JPS5986219A - Charged beam type optical lens barrel - Google Patents

Abstract

PURPOSE:To facilitate alignment between optical systems thereby to permit an improvement in working efficiency, by providing a beam current detector. CONSTITUTION:A beam current detector constituted by a coil is provided at one or more arbitrary positions on the part of a beam transport path on the downstream side of a blanking electrode 21, and a beam is modulated by the blanking electrode 21, thereby making it possible to measure the beam current at the position where the beam current detector is provided without affecting the beam. For example, current detector coils 230a-230e are respectively disposed under apertures. The arrangement is such that whether or not the beam is intercepted by a projection lens aperture owing to, for example, the deflecting operation is judged simply by making comparison between the respective outputs of control circuit 28, 29 connected to the beam current detectors.

Description

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

[Prior art and its problems]

Recently, various electron beam exposure apparatuses have been developed to form fine patterns on samples such as semiconductor wafers and mask substrates. Among these devices, a variable beam size type electron beam exposure device, which performs writing while changing the size and shape of the electron beam, is said to be most suitable for high-speed writing.

FIG. 1 is a schematic diagram showing the main parts of a conventional forceps beam optical mirror used in such an apparatus.

In the figure, 1 is the Nariko gun, 2 is the first condenser lens, 3 is the blanking pole, 4 is the second condenser lens, 5 is the first aperture mask for the beam pot shape, and 6 is the deflection electrode for changing the beam size. , 7 is a projection lens, 8 is a second beam bottle type
9 is an aperture mask, 9 is a reduction lens, 10 is a scanning deflection pole, 9' is an objective lens, and 40 is a sample. The first crossover P s formed at the center of the blanking polarization 3
An image is formed at the center of the deflector 6 by the second condenser lens, and a second crossover P2 is formed at the center of this deflection. The image of the l-th aperture mask 5 is formed on the second aperture mask 8 by the projection lens 7. When the aperture beam is deflected in a predetermined direction by the deflector 6, the position of the aperture image relative to the aperture of the second aperture mask 8 changes. As a result, when the image of the second aperture mask 8 is formed on the sample surface using the reduction lens 9, the objective lens 11, etc., the image finally formed on the sample surface is the image of the second aperture mask 8. This is the overlapped portion between the aperture and the image of the first aperture mask 5 formed on its surface. Therefore, by deflecting the ion beam with the deflector 6, the size and shape of the beam irradiated onto the sample surface can be varied.

However, the equipment in this building had the following problems. That is, in the configuration shown in FIG.
The beam passes through the center of the aperture of the lens on the projection lens 7, reduction lens 9, and objective lens 9', and the beam is not blocked by the aperture even if the beam is deflected by operating the beam dimension changing deflection pole 6. Otherwise, a good shaped beam cannot be obtained. This made adjustments complicated and reduced work efficiency.

Note that the above-mentioned problem is not limited to the mass beam optical tube but also applies to the ion beam optical tube.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a charged beam optical lens barrel that can facilitate axis alignment of an optical system and improve work efficiency.

[Summary of the invention]

The gist of the present invention is to attach a beam current detector consisting of a coil 230 as shown in FIG. The purpose of this method is to make it possible to measure the beam current at that point without affecting the beam. 220 is a blanking plate.

That is, the present invention has one or more sets of blanking-poles and 2
At least one beam current detector in a bamboo ridge beam tube equipped with two beam shaping aperture masks and one or more sets of deflectors, which variably controls the size and shape of the charged beam and irradiates the beam onto the sample. It is equipped with a.

[Yumei's effect]

According to the present invention, the beam current at any point on the beam transport path can be measured without affecting the beam, and the behavior of the beam under actual operating conditions can be analyzed. In turn, alignment of the axes can be facilitated and productivity can be improved.

[Embodiments of the invention]

FIG. M3 is a schematic configuration diagram showing a single beam optical lens barrel according to an embodiment of the present invention. Components that are the same as those in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

21 to 26 are respectively C's subgun alignment coil, second condenser alignment coil, projection lens alignment coil, reduction lens alignment coil, and objective lens alignment coil, and 127 to 31 are respectively explained in FIG. This is a control circuit that detects a stain current through the coils 230a to 230e of a beam current detector such as the one shown in FIG.

The operation of the thus constructed Yokobeam optical sharp tube will be explained.

Variable beam dimensions as described above - Child beam optical column Teha Projection lens on the beam transport path Aperture reduction lens Aperture Objective lens If the beam blocked by the aperture changes in response to changes in beam dimension, it will change depending on the shaping dimension at the sample surface. The substream density changes. Therefore, the adjustment was complicated and time-consuming.

Therefore, as shown in Fig. 3, subcurrent detector coils 2308 to 230e are placed under each aperture, and then a current detector is connected to detect whether the beam is even cut off by the deflection operation, etc. control circuit 28.2
All you have to do is compare the outputs of 9.

The sensitivity of the beam current detector is determined by the distance r from the beam center to the coil center when the cross-sectional shape is as shown in Figure 2.
The area of 1 coil is sl The beam current is -1 (1sin
wt (where W is blanking frequency, t is time, I
O is the beam current during non-blanking 1 The specific M magnetic flux of the core material of the coil is μ, and the voltage generated is μ・μoIos V == nw 2πr As a typical value, r-=l, 5J , S=Icm, l
0=1 ttA.

w==4πXl07(20?, 1f(z), n=100
0. Assuming n=1000, V=1.70 (mV'). By detecting this voltage, the beam current can be determined.

[Other Embodiments of the Invention] The current detector 31 in FIG. 2 can also be used in a crossover reduction type device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional electron beam optical column, FIG. 2 is a diagram showing an example of a current detector, and FIG. 3 is a schematic diagram showing an electron beam optical acute part according to an embodiment of the present invention. FIG. 3... Blanking pole, 6... Electrode for beam size change, 23 (la to 230f... Magnetic field detection coil, Fig. 1 # Fig. 2

Claims (1)

[Claims] A charged beam optical column that is equipped with two beam shaping aperture masks and a side deflector, variably controls the size and shape of a charged beam, and has at least one set of blanking electrodes that irradiates the beam onto a sample surface, A beam current detector using a magnetic field detection coil is installed at at least one center of the beam transport path, the beam is modulated by blanking polarization, and the current is detected by the beam current detector. Heem optical inkstone cylinder.