KR100948705B1 - Method And Appratus For Manufacturing Hyperfine Needle Electrode - Google Patents

Abstract

The present invention relates to a method and apparatus for manufacturing an ultra-fine needle electrode, and more particularly, to predict the etching amount of the current tungsten wire by measuring the current applied to the tungsten wire in real time and substituting the current value into an electrochemical model. The present invention relates to an ultrafine needle electrode manufacturing method and apparatus capable of producing an ultrafine needle electrode having a desired shape by adjusting the depth of immersion of a tungsten wire based on the amount thereof.

for teeth,

(a) obtaining a tungsten wire into the electrolyte solution;

(b) applying a voltage by connecting a positive electrode to the tungsten wire and a negative electrode to an electrolyte solution;

(c) measuring a current value flowing in the electrolyte solution;

(d) predicting the radius of the tungsten wire;

(e) calculating the extraction length of the tungsten wire;

(f) moving the tungsten wire by the calculated extraction length;

(g) manufacturing an ultrafine needle electrode, comprising repeating steps (c) to (f) until the current value measured in step (c) is greater than or equal to a set value. It provides a method and apparatus.

Ultra fine needle electrode, precise geometry control, real time, tungsten wire, etching, electrochemical model.

Description

Method and Apparatus for Manufacturing Ultrafine Needle Electrode {Method And Appratus For Manufacturing Hyperfine Needle Electrode}

The present invention relates to a method and apparatus for manufacturing an ultra-fine needle electrode, and more particularly, to predict the etching amount of the current tungsten wire by measuring the current applied to the tungsten wire in real time and substituting the current value into an electrochemical model. The present invention relates to an ultrafine needle electrode manufacturing method and apparatus capable of producing an ultrafine needle electrode having a desired shape by adjusting the depth of immersion of a tungsten wire based on the amount thereof.

In general, nanotechnology is a radically different concept from micro (one-millionth) technology, which is still synonymous with micro technology. To date, nano technology only makes things small but does not change the arrangement of molecules. Technology is free to manipulate at the molecular level, allowing the creation of entirely new concepts as well as changes in the properties of matter.

The ultrafine needle electrode, a component that enables such nanotechnology, is an electron beam source such as ultra-precision machining, milling, drilling, ultra-fine lithography, scanning tenneling microscope (STM), or scanning electron microscope (SEM). It is used as an important part of the equipment for the ultra-fine processing field such as the electron beam source and the ultra-structural research field.

To explain this in detail, a general microscope refers to an optical microscope, which is a device for observing a study subject using sunlight, and the limitation of these devices appears in a resolution. Resolution refers to the smallest unit that can distinguish objects, and it is difficult to distinguish nano-class objects using a general optical microscope. Therefore, in order to classify the microstructured object, a microscope using energy with better resolution than sunlight is needed, and at this time, electron emission near the apex of the ultrafine needle electrode placed on the electric field using the ultraneedle electrode It is possible to observe objects using these electrons instead of sunlight by inducing. If the electron beam emitted from the tip of the ultra-fine needle electrode is used at a short distance, the intensity is higher, which may cause scratches on the surface of a metal or an insulator. The technology using this is ultra-precision machining and milling. Perforation, lithography.

Representative and easiest method of manufacturing the ultra-fine needle electrode as described above is an etching method using the electrochemical principle. The tip of the tungsten wire is immersed in NaOH or KOH electrolyte solution and a 5-15 V voltage is applied to the tungsten wire to the anode, platinum or copper electrode to induce an electrochemical reaction to form an ultrafine tip on the tungsten wire. Can be.

However, according to the conventional manufacturing technique as described above, there was a restriction that a large amount of experiments were required to manufacture an ultrafine electrode having a desired shape, and there was a problem that it was difficult to reproduce the same.

The present invention has been made in view of the above, and provides an ultrafine needle electrode manufacturing method and apparatus capable of producing an ultrafine needle electrode having a desired shape without undergoing a step of setting conditions through a large amount of experiments. There is a purpose.

Ultrafine needle electrode manufacturing method of the present invention as described above,

(a) obtaining a tungsten wire into the electrolyte solution;

(b) applying a voltage by connecting a positive electrode to the tungsten wire and a negative electrode to an electrolyte solution;

(c) measuring a current value flowing in the electrolyte solution;

(d) predicting the radius of the tungsten wire;

(e) calculating the extraction length of the tungsten wire;

(f) moving the tungsten wire by the calculated extraction length;

(g) repeating steps (c) to (f) until the current value measured in step (c) is greater than or equal to a set value.

On the other hand, the ultrafine needle electrode manufacturing apparatus which is another aspect of the present invention,

Tungsten wire part;

An electrolyte solution portion connected to the tungsten wire portion to cause an electrochemical reaction with the tungsten wire;

A voltage applying part connected to the tungsten wire part and the electrolyte solution part to apply a voltage;

A current measuring unit measuring a current value connected between the voltage applying unit and the electrolyte solution unit;

A wire control unit connected to the tungsten wire unit to adjust the depth of immersion of the tungsten wire;

And a control unit connected to the voltage applying unit, the current measuring unit, and the wire control unit to identify and control their states.

According to the ultrafine needle electrode manufacturing method and apparatus of the present invention as described above, the production of ultrafine needle electrodes having a desired shape can be easily performed without a plurality of experiments, and also the production of a plurality of ultrafine needle electrodes using the parallel structure. Is possible at the same time. Since the needle electrode is used as an important part of ultra-structured research equipment such as STM or SEM and the equipment for measuring electrical characteristics of semiconductor or display devices, various commercial and economic effects are expected in the future.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this application, the terms “comprises” or “having” are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification, and one or more other It is to be understood that the present invention does not exclude the possibility of the presence or the addition of features, numbers, steps, operations, components, parts, or a combination thereof.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, Faraday's law of electrolysis is applied to the electrochemical etching mechanism of the tungsten wire to derive a proportional model 110 between the mass of precipitated tungsten and the current value 100 passing therethrough. On the basis of this, the etching amount of the tungsten wire currently obtained in the electrolytic solution is estimated (120), and the estimated etching amount is substituted into the cross-sectional shape function (130) to determine the tungsten wire extraction height from the electrolyte solution surface (140). ).

The ultrafine needle electrode manufacturing apparatus using the above method will be described with reference to FIG. 2. First, there is a wire portion 210 that is manufactured as a needle electrode, and the wire portion is obtained in the electrolyte solution portion 220. When a positive voltage is applied to the wire part and a negative voltage to the electrolyte solution part by the voltage applying part 230, etching of the wire part starts, and the current measuring part 240 measures a current value flowing through the electrolyte solution. To the control unit 250. The controller estimates the etching amount using the input current value, determines the tungsten wire extraction height from the surface of the electrolytic solution by substituting the predicted etching amount into the cross-sectional shape function, and transmits it to the wire control unit 200. The wire control unit 200 adjusts the depth of acquisition of the wire unit 210 according to the input height value.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 3.

The NaOH or KOH electrolyte solution 360 is filled in a predetermined container 370, the positive electrode is connected to the tungsten wire 340, and the negative electrode is connected to the platinum or copper electrode 350 to supply the power supply. When the 310 supplies a predetermined power, an electrochemical etching reaction of the tungsten wire 340 contained in the electrolyte solution 360 occurs.

Here, the tungsten wire 340 is connected to the motor drive stage 320 capable of vertical transfer, so that the depth of immersion into the electrolyte solution 360 through the motion board 332 installed in the monitoring / control PC 330 is high speed Computerized. The immersion depth control algorithm of the tungsten wire 340 into the electrolyte solution 360 is obtained through an electrochemical model, and is implemented by real-time monitoring of the current value applied to the tungsten wire 340 by the data processing board 331. At this time, the current value applied to the tungsten wire 340 is obtained by measuring the voltage applied to the reference resistor 311 and dividing it by the resistance value.

Hereinafter, the electrochemical model 110 of tungsten wire etching will be described with reference to FIGS. 4 and 5.

Extraction length z _i from the initial immersion depth L 400 of the tungsten wire 340 into the electrolyte solution 360 in the i th control loop After the motor driving stage 320 is raised by 410, the volume V _{i +1} 430 of the tungsten wire outer surface etched during the next control time interval T is expressed by Equation 1 below.

는 텅스텐 와이어의 초기 반경을 나타낸다.In the above,

Represents the initial radius of the tungsten wire.

In addition, applying Faraday's law, the etched volume V _{i +1} is the current value I _i (A) passed during the control time interval T (= 50 ms), the atomic weight Mw of tungsten (= 183.84 g / mol), and the density of tungsten dw ( = 19400 kg / m ³ ), the number of charges of the ions involved in the reaction | n |, Faraday's constant F (= 96485 C / mol), etc. are represented by the following equation (2).

It can be seen that the charge number | n | of the ions involved in the electrochemical etching reaction of the tungsten wire 340 occurring in the NaOH electrolyte solution 360 is 6 as shown in FIG. 5.

By combining Equations 1 and 2, the following Equation 3 can be obtained.

When the real root of x _{i +1} 420 is obtained, the radius x _{i +1} 420 of the tungsten wire contained in the i + 1 th control loop can be predicted.

By substituting the x _{i +1} value into an arbitrary cross-sectional shape function f, the extraction length zi + 1 in the i + 1 th control loop can be obtained through Equation 4.

z _{i +1} = f (x _{i +1} )

Hereinafter, a method of manufacturing an ultrafine needle electrode according to the present invention will be described in detail with reference to FIG. 6.

First, the tungsten wire 340 is obtained in the electrolyte solution 360 by the desired depth L (600). Thereafter, when the interface unit 333 operates the power supply 310 (610), an electrochemical etching reaction of the tungsten wire 340 as shown in FIG. 5 starts.

First, initial values of the control loops are set (620), and the current flowing through the tungsten wire 340 through the voltage applied to the reference resistor 311 is measured (630). After determining whether it is smaller than the set value of (640), if not smaller, continue the process to predict the real root x _{i + 1} of the equation (3) obtained through the electrochemical model (650). Since x _{i +1} means the radius of the tungsten wire 340 contained in the solution 360 in the i + 1 th control loop, it is substituted into the desired cross-sectional shape z = f (x) in the i + 1 th control loop After determining the extraction length of z _{i + 1} (660), the tungsten wire 340 is extracted out of the electrolyte solution 360 by z _{i +1} -z _i (670). Thereafter, the process proceeds to the next control sequence and repeats steps 630 to 680 until the conditions of 680 and 640 are satisfied. If the condition 640 is satisfied, the power is cut off (690) and the process ends.

The reason why the etching process is terminated when the current value is smaller than the set value as described above (640) is that, as the etching process continues, the tungsten wire gradually approaches the desired shape, as shown in FIG. Although the probe escapes when the wire leaves the surface, processing may continue because the NaOH solution is stuck to the tip of the probe due to tension. Therefore, the current setpoint is set so that the process is terminated when the measured value is smaller than the setpoint, and the current setpoint is any real number determined by the user.

Hereinafter, with reference to FIG. 7, the apparatus which can manufacture N needle electrodes simultaneously using this invention is demonstrated.

As shown in FIG. 7, N-tungsten wires 340 are connected in parallel to the same power supply, and the measured current is divided by the number of mass-produced tungsten wires and applied simultaneously using the electrochemical model and control method. N needle electrodes can be manufactured.

9 and 10 show photographs of ultrafine needle electrodes fabricated according to the present invention. In the case of FIG. 9, the cross-sectional shape function is a polynomial shape. In FIG. 10, the cross-sectional shape function is an ultrafine needle electrode when the cross-sectional shape function is a linear shape.

While the invention has been shown and described with respect to certain preferred embodiments, the invention is not limited to these embodiments, and those of ordinary skill in the art claim the invention as claimed in the appended claims. It includes all the various forms of embodiments that can be implemented without departing from the spirit.

1 is a flow chart showing a method for determining the extraction length of a tungsten wire according to the present invention,

2 is a view showing an ultrafine needle electrode manufacturing apparatus according to the present invention,

3 is a view showing an embodiment of an ultrafine needle electrode manufacturing apparatus according to the present invention,

4 is a view showing the etching amount of the tungsten wire according to the present invention,

5 is a view showing an electrochemical reaction process and reaction equation of the etching of the tungsten wire according to the present invention,

6 is a view showing a method for producing an ultrafine needle electrode according to the present invention;

7 is a view showing an apparatus capable of simultaneously manufacturing a plurality of ultrafine needle electrodes using the present invention;

8 is a view showing an end of etching of a tungsten wire;

9 is a photograph of an ultrafine needle electrode manufactured according to an embodiment of the present invention,

10 is a photograph of an ultrafine needle electrode manufactured according to an embodiment of the present invention.

<Description of Signs of Major Parts of Drawings>

310: DC power supply 311: reference resistor

320: motor drive stage 321: motion driver

330: PC for monitoring / control 331: Data processing board

332 motion board 333 mechanical interface

340: tungsten wire 350: copper electrode

360: electrolyte solution 370: receiving container

400: Initial immersion depth 410: Extraction length from i th control loop

420: radius of tungsten wire contained in i + 1th control loop

430: volume of tungsten wire etched during the control time interval

Claims (13)

(a) obtaining a tungsten wire into the electrolyte solution; (b) applying a voltage by connecting a positive electrode to the tungsten wire and a negative electrode to an electrolyte solution; (c) measuring a current value flowing in the electrolyte solution; (d) predicting the radius of the tungsten wire; (e) calculating the extraction length of the tungsten wire through the radius of the tungsten wire predicted in step (d); (f) moving the tungsten wire by the calculated extraction length; (g) manufacturing an ultrafine needle electrode, comprising repeating steps (c) to (f) until the current value measured in step (c) is greater than or equal to a set value. Way. The method according to claim 1, In the step (d), the radius (x _{i + 1} ) of the tungsten wire is

Where L is the initial depth of immersion of the tungsten wire, z _i is the tungsten wire extraction length in the i-th control loop, T is the control time interval, I _i is the current value passed during the control time interval T, and Mw is the Atomic weight, dw is tungsten density, | n | is the number of charges of ions involved in the reaction, F is Faraday's constant F,

Ultrafine needle electrode manufacturing method, characterized in that the initial tungsten wire radius. The method according to claim 2, The extraction length z _{i + 1} of the tungsten wire of step (e) is determined by the equation z _{i + 1} = f (x _{i + 1} ), and the function f is a cross-sectional shape function defined by the user. Ultra-fine needle electrode manufacturing method characterized in that. The method according to claim 3, The electrolyte solution of step (b) is ultra-fine needle electrode, characterized in that any one of NaOH or KOH. delete delete Tungsten wire part; An electrolyte solution portion connected to the tungsten wire portion to cause an electrochemical reaction with the tungsten wire; A voltage applying part connected to the tungsten wire part and the electrolyte solution part to apply a voltage; A current measuring unit measuring a current value connected between the voltage applying unit and the electrolyte solution unit; A wire control unit connected to the tungsten wire unit to adjust the depth of immersion of the tungsten wire; And a controller connected to the voltage applying unit, the current measuring unit, and the wire adjusting unit to determine their states and control until the current value measured by the current measuring unit is greater than or equal to a set value. The control unit calculates the radius of the tungsten wire (x _{i + 1} )

Where L is the initial depth of immersion of the tungsten wire, z _i is the tungsten wire extraction length in the i-th control loop, T is the control time interval, I _i is the current value passed during the control time interval T, and Mw is the Atomic weight, dw is tungsten density, | n | is the number of charges of ions involved in the reaction, F is Faraday's constant F,

Ultrafine needle electrode manufacturing apparatus, characterized in that the radius of the initial tungsten wire. The method according to claim 7, The controller calculates an extraction length z _{i + 1} of the tungsten wire using the radius x _{i + 1} of the tungsten wire and transmits the extraction length z _{i + 1} to a wire control unit. Ultra-fine needle electrode manufacturing apparatus. The method according to claim 8, The extraction length z _{i +1} of the tungsten wire is determined by the equation z _{i +1} = f (x _{i +1} ), and the function f is a cross-sectional shape function defined by a user. Fine needle electrode manufacturing device. The method according to claim 8, The current measuring unit is configured to include a reference resistor, ultra-fine needle electrode manufacturing apparatus, characterized in that for calculating the current value by dividing the voltage value applied to the reference resistor by the reference resistance value. The method according to claim 8, The ultra-fine needle electrode manufacturing apparatus, including a plurality of tungsten wire portion, it is possible to manufacture a plurality of ultra-fine needle electrode, characterized in that the ultra-fine needle electrode. delete delete

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