Diffractive Lenses for High Resolution Laser Based Failure Analysis

Zachariasse, Frank; Goossens, M.J.

doi:10.31399/asm.cp.istfa2005p0001

Cited by 5 publications

(3 citation statements)

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“…Critically, the method must be capable of reliably making sub-wavelength structural geometries with etch depths of 440 nm in silicon. To satisfy these criteria, this work will use the focused ion beam (FIB) to implant gallium atoms in silicon to form a mask pattern with subsequent reactive ion etching using CHF 3 chemistry [4].…”

Section: Fabricationmentioning

confidence: 99%

“…The use of refraction or diffraction solid immersion lenses (SIL) is an established optical technique to enhance the resolution of microscope images [1][2][3]. This technique has found recent use with near infrared scanning laser microscopy of integrated circuits through the silicon substrate [4] where the use of a hemispherical refraction lens (hSIL) or a planar diffraction lens (dSIL) on the substrate surface has been reported to increase the resolution of backside images. The hSIL has the advantage of being free to move and provide a practical method for achieving high-quality images; however, the design of refraction lens is limited by the difficulty to change their structure to do anything more complicated than focus light.…”

Section: Introductionmentioning

confidence: 99%

“…The reported use of diffraction lenses primarily consists of a binary-phase structure that achieves a maximum theoretical diffraction efficiency of 40.5% [5,6]. It can be fabricated with a number of established nano-lithographic techniques, such as the use of an ion or electron beam to write a mask pattern followed by reactive ion etching to transfer it into the substrate [4,7]. These diffraction lenses provide a working method to achieve SIL images using a structure that is more amenable to changes in its design and, therefore, offers a wavefront reconstruction capability that has the potential to enhance laser imaging and analysis techniques.…”

Section: Introductionmentioning

confidence: 99%

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A working method for prototyping solid immersion blazed-phase diffractive optics for near-infrared laser microscopy

Coyne¹,

Zachariasse²

2008

J. Micromech. Microeng.

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This paper reports on the design, fabrication and evaluation of solid immersion blazed-phase diffractive optics for near-infrared radiation of wavelength 1064 nm. The practical application of enhancing the analysis of integrated circuits using scanning laser microscopy through the silicon substrate is demonstrated. A general design technique using computer generated holography (CGH) is developed to create a numerical program that calculates the structure required for spherical wavefront reconstruction through a silicon substrate into any user-defined pattern. Fabrication of the blazed-phase structure with a diffraction efficiency of 87.9% is achieved in a single-process step by using a combination of the focused ion beam to implant gallium atoms according to the phase pattern, followed by reactive-ion etching using CHF 3 chemistry. The implant conditions and etch times are experimentally adjusted to achieve a continuous blazed-phase profile with the required height of 440 nm with a minimum implant spacing of 140 nm. The imaging capability of the solid immersion blazed-phase lens is compared to a binary-phase lens with a diffraction efficiency of 38.8%, where the more efficient blazed design results in a corresponding improvement with image contrast. The complete technique is then extended to the reconstruction of multiple focal points and ring patterns, to produce analysis techniques that use phase contrast to produce differential images between each focal point from the same diffractive optic. Analysis results are presented that demonstrate lateral resolutions up to 3.5 times better than without the diffraction optic and the capability of selectively removing of specific spatial frequencies from repetitive integrated circuits.

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Section: Fabricationmentioning

confidence: 99%