Contemporary patent analytics employs a holistic approach whose purpose is to extract insights from aggregate analysis of patent landscapes. For the fruits of this endeavour to be accessible to executives, public servants and other individuals who value their time, the insights must be graphical in nature. In this paper, time evolved ranked Pareto distribution of patent family counts per assignee are analyzed by power law analysis. A graphical representation is presented which provides instantaneous insights into comparative scale and consolidation of technology landscapes. A number of specific data-analytical issues have been investigated and their impact on the validity of the results have been bounded and best-known methods proposed.
For the most advanced nodes, edge placement errors are typically dominated by stochastics, necessitating a rigorous stochastics approach to modeling and measuring edge placement errors and their contributors. In this work, a new approach to developing an edge placement error (EPE) model useful for lot dispositioning or EPE budgeting is presented. Approach: As an example of the proposed approach, a rigorous EPE model is developed for the case of complementary lithography, where dense lines and spaces are cut with a second patterning step. This model gives rise to the generation of an Overlay Process Window, the range of overlay errors that can be tolerated in the presence of stochastics critical dimension and placement errors of the individual layers. The resulting model uses only measurable quantities and allows the prediction of EPE-based failure rates for the purpose of lot dispositioning. One interesting outcome is that Angstrom-level changes in the 1-sigma stochastics terms produces nanometer-level changes in the overlay process window. This new EPE modeling approach provides a more rigorous and accurate method for lot dispositioning and EPE budgeting than prior approaches.
New business insights are shown to be extractable from patent landscapes by the mathematical method of discrete Pareto analysis. By applying to patent publication distributions, a method analogous to that proposed by the linguist George Kingsley Zipf, metrics and methods of visualization are introduced which quantify scale, dominance and consolidation of a patent landscape. The key results of the method are illustrated in the Zipf plot of assignee patent publication count versus assignee rank for the lithography patent landscape shown below.
In recent years, lithographic printability of overlay metrology targets for memory applications has emerged as a significant issue. Lithographic illumination conditions such as extreme dipole, required to achieve the tightest possible pitches in DRAM pose a significant process window challenge to the metrology target design. Furthermore, the design is also required to track scanner aberration induced pattern placement errors of the device structure. Previous workiii, has shown that the above requirements have driven a design optimization methodology which needs to be tailored for every lithographic and integration scheme, in particular self-aligned double and quadruple patterning methods. In this publication we will report on the results of a new target design technique and show some example target structures which, while achieving the requirements specified above, address a further critical design criterion - that of process resilience.
We present a novel metrology target design framework using the scanner exit pupil wavefront analysis together with Zernike sensitivity analysis (ZSA) based on the Monte-Carlo technique. The proposed method enables the design of robust metrology targets that maximize target process window (PW) while minimizing placement error discrepancies with device features in the presence of spatial and temporal variation of the aberration characteristics of an exposure tool. Knowing the limitations of lithography systems, design constraints, and detailed lithography information including illumination, mask type, etc., we can successfully design an optimal metrology target. We have validated our new metrology target design (MTD) method for one of the challenging DRAM active layer consisting of diagonal line and space patterns illuminated by a rotated extreme dipole source. We find that an optimal MTD target gives the maximized PW and the strong device correlation, resulting in the dramatic improvement of overall overlay performance. The proposed target design framework is completely general and can be used to optimize targets for different lithography conditions. The results from our analysis are both physically sensible and in good agreement with experimental results.
We present a metrology target design (MTD) framework based on co-optimizing lithography and metrology performance. The overlay metrology performance is strongly related to the target design and optimizing the target under different process variations in a high NA optical lithography tool and measurement conditions in a metrology tool becomes critical for sub-20nm nodes. The lithography performance can be quantified by device matching and printability metrics, while accuracy and precision metrics are used to quantify the metrology performance. Based on using these metrics, we demonstrate how the optimized target can improve target printability while maintaining the good metrology performance for rotated dipole illumination used for printing a sub-100nm diagonal feature in a memory active layer. The remaining challenges and the existing tradeoff between metrology and lithography performance are explored with the metrology target designer’s perspective. The proposed target design framework is completely general and can be used to optimize targets for different lithography conditions. The results from our analysis are both physically sensible and in good agreement with experimental results.
We demonstrate a novel method to establish a root cause for an overlay excursion using optical Scatterometry metrology. Scatterometry overlay metrology consists of four cells (two per directions) of grating on grating structures that are illuminated with a laser and diffracted orders measured in the pupil plane within a certain range of aperture. State of art algorithms permit, with symmetric considerations over the targets, to extract the overlay between the two gratings. We exploit the optical properties of the target to extract further information from the measured pupil images, particularly information that maybe related to any change in the process that may lead to an overlay excursion. Root Cause Analysis or RCA is being developed to identify different kinds of process variations (either within the wafer, or between different wafers) that may indicate overlay excursions. In this manuscript, we demonstrate a collaboration between Globalfoundries and KLA-Tencor to identify a symmetric process variation using scatterometry overlay metrology and RCA technique.
Computational metrology target design requires both an accurate metrology simulation engine and an accurate geometric model. This paper deals with the later. Optical critical dimension metrology and cross-section SEM are demonstrated as two useful methods of geometric model verification with differing capabilities. Specifically, a methodology is proposed which allows the metrology engineer to quantify the level of accuracy required by the model as a function of the tolerable uncertainty in the prediction of metrology performance metrics. The methodology identifies a subset of model parameters which need to be verified enabling the metrology engineer to invest the minimum effort in stack and topography verification which will lead to performing target designs on the first design round.
P>Background and objectives:Neonatal sepsis is frequently associated with pathological activation of the coagulation system, leading to microcirculatory derangement and multiple organ dysfunction syndrome (MODS). The key role in the pathogenesis of sepsis has been attributed to proinflammatory cytokines. These trigger the development of disseminated intravascular coagulation (DIC) via the tissue factor-dependent pathway of coagulation. Pentoxifylline (PTX), a methylxanthine derivative that is used in peripheral vascular disease, has the potential to modify inflammatory response. The current work was designed to evaluate the potential protective effects of PTX against sepsis-induced microcirculatory derangement in Egyptian neonates.Methods:A double-blind placebo-controlled quasi-randomized design was used. Thirty-seven neonates with sepsis were randomly allocated into two groups. Seventeen patients were given PTX (5 mg/kg/h for 6 h; for 6 successive days). Twenty patients received equivalent volume of normal saline and represented the placebo group. Prothrombin time (PT), Activated partial thromboplastin time (APTT), fibrinogen, d-dimer, C-reactive protein (CRP), complete blood count (CBC), also hemodynamic parameters comprising arterial blood pressure, heart rate, capillary refill and urinary output were assessed in both groups before and after treatment.Results:Coagulation parameters in the two groups showed no significant differences. However, a higher incidence of DIC was observed in the placebo group neonates. PTX significantly lowered the percentage of bleeding (P = 0 center dot 0128) and less frequent use of FFP was observed in the PTX group (35 center dot 53% in PTX group vs. 80% in placebo group, P = 0 center dot 003). Incidence of MODS was significantly lower (P = 0 center dot 037) and hospital stay duration of survivors was significantly shorter (P = 0 center dot 044) in the PTX treated-infants.Conclusion:Pentoxifylline protects against sepsis-induced microcirculatory derangement in neonates. It significantly lowered the incidence of bleeding and MODS and shortened the length of hospital stay.
Bright field imaging based metrology performance enhancement is essential in the quest to meet lithography process control requirements below 65 nm half pitch. Recent work has shown that, in parallel to the lithographic processes themselves, the metrology tools are able to continue to perform despite the fact that the size of the features under test are often below the classical Rayleigh resolution limit of the optical system. Full electromagnetic simulation is a mandatory tool in the investigation and optimization of advanced metrology tool and metrology target architectures. In this paper we report on imaging simulations of overlay marks. We benchmark different simulation platforms and methods, focusing in particular on the challenges associated with bright-field imaging overlay metrology of marks with feature sizes below the resolution limit. In particular, we study the dependence of overlay mark contrast and information content on overlay mark pitch and feature size.
We report a case of a young woman suffering from a steady anthracycline-induced myocardiopathy with a decreased left ventricular function on echocardiography. A pregnancy was initiated, without worsening of the cardiopathy until 34 weeks. Nine days after delivery, an acute heart failure was observed leading to heart transplantation after cardiac assistance with heart cardiac device. As pregnancy is an extended stress test for a chronic failing heart, a multidisciplinary decision of pregnancy initiation and follow up should be preferred in pre and postpartum period, when such a cardiopathy exists.
In this publication we introduce a new metric for process robustness of overlay metrology in microelectronic manufacturing. By straightforward statistical analysis of overlay metrology measurements on an array of adjacent, nominally identical overlay targets the Overlay Mark Fidelity (OMF) can be estimated. We present the results of such measurements and analysis on various marks, which were patterned using a DUV scanner.The same reticle set was used to pattern wafers on different process layers and process conditions. By appropriate statistical analysis, the breakdown of the total ONE into a reticle-induced ONE component and a process induced ONE component was facilitated. We compare the ONE of traditional box-in-box overlay marks with that of new grating-based overlay marks and show that in all cases the grating marks are superior. The reticle related ONE showed an improvement of 30 % when using the new grating-based overlay mark. Furthermore, in a series of wafers run through an STI-process with different Chemical Mechanical Polish (CMP) times, the random component of the OMF of the new grating-based overlay mark was observed to be 40% lower and 50% less sensitive to process variation compared with Box in Box marks. These two observations are interpreted as improved process robustness of the grating mark over box in box, specifically in terms of reduced site by site variations and reduced wafer to wafer variations as process conditions change over time.Overlay Mark Fidelity, as defined in this publication, is a source of overlay metrology uncertainty, which is statistically independent of the standard error contributors, i.e. precision, TIS variability, and tool to tool matching. Current overlay metrology budgeting practices do not take this into consideration when calculating total measurement uncertainty (TMU). It is proposed that this be reconsidered, given the tightness of overlay and overlay metrology budgets at the 70 nm design rule node and below.