JPH039581B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charged particle beam device in which a multipole charged particle lens is arranged on the image plane of the charged particle lens.

Recently, so-called charged particle beam lithography systems, which draw patterns on materials using electron beams or ion beams, have been in the spotlight as a means of manufacturing (super)LSI devices. Taking an electron beam lithography system as an example, this system includes one that draws a pattern by focusing a spot-shaped beam on a predetermined position on a material (spot-type electron beam lithography system), and a beam path. A method in which a pattern is drawn by placing a mask plate with square or rectangular holes on top of the material and focusing a beam whose cross section is square or rectangular at a predetermined position on the material (fixed area type). (electron beam lithography system), a plurality of mask plates as described above are placed on the beam path, and the cross-sectional shape and size of the beam passing through the final mask plate are controlled by controlling the deflector placed between each mask plate. There is a system (variable area type electron beam lithography system) in which a pattern is drawn by imaging a beam that has passed through the final mask plate at a predetermined position on the material.

An object of the present invention is to provide a charged particle beam in which the cross-sectional shape of the charged beam irradiated onto a target can be arbitrarily varied without being restricted by the shape of the hole in the mask in the above-mentioned apparatus.
Therefore, the present invention provides a charged particle beam generating means, a mask plate disposed on the charged particle beam path from the generating means and having a hole for shaping the beam cross section, and a first mask plate for forming an image of the hole by the charged particle beam. A charged particle beam device comprising: a charged particle lens; and a second charged particle lens for forming an image of the hole on a target by the charged particle beam formed by the first charged particle lens. , a multipole charged particle lens disposed on the imaging plane of the hole image formed by the first lens; an electric signal supplied to each pole of the multipole charged particle lens is controlled to form the image on the target; It is characterized by comprising means for changing the shape of the hole image.

FIG. 1 is a schematic diagram of a fixed area type electron beam lithography apparatus shown as an embodiment of the present invention. 1 in the diagram
is an electron gun, and the electron beam generated from the electron gun is transmitted through a square opening 2H formed in a mask plate 2M.
The cross section is shaped into a square. 3 is an electron lens for forming a beam image of the aperture surface of the mask plate 2M, and 4 is an electrostatic quadrupole lens arranged around the beam image 5 (that is, the image plane of the electron lens 3). . A voltage is applied to the lens as shown in FIG. That is, the electrostatic electrode plates 4a, 4b
For example, a negative voltage from the potentiometer 6 is applied via an amplifier 7 with a gain of A, and the output of the amplifier 7 is applied to the electrostatic electrode plates 4c and 4d via an amplifier 8 with a gain of (-1). applied. Reference numeral 9 denotes an electron lens for forming the beam image 5 onto the material 10. Reference numeral 11 denotes a deflection lens that controls the imaging position of the beam image on the material 10 based on a position command signal from a central processing unit (not shown).

In such an apparatus, the electron beam emitted from the electron gun 1 is shaped into a square cross section by the opening of the mask plate 2M. The beam exiting the aperture is imaged by an electron lens 3 approximately at the center of an electrostatic quadrupole lens 4. The square beam image is shaped into a rectangular shape by the quadrupole lens as follows.

The quadrupole lens creates a field as shown in FIG. When a beam with a square cross section attempts to pass through the center of such a field, the trajectory of the beam changes as it receives a force in the direction of the electric lines of force as shown by the arrows. This force is equal to zero at the center of the field, that is, on the optical axis, and acts with a strength roughly proportional to the distance from the optical axis. That is, as shown in FIG. 3, the square beam image (aerial image) receives an attractive force from the electrode plates 4c and 4d, and at the same time receives a repulsive force from the electrode plates 4a and 4b. Therefore, the image passing through the aperture surface of the electron lens 9 does not have a square shape such as a', b', c', d', but a rectangular shape such as ABCD, and is focused on the material 10 by the electron lens. The image that is imaged,
It is not a square shape like a″, b″, c″, d″, but A′,
They will be rectangular shapes like B', C', and D'. The length and width ratio of this rectangle can be controlled by the strength of the voltage applied to the electrostatic electrode plate of the quadrupole lens 4. Further, by applying a positive voltage to the electrostatic electrode plates 4a and 4b and a negative voltage to the electrostatic electrode plates 4c and 4d, the vertical and horizontal directions of the shaped image are reversed.

Now, the very important point here is that the quadrupole lens 4 is placed on the image plane of the electron lens 3. With this arrangement, as shown in FIG. 4, the beam emitted from one point in the aerial image abcd of the electron lens 3 is bent by the same strength as the beam proceeding in the X direction and the beam proceeding in the Y direction. When they arrive, the beams coming from either direction intersect at one point. That is,
No pockets due to astigmatism occur. Furthermore, 9', 1
0' are the aperture surface and material surface of the electronic lens 9, respectively.

In the above example, a square beam is shaped into a rectangular beam without causing blurring due to astigmatism.
Rotate by 45 degrees, and quadrupole lenses 4a, 4b, 4c,
If a beam image as shown by the solid line in FIG. 5 is created at the center of 4d, a diamond-shaped image as shown by the broken line will be formed on the material 10. Alternatively, two sets of quadrupole lenses may be provided, shifted by 45 degrees, and the field formed by these lenses may be electrically rotated appropriately so that a diamond-shaped image forms a parallelogram-shaped image on the material. . or,
In the above embodiments, an electrostatic quadrupole lens was used as an example, but an electromagnetic quadrupole lens may also be used. Further, the quadrupole lens may be stacked with the octupole lens to improve the precision of shaping. Also, the present invention is not limited to quadrupoles. For example, it is also possible to shape a spot beam (round beam) into a triangular beam using a hexapole lens.

According to the present invention, the cross-sectional shape of the beam imaged at the center of the multipole lens is shaped into a triangle, rectangle, rhombus, or parallelogram by the lens action of the multipole lens, and astigmatism is caused on the material. It is possible to reshape images without causing blurring. In addition, shape changes that occur in other lens systems can be corrected using a multipole lens without causing blurring due to astigmatism.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fixed area electron beam lithography system showing an embodiment of the present invention, FIGS. 2 to 4 are diagrams used to assist in explaining the operation of the system, and FIG. The figure shows the shape of the beam image formed on the material when the beam image formed at the center of the quadrupole lens is rotated by 45 degrees with respect to the embodiment shown in FIG. 1... Electron gun, 3... Electron lens, 4... Electrostatic quadrupole lens, 5... Beam image, 9... Electron lens, 10... Material.

Claims (1)

[Claims] 1. Charged particle beam generating means, a mask plate disposed on the charged particle beam path from the generating means and having a hole for shaping the beam cross section, and a first charged particle lens for forming an image of the hole by the charged particle beam. , a charged particle beam device comprising a second charged particle lens for forming an image of the hole by the charged particle beam imaged by the first charged particle lens on a target; a multipole charged particle lens disposed on the imaging plane of the hole image formed by the lens; controlling electric signals supplied to each pole of the multipole charged particle lens to form an image of the hole on the target; Charged particle beam device with means for changing shape.