JP3266995B2 - Method and apparatus for observing and measuring conductive members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for observing and measuring a conductive member, and more particularly to a device having a resolution of an atomic order, analyzing the structure and composition of an extremely fine region and clarifying an electronic state. The present invention relates to a measuring method and apparatus suitable for the method described above, and also relates to a method for producing a sample using a sample surface as a beam source.

[0002]

2. Description of the Related Art In a conventional atom probe, a tip radius is set to 0.
A high voltage is applied to a single needle-shaped sample of 1 μm or less, a pulse voltage or a pulse laser is applied to evaporate surface atoms as ions, and the flight time is measured to identify the type of atoms.

The reason why the tip radius is set to 0.1 μm or less is related to a voltage that enables the evaporation of atoms. If the tip radius is too large, a high voltage must be applied to cause a discharge. Therefore, even if a needle having a diameter of 0.1 μm or less is used initially, if evaporation is continued, the thickness gradually increases, and further analysis cannot be continued. Therefore, even if a needle is formed from a linear sample and the tip of the needle is analyzed, it is difficult to measure more than 50,000 atoms from one needle, and accurate statistical processing cannot be performed. was there.

In addition, when measuring adsorption, surface reaction, and interface, it is necessary to measure from a large number of needles and confirm the reliability of the data.

Incidentally, this type of prior art is disclosed in US Pat. Ts
ong: "Atom-probeField Ion
Microscope ", Cambridge Uni
-Version Press (Atom Probe Field Ion Microscopy; Cambridge University Press) (1990).

[0006]

In the prior art using a single needle as described above, the measurement or beam source is taken out of an ultra-high vacuum when the observation, analysis and measurement of one needle are completed. Must be replaced with a new one, and the equipment has a huge Dead
Generate Time. In addition, an atom probe or a field ion microscope (Field Ion Microsc)
(OP, FIM), data and statistical processing often cannot be performed by measurement from a single needle. Furthermore, it is extremely difficult to prepare a needle-shaped sample from a two-dimensional sample having a layered structure, and the evaluation of the interface structure is greatly limited.

According to the present invention, a multi-tip is prepared by using a sample
Atomic order which can measure a large number of points on a planar sample without disturbing an ultra-high vacuum, greatly reducing the Dead Time of the device as a system source and enabling two-dimensional sample analysis. It is an object of the present invention to provide a method and an apparatus for analyzing an extremely fine region, and a method for manufacturing a multi-tip suitable for the analysis.

[0008]

SUMMARY OF THE INVENTION The foregoing objects are attained by a scannable micro-lead electrode and a multi-tip.
You. For example, first, a mask formed on a conductive planar sample
A drawer supported by a movable mechanism on the front of the tip
Approach the electrode, and multi-tip with the extraction electrode
Select the tip to observe / measure from, and then select
By observing and measuring the tip
You.

Second, a drawer supported by a movable mechanism
Move the electrode and select, observe and measure the tip.
It is solved by observing and measuring different tips
You.

[0010] Further , the observation / measurement device for the conductive member of the present invention.
The device is formed, for example, on a vacuum vessel and a conductive planar sample.
Provided at a position facing the set multi-tip
The extraction electrode supported by a simple mechanism and the selected tip
And means for observing and measuring
You.

[0011]

[0012]

[0013]

[0014]

[0015]

[Function] Depending on the purpose of the research, the material of the planar sample can be metal,
There are various types of semiconductors, conductive glass, conductive ceramics, and conductive polymers, and multi-tips with sharp tips are prepared from these samples.

A conical extraction electrode supported by a mechanism movable in three directions of XYZ is brought close to the front of the multi-tip, and a tip to be observed, measured and analyzed is selected from the multi-tip. Next, after introducing the image gas into the vacuum device, multi-tip high voltage (bias + pulse)
Is applied to ionize the gas atoms at the needle tip, and the ions are used to observe the atomic arrangement at the needle tip.

Subsequently, the atoms are evaporated from the tip surface as cations, and the ions are flown to an ion detector to measure the flight time and identify the atoms. In addition, a negative voltage is applied to the sample to apply a field emission microscope (Field Emissi).
on Microscope (FEM), and emits electrons from the tip of the needle, and the energy of those electrons.
The electronic state is also examined by analyzing and measuring.

When the observation and measurement of this tip are completed, the next tip is selected by the extraction electrode. This work is continued to complete the target analysis. This makes it possible to acquire a large amount of data on the target surface / interface structure, composition distribution, and electronic state by introducing the sample into an ultra-high vacuum once.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. ◆ An external view of the multi-tip is shown in FIG. The multi-tip has a form in which many tips 11 are arranged on the same substrate 12 plane. The length and distribution interval of the needles are selected according to the purpose of use.

As shown in FIG. 2, the tip of the multi-tip is mechanically formed by cutting a plate-like sample 21 vertically and horizontally by a cutter 22. This allows
In addition to producing a large number of tips in a short time and performing analysis, there is an effect that two-dimensional information can be obtained. Here, the cutting edge angle 23 of the cutter determines the tip angle of the tip 24.

Further, FEM, FIM, atom probe,
Position-sensitive atom probe (Po-position-Se)
When used as a sample of an native atom probe), all tips of the multi-tip are further immersed in an electrolytic solution and electrolytically polished to have a radius of curvature of 1000 tips.
に す る Use the following sharp multi-tips. In this case, in contrast to the conventional method of separately performing electropolishing one by one, the present invention has a feature that a large number of sharp tips can be simultaneously manufactured in a short time.

In the case of a thin film multilayer structure material such as a semiconductor or a magnetic thin film, a multi-tip can be manufactured by a photolithography process using ion milling or the like. Furthermore, a multi-tip can be manufactured by placing a lump of the nucleus element at regular intervals on a planar sample and growing whiskers from the lump. The multi-tip can be used as an electron beam source for FE-TEM or electron beam holography in addition to the above.

The following multi-tip is used for the atom probe FI
The case where the analysis sample of M is used will be described below with reference to FIG. Instead of one conventional tip, the multi-tip sample 31 is mounted on the ultrahigh vacuum vessel of the atom probe FIM. Multi-tip with cryogenic refrigerator 32 for about 2
After cooling to 0K, a positive high voltage (stationary voltage) of several kV is applied to the sample.

An extraction electrode 33 made of a cone having a diameter of 1 μm or less with a taper is brought close to one of the multi-tips 34 from the opposite side, and a positive high voltage of several kV is applied to this extraction electrode (here, a high voltage is applied). The extraction electrode 33 is supported by a mechanism movable in three directions of X, Y, and Z, and is formed by molding by electroforming or plastic working. In order to prevent damage to the substrate, set the shape of the electrode so that the ratio of the electric field strength between the tip of the tip and the tip of the extraction electrode is 10: 1 or more, and move the electrode to the optimal position (1 μm or less from the needle). Approach.)

Further, when a pulse voltage of 10 to 20% of the steady voltage is added, the atoms on the tip surface evaporate by electric field, fly as ions 35, and arrive at the detector 36.
When the pulse voltage is continuously applied, surface atoms are peeled off one by one from the tip of the tip, and a concentration profile for each atomic layer can be obtained from the surface. When an inert gas such as He or Ne is introduced without applying the pulse voltage, an FIM image showing a two-dimensional array of surface atoms can be observed on the screen 37.

When about 50,000 or more ions are collected from the tip 34, the radius of curvature at the tip of the tip is increased, the applied voltage required for electric field evaporation is increased, and the analysis cannot be continued. When a negative voltage is further applied to the needle, FIM
Operates as an FEM and emits electrons from the needle tip.

The probe hose at the center of the screen 37
Inserting the Faraday cup 38 after the hole and analyzing the energy of the electrons reveals the electronic state of the region of the needle tip corresponding to the probe hole.

In the conventional atom probe FIM, the analysis is terminated here. In the present invention, the same analysis is performed by moving the extraction electrode 33 and approaching the next tip 38. By repeating each tip analysis as described above, a large amount of information can be obtained from one sample, and there is an effect that the concentration distribution in the planar direction of the sample can be examined.

This indicates that the present invention is also advantageous when a large amount of electrons and ions are emitted by using the sample surface as an electron and ion source. Also, if the tip of the extraction electrode can be miniaturized to a diameter of several thousand mm or less, it becomes the same dimension as the scanning needle and the flat sample of the currently used scanning tunneling microscope. Therefore, even if a multi-tip is not formed, the surface itself becomes an electron ion source if there are irregularities in the atomic order.

[0030]

According to the present invention, since a multi-tip arranged on the same sample is used as a sample or a beam source, it is not necessary to exchange the sample for each tip, thereby improving the operation rate of the apparatus. There is an effect that can be. Further, there is an effect that a large number of measurements can be performed without disturbing the ultra-high vacuum.

[Brief description of the drawings]

FIG. 1 is an external view of a multi-tip.

FIG. 2 is a schematic view showing a method for producing a multi-tip by mechanical cutting.

FIG. 3 is a schematic diagram showing a method of using a multitip as an analysis sample of an atom probe FIM.

[Explanation of symbols]

11 tip, 12 substrate, 21 plate sample, 22
Cutter, 23 ... Blade angle, 24 ... Tip angle, 31 ... Multi tip sample, 32 ... Cryogenic refrigerator, 33 ... Extraction electrode, 34 ... Tip, 35 ... Ion, 36 ... Detector,
37 ... Screen, 38 ... Faraday cup.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Osamu Nishikawa 7-364, Kubo, Kanazawa-shi, Ishikawa Nishio Building Room No. 608 (56) References JP-A-50-114969 (JP, A) JP-A-61-263020 (JP) JP-A-1-117234 (JP, A) JP-A-62-232849 (JP, A) JP-A-60-211756 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01J 37/285 H01J 49/40 H01J 9/02 H01J 9/42 H01J 37/06-37/077

Claims (8)

(57) [Claims] 1. An extraction electrode supported by a mechanism movable in three directions of XYZ, approaching a front surface of a plurality of tips (multi-tips) formed on a conductive planar sample. A tip to be observed / measured from the plurality of tips (multi-tips), and thereafter, a voltage is applied to the selected tip in an image gas atmosphere, so that the image gas is applied at the tip of the selected tip. A method for observing and measuring a conductive member, comprising ionizing and observing and measuring the atomic arrangement of the tip of the tip with the ions of the image gas. 2. An extraction electrode supported by a mechanism movable in three directions of XYZ, approaching a front surface of a plurality of tips (multitips) formed on a conductive planar sample. A tip to be observed and measured is selected from the plurality of tips (multi-tips), and thereafter, atoms are electro-evaporated as cations from the surface of the selected tip, and the electro-evaporated cations are detected by an ion detector. A method for observing and measuring a conductive member, comprising detecting and measuring the time of flight of the cations from the selected tip to the ion detector to identify atoms. 3. An extraction electrode supported by a mechanism movable in three directions of XYZ, approaching a front surface of a plurality of tips (multitips) formed on a conductive planar sample. Selecting a tip to observe and measure from the plurality of tips (multi-tip), and then applying a negative voltage to the tip of the selected tip,
Analyze the energy of the electrons emitted from the tip
A method for observing and measuring a conductive member, characterized by measuring. 4. An extraction electrode supported by a mechanism movable in three directions, XYZ, is moved to the front of a plurality of tips (multitips) formed on a conductive planar sample. A tip to be observed / measured from the plurality of tips (multi-tip) is selected, and after observing and measuring the tip of the selected tip, the extraction electrode is moved to observe a tip different from the selected tip. -A method for observing and measuring a conductive member characterized by measuring. 5. The electric field intensity ratio between the tip of the selected tip and the tip of the extraction electrode is 10: 1 or more, and the distance between the tip of the selected tip and the tip of the extraction electrode is 1 μm. The method for observing and measuring a conductive member according to claim 1, wherein: 6. A drawer provided at a position facing a vacuum container and a plurality of tips (multi-tips) formed on a conductive planar sample, and supported by a mechanism movable in three directions XYZ. An electrode, means for supplying an image gas, means for applying a voltage to a selected tip, and means for observing and measuring the atomic arrangement at the tip of the selected tip by ions of the image gas. Observation / measurement device for conductive members. 7. A drawer provided at a position facing a vacuum container and a plurality of tips (multi-tips) formed on a conductive planar sample, and supported by a mechanism movable in three directions of XYZ. An electrode, means for applying a voltage to the selected tip, means for electrolytically evaporating atoms from the surface of the selected tip as cations, means for detecting the cations with an ion detector, and the cations Means for measuring the time of flight from the selected tip to the ion detector. 8. A drawer provided at a position facing a vacuum vessel and a plurality of tips (multi-tips) formed on a conductive planar sample, and supported by a mechanism movable in three directions of XYZ. An electrode, means for applying a voltage to the selected tip, and means for applying a negative voltage to the tip of the selected tip to analyze and measure the energy of electrons emitted from the selected tip. Observation and measurement device for conductive members provided.