Traditional insight of effective probe of scanning electron microscope (SEM) is considered. A contradiction of this insight with experimental results registered at scanning of test objects with the trapezoidal profile and large slope angles by SEM probe is detected. A new insight of effective probe based on analyzes of the experimental results registered by SEM working in a back scattered electron (BSE) mode is proposed.
Semi empirical model of image formation is proposed for scanning electron microscope (SEM) working in low and high voltage modes with registration of back scattered (BSE) and slow secondary (SSE) electrons. The model is based on analysis of experiments executed with a test object with trapezoidal profile and with large slope angles scanned in a SEM. The model is designated for application in virtual SEM.
A scan of trapezoidal protrusions by an electron beam was carried out in a SEM during an hour. This allows detecting some laws of a profile change due to contamination. The detection is based on analysis of distorted protrusion images obtained by the SEM. The greatest distortion of protrusion images was discovered around a scanned area. This distortion is not uniformed in the area (and associated with a non-uniform profile change in that area) that leads to a pitch change of a periodic structure. The protrusion image change in the scanned area is minimal, contrary to perceptible structure profile changes in that area. The latest circumstance allows defining geometrical parameters of a protrusion using a model developed for measurement of these parameters for a non-distorted structure. It was discovered that contamination process of periodic linear structures beyond the scanned area differs from the corresponding process for a flat surface. The difference firstly is due to dissimilar contribution of a volume and surface diffusion of hydrocarbon particles (HCP) that induce the contamination into various structure areas. Secondly it is due to different diffusion velocity of surface HCPs that are moving along and across of stripes with trapezoidal profile and over surfaces with different crystallographic indexes.
Application of virtual instruments to a process of measurements of geometrical characteristics of investigated objects is considered. Methods of construction of virtual instruments on a base of imitators and simulators are discussed. It is demonstrated, that a virtual scanning electron microscope (SEM) can be constructed only on the base of simulator. Examples of work of the virtual SEM in a low-voltage mode and in modes of registration of back scattered electrons (BSE) and slow secondary of electrons (SSE) are given.
An unusual phenomenon of non-monotone change of phosphosilicate glass network, including its structural elements (i.e. inter-atomic bonds, phosphorous and siliceous point defects, ring structures of SiO<sub>4</sub> tetrahedra) under laser irradiation at 193 nm is discovered. The phenomenon is explained by applying
conceptions of the rigidity percolation theory, which describes connectivity of atoms in network, for the phosphosilicate glass under UV-exposure. Presence of phosphorous atoms in silica glass decreases the rigidity of the network in comparison with silica. Generation of point defects in the phosphosilicate network due to the two-photon light absorption decreases of the rigidity in addition and finally leads to achievement of the network rigidity threshold. This results in a transformation of the network from the rigid to a floppy mode where switches of bonds between atoms are possible. But later under exposure the network switches back into the rigid mode and the cycle of rigidity change can be repeated several times. This quasi-periodical transformation of phosphosilicate glass network leads to the corresponding change of inter-atomic bonds, point defects concentration and reconstruction of ring structures during an exposure. The presence off the network in the floppy mode affords one to explain a change off phosphosilicate glass density and induced index in a new manner.