Subsurface microscopy of integrated circuits with angular spectrum and polarization control

Abstract

We investigate the effect of an annular pupil-plane aperture in confocal imaging while using an NA increasing lens. We show that focal spot shape is highly sensitive to both polarization and angular spectrum of the incoming light. We demonstrate a lateral spatial resolution of 145 nm (lambda(0)/9) in the direction perpendicular to the polarization direction.

Evanescent waves in high numerical aperture aplanatic solid immersion microscopy: Effects of forbidden light on subsurface imaging

“…Furthermore, the developed electromagnetic model is intended to solve the light propagation from object space to the detector. The stray light originating from the reflections from lens surfaces or chip package are not considered in the image formation process in accordance with the previous studies [3][4][5][6][7][14][15][16].…”

“…The derivation steps between Eqs. (4) and (5) are skipped for the sake of brevity; and these details can be found in Ref [16]. In Eqs.…”

“…In Eqs. (5) and (6), det k is the wave number in the detector space. f det is the focal length of the tube lens (f det >>f obj ), n det is the refractive index of the detector medium, r det = (x det , y det , z det ) is the location on the detector plane.…”

“…The growing demand for high spatial resolution in optical inspection for failure analysis of semiconductor integrated circuits (ICs) has aroused interest in employing aplanatic solid immersions lenses (aSILs) [1][2][3][4][5][6][7]. In such applications, aSILs are placed in intimate mechanical contact with the polished back-side of an IC chip, hence transforming the silicon substrate into a high refractive index immersion medium (n Si = ~3.5) for high numerical aperture (NA) sub-surface imaging.…”

Complete modeling of subsurface microscopy system based on aplanatic solid immersion lens

“…The solid immersion lens (SIL), invented by Mansfield and Kino in 1990 [1], has been widely used both in scientific research and industrial application, for example, optical storage [2][3][4][5], photolithography [6][7][8], and microscopy [9][10][11][12][13][14][15][16][17][18]. Due to the higher numerical aperture (NA) of a SIL, the SIL microscopy system provides not only higher spatial resolution and improved light collection efficiency, but also the capability of subsurface imaging with good resolution if the refractive index of the substrate is the same as that of the SIL.…”