Moire patterns of skewed radial gratings

Sandler, Ben-Zion; Keren, Eliezer; Livnat, Aminadav; Kafri, Oded

doi:10.1364/ao.26.000772

Cited by 14 publications

(4 citation statements)

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“…In the past years the moire´fringes formed by overlapping simple structures such as line, radial, and circular gratings have been widely examined [4][5][6][7][8]. Also, complicated types of gratings such as Fresnel zones, skewed radial lines, spiral lines, matched radial-parallel lines and elongated circles have been studied for specific applications in moire´metrology [9][10][11][12][13][14]. If any two gratings are superimposed onto each other, optical moire´s readily appear even under the illumination of a white light source.…”

Section: Introductionmentioning

confidence: 99%

A moiré method of visualizing electromagnetic force lines

Yuk

Lee

2008

Optik

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Section: Introductionmentioning

confidence: 99%

A moiré method of visualizing electromagnetic force lines

Yuk

Lee

2008

Optik

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“…10) Therefore, by fabricating the sets of moire ´gratings on two silicon wafers prior to bonding, the moire ´fringes of bonded wafers could also be observed by an IR microscope. Several types of moire ´fringes superposed by two radial gratings, skewed-radial gratings, 11) Fresnel zone plates, 12) and elongated circular gratings 13) are known for the metrology of planar displacements. However, the moire fringes superposed by these gratings are still difficult to be used to identify obvious differences between perfectly aligned and very small misaligned moire ´fringes within sub-pitch misalignments by an observer's eyes without any external reference.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Alignment Accuracy for Wafer Bonding by Moiré Method

Wang

Suga

2007

jjap

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A centrosymmetric square grating was developed in this paper. Moire ´fringes produced by the two centrosymmetric square gratings are highly sensitive with the misalignments and misaligned directions. The distance between the mismatched moire fringes are expected to be measured directly by an infrared (IR) microscope without requiring any external reference. Using two pair of the moire ´square gratings, misalignments of bonded wafers are proposed to be measured in the X-Y-axis simultaneously on wafer scale. The measurement accuracy of 0.5 mm in the X-Y axis and 3 Â 10 À4 deg in the -axis is presented as an example, which is sufficient for the alignment accuracy of currently available wafer bonding. Moreover, the measurement accuracy by this moire ´method can be improved to nanometer level if the fabrication errors and IR microscope resolution are allowed.

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“…Therefore, moiré fringes could be also observed by using IR transmission images when patterns on upper and lower wafers are overlapped. Several types of moiré patterns superimposed by two radial gratings, skewed-radial gratings [4], Fresnel zone plates [5], as well as elongated circular gratings were also investigated to measure planar displacements [6]. However, misalignments of θ axis, i.e.…”

Section: Introductionmentioning

confidence: 99%