JP3671687B2 - Ultra-short pulse high voltage generator for scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrashort pulse high voltage generator for use in a scanning probe microscope, and more specifically, in addition to the original function of observing a sample surface at an atomic level in a scanning probe microscope, for each surface atom. To detect Auger electrons and characteristic X-rays by irradiating sample surface atoms with high kinetic energy electrons from a probe so that three-dimensional nuclear coordinate determination, elemental analysis, and chemical bonding state analysis can be performed. The present invention relates to an ultrashort pulse high voltage generator.
[0002]
[Prior art]
Among the conventional elemental analysis and chemical bonding state analysis techniques, the most capable of analyzing a very small area and extreme surface layer is scanning Auger electron spectroscopy, but even the latest techniques measure diameters of 10 nm and depths of several nm. It is a region, and it is impossible to measure each surface atom.
[0003]
On the other hand, a scanning probe microscope (SPM) such as a scanning tunneling microscope (STM) or an atomic force microscope (AFM) has real space resolution on the atomic order, but interpretation of the measurement results is not always easy. A scanning tunneling microscope applies a bias voltage between a probe and a sample arranged at an interval of about 10 mm, and controls the distance between the probe and the sample (Z direction) with a piezo element to generate a tunnel current flowing between the two. An atomic image of the sample surface can be drawn from the control voltage of the Z-direction piezo element by scanning the probe along the unevenness of the sample surface (XY plane) while maintaining constant. In addition, the scanning atomic force microscope is such that the distance between the probe provided at the tip of the “lever” with a small spring constant and the sample is such that an atomic force (repulsive force) acts between them (2 to 3 mm). By scanning the probe along the surface of the sample, the "lever" is deformed according to the surface of the sample, and this atomic order deformation is measured by STM, laser light reflection measurement, or optical interference measurement. The atomic image of the sample surface can be drawn by measuring by the method.
[0004]
As for the chemical properties of semiconductors and metals, the characteristics (atomic structure, electronic state, etc.) at the surface rather than the bulk play an important role. Currently, many researchers are working theoretically and experimentally to elucidate surface characteristics with spatial resolution at the atomic level. Among them, research using STM has been successful in measuring the surface geometrical structure with atomic spatial resolution. However, since elemental analysis of surface atoms is not possible with STM, the surface structure cannot be strictly understood from the STM image when there are heterogeneous atoms on the surface.
[0005]
Therefore, the present inventor disclosed in Japanese Patent Application Laid-Open No. 8-178934 (elemental analysis method using a scanning probe microscope) during measurement of a sample surface using a scanning probe microscope, particularly a scanning tunnel microscope (STM). At any point on the surface, a sample surface atom is irradiated with electrons of high kinetic energy (50 eV or more) from the probe, and Auger electrons and characteristic X-rays are generated from the atom, thereby causing individual atoms on the sample surface to A method for elemental analysis has been proposed. As a result, the atomic structure and local electronic state of the sample surface can be measured simultaneously, and detailed surface analysis becomes possible. Hereinafter, in particular, a method for detecting Auger electrons is defined as “STM-AES”, and a method for detecting characteristic X-rays is defined as “STM-XMA”.
[0006]
When performing STM-AES and STM-XMA, in order to generate Auger electrons and characteristic X-rays from sample atoms, it is necessary to apply high voltage to the probe and irradiate sample surface atoms with electrons of high kinetic energy. However, for this purpose, the present inventors used a coaxial cable to generate a short pulse high voltage generated by a pulse power supply in Japanese Patent Laid-Open No. 9-178759 (method of applying an ultrashort pulse high voltage in a scanning probe microscope). And a method of applying a short pulse high voltage to the probe or the sample, assuming that the probe and the sample are open ends (impedance is infinite).
[0007]
[Problems to be solved by the invention]
However, there are two major problems in actually applying a high voltage to the probe. First of all, under the conditions for performing STM-AES and STM-XMA, when a high voltage is applied to the probe, the distance between the probe and the sample is very close to about 1 nm.⁷A strong electric field of V / mm or more is applied, whereby electric field evaporation occurs on the sample surface and the probe surface. Therefore, in order to prevent this influence, it is necessary to make the high voltage applied to the probe into a pulse shape and make the pulse width 1 ns or less. Second, when a pulse voltage is applied, the charge flows in a very small area on the sample surface just below the probe, so that the sample surface melts and evaporates due to Joule heat. For this, it is necessary to limit the amount of charge (number of electrons) irradiated on the sample surface by the pulse, and to reduce the current when applying the pulse voltage as much as possible.
[0008]
Therefore, in view of the above-described situation, the present invention intends to solve the problem that high kinetic energy (50 eV or more) sufficient to generate Auger electrons and characteristic X-rays when performing STM-AES and STM-XMA. In order to irradiate sample atoms with electrons and prevent structural changes on the sample surface due to field evaporation or Joule heat, a high voltage ultrashort pulse of 1 ns or less with controlled charge can be applied to the probe. An object of the present invention is to provide an ultrashort pulse high voltage generator for use in a scanning probe microscope.
[0009]
[Means for Solving the Problems]
  In order to solve the above-described problems, the present invention provides an ultrashort pulse high voltage generator for applying an ultrashort pulse high voltage between a probe of a scanning probe microscope and a sample, the probe and the electric ConnectedStructure in which a first insulator is sandwiched between a probe fixing electrode plate and a first metal electrode plateMicro capacityHigh voltage charge / discharge capacity C ₀ The probe andUnitedProvided inA high-voltage ultrashort pulse power supply unit equipped with a high-voltage charge / discharge circuit capable of switching between positive and negative with impedance matching with the main coaxial cable, and having a central conductor for applying a high voltage at the end of the main coaxial cable The high voltage charge / discharge capacity C is adjusted by adding a capacitance or an inductance for impedance matching while being connected to the first metal plate. ₀ The first metal electrode plate constitutingThe positive charge accumulated in the battery is discharged and the negative charge is applied to the probe, or the negative charge accumulated in the opposite direction is discharged and the positive charge is applied to the probe. An ultrashort pulse high-voltage generator used for a scanning probe microscope using the micro charge was constructed.
[0011]
  Here, a high voltage charge / discharge capacity C for applying a high voltage to the probe between the probe and an XYZ piezo scanner for a scanning probe microscope for driving the probe as the capacitor unit.₀Impedance matching capacitance C for impedance matching between main cable and main coaxial cable_mAndIntegrallyA high-voltage charge / discharge capacity C for applying a high voltage to the probe with a built-in or XYZ piezo scanner for a scanning probe microscope on the sample side₀Impedance matching capacitance C for impedance matching between main cable and main coaxial cable_mAndIntegrallyHigh voltage charge / discharge capacity C₀IsProbe fixing plateAnd the first metal electrode plate with a first insulator sandwiched between them and an impedance matching capacitor C_mIs formed by sandwiching a second insulator between the first metal electrode plate and the second metal electrode plate, and connects the central conductor of the main coaxial cable to the first metal electrode plate and the outer conductor of the main coaxial cable as the first conductor. A structure connected to a two-metal electrode plate was adopted.
[0012]
Also, a resistance R that is impedance matched with the characteristic impedance of the main coaxial cable._mCapacity C through₀By discharging the charge accumulated in the electrode, the reflected wave can be absorbed and removed by the resistance, so that the pulse waveform applied to the probe is not disturbed.
[0013]
In addition, it is highly accurate positioning of the probe by the XYZ piezo scanner for a scanning probe microscope that the metal electrode plate and the insulator constituting the capacitive part are made of a material having no piezoelectric effect and high rigidity. It is necessary for.
[0014]
Here, “high voltage” in the present invention means that it is sufficiently higher than a bias voltage of several volts in a normal scanning tunneling microscope, and the voltage is about several tens of volts to several tens of kV, and this voltage is It is selected according to the kind of element constituting the sample or the probe or the energy level of the excited electron orbit. The “ultra-short pulse” in the present invention means that a high voltage can be applied only for a short time that does not cause the field to evaporate, and that a large amount of electrons are incident on the sample surface in a minute time. This means a pulse with a very short time width for limiting the amount of electrons incident at one time to prevent sample melting, and the pulse width is 1 ns or less. Further, in the present invention, the scanning probe microscope means a microscope having real spatial resolution of atomic order derived from a scanning tunneling microscope such as a so-called scanning tunneling microscope, an atomic force microscope, and a scanning near-field optical microscope. .
[0015]
In the present invention, an ultrashort pulse high voltage is applied between the probe and the sample, and the inner shell electrons of the sample atom (in some cases, the valence distributed spherically around the nucleus is generated by the high kinetic energy electrons emitted from the probe. It may be an electron). Then, when an electron whose energy level is higher than that of the core electron falls into the vacancies generated by the excitation of the core electron, photon or Auger electron is emitted, and energy analysis and counting analysis of the photon or Auger electron are performed. In other words, by analyzing information such as inner-shell electrons distributed spherically around the nucleus for each atom, determination of three-dimensional nuclear coordinates for each surface atom, elemental analysis, chemical bond state analysis Can be done.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, the details of the present invention will be further described based on the embodiments shown in the accompanying drawings. FIG. 1 is a schematic view showing an embodiment of an apparatus for applying a high voltage ultrashort pulse to an STM probe according to the present invention, FIG. 2 is an equivalent circuit diagram thereof, and reference numeral 1 in the figure denotes an STM body. Reference numeral 2 denotes a high-voltage ultrashort pulse power supply unit.
[0017]
The STM body 1 has a probe 4 and a sample 5 arranged in an ultra-high vacuum chamber 3 with a very narrow interval, and the probe 4 scans the surface of the sample 5 by an STM XYZ piezo scanner 6. It has come to be. Here, the probe 4 may be fixed, the STM XYZ piezo scanner 6 may be provided on the sample 5 side, and the sample 5 may be moved. Further, a bias voltage can be applied to the probe 4 from a power supply 7 for STM measurement via a switch 8. The tunnel current flowing through the sample 5 is the resistance R_F1, Resistance R_F2, Capacitor C_FThe STM current amplifier 10 is used to amplify and measure through the low-pass filter 9 and the STM measurement is performed by feeding back the value to the STM XYZ piezo scanner 6. For STM-XMA, since photons are detected, the measurement atmosphere is not limited to the ultra-high vacuum and can be applied to the atmosphere, so the ultra-high vacuum chamber 3 is not particularly required.
[0018]
The high-voltage ultrashort pulse power supply unit 2 connects a high-voltage power supply 12 to a central conductor 11A of a high-voltage supply cable 11 and grounds an external conductor 11B. A coaxial relay switch 13 is connected to the high-voltage supply cable 11. The main coaxial cable 14 and the branch coaxial cable 15 are connected via a cable, and a resistance R is connected to the central conductor 15A of the branch coaxial cable 15._mAre connected in series and grounded. Here, the coaxial relay switch 13 and the resistor R_mThe branch coaxial cable 15 having impedance is impedance matched with the main coaxial cable 14. Note that the terminal a of the coaxial relay switch 13 connects the high-voltage supply cable 11 and the main coaxial cable 14 to form a charging circuit, and the terminal b disconnects the load side from the high-voltage power source 12 and the main coaxial cable. 14 and the branch coaxial cable 15 are made conductive, and the resistance R_mA discharge circuit that discharges through is configured.
[0019]
A minute capacitor 16 is formed in the very vicinity of the probe 4, and a high voltage is applied to one electrode of the capacitor 16 from the high-voltage ultrashort pulse power supply unit 2 via the main coaxial cable 14. The coaxial relay switch 13 and the branch coaxial cable 15 (resistor R) impedance-matched with the positive or negative charge accumulated by the application._m) Is rapidly discharged, and the positive and negative charges left on the other electrode of the capacitor portion 16 are supplied to the probe 4 to generate a high-voltage ultrashort pulse on the probe 4. The sample 5 or the probe 4 is irradiated with electrons of kinetic energy.
[0020]
Specifically, in FIG. 1, the capacitor portion 16 is formed by laminating a metal electrode plate and an insulator between the probe 4 and the STM XYZ piezo scanner 6. That is, the high voltage charge / discharge capacity C is obtained by sandwiching the first insulator 18 between the STM probe 4 and the first metal electrode plate 17.₀And an impedance matching capacitor C with a second insulator 20 sandwiched between the first metal electrode plate 17 and the second metal electrode plate 19 provided on the STM XYZ piezo scanner 6 side._mConfigure. The central conductor 14A at the tip of the main coaxial cable 14 is connected to the first metal electrode plate 17, and the outer conductor 14B is connected to the second metal electrode plate 19. Here, the central conductor 14A exposed at the tip of the main coaxial cable 14 inevitably has an inductance L._mHowever, in the ultra-short pulse, this part is made as short as possible and the inductance L_mIt is desirable to reduce the value.
[0021]
First, as shown in FIG. 3, by connecting the coaxial relay switch 13 to a terminal a, a high voltage (V) of several tens of volts to several tens of kV is applied to the first metal electrode plate 17 via the main coaxial cable 14.₀) Is applied. In this state, when the switch 8 in the vicinity of the probe is turned ON, the high voltage charge / discharge capacity C of the capacitor unit 16 is set.₀V₀Is applied, but the potential of the probe 4 itself is the voltage V of the power supply 7 for STM measurement._sTherefore, the STM measurement is made possible by measuring the tunnel current with the STM current amplifier 10 and feeding back the value to the STM XYZ piezo scanner 6. Normally, when performing STM measurement, the switch 8 is turned on and the coaxial relay switch 13 is connected to the terminal a as described above. FIG. 3 schematically shows the state of the high voltage V V generated by the high voltage power supply 12.₀Depending on each high voltage charge / discharge capacity C₀, Impedance matching capacitance C_mNegative charges (electrons) and positive charges are stored in a steady state without moving. Here, the high-voltage power supply 12 can be switched between positive and negative, and when irradiating electrons from the probe 4 to the sample 5 in normal STM-AES or STM-XMA, a positive high voltage is charged and discharged at a high voltage. Capacity C₀Apply to. On the contrary, when it is necessary to irradiate the probe 4 with electrons from the sample 5, the high voltage power supply 12 applies a negative high voltage to the high voltage charge / discharge capacity C₀Is applied.
[0022]
Next, a procedure for applying an ultrashort pulse high voltage to the probe 4 in order to perform STM-AES and STM-XMA will be described. While performing the STM measurement, or temporarily interrupting the STM measurement, the probe 4 is placed on the STM-AES or STM-XMA on any point on the surface of the sample 5 and close to the tunnel region. Use the XYZ piezo scanner 6 for movement. Therefore, as shown in FIG. 4, when the switch 8 near the probe is turned OFF and the coaxial relay switch 13 impedance-matched with the main coaxial cable 14 is connected to the terminal b, the main coaxial cable 14 is connected to the terminal b. R with impedance matching_mAre connected, the electric charge stored in the central conductor 14A of the main coaxial cable 14 is resistance R_mThe potential of the central conductor 14A of the main coaxial cable 14 quickly reaches the ground potential. High voltage charge / discharge capacity C at this time₀The movement of the charge at the electrodes of the high voltage charge and discharge capacity C₀The positive charge stored on the first metal electrode plate 17 side is transmitted through the main coaxial cable 14 and the resistance R_mThe negative charge (electrons) stored on the opposite probe 4 side must be moved from the probe 4 to the sample 5 because the switch 8 is OFF. At this time, electrons having high kinetic energy are irradiated on the surface of the sample 5 in a pulsed manner.
[0023]
In this case, since the negative charge (electrons) stored in the probe 4 is only irradiated from the probe 4 to the surface of the sample 5, a high voltage (V₀), The potential energy (C₀V₀ ²/ 2) can be converted into kinetic energy with a minimum loss and irradiated onto the surface of the sample 5, and a pulse can be efficiently applied with the minimum necessary energy so as not to damage the surface of the sample 5. Of course, when a pulse is applied, a part of the energy of the applied pulse is transmitted as a reflected wave through the main coaxial cable 14 due to the impedance between the probe 4 and the sample 5, but the coaxial relay switch 13 is connected to the terminal b. Therefore, the reflected wave has a resistance R with impedance matching._mIs absorbed and removed by the signal and transmitted to the probe 4 again, and the pulse waveform is not disturbed. In addition, the pulse irradiated to the sample 5 side has resistance R_F1, Resistance R_F2, Capacitor C_FTherefore, the STM current amplifier 10 is not overloaded.
[0024]
After applying a pulse from the probe 4 to the sample 5 as described above, when the switch 8 is turned ON and the coaxial relay switch 13 is reconnected to the terminal a, STM measurement can be performed again, and the high voltage charge / discharge capacity C₀High voltage V₀The charge corresponding to is accumulated. Repeating the above cycle, linking the results of STM measurement with the computer processing at the same time, the STM image and the results of elemental analysis of the sample 5 surface by STM-AES or STM-XMA can be obtained on the same surface Is possible.
[0025]
Next, FIG. 5 shows a structural design example around the probe 4 and the STM XYZ piezo scanner 6. In the above-described process, the pulse waveform applied to the probe 4 is ideally determined by the impedance value between the probe 4 and the sample 5, but the stray capacitance generated when an actual structure is manufactured. And inductance L in the central conductor 14A portion of the main coaxial cable 14_mCan no longer be ignored. In order to apply an ultrashort pulse, it is necessary to take into account those unintended circuit components and to perform impedance matching and design so that the structure itself becomes a circuit.
[0026]
In FIG. 5, the probe 4 is designed to be removable by a screw 21, and the first metal electrode plate is disposed between the probe fixing electrode plate 22 provided with the screw 21 and the first metal electrode plate 17. By sandwiching the first insulator 18 and the second insulator 20 between the first metal plate 19 and the second metal electrode plate 19, high voltage charge / discharge capacitance C₀, Impedance matching capacitance C_mConfigure. As the material of the insulator, a material having no piezoelectric effect such as alumina and having high rigidity is used. The capacitive portion 16 is integrally fixed to the drive surface of the STM XYZ piezo scanner 6 and the probe 4 is attached to the probe fixing electrode plate 22. Further, when the high-voltage main coaxial cable 14 is connected, the inductance formed by the center conductor 14A and the outer conductor 14B being exposed is represented by L._mAs described above. This inductance L_mSince it varies depending on the type of the main coaxial cable 14 and the position of the cable with respect to the ground, it must be measured in advance by experiments. High voltage charge / discharge capacity C₀Of the applied pulse energy and the high voltage V₀The area and thickness of the first insulator 18 are determined by the withstand voltage with respect to the impedance matching capacitance C_mIs Z = √ [L, where Z is the characteristic impedance of the high-voltage main coaxial cable 14._m/ (C₀+ C_m)] To satisfy the above, and design the vicinity of the probe 4. As a result, all stray capacitance generated when connecting to the main coaxial cable 14 is C._mC is smaller than_mAnd inductance L_mIs the high voltage charge / discharge capacity C₀And impedance matching capacitance C_mTogether with the characteristic impedance Z, the impedance matching is achieved electrically.
[0027]
Specifically, Auger electrons and electrons with high kinetic energy (50 eV or more) sufficient to generate characteristic X-rays can be irradiated to the sample 5 atoms, and the structural change of the surface of the sample 5 can be caused by field evaporation or Joule heat. In order not to cause the high voltage charge / discharge capacity C₀Was 1 pF. And inductance L_mIs 5 nH, and impedance matching capacitance C is used to achieve impedance matching with the characteristic impedance 50 Ω of the main coaxial cable 14._mWas 1 pF.
[0028]
FIG. 6 shows another example of the structure for providing the capacitor portion 16 in the vicinity of the probe 4.₀And impedance matching capacitance C_mAnd a coaxial configuration. That is, the fixing plate 25 which is arranged at the center of the metal rod 24 formed with the screw 23 for attaching the probe 4 at the tip and fixed to the base end of the metal rod 24 is attached to the driving surface of the STM XYZ piezo scanner 6. A cylindrical first insulator 26 is provided around the metal rod 24, and a ring-shaped first metal plate 27 is provided on the outer periphery of the first insulator 26 to provide a high voltage charge / discharge capacity C.₀Is configured. Further, a space gap is formed on the outer periphery of the first metal plate 27 or a ring-shaped second metal plate 29 is provided via a ring-shaped second insulator 28 to provide the impedance matching capacitance C._mIs configured. Similarly to the above, the central conductor 14A of the main coaxial cable 14 is connected to the first metal plate 27, and the outer conductor 14B is connected to the second metal plate 29. In this case, the high voltage charge / discharge capacity C₀And impedance matching capacitance C_mThe capacitance of the first metal plate 27 and the second metal plate 29 can be adjusted by changing the axial width.
[0029]
Therefore, the voltage V of the high voltage power supply 12₀5 kV, resistance R_m50Ω, high voltage charge / discharge capacity C₀, Impedance matching capacitance C_mIs 1 pF and inductance L_mWas assumed to be 5 nH, and the current flowing between the probe 4 and the sample 5 was simulated when it was assumed that the probe 4 and the sample 5 were short-circuited during pulse application. The results are shown in FIG. 7 and FIG._mVoltage and resistance R_mFIG. 9 and FIG. 10 show high voltage charge / discharge capacitance C.₀Voltage and high voltage charge / discharge capacity C₀The transient phenomenon of the current flowing through each is shown. This high voltage charge / discharge capacity C₀Can be regarded as the current flowing between the probe 4 and the sample 5 (see FIG. 10). As a result, it was found that a pulse having a time width of about 200 to 300 ps was applied from the probe 4 to the sample 5.
[0030]
Although there is no method for directly measuring the ultrashort pulse high voltage waveform applied to the probe 4, high kinetic energy electrons emitted from the probe 4 are elastically scattered on the surface of the sample 5 with a certain probability. By utilizing this fact, the energy analysis of the elastically scattered electrons can be performed with an electron energy analyzer, and the maximum voltage of the ultrashort pulse high voltage applied to the probe 4 can be known from the maximum energy. Further, when high kinetic energy electrons radiated from the probe 4 collide with the surface of the sample 5, photons are radiated by bremsstrahlung with a certain probability. This photon energy analysis is performed by a photon energy analyzer, and the maximum voltage of the ultrashort pulse high voltage applied to the probe 4 can be known from the maximum energy.
[0031]
Then, the high-energy electrons radiated from the probe 4 can excite inner-shell electrons of the sample 5 (in some cases, valence electrons distributed spherically around the nucleus). When an electron whose energy level is lower than that of the inner shell electron, a photon or Auger electron is emitted. Therefore, the energy analysis and counting analysis of the photon or Auger electron are performed, that is, the inner shell distributed spherically around the nucleus. By analyzing information such as electrons for each atom, it is possible to determine the three-dimensional coordinates of the nucleus for each surface atom, elemental analysis, and chemical bond state analysis. That is, it is possible to know information on inner electrons of atoms that could not be measured with a conventional scanning probe microscope.
[0032]
Thereby, for example, the surface nucleus arrangement, surface impurity nucleus distribution, and surface chemical bonding state in silicon wafer, gallium arsenide wafer, and ULSI can be measured, which can contribute to the development of the semiconductor industry. In addition, it can contribute to the construction of fine structures by atomic manipulation, and is useful for surface atomic structure analysis to contribute to elucidation of the mechanism and practical application of high-temperature superconductors. It is useful for analysis of the binding state, and leads to DNA recombination such as DNA cleavage, binding and synthesis of new DNA, and can contribute to the development of the biotechnology industry.
[0033]
【The invention's effect】
  According to the ultrashort pulse high voltage generator for use in the scanning probe microscope of the present invention having the above contents, the probeIntegrated withBy applying a high-voltage ultrashort pulse to the probe with the charge accumulated in the microcapacitor provided on the probe, the amount of electric current (current) that flows when the pulse is applied is limited, and the probe applies a voltage applied to the capacitor and is emitted from the probe The kinetic energy of electrons can be controlled. In other words, when performing STM-AES and STM-XMA, sample atoms can be irradiated with electrons having high kinetic energy (50 eV or more) sufficient to generate Auger electrons or characteristic X-rays, and field evaporation or Joule heat Therefore, a high voltage ultrashort pulse having a pulse width of 1 ns or less with a controlled charge amount can be applied to the probe in order not to cause structural change of the sample surface.
[0034]
In order to remove the reflected wave caused by a large change in the impedance between the probe and the sample when a pulse is applied, a resistor with impedance matching is connected to the other end of the main coaxial cable connected to the capacitor. Therefore, since the unexpected reflected wave is completely removed by this resistance, the pulse waveform is completely prevented from being disturbed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining the present invention.
FIG. 2 is also an equivalent circuit diagram.
FIG. 3 is an explanatory conceptual diagram showing a case of STM measurement.
FIG. 4 is an explanatory conceptual diagram showing a case of applying a pulse.
FIG. 5 is a partial side view showing the structure around the probe.
FIG. 6 is a partial perspective view showing another structure around the probe.
FIG. 7: Resistance R_mIt is a graph which shows the simulation result of the voltage concerning.
FIG. 8: Resistance R_mIt is a graph which shows the simulation result of the electric current which flows into.
FIG. 9: High voltage charge / discharge capacity C₀It is a graph which shows the simulation result of the voltage concerning.
FIG. 10 High voltage charge / discharge capacity C₀It is a graph which shows the simulation result of the electric current which flows into.
[Explanation of symbols]
C₀  High voltage charge / discharge capacity C_m  Impedance matching capacity
R_m  Resistance L_m  Inductance
V₀  High voltage power supply voltage V_s  Power supply voltage for STM measurement
1 STM body 2 High-voltage ultrashort pulse power supply unit
3 Ultra-high vacuum chamber 4 Probe
5 Sample 6 XYZ Piezo Scanner for STM
7 Power supply for STM measurement 8 Switch
9 Low-pass filter 10 Current amplifier for STM
11 High voltage supply cable 11A Center conductor
11B Outer conductor 12 High voltage power supply
13 Coaxial relay switch 14 Main coaxial cable
14A Center conductor 14B Outer conductor
15 branch coaxial cable 15A center conductor
15B Outer conductor 16 Capacitor
17 1st metal electrode plate 18 1st insulator
19 Second metal electrode plate 20 Second insulator
21 Screw 22 Probe fixing plate
23 Screw 24 Metal rod
25 Fixing plate 26 First insulator
27 1st metal plate 28 2nd insulator
29 Second metal plate

Claims (4)

An ultrashort pulse high voltage generator for applying an ultrashort pulse high voltage between a probe and a sample of a scanning probe microscope, comprising: a probe fixing electrode plate electrically connected to the probe; A high voltage charge / discharge capacitance C ₀ composed of a minute capacitance having a structure in which a first insulator is sandwiched between one metal electrode plate is provided integrally with the probe, and switching between positive and negative with impedance matching with the main coaxial cable. A high-voltage ultrashort pulse power supply unit equipped with a possible high-voltage charging / discharging circuit, and connecting a central conductor for applying a high voltage to the first metal electrode plate at the tip of the main coaxial cable; It is adjusted by adding capacitance or inductance for impedance matching , discharging positive charges accumulated in the first metal plate constituting the high voltage charge / discharge capacity C ₀ , and applying negative charges to the probe. Or On the other hand, an ultrashort pulse high voltage generator for use in a scanning probe microscope, which discharges negative charges accumulated and applies positive charges to a probe. A high-voltage charge / discharge capacity C ₀ for applying a high voltage to the probe and a main part between the probe and an XYZ piezo scanner for a scanning probe microscope for driving the probe as the capacitor part that integrally formed and an impedance matching capacitor C _m for impedance matching with the coaxial cable, or the sample side embedded the XYZ piezo scanner for scanning Puropu microscope, high for applying a high voltage to該探needle The voltage charging / discharging capacity C ₀ and the impedance matching capacity C _m for impedance matching of the main coaxial cable are integrally configured. The high voltage charging / discharging capacity C ₀ includes the probe fixing electrode plate and the first electrode . forming across the first insulator to the metal electrode plates, impedance matching capacitor C _m is formed across the second insulator to the first metal plate and a second metal electrode plates, the center of the main coaxial cable With connecting body to the first metal electrode plate, an outer conductor and formed by connecting the second metal electrode plate according to claim 1 ultra short pulse high-voltage generator for use in scanning probe microscope according to the main coaxial cable. Ultra short pulse high voltage used for the characteristic impedance and the impedance matching via a balanced resistor R _m is formed by discharging charges accumulated in the capacitor C ₀ claim 1 or 2 scanning probe microscope according to the main coaxial cable Generator. 3. The ultrashort pulse high voltage generator for use in a scanning probe microscope according to claim 1 or 2, wherein a material having no piezoelectric effect and having a high rigidity is used as a material of the metal electrode plate and the insulator constituting the capacitor section.

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