JPH02243906A - Probe for scan type tunneling microscope with auxiliary electrode - Google Patents
Probe for scan type tunneling microscope with auxiliary electrodeInfo
- Publication number
- JPH02243906A JPH02243906A JP1063556A JP6355689A JPH02243906A JP H02243906 A JPH02243906 A JP H02243906A JP 1063556 A JP1063556 A JP 1063556A JP 6355689 A JP6355689 A JP 6355689A JP H02243906 A JPH02243906 A JP H02243906A
- Authority
- JP
- Japan
- Prior art keywords
- probe
- auxiliary electrode
- electric field
- electrode
- tip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000523 sample Substances 0.000 title claims abstract description 65
- 230000005641 tunneling Effects 0.000 title claims abstract description 10
- 230000005684 electric field Effects 0.000 claims abstract description 9
- 238000001514 detection method Methods 0.000 claims 1
- 150000002500 ions Chemical class 0.000 abstract description 23
- 238000005259 measurement Methods 0.000 abstract description 13
- 239000008151 electrolyte solution Substances 0.000 abstract description 5
- 239000000243 solution Substances 0.000 abstract description 5
- 230000005855 radiation Effects 0.000 abstract description 4
- 239000012212 insulator Substances 0.000 abstract description 3
- 230000000694 effects Effects 0.000 description 6
- 229940021013 electrolyte solution Drugs 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000005211 surface analysis Methods 0.000 description 1
Classifications
-
- 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
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は走査型トンネル顕ｙ１鏡等、試料表面に探針を
近づけ、探針先端より流れる電流を検出する表面解析装
置の探針の構造に関するものである。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the structure of a probe in a surface analysis device such as a scanning tunneling microscope that brings the probe close to the sample surface and detects the current flowing from the tip of the probe. It is related to.
（従来の技術）
従来の走査型トンネル顕微鏡では探針のみが試料表面に
突き出る構造になっており、探針先端近傍での電界制御
という観点からの配慮はなされていなかった。(Prior Art) Conventional scanning tunneling microscopes have a structure in which only the probe protrudes from the sample surface, and no consideration has been given to controlling the electric field near the tip of the probe.
（発明が解決しようとする問題点）
このため大気中または真空中での測定においては、探針
先端や試料表面に移動可能なイオンが吸着していると、
イオンの移動や振動が雑音として観測され、測定精度を
悪化させる原因となっていた。さらに電解質溶液中で観
測する場合には、探針側面から溶液への漏れ電流を防止
するために。(Problem to be solved by the invention) For this reason, in measurements in the air or vacuum, if movable ions are adsorbed to the tip of the probe or the surface of the sample,
The movement and vibration of ions were observed as noise, which worsened measurement accuracy. Furthermore, when observing in an electrolyte solution, to prevent current leakage from the side of the probe into the solution.
先端部以外を絶縁物でおおっている。しかしトンネル電
流に寄与している先端微小部だけを残して絶縁物で探針
をおおうことは、事実上不可能で２溶液への漏れ電流も
トンネル電流に加算されてしまうため、測定精度を悪化
させ、信頼性も低下している。All parts except the tip are covered with an insulating material. However, it is virtually impossible to cover the probe with an insulator while leaving only the tiny part of the tip that contributes to the tunneling current, and the leakage current to the two solutions will also be added to the tunneling current, which will deteriorate measurement accuracy. This has led to a decline in reliability.
（問題点を解決するための手段）
本発明では探針の周囲に補助電極を設置し、測定前に探
針と補助電極の間で電界イオン放射を行ない、探針先端
部の可動性イオンの除去を行なうことができる。さらに
測定中は補助電極に適当な電圧を印加して探針先端近傍
の電界を制御することにより 電解質溶液中においては
探針側面からの漏れ電流を減少させ、大気中においては
試料表面の移動可能なイオンが探針先端直下で動き回る
ことを防止しようというものである。(Means for Solving the Problems) In the present invention, an auxiliary electrode is installed around the probe, and before measurement, electric field ion emission is performed between the probe and the auxiliary electrode to eliminate mobile ions at the tip of the probe. Removal can be performed. Furthermore, during measurement, by applying an appropriate voltage to the auxiliary electrode and controlling the electric field near the tip of the probe, leakage current from the side of the probe is reduced in an electrolyte solution, and movement of the sample surface is possible in the atmosphere. The aim is to prevent ions from moving around directly beneath the tip of the probe.
（実施例）
第１図は本発明の基本的な配置を示す断面図で、第２図
は試料４を除いた外観図である。探針１の周囲に探針ｌ
を囲むように補助電極３を配置する。(Example) FIG. 1 is a sectional view showing the basic arrangement of the present invention, and FIG. 2 is an external view with sample 4 removed. Probe l around probe 1
The auxiliary electrode 3 is arranged so as to surround the auxiliary electrode 3.
補助電極３は探針１を中心とする中空円板ないしは中空
円筒が合理的な形状と考えられるが、特定の形をしてい
る必要はない、絶縁物２は、電解質溶液中の測定におい
ては、探針側面からの漏れ電流を防止する役割を果たし
、不可欠であるが、大気中の測定においては、補助電極
３を探針１に固定する手段が確保されていれば、必ずし
も必要と言う訳ではない、補助電極３と探針ｌの距離は
信号電流の測定を乱さない限り、近いことが望ましく、
補助電極３の内径と補助電極３を含む平面内の探針ｌの
外径の差を数十μｍ以内に納めないと効果が激減する。The ideal shape for the auxiliary electrode 3 is a hollow disk or hollow cylinder with the probe 1 at its center, but it does not need to have a specific shape. , which plays the role of preventing leakage current from the side surface of the probe and is indispensable; however, in atmospheric measurements, it is not necessarily necessary as long as a means for fixing the auxiliary electrode 3 to the probe 1 is secured. It is desirable that the distance between the auxiliary electrode 3 and the probe l be close as long as it does not disturb the measurement of the signal current.
Unless the difference between the inner diameter of the auxiliary electrode 3 and the outer diameter of the probe l in the plane containing the auxiliary electrode 3 is kept within several tens of μm, the effect will be drastically reduced.
以下に具体的な使い方について述べる。まず探針の先端
を電界イオン放射により清浄化するには、真空中におい
て探針ｌと補助電極３の間に電界イオン放射に必要なパ
ルス状の電圧をかけると吸着イオンが電界脱離する。実
際には吸着イオンのみでなく、探針を構成している金属
原子の一部も電界蒸発する事が考えられるが、それによ
り清浄で鋭利な先端突起部が得られれば、安定な表面像
が観察可能になる。The specific usage is described below. First, in order to clean the tip of the probe by field ion radiation, a pulsed voltage necessary for field ion radiation is applied between the probe l and the auxiliary electrode 3 in vacuum, and the adsorbed ions are desorbed by the field. In reality, it is possible that not only the adsorbed ions but also some of the metal atoms that make up the probe are evaporated by the electric field, but if a clean and sharp tip protrusion is obtained by this, a stable surface image can be obtained. becomes observable.
次に電解質溶液中において漏れ電流を減少させる場合の
使用法について述べる。この場合探針１と補助電極３は
同種の物質でできていることが望ましく、補助電極３に
探針１と同じ電位を加えることにより、電気力線の分布
が第３図に示したようになり、漏れ電流の大きさは電気
力線の密度に比例するので、探針１の側面から溶液への
漏れ電流が大幅に減少する事になる。探針１と補助電極
３がことなる物質でできている場合には、それぞれの物
質の標準酸化還元電位に配慮してことなる電圧を与えて
同様の効果を得ることができる。場合によっては補助電
極３が酸化還元反応を起こさない範囲内で、補助電極３
に印加する電圧を探針ｌのそれから変化させることによ
り、漏れ電流をさらに減少させることも期待できる。Next, we will discuss how to use it to reduce leakage current in an electrolyte solution. In this case, it is desirable that the probe 1 and the auxiliary electrode 3 are made of the same kind of material, and by applying the same potential to the auxiliary electrode 3 as the probe 1, the distribution of electric lines of force will be as shown in Figure 3. Since the magnitude of the leakage current is proportional to the density of the electric lines of force, the leakage current from the side surface of the probe 1 to the solution is significantly reduced. When the probe 1 and the auxiliary electrode 3 are made of different materials, the same effect can be obtained by applying different voltages in consideration of the standard redox potential of each material. In some cases, within the range where the auxiliary electrode 3 does not cause a redox reaction, the auxiliary electrode 3
It is also expected that the leakage current can be further reduced by changing the voltage applied to the probe l from that of the probe l.
最後に大気中の測定において試料４の表面に移動可能な
吸着イオンが存在する場合、補助電極３に吸着イオンと
逆極性の比較的大きな電圧を加えることにより、吸着イ
オンが補助電極３の下に移動することが期待され、探針
１の先端でのトンネル電流の測定に影響を与えなくなる
。特に第４図の実施例に示したように、２つの補助電極
を探針ｌにたいし同心円状に配置し、内側の補助電極３
に吸着イオンと同極性の電圧を印加して、外側の第２の
補助電極６に吸着イオンと逆極性の電圧をかけ、吸着イ
オンが第２の補助電極６の下に移動するようにすれば一
層の効果が期待できる。Finally, if there are movable adsorbed ions on the surface of the sample 4 during measurement in the atmosphere, by applying a relatively large voltage with the opposite polarity to the adsorbed ions to the auxiliary electrode 3, the adsorbed ions are moved under the auxiliary electrode 3. It is expected that it will move and will no longer affect the measurement of the tunneling current at the tip of the probe 1. In particular, as shown in the embodiment of FIG. 4, two auxiliary electrodes are arranged concentrically around the probe l, and the inner auxiliary electrode
If a voltage of the same polarity as the adsorbed ions is applied to the electrode, and a voltage of opposite polarity to the adsorbed ions is applied to the outer second auxiliary electrode 6, the adsorbed ions move below the second auxiliary electrode 6. Further effects can be expected.
（発明の効果）
この発明は（実施例）で述べたように、非常に簡単な構
造でありながら、その使用法により、走査型トンネル顕
微鏡用探針先端の清浄化、あるいは試料表面で移動可能
な吸着イオンによる測定妨害の軽減化等、各種の効果が
期待できる。大気中での走査型トンネル即徴鏡での観察
において見えるべき原子像が安定に観察できない原因は
前述の吸着イオンによる場合が多いと言われており、そ
の意味で本発明はおおいに有効である。また電解質溶液
において、従来の探針と同程度の面積を溶液に露出して
おきながら、探針側面からの漏れ電流を大幅に軽減でき
る点は、他に同様の効果を与える方法が確立していない
だけにその利益は大きい。(Effects of the invention) As described in (Example), this invention has a very simple structure, but depending on its usage, it can be used to clean the tip of a scanning tunneling microscope probe or to move it on the sample surface. Various effects can be expected, such as reducing measurement interference caused by adsorbed ions. It is said that the aforementioned adsorbed ions are often the reason why atomic images that should be visible cannot be stably observed during observation with a scanning tunneling mirror in the atmosphere, and in this sense, the present invention is highly effective. In addition, in electrolyte solutions, the leakage current from the side of the probe can be significantly reduced while exposing the same area to the solution as a conventional probe, and no other method has been established to provide a similar effect. However, the benefits are huge.
第１図は本発明の原理的な配置を示す探針先端部の断面
図である。第２図は第１図から試料４を取り除いた外観
図である。第３図は探針１と補助電極３に同電位を印加
した場合の電気力線の概略の分布を示している。第４図
は第２の補助電極６を付加した実施例の外観図である。
ｌ・・・・探針、２・・・・絶縁物、３・・・・補助電
極、４・・・・試料、５・・・・電気力線、
６・・・・第２の補助電極FIG. 1 is a sectional view of the tip of the probe showing the basic arrangement of the present invention. FIG. 2 is an external view with sample 4 removed from FIG. 1. FIG. 3 shows a rough distribution of electric lines of force when the same potential is applied to the probe 1 and the auxiliary electrode 3. FIG. 4 is an external view of an embodiment in which a second auxiliary electrode 6 is added. l... Probe, 2... Insulator, 3... Auxiliary electrode, 4... Sample, 5... Lines of electric force, 6... Second auxiliary electrode.
Claims (1)
印加する電圧により、探針近傍の電界を制御できる微小
電流検出用探針。 ２、特許請求の範囲第１項記載の走査型トンネル顕微鏡
用探針およびトポグラフィナー用探針。 ３、探針に流れる微弱電流を検出することにより、試料
表面微小領域の解析を行なう分析装置に使用される特許
請求の範囲第１項記載の探針。[Scope of Claims] 1. A microcurrent detection probe that has one or more auxiliary electrodes near the probe and can control the electric field near the probe by applying a voltage to the auxiliary electrodes. 2. A scanning tunneling microscope probe and a topographer probe according to claim 1. 3. The probe according to claim 1, which is used in an analysis device that analyzes a minute region on a sample surface by detecting a weak current flowing through the probe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1063556A JPH02243906A (en) | 1989-03-17 | 1989-03-17 | Probe for scan type tunneling microscope with auxiliary electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1063556A JPH02243906A (en) | 1989-03-17 | 1989-03-17 | Probe for scan type tunneling microscope with auxiliary electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02243906A true JPH02243906A (en) | 1990-09-28 |
Family
ID=13232611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1063556A Pending JPH02243906A (en) | 1989-03-17 | 1989-03-17 | Probe for scan type tunneling microscope with auxiliary electrode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02243906A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5136162A (en) * | 1990-07-26 | 1992-08-04 | Olympus Optical Co., Ltd. | Measuring device in a scanning probe microscope |
| EP0687889A3 (en) * | 1994-06-16 | 1996-10-16 | Japan Res Dev Corp | Method for detecting displacement of atoms on material surface and method for local supply of heteroatoms |
| US6088320A (en) * | 1997-02-19 | 2000-07-11 | International Business Machines Corporation | Micro-mechanically fabricated read/write head with a strengthening shell on the tip shaft |
-
1989
- 1989-03-17 JP JP1063556A patent/JPH02243906A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5136162A (en) * | 1990-07-26 | 1992-08-04 | Olympus Optical Co., Ltd. | Measuring device in a scanning probe microscope |
| EP0687889A3 (en) * | 1994-06-16 | 1996-10-16 | Japan Res Dev Corp | Method for detecting displacement of atoms on material surface and method for local supply of heteroatoms |
| US6088320A (en) * | 1997-02-19 | 2000-07-11 | International Business Machines Corporation | Micro-mechanically fabricated read/write head with a strengthening shell on the tip shaft |
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