Manufacture of High Aspect Ratio Carbon Nanotube Atomic Force Microscopy Probes Y.N. Emirov 1, J.D. Schumacher 1, M. M. Beerbom 1, B. Lagel 1 B.B. Rossie 2, and R. Schlaf 1* 1)University of South Florida, Dept. of Electrical Engineering 2)USF Center for Ocean Technology *)

Need: Atomic Force Microscopy Nanotube Cantilevers For High Aspect Ratio Feature Critical Dimension Metrology Image features incorrectImage features correct

Carbon Nanotube Growth by PE-CVD Plasma Enhanced Chemical Vapor Deposition (PECVD) Precursors: Methane, acetylene, propane Catalysts needed: Ni, Fe, Co (allows directed assembly) DC Plasma helps cracking the precursor molecules

Directed Assembly of CNT Through Catalyst Patterning

Focused Ion Beam Patterning of Catalyst Focused Ga-ion beam sputters sample Computer controlled, complicated patterns are possible 5 nm resolution Dual beam instrument with integrated SEM

Process: Masking Layers with Sockets Cr masking layers prevent CNT growth in unwanted locations (i.e. on tip cone) Access to buried catalyst through cylindrical cavity extending into the catalyst. Result: Good control over Ni patch

CNT Growth From Si-Ox Sockets Sockets in 130 nm Si-Ox layers 10nm/30nm Cr/Ni at bottom of sockets CNT with well defined diameter grow from each socket, ~25% are straight.

64 nm Tubes From 130 nm Sockets Smaller CNT diameters possible However, yield appears to depend on diameter

Recent CNT Cantilevers 70 nm x 400 nm CNT Grown from cavity Cold cathode PECVD Acetylene/Ammonia precursors Grown at 10 deg angle suitable for Nanoscope

CNT Probe Test on Mikromasch TGZ02 Standard TGZ02: 100 nm high steps CNT probe shows better defined height image Sharper edges Standard Si Probe CNT probe

CNT vs. Standard Si Probe Comparison Traces across Mikromasch test sample FWHM of lines much smaller with CNT probe Much steeper side wall curves

Forward/Backward Scan Comparison CNT probe shows much smaller difference between opposite direction scans than standard Si probe

CNT Probe Before and After Scanning No apparent damage to CNT from scanning process CNT attached strongly enough to withstand torques during scanning Socket provides stability

Latest Results: New, stable process CNT are well-defined Testing of these probes is underway Patent pending Dimensions: 1µm long/50 nm wide

Summary Goal: Well-defined CNT on standard AFM tips suitable for critical dimension metrology Concept has been demonstrated Focused ion beam/e-beam litho patterning used for prototyping Outlook: Testing on state-of-the-art industry structures/expansion of process to wafer scale Thank you for your kind attention! Contact: