Combined use of three-dimensional X-ray diffraction imaging and micro-Raman spectroscopy for the non-destructive evaluation of plasma arc induced damage on silicon wafers

The practicality of plasma etching, combined with low temperature and directional process capabilities make it an integral part of the IC manufacturing process. A significant cause of damage to wafers during plasma processing is arcing damage. Plasma arcing damage results in large pits and non-uniformities on the wafer surface which can lead to wafer breakage and high yield losses.Thus a non-destructive wafer damage metrology is crucial to the understanding of wafer failure mechanisms. We report on the successful use of a combined suite of non-destructive metrology techniques to locate the arc damage sites and examine the physical processes which have occurred as a result of the damage. These consist of 3D X-ray diffraction imaging (3D-XRDI), micro-Raman spectroscopy (μRS), and scanning electron microscopy (SEM).In the case of the two examples examined in this study the plasma induced damage on the wafer surface appears as regions of damage ranging from 100 μm to 1000 μm in diameter. 3D-XRDI shows that the strain fields propagate out from the damage site in all directions, with the damage penetrating up to ? of the way through the substrate. K-means clustering and false colouring algorithms are used to highlight the regions of interest in 3D-XRDI, and to enhance the analysis process. Sectioning of the 3D images has enabled non-destructive imaging of the internal damage in the samples at any location. Micro-Raman spectroscopy results indicate the presence of both crystalline and amorphous silicon. Strain measurements at the damage site show tensile strains as high as 500 MPa in certain situations, with strain levels increasing from the surface towards the bottom of the dislocation cell structures, which can be distinguished in the synchrotron X-ray topographs. 3D-XRDI and μRS results are in close correlation, proving the potential for 3D-XRDI as non-contact, non-destructive metrology particularly suited to these problems.     

Full-chip wire-oriented back-end-of-line TDDB hotspot detection and lifetime analysis

Time-dependent dielectric breakdown (TDDB) has become an important cause of failure for inter-metal dielectrics (IMD) in integrated circuits as feature sizes continue to shrink and novel materials are introduced. Although many studies have been conducted to understand the underlying physics of this issue, not enough work has been focused on evaluating TDDB lifetime of practical chip designs in the physical design stage. This paper proposes a full-chip TDDB failure analysis methodology to evaluate lifetime and identify TDDB hotspots in VLSI layouts, which are essentially interconnect wires that have high failure risk due to TDDB. The proposed method features three new techniques compared to existing methods. First, we have developed a partitioning-based scheme to deal with scaling of full-chip analysis by partitioning the full chip layout into small tiles. Second, for each tile, the new method calculates a newly-introduced TDDB failure metric called TDDB Damage for vulnerable wires. Such a wire-oriented TDDB analysis is the first of its kind and is very amenable for physical design as the wires can be easily adjusted or re-routed for TDDB-aware optimization. Third, the new method considers the impact of the non-uniform electric field calculated using the finite element method (FEM), which significantly improves the accuracy of TDDB risk evaluation. Experimental results show that the proposed new TDDB analysis method is more accurate than a recently proposed full-chip TDDB analysis method in which electrical field is treated as a constant value. Additionally, the proposed method can analyze a practical VLSI layout in a few hours.     

碲镉汞晶片表面加工损伤的电化学腐蚀观察方法

本文报道一种新的观察碲镉汞（ＣＭＴ）晶片表面加工损伤的方法──电化学腐蚀法。文中讨论了电化学腐蚀法的原理，给出了实验结果。实验表明：机械磨抛的ＣＭＴ晶片表面的加工损伤可用电化学腐蚀法清楚地揭示出来；磨抛产生的机械划痕在电化学腐蚀前后一一对应，而且腐蚀后可清晰、直观地看到腐蚀前看不见的机械划痕；结合化学腐蚀的方法测量了一定磨抛条件下Ｗ３．５磨料在ＣＭＴ晶片表面产生的最大加工损伤深度约３２～４０ｐｍ；机械磨抛产生的划痕和其在表面留下的应力沟道区是ＣＭＴ晶片表面在磨抛加工中受到损伤的主要机构。分析认为平均损伤深度主要影响磨抛ＣＭＴ晶片的表面复合速度，而最大加工损伤深度则对ＣＭＴ器件、特别是多元器件性能参数的均匀性影响比较大；故控制好ＣＭＴ晶片表面加工的最大损伤深度也是制备性能均匀的ＣＭＴ多元探测器的一个重要环节。     

含预制缺陷PBX模拟材料损伤演变的原位CT研究

为研究初始损伤对高聚物粘结炸药(PBX)在外力作用下结构变化与损伤行为的影响,采用预制缺陷的方式模拟了初始损伤,制备了不含预制缺陷、含斜45°非贯通缺陷以及含斜45°贯通缺陷的3组PBX模拟材料样品,利用经改进的圆弧压头巴西试验加载方式,在X射线CT系统上开展原位研究。通过数字图像处理技术获得了裂纹及孔隙的三维形态、尺寸及空间分布信息。利用ABAQUS软件对试验进行了有限元模拟。结果表明,预制缺陷与巴西试验加载方向呈45°角时,预制缺陷会破坏其加载方式的对称性,样品的损伤行为也会相应发生改变;非贯通缺陷与贯通缺陷对样品的损伤行为的影响有很大区别;含非贯通缺陷的样品会发生分层现象,即表层缺陷对样品损伤行为的影响范围主要集中在含有缺陷的部分;模拟的结果与试验结果吻合较好,在一定程度上解释了试验现象。     

杀伤爆破弹综合威力评估方法与应用研究

为研究杀伤爆破弹（简称杀爆弹）综合威力定量评估方法,提出一种采用毁伤幅员定量表征与评估杀爆弹（战斗部）综合威力的原理和方法,推导了战斗部威力场和目标毁伤律模型相结合的毁伤幅员计算模型;进行两种杀爆弹的静爆试验,依据试验数据验证和修正了威力场模型,并以此为实例进行了毁伤幅员计算以及综合威力定量评估与分析。研究结果表明,所提出的杀爆弹综合威力评估方法,可实现综合威力的归一化定量表征与评估,能够定量地分析不同弹药对同一目标以及同一弹药对不同目标的毁伤能力差别。     

舰载无人机传输舰艇毁伤信息能力研究

通过对舰载无人机传输舰艇毁伤信息能力的研究,分析舰载无人机传输舰艇毁伤信息中的信息传输组织,明确舰载无人机传输舰艇毁伤信息能力指标,建立舰载无人机传输舰艇毁伤信息能力模型,为海战场打击效果评估提供重要支持。     

激光器窗口的旋转效应

通过数值计算比较研究了静止、同心旋转、偏心旋转三种模式下高能激光器窗口工作过程中温度场和应力场的特征及其演变规律。研究表明，旋转式激光器窗口不但可使温度场和应力场轴对称化，且可降低最高温升、最大拉应力和最大剪应力；一定偏心距的偏心旋转可以起到消去拉应力、减小剪切应力的作用，从而使激光器窗口的抗激光损伤的能力有较大幅度的提高。     

基于HHT技术的二维结构损伤定位研究

希尔伯特-黄变换(HHT)是具有适应性的局部化时频分析方法,适用于非线性、非平稳的信号分析。该文基于主动监测技术,将结构健康和损伤状态下的响应信号进行对比,二者的差信号实际上是激励信号通过损伤折射后被接收到的一种信号。利用HHT对差信号和激励信号等进行分析,提取信号群速度的到达时刻,从而得到差信号的传播时间。根据差信号传播路径的分析,并结合四点圆弧定位方法,实现二维结构的损伤定位,实验验证利用HHT信号处理技术能够有效准确的进行复合材料结构的二维损伤定位。     

HTPB推进剂药柱在变温环境下的累积损伤分析

为研究变温环境对固体火箭发动机的影响,基于热粘弹性模型和累积损伤模型,对某HTPB推进剂药柱在变温环境下的应力响应和累积损伤进行了分析计算。结果表明,药柱损伤随着环境严酷度的增大而增大,温度冲击环境比温度循环对药柱产生的损伤要大。在温度冲击环境下,温度范围、推进剂材料参数对药柱的损伤有较大的影响,平衡模量和膨胀系数的影响有相同的趋势。研究结果可为固体火箭发动机的贮存和使用寿命预估提供技术支持。     

超近程拦截系统中毁伤元的最佳延时起爆时间的控制

为了准确计算毁伤元延时起爆时间、提高超近程系统拦截空中目标的有效性,采用线性切割器作为毁伤元,且研究线性切割器的原理及特点,在地面坐标系中建立线性切割器和目标的运动模型.通过对模型的计算及分析得到毁伤元最佳起爆延时时间段,它对超近程反导的弹目交汇时间计算有一定的指导意义.同时得到在最佳起爆延时时间段对线性切割器的射角及时调整可以更有效的拦截目标.