JPS60244025A - Electron beam drawing device - Google Patents

Abstract

PURPOSE:To enable to attain high speed electron beam drawing with high precision by a method wherein a beam current is changed over corresponding to a figure, and the figure is drawn according to a large beam and a large pitch excluding the case when a figure of minutely high precision is to be drawn according to a small beam and a small pitch. CONSTITUTION:When a beam is small, electron lenses 3, 4 are used. Moreover, when the beam is made large, electron lenses 2, 4 are used to make the system to a magnification system. Namely, the beam can be changed only by selecting either of the lenses 2, 3 to be used, and the change of the beam current becomes to the square of magnification. When the electron beam current is made large, the scanning pitch is made rough, and the scanning speed is made the same, because the number of beam projecting times is small, and the scanning speed is the same when the figure is drawn with a large beam, drawing time can be curtailed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electron beam drawing apparatus for drawing ultra-fine figures using an electron beam.

[Background of the invention]

2. Description of the Related Art Electron beam lithography, in which an arbitrary figure is drawn by focusing and deflecting an electron beam and irradiating it onto a substrate, is used in the manufacture of semiconductor integrated circuit devices and the like. When using this to draw ultrafine figures of 0.2 μm or smaller, the beam aperture angle is limited to a small value due to the need to reduce blur caused by aberrations, so the current value is small and it takes a long time to draw. This results in drawbacks that require time.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron beam lithography apparatus that eliminates the above-mentioned drawbacks and enables high-accuracy and high-speed electron beam lithography.

[Summary of the invention]

In order to achieve the above object, in the present invention, not all of the figures to be drawn on semiconductor integrated devices or the like are minute and require high precision, and loose precision is often sufficient for many parts. Therefore, the beam current is switched according to the shape,
Fine and high precision ones.

It is constructed so that writing is performed with a small beam at a small pitch, and other writing is performed with a large beam at a large pitch, and the overall writing time can be greatly shortened.

[Embodiments of the invention]

An embodiment of the present invention will be described below. FIG. 1 shows an example of switching the beam current. 1 is an electron source, which is used for the purpose of drawing ultra-fine figures.

It is preferable to use a field emission cathode with a small radiation source diameter and high brightness. 2, 3, and 4 are electronic lenses.

5 is a substrate to be drawn. In the figure (a), the beam is small, and only child lenses 3 and 4 are used to reduce the source and project it onto the substrate. Figure (b) shows a state in which the beam is enlarged, and the electron lenses 2 and 4 are used as an enlargement system. In this case, by setting the electronic lenses 2 and 3 so that the position of the object point of the electronic lens 4 is the same, the usage conditions of the electronic lens 4 can be made the same. Namely.

The beam can be changed simply by selecting which lens 2 or 3 to use. In this case, the change in beam current is the square of the 1 magnification. Therefore, if the magnification ratio is set to 1:2, the beam current changes by 1:4.

FIG. 2 shows another embodiment in which the beam current is varied. In this embodiment, the aperture 6.6'i, which limits the aperture angle of the projection beam, placed in the final stage electron lens 4 is replaced, as shown in FIGS.

This changes the beam current. In this case, the beam current changes as the square of the aperture diameter ratio. In this case, the conditions for the electron lens before and after changing the aperture are as follows:
Everything should remain the same.

When increasing the electron beam current, it is necessary to increase the scanning speed if the pitch of the deflection scanning for writing remains the same, but when a field emission cathode is used as the electron source, the required speed is increased due to the large current density. This becomes very large, causing problems in the response of the deflection electric circuit. Therefore, it is preferable to configure the scanning pitch to be coarse and to equalize the scanning speed.

High-precision drawing devices usually use digital deflection. Therefore, by selecting the scanning pitch to be an integral multiple of the minimum deflection unit (L8B) and configuring the beam current ratio to be the square thereof, the scanning speeds can be made equal. Figure 3 shows examples of figures drawn using the method described above. Figure (a) is a figure drawn with a small beam at a fine scanning pitch, and figure (b) is a figure drawn with a large beam at a rough scanning pitch. It is a drawn figure. As can be seen from the figure, when drawing is performed with a large beam, the number of beam irradiations is small (reciprocal of the beam current ratio) and the scanning speed remains the same, so the drawing time is shortened.

The above example shows two-stage switching, but the number of stages can easily be increased to three or more depending on the required precision of the figure.
In the electronic lens switching shown in the figure.

By appropriately excitation of lenses 2 and 3, it is possible to achieve any magnification between those obtained with only lens 2 and only lens 3.

〔Effect of the invention〕

As described above, according to the present invention, a figure with low precision can be drawn at high speed, so that the overall drawing time can be significantly shortened. For example, the drawing area ratio is 20% for high-precision figures.
When writing in two stages with a beam current ratio of 1:4, compared to the conventional method of writing the entire area with a small beam,
You can draw in 0% of the time.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of the present invention, FIG. 2 is a diagram for explaining another embodiment of the present invention, and FIG. 3 is a diagram for explaining an example of a drawing figure according to the present invention. ...electron source, 2
, 3.4...electronic lens, 5...substrate. 6.6I...Aperture. Continuing from page 10 Inventor Akira Fujinami Ono, Atsugi City0 Inventor Kazumi Iwatate Ono, Atsugi City [Inside the facility = 145-

Claims (1)

[Claims] 1. A means for switching the child beam diameter or beam current value in a plurality of stages, so that the writing scanning pitch is made approximately proportional to the beam diameter ratio or the square root ratio of the beam current value in accordance with the switching. What is claimed is: 1. An electron beam lithography apparatus characterized in that the electron beam lithography apparatus is configured to switch to 2. The electron beam lithography apparatus according to claim 1, wherein the electron source for emitting the electron beam is constituted by a field emission cathode. 3. The electron beam lithography apparatus according to claims 1 and 2, wherein the ratio of the beam diameters or the ratio of the square root of the beam current values is set to be approximately an integer ratio. 4. By changing the excitation of the two electron lenses and varying the optical magnification while maintaining the object point position of the final lens,
An electron beam lithography apparatus according to any of claims 1, 2, and 3, characterized in that the beam diameter is configured to be switched. 5. Equipped with multiple apertures to limit the beam aperture angle. Claim 1, characterized in that the beam current value is switched by selecting one of them using an electric signal. The electron beam lithography apparatus according to items 2 and 3.