矩形缺陷轮廓的成品率模型

现有成品率及关键面积估计模型中,假定缺陷轮廓为圆,而实际缺陷轮廓为非规则形状.本文提出了矩形缺陷轮廓的成品率模型,该模型与圆模型相比,考虑了缺陷的二维分布特性,接近真实缺陷形状及IC版图布线和成品率估计的特点.比较了新模型与真实缺陷及其圆模型引起的成品率损失,表明新模型在成品率估计方面更加精确,这对成品率精确估计与提高有重要意义.     

真实缺陷的矩形模型及其关键面积计算

在集成电路(IC)中,为了进行有效的成品率估计和故障分析,与光刻有关的缺陷形状通常假设为圆模型.然而,真实缺陷的形状多种多样.本文提出一种真实缺陷的矩形模型及与之相关的关键面积计算模型,该模型既考虑了真实缺陷的形状又考虑了IC版图布线的特点.在缺陷引起故障概率预测方面,仿真结果表明新模型比圆模型更接近真实缺陷引起的故障概率.     

考虑缺陷形状分布的IC成品率模型

实现了基于圆缺陷模型的蒙特卡洛关键面积及成品率估计,模拟了圆缺陷模型估计的成品率误差与缺陷的矩形度之间的关系,提出了更具有一般性的两种集成电路成品率模型,它们分别对应于矩形度相同和不同的缺陷．仿真结果表明该模型为成品率的精确表征提供了新途径．     

IC缺陷轮廓分形维估计的小波方法

为了有效的进行集成电路成品率预报和故障分析,与光刻有关的硅片表面缺陷通常被假定为圆形、椭圆或方形.然而,真实缺陷的形貌是多种多样的,它们的形状对集成电路的成品率估计有重要影响.本文讨论了缺陷轮廓所具有的分形特征,并用小波变换的方法对其分形维数进行了估计,估计结果与实例的特征相符,从而为缺陷轮廓的表征和计算机模拟提供了新的特征参数.     

Equivalent circular defect model of real defect outlines in the ICmanufacturing process

For efficient yield prediction and inductive fault analysis of integrated circuits (IC's), it is usually assumed that defects related to photolithography have the shape of circular discs or squares. Real defects, however, exhibit a great variety of shapes. This paper presents an accurate model to characterize those real defects. The defect outline is used in this model to determine an equivalent circular defect such that the probability that the circular defect causes a fault is the same as the probability that the real defect causes a fault, so a norm is available which ran be used to determine the accuracy of a defect model, and thus estimate approximately the error that will be aroused in the prediction of fault probability of a pattern by using circular defect model. Finally, the new model is illustrated with the real defect outlines obtained by optical inspection     

IC缺陷轮廓的分形插值模型

现用于集成电路(IC)成品率预报及故障分析的缺陷模型均是用圆或正方形来代替真实缺陷的复杂轮廓进行近似建模的,从而在模型中引入了很大的误差。本文利用分形插值的思想直接对真实缺陷的轮廓进行模拟,从而提出了一种新的缺陷轮廓表征模型。实验结果表明:与传统的最大圆模型、最小圆模型及椭圆模型相比,新模型的建模精度有了很大的提高。     

一种IC缺陷轮廓建模的新方法

现用于集成电路（ＩＣ）成品率预报及故障分析的缺陷模型均是用圆或正方形来代替真实缺陷的复杂轮廓进行近似建模的,从而在模型中引入了很大的误差。本文利用分段线性插值瓣思想直接对真实缺陷的方向尺寸进行逼近,从而提出了一种亲折缺陷轮廓表征模型。实验结果表明：与传统的最大圆模型、最小圆模型及椭圆模型相比,新模型的建模精度有了较大的提高。     

Modeling of real defect outlines and parameter extraction using acheckerboard test structure to localize defects

For efficient yield prediction and inductive fault analysis, it is usually assumed that defects have the shape of circular discs or squares. Real defects, however, exhibit a great variety of different shapes. This paper presents a more accurate model. The defect outline is approximated by an ellipse, and an equivalent circular defect is determined that causes a fault with the same probability as the real defect. To utilize this model, only the maximum and the minimum extension of detected defects have to be determined. That can be done easily using a novel test structure design. The checkerboard test structure uses the boundary pad frame of standard chips and thus achieves a large defect sensitive area. This area is partitioned into many small regions that can be analyzed separately. Defects are localized by simple electrical measurements. This allows an efficient optical inspection that can provide detailed information about the detected defects     

基于缺陷均匀分布的集成电路制造成品率与可靠性之间的关系模型

在集成电路可制造性设计研究中,成品率与可靠性之间的关系模型备受人们关注.缺陷对成品率和可靠性的影响不仅与出现在芯片上的缺陷粒径大小有关而且与缺陷出现在芯片上的位置有关.本文主要考虑了出现在互连线上的金属丢失物缺陷对互连线的影响,分析了同一粒径的缺陷出现在互连线不同位置对互连线有效宽度的影响,给出了基于缺陷均匀分布的互连线平均有效宽度,结合已有成品率和可靠性估计模型,提出了基于缺陷位置信息的集成电路制造成品率与可靠性之间的关系模型.在工艺线稳定的情况下,利用该工艺线的制造成品率可以通过该关系式有效地估计出产品的可靠性,从而有效地缩短新产品的研发周期.     

Introducing dependency into IC yield models

Many models have been proposed to explain the distribution of point defects on integrated circuit (IC) chips. The most popular of these models are based on distributions derived from the Poisson distribution for describing the number of defects expected on a chip. These models do not inherently allow for dependence between the number of defects expected on two adjacent chips. This paper introduces a model for generating an IC defect distribution that allows for dependence in the number of defects on chips that are near one another. Simulations are done to compare the new dependent model to a previously proposed independent model. These simulations with the new model show defective chips clustered near each other on the water. This clustering property has been observed on real wafers. Methods of parameter and yield estimation in the dependent model are discussed.     

合金弹头超声检测缺陷定位方法研究

首先论述提出的一种结合信号包络线和阈值判定的缺陷定位方法,然后针对采集的合金弹头内部及近表面缺陷超声回波信号采用这种方法进行合金弹头缺陷定位。通过实验表明,该方法能够较准确地判断出合金弹头内部及近表面缺陷所在的位置,参照C扫描方式重构图,能直观地判定缺陷的位置、形状和大小,为合金弹头自动超声检测提供了一种有效的手段。     

基于高斯曲面特征矩阵的扩展目标形状估计

针对传统方法难以准确估计扩展目标形状的问题,提出一种新的基于高斯曲面拟合的量测模型和基于高斯曲面特征矩阵的形状估计算法。首先,建立能反映目标真实形状的结构点,并产生多个高斯曲面,通过曲面叠加形成任意形状的量测空间分布模型;然后,根据高斯曲面拟合原理,用矩阵表示该拟合曲面主要区域的分布特征,并通过映射方程建立矩阵坐标与笛卡尔坐标的映射关系;最后,通过贝叶斯滤波体系更新拟合矩阵。与现有算法相比,本文算法不需要准确预设目标形状,在量测噪声较大的环境下,可以自适应的拟合目标真实形状。并且,在不需要预设目标形状方程的情况下,可以估计包括空心形状在内的任意不规则目标形状。实验结果表明,在目标初始形状参数不准确的情况下,本文算法正确估计了飞机形状、空心形状和集群目标形状,并且具有较好的扩展目标形状估计性能和较强的鲁棒性。     

基于小波变换的IC缺陷轮廓曲线分形维估计

硅片表面缺陷轮廓的形状特征对集成电路(IC)成品率预报及故障分析有重要影响。讨论了IC缺陷轮廓所具有的分形特征,利用小波变换对其参数曲线的分形维数进行了估计,估计结果与实际特征相符,从而为缺陷轮廓特征的描述和计算机模拟提供了一条新的途径。     

基于BP神经网络的玻璃缺陷识别技术研究

为了准确、快速地对玻璃质量进行分类,提出一种基于BP神经网络的玻璃缺陷识别方法。由于不变矩与灰度共生矩阵分别可以描述图像的形状与纹理,在分析了缺陷灰度图像特点的基础上,将图像的纹理特征和不变矩特征融合,综合提取出一个分类能力更强的特征向量,再使用一个拟牛顿改进算法的三层前向BP网络。作为分类器,对常见的玻璃缺陷进行了识别。通过实验对比该方法和传统的单一特征识别法,证明该方法不仅具有更高的识别率,并且实时性较好,为玻璃缺陷的自动识别提供了一种新的途径。     

Yield fluctuations and defect models

This paper establishes a general statistical framework for analyzing wafer fallout data in order to obtain information about process induced defects. The statistical behavior of fallout during testing is characterized. A general model is presented that relates the yield to the test coverage and the defect distribution. This model incorporates arbitrary variations in the occurrence probabilities of different defects and arbitrary dependencies between the defects, although it still ignores correlations between the occurrence probability of a defect and whether or not this defect is detected. A statistical acceptance criterion for this model is proposed, based on a convexity property of the model. It is applied to a published set of yield data and shows that some striking features in these data cannot be due to mere statistical fluctuations. Some explanations of these features will be discussed.     

A new sensitivity model with blank space for layout optimization

As the technology scales advancing into the nanometer region, the concept of yield has become an increasingly important design metric. To reduce the yield loss caused by local defects, layout optimization can play a critical role. In this paper, we propose a new open sensitivity-based model with consideration of the blank space around the net, and study the corresponding net optimization. The proposed new model not only has a high practicability in the selection of nets to be optimized but also solves the issue of the increase in short critical area brought during the open optimization,which means to reduce the open critical area with no new short critical area produced, and thereby this model can ensure the decrease of total critical area and finally achieves an integrative optimization. Compared with the models available, the experimental results show that our sensitivity model not only consumes less time with concise algorithm but also can deal with irregular layout, which is out of the scope of other models. At the end of this paper, the effectiveness of the new model is verified by the experiment on the randomly selected five metal layers from the synthesized OpenSparc circuit layout.     

均匀圆阵二维波达角估计的Cramer-Rao界

均匀圆阵(UCA)是一种应用广泛的具有二位波达角估计能力的平面阵列。为了从理论上分析不同阵列参数下到达波方位角(AOA)、仰角估计精度,推导了均匀圆阵二维波达角估计的性能界,以此为基础分析了阵列孔径、阵元个数、快拍数以及来波仰角高低与到达角估计精度的关系,并通过对UCA-MUSIC算法计算机仿真验证了推导结果的正确性。研究结果为波达角估计类算法提供了可供参考的性能下界,圆阵设计时也不再需要大量的Monte Carlo仿真试验确定阵列参数,可直接从估计精度表达式中获得。     

基于弹性网稀疏表示的芯片参数成品率估算方法

当前集成电路芯片参数成品率估算通常预设大量扰动基函数进行芯片性能模型构建,易造成成品率估算方法复杂度过高.而若随意减少扰动基函数数量,则极易造成成品率估算精度缺失.针对此问题,本文提出一种芯片参数成品率稀疏估算方法.该方法首先根据工艺参数扰动建立具有随机不确定性的漏电功耗模型;然后按照关键度高低,利用弹性网自适应选取关键扰动基函数对漏电功耗模型进行稀疏表示建模;最后,利用贝叶斯理论及马尔科夫链方法对漏电功耗成品率进行估算.实验结果表明,该方法不仅可以使所构建的漏电功耗模型具有一般性和稀疏性优点,而且能够对漏电功耗成品率进行准确估算,与蒙特卡罗仿真结果相比估算误差不超过5%.同时,相较于蒙特卡罗采样,该方法还可以大幅减少算法仿真时间,具有更好的仿真效率.     

IC缺陷轮廓多分形特征研究

IC真实缺陷轮廓曲线的形状特征对集成电路成品率预报及故障分析有重要影响。该文提出缺陷轮廓曲线具有多分形特征,以某一真实缺陷为例,用小波变换模极大(WTMM)的方法估计了其轮廓曲线参数方程的多分形谱,该结果为硅片表面缺陷的精细表征及其计算机模拟作了有益探索。     

Reconstruction of sculpture from its profiles with unknown camera positions

Profiles of a sculpture provide rich information about its geometry, and can be used for shape recovery under known camera motion. By exploiting correspondences induced by epipolar tangents on the profiles, a successful solution to motion estimation from profiles has been developed in the special case of circular motion. The main drawbacks of using circular motion alone, namely the difficulty in adding new views and part of the object always being invisible, can be overcome by incorporating arbitrary general views of the object and registering its new profiles with the set of profiles resulted from the circular motion. In this paper, we describe a complete and practical system for producing a three-dimensional (3-D) model from uncalibrated images of an arbitrary object using its profiles alone. Experimental results on various objects are presented, demonstrating the quality of the reconstructions using the estimated motion.