JPS61135036A - Charged beam optical lens-barrel - Google Patents

Abstract

PURPOSE:To simplify the structure of a charged beam optical lens-barrel by using a deflection device which consists of a pair of parallel plate electrodes, located in such a manner as to make the deflection center coincide with the main surface of a final-stage lens, and two pairs of parallel plate electrodes located in front of and in the back of said two parallel plate electrodes. CONSTITUTION:A charge beam optical lens-barrel for an electron beam exposure device of a similar device is constituted by installing a first electrostatic deflector, consisting of parallel plate electrodes 41 and used to deflect the beam in X-direction, along the main surface (P) of a final-stage lens 34 and installing a second electrostatic deflector, consisting of parallel plate electrodes 42 and 43 and used to deflect the beam in Y-direction, over and under the first deflector. Because of the above structure, linear lines of electric force are produced among the electrodes 41-43 and not only the center of X-direction deflection but also that of Y-direction deflection coincide with the main surface (P) of the objective 34, thereby simplifying the electrostatic deflectors with low aberration. Besides, it is possible to reduce the number of driving power supplies for the deflectors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a charged beam optical LT tube used in a charged beam device such as an electron beam exposure device or an ion beam exposure device.

(Technical background of the invention and its problems) In recent years, electron beam exposure equipment has been developed to form desired patterns on samples such as semiconductor wafers and mask substrates, but this equipment uses an electron gun.

An electron beam optical cylinder consisting of various lens systems, various deflection systems, etc. is used. This kind of electron beam optical MI
! When the electron beam exposure apparatus is of a continuous sample stage movement type, an electrostatic deflector is generally used as a beam scanning deflector. Furthermore, in the case of the sample stand step-and-repeat method, i! Magnetic deflectors are often used. and,
Due to the need for high-speed writing, the beam scanning deflector is currently shifting from an electrostatic deflector to an electrostatic deflector. However, the electrostatic deflection of the conventionally used Brilens double deflection method is impractical due to large aberrations when the scanning field of view increases to a certain extent. For this reason, multi-electrode electrostatic deflectors with 8 to 20 poles have come to be used.

However, the electron beam optical column using a multi-electrode electrostatic deflector has the following problems (1) to (5).

(1) The structure is complicated and manufacturing thereof is extremely difficult.

(2) Since the machining accuracy is not very high, in order to compensate for this, the overall dimensions must be increased to relatively improve the accuracy, and for this reason, a large driving voltage is required.

(3) Because a large number of electrodes are closely packed and insulated, the surface area of the metal surface is large relative to the space, and when a vacuum is created, a large amount of gas is generated.Moreover, the exhaust must be evacuated from a narrow space, and the beam passes through it. The degree of vacuum in some areas does not improve.

(Since it is necessary to apply different voltages to all eight electrodes, multiple drive power supplies are required.

(Compared to a 5-parallel plate deflector, the deflection sensitivity is lower, the electrodes need to be longer, the total length of the lens barrel becomes longer, and the empty r1
The beam blur due to the charge effect increases.

Note that the above-mentioned problem is not limited to electron beam optical barrels, but also applies to ion beam optical barrels.

[Purpose of the invention]

An object of the present invention is to provide a charged beam optical lens barrel that can simplify the configuration of an electrostatic deflector while having low aberrations, and can reduce the number of driving power sources for the electrostatic deflector. be.

(Summary of the Invention) The gist of the present invention is to configure an electrostatic deflector by arranging a plurality of parallel plate electrodes.

The advantages of using an 8-pole or 20-pole multi-electrode electrostatic deflector are:
The purpose is to make the center of deflection coincide with the main surface of the focusing lens in both the X and Y directions. 4 ordinary parallel plate electrodes
If they are placed at the same two positions, the lines of electric force will not be straight lines but curved lines, which will immediately cause large aberrations. In order to avoid this, a pair of parallel plate electrodes are provided with respect to one axis at positions where the main surface of the lens and the center of deflection substantially coincide. In addition, two pairs of parallel plate electrodes are installed before and after the other axis so that the combined deflection center of the two electrodes coincides with the center of the lens.

That is, the present invention provides a charged beam optical column that irradiates a charged beam emitted from a charged beam emission source onto a sample with a focused deflection Ill 10 t, such that the center of deflection coincides with the main surface of the final stage lens. A pair of parallel flat plates 1 provided
a first electrostatic deflector that deflects the beam in one direction; and two pairs of parallel plate electrodes provided before and after the final stage lens, respectively. A deflection device is configured with a second electrostatic deflector that deflects in a direction perpendicular to the deflection direction.

〔Effect of the invention〕

According to the present invention, the following effects (1) to (4) can be obtained.

■ The drive 74 sources for the electrostatic deflector are +x, -x, +y.

-y and 4 pieces are sufficient, and the voltage on the + side and the one side can be the same, reducing the driving power supply by half or less.

■ The number of electrodes in the electrostatic deflector is reduced to 6, and the structure is simple because it is a parallel flat plate.

■ Since the center of deflection and the principal surface of the lens coincide on both axes, aberrations are low.

■ Because it is a parallel plate electrode, the electric field distribution is uniform throughout the electrode space. This is in contrast to an 8-pole multi-electrode electrostatic deflector, etc., which has a uniform electric field distribution of only about half the inner diameter of the electrodes. Therefore, the distance between the parallel plates can be reduced, and the deflection sensitivity can be increased. Therefore, it is possible to reduce the driving voltage or shorten the lens barrel length.

■ Since the structure is simple with parallel flat plates, the surface area is small and the structure is easy to pump out, increasing the degree of vacuum in the space through which the beam passes and stabilizing the beam.

(Embodiment of the Invention) FIG. 3 is a schematic configuration diagram showing an electron beam exposure apparatus using an electron beam optical lens barrel according to an embodiment of the invention.

In the figure, reference numeral 11 denotes a sample chamber, and within this sample chamber 11 is housed a sample stage 13 on which samples 12 such as semiconductor wafers are held. The sample stage 13 is driven by a stage drive system 14 that receives a command from the computer 20 through one interface, and is moved in the X direction (left-right direction in the paper) and Y direction (front and back direction in the paper). Then, the moving position of the stage 13 is measured by the laser length measuring system 15 and sent to calculation [20].

On the other hand, above the sample chamber 11, an electron beam optical lens barrel upper stop according to this embodiment is disposed. The electron beam optical column 30 includes an electron fc31. Various lenses 32, 33, 34
．． Various deflectors 36.37 and aperture masks 38.3
It is composed of 9 mag. The deflector 36 directs the beam to 0N
- It is a blanking deflector for turning off, and is given a deflection voltage by the blanking circuit 16. The deflector 37 is a beam scanning deflector (electrostatic deflector) for scanning the beam on the sample 12 in the X direction and the Y direction,
As will be described later, it is provided at the position of the final stage lens (objective lens) 34. The deflector 37 is supplied with a deflection voltage by the scanning circuit 17.

Here, the beam scanning deflector 37 is composed of three parallel plate electrodes 41, 42, and 43 as shown in FIG. The parallel plate electrode 41 serves as a first electrostatic deflector that deflects the beam in the X direction, and is provided at the main surface P of the objective lens 34 . The center of deflection of this electrode 41 coincides with the main surface P of the lens 34. Further, the parallel plate electrodes 42 and 43 constitute a second electrostatic deflector that deflects the beam in the Y direction.The electrode 42 is provided above the electrode 41, and the electrode 43 is provided below the electrode 41. It is set in. When deflecting the beam in the Y direction, as shown in FIG. 2, the beam is deflected to the right in the drawing by the parallel plate electrode 42, and further deflected to the right in the drawing by the parallel plate electrode 43. And the electrode 43
The deflection center of the beam exiting the lens 34 coincides with the main surface P of the lens 34.

In addition, parallel plate i! The poles 42 and 43 have the same deflection sensitivity and are arranged at the same distance from the parallel plate electrode 41,
Moreover, the same voltage is applied to both during deflection. In addition, 51 in the first factor is a cylinder housing a deflector, an aperture mask, etc., and 52 is a parallel plate electrode 41 (42, 4
The insulating attachment for fixing the cylindrical body 51 to the cylindrical body 51 is shown as a tool.

With this configuration, the parallel plate electrodes 41, 42° 43 for forming the first and second electrostatic deflectors are arranged at different positions, so that no electric force is generated between each electrode. The line becomes a straight line.

Furthermore, the center of deflection coincides with the main surface P of the objective lens 24 not only in the X direction but also in the Y direction. Therefore, effects such as those described in (1) to (4) described above can be obtained, and it is possible to increase the drawing speed and improve the drawing accuracy.

Note that the present invention is not limited to the embodiments described above. For example, the two pairs of parallel plate electrodes that make up the second electrostatic deflector do not necessarily have to have the same sensitivity, and they need to be roughly equidistant from the parallel plate electrode that makes up the first electrostatic deflector. Nor. In short, the beam deflected by the parallel plate electrode in the front stage is redirected by the parallel plate 1i pole in the rear stage, and the deflection sensitivity and deflection voltage are controlled so that the center of deflection coincides with the main surface of the final stage lens. good. Further, the configuration of the optical system upstream of the electrostatic deflector for beam scanning is not limited to that shown in FIG. 3, and can be changed as appropriate according to specifications. Furthermore, ion beam optics using an ion beam instead of an electron beam can also be easily applied. In addition, t! which does not depart from the gist of the present invention! This can be implemented with various modifications.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main structure of an electron beam optical column according to an embodiment of the present invention, FIG. 2 is a schematic diagram for explaining the deflection effect of two pairs of parallel plate electrodes, and FIG. 3 1 is a schematic configuration diagram showing an electron beam exposure apparatus using the above electron beam optical column. DESCRIPTION OF SYMBOLS 11... Sample chamber, 12... Sample, 13... Sample stage, 14... Stage drive system, 15... Laser length measurement system, 16... Blanking circuit, 17... Scanning circuit, 18... power supply, 19... interface,
20...control computer, knee...electron optical lens barrel, 31...
...electron gun, 32°33.34...lens, 36.3
7... Deflector, 38° 39... Aperture mask,
41, 42, 43...parallel plate electrodes. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (2)

[Claims] (1) In a charged beam optical column that focuses and deflects a charged beam emitted from a charged beam emission source and irradiates it onto a sample, a pair of lenses are provided so that the center of deflection coincides with the main surface of the final stage lens. a first electrostatic deflector that deflects the beam in one direction; and two pairs of parallel plate electrodes provided before and after the final stage lens, respectively, to deflect the beam in one direction. A charged beam optical lens barrel comprising a second electrostatic deflector that deflects in a direction perpendicular to the direction of deflection by the deflector. (2) The second electrostatic deflector is configured such that each deflection direction of the beam by the front-stage and rear-stage parallel plate electrodes is a circumferential direction, and the deflection center of the second electrostatic deflector is aligned with the main surface of the front-last stage lens. A charged beam optical lens barrel according to claim 1, characterized in that the charged beam optical lens barrel is: