JPS62273720A - Charged particle beam lithography equipment - Google Patents

Abstract

PURPOSE:To obtain a charged particle beam lithography equipment which can form an accurate pattern even with a large deflecting unit by superposing a voltage for an astigmatism correction of the beam on the electrodes of a multipolar deflector in addition to a voltage for generating a deflecting electric field, and varying a voltage value upon deflecting to scan the beam to easily correct the astigmatism of the beam occurring by the scanning by deflecting. CONSTITUTION:A scanning deflector 24 has octode deflector having 8 rodlike electrodes 24a-24h disposed at an equal on the same circumference, and a predetermined deflecting voltage from a deflecting voltage generator 25 is applied to the electrodes. Symmetrical astigmatism correction voltages Va, Va,-Va,-Va are applied twice from an astigmatism voltage generator 26 on deflecting voltages Vx,-V1, Vy,-Vy to be applied to the electrodes 24a, 24e opposed to a direction (x) and the electrodes 24c, 25g opposed in a direction (y). When such a voltage is applied to the electrodes 24a-24h of the deflector 24, the deflector 24 generates a deflecting electric field designated by lines 27 of electric force and an astigmatism correction electric field designated by lines 28 of electric force. Accordingly, the voltage Va is suitably set to simultaneously perform both the scanning deflection and the astigmatism correction.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a charged beam lithography system, and particularly to a charged beam lithography device with an improved scanning deflector. It relates to a drawing device.

(Prior Art) In recent years, electron beam lithography devices have been used as devices for forming fine and high-density patterns for VLSIs and the like. Among electron beam lithography apparatuses, those using a variable beam beam type are particularly capable of performing lithography with high precision and high throughput. For this reason, it is impossible to transfer with light.
It is suitable as an apparatus for directly drawing a VLSI pattern with a design rule of [μm] or less on a wafer.

FIG. 4 shows an example of an electron optical system of this type of conventional device.

In the figure, 31 is an electron gun, and 35 is a first electron gun having a shaped aperture.
A shaped aperture mask 33, 34 a condenser lens for illuminating the mask 35, 38 a second shaped aperture mask, 37 projects the aperture image of the mask 2 onto the mask 38, and produces a synthesized aperture image. 36 is a dimension-variable deflector for varying the dimensions of the synthesized aperture image by varying the overlap between the aperture image of the mask 35 and the aperture of the mask 38;
39 is a reduction lens, 4n is an objective lens for projecting the reduced synthetic aperture image onto the sample surface 42, 4n is a scanning deflector for positioning the beam position on the sample surface 42, and 43 is an astigmatism correction coil. It is. By the way, in such a device, a multipole deflector is used as a deflector for the purpose of high-precision drawing, which has the advantage of having small deflection distortion, the deflection centers in the X and Y directions being aligned, and being able to improve drawing accuracy. Used in drawing devices.

However, even when a multipole deflector is used, uniform and sufficient resolution may not be obtained over the entire scanning region due to astigmatism caused by deflection scanning of the electron beam. In particular, when the deflection area is expanded for high throughput writing, the astigmatism associated with the deflection scanning described above becomes a non-negligible amount.

Conventionally, astigmatism correction has been carried out by changing the excitation of the astigmatism correction coil 43, as shown in FIG. It was difficult to make corrections at high speed.

(Problems to be Solved by the Invention) The present invention has been made in consideration of the above circumstances, and its purpose is to easily and quickly correct the astigmatism of an electron beam caused by deflection scanning. It is an object of the present invention to provide a charged beam drawing device that can form a high-definition pattern even in a device that uses large deflections.

[Structure of the invention]

(c) Means for Solving Problems) The gist of the present invention is to superimpose a voltage for astigmatism correction of a charged beam in addition to a voltage for generating a deflection electric field in each electrode of a multipole deflector. , and to change the value of the voltage as the charged beam is deflected and scanned.

That is, the present invention provides a charged beam drawing apparatus that draws a desired pattern on a nuclear sample by focusing a charged beam emitted from a charged beam radiation source onto the sample and scanning the sample with a scanning deflector. 4n scanning deflector
(n is a positive integer) deflection electrodes are used to apply a deflection voltage, and a 2-fold or 4-fold symmetric astigmatism correction voltage is superimposed on each of the 4n electrodes, and the beam is The value of the superimposed voltage is changed in accordance with the scanning deflection.

(Function) According to the present invention, since the multipole deflector performs astigmatism correction of the charged beam, the resolution of the charged beam on the sample is improved without providing a separate means for astigmatism correction such as an astigmatism correction coil. can. Furthermore, by changing the astigmatism correction voltage superimposed with scanning deflection, it is possible to improve the resolution during deflection. Furthermore, since it uses an electrostatic deflector that is free from hysteresis, high-speed operation is possible, and high-speed, large-deflection, and high-definition drawing can be performed.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing an electron beam lithography apparatus according to an embodiment of the present invention. In the figure, numeral 11 is an electron gun, and the electron beam emitted from this electron gun 11 is transmitted through various lenses.
The sample portion 17 is irradiated via the beams 2 to 16. here 12
．． 13 is a condenser lens, 14 is a projection lens, 15 is a reduction lens, and 16 is an objective lens. A first shaped aperture mask 21 is arranged between the condenser lens 13 and the projection lens 14, and the projection lens 14 and the reduction lens 1
A second aperture mask 22 is arranged between the two apertures 5 and 5. Also, the first aperture mask 21 and the projection lens 14
A dimension variable deflector 23 is arranged between the masks 21 and 22 to vary the dimensions of the aperture image by changing the overlapping of the apertures of the masks 21 and 22.

A scanning deflector 24 for scanning the beam on the sample surface 17 is arranged inside the objective lens 16 . Here, the scanning deflector 24 consists of an 81-pole deflector configured by arranging eight rod-shaped electrodes 24a to 24h at equal intervals on the same circumference as shown in FIG. As shown in the figure, a predetermined deflection voltage is applied from a deflection voltage generator 25. That is, a voltage of opposite polarity is applied between the opposing electrodes, and the electrodes 24a, 24 facing each other in the X direction
e is the X-direction deflection voltage ■8. Vx is deflected in the y direction at the electrodes 24c and 24g facing in the x direction.
r Vy Ka, middle fiJ1(7)ti24 b, 2
4d.

An intermediate voltage between adjacent electrodes is applied to 24f and 24h, respectively.

The aforementioned deflection voltage (8) is applied to the electrodes 24a and 24e facing each other in the X direction and the electrodes 24C and 24g facing each other in the X direction. −
Two-fold symmetrical astigmatism correction voltages v, , va, -va, -va are applied from an astigmatism voltage generator 26 superimposed on people, v, , -v, respectively.

Apply the voltage as described above to each electrode 248 of the 8 weight deflector 24.
24h, a deflection electric field shown by the lines of electric force 27 in FIG. 2 and an astigmatism correction electric field shown by the lines of electric force 28 in FIG. 2 are generated inside the deflector 24. Therefore, by setting the value of the astigmatism correction voltage (8) appropriately, scanning deflection and astigmatism correction can be performed simultaneously. Astigmatism that occurs with scanning deflection depends on the scanning deflection direction and scanning deflection amount, so the value of correction voltage
and must be changed according to the value to the X-direction deflection voltage. The curve 29 in FIG. 3 shows the relationship between a typical X-direction deflection type press-fit and the correction voltage input, and the curve 30 shows the relationship between the y-direction deflection voltage outside and the correction voltage V8.

As described above, in this embodiment, astigmatism correction is performed using the 8-weight deflector, so there is no effect of hysteresis, which was a problem in the conventional example, so that astigmatism caused by scanning deflection can be corrected at high speed.

Although the case where one deflector and eight weight deflectors are used has been described above, the present invention is generally applicable to weight deflectors with 4 electrodes or 16 weight deflectors and 4n (n is a positive integer) weight deflectors. Further, in the above description, a case has been described in which the present invention is applied to an electron beam lithography apparatus, but the present invention can also be applied to a charged beam lithography apparatus such as an ion beam lithography apparatus.

〔Effect of the invention〕

As described above, the charged beam lithography apparatus according to the present invention can quickly correct the astigmatism associated with scanning deflection, and can realize a high-speed, high-precision charged beam lithography apparatus.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an electron beam lithography apparatus according to an embodiment of the invention, FIG. 2 is a diagram showing voltage distribution of eight weight deflectors used in the apparatus of FIG. 1, and FIG. FIG. 2 is a diagram showing a typical example of the relationship between the deflection voltage applied to the 8-weight deflector and the astigmatism correction voltage, and FIG. 4 is a schematic configuration diagram showing a conventional electron beam lithography apparatus. ] 1.31... Electron gun, 12-16, 33, 34° 37.39.4n... Lens, 24.4n... Scanning deflector, 24 a-24h... Scanning deflector (8 weight deflector) electrode. Agent Patent Attorney Nori Chika Yudo Takehana Kikuo Figure 1

Claims (1)

[Claims] An objective lens that focuses the charged beam emitted from the charged beam radiation source onto the sample, and 4n objective lenses (n is a positive integer) arranged at equal intervals on concentric circles that scan the beam on the sample.
In a charged beam lithography apparatus equipped with a scanning deflector consisting of electrodes, a deflection voltage is applied to the 4n scanning deflection electrodes, and each of the 4n electrodes is
A charged beam lithography apparatus characterized in that a rotationally symmetrical astigmatism correction voltage is superimposed, and the value of the superimposed correction voltage is changed in accordance with the scanning deflection of the beam.