32 nm node BEOL integration with an extreme low-k porous SiOCH dielectric k = 2.3

A 32 nm node BEOL integration scheme is presented with 100 nm metal pitch at local and intermediate levels and 50 nm via size through a M1-Via1-M2 via chain demonstrator. To meet the 32 nm RC performance specifications, extreme low-k (ELK) porous SiOCH k = 2.3 is introduced at line and via level using a Trench First Hard Mask dual damascene architecture. Parametrical results show functional via chains and good line resistance. Integration validation of ELK porous SiOCH k = 2.3 is investigated using a multi-level metallization test vehicle in a 45 nm mature generation.     

Economic analysis of robust access network architecture in two-tierdata networks

Recent studies have addressed routing and performance issues of nonhierarchical and hierarchical backbone packet networks in a unified fashion, by adopting an end-to-end mean delay objective and including a variety of practical routing constraints. The authors build on this approach to include the design of robust access networks, and they analyze the economic and robustness-related tradeoffs of several access network architectures in two-tier data packet networks. Two-tier architectures consist of an access network that homes to a high-capacity backbone network through a variety of topological arrangements. The access tier provides protocol handling and traffic concentration. The backbone tier performs high-speed transport and alternate routing under congestion/failure conditions. They identify the fundamental access network parameters that allow them to develop network designs with optimized characteristics. The analysis demonstrates the cost effectiveness of access diversity as well as the enhanced robustness it can provide even though it requires higher switch functionality and cost     

Numerical paraxial approximation for highly relativistic beams

This paper is concerned with the numerical simulation of highly relativistic beams. We developed a particle-in-cell code for highly relativistic beams, based on the paraxial Vlasov-Maxwell formulation of Laval et al. This formulation follows the beam in a speed-of-light frame. It is fourth order accurate in the small characteristic velocity of the beam. The formulation is simpler than standard particle-in-cell codes in the lab frame or in the beam frame and gives a fast and easy to implement algorithm. Numerical examples illustrate the accuracy of the method.     

A new damascene architecture for high-performance metal–insulator–metal capacitors integration

As high-performance metal–insulator–metal capacitors are required for new technologies, an innovative architecture was developed with standard damascene processes used for copper interconnect realization. Low-cost damascene capacitors were integrated with thin Si₃N₄ films, leading to 2.9 fF/μm² capacitance values and low leakage currents, demonstrating this architecture ability to reduce the insulators thickness, thus achieving high-performance passive implementation for mixed integrated circuits.     

Nonlinear elastic inversion of prestack marine seismic data

A horizontally stratified medium consisting of a fluid layer overlaying any number of solid layers is considered. The depth distribution of the density and of the two elastic parameters from prestack offshore surface data is to be determined. The inverse problem is posed in terms of optimization. Its solution is based on nonlinear least squares. Since the solution of the direct problem is an important point in the inversion algorithm, a variational formulation capable of solving the (well-known) numerical difficulty at the liquid-solid interface is used. The acoustoelastic aspect of the problem is stressed. The feasibility of the technique is shown for large-size synthetic examples. It is expected that acoustoelastic inversion will help improve the interpretation of offshore seismic data     

S-transform applied to laser Doppler flowmetry reactive hyperemia signals

Laser Doppler flowmetry signals give information about many physiological activities of the cardiovascular system. The activities manifest themselves in rhythmic cycles. In order to explore these activities during the reactive hyperemia phenomenon, a novel time-frequency method, called the S-transform, based on a scalable Gaussian wavelet, is applied. The goal is to have a deeper understanding of reactive hyperemia. This paper focuses on the evaluation of the different activities between a rest signal and an hyperemia signal, both acquired simultaneously on the two forearms of healthy subjects. The results show that after the release of the occlusion, the myogenic, neurogenic, and endothelial related activities clearly increase on the forearm where the occlusion took place. Then, they return progressively to their basal level. However, on the rest forearm, no increase is noted for the three activities. The mechanisms that take place during reactive hyperemia are, therefore, local. The S-transform proves to be a suited time-frequency method, in order to analyze laser Doppler signal underlying mechanisms.     

Development of a permittivity extraction method for ultra low k dielectrics integrated in advanced interconnects

An extraction method to determine the permittivity of ultra low k (ULK) dielectrics on real integrated structures is presented. It is a two-step method based on a comparison between measured and simulated capacitance. A best-estimate value of the k_ULK value is first extracted with optimization software coupled to capacitance extraction software. Secondly, uncertainties on material and process parameters are considered to determine an error margin on the best-estimate extracted k value. The uncertainty on the best-estimate value is approximated by a function of the uncertainties on material and process variables. This function is calculated using a multi-linear approximation model and a numerical design of experiments. The same method is applied for the extraction of a ULK material k value (k_ULK) value and an effective k value (k_eff) but with two different simulation structures. In the simulation structure used for k_eff extraction, an equivalent dielectric layer including the ULK layer, the etch-stop and capping layers is used. This method was applied to metal 1 single damascene structures. First results of extraction are presented for two different ULK dielectrics. With the estimated uncertainty used for the parameters in this work, the uncertainties obtained for the best-estimate value of k_ULK and k_effective are significant. Due to the linearity of the model, the method is still applicable with different values for parameters uncertainty. An analysis work will be realized to improve the parameters uncertainty estimation. Future work will also include extraction of ULK permittivity for more complex structures like double damascene structures.     

Transformer coupled plasma dielectric etch for 0.25 μm technologies

Manufacturable etch processes for 0.18 μm technology TEOS bi-level contacts and vias (TEOS or TEOS/FOX/TEOS) are demonstrated in a low pressure high density reactor. Good CD control and high yields are demonstrated for structures down to 0.25 μm. In the process regimes used, the photoresist etch rate and the selectivity to underlayer are correlated with the amount of free fluorine in the plasma. The same TCP 9100 reactor can be used for low k polymer (Silk™ from Dow Chemical) etching with in situ hardmask open. A compromise between hard mask facetting and bowing has to be made unless passivating gases are added to an O₂/N₂ chemistry. For several architectures, initial results show potential integration with Cu.     

High resolution time delay estimation using sliding discrete Fourier transform

In this paper, we propose a novel time delay estimation approach based on sliding the discrete Fourier transform (DFT) analysis window, sample by sample, over the received short continuous wave (CW) pulse signal with the DFT evaluated successively. This approach uses the maximum magnitude of the spectrum and its corresponding phase offset to estimate the time delay (pulse echo mode) of the signal. We use the corresponding time as the first estimate, which is improved on the basis of the related phase. Examples are given of synthetic signals and simulated delays scenario, with and without added white noise. An underwater application, based on distance and speed of sound measurements using this approach in a water tank is demonstrated. The proposed method is shown to significantly outperform standard correlator-based approaches. Furthermore, the algorithm is simple to use and can be easily implemented, being based on phase detection using the sliding DFT.