Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
1999-03-17
2001-06-19
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C073S105000, C369S126000
Reexamination Certificate
active
06249747
ABSTRACT:
TECHNICAL FIELD
The invention relates to an investigation and/or manipulation device for a sample, wherein the sample consists of a material that is locally deformed when subjected to a local heat treatment. More particularly, the invention relates to a data storage system with a fast reading and writing scheme based on atomic-force microscope (AFM) techniques. A further essential aspect of the invention has to be seen in the provision of an improved sensor which is able to detect the displacement of a movable object relative to an immovable object.
BACKGROUND OF THE INVENTION
A conventional investigation device for a sample is e.g. disclosed in U.S. Pat. No. 5,345,815. In particular, this known investigation device relates to an atomic-force microscope (AFM) which comprises a cantilever, the movement of which is picked up by means of a piezoresistive deflection sensor.
An AFM is known as an instrument in which a flexible cantilever of very small dimensions is moved relatively to a surface so as to investigate or to scan the structure of this surface. Such cantilevers typically have a sharp tip at the free (distal) end thereof. The apex of the tip projects in the direction of the sample surface. As the sample is scanned, forces (including electrostatic, magnetic, viscous, van-der-Waals and other forces) between the cantilever tip and the sample surface cause the cantilever to deflect. The deflection is measured by the integrated sensor (as e.g. the piezoresistive deflection sensor disclosed in U.S. Pat. No. 5,345,815); the output signal of this sensor is representative of the respective profile or structure of the sample and, typically, has an extraordinary resolution in the order of nanometers.
A similar type of AFM which makes use of integrated piezoresistive sensors is disclosed in the PCT Patent Application No. WO 94/298994; furtheron, an AFM device which measures the deflection of the micro-cantilever by means of an optical sensor instead of piezoresistive elements is disclosed in U.S. Pat. No. 5,388,323.
However, these known AFM devices are only capable of investigating or scanning the surface of a sample; these known AFM devices are, however, not capable of manipulating the surface. The presently known AFM devices, consequently, cannot be used for writing information onto the surface of a storage medium. On the other hand, it would be highly desirable to provide a device which both has the ability to investigate and to manipulate a sample, for example in order to provide a read/write operation for coded information on the sample.
Since an AFM is able to investigate a sample with a resolution in the order of nanometers, such an AFM device is able to read the information stored on a very small area; hence, an AFM device, in principle, has the ability to read huge amounts of information which are stored at a very high recording density. However, the investigation techniques used in these known AFM devices are not fast enough so as to be used for a read operation having a sufficiently high data transfer speed (throughput). Moreover, the power consumption of the sensor of these known devices is rather high; therefore, any attempt to speed up the data transfer rate by using a plurality of AFM tips simultaneously is drastically limited by the increasing power consumption which finally would lead to an overheating of the device.
OBJECT OF THE INVENTION
Accordingly, it is the object of the present invention to provide an investigation and/or manipulation device which is able to investigate and/or to manipulate a sample at a very high speed and with a very low power consumption.
Another aspect of the present invention is to provide a data storage system that advantageously uses this investigation and/or manipulation device in order to significantly increase the recording density as compared to conventional data storage systems.
Still another aspect of the present invention is the provision of a new and improved sensor for detecting the displacement of a movable object relative to an immovable object which has a very high detection speed and a low power consumption.
SUMMARY OF THE INVENTION
The core concept underlying the investigation and/or manipulation device of the present invention as claimed in claim
1
is the provision of a heated tool which is made in such a way that the supplied power is heating substantially only the tool, and not the complete structure of tool and the support means (cantilever). This exclusive heating of the tool can easily be reached if the tool and the cantilever are formed with an appropriate structure or if these parts are made of appropriate materials; thus, as claimed in claim
3
, this exclusive heating of the tool can e.g. be reached if at least that one region of the cantilever which is in the neighbourhood of the tool is made of a material which has a lower heat conductivity than the material of the tool; alternatively, as claimed in claim
9
, it is possible to provide a cantilever which is made of two arms, these two arms being spaced from each other and being made of electrically conductive material, each arm, at the outer end thereof, being connected to the tool so as to supply electric power in order to heat same. The latter-mentioned solution has the additional advantage that any bimorphous effects that could deform the cantilever can be avoided; furthermore, the overall mass of the moved parts of the device is further reduced, thereby further increasing the operating speed.
As, according to the afore-mentioned basic principle of the present invention, the investigation and manipulation process is performed by a heated tool which is isolated with respect to the support means (preferably in the form of a cantilever) and, thus, the only part of the device to be heated, the power consumption of the device, due to the small mass of the tool as compared to the mass of the cantilever, is extremly low. Consequently, the heating and cooling of the tool can be performed at very short cycles so that the work speed of the device is very high; the investigation and/or manipulation of a sample, thus, can be perfomed at an extraordinary high speed. Experiments have e.g. shown that operation frequencies of up to 1 MHz or even more can be realized without any problems.
Of course, if the device of the present invention is operating in the manipulation mode, the respectivly manipulated sample—due to the afore-mentioned operation principle of the tool—should consist of a material which is locally deformed when subjected to a local heat treatment. For this operation mode, the device of the present invention, moreover, comprises a manipulation means which is adapted to supply a high amount of power to the tool, this high amount of power heating the tool to a temperature which is sufficient to deform the sample surface region which is presently effected by the tool.
One further major advantage of the present invention has to be seen in the fact that the heated tool not only can be used for manipulation purposes but also for sensing the structure of the sample: Experiments made by the inventors have revealed that it is possible to detect or investigate the structure of the respective sample by heating the tool to a predetermined temperature (which, of course, must be unsufficient to deform the sample) and by subsequently measuring a variation in the temperature of the tool; it in fact could be shown that the cooling rate of the tool is influenced by the structure of the sample to such an extent that the corresponding change of the temperature of the tool can be easily measured (e.g. by measuring the corresponding change or variation of the power supplied to the tool, see claim
12
). Therefore, the heated tool can also be used as a sensor for investigating the structure of the sample.
Thus, if the device of the present invention is operating in the investigation mode, there is provided a sensing means which is adapted to supply a low amount of power to the tool, this low amount of power being selected such that it is insufficient to locally deform the sample
Binnig Gerd K.
Brugger Jurgen
Haeberle Walter
Vettiger Peter
Drumheller Ronald L.
International Business Machines - Corporation
Shah Kamini
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