DocumentCode :
2069915
Title :
A novel moiré fringe assisted method for nanoprecision alignment in wafer bonding
Author :
Wang, Chenxi ; Suga, Tadatomo
Author_Institution :
Sch. of Eng., Univ. of Tokyo, Tokyo
fYear :
2009
fDate :
26-29 May 2009
Firstpage :
872
Lastpage :
878
Abstract :
High precision alignment is essential to 3D integrated circuit and other multilayer structure fabrication. A novel centrosymmetric square moire grating is developed for aligning between the top and bottom wafers. The mismatched moire fringes produced by the two superimposed centrosymmetric square gratings are highly sensitive with the misalignments and misaligned directions without requiring any external reference. Using two pairs of these square moire gratings, misalignments of the bonded wafers are determined in X-Y-thetas direction simultaneously on wafer scale. In our experiment, the misalignments in the order of plusmn 0.5 mum in X-Y direction can be easily identified using a simple infrared (IR) microscope. Moreover, the measurement of misalignments using the moire fringe distances does not depend on the gap between the two wafers changing from tens of micrometers to zero during alignment process. Therefore, these moire gratings are suitable for being secondary alignment mark to achieve high-precision alignment as well. A moire fringe assisted alignment method is proposed for realization of alignment accuracy in nanometer-scale.
Keywords :
moire fringes; nanotechnology; wafer bonding; 3D integrated circuit; centrosymmetric square moire grating; infrared microscope; moire fringe; nanoprecision alignment; wafer bonding; Fabrication; Geometry; Gratings; Metrology; Microscopy; Nonhomogeneous media; Strain measurement; Three-dimensional integrated circuits; Two dimensional displays; Wafer bonding;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Electronic Components and Technology Conference, 2009. ECTC 2009. 59th
Conference_Location :
San Diego, CA
ISSN :
0569-5503
Print_ISBN :
978-1-4244-4475-5
Electronic_ISBN :
0569-5503
Type :
conf
DOI :
10.1109/ECTC.2009.5074115
Filename :
5074115
Link To Document :
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