46163853
Enhancement of adhesion strength of Cu layer with low dielectric constant SiC: H liners in Cu interconnects
Abstract One of the primary candidates for the liner/etch stop layer in damascene process is silicon nitride (Si 3 N 4 ). However, silicon nitride has a high dielectric constant of 7.0. To reduce the effective dielectric constant in Copper (Cu) damascene structure, dielectric SiC:H (prepared by plasma enhanced chemical vapor deposition (PECVD) using trimethylsilane source) as the Cu diffusion barrier was studied. The dielectric constant of SiC:H used is 4.2. A systematic study was made on the properties of liner material and electro-chemically plated (ECP) Cu to enhance the adhesion strength in Cu/low-dielectric constant ( k ) multilevel interconnects. Though the effects of as Si 3 N 4 the liner have been much studied in the past, less is known about the relation between adhesion strength of ECP Cu layer and physical vapor deposited (PVD) Cu seeds, with seed thickness below 1000 A. The annealing of Cu seed layer was carried out at 200 °C in N 2 ambient for 30 min was carried out to study the impact on adhesion strength and the microstructure evolution on the adhesion between ECP Cu and its barrier layer. In the study, our claim that SiC:H barrier/etch stop layer is essential for replacing conventional Si 3 N 4 layer in enhancing adhesion strength and interfacial bonding between Cu/dielectric interconnects.
1111313
Resist pattern peeling assessment in DUV chemically amplified resist
As device size shrinks resist line peeling becomes more challenging. In this paper we studied the resist pattern peeling based on resist processing parameters and type of bottom antireflective coating (BARC), for patterning trench structures with different duty ratios, in copper and low k dual damascene process. To minimize resist poisoning in dual damascene process, acetal-based resist was used. Significant improvement in via poisoning was observed with this chemistry as compared to environmentally stable chemically amplified resist chemistry but at the cost of pattern peeling. In order to solve pattern peeling problem we tried to analyze key factors such as compatibility with BARC, post-exposure bake, BARC curing, adhesion and their effects. Pitch dependency on pattern peeling margin is observed.
135903312
Determination of the hardness and elastic modulus of low- k thin films and their barrier layer for microelectronic applications
This paper presents the experimental results and analysis of the elastic modulus and hardness for several thicknesses of dielectric films, namely low-k films and their barrier layer, using the nano-indentation technique. The elastic modulus and hardness of the films were determined by "normal" nano-indentation analysis. The data were then analyzed by rearranging the load-displacement data (P-h) obtained by nano-indentation in such a way that the applied load divided by the corresponding displacement (P/h) versus the displacement (h) was obtained, which effectively differentiates the film-only mechanical properties from those of the substrate. The low-k film, carbon-doped silicon oxide (SiOC), was prepared using a parallel plate PECVD system. The dielectric constant of the low-k film was measured to be 3.09, which is much lower than that of commonly used dielectric materials such as SiO2 (k ∼ 3.9). The hardness and elastic modulus of the film were measured to be approximately 2.23 and 13.98 GPa, respectively. To enhance the mechanical properties of the low-k thin film, a low-k barrier layer (SiCN:H) with better mechanical properties was deposited between the low-k film and the substrate or on top of the low-k film. It was found that the barrier layer improved the mechanical properties of the low-k film and the barrier layer stacked in certain circumstances. The effects of the arrangement of the barrier layer and the low-k film on the mechanical behavior of the bi-layer system were studied in detail.
23462768
A method for deep etching in dielectric films for 3D-chip and photonics applications
Abstract In this paper, RIE of thick undoped silicate glass (USG) films for various applications is described. Though moderate etch rates (∼0.4 μm/min) were achieved for USG film, process development was quite challenging due to stringent requirements of deep USG etching (>6 μm) and vertical profile. Alternatively, etch process with higher etch rate (1.0 μm/min) was also evaluated for profile angle and results were found not comparable to low etch rate process. However, low etch rate process was found to have tool limitations and an alternate method called ‘discrete etching’ was proposed and successfully verified. Promising results were obtained with etch depth (6 μm) and vertical profile (∼89.50°) in USG as well as SiON films. Based on the results discrete etching method was found to have provided advantage of unlimited capability for deep etching.
35084564
Effect of test condition and stress free temperature on the electromigration failure of Cu dual damascene submicron interconnect line-via test structures
Atomic flux divergence (AFD) based finite element analyses have been performed to show the difference in the electromigration (EM) failure mechanisms at different test conditions for Cu dual damascene line-via test structures. A combined driving force approach adapted in the model consists of driving forces from electron-wind, stress-migration and thermo-migration. It is shown that the failure mechanisms depend on the test condition and the stress free temperature of the structure. As the failure time depends on the failure mechanisms, the life-time prediction from accelerated test would be inaccurate if the invariability of failure mechanisms is assumed. It is also found that the interconnect life-time can be improved by lowering the final annealing temperature of the structure.
26545951
Placement of scattering bars in binary and attenuated phase shift mask for damascene trench patterning
Abstract Scattering bars have been very effective technique to increase the common lithography process window for patterns with design rules 0.18 μm and below. This paper studies the placement of scattering bars in binary and attenuated phase shift mask in damascene trench patterning. Different partial coherence values are used to compare the scattering bar effect in binary and 8% attenuated phase shift mask. At low partial coherence ( σ ) the trench size has been found more sensitive to scattering bar parameters than at high σ . Scattering bar separation is found more effective than size to affect the trench critical dimension (CD). At low partial coherence a deep valley or ‘V’ shaped CD trend is found in scattering bar separation versus CD curve. CD dip is more using APSM as compared to binary mask. The process latitude is poor at valley as compared to top. Also, 3 sigma CD variation and range is higher at valley as compared to other separations of the scattering bars.
13502244
Object Tracking with Bayesian Estimation of Dynamic Layer Representations
Decomposing video frames into coherent 2D motion layers is a powerful method for representing videos. Such a representation provides an intermediate description that enables applications such as object tracking, video summarization and visualization, video insertion, and sprite-based video compression. Previous work on motion layer analysis has largely concentrated on two-frame or multi-frame batch formulations. The temporal coherency of motion layers and the domain constraints on shapes have not been exploited. This paper introduces a complete dynamic motion layer representation in which spatial and temporal constraints on shape, motion and layer appearance are modeled and estimated in a maximum a-posteriori (MAP) framework using the generalized expectation-maximization (EM) algorithm. In order to limit the computational complexity of tracking arbitrarily shaped layer ownership, we propose a shape prior that parameterizes the representation of shape and prevents motion layers from evolving into arbitrary shapes. In this work, a Gaussian shape prior is chosen to specifically develop a near-real-time tracker for vehicle tracking in aerial videos. However, the general idea of using a parametric shape representation as part of the state of a tracker is a powerful one that can be extended to other domains as well. Based on the dynamic layer representation, an iterative algorithm is developed for continuous object tracking over time. The proposed method has been successfully applied in an airborne vehicle tracking system. Its performance is compared with that of a correlation-based tracker and a motion change-based tracker to demonstrate the advantages of the new method. Examples of tracking when the backgrounds are cluttered and the vehicles undergo various rigid motions and complex interactions such as passing, turning, and stop-and-go demonstrate the strength of the complete dynamic layer representation.
8038424
Robust Object Matching for Persistent Tracking with Heterogeneous Features
This paper addresses the problem of matching vehicles across multiple sightings under variations in illumination and camera poses. Since multiple observations of a vehicle are separated in large temporal and/or spatial gaps, thus prohibiting the use of standard frame-to-frame data association, we employ features extracted over a sequence during one time interval as a vehicle fingerprint that is used to compute the likelihood that two or more sequence observations are from the same or different vehicles. Furthermore, since our domain is aerial video tracking, in order to deal with poor image quality and large resolution and quality variations, our approach employs robust alignment and match measures for different stages of vehicle matching. Most notably, we employ a heterogeneous collection of features such as lines, points, and regions in an integrated matching framework. Heterogeneous features are shown to be important. Line and point features provide accurate localization and are employed for robust alignment across disparate views. The challenges of change in pose, aspect, and appearances across two disparate observations are handled by combining a novel feature-based quasi-rigid alignment with flexible matching between two or more sequences. However, since lines and points are relatively sparse, they are not adequate to delineate the object and provide a comprehensive matching set that covers the complete object. Region features provide a high degree of coverage and are employed for continuous frames to provide a delineation of the vehicle region for subsequent generation of a match measure. Our approach reliably delineates objects by representing regions as robust blob features and matching multiple regions to multiple regions using earth mover's distance (EMD). Extensive experimentation under a variety of real-world scenarios and over hundreds of thousands of confirmatory identification (CID) trails has demonstrated about 95 percent accuracy in vehicle reacquisition with both visible and infrared (IR) imaging cameras
27240142
Two optimal peer selection problems
Many peer computers today participate in peer-to-peer file sharing applications in which the computers contribute storage and bandwidth resources. Of course, applications can only harness the resource pool if peers make available their surplus resources to them. It is widely documented, however, that the P2P systems are havens for "free riders": a significant fraction of users do not contribute any resources, and a minute fraction of users contribute the majority of the resources. Clearly, to improve the performance of existing P2P file sharing systems, and to enable new classes of P2P applications, a compelling incentive system needs to be put in place.
5884426
Validation of an optical flow method for tag displacement estimation
Presents a validation study of an optical-flow method for the rapid estimation of myocardial displacement in magnetic resonance tagged cardiac images. This registration and change visualization (RCV) software uses a hierarchical estimation technique to compute the flow field that describes the warping of an image of one cardiac phase into alignment with the next. This method overcomes the requirement of constant pixel intensity in standard optical-flow methods by preprocessing the input images to reduce any intensity bias which results from the reduction in stripe contrast throughout the cardiac cycle. To validate the method, SPAMM-tagged images were acquired of a silicon gel phantom with simulated rotational motion. The pixel displacement was estimated with the RCV method and the error in pixel tracking was <4% 1000 ms after application of the tags, and after 30/spl deg/ of rotation. An additional study was performed using a SPAMM-tagged multiphase slice of a canine left ventricle. The true displacement was determined using a previously validated active contour model (snakes). The error between methods was 6.7% at end systole. The RCV method has the advantage of tracking all pixels in the image in a substantially shorter period than the snakes method.
9621286
Unsupervised Learning of Discriminative Edge Measures for Vehicle Matching between Nonoverlapping Cameras
This paper proposes a novel unsupervised algorithm learning discriminative features in the context of matching road vehicles between two nonoverlapping cameras. The matching problem is formulated as a same-different classification problem; which aims to compute the probability of vehicle images from two distinct cameras being from the same vehicle or different vehicle(s). We employ a novel measurement vector that consists of three independent edge-based measures and their associated robust measures computed from a pair of aligned vehicle edge maps. The weight of each measure is determined by an unsupervised learning algorithm that optimally separates the same-different classes in the combined measurement space. This is achieved with a weak classification algorithm that automatically collects representative samples from same-different classes, followed by a more discriminative classifier based on Fisher's linear discriminants and Gibbs sampling. The robustness of the match measures and the use of unsupervised discriminant analysis in the classification ensures that the proposed method performs consistently in the presence of missing/false features, temporally and spatially changing illumination conditions and systematic misalignment caused by different camera configurations. Extensive experiments based on real data of more than 200 vehicles at different times of the day demonstrate promising results.