JP2005072469A - Method and apparatus for charged beam drawing - Google Patents

Method and apparatus for charged beam drawing Download PDF

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JP2005072469A
JP2005072469A JP2003303112A JP2003303112A JP2005072469A JP 2005072469 A JP2005072469 A JP 2005072469A JP 2003303112 A JP2003303112 A JP 2003303112A JP 2003303112 A JP2003303112 A JP 2003303112A JP 2005072469 A JP2005072469 A JP 2005072469A
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shaping
coordinate axis
aperture
deflector
deflection
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JP4256232B2 (en
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Chikasuke Nishimura
慎祐 西村
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Toshiba Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To improve precision in drawing by matching the rotation of a first molding aperture with the reference coordinates of a sample surface without requiring a special mark etc. <P>SOLUTION: This method for charged beam drawing projects the image of the first molding aperture 4 onto a second molding aperture 7, varies the position of the image of the first molding aperture 4 on the second molding aperture 7 by a molding deflector 5, and image-forms the optically superposed images of the first and second molding apertures 4 and 7 on the sample surface by electromagnetic lenses 9 and 10 to draw a desired pattern on the sample surface. In order to adjust the molding deflector 5 and the electromagnetic lenses 9 and 10 in advance of drawing, voltage to apply to the molding deflector 5 is adjusted so that the coordinate axis of the first molding aperture 4 may match with a deflected coordinate axis by the molding deflector 5, and the exciting current of electromagnetic lenses 9 and 10 is next adjusted so that the deflected coordinate axis by the molding deflector 5 may match with the reference coordinate axis of the sample surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、荷電ビームを用いたリソグラフィ技術に係わり、特に電子光学系の調整方法を改良した荷電ビーム描画方法と荷電ビーム描画装置に関する。   The present invention relates to a lithography technique using a charged beam, and more particularly to a charged beam drawing method and a charged beam drawing apparatus in which an adjustment method of an electron optical system is improved.

可変成形ビーム方式の電子ビーム描画装置は、光軸方向に離間対向配置された第１及び第２の成形アパーチャ間に、第１の成形アパーチャの像を第２成形アパーチャ上で偏向する成形偏向器を設け、成形偏向器よりも下流側に縮小レンズや対物レンズ等の電磁レンズを設け、第１及び第２成形アパーチャの光学的重なり像を試料面上に結像するようになっている。この種の装置においては、各アパーチャの座標軸と試料面の基準座標軸とを一致させるために、第１及び第２の成形アパーチャの回転調整が必須である。   A variable shaped beam type electron beam writing apparatus includes a shaping deflector that deflects an image of a first shaping aperture on a second shaping aperture between first and second shaping apertures that are spaced apart from each other in the optical axis direction. And an electromagnetic lens such as a reduction lens or an objective lens is provided on the downstream side of the shaping deflector, and an optical overlap image of the first and second shaping apertures is formed on the sample surface. In this type of apparatus, rotation adjustment of the first and second shaping apertures is indispensable in order to make the coordinate axes of the respective apertures coincide with the reference coordinate axes of the sample surface.

第１成形アパーチャの回転調整方法としては、第１成形アパーチャに回転機構を設けて機械的に調整する方法と、電磁レンズの像の回転作用を利用して調整する方法のどちらかが取られている。回転機構で調整する方法は、縮小率を変えずに回転単独で調整できるという長所があるが、回転機構の製作コストが高いこと、回転機構を組み込むスペースが必要なために電子光学系の設計に制限がでること、回転機構の厚み分だけビーム光路長が長くなってビームボケを増大させるといった短所がある。それに比べて、電磁レンズでの像の回転作用を利用する調整方法はそれらの短所が無い。   As a method for adjusting the rotation of the first shaping aperture, either a method of adjusting the rotation by providing a rotation mechanism in the first shaping aperture or a method of adjusting using the rotation action of the image of the electromagnetic lens is taken. Yes. The method of adjusting with the rotating mechanism has the advantage that it can be adjusted by rotating alone without changing the reduction ratio, but the manufacturing cost of the rotating mechanism is high, and the space for incorporating the rotating mechanism is required, so designing the electron optical system There are disadvantages such as a limitation, and the beam optical path length is increased by the thickness of the rotation mechanism to increase the beam blur. In contrast, the adjustment method using the image rotating action of the electromagnetic lens does not have the disadvantages.

従来、電磁レンズで回転調整する場合、縮小した試料面上の像を検出する方法を用いて調整を行っていた。具体的には、電子ビーム描画装置において、特殊な形状をした試料面上のマークの形状を利用して成形像の回転調整を行っている（例えば、特許文献１参照）。また、試料面上に設けたナイフエッジを利用して回転調整を行っている（例えば、特許文献２参照）。   Conventionally, when rotational adjustment is performed using an electromagnetic lens, adjustment is performed using a method of detecting a reduced image on a sample surface. Specifically, in the electron beam drawing apparatus, the rotation of the formed image is adjusted using the shape of the mark on the sample surface having a special shape (see, for example, Patent Document 1). Further, rotation adjustment is performed using a knife edge provided on the sample surface (see, for example, Patent Document 2).

しかしながら、特許文献１の方法においては、特殊マークが必要となること、特殊マーク形状精度及び同マーク設置位置精度に応じて調整誤差が発生する欠点を持っている。数ミクロン寸法のマークの形状精度及び試料面座標に対して１ｍｒａｄ以下の精度で配置することは非常に困難である。また、数ミクロンの小さな縮小ビームの検出であるため、検出ノイズの影響で１ｍｒａｄの優れた調整精度を得るのは困難である。   However, the method of Patent Document 1 has the disadvantage that a special mark is required, and that an adjustment error occurs depending on the special mark shape accuracy and the mark installation position accuracy. It is very difficult to arrange the mark with a precision of 1 mrad or less with respect to the shape accuracy of the mark having a dimension of several microns and the sample surface coordinates. Further, since the detection is performed with a small reduced beam of several microns, it is difficult to obtain an excellent adjustment accuracy of 1 mrad due to the influence of detection noise.

一方、特許文献２の方法においても同様に、ナイフエッジが必要であること、ナイフエッジを１ｍｒａｄの精度で試料面座標に調整するのは非常に困難であり、さらに数ミクロンの小さな縮小ビームの検出であるため、１ｍｒａｄの優れた調整精度を得るのは非常に困難である。
特開２００１−１４４００７号公報 特開平１０−２４７４７０号公報 On the other hand, in the method of Patent Document 2 as well, it is very difficult to adjust the knife edge to the sample surface coordinates with an accuracy of 1 mrad, and to detect a reduced beam as small as several microns. Therefore, it is very difficult to obtain an adjustment accuracy of 1 mrad.
JP 2001-144007 A JP-A-10-247470

このように従来、可変成形ビーム方式の電子ビーム描画装置においては、機械的回転調整機構を用いずに電磁レンズにより第１成形アパーチャの回転調整を行う場合、試料面上に特殊なマークなどを超高精度に準備する必要があり、コスト，手間が多く掛かってしまうと共に、第１成形アパーチャの座標を試料面の基準座標に対して高精度に調整するのが困難な状況であった。   As described above, conventionally, in a variable shaped beam type electron beam writing apparatus, when the rotation of the first shaping aperture is adjusted by an electromagnetic lens without using a mechanical rotation adjustment mechanism, a special mark or the like is superposed on the sample surface. It is necessary to prepare with high accuracy, which is costly and troublesome, and it is difficult to adjust the coordinates of the first shaping aperture with high accuracy with respect to the reference coordinates of the sample surface.

本発明は、上記事情を考慮して成されたもので、その目的とするところは、特別なマーク等を必要とせずに、第１成形アパーチャの座標軸を試料面の基準座標軸に合わせることができ、描画精度の向上に寄与し得る荷電ビーム描画方法と荷電ビーム描画装置を提供することにある。   The present invention has been made in view of the above circumstances, and the object of the present invention is to align the coordinate axis of the first shaping aperture with the reference coordinate axis of the sample surface without requiring a special mark or the like. Another object of the present invention is to provide a charged beam drawing method and a charged beam drawing apparatus that can contribute to improvement of drawing accuracy.

上記課題を解決するために本発明は、次のような構成を採用している。   In order to solve the above problems, the present invention adopts the following configuration.

即ち本発明は、第１成形アパーチャの像を第２成形アパーチャ上に投影すると共に、成形偏向器により第２成形アパーチャ上の第１成形アパーチャの像の位置を可変し、第１及び第２成形アパーチャの光学的重なり像を電磁レンズにより試料面上に結像することにより、試料面に所望パターンを描画する荷電ビーム描画方法であって、描画に先立ち前記成形偏向器及び電磁レンズを調整するために、第１成形アパーチャの座標軸と前記成形偏向器による偏向座標軸とが一致するように、前記成形偏向器に印加する電圧を調整し、次いで前記成形偏向器による偏向座標軸と前記試料面の基準座標軸とが一致するように、前記電磁レンズの励磁電流を調整することを特徴とする。   That is, the present invention projects the image of the first shaping aperture onto the second shaping aperture, and the position of the image of the first shaping aperture on the second shaping aperture is varied by the shaping deflector, so that the first and second shaping apertures are changed. A charged beam drawing method for drawing a desired pattern on a sample surface by forming an optical overlap image of an aperture on the sample surface by an electromagnetic lens, for adjusting the shaping deflector and the electromagnetic lens prior to drawing The voltage applied to the shaping deflector is adjusted so that the coordinate axis of the first shaping aperture and the deflection coordinate axis of the shaping deflector coincide, and then the deflection coordinate axis of the shaping deflector and the reference coordinate axis of the sample surface The excitation current of the electromagnetic lens is adjusted so that the two coincide with each other.

ここで、本発明の望ましい実施態様としては次のものがあげられる。   Here, preferred embodiments of the present invention include the following.

(1) 成形偏向器は複数の電極からなり、各々の偏向電極に印加する偏向電圧は、倍率係数，回転係数，Ｘ方向及びＹ方向の偏向量で定義されるものであり、成形偏向器に印加する電圧の調整に際して、第１成形アパーチャの座標軸と成形偏向器による偏向座標軸とが一致する回転係数を求めること。   (1) The shaping deflector is composed of a plurality of electrodes, and the deflection voltage applied to each deflection electrode is defined by a magnification factor, a rotation coefficient, and deflection amounts in the X and Y directions. In adjusting the voltage to be applied, a rotation coefficient is obtained in which the coordinate axis of the first shaping aperture and the deflection coordinate axis of the shaping deflector coincide.

(2) 成形偏向器の各電極に印加する電圧は、
Ｖｘ＝Ｇｘ・ｘ＋Ｒｘ・ｙ
Ｖｙ＝Ｇｙ・ｙ＋Ｒｙ・ｘ
Ｇ：倍率係数、Ｒ：回転係数、ｘ：Ｘ方向偏向量、ｙ：Ｙ方向偏向量
で定義されるものであること。 (2) The voltage applied to each electrode of the shaping deflector is
Vx = Gx.x + Rx.y
Vy = Gy · y + Ry · x
G: Magnification factor, R: Rotation coefficient, x: X direction deflection amount, y: Y direction deflection amount.

(3) 第１成形アパーチャの座標軸と成形偏向器による偏向座標軸とが一致する回転係数を求めるために、第１成形アパーチャの像の一辺と第２成形アパーチャとが一部重なる状態で、前記成形偏向器により第１成形アパーチャの像を前記一辺と平行な方向に相当する方向に偏向したときに、試料面上でのビーム電流の変化が最も少なくなる回転係数を求めること。   (3) In order to obtain a rotation coefficient at which the coordinate axis of the first shaping aperture coincides with the deflection coordinate axis of the shaping deflector, the shaping is performed with one side of the image of the first shaping aperture partially overlapping with the second shaping aperture. Determining a rotation coefficient that minimizes a change in beam current on the sample surface when the image of the first shaping aperture is deflected by a deflector in a direction corresponding to a direction parallel to the one side;

(4) 電磁レンズは、第２成形アパーチャ側の縮小レンズと試料側の対物レンズの２段構成であり、各々のレンズの励磁電流を最適に設定することにより、偏向座標軸と基準座標軸とを一致させながら焦点を合わせること。   (4) The electromagnetic lens has a two-stage configuration of a reduction lens on the second shaping aperture side and an objective lens on the sample side. By optimally setting the excitation current of each lens, the deflection coordinate axis coincides with the reference coordinate axis. To focus.

(5) 偏向座標軸と基準座標軸とが一致するように縮小レンズの励磁電流を調整し、これに伴う焦点位置ずれを対物レンズの励磁電流を調整することにより補正し、これらの操作を繰り返すこと。   (5) Adjust the excitation current of the reduction lens so that the deflection coordinate axis coincides with the reference coordinate axis, correct the focal position shift caused by this by adjusting the excitation current of the objective lens, and repeat these operations.

また本発明は、荷電ビーム描画装置において、光軸方向に離間対向配置された第１及び第２の成形アパーチャと、第１の成形アパーチャと第２の成形アパーチャとの間に配置され、第１の成形アパーチャの像を第２成形アパーチャ上で偏向する成形偏向器と、前記成形偏向器よりも下流側に設けられ、第１及び第２成形アパーチャの光学的重なり像を試料面上に結像する電磁レンズと、第１成形アパーチャの座標軸と前記成形偏向器による偏向座標軸とが一致するように、前記成形偏向器に印加する電圧を調整する手段と、前記成形偏向器による偏向座標軸と前記試料面の基準座標軸とが一致するように、前記電磁レンズの励磁電流を調整する手段と、を具備してなることを特徴とする。   According to the present invention, in the charged beam drawing apparatus, the first and second shaping apertures that are spaced apart from each other in the optical axis direction, the first shaping aperture, and the second shaping aperture are arranged, A shaping deflector for deflecting the image of the shaping aperture on the second shaping aperture, and an optically overlapped image of the first and second shaping apertures formed on the sample surface. An electromagnetic lens, means for adjusting a voltage applied to the shaping deflector so that the coordinate axis of the first shaping aperture and the deflection coordinate axis of the shaping deflector coincide, and the deflection coordinate axis of the shaping deflector and the sample Means for adjusting the excitation current of the electromagnetic lens so that the reference coordinate axis of the surface matches.

本発明によれば、成形偏向器に印加する電圧及び電磁レンズの励磁電流を調整することにより、第１成形アパーチャの座標軸を試料面の基準座標軸に高精度に合わせることができ、描画精度の向上をはかることができる。そしてこの場合、第１成形アパーチャを機械的に回転する機構や特殊なマークを必要とすることもないので、手間やコストの点でも有利である。   According to the present invention, by adjusting the voltage applied to the shaping deflector and the excitation current of the electromagnetic lens, the coordinate axis of the first shaping aperture can be adjusted to the reference coordinate axis of the sample surface with high accuracy, and the drawing accuracy is improved. Can be measured. In this case, a mechanism for mechanically rotating the first shaping aperture and a special mark are not required, which is advantageous in terms of labor and cost.

以下、本発明の詳細を図示の実施形態によって説明する。   The details of the present invention will be described below with reference to the illustrated embodiments.

図１は、本発明の一実施形態に係わる電子ビーム描画装置を示す概略構成図である。図中の１は電子銃、２は照明レンズ、３はブランキング偏向器、４は第１成形アパーチャ、５は成形偏向器、６は投影レンズ、７は第２成形アパーチャ、８はビーム制限用アパーチャ、９は縮小レンズ、１０は対物レンズ、１１は対物偏向器、１２は反射電子検出器、１３はＸＹ試料ステージ，１４はビーム電流検出器、１５はマーク板である。   FIG. 1 is a schematic configuration diagram showing an electron beam drawing apparatus according to an embodiment of the present invention. In the figure, 1 is an electron gun, 2 is an illumination lens, 3 is a blanking deflector, 4 is a first shaping aperture, 5 is a shaping deflector, 6 is a projection lens, 7 is a second shaping aperture, and 8 is for beam limiting. Aperture, 9 is a reduction lens, 10 is an objective lens, 11 is an objective deflector, 12 is a backscattered electron detector, 13 is an XY sample stage, 14 is a beam current detector, and 15 is a mark plate.

電子銃１から放出されたビームは照明レンズ２により第１成形アパーチャ４上に照射される。第１成形アパーチャ４の像は投影レンズ６により第２成形アパーチャ７上に結像され、さらに縮小レンズ９により縮小され対物レンズ１０により試料面上に結像される。第２成形アパーチャ７はθステージ２３上に取り付けられている。第２成形アパーチャ７は多角形の開口部１８を有していて、その寸法形状は、第２成形アパーチャ７上での第１成形アパーチャ４の像１９の寸法よりも大きいものとなっている。第１成形アパーチャ４の開口部２０を通過したビームは成形偏向器５によって偏向することができ、第２成形アパーチャ７上のビーム位置を変えることができる。これにより、ビームの形状を変えることが可能となっている。   The beam emitted from the electron gun 1 is irradiated onto the first shaping aperture 4 by the illumination lens 2. The image of the first shaping aperture 4 is formed on the second shaping aperture 7 by the projection lens 6, further reduced by the reduction lens 9, and formed on the sample surface by the objective lens 10. The second shaping aperture 7 is attached on the θ stage 23. The second shaping aperture 7 has a polygonal opening 18, and the size of the second shaping aperture 7 is larger than the size of the image 19 of the first shaping aperture 4 on the second shaping aperture 7. The beam that has passed through the opening 20 of the first shaping aperture 4 can be deflected by the shaping deflector 5 and the beam position on the second shaping aperture 7 can be changed. This makes it possible to change the shape of the beam.

対物レンズ１０を通過したビームは対物偏向器１１によって偏向することができる。マーク板１５及びビーム電流検出器１４はＸＹ試料ステージ１３に取り付けられていて、移動することが可能である。ＸＹ試料ステージ１３の移動位置は、図示しない高精度レーザ位置測長器によって測定される。マーク板１５に設けられた十字マーク２１は下地２２と異なるビーム反射をする材質で作られている。例えば、下地２２はシリコン、十字マーク２１は金，タングステンなどの材質である。ビーム電流検出器１４は電流計につながれていて、ビーム電流値測定ができるようになっている。   The beam that has passed through the objective lens 10 can be deflected by the objective deflector 11. The mark plate 15 and the beam current detector 14 are attached to the XY sample stage 13 and can move. The movement position of the XY sample stage 13 is measured by a high-precision laser position measuring device (not shown). The cross mark 21 provided on the mark plate 15 is made of a material that reflects the beam differently from the base 22. For example, the base 22 is made of silicon, and the cross mark 21 is made of a material such as gold or tungsten. The beam current detector 14 is connected to an ammeter so that a beam current value can be measured.

次に、本実施形態における第１成形アパーチャ４の回転調整方法について、図２と図３を基に説明する。基本的には、図２に示すように、まず成形偏向回転を第１成形アパーチャ回転に一致させる（ステップＳ１）。即ち、第１成形アパーチャの座標軸を成形偏向座標軸に一致させる。次いで、成形偏向回転及び第１成形アパーチャ回転を基準座標系である試料面座標に電磁レンズ励磁を変えることによって一致させる（ステップＳ２）。即ち、第１成形アパーチャの座標軸及び成形偏向座標軸を試料面の基準座標軸に一致させる。   Next, a method for adjusting the rotation of the first shaping aperture 4 in the present embodiment will be described with reference to FIGS. Basically, as shown in FIG. 2, first, the shaping deflection rotation is matched with the first shaping aperture rotation (step S1). That is, the coordinate axis of the first shaping aperture is matched with the shaping deflection coordinate axis. Next, the shaping deflection rotation and the first shaping aperture rotation are made to coincide with the sample surface coordinates which are the reference coordinate system by changing the electromagnetic lens excitation (step S2). That is, the coordinate axis of the first shaping aperture and the shaping deflection coordinate axis are made to coincide with the reference coordinate axis of the sample surface.

装置の基準座標は試料ステージ位置を測定しているレーザ干渉計座標で１ｎｍ以下の測定精度がある。この座標系を試料面の座標（基準座標）とする。成形偏向座標は成形偏向器５よりも下流にある電磁レンズ９，１０の磁場によって試料面に到達するまでの間に回転する。装置の設計計算でこの回転量は成形偏向座標にフィードバックされるが、設計計算誤差，成形偏向器５の組立誤差などにより図３（ａ）に示すように試料面座標と回転ずれが発生する。また、第１成形アパーチャ４についても、第１成形アパーチャ４より下流にある電磁レンズ９，１０の磁場によって回転し、計算値が設計にフィードバックされるが、成形偏向器５と同様の理由で試料面座標からは図３（ａ）に示すように回転誤差が発生する。   The reference coordinates of the apparatus are laser interferometer coordinates for measuring the position of the sample stage and have a measurement accuracy of 1 nm or less. This coordinate system is set as the coordinate (reference coordinate) of the sample surface. The shaping deflection coordinates rotate until reaching the sample surface by the magnetic field of the electromagnetic lenses 9 and 10 located downstream of the shaping deflector 5. This rotation amount is fed back to the forming deflection coordinates in the design calculation of the apparatus, but due to a design calculation error, an assembly error of the forming deflector 5 and the like, as shown in FIG. The first shaping aperture 4 is also rotated by the magnetic field of the electromagnetic lenses 9 and 10 downstream from the first shaping aperture 4 and the calculated value is fed back to the design. For the same reason as the shaping deflector 5, the sample From the surface coordinates, a rotation error occurs as shown in FIG.

成形偏向は成形偏向器５に電圧を印加することで行うが、成形偏向器５が例えばＸ方向に対向する一対の偏向板とＹ方向に対向する一対の偏向板で構成されているとすると、Ｘ方向の偏向板に印加する電圧ＶｘとＹ方向の偏向板に印加する電圧Ｖｙは、
Ｖｘ＝Ｇｘ・ｘ＋Ｒｘ・ｙ
Ｖｙ＝Ｇｙ・ｙ＋Ｒｙ・ｘ
Ｇ：倍率係数、Ｒ：回転係数、ｘ：Ｘ方向偏向量、ｙ：Ｙ方向偏向量
のような関係で決定される。そして、回転係数Ｒを変えることによって、成形偏向座標を回転させることができる。そこで、この回転係数を変えて、図３（ｂ）に示すように、第１成形アパーチャの座標軸に成形偏向座標軸を一致させる。なお、上記式は成形偏向器５を構成する偏向電極の数によって変わるものであるが、各偏向電極に印加する電圧が倍率係数，回転係数，Ｘ方向及びＹ方向の偏向量で定義されるものであれば、上記と同様に回転係数Ｒを変えることにより第１成形アパーチャの座標軸に成形偏向座標軸を一致させることが可能である。 The shaping deflection is performed by applying a voltage to the shaping deflector 5. If the shaping deflector 5 is composed of, for example, a pair of deflection plates facing in the X direction and a pair of deflection plates facing in the Y direction, The voltage Vx applied to the deflection plate in the X direction and the voltage Vy applied to the deflection plate in the Y direction are
Vx = Gx.x + Rx.y
Vy = Gy · y + Ry · x
G: magnification factor, R: rotation coefficient, x: X direction deflection amount, y: Y direction deflection amount. Then, by changing the rotation coefficient R, the forming deflection coordinates can be rotated. Therefore, this rotation coefficient is changed so that the shaping deflection coordinate axis coincides with the coordinate axis of the first shaping aperture as shown in FIG. The above formula varies depending on the number of deflection electrodes constituting the shaping deflector 5, but the voltage applied to each deflection electrode is defined by the magnification coefficient, the rotation coefficient, the deflection amount in the X direction and the Y direction. If so, it is possible to make the shaping deflection coordinate axis coincide with the coordinate axis of the first shaping aperture by changing the rotation coefficient R in the same manner as described above.

成形偏向座標軸を精密に第１成形アパーチャの座標軸に一致させるための具体例を、図４を使って説明する。成形偏向座標と第１成形アパーチャ座標の回転ずれ量の測定は特開平１０−２６００２８号公報に記載された方法を用いる。図４（ａ）に示すように、第２成形アパーチャ７のコーナーに第１成形アパーチャ４の像を偏向し、試料面上でビーム電流の変化を測定する。成形偏向回転係数がＲ２の時にはビーム電流は一定となると共に、成形偏向回転係数がＲ２の時に第１成形アパーチャ回転と成形偏向回転が一致する。この測定方法を以後、ビーム電流測定方法と称する。   A specific example for precisely matching the forming deflection coordinate axis with the coordinate axis of the first forming aperture will be described with reference to FIG. The method described in Japanese Patent Laid-Open No. 10-260028 is used to measure the rotational deviation between the forming deflection coordinates and the first forming aperture coordinates. As shown in FIG. 4A, the image of the first shaping aperture 4 is deflected to the corner of the second shaping aperture 7, and the change in the beam current is measured on the sample surface. When the shaping deflection rotation coefficient is R2, the beam current is constant, and when the shaping deflection rotation coefficient is R2, the first shaping aperture rotation coincides with the shaping deflection rotation. Hereinafter, this measurement method is referred to as a beam current measurement method.

次に、第１成形アパーチャ４及び成形偏向器５よりも下流に位置する電磁レンズ９，１０の励磁を変えて、図３（ｃ）に示すように、第１成形アパーチャ座標及び成形偏向座標を同時に同量回転させて試料面座標の回転に一致させる。電磁レンズは、例えば図１における縮小レンズ９と対物レンズ１０である。成形偏向座標回転を精密に測定する方法の具体例について、図５を使って説明する。この方法は特開平１０−２７０３３７号公報に一部記載されているものである。上述の成形偏向回転係数Ｒ２を用いて、図５（ａ）に示すように、第１成形アパーチャ像が第２成形アパーチャ７に接触しないように成形偏向する。そして、試料面上のビームの位置を通常使われている方法、例えば十字マーク上をビーム走査させる方法などを用いて、図５（ｂ）に示すように、ビームａの状態に対応するビーム位置Ａを測定する。   Next, the excitation of the electromagnetic lenses 9 and 10 located downstream of the first shaping aperture 4 and the shaping deflector 5 is changed, and the first shaping aperture coordinates and the shaping deflection coordinates are changed as shown in FIG. Simultaneously rotate the same amount to match the rotation of the sample surface coordinates. The electromagnetic lens is, for example, the reduction lens 9 and the objective lens 10 in FIG. A specific example of a method for accurately measuring the forming deflection coordinate rotation will be described with reference to FIG. This method is partly described in Japanese Patent Application Laid-Open No. 10-270337. Using the above-described shaping deflection rotation coefficient R2, as shown in FIG. 5A, shaping deflection is performed so that the first shaping aperture image does not contact the second shaping aperture 7. Then, using a method in which the beam position on the sample surface is normally used, for example, a method of scanning the beam on the cross mark, as shown in FIG. 5B, the beam position corresponding to the state of the beam a. A is measured.

次いで、第１成形アパーチャ像を第２成形アパーチャ７にかからないようにビームａからＲ２を用いてビームｂまで成形偏向座標のＸ方向に成形偏向し、試料面上のビーム位置Ｂを測定する。位置Ａと位置Ｂから成形偏向座標Ｘ方向の試料面上に対するずれ量角度δが算出できる。Ｙ方向に関してのずれ量を求めるためにはビームｃ，ビームｄを用いてビーム位置Ｃ，Ｄを求めればよい。このδの測定方法をマークスキャン方法と称することにする。そして、δがゼロになる方向にレンズ励磁を変化させ、δが許容値以内になるまで繰り返す。   Next, the first shaping aperture image is shaped and deflected in the X direction of the shaping deflection coordinates from the beam a to the beam b so as not to reach the second shaping aperture 7, and the beam position B on the sample surface is measured. A deviation angle δ with respect to the sample surface in the molding deflection coordinate X direction from the position A and the position B can be calculated. In order to obtain the deviation amount in the Y direction, the beam positions C and D may be obtained using the beams c and d. This method of measuring δ will be referred to as a mark scanning method. Then, the lens excitation is changed in the direction in which δ becomes zero, and the process is repeated until δ is within an allowable value.

具体的には、最初にδが零になる方向に縮小レンズ９の励磁電流を調整し、これに伴う焦点位置ずれを補正するために対物レンズ１０の励磁電流を調整する。そして、再度縮小レンズ９の励磁電流を調整し、更に対物レンズ１０の励磁電流を調整する。これらの操作を繰り返すことにより、δが零になり且つ焦点位置が合う各々の励磁電流を求める。   Specifically, first, the excitation current of the reduction lens 9 is adjusted in the direction in which δ becomes zero, and the excitation current of the objective lens 10 is adjusted in order to correct the focal position shift associated therewith. Then, the excitation current of the reduction lens 9 is adjusted again, and the excitation current of the objective lens 10 is further adjusted. By repeating these operations, each excitation current in which δ becomes zero and the focal position matches is obtained.

上述の一連のアルゴリズムを、図６に示しておく。   The series of algorithms described above is shown in FIG.

なお、第１成形アパーチャ４だけではなく第２成形アパーチャ７の座標軸と試料面の基準座標軸とを合わせる必要があるが、これは第２成形アパーチャ７を保持する回転ステージ２３で行うことができる。このように、第２成形アパーチャ７に対しては回転ステージ２３が設けられているが、一般に第２成形アパーチャ７の設置空間は第１成形アパーチャ４の設置空間に比べて十分に余裕があり、回転ステージ２３を設けることによるデメリットは小さいものである。   Although it is necessary to match not only the first shaping aperture 4 but also the coordinate axis of the second shaping aperture 7 with the reference coordinate axis of the sample surface, this can be done by the rotary stage 23 holding the second shaping aperture 7. As described above, the rotation stage 23 is provided for the second shaping aperture 7, but generally the installation space for the second shaping aperture 7 has a sufficient margin compared to the installation space for the first shaping aperture 4, The disadvantages of providing the rotary stage 23 are small.

このように本実施形態によれば、描画に先立ち成形偏向器５及び電磁レンズ９，１０を調整するために、第１成形アパーチャ４の座標軸と成形偏向器５による偏向座標軸とが一致するように、成形偏向器５に印加する電圧を調整し、次いで成形偏向器５による偏向座標軸と試料面の基準座標軸とが一致するように、電磁レンズ９，１０の励磁電流を調整することにより、特別なマーク等を必要とせずに、第１成形アパーチャの回転を試料面の基準座標に合わせることができ、描画精度の向上に寄与することが可能となる。   As described above, according to this embodiment, the coordinate axis of the first shaping aperture 4 and the deflection coordinate axis of the shaping deflector 5 coincide with each other in order to adjust the shaping deflector 5 and the electromagnetic lenses 9 and 10 before drawing. The voltage applied to the shaping deflector 5 is adjusted, and then the excitation current of the electromagnetic lenses 9 and 10 is adjusted so that the deflection coordinate axis by the shaping deflector 5 and the reference coordinate axis of the sample surface coincide with each other. Without requiring a mark or the like, the rotation of the first shaping aperture can be adjusted to the reference coordinates of the sample surface, which can contribute to the improvement of the drawing accuracy.

ここで、第１成形アパーチャ回転と成形偏向回転のずれ量を測定するためのビーム電流測定方法では、０．５ｍｒａｄ以下の測定精度が実験では得られている。また、マークスキャン方法による試料面上座標に対する成形偏向回転の測定精度は０．５ｍｒａｄ以下が実験では得られている。従って、本実施形態の第１成形アパーチャ回転調整方法による調整精度は１ｍｒａｄ以下であり、極めて高精度な調整が可能である。   Here, in the beam current measurement method for measuring the deviation amount between the first shaping aperture rotation and the shaping deflection rotation, a measurement accuracy of 0.5 mrad or less is obtained in the experiment. In addition, the measurement accuracy of the forming deflection rotation with respect to the coordinates on the sample surface by the mark scanning method is 0.5 mrad or less in the experiment. Therefore, the adjustment accuracy according to the first shaping aperture rotation adjustment method of the present embodiment is 1 mrad or less, and extremely high-precision adjustment is possible.

なお、本発明は上述した実施形態に限定されるものではない。実施形態では、可変成形ビーム方式の電子ビーム描画装置を例にとり説明したが、本発明は必ずしも可変成形ビーム方式に限らず、複数枚の成形アパーチャを有する描画装置に適用することができる。また、電子ビーム描画装置に限らず、イオンビーム描画装置に適用することも可能である。また、各座標軸を一致させるための成形偏向器の電圧調整手段及び電磁レンズの励磁電流調整手段は、必ずしも実施形態に説明した方法に限らず、仕様に応じて適宜変更可能である。   In addition, this invention is not limited to embodiment mentioned above. In the embodiment, the variable shaped beam type electron beam drawing apparatus has been described as an example. However, the present invention is not necessarily limited to the variable shaped beam type, and can be applied to a drawing apparatus having a plurality of shaping apertures. Further, the present invention can be applied not only to an electron beam drawing apparatus but also to an ion beam drawing apparatus. Further, the voltage adjusting means of the shaping deflector and the exciting current adjusting means of the electromagnetic lens for matching the coordinate axes are not necessarily limited to the method described in the embodiment, and can be appropriately changed according to the specifications.

その他、本発明の要旨を逸脱しない範囲で、種々変形して実施することができる。   In addition, various modifications can be made without departing from the scope of the present invention.

本発明の一実施形態に係わる電子ビーム描画装置を示す概略構成図。1 is a schematic configuration diagram showing an electron beam drawing apparatus according to an embodiment of the present invention. 同実施形態おけるアパーチャ回転調整法のアルゴリズムを示す図。The figure which shows the algorithm of the aperture rotation adjustment method in the embodiment. 第１成形アパーチャ座標，成形偏向座標，及び試料面座標の関係を示す図。The figure which shows the relationship between a 1st shaping | molding aperture coordinate, a shaping | molding deflection | deviation coordinate, and a sample surface coordinate. 成形偏向座標を第１成形アパーチャ座標に一致させるための具体的方法を示す図。The figure which shows the specific method for making a shaping | molding deflection | deviation coordinate correspond to a 1st shaping | molding aperture coordinate. 成形偏向座標回転を測定する具体的方法を示す図。The figure which shows the specific method of measuring shaping | molding deflection | deviation coordinate rotation. 第１成形アパーチャ座標，成形偏向座標，及び試料面座標を合わせるためのフローチャート。The flowchart for adjusting a 1st shaping | molding aperture coordinate, a shaping | molding deflection coordinate, and a sample surface coordinate.

符号の説明Explanation of symbols

１…電子銃
２…照明レンズ
３…ブランキング偏向器
４…第１成形アパーチャ
５…成形偏向器
６…投影レンズ
７…第２成形アパーチャ
８…ビーム制限用アパーチャ
９…縮小レンズ
１０…対物レンズ
１１…対物偏向器
１２…反射電子検出器
１３…ＸＹステージ
１４…ビーム電流検出器
１５…マーク台
１６…成形ビーム結像系
１８…第２成形アパーチャ開口部
１９…第１成形アパーチャ像
２０…第１成形アパーチャ開口部
２１…十字マーク
２２…下地
２３…第２成形アパーチャ回転ステージ DESCRIPTION OF SYMBOLS 1 ... Electron gun 2 ... Illumination lens 3 ... Blanking deflector 4 ... 1st shaping | molding aperture 5 ... Molding deflector 6 ... Projection lens 7 ... 2nd shaping aperture 8 ... Aperture for beam limitation 9 ... Reduction lens 10 ... Objective lens 11 DESCRIPTION OF SYMBOLS ... Objective deflector 12 ... Backscattered electron detector 13 ... XY stage 14 ... Beam current detector 15 ... Mark stand 16 ... Shaped beam imaging system 18 ... 2nd shaping aperture opening 19 ... 1st shaping aperture image 20 ... 1st Molding aperture opening 21 ... Cross mark 22 ... Base 23 ... Second molding aperture rotation stage

Claims (5)

第１成形アパーチャの像を第２成形アパーチャ上に投影すると共に、成形偏向器により第２成形アパーチャ上の第１成形アパーチャの像の位置を可変し、第１及び第２成形アパーチャの光学的重なり像を電磁レンズにより試料面上に結像することにより、試料面に所望パターンを描画する荷電ビーム描画方法であって、
描画に先立ち前記成形偏向器及び電磁レンズを調整するために、第１成形アパーチャの座標軸と前記成形偏向器による偏向座標軸とが一致するように、前記成形偏向器に印加する電圧を調整し、次いで前記成形偏向器による偏向座標軸と前記試料面の基準座標軸とが一致するように、前記電磁レンズの励磁電流を調整することを特徴とする荷電ビーム描画方法。 An image of the first shaping aperture is projected onto the second shaping aperture, and the position of the image of the first shaping aperture on the second shaping aperture is varied by the shaping deflector, so that the optical overlap of the first and second shaping apertures is achieved. A charged beam drawing method for drawing a desired pattern on a sample surface by forming an image on the sample surface by an electromagnetic lens,
Prior to drawing, in order to adjust the shaping deflector and the electromagnetic lens, the voltage applied to the shaping deflector is adjusted so that the coordinate axis of the first shaping aperture and the deflection coordinate axis of the shaping deflector coincide, and then A charged beam drawing method, wherein an excitation current of the electromagnetic lens is adjusted so that a deflection coordinate axis by the shaping deflector coincides with a reference coordinate axis of the sample surface. 前記成形偏向器は複数の電極からなり、各々の偏向電極に印加する偏向電圧は、倍率係数，回転係数，Ｘ方向及びＹ方向の偏向量で定義されるものであり、前記成形偏向器に印加する電圧の調整に際して、第１成形アパーチャの座標軸と前記成形偏向器による偏向座標軸とが一致する回転係数を求めることを特徴とする請求項１記載の荷電ビーム描画方法。   The shaping deflector comprises a plurality of electrodes, and a deflection voltage applied to each deflection electrode is defined by a magnification factor, a rotation coefficient, and deflection amounts in the X and Y directions, and is applied to the shaping deflector. 2. The charged beam drawing method according to claim 1, wherein a rotation coefficient at which a coordinate axis of the first shaping aperture coincides with a deflection coordinate axis of the shaping deflector is determined when adjusting the voltage to be applied. 第１成形アパーチャの座標軸と前記成形偏向器による偏向座標軸とが一致する回転係数を求めるために、第１成形アパーチャの像の一辺と第２成形アパーチャとが一部重なる状態で、前記成形偏向器により第１成形アパーチャの像を前記一辺と平行な方向に相当する方向に偏向したときに、前記試料面上でのビーム電流の変化が最も少なくなる回転係数を求めることを特徴とする請求項２記載の荷電ビーム描画方法。   In order to obtain a rotation coefficient at which the coordinate axis of the first shaping aperture coincides with the deflection coordinate axis of the shaping deflector, the shaping deflector in a state in which one side of the image of the first shaping aperture and the second shaping aperture partially overlap each other. The rotation coefficient that minimizes a change in beam current on the sample surface is obtained when the image of the first shaping aperture is deflected in a direction corresponding to a direction parallel to the one side by the method. The charged beam drawing method described. 前記電磁レンズは、第２成形アパーチャ側の縮小レンズと前記試料側の対物レンズの２段構成であり、各々のレンズの励磁電流を最適に設定することにより、前記偏向座標軸と基準座標軸とを一致させながら、焦点を合わせることを特徴とする請求項１記載の荷電ビーム描画方法。   The electromagnetic lens has a two-stage configuration of a reduction lens on the second shaping aperture side and an objective lens on the sample side, and the deflection coordinate axis coincides with the reference coordinate axis by optimally setting the excitation current of each lens. The charged beam writing method according to claim 1, wherein focusing is performed while the focus is adjusted. 光軸方向に離間対向配置された第１及び第２の成形アパーチャと、
第１の成形アパーチャと第２の成形アパーチャとの間に配置され、第１の成形アパーチャの像を第２成形アパーチャ上で偏向する成形偏向器と、
前記成形偏向器よりも下流側に設けられ、第１及び第２成形アパーチャの光学的重なり像を試料面上に結像する電磁レンズと、
第１成形アパーチャの座標軸と前記成形偏向器による偏向座標軸とが一致するように、前記成形偏向器に印加する電圧を調整する手段と、
前記成形偏向器による偏向座標軸と前記試料面の基準座標軸とが一致するように、前記電磁レンズの励磁電流を調整する手段と、
を具備してなることを特徴とする荷電ビーム描画装置。 First and second shaping apertures spaced apart in the optical axis direction;
A shaping deflector disposed between the first shaping aperture and the second shaping aperture for deflecting an image of the first shaping aperture on the second shaping aperture;
An electromagnetic lens which is provided downstream of the shaping deflector and forms an optical overlap image of the first and second shaping apertures on the sample surface;
Means for adjusting a voltage applied to the shaping deflector so that a coordinate axis of the first shaping aperture and a deflection coordinate axis by the shaping deflector coincide;
Means for adjusting an excitation current of the electromagnetic lens so that a deflection coordinate axis by the shaping deflector and a reference coordinate axis of the sample surface coincide with each other;
A charged beam drawing apparatus comprising:
JP2003303112A 2003-08-27 2003-08-27 Charged beam drawing method and charged beam drawing apparatus Expired - Lifetime JP4256232B2 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010016170A (en) * 2008-07-03 2010-01-21 Nuflare Technology Inc Method for acquiring offset deflection amount for shaped beam and plotting device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010016170A (en) * 2008-07-03 2010-01-21 Nuflare Technology Inc Method for acquiring offset deflection amount for shaped beam and plotting device

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