JP3762982B2 - Method and apparatus for adjusting the axis of a transmission electron microscope - Google Patents

Description

【００２７】
ここで、Csは球面収差、zは焦点はずれ量、a₂およびa₃は２回および３回の非点収差、bはレンズ自身が持つコマ収差である。記号上のバーは、その数の複素共役を示している。
【００２８】
式（１）に基づき、散乱電子が形成するＴＥＭ像を計算したものを図２に示す。これは、スポットダイアグラムと呼ばれているものである（村田和美、「光学」 サイエンス社）。ここでは、試料面上の一点から格子状に散乱した電子が像面で観察される位置を計算した。図２（ａ）は、球面収差Ｃｓと焦点ぼけ量ｚのみ考慮して計算したものである。図２（ｂ）〜（ｄ）は、それぞれ２回の非点収差ａ２ 、コマ収差ｂおよび３回の非点収差ａ３ を図２（ａ）の条件に加えて計算したものである。各点は１．９ｍｒａｄステップで散乱された散乱電子のＴＥＭ像上の位置を点として描いている。
【００２９】
Cs =1.5x10^-3、z = -7x10^-6 (不足焦点)|a₂|=5x10^-6、|b|=1x10^-5、|a₃|=1x10^{- 5}で計算した。矢印15b〜15dは、a₂、b、およびa₃によって受ける点の動きの方向である。○印12は散乱角（w）が0の方向を示している。２回の非点収差a₂により、火面は楕円になり、３回の非点収差a₃により３角形に歪んでくる。２回や３回の非点によって火面は円形からゆがむものの、重心の位置は○印から動いていない性質が重要である。
【００３０】
一方、コマ収差によると、図2(c)に示されるように、火面はほぼ平行移動する。火面の中心(□印12c)は、式2から計算されるように散乱角で3.3 mradずれる。コマフリー軸調整とは、レンズ自身がもつコマ収差bをうち消すように入射電子を傾斜させ、実効的にコマ収差をなくすことを意味する。式(2)によれば、その傾斜角度はw=-b/2Csとなる。これは図２(c)における火面の中心(□印)に他ならない。したがって、本発明による軸調整方法は、コマフリー軸調整法を提供していることになる。
【００３１】
図３は、本発明による実施の形態を示したものである。コマ収差が残存している状態(a)から、入射電子を傾斜させることにより、火面16の中心と透過スポット17とを一致させ(c)、コマフリー軸調整ができていることが分かる。
【００３２】
本発明では、試料により散乱された電子が形成する火面を用いて軸調整を行う。火面を観察するためには、入射電子を試料面上の小さな領域に収束するとともに、大きな焦点ぼけを設定する必要がある。試料面上の入射電子の最小プローブ径をｐ、焦点ぼけ量ｚ、コマフリー軸からのミスアライメント量をαとすると、上述のようにｐ/｜ｚ｜＜αの条件が必要であり、一般にＴＥＭで要求されるミスアライメント量αは１ｍｒａｄ未満であることから、ｐ/｜ｚ｜＜α＜０．００１の条件が必要である。最小プローブ径ｐは最近の電子顕微鏡では１〜１０ｎｍ程度であると考えられるので、一般に必要な焦点ぼけ量ｚは１〜１０μｍ以上となる。
【００３３】
なお、以上の実施の形態では、TEM像の焦点をぼけさせるために、試料の位置を変化させたが、これに限ることはなく、中間レンズの焦点を変化させる、加速電圧を変化させる、対物レンズの焦点距離を変化させる、などの方法を用いてもよい。
【００３４】
上述の実施の形態（図３）では、TEM像は不足焦点で観察したが、過焦点で観察し散乱された電子の強度のちょうど中心に透過スポットを位置するようにすることによっても同じ効果が得られる。
【００３５】
図3の実施の形態では、試料は非晶質試料であったが、結晶性試料を用いても同様の軸調整が可能である。その場合には、多数の回折スポットが観察されるので、そのスポットが回転対称をとるように軸調整することにより、同様の軸調整が可能になる。
【００３６】
１１２４３４３９３７２５０＿０は、他の実施の形態を示したものである。ＴＥＭ１９に加え、画像取得装置３０、画像解析装置３１を備えている。画像取得装置３０では、ＴＥＭ像２９を取得し、当該ＴＥＭ像２９を画像解析装置３１に転送する。画像解析装置３１では、ＴＥＭ像２９中の火面の形状、火面の位置、又は透過電子により形成されるスポットの位置を検出する。さらに、画像解析装置３１では、そのずれ量からコマ収差を式（２）に基づき計算する。
【００３７】
計算結果に基づき、画像解析装置31は偏向装置制御装置22へと必要な偏向量を指示し、それにより偏向装置21が駆動され入射電子23の方向が設定され、コマフリー軸調整が行われる。画像取得装置30を用いることにより、オペレーターが目視でやるよりも高精度にコマフリー軸調整が可能になる。
【００３８】
【発明の効果】
従来は電子線を傾斜させて複数枚の画像を観察しそれを比較していたが、本発明では、１枚の画像から軸調整に必要な情報が得られる。また、解析に周波数解析などを必要としない。本発明は、一般に電子顕微鏡観察に用いる焦点(数100nm)よりも大きな焦点はずれ量を用い、さらに、試料面上に電子線を収束している点で、従来全く行われていなかった方法である。この条件で観察された図形から、対物レンズの軸調整ができるという報告例は全くなく、検討された報告例もなかった。
【００３９】
従来よりも簡単な原理および装置に基づき、一枚の画像で軸調整できることから、複数の画像の観察・解析が必要な従来手法と比べ、即時性に優れている。また、火面の中心に入射電子を傾斜すればよいだけであるので、TEMが一般に備えている蛍光板上で調整可能で、複雑な電子偏向システムや画像解析システムを必要としない。その結果、安価に軸調整が行える。
【図面の簡単な説明】
【図１】図１は、本発明による軸調整法の実施の形態を示す概念図である。
【図２】図２は、火面の計算結果を示す図である。
【図３】図３は、本発明による軸調整法の実施の形態における、(a)は軸調整前、(b)は軸調整中、(c)は軸調整が完了したときのTEM像を示す図面代用写真である。
【図４】図４は、本発明による他の実施の形態を示す概念図である。
【符号の説明】
1… 入射電子
2…光軸
3…正焦点試料位置
4…試料
5a…透過電子
5b〜5d…散乱電子
5e…火面
6…対物レンズ
7…TEM像
8a…透過スポット（透過電子5aの投影位置）
8b…火面（散乱電子5bの投影位置）
8c…プローブ像（散乱電子5cの投影位置）
8d…バックグラウンド（散乱電子5dの投影位置）
9…散乱角度に対する電子線の投影位置の変化
10…光軸の位置
11a…透過電子5aの投影位置
11b…散乱電子5bの投影位置
11c…散乱電子5cの投影位置
11d…散乱電子5dの投影位置
12…散乱角が0の軸
13…火面（コマ、２回および３回非点が無い場合）
14a…スポットダイヤグラム（コマ、２回および３回非点が無い場合）
14b…スポットダイヤグラム（コマおよび３回非点が無い場合）
14c…スポットダイヤグラム（２回および３回非点が無い場合）
14d…スポットダイヤグラム（コマおよび２回非点が無い場合）
15b…２回非点による散乱電子の位置の動き
15c…コマによる散乱電子の位置の動き
15d…３回非点による散乱電子の位置の動き
16…火面
17…透過スポット
18…プローブ像
19…透過電子顕微鏡
20…電子銃
21…偏向手段
22…偏向手段制御装置
23…入射電子
24…透過電子
25…散乱電子
26…試料
27…対物レンズ
28…結像レンズ系
29…TEM像
30…画像取得装置
31…画像解析装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an axis adjustment method for a transmission electron microscope and an apparatus for performing the method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a transmission electron microscope (hereinafter referred to as TEM) has been actively used as a material evaluation method for a minute region. In order to observe an image with high spatial resolution by TEM, it is essential to perform appropriate axis adjustment. The axis adjustment is to appropriately set the astigmatism, the focal point, the incident direction of incident electrons, and the like for the objective lens used for observing the sample. In particular, since the direction and astigmatism of incident electrons greatly affect the spatial resolution of the obtained TEM image, it is desired to easily and easily adjust this.
[0003]
Conventionally, a method called a voltage axis adjustment method has been used for axis adjustment of a TEM (for example, Japanese Patent Laid-Open No. 60-167248, Japanese Patent Publication No. 03-39378, registration 1672379). This is because the TEM acceleration voltage is slightly modulated (for example, about 1 kV with respect to an acceleration voltage of 200 kV), the change in the position of the TEM image due to the voltage modulation is observed, and the incident electrons are minimized so that the position variation of the TEM image is minimized. The direction is adjusted.
[0004]
In addition, a current axis adjustment method is also used in which the current of the TEM objective lens is modulated to adjust the direction of incident electrons so that the positional fluctuation of the TEM image is minimized. The voltage axis adjustment method and the current axis adjustment method are currently widely used because they can be performed on a fluorescent screen without requiring a special device.
[0005]
On the other hand, with recent improvements in TEM accuracy and resolution, the need for new axis adjustment methods to replace voltage axis adjustment and current axis adjustment was pointed out (F. Zemlin, etal., Ultramicroscopy, vol. 3). (1978), p49). This is to adjust the direction of incident electrons in a direction where there is no coma aberration, and is called a coma-free axis adjustment method. Several methods have been proposed for the frame-free axis adjustment method.
[0006]
All of the methods proposed so far observe multiple TEM images by changing the direction of the incident electrons, and change the focus, astigmatism and position of the TEM image as the direction of the incident electrons changes. An appropriate electron beam incident direction is detected by detection (for example, the following patent is given as a similar method: Japanese Patent Laid-Open No. 60-91540, Japanese Patent Publication No. 03-78738, registration 1711234). In order to perform the frame-free axis adjustment method, a special device that adjusts the direction of incident electrons with high accuracy and a device that calculates the astigmatism and focus by Fourier transform of the TEM image are required.
[0007]
[Problems to be solved by the invention]
In order to use TEM with high spatial resolution, frame-free axis adjustment is required. However, the coma-free axis adjustment method proposed so far could not be used with a general TEM apparatus. Therefore, it is not generally used yet compared with the voltage axis adjustment method and the current axis adjustment method. The present invention provides a frame-free axis adjustment method based on a principle and means different from the conventional one. The contents of the problems to be solved by the present invention will be described below.
[0008]
In the case of the conventional frame-free axis adjustment method, at least two or more TEM images are photographed by tilting incident electrons. An electronic deflection system that tilts incident electrons with high accuracy, a camera that acquires TEM images online, and a system that calculates the focus and astigmatism of TEM images are required. Since the image to be analyzed is a high spatial resolution TEM image, in order to acquire it, a stable sample stage and appropriate imaging conditions and samples are required. Furthermore, in order to adjust the axis by feeding back the measurement results to the TEM, a calculation based on a complex algorithm is required, which is not an immediate method.
[0009]
[Means for Solving the Problems]
As a method for solving the above-described problems, the present invention provides a new axis adjustment method.
[0010]
That is, the present invention relates to a frame-free axis adjustment method using a fire surface, and converges incident electrons in the vicinity of a sample using a converging lens system, and observes an electron microscope image using an objective lens and an imaging lens system. In a transmission electron microscope, formed by scattered electrons scattered by the sample,
The center of the caustic observed in the electron microscope image, such that the sample permeated spots by Ri Ru formed to electrons is located, and adjusting the incident direction of the incident electrons, transmitted electrons This is a method for adjusting the frame-free axis of a microscope.
[0011]
The present invention also relates to a method for adjusting a frame-free axis using scattered electrons, and converges incident electrons in the vicinity of a sample using a converging lens system, and observes an electron microscope image using an objective lens and an imaging lens system. In a transmission electron microscope, formed by scattered electrons scattered by the sample,
The center of the intensity of the scattered electrons observed in the electron microscope image, such that the sample permeated spots by Ri Ru formed to electrons is located, and adjusting the incident direction of the incident electron, This is a frame-free axis adjustment method for a transmission electron microscope.
[0012]
The present invention also relates to a frame-free axis adjustment method using a probe image, in which incident electrons are converged in the vicinity of a sample using a converging lens system, and an electron microscope image is observed using an objective lens and an imaging lens system. in transmission electron microscopy, it is formed by scattering electrons scattered by the sample, wherein the center of the probe image to be observed in an electron microscope image, such that the sample permeated spots by Ri Ru formed to electrons is located, A method for adjusting a frame-free axis of a transmission electron microscope, wherein an incident direction of the incident electrons is adjusted.
[0016]
Further, the present invention relates to a condition relating to a defocus amount at the time of photographing an electron microscope image. In each of the above methods, the minimum probe diameter of the incident electrons is p, and a defocus amount when observing the electron microscope image ( however, The axis of the transmission electron microscope is characterized in that the value of p / | z | is smaller than 0.001 where z is the amount of defocusing (distance between the sample and the normal focus sample position). It is an adjustment method. The upper limit of the numerical value of p / | z | is defined as follows. In the present invention,
The amount of misalignment is detected by the probe image and the spot shift caused by transmitted electrons. The amount of deviation is α | z | if the misalignment angle is α, and if the value is larger than the probe diameter p (α | z |> p, ie, p / | z | <α). Therefore, the remaining misalignment can be detected. On the other hand, in the normal TEM frame-free axis adjustment, the amount of misalignment α is required to be 1 mrad or less (α <0.001). From the above conditions, p / | z | <α <0.001 is derived, and p / | z | <0.001.
[0017]
In addition, the present invention relates to an apparatus incorporating an axis adjustment method, and performs each of the axis adjustment methods described above in a transmission electron microscope including an image acquisition device for detecting an electron microscope image and an analysis device for the electron microscope image. Therefore, the transmission electron microscope has a function of detecting a position of a spot formed by electrons transmitted through the sample .
[0018]
In the frame-free axis adjustment method provided by the present invention, it is only necessary to observe one TEM image and adjust the direction of incident electrons while viewing the TEM image. For example, in one embodiment, the inclination angle of incident electrons may be adjusted so that the transmission spot formed by the transmission electrons coincides with the center of the fire surface due to the scattered electrons.
The minimum equipment required to use the principle of the present invention is a device that finely focuses incident electrons, a device that forms a defocused TEM image, and a device that observes a TEM image. In many cases, it is an existing device.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an example of an embodiment of axis adjustment of a transmission electron microscope (TEM) according to the present invention. In the present invention, a small region of the sample 4 is irradiated with the incident electrons 1 and a TEM image 7 that is largely out of focus than that normally used in TEM is observed. In order to observe a TEM image that is largely out of focus, in the present embodiment, the sample 4 is closer to the objective lens 6 side than the regular focus sample position 3 (position where the focus is achieved).
[0020]
In the case of the method and apparatus of the present invention, the value of the distance between the sample 4 and the regular focus sample position 3 is, for example, 1 μm or more. This value is much larger than the defocus amount generally used in TEM. By moving the sample 4 to the objective lens 6 side, the observed TEM image 7 becomes an underfocus image.
[0021]
The electrons 5a transmitted through the sample are observed as transmission spots 8b in the TEM image 7. The scattered electrons scattered by the sample form a fire surface 5e. The fire surface 5e is often observed as a circle in the TEM image 7 as a region having a high electron density (fire surface 8b). In the scattered electrons 5c scattered at a high angle, the amount of defocus caused by the movement of the sample 4 is canceled by the focal length shortened by the spherical aberration of the objective lens 6.
[0022]
That is, the scattered electrons 5c scattered by the sample 4 are focused on the TEM image 7. This is considered to be a probe image 8c on the sample surface. The probe image is an image formed by canceling out the aberration (spherical aberration and astigmatism) of the objective lens and the defocus amount. Further, the scattered electrons 5d scattered at a wide angle are projected outside the fire surface 8b to form a background 8d. The change 9 of the electron position on the TEM image plane when the scattering angle is changed is indicated by a curve.
[0023]
The positions of the fire surface 8b and the probe image 8c do not depend on the direction of the incident electrons 1 and are constant. On the other hand, when the direction of the incident electrons is changed, the position of the transmission spot 8a changes. In this figure, since the objective lens 6 has no coma aberration, the optical axis 2 is a coma-free axis, and the direction thereof is the center of the fire surface 8b (or the position of the probe image 8c). If the electron beam is tilted in that direction, the axis is adjusted.
[0024]
Even when the axis is adjusted in an objective lens having coma aberration, if the transmitted spot is made to coincide with the center of the fire surface, the coma-free axis adjustment is performed. The fact that the axis adjustment of the transmission electron microscope according to the present invention is the conventionally reported frame-free axis adjustment is shown as follows.
[0025]
Using the complex number representation of lens aberration (K. Ishizuka, Ultramicroscopy, 55 (1994) 407), the electron projection position d when the electron is tilted w = αexp (iφ) from the optical axis is Indicated.
[0026]
[Formula 1]

[0027]
Here, Cs is a spherical aberration, z is a defocus amount, a ₂ and a ₃ are astigmatisms 2 and 3, and b is a coma aberration of the lens itself. The bar above the symbol indicates the complex conjugate of that number.
[0028]
FIG. 2 shows a TEM image calculated by scattered electrons based on the formula (1). This is what is called a spot diagram (Kazumi Murata, “Optical” Science, Inc.). Here, the position where electrons scattered in a lattice form from one point on the sample surface were observed on the image plane was calculated. FIG. 2A shows the calculation taking into consideration only the spherical aberration Cs and the amount of defocus z. 2 (b) to 2 (d) are calculated by adding two astigmatisms a2, coma aberration b, and three astigmatisms a3 in addition to the conditions of FIG. 2 (a). Each point draws the position on the TEM image of the scattered electrons scattered in the 1.9 mrad step as a point.
[0029]
Cs = 1.5x10 ^-3 , z = -7x10 ^-6 (Insufficient ^{_{focus) | a 2 | = 5x10 -6}} , | b | = 1x10 -5, | a 3 | = 1x10 - calculated at ^5. Arrow 15b~15d is the direction of movement of the point receiving the a _2, b, and a _3. A circle 12 indicates a direction in which the scattering angle (w) is zero. The fire surface becomes elliptic due to _two astigmatisms a ₂ , and is distorted into a triangle due to three astigmatisms a ₃ . Although the fire surface is distorted from a circle by two or three astigmatisms, it is important that the center of gravity does not move from the circle.
[0030]
On the other hand, according to coma aberration, as shown in FIG. The center of the fire surface (□ mark 12c) deviates by 3.3 mrad in the scattering angle as calculated from Equation 2. The coma-free axis adjustment means that the incident electrons are tilted so as to eliminate the coma aberration b of the lens itself, thereby effectively eliminating the coma aberration. According to Equation (2), the inclination angle is w = −b / 2Cs. This is nothing but the center of the fire surface (marked with □) in Fig. 2 (c). Therefore, the axis adjustment method according to the present invention provides a frame-free axis adjustment method.
[0031]
FIG. 3 shows an embodiment according to the present invention. From the state where the coma aberration remains (a), it can be seen that by tilting the incident electrons, the center of the fire surface 16 and the transmission spot 17 are matched (c), and the coma-free axis adjustment can be performed.
[0032]
In the present invention, the axis is adjusted using a fire surface formed by electrons scattered by the sample. In order to observe the fire surface, it is necessary to focus the incident electrons on a small area on the sample surface and to set a large defocus. Assuming that the minimum probe diameter of incident electrons on the sample surface is p, the defocus amount z, and the misalignment amount from the coma-free axis is α, the condition of p / | z | <α is necessary as described above. Since the misalignment amount α required by the TEM is less than 1 mrad, the condition of p / | z | <α <0.001 is necessary. Since the minimum probe diameter p is considered to be about 1 to 10 nm in recent electron microscopes, generally the required defocus amount z is 1 to 10 μm or more.
[0033]
In the above embodiment, the position of the sample is changed in order to blur the focus of the TEM image. However, the present invention is not limited to this. The focus of the intermediate lens is changed, the acceleration voltage is changed, and the objective is changed. A method such as changing the focal length of the lens may be used.
[0034]
In the above-described embodiment (FIG. 3), the TEM image is observed with an insufficient focal point. However, the same effect can be obtained by locating the transmission spot at the exact center of the scattered electron intensity. can get.
[0035]
In the embodiment of FIG. 3, the sample is an amorphous sample, but the same axis adjustment is possible even when a crystalline sample is used. In that case, since many diffraction spots are observed, the same axis adjustment can be performed by adjusting the axes so that the spots are rotationally symmetric.
[0036]
1124333937250_0 shows another embodiment. In addition to the TEM 19, an image acquisition device 30 and an image analysis device 31 are provided. The image acquisition device 30 acquires a TEM image 29 and transfers the TEM image 29 to the image analysis device 31. The image analysis device 31 detects the shape of the fire surface in the TEM image 29, the position of the fire surface, or the position of a spot formed by transmitted electrons . Further, the image analysis device 31 calculates the coma aberration from the deviation amount based on the equation (2).
[0037]
Based on the calculation result, the image analysis device 31 instructs the deflection device control device 22 on the necessary deflection amount, whereby the deflection device 21 is driven, the direction of the incident electrons 23 is set, and the frame-free axis adjustment is performed. By using the image acquisition device 30, the frame-free axis adjustment can be performed with higher accuracy than the operator can visually observe.
[0038]
【The invention's effect】
Conventionally, an electron beam is tilted and a plurality of images are observed and compared. In the present invention, information necessary for axis adjustment can be obtained from one image. Moreover, frequency analysis is not required for analysis. The present invention is a method that has never been performed in the past in that it uses a defocus amount larger than the focal point (several hundred nm) that is generally used for electron microscope observation, and further converges the electron beam on the sample surface. . There was no report example that the axis of the objective lens could be adjusted from the figure observed under these conditions, and there was no report example examined.
[0039]
Since the axis can be adjusted with a single image based on a simpler principle and apparatus than in the past, it is superior in immediacy compared with the conventional method that requires observation and analysis of a plurality of images. Further, since it is only necessary to incline incident electrons at the center of the fire surface, adjustment is possible on a fluorescent screen generally provided in the TEM, and a complicated electron deflection system or image analysis system is not required. As a result, the shaft can be adjusted at a low cost.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an embodiment of an axis adjustment method according to the present invention.
FIG. 2 is a diagram showing a calculation result of a fire surface.
FIGS. 3A and 3B are diagrams showing an embodiment of an axis adjustment method according to the present invention, in which (a) is before axis adjustment, (b) is during axis adjustment, and (c) is a TEM image when axis adjustment is completed. It is a drawing substitute photograph shown.
FIG. 4 is a conceptual diagram showing another embodiment according to the present invention.
[Explanation of symbols]
1 ... Incident electrons
2 ... Optical axis
3 ... Focus sample position
4 ... Sample
5a ... Transmission electron
5b to 5d ... scattered electrons
5e… Fire surface
6 ... Objective lens
7 ... TEM image
8a: Transmission spot (projection position of transmission electron 5a)
8b ... Fire surface (projection position of scattered electrons 5b)
8c ... probe image (projection position of scattered electrons 5c)
8d ... Background (projection position of scattered electrons 5d)
9 ... Change of electron beam projection position with respect to scattering angle
10 ... Optical axis position
11a: Projection position of transmission electron 5a
11b: Projection position of scattered electrons 5b
11c: Projection position of scattered electrons 5c
11d: Projection position of scattered electrons 5d
12 ... Axis with zero scattering angle
13 ... Fire (when there is no astigmatism, 2 times and 3 times)
14a ... Spot diagram (when there is no astigmatism, 2 times and 3 times)
14b… Spot diagram (when there are no frames and three astigmatisms)
14c ... Spot diagram (when there is no astigmatism twice and three times)
14d ... Spot diagram (when there is no frame and astigmatism twice)
15b: Movement of scattered electron position due to astigmatism twice
15c: Movement of scattered electron position by top
15d: Movement of scattered electrons due to astigmatism three times
16 ... Fire surface
17 ... Transmission spot
18 ... probe image
19 ... Transmission electron microscope
20 ... electron gun
21: Deflection means
22 ... Deflection means control device
23 ... Incident electrons
24 ... Transmission electron
25 ... scattered electrons
26 ... Sample
27… Objective lens
28 ... imaging lens system
29 ... TEM image
30 ... Image acquisition device
31 ... Image analyzer

Claims (5)

  In the transmission electron microscope, the incident electrons are converged in the vicinity of the sample using a converging lens system, and an electron microscope image is observed using an objective lens and an imaging lens system. A transmission electron microscope frame characterized by adjusting the incident direction of the incident electrons so that a spot formed by electrons transmitted through the sample is positioned at the center of the fire surface observed in the electron microscope image. Free axis adjustment method.   In the transmission electron microscope, the incident electrons are converged in the vicinity of the sample using a converging lens system, and an electron microscope image is observed using an objective lens and an imaging lens system. A transmission electron microscope characterized by adjusting the incident direction of the incident electrons so that a spot formed by electrons transmitted through the sample is positioned at the center of the intensity of scattered electrons observed in an electron microscope image The frame-free axis adjustment method. In the transmission electron microscope, the incident electrons are converged in the vicinity of the sample using a converging lens system, and an electron microscope image is observed using an objective lens and an imaging lens system. The incident direction of the incident electrons is adjusted so that a spot formed by electrons transmitted through the sample is positioned at the center of the probe image on the sample surface observed in the electron microscope image. How to adjust the frame free axis of an electron microscope. The method according to any one of claims 1 to 3, the minimum probe diameter of the incident electron p, the defocus amount at the time of observing an electron microscope image (however, the defocus amount and the and the sample positive focal sample A method for adjusting an axis of a transmission electron microscope, characterized in that the value of p / | z | is smaller than 0.001 when the distance to the position is z. In the transmission electron microscope provided with the image acquisition apparatus for detecting an electron microscope image, and the analysis apparatus of the said electron microscope image, in order to perform the axis adjustment method in any one of Claim 1 thru | or 4 , the sample was permeate | transmitted A transmission electron microscope having a function of detecting a position of a spot formed by electrons.

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