New insight is provided into how runaway electrons are generated in gases. It is shown that the Townsend mechanism of electron multiplication works even for strong fields, when the ionization friction of electrons can be neglected. The nonlocal electron runaway criterion proposed in the work determines the critical voltage ± pd relationship as a two-valued function universal for a given gas (p being the gas pressure, and d the electrode spacing). This relationship exhibits an additional upper branch as contrasted to the familiar Paschen's curves and divides the discharge gap into two regions: one where electrons multiply effectively, and the other which they leave without having enough time to multiply. Experiments on the production of electron beams with subnanosecond pulse duration and an amplitude of tens to hundreds of amperes at atmospheric pressure in various gases are addressed, and the creation of a nanosecond volume discharge with the high density of excitation power and without preionization of the gap by a supplementary source is discussed.

The initial nucleation and coalescence of Cu by supercritical fluid deposition (SCFD) were monitored by measuring the surface reflectivity of visible white light. The reflectivity at 770 nm is sensitive to initial nucleation, thus, the nucleation and coalescence temperatures of Cu-SCFD can be easily monitored by this in situ technique. The nucleation temperature of Cu-SCFD was found to be independent of the precursor concentration, which suggests a strong adsorption and surface saturation of the source precursor at high concentration. A high H 2 concentration up to 0.39 mol/L with Cu(tmhd) 2 as a precursor can decrease the nucleation temperature from 215 to 180 C. A high H 2 concentration is also effective for realizing a smooth surface morphology of the deposited Cu film and for making the film thin at the coalescence stage probably because of the initial nucleation with a high number density. The fabrication of a 10-nm-thick continuous Cu film, which is required as a seed layer in ultralarge scale integration (ULSI), was successfully demonstrated with a high H 2 concentration of 0.39 mol/L.

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New understanding of the mechanism of runaway electrons beam generation in gases is presented. It is shown that the Townsend mechanism of avalanche electron multiplication is valid even for strong electric fields when the electron ionization friction on the gas may be neglected. A non-local criterion for runaway electron generation is proposed. This criterion results in the universal two-valued dependence of critical voltage Ucr on pd for a certain gas (p is pressure, d is interelectrode distance). This dependence subdivides a plane (U, pd) onto an area of efficient electron multiplication and an area where the electrons leave the gas gap without multiplication. On the basis of this dependence analogs of Paschen's curves are constructed, which contain an additional new upper branch. This brunch demarcates the area of discharge and the e-beam area.Electron beams of subnanosecond pulse duration and amplitudes of hundreds of amperes have been created at atmospheric pressure in various gases. It is shown that the beam of the runaway electrons is formed at an instant when the plasma of the discharge gap approaches the anode. In this case a basic pulse of the electron beam is formed according to the non-local criterion of runaway electron generation.A volume nanosecond discharge with high specific excitation power in the absence of gap preionization by an additional external source has been realized. The role of discharge gap preionization by the fast electrons, emitted from the plasma non-uniformities on the cathode, as well as propagation of an electron multiplication wave from cathode to anode in a dense gas are considered.