JPS59198721A - Electron beam drawing device - Google Patents

Abstract

PURPOSE:To enlarge both of luminance and emittance of an electron gun, and to contrive to enhance the throughput and precision of the process of an electron beam drawing device by a method wherein after an electron beam is drawn out from the electron gun by the high accelerating voltage V1 once, the beam thereof is decelerated up to the prescribed accelerating voltage V2. CONSTITUTION:When voltages are set to V1=100KV, V2=50kV by regulating electric power sources 210, 211, an electron beam is drawn out according to the voltage of 100kV between a cathode and an anode from an electron gun 201, and the beam thereof forms a first crossover at the position P1. The beam is decelerated continuously up to 50kV according to a decelerating lens 207, and a second crossover is formed at the position P2. Therefore, both of luminance and emittance of the electron gun 201 can be increased, and an aperture mask 227 can be illuminated uniformly by high current density. Accordingly, the molding beam of uniform and high current density can be formed on a sample surface 225, and as a result, enhancement of a throughput can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an electron beam lithography apparatus using a shaped beam.

[Technical background of the invention and its problems]

In recent years, various electron beam lithography apparatuses have been used to form fine patterns on samples such as semiconductor wafers 1 and mask substrates. This device focuses and deflects an electron beam emitted from an electron gun and irradiates it onto a sample to draw a desired pattern on the resist on the sample.
It is most excellent for micron or Zabumicron 9 NJB patterns. Processing submicron patterns requires the formation of a resist pattern with a vertical cross section, and generally a large amount of beam irradiation is required to form such a pattern.

Therefore, an electron gun with brightness as low as possible is required.

On the other hand, in electron beam lithography technology, increasing the number of images drawn per unit time (throughput) has become an important issue, and for this purpose, variable shaped beam type electron beams, which perform lithography while changing the dimensions of the electron beam, have recently been developed. A drawing device has been developed. In this device, it is impossible to form a uniformly shaped beam, and in order to form a uniformly shaped beam, it is necessary to uniformly irradiate the beam through an aperture mask for beam shaping.

Fig. 1 is a schematic diagram for explaining the conditions for forming a uniform shaped beam. The beam is shown focused on the sample surface. Further, dg is the diameter of the crossover 103, α is the divergence angle of the electron beam, and d is the diameter of the electron beam on the sample surface.

αt is the focal angle of the beam by the final stage lens. The condition for forming a uniform shaped beam is α2・dg≧αj
-d It is known that (1). Here, the product of the above angle and the diameter (
α□・dg, αvid) are called emittances, and it is necessary to increase the emittances in order to increase the throughput.

In this way, the variable dimension beam type electron beam lithography system
Both the brightness and emittance of the electron gun are required to be high. However, there is a contradiction in that increasing the luminance reduces the emittance, and increasing the emittance decreases the luminance, making it impossible to satisfy the above requirements.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron beam lithography apparatus in which both the brightness and emittance of an electron gun can be sufficiently increased, and the throughput and processing accuracy can be improved.

[Summary of the invention]

The gist of the present invention is to decelerate a 7E beam extracted from an electron gun at an acceleration voltage 1 to an acceleration voltage V lower than the voltage v1.

In FIG. 1, the potential of the space where the crossover 101 is formed is set to v8. If the space where the sample surface exists is ■, then β・π(α2・dg)2■1=β・π(dt−d)”V
,...(2) is known to hold true. Here, β is β-J. /(π・k−T) ・・・・・・
...+31, where Jc is the current density of the cathode, T is the temperature of the cathode, and is Boltzmann's constant.

Also, the brightness β is B=β・V pa...
...(4).

On the other hand, in a 'ladder beam' lithography system using a shaped beam, the electron gun is used under space charge limiting conditions in order to uniformly irradiate the aperture mask for beam shaping.At this time, the cathode current density Jc and the acceleration ' Between city pressure ■1, J c = J co *v'・' ・
・・・・・・・・・・・・(5) There is a relationship. However, Jco is a constant that does not depend on the 7a pressure. Therefore, the magneton beam is extracted with an accelerating voltage of -1, and 1' of V2 is
When a beam is formed at a position of ;, the emittance E and brightness B in space are as follows. For example, (V, =v2-5oi<
v) + (V, = 100 KV, V2-50 KV
). In other words, once the height is 17N'
I'I8i pressure ■ After drawing out the beam at 1, the specified voltage V
The emittance E and brightness B are better when the speed is reduced to 2.
Together they become big papers.

The present invention focuses on such points, and includes an electron beam drawing apparatus that irradiates a sample with an electron beam emitted from an electron gun and draws a desired pattern on the sample button. The extracted beam is applied at an accelerating voltage V2 (V, <V,) on the cryoreading side of the blanking deflector, beam shaping aperture, mask, etc.
It was designed to reduce the speed to .

〔Effect of the invention〕

According to the present invention, after an electron beam is extracted from the electron gun at a high acceleration voltage v1, this beam is decelerated to a predetermined acceleration voltage 2, so that the brightness B and emittance E of the '1E child gun are reduced. Both can be made larger. Therefore, it is possible to achieve the same throughput and processing load, and it is extremely effective in manufacturing semiconductor devices. Also,
Since the beam is decelerated on the electron gun side rather than the blanking deflector and the beam shaping aperture mask, the beam accelerated at high voltage may damage the mask, and the deflector FF-11 may be used to plan the beam. - It is possible to prevent inconveniences such as difficulty in kinging.

[Embodiments of the invention]

FIG. 2 is a schematic configuration diagram showing an electron beam lithography apparatus of a shapeable beam type according to an embodiment of the present invention. 201 in the diagram
is an electron gun, and this electron gun 201 has a large tip diameter L.
The JLB6 cathode is formed from a 2θ2° Wehnelt electrode 203 and an anode (beam extraction electrode) 204.

The electron beam emitted from the electron gun 201 is decelerated by a deceleration lens 207 consisting of a high voltage side electrode 205 and a ground side electrode (beam deceleration electrode) 206. Still, the beam is aligned by an alignment coil 208 placed between the anode 204 and the lens 207. Here, a bias resistor 209 is connected between the cathode 202 and the Wehnelt electrode 203, and a high voltage '4 Sources 210 and 211 are connected, respectively. The cathode 20 is powered by these power supplies 210 and 211.
A voltage vl is applied between the cathode 202 and the anode 204, and a voltage 2 (v2<vl) is applied from Q between the cathode 202 and the earth-side electrode 206. This results in
'An electron beam is extracted from the electron gun 20 at an accelerating voltage V8, and this beam has an accelerating voltage V.

The speed will be reduced to .

The electron beam decelerated to the acceleration voltage 2 is passed through the condenser lens 221. The light is focused and controlled by a projector lens 222, a reduction lens 223, and an objective lens 224, and is irradiated onto a sample surface 225. Here, the earth electric value 20
A blanking deflector 226 is disposed between the blanking lens 6 and the condenser lens 221, and the beam is subjected to ON-OF control by this deflector 226. In addition, an aperture mask 227 for beam shaping is provided between the lenses 221 and 222 ('': 1.
A beam-shaping aperture mask 228 and a beam-shaping deflector 229 are arranged between the beam shapes 23 and 23 . Then, by deflecting the beam by the deflector 229, the masks 227 and 221 are
The overlapping state of the beams 1 can be changed, thereby changing the shape and dimensions of the beam.

In the figure, 230 is a beam scanning deflector for scanning the beam on the sample, and 23) is a computer.

232 is an interface, 233. . . . , 237 indicate power supplies, respectively.

In a device configured in this way, if the power supply 210° 211 is set to vl-100 [KV], ■, = 50 (KV), the electron gun 201 will output 100 [KV] between the cathode and the anode. An electron beam is extracted by the voltage of
This beam forms the first cross-ohno at position P. The upstream beam is then decelerated by the deceleration lens 207.
0 (KV), forming a second crossover at position P2'. Therefore, electron gun 2
Both the brightness and emittance of 01 can be increased,
The aperture mask 227 can be uniformly illuminated with current density. Therefore, it becomes possible to create a shaped beam with a uniform high current density on the sample surface 225, and as a result, the throughput can be increased.

In addition, in this device, the beam is decelerated above the blanking deflector 226 and the beam shaping aperture mask 227, 228, so the mask 227 may be damaged by the beam accelerated at high pressure. There are no inconveniences such as blanking or difficulty in blanking. moreover,
Even if the optical axis shifts due to acceleration/deceleration, this shift can be easily corrected by the alignment coil 208.

Note that the present invention is not limited to the embodiments described above. For example, as means for decelerating the electron beam,
It is not necessarily necessary to use a deceleration lens, and only a beam deceleration electrode may be used. In this case, the optical axis does not shift, and the alignment coil becomes unnecessary. Furthermore, it goes without saying that the present invention is applicable not only to the variable shaped beam type but also to various types of electron beam lithography apparatuses that use shaped beams. Furthermore, the acceleration voltage V11v! is V,
) V2, which may be determined as appropriate according to the specifications. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the conditions for forming a uniformly shaped beam, and FIG. 2 is a schematic diagram showing a variable shaped beam type electron beam lithography apparatus according to an embodiment of the present invention. 201--Electron gun, 2 (72--LaBa cathode, 203--Wehnelt electrode, 204--anode, 205--High voltage side %i pole, 206--Earth side electrode (for beam deceleration) electrode), 207... deceleration lens,
208... Axis alignment coil, 210, 211... Power supply for cylinder, 22, ~, 224... Lens, 226... Deflector for blanking, 227, 228... Aperture mask for beam shaping, 229 ...The beam is also ≦ shape deflector.

Claims (1)

[Scope of Claims] (1) In an electron beam drawing apparatus that irradiates an electron beam emitted from an electron gun onto a sample and draws a desired pattern on the sample, blanking controls the electron beam. 3. a beam deflector, a beam shaping aperture mask for shaping the beam, means for extracting the electron beam from the electron gun with an accelerating voltage V, and a means for extracting the extracted beam from the electron beam deflector and mask. An electron beam lithography apparatus comprising means for decelerating the electron beam to an acceleration voltage V2 (V2 < Vl) on the electron gun side. 2) As a means for extracting the beam at an accelerating voltage V, an acceleration pressure (1) is applied to the anode of the electron gun, and as a means for decelerating the beam to an accelerating voltage V2, a beam deceleration is applied to the beam emitting side of the electron gun. An electron beam lithography system according to claim 1, characterized in that a magnetic pole is provided and an accelerating voltage v2 is applied to this electrode.
. (3) The electron beam lithography apparatus according to claim 1, further comprising an alignment coil provided between the electron gun and the beam deceleration pole.