method for nondestructive testing of high-quality anodic bonding seals. The results obtained are confirmed experimentally.
The physical and mathematical model allowing to estimate force and power characteristics of non-uniform electric field in electroadhesive technologies is developed. The new processing method for making of qualitative conductive covering films on dielectric substrates with electrostatic field use is theoretically proved. The obtained results prove to be true experimentally.
The software for the procedure of definition of parameters of a cap of condenser structure with mobile facings on the basis of use of power action of an electrostatic field is considered. The offered technique allows on one operation of removal volt – capacitance characteristics to define the whole complex of the major parameters of a cap – size of a working air gap, a membrane deflection, electret surface potential and a membrane tension. The expressions for capacity of a cap as a function of specified parameters are obtained. The software is developed for the technique use, allowing to define required parameters of a cap and to estimate their error. The procedure considered in the present work is a not destroying monitoring.
The appearance of great pulling electric fields at anodic bonding process with a conductor surface to dielectric turns out to be possible due to the interlayer polarization developing in dielectric under the action of electric voltage. This results in a negative charge accumulation in a layer of small thickness beside anode. Thus applied electric voltage is distributed not through the whole thickness of a dielectric, but in fact is applied to a narrow area of the three-dimensional charge beside anode. Arising strong electric fields force the connected materials to unite. The physical and mathematical models for force characteristics of non-uniform electric field are developed. Research of a charge intermittence influence on intensity of an electrostatic field has shown a considerable differences on small distances to the charged surface between carried out and traditional ways of calculation.
Physical processes that lead to the emergence of large forces of attraction between bodies, joined by anodic bonding technology result from the large electric fields strengths at the ontact interface. Nondestructive method of monitoring the strength of obtained conductor-to ionic di- electric anodic bonding seals is based on the relationship between the dependence of current versus time flowing in the formation of seals and the strength of the resulting seals. Theoreti cally justified a new technological method for manufacturing of high-quality anodic bonding seals. The results obtained are confirmed experimentally.
The paper presents a number of experimental techniques for detecting in amorphous tantalum oxide films structural defects, which accelerate film destruction processes in a strong electric field and thus are potentially dangerous under prolonged thermoelectric stresses applied to capacitor structures. It is shown that the anomalous frequency dependence of dielectric losses and increase of the leakage current over time can identify potentially unreliable capacitors.
Emission parameters and coefficients of reflection of heat electrons from tungsten thermo cathodes were investigated under nontraditional for emission electronic conditions, when the surface contacts with highly ionized plasma. For measurements plasma diode electron current-magnetic field strength relations were used. Parameter Dj, which characterizes cathode heterogeneity by work function, and coefficient of reflection for policrystallic tungsten and for face 110 tungsten single crystal were measured. Proportion entering in effective reflection coefficient of electrons, reflected immediately from the surface and from potential barrier of spots field was determinate.
Procedure for definition of parameters of a condenser structure cap is considered. The procedure allows by means of one operation – volt – capacitance characteristic measuring – to define the whole complex of the major parameters of a cap – size of a working air gap, a membrane deflection, surface electret potential and a membrane tension. The expressions for capacitance of a condenser structure cap as a function of specified parameters are obtained. Analytical expression for capacitance of a cap depending on the specified parameters and measuring of its volt-capacitance characteristic allow to define these parameters by solving corresponding system of equations. The procedure considered in the present work is a not-destroying quality monitoring method.
In this work a device for measurement on a constant voltage of the basic electric characteristics of high-resistance dielectric materials and products from – their electric capacitance and resistance – is developed. The principle of work of the device is based on use of transients in connected in sereies elements having electric capacity and resistance. In the electric circuit of the device the MOSFET with high entrance resistance is used. The device on the basis of the MOSFET for measurement of surface potential of dielectrics is considered also. Use of this device is especially effective at measurement of electret surface potential. Results of research of electrets on a basis of silicon dioxide are discussed.
The appearance of great pulling electric fields at anodic bonding process with a conductor surface to ionic dielectric turns out to be possible due to the interlayer polarization developing in dielectric under the action of electric voltage. This results in a negative charge accumulation in a layer of small thickness beside anode. Thus applied electric voltage is distributed not through the whole thickness of a dielectric, but in fact is applied to a narrow area of the three-dimensional charge beside anode. Arising strong electric fields force the connected materials to unite. In the present work it is shown that use of the discussed technology allows to increase considerably adhesion of conducting films to dielectric substrates both in the process of their deposition and after it.
Some designs of capacitor sensors and actuators which work is based on electric field use are considered. It is shown that these designs are rather cheap in manufacturing, but thus possess good technical characteristics. The theoretical substantiation of possibility of electrostatic forces use for balancing of a pressure difference in the corresponding measuring device is adduced. Procedure for definition of parameters of a condenser structure cap is considered. The procedure allows by means of one operation – volt-capacitance characteristic measuring – to define the whole complex of the major parameters of a cap-size of a working air gap, a membrane deflection, surface electret potential and a membrane tension. Analytical expression for capacitance of a cap depending on the specified parameters and measuring of its volt-capacitance characteristic allow to define these parameters by solving corresponding system of equations. The procedure considered in the present work is a method of a not-destroying control.
The basic electric characteristics of dielectric materials and products from them are their electric capacitance and resistance. The purpose of work was development of an express train – technique and the inexpensive, mobile device for measurement of these parameters of highresistance materials on a constant voltage. The principle of work of the device is based on use of transients in connected in sereies elements having electric capacity and resistance. In the electric circuit of the device the MOSFET with high entrance resistance is used. Applications of the device are possible for: estimations of the controllable, specially created porosity of dielectric materials; measurements of humidity of wood, concrete and other porous, loose materials; revealings of impurity in small quantities in especially pure substances; revealing crystal orientations of monocrystals, etc.
A comprehensive analysis of modern methods used for diamond identification has been carried out. It is shown that high thermal conductivity cannot unambiguously testify to the authenticity of a diamond, since synthetic imitations of silicon carbide have recently appeared. It is shown that electrical methods of gemstone diagnostics are promising but not yet sufficiently developed. A set of innovative electrocalcium methods for diamond identification is proposed. Techniques for measuring high resistivity, dielectric permittivity and surface potentials, which can be used in the procedure of diamond identification, are developed. An operational model has been tested in the study of new and traditional dielectric materials. The possibility of detecting differences in electrical and physical properties of externally identical materials using this method is shown.
Methodological problems of electret transducer calculation are discussed. It is shown that the electret transducer insert is too complicated object for modeling. Therefore, it is necessary to make some simplifying assumptions in the model. For example, the transducer membrane is assumed to have a dome-shape. Since the amplitude of membrane oscillations is small, the object under consideration is studied in the linear approximation. A method of calculating the sensitivity of the electret microphone depending on the frequency of oscillation, transducer geometry, voltage and charge of the electret, etc. is proposed. The deflection of the membrane under the action of electrostatic forces is taken into account. It is shown that this procedure leads to a relatively simple analytically feasible solution. Application of the procedure allows to develop nondestructive testing methods for electret microphones, to optimize the design of electret microphones, to use the design of electret transducer in the educational process, etc.
