CN107515316A - Apparatus and method for etching needle tip of scanning tunnel microscope - Google Patents
Apparatus and method for etching needle tip of scanning tunnel microscope Download PDFInfo
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- CN107515316A CN107515316A CN201610427573.1A CN201610427573A CN107515316A CN 107515316 A CN107515316 A CN 107515316A CN 201610427573 A CN201610427573 A CN 201610427573A CN 107515316 A CN107515316 A CN 107515316A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
- G01Q60/10—STM [Scanning Tunnelling Microscopy] or apparatus therefor, e.g. STM probes
- G01Q60/16—Probes, their manufacture, or their related instrumentation, e.g. holders
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Abstract
The present invention relates to the apparatus and method for etching needle tip of scanning tunnel microscope.A kind of device for being used to etch needle tip of scanning tunnel microscope includes：Circuit module, including circuit unit and data collecting card, circuit unit includes P-type transistor and N-type transistor, the source electrode of P-type transistor receives the supply voltage of the first lead-out terminal from data collecting card, the drain electrode of P-type transistor is connected to the drain electrode of N-type transistor and needle point to be etched, the grid of P-type transistor is connected to the grid of N-type transistor, the source electrode of N-type transistor is connected to earth potential, circuit unit also includes comparator, the positive pole input of comparator receives the reference voltage of the second lead-out terminal from data collecting card, the negative pole input of comparator receives the etch voltage from cathode electrode, the output of comparator is provided to P-type transistor and the grid both N-type transistor；And control module, it is connected to each output of the data collecting card with control data capture card.
Description
Technical field
Present invention relates in general to PSTM field, more specifically it relates to which a kind of be used to etch scanning-tunnelling
The apparatus and method of microscope needle-tip, it can accurately control needle point etching process, so as to manufacture with intended shape
Needle tip of scanning tunnel microscope.
Background technology
PSTM (Scanning Tunneling Microscope, be abbreviated as STM) is a kind of scanning probe
Microscopy instrument, it make use of tunnelling current, and very delicately dependent on the spacing between scanning probe and sample surfaces, this is former
Reason.When scan probe with set height scan sample surfaces when, sample surfaces height change causes probe and sample surfaces
Between spacing change so that the size of tunnelling current also changes therewith.By making scanning probe on sample surfaces
Particles, and record tunnelling current value corresponding to each scanning element, you can obtain the height pattern of sample surfaces.Scan tunnel
Road microscope makes it possible to observe sample surfaces in the high-resolution of atom level, and can also be sharp under low temperature (for example, 4K)
Atom is accurately manipulated with scanning probe, therefore it has in the research fields such as Surface Science, material science, life science
Great meaning and it is widely applied.
Probe is one of most important part of PSTM, size, shape and the chemical identity of probe tip
The resolution ratio of PSTM image and the shape of image are not only influenceed, and also contributes to the electronic state of measure.It is preferable
Needle point should meet to require as follows：1) there is less radius of curvature, be that the tip of needle point only has one in the case of optimal
Atom；2) well-regulated shape, because PSTM imaging requirements needle point has good stability and the electricity exported
Field is symmetrical and regular.Making the common method of STM needle points has grinding, shearing, field to cause electrostatic transmitting, ion milling, electricity
Beamlet deposition and electrochemical corrosion etc..Wherein, the tip end that shearing method obtains is coarse, it is understood that there may be many miniature probes, makes
Into measurement result distortion, and other methods generally require more complicated equipment and technique, therefore most widely used
Method is electrochemical etching method.
Fig. 1 is the schematic diagram of Conventional electrochemical corrosion device 10.As shown in figure 1, by tip point material 12 and cathode material 14
It is inserted into etchant solution 16, tip point material 12 can be exemplified by such as conventional tungsten filament, and cathode material 14 can be such as copper or tantalum,
Etchant solution 16 can be strong base solution, such as NaOH or KOH etc..Tip point material 12 and cathode material 14 are connected respectively to power supply
18 positive pole and negative pole, to be etched.In corrosion process, because the proportion of tungstate ion is larger, it can be along corrosion
Tungsten filament in solution flows downward, so as to protect the end portion of tungsten filament so that the tungsten filament near liquid level is by quickly rotten
Erosion, form recess.With the progress of corrosion, the recess constantly attenuates, final fracture.One of difficult point of electrochemical corrosion course is just
It is the opportunity of deenergization 18 when resting in tungsten filament fracture.If prematurely deenergization, tungsten filament is not etched to also enough
Carefully；If deenergization too late, as shown in figure 1, because etchant solution has concave meniscus, after tungsten filament fracture liquid level still with tungsten
Silk upper part contact, therefore may proceed to corrode needle point so that the needle point formed relatively put down it is blunt, be unsatisfactory for before to pin
The requirement of point.
Therefore, it is necessary to which a kind of apparatus and method for etching needle tip of scanning tunnel microscope, it can be in tip point material
Etching is terminated when being etched fracture in time, so as to obtain the needle tip of scanning tunnel microscope with required shape.
The content of the invention
The present invention provides a kind of apparatus and method for etching needle tip of scanning tunnel microscope, and it can be accurately controlled
Needle point etching process, so as to manufacture the needle tip of scanning tunnel microscope with intended shape.
According to an one exemplary embodiment of the invention, a kind of device for being used to etch needle tip of scanning tunnel microscope may include：
Circuit module (110), including circuit unit (114) and data collecting card (116), the circuit unit (114) include the first p-type
Transistor (220) and the second N-type transistor (230), the source electrode of first P-type transistor (220), which receives, comes from the data
The supply voltage of the first lead-out terminal (AO0) of capture card (116), the drain electrode of first P-type transistor (220) are connected to institute
The drain electrode of the second N-type transistor (230) is stated, and is connected to needle point to be etched (132), first P-type transistor (220)
Grid be connected to the grid of second N-type transistor (230), the source electrode of second N-type transistor (230) is connected to ground
Potential, the circuit unit (114) also include comparator (240), and the positive pole input of the comparator (240) is received from described
Reference voltage (the V of the second lead-out terminal (AO1) of data collecting card (116)ref), the negative pole input of the comparator (240) connects
Receive the etch voltage (V from cathode electrode (134)etch), the output of the comparator (240) is provided to first p-type
Transistor (220) and second N-type transistor (230) grid of the two；And control module (120), it is connected to described
Data collecting card (116) is to control each output of the data collecting card (116).
In certain embodiments, the etch voltage (V during etchingetch) it is more than the reference voltage (Vref), institute
State needle point and be etched etch voltage (V during fractureetch) become less than the reference voltage (Vref)。
In certain embodiments, described device also includes amplifier (210), and the amplifier (210) is configured to will be described
First P-type transistor is supplied to after the supply voltage amplification of the first lead-out terminal (AO0) of data collecting card (116)
(220) source electrode.
In certain embodiments, the etch voltage (V from the cathode electrode (134)etch) it is additionally provided to the number
According to the first input port (AI0) of capture card (116), the etch voltage (Vetch) and the reference voltage (Vref) meet such as
Lower formula：
Wherein,The reference voltage in moment i is represented,The reference voltage at a moment before moment i is represented,The etch voltage at a moment before moment i is represented, β represents filter constant, and Δ t represents time variable, and A represents ginseng
Examine current control percentage.
In certain embodiments, the output current I of the first output port (AO0) of the data collecting card (116)AO0It is full
Sufficient equation below：
Wherein, IsetRepresenting to set electric current, it is the minimum etching electric current in etching process,Represent the erosion in moment i
Carve electric current,The etching electric current at a moment before moment i is represented, σ represents feedback factor.
In certain embodiments, in 1-20 scope, the time-count cycle of the time variable Δ t is the filter constant β
1-1000ms, the setting electric current IsetFor 3-4mA, the feedback factor σ is in 0.001-0.1 scope, the reference current control
Scopes of the percentage A processed in 1%-99%.The filter constant β, the time-count cycle of the time variable Δ t, the setting electricity
Flow Iset, the feedback factor σ and the reference current control percentage A can be set at the control module (120) place.
In certain embodiments, described device also includes D translation platform (130), and the needle point (132) is arranged on described
To be inserted into etching solution on D translation platform (130).
In certain embodiments, described device also includes image-forming module (140), and it is used to be imaged the needle point (132)
To control the needle point to be inserted into the depth in etching solution.
In certain embodiments, the control module 120 is computer installation, and it is connected to the number by USB interface
According to capture card.
It is a kind of to etch needle tip of scanning tunnel microscope using said apparatus according to another one exemplary embodiment of the present invention
Method may include：Needle point and cathode material to be etched are inserted into etching solution；Pass through the data collecting card (116)
First lead-out terminal (AO0) applies electric current I to the needle pointAO0, the electric current IAO0Meet formulaWherein IsetRepresent to set electric current, it is the minimum etching electricity in etching process
Stream,The etching electric current in moment i is represented,The etching electric current at a moment before moment i is represented, σ represents feedback
Coefficient；Monitor the etch voltage (V at the cathode materialetch), and by the reference voltage (Vref) be configured to meet formulaWhereinThe reference voltage in moment i is represented,Represent
The reference voltage at a moment before moment i,The etch voltage at a moment before moment i is represented, β represents filter
Wave constant, Δ t represent time variable, and A represents reference current control percentage；And by the comparator etching electricity
Press (Vetch) and the reference voltage (Vref), as the etch voltage (Vetch) it is more than the reference voltage (Vref) when, the ratio
Export low level compared with device, first P-type transistor conducting, the second N-type transistor cut-off, etching to the needle point after
It is continuous to carry out, as the etch voltage (Vetch) it is less than the reference voltage (Vref) when, the comparator exports high level, described
First P-type transistor ends, the second N-type transistor conducting, to the etch stop of the needle point.
Brief description of the drawings
Fig. 1 is the schematic diagram of Conventional electrochemical corrosion device.
Fig. 2 is the block diagram according to the electrochemical corrosion device of an one exemplary embodiment of the invention.
Fig. 3 is according to an one exemplary embodiment of the invention, the circuit diagram available for the circuit in Fig. 2 device.
Fig. 4 is the photo of the needle point manufactured according to an one exemplary embodiment of the invention.
Embodiment
Fig. 2 is the electrochemical corrosion for being used to etch needle tip of scanning tunnel microscope according to an one exemplary embodiment of the invention
The block diagram of device 100.As shown in Fig. 2 electrochemical corrosion device 100 includes circuit module 110, control module 120, three-dimensional (3D)
Translation stage 130 and imaging device such as CCD 140.
Circuit module 110 includes power subsystem 112, circuit unit 114 and data collecting card (DAQ) unit 116.It is real one
To apply in example, power subsystem 112 can be the ultra-thin switch power supply ZCB20-HD15 that can provide positive and negative 15V direct voltage outputs,
Certainly the invention is not restricted to this, other power supplys, such as power supply commercially available at present can also be used, as long as disclosure satisfy that electricity
Demand of the road module 110 to electric power.Power subsystem 112 can be the miscellaneous part power supply in circuit module 110, be, for example,
Circuit unit 114 and data collecting card unit 116 are powered.
Circuit unit 114 may be coupled to tip point material 132 and cathode electrode 134 to be etched, to control etching process.
As being described further in detail below, circuit unit 114 is operable as being etched the one of fracture in tip point material 132
Moment, stop applying voltage to tip point material 132 and cathode electrode 134, so that it is guaranteed that etching reaction stops.Circuit unit 114
Concrete structure will be further described below in reference to Fig. 3.
Data collecting card 116 can use various commercially available data collecting cards.In an exemplary implementation of the invention
In example, data collecting card 116 can use the USB6008 type data collecting cards that for example National Instruments (NI) sell
(DAQ), it has 8 simulation input (AI) ports, 2 simulation output (AO) ports and a USB interface.The data are adopted
The details of truck can be from network address http://sine.ni.com/nips/cds/view/p/lang/zhs/nid/14604
Obtain, therefore description is not repeated herein.DAQ 116 can gather various signals from circuit unit 114, and in control module
Various signals are provided under 120 control to circuit unit 114 with the operation of control circuit unit 114, this will in further detail below
Ground describes.
Control module 120 is used for the operation of control circuit module 110.Specifically, in certain embodiments, control module
120 can be such as computer, and it is connected to DAQ 116 by USB interface.Computer can be provided with the software of correlation, example
It such as can be used for the NI-DAQmx softwares or LabVIEW softwares of USB6008 data collecting cards, to control DAQ 116 and and then electricity
The operation of road unit 114.For example, user can set DAQ 116 relevant parameter etc. by related software, this will be below
It is described in further detail.In further embodiments, control module 120 can also be the specialized hardware for controlling DAQ 116
Equipment.
For the tip point material 132 of etching, such as tungsten filament, may be mounted on 3D translation stages 130.3D translation stages 130 can
To translate in three dimensions, tip point material 132 is inserted into desired depth in etching solution 136.Cathode material 134, example
Such as copper or tantalum, can be also inserted into etching solution 136.Different etchings can be selected molten according to different tip point materials
Liquid.For example, for conventional tungsten filament needle point, strong base solution, such as NaOH solution and KOH solution can be used.Tip point material 132
The depth that is inserted into etching solution 136, concentration of etching solution 136 etc. can rule of thumb be set.For example, general use
Tungsten filament needle point be inserted into the depth of 1.5mm to 3mm in NaOH solution.
CCD 140 can be amplified imaging to the tip point material 132 being inserted into etching solution 136, so as to accurately
Control needle point is inserted into the depth in solution.For example, in certain embodiments, 3D translation stages 130 have (vertical along Z-direction
Direction) graduated scale, CCD 140 can monitor needle point 132 contact etching solution liquid level when position, write down Z now
Axle scale, then needle point 132 is continued along Z-direction using 3D translation stages 130 to translate predetermined graduated, needle point 132 is inserted
Desired depth under to liquid level.In certain embodiments, 3D translation stages 130 can be by user's manual operations；In other embodiments
In, 3D translation stages 130 can be operated by motor under control of the computer.
Fig. 3 is to can be used for according to the circuit diagram of the circuit 200 of an one exemplary embodiment of the invention, circuit 200 shown in Fig. 2
Circuit unit 114 in circuit module 110.The structure of circuit 200 is described in detail below with reference to Fig. 2 and Fig. 3.
As shown in figure 3, circuit 200 includes the first transistor 220 and second transistor 230 being serially connected, it has
There is reciprocal conduction type.For example, the first transistor 220 can be the PMOS turned under low level, its source S connects
Supply voltage is connected to, its drain D is connected to second transistor；Second transistor 230 can be the NMOS turned under high level
Pipe, its drain D are connected to the first transistor 220, and its source S is connected to earth potential.The grid G of the first transistor 220 can connect
The grid G of second transistor 230 is connected to, so that under same level, one in the first transistor 220 and second transistor 230
Individual conducting, another cut-off.In certain embodiments, for example, the first transistor 220 can use commercially available IRFD9210
Type PMOS, second transistor 230 can use commercially available IRFD213 type NMOS tubes, but the invention is not restricted to this, also
Other kinds of transistor can be used.
The source electrode of the first transistor 220 can receive supply voltage, such as receive DAQ 116 analog output
AO0 output.For example, USB6008 types DAQ analog output AO0 can provide+5V voltage output, the voltage can be through computing
Amplifier 210 is amplified to required voltage or current amplitude, is then supplied to the source electrode of the first transistor 220.Generally, etch
The voltage of needle point is enough in 12V or so, therefore operational amplifier 210 can carry out 3 times or so of amplification.
The node that needle point 132 may be coupled between the drain electrode of the first transistor 220 and the drain electrode of second transistor 230
222.So, when the first transistor 220 turns on, and second transistor 230 ends, etch voltage is applied to needle point 132, etching
Carry out；When the first transistor 220 ends, and second transistor 230 turns on, the voltage on needle point 132 is substantially equal to earth potential, loses
Carve and stop.Cathode electrode 134 can be connected to earth potential by resistance R1.
The inventors discovered that when needle point 132 is etched fracture, the resistance between needle point and etching solution can instantaneously drastically
Increase, such as increased sharply from about 1k Ω to about 30k Ω, concrete numerical value can because of tip point material, etching solution composition and concentration and
It is different.It is contemplated that triggering the stopping of etching reaction using the instantaneous increase of the resistance, stop in needle point fracture moment
Only chemical etching, so as to obtain the etching needle point with intended shape.
With continued reference to Fig. 3, the node 224 between cathode electrode 134 and resistance R1 may be coupled to the negative pole of comparator 240
Input, and it is connected to a DAQ 116 simulation input port AI0.The voltage of node 224 can be designated as etch voltage
Vetch, and can be by etch voltage VetchFurther obtain etching electric current Ietch=Vetch/R1。
Comparator 240 can use such as LM306 types comparator, or the comparator of other models.The positive pole of comparator 240 is defeated
The reference voltage V of a simulation output port AO1 from DAQ 116 can be received by entering endref.The output of comparator 240 can be with chain
The first transistor 220 and the grid both second transistor 230 are connected to, for controlling the conducting of the two transistors and cutting
Only.
As etch voltage VetchMore than reference voltage VrefWhen, comparator 240 exports low level, now the first transistor 220
Conducting, second transistor 230 end, and the supply voltage of the simulation output port AO0 from DAQ 116 is through the first transistor 220
Needle point 132 is provided to, etching continues.In the moment that needle point 132 is broken, etch voltage VetchIt is reduced to close to zero,
And it is less than reference voltage Vref.Now, comparator 240 exports high level, and the first transistor 220 ends, second transistor 230
Turn on, the voltage on needle point 132 stops close to earth potential, chemical etching.When initial, reference voltage V can be maderefWink
Between be negative value, i.e., on DAQ 116 AO1 ports provide one be negative value initial signal, to enable reaction to carry out.It is logical
Cross and etch voltage V is suitably setetchWith reference voltage Vref, you can realize above-mentioned etching process.As it was previously stated, it can control
DAQ 116 is controlled suitably to set etch voltage V at molding block 120etchWith reference voltage Vref。
Present inventors have further discovered that if etch voltage VetchSet larger, in the fracture of needle point 132 in a flash,
Needle point may be still etched excessively, so as to influence resulting needlepoint form；If etch voltage VetchSet smaller, although
The over etching for being broken moment reduces, but the time for needing to grow very much completes etching process, and on the other hand, with reference to electricity
Press VrefIt must be provided with very low (between etch voltage and zero), and etch voltage VetchWith reference voltage VrefBetween
Interval becomes very little.Now, due to possible from the etched solution 136 of needle point 132 to the resistance of cathode electrode 134 in etching process
Fluctuation occurs, it is thus possible to etch voltage V occursetchLess than reference voltage VrefMoment, cause etching process unexpected eventually
Only.
Therefore, in some embodiments of the invention, etching electric current is arranged to taper into, so as to be broken in needle point 132
At the time of near, etching electric current has become smaller, therefore can reduce the influence of over etching, it is ensured that gained needle point has the phase
The shape of prestige.Specifically, DAQ 116 simulation output port AO0 output current I can be madeAO0Meet following formula 1：
Wherein, IsetRepresenting to set electric current, it is the minimum etching electric current in etching process,Represent the erosion in moment i
Carve electric current,Represent the etching electric current at a moment before moment i.As it was previously stated, etching electric current IetchCan be in DAQ
116 be connected at the simulation input port AI0 of cathode electrode 134 obtains.σ represents feedback factor.IsetIt can controlled with σ
Set at module 120, for example, setting electric current IsetIt is generally located on 3mA to 6mA scope, preferably 3mA to 4mA.Feedback factor σ
It is generally located on 0.001 to 0.1 scope.When etching reaction initially starts, the voltage (and then electric current) on the AO0 of port is larger,
For example, 5V, it is supplied to needle point 132 after the amplification of amplifier 210, so as to produce larger etching electric current Ietch, etching reaction
It is quick to carry out.When etching reaction continues, according to above-mentioned formula 1, electric current I is setsetWith etching electric currentBetween difference
It is worth for negative value so that the electric current I provided at the AO0 of portAO0Reduce, and then etch electric current IetchIt is gradually lowered.It is appreciated that
Feedback factor σ represents current reduction speed, and when feedback factor σ is bigger, current reduction is faster.Finally, as etching electric current Ietch
It is reduced to setting electric current IsetWhen equal, for example, 3mA, the item in above-mentioned formula 1 Vanishing so that electric current
IAO0No longer decline.Even in some moment, IetchDrop below and electric current I is setset, due to the item in above-mentioned formula 1It is changed on the occasion of so that electric current IAO0Rise, it is final to etch electric current IetchStabilization is with setting electric current IsetIt is equal.
Although described above is by monitor current to control reaction speed, can also be controlled by monitoring voltage
Reaction speed, its principle is identical with above description, simply also needs to consider voltage gain and the voltage drop introduced in circuit, because
Here repeat no more.As can be seen that from simply and easily for angle, by monitor current come to control reaction speed be preferred
's.
As it was previously stated, it is normally carried out in order to ensure etching reaction, it is desirable to reference voltage VrefLess than etch voltage Vetch；
On the other hand, in order to ensure etching reaction can terminate in time, it is desirable to reference voltage VrefEtching when being broken more than needle point 132
Voltage Vetch.In some embodiments of the invention, reference voltage VrefWith etch voltage VetchMeet following formula 2：
Wherein, β is filter constant, and Δ t is time variable, and A is reference current control percentage.According to formula 2, when etching electricity
Press VetchAt the time of diminishing, Δ t is zero, can be obtainedIt can be seen that the value of reference voltage still keeps constant, now Vetch
Reference voltage V may be become less thanref, etching reaction termination.If etch voltage VetchIt is not less than reference voltage V after diminishingref
(such as situation about being described above with reference to formula 1), then Δ t accumulation over time, can obtainI.e.
The etch voltage that reference voltage becomes is multiplied by a percentage, so as to which reference voltage diminishes and diminished also with etch voltage, it is ensured that
Etching reaction continues.Filter constant β, reference current control percentage A and time variable Δ t time-count cycle can be with
Set at control module 120, wherein filter constant β's may range from such as 1-20, and percentage A's may range from for example
1% to 99%, Δ t time-count cycle can be 1-1000 milliseconds.
In superincumbent formula 2, by setting filter constant β so that reference voltage VrefIn etch voltage VetchDecline
Moment does not decline immediately, but gradually decreases to corresponding magnitude of voltage, so as to serve the effect of filtering, reduces with reference to electricity
Press VrefFluctuation.On the other hand, according to formula 2, reference voltage VrefAlso with etch voltage VetchDecline and decline, it is ensured that
Reference voltage V in etching processrefLess than etch voltage VetchSo that etching can be normally carried out.
Described above is makes reference voltage VrefIt is etch voltage VetchA percentage situation, i.e. Vref=Vetch× A,
In further embodiments, the situation of difference, i.e. V can also be usedref=Vetch- Δ V, now reference voltage VrefWith etching electricity
Press VetchMeet following formula 3：
Wherein Δ V represents reference voltage VrefWith etch voltage VetchBetween difference constant, it can for example control mould
Set at block 120, and its value can be because of system design parameter (such as etching electric current, resistance R1 etc.) and in larger scope
Interior change.Other aspects of difference situation are identical with percentage situation described above, and here is omitted.
The step of describing below using the device of the present invention to etch the method for needle point.It is possible, firstly, to use strong base solution
NaOH/KOH (1.5mol-3mol) removes the surface oxide layer of such as tungsten filament (0.5mm diameters) of tip point material 132, utilizes CCD
140 and lifting platform 130 needle point 132 is accurately inserted into the following desired depth of liquid level, such as 1.5mm-3mm, tungsten filament 132 with it is cloudy
DC voltage is added between pole electrode 134.
It is it is then possible to default each at control module 120, such as in the LabVIEW operation interfaces of computer operation
Operating parameter.The parameter set at control module 120 can include but is not limited to such as initial time electric current (or voltage), set
Put electric current Iset, feedback factor σ, filter constant β, reference current control percentage A, time cycle Δ t, etc..Then, run
For control program to start to etch, etching process can be substantially as explained above with as the descriptions of Fig. 2 and 3.When the etch is completed, such as
It is preceding described, the voltage applied to needle point 132 can be disconnected automatically, and system can sound the alarm.Operator can immediately by
Needle point is raised to more than liquid level, and tungsten filament is cut in appropriate length with wire nipper.Next, the needle point of completion is rushed with deionized water
Wash, and be saved in suitable position.
Fig. 4 shows to etch the obtained microphoto of tungsten filament needle point using apparatus and method of the present invention.From Fig. 4 photo
As can be seen that can be obtained with good profile using apparatus and method of the present invention, and there is good pointed shape
Needle point.
The principle of the present invention is described above with reference to one exemplary embodiment, and is given in these one exemplary embodiments
Many details, it will be appreciated, however, by one skilled in the art that the invention is not restricted to these details.But those skilled in the art can
It is of the invention to implement in the case of without these details, or the present invention is implemented using the details substituted, these embodiment party
Formula should all be fallen within the scope of the present invention.The scope of the present invention is defined by the independent claims.
Claims (10)
1. a kind of device for being used to etch needle tip of scanning tunnel microscope, including：
Circuit module (110), including circuit unit (114) and data collecting card (116), the circuit unit (114) include the
One P-type transistor (220) and the second N-type transistor (230), the source electrode of first P-type transistor (220) are received from described
The supply voltage of the first lead-out terminal (AO0) of data collecting card (116), the drain electrode connection of first P-type transistor (220)
To the drain electrode of second N-type transistor (230), and needle point to be etched (132) is connected to, first P-type transistor
(220) grid is connected to the grid of second N-type transistor (230), and the source electrode of second N-type transistor (230) connects
Earth potential is connected to, the circuit unit (114) also includes comparator (240), and the positive pole input of the comparator (240) receives
From the reference voltage (V of the second lead-out terminal (AO1) of the data collecting card (116)ref), the negative pole of the comparator (240)
Input receives the etch voltage (V from cathode electrode (134)etch), the output of the comparator (240) is provided to described
One P-type transistor (220) and second N-type transistor (230) grid of the two；And
Control module (120), it is connected to the data collecting card (116) to control each of the data collecting card (116)
Output.
2. device as claimed in claim 1, wherein, the etch voltage (V during etchingetch) it is more than the reference voltage
(Vref), the etch voltage (V when the needle point is etched fractureetch) become less than the reference voltage (Vref)。
3. device as claimed in claim 1, in addition to amplifier (210), the amplifier (210) is configured to the data
First P-type transistor (220) is supplied to after the supply voltage amplification of the first lead-out terminal (AO0) of capture card (116)
Source electrode.
4. device as claimed in claim 1, wherein, the etch voltage (V from the cathode electrode (134)etch) be further provided with
To the first input port (AI0) of the data collecting card (116), the etch voltage (Vetch) and the reference voltage
(Vref) meet equation below：
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<mi>i</mi>
<mo>-</mo>
<mn>1</mn>
</mrow>
</msubsup>
<mo>,</mo>
</mrow>
Wherein,The reference voltage in moment i is represented,The reference voltage at a moment before moment i is represented,
The etch voltage at a moment before moment i is represented, β represents filter constant, and Δ t represents time variable, and A is represented with reference to electricity
Flow control percentage.
5. device as claimed in claim 4, wherein, the output of the first output port (AO0) of the data collecting card (116)
Electric current IAO0Meet equation below：
<mrow>
<msub>
<mi>I</mi>
<mrow>
<mi>A</mi>
<mi>O</mi>
<mn>0</mn>
</mrow>
</msub>
<mo>=</mo>
<mrow>
<mo>(</mo>
<msub>
<mi>I</mi>
<mrow>
<mi>s</mi>
<mi>e</mi>
<mi>t</mi>
</mrow>
</msub>
<mo>-</mo>
<msubsup>
<mi>I</mi>
<mrow>
<mi>e</mi>
<mi>t</mi>
<mi>c</mi>
<mi>h</mi>
</mrow>
<mi>i</mi>
</msubsup>
<mo>)</mo>
</mrow>
<mo>&times;</mo>
<mi>&sigma;</mi>
<mo>+</mo>
<msubsup>
<mi>I</mi>
<mrow>
<mi>e</mi>
<mi>t</mi>
<mi>c</mi>
<mi>h</mi>
</mrow>
<mrow>
<mi>i</mi>
<mo>-</mo>
<mn>1</mn>
</mrow>
</msubsup>
<mo>,</mo>
</mrow>
Wherein, IsetRepresenting to set electric current, it is the minimum etching electric current in etching process,Represent the etching electricity in moment i
Stream,The etching electric current at a moment before moment i is represented, σ represents feedback factor.
6. device as claimed in claim 5, wherein, the filter constant β 1-20 scope, the time variable Δ t's
Time-count cycle is 1-1000ms, the setting electric current IsetFor 3-4mA, the feedback factor σ 0.001-0.1 scope, it is described
Reference current controls percentage A in 1%-99% scope, and
Wherein, the filter constant β, the time-count cycle of the time variable Δ t, the setting electric current Iset, the feedback factor
σ and reference current control percentage A can be set at the control module (120) place.
7. device as claimed in claim 1, in addition to D translation platform (130), the needle point (132) is arranged on the three-dimensional
To be inserted into etching solution on translation stage (130).
8. device as claimed in claim 1, in addition to image-forming module (140), it is used to be imaged to control the needle point (132)
Make the depth that the needle point is inserted into etching solution.
9. device as claimed in claim 1, wherein, the control module 120 is computer installation, and it is connected by USB interface
It is connected to the data collecting card.
10. the device of usage right requirement 1 a kind of etches the method for needle tip of scanning tunnel microscope, methods described includes：
Needle point and cathode material to be etched are inserted into etching solution；
Electric current I is applied to the needle point by the first lead-out terminal (AO0) of the data collecting card (116)AO0, the electric current
IAO0Meet formulaWherein IsetRepresent to set electric current, it is in etching process
Minimum etching electric current,The etching electric current in moment i is represented,The etching electric current at a moment before moment i is represented,
σ represents feedback factor；
Monitor the etch voltage (V at the cathode materialetch), and by the reference voltage (Vref) be configured to meet formulaWhereinThe reference voltage in moment i is represented,Represent
The reference voltage at a moment before moment i,The etch voltage at a moment before moment i is represented, β represents filter
Wave constant, Δ t represent time variable, and A represents reference current control percentage；And
By the comparator etch voltage (Vetch) and the reference voltage (Vref), as the etch voltage (Vetch)
More than the reference voltage (Vref) when, the comparator exports low level, the first P-type transistor conducting, the 2nd N
Transistor npn npn ends, and the etching to the needle point continues, as the etch voltage (Vetch) it is less than the reference voltage
(Vref) when, the comparator exports high level, the first P-type transistor cut-off, the second N-type transistor conducting, to institute
State the etch stop of needle point.
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Cited By (2)
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| CN108196093A (en) * | 2017-12-26 | 2018-06-22 | 北京阳光凯特科技有限公司 | A kind of auxiliary device of preparation for metallic nano detecting probe |
| TWI782767B (en) * | 2021-10-27 | 2022-11-01 | 汎銓科技股份有限公司 | A methof of mass-producing nanoprobes |
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| CN201017691Y (en) * | 2007-03-06 | 2008-02-06 | 南开大学 | Metallic nano detecting probe preparing circuit |
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| CN107515316B (en) | 2019-09-03 |
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