Abstract Aplanatic solid immersion lens (SIL) microscopy is required to achieve the highest possible resolution for next generation silicon IC backside inspection and failure analysis. However, aplanatic SILs are susceptible to spherical aberration introduced by substrate thickness mismatch. We have developed a wavefront precompensation technique using a MEMS deformable mirror and demonstrated an increase in substrate thickness tolerance in aplanatic SIL imaging. Good agreement between theory and experiment is achieved and spot intensity increases by at least a factor of two to three are demonstrated for thicknesses deviating several percent from ideal. This technique is also capable of fixing aberrations due to SIL fabrication, off-axis imaging and refractive index mismatch.

Abstract This paper demonstrates a differential dual-phase interferometric imaging method in which the reflected probe beam modulated weakly by the charge carriers is mixed separately with two reference beams with a known phase shift in between. Performing a balanced detection scheme on these two channels, the common-mode-noise associated with strong DC background and its noise can be significantly reduced. The performance of the interferometric technique is systematically compared with the conventional mapping method through investigating inverter chains on two test chips of 180nm bulk silicon technology and 32nm SOI technology. The future work will focus on adapting the method for GHz frequency regime and time-domain implementation of the method. The method will find applications in failure analysis and testing of advanced technology IC chips for which the high sensitivity in modulation mapping is required.

Abstract We present a method for correcting spherical aberrations in solid immersion microscopy through the use of a deformable mirror. Aberrations in solid immersion imaging for failure analysis can be induced through off-axis imaging, errors in lens fabrication or mismatch of design and substrate wafer thickness. RMS wavefront error correction of 30% is demonstrated in the case of substrate wafer thickness error.

Abstract We investigate a complementary objective lens design for correcting chromatic aberration in the use of a silicon aplanatic solid immersion lens for back-side photon emission microscopy of metal-oxide-semiconductor circuits. Our simulations demonstrate that the chromatic aberration due to material dispersion of aplanatic silicon solid immersion lenses can be reduced by more than an order of magnitude in the spectral window 1.5µm-2.1µm, providing new diffraction limited performance. On-axis and off-axis imaging performance of the proposed optical design is evaluated.