JPH06186027A - Atomic force microscope - Google Patents

Abstract

PURPOSE:To provide an atomic force microscope which can easily carry out the changing of a sample or a cantilever or the adjustment of the displacement detecting system for the cantilever only through a transfer rod. CONSTITUTION:A transfer jig 44 has a bottomed cylindrical body 46 and a disc 40 attached to its bottom. The body 46 has two projecting parts 48 at its opening ends, and the projecting part 48 has a protruding part 50 protruding inward. The inside of the body 46 is provided with magnets 52, 54. A cantilever holder 56 has a slope part to which the cantilever 58 is attached and a threaded portion 57. A scanner 24 has a cylindrical piezoelectric actuator 62 fixed to a base 60, and its tip part is provided with a regulating screw 72, and a coil spring 66 and a holder support 68 are accommodated in its inside. An optical fiber 76 is inserted into the base 60 and fixed, and its tip part passes through the thread hole 70 of the holder support 68 and protrudes.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an atomic force microscope.

[0002]

2. Description of the Related Art An atomic force microscope (Atomic Force Micros
cope (AFM)). This AFM is a device proposed by Binich et al., The inventor of the scanning tunneling microscope (STM), and the details are described in "G.binnig, CFQuate," Atomic.
Force Microscope ", Physical Review Letters, Vol.5
6, 930 (1986) ". When a sharply pointed probe is brought close to the sample surface, van der Waals appear between the atom on the tip of the probe and the atom on the sample surface.
An attractive force proportional to the −7th power of the interatomic distance acts due to the interaction. Further, when the probe is brought closer to the sample surface and the distance between the atom at the tip of the probe and the atom on the sample surface becomes about the bond distance of the atoms, the repulsive force due to Pauli exclusion rule acts between them. These attractive and repulsive forces are generally called atomic forces, and their magnitude is very small, about 10-19 to 10-12 [N]. The atomic force microscope is an apparatus for examining irregularities on the sample surface by utilizing this atomic force, and its outline will be described below. In the atomic force microscope, a probe supported on the free end of a flexible cantilever is brought close to the sample until the cantilever is displaced to some extent by the atomic force generated between the tip of the probe and the atom on the sample surface. From this state, the probe or the sample is moved, and the probe is raster-scanned along the sample surface. During that time, the displacement of the free end of the cantilever caused by the change in the inter-sample distance corresponding to the unevenness of the sample surface is constantly detected,
The inter-probe sample distance is controlled by using a fine movement element such as a piezoelectric element so that this displacement always becomes an initial value. Therefore, the tip of the probe draws a trajectory that reflects the unevenness of the sample surface. This trajectory is processed together with the position information on the sample surface to obtain an image showing the surface shape of the sample.

As a method of detecting the displacement of the free end of the cantilever, there are a method using a tunnel current, a method using an optical lever method, and a method using an optical interference method. In the method using the tunnel current, the conductive probe is placed close to the back surface of the free end of the cantilever (the surface opposite to the probe),
A bias voltage is applied between the probe and the cantilever, and the displacement of the free end of the cantilever is detected as a change in the tunnel current flowing between the two. In the optical lever method, the back surface of the free end of the cantilever is irradiated with a light beam at a predetermined angle, the reflected beam is received by the PSD, and the change in the reflection angle due to the displacement of the free end of the cantilever is reflected by the PSD. It is detected as a change and the displacement of the free end of the cantilever is calculated. In the optical interferometry, coherent light is divided into reference light and detection light, the detection light is applied to the back surface of the free end of the cantilever, and the reflected light is caused to interfere with the reference light. Seeking displacement.

[0004]

There are several problems in operating an atomic force microscope in a vacuum vessel. (1) If the detection system does not cool the heat, the detection system itself will fail. (2) Since the cantilever has directionality, it must always be attached to the scanner in the same direction. (3) The cantilever holder must be small and easy to remove. (4) Cantilever replacement, sample replacement, fiber coarse movement adjustment, etc. must be able to be performed with one transfer rod that can rotate and go straight.

An object of the present invention is to provide an atomic force microscope capable of easily exchanging a sample or a cantilever, adjusting a displacement detection system of the cantilever, and the like only by using a transfer rod.

[0006]

The present invention is an atomic force microscope housed in a vacuum chamber, in which a cantilever holder holding a cantilever can be attached and detached, and a scanner for scanning the attached cantilever with respect to a sample is provided. The atomic force microscope has a cantilever holder that is attached to and detached from the scanner by using a transfer rod that can move forward and backward and rotate in the chamber.Atomic force microscope has a means for holding the cantilever holder. It has a possible transfer jig and means for attaching the cantilever holder to the scanner with the cantilever holder always facing the same direction.

[0007]

In the present invention, the cantilever holder is held by the transfer jig, and is mounted on the scanner by advancing and retracting and rotating the transfer rod. The cantilever holder is attached to the scanner so that the cantilevers always face the same direction. This is achieved, for example, by providing a screw hole on the scanner side, providing a screw part that matches this with the cantilever holder, and forming the screw part so that it faces the same direction when tightened with a predetermined load. To be done. Alternatively, this can be achieved by providing the cantilever holder with a prismatic protrusion and providing a hole on the scanner side into which the protrusion can be inserted.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. The apparatus of the present embodiment, as shown in FIG.
It has a main chamber 12 and a load lock chamber 14 which are connected via a gate valve 16. In the main chamber 12, a main unit stand 18
Is provided. An atomic force microscope unit 22 is supported on the main unit base 18 via a vibration isolation mechanism 20. A scanner 24 and a sample table 26 are arranged on the atomic force unit 22. Also, the main chamber 1
2 is provided with an arm member 28 that can be vertically moved from outside the chamber. On the other hand, in the load lock chamber 14, a sample table 26, a cantilever holder 56, and a reservoir 30 for storing and storing the transfer jig 44 are provided so as to be vertically movable. The reservoir 30 is retracted upward when the transfer rod 32 is inserted into the main chamber 12 via the gate valve 16.

During the work of exchanging the sample and the cantilever using the transfer rod 32, the atomic force microscope unit 22 is mounted on the main unit base 18 by the arm member 28.
Fixed to. Therefore, as shown in FIG. 2, a stopper member 19 having a V-shaped cut portion is provided on the main unit base 18, and a projection 23 is provided on the lower surface of the atomic force microscope unit 22. When the atomic force microscope unit 22 is lowered by lowering the arm member 28, the projection 23 is housed in the cut portion of the stopper member 19, and the arm member 28 presses the atomic force microscope unit 22 against the main unit base 18. Be fixed by that.

As shown in FIG. 3, the transfer rod 32 has a T-shaped tip portion 36. The tip portion 36 is to be inserted into the sample table 26 or the transfer jig 44 to support it.

The sample table 26, as shown in FIG.
A disk 4 having a substantially cubic block 38 into which the tip 36 of the transfer rod 32 can be inserted.
0 is provided, and the sample is attached to the opposite surface. As shown in FIG. 5, the disk 40 has an opening 41 into which the tip 36 of the transfer rod 32 is inserted, and after insertion, the thin portion 40a is provided so that the tip 36 can be turned to the right or left within a predetermined angle range. Is provided. As a result, the tip 36 of the transfer rod 32 is moved to the disc 40
The sample holder 26 can be held by inserting the transfer rod 32 into the opening 41 and rotating the transfer rod 32 clockwise or counterclockwise. To replace the sample or to temporarily withdraw it to replace the cantilever, the atomic force microscope is used. Unit 22
It becomes possible to carry between the container and the reservoir 30.

Next, replacement of the cantilever will be described with reference to FIG. The replacement of the cantilever is performed together with the cantilever holder 56 using the transfer jig 44. The transfer jig 44 has a bottomed cylindrical main body 46 and a disk 40 (see FIG. 5) attached to the bottom surface thereof. Two projecting portions 48 are provided at centrally symmetrical positions at the open end of the body 46, and the projecting portions 48 have a projecting portion 50 that projects inward from the inner diameter of the body 46. Inside the main body 46, two substantially prismatic magnets 52 projecting toward the center so as to face each other, and two substantially prismatic magnets projecting so as to face each other toward the center from a direction orthogonal thereto. Magnet 54 is provided. The cantilever holder 56 has an inclined surface portion to which the cantilever 58 is attached and a screw portion 57. The scanner 24 is an atomic force microscope unit 22.
It has a base 60 fixed to (as shown in FIG. 1) and a cylindrical piezoelectric actuator 62 fixed to this.
Inside the cylindrical piezoelectric actuator 62, a coil spring 66 and a holder receiver 68 are inserted.
2 is a screw 6 at the tip of the cylindrical piezoelectric actuator 62
It is tightened to 4. An optical fiber 76 is inserted into and fixed to the base 60, and a tip portion of the optical fiber 76 projects through a screw hole 70 of the holder receiver 68.

Like the sample table 26, the transfer jig 44 is held and moved by the transfer rod 32 by inserting the tip 36 of the transfer rod 32 into the opening 41 of the disk 40 and then turning it to the right or left. And rotation operation becomes possible. The cantilever holder 56 is made of a magnetic material, is housed in the space between the tips of the four magnets, and is held by the magnetic force. The operation of attaching the cantilever holder 56 housed in the transfer jig 44 to the scanner 24 is performed as follows.

The transfer jig 44, which holds the cantilever holder 56, is placed on the scanner 24 so as to avoid the protrusion 48 of the main body 46 from hitting the protrusion 74 of the adjusting screw 72. Cantilever holder 5
When the screw portion 57 of 6 hits the end of the screw hole 70 of the holder receiver 68, the transfer rod 32 is rotated to screw in the cantilever holder 56. The screw portion 57 of the cantilever holder 56 is formed so as to always face the same direction when tightened with a predetermined load. As a result, the cantilever 58 is always mounted in the same direction. As shown in FIG. 6, the cantilever holder 56 has a through hole substantially in the center thereof, and when attached to the holder receiver 68, the tip of the optical fiber 76 is arranged above the lever portion of the cantilever 58. The distance d between the lever portion and the tip of the optical fiber 76 is adjusted by rotating the adjusting screw 72. Adjustment screw 72
Is rotated as follows.

The transfer jig 44 is attached to the scanner 24.
Adjust the overburden depth so that the protrusion 48 of the body 46 is exactly at the protrusion 74 of the adjusting screw 72. From this state, when the transfer rod 32 is turned to the right or left to rotate the transfer jig 44, the overhanging portion 50 of the protruding portion 48 of the main body 46 hits the protrusion 74 of the adjusting screw 72 and the adjusting screw 72 is moved to the right or left. Rotate to. As a result,
The adjustment screw 72 is loosened or loosened, and the optical fiber 7
6, the cantilever holder 56 moves back and forth, that is, in the axial direction, and the distance d between the tip of the optical fiber 76 and the lever portion of the cantilever 58 is adjusted.

By the way, in the above description, the sample table 26 is held by using the transfer rod 32. However, the transfer jig 44 is configured as follows.
Can also be held. The structure is such that a screw is provided on the overhanging portion 50 of the main body 46 of the transfer jig 44, and as shown in FIG.
The screw part 42 that fits the 0 screw is attached to the block 38 of the sample table 26
To be installed. Block the screws of the overhanging portion 50 of the main body 46 to the block 38
The sample stage 26 can be held by using the transfer jig 44 by screwing the sample stage 26 into the screw portion 42.

Next, another example of the transfer jig and the corresponding cantilever holder and holder holder will be described with reference to FIG. Unlike the transfer jig of FIG. 7, the transfer jig of this example does not have the magnets 52 and 54,
Instead, the main body 46 of the transfer jig has a groove 88 extending in the length direction from the opening end, a groove 90 extending in the circumferential direction from the end of the groove 88, and a groove 88 extending from the end of the groove 90 in the opening end direction. Groove 92. Other configurations are the same as those in FIG. 7. The cantilever holder 84 has two arms 86 extending in parallel on both sides thereof and a prismatic projection 85. The holder receiver 78 has a through hole 80 into which the prismatic protrusion 85 of the cantilever holder 84 can be inserted. Further, four elongated leaf springs 82 are provided on the front end surface thereof, that is, the surface exposed from the adjusting screw 72. Two leaf springs 82 are paired, and the paired two leaf springs 82 are bent so that the middle thereof spreads outward.

The mounting of the cantilever holder 84 to the transfer jig is performed as follows. First, the groove 88 of the transfer jig main body 46 is inserted into the cantilever holder 8.
4, the transfer jig is moved straight, and the arm 86 is inserted along the groove 88. Arm 86
When reaches the end of the groove 88, the transfer jig is rotated to the right until the arm 86 reaches the end of the groove 90. After that, when the transfer jig is retracted, the arm 86
Is caught at the end of the groove 92, and the cantilever holder 8
4 is held by the transfer jig.

The cantilever holder 84 is mounted on the holder receiver 78 as follows. After arranging so that the tips of the two leaf springs 82 of each set come respectively between the two arms 86 on both sides of the cantilever holder 84, the transfer jig is moved straight. Arm 8
6 advances by crushing the expanded portion of the leaf spring 82, and the prismatic projection 85 of the cantilever holder 84 is inserted into the through hole 80 of the holder receiver 78. After that, the cantilever holder 84 is removed from the transfer jig by the completely reverse procedure of mounting the cantilever holder 84 on the transfer jig. Cantilever holder 8
4 is held in a state where its back surface is in contact with the front end surface of the holder receiver 78 by the elastic force of the two leaf springs 82 of each set to spread outward. The removal of the cantilever holder 84 is performed by the procedure which is completely opposite to this.
In this example, since the through hole 80 of the holder receiver 78 is a square, the cantilever holder 84 is attached so that the cantilevers always face the same direction.

Next, another example of the cantilever holder and the holder receiver will be described with reference to FIG. The transfer jig used in this example is exactly the same as that shown in FIG. Cantilever holder 100
Has two arms 102 extending one from each side.
And a columnar protruding portion 101 protruding from the back surface thereof. The holder receiver 94 has a circular through hole 96, and has two elongated leaf springs 98 extending parallel to the front end surface thereof.
have. The leaf spring 98 has one end fixed and the other end bent so as to be separated from the front end face. It also has two elongated leaf springs 98 extending in parallel. The leaf spring 98 is bent so that its free end is separated from the front end face.

The cantilever holder 100 is mounted on the transfer jig in the same manner as in the example of FIG.
To attach the cantilever holder 100 to the holder receiver 94, the arm 102 is arranged in an angular direction in which the arm spring does not contact the leaf spring 98, and the transfer jig is moved straight. When the back surface of the cantilever holder 100 hits the front end surface of the holder receiver 94, the transfer jig is turned to the right. As a result, the arm 102 is inserted between the front end surface of the holder receiver 94 and the leaf spring 98, and the cantilever holder 100 is held. In this example, the arm 102 is a leaf spring 98.
It is applied to the fixed end of and always in the same direction.

Still another example of the cantilever holder and the holder receiver is shown in FIG. Cantilever holder 1
The reference numeral 12 has two arms 114 made of a magnetic material and extending on both sides thereof, and a prismatic protrusion 116 protruding from the back surface. The holder receiver 106 is a prismatic protrusion 1
16 has a rectangular through hole 108 into which the hole 16 can be just inserted, and magnets 110 provided on both sides of the through hole 108 at the front end surface thereof.

The cantilever holder 112 is mounted on the transfer jig in the same manner as in the example of FIG.
To attach the cantilever holder 112 to the holder receiver 106, the arm 114 is arranged in an angular direction in which the magnet 110 abuts, the transfer jig is moved straight, and the prismatic protrusion 116 is inserted into the through hole 108. In the cantilever holder 112 thus inserted, the arm 114 is attracted and held by the magnetic force of the magnet 110. In this example, since the through hole 108 of the holder receiver 106 is rectangular, the cantilever holder 112 is attached so that the cantilevers always face the same direction.

[0024]

According to the present invention, the cantilever holder can be attached to the scanner so that the cantilever always faces the same direction by moving the transfer rod straight forward / backward and rotating.

[Brief description of drawings]

FIG. 1 shows the overall configuration of an atomic force microscope according to an embodiment of the present invention.

FIG. 2 shows a structure for fixing an atomic force microscope unit to a main chamber table.

FIG. 3 shows a shape of a tip portion of a transfer rod.

FIG. 4 is a diagram showing a configuration of a sample table.

FIG. 5 shows a configuration of a disk attached to the sample stand shown in FIG. 4 (A).

FIG. 6 is a partial cross-sectional view showing an enlarged configuration of a cantilever holder and its periphery.

[Fig. 7] Trough fur jig, cantilever holder,
It is a figure which shows the structure of a scanner, (A) is the perspective view,
(B) is a cross-sectional view of (A) taken along the line BB.

8A and 8B are views showing a configuration of a transfer jig, a cantilever holder, and a scanner according to another example, FIG. 8A is a perspective view thereof, and FIG. 8B is a cross section taken along line BB of FIG. 8A. FIG. 1C is a cross-sectional view of FIG. 1A taken along the line C-C.

FIG. 9 is a diagram showing a configuration of a transfer jig, a cantilever holder, and a scanner according to still another example, (A).
Is a perspective view thereof, (B) is a sectional view of (A) taken along the line BB, and (C) is a sectional view of (A) taken along the line C-C.

FIG. 10 is a transfer jig according to still another example,
It is a diagram showing the structure of the cantilever holder and scanner,
(A) is the perspective view, (B) is sectional drawing when (A) is broken by the BB line, (C) is sectional drawing when (A) is broken by the CC line.

[Explanation of symbols]

40 ... Disc, 44 ... Transfer jig, 46 ... Main body,
52, 54 ... Magnet, 56 ... Cantilever holder, 57
… Screw part, 68… Holder holder, 70… Screw hole.

Claims (1)

[Claims] 1. An atomic force microscope housed in a vacuum chamber, wherein a cantilever holder holding a cantilever can be attached and detached, and a scanner for scanning the attached cantilever with respect to a sample is provided, and the cantilever holder is inside the chamber. In an atomic force microscope that is attached to and detached from a scanner by using a transfer rod that can move forward and backward and rotate, a transfer jig that has a means for holding a cantilever holder, a detachable transfer jig at the tip of the transfer rod, and a cantilever. Atomic force microscope, characterized in that it has means for attaching the holder to the scanner in the same direction.