JP3139441B2 - Electron beam drawing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam lithography apparatus, and more particularly to a batch exposure type electron beam lithography apparatus using an aperture of a complicated figure.

[0002]

2. Description of the Related Art Conventionally, an aperture of a complicated figure has been irradiated with an electron beam by using a plurality of electromagnetic deflectors as described by Sakamoto et al. In Japanese Patent Application Laid-Open No. 2-122518.

[0003]

However, in the above method, since electromagnetic deflection is used, time is required for deflection. Therefore, when drawing is performed using various figures, the deflection is rate-limiting and the throughput is reduced. Also, Japanese Unexamined Patent Publication No.
No. 69131 discloses a combination of one electromagnetic deflector and one electrostatic deflector, but does not mention anything about matching the deflection center and high-speed deflection, and the electron trajectory is complicated.

[0004]

An electrostatic deflector for shaping deflection and an electrostatic deflector for selecting figures are provided. Further, for example, a divided electrostatic deflector structure shown in FIG.

[0005]

The deflector for variable shaping is required to operate at a low voltage because of high speed operation, and the deflection amount cannot be increased too much. However, if a high-voltage electrostatic deflector is used, it is possible to obtain a deflection amount equivalent to that of an electromagnetic deflector at a speed higher than that of an electromagnetic deflector, at the latest, even more slowly than a deflector for variable shaping. In addition, if the deflection centers of the two coincide, the deflection is substantially performed by one deflector, and the control of the electron trajectory is simplified. Since the electrostatic deflectors cannot be used in an overlapping manner, as shown in FIG. 1, one of the deflectors (in this case, the deflector 2 for figure selection) is divided into two parts so that the deflection centers are matched. Just do it. In the deflector divided into two, the off-axis of the electrons on the subsequent deflection plate becomes large. In order to reduce the deflection distortion caused by this, it is effective to make the interval between the deflection plates of the deflector divided into two larger than the interval between the deflection plates of the central deflector.

[0006]

FIG. 2 is a block diagram showing an embodiment of the present invention incorporated in an electron beam drawing apparatus. FIG. 3 shows a configuration diagram of the aperture. As is clear from FIG. 3, in the case of the figure selection, the image of the first aperture is simply used as illumination of the second aperture. Therefore, the image distortion of the first aperture is not a problem as long as the second aperture does not protrude from the image of the first aperture. On the other hand, in the case of shaping deflection, the image distortion of the first aperture has an effect on a figure to be drawn directly. Therefore, the deflection of the first aperture image needs to be performed with higher precision in the shaping deflection. As described above, since the deflection aberration tends to be larger in the two-divided deflector, in this embodiment, the deflection for forming deflection is performed by the central deflector. Therefore, the shaping deflection is performed by the deflector 6 and the deflection of the figure selection is performed by the deflector 7. The molding deflection operates at a voltage of 20 V, and the deflection time is as fast as 50 ns. On the other hand, a voltage of 50 V is required in the graphic selection deflection because the deflection angle is large, and the deflection time is 1 μs. The center of deflection of both is aligned with the crossover image 9 of the upper transfer lens, and the crossover position does not move due to deflection. In this apparatus, since the objective aperture 11 is arranged on the crossover image plane of the reduction lens 10, it is necessary to match the crossover with the center of deflection in order to keep the current density on the wafer constant. From this point, it is understood that it is necessary to match the deflection centers of both deflectors. When the figure is selected, the axis of the electron beam is returned to the original position by the return deflector 12 on the crossover image plane of the lower transfer lens. As a result, the trajectory change due to the figure selection is limited between the figure selection deflector and the return deflector, and a decrease in drawing accuracy such as distortion and astigmatism due to the trajectory change can be minimized.
Thereafter, the electron beam is imaged on the wafer by the reduction lens and the objective lens.

When such a deflecting plate is used, the size of the deflector is inevitably larger than in the case of only variable shaping. For this reason, the outer deflector (the figure selecting deflector in this embodiment) enters the magnetic field of the transfer lens. In the deflection in the presence of a magnetic field, the center of the deflector does not always become the center of deflection because the trajectory of electrons rotates. With this effect, 2
It becomes difficult to align the deflection centers of the two deflectors. In order to avoid this effect, it is necessary to cancel the effect with two transfer lenses. Therefore, the excitation of the upper and lower lenses is reversed, and the electric field of the deflector and the lens magnetic field are vertically symmetric. A similar effect is manifested in the return deflector. In this embodiment, the return deflector is also divided into two and the upper and lower deflection directions are changed to align the crossover image with the deflection center. Furthermore, in order to correct the astigmatism generated by the figure selection, the return deflector is an 8-pole electrostatic deflector so that the astigmatism can be corrected at the same time.

[0008] As a result of arranging the conventional electromagnetic deflector so that the center of deflection is the same as the center of deflection, the deflection time is 10 µs, which is about ten times longer than the electrostatic deflection. As a result of drawing an SRAM having a size of 0.5 μm, a throughput of 10 wafers / hour was obtained in the case of electrostatic deflection, whereas a throughput of 7 wafers / hour was obtained in the case of electromagnetic deflection.

[0009]

According to the present invention, a figure can be selected at a high speed in an electron beam lithography system of the batch exposure system. Accordingly, the speed of the drawing process of a semiconductor circuit or a photo reticle can be increased, which contributes to an improvement in productivity.

[Brief description of the drawings]

FIG. 1 is a structural diagram of an electrostatic deflector.

FIG. 2 is a configuration diagram of an electron beam drawing apparatus.

FIG. 3 is an aperture configuration diagram.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Deflector for shaping | deflection, 2 ... Deflector for figure selection, 3 ... Electron gun, 4 ... 1st aperture, 5 ... Transfer lens, 6 ... Deflection plate for shaping | deflection, 7 ... Deflector for figure selection, 8 ... 2nd aperture, 9 ... crossover image, 10 ... reduction lens,
Reference numeral 11: Object diaphragm, 12: Back deflector, 13: Objective lens, 14: Object deflector, 15: Wafer, 16: Stage, 17: Aperture for shaping / deflection, 18: Graphic aperture, 19: Origin of the first aperture image , 20... A first aperture image when a figure is selected, 21.

Continuation of the front page (56) References JP-A-4-100203 (JP, A) JP-A-2-122518 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21 / 027 G03F 7/20 504 G03F 7/20 521 H01J 37/147 H01J 37/305

Claims (5)

(57) [Claims] An electron source, a first aperture plate having an opening for making an electron beam from the electron source into a predetermined shape, and a first aperture plate provided downstream of the first aperture plate. A transfer lens, a second aperture plate having the plurality of aperture figures, and a deflector for forming deflection and figure selection between the first aperture plate and the second aperture plate; A first figure selecting deflector such that the deflection centers of the figure selecting deflector and the shaping deflector are aligned, a shaping deflector below the first figure selecting deflector; An electron beam lithography apparatus, comprising a second deflector for selecting a figure and a second transfer lens in which the excitation of the first transfer lens is reversed below the deflector for deflection. 2. The deflector for forming and deflecting the figure so that the crossover image of the first transfer lens coincides with the deflection center of the deflector for forming and deflecting the figure. 2. An arrangement according to claim 1, wherein
An electron beam lithography apparatus according to claim 1. 3. The electron beam lithography apparatus according to claim 2, wherein said shaping deflector is arranged inside said figure selecting deflector. Wherein said shaping deflecting deflector the electron beam drawing apparatus according to claim 1 to 3, wherein features that there in the electrostatic deflector. 5. A electron source, a first aperture plate having an opening for the electron beam into a predetermined shape from the electron source, the first disposed downstream of said first aperture plate Using a transfer lens, a second transfer lens provided downstream of the first transfer lens, and a second aperture plate having the plurality of aperture figures, wherein the first aperture plate and the second aperture A step of transforming the electron beam into a rectangular beam by the first aperture plate at the time of selecting a graphic with a shaping deflector between the plate and the first aperture plate; A first deflecting step of deflecting by the selecting deflector; and a second deflecting step of deflecting by the second figure selecting deflector so that the deflection center of the shaping deflector coincides.
Deflection step, excitation of the first transfer lens and the second
Driving the excitation of the transfer lens in the opposite direction.