Asymmetric co-evaporated Co-Cr films: magnetic parameters and reversal mechanism

The magnetic parameters of co-evaporated Co-Cr films, where Cr was deposited obliquely, are investigated. Process-induced compositional separation enhanced the energy product. When the substrate was rotated during evaporation, the perpendicular characteristics were lost

W-CMP for sub-micron inverse metallisation

Chemical Mechanical Polishing (CMP) of tungsten for an inverse metallisation scheme is investigated. The influence of CMP parameters on removal rate and uniformity is studied. The main effects on the removal rate are the applied pressure and the rotation rate of the polishing pad. To the first order Preston's equation is obeyed. The uniformity is best with equal rpm of pad and wafer and with perforated pads. Also, pattern density effects of CMP of W/PETEOS are investigated. Dishing increased at larger W-linewidth. Oxide erosion increased at larger pattern density and smaller W-linewidth. Electrical measurements on submicron (0.4 and 0.5 ¿m) test structures yielded good CMP results

Modelling of dishing for metal chemical mechanical polishing

In this paper, a physical model for the development of dishing during metal chemical mechanical polishing (CMP) is proposed. The main assumption of the model is that material removal occurs predominantly at the pad/wafer contacts. The distribution of pad/wafer contact size is studied first. This distribution is used as an input for a model of the dependence for the material removal rate on the line width. A relation that describes the development of dishing as a function of overpolish time will be presented. The model describes to a great accuracy the observed dishing effects, using one free paramete

Dependency of dishing on polish time and slurry chemistry in Cu CMP

\u3cp\u3eIn this paper the influences of slurry chemistry and thickness of the copper layer on dishing will be discussed. The dishing is studied for different patterns and variable polishing times. We found that the concentration of the oxidizer and the thickness of copper layer have a strong impact on dishing. The larger Cu features develop dishing at a higher rate than smaller structures during overpolishing. The experimental results lead to the following hypothesis for the Cu removal and surface passivation. The oxidizer (H\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e) reacts with Cu in an acidic slurry (pH 4) and Cu\u3csup\u3e2+\u3c/sup\u3e ions are formed. The anions of the carboxylic acid react with Cu\u3csup\u3e2+\u3c/sup\u3e ions and form an insoluble salt (R(COO)\u3csub\u3e2\u3c/sub\u3eCu) which passivates the surface. This passivation layer is removed in protruding areas by mechanical abrasion. Once removed from the surface, the `metallic soap' particles are swept away by the turbulent motion in the slurry .\u3c/p\u3

Ubiquitous Attentiveness - Enabling Context-Aware Mobile Applications and Services

Abstract. We present a concept called 'ubiquitous attentiveness': Context information concerning the user and his environment is aggregated, exchanged and constitutes triggers that allow mobile applications and services to react on them and adapt accordingly. Ubiquitous attentiveness is particularly relevant for mobile applications due to the use of positional user context information, such as location and movement. Key aspects foreseen in the realization of ubiquitously attentive (wearable) systems are acquiring, interpreting, managing, retaining and exchanging contextual information. Because various players own this contextual information, we claim in this paper that a federated service control architecture is needed to facilitate ubiquitous attentive services. Such a control architecture must support the necessary intelligent sharing of resources and information, and ensure trust

A Physical Model for Dishing during Metal CMP

A physically based model for dishing during metal chemical mechanical polishing (CMP) is presented. The control of dishing is important for advanced damascene metal interconnect technologies. However, the modeling of dishing is still in an initial phase. Material removal mainly takes place at the contact areas between the rough polish pad and the substrate. Therefore, a numerical model of the contact area of the pad and wafer, and the number of contacts and the size distribution of the contact areas as function of polish parameters and pad properties, was developed. The number of contacts appeared directly proportional to the applied pressure. In addition, the contact size distribution was strongly dependent on pad morphology. It was weakly dependent on the applied pressure and the Young's modulus of the pad. Thereafter the dishing phenomenon was modeled using these results. For an arbitrary linewidth, the metal was removed by two groups of pad asperities, one group with contact size smaller than the linewidth (group S) and one with contact size larger than the metal linewidth (group B). By considering the material removal rate of these two groups of asperities separately and using a modified form of Preston's law, a model was developed that describes the dishing during (over)polishing for an arbitrary metal line. The model contains one free parameter. The model was compared with experimental results obtained from state-of-the-art copper CMP. Excellent agreement was observed between data and the mode

Copper chemical mechanical polishing using a slurry-free technique

\u3cp\u3eA study of the chemical mechanical polishing (CMP) of thin copper films using fixed-abrasive pads is presented. The composition of the polishing solution is optimized by investigating the impact of both the oxidizer concentration and the pH of the solution on the polishing characteristics of copper. The resulting optimum polishing solution gives a high removal rate (>300 nm/min), good uniformity (standard deviation 3%) and a very high selectivity for the oxide removal rate (>100:1). The dependence of the removal rate of copper on the geometry is studied for different feature sizes and various pattern densities. The geometry dependency is considerably less in the slurry-free process than in the conventional slurry CMP. This is crucial for copper CMP because it helps to minimize the overpolishing time and consequently the amount of dishing. Damascene copper structures have been successfully made by polishing patterned test wafers. The amount of dishing of the copper lines is smaller than that for the conventional polishing technique. The polished wafers were easily cleaned; a standard rinsing step seemed to be sufficient.\u3c/p\u3