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In plants, developmental plasticity allows for the modulation of organ growth in response to environmental cues. Being in contact with soil, roots are the first organ responding to soil abiotic stresses such as high salt concentration. In the root, plasticity relies on changes in the activity of the apical meristem, the region at the tip of the root where a set of self-renewing undifferentiated stem cells sustains growth. We show that salt stress promotes root meristem cells differentiation via reducing the dosage of the microRNAs miR165 and 166. By means of genetic, molecular and computational analysis, we show that the levels of miR165 and 166 respond to high salt concentration, and that miR165 and 166-dependent PHB modulation is fundamental for the response of root growth to this stress. Salt dependent reductions of miR165 and 166 causes rapid increase of the Arabidopsis homeobox protein PHABULOSA (PHB) expression and production of the root meristem pro-differentiation hormone cytokinin. Our data provide direct evidence of how the miRNA-dependent modulation of transcription factors dosage mediates plastic development in plants.In plants, development must be both robust – to ensure appropriate growth - and plastic – to enable the adaptation to external cues. Plastic development largely depends on the modulation of gene expression, controlling the concentration of developmental factors, such as hormones, transcription factors (TFs) and signalling molecules (Garcia-Molinaet al, 2013; Hofhuis & Heidstra, 2018; López-Ruizet al, 2020; Schröderet al, 2021). A classic example of plant developmental plasticity is the adaptation of plant growth to high salt conditions, a stress that inhibits shoot and root development (Flowerset al, 1997). Roots are the first organs sensing salt concentration in soil, where high salt reduces meristem activity and root growth (Dinnenyet al, 2008; Genget al, 2013; Jianget al, 2016). It has been suggested that the regulation of several plant hormones and miRNAs mediate the plant response to salt stress (Dolataet al, 2016; Genget al, 2013; Iglesiaset al, 2014; Jianget al, 2016; Nishiyamaet al, 2011; Yanet al, 2016). However, the molecular interplays mediating the adaptation of plant roots to salt stress are still vague. Post-embryonic root growth is supported by the activity of the root meristem, a region located at the root tip where self-renewing stem cells divide asymmetrically in the stem cell niche (SCN), originating transit-amplifying daughter cells that divide in the division zone (DZ) (Di Mambroet al, 2018). Once these cells reach a developmental boundary denominated transition zone (TZ), they stop dividing and start to elongate in the so-called elongation/differentiation zone (EDZ) (Di Mambroet al, 2018). A dynamic balance between cell division and cell differentiation ensures continuous root growth, maintaining a fixed number of cells in the DZ. Alterations in this dynamic equilibrium promote or inhibit root growth (Di Mambroet al, 2018; Salviet al, 2020). microRNA molecules (miRNA) play a key role in the control of root meristem development (Bertolottiet al, 2021a; Skopelitiset al, 2012). Maturation of plant miRNAs depends on the activity of a multiprotein complex comprising the DICER-LIKE1 (DCL1), HYPONASTIC LEAVES1 (HYL1) and SERRATE (SE) proteins that cut pre-miRNA transcripts into 21 nucleotides mature miRNA (Yanet al, 2016). Among miRNAs, miR165 and 166 have been shown to be main regulator of root development (Carlsbeckeret al, 2010; Dello Ioioet al, 2012). miR165 and miR166 are pleiotropic regulators of plant developmental processes. miR165 and 166 family consists of nine independent loci (MIR165 A-BandMIR166 A-G) that drive expression of pre-miR165 and 166 in different tissues and at different developmental stages (Miyashimaet al, 2011). miR165/166 activity is crucial in the control of robust development, restricting the expression of the HOMEODOMAIN LEUCINE ZIPPER III (HD-ZIPIII), including PHABULOSA (PHB) and PHAVOLUTA (PHV), which are involved in root and shoot development, vascular growth, and leaf and embryo polarity (Carlsbeckeret al, 2010; Dello Ioioet al, 2012; Di Ruoccoet al, 2017; Grigget al, 2009; McConnellet al, 2001; Skopelitiset al, 2017; Williamset al, 2005). In the root, miR165/166 regulate meristem homeostasis and radial patterning (Carlsbeckeret al, 2010; Dello Ioioet al, 2012); pre-miR165a, pre-miR166a and b transcription is promoted by the SCARECROW (SCR) and SHORTROOT (SHR) transcription factors (Carlsbeckeret al, 2010) and, thanks to the cell-to-cell mobility, mature miR165 and 166 forms diffuse to patterns both the root vasculature and the ground tissue (Carlsbeckeret al, 2010; Miyashimaet al, 2011; Skopelitiset al, 2018; Vaténet al, 2011; Bertolottiet al, 2021b). In the root meristem the miR165-166-PHB module promotes the synthesis of the plant hormone cytokinin, an important player in root developmental plasticity regulating cell differentiation rate of meristematic cells via the activation of the ARABIDOPSIS HISTIDINE KINASE3 (AHK3)/ARABIDOPSIS RESPONSE REGULATOR 1/12 (ARR1/12) pathway (Dello Ioioet al, 2007,2008). Here, we show that in response to salt stress miR165 and 166 modulatesPHBexpression to adjust root meristem activity. Salt exposure results in changes in cytokinin biosynthesis, which further regulates the miR165/166-PHB module. Hence, in addition to the above-described miRNA activity in controlling root robust development, we provide clear evidence that, in response to environmental cues, miRNAs are crucial also in the control of root plastic development, modulating the dosage of transcription factors.

To report our experience with full-dose 21 Gy IORT in early breast cancer patients after breast-conserving surgery to define most important selection factors.Seven hundred and fifty eight patients, subjected to conserving surgery and IORT, were retrospectively analyzed evaluating most important clinical outcomes.Median follow up was 5.2 years. Results from Cox analyses defined 2 groups of patients, "suitable" (age 50 years, non lobular histology, tumour size ≤ 2 cm, pN0 or pNmic, ki67 ≤ 20%, non triple negative receptor status and G1-G2) and "unsuitable" for IORT, with a higher rate of breast related events moving from "suitable" to "unsuitable" group. The 5 year rate of IBR is 1.8% in suitable group with significant differences versus unsuitable (1.8 vs. 11.6%, p 0.005). Same differences between two groups were evidenced in true local relapse (0.6 vs. 6.9%, p 0.005) and in new ipsilateral BC (1.1 vs. 4.7%, p 0.015).In our current practice we consider the following preoperative factors to select patients suitable for IORT: age 50 years, absence of lobular histology, tumor size ≤ 2 cm, pN0 or pNmic, according to APBI consensus statement, including also ki67 ≤ 20%, non triple negative receptor status and G1-G2.

A systematic design of practicable media suitable for rewritable, ultrahigh density (>;1Tbit/sq.in.), high data rate (>;1Mbit/s/tip) scanning-probe phase-change memories is presented. The basic design requirements were met by a Si/TiN/Ge2Sb2Te5 (GST)/diamond-like carbon structure, with properly tailored electrical and thermal conductivities. Various alternatives for providing rewritability were investigated. In the first case, amorphous marks were written into a crystalline starting phase and subsequently erased by recrystallization, as in other already established phase-change memory technologies. Results imply that this approach is also appropriate for probe-based memories. However, experimentally, the successful writing of amorphous bits using scanning electrical probes has not been widely reported. In light of this, a second approach has been studied, that of writing crystalline bits in an amorphous starting matrix, with subsequent erasure by reamorphization. With conventional phase-change materials, such as continuous films of GST, this approach invariably leads to the formation of a crystalline “halo” surrounding the erased (reamorphized) region, with severe adverse consequences on the achievable density. Suppression of the “halo” was achieved using patterned media or slow-growth phase-change media, with the latter seemingly more viable.

The recovery of the boron implantation damage can be very difficult. Depending on the energy and the dose many dislocations are generated at the projected range of the boron implantation. The morphology of these dislocations depends on the silicon substrate. In this work we demonstrate that the interstitial oxygen concentration ([Oi]) is related with the dislocation dimension, density end morphology. Particularly long dislocation dipoles were generated by the boron implantation in substrate with interstitial oxygen, and their density is connected with the [Oi] concentration.

In this article the phenomenology related to the mechanisms of defect generation in Shallow Trench Isolation (STI) processes is discussed, and the role of the structure pattern is investigated. Defect formation is studied by plan and cross TEM analyses of wafers with different boron doses and after annealing at various temperatures. In addition, to obtain a wider statistics our analysis was extended by electrical measurements of defect-sensitive structures. It is shown that a modification of the STI flow suppresses the main mechanism of mechanical stress accumulation, hence stress-induced defects are eliminated. However, this approach is found to be critical from the point of view of the implantation damage recovery, specifically for what concerns the implantations carried out before the trench etch. This result can be explained by the role of the silicon surface in reducing the point defect excess generated in the implantation. As a consequence, in this example the presence of the STI structure is beneficial, in that it assists in annealing implantation-related defects. An attempt is also presented to model the evolution of implantation-induced defects by a Kinetic Monte Carlo code. The calculation results are promising, though the capabilities of the model are limited by the computation time.

Aim of this work is the investigation of the impact of gate stack process on conduction and reliability of NMOSFET and PMOSFET in 0.18 μm dual-gate technology. Different poly-Si gate depositions and annealing oxidations have been compared, showing a strong impact on conduction characteristics only in PMOSFET in inversion mode. The differences have been ascribed to the contribution of electron tunneling through interface states at the poly-Si/SiO 2 interface, whose density depends on the poly-Si grain dimension. STEM cross-sections have indeed shown completely different grain size depending on the gate stack technology. A significantly different reliability performance is found in correspondence.

In this paper, the correlation between dislocation density and transistor leakage current is demonstrated. The stress evolution and the generation of defects are studied as a function of the process step, and experimental evidence is given of the role of structure geometry in determining the stress level and hence defect formation. Finally, the role of high-dose implantations and the related silicon amorphization and recrystallization is investigated.

A significant increase of HF etching rate and mean surface roughness (monitored by atomic force microscopy) was observed after P ion implantation on thin thermal SiO2 films (150 A). The dependence upon the ion fluence (in the range 3×1012–5×1013 ions/cm2) and energy (in the range 270–500 keV) was analyzed, together with the recovery effect of a postimplantation annealing in N2 atmosphere. Moreover, the impact of P implants on oxides grown by different sequences, considering postoxidation annealing in N2O or N2 atmospheres, was also studied. The effect of ion irradiation was investigated by thermally stimulated luminescence (TSL) above room temperature in order to obtain information on point defects present in the layers. The results showed that postoxidation annealing treatments in N2 atmosphere carried out not only after, but also before ion implantation, were particularly useful in order to lower the concentration of TSL active defects. This can be interpreted as a role of N2 annealing in favoring a structural rearrangement of the SiO2 layers.

In titanium silicide, the transition from the high (C49) to the low resistivity phase (C54) is difficult in small areas. This has been attributed in the literature to the lack of the nucleation sites for phase transition in small areas [1] . The mean grain size is directly related to the nucleation point density and its evaluation is important in obtaining data on nucleation mechanism of a new crystalline phase. TEM and SEM cross sections show that a silicon ridge is formed on the silicon substrate at the silicide grain boundaries, due to the equilibrium between the forces related to the grain–grain and to the grain–silicon interface energies [2] , [3] . AFM measurements have been performed on the interface between silicon and silicide after the removal of the silicide film. The grain boundaries of the silicide were imaged using the silicon ridges, allowing us to obtain unambiguous and statistically relevant data on the grain size.

MOCVD-TiN deposition from TDMAT precursor consists of two steps: a deposition and a plasma treatment in hydrogen. The effects of different plasma treatment times are tested on high aspect ratio contacts, finding an increase in the number of high resistance contacts for short plasma treatments. Moreover, the W nucleation layer thickness on MOCVD-TiN is impacted by the plasma time: for a short treatment a thin nucleation layer is found. Various investigations are performed on different MOCVD-TiN layers, comparing samples exposed to the air and samples in-situ capped by Ti to prevent oxygen contamination. It is shown that the plasma treatment influences the film morphology.

Various substrates are compared for both bulk defect formation and thin oxide reliability. Wafers were subjected to a complete device fabrication process, and the formation of the denuded zone was monitored by SPV measurements of carrier lifetime. Oxide reliability tests were carried out by exponentially ramped current stress and constant current stress measurements. Oxides with different thicknesses (70, 150 and 300 A) were tested, in order to detect both gettering effects (expected to be most effective in the thinnest oxides) and defectivity related to vacancy clusters (reported to be most apparent in 200–500 A thick oxides). The detrimental effect of vacancy clusters and oxygen-related defects is demonstrated by comparing Czochralski grown wafers with different densities of such defects and epitaxial p/p + material. In Czochralski material, the usual denuding and precipitation thermal cycle is compared to the recently proposed method to control oxygen precipitation through the concentration of intrinsic point defects.

This work is addressed to investigate thermal stability of a thin TiSi 2 film, that is its ability to resist degradation due to heat treatments at high temperatures. The study was carried out as a function of the formation RT treatment (675–750°C) at the end of a common process flow. Sheet resistance measurements were employed in order to evaluate this degradation. Electrical measures were performed on large and narrow poly-Si lines, on Van Der Pauw structures and on doped mono-Si substrates. An increase in sheet resistance value of an order of magnitude for silicide formed at temperatures below 700°C with respect to the one formed at temperatures above 700°C was found, particularly on poly-Si lines. The effect is detectable independently of the structure: it was observed also on 0.75-μm wide poly-Si lines, increasing when line width decreases. Different morphological analyses were carried out for investigating the influence of the formation temperature. We explain the increase of the final sheet resistance decreasing the formation temperature as a lower thermal stability of the TiSi 2 film, leading to a thermal grooving of the silicide grains.

In this work the surface morphology of nitrided silicon dioxide is extensively studied using atomic force microscopy. Nitridation is obtained by thermal annealing in nitriding atmosphere in conventional furnace, immediately after thermal oxidation of silicon substrates. The characterisation performed concerns the oxide surface, as well as the region where nitrogen is incorporated, the latter exposed using a diluted HF solution. Significant differences in the morphology of the nitrided layer are observed, which are a function of the nitridation process applied. They allow us to correlate the morphology to the nitrogen incorporation mechanisms that have occurred.

Electron beam induced current (EBIC) technique is successfully used to characterize intrinsically gettered Czochralski silicon. The impact of three different sequences of thermal treatments, typically used in ultralarge scale integration device manufacturing, on the denuded zone (DZ) formation and oxygen precipitation in the bulk is evaluated. EBIC technique is applied in a nonstandard configuration, where a Schottky diode is evaporated on the wafer cross section, for the direct observation of the DZ and oxygen related defects in the silicon bulk. The reduction of minority carrier diffusion length, due to the formation of recombination centers after oxygen precipitation, is also estimated by EBIC in planar collector geometry. The DZ determination by EBIC technique is in good agreement with surface photovoltage measurements and microscopical inspections after chemical etching.

A systematic comparison among the most common methods (surface photovoltage (SPV), Elymat, and microwave-detected photoconductive decay (μ-PCD)) for lifetime measurements is presented. Though these techniques are very different from each other, we show that, where bulk-diffused impurities are concerned, they agree very well with each other, provided they are properly used. In order to validate these techniques for the quantitative evaluation of bulk-diffused contaminants, iron and chromium implantations were carried out. An excellent correspondence was found between Elymat and μ-PCD data. In addition, the lifetime dependence on iron dose was studied and the expected behaviour was verified over two orders of magnitude. Elymat and μ-PCD measurements have also been applied to the study of contaminants segregated at wafer surface, such as nickel and copper. Both these techniques are very sensitive to surface-segregated metals, though under these conditions the correlation between Elymat and μ-PCD data is somewhat different with respect to samples with metals dissolved in the bulk. A measurement procedure is proposed in order to discriminate bulk and surface recombination.

In the last years the coming of the 193 nm lithography requested to the characterization technique a continuous improvement. Scanning electron microscopy (SEM), with Atomic force microscopy (AFM), remained the main techniques for the photoresist characterization, but the energy of the electron beam has drastically dropped down. In fact the materials used in the 193 nm lithography are easily modified by the electron beam if the energy is higher then 1 kV.

The application of the focused ion beam (FIB) to the preparation of thin lamellae of Si-based samples for strain analysis by means of convergent beam electron diffraction (CBED) was investigated. The crystal damage induced by the ion beam at the sample surface is expected to influence the pattern quality strain analysis too. Repeatable results in the strain measurements were obtained only if a low energy (5 KeV) finishing step was used in the sample preparation. The strain measurement results obtained in patterned structures with different strain amount were also compared with the ones calculated using a commercial process simulator and with electrical measurements performed on the final devices.

A significant increase in the etching rate of 680 nm thermally grown silicon dioxide layers has been observed following high energy ion implantation. Phosphorous and boron implantations have been considered, and the dependence upon fluence (from 1012 to 1014 atom/cm2)and ion energy (from 700 to 3000 keV) has been investigated. The effect of ion implantation has also been analyzed by thermally stimulated luminescence measurements above room temperature, to obtain complementary information on the physical mechanisms involved in the damage process. Data related to thermal annealing of oxide damage are also presented, indicating that a monotonic recovery takes place at temperatures higher than 550 °C although residual damage is observed even after thermal treatment up to 1000 °C.

In this paper we discuss the physical mechanism and the critical factors for the dislocation generation in device processing. The mechanisms of the stress development are identified. Elastic stress is estimated from the convergent beam electron diffraction (CBED) measurements using transmission electron microscopy (TEM), and the defect generation is monitored by electrical measurements of a specific monitor structure. The implantation conditions and the implantation damage recovery is shown to be another key factor in the defect generation. Thermal oxidations of the STI structure are shown to be a major responsible of the stress increase. In addition to the process the pattern geometry strongly affects the mechanical stress. Minimum geometry structures with a complex layout are prone to defect generation.

This paper presents a systematic investigation of thermal stability of high-k materials deposited on RCA cleaned wafers by ALCVD™ in an ASM Pulsar™ 2000 reactor. Physical-chemical evolution of Al2O3, HfO2 and Al/Hf composite materials (nanolaminate and aluminates) was studied considering two types of thermal treatments: quenched vacuum anneals from 300°C to 900°C and furnace atmospheric processes in N2 or O2 at 850°C and 900°C. Material crystallization and changes in film structure were studied by means of TEM, XRD, XRR, XRF, RBS and TOF-SIMS. Non-contact electrical measurements were used to detect modification in EOT and fixed charge. Al2O3 was found still amorphous at 900°C. Not so for HfO2 that crystallized in monoclinic phase at a temperature between 300–400°C. Crystallization temperature and possible phase separation of Al/Hf composite materials were found to be a function of Al2O3 content and film type. In most of these samples, however, a chemical evolution was detected in addition to the above reported crystallization phenomena. All the achieved results demonstrate that depending on thermal treatment conditions, ALCVD™ high-k stability does not only concern phase transition effects but also a transformation of the “SiO2/high-k” system into “doped-SiO2/silicate” stack.

In this paper a systematic investigation of nitrided oxides obtained by Rapid Thermal Oxidation/Nitridation (RTO/RTN) in AMAT Centura System is reported. Two different aspects were considered: first the comparison between single wafers and batch technology, second the different possible oxide architecture achievable with RTO/RTN system (i.e. RTO + RTN, RTN + RTO, RTN + RTO + RTN). Both morphological and patterned wafers were processed. Physical and chemical characterizations were carried out by means of SIMS, XPS, ELYMAT, AFM and Etching Rate studies. Morphological results were then correlated to electrical data obtained on MOS capacitors. The film obtained performing a NO RTN nitridation of the native oxide followed by a ISSG (In Situ Steam Generation) oxidation exhibited very promising electrical properties that made it an appealing candidate as gate dielectric in CMOS and Flash memories applications.

X-ray photoelectron spectroscopy (XPS) and photocurrent measurements for the determination of surface recombination velocity provide complementary information on the structure of the Si-SiO2 interface, being sensitive to the chemical nature of foreign species at the interface the former, and to intrinsic defects the latter. The comparison of the XPS N(1s) peaks determined for the Si-Si0 2 interfaces nitrided in NO or N2O ambients is useful to identify the species responsible for the broadening of the peak. In fact, nitridation by NO is mainly responsible for the formation of Si3N moieties at the silicon surface in which silicon atoms are partially oxidized; while nitridation by N2O proceeds with the oxidation of Si – Si backbonds to Si – N bonds, thus resulting in the formation of N(Si(O-)3)3 groups embedded in the oxide. Surface recombination velocity by photocurrent measurements gives evidence that nitridation in N2O is associated with an appreciable co-oxidation, while nitridation in NO is mainly associated with the passivation of interface states. Furthermore N2O and NO nitridation are responsible for different morphologies of the nitrided layers.

Titanium disilicide obtained by direct interaction between Si and a deposited Ti layer is a choice for low- resistance gate interconnections and source and drain areas. The properties of the TiSi2 film can be influenced by many factors; such as substrate nature and doping, the depositing Ti layer, structure dimensions [1][2][3][4]. This work is addressed to study the properties of TiSi2 film as obtained from titanium deposited by Ion Metal Plasma (IMP), which has recently been introduced in high aspect ratio contact and via applications.Its suitability for titanium silicide formation is investigated here in comparison to standard PVD deposition. The study was carried out on flat and patterned samples. Titanium silicide formed on mono- Si substrates were characterized as a function of RTP temperature in terms of sheet resistance, tilm morphology, crystallography and phase evolution. It was found that the TiSi2 film obtained from IMP- Ti is very similar to the one obtained from PVD standard deposition. However, for annealing below 700°C, an increase in the sheet resistance of the TiSi2 C49 phase from IMP- Ti compared to the one from PVD- Ti was found, and is explained by different silicide grain size. Analyses performed on patterned samples with doped silicon and poly- Si lines show similar electrical results for TiSi2 from IMP and PVD deposition; however, fbr p+ poly-Si lines, the IMP samples displayed correct TiSi2 formation down to 0.18µm line width, while the PVD wafers showed discontinuous results at these minimum feature sizes.

Quality controls in radiotherapy allow to check the correct running of treatment units and to test our procedures. Portal films taken during the first treatment session are used in quality assurance programs to compare scheduled to administered doses.To analyze the accuracy of patient positioning in pelvic cancer irradiation, a retrospective study was carried out on 50 treatment schedules carried out at the Radiotherapy Department of S. Anna Hospital (Como, Italy) from June to December, 1996. We checked field mispositioning for correlations with patient or treatment variables, such as patient age, sex, weight, thickness, or unit type. We took one portal film at the first treatment session and checked field positioning by measuring the distance of the isocenter from fixed anatomical structures on the simulation film and on the portal film taken in anteroposterior and lateral projections.Four vectors were defined to evaluate field mispositioning along right-left (ADS), craniocaudal (ACC, LCC) and anteroposterior (AP) directions. The average values of these four vectors were respectively 2.94, 5.23, 5.54 and 3.20 mm. We found a major shift in field centering leftward and toward the patient's feet. To obtain more information about the total isocenter displacement, a vector T was calculated by summing the vectors ADS, ACC and LAP; a further evidence of field mispositioning is given by the vector T mean value (8.66 +/- 4.95 mm). No correlation was found between vector T values and any patient or treatment variable.The acquaintance with uncertainties requires adequate statistical tools. A single check at treatment beginning could show a systematic error, but not the random fluctuations which can be recognized only with periodic portal films. To correct a possible systematic error without likely worsening set-up conditions, an adequate threshold value must be chosen for field mispositioning, according to each center's historical data.One portal film at the beginning of treatment is the minimum requirement in a quality assurance program. We feel the need to change our protocol and acquire more than one portal film, because the higher the number of portal films the easier the distinction of systematic from random errors. Using serial portal films, all at the first session, we will be able to introduce quantitative criteria for various action levels.

A method for measuring denuded zone depth from lifetime measurements is proposed and compared to observations by microscopy techniques and to Electron Beam Induced Current (EBIC) analyses. The surface photovoltage (SPV) method is chosen for measuring lifetime, as it is found to be extremely sensitive to oxygen precipitation. Samples prepared according to three typical thermal hystories are used as test vehicles.Correlating the results given by the different techniques, this study points out a few relevant features from the point of view of wafer processing. For instance, processes starting with a low temperature treatment are poorly reproducible for what concerns oxygen precipitation and denuding, as shown by SPV data, and do not guarantee a defect-free denuded zone, as seen in EBIC images. Additional high temperature treatments during the process increase the denuded zone depth and improve uniformity.Techniques which rely on a selective etching for defect detection, such as the Secondary Electron method of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), are limited by etching sensitivy. On the other hand, the Transmission Electron Microscopy (TEM) statistics is too poor for this sort of observations. Instead, as a technique based on the recombination activity of defects, EBIC has roughly the same sensitivity as SPV. Both these techniques detect the formation of a denuded zone even when other methods fail, and can be considered as complementary tools.

In this paper a phenomenological characterisation of an anomalous grain growth, observed after classical electromigration lifetests, on Al-l%Si-0.5%Cu multigrain stripes, deposited at high temperature (460°C) on a Ti substrate, is reported. Failure analysis, carried out by Scanning Electron Microscopy (SEM) and Focus Ion Beam (FIB), has detected an abnormal single-grain growth in the vertical direction, starting from the Ti/Al interface. Medium Time to Failure (MTF) data are compared with those of stripes on Ti/TiN substrate, on which no grain growth was observed. The growth of the anomalous grains has been related to the Ti/Al interface properties. Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM) analyses concurrently show a higher texture of the film on the Ti, compared with the film on the Ti/TiN substrate. The tight columnar orientation of grain boundaries strongly limits the mechanism of grain boundary diffusion during electromigration stress. The atomic flux is then forced to take place at the Ti/Al interface, where the epitaxial growth of the Al single grains is favoured.

A study of amorphous and polycrystalline silicon films deposited at different temperatures is presented. The effect of surface roughness on the quality of the fits to the spectroscopic ellipsometry data is assessed through a comparison with complementary atomic force microscopy images. © 1998 Elsevier Science S.A.

In this work we present a systematic study about the metal contamination induced by ion implantation, with the aim to identify contamination mechanisms and possible solutions to the problem. Lifetime measurements have been used in order to evaluate the level of contamination in implented wafers. Lifetime values have been extracted from photocurrent measurments (Elymat technique). Implantations of iron and cromium have been used in order to validate the study of lifetime versus injection level as a technique for the identification of contaminants and for the quantitative evaluation of their concentration. The contamination level in ion implanted wafers has been characterized varying main implantation parameters (species of the implanted ion, dose, current, energy, angle) and surface condition (whether bare or oxidized silicon). Ion implantation is responsible for a a heavy lifetime degradation (i.e. metal contamination), which increases in proportion to implantation dose and comes from the side exposed to the ion beam. The distribution of lifetime over wafer surface provides relevant information. Details of the implanter endstation (e.g., the clamping system) usually show up in wafer maps of lifetime. Results coming from different equipments concur to indicate that contaminants come from material sputtered from the loading disk. This conclusion is confirmed by the dependence of lifetime on implantation energy and tilt angle. The chemical nature of the contaminant can in some cases be identified by injection level spectroscopy. Implantation of heavy ions is mainly responsible for iron contamination; some other impurity (maybe cromium) is detected in boron-implanted wafers. From the point of view of device processing, the problem can be circumvented by implantation through a screening exide. Vice versa gettering techniques remove only a limited fraction of the contaminants introduced during the implantation.

March 1988 through April 1992, three hundred and ninety-six patients affected with bronchogenic carcinoma were treated at the Department of Radiation Oncology of the S. Anna Hospital, Como, Italy. A hundred and ten patients presenting stage-III non-small-cell lung carcinoma were evaluable. All evaluable patients underwent radiation therapy alone, with either palliative or curative purposes. Two main periods can be distinguished: in period A, before June 30th, 1990, treatment planning included conventional techniques, with no simulators; the patients were treated with opposing anteroposterior fields only. In period B, after July 1st, 1990, either the simulator alone was used or a simulator, a CT unit and a treatment planning computer system were combined; anteroposterior opposing fields or multiportal technique were used. Median overall survival was 10 months. Independent of treatment goals, the irradiated volume was markedly different in the patients treated in period A than in those treated in period B. A marked and statistically significant increase in survival was observed in group B. Survival also increased in patients treated with doses40 Gy, but only if treatment planning had used adequate technology and accuracy. To conclude, better survival can be achieved only by improving treatment accuracy and quality.

Lonidamine, an indazole carboxylic acid derivative, was reported in Phase II/III trials to have efficacy as radiopotentiator in malignant glioma. Between October 1990 and August 1994, 191 pts. with supratentorial malignant glioma were randomly allocated to treatment with RT or RT + L, following surgical resection. Prior to randomisation patients were stratified according to age. One patient was ineligible and excluded from the study (not malignant glioma). Patients (pts) in arm A (98 pts) received RT alone (50 Gy whole bram plus 14 Gy coned-down boost to the tumour volume, 2 Gy/day for 5 days a week), those in arm B (92 pts) received RT + L (150 mg 3 times daily for 1 year starting from 3 days before irradiation). The groups were comparable in median age, performance status, TNM classes, sex, residual tumour size after surgery and histologic grade. Median follow up was 49 weeks. Intention to treat analysis failed to demonstrate significance difference in the survival rates and shapes of the survival curves between the two treatment arms. Cumulative survival at 12 and 24 months calculated by the Kaplan Meier method were 50% ± 5% and 13.4% ± 4% for arm A, 49% ± 5% and 13.4% ± 4% for arm B. (P> 0.4). The Cox proportional hazards model confirmed the prognostic variables of age ( P P P

The authors review the supraglottic laryngeal carcinomas examined in the Radiotherapy Department of the "Ospedale Regionale" of Varese, Italy, from 1979 to 1984. 255 patients have been monitored: 80 considered for radiotherapy alone and 77 for postoperatory radiotherapy treatment. The cumulative actuarial survival (pcs) after 60 months, for patients treated only with radiotherapy, is 0.66 +/- e.s. 0.07; for patients treated with post-operatory radiotherapy the cumulative actuarial survival (pcs) after 60 months is 0.49 +/- e.s. 0.11. The irradiation techniques are described and the results achieved fully discussed.

The records of 168 patients treated by definitive radiation therapy for non-oat-cell-carcinoma of the lung in the Radiotherapy Department of the "Ospedale Regionale Multizonale" of Varese, Italy, from may 1979 to december 1984, were analyzed. Cumulative probability of survival from the beginning of radiotherapy were 48 +/- 4% at 12 months and 8 +/- 3% at 60 months. It appears to be no significant difference in survival according to TNM classes, UICC stages, histology and grading. Significant differences in survival were found grouping patients by performance status (I.K. less than 70 v.s. greater than or equal to 70), total absorbed dose (dose less than 56 Gy v.s. greater than or equal to 56 Gy), total isoeffect levels (CRE less than 17 reu v.s. greater than or equal to 17 reu), and response to treatment. The latter could be the most important prognostic factor. Median survival for CR, PR and NC categories were 48.5, 12 and 10 months respectively. We suggest that RT may be of value in improving quality of life and survival of patients affected by non operable non-oat-cell-carcinoma of the lung.

The Authors, considering 141 cases of patient women under 40, suffering from breast cancer, analyse the prognostic factors in relation to the different therapeutical approach, histologic type, dimensions of T, and presence or absence of metastases at the axillary lymph nodes. They, moreover, appraise the actuarial global survival with no disease (NED) of this group of patients as compared with the survival of women in more advanced age.

The anti-inflammatory activity and the eicosanoid generation in rat gastric mucosa after a single oral dose of S-(+)-2(4-fluorophenyl)-α-methyl-5-benzoxazolacetic acid (flunoxaprofen, 10 mg/kg) or indomethacin (5 mg/kg) were compared. The two compounds, at the dose used, show a similar degree of anti-inflammatory activity (50% inhibition of carrageenan-induced oedema in rat paw). Moreover flunoxaprofen does not modify the formation of 6-keto-PGF1α by rat gastric mucosa in vitro while indomethacin causes 50% inhibition of gastric cyclooxygenase activity. This biochemical change induced by indomethacin is associated with gastric lesions. Chronic treatment of rats with flunoxaprofen (5 or 50 mg/kg p.o. for 15 days) shows an anti-inflammatory activity in the range of 60–70% inhibition in the rat paw oedema test without gastric mucosa damages and prostaglandin synthesis inhibition.

Some commonly used techniques for metal contamination monitoring by lifetime measurements (surface photovoltage, Elymat and microwave-detected photoconductive decay) are discussed and compared. In order to validate these techniques for the detection and the quantitative evaluation of bulk-diffused contamination, iron and chromium implanted samples have been studied. Though these techniques are very different from each other, we show that for what concerns bulk-diffused impurities they agree very well with each other, provided in the comparison the dependence of carrier lifetime on the injection level is taken into account. In addition, the possibility to extend these techniques to surface characterization (e.g. for the detection of surface-precipitated metals) is studied. Nickel and copper implantated wafers were used to this purpose. Both Elymat and μ-PCD are found to be very sensitive to surface-segregated metals, though under these conditions the correlation between Elymat and μ-PCD data is somewhat different with respect to samples with metals dissolved in the bulk. Finally, some gettering techniques are reviewed and compared for what concerns gettering efficiency. It is pointed out that gettering efficiency is sensitively reduced in high temperature rapid thermal treatments. This fact can be explained by efficiency loss of the segregation mechanism.

A method for measuring denuded zone depth from lifetime measurements is proposed and compared to observations by microscopy techniques. The surface photovoltage (SPV) method is chosen for measuring lifetime, as it is found to be extremely sensitive to oxygen precipitation. SPV estimates of denuded zone depth are compared to observations by microscopy techniques, such as selective etching and inspections by a scanning electron microscope or an atomic force microscope, and analysis by transmission electron microscopy. SPV estimates agree with microscopy inspection, provided defect density is high enough to allow a denuded zone to be identified.