Defect mapping

Defects in a SCR, which is present under reverse bias, can be tested in a similar way. Figure 10.6 c shows the same wafer as in Fig. 10.6 e after removal of the oxide and under cathodic polarization in the dark. Hydrogen bubbles caused by the dark current now decorate nickel silicide precipitates that short-circuit the SCR. Nickel precipitates are known to increase the dark current of a p-type Si electrode under reverse bias by orders of magnitude [Wa4]. If the bias is increased the copper silicide precipitates also become visible, as shown in Fig. 10.6 d. This method, like defect etching (Fig. 10.4f), is only sensitive to precipitated metals. Metals that stay in solution, like iron, do not show up in defect mapping and have to be determined by other methods, for example diffusion length mapping. 

By combining this technique with capacitive coupling or ultrasound reflection, wafer thickness and wafer flatness information is also obtained. A further step is to wafer-map the data. Using optical scanning, surface defect maps are generated (2.) and insulator thickness variations are measured ellipsometrically and displayed. As discussed further on, recombination lifetime maps can also be generated by non-contacting methods. 

Pixels in each defect category are shown on the corresponding defect map with the color indicated here. 

Cathodoluminescence, CL, involves emission in the UV and visible region and as such is not element specific, since the valence/conduction band electrons are involved in the process. It is therefore sensitive to electronic structure effects and is sensitive to defects, dopants, etc., in electronic materials. Its major use is to map out such regions spatially, using a photomultiplier to detect all emitted light without... 

Uniformity characterization of luminescent materials (e.g., mapping of defects and measurement of their densities, and impurity segregation studies)... 

Element mapping with non-resonant laser- SNM S can be used to investigate the structure of electronic devices and to locate defects and microcontaminants [3.114]. Typical SNMS maps for a GaAs test pattern are shown in Fig. 3.43. In the subscript of each map the maximum number of counts obtained in one pixel is given. The images were acquired by use of a 25-keV Ga" liquid metal ion source with a spot size of approximately 150-200 nm. For the given images only 1.5 % of a monolayer was consumed -"static SNMS". 

EDMD is another X-linked muscular dystrophy, clinically and genetically completely distinct from DMD and BMD. Affected boys usually have onset in childhood of contractures (especially involving the Achilles tendons, elbows, and spinal muscles), humeroperoneal muscle weakness, and cardiac conduction defects, which tend to be mostly a problem in adult life and may necessitate insertion of a pacemaker. The gene for EDMD is known to map to Xq28, but this localization is... 

Short-chain acyl-CoA dehydrogenase (SCAD) deficiency has been recorded in only a few patients and these show wide variation in clinical presentation. The defect has been seen in infants with a syndrome of psychomotor retardation and failure to thrive. These infants showed abnormal organic aciduria, and drastically decreased SCAD activity was demonstrable in cultured fibroblasts. Muscle symptoms were only part of a wider syndrome in all infants and children so far reported to have SCAD deficiency, but were the sole presenting feature in two adult patients, in whom lipid storage was demonstrable in skeletal muscle. The gene encoding for human SCAD has been mapped to chromosome 12. 

Fig. 2 Mechanically oriented bilayer samples as a membrane model for ssNMR. (a) Illustration of the hydrated lipid bilayers with MAPs embedded, the glass supports, and the insulating wrapping, (b) A real sample consists of 15 stacked glass slides, (c) Schematic solid-state 19F-NMR lineshapes from an oriented CF3-labelled peptide (red), and the corresponding powder lineshape from a non-oriented sample (grey), (d) Illustration of typical orientational defects in real samples - the sources of powder contribution in the spectra...

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