JPH07282767A - Scanning electron microscope - Google Patents

Abstract

PURPOSE:To reduce emission of scattered electrons outside a sample, and enhance resolution of a microscope by performing operation with specific constitution in a spin polarized scanning electron microscope to obtain a magnetic domain image by detecting a spin condition of secondary electrons emitted from the sample. CONSTITUTION:A probe electron beam is made incident at a vertical or near- vertical angle on a surface of a sample 2, and preferably, most of generated secondary electrons are introduced to a spin detector by a secondary electron collecting means and a transfer means being a secondary electron collecting electrode 5 and a deflection electrode (a spherical surface deflecting system 6) arranged between an objective lens 8 of an electron gun and the sample 2.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は磁区観察用走査電子顕微
鏡に関し、特に高分解能磁区観察が可能なスピン偏極走
査電子顕微鏡に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope for observing magnetic domains, and more particularly to a spin polarized scanning electron microscope capable of observing high resolution magnetic domains.

【０００２】[0002]

【従来の技術】試料から放出される２次電子のスピン状
態を検出して磁区像を得るスピン偏極走査電子顕微鏡に
ついては、小池他特開平０５−６８０５９や、シュアイ
ンフェイン他 レビュ サイエンス インスツルメント
Vol. 61, 2501(1990)(scheinfein et al.、Rev. Sci.
Instrum. Vol. 61, 2501(1990))等に開示されている。
スピン偏極走査電子顕微鏡においては、２次電子のスピ
ン状態を検出するスピン検出器の検出効率は、従来の走
査電子顕微鏡において２次電子の強度を検出する電子検
出器の検出効率に比して４桁も低い。そのため、スピン
偏極走査電子顕微鏡においては、試料直上に２次電子収
集電極を配置し、できるだけ多くの２次電子を収集して
いる。この２次電子収集電極との空間的干渉を避けるた
め、プローブ電子線は試料面斜め上方から試料に入射し
ている。2. Description of the Related Art A spin-polarized scanning electron microscope for detecting a spin state of secondary electrons emitted from a sample to obtain a magnetic domain image is disclosed in Koike et al., JP-A-05-68059 and Sure Infein et al., Review Science Instruments. Ment
Vol. 61, 2501 (1990) (scheinfein et al., Rev. Sci.
Instrum. Vol. 61, 2501 (1990)) and the like.
In a spin-polarized scanning electron microscope, the detection efficiency of a spin detector that detects the spin state of secondary electrons is higher than the detection efficiency of an electron detector that detects the intensity of secondary electrons in a conventional scanning electron microscope. 4 digits low. Therefore, in the spin-polarized scanning electron microscope, a secondary electron collecting electrode is arranged immediately above the sample to collect as many secondary electrons as possible. In order to avoid spatial interference with the secondary electron collecting electrode, the probe electron beam is incident on the sample obliquely above the sample surface.

【０００３】一方、２次電子収集電極とプローブ電子線
の空間的干渉を無くし、かつプローブ電子線を試料面上
方法線方向から試料に入射して、放出２次電子を試料直
上に配置した２次電子収集電極によって収集し、円筒偏
向電極を介して電子検出器へ導く方式は、試料表面の電
位を測定する走査電子顕微鏡について、メンツェル他ス
キャニング エレクトロン マイクロスコピ 1981/I,3
05 （Menzel et al.,Scanning Electron Miroscopy/19
81/I,305)に開示されている。On the other hand, spatial interference between the secondary electron collecting electrode and the probe electron beam is eliminated, and the probe electron beam is incident on the sample from the direction of the method line on the sample surface, and the emitted secondary electrons are arranged immediately above the sample. The method of collecting by the secondary electron collecting electrode and guiding it to the electron detector through the cylindrical deflection electrode is the scanning electron microscope which measures the potential of the sample surface, Menzel et al. Scanning Electron Microscopy 1981 / I, 3
05 (Menzel et al., Scanning Electron Miroscopy / 19
81 / I, 305).

【０００４】[0004]

【発明が解決しようとする課題】図１に示す様に、プロ
ーブ電子線１が斜め上方から試料２に入射した場合、試
料内部で散乱されたプローブ電子線３が入射領域よりも
広い領域から試料外に飛び出し、これら散乱電子によっ
ても２次電子４が生成されるため、２次電子の放出領域
はプローブ電子線の入射領域よりも広くなって高い空間
分解能が得られない。また、Menzel等の実施例に示され
る２次電子収集転送光学系の目的は２次電子のエネルギ
ー分析にあるため、エネルギー分解能に重点を置いて、
偏向電極としては収束作用が１次元方向しか無い円筒偏
向電極を330 eVの通過エネルギーで用いており、大きな
透過率が得られない。As shown in FIG. 1, when the probe electron beam 1 is incident on the sample 2 obliquely from above, the probe electron beam 3 scattered inside the sample is sampled from a region wider than the incident region. Since secondary electrons 4 are generated by these scattered electrons as well as the scattered electrons, the secondary electron emission region is wider than the probe electron beam incident region, and high spatial resolution cannot be obtained. Further, since the purpose of the secondary electron collection and transfer optical system shown in the embodiment of Menzel et al. Is to analyze the energy of secondary electrons, emphasis is placed on energy resolution,
As the deflection electrode, a cylindrical deflection electrode having a converging action only in the one-dimensional direction is used with a passage energy of 330 eV, and a large transmittance cannot be obtained.

【０００５】本発明が解決しようとする課題は散乱電子
の試料外放出を極力少なくなるようにして、２次電子の
放出領域をプローブ電子線の入射領域程度にし、かつ放
出２次電子を試料からスピン検出器へ効率良く導いて、
スピン偏極走査電子顕微鏡の分解能を向上させることに
ある。The problem to be solved by the present invention is to minimize the emission of scattered electrons out of the sample as much as possible so that the emission region of secondary electrons is set to the incident region of the probe electron beam and the emitted secondary electrons are emitted from the sample. Efficiently guide to the spin detector,
It is to improve the resolution of a spin polarized scanning electron microscope.

【０００６】[0006]

【課題を解決するための手段】上記課題は、プローブ電
子線を試料面に垂直もしくはそれに近い角度で入射し、
発生した２次電子を、電子銃と試料の間に配置した２次
電子収集電極と350 eV以上の通過エネルギーで動作させ
た球面偏向器によって、効率良くスピン検出器へ導くこ
とで解決できる。[Means for Solving the Problems] The above problem is that the probe electron beam is incident on the sample surface at an angle perpendicular to or close to it.
This can be solved by efficiently guiding the generated secondary electrons to the spin detector by means of the secondary electron collecting electrode arranged between the electron gun and the sample and the spherical deflector operated with passing energy of 350 eV or more.

【０００７】[0007]

【作用】図２に示す様に、プローブ電子線１を試料面方
線方向から入射した場合、散乱電子３の大部分は試料内
部に留まって、試料面から放出されるものは極めて少量
となり、２次電子の大部分はプローブ電子線の照射領域
から放出される。２次電子転送に用いる球面偏向電極は
２次元収束特性を有するため電子線の空間的広がりを小
さくすることができ、また、この偏向電極の通過エネル
ギーを大きくすることで、２次電子のエネルギーの広が
りに起因する電子線の広がりを小さくすることができ
て、２次電子を効率良くスピン検出器へ導くことができ
る。これにより、ほぼプローブ電子線の線径で与えられ
る高い分解能が得られる。As shown in FIG. 2, when the probe electron beam 1 is incident from the direction normal to the sample surface, most of the scattered electrons 3 remain inside the sample and the amount emitted from the sample surface becomes extremely small. Most of the secondary electrons are emitted from the irradiation area of the probe electron beam. Since the spherical deflection electrode used for secondary electron transfer has a two-dimensional converging characteristic, it is possible to reduce the spatial spread of the electron beam, and by increasing the passing energy of this deflection electrode, the secondary electron energy The spread of the electron beam due to the spread can be reduced, and the secondary electrons can be efficiently guided to the spin detector. As a result, a high resolution, which is almost given by the diameter of the probe electron beam, can be obtained.

【０００８】[0008]

【実施例】以下図を用いて、本発明によるスピン偏極走
査電子顕微鏡の構成を詳細に説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the spin polarized scanning electron microscope according to the present invention will be described in detail below with reference to the drawings.

【０００９】図３は本発明によるのスピン偏極走査電子
顕微鏡のプローブ電子線照射及び２次電子収集転送部の
実施例を示したものである。FIG. 3 shows an embodiment of the probe electron beam irradiation and secondary electron collecting and transferring section of the spin polarized scanning electron microscope according to the present invention.

【００１０】本発明の２次電子収集転送部は２次電子収
集電極５、球面偏向器６、及び静電レンズ７より構成さ
れ、電子銃の対物レンズ８と試料３の間に配置されてい
る。球面偏向器の対物レンズ側電極には試料面と垂直方
向に穴が開けられており、電子銃からのプローブ電子線
を試料面に垂直入射させることができる。２次電子収集
電極には試料に対して＋５００Ｖの電圧が印加されてお
り、放出された２次電子の大部分を収集することができ
る。この収集電極で収集された２次電子は、500 eVのエ
ネルギーを持って球面偏向器を通過し、軌道を９０度偏
向されれた後、静電レンズ７を通してスピン検出器へと
導かれる。The secondary electron collecting / transferring unit of the present invention comprises a secondary electron collecting electrode 5, a spherical deflector 6, and an electrostatic lens 7, and is arranged between the objective lens 8 of the electron gun and the sample 3. . A hole is formed in the objective lens side electrode of the spherical deflector in a direction perpendicular to the sample surface, and a probe electron beam from an electron gun can be vertically incident on the sample surface. A voltage of +500 V is applied to the secondary electron collecting electrode with respect to the sample, and most of the emitted secondary electrons can be collected. The secondary electrons collected by this collecting electrode pass through the spherical deflector with energy of 500 eV, are deflected by 90 degrees on the trajectory, and are then guided to the spin detector through the electrostatic lens 7.

【００１１】[0011]

【発明の効果】以上詳述したように、本発明によればス
ピン偏極走査電子顕微鏡の空間分解能を大幅に向上させ
ることができ、高密度磁気記録の記録状態の観察等その
工業的価値は非常に高いものである。As described in detail above, according to the present invention, the spatial resolution of the spin polarized scanning electron microscope can be greatly improved, and its industrial value such as observation of the recording state of high density magnetic recording is high. It is very expensive.

【図面の簡単な説明】[Brief description of drawings]

【図１】斜め入射電子線に対する２次電子の放出領域を
説明する模式図。FIG. 1 is a schematic diagram illustrating a secondary electron emission region with respect to an obliquely incident electron beam.

【図２】垂直入射電子線に対する２次電子の放出領域を
説明する模式図。FIG. 2 is a schematic diagram illustrating a secondary electron emission region with respect to a vertically incident electron beam.

【図３】本発明の実施例に係わるプローブ電子線照射及
び２次電子収集転送部を示す断面図。FIG. 3 is a cross-sectional view showing a probe electron beam irradiation and a secondary electron collecting / transferring unit according to an embodiment of the present invention.

【符号の説明】[Explanation of symbols]

１…プローブ電子線、２…試料、３…散乱電子、４…２
次電子、５…２次電子収集電極、６…球面偏向器、７…
静電レンズ、８…対物レンズ。1 ... Probe electron beam, 2 ... Sample, 3 ... Scattered electron, 4 ... 2
Secondary electron, 5 ... Secondary electron collecting electrode, 6 ... Spherical deflector, 7 ...
Electrostatic lens, 8 ... Objective lens.

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】試料から放出される２次電子のスピン状態
を検出して磁区像を得るスピン偏極走査電子顕微鏡にお
いて、プローブ電子線を試料面に垂直もしくはそれに近
い角度で入射し、発生した２次電子の大部分を、電子銃
の対物レンズと試料の間に配置した２次電子収集及び転
送手段によって、スピン検出器へ導くことを特徴とす
る、スピン偏極走査電子顕微鏡。1. A spin-polarized scanning electron microscope for detecting a spin state of secondary electrons emitted from a sample to obtain a magnetic domain image, which is produced by irradiating a probe electron beam to a sample surface at a vertical angle or at an angle close thereto. A spin-polarized scanning electron microscope, characterized in that most of the secondary electrons are guided to a spin detector by means of secondary electron collection and transfer means arranged between the objective lens of the electron gun and the sample. 【請求項２】上記２次電子収集手段が、２次電子収集電
極及び偏向電極であることを特徴とする請求項１記載の
スピン偏極走査電子顕微鏡。2. The spin-polarized scanning electron microscope according to claim 1, wherein the secondary electron collecting means is a secondary electron collecting electrode and a deflection electrode. 【請求項３】上記偏向電極を通過する２次電子のエネル
ギーを350 eV以上とすることを特徴とする請求項１記載
のスピン偏極走査電子顕微鏡。3. The spin polarized scanning electron microscope according to claim 1, wherein the energy of secondary electrons passing through the deflection electrode is 350 eV or more. 【請求項４】上記偏向電極が球面偏向器であることを特
徴とする請求項１記載のスピン偏極走査電子顕微鏡。4. The spin polarized scanning electron microscope according to claim 1, wherein the deflection electrode is a spherical deflector.