DE102008020982B4 - Sample positioning device and scanning probe microscope with the sample positioning device - Google Patents

Abstract

Probenpositioniervorrichtung, in particular for a scanning probe microscope, with
(a) a sample table (12),
(b) a first sample table drive (14) mechanically coupled to the sample table (12) for moving the sample table (12) in a first direction (x),
(c) a second sample table drive (16) mechanically coupled to the sample table (12) for moving the sample table (12) in a second direction (y) different from the first direction (x),
(D) wherein the first sample table drive (14) comprises a first plunger coil assembly, and
(e) the second sample table drive (16) having a second immersion coil arrangement,
characterized in that
(f) the first sample table drive (14) comprises a first loudspeaker (18) comprising a first loudspeaker cup (62), a first loudspeaker magnet (20) and a first plunger coil assembly, the first loudspeaker magnet (20) being part of the first plunger coil assembly, and that the second stage table drive (16) comprises a second loudspeaker (22) comprising a second loudspeaker cup (26), a second loudspeaker magnet (24) and a second plunger coil assembly, the second loudspeaker magnet (24) being part of the second plunger coil assembly.

Description

The invention relates to a Probenpositioniervorrichtung according to the preamble of claim 1 and a kit for an atomic force microscope with such a sample positioning.

Such Probenpositioniervorrichtungen be used for example in atomic force microscopes. Atomic force microscopes serve to scan the surface of a sample. For this purpose, a cantilever is moved in an x-y plane and deflected from the surface of the sample in a z-direction. The deflection is detected by a measuring head and the data thus obtained are processed electronically, for example by a computer.

The movement in the x-direction and y-direction requires a high positioning accuracy of less than 10 nm and is therefore performed by piezo actuators. Piezo actuators have the advantage of allowing a very high positioning accuracy. A disadvantage of known atomic force microscopes is their high price.

From the US 6,005,251 A For example, a sample positioning device for use in a scanning probe microscope is known. The known sample positioning device uses plunger coils to move the sample table. The known Probenpositioniervorrichtung is very compact, but disadvantageous is the high cost in the production.

From the EP 0 807 799 A1 For example, an atomic force microscope is known in which the probe is moved over plunger coils. A disadvantage of this scanning probe microscope is that it is less robust and has a complex structure, so that it is not suitable for use in schools, for example.

From the US Pat. No. 6,836,033 B2 is known an XY table, which is moved over plunger coils. A disadvantage of this device is its complex structure, which leads to increased manufacturing costs and low robustness.

From the US 6,789,486 B2 a sample table is known in which a sample holder is mounted by means of two mutually orthogonal leaf springs. From the US 2008/0 030 851 A1 a displacement device for a microscope system is known, in which the sample table is also mounted by means of leaf springs.

The invention has for its object to provide a low-cost scanning probe microscope, in particular a low-cost atomic force microscope, so that, for example, schools access to atomic force microscope technology can be obtained.

The invention solves the problem by a sample positioning device according to claim 1 and a kit according to claim 9.

The sample positioning device is preferably used in a scanning sample microscope, in particular an atomic force microscope.

An advantage of the scanning probe microscope according to the invention is that sample stage drives based on immersion coils are particularly inexpensive to produce. For example, a speaker can be used in the sample table drive. Such speakers are mass-produced and readily available. It has surprisingly been found that even with cheap immersion coils, the high demands on the positioning accuracy can be met.

It is a further advantage of the ratchet probe microscope according to the invention that a high-voltage source for a piezoelectric actuator is dispensable. Thus, the scanning probe microscope can be used, for example, for educational purposes, without elaborate security measures must be provided.

In a preferred embodiment, the sample table comprises a bottom plate, a punch connected to the bottom plate, and a top-mounted head for receiving a sample to be measured, and a spring structure connected to the punch and bottom plate. The advantage hereof is that the spring structure has a damping effect on any fluctuations in the sample table drives.

In a preferred embodiment, the spring structure comprises a first spring element, an intermediate bottom and a second spring element, wherein the first spring element are fixed to the bottom plate and the intermediate bottom and the second spring element to the intermediate bottom and the head. The advantage of this is that the first spring element and the second spring element can be anisotropic with respect to their spring constants, which improves the damping properties.

Particularly preferably, the first direction and the second direction are perpendicular to each other, wherein the first spring element is a first leaf spring, which is perpendicular to the first direction, and wherein the second spring element is a second leaf spring, which is perpendicular to the second direction. Thus vibrations of the sample table are suppressed particularly effectively.

A backlash-free and torque-free coupling between the sample table and the plunger coils is obtained when the first plunger coil over a first coupling rod is connected to the punch and the second plunger coil is connected via a second coupling rod with the punch, wherein both coupling rods are connected by means of magnetic bearing points in each case with the respective plunger coil on the one hand and the punch on the other.

According to the invention, the first plunger coil is part of a first loudspeaker comprising a first loudspeaker dome, and the second plunger coil is part of a second loudspeaker comprising a second loudspeaker dome. In this case, the first coupling rod is preferably connected via a first magnetic bearing point with the first speaker calotte and the second coupling rod is preferably connected via a second magnetic bearing point with the second speaker calotte. The loudspeakers are, for example, commercially available built-in loudspeakers which transmit a continuous and vibration-free movement via the coupling rods to the spring elements. Magnetic bearing points are also mounted on the calottes of the speakers.

Particularly good damping properties are obtained when the first spring element and / or the second spring element consists of fiber-reinforced plastic, in particular of carbon fiber reinforced plastic. In this way, vibrations are suppressed particularly effectively.

A kit is a spatial arrangement of objects which, when assembled, result in a sample positioning device according to the invention or a scanning probe microscope according to the invention, in particular an atomic force microscope according to the invention.

As described above, the first and second stage table drives are preferably speakers. The kit also preferably has a first coupling rod, a second coupling rod, a first leaf spring and a second leaf spring, these elements being constructed as described above.

In addition, the kit may include a base plate, for example made of aluminum. This base plate may have a thickness of 5 to 25 mm and be connected on two sides to respective plates which are adapted to receive the loudspeakers. It is also advantageous if the kit has an electrical drive unit, which is designed to drive the first speaker and the second speaker and has an interface, such as a serial interface or a USB interface to a computer.

The invention also relates to a scanning probe microscope, in particular an atomic force microscope with a sample positioning device described above.

In the following the invention will be explained in more detail with reference to an exemplary embodiment. It shows

1 a perspective view of a sample positioning device according to the invention for a scanning probe microscope according to the invention,

2 a second perspective view of the sample positioning after 1 and

3 a third perspective view of the sample positioning.

1 shows a sample positioning device 10 holding a sample table 12 , a first sample table drive 14 and a second stage table drive 16 includes. The first sample table drive 14 includes a first speaker 18 with a first speaker magnet 20 and one in 1 not shown first calotte (reference numeral 62 . 3 ), which can also be referred to as the first speaker diaphragm. The dome can be made of thin metal, so it can also be called a metal membrane. The loudspeaker magnet 20 is part of a first plunger coil assembly, which also includes a first plunger coil. The first plunger coil is not shown in the figures. The dome is used in the original operation of the speaker as such for emitting sound and is for example a cardboard or plastic membrane.

The second sample table drive 16 includes a second speaker 22 with a second speaker magnet 24 and a second dome 26 , which can also be referred to as a second speaker diaphragm. The loudspeaker magnet 20 is part of a second plunger coil assembly, which also includes a second plunger coil. The second plunger coil is not shown in the figures.

The first speaker 18 is at a first plate 28 and the second speaker 22 is on a second plate 30 attached, in turn, each with a base plate 32 connected and arranged at right angles to each other and to the base plate.

On the base plate 32 is a floor plate 34 of the sample table 12 attached. The bottom plate 34 is about a first spring element 36 with an intermediate floor 38 connected. The first spring element 36 includes two leaf springs 40.1 . 40.2 of carbon fiber reinforced plastic having a thickness of less than 500 microns, in the present case, namely 300 microns, and are arranged parallel to each other.

The intermediate floor 38 is about a second spring element 42 with a head 44 connected to a recording 46 has to attach a sample to be measured. The second spring element 42 is made of two leaf springs 48.1 . 48.2 constructed of carbon fiber reinforced plastic, wherein the leaf springs 40.1 and 40.2 are the same size and opposite each other. The spring elements 36 and 42 form with the intermediate floor 38 a spring structure 49 ,

The bottom plate 34 is over a stamp 50 with the recording 46 connected. The Stamp 50 is about a first adjustable tie rod 52 with the first dome of the first speaker 18 connected so that a Bestromen of the first speaker 18 that causes the recording 46 moved in the x direction. Over a second coupling rod 54 is the stamp 50 with the second calotte 26 of the second speaker 22 connected so that a Bestromen the second speaker 22 the recording 46 moved in a direction perpendicular to the x-direction y-direction.

The first coupling rod 52 and the second adjustable connecting rod 54 are each connected via magnetic bearing points with the respective dome and the punch for backlash and torque-free transmission of train and thrust, with only the magnetic bearing point 56 you can see it on the second calotte 26 is glued on.

2 shows the sample positioning 10 in a different perspective, in which also a bearing point 58 can be seen, in which the second coupling rod 54 with the stamp 50 connected is. Not shown is an electrical drive unit, which is designed to the first speaker 18 and the second speaker 22 to control that recording 46 to a predetermined position relative to the base plate 32 is positioned.

The sample positioning device 10 may include a displacement measuring system for a displacement measurement in the x-direction and a displacement measuring system for a displacement measurement in the y-direction. Optionally, a z-axis can be incorporated, which includes a piezoelectric transducer, which generates a stroke of +5 microns or -5 microns relative to a zero position at a voltage swing of +40 V to -40 V and can be moved very quickly to unevenness of a sample on the recording 46 compensate.

Alternatively, the z-axis may comprise a metal diaphragm loudspeaker operated, for example, at -40V and / or 250mA with a voltage swing of +40V and having a lift of +5μm and -5μm, respectively. This metal diaphragm speaker may also be designed to perform the specified lift at a voltage swing of less than +4 volts to -4 volts, for example, from +2 volts to -2 volts. In this case, the displacement measuring system and the atomic force microscope can be operated with a voltage of ± 2 V, which is particularly favorable for use of the atomic force microscope as a school device.

The base plate 32 is square and made of aluminum. The dimensions are 100 mm × 100 mm, with the base plate 32 10 mm thick.

The speaker 18 . 22 are designed to operate with voltages between -2 V and + 2 V and 250 mA. The speakers are constructed so that the recording 46 be deflected by +50 μm or -50 μm at the specified voltages. It is also possible to operate the loudspeakers with a higher voltage, for example between +/- 10 V, and a higher current, for example up to 1 A. The deflection of the spring elements can then for example be between -250 microns and +250 microns.

The in 1 The structure shown can also be used as a microscope stage or as a micromanipulator.

3 shows a further perspective view of the atomic force microscope according to the invention 10 in which another bearing point 60 it can be seen in which the first coupling rod 52 with the first dome 62 connected is.

The atomic force microscope according to the invention comprises the sample positioning device 10 and a cantilever unit, not shown, attached to the sample positioning device 10 is fixed, and an electrical interface device for driving the first sample table drive 14 and second sample table drive 16 with an accuracy of less than 10 nm and for reading out measured data of the cantilever unit. It can also be present in its voltage adjustable power supply.

A kit according to the invention comprises the components and connecting elements described above for connecting the components to a sample positioning device according to the invention or to an atomic force microscope according to the invention.

LIST OF REFERENCE NUMBERS

10

Probenpositioniervorrichtung

12

sample table

14

first sample table drive

16

second sample table drive

18

first speaker

20

first speaker magnet

22

second speaker

24

second loudspeaker magnet

26

second dome

28

first plate

30

second plate

32

baseplate

34

baseplate

36

first spring element

38

false floor

40

leaf spring

42

second spring element

44

head

46

admission

48

leaf spring

49

spring structure

50

stamp

52

first coupling rod

54

second coupling rod

56

bearing point

58

bearing point

60

bearing point

62

first dome

Claims (10)

Sample positioning device, in particular for a scanning probe microscope, having (a) a sample table ( 12 ), (b) a first sample table drive ( 14 ), which is connected to the sample table ( 12 ) is mechanically coupled, for moving the sample table ( 12 ) in a first direction (x), (c) a second sample table drive ( 16 ), which is connected to the sample table ( 12 ) is mechanically coupled, for moving the sample table ( 12 ) in a second direction (y) different from the first direction (x), (d) wherein the first sample table drive ( 14 ) has a first plunger coil arrangement, and (e) wherein the second sample table drive ( 16 ) has a second plunger coil arrangement, characterized in that (f) the first sample table drive ( 14 ) a first speaker ( 18 ) comprising a first loudspeaker dome ( 62 ), a first loudspeaker magnet ( 20 ) and a first immersion coil arrangement, wherein the first loudspeaker magnet ( 20 ) Is part of the first plunger coil assembly, and that the second sample table drive ( 16 ) a second speaker ( 22 ) comprising a second loudspeaker dome ( 26 ), a second loudspeaker magnet ( 24 ) and a second immersion coil arrangement, wherein the second loudspeaker magnet ( 24 ) Is part of the second plunger coil assembly. Scanning probe microscope, in particular atomic force microscope, with a sample positioning device ( 10 ) according to claim 1. Scanning probe microscope according to claim 2, characterized in that the sample table ( 12 ) (i) a bottom plate ( 34 ), (ii) a stamp ( 50 ), with the bottom plate ( 34 ) is connected and a top in operating position arranged head ( 44 ) for receiving a sample to be measured, and (ii) a spring structure ( 49 ), with the stamp ( 50 ) and the bottom plate ( 34 ). Scanning probe microscope according to one of claims 2 to 3, characterized in that the spring structure ( 49 ) - a first spring element ( 36 ), - an intermediate floor ( 38 ) and - a second spring element ( 42 ), - wherein the first spring element ( 36 ) on the bottom plate ( 34 ) and the intermediate floor ( 38 ) and the second spring element ( 42 ) at the intermediate floor ( 38 ) and the head ( 44 ) is attached. Atomic force microscope according to claim 4, characterized in that - the first direction (x) and the second direction (y) are perpendicular to each other, - the first spring element ( 36 ) a first leaf spring ( 40 ) which is perpendicular to the first direction (x) and - the second spring element ( 42 ) a second leaf spring ( 48 ) which is perpendicular to the second direction (y). Atomic force microscope according to one of claims 2 to 5, characterized in that - the first plunger coil arrangement via a first coupling rod ( 52 ) with the stamp ( 50 ) is connected and - the second plunger coil assembly via a second coupling rod ( 54 ) with the stamp ( 50 ), both coupling rods ( 52 . 54 ) by means of magnetic bearing points ( 56 . 58 . 60 ) each with the respective plunger coil assembly on the one hand and the punch ( 50 ) on the other hand. Atomic force microscope according to one of claims 2 to 6, characterized in that - the first coupling rod ( 52 ) via a first magnetic bearing point ( 60 ) with the first loudspeaker dome ( 62 ) and - the second coupling rod ( 54 ) via a second magnetic bearing point ( 56 ) with the second loudspeaker dome ( 26 ) connected is. Scanning probe microscope according to one of claims 4 to 7, characterized in that the first spring element ( 36 ) and / or the second spring element ( 42 ) consists of fiber-reinforced plastic, in particular carbon fiber reinforced plastic. Kit for an atomic force microscope according to one of claims 2 to 8. Kit according to claim 9, characterized by - a first coupling rod ( 52 ), - a second coupling rod ( 54 ), - a first leaf spring ( 40 ) and - a second leaf spring ( 48 ).

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