JPH10312954A - Electron beam aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the dimensional and positional accuracy of an electron beam from degrading without sacrifice of throughput by arranging a blanking deflector closer to the electron beam source side than a shaping aperture and arranging a blanking aperture closer to the sample stage side than the shaping aperture. SOLUTION: An optically superposed image of first and second shaping apertures 104, 107 is demagnified through a demagnification lens 108 and an objective lens 110 before being focused onto a sample 111. When the position of an electron beam 102 is shifted on the sample 111, the electron beam 102 is deflected by a blanking deflector 120 such that the unnecessary part on the sample is not exposed. The electron beam 102 is also cut by a blanking aperture 121 so that it does not reach the surface of the sample. More specifically, the blanking deflector 120 is arranged closer to the electron gun 101 side than the first shaping aperture 104 and the blanking aperture 121 is arranged closer to the sample 111 side than the second shaping aperture 107.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electron beam exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, an electron beam exposure apparatus has been used as a means for drawing a desired fine pattern on a sample surface such as a semiconductor sample. Among them, an electron beam exposure apparatus (hereinafter, referred to as a VSB exposure apparatus) having a variable beam size has a feature that the throughput is extremely high.

In a VSB exposure apparatus, two shaping apertures for shaping an electron beam generated from an electron beam source into a desired shape, and an optical overlap between the two shaping apertures provided between the two shaping apertures are set to a desired shape. The shape of the beam is determined by the shaping deflector. A projection lens is provided between the two shaping apertures, the first shaping aperture serving as an object surface, and an image plane formed on the second shaping aperture. A reduction lens and an objective lens are provided on the sample side of the second shaping aperture in order to form an electron beam formed by the two shaping apertures on the sample. In addition, a main deflector is provided in the objective lens for selecting a beam position on the sample, and blanks the beam so that unnecessary exposure is not performed on the sample when moving the beam position on the sample.

In the VSB exposure apparatus, it is necessary to adjust the beam size so that the set beam size matches the actual beam size. For adjusting the beam size, for example, as shown in JP-A-63-23756, after adjusting each side of the first shaping aperture and the second shaping aperture so as to be parallel to the reference coordinates, The beam current is measured with a Faraday cup or the like while changing the beam size, and the aperture is adjusted so that the increase amount of the beam current becomes linear with respect to the beam size. Then, the offset value of the beam current amount when the set beam dimension on the straight line is zero is obtained. Then, by correcting the beam size based on the offset value, an actual beam size according to the set beam size can be obtained.

[0005] Further, when drawing the formed electron beam on a sample, it is necessary to blank the beam so as not to expose unnecessary portions on the sample. Where V
The problem that occurs when the SB exposure apparatus turns blanking on / off will be described.

The blanking needs to be deflected at a high speed, and is constituted by an electrostatic deflector and a blanking aperture. As a blanking method, a blanking deflector and a blanking aperture are provided on the electron gun side from the shaping deflector to perform blanking, and a blanking deflector and a blanking aperture are provided on the sample side from the shaping deflector. There is a method of performing blanking.

FIG. 4 shows an example in which a blanking deflector (blanking electrode) 120 and a blanking aperture 121 are provided closer to the electron gun 101 than the first shaping aperture 104.

[0008] The trajectory of the electron beam 102 changes as shown by a dotted line by blanking ON / OFF. The electron beam 102 is cut by the blanking aperture 121, and does not reach the sample 111 side from the blanking aperture 121 during blanking.
The amount of electron beam incident on the first shaping aperture 104 and the second shaping aperture 107 changes due to blanking ON / OFF, and the amount of reflected electrons and secondary electrons generated by the first shaping aperture 104 and the second shaping aperture 107. Changes greatly. Due to this change, the forming deflector 105
The state of charge-up on the surface, near the first forming aperture 104 and the second forming aperture 107 changes. As a result, the trajectory of the electron beam 102 changes and the first
The degree of optical overlap between the shaping aperture 104 and the second shaping aperture 107 changes, and the size of the electron beam 102 changes. Further, the amount of the electron beam incident on the first shaping aperture 104 and the second shaping aperture 107 also changes. Since the temperature of the first shaping aperture 104 and the temperature of the second shaping aperture 107 change when the input energy changes, the shapes of the first shaping aperture 104 and the second shaping aperture 107 change due to thermal expansion.
As a result, the amount of the electron beam 102 passing through the first shaping aperture 104 and the second shaping aperture 107 changes, and the size of the electron beam changes. As a result, the pattern dimensional accuracy on the surface of the sample 111 deteriorates.

The effect of a change in beam size on a writing pattern becomes more pronounced as the pattern becomes finer. For example, when the beam size change amount is 0.01 μm (on the sample surface), 2% (0.0%
1 μm / 0.5 μm), but 10% (0.01 μm / 0.1 μm) in the drawing pattern of the 0.1 μm rule.
m).

FIG. 5 shows an example in which a blanking deflector (blanking electrode) 120 and a blanking aperture 121 are provided on the sample 111 side from the second shaping aperture 107.

The trajectory of the electron beam 102 is blanking O
N / OFF changes as shown by the dotted line. The electron beam 102 is deflected by a blanking deflector 120 provided below the second shaping aperture 107 and cut by a blanking aperture 121. In this method, the amount of electron beam incident on the first shaping aperture 104 and the second shaping aperture 107 does not change due to blanking ON / OFF. Therefore, the forming deflector 10
5. There is no dimensional change of the electron beam due to a change in the charge state near the first shaping aperture 104 and the second shaping aperture 107. Further, the first shaping aperture 104 and the second shaping aperture 107 do not change in shape due to a temperature change. Therefore, the electron beam 10 passing through the first shaping aperture 104 and the second shaping aperture 107
The amount of 2 does not change and the size of the electron beam does not change. As described above, this method does not deteriorate the shape accuracy of the drawing pattern.

However, due to a change in the state of charge-up on the surface of the blanking deflector 120 provided below the second shaping aperture 107, the first shaping aperture 104 and the second shaping aperture
Since the trajectory of the formed electron beam 102 changes due to the optical overlap with the forming aperture 107, the sample 1
The position accuracy of the electron beam on 11 is degraded. The charge-up state of the electrode surface of the electrostatic deflector changes depending on the voltage applied to the deflector. Blanking ON
Since the applied voltage of the blanking deflector 120 changes greatly due to / OFF, the trajectory of the electron beam changes due to a change in the surface state of the blanking deflector 120, and the sample 1
The positional accuracy of the beam on the eleventh surface is degraded.

In order to eliminate such deterioration in beam size accuracy and beam position accuracy, the beam size is measured and corrected at regular time intervals, or the beam position is measured at regular time intervals in the middle of a desired drawing pattern. Is measured, and the position correction is performed by adjusting the deflection amount of the beam by the amount of the position drift, thereby preventing a decrease in the drawing accuracy. However, in this case, it is necessary to perform dummy drawing or the like until the charge-up state change or the temperature change becomes stable, which lowers the drawing throughput.

[0014]

As described above, when the blanking deflector (blanking electrode) and the blanking aperture are provided closer to the electron gun than the first shaping aperture, the dimensional accuracy of the beam deteriorates. There is a problem that. On the other hand, when the blanking deflector (blanking electrode) and the blanking aperture are provided on the sample side with respect to the second shaping aperture, there is a problem that the beam position accuracy deteriorates. Further, when correcting the beam size or correcting the beam position in order to reduce these problems, it takes time to perform dummy drawing or the like, which causes a problem that the drawing throughput is reduced.

An object of the present invention is to provide an electron beam exposure apparatus capable of preventing deterioration of dimensional accuracy and positional accuracy of an electron beam without lowering throughput.

[0016]

According to the present invention, there is provided an electron beam exposure apparatus comprising: an electron beam source; a sample table on which a sample to be irradiated with an electron beam generated from the electron beam source is mounted; A plurality of (for example, two) shaping apertures for shaping the generated electron beam into a desired shape, and a shaping deflection provided between the plurality of shaping apertures to shape an optical overlap of the shaping apertures into a desired shape. Device, projecting means for projecting the electron beam passing through the shaping aperture on the electron beam source side onto the shaping aperture on the sample stage side, and mounting the electron beam shaped by the plurality of shaping apertures on the sample stage. Image forming means for forming an image on the sample, and a brassier arranged closer to the electron beam source than the shaping aperture closest to the electron beam source. It has a King deflector, a blanking aperture positioned on the sample stage side of the shaping aperture of most the sample stage side.

Further, the blanking deflector may be constituted by a plurality of blanking electrodes, and a deflection sensitivity adjusting means for adjusting the deflection sensitivity of the plurality of blanking electrodes may be further provided.

By arranging the blanking deflector and the blanking aperture as described above, it is possible to eliminate a change in the irradiation amount of the electron beam to the shaping aperture due to blanking ON / OFF. The blanking deflector is composed of a plurality of blanking electrodes, and the electrode deflection ratio is adjusted so that the electron beam does not move on the shaping aperture. / OFF can be prevented from changing. For these reasons, it is possible to prevent the dimensional accuracy of the electron beam from deteriorating on the sample surface.

The trajectory of the electron beam changes due to the change in the state of charge on the surface of the blanking deflector.
Since the blanking deflector is arranged closer to the electron beam source than the shaping aperture on the electron beam source side, it is possible to prevent deterioration of the position accuracy of the electron beam on the sample surface.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an electron beam exposure apparatus according to the embodiment of the present invention. Electron gun 10
The current density of the electron beam 102 emitted from 1 is adjusted by the condenser lens 103, and uniformly illuminates the first shaping aperture 104. This first forming aperture 10
The image of No. 4 is formed on the second shaping aperture 107 by the projection lens 106. The degree of optical overlap between the two apertures is controlled by the shaping deflector 105. A shaping deflection amplifier 116 is connected to the shaping deflector 105, and data from a pattern data memory 117 is decoded by a pattern data decoder 115 and input to the shaping deflection amplifier 116.

The image formed by the optical overlap between the first shaping aperture 104 and the second shaping aperture 107 is reduced by the reduction lens 108 and the objective lens 110 and then the sample 111
Imaged on top. The position of the electron beam 102 on the sample 111 is controlled by the objective main deflector 109 via the pattern data decoder 115 and the objective main deflector amplifier 119.

The sample 111 is mounted on a movable stage 114 together with a Faraday cup 113 and a mark stand 112 for measuring an electron beam size. By moving the movable stage 114, the sample 111, the Faraday cup 113 or the mark stand 112 can be selected. it can.

When the position of the electron beam 102 on the sample 111 is moved, the electron beam 102 is deflected by a blanking deflector (blanking electrode) 120 so that unnecessary portions on the sample are not exposed. The electron beam is cut by the blanking aperture 121 so that the electron beam does not reach the sample surface. The deflection voltage to the blanking deflector 120 is controlled by the pattern data decoder 114 and the blanking amplifier 122.

As described above, in the present embodiment, the blanking deflector (blanking electrode) 120 is provided closer to the electron gun 101 than the first shaping aperture 104, and the blanking aperture 121 is connected to the second shaping aperture 10.
7 is provided on the sample 111 side.

At the time of blanking deflection, the electron beam 102
Follows a trajectory as indicated by the dotted line. Since the electron beam 102 deflected by the upper blanking deflector 120 is returned by the lower blanking deflector 120, the electron beam 102 on the first shaping aperture 104 and the second shaping aperture 107 at the time of blanking ON / OFF. No change occurs in the current amount of the incident beam and the irradiation position. Therefore, there is no change in the amount of reflected electrons and secondary electrons generated in the first shaping aperture 104 and the second shaping aperture 107, and the charge deflector 105, the charge shaping in the vicinity of the first shaping aperture 104 and the second shaping aperture 107 are not changed. The state does not change. Therefore, the trajectory of the electron beam 102 does not change, and the degree of optical overlap between the first shaping aperture 104 and the second shaping aperture 107 does not change, so that the beam size does not change. In addition, the first forming aperture 104
In addition, the amount of the electron beam incident on the second shaping aperture 107 is also constant when blanking is ON / OFF. Therefore, the temperature of the aperture does not change, and the shape of the aperture does not change due to thermal expansion, so that the electron beam dimension does not change. Due to these, pattern dimensional accuracy on the surface of the sample 111 does not deteriorate.

On the other hand, a change in the state of charge-up on the surface of the blanking deflector 120 causes a change in the trajectory of the electron beam 102. That is, the blanking deflector 1
Since the reference numeral 20 is disposed closer to the electron gun 101 than the first shaping aperture 104, a change in the charged state of the surface of the blanking deflector 120 causes a change in the trajectory of the electron beam. Moves. However, FIGS. 2A and 2B
As shown in FIG. 5, even if the irradiation area of the electron beam 102 to the first shaping aperture 104 moves, the irradiation area of the electron beam 102 to the first shaping aperture 104 becomes the first shaping aperture.
Since it is sufficiently large with respect to the diameter of the forming aperture 104, the first
The optical overlap between the shaping aperture 104 and the second shaping aperture 107 does not cause a change in the shape of the electron beam 102 formed.

Since the trajectory of the electron beam 102 changes due to a change in the state of charge-up on the surface of the blanking deflector 120 disposed on the electron gun 101 side from the first forming aperture 104, the sample of the formed electron beam 102 There is no effect on the position accuracy on the 111 plane.

FIG. 3A shows a measurement result when the electron beam current in the electron optical system of FIG. 1 (this embodiment) is measured by the Faraday cup 113 on the movable stage 114. As can be seen from this figure, there is almost no change in the electron beam current, indicating that the electron beam size on the sample 111 is stable.

FIG. 3B shows a measurement result when the electron beam current in the electron optical system of FIG. 5 (prior art) is measured by the Faraday cup 113 on the movable stage 114. As can be seen from this figure, the electron beam current has changed significantly, and the electron beam size on the sample 111 has changed significantly.

Although the blanking aperture 121 is located on the crossover image of the electron beam 102 in the example shown in FIG. 1, it is not always necessary to provide the blanking aperture 121 at this position.

In the example shown in FIG. 1, two shaping apertures are provided and a shaping deflector and a projection lens are arranged between them. However, three or more shaping apertures are provided, and as in the case of two shaping apertures. A shaping deflector and a projection lens may be arranged between the shaping apertures. In addition, the present invention can be variously modified and implemented without departing from the spirit thereof.

[0032]

According to the electron beam exposure apparatus of the present invention, it is possible to prevent the dimensional accuracy and position accuracy of the electron beam from deteriorating due to blanking ON / OFF.
Therefore, by improving the precision, the precision of the apparatus can be improved, the precision of the drawing pattern and the precision of the drawing position can be improved, and a great effect can be exhibited in the semiconductor manufacturing field and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a change in the trajectory of an electron beam.

FIG. 3 is a diagram showing a change in a current value of an electron beam.

FIG. 4 is a diagram showing an example of a conventional technique.

FIG. 5 is a diagram showing another example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Electron gun (electron beam source) 102 ... Electron beam 104 ... 1st shaping aperture 105 ... Shaping deflector 106 ... Projection lens (projection means) 107 ... 2nd shaping aperture 108 ... Reduction lens (imaging means) 110 ... Objective Lens (imaging means) 111: sample 114: movable stage (sample stage) 120: blanking deflector 121: blanking aperture

Claims (4)

[Claims] 1. An electron beam source, a sample stage on which a sample to be irradiated with an electron beam generated from the electron beam source is mounted, and a plurality of electron beam sources formed from the electron beam source into a desired shape. A shaping aperture, a shaping deflector provided between the shaping apertures and shaping the optical overlap of the shaping apertures into a desired shape, and an electron beam passing through the shaping aperture on the electron beam source side. Projection means for projecting onto the shaping aperture on the sample stage side; imaging means for imaging an electron beam formed by the plurality of shaping apertures on a sample mounted on the sample stage; A blanking deflector disposed closer to the electron beam source than the shaping aperture on the sample side; An electron beam exposure apparatus, comprising: a blanking aperture disposed on a platform. 2. The electron beam exposure apparatus according to claim 1, wherein the number of the plurality of shaping apertures is two. 3. An electron beam exposure apparatus according to claim 1, wherein said blanking deflector comprises a plurality of blanking electrodes. 4. An electron beam exposure apparatus according to claim 3, further comprising a deflection sensitivity adjusting means for adjusting the deflection sensitivity of said plurality of blanking electrodes.