Atomic layer deposition of copper for CMOS interconnects

This work concerns the atomic layer deposition (ALD) of copper. ALD is a technique that allows conformal coating of difficult topographies such as narrow trenches and holes or even shadowed regions. However, the deposition of pure metals has so far been less successful than the deposition of oxides except for a few exceptions. Challenges include difficulties associated with the reduction of the metal centre of the precursor at reasonable temperatures and the tendency of metals to agglomerate during the growth process. Cu is a metal of special technical interest as it is widely used for interconnects on CMOS devices. These interconnects are usually fabricated by electroplating, which requires the deposition of thin Cu seed layers onto the trenches and vias. Here, ALD is regarded as potential candidate for replacing the current PVD technique, which is expected to reach its limitations as the critical dimensions continue to shrink. This work is separated into two parts. In the first part, a laboratory-scale ALD reactor was constructed and used for the thermal ALD of Cu. In the second part, the potentials of the application of Cu ALD on industry scale fabrication were examined in a joint project with Applied Materials and Intel. Within this project precursors developed by industrial partners were evaluated on a 300 mm Applied Materials metal-ALD chamber modified with a direct RF-plasma source. A feature that makes ALD a popular technique among researchers is the possibility to produce high- level thin film coatings for micro-electronics and nano-technology with relatively simple laboratory- scale reactors. The advanced materials and surfaces group (AMSG) at Tyndall National Institute operates a range of home-built ALD reactors. In order to carry out Cu ALD experiments, modifications to the normal reactor design had to be made. For example a carrier gas mechanism was necessary to facilitate the transport of the low-volatile Cu precursors. Precursors evaluated included the readily available Cu(II)-diketonates Cu-bis(acetylacetonate), Cu-bis(2,2,6,6-tetramethyl-hepta-3,5-dionate) and Cu-bis(1,1,1,5,5,5-hexafluoacetylacetonate) as well as the Cu-ketoiminate Cu-bis(4N-ethylamino- pent-3-en-2-onate), which is also known under the trade name AbaCus (Air Liquide), and the Cu(I)- silylamide 1,3-diisopropyl-imidazolin-2-ylidene Cu(I) hexamethyldisilazide ([NHC]Cu(hmds)), which was developed at Carleton University Ottawa. Forming gas (10 % H2 in Ar) was used as reducing agent except in early experiments where formalin was used. With all precursors an extreme surface selectivity of the deposition process was observed and significant growth was only achieved on platinum-group metals. Improvements in the Cu deposition process were obtained with [NHC]Cu(hmds) compared with the Cu(II) complexes. A possible reason is the reduced oxidation state of the metal centre. Continuous Cu films were obtained on Pd and indications for saturated growth with a rate of about 0.4 Å/cycle were found for deposition at 220 °C. Deposits obtained on Ru consisted of separated islands. Although no continuous films could be obtained in this work the relatively high density of Cu islands obtained was a clear improvement as compared to the deposits grown with Cu(II) complexes. When ultra-thin Pd films were used as substrates, island growth was also observed. A likely reason for this extreme difference to the Cu films obtained on thicker Pd films is the lack of stress compensation within the thin films. The most likely source of stress compensation in the thicker Pd films is the formation of a graded interlayer between Pd and Cu by inter-diffusion. To obtain continuous Cu films on more materials, reduction of the growth temperature was required. This was achieved in the plasma assisted ALD experiments discussed in the second part of this work. The precursors evaluated included the AbaCus compound and CTA-1, an aliphatic Cu-bis(aminoalkoxide), which was supplied by Adeka Corp.. Depositions could be carried out at very low temperatures (60 °C Abacus, 30 °C CTA-1). Metallic Cu could be obtained on all substrate materials investigated, but the shape of the deposits varied significantly between the substrate materials. On most materials (Si, TaN, Al2O3, CDO) Cu grew in isolated nearly spherical islands even at temperatures as low as 30 °C. It was observed that the reason for the island formation is the coalescence of the initial islands to larger, spherical islands instead of forming a continuous film. On the other hand, the formation of nearly two-dimensional islands was observed on Ru. These islands grew together forming a conductive film after a reasonably small number of cycles. The resulting Cu films were of excellent crystal quality and had good electrical properties; e.g. a resistivity of 2.39 µΩ cm was measured for a 47 nm thick film. Moreover, conformal coating of narrow trenches (1 µm deep 100/1 aspect ratio) was demonstrated showing the feasibility of the ALD process.

Human dimensions of bycatch reduction technology: Current assumptions and directions for future research

Bycatch reduction technology (BRT) modifies fishing gear to increase selectivity and avoid capture of non-target species, or to facilitate their non-lethal release. As a solution to fisheries-related mortality of non-target species, BRT is an attractive option; effectively implemented, BRT presents a technical 'fix' that can reduce pressure for politically contentious and economically detrimental interventions, such as fisheries closures. While a number of factors might contribute to effective implementation, our review of BRT literature finds that research has focused on technical design and experimental performance of individual technologies. In contrast, and with a few notable exceptions, research on the human and institutional context of BRT, and more specifically on how fishers respond to BRT, is limited. This is not to say that fisher attitudes are ignored or overlooked, but that incentives for fisher uptake of BRT are usually assumed rather than assessed or demonstrated. Three assumptions about fisher incentives dominate: (1) economic incentives will generate acceptance of BRT; (2) enforcement will generate compliance with BRT; and (3) 'participation' by fishers will increase acceptance and compliance, and overall support for BRT. In this paper, we explore evidence for and against these assumptions and situate our analysis in the wider social science literature on fisheries. Our goal is to highlight the need and suggest focal areas for further research. © Inter-Research 2008.

The distribution of sales revenues from pharmaceutical innovation.

OBJECTIVE: This report updates our earlier work on the returns to pharmaceutical research and development (R&D) in the US (1980 to 1984), which showed that the returns distributions are highly skewed. It evaluates a more recent cohort of new drug introductions in the US (1988 to 1992) and examines how the returns distribution is emerging for drugs with life cycles concentrated in the 1990s versus the 1980s. DESIGN AND SETTING: Methods were described in detail in our earlier reports. The current sample included 110 new drug entities (including 28 orphan drugs), and sales data were obtained for the period 1988 to 1998, which represented between 7 and 11 years of sales for the drugs included. 20 years was chosen as the expected market life for this cohort, and a 2-step procedure was used to project future sales for the drugs--during the period until patent expiry and then beyond patent expiry until the 20-year time-horizon was completed. Thus, the values in the first half of the life cycle are essentially based on realised sales, while those in the second half are projected using information on patent expiry and other inputs. MAIN OUTCOME MEASURES AND RESULTS: Peak annual sales for the top decile of drugs introduced between 1988 and 1992 in the US amounted to almost $US1.1 billion compared with peak sales of less than $US175 million (1992 values) for the mean compound. In particular, the top decile accounted for 56% of overall sales revenue. Although the sales distributions were skewed in both our earlier and current analysis, the top decile in the later time-period exhibited more rapid rates of growth after launch, a peak that was more than 50% greater in real terms than for the 1980 to 1984 cohort, and a faster rate of expected decline in sales after patent expiry. One factor contributing to the distribution of sales revenues becoming more skewed over time is the orphan drug phenomenon (i.e. most of the orphan drugs are concentrated at the bottom of the distribution). CONCLUSION: The distribution of sales revenues for new drug compounds is highly skewed in nature. In this regard, the top decile of new drugs accounts for more than half of the total sales generated by the 1988 to 1992 cohort analysed. Furthermore, the distribution of sales revenues for this cohort is more skewed than that of the 1980 to 1984 cohort we analysed in previous research.

Where does energy R&D come from? Examining crowding out from energy R&D

Recent efforts to endogenize technological change in climate policy models demonstrate the importance of accounting for the opportunity cost of climate R&D investments. Because the social returns to R&D investments are typically higher than the social returns to other types of investment, any new climate mitigation R&D that comes at the expense of other R&D investment may dampen the overall gains from induced technological change. Unfortunately, there has been little empirical work to guide modelers as to the potential magnitude of such crowding out effects. This paper considers both the private and social opportunity costs of climate R&D. Addressing private costs, we ask whether an increase in climate R&D represents new R&D spending, or whether some (or all) of the additional climate R&D comes at the expense of other R&D. Addressing social costs, we use patent citations to compare the social value of alternative energy research to other types of R&D that may be crowded out. Beginning at the industry level, we find no evidence of crowding out across sectors-that is, increases in energy R&D do not draw R&D resources away from sectors that do not perform R&D. Given this, we proceed with a detailed look at alternative energy R&D. Linking patent data and financial data by firm, we ask whether an increase in alternative energy patents leads to a decrease in other types of patenting activity. While we find that increases in alternative energy patents do result in fewer patents of other types, the evidence suggests that this is due to profit-maximizing changes in research effort, rather than financial constraints that limit the total amount of R&D possible. Finally, we use patent citation data to compare the social value of alternative energy patents to other patents by these firms. Alternative energy patents are cited more frequently, and by a wider range of other technologies, than other patents by these firms, suggesting that their social value is higher. © 2011 Elsevier B.V.

Mainland size variation informs predictive models of exceptional insular body size change in rodents.

The tendency for island populations of mammalian taxa to diverge in body size from their mainland counterparts consistently in particular directions is both impressive for its regularity and, especially among rodents, troublesome for its exceptions. However, previous studies have largely ignored mainland body size variation, treating size differences of any magnitude as equally noteworthy. Here, we use distributions of mainland population body sizes to identify island populations as 'extremely' big or small, and we compare traits of extreme populations and their islands with those of island populations more typical in body size. We find that although insular rodents vary in the directions of body size change, 'extreme' populations tend towards gigantism. With classification tree methods, we develop a predictive model, which points to resource limitations as major drivers in the few cases of insular dwarfism. Highly successful in classifying our dataset, our model also successfully predicts change in untested cases.

Nasopharyngeal Masses Arising from Embryologic Remnants of the Clivus: A Case Series.

Objectives This study aims to (1) discuss rare nasopharyngeal masses originating from embryologic remnants of the clivus, and (2) discuss the embryology of the clivus and understand its importance in the diagnosis and treatment of these masses. Design and Participants This is a case series of three patients. We discuss the clinical and imaging characteristics of infrasellar craniopharyngioma, intranasal extraosseous chordoma, and canalis basilaris medianus. Results Case 1: A 16-year-old male patient with a history of craniopharyngioma resection, who presented with nasal obstruction. A nasopharyngeal cystic mass was noted to be communicating with a patent craniopharyngeal canal. Histology revealed adamantinomatous craniopharyngioma. Case 2: A 43-year-old male patient who presented with nasal obstruction and headache. Computed tomography (CT) and magnetic resonance imaging revealed an enhancing polypoid mass in the posterior nasal cavity abutting the clivus. Histopathology revealed chondroid chordoma. Case 3: A 4-year-old female patient with a recurrent nasopharyngeal polyp. CT cisternogram showed that this mass may have risen from a bony defect of the middle clivus suggestive of canalis basilaris medianus. Conclusions Understanding the embryology of the clivus is crucial when considering the differential diagnosis of a nasopharyngeal mass. Identification of characteristic findings on imaging is critical in the diagnosis and treatment of these lesions.

The paradox of openness revisited: Collaborative innovation and patenting by UK innovators

© 2016 The Authors.We revisit the "paradox of openness" in the literature which consists of two conflicting views on the link between patenting and open innovation-the spillover prevention and the organizational openness views. We use the data from the Survey of Innovation and Patent Use and the Community Innovation Survey (CIS6) in the UK to assess the empirical support for the distinct predictions of these theories. We argue that both patenting and external sourcing (openness) are jointly-determined decisions made by firms. Their relationship is contingent upon whether the firms are technically superior to their rivals and lead in the market or not. Leading firms are more vulnerable to unintended knowledge spillovers during collaboration as compared to followers, and consequently, the increase in patenting due to openness is higher for leaders than for followers. We develop a simple framework that allows us to formally derive the empirical implications of this hypothesis and test it by estimating whether the reduced form relationship between patenting and collaboration is stronger for leaders than for followers.

Without prejudice: opening shots and negotiating documents

Reviews case law which has provided guidance on the law relating to without prejudice communications in landlord and tenant disputes. Considers: (1) the extent to which without prejudice communications are inadmissible in subsequent litigation; (2) exceptions to the without prejudice rule; (3) the specific context in which the rule applies; (4) the need for a dispute or negotiation to have arisen; (5) the prohibition on using "without prejudice" as an opening shot; and (6) the effect of changing the negotiating basis.

Too much formality?

Reflects on problems created by the formalities applicable to leases, with reference to the exceptions to the rule that leases be made by deed and the position of tenants paying rent under a void lease. Considers possible proposals for simplifying the system, including the introduction of a single requirement that all leases be in writing, abolishing the need for a deed when assigning a tenancy and reforming the right of tenants under a short lease to oblige landlords to supply written details of the tenancy terms.

Impacts of climate change on marine ecosystem production in societies dependent on fisheries

Growing human populations and changing dietary preferences are increasing global demands for fish, adding pressure to concerns over fisheries sustainability. Here we develop and link models of physical, biological and human responses to climate change in 67 marine national exclusive economic zones, which yield approximately 60% of global fish catches, to project climate change yield impacts in countries with different dependencies on marine fisheries. Predicted changes in fish production indicate increased productivity at high latitudes and decreased productivity at low/mid latitudes, with considerable regional variations. With few exceptions, increases and decreases in fish production potential by 2050 are estimated to be <10% (mean C3.4%) from present yields. Among the nations showing a high dependency on fisheries, climate change is predicted to increase productive potential in West Africa and decrease it in South and Southeast Asia. Despite projected human population increases and assuming that per capita fish consumption rates will be maintained1, ongoing technological development in the aquaculture industry suggests that projected global fish demands in 2050 could be met, thus challenging existing predictions of inevitable shortfalls in fish supply by the mid-twenty-first century. This conclusion, however, is contingent on successful implementation of strategies for sustainable harvesting and effective distribution of wild fish products from nations and regions with a surplus to those with a deficit. Changes in management effectiveness2 and trade practices5 will remain the main influence on realized gains or losses in global fish production.

Ecological Relations Between the Herring and the Plankton off The North-East Coast of England

I. 430 plankton samples, which were taken by several herring drifters using the Continuous Plankton Recorder in the Shields fishing area during the summer seasons of 1931 to 1933, are analysed to show the main changes in the plankton during those seasons. 2. A comparison is made between the proportions of the different zooplankton organisms found in the plankton and the proportions of these recorded by Savage (1937) in the stomachs of herring obtained from drifters working in the same area and during the same time. The comparisons are made for 29 ten-day periods in the seasons 1931 to 1933, and in addition, for 6 ten-day periods relating to a single drifter which obtained both plankton and stomach samples at the same time in 1932. 3. The comparisons in 2 provide evidence that the herring feeds by selecting certain organisms by individual acts of capture and not by swimming open-mouthed to strain out the plankton indiscriminately: (a) Calanus and Temora in the stomachs either correspond fairly closely to the proportions in the plankton or they may be in very much higher proportions. The latter is always true regarding Anomalocera. (b) Acartia, Oithona, Cladocera and Lamellibranch larvae are always in larger proportions in the plankton than in the stomachs; this applies also to Centropages with two insignificant exceptions. (c) There is a close correspondence between the numbers of Limacina and Sagitta in the plankton and stomachs in the latter half of the 1931 season, but not during 1932 and 1933, when the numbers in the stomachs were insignificant ; during the former period there was a great scarcity of Calanus in the plankton.

Assimilation of remotely-sensed optical properties to improve marine biogeochemistry modelling

In this paper we evaluate whether the assimilation of remotely-sensed optical data into a marine ecosystem model improves the simulation of biogeochemistry in a shelf sea. A localized Ensemble Kalman filter was used to assimilate weekly diffuse light attenuation coefficient data, Kd(443) from SeaWiFs, into an ecosystem model of the western English Channel. The spatial distributions of (unassimilated) surface chlorophyll from satellite, and a multivariate time series of eighteen biogeochemical and optical variables measured in situ at one long-term monitoring site were used to evaluate the system performance for the year 2006. Assimilation reduced the root mean square error and improved the correlation with the assimilated Kd(443) observations, for both the analysis and, to a lesser extent, the forecast estimates, when compared to the reference model simulation. Improvements in the simulation of (unassimilated) ocean colour chlorophyll were less evident, and in some parts of the Channel the simulation of this data deteriorated. The estimation errors for the (unassimilated) in situ data were reduced for most variables with some exceptions, e.g. dissolved nitrogen. Importantly, the assimilation adjusted the balance of ecosystem processes by shifting the simulated food web towards the microbial loop, thus improving the estimation of some properties, e.g. total particulate carbon. Assimilation of Kd(443) outperformed a comparative chlorophyll assimilation experiment, in both the estimation of ocean colour data and in the simulation of independent in situ data. These results are related to relatively low error in Kd(443) data, and because it is a bulk optical property of marine ecosystems. Assimilation of remotely-sensed optical properties is a promising approach to improve the simulation of biogeochemical and optical variables that are relevant for ecosystem functioning and climate change studies.

An interlaboratory comparison for the quantification of aqueous dimethylsulfide

An interlaboratory comparison (ILC) was conducted to evaluate the proficiency of multiple laboratories to quantify dimethylsulfide (DMS) in aqueous solution. Ten participating laboratories were each supplied with blind duplicate test solutions containing dimethylsulfoniopropionate hydrochloride (DMSP HCl) dissolved in acidified artificial seawater. The test solutions were prepared by the coordinating laboratory from a DMSP HCl reference material that was synthesized and purity certified for this purpose. A concentration range was specified for the test solutions and the participating laboratories were requested to dilute them as required for their analytical procedure, together with the addition of excess alkali under gas-tight conditions to convert the DMSP to DMS. Twenty-two DMS concentrations and their estimated expanded measurement uncertainties (95% confidence level) were received from the laboratories. With two exceptions, the within-laboratory variability was 5% or less and the between-laboratory variability was ~ 25%. The magnitude of expanded measurement uncertainties reported from all participants ranged from 1% to 33% relative to the result. The information gained from this pilot ILC indicated the need for further test sample distribution studies of this type so that participating laboratories can identify systematic errors in their analysis procedures and realistically evaluate their measurement uncertainty. The outcome of ILC studies provides insights into the comparability of data in the global surface seawater DMS database.

Questioning the role of phenology shifts and trophic mismatching in a planktonic food web

In a warming climate, differential shifts in the seasonal timing of predators and prey have been suggested to lead to trophic ‘‘mismatches’’ that decouple primary, secondary and tertiary production. We tested this hypothesis using a 25-year time-series of weekly sampling at the Plymouth L4 site, comparing 57 plankton taxa spanning 4 trophic levels. During warm years, there was a weak tendency for earlier timings of spring taxa and later timings of autumn taxa. While this is in line with many previous findings, numerous exceptions existed and only a few taxa (e.g. Gyrodinium spp., Pseudocalanus elongatus, and Acartia clausi) showed consistent, strong evidence for temperature-related timing shifts, revealed by all 4 of the timing indices that we used. Also, the calculated offsets in timing i.e. ‘‘mismatches’’) between predator and prey were no greater in extreme warm or cold years than during more average years. Further, the magnitude of these offsets had no effect on the ‘‘success’’ of the predator, in terms of their annual mean abundance or egg production rates. Instead numerous other factors override, including: inter-annual variability in food quantity, high food baseline levels, turnover rates and prolonged seasonal availability, allowing extended periods of production. Furthermore many taxa, notably meroplankton, increased well before the spring bloom. While theoretically a chronic mismatch, this likely reflects trade-offs for example in predation avoidance. Various gelatinous taxa (Phaeocystis, Noctiluca, ctenophores, appendicularians, medusae) may have reduced these predation constraints, with variable, explosive population outbursts likely responding to improved conditions. The match–mismatch hypothesis may apply for highly seasonal, pulsed systems or specialist feeders, but we suggest that the concept is being over-extended to other marine systems where multiple factors compensate.