JPH01126504A - Electron beam length measuring machine - Google Patents

Electron beam length measuring machine

Info

Publication number
JPH01126504A
JPH01126504A JP28482587A JP28482587A JPH01126504A JP H01126504 A JPH01126504 A JP H01126504A JP 28482587 A JP28482587 A JP 28482587A JP 28482587 A JP28482587 A JP 28482587A JP H01126504 A JPH01126504 A JP H01126504A
Authority
JP
Japan
Prior art keywords
electron beam
scanning
sample
objective lens
measuring machine
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
Application number
JP28482587A
Other languages
Japanese (ja)
Inventor
Makoto Mimura
三村 良
Hiroshi Shimada
宏 島田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jeol Ltd
Original Assignee
Jeol Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Jeol Ltd filed Critical Jeol Ltd
Priority to JP28482587A priority Critical patent/JPH01126504A/en
Publication of JPH01126504A publication Critical patent/JPH01126504A/en
Pending legal-status Critical Current

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  • Length-Measuring Devices Using Wave Or Particle Radiation (AREA)

Abstract

PURPOSE:To accurately measure the width of a pattern at any position, by moving an objective lens or a sample stand corresponding to the scanning position of electron beam and always irradiating the surface of a sample with electron beam at a predetermined angle. CONSTITUTION:The scanning beams parallel to an optical axis are formed on the basis of the scanning signal from a CPU 11 using two-stage deflection systems of the first and second scanning systems 4, 5. Then, beams B1-3 are respectively set to such a case that a scanning axis coincides with the optical axis and such a case that the scanning axis is shifted in a- and b-directions. The case of the beam B1 is set to the initial position of an objective lens 6 and, herein, no voltage is applied to a piezoelectric element 21. When the scanning axis moves in the a- and b-directions and the beams B2, B3 are formed, the CPU 11 drives the element 21 through an amplifier 22 and the element 21 is distorted corresponding to applied voltage to minutely move the lens 6 in the a- and b-directions. By this method, the scanning axis of electron beam can be matched with the center of the lens 6 and the width of a pattern can be accurately measured.

Description

【発明の詳細な説明】 [産業上の利用分野] 本発明は電子ビーム測長機に関し、更に詳しくはパター
ン幅を正確に測定することができるようにした電子ビー
ム測長機に関する。
DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron beam length measuring machine, and more particularly to an electron beam length measuring machine capable of accurately measuring pattern width.

[従来の技術] 微細加工技術の急速な進歩により、集積回路はますます
微細化されてきている。その回路素子の寸法は数ミクロ
ンから1ミクロンと微細化されてきている。素子の寸法
が増幅度や周波数特性等、電子回路の基本的性能を決定
する重要な要素となる。そこで、チップ内のパターン幅
を正確に測定ザることが集積回路を設計する上で必要と
なる。
[Background Art] With rapid progress in microfabrication technology, integrated circuits are becoming increasingly finer. The dimensions of the circuit elements have been miniaturized from several microns to one micron. The dimensions of the element are important factors that determine the basic performance of electronic circuits, such as the degree of amplification and frequency characteristics. Therefore, it is necessary to accurately measure the pattern width within a chip when designing an integrated circuit.

電子ビーム測長機は、チップ内のパターン幅を正確に測
定する装置で、第3図にその格成例を示す。電子銃1か
ら出射した電子ビーム3iは、ブランキング電極2によ
りオンオフされた後、収束レンズ3で収束される。収束
された電子ビームBiは、第1走査系4及び第2走査系
5を通過する問に2次元方向に偏向を受ける。この偏向
制御は、CPLlllの指示により行われる。偏向を受
けた電子ビームBiは、対物レンズ6により収束を受り
た後、試料台7上にV、置された試料8上に焦点を結ぶ
。つまり試料8を電子ビーム[3iが照射することにな
る。
An electron beam length measuring machine is a device that accurately measures the pattern width within a chip, and an example thereof is shown in FIG. An electron beam 3i emitted from the electron gun 1 is turned on and off by a blanking electrode 2 and then converged by a converging lens 3. The focused electron beam Bi is deflected in two-dimensional directions while passing through the first scanning system 4 and the second scanning system 5. This deflection control is performed according to instructions from CPLlll. The deflected electron beam Bi is converged by an objective lens 6 and then focused on a sample 8 placed on a sample stage 7 . In other words, the sample 8 is irradiated with the electron beam [3i.

電子ビーム3iが試料8上を走査していくにつれて、試
料8のビーム照射点からは反射電子又は2次電子が発生
する。ここで試料8を走査する方法としては、電子ビー
ム3iを一定の間隔で飛び飛びに走らせるディジタル走
査が行われる。この飛びの間隔(目盛り単位)としては
、例えば電子ビームBiの走査距離の1/1000程度
に設定される。例えば1ミクロンの線幅を測るには3ミ
クロンの幅だけ電子ビーム3iを走査し、目盛りの単位
を0.003ミクロンに設定する。
As the electron beam 3i scans over the sample 8, reflected electrons or secondary electrons are generated from the beam irradiation point of the sample 8. Here, as a method of scanning the sample 8, digital scanning is performed in which the electron beam 3i is made to run intermittently at regular intervals. The interval of this jump (scale unit) is set, for example, to about 1/1000 of the scanning distance of the electron beam Bi. For example, to measure a line width of 1 micron, the electron beam 3i is scanned by a width of 3 microns, and the scale unit is set to 0.003 micron.

試料面から発生した反射電子又は2次電子の強度は、照
割点の材質によって異なる。そこで試料面上部に配置し
た検出器9でこの反射電子を検出し、アンプ10で増幅
した後、CPU11に与える。CPU11は、検出器9
で検出した信号を基にしてパターンの幅を測定する。な
お、走査距離や目盛りの単位は、電子ビーム描画装置で
作った基準図形を用いて精密に校正される。実際の測定
においては、測定の再現性や精度を上げるために、通常
1024ステツプ(10ビツト)や2048ステツプ(
11ピツ[−)の分解能のD/Aコンバータを用いてデ
ィジタル走査を行っている。1フイ一ルド分のビーム走
査が終了したらCPU11の指令により駆動機構12を
作動させ、試料台7を移動さVる。
The intensity of reflected electrons or secondary electrons generated from the sample surface differs depending on the material of the illumination point. Therefore, the reflected electrons are detected by a detector 9 placed above the sample surface, amplified by an amplifier 10, and then provided to the CPU 11. The CPU 11 is the detector 9
The width of the pattern is measured based on the signal detected by . Note that the scanning distance and scale units are precisely calibrated using a reference pattern created by an electron beam drawing device. In actual measurements, usually 1024 steps (10 bits) or 2048 steps (
Digital scanning is performed using a D/A converter with a resolution of 11 bits [-]. When the beam scanning for one field is completed, the drive mechanism 12 is operated according to a command from the CPU 11, and the sample stage 7 is moved.

[発明が解決しようとする問題点] 従来の方式では、試料上の走査幅が、同じ振り角に対し
ても試料の高さの違いによって異なってくるという不具
合が発生する。第4図はビームの走査状態を示す図であ
る。試料面がA、Bと高さの異なる2つの而を想定する
。偏向支点Kを中心として偏向角θで振った場合、試料
面へでの走査幅をLlとすると、試料面Bでの走査幅は
L2(L2>11)となる。この走査幅の差は、測定誤
着となって表われる。偏向角θの範囲内では、同一時間
で処理されるので、例えば試料面へで測定したパターン
幅をし、試料面Bで測定した同じパターンのパターン幅
をL′とすると、L>L’となってしまう。
[Problems to be Solved by the Invention] In the conventional method, a problem arises in that the scanning width on the sample varies depending on the height of the sample even for the same swing angle. FIG. 4 is a diagram showing the scanning state of the beam. Assume that there are two sample surfaces, A and B, with different heights. When the beam is swung at a deflection angle θ around the deflection fulcrum K, if the scanning width on the sample surface is Ll, the scanning width on the sample surface B is L2 (L2>11). This difference in scanning width appears as a measurement error. Within the range of deflection angle θ, processing takes the same amount of time, so for example, if the pattern width measured on the sample surface is L', and the pattern width of the same pattern measured on sample surface B is L', then L>L'. turn into.

また、D/Aコンバータを用いて振り角を等間隔(例え
ば2048ステツプ)で走査した場合に、光軸の中心付
近と端付近とでは、試料上における走査幅が異なってく
る。このことも測定誤差を発生させる要因となる。この
ような不具合を除去するためには、試料面の高さ(ワー
キングデイスタンス)を何らかの方法で測定し、測定結
果に基づいて各ステップ毎に撮り角を演算して変えてや
る必要があるため、測定誤差はなくならなかった。
Further, when the D/A converter is used to scan the swing angle at equal intervals (for example, 2048 steps), the scanning width on the sample differs between near the center and near the end of the optical axis. This also causes measurement errors. In order to eliminate such problems, it is necessary to measure the height of the sample surface (working distance) by some method, and then calculate and change the angle of view at each step based on the measurement results. , the measurement error remained.

本発明はこのような点に鑑みてなされたものであって、
その目的はパターン幅をどの位置においても正確に測定
することができるようにした電子ビーム測長機を実現す
ることにある。
The present invention has been made in view of these points, and
The purpose is to realize an electron beam length measuring machine that can accurately measure pattern width at any position.

[問題点を解決するための手段] 前記した問題点を解決する本発明は、走査系を通過した
電子ビームを対物レンズで収束して試料面に照射し、そ
の反射信号を検出して試料面に形成されたパターン幅を
測定する電子ビーム測長機において、電子ビームの走査
位置に応じて駆動手段を用いて対物レンズ又は試料台を
移動させて、常に電子ビームが試料面に所定角で照射さ
れるように構成したことを特徴とするものである。
[Means for Solving the Problems] The present invention, which solves the above-mentioned problems, focuses an electron beam that has passed through a scanning system using an objective lens, irradiates it onto the sample surface, detects the reflected signal, and detects the sample surface. In an electron beam length measuring machine that measures the width of a pattern formed in The invention is characterized in that it is configured so that

[作用] 電子ビームが試お1面に常に所定角で黒用されるような
機構を設ける。
[Operation] A mechanism is provided so that the electron beam is always directed at a predetermined angle on one surface of the test plate.

[実施例] 以下、図面を参照して本発明の実施例を詳細に説明する
[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

第1図は本発明の一実施例を示す要部構成図である1、
第3図と同一のものは同一の符号を付して示す。図にお
いて、21は対物レンズ6の端部に取付けられたピエゾ
素子である。該ピエゾ素子21はCPU11により制御
されるアンプ22により駆動される。このように構成さ
れた装置の動作を説明ずれば、以下のとおりである。
FIG. 1 is a main part configuration diagram showing an embodiment of the present invention.
Components that are the same as those in FIG. 3 are designated by the same reference numerals. In the figure, 21 is a piezo element attached to the end of the objective lens 6. The piezo element 21 is driven by an amplifier 22 controlled by the CPU 11. The operation of the device configured as described above will be explained as follows.

CPU11からの走査信号により第1走査系4、第2走
査系5の2段の偏向系を用いて光軸に平衡な走査ビーム
をつくる。図中のB1は走査軸が光軸に一致している場
合、B2はB1よりもa方向にずれた場合、B3はB1
よりもb方向にずれた場合である。ここで、走査軸が8
1の1易合における対物レンズ6の位置を初期位置とす
る。この位置では、ピエゾ素子21には電圧を印加しな
い。
A scanning beam balanced on the optical axis is created using a two-stage deflection system, a first scanning system 4 and a second scanning system 5, in response to a scanning signal from the CPU 11. In the figure, B1 is when the scanning axis coincides with the optical axis, B2 is when it is shifted from B1 in the direction a, and B3 is B1.
This is a case where the distance is shifted in the direction b. Here, the scan axis is 8
The position of the objective lens 6 in the 1st case of 1 is the initial position. At this position, no voltage is applied to the piezo element 21.

次に、走査軸がa方向に移動してB2となったものとす
る。そこで、CPU11はアンプ22を介してピエゾ素
子21を駆動する。ピエゾ素子は印加する電圧に応じて
歪み、対物レンズ6をa方向に微小移動させる。逆に、
走査軸がb方向に移動してB3になったものとすると、
CPtJllはピエゾ素子21を逆方向に駆動し、対物
レンズ6をb方向に微小移動させる。このようにして、
電子ビームの走査軸を対物レンズ6の中心に合わせるこ
とができ、正確なパターン幅測定を行うことができる。
Next, assume that the scanning axis moves in the a direction and becomes B2. Therefore, the CPU 11 drives the piezo element 21 via the amplifier 22. The piezo element is distorted according to the applied voltage, and moves the objective lens 6 minutely in the a direction. vice versa,
Assuming that the scanning axis moves in the b direction and becomes B3,
CPtJll drives the piezo element 21 in the opposite direction and moves the objective lens 6 minutely in the b direction. In this way,
The scanning axis of the electron beam can be aligned with the center of the objective lens 6, making it possible to accurately measure the pattern width.

第2図は本発明の他の実施例を示す要部構成図である。FIG. 2 is a block diagram of main parts showing another embodiment of the present invention.

第3図と同一のものは、同一の符号を付して示す。図に
おいて、31.32はそれぞれ試料台7のx、y各方向
に取付けられたピエゾ素子である。これらピエゾ素子3
1.32は、それぞれアンプ33.34を介してCPU
11にヨリ駆動される。このように構成された装置の動
作を説明づれば、以下のとおりである。
Components that are the same as those in FIG. 3 are designated by the same reference numerals. In the figure, numerals 31 and 32 are piezo elements mounted in each of the x and y directions of the sample stage 7, respectively. These piezo elements 3
1.32 are the CPU via amplifiers 33 and 34, respectively.
11. The operation of the device configured as described above will be explained as follows.

CPU11から第1走査系4及び第2走査系5に与える
走査信号は固定とする。このため、電子ビーム[3iは
試f3[8の照射点の位置に拘らず、常に同じ振り角で
走査する。そこで、CPU11は電子ビームBiの走査
に連動して、ピエゾ素子31.32を駆動し、試料台7
を移動させる。これにより、試着18の照射点へは電子
ビーム(3iは常に同じ角度で照射されるので、光軸の
中心付近と端付近でパターン幅測定に差異が生じないよ
うにすることができる。
The scanning signals given from the CPU 11 to the first scanning system 4 and the second scanning system 5 are fixed. For this reason, the electron beam [3i always scans at the same swing angle regardless of the position of the irradiation point of the test f3[8. Therefore, the CPU 11 drives the piezo elements 31 and 32 in conjunction with the scanning of the electron beam Bi, and
move. As a result, since the electron beam (3i) is always irradiated at the same angle to the irradiation point of the try-on 18, it is possible to prevent a difference in pattern width measurement near the center and end of the optical axis.

上述の実施例においては、電子ビームが試料面に所定角
で照射されるように対物レンズ又は試料台を移動させる
駆動手段としてピエゾ素子を用いた場合について説明し
た。しかしながら本発明はこれに限るものではなり、伯
の種類の駆動手段を用いることができる。
In the embodiments described above, a case has been described in which a piezo element is used as a driving means for moving the objective lens or the sample stage so that the electron beam is irradiated onto the sample surface at a predetermined angle. However, the present invention is not limited to this, and other types of driving means can be used.

[発明の効果] 以上詳細に説明したように、本発明によれば駆動手段を
用いて、試料面に電子ビームが常に所定角で照射される
ようにすることができ、パターン幅を正確に測定するこ
とができる。
[Effects of the Invention] As described in detail above, according to the present invention, the electron beam can be always irradiated onto the sample surface at a predetermined angle by using the driving means, and the pattern width can be accurately measured. can do.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は本発明の一実施例を示す要部構成図、第2図は
本発明の他の実施例を示す要部構成図、第3図は電子ビ
ーム測長様の従来構成例を示す図、第4図はビームの走
査状態を示す図である。 4・・・第1走査系    5・・・第2走査系6・・
・対物レンズ    7・・・試料台8・・・試料  
     11・・・CPU21.31.32・・・ピ
エゾ素子 22.23.34・・・アンプ 特許出願人  日  本  電  子  株  式  
会  礼式  理  人   弁  理  士    
井  島  藤  冶外1名 第 1 図 角)2 図 第3図 7試料台
Fig. 1 is a block diagram of main parts showing one embodiment of the present invention, Fig. 2 is a block diagram of main parts showing another embodiment of the present invention, and Fig. 3 shows an example of a conventional structure for electron beam length measurement. FIG. 4 is a diagram showing the scanning state of the beam. 4...First scanning system 5...Second scanning system 6...
・Objective lens 7...Sample stand 8...Sample
11...CPU21.31.32...Piezo element 22.23.34...Amplifier patent applicant Japan Electronics Co., Ltd.
Ceremony for the meeting Patent attorney
Fuji Ijima (1 person) Figure 1 (angle) 2 Figure 3 Figure 7 Sample stand

Claims (2)

【特許請求の範囲】[Claims] (1)走査系を通過した電子ビームを対物レンズで収束
して試料面に照射し、その反射信号を検出して試料面に
形成されたパターン幅を測定する電子ビーム測長機にお
いて、電子ビームの走査位置に応じて駆動手段を用いて
対物レンズ又は試料台を移動させて、常に電子ビームが
試料面に所定角で照射されるように構成したことを特徴
とする電子ビーム測長機。
(1) In an electron beam length measuring machine, the electron beam that has passed through the scanning system is focused by an objective lens and irradiated onto the sample surface, and the reflected signal is detected to measure the pattern width formed on the sample surface. An electron beam length measuring machine characterized in that the objective lens or the sample stage is moved using a driving means according to the scanning position of the electron beam, so that the electron beam is always irradiated onto the sample surface at a predetermined angle.
(2)前記駆動手段としてピエゾ素子を用いたことを特
徴とする特許請求の範囲第1項記載の電子ビーム測長機
(2) The electron beam length measuring machine according to claim 1, characterized in that a piezo element is used as the driving means.
JP28482587A 1987-11-10 1987-11-10 Electron beam length measuring machine Pending JPH01126504A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP28482587A JPH01126504A (en) 1987-11-10 1987-11-10 Electron beam length measuring machine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP28482587A JPH01126504A (en) 1987-11-10 1987-11-10 Electron beam length measuring machine

Publications (1)

Publication Number Publication Date
JPH01126504A true JPH01126504A (en) 1989-05-18

Family

ID=17683497

Family Applications (1)

Application Number Title Priority Date Filing Date
JP28482587A Pending JPH01126504A (en) 1987-11-10 1987-11-10 Electron beam length measuring machine

Country Status (1)

Country Link
JP (1) JPH01126504A (en)

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