Monte Carlo simulation of charging effects on linewidth metrology

Abstract

Summary: Charging effects of scanning electron microscopes on the linewidth metrology of polymethylmethacrylate (PMMA) insulator patterns are investigated using Monte Carlo simulation. It is first revealed in detail how the nonunity yield of electron generation in the PMMA target leads to local charge accumulation and affects the image profile of secondary electrons as charging develops. Then the measurement offset due to charging effects is identified for various target patterns of isolated and array types. Finally, it is concluded that the measurement uncertainty caused by the measurement offset exceeds the error budget limit that will be allowed in the linewidth metrology of the next generation of semiconductors.

The surface potential of insulating thin films negatively charged by a low-energy focused electron beam

“…Here, the surface potential can cause some undesirable effects by affecting motion states of both secondary electrons (SEs) emitted from the insulator surface and primary electrons (PEs) (see, for example, Ko et al, 1998;Zhang et al, 2003;Postek et al, 2004;Cazaux, 2005). On the other side, it can be utilized to image surface and buried structures of insulators in SEM (Ura, 1998;Koike et al, 1999;Zhang et al, 2004;Kokhanchik, 2009).…”

Determination of secondary electron spectra from insulators

“…Recently, the problem of surface charging during lowkV metrology has spurred interest in the simulation of scanning electron microscope (SEM) signal profiles from insulating structures employed in the semiconductor industry (Davidson and Sullivan 1997, Ko et al 1998, Kotera et al 1994, Monahan et al 1991. This need has arisen since quantitative analyses of such SEM images are highly susceptible to errors introduced by surface charging often exhibited in the form of intensity blooming, image distortions, and flicker noise, and so forth.…”

Mask Charging Phenomena during Electron Beam Exposure in the EPL System

“…However, the precise understanding has not been accomplished yet. Recently, some simulations have been developed to explain certain experimental results~Kotera & Suga, 1988;Liu et al, 1995;Ko et al, 1998;Kotera, 1998;Bai et al, 1999;Kotera et al, 1999;Lee et al, 2000;Mkrtchyan, 2000!. The mask charging phenomena in EPL optics have been discussed by several authors~Lee et al, 2000; Mkrtchyan, 2000!.…”