(Color online) Illustration of the synthesis of arbitrary Manhattan structures from gratings. After the grating teeth are patterned, they are cut at specific locations and then connected together by stitches to form designed pattern.
(Color online) (a) Gratings etched into thermal oxide. The pattern was generated via interference lithography. Roughness is noticeable; (b) KOH etched Si gratings with highly smooth sidewalls.
(Color online) (a) Gratings in thick HSQ at pitch. Roughness is clearly visible; (b) KOH etched Si with highly smooth sidewalls.
(Color online) (a) Schematic of the cutting process. A thick photoresist for e-beam lithography, such as ZEP 520A, is spun over the grating and exposed by EBL at designed locations. Grating teeth not protected by the ZEP 520A will be etched away by reactive-ion etch. Finally the resist is removed by oxygen plasma. (b) An orthogonal cut in pitch grating formed by interference lithography and orientation-dependent etch. The grating pattern remained in the trench. However, it will not be duplicated in nanoimprint lithography if the cut is sufficiently deep. (c) Cutting gratings at pitch. Grating line width is approaching . (d) Aligned cuts in pitch grating.
(Color online) (a) Schematic of the stitching process. A negative e-beam resist, e.g. HSQ, is spun over the grating with cuts. The exposed HSQ forms the desired stitches. (b) Stitches formed in gratings generated by IL at pitch; (c) Aligned stitches in grating of pitch.
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