基于THz-TDR的芯片金属微带线缺陷检测

针对体积小、走线密集、集成度高的封装芯片缺陷检测,目前的主要检测手段存在精度低、周期长等缺点。为弥补传统检测方法的不足,作者结合太赫兹技术与时域反射技术,探究对芯片上金属导线缺陷检测的可行性。首先在不同宽度的金属微带线上加工了不同比例的凸起、凹槽缺陷,模拟集成芯片中金属导线的不完全开/短路等阻抗不匹配情况,利用太赫兹时域反射计采集其时域反射信号。然后根据时域反射脉冲对应的时间分别对不同缺陷程度、不同缺陷类型进行定性分析,并精确计算出了芯片上金属微带线的缺陷位置。最后利用有限元分析法对硅基底上存在缺陷的金属微带线进行仿真分析,与实验结果具有良好的一致性。该研究表明,太赫兹技术与时域反射技术结合能够实现对芯片上金属导线缺陷的诊断检测,为集成芯片的缺陷检测提供了经验参考。     

Interactions between clusters of self-interstitial atoms via a conservative climb in BCC–Fe

We conduct kinetic Monte Carlo simulations for the conservative climb motion of a cluster of self-interstitial atoms (SIAs) towards another SIA cluster in BCC–Fe; the conservative climb velocity is inversely proportional to the fourth power of the distance between them, as per the prediction based on Einstein’s equation. The size of the climbing cluster significantly affects its conservative climb velocity, while the size of the cluster that originates the stress field does not. The activation energy for the conservative climb is considerably greater than that derived in previous studies and strongly dependent on the climbing cluster size. The results presented in this study are the atomistic evaluation of the behaviour of SIA clusters through three-dimensional motion, which cannot be achieved using molecular dynamics techniques alone.     

Monitoring of the process of formation of epitaxial films with the use of ultrasoft x-ray spectroscopy

The distinctive features of the atomic and electronic structure of thin surface layers of substances in the process of formation of epitaxial silicon films on silicon are studied using the procedures of reflection and scattering of ultrasoft x-ray radiation. The angular distribution of the scattered x-ray radiation (the scattering indicatrices) and the near fine structure of SiL_2,3 spectra of reflection are investigated. The assumption of the sensitivity of the observed peak of anomalous scattering (the Yoneda peak) of x-ray radiation to the presence, in the surface regions of the materials, of extended double-boundary defects, the defects of packing, grain boundaries, dislocations, etc. is made. It is shown that the experimental procedure used makes it possible to obtain information on the surface layers of substances. Translated from Zhurnal Priklaldnoi Spektroskopii, Vol. 67, No. 4, pp. 496–498, July–August, 2000.     

The characteristics for H<Subscript> 2</Subscript><Superscript> +</Superscript>-like impurities confined by spherical quantum dots

The energy spectra of H₂ ⁺-like impurities confined in finite spherical quantum dots have been calculated as a function of the distance between nuclear with different sizes on the basis of effective-mass approximation by linear variational method. B-splines have been used as basis functions, which can easily construct the trial wavefunctions with appropriate boundary and cusp conditions. The quantitative analyses of the partial wave weights for ground state and some low lying states have been done.     

Micro-segregation model calculation of residual tin in boiler and pressure vessel steel

Tin is a typical residual element in steel and mainly originates from Sn-containing complex iron ore and steel scrap. The segregation of Sn in steel is harmful to the performances of steel. In this paper, the micro-segregation of residual element Sn during the solidification process of boiler and pressure vessel steel by micro-segregation model was studied. The results showed that the micro-segregation degree of Sn reduces apparently with the increase of cooling rate and remarkably deteriorates during the solidification process. When the initial content of C is higher than 0.1%, it will cause the solidification transform of the solid phase converting from the ferrite phase to austenite phase and the significant increase in the micro-segregation degree of Sn. However, increasing the initial contents of Si, Mn, P and S separately has non-significant effects on the micro-segregation degree of Sn. In addition, the improvement of initial content of Sn will lead to the micro-segregation degree decrease of Sn and has an inapparent impact on zero strength temperature and zero ductility temperature of the boiler and pressure vessel steel.     

Effect of defects on the electronic structure of a PbI2/MoS2 van der Waals heterostructure: A first-principles study

PbI2/MoS2,as a typical van der Waals(vdW)heterostructure,has attracted intensive attention owing to its remarkable electronic and optoelectronic properties.In this work,the effect of defects on the electronic structures of a PbI2/MoS2 heterointerface has been systematically investigated.The manner in which the defects modulate the band structure of PbI2/MoS2,including the band gap,band edge,band alignment,and defect energy-level density within the band gap is discussed herein.It is shown that sulfur defects tune the band gaps,iodine defects shift the positions of the band edge and Fermi level,and lead defects realize the conversions between the straddling-gap band alignment and valence-band-aligned gap,thus enhancing the light-absorption ability of the material.     

Spin-Hamiltonian parameters,defect model and defect structure for the tetragonal Mo5+ center in x-ray-irradiated α-ZnMoO4 crystals

ABSTRACT

The spin-Hamiltonian parameters (g factors g_i, hyperfine structure constants A_i (⁹⁵Mo⁵⁺) and A_i (⁹⁷Mo⁵⁺), i?=?// and ⊥) assigned to the tetragonal Mo⁵⁺ (4d¹) tetrahedral center in α-ZnMoO₄ crystal caused by a Mo⁶⁺(1) ion trapping an electron after x-ray irradiation are calculated from the high-order perturbation formulas resting on the two-mechanism model. The model takes account of both the effects of crystal-field (CF) mechanism concerning the CF excited states in the CF theory and that of the charge-transfer (CT) mechanism related to CT excited states. The calculated results are reasonably consistent with the experimental values, confirming this assignment (or defect model). The calculations also indicate that the effect of CT mechanism cannot be neglected. The defect structure (particularly, the angular distortion) and signs of constants A_i (⁹⁵Mo⁵⁺) and A_i (⁹⁷Mo⁵⁺) of this Mo⁵⁺ defect center are also decided from the calculations. The outcomes are discussed.     

Muffin‐tin potentials in EXAFS analysis

Muffin‐tin potentials are the standard tool for calculating the potential surface of a cluster of atoms for use in the analysis of extended X‐ray absorption fine‐structure (EXAFS) data. The set of Cartesian coordinates used to define the positions of atoms in the cluster and to calculate the muffin‐tin potentials is commonly also used to enumerate the scattering paths used in the EXAFS data analysis. In this paper, it is shown that these muffin‐tin potentials are sufficiently robust to be used to examine quantitatively contributions to the EXAFS data from scattering geometries not represented in the original cluster.     

激光微织构硬质合金表面润湿性

为了研究硬质合金表面激光微织构对其表面润湿性的影响,利用光纤激光不同功率（3,5,7,9,10 W）及不同加工次数（1,2,3,4,5）加工微凹坑,采用VHX1000c超景深三维显微镜、光学显微镜分析微凹坑形貌,利用CAM 200光学接触角仪测量表面微织构（微凹坑直径、深度和织构密度）与润湿性之间的关系。结果表明：随着激光功率的增大,微凹坑深度增加,直径变化不明显;硬质合金表面的亲水性能随着微凹坑深度的增加而减小;随着微凹坑直径的增大,亲水性增强;随着微织构密度的增加,亲水性出现极值。     

BaSnF4 fast ion conductor: Variations versus the method of preparation and anomalous temperature variation of the quadrupole splitting

A new method of preparation of high performance fluoride ion conductor, BaSnF₄, by water leaching of newly discovered barium tin(II) chloride fluorides, has been designed, and the materials have been studied and compared to the solid prepared by the usual dry method. The unit-cell parameters and crystallite dimensions were found to vary with the method of preparation. In addition, the crystallite dimensions were found to be highly anisotropic for the samples obtained by the wet method. The Mössbauer spectrum is made of a large tin(II) quadrupole doublet, and a broad tin(IV) oxide peak due to surface oxidation. The tin(II) spectrum is in agreement with covalently bonded tin(II) having a strongly stereoactive lone pair. An unusually high dependence of the quadrupole splitting at low temperatures was observed (5.8 times larger than for α-SnF₂).