Abstract
High resolution patterning on nonplanar substrates with large height variation using electron beam
lithography is reported. Using an automatic, high precision, noncontact laser probe microscope, a
three-dimensional map of the nonplanar substrate to be patterned is obtained first. This data are
converted to a format for the electron beam lithography system, which performs the write by
adjusting the plane of electron beam focus based on the mapping data. As a proof of concept of this
patterning scheme, three different kinds of nonplanar substrates were used including a tilted Si
wafer for a uniform and unidirectional tilt, a planoconvex lens for a multidirectional tilt, and deep
Si trenches with a step height variation. The patterning scheme was tested for resolution, field
stitching accuracy, and field placement accuracy. The results of these tests are in very close
agreement with typical results that are obtained for flat substrates with similar patterning
conditions. For wafers with 10mm tilt, 50 nm gratings show a line width variation of 18%, average
field stitching error of 1.06 nm with a 3r of 24.62 nm, and field placement error of 20.53 nm with a
3r variation of 31.92 nm. The simplicity of this method and the fact that it can be applied for
various nonplanar substrates with nanometer scale precision and over large areas open up a new
avenue for the fabrication of devices based on nonplanar substrates. VC 2012 American Vacuum
Society. [http://dx.doi.org/10.1116/1.4755819]
lithography is reported. Using an automatic, high precision, noncontact laser probe microscope, a
three-dimensional map of the nonplanar substrate to be patterned is obtained first. This data are
converted to a format for the electron beam lithography system, which performs the write by
adjusting the plane of electron beam focus based on the mapping data. As a proof of concept of this
patterning scheme, three different kinds of nonplanar substrates were used including a tilted Si
wafer for a uniform and unidirectional tilt, a planoconvex lens for a multidirectional tilt, and deep
Si trenches with a step height variation. The patterning scheme was tested for resolution, field
stitching accuracy, and field placement accuracy. The results of these tests are in very close
agreement with typical results that are obtained for flat substrates with similar patterning
conditions. For wafers with 10mm tilt, 50 nm gratings show a line width variation of 18%, average
field stitching error of 1.06 nm with a 3r of 24.62 nm, and field placement error of 20.53 nm with a
3r variation of 31.92 nm. The simplicity of this method and the fact that it can be applied for
various nonplanar substrates with nanometer scale precision and over large areas open up a new
avenue for the fabrication of devices based on nonplanar substrates. VC 2012 American Vacuum
Society. [http://dx.doi.org/10.1116/1.4755819]
Vishva Ray1, Yukinori Aida2, Ryo Funakoshi3, Hitoshi Kato2, and Stella W. Pang4
1Lurie Nanofabrication Facility, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109
2JEOL Ltd., 3-1-2 Musashino, Akishima-shi, Tokyo, Japan 196-8558
3JEOL USA, Inc., 11 Dearborn Road, Peabody, Massachusetts 01960
4Lurie Nanofabrication Facility, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 and Department of Electronic Engineering, City University of Hong Kong, Hong Kong
(Published online 4 October 2012)
For full paper please go here. http://avspublications.org/jvstb/resource/1/jvtbd9/v30/i6/p06F303_s1
