JPS6244407B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure method, and in particular, it is possible to prevent dimensional instability that is likely to occur when the current value of the rectangular electron beam is changed when a rectangular electron beam is applied. The present invention attempts to provide an electron beam exposure method.

Conventionally, as one of the electron beam (beam) exposure methods, when drawing a pattern on a substrate coated with an electron beam sensitive material (electron beam resist), a fine diameter electron beam is used to deflect and scan the pattern. It has been proposed to draw a desired shape pattern by painting and sliding one point at a time.

However, such a method has the drawback that when the desired pattern area becomes large, the number of scanning points increases and the drawing time becomes too long.

For this reason, a method has recently been proposed in which a pattern is drawn using an electron beam having a relatively large rectangular cross section.

Such a rectangular electron beam (beam) exposure apparatus generally has a configuration as shown in FIG. That is, in the figure, an electron beam generated from an electron gun 1 is shaped by a first shaping slit 6 having an electron beam opening through an irradiation lens 5, and a second shaping slit 6 having an electron beam opening by a beam shaping lens 8. The light is projected onto the shaping slit 9. At this time, by changing the voltage or current applied to the beam shaping deflectors 7, 7', the electron beam shaped by the first shaping slit 6 can be placed at an arbitrary position on the second shaping slit 9. , only the beam that has passed through the electron beam apertures of both shaping slits 6 and 9 is irradiated onto the substrate 13 to be processed by the reduction lens 10, the projection lens 11, and the positioning deflector 12.

In such an electron beam exposure apparatus, when the voltage of the beam axis adjustment coil 3 is changed in order to correct fluctuations in the beam current value, lines 21 and 2 are shown in FIG. 2a.
As shown by 2, the electron beam changes minutely.

The beam shaped by the electron beam aperture of the first shaping slit 6 changes its position from 23 to 2 due to a slight change in the electron beam axis.
4, resulting in a change in the cross-sectional shape of the electron beam 25 shaped at the opening of the second shaping slit 9.

In FIG. 1, 2 is a grid, 3 is a beam axis adjustment coil, and 4 is a blanking deflector.

The present invention aims to prevent dimensional instability caused by changes or fluctuations in the current value or area of the electron beam in such rectangular electron beam exposure.

Therefore, according to the present invention, in an electron beam exposure method using an electron beam having a rectangular cross section as an exposure electron beam, the area-to-current value of the rectangular electron beam is and a second means for detecting the dimension of the rectangular electron beam on the irradiated surface, and the first means detects the area versus current value. There is provided an electron beam exposure method characterized in that after detecting the relationship and adjusting it to a desired relationship, the second means detects the dimension and adjusts it to the desired dimension.

Next, the present invention will be described in detail with reference to embodiments.

That is, as shown in FIG. 3, a Faraday gauge 33 is disposed outside an exposure field 32 of the electron beam 31 onto the substrate 13 to be processed, and the electron beam 31 is placed inside the Faraday gauge 33. is incident. The electron beam 31 can be deflected into the Faraday gauge 33 by applying a voltage to the positioning deflector 12.

At this time, if the area of the electron beam incident on the Faraday gauge 33 is gradually widened, for example, from a ribbon shape to a step shape as shown in FIG. The observed current value increases stepwise.

Therefore, in the exposure electron beam, if the area versus current value of the electron beam remains constant at the specified value,
As shown in Figure b, it is observed that the current value also increases in proportion to the size of the electron beam. However, even if the area of the exposing electron beam changes, a situation may occur in which the current value is not proportional to the change in the dimensions of the electron beam, as shown in FIG.

In the figures b and c, the horizontal axis S represents the area of the rectangular electron beam, and the vertical axis I represents the beam current value.
In such a case, the voltage applied to the beam axis adjustment coil 3 of the electron beam exposure apparatus is adjusted so that the area versus current value of the electron beam becomes a specified value.
At this time, if the voltage of the beam axis adjustment coil 3 is changed, the axis of the electron beam may change slightly as described above, and the area and dimensions of the electron beam may change.

Therefore, according to the present invention, in such a case, the area and dimensions of the electron beam are measured and corrected.

That is, as shown in FIG. 5, for example, a thin wire 51 is disposed on a plane substantially equal to the plane on which the substrate to be processed 13 is disposed, and a rectangular electron beam 52 is directed to the thin wire 51 by the positioning deflector 12. Deflection scans in a direction perpendicular to the direction in which the beam extends.

As a result, the current measuring element 53 disposed below the thin wire 51 measures a current that is shielded only in the portion of the thin wire 51. This current is converted into a current-voltage conversion circuit 5
4 to obtain a voltage waveform 54'.

The bottom 54'' of the voltage waveform 54' is the part shielded by the thin line 51, and represents the width of the thin line 51. Next, the voltage waveform 54' is differentiated by a first-order differentiation circuit 55 to obtain a first-order differential waveform 55'. The protrusion 55'' of the first-order differential waveform 55' forms a current density distribution in a direction perpendicular to the thin line 51 of the electron beam 52.
Furthermore, the first-order differential waveform 55' is converted into a second-order differential circuit 56.
A second-order differential waveform 56' is obtained. If the point at which the second-order differential waveform 56' exceeds the threshold voltage 57 is 56'', 56, then the distance between the points 56'' and 56 is the length of the electron beam 52 in the direction perpendicular to the thin line 51.

Therefore, the interval between points 56'', 56 whose value exceeds the threshold voltage 57 in the second-order differential waveform 56',
That is, if the length of one side of the rectangular electron beam 52 differs from a specified value, the beam shaping deflector 7 of the electron beam exposure apparatus and The output voltage or current of the deflection circuit 7' is adjusted to modify the length of one side of the rectangular electron beam.

In addition, according to the method shown in FIG. 5 described above, since there is only one thin wire, only the length of the rectangular electron beam in one direction (one side) is measured, so as shown in FIG. By preparing two thin wires and arranging them orthogonally, it is possible to measure the lengths of a rectangular electron beam in both directions (two orthogonal sides).

Alternatively, instead of the orthogonal thin wires, a member 71 having orthogonal knife edge portions as shown in FIG. 7 may be used to similarly measure the lengths of the rectangular electron beam in both directions (two orthogonal sides). .

In actual exposure processing, the lengths of the rectangular electron beam in both directions (two orthogonal sides) are measured using this method, and if these lengths differ from the specified values, the beam is adjusted as described above. Adjusting the output voltage or current of the deflection circuit of the shaping deflectors 7 and 7',
The rectangular electron beam is modified to a specified size.

The structure of the electron beam exposure method according to the present invention described above is shown in a flowchart of FIG.

According to the present invention, in an electron beam exposure method that uses a rectangular electron beam, the current value of the rectangular electron beam can be kept constant, and the rectangular electron beam that is likely to occur when changing the current value can be It is possible to correct the instability of the dimensions of the electron beam and perform more stable electron beam exposure processing.

The electron beam exposure processing according to the present invention described above can improve the exposure processing efficiency based on the time required for the electron beam exposure processing according to the present invention by utilizing the exposure free time when performing the desired exposure processing on the substrate to be processed. Further, the next desired exposure process on the substrate to be processed can be performed accurately without causing any deterioration.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the configuration of a rectangular electron beam exposure apparatus, FIG. 2 is a partial cross-sectional view and a plan view showing variations in the electron beam in such an electron beam exposure apparatus, and FIGS. A partial sectional view and a curve diagram of an electron beam exposure apparatus showing the configuration of a means for detecting the relationship between the area and current value of an electron beam according to the present invention, and FIG. 5 shows the configuration of a means for detecting the dimensions of an electron beam according to the present invention. FIGS. 6 and 7 are plan views showing other embodiments of the electron beam size detection means shown in FIG. 5, and FIG. 1 is a flowchart showing the configuration of an electron beam exposure method according to the present invention. 1 to 7, 3...beam axis adjustment coil, 6...first shaping slit, 9...
Second shaping slit, 12... positioning deflector,
13... Substrate to be processed, 33... Faraday gauge, 51... Thin wire, 53... Current measuring element, 71...
...A member having orthogonal knife edges.

Claims (1)

[Claims] 1. In an electron beam exposure method using an electron beam having a rectangular cross-sectional shape as an exposure electron beam, a first step is carried out to detect the relationship between the area of the rectangular electron beam and the current value near the irradiated surface of the rectangular electron beam.
Further, a second means for detecting the dimensions of the rectangular electron beam is disposed on the irradiated surface, and the first means detects the relationship between the area and the current value. An electron beam exposure method characterized in that after adjusting to a desired relationship, the second means detects the dimension and adjusts to the desired dimension.