1. Shadow Nanosphere Lithography Peter J. Shin Department of Bioengineering

2. UC Berkeley The BioPOETS Introduction Interested in Batch Fabrication technique for making biosensors (i.e. SERS substrate) Wanted features include - low cost manufacturing - regular patterns in large area (6” Si wafer) - very high uniformity A. Kosiorek, et al., Shadow Nanosphere Lithography: Simulation and Experiment, Nano Lett., 2004

3. UC Berkeley The BioPOETS Nanosphere Lithography (NSL) Metal (Au, Ag) Deposition Array of Polystyrene Beads as Mask Si Substrate Metal deposit with electron beam evaporation (EBE) system Control over shape & size of patterns by varying bead radius

4. UC Berkeley The BioPOETS Nanosphere Lithography (NSL) Top ViewSide View 1. Bead Coating (self-assembled monolayers) 2. Deposit Metal 3. Bead Removal (toluene, tape)

5. UC Berkeley The BioPOETS Nanosphere Lithography (NSL) Targeted Pattern scanning electron microscopy (SEM) image resulting from fabrication process (image from Van Duyne’s group)

6. UC Berkeley The BioPOETS Shadow Nanosphere Lithography * Modified EBE System –Sample –Metal source 5. e-beam source Θ : angle between sample & metal source α : angle of sample rotation

7. UC Berkeley The BioPOETS Shadow Nanosphere Lithography Metal (Au, Ag) Deposition Θ α Varying α resulting in nanowire Sample Rotation Varying Θ resulting in complex morphology

8. UC Berkeley The BioPOETS Shadow Nanosphere Lithography Θ = 0° & α = 0° leads to conventional NSL 150nm Cr with Θ = 25° + 15nm Ni with Θ = 0° Conventional NSLShadow NSLvs

9. UC Berkeley The BioPOETS Thank you! Questions?