JPH07325090A - Optical lever type scanning probe microscope and atomic force microscope - Google Patents
Optical lever type scanning probe microscope and atomic force microscopeInfo
- Publication number
- JPH07325090A JPH07325090A JP6118116A JP11811694A JPH07325090A JP H07325090 A JPH07325090 A JP H07325090A JP 6118116 A JP6118116 A JP 6118116A JP 11811694 A JP11811694 A JP 11811694A JP H07325090 A JPH07325090 A JP H07325090A
- Authority
- JP
- Japan
- Prior art keywords
- force
- probe
- cantilever
- sample
- microscope
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q20/00—Monitoring the movement or position of the probe
- G01Q20/02—Monitoring the movement or position of the probe by optical means
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は走査型プローブ顕微鏡及
び原子間力顕微鏡に係り、特にカンチレバーの微動制御
を含む光てこ方式の顕微鏡に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscope and an atomic force microscope, and more particularly to an optical lever type microscope including fine movement control of a cantilever.
【０００２】[0002]
【従来の技術】近年物質表面の計測技術と微細加工技術
の発展に伴なって、量子サイズの表面粗さ計である走査
型プローブ顕微鏡（Ｓｃａｎｎｉｎｇ Ｐｒｏｂｅ Ｍ
ｉｃｒｏｓｃｏｐｅ、ＳＰＭ）が開発されるに至った。
ＳＰＭは探針（プローブ）先端と近接した試料との間に
作用する微少な力を利用して、この力を一定値に保つよ
うにプローブ位置を制御しつつ試料表面を走査すること
によって拡大されたプローブ軌跡を像として観察する機
能を持つ。プローブに作用する量子効果としては、トン
ネル電流、中性原子間引力・斥力及び磁力などが利用さ
れている。その結果、走査型トンネル顕微鏡（ＳＴ
Ｍ）、原子間力顕微鏡（Ａｔｏｍｉｃ Ｆｏｒｃｅ Ｍ
ｉｃｒｏｓｃｏｐｅ、ＡＦＭ）及び磁気力顕微鏡（ＭＦ
Ｍ）が実用化された。2. Description of the Related Art In recent years, along with the development of material surface measurement technology and fine processing technology, a scanning probe microscope (Scanning Probe M), which is a surface roughness meter of quantum size, has been developed.
(microscope, SPM) has been developed.
SPM is magnified by scanning the sample surface while controlling the probe position so as to maintain this force at a constant value by utilizing the minute force that acts between the tip of the probe (probe) and the sample in the vicinity. It has the function of observing the probe locus as an image. Tunneling current, neutral interatomic attraction / repulsion, magnetic force, etc. are used as the quantum effect acting on the probe. As a result, the scanning tunneling microscope (ST
M), atomic force microscope (Atomic Force M)
microscope (AFM) and magnetic force microscope (MF)
M) was put to practical use.
【０００３】特に、ＡＦＭはＳＴＭで必要な試料の導電
性やＭＦＭで必要な磁性体試料は不要であり、絶縁物や
有機分子（例えば液晶やプラスチックなど）の表面状態
をｎｍスケールで観察できるため広範な応用が期待され
ている。In particular, the AFM does not require the conductivity of the sample required for the STM or the magnetic sample required for the MFM, and the surface state of insulators and organic molecules (for example, liquid crystals and plastics) can be observed on the nm scale. Wide application is expected.
【０００４】図２には光てこ方式の走査型プローブ顕微
鏡の１つであるＡＦＭの構成図を示す。このＡＦＭ顕微
鏡１は、ｘｙｚスキャナ（微動機構）２（これはｚスキ
ャナとｘｙスキャナとより成る）、カンチレバー３、カ
ンチレバー３の先端に取り付けた探針４、光／電気変換
を行うカンチレバー検出器５、試料６を搭載する試料テ
ーブル７、試料テーブル７を搭載してＸＹ方向に駆動す
るＸＹステージ１０、光学顕微鏡９、Ｚ方向粗動ステー
ジ（粗動機構）８、カンチレバー検出器５の変位電気信
号を増幅するカンチレバー変位検出部１１、力設定部１
２、計算機１３、モニタ１４、Ｚ方向粗動ステージ制御
回路１５、ｘｙｚスキャナ制御回路１６、ＸＹステージ
制御回路１７、ステージ変位検出部１８より成る。FIG. 2 is a block diagram of an AFM which is one of the optical lever type scanning probe microscopes. This AFM microscope 1 includes an xyz scanner (fine movement mechanism) 2 (which is composed of a z scanner and an xy scanner), a cantilever 3, a probe 4 attached to the tip of the cantilever 3, and a cantilever detector 5 for performing optical / electrical conversion. , A sample table 7 on which the sample 6 is mounted, an XY stage 10 on which the sample table 7 is mounted and driven in the XY directions, an optical microscope 9, a Z direction coarse movement stage (coarse movement mechanism) 8, and displacement electric signals of the cantilever detector 5. Displacement detection unit 11 for amplifying force, force setting unit 1
2, a computer 13, a monitor 14, a Z-direction coarse movement stage control circuit 15, an xyz scanner control circuit 16, an XY stage control circuit 17, and a stage displacement detector 18.
【０００５】カンチレバー検出器５は、レーザ光学系に
よるカンチレバー変位検出器であり、レーザ光５Ａをカ
ンチレバー３に当て、その反射光を受光してカンチレバ
ーのＺ方向変位を検出する。このカンチレバー検出器５
の検出方式が光てこ方式である。光てこ方式以外には、
トンネル検出式や光波干渉式がある。The cantilever detector 5 is a cantilever displacement detector using a laser optical system. The cantilever detector 5 applies a laser beam 5A to the cantilever 3 and receives the reflected light to detect the Z direction displacement of the cantilever. This cantilever detector 5
The detection method is the optical lever method. Other than the optical lever method,
There are tunnel detection type and light wave interference type.
【０００６】かかる顕微鏡では、ＸＹステージ１０上に
試料６を載せ、光学顕微鏡９で試料上の観察位置を捜
し、その位置にＡＦＭの探針４を合わせ、カンチレバー
３の受ける力を一定に制御しながらＸＹ方向にスキャニ
ングし、像観察する。力一定の制御は、フォースカーブ
に従って動作指令を行う力設定部１２によって行う。ま
たＸＹ方向のスキャニングに関しては、例えば、１００
倍の光学顕微鏡では、８８×６６μｍの範囲を、水平方
向に０．２５μｍ、垂直方向に０．５μｍ程度の精度
で、またＡＦＭ顕微鏡では、約１０×１０μｍの範囲
を、水平方向０．１ｎｍ、垂直方向０．０１ｎｍの分解
能で測定できる。In such a microscope, the sample 6 is placed on the XY stage 10, the observation position on the sample is searched by the optical microscope 9, the probe 4 of the AFM is aligned with that position, and the force received by the cantilever 3 is controlled to be constant. While scanning in the XY directions, observe the image. The constant force control is performed by the force setting unit 12 that issues an operation command according to the force curve. For scanning in the XY directions, for example, 100
With a double optical microscope, the range of 88 × 66 μm is 0.25 μm in the horizontal direction and about 0.5 μm in the vertical direction, and with the AFM microscope, the range of about 10 × 10 μm is 0.1 nm in the horizontal direction. It can be measured with a resolution of 0.01 nm in the vertical direction.
【０００７】図３に、フォースカーブを示す。このカー
ブは、原子間力とカンチレバー検出値との関係を求める
ために必要である。矢印は行きと帰りとで特性が異な
る、いわゆるヒステリシス特性を示す。この従来例では
原子間力そのものを直接求めるのではなく、カンチレバ
ー３に働く原子間力（引力または斥力）を、カンチレバ
ー３の変位（Ｚ変位のこと）によって間接的に求めてい
るためフォースカーブが必要なのである。更に探針の材
質、形状や重さ、探針の周囲の環境によってフォースカ
ーブは変化する。そこで実際の測定開始前に、その測定
のためにフォースカーブを求めることになっている。FIG. 3 shows a force curve. This curve is necessary to obtain the relationship between the atomic force and the cantilever detection value. The arrow indicates a so-called hysteresis characteristic in which the characteristics differ between the going and returning. In this conventional example, the atomic curve itself is not directly obtained, but the atomic force (attractive force or repulsive force) acting on the cantilever 3 is indirectly obtained by the displacement (Z displacement) of the cantilever 3, so that the force curve is It is necessary. Further, the force curve changes depending on the material, shape and weight of the probe and the environment around the probe. Therefore, before starting the actual measurement, the force curve is to be obtained for the measurement.
【０００８】図３のフォースカーブは、探針４を被測定
試料表面から十分離れた位置より矢印に沿って被測定試
料６に近接させていき、試料表面に接触後逆に次第に試
料６から引き離していった時の探針４と試料６との距離
（Ｚ）と力（Ｆ）との曲線例である。接近させていく場
合、Ａ点で探針４に原子間力（引力）が作用しはじめ、
引力が極大値を示す。探針４をＺ方向に移動させるに従
って、探針４に斥力が加わってくるため、原子間力Ｆ
（引力と斥力の和）は直線的に減少し、引力と斥力が釣
りあった後斥力領域に至る。で示す試料表面から逆に
探針４を離していく場合には、径路がずれてヒステリシ
スができる。Ｂ点で引力が最大となった後、原子間力の
働きがない距離に至る。具体的な数値例としては、Ａ点
での引力が約１０-10Ｎ、被測定試料２４表面近傍の
では斥力が１０-6〜１０-7Ｎ、、は斥力１０-8Ｎ、
１０-9Ｎの位置である。In the force curve shown in FIG. 3, the probe 4 is moved closer to the sample 6 to be measured along the arrow from a position sufficiently distant from the sample surface to be measured. It is an example of a curve of the force (F) and the distance (Z) between the probe 4 and the sample 6 when going down. When approaching, atomic force (attraction) begins to act on the probe 4 at point A,
The attractive force shows the maximum value. As the probe 4 is moved in the Z direction, a repulsive force is applied to the probe 4, so the atomic force F
(The sum of the attractive force and the repulsive force) decreases linearly, and reaches the repulsive force region after the attractive force and the repulsive force are balanced. When the probe 4 is separated from the surface of the sample, the path is deviated to cause hysteresis. After the attractive force reaches its maximum at point B, it reaches a distance where no atomic force works. As a specific numerical example, the attractive force at the point A is about 10 −10 N, the repulsive force is 10 −6 to 10 −7 N near the surface of the measured sample 24, and the repulsive force is 10 −8 N,
The position is 10 -9 N.
【０００９】このようなフォースカーブを、従来はカン
チレバー検出器等を利用して求め、これを力設定部１２
にラッチしておき、力設定部１２では力設定値になるよ
うに、このフォースカーブを利用してカンチレバー３の
距離Ｚの制御を行う。この力設定値となるようにカンチ
レバー３の位置制御を行いながら、実際の計測を行う。Conventionally, such a force curve is obtained using a cantilever detector or the like, and this is obtained.
The force setting unit 12 controls the distance Z of the cantilever 3 by using this force curve so that the force setting value becomes the force setting value. The actual measurement is performed while controlling the position of the cantilever 3 so that this force setting value is obtained.
【００１０】ここで、フォースカーブの事前計測法の一
例を以下に示す。Ｚ軸粗動ステージ８で、カンチレバー
３の探針４を試料に接近させる。移動距離は数十ｍｍか
ら、数μｍで、駆動方法としては、インチワーム方式等
が使われる。ｘｙｚスキャナ２のｚスキャナのストロー
ク範囲（数μｍ）に入ると、ｘｙｚスキャナ２のｚスキ
ャナで更に接近させる。ｘｙｚスキャナ２の微動駆動
は、トライポット、チューブスキャナ等の圧電素子で行
う。数１０ｎｍに接近すると、例えば試料６に水滴が付
着していると、水滴の引力によってカンチレバー３が一
瞬に引き付けられる。更に接近させると、探針４が試料
に当り、斥力が働き、カンチレバー３が逆方向に変形す
る。探針４が試料６に当たった状態は、スタート時のた
わみと同一になったことで分かる。また、カンチレバー
３のたわみは、試料６に探針４が当たった状態から、ｘ
ｙｚスキャナ２のｚスキャナが移動した距離ｄで分か
る。もともとカンチレバー４の剛性Ｋは、計算式で求ま
るので、カンチレバー４の受ける力ＦはＫｄで求まる。
例えば、Ａ点で１０-10Ｎ、点で１０-6〜-7Ｎとな
る。このフォースカーブを求めるとき、カンチレバー４
に、レーザ光５Ａを当て、その出力を、カンチレバー検
出器５で測定するため、カンチレバーの出力値と、カン
チレバーが受ける力（原子間力）との関係が求まる。な
お、カンチレバー検出器５は、反射レーザ光の反射位置
の変位でカンチレバーが受ける力を測定する。この時、
この変位相当を示す電気信号を得、これを検出部１１に
送り増幅させ、力設定部１２にフォースカーブとしてラ
ッチさせる。An example of a force curve pre-measurement method will be described below. On the Z-axis coarse movement stage 8, the probe 4 of the cantilever 3 is brought close to the sample. The moving distance is from several tens of mm to several μm, and an inchworm system or the like is used as a driving method. When the stroke range (several μm) of the z scanner of the xyz scanner 2 is entered, the z scanner of the xyz scanner 2 is moved closer. The fine movement drive of the xyz scanner 2 is performed by a piezoelectric element such as a tripot or a tube scanner. When approaching several tens of nm, for example, if water droplets are attached to the sample 6, the cantilever 3 is instantly attracted by the attractive force of the water droplets. When the probe 4 is brought closer, the probe 4 hits the sample, a repulsive force is exerted, and the cantilever 3 is deformed in the opposite direction. It can be seen that the state in which the probe 4 hits the sample 6 is the same as the deflection at the start. In addition, the deflection of the cantilever 3 can be determined by measuring x when the probe 4 hits the sample 6.
It can be seen from the distance d moved by the z scanner of the yz scanner 2. Since the rigidity K of the cantilever 4 is originally obtained by a calculation formula, the force F received by the cantilever 4 is obtained by Kd.
For example, the point A is 10 -10 N and the point is 10 -6 to -7 N. When calculating this force curve, the cantilever 4
Since the laser beam 5A is applied to and the output is measured by the cantilever detector 5, the relationship between the output value of the cantilever and the force (atomic force) received by the cantilever can be obtained. The cantilever detector 5 measures the force received by the cantilever by the displacement of the reflection position of the reflected laser light. At this time,
An electric signal indicating this displacement is obtained, sent to the detection unit 11 for amplification, and the force setting unit 12 latches it as a force curve.
【００１１】フォースカーブが求まった後で、ＡＦＭと
しての使用する力を設定する。カンチレバー３に加わる
力を一定にしながら実際の計測を行うが、この一定に加
える力をいかなる値にするかを設定するのである。この
力設定値は、カンチレバー検出器５の出力と同じ電圧値
としておくと便利である。After the force curve is obtained, the force used as the AFM is set. The actual measurement is performed while keeping the force applied to the cantilever 3 constant, and what value the constant force is set to is set. It is convenient to set this force set value to the same voltage value as the output of the cantilever detector 5.
【００１２】かくして実際の計測動作に入るが、先ず設
定値になるようにＺ粗動ステージ８、ｘｙｚスキャナ２
のｚスキャナを移動させる。カンチレバー３の出力値が
力設定値に対応するようになると、ｘｙスキャナを移動
させ平面内の像観察を行う。この時、常にｚスキャナで
力設定値が一定になるようにサーボ制御が加えられてい
る。このサーボ系を構成しているのが、記号５、１１、
１２、１５、１６、８、２で示す装置類である。Thus, the actual measurement operation is started, but first, the Z coarse movement stage 8 and the xyz scanner 2 are adjusted so that the set values are obtained.
Move the z scanner of. When the output value of the cantilever 3 comes to correspond to the force setting value, the xy scanner is moved to observe the image in the plane. At this time, servo control is always applied by the z scanner so that the force setting value becomes constant. This servo system is composed of symbols 5, 11,
These are devices indicated by 12, 15, 16, 8, and 2.
【００１３】[0013]
【発明が解決しようとする課題】前記したように原子間
力顕微鏡（ＡＦＭ）では、被測定試料を代える度に（或
は同一試料でも組成、形状を異にする度に、或は場所を
代える度に）、フォースカーブをとり直さなければなら
ない。この場合、図３で示したように、従来は力設定値
となる原子間力ＦがのＦ0にあっても、被測定試料の
表面近傍までのフォースカーブをとっていた。即ち、
１０-9Ｎ程度（の位置）の原子間力を利用するのに、
１０-6〜１０-7Ｎ（の位置）までの力履歴をカンチレ
バーに与えていた。As described above, in the atomic force microscope (AFM), each time the sample to be measured is changed (or the same sample has a different composition or shape, or the position is changed). Every time) you have to retake the force curve. In this case, as shown in FIG. 3, conventionally, a force curve up to the vicinity of the surface of the sample to be measured was taken even when the atomic force F, which is the force setting value, was F 0 . That is,
To use the atomic force of about 10 -9 N (at the position),
The cantilever was given a force history up to (position of) 10 -6 to 10 -7 N.
【００１４】カンチレバーは、微細な金属箔や酸化シリ
コンなどの薄膜で形成され柔らかいバネであるため、機
械的に非常に脆弱である。それ故前記したように、実際
試料計測に使用しない大きな応力を印加してこの応力に
相当する深い曲げを与えることは、カンチレバーの材料
疲労を惹起する原因になる。更に図３のようなフォース
カーブを求めるために、探針をで示すように一旦試料
表面に接触させると鋭敏な先端を有する探針や試料表面
にキズをつける恐れがある。このような場合は、正確な
試料の表面像が得られなくなる。Since the cantilever is a soft spring formed of a fine metal foil or a thin film of silicon oxide, it is mechanically very fragile. Therefore, as described above, applying a large stress that is not actually used for sample measurement and applying deep bending corresponding to this stress causes material fatigue of the cantilever. Further, in order to obtain the force curve as shown in FIG. 3, once the probe is brought into contact with the sample surface as indicated by, there is a risk that the probe having a sharp tip or the sample surface may be damaged. In such a case, an accurate surface image of the sample cannot be obtained.
【００１５】本発明の目的は、カンチレバーに過大な応
力を印加せず、また探針や試料表面を損傷せずに試料の
表面像を観察することができる走査型プローブ顕微鏡及
び原子間力顕微鏡を提供することである。An object of the present invention is to provide a scanning probe microscope and an atomic force microscope capable of observing a surface image of a sample without applying excessive stress to the cantilever and without damaging the probe or the sample surface. Is to provide.
【００１６】[0016]
【課題を解決するための手段】本発明は、一端に探針を
持つカンチレバーを持ち、探針に働く力を一定にした状
態で試料表面を走査する光てこ方式の走査型プローブ顕
微鏡において、探針を試料に接近させる毎に、Ｚ方向の
移動量とカンチレバーの剛性により探針に働く力を演算
し、それにより、力設定値のカンチレバー変位検出値を
求め、力設定値になった後、その力を一定に制御しなが
ら、平面走査し、像観察する光てこ方式の走査型プロー
ブ顕微鏡を開示する。The present invention provides a cantilever having a probe at one end, and an optical lever type scanning probe microscope which scans a sample surface with a force acting on the probe being constant. Each time the needle approaches the sample, the force acting on the probe is calculated based on the amount of movement in the Z direction and the rigidity of the cantilever, and the cantilever displacement detection value of the force setting value is calculated, and after reaching the force setting value, An optical lever type scanning probe microscope is disclosed which performs planar scanning and image observation while controlling the force constant.
【００１７】更に本発明は、Ｚ方向への粗動・微動機構
と、一端にこの機構が固定し、他端に探針を持つカンチ
レバーと、カンチレバーに働く試料の原子間力を光てこ
方式で検出するカンチレバー検出器と、探針を粗動・微
動機構を用いて試料に接近させる毎に、該機構の移動量
（探針の移動量）Ｚとカンチレバーの剛性Ｋとによりそ
の時の原子間力Ｆを算出し、これから力設定値Ｆthを得
るべきカンチレバー変位検出器の検出予測値Ｖthを算出
する演算手段と、この検出予測値Ｖthになるように上記
粗動・微動機構を位置制御する制御手段と、この力設定
値になるような一定力制御のもとで試料面の観察像を得
る手段と、より成る原子間力顕微鏡開示する。Further, according to the present invention, a coarse / fine movement mechanism in the Z direction, a cantilever having this mechanism fixed at one end and a probe at the other end, and an interatomic force of a sample acting on the cantilever are utilized by an optical lever method. Each time the cantilever detector for detection and the probe are brought closer to the sample by using the coarse / fine movement mechanism, the atomic force at that time is determined by the movement amount (movement amount of the probe) Z of the mechanism and the rigidity K of the cantilever. A calculation means for calculating F and calculating a predicted detection value V th of the cantilever displacement detector from which the force set value F th should be obtained, and position control of the coarse / fine movement mechanism so as to reach the detected prediction value V th. The atomic force microscope is disclosed which comprises a control means for controlling the force and a means for obtaining an observation image of the sample surface under the constant force control so as to obtain the force set value.
【００１８】[0018]
【作用】本発明によれば、探針を接近させる毎に、その
時の計測値から力一定制御のための探針の位置制御を行
う。従って、フォースカーブの全体を求めることなく、
力一定制御を実行でき、カンチレバーへの負担、試料表
面への衝突等の障害をなくせる。According to the present invention, each time the probe is approached, the position of the probe for constant force control is controlled from the measured value at that time. Therefore, without obtaining the entire force curve,
The constant force control can be executed, and the obstacles such as the load on the cantilever and the collision on the sample surface can be eliminated.
【００１９】[0019]
【実施例】以下本発明を実施例に基づいて、より詳しく
述べる。図１は実施例で用いたＡＦＭの構成を示す図で
ある。原子間力顕微鏡（ＡＦＭ）１は、カンチレバー３
の一端が固設されたｘｙｚスキャナ（ｘｙスキャナとｚ
スキャナより成る）（微動装置）２、カンチレバー検出
器５、ｘｙｚスキャナ２に接続したＺ粗動ステージ（粗
動機構）８、光学顕微鏡９、試料テーブル７、試料テー
ブル７を固設したＸＹステージ１０、ベース１９及び制
御系とモニタ１４から成る。カンチレバー３の先端には
探針４が接続され、試料テーブル７には被測定の試料６
が設置される。更に、カンチレバー変位検出器５、Ｚ粗
動ステージ８、光学顕微鏡９及びＸＹステージ１０を設
けているが、これらは図示しないベース上に固定設置さ
れる。EXAMPLES The present invention will be described in more detail based on the following examples. FIG. 1 is a diagram showing the configuration of the AFM used in the embodiment. Atomic force microscope (AFM) 1 has a cantilever 3
Xyz scanner with one end fixed (xy scanner and z
(Composed of scanner) (fine movement device) 2, cantilever detector 5, Z coarse movement stage (coarse movement mechanism) 8 connected to xyz scanner 2, optical microscope 9, sample table 7, XY stage 10 having sample table 7 fixed , A base 19, a control system and a monitor 14. A tip 4 of the cantilever 3 is connected to the tip of the cantilever 3, and a sample 6 to be measured is placed on the sample table 7.
Is installed. Further, a cantilever displacement detector 5, a Z coarse movement stage 8, an optical microscope 9 and an XY stage 10 are provided, but these are fixedly installed on a base (not shown).
【００２０】制御系は、カンチレバー変位検出部１１、
原子間力設定部１２Ａ、Ｚ方向粗動ステージ制御回路１
５、ｘｙｚスキャナ制御回路１６、ＸＹステージ制御回
路１７、ステージ変位検出部１８、及びこれら諸回路を
統括する計算機１３から成る。The control system consists of a cantilever displacement detector 11,
Atomic force setting unit 12A, Z direction coarse movement stage control circuit 1
5, an xyz scanner control circuit 16, an XY stage control circuit 17, a stage displacement detection unit 18, and a computer 13 that controls these circuits.
【００２１】試料テーブル７に設置された被測定用の試
料６表面を、まず光学顕微鏡９で観察し、ＸＹステージ
１０を粗動させて観察位置を特定する。光学顕微鏡９と
探針４との距離Ｌはできるだけ近いことが望ましい。倍
率１００倍の光学顕微鏡の場合、８８μｍ×６６μｍの
範囲を、水平方向０．２５μｍ、垂直方向０．５μｍ程
度の精度で観察することができる。The surface of the sample 6 to be measured set on the sample table 7 is first observed by the optical microscope 9, and the XY stage 10 is roughly moved to specify the observation position. It is desirable that the distance L between the optical microscope 9 and the probe 4 be as short as possible. In the case of an optical microscope with a magnification of 100, a range of 88 μm × 66 μm can be observed with an accuracy of about 0.25 μm in the horizontal direction and 0.5 μm in the vertical direction.
【００２２】次に、所定の観察位置（約１０μｍ×１０
μｍ）をＡＦＭで走査して観察する。この時の分解能
は、水平方向０．１ｎｍ、垂直方向０．０１ｎｍとな
る。前記したように、ＡＦＭにおいては被測定試料の表
面像を得る前にＡＦＭの作動条件の設定、即ちフォース
カーブの測定を行う必要がある。フォースカーブの測定
のためにはカンチレバーの変位を検出する必要がある
が、その変位検出系には、トンネル検出方式、光波干渉
方式及び光てこ方式があり、いずれを用いることもあり
うる。トンネル検出方式は、カンチレバー背面にトンネ
ル電流用探針を近接させて、この探針とカンチレバー間
に流れるトンネル電流が一定値をとるようにトンネル電
流用探針位置を制御しながらカンチレバーの変位を検出
する方法である。原理的には、高感度であるが、トンネ
ル電流用探針とカンチレバー間に原子間力が作用するた
め正確な計測が阻害されるという問題がある。これに対
して光を用いた検出法は、光の輻射圧が非常に小さいた
めにカンチレバー背面に作用する力を無視することがで
きる。Next, a predetermined observation position (about 10 μm × 10
(μm) is observed by scanning with AFM. The resolution at this time is 0.1 nm in the horizontal direction and 0.01 nm in the vertical direction. As described above, in the AFM, it is necessary to set the operating conditions of the AFM, that is, to measure the force curve before obtaining the surface image of the sample to be measured. It is necessary to detect the displacement of the cantilever in order to measure the force curve. The displacement detection system includes a tunnel detection system, a light wave interference system, and an optical lever system, and any of them can be used. The tunnel detection method detects the displacement of the cantilever while controlling the position of the tunnel current probe so that the tunnel current flowing between this probe and the cantilever takes a constant value by bringing the tunnel current probe close to the back of the cantilever. Is the way to do it. In principle, the sensitivity is high, but there is a problem that accurate measurement is impeded by the interatomic force acting between the tunnel current probe and the cantilever. On the other hand, the detection method using light can ignore the force acting on the back surface of the cantilever because the radiation pressure of light is very small.
【００２３】図１のカンチレバー検出器５は、検出方式
がレーザ光による光てこ方式とし、反射レーザ光の受光
面は２分割光電変換面としたものである。探針４が原子
間力の作用を受けて中立の位置から角度Δθだけ変位し
たとすれば、光てこの原理によって反射光は２Δθだけ
シフトした方向へ放射される。カンチレバー３の光反射
点と放射先に設けた２分割光電変換部の受光面との距離
をｈとすれば受光面でのレーザスポットの変位は２ｈΔ
θに拡大される。従って、中立の位置（原子間力が作用
していない位置）で２分割された各受光領域の光出力が
均等であったとすれば、２ｈΔθのレーザスポット変位
によって各領域の出力バランスがくずれ、カンチレバー
の曲がりに比例した差動出力が出る。カンチレバー３
は、引力と斥力とでは逆方向に曲がるので、差動出力の
符号で区別できる。差動出力は検出部１１に送られる。In the cantilever detector 5 of FIG. 1, the detection method is an optical lever method using laser light, and the light receiving surface of the reflected laser light is a two-division photoelectric conversion surface. If the probe 4 is displaced from the neutral position by an angle Δθ under the action of an atomic force, the reflected light is emitted in a direction shifted by 2Δθ by the principle of optical lever. If the distance between the light reflection point of the cantilever 3 and the light receiving surface of the two-division photoelectric conversion portion provided at the radiation destination is h, the displacement of the laser spot on the light receiving surface is 2hΔ.
Expanded to θ. Therefore, if the light output of each light-receiving region divided into two at the neutral position (the position where no interatomic force is acting) is equal, the output balance of each region is disturbed by the laser spot displacement of 2hΔθ, and the cantilever A differential output proportional to the bend is output. Cantilever 3
Can be distinguished by the sign of the differential output because the attractive force and the repulsive force bend in opposite directions. The differential output is sent to the detection unit 11.
【００２４】図４は、本実施例の原子間力設定部１２Ａ
による処理フローを示す図である。フローＦ３０では、
探針４の試料面の接近過程で、少なくとも２つのサンプ
ル点で検出部１１を通じてカンチレバー変位検出値をラ
ッチする。フローＦ３１では、その時点の探針位置（粗
動ステージ８及び又はｘｙｚスキャナ２のｚスキャナの
位置又は制御回路１５、１６の指令位置）を取り込む。
かくしてフォースカーブ上の２つのサンプル点でのカン
チレバー変位検出値と探針位置とが得られる。フローＦ
３２では、各サンプル点のカンチレバー変位検出値Ｖi
と探針位置Ｚiとからカンチレバーに加わった力Ｆiを算
出する。FIG. 4 shows the atomic force setting unit 12A of this embodiment.
It is a figure which shows the processing flow by. In Flow F30,
In the process of approaching the sample surface of the probe 4, at least two sample points latch the cantilever displacement detection value through the detection unit 11. In the flow F31, the probe position at that time (the position of the coarse movement stage 8 and / or the z scanner of the xyz scanner 2 or the command position of the control circuits 15 and 16) is fetched.
Thus, the cantilever displacement detection value and the probe position at the two sample points on the force curve can be obtained. Flow F
At 32, the cantilever displacement detection value V i at each sample point
And the probe position Z i , the force F i applied to the cantilever is calculated.
【数１】Ｖi＝ｃＺｉ ## EQU1 ## V i = cZ i
【数２】Ｆｉ＝ＫＺi 但し、Ｋは剛性 数１のＺiを数２に代入して[Number 2] F i = KZ i where, K is by substituting Z i stiffness number 1 to number 2
【数３】Ｆi＝（Ｋ／ｃ）Ｖi となる。## EQU3 ## F i = (K / c) V i .
【００２５】次にフローＦ３３で、２点のサンプル点の
ＺiとＦi（即ち、Ｚi1とＦi1、Ｚi2とＦi2）とから、力
設定値Ｆth対応の変位検出予測値Ｖth（又はそれになる
探針位置、又はその探針位置になるような移動量）を求
める。例えば２つのサンプル点を通る直線を算出し、力
設定値Ｆthに対応する予測値をその直線から得る。こう
した線形補間（内挿、外挿いずれも可）により予測値Ｖ
thを求める。フローＦ３４では、この力設定値Ｆth（又
はＶth又は位置や移動量）になるように、制御回路１
５、１６を用いて粗動ステージ８、微動ｘｙｚスキャナ
２のｚスキャナを制御する。この制御のもとで実際の計
測を行う。直線化できない例にあっては、３点以上のサ
ンプル点で計測しておき、高次補間を行う。尚、２点
（又は３点以上）の中の１点は接触してＦ＝０になつて
いる点を選ぶと便利である。Next, in a flow F33, the displacement detection prediction value V corresponding to the force setting value F th is calculated from Z i and F i of two sample points (ie, Z i1 and F i1 , Z i2 and F i2 ). th (or the probe position corresponding thereto or the amount of movement to reach the probe position) is obtained. For example, a straight line that passes through two sample points is calculated, and a predicted value corresponding to the force setting value F th is obtained from that straight line. With such linear interpolation (both interpolation and extrapolation are possible), the predicted value V
ask th . In the flow F34, the control circuit 1 is controlled so that the force setting value F th (or V th or the position or movement amount) is reached.
5 and 16 are used to control the coarse movement stage 8 and the fine movement xyz scanner 2 z scanner. Actual measurement is performed under this control. In an example where linearization is not possible, measurement is performed at three or more sample points and high-order interpolation is performed. Incidentally, it is convenient to select a point where one point out of two points (or three points or more) is in contact with F = 0.
【００２６】以上の図４の動作は、探針を試料に接近さ
せる毎に行う。即ち、実際の試料面の計測に際して、探
針を試料面に接近させるが、その接近の都度、図４の動
作を行う。従来例では、フォースカーブを求める計測動
作を行っているが、本実施例では、フォースカーブを求
める計測動作をせずに、代わりに探針の接近の過程で２
点以上のサンプル点にわたって、Ｚ、Ｆ又はＶの計測を
行い、そこから力設定値になるような予測を行い、この
予測になるようなカンチレバー制御を行う。従って、探
針を試料面に衝突させるようなの点の計測は不要であ
る。The above operation of FIG. 4 is performed every time the probe approaches the sample. That is, in actual measurement of the sample surface, the probe is brought close to the sample surface, and the operation shown in FIG. In the conventional example, the measurement operation for obtaining the force curve is performed, but in the present embodiment, the measurement operation for obtaining the force curve is not performed, but instead, in the process of approaching the probe, 2
Z, F, or V is measured over the sampling points equal to or more than the points, and the force set value is predicted from the measured value, and the cantilever control is performed so as to obtain the predicted value. Therefore, it is not necessary to measure the point where the probe collides with the sample surface.
【００２７】Ｚ軸方向変位データは計算機１３に送られ
て処理された上で、モニタ１４によって平面像として拡
大ディスプレイされる。The Z-axis direction displacement data is sent to the computer 13 for processing and then enlarged and displayed as a plane image by the monitor 14.
【００２８】[0028]
【発明の効果】以上実施例を用いて説明したように、本
発明によればＡＦＭの探針を試料に近接させながら測定
するフォースカーブの２点以上のサンプル点から、試料
観察に使用する原子間力に相当するＺ軸座標（カンチレ
バーのＺ軸方向の必要移動距離）を予測演算することが
できる。従って、目標座標でカンチレバーを停止させる
ことができるので、必要以上に深い位置まで探針を進入
させてカンチレバーに過大な曲げを与えたり、試料表面
と探針との衝突で試料や探針に損傷を与える危険がなく
なった。それ故、本発明は、ＡＦＭを用いた正確な試料
表面像の観察に資することができる。As described above with reference to the embodiments, according to the present invention, the atoms used for observing the sample are measured from two or more sample points of the force curve measured while the AFM probe is brought close to the sample. The Z-axis coordinate (required moving distance of the cantilever in the Z-axis direction) corresponding to the inter-force can be predicted and calculated. Therefore, it is possible to stop the cantilever at the target coordinates, so that the probe can be inserted to a deeper position than necessary to bend the cantilever excessively, or the sample or probe can be damaged by the collision between the sample surface and the probe. The danger of giving away is gone. Therefore, the present invention can contribute to the accurate observation of the sample surface image using the AFM.
【図１】実施例に係るＡＦＭの構成を示す図である。FIG. 1 is a diagram showing a configuration of an AFM according to an embodiment.
【図２】ＡＦＭの一般的構成を示す図である。FIG. 2 is a diagram showing a general configuration of an AFM.
【図３】フォースカーブを示す図である。FIG. 3 is a diagram showing a force curve.
【図４】実施例における力設定部１２Ａを中心とするフ
ローチャートである。FIG. 4 is a flowchart focusing on a force setting unit 12A in the embodiment.
１ 原子間力顕微鏡（ＡＦＭ） ２ ｘｙｚスキャナ ３ カンチレバー ４ 探針 ５ カンチレバー変位検出器 ６ 試料 1 Atomic Force Microscope (AFM) 2 xyz scanner 3 cantilever 4 probe 5 cantilever displacement detector 6 sample
Claims (2)
探針に働く力を一定にした状態で試料表面を走査する光
てこ方式の走査型プローブ顕微鏡において、 探針を試料に接近させる毎に、Ｚ方向の移動量とカンチ
レバーの剛性により探針に働く力を演算し、それによ
り、力設定値のカンチレバー変位検出値を求め、力設定
値になった後、その力を一定に制御しながら、平面走査
し、像観察する光てこ方式の走査型プローブ顕微鏡。1. A cantilever having a probe at one end,
In an optical lever type scanning probe microscope that scans the sample surface with the force acting on the probe constant, it works on the probe each time the probe approaches the sample due to the amount of movement in the Z direction and the rigidity of the cantilever. Optical lever type scanning probe that calculates the force, obtains the cantilever displacement detection value of the force setting value, and after the force setting value is reached, performs planar scanning while observing the image while controlling the force constant. microscope.
ーと、 カンチレバーに働く試料の原子間力を光てこ方式で検出
するカンチレバー検出器と、 探針を粗動・微動機構を用いて試料に接近させる毎に、
該機構の移動量（探針の移動量）Ｚとカンチレバーの剛
性Ｋとによりその時の原子間力Ｆを算出し、これから力
設定値Ｆthを得るべきカンチレバー変位検出器の検出予
測値Ｖthを算出する演算手段と、 この検出予測値Ｖthになるように上記粗動・微動機構を
位置制御する制御手段と、 この力設定値になるような一定力制御のもとで試料面の
観察像を得る手段と、より成る原子間力顕微鏡。2. A coarse / fine movement mechanism in the Z direction, a cantilever having this mechanism fixed at one end and a probe at the other end, and a cantilever for detecting the atomic force of the sample acting on the cantilever by an optical lever method. Each time the detector and the probe are brought close to the sample using the coarse and fine movement mechanisms,
The atomic force F at that time is calculated from the movement amount (movement amount of the probe) Z of the mechanism and the rigidity K of the cantilever, and the predicted detection value V th of the cantilever displacement detector that should obtain the force set value F th is calculated from this. The calculation means for calculating, the control means for controlling the position of the coarse / fine movement mechanism so that the detection predicted value V th is obtained, and the observation image of the sample surface under the constant force control so as to obtain the force set value. And an atomic force microscope.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11811694A JP3364531B2 (en) | 1994-05-31 | 1994-05-31 | Optical lever scanning probe microscope and atomic force microscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11811694A JP3364531B2 (en) | 1994-05-31 | 1994-05-31 | Optical lever scanning probe microscope and atomic force microscope |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07325090A true JPH07325090A (en) | 1995-12-12 |
| JP3364531B2 JP3364531B2 (en) | 2003-01-08 |
Family
ID=14728431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11811694A Expired - Fee Related JP3364531B2 (en) | 1994-05-31 | 1994-05-31 | Optical lever scanning probe microscope and atomic force microscope |
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| Country | Link |
|---|---|
| JP (1) | JP3364531B2 (en) |
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| US6989535B2 (en) | 1998-11-20 | 2006-01-24 | Hitachi, Ltd. | Atomic force microscopy, method of measuring surface configuration using the same, and method of producing magnetic recording medium |
| KR100646441B1 (en) * | 2002-02-15 | 2006-11-14 | 피에스아이에이 주식회사 | Improved scanning probe microscope |
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| CN103185812A (en) * | 2011-12-29 | 2013-07-03 | 中国科学院沈阳自动化研究所 | Physical property measurement system and method for material based on probe force curve |
| WO2022065926A1 (en) * | 2020-09-24 | 2022-03-31 | 파크시스템스 주식회사 | Method for measuring characteristics of surface of object to be measured by means of measuring apparatus using variable set point setting, atomic microscope for performing method, and computer program stored in storage medium for performing method |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6989535B2 (en) | 1998-11-20 | 2006-01-24 | Hitachi, Ltd. | Atomic force microscopy, method of measuring surface configuration using the same, and method of producing magnetic recording medium |
| KR100646441B1 (en) * | 2002-02-15 | 2006-11-14 | 피에스아이에이 주식회사 | Improved scanning probe microscope |
| KR100873436B1 (en) * | 2005-03-09 | 2008-12-11 | 가부시키가이샤 시마쓰세사쿠쇼 | Scanning probe microscope |
| KR100904390B1 (en) * | 2005-03-09 | 2009-06-26 | 가부시키가이샤 시마쓰세사쿠쇼 | Scanning probe microscope |
| KR100761059B1 (en) * | 2006-09-29 | 2007-09-21 | 파크시스템스 주식회사 | Scanning probe microscope being able to measure samples having overhang structure |
| US7644447B2 (en) | 2006-09-29 | 2010-01-05 | Park Systems Corp. | Scanning probe microscope capable of measuring samples having overhang structure |
| CN103185812A (en) * | 2011-12-29 | 2013-07-03 | 中国科学院沈阳自动化研究所 | Physical property measurement system and method for material based on probe force curve |
| WO2022065926A1 (en) * | 2020-09-24 | 2022-03-31 | 파크시스템스 주식회사 | Method for measuring characteristics of surface of object to be measured by means of measuring apparatus using variable set point setting, atomic microscope for performing method, and computer program stored in storage medium for performing method |
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| JP3364531B2 (en) | 2003-01-08 |
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