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Caltech

Self-sensing, self-actuating NEMS SPM cantilever at 1 to 5 MHz for parallel, low cost, high speed imaging and lithography.

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Figure 1. Caltech 1 MHz piezoresistive self-sensing SPM cantilever with tip

Scanning probe microscopy (SPM) is very popular:

  • Biologists use atomic force microscopy (AFM) to image cells and proteins.
  • Material scientists use magnetic force microscopy (MFM) to map moments of nano-magnets.
  • Nano-technologists use dip-pen and tip-enhanced-oxidation lithography to pattern features below 10 nm.

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Figure 2. AFM image by commercial system (left) and by Caltech piezoresistive probe

Commercial SPM has excellent imaging quality but limited speed and throughput

  • Only one cantilever is operated at a time. It is too expensive in commercial systems to allow two sets of piezo actuator and laser-photodiode sensor. They are also too bulky to let two levers to work in close proximity.
  • Newer system could go up to 7 MHz (actual imaging bandwidth is ~ 1/10th). However, there is not yet commercial lever at over 2 MHz. In addition, most people are still operating below bandwidth of 100 kHz.

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Figure 3. 100mm-wafer scale production of Caltech AFM probe

Caltech NEMS SPM offers high speed and parallel operation

  • Parallel operation through cantilever self actuation and sensing
    • Self actuation by on chip thermal and piezoelectric drive.
    • Self sensing by integrated piezo-resistive sensor.
    • Such lever requires only electrical drive and sensing and is cost effective to operate in large array of 1000 or more.
  • High frequency NEMS cantilever
    • NEMS lever (~ 5 mm ' 300 nm ' 100 nm) has high frequency (1 to 5 MHz) and moderate force constant (100 N/m)

Applications

  • Video-frame rate imaging for "fast-shutter" imaging.
  • Massive parallel tip-based patterning for semiconductor lithography and photomask repair.

Personnel
Warren Fon, Derrick Chi and Michael Roukes

References

  1. Mo Li1, H. X. Tang & M. L. Roukes. Ultra-sensitive NEMS-based cantilevers for sensing, scanned probe and very high-frequency applications. Nature Nanotechnology 2, 114 - 120 (2006)
  2. J L Arlett, J r Maloney, B Gudlewski, M Muluneh, & M L Roukes. Self-sensing Micro- and Nanocantilevers with Attonewton-scale Force Resolution. Nano Letters 2006, Vol 6, No. 5, 1000 1006.


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