Method for forming a titanium-germanium contact layer for thermostabilization of transistors

Objective. The objective of the study is to obtain high-quality and reproducible electrophysical parameters of thin-film metal layers, the formation technology of which determines the reliability and quality of microelectronic products – silicon transistors.Methods. A method for forming a two-layer titanium-germanium metallization to create a contact and remove heat from the collector junction of high-power semiconductor transistors on the reverse side of plates with formed structures is proposed. The proposed method ensures the quality of the soldered connection and thermal stabilization of semiconductor devices, increasing the reliability of the studied devices in radio electronic equipment systems.Results. This combination of sprayed metals provides a reliable contact to the collector area when the crystal is placed on the base of the case, which reduces the resistance of the ohmic transition and increases the output of suitable devices.Conclusion. Based on the results of experimental procedures, the optimal thicknesses of metal layers deposited on the reverse side of transistor crystals were obtained during the formation of metallization to fit crystals on the base of the case. The Ti-Ge system stability is studied. The technical result of the research is to improve the quality of planting by obtaining a uniform distribution of the Ti-Ge layer in a single technological cycle at a given temperature with a certain thickness for each metal separately.

CALCULATION OF NON-STANDARD W-PARAMETERS OF FOUR-POLE ON BIPOLAR TRANSISTORS

Improving the performance of microwave devices can be achieved both through the use of a fundamentally new element base, and through the use of new circuit designs. In this respect, the direction of use of the reactive properties of transistors as well as transistor structures with negative resistance for the construction of information-measuring systems and operating and computing devices of the microwave range is promising in this respect. In order to confirm the proposed methods, it is necessary to compare the results of the experimental studies using the proposed methods and means of measuring the W-parameters of real potentially unstable four-poles. As such four-poles it is proposed to use bipolar and transistors with a wide range of frequencies of potential instability. The paper develops mathematical models of W-parameters of such structures and evaluates their parameters in the frequency range. The active four-pole is a transistor model. Its W parameters can be determined either experimentally - for specific conditions or calculated - by using a physical transistor replacement circuit. In most cases, the calculation path is more acceptable because it allows to obtain analytical expressions for the four-pole, it is important in the analysis of the influence of various factors on the characteristics of the scheme under study. The inertial properties of the transistor are already manifested at relatively low frequencies and must be taken into account in practically the entire operating range of the transistor. The theoretical model holds up to frequencies f  2fт (where ft is the limit frequency) [1,3]. At higher frequencies, it is necessary to consider the parasitic reactive parameters of real transistors, first of all, the inductance of the terminals. A physically T-equivalent equivalent transistor replacement scheme was proposed by Pritchard in a simplified version [4]. It has several varieties, differing in the configuration of the circuit consisting of the resistance of the base material and the capacity of the collector junction. If we carefully consider and compare the T and U-shaped circuits of the transistor substitution, it can be noticed that they differ only in the configuration of their inne r part - the theoretical model. At high frequencies P and T, such circuits are not exact mutual equivalents. This is due to the approximation used in the transition from one circuit to another. However, the frequency characteristics of the circuits are very close. Each of them models the processes in the transistor with approximately the same accuracy, and in this sense they are equivalent.

Principles of synergetics in training of specialists physical and technical profile

The article discusses the use of the basic principles of synergetics in the training of physicists in the study of the discipline «Physical Electronics». The work is based on many years of experience in teaching the discipline at the Department of Radiophysics and Electronics of Karaganda State University named after E.A. Buketova. It is shown that the system «semiconductor structure + external source of electrical energy» can be considered as an open nonequilibrium thermodynamic system in which cooperative processes of spontaneous self-organization due to the constant exchange of energy and matter develop. The physical processes in bipolar transistors in the active mode of operation are analyzed. By means of a qualitative theoreti- cal analysis, it was established that the system under consideration interacts with self-organizing processes that result in spontaneous lowering of the potential barrier in the emitter region and an increase in similar barter in the region of collector junctions; spontaneous injection of minority charge carriers into the base is observed, resulting in a spontaneous increase in the concentration of minority charge carriers in the base layer adjacent to the transition. Spontaneous transfer of charge carriers through the base to the collector causes a spontaneous decrease in the collector junction resistance to the resistance of a forward-biased emitter junction, etc. All of the above processes determine the spontaneous redistribution of the voltage of the power source, as a result of which the power at the output of the transistor begins to exceed the power at its input, i.e. A bipolar transistor will amplify the power.

Effect of Hole Extraction from the Base Region of a Silicon p–n–p Transistor on its Reactive Impedance

Transistor structures are the basic elements of integrated circuitry and are often used to create not only transistors themselves, but also diodes, resistors, and capacitors. Determining the mechanism of the occurrence of inductive type impedance in semiconductor structures is an urgent task, the solution of which will create the prerequisites for the development of solid-state analogs of inductors. The purpose of the work is to establish the effect of extraction of non-equilibrium charge carriers from the base region on the reactive impedance of a bipolar p–n–p transistor.Using impedance spectroscopy in the frequency range 20 Hz–30 MHz, the structures based on p–n–p transistors KT814G manufactured by JSC “INTEGRAL” were studied. It is shown that in the transistor structures it is possible to observe the “effect of negative capacitance” (inductive type impedance). It is established that the most probable cause of the inductive type impedance is the accumulation of uncompensated charge of holes in the base, the value of inductive impedance is influenced by both the injection efficiency in the base–emitter junction and the extraction efficiency in the base–collector junction.The results can be applied in the elaboration of technologies for the formation of elements of silicon based integrated circuits with an impedance of inductive type.

INVESTIGATION OF INFLUENCE OF TECHNOLOGICAL IMPURITIES ON THE I–V CHARACTERISTICS OF THE BIPOLAR n–p–n-TRANSISTOR

Contamination of the monocrystal silicon with technological impurities in the devices fabrication process exerts a considerable influence on the electro-physical characteristics of the bipolar n–p–n-transistors. Revelation of the causes of the labile reproducibility of the basic characteristics of the bipolar planar n–p–n-transistors is vital for the purpose of establishing the factors, determining reliability and stability of the operational parameters of the integrated circuits. There were investigated I–V characteristics of the various lots of the bipolar n–p–n-transistors, fabricated under the epitaxialplanar technology as per the similar process charts with the identical used technological materials, however, at different times. It is established that the electro-physical characteristics of the bipolar n–p–n-transistors substantially depend on the contents of the technological impurities in the substrate material. Availability of the high concentration of the generation-recombination centers, related to the metallic impurities, results both in increase of the reverse current of the collector – base junction of the transistors and the significant reduction of the breakdown voltage of the collector junction. The most probable cause of deterioration of the electro-physical parameters of the bipolar n–p–n-transistors is the material contamination with the technological impurities (such, as Fe, Cl, Ca, Cu, Zn and others) during the production process of the devices fabrication. The sources of impurity may be both the components and sub-assemblies of the technological units and the materials and reagents under usage.

Modelling of ionization effects and the effects of displacement in digital chips for CAD

The methods of design of digital fault-tolerant bipolar integrated circuits to exposure to radiations such as gamma, x-ray and neutron radiation are considered, as well as the impact of the neutron pulse, which af-fect largely on the gain of the transistor. The operating mode of integrated circuits with change in the ini-tial values of voltages, as well as currents of the emitter and of the base is presented. Numerical calcula-tions of the ionization current in the base-collector junction are considered which allow pre-calculate dose rate of gamma, x-ray and neutron radiation.

Temperature-Dependent Logic Failure in a GaAs Power Amplifier-Duplexer Module Caused by a Subtle Parasitic Schottky Diode

A single power amplifier-duplexer device was submitted by a customer for analysis. The device was initially considered passing when tested against the production test. However, further electrical testing suggested that the device was stuck in a single power mode for a particular frequency band at cold temperatures only. This paper outlines the systematic isolation of a parasitic Schottky diode formed by a base contactcollector punch through process defect that pulled down the input of a NOR gate leading to the incorrect logic state. Note that this parasitic Schottky diode is parallel to the basecollector junction. It was observed that the logic failure only manifested at colder temperatures because the base contact only slightly diffused into the collector layer. Since the difference in the turn-on voltages between the base-collector junction and the parasitic Schottky diode increases with decreasing temperature, the effect of the parasitic diode is only noticeable at lower temperatures.