JPH02237106A - Charged particle beam lithography equipment - Google Patents

Abstract

PURPOSE:To prevent a displacement of a beam axis by a changeover operation of a beam diameter or to prevent a thermal strain of a beam diaphragm and to change over the beam diameter at high speed and with high accuracy by providing a variable beam-limiting diaphragm whose opening diameter is concentric and variable. CONSTITUTION:A variable beam-limiting diaphragm 7 is connected to a tip part 10A of an arm 10 protruding from a diaphragm-blade operation ring 9; the diaphragm-blade operation ring 9 is turned by a driving rotary sheet 11 which moves the arm 10; an opening diameter 7A is formed in the central part 12B by a plurality of diaphragm blades 12. Accordingly, the opening diameter 7A can be changed arbitrarily; a beam diameter and a beam current can be controlled. Since the opening diameter 7A can be changed in a concentric circle shape by using a beam axis X as its center, a displacement of the beam axis X can be neglected; in addition, since the opening diameter 7A is always irradiated with an electron beam 6, it is thermally stable and a change in the opening diameter 7A by a thermal strain can be made extremely small. Thereby, it is possible to suppress an influence by the displacement of the beam axis or by the thermal strain; a high-speed changeover operation can be realized; a high-speed and a high-accuracy lithographic operation can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a charged beam drawing device that draws fine figures at high speed using a charged beam. (Prior art) Charged beam lithography systems such as electron or ion beams have been used in fields that require microfabrication such as semiconductor integrated circuits and optical components.
As the beam becomes thinner, it is necessary to make the beam diameter of the charged beam finer, but the resulting beam current becomes smaller, leading to an increase in time of 100 hours. For this reason, a device has been devised that draws the button by switching the beam diameter between large and small. In other words, a large bang is a large beam diameter with a large beam current,
A small bang is a method of drawing with a small beam diameter. By doing this, it is possible to draw figures with a mixture of large and small patterns at high speed. Conventionally, the method shown in Figure 3 was used to switch the beam diameter. 1 is an electron gun, 2 and 3 are electron lenses, 4
is a sample, and 5 is a beam limiting diaphragm having multiple aperture diameters 5A and 5B. Figure 4 is a plan view of the beam limiting diaphragm. An electron beam 6 emitted from an electron gun 1 is focused by electron lenses 2 and 3 and formed into an image on a sample 4. Generally, the electron lens 3 is called an objective lens, and a beam limiting diaphragm 5 is inserted therein to limit the aperture angle of the electron beam. The beam current obtained on the sample 4 is limited by the beam limiting diaphragm 5. Now, if the half-angle of opening of the electron beam 6 seen from the sample 4 is α, the beam current obtained is l−πβαg. Here, 1 is the beam current and β is the brightness. α is determined by the aperture diameter 5A or 5B of the beam limiting diaphragm 5 and the distance between the surface of the beam limiting diaphragm 5 and the surface of the sample 4. Therefore, by changing the aperture diameter 5A or 5B of the beam limiting diaphragm 5, α
can be changed, and the amount of beam current can also be controlled. On the other hand, the beam diameter obtained on the surface of sample 4 is α from several mrad to several tens of meters.
When changing within the range of rad, it increases as α increases. Therefore, by appropriately changing the aperture diameter 5A or 5B of the beam limiting diaphragm 5, it is possible to change the beam diameter and beam current under the same lens conditions.

(Problem to be Solved by the Invention) In order to switch the beam diameter as described above, as shown in FIG. The aperture diameter 5A or 5B was changed by stepping the limiting diaphragm 5. However, in such a method, accurate positioning is difficult due to backflash during step feed, and the beam axis X becomes deviated, causing an increase in astigmatism. Also, the diameter of the beam limiting diaphragm 5 is changed from 5A to 5A.
Due to the local thermal strain that occurs when changing to B (and vice versa), the aperture diameter 5A or 5B of the beam limiting diaphragm 5 changes,
There was a problem in which the beam current or beam diameter fluctuated over several minutes. For this reason, every time the aperture diameters 5A and 5B of the beam limiting diaphragm 5 are changed, waiting time is required, and in some cases, the beam axis X of the electron beam 6 needs to be adjusted, which increases wasted time. It was difficult to achieve high-speed drawing, which is the main purpose of In order to eliminate these drawbacks, the present invention has a structure in which the diameter of the beam limiting diaphragm can be varied concentrically, thereby preventing deviation of the beam axis or thermal distortion of the beam diaphragm caused by switching the beam diameter, and achieving high-speed and The purpose of this project is to provide a charged beam lithography system that enables highly accurate beam diameter switching. (Means for Solving the Problems) In order to achieve the above object, the present invention provides a charged beam lithography apparatus having means for switching the beam diameter or beam current value in multiple stages, in which the aperture diameter is concentrically variable as the switching means. The gist of this paper is a charged beam lithography system characterized by a variable beam limiting aperture. (Function) With the above configuration, the present invention can change the beam diameter without changing the position of the aperture diameter, and can eliminate beam axis deviation or thermal distortion of the beam diaphragm.

(Example) Examples of the present invention will be described below with reference to the drawings. Note that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the spirit of the present invention.

FIG. 1 shows an embodiment of the present invention, in which 1 is an electron gun, 2 and 3 are electron lenses, 4 is a sample, 6 is an electron beam, and 7 is a variable beam limiting aperture. The electron beam 6 emitted from the electron gun 1 is focused by electron lenses 2 and 3 and reaches the sample 4, but the beam diameter or beam current at that time is controlled by a variable beam limiting aperture that can be moved symmetrically around the beam axis X. 7 can be freely varied. As shown in FIG. 2, the variable beam limiting diaphragm 7 includes an aperture blade operating ring 9 that fits into the inner peripheral edge of the outer annular plate 8 and can rotate freely, and a aperture blade operating ring 9 that rotates the aperture blade operating ring 9. The tip 1 of the arm 10 protruding from the aperture blade operating ring 9
0A to move the arm 10, and an outer end protrusion 1 on the aperture blade operating ring 9.
2A is rotatably supported by a bottle, and when the aperture blade operating ring 9 rotates, the center portions 12 on the inner end sides of each other are rotated.
It consists of several to ten or more diaphragm blades l2 that form an aperture diameter 7A (see Figure 1) at B. The driving rotary plate 11 is connected to a motor l3, and the external control plate 1'
An arbitrary angle rotation is possible using the n device (not shown). In the figure, when the arm 10 is rotated from position B to position A, the aperture blades 12 concentrically widen the aperture diameter 7A (see FIG. 1).

In this way, the arbitrary aperture diameter 7A can be changed, thereby making it possible to control the beam diameter and beam current.

As shown in FIG. 1, the aperture diameter 7A of the variable beam limiting diaphragm 7
can be changed in a concentric manner around the beam axis It is thermally stable, and changes in the aperture diameter 7A due to thermal strain can be made extremely small.

Therefore, the desired beam diameter and beam current can be obtained immediately after switching. The time required for this switching is approximately several milliseconds at most, which is significantly faster than conventional methods. Although an electron beam was used as the charged beam in this example, the present invention is not limited to this; a similar device configuration is also possible using an ion beam. Further, according to the gist of the present invention, it is clear that any aperture having a structure in which the aperture diameter is concentrically variable can be used in addition to the variable beam limiting aperture used in this embodiment.

(Effects of the Invention) As explained above, the present invention provides a charged beam lithography apparatus having means for switching the beam diameter or beam current value in multiple steps, in which the aperture diameter is concentrically variable. By having a beam limiting diaphragm,
When switching the beam diameter or beam current, it is possible to suppress the effects of beam axis misalignment or thermal distortion, making it possible to switch quickly and achieve high-speed, high-precision writing.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a device showing an embodiment of the present invention, FIG. 2 is a perspective view of a variable beam limiting diaphragm, FIG. 3 is an explanatory diagram of a conventional device, and FIG. 4 is a plan view of the beam limiting diaphragm. ．． 1... Electron guns 2, 3... Electron lens 4... Sample 5... Beam limiting diaphragm 6 with multiple aperture diameters...
・Electron beam 7...Variable beam limiting diaphragm Outer annular plate diaphragm blade actuation Ring arm drive Rotating plate diaphragm blade motor @1 Figure 2

Claims (1)

[Claims] A charged beam lithography apparatus having a means for switching a beam diameter or a beam current value in multiple stages, characterized in that the switching means includes a variable beam limiting aperture whose aperture diameter is concentrically variable.