We demonstrate significant improvement of the radiation immunity of the integrated circuits based on silicon bipolar transistors. Strong decrease of the current gain degradation and significant yield improvement after high-energy gamma irradiation are both shown. This was achieved by development of efficient hydrogenation process for the silicon bulk and the surface dielectric layer using electron cyclotron resonance (ECR) plasma, as well as implementation of effective Si-wafer gettering option. Keywords: integrated circuits, bipolar transistors, ECR-plasma, hydrogenation of semiconductor structures, trap state passivation, gettering of semiconductor wafers, γ-irradiation, radiation hardness, yield of workable transistors.

This paper presents the results of hydrogen electron-cyclotron resonance (ECR) plasma in microelectronics technology. Its effect on the radiation resistance of the IC and on the quality of the ohmic contact during the formation of UBM metallization is demonstrated. The devices obtained with the use of plasma ECR and without it are analyzed.

A spiral phase plate with a topological charge of 1 is fabricated via 3D femtosecond laser submicron lithography. An optical scheme based on a Michelson interferometer is developed and assembled to check the vortex properties of a generated laser beam. Optical measurements confirm that the spiral phase plate generates an optical laser vortex with a normalized orbital angular momentum of | m | = 1. A technology for fabricating and testing spiral phase plates that transmit the required orbital angular momentum to the laser field is developed.

Performance of a detector based on AlGaAs/InGaAs/GaAs-material system was studied. The detector was comprised of large serpentine array of high-electron mobility transistors (HEMTs) connected in series. The floating drain contact of each transistor (except the last one) served as a source for the next one. Detection of terahertz (THz) radiation was based on the excitation of electron plasma oscillations in the HEMT's channel. The peculiarities of THz response of the detector in question including an enhanced noise-equivalent power were demonstrated.

THz response of AlGaAs/InGaAs/GaAs HEMT structure has been investigated. The structure consists of the serpentine chain of series connected HEMTs. The source of one is the drain for the subsequent transistor. Experiments have been showed THz response peculiarities of such structures and enhanced noise equivalent power.

Array of field-effect transistors (FET) with asymmetric T-gates and floating electrodes fabricated on a single chip was used as terahertz (THz) detector. Nonresonant detection with strong photovoltaic response was realized due to excitation of electron plasma oscillations in the common channel of the FETs array. Voltage responsivities obtained by the array of FETs with floating electrodes surpass the photoresponse reported for the array of FETs connected in series by external wiring.

An array of GaAs/InGaAs/AlGaAs field-effect transistors with an asymmetric T-gate in each transistor and floating electrodes was fabricated on a single chip and tested as a detector of terahertz (THz) radiation. Principle of detection was based on excitation of plasma oscillations in the common electron channel of the FETs array. Strong terahertz photovoltaic response was demonstrated without any supplementary antenna. Voltage re-sponsivities above 1000 V/W and up to 2000 V/W were obtained at zero (unbiased mode) and positive (directed from drain to source - biased mode) dc currents in the FETs array channel, respectively, surpassing the photorespponse demonstrated by the array of FETs connected in series by external wiring [5].

Detection of terahertz radiation by GaAs transistor structures has been studied experimentally. The two types of samples under study included dense arrays of HEMTs and large-apertures detectors. Arrays consisted of parallel and series chains with asymmetric gate transistors for enhanced photoresponse on terahertz radiation. We investigated two types of wide-aperture detectors: grating gate detector, and single gate detector with bow-tie antenna. Wide-aperture detectors were symmetrical. Studies of transistor chains have shown that two essential features for this type of detector are the presence of asymmetry in the gate, and the type of connection between individual transistors themselves. Wide-aperture detectors have also been tested by narrow beams of terahertz radiation, which allows analyzing the role influence of individual parts of the detector for total sensitivity to terahertz excitation. The sensitivity and noise equivalent power of the detectors were evaluated.

Dependence of the chemical composition of a film of plasma-chemical silicon nitride on the technological parameters of the deposition process is studied. The stages in which the process parameters are optimized in order to improve the masking properties of the film are described. A systematic study of the Fourier-transform infra-red (IR) spectra of plasma-chemical silicon-nitride films is carried out. It is found that the chemical resistance of a silicon-nitride film depends on the configuration in which hydrogen is incorporated into chemical bonds.

Terahertz response of wide-aperture plasmonic detectors is studied experimentally by using a focused terahertz radiation with frequencies 1.63, 1.89 and 2.55 THz. Two different types of plasmonic detector have been investigated: (i) field-effect transistor (FET) with a grating-gate of large (2x2 mm2) area and (ii) FET with a single gate and ohmic contacts forming a bow-tie antenna. By raster scanning the detector area by using a tightly focused terahertz beam, we studied the contribution of individual parts of the detector to the total detection response and we determined the effective area of the detector structures.

Terahertz (THz) detection by a one-dimensional array of series connected field-effect transistors (FETs) is studied experimentally. Such terahertz detector demonstrates greatly enhanced voltaic responsivity up to 2 kV/W. Asymmetrical position of the gate contact in each FET in the array enables strong photovoltaic response.

A tightly concatenated chain of InGaAs field-effect transistors with an asymmetric T-gate in each transistor demonstrates strong terahertz photovoltaic response without using supplementary antenna elements. We obtain the responsivity above 1000 V/W and up to 2000 V/W for unbiased and drain-biased transistors in the chain, respectively, with the noise equivalent power below 10−11 W/Hz0.5 in the unbiased mode of the detector operation.

We have fabricated a grating-gate InGaAs/GaAs field-effect transistor structure with narrow slits between the grating gate fingers. The resonant photoconductive response of this structure has been measured in the sub-terahertz frequency range. The frequencies of the photoresponse peaks correspond to the excitation of the plasmon resonances in the structure channel. The obtained responsivity exceeds the responsivity reported previously for similar plasmonic terahertz detectors by two orders of magnitude due to enhanced coupling between incoming terahertz radiation and plasmon oscillations in the slit-grating-gate field-effect transistor structure.

Terahertz detection by a one-dimensional dense array of field-effect transistors (FETs) is studied experimentally. Such terahertz detector demonstrates greatly enhanced responsivity without using supplementary antenna elements because a short-period grating formed by metal contact fingers of densely ordered transistors in the array serves as an effective antenna coupling incident terahertz radiation to the transistor channels. Asymmetrical position of the gate contact in each FET in the array enables strong photovoltaic response.

Terahertz photoresponse of a GaAs/InGaAs transistor structure with large-area slit grating gate has been measured. Peaks in the photoresponse curve are assigned to plasmon resonances excited in the structure. More effective excitation of plasmon resonances is achieved in a grating gate structure with narrow slits, which increase the photoresponse amplitude by an order of magnitude.

Resonance detection of terahertz radiation by nanometer field-effect transistors GaAs/AlGaAs and transistor structure GaAs/InGaAs with large area slit grating gate has been measured. For these transistors peaks in the resonance photoresponse curve are tunable with gate voltages in accordance with the Dyakonov-Shur theory.

The interphase boundary formed in the process of tungsten thin-film deposition on a silicon wafer is investigated. These films are produced via (1) a CVD technique relying on hydrogen reduction of tungsten hexafluoride, (2) the same technique supplemented with plasmochemical action, and (3) magnetron deposition used for comparison purposes. It is shown that a nanometer tungsten silicide W5Si3 layer is formed at the tungsten-silicon interface only under gas-phase deposition. The effect of annealing on the specimen composition and surface resistance is investigated. It is shown that the formation and growth of a silicide WSi2 layer commences at 700°C for CVD films and at above 750°C for films obtained with plasmochemical deposition; this results in a drastic increase in their electrical resistance. Under optimal conditions, tungsten films of 8 × 10 −6 Ω cm resistivity are produced.