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.     

Conduction Efficiency and Strength of Electronically Conductive Adhesive Joints

Electronically conductive adhesives are being considered as an alternative to solder for interconnection in microelectronics. In order to gain insight regarding electrical and mechanical performance properties of this class of adhesive interconnections, overlap joints were made. Joint resistance and mechanical bond strength were measured before and after environmental stressing.     

Method For Studying Surface Topography and Roughness of Onion and Garlic Skins For Coating Purposes

Surface topography and roughness of garlic and onion skins were studied by atomic force microscopy in order to estimate the surface area. Image-processing and Arc/Info software were used to interpret the data. The calculated ratio between apparent and measured surfaces (roughness factor) deviated from 1.11 to 1.15 for untreated and chloroform-treated onion skin, respectively. For garlic, higher values were detected for the untreated skin. The higher the roughness factor, when the coating solutions are easily spread on the fruit or vegetable surfaces, the better the adhesion between coating and skin. A knowledge of true surface areas can help to better estimate required coating-solution volumes.     

High-energy X-ray diffraction and topography investigation of CdZnTe

High-energy transmission x-ray diffraction techniques have been applied to investigate the crystal quality of CdZnTe (CZT). CdZnTe has shown excellent performance in hard x-ray and gamma detection; unfortunately, bulk nonuniformities still limit spectroscopic properties of CZT detectors. Collimated high-energy x-rays, produced by a superconducting wiggler at the National Synchrotron Light Source’s X17B1 beamline, allow for a nondestructive characterization of thick CZT samples (2–3 mm). In order to have complete information about the defect distribution and strains in the crystals, two series of experiments have been performed. First, a monochromatic 67 keV x-ray beam with the size of 300×300 μm² was used to measure the rocking curves of CZT crystals supplied by different material growers. A raster scan of a few square centimeter area allowed us to measure the full-width at half-maximum (FWHM) and shift in the peak position across the crystal. The rocking curve peak position and its FWHM can be correlated with local stoichiometry variations and other local defects. Typically, the FWHM values ranging from 8.3 arcsec to 14.7 arcsec were measured with the best crystal used in these measurements. Second, transmission white beam x-ray topography (WBXT) was performed by using a 22 mm×200 μm beam in the energy range of 50 keV to 200 keV. These types of measurements allowed for large area, high-resolution (50 μm) scans of the samples. Usually, this technique is used to visualize growth and process-induced defects, such as dislocations, twins, domains, inclusions, etc. the difference in contrast shows different parts of the crystal that could not be shown otherwise. In topography, good contrast is indicative of a high quality of the sample, while blurred gray shows the presence of defects. Correlation with other techniques (e.g., infrared (IR) mapping and gamma mapping) was also attempted. Our characterization techniques, which use highly penetrating x-rays, are valid for in-situ measurements, even after electrical contacts have been formed on the crystal in a working device. Thus, these studies may lead to understanding the effects of the defects on the device performance and ultimately to improving the quality of CZT material required for device fabrication. It is important to study crystals from different ingot positions (bottom, center, and top); consequently, more systematic studies involving scans from center to border are planned.     

用于X光动态形貌实验的高温样品室及其温度控制系统

为进行动态形貌实验研究，在北京同步辐射装置形貌学实验站建立了高低温样品环境室，用英国欧陆控制器组成温度控制系统，用ＰＩＤ控制和时间比例法进行温度控制，系统温度分辨率在０．０５℃。     

起伏地表下基于高阶广义屏算子的叠前深度偏移

:基于波场逐步累加的“直接下延”法是解决复杂地表和地质条件下叠前深度偏移成像的有效手段。波动方程的深度偏移对介质速度横向变化有较强的适应性，适宜于复杂构造的偏移成像。高阶广义屏算子随其阶数的增多，其精度也将越高。基于高阶广义屏算子，应用直接下延法，实现了起伏地表条件下的高阶广义屏算子深度偏移。在具体的计算中，采用一系列的近似以避开奇值点，保证算法的稳定性。模型试算结果表明了该方法的有效性。     

A Comparative Study on Asperity Peak Modeling Methods

The peak identification scheme based method(three-point definition) and the spectral moments based method(spectral moment approach) are both widely used for asperity peak modeling in tribology. To discover the differences between the two methods, a great number of rough surface profile samples with various statistical distributions are first randomly generated using FFT. Then the distribution parameters of asperity peaks are calculated for the generated samples with both methods. The obtained results are compared and verified by experiment. The variation rules of the differences between the two methods with statistical characteristics of rough surfaces are investigated. To explain for the discovered differences, the assumptions by spectral moment approach that the joint distribution of surface height, slope and curvature is normal and that the height distribution of asperities is Gaussian, are examined. The results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of [z], [z′] and [z′′], and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent, 20 for instance.     

巧妙利用地形,营造宜人的休闲居住空间——以温州洞头某滨海山地项目规划设计为例

以温州洞头某滨海山地项目的规划设计方案为例,从总体布局、交通组织、景观营造、建筑设计等方面入手,对如何利用山地的特殊条件,在保护自然生态环境免受大破坏的前提下,创造宜人的居住空间进行探讨,供类似工程借鉴。     

谈CASS7.0在新农村建设规划中的应用

介绍了在社会主义新农村建设规划中,如何应用CASS7.0软件测绘出高精度、大比例尺的数字地形图,并对测绘要点进行了论述,指出采用CASS7.0软件进行地形图测绘,不仅提升了测绘速率,而且提高了成图精度,值得推广应用。     

怒江地区泥石流形成机理初探

结合具体工程实例,从地形地貌、气象与水文方面入手,对怒江地区泥石流形成条件进行了深入剖析,并对泥石流的地形、冲蚀、淤积物和植被特征进行了阐述,为野外鉴定泥石流提供了参考。