JPS5824008B2 - Electron beam exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure apparatus that can accurately detect the dimensions and current density distribution of a shaped rectangular beam.

In an electron beam exposure apparatus used as a means for manufacturing a VLSI, an improvement in exposure speed is required in addition to improvement in accuracy.

In order to meet these conflicting demands, single-area exposure
Correct the beam cross section called , into a rectangle with a constant area,
A method of shooting this onto a sample is attracting attention.

FIG. 1 is a block diagram showing an example of area exposure, and numeral 1 indicates an electron gun.

The electron beam emitted from this electron gun is focused by a focusing lens 2 and projected onto a rectangular aperture plate 3 for beam shaping.

The beam passing through this rectangular aperture plate is reduced by a lens 4 and projected onto a sample 5 such as a semiconductor wafer.

A sample 5 is placed on a stage 6 and is moved by X by a driving means 7.

It can be moved in the Y direction.

A deflection system 8 is installed between the lens 4 and the sample 5, and determines the irradiation position of the shaped beam onto the sample.

A computer 9 controls the electron gun 1, lenses 2 and 4, stage driving means 7, and deflection system 8, and as a result, a desired pattern is drawn on the sample 5.

In such an apparatus, the shape and size of the shaped rectangular beam or the current density distribution are directly related to exposure accuracy and exposure unevenness, so it is necessary to accurately measure or detect them.

For this purpose, a detection means as shown in FIG. 2 has been proposed.

In the figure, reference numeral 10 denotes a thin wire or knife, which is placed in place of the sample 5 in FIG. 1 or very close to the sample.

The wire or knife is oriented in the direction of the sides of the rectangular beam, that is, in the X and/or Y directions.

An electron beam detector 11 such as a Faraday cage or a semiconductor detector is placed behind this wire or knife to detect the incident electron beam current.

The output from this detector is appropriately amplified and then sent to a second-order differentiation circuit 12 for differentiation, and this output is sent to a second-order differentiation circuit 13 and a display device 14.

The output signal of the second-order differentiator circuit is also sent to the display device 14.

In such a configuration, when the spot of the shaped beam is deflected and moved across the wire 10 using the deflection system 8 or another deflection system, the detector 11 will be shown as shown in FIG. A signal change as shown in is obtained.

The output signal of the detector is subjected to constant differentiation in a first-order differentiator circuit 12, resulting in a signal as shown in FIG.

This signal indicates the current density distribution of the electron beam.

The signal in Figure b is further differentiated in circuit 13, and the signal in Figure 3C
The signal will be as shown in .

The pulse interval of this signal indicates the size of the beam spot in the deflection direction.

Therefore, if the signals from the circuits 12 and 13 are displayed in waveform on the display device 14 and observed, the dimensions and current density distribution of the shaped beam can be detected.

However, with this type of equipment, the results obtained are averaged for both dimensions and current density distribution, so there is a drawback that some distribution unevenness and dimensional errors cannot be detected, making it difficult to perform high-precision exposure. becomes difficult to achieve.

The present invention has been made in view of these points, and will be described in detail below according to embodiments shown in the drawings.

FIG. 4 is a perspective view showing the main parts of the present invention, 10 and 11.
2 shows a wire (or knife) and an electron beam detector, respectively, as in FIG.

15 is a shielding plate having a slit 16 placed above the wire 10, and both linear edges 16a of the slit.

16b is made to coincide with the direction perpendicular to the wire 10, that is, the direction of deflection and movement of the beam spot 51 (S2).

In such a configuration, first, as shown in spot S1, the shaped beam is aligned with the straight edge 16a as shown in FIG. 5a.
, so that only the shaded portion is incident on the detector 11.

If the spot S1 is deflected and moved along the edge, a detector output as shown in FIG. 6a can be obtained.

Then, the output signal is converted by differentiating circuits 12 and 13 as shown in Fig. c.

At this time, the interval between both pulses in FIG. 0 indicates the length dl of the upper side of the beam spot S.

On the other hand, when the spot is moved upward (FIG. 5) as shown by S2 and deflected along the edge 16b, a signal as shown in FIG. Figure.

It is converted into a signal as shown in C.

The pulse interval in Figure 0 is the length d of the lower side of Figure 5.
2, and therefore, when compared with the pulse interval in FIG. 6C, the difference in length between the two opposing sides of the rectangular cross section can be accurately detected.

In addition, if the current density is non-uniform, Figures 6 and 7
Since the waveform shown in figure b changes into a sawtooth shape or a quadratic curve, an accurate distribution can be obtained.

FIG. 8 shows another embodiment in which a wire or knife 10 and a shielding plate 15 are integrated.

That is, a rectangular hole 17 is made in the shielding plate 15, and its straight edge 17 is
17° and 17° with respect to a and 17b are designed to have the function of a knife.

In this way, the structure can be simplified.

Although the above embodiment (Fig. 1) shows the case where the electron beam is shaped by a single aperture plate 3, two aperture plates, a lens, and a deflection system are used to shape and shape the cross section of the beam. The present invention can also be applied to a device whose size can be changed.

As detailed above, since the present invention detects only the portions near each side of the rectangular beam cross section, the cross-sectional dimensions and current density distribution can be detected extremely accurately, thus further improving exposure accuracy. It becomes possible to do so.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an electron beam exposure apparatus to which the present invention is applied, FIG. 2 is a diagram showing the main parts of a conventional apparatus, FIG. The figure is a perspective view of a main part showing one embodiment of the present invention, FIGS. 5 to 7 are diagrams for explaining the operation of FIG. 4, and FIG. 8 is a diagram showing another embodiment. 10... Wire or knife, 11...
...Electron beam detector, 15...Block plate, 16...
...Slit hole, 16a, 16b...Straight edge.

Claims (1)

[Scope of Claims] 1. An electron beam generation source, means for shaping the cross section of the electron beam emitted from the generation source into a rectangular shape, means for reducing and projecting the shaped electron beam onto a sample, and a sample. means for varying the electron beam projection position on the sample; a linear member or knife placed on the same plane as the sample or in the vicinity; and a shaped electron beam so as to cross the linear member or knife. In an apparatus comprising a means for deflecting and moving the electron beam, and a means for detecting a blocking state of the electron beam by the linear member or knife, the deflection movement of the electron beam is arranged on the same plane as or above the linear member or knife. What is claimed is: 1. An electron beam exposure apparatus characterized in that a shielding plate having a straight edge along a direction is provided so that information about an end of a rectangular cross-section electron beam can be detected. 2. The electron beam exposure apparatus according to claim 1, wherein the shielding plate has an elongated slit hole. 3. The electron beam exposure according to claim 1, wherein the shielding plate has a rectangular hole, and any edge is the linear edge, and an edge perpendicular thereto is provided with a knife function. Device.