[en] A process for a retrograde well obtained by partial compensation of doping in the surface region is described. This structure is useful to reduce the latch-up susceptibility in CMOS technology. The process has been designed using the SUPREM program. Sample characterization has been carried out by the spreading resistance technique and by the four-point probe method. Good agreement has been obtained between simulated and experimental values. (author)

[en] Al recoil implantation have been shown to be a possible alternative to direct Al ion implantation to avoid usual problems linked with Al sources. Poor efficiency of the recoil + annealing process is observed if no barrier or an oxyde screen layers are used. This problem can be solved using a Si₃N₄ screen layer. Then, P-N and N⁺/P/N structures can be obtained with deep low doped P-well with reduced thermal budget

[en] Intense white (to the eye) luminescence has been obtained by multiple implantation of Si⁺ and C⁺ ions into thermal SiO₂ and a post-implantation annealing process. This white emission is a consequence of the convolution of three luminescence peaks centred at about 1.45 eV (infrared with a long tail in the red), 2.1 eV (yellow) and 2.8 eV (blue). These emissions have been correlated to the synthesis of nanocrystals of Si and SiC, and the existence of C-rich precipitates. Cross section TEM shows a buried layer with dark contrast, which correlates with the maximum of the C implanted profile, and likely with a high density of C-rich amorphous domains. Besides, two kinds of nanocrystalline precipitates are found, which have been identified as Si and hexagonal 6H-SiC by electron diffraction experiments. To our knowledge, these data provide the first experimental evidence on the ion beam synthesis of nanocrystalline 6H-SiC embedded in SiO₂. Correlation with previous data gives support to the assignment of the infrared, yellow and blue peaks with the Si, C-rich and SiC precipitate phases and/or its interfaces with SiO₂

[en] In this work Si samples implanted with nitrogen (N⁺ or N₂⁺) at a dose of 10¹⁷ cm^-2 are characterized by Raman spectroscopy and cross section transmission electron microscopy (XTEM). The correlation between the Raman spectra obtained with different excitation wavelengths and XTEM observations allows to determine the structural features related to the layers contributing to the total spectra. The evolution of these features with the annealing treatments (up to 1,150 C) is studied. The results obtained show, after the annealing treatment at the highest temperature, the presence of silicon nitride precipitates in the silicon subsurface region, and the formation of a nitrogen rich polycrystalline Si layer with Si₃N, grains. The Raman spectra from the subsurface region show a remaining shift of -0.15 cm^-1 when compared to the spectra from unimplanted Si. This shift, together with the similar shape of both Raman lines, suggests the presence in this region of an average tensile stress of 37.5 MPa

[en] The analysis of the etch-stop properties of layers obtained by substoichiometric nitrogen-ion implantation and annealing in silicon has been performed as a function of the implantation conditions. The analysis of the etching efficiency has been tested in TMAH-IPA systems. The results obtained show the need to implant at doses higher than 2 x 10¹⁷ cm^-2 to obtain etch-stop layers stable under high-temperature annealing. So, for implantation doses of 5 x 10¹⁷ cm^-2, layers stand unetched for times longer than 2 h. The preliminary structural analysis of the samples suggests the presence of an amorphous silicon nitride layer for higher implantation doses. (author)

[en] In this work the etch-stop behavior of buried layers formed by substoichiometric nitrogen ion implantation into silicon is studied as a function of the processing parameters, the implantation dose and temperature, and the presence of capping layers during implantation. Etching characteristics have been probed using tetramethylammonium hydroxide or KOH solutions for different times up to 6 h. Results show that, after annealing, the minimum dose required for the formation of an efficient etch-stop layer is about 4 x 10¹⁷ cm^-2, for an implantation energy of 75 keV. This is defined as a layer with an efficient etch selectivity in relation to Si of s ≥ 100. For larger implantation doses efficient etch selectivities larger than 100 are obtained. However, for these doses a considerable density of pits is observed in the etch-stop layer. These are related to the presence of nitrogen poor Si regions in the buried layer after annealing, due to a partial separation of silicon and silicon nitride phases during the annealing process. The influence of this separation of phases as well as nitrogen gettering in the buried layer on the etch-stop behavior is discussed as a function of the processing parameters

[en] Microstructural and magnetic properties of ¹⁴N⁺ irradiated Co/Pd multilayers, deposited on ultra-flat large (2.5 in) glass substrates by a special hard disk industrial manufacturing system, are discussed. Upon irradiation with ¹⁴N⁺ ions at different energies (20-30 keV) and doses (10¹⁴ - 10¹⁵ ions/cm²), both the coercive and nucleation fields were found to change with respect to as deposited multilayer. Results indicate that the irradiation process leads to a lowering of the magnetic anisotropy due to the induced disorder and degradation of the interface quality: for an energy of 30 keV; at an irradiation level of 10¹⁵ ions/cm², H_c reduces from H_c ∼ 5.4 kOe for the as deposited multilayer down to 300 Oe, being the easy axis still perpendicular to the multilayer plane; at the highest dose (10¹⁶ ions/cm²), the coercivity vanishes and the perpendicular anisotropy is suppressed. (authors)

No abstract available

[en] Flow-focusing devices can be used to produce microparticles at low cost, with the added advantage of low dispersion in the size of the generated particles. However, when multiple parallel devices are used with common inputs to massively produce the microparticles, the overall production is polydisperse, usually due to differences in flow rates of the focused fluid through each single device. The solution to uniformize this flow rate can involve active, movable devices that would add complexity and cost to the system. A simpler solution is to add distribution and equalization channels that drive focused fluid to the inputs. Experimental results show that this method can reduce the total dispersion, and render the multiple device close to monodispersion

[en] We describe high-speed control of light from silicon nanocrystals under electrical excitation. The nanocrystals are fabricated by the ion implantation of Si⁺ in the 15 nm thick gate oxide of a field effect transistor at 6.5 keV. A characteristic read-peaked electroluminescence is obtained either by DC or AC gate excitation. However, AC gate excitation is found to have a frequency response that is limited by the radiative lifetimes of silicon nanocrystals, which makes impossible the direct modulation of light beyond 100 kb s^-1 rates. As a solution, we demonstrate that combined DC gate excitation along with an AC channel hot electron injection of electrons into the nanocrystals may be used to obtain a 100% deep modulation at rates of 200 Mb s^-1 and low modulating voltages. This approach may find applications in biological sensing integrated into CMOS, single-photon emitters or direct encoding of information into light from Si-nc doped with erbium systems, which exhibit net optical gain. In this respect, the main advantage compared to conventional electro-optical modulators based on plasma dispersion effects is the low power consumption (10⁴ times smaller) and thus the inherent large scale of integration. A detailed electrical characterization is also given. An Si/SiO₂ barrier change from Φ_b = 3.2 to 4.2 eV is found while the injection mechanism is changed from Fowler-Nordheim to channel hot electron, which is a clear signature of nanocrystal charging and subsequent electroluminescence quenching