JP2572106Y2 - Probe making device by electric field polishing - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for electrolytically polishing a probe used in a scanning tunneling microscope or the like.

[0002]

2. Description of the Related Art A metal probe used in a scanning tunneling microscope is formed by an electrolytic polishing method in the same manner as a method of forming an emitter used in an electrolytic radiation electron gun.
Conventionally, there have been several methods for forming a probe by the electrolytic polishing method. However, a change in the liquid level due to vibration sometimes disturbs the shape and the like of the formed probe.

[0003] The inventor of the present invention disclosed in Japanese Patent Application No. 4-91753 that the probe material and the annular electrode were brought into contact with the electrolyte surface while the probe material was supported so as to pass through the center of the annular electrode.
The ring electrode is fixed at a position slightly thicker than the thickness of the ring electrode from the electrolyte surface, and a voltage is applied between the probe material and the ring electrode with the liquid level difference between the inside and outside at the ring electrode part. A method for making a probe by electropolishing was proposed. According to this method, a probe having a stable shape can be formed.

[0004] This method will be briefly described with reference to FIG. 7. In FIG. 1 A, reference numeral 2 denotes a tungsten wire having a diameter of 0.2 mm to 0.3 mm whose surface is smoothed by mechanical polishing. Tungsten wire 2 and annular electrode 5
Are held by arms 10a and 10b of a lifting stand 9 via insulating members 8a and 8b. The axes are aligned by the arms 10a and 10b so that the tungsten wire 2 is located at the center of the annular electrode 5. The terminal 7 and the tungsten wire 2 are connected via a current detection circuit 6 and a power supply 4. An electrolyte 1 such as an aqueous solution of sodium hydroxide is placed in the container 11. In such a configuration, the lifting stand 9 is lowered, and the tungsten wire 2 and the ring electrode 5 are immersed in the electrolyte 1. Then, the elevating stand 9 is raised, and the annular electrode 5 is fixed at a position separated from the liquid level 12 by a distance (about 0.5 mm) slightly larger than the diameter of the wire of the annular electrode 5. FIG. 2B shows the relationship between the annular electrode 5 and the electrolyte 1.
The electrolytic solution inside the annular electrode 5 and the external electrolytic solution are in contact with each other due to surface tension or the viscosity of the electrolytic solution, and a liquid level difference occurs inside and outside the annular electrode 5. In this state, when a voltage is applied from the power supply 4 between the tungsten wire 2 and the annular electrode 5, the etching of the tungsten wire 2 starts, and as the tungsten wire 2 is sharpened, the amount of current detected by the current detection circuit 6 becomes Decreases gradually. Then, when the tungsten wire 2 is blown, the current amount sharply decreases. A differentiating circuit or the like is used for the current detection circuit 6 to detect this rapid change in the amount of current, and the power supply 4 is turned off for a change exceeding a preset threshold value. When the tungsten wire 2 is blown, the blown lower tungsten wire 2 falls in the electrolytic solution 1. With this fall, the annular electrode 5
The electrolytic solution in the inside is drawn downward, and the liquid level in the annular electrode 5 drops. Then, the electrolyte in the annular electrode 5 has the same height as the liquid level 12 on the outer periphery. That is, the annular electrode 5 and the electrolytic solution 1 are separated. Thus, the etching of the tungsten wire 2 is completed, and a sharp probe as shown in FIG. In addition, a gas is generated along with the etching of the tungsten wire 2, and the gas stays on the liquid surface and forms bubbles in the annular electrode 5. Bubbles are formed because the solution tension is higher than the gas pressure. Each bubble moves in the direction of the annular electrode 5 along the liquid surface, and the bubbles contact each other at the annular electrode 5 to become large bubbles. Then, the gas pressure increases and bubbles are released out of the solution. For this reason, the bubbles do not adsorb to the tungsten wire 2 and do not hinder the etching.

[0005]

By the way, the probe 13 formed by the method shown in FIG. 7 is cut into an appropriate length by a nipper or the like as shown by a dotted line in FIG. 8, and shown in FIG. It was attached to such a probe holder 14 and the length from the tip a to the bottom b of the holder was measured with an optical microscope, and the length was adjusted using tweezers 15 to the reference length. This operation is very difficult, and if the tweezers 15 are used incorrectly, the tip of the probe 13 may be broken. By the way, in the case of a scanning tunneling microscope, this reference length is mechanically determined by the design value of the stage, but is determined by the actual alignment according to the assembly accuracy, and each time the thickness of the sample changes variously, the length of the probe 13 is changed. Need to be moved back and forth. When the reference length becomes very short, there is no longer any grip on the wire portion of the probe 13, and it may be difficult to attach the probe 13 to the probe holder 14. Note that reference numeral 16 in FIG.
4 is a holding jig.

[0006] The present invention has been made in view of such problems, and its purpose is to solve the above-mentioned problem.
It is an object of the present invention to provide a probe making device by electric field polishing for easily making a probe used for a scanning tunnel microscope or the like in a form that can be easily attached to the device main body by using the method of No. 3.

[0007]

In order to achieve the above object, the present invention provides an electric field polishing probe forming apparatus for electrolytically polishing a probe wire and an annular electrode while supporting the probe wire so as to pass through the center of the annular electrode. After contacting the liquid surface, fix the annular electrode at a position slightly thicker than the thickness of the annular electrode from the electrolyte surface, and fix the annular electrode part with the liquid level difference between the inside and outside of the probe wire. In a probe making apparatus by electropolishing in which a voltage is applied between the electrode and a ring electrode, a probe for accommodating an electrolytic solution, which is mounted on an upper portion of the container, and which can be directly attached to a ring electrode and a device such as a scanning tunnel microscope. A support for supporting a probe wire holder having a needle wire attached thereto, a height adjusting mechanism for adjusting a relative height between the annular electrode and the probe wire supported by the support, and at least the aforementioned The ring electrode supported by the support Means for temporarily positioning the liquid level or below the liquid level from a state in which the liquid level is not in contact with the electrolytic solution level in the container, and a means for returning to the original state again. Is what you do.

[0008] Another type of probe making apparatus using electric field polishing is a method in which a probe wire and an annular electrode are brought into contact with an electrolyte surface in a state where the probe wire is supported so as to pass through the center of the annular electrode. Electropolishing in which the liquid is fixed at a position slightly thicker than the thickness of the ring electrode from the liquid level, and a voltage is applied between the probe wire and the ring electrode with the liquid level difference between the inside and outside at the ring electrode part In the probe making device according to the present invention, a container for accommodating an electrolytic solution, a probe wire holder attached to the upper portion of the container, and directly attached to a ring electrode and a device such as a scanning tunneling microscope and having a probe wire attached thereto. And a height adjusting mechanism for adjusting a relative height between the annular electrode and the probe wire supported by the support, and a ring-shaped liquid surface of the electrolytic solution contained in the container. Temporary liquid level from the height where the electrodes do not touch Is raised to a height which is located below the liquid level, it is characterized in that it comprises a means for returning to the original height again.

[0009]

In the present invention, a container for accommodating an electrolytic solution;
A support that is attached to the top of the container and supports a ring electrode and a probe wire holder that can be directly attached to a device such as a scanning tunnel microscope and has a probe wire attached thereto, and a ring electrode supported by the support A height adjusting mechanism for adjusting the relative height between the probe and the probe wire, and further, a state in which at least the annular electrode supported by the support is arranged without contacting the electrolyte surface in the container. A means for temporarily positioning the liquid surface or below the liquid surface from and returning to the original state again,
Alternatively, a means for temporarily raising the liquid level of the electrolytic solution contained in the container from a level at which the ring electrode does not come into contact with the liquid level or a level located below the liquid level, and returning the liquid level to the original level again With either of the means, the probe wire can be easily and reliably formed with good reproducibility while the probe wire is attached to the probe wire holder at a preset length. Therefore, the length adjustment is not required, and it is extremely easy to mount the device on a scanning tunnel microscope or the like, so that a careful mounting operation is not required.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a probe making apparatus according to the present invention; FIG. 1 is a sectional view showing the entire configuration of one embodiment,
FIG. 2 is an enlarged sectional view of the main part. As shown in FIGS. 1 and 2, an annular cathode 24 is attached to a holding block 23 for inserting and holding a probe holder 22 attached around one end of a probe wire 2 made of a tungsten wire or the like. The height is adjustable by a screw 25 which is screwed through the holding block 23 in the axial direction. An elastic body 26 is attached to the upper edge of the holding block 23. On the other hand, the lid 2 on the upper part of the container 27 for containing the electrolyte 1
8 is provided with a hole through which the lower part of the holding block 23 penetrates.
When the holding block 23 is inserted into the hole of the lid 28 from above, it comes into contact with the edge of the hole. Figure 2
Reference numerals 9 and 30 are introduction terminals for voltage application. Also,
31 is a jig for holding the probe holder 22.

In such a configuration, the probe holder 22 to which the probe wire 2 is fixed is inserted into the holding block 23, and the ring lower end 24a of the annular cathode 24 attached to the holding block 23 has a reference length. Using an optical microscope,
Turn the screw 25 to adjust. This adjustment need only be performed once unless it is necessary to change the length of the probe. Next, the holding block 23 is inserted into the hole of the lid 28. The level of the electrolytic solution 1 in the container 27
4a is about 1 mm below (FIG. 3
(A)). The end of the holding jig 31 and the terminal of the annular cathode 24 are connected to the introduction terminals 29 and 30. And FIG.
As shown in (b), when the upper end of the holding jig 31 is pushed down, the elastic body 26 is distorted, and the annular cathode 24 comes into contact with the liquid surface of the electrolytic solution 1. Thereafter, if the user releases his hand, the annular cathode 24 rises, but the liquid level in the annular cathode 24 rises higher than the liquid level on the outer periphery due to the surface tension of the electrolytic solution 1, as shown in FIG. In this state, as disclosed in Japanese Patent Application No. 4-91753 (see FIG. 7), when a voltage is applied from the power supply between the probe wire 2 and the annular cathode 24, the etching of the probe wire 2 is started. As the probe wire 2 is sharpened, the amount of current detected by the current detection circuit gradually decreases, and when the probe wire 2 is blown, the amount of current sharply decreases. A differentiating circuit or the like is used in the current detection circuit to detect this sudden change in the amount of current, and the power supply is turned off for a change exceeding a preset threshold value. When the probe wire 2 is blown, the blown lower probe wire 2 falls in the electrolytic solution 1. Along with this drop, the electrolytic solution 1 in the annular cathode 24 is pulled downward, and the liquid level in the annular cathode 24 drops. And
The electrolyte 1 in the annular cathode 24 has the same height as the liquid level on the outer periphery, and the annular cathode 24 and the electrolyte 1 are separated. For this reason,
The etching of the probe wire 2 is completed, and a sharp probe as shown in FIG. 7C is completed.

After the etching is completed, the probe holder 22 together with the holding block 23 is removed from the lid 28, and the probe holder 22 together with the holding block 23 is attached to a cleaning device having a similar structure. After being immersed in a cleaning solution and washed, the probe holder 22 is removed from the holding block 23, and the probe integrated with the probe holder 22 is introduced into a scanning tunnel microscope and attached.

In the above, the length of the probe is adjusted by adjusting the height of the annular cathode 24 with respect to the holding block 23. However, as shown in FIG. The length can be adjusted by the screw 32 so that the length of the probe is adjusted without moving the annular cathode 24. In the above-described embodiment, the elastic body 26 is interposed between the holding block 23 and the lid 28. However, as shown in FIG. 5A, a structure is adopted in which the upper surface of the lid 28 is bent. As shown in FIG. 5B, an elastic body 26 may be interposed between the lid 28 and the container 27.

In another embodiment, as shown in the sectional view of FIG. 6, an expandable spring 33 is attached to the lower end of the hole of the thick lid 28, and the probe holder 22 is attached to the hole. The holding jig 31 is immersed, and the holding jig 31 is urged upward by the action of the spring 33. Then, a micrometer 34 is attached to the upper end of the hole, and by adjusting the micrometer 34, the probe holder 22 with respect to the lid 28 is
The height of the is adjustable. Therefore, at this point, as in the case of FIG. 4, the length of the probe can be adjusted without moving the annular cathode 24. In the case of this embodiment, the rise and fall of the annular cathode 24 with respect to the level of the electrolyte 1 is not performed, but the level of the electrolyte 1 itself in the container 27 is adjusted. For this purpose, an upward expandable spring 36 is mounted in the container 27, and a volume 35 is placed thereon so as to come out of the liquid level. Then, a bar 37 that penetrates through the lid 28 and that can push down the volume 35 against the action of the spring 36 is attached. With this configuration, at least a part of the volume 35 is exposed above the liquid surface of the electrolyte 1 unless the bar 37 is pushed down.
Is at the height of the solid line determined by the weir 38. When the bar 37 is depressed, the volume 35 enters the electrolyte 1 and
The liquid level rises to the height of the dotted line and contacts the annular cathode 24. Thereafter, when the user releases his hand, the liquid level drops to the height of the solid line, but the liquid level in the annular cathode 24 becomes relatively higher than the liquid level on the outer periphery due to the surface tension of the electrolytic solution 1.

Although the present invention has been described based on several embodiments of the probe making apparatus using electric field polishing according to the present invention, the present invention is not limited to these embodiments, and various modifications are possible.

[0016]

As is clear from the above description, according to the probe making apparatus by electric field polishing of the present invention, a container for accommodating an electrolytic solution, a ring electrode and a scanning tunnel microscope mounted on the upper portion of the container. And a support for directly supporting the probe wire holder to which the probe wire is attached, and for adjusting the relative height between the annular electrode and the probe wire supported by the support. Height adjustment mechanism, and
At least temporarily place the annular electrode supported by the support above the liquid surface or below the liquid surface from a state in which the ring electrode is not in contact with the electrolyte surface in the container, and to return to the original state again Means or for temporarily raising the liquid level of the electrolyte contained in the container from a level at which the ring electrode does not come into contact with the liquid level or a level located below the liquid level, and then returning to the original level again The probe wire is attached to the probe wire holder at a preset length, and the probe can be easily and reliably formed with good reproducibility. Therefore, the length adjustment is not required, and it is extremely easy to attach to a scanning tunnel microscope or the like, so that a careful attaching operation is not required.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an entire configuration of an embodiment of a probe making device of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the embodiment of FIG.

FIG. 3 is a view for explaining a step of creating a probe using the apparatus of FIG. 1;

FIG. 4 is a sectional view of a main part showing a modification of FIG. 1;

FIG. 5 is a sectional view of a main part showing another modification.

FIG. 6 is a cross-sectional view showing the overall configuration of another embodiment.

FIG. 7 is a diagram for explaining a method of preparing a probe by electric field polishing proposed earlier.

FIG. 8 is a diagram showing a state in which a probe is cut out from a probe created by the method proposed above.

FIG. 9 is a diagram for explaining a problem associated with the previously proposed probe creation method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrolyte solution 2 ... Probe wire 22 ... Probe holder 23 ... Holding block 24 ... Annular cathode 24a ... Annular cathode lower end 25 ... Screw 26 ... Elastic body 27 ... Container 28 ... Lid 29, 30 ... Introducing terminal 31 ... Holding Jig 32 ... Screw 33 ... Spring 34 ... Micrometer 35 ... Volume 36 ... Spring 37 ... Bar 38 ... Weir

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor: Ken Sekine 3-1-2-2 Musashino, Akishima-shi, Tokyo Japan Electronic Engineering Co., Ltd. (56) References JP-A-5-261625 (JP, A) JP-A 4-217427 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 9/02 B23H 9/08 C25F 3/22 G01B 7/34 H01J 37/28

Claims (2)

(57) [Scope of request for utility model registration] After the probe wire and the ring electrode are brought into contact with the electrolyte surface in a state where the probe wire is supported so as to pass through the center of the ring electrode, the ring electrode is slightly separated from the electrolyte surface by a thickness smaller than the thickness of the ring electrode. In a probe making apparatus by electrolytic polishing in which a voltage is applied between a probe wire and a ring electrode in a state where a liquid level difference between the inside and the outside is provided at a ring electrode portion by fixing at a position separated by a thick portion,
A container for storing the electrolyte, and a liquid crystal device mounted on the upper portion of the container and directly connected to a ring electrode and a device such as a scanning tunnel microscope.
A support for supporting a probe wire holder to which a probe wire can be attached , and a height adjustment for adjusting a relative height between the annular electrode supported by the support and the probe wire; Mechanism, and at least the annular electrode supported by the support is temporarily positioned below the liquid surface or below the liquid surface from a state in which the annular electrode is not in contact with the electrolyte surface in the container, and is returned to the original state. And a means for restoring the probe. 2. After the probe wire and the ring electrode are brought into contact with the electrolyte surface in a state where the probe wire is supported so as to pass through the center of the ring electrode, the ring electrode is slightly separated from the electrolyte surface by a thickness smaller than the thickness of the ring electrode. In a probe making apparatus by electrolytic polishing in which a voltage is applied between a probe wire and a ring electrode in a state where a liquid level difference between the inside and the outside is provided at a ring electrode portion by fixing at a position separated by a thick portion,
A container for storing the electrolyte, and a liquid crystal device mounted on the upper portion of the container and directly connected to a ring electrode and a device such as a scanning tunnel microscope.
A support for supporting a probe wire holder to which a probe wire can be attached and to which a probe wire is attached , and for adjusting a relative height between the annular electrode and the probe wire supported by the support. Height adjustment mechanism, the liquid level of the electrolytic solution contained in the container is temporarily raised from a height at which the ring electrode does not come into contact with the liquid level or a level located below the liquid level, and the original height is returned again. And a means for restoring the probe to an electric field.