JPS5875746A - Optical lens-barrel for changed beam - Google Patents

Abstract

PURPOSE:To deflect a beam at a high response speed and reduce the mounting mechanical accuracy of a shaping aperture mask by using an electrostatic deflector that varies the dimensional shape of the beam. CONSTITUTION:The first electrostatic deflector 4 consists of an x directional deflector 4a and a y directional deflector 4b and is used as a beam deflector that varies the dimensions and shape of a beam. The second electrostatic deflector 5 consists of an x directional deflector 5a and a y directional deflector 5b in the same way as the first electrostatic deflector 4 and restores the beam deflected by the first electrostatic deflector 4. Besides, beam mounting accuracy correction coils 6 and 7 (electromagnetic deflectors) are arranged outside vacuum at the outside of the respective deflectors 4 and 5. Further, a reducing lens 8 and an objective lens 9 are arranged at the lower part of the second aperture mask 3. The electron beam emitted from an electron gun allows its dimensional shape to be varied by the beam shaping aperture masks 2 and 3 and the electrostatic deflectors 4 and 5 and is irradiated on a sample surface 10.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a charged beam optical column used in a charged beam exposure apparatus such as an electron beam exposure apparatus or an ion beam exposure apparatus, and particularly relates to a charged beam optical column used in a charged beam exposure apparatus such as an electron beam exposure apparatus or an ion beam exposure apparatus. This invention relates to an improved charged beam optical column having a function of variably controlling the shape.

(2) Prior Art Recently, various electron beam exposure apparatuses have been developed for forming fine patterns on samples such as semiconductor wafers and mask substrates. Among these devices, drawing is performed while changing the size and shape of the electron beam.
It is said that a so-called variable beam dimension type electron beam exposure apparatus is most suitable for high-speed writing.

By the way, recently, as an electron beam optical column used in an electron beam exposure apparatus with a variable beam size, a projection lens between two beam shaping aperture masks has been omitted, and two sets of deflectors have been installed between each aperture mask. It has been proposed to vary the size and shape of the beam by arranging it. This allows the projection lens to be omitted by increasing the reduction ratio of the lens system and increasing the depth of focus at the object point. Since the lens can be omitted, the structure can be simplified and costs can be reduced.

(3) Problems with the Prior Art In the device using the four sets of deflectors described above, an electromagnetic deflector is usually used as the deflector in order to perform a large deflection with a small amount of electric power. Electromagnetic deflectors have a faster response time than electrostatic deflectors.

It is slow and therefore not suitable for high-speed drawing. Further, unless the precision of the machine for attaching the two beam-shaping aperture masks is extremely high, there are problems such as blurring of the new assembly. Furthermore, since an electromagnetic deflector is used to deflect the beam, the ferrite must be placed in a vacuum, resulting in disadvantages such as poor beam stability. Further, such problems also apply to ion beam optical barrels.

(4) Purpose of the Invention The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to achieve It is an object of the present invention to provide a charged beam optical column that can deflect a charged beam with a fast response speed and that can reduce the mechanical precision of attaching an aperture mask for beam shaping.

(5) Summary of the Invention The present invention provides a charged beam optical column that variably controls the size and shape of a charged beam, in which at least one of two sets of electrostatic deflectors for changing the beam size is replaced by two beam shaping plates. When placed between the aperture masks, electromagnetic deflectors S for optical axis correction are placed on the outside of the electrostatic deflectors, respectively. In other words, the deflection for changing the beam dimensions was performed using an electrostatic deflector with a fast response time, and the correction of the accuracy of the electrosealing machine of the Aber Chiyama mask was performed using an electromagnetic deflector that could perform large deflections with low power. It is something.

(6) Effects of the invention Since the deflection for changing the beam size can be performed electrostatically,
The beam size can be changed at high speed. Further, even if the accuracy of the mounting machine for the two aperture masks is poor, it can be corrected electromagnetically, so that the precision of the mounting machine for the aperture masks can be made loose. Furthermore, there is no need to arrange a ferrite in a vacuum, and the beam stability can be improved.

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

The figure is a schematic diagram showing an embodiment in which the present invention is applied to an electron beam exposure apparatus. 1 in the figure is a condenser lens,
Below this lens 1, first and second beam shaping aperture masks 2.3 are arranged facing each other and separated from each other. A first and a second electrostatic deflector 4.5 are arranged between the aperture masks 2, 3, respectively.

The first electrostatic deflector 4! It consists of a direction deflection plate 4a and a y-direction deflection plate 4b, and is used for beam deflection to change the size and shape of the beam. Second electrostatic deflector 5
is the same as the first electrostatic deflector 4! It consists of a direction deflection plate 5a and a y direction deflection plate 5b, and the first electrostatic uneven thickness Wk
The beam deflected by step 4 is deflected back. Further, a beam encapsulation accuracy correction coil 6.7 (electromagnetic deflector) is arranged outside the vacuum outside each deflector 4.5. Furthermore, a reduction lens 8 is provided below the second aperture mask 3.
and an objective lens 9 are arranged. 1. An electron beam emitted from an electron gun (not shown) is changed in size and shape by a beam shaping aperture mask 2.3 and electrostatic deflectors 4, 5, and then irradiated onto a sample surface 10. .

In addition, the reduction ratio of the beam shaping aperture mask 3 on the sample surface is 1/4oo, and the maximum beam dimension is 1 [μm].
The beam resolution by separating the two beam-shaping aperture masks 2.3 was set to 0.1 [μm], and the half-aperture angle at the sample surface 10 was set to 10 [mm]. A distance of 10- is allowed between the aperture masks 2 and 3. Electrostatic deflector 2
．． 3 has a length of 20 (■), and the shadow of the first aperture mask 2 is 1 * 50 at the position of the second aperture mask 3.
[μm] deflection is sufficient, and it is possible to do so without extremely shortening the electrode spacing. The mounting mechanical accuracy of the aperture masks 2 and 3 with respect to the optical axis is approximately ±0.2 (■) because the distance between them is 10 (countries). This ±0.2 (μm
] is corrected by the electromagnetic deflectors 6 and 7. With electromagnetic deflection s6°7, it is difficult to deflect at high speed, but
It is a harmful bird that performs a large deflection with a small amount of power. For this reason, the accuracy of the mounting machine for the Percha masks 2 and 3 only needs to be corrected once every time the Aberperture mask 2.3 is replaced, and high-speed deflection is not required, so it can be used satisfactorily.

As described above, according to this embodiment, the deflection for changing the size and shape of the electron beam can be performed electrostatically, and the speed of the size changing operation can be increased. Furthermore, the deviation of the shear aperture mask 2.3 is corrected by the electromagnetic deflectors g and F.

The precision of the mounting machine for the Aba Chiyama Masks 2 and 3 can be made looser. In addition, an electromagnetic deflector 6 that requires ferrite
．． 7 is placed outside the vacuum, the beam stability can be improved.

(8) Modifications of the invention Note that the invention is not limited to the embodiments described above. For example, a second deflector for deflecting the beam deflected by the first electrostatic deflector may be arranged below the second aperture mask. Also,
The present invention can be applied not only to electron beam exposure apparatuses but also to ion beam exposure apparatuses. Furthermore, the present invention can be applied not only to exposure apparatuses but also to various charged beam apparatuses. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

The figure is a schematic configuration diagram showing an embodiment in which the present invention is applied to an electron beam exposure apparatus. 1... Condenser lens, 2.3... Aperture mask for beam shaping, 4.5... Electrostatic deflector, 4*, 5
m...x direction deflection plate, 4b, 5b-7 direction deflection plate, 6
, 1... Beam installation accuracy correction coil (electromagnetic deflector) 8
...reducing lens, g...objective lens, 10...sample surface.

Claims (1)

[Claims] Two beam shaping aperture masks arranged opposite to each other, two sets of electrostatic deflectors for varying beam dimensions, at least one of which is arranged between these aperture masks, and these electrostatic deflectors. 1. A charged beam optical lens barrel comprising: an electromagnetic deflector for optical axis correction arranged on the outside of the charged beam optical lens barrel.