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Accessory for Nanorobotics

not only for vacuum chambers

     


Fig.1: Etched tungsten wire with 50 nm tip size


Fig. 2: Etching stage

Our high resolution Nanorobotics manipulators can be equipped with additional tools, to form complete solutions and to expand their field of application. Each Nanorobotics stage offers a set of different positions, where objects can be fixed. The following items are preferred examples. Other probes like e.g. MEMS sensors are also available within our Microtechnology Network that includes more than 110 partners.

 

Conductive tips:

a) Conductive Cantilevers:

The NMT manipulators can be equipped with electrically conductive cantilevers:


Tip approach with a conductive cantilever

The tip is at the very front end of the cantilever and has a tip radius of less than 100 nm. Diamond coated tips for processing material are available as well.

b) Wire shaped tips:

Fine wire shaped tips can be prepared by etching tungsten or PtIr wires. For wafer probing these wires have the advantage that they can point under a selectable angle towards the sample. The disadvantage is the missing flexible area of the cantilever. A secure approach of these tips also on non conductive sample areas is still possible with our "Nanofinger", a sensor that feels the sample without touching it in a distance of about 10 nm, see below. Fig. 1 shows an etched tungsten tip, Fig. 2 a tip etching stage.

 

Tip approach:

At first the tip is moved fast with the absolute positioning Nanorobotics manipulator into a secure distance above the sample, e.g. 50 microns above. Then the automatic approach process similar to that of an STM can be executed:
The tip is moved within the fine positioning stroke and a the contact signal is measured. When there is no sample the tip is retracted into a secure distance, a coarse step is induced and the process begins again - until the sample is reached.

Different sensors and electronics can be used to detect the contact moment on conductive or isolating samples:

  • Current detection
  • Contact force detection
  • Signal from our Nanofinger

Software modules and electronics compatible to our Network Controller are available to support these approach modes.

 

Nanofinger:

The "Nanofinger" developed by Klocke Nanotechnik is a small MEMS device that detects the distance of a probe tip and a sample. The following graph describes the signal output of this device during a tip approach:


In a distance of about 10 nm the Nanofinger "feels" the sample - without touching it. The shape of the intensity - distance curve in the area between 0 nm (contact) and about 10 nm is independent from the properties of the sample, conductivity is not necessary. When the output signal is compared with a certain selectable level (e.g. 75% amplitude) this level is related to a calibrated distance between Nanofinger and sample (in this example e.g. 5 nm).

This signal can be used for the tip approach on isolating samples, as described above:

  • At the moment the signal of the Nanofinger reaches the desired value (e.g. 75% amplitude) the position of the manipulators vertical stage is stored "as sample height".
  • When a retraction distance is entered the vertical stage immediately drives back to this position. This distance allows to hover above the sample without the danger of an interaction. Still the height of the sample is known, because it was stored as one position of the absolute scale of the vertical stage.
  • Using the position sensors of the manipulator allows to interact with the sample in a scaled volume.
  • When the height of the sample and the shape of the tip is not changed the approach described above can start next time nearer to the sample, because the sample height is known.

The Nanofinger uses a high speed electronics that reacts with a bandwidth of some KHz. To read a height signal needs about 1 ms. The electronics of the Nanofinger is completely compatible to our Network Controller and allows a closed loop operation without burdening the master PC with the feedback.

The Nanofinger includes a tip holder that can carry a thin wire-shaped tip. This tip can be used for wafer probing, TEM lamella handling or to define a position precisely.

 

Nanorobotics Gripper:

The Nanorobotics system includes stages and tools that are compatible in mechanics and electronics. Our Nanorobotics Gripper can also be used in a vacuum chamber, fixed at the end of a manipulator.

 

Vision systems and pattern recognition:

Our Micro Production Systems include video cameras and a Server PC with a vision software for pattern recognition. With this software the position and orientation of an object can be detected and many procedures for quality control are included. The vision PC can read any kind of video signals, e.g. from an Electron Microscope when it offers such a signal. Our complete process control of the Micro Production system can be used for this application, and objects can be taught in the vision system to identify their position in the SEM picture.

An example for the usage of this system is automatic wafer probing: extremely small structures are recognized by the vision system and the manipulator can place its probe tip directly onto that structures.
In the same way high speed handling of TEM lamellas prepared in a FIB is possible with the help of the vision system. More details are descibed at the page "Vision System".

Summary:
Accessory for our Nanorobotics manipulators to form complete systems for Electron or Ion Microscopes.
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