The results of studies of the changes in the electrophysical parameters of PIN photodiodes made on monocrystalline silicon wafers of the p-type of conductivity of orientation (100) with ρ = 1000 Ohm cm, when irradiated with γ-quanta from a 60Co source, are presented. It is established that as a result of the irradiation of the PIN photodiodes doses up to 2 × 1015 quanta/cm2 results in an increase in the reverse dark current by more than an order of magnitude. However, the shape of the curve of the dependence of the current on the applied reverse voltage of irradiated PIN photodiodes does not change qualitatively, just as for the original devices, there are three regions with different dependencies of the current on voltage—sublinear, superlinear, and linear—caused by different mechanisms of the generation-recombination processes in the depletion region of the p–n transition. The main reason for the increase in the reverse current of PIN photodiodes as a result of the irradiation of γ-quanta is the formation of the generation-recombination centers of radiation origin due to the condensation of the primary radiation defects (vacancies and/or self-interstitial atoms) on the technological residual structural defects formed both during the growth of silicon single crystals and during subsequent high-temperature treatments during the formation of devices.

The results of studies of electrophysical parameters of pin-silicon-based photodiodes, depending on their operating modes (external bias and temperature), manufactured on single-crystal silicon wafers of p-type conduction orientation (100) with ρ = 1000 ohm cm, are presented. The p+-type region (isotype junction) is created by the implantation of boron ions; the n+-type region, by the diffusion of phosphorus from the gas phase. It is established that on the voltage-current characteristics under reverse bias, three regions of dark current variation depending on the applied voltage can be distinguished, sublinear, superlinear, and linear, caused by various mechanisms of the generation-recombination processes in the depletion region of the pn‑junction. A noticeable dependence of the barrier capacitance value (at a frequency of 1 kHz) and the size of the depletion region on temperature is observed only when the applied reverse voltages do not exceed the contact potential difference (V ≤ 1 V).

An algorithm for solving the inverse problem of multiangle spectrophotometry of an inhomogeneous absorbing film is developed, which is based on polynomial representations of the density of the film material and its complex refraction coefficient. The algorithm is applied to determine the spectral and spatial distributions of the refractive index and absorption coefficient of a barium titanate film doped with europium. The film is deposited on a silicon dioxide layer on a silicon substrate using a sol–gel technology. The correctness of the obtained solution is verified by comparing the calculated and measured spectra of ellipsometric angles and the spectra of reflectance of the structure at normal incidence of light. Doping of barium titanate with europium leads to a decrease in the wavelength corresponding to the intrinsic absorption band edge, an increase in the band gap width of the material in the near-surface layer of the film, and a decrease in the concentration of europium deep into the film.

REFLECTION SPECTRA OF Γ-IRRADIATED FILMS OF DIAZOQUINONE-NOVOLAK PHOTORESIST S. VABISHCHEVICH, N. VABISHCHEVICH, D. BRINKEVICH, A. KHARCHENKO, M. LUKASHEVICH, V. PROSOLOVICH, S. BRINKEVICH

Разработан алгоритм решения обратной задачи многоугловой спектрофотометрии неоднородной поглощающей пленки, основанный на полиномиальных представлениях плотности материала пленки и его комплексного коэффициента рефракции. Алгоритм применен для определения спектральных и пространственных распределений показателей преломления и поглощения пленки титаната бария, легированного европием. Пленка нанесена по золь-гель-технологии на слой диоксида кремния, находящийся на кремниевой подложке. Корректность полученного решения проверена сравнением рассчитанных и измеренных спектров эллипсометрических углов и спектров отражательной способности структуры при нормальном падении света. Легирование европием титаната бария приводит к уменьшению длины волны, соответствующей краю полосы собственного поглощения, увеличению ширины запрещенной зоны материала в приповерхностном слое пленки и снижению концентрации европия вглубь пленки. Ключевые слова: многоугловая спектрофотометрия, эллипсометрия, неоднородный поглощающий слой, оптические характеристики титаната бария, легированного европием.

It is established that the electrophysical characteristics of MOS transistors largely depend on the quality of a gate dielectric. The presence of an extra built-in charge in the dielectric and fast surface states at the SiO2/Si interface leads to both an increased threshold voltage and decreased saturation current and voltage, decreased slopes of the characteristics of the MOS transistor in the linear and saturation regions, and a decreased structure conductance in the linear region. The gate leakage currents also increase. It is shown that the view and shape of the capacity–voltage characteristics are determined by the value of an extra positive charge in the bulk of the dielectric and the density of fast surface states at the Si/SiO2 interface. These values are correlated to the profile of the distribution of the surface concentration of the process-related impurities adsorbed at the wafer surface during the manufacturing of the device, which allows us to judge the quality of the materials used, adherence to the production conditions, and, if necessary, correct them opportunely as required.

ВЕСЦІ НАЦЫЯНАЛЬНАЙ АКАДЭМІІ НАВУК БЕЛАРУСІ № 4 2014 СЕРЫЯ ФІЗІКА-ТЭХНІЧНЫХ НАВУК УДК 621.382В. Б. ОДжАЕВ 1 , А. н.ПЕТЛИцКИЙ 2 , В. С. ПРОСОЛОВИЧ 1 , А. С. ТУРцЕВИЧ 2 , С. В. ШВЕДОВ 2 , В. А. ФИЛИПЕнЯ 2 , В. В. ЧЕРныЙ 3 , В. Ю. ЯВИД 1 , Ю. н.ЯнКОВСКИЙ 1 , В. А. ДУБРОВСКИЙ 1 ВЛИЯНИЕ ТЕХНОЛОГИЧЕСКИХ ПРИМЕСЕЙ НА ЭЛЕКТРОФИЗИЧЕСКИЕ ПАРАМЕТРЫ МОП-ТРАНЗИСТОРА 1 Белорусский государственный университет, 2 Открытое акционерное общество «ИнТЕГРАЛ» -управляющая компания холдинга «ИнТЕГРАЛ», 3 Белорусский национальный технический университет (Поступила в редакцию 13.03.2014

Radiation-induced processes taking place at boron and phosphorus ions implantation in the positive FN9120 diazoquinon-novoloc photoresist films on silicon were studied by the method of IR- Fourier spectroscopy of frustrated total internal reflection. It was established, that strengthening of photoresist adhesion to monocrystalline silicon is caused by the formation of ester linkages between hydroxyl groups on the surface of oxide layer of silicon wafer and carboxylic groups of 1H-inden-3-carbohylic acid.

Using the method of IR-Fourier spectroscopy of attenuated total internal reflection (ATR) we studied the radiation-induced effects in thin films of diazoquinon-novoloc photoresists on the silicon substrate under the irradiation with 5 МeV electrons. It is established that electron irradiation in a dose above 3·10 15 cm -2 leads to a decrease in the integral absorption in the wave numbers range 3700-400 cm -1 . The intensity of the bands associated with -O-H oscillation and especially aliphatic -C-H bonds decreases the most. At a dose of 1·10 17 cm -2 , the intensity of the bands related to methylene (-CH 2 -) and methyl (~CH 3 ) groups is comparable to the noise level. The intensity of the band ~ 1600 cm -1 , caused by stretching oscillations of the aromatic ring, does not change in the entire dose range 3 • 10 14 cm -1 • 10 17 cm -2 . The experimental data obtained indicate intense crosslinking of the polymer components ofphotoresists upon electron irradiation. It is found that the radiation-induced changes in ATR spectra depend on the type of photoresist (FP9120, S1813 G2SP15). The experimental regularities of changes in the optical characteristics of thin photoresist films irradiated with electrons are explained with respect to the peculiarities of the radiation chemistry of diazoquinon-novolac resins.

The interaction between Sb atoms and micropores of a getter layer in silicon is studied. The getter layer was obtained via implantation of Sb+ ions into silicon and subsequent heat treatment processes. The antimony atoms located in the vicinity of micropores are captured by micropores during gettering annealing and lose its electrical activity. The activation energy of capture process to the pores for antimony is lower than that of antimony diffusion in silicon deformation fields around microvoids on the diffusion process.

AbstractThe interaction between Sb atoms and micropores of a getter layer in silicon is studied. The getter layer was obtained via implantation of Sb^+ ions into silicon and subsequent heat treatment processes. The antimony atoms located in the vicinity of micropores are captured by micropores during gettering annealing and lose its electrical activity. The activation energy of capture process to the pores for antimony is lower than that of antimony diffusion in silicon deformation fields around microvoids on the diffusion process.

The algorithm is developed for solving the inverse problem of multiangular spectrophotometry of a layer on a plane-parallel substrate of finite thickness using s and p waves. The algorithm allows investigating dispersion properties of the layer and substrate both in the vicinity and far from the resonant wavelengths. The dispersion properties of the layers of pure and aluminum-doped zinc oxide on a glass substrate are investigated. It is shown that the doping leads to a shift in the maximum of the absorption band to the short-wavelength region and to a decrease in the refractive index of the material. The applicability of known approximate expressions for determining the spectrum of the absorption index of a layer from spectrophotometric data is estimated.

Using data of multiangle spectrophotometry and spectral ellipsometry in the UV and visible ranges, spectra of the refractive indices and absorption coefficients and width of the forbidden band of one- and five-layer strontium titanate films obtained by the sol–gel method have been calculated. Layer-by-layer deposition of sol on quartz substrates, from one to five layers, leads to an increase in film porosity from 4 to 33%. This causes a decrease in the refractive indices in the middle part of the visible spectrum from 2.33 to 1.87, which leads to a decrease in the reflectance and an increase in the transmittance or transparency of five-layer films. With an increase in the heating temperature of such films from 500 to 750°C, a shift of the absorption band maximum from 239 to 253 nm takes place and the optical width of the forbidden band decreases from 4.63 to 4.20 eV. The absorption band maximum of the single-layer film falls on the wavelength of 252 nm, and its optical width of the forbidden band is 3.96 eV.

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-р-n-transistors. Revelation of the causes of the labile reproducibility of the basic characteristics of the bipolar planar n-р-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-р-n-transistors, fabricated under the epitaxial-planar 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-р-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.