High Resolution Measurements of Two-dimensional Dopant Diffusion in Silicon

2000 ◽  
Vol 6 (3) ◽  
pp. 237-245
Author(s):  
G. D’Arrigo ◽  
C. Spinella

Abstract We report detailed experimental results on the electrochemical selective etching of doped Si. By using transmission electron microscopy analyses and spreading resistance measurements we investigated the dependence of the etching selectivity on the different parameters of the electrochemical cell, i.e., bias voltage and chemical solution. In B-doped samples immersed in buffered HF, the increase of bias voltage from 0.5 to 1 V produces a slight improvement of the etching selectivity and a B concentration as low as 1 × 1017 cm−3 can be successfully delineated at 1 V. A further improvement is achieved by using HF:HNO3:CH3COOH or HF:HCl chemical mixtures for which the delineation sensitivity approaches the value of 1 × 1016 cm−3. In buffered HF As-doped regions can be delineated to a concentration of 2 × 1017 cm−3, independently of the bias voltage, in the range 2–4 V. These results were used to measure the 2D doping diffusion profiles in silicon wafers patterned with polycrystalline Si strips and implanted with As or B, by using different tilt and twist angles. The high resolution of the electrochemical delineation allowed us to evaluate very accurately the effects of the implant angles on the lateral doping distribution.

2000 ◽  
Vol 6 (3) ◽  
pp. 237-245 ◽  
Author(s):  
G. D’Arrigo ◽  
C. Spinella

AbstractWe report detailed experimental results on the electrochemical selective etching of doped Si. By using transmission electron microscopy analyses and spreading resistance measurements we investigated the dependence of the etching selectivity on the different parameters of the electrochemical cell, i.e., bias voltage and chemical solution. In B-doped samples immersed in buffered HF, the increase of bias voltage from 0.5 to 1 V produces a slight improvement of the etching selectivity and a B concentration as low as 1 × 1017 cm−3 can be successfully delineated at 1 V. A further improvement is achieved by using HF:HNO3:CH3COOH or HF:HCl chemical mixtures for which the delineation sensitivity approaches the value of 1 × 1016 cm−3. In buffered HF As-doped regions can be delineated to a concentration of 2 × 1017 cm−3, independently of the bias voltage, in the range 2–4 V. These results were used to measure the 2D doping diffusion profiles in silicon wafers patterned with polycrystalline Si strips and implanted with As or B, by using different tilt and twist angles. The high resolution of the electrochemical delineation allowed us to evaluate very accurately the effects of the implant angles on the lateral doping distribution.


1981 ◽  
Vol 44 (335) ◽  
pp. 287-291
Author(s):  
E. J. W. Whittaker ◽  
B. A. Cressey ◽  
J. L. Hutchison

AbstractSections perpendicular to [001] of ion-thinned specimens of fibrous grunerite (amosite) have been examined by high-resolution transmission electron microscopy. In this orientation, two kinds of dislocation have been observed with about equal frequency. One lies on [001] and has a Burgers vector a. The other is on [001] and has a Burgers vector ½a+½b Interpretation of features associated with these dislocations has been assisted by the use of two-dimensional models of I-beam cross-sections which can be interlocked to simulate the possible modes of stacking.


Author(s):  
R. Gronsky

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.


Author(s):  
Jan-Olle Malm ◽  
Jan-Olov Bovin

Understanding of catalytic processes requires detailed knowledge of the catalyst. As heterogeneous catalysis is a surface phenomena the understanding of the atomic surface structure of both the active material and the support material is of utmost importance. This work is a high resolution electron microscopy (HREM) study of different phases found in a used automobile catalytic converter.The high resolution micrographs were obtained with a JEM-4000EX working with a structural resolution better than 0.17 nm and equipped with a Gatan 622 TV-camera with an image intensifier. Some work (e.g. EDS-analysis and diffraction) was done with a JEM-2000FX equipped with a Link AN10000 EDX spectrometer. The catalytic converter in this study has been used under normal driving conditions for several years and has also been poisoned by using leaded fuel. To prepare the sample, parts of the monolith were crushed, dispersed in methanol and a drop of the dispersion was placed on the holey carbon grid.


Author(s):  
Quintin J. Lai ◽  
Stuart L. Cooper ◽  
Ralph M. Albrecht

Thrombus formation and embolization are significant problems for blood-contacting biomedical devices. Two major components of thrombi are blood platelets and the plasma protein, fibrinogen. Previous studies have examined interactions of platelets with polymer surfaces, fibrinogen with platelets, and platelets in suspension with spreading platelets attached to surfaces. Correlative microscopic techniques permit light microscopic observations of labeled living platelets, under static or flow conditions, followed by the observation of identical platelets by electron microscopy. Videoenhanced, differential interference contrast (DIC) light microscopy permits high-resolution, real-time imaging of live platelets and their interactions with surfaces. Interference reflection microscopy (IRM) provides information on the focal adhesion of platelets on surfaces. High voltage, transmission electron microscopy (HVEM) allows observation of platelet cytoskeletal structure of whole mount preparations. Low-voltage, high resolution, scanning electron microscopy allows observation of fine surface detail of platelets. Colloidal gold-labeled fibrinogen, used to identify the Gp Ilb/IIIa membrane receptor for fibrinogen, can be detected in all the above microscopies.


Author(s):  
Chung-Ching Lin ◽  
Franco Stellari ◽  
Lynne Gignac ◽  
Peilin Song ◽  
John Bruley

Abstract Transmission Electron Microscopy (TEM) and scanning TEM (STEM) is widely used to acquire ultra high resolution images in different research areas. For some applications, a single TEM/STEM image does not provide enough information for analysis. One example in VLSI circuit failure analysis is the tracking of long interconnection. The capability of creating a large map of high resolution images may enable significant progress in some tasks. However, stitching TEM/STEM images in semiconductor applications is difficult and existing tools are unable to provide usable stitching results for analysis. In this paper, a novel fully automated method for stitching TEM/STEM image mosaics is proposed. The proposed method allows one to reach a global optimal configuration of each image tile so that both missing and false-positive correspondences can be tolerated. The experiment results presented in this paper show that the proposed method is robust and performs well in very challenging situations.


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