DD241812A1

DD241812A1 - ELECTROSTATIC MULTIPOLDEFLECTOR

Info

Publication number: DD241812A1
Application number: DD28166885A
Authority: DD
Inventors: Friedrich Naehring
Original assignee: Akad Wissenschaften Ddr
Priority date: 1985-10-14
Filing date: 1985-10-14
Publication date: 1986-12-24

Abstract

Die Erfindung betrifft einen elektrostatischen Multipoldeflektor, der insbesondere fuer die Steuerung von fokussierten Ionen- bzw. Elektronenstrahlen in entsprechenden Anlagen, vorzugsweise bei der Herstellung von strukturierten Halbleiterbauelementen mit Strukturen im Submikrometerbereich, angewendet werden kann. Das Ziel der Erfindung besteht darin, einen Deflektor bereitzustellen, der bei niedrigem Fertigungsaufwand eine hohe Ablenkempfindlichkeit und geringe optische Fehler aufweist. Der Erfindung liegt die Aufgabe zugrunde, einen elektrostatischen Deflektor zu schaffen, der bei einfachen Aufbau ein dem ideal homogenen elektronischen Feld weitgehend angenaehertes Feld aufweist. Diese Aufgabe wird durch einen elektrostatischen Multipoldeflektor an sich bekannter Bauart mit n Elektroden erfindungsgemaess dadurch geloest, dass die Elektroden zumindest zwei ebene, einen Winkel a mit der Groesse 360:n zueinander bildende Seitenflaechen aufweisen, und die so angeordnet sind, dass die ueber die gemeinsame Kante der Seitenflaechen hinaus verlaengerten Winkelhalbierenden aller Elektroden sich in der Mittelachse des Zylinders oder Kegels treffen. FigurThe invention relates to an electrostatic multi-pole reflector, which can be used in particular for the control of focused ion or electron beams in corresponding systems, preferably in the production of structured semiconductor devices with structures in the submicron range. The object of the invention is to provide a deflector which has high deflection sensitivity and low optical errors at low manufacturing cost. The invention has for its object to provide an electrostatic deflector, which has a largely homogeneous to the ideal homogeneous electronic field largely simple field with a simple structure. This object is achieved by an electrostatic multi-pole reflector of a known type with n electrodes according to the invention that the electrodes have at least two planar, an angle a with the size 360: n mutually forming Seitenflaechen, and which are arranged so that the over the common Edge of the side surfaces extended bisectors of all electrodes meet in the central axis of the cylinder or cone. figure

Description

der Elektroden die Kosinusverteilung besser angenähert als bei Multipoldeflektoren, die nach dem Stand der Technik geformt sind. Mjtdem erfindungsgemäßen Multipoldeflektor lassen sich ca. um den Faktor 10 geringere Abweichungen von der idealen Kosinusverteilung gegenüber bisher bekannten Multipoldeflektoren erreichen. Voraussetzung ist dafür natürlich weiterhin das Anlegen entsprechend optimierter Elektrodenspannungen.of the electrodes approximates the cosine distribution better than multipole reflectors formed in the prior art. Mjtdem Multipoldeflektor invention can be about 10 times lower deviations from the ideal cosine distribution over previously known Multipoldeflektoren reach. The prerequisite for this, of course, continues to be the creation of correspondingly optimized electrode voltages.

Außerdem besitzt der erfindungsgemäße Multipoldeflektor den wesentlichen Vorteil einer sehr einfach zu realisierenden präzisen Herstellung und einer höheren Spannungsfestigkeit durch die größeren Elektrodenabstände.In addition, the multipole reflector according to the invention has the significant advantage of a very easy to implement precise production and a higher dielectric strength due to the larger electrode distances.

Da sich exakte, scharfe Kanten über eine längere Strecke schwer herstellen lassen, ist es vorteilhaft, sie etwas abzurunden oder anzufassen, wobei zur Gewährleistung der angestrebten Feldverteilung der Radius bzw. die Fase der Kante der Seitenflächen viel kleiner als der Abstand der Elektroden zueinander sein muß.Since it is difficult to produce exact, sharp edges over a longer distance, it is advantageous to round or touch them a little, wherein to ensure the desired field distribution of the radius or bevel of the edge of the side surfaces must be much smaller than the distance of the electrodes to each other ,

Eine weitere für die Feldausbildung vorteilhafte Ausgestaltung der Erfindung besteht darin, daß die Breite der Seitenflächen der Elektroden mindestens dem Abstand der Elektroden zueinander entspricht.Another embodiment of the invention which is advantageous for field formation consists in that the width of the side surfaces of the electrodes corresponds at least to the distance of the electrodes from each other.

embodiment

Nachfolgend soll die Erfindung anhand eines Ausführungsbeispieles näher erläutert werden. In der zugehörigen Fig. 1 ist ein aus 8 Elektroden aufgebauter erfindungsgemäßer Mutipoldeflektor dargestellt. Die Spannungen ± V₀ und ± V₁ an den Elektroden sind für Ablenkung des Teilchenstrahls in vertikale Richtung angegeben. Alle Elektroden bestehen aus dreikantigen Stäben, die jeweils 2 ebene Flächen und eine aufgrund der Herstellung der Elektroden aus einem runden Ausgangsmaterial gekrümmte Fläche aufweisen. Die beiden ebenen Flächen schließen einen Winkel α = 360°:8 =45° ein. Aufgrund der ringförmigen Anordnung, der mittigen Austrichtung der Dreikante und der damit parallel zueinander liegende Seitenflächen benachbarter Elektroden wird das elektrische Feld in besonders günstiger Weise aufgebaut. Für den in Fig.1 dargestellten Oktupol betragen die optimalen Elektrodenspannungen für die anzunähernde PotentialverteilungThe invention will be explained in more detail with reference to an embodiment. In the accompanying FIG. 1, a mutipole reflector according to the invention constructed from 8 electrodes is shown. The voltages ± V ₀ and ± V ₁ at the electrodes are indicated for deflection of the particle beam in the vertical direction. All electrodes consist of triangular bars, each having two flat surfaces and a curved surface due to the production of the electrodes from a round starting material. The two flat surfaces enclose an angle α = 360 °: 8 = 45 °. Due to the annular arrangement, the central discharge of the three-edge and thus parallel to each other side surfaces of adjacent electrodes, the electric field is constructed in a particularly favorable manner. For the octupole shown in FIG. 1, the optimum electrode voltages are for the potential distribution to be approximated

V₀ = 0,9808V_s, V₁ = 0,3955V_s;V ₀ = 0.9808V _s , V ₁ = 0.3955V _s ;

wobei V_s der Scheitelwert des Potentials ist, den die ideale Kosinusverteilung auf dem von den Elektrokanten gebildeten Zylindermantel haben würde. Die absolute Abweichung des realen elektrostatischen Potentials V (φ) von dieser idealen Kosinusverteilung V_scoscpbeträgtwhere V _{s is} the peak of the potential the ideal cosine distribution would have on the cylinder jacket formed by the electric edges. The absolute deviation of the real electrostatic potential V (φ) from this ideal cosine distribution V _s coscp is

γ = 0,086 V₈.¹ .· . ' γ = 0.086 V ₈ . ¹ ·. '

φ ist dabei der Winkel um die Zylinderachse. Die entsprechende Abweichung für den bekannten Multipoldeflektor (8 identische, aus einem dünnwandigen Hohlzylinder geschnittene Elektroden) ist 10mal so groß.φ is the angle around the cylinder axis. The corresponding deviation for the known Multipoldeflektor (8 identical, cut from a thin-walled hollow cylinder electrodes) is 10 times as large.

In Fig.2 sind die Vorläufe der idealen Kosinusverteilung 1, der Verteilung nach dem Stand der Technik 2 und nach der Erfindung 3 im ersten Quadranten dargestellt. Sie setzen sich entsprechend der Symmetrie der Kosinusfunktion in den anderen QuadrantenFIG. 2 shows the headers of the ideal cosine distribution 1, the distribution according to the prior art 2 and according to the invention 3 in the first quadrant. They sit in the other quadrants according to the symmetry of the cosine function

Die in diesem Ausführungsbeispiel der Erfindung beschriebenen Elektroden lassen sich aber auch auf einem Kegelmantel zu einem kegeligen Oktupoldeflektor zusammenstellen. Diese Form ist insbesondere für große Auslenkungen des Strahles vorteilhaft. Dann sind die Seitenflächen benachbarter Elektroden zwar nicht mehr parallel zueinander, sondern nur deren Schnittlinien in einem Schnitt senkrecht zur Kegelachse, was jedoch an der oben beschriebenen, coscp weitgehend angenäherten Feldverteilung nichts ändert.However, the electrodes described in this embodiment of the invention can also be put together on a conical surface to form a conical octopole reflector. This shape is particularly advantageous for large deflections of the beam. Although the side surfaces of adjacent electrodes are no longer parallel to each other, but only their cutting lines in a section perpendicular to the cone axis, but this does not change the above-described, coscp largely approximated field distribution.

Claims

Invention claim:

1. Elektostischer Multipoldeflektor, consisting of a number of η rod-shaped, on an imaginary cylinder or cone sheath at equal intervals arranged electrodes, characterized in that the electrodes have at least 2 flat, an angle with the size 360 °: n forming side surfaces , and which are arranged so that the extended over the common edge of the side surfaces also bisectors of all electrodes meet in the central axis of the cylinder or cone.

2. Elektostischer Multipoldeflektor according to item 1, characterized in that the common edges of the side surfaces of the electrodes are rounded or broken (chamfered), wherein the radii or the widths of the chamfers are much smaller than the distance of the electrodes to each other.

3. Eletrostatic Multipoldeflektor according to item 1, characterized in that the width of the side surfaces of the electrodes at least equal to the distance of the electrodes to each other.

For this 1 page drawings

Field of application of the invention

The invention relates to an electrostatic Multipoldeflektor, in particular for the control of focused ion or. Electron beams in appropriate systems, preferably in the production of structured semiconductor devices with structures in the submicron range, can be applied.

Characteristic of the known technical solutions

Electrostatic deflectors serve to deflect charged high energy particles to control their trajectory and impact on a target. In addition to the very simple, in their parameters but insufficient parallel plate deflectors multi pole or Schlesinger deflectors have been presented, which are characterized in particular by a higher deflection sensitivity and improved optical properties (J. Kelly, Adv. Electronics Electron Phys 43 [1977] ] 43).

Important for low optical errors in the deflection is a large homogeneity of the electrostatic field within the deflector. An ideal homogeneous field would mean that the potential along a base circle whose center is struck vertically by the incoming beam would be cosinusoidal. In addition, a common center for the deflection in the x and y direction should be available for good controllability. With Multipoldeflektoren, which consist of a finite number of symmetrically arranged on an imaginary truncated cone or cylinder jacket rod-shaped electrodes, the cosine distribution when applying correspondingly optimized voltages is approximately to achieve, the previously achieved approximations are still unsatisfactory. In addition, either a rather complicated eletrical network for generating the individual electrode voltages is required or the rods must have different cross-sections.

The Schlesinger deflector (supra), which consists of four identical electrodes (two for x and two for y deflection), which are arranged in an meandering manner on an insulating or imaginary cylinder jacket, causes the particles to fly along the cylinder axis are always influenced simultaneously by the field of the x-undy electrodes, whose direction varies periodically through the meandering shape of the electrodes, thus making the desired cosine distribution averaged over time. The Schlesinger deflector, like the electrostatic multipole, has a common center for the deflection in the x and y directions. He has a similar large deflection sensitivity. For a comparison of both with respect to field homogeneity and aberration missing the data of the Schlesinger deflector, which does not require the higher electrical effort for the control, but it is much more expensive to manufacture it.

Object of the invention

The object of the invention is to provide a deflector which has high deflection sensitivity and low optical errors at low manufacturing cost.

Explanation of the essence of the invention

The invention has for its object to provide an electrostatic deflector, which has a largely homogeneous ideal ideal electric field with a simple structure.

This object is achieved by an electrostatic Multipoldeflektor per se known type with η electrodes according to the invention that the electrodes have at least two planar, an angle α with the size 360 °: n forming side surfaces, and which are arranged so that the over common edge of the side surfaces of extended bisectors of all electrodes meet in the central axis of the cylinder or cone. From the condition that the considered flat side surfaces make an angle of 360 °: n to each other, in the case of the cilindrical arrangement, it follows that adjacent side surfaces of adjacent electrodes are parallel to each other. In the case of the conical arrangement, at least their cutting lines are parallel to each other in a section perpendicular to the cone axis. The electric field forming between the planar side surfaces of adjacent electrodes is approximately homogeneous and thus represents a continuous transition between the electrode potentials. In this way, in conjunction with the relatively sharp edge