JPH04155739A - Electron beam drawing device - Google Patents

Abstract

PURPOSE:To enable the high density of a blanker by deflecting a number of electron beams with a single deflector. CONSTITUTION:A control circuit 12 selectively performs blanking of an electron source in accordance with pattern data sent from a computer 14. When the blanking is off, blanking voltage with the polarity opposite to that of drawing voltage is applied and field strength is set less than strength necessary to produce electron beams, to stop producing electron beams. With control signals from the computer 14, a deflector 13 deflects electron beams to a desired position on a sample plane. In this configuration, the higher density electron source has a narrower deflecting area so that deflection aberration and distortion can be disregarded and only one deflector in minimum may be required. So, a simple and fine structure of blanker is allowed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electron beam lithography apparatus used for forming fine and highly accurate patterns in the manufacture of semiconductor integrated circuits, optical integrated circuits, and the like.

[Conventional technology]

The trend towards higher density and miniaturization of semiconductor integrated circuits is remarkable.
．． Advanced devices such as S1S GaAs devices in the 1 μm region and below are being developed. Electron beam lithography equipment, which can control ultrafine beams with high precision, is the optimal equipment for forming these ultrafine device patterns.

In order to achieve ultra-fine drawing performance, it is essential to reduce the beam diameter. On the other hand, the throughput of electron beam lithography equipment is
Mainly depends on beam current.

If the beam diameter is made smaller, the beam current cannot be avoided in principle. Even if a high-brightness electron source is used to increase the beam current, it becomes difficult to reduce the beam diameter due to the Coulomb effect. As described above, there is a problem in that it is difficult to achieve both fine drawing characteristics and high throughput. As a means to solve this problem, an electron beam drawing apparatus using multiple beams has been proposed.

FIG. 6 shows a schematic configuration diagram of a conventional multiple electron beam lithography apparatus as an example. 1 is an electron source, 2, 3, 6 is a converging lens, 4 is a one-dimensionally arranged shaped beam aperture, 5 is a similarly arranged blanking electrode, 7 is a blanking aperture that blocks the beam, 8 9 is an objective lens, and 9 is a deflector. The operation of the conventional example will be explained below.

The electron beam generated from the electron source 1 is passed through a converging lens 2.
3 to obtain a uniform intensity distribution on the aperture surface, the beam is irradiated onto a shaping beam aperture 4 and split into multiple electron beams. Furthermore, after each of the multiple electron beams is blanked by a blanking electrode 5, it is focused onto a sample by an objective lens 8 and deflected to a desired position by a deflector 9.

In the above example, there is an upper limit to the current value that can be emitted from - electron sources, so the total beam current value that is the sum of multiple beams cannot be increased, and there is a limit to the improvement of sloop/soto. There is a problem in that it is difficult to irradiate the aperture surface over a wide area with a uniform distribution.

Furthermore, since it is difficult to miniaturize the blanker, it is difficult to realize a two-dimensional high-density array and it is difficult to increase the number of electron beams. Most blankers currently in use consist of a bipolar electrostatic deflection plate that deflects the beam and a blanking aperture. To blank the beam, it is necessary to deflect the electron beam to a position greater than the sum of the distance from the optical axis to the edge of the aperture and the radius of the beam. In order to prevent beam leakage due to beam tailing, scattering, etc., it is necessary to allow for a sufficient margin of displacement beyond the minimum necessary displacement, so blankers cannot be arranged in a high density in the deflection direction.

[Problem to be solved by the invention]

The present invention relates to an electron beam lithography apparatus that generates multiple electron beams using two-dimensionally arranged field emission type electron sources to form extremely fine patterns. The shape of the electron beam is a point beam.

[Means to solve the problem]

The structure of the present invention is as shown below. That is, the present invention provides a two-dimensionally arranged field emission electron source, an electrostatic lens that generates, accelerates, and focuses multiple beams from the electron source, and a blanker that blanks the multiple beams on the same substrate. It has a structure as an electron beam lithography apparatus characterized by having a multi-electron beam generating device laminated on a plurality of electron beams and one deflector for deflecting the multi-electron beam. It is configured as an electron beam lithography device characterized by having a reduction lens for reducing the beam, or alternatively, it is characterized by having a reduction lens and a deflector for reducing the number of electron beams instead of a deflector. It has a structure as an electron beam lithography apparatus.

〔Example〕

FIG. 1 shows a schematic configuration diagram of an electron beam lithography apparatus as a first embodiment of the present invention. 11 is a multiple beam generator in which a two-dimensionally arranged field emission type electron source and an electrostatic lens for generating, stopping, accelerating, and focusing electron beams are stacked on the same substrate; 12 is a control for the multiple beam generator; circuit,
13 is a deflector that deflects multiple beams. 14 is a computer for inputting and outputting data such as system control, baton data, and drawing conditions; and 15 is a drawing sample. 16 is a stage. FIG. 2 shows a detailed diagram of the multiple beam generator.

(a) is a sectional view, and (b) is a plan view. 17 is a board;
18 is a field emission type electron source, 19 is a blanking electrode, 2
0 is an extraction electrode, and 21 is an acceleration electrode. 22 is a material that insulates each electrode. 23 is a wiring connected to the blanking electrode of each electron source. The extraction electrode 20 and the acceleration electrode 21 are wired in common to all the electron sources, but the blanking electrode 19 is wired for each electron source.

Normally, the radius of curvature of the field emission type electron source used in electron beam lithography equipment is around 0.5 μm, and the extraction voltage is 3 kV.
The above is 100V if the radius of curvature is further reduced.
It is possible to operate with low front and rear extraction voltages, that is, lower than the withstand voltage of the insulating film. This point is, for example, C, A, 5pindt, 1
．． Brodie, L., Humphrey, and E.
A paper by R. Westerberg et al., “Physi
cal properties of thin-fil
m field emission cathodes
with molybdenum cones”;J
, Appl, Phys, , vol, 47.
pp. 5248, 1976. Here, the insulating film is made of high dielectric strength material A I
! Os, Si.

N4.5if2 etc. The operation of this embodiment will be explained below.

A constant voltage v1 is applied to the extraction electrode 20 to generate a high electric field for the electron source to generate an electron beam. A constant voltage (2) is applied to the accelerating electrode 21 to accelerate the electron beam.

The applied voltages vI and V are set to appropriate values to operate as an electrostatic lens and focus the electron beam on the sample surface. For example, A.

“A Simple
e Scanning Electron Micro
scope″Rev, Sci, Instrum,
vol, 40. pp. 241.1969. Based on the button data sent from the computer 14, the control circuit 12 selects and blanks an electron source. The electric field strength E at the tip of the electron source caused by the extraction voltage V1 and the blanking voltage V is empirically expressed as E=AV, +BV, +C. Here, A, B, and C are constants, and when turning off blanking,
■,=0. When turning on blanking, a blanking voltage V having a polarity opposite to that of the extraction voltage is applied to reduce the electric field strength to less than the intensity required for generating an electron beam and stop generating the electron beam. In response to a control signal from the computer 14, the deflector 13 deflects the electron beam to a desired position on the sample surface. The drawing method of the present invention will be described.

Figure 3 shows the deflection area (1,
1), (1,2), (1,3), (1,4)...
...and drawing button examples A and B are shown. x of each deflection area
, the lengths of the sides in the y direction ΔX and Δy are equal to the arrangement pitch of the electron sources in each direction. Beam scanning may be either raster scanning or vector scanning. BUTTON A with raster scanning,
When drawing B, the lower left position Ps of the deflection area is used as the beam scanning start point, and the beam scanning is sequentially scanned to determine the beam scanning end point position P.
End the scan with e. Deflection area (1, 3), (1, 4
), (2, 3), and (2, 4), for each electron source having these regions, blanking is turned off at the start of scanning and turned on at the end of scanning. In areas (2,1) and (2,2), position P during scanning
Blanking is turned off for the electron source at position m and turned on at position Pn. After that, the button is drawn by repeatedly turning off and on at the border of the button. The electron sources in other areas remain blanked on.

In the case of vector scanning, deflection is performed separately for each deflection area group having the same deflection position data. In this example, the area (1
,3), (1,4), (2,3), (2,4) and area (2,1).

It is divided into two groups (2, 2) and deflected twice.

For the former group, the scan start position is set to Ps, and for the latter group, the scan start position is set to Pm, and only the inside of the slam area is scanned. In either case, blanking is turned off at the start of scanning and turned on at the end of scanning.

When trying to install a deflector for each electron beam,
The higher the degree of integration of an electron source, the larger the number of deflectors and the space occupied by the deflectors and control lines, and the more complex the control circuit becomes, making it difficult to actually realize it. On the other hand, in the present invention, since the deflection region can be narrowed as the density of the electron source becomes higher, deflection aberrations and deflection distortions can be ignored, and there is an advantage that the deflector can be configured with a minimum number of one deflector. Therefore, the deflection control circuit also has a simple configuration. In reality, it is very difficult to arrange electron sources to the same extent as the desired beam pitch. According to the present invention, even if the arrangement pitch of the electron sources is larger than the desired beam pitch, it is possible to perform baton writing at the desired beam pitch.

FIG. 4 shows a schematic configuration diagram of an electron beam lithography apparatus as a second embodiment of the present invention. The system configuration is the same as that of the first embodiment except that a reduction lens 24 is used instead of the deflector used in the system of the first embodiment. The operation of this embodiment will be explained below.

A constant voltage V1 is applied to the extraction electrode 20 to generate a high electric field for the electron source to generate an electron beam. A constant voltage V is applied to the accelerating electrode 21 to accelerate the electron beam.

Based on the baton data sent from the computer 14, the control circuit 12 selects and blanks an electron source to form an enlarged image of the drawn baton. The reduction lens 24 reduces the image so as to obtain a desired batten size and irradiates it onto the sample surface. Here, the minimum beam pitch is a value obtained by multiplying the arrangement pitch of the electron sources by the reduction rate.

In the case of the present invention, the operation of scanning the beam sequentially at an appropriate beam pitch in a conventional point beam type electron beam lithography apparatus can be performed with a single blanking operation.

FIG. 5 shows a schematic configuration diagram of an electron beam lithography apparatus as a third embodiment of the present invention. The system configuration is such that a deflector 13 is added to the system of the second embodiment described above. The operation of this embodiment will be explained below.

An electron beam is generated and accelerated in the same manner as in the second embodiment. Based on the button data sent from the computer 14, the control circuit 12 selects and blanks the electron source to form an enlarged image of the drawing pattern. The reduction lens 24 reduces the image at an appropriate reduction ratio and irradiates it onto the sample surface. In response to a control signal from the computer 11, the deflector 13 deflects the electron beam to a desired position on the sample surface. In this case, the lengths ΔX and Δy of the sides of the deflection region in the x+7 direction are equal to the value obtained by multiplying the arrangement pitch of the electron sources by the reduction ratio of the reduction lens. The drawing method is the same as in the first embodiment.

In this embodiment, a deflector 13 is installed to reduce the reduction ratio of the reduction lens. The reason for this is to avoid a multi-stage configuration of reduction lenses due to an increase in the reduction ratio, and to improve the narrow selection range of beam pitch values due to a fixed reduction ratio.

〔Effect of the invention〕

As explained above, according to the present invention, unlike the conventional beam deflection type blanker, the blanker structure can be simplified because it is a type that controls the electric field intensity applied to the electron source. Therefore, it is possible to miniaturize the blanker, and there is an advantage that it can be integrated with the electron source to achieve high density. The electron optical system also has a simpler configuration, and the lens barrel length is also much shorter than in the past. In addition, since a blanker is installed between the electron source and the extraction electrode, the distance between the electron source and the blanker is short.
It has the advantage of being able to perform blanking operation at low voltage. Furthermore, by miniaturizing and integrating the electron source, blanker, and electrostatic lens, it becomes possible to increase the number of electron beams and increase the density of the electron beams. This makes it possible to increase the total beam current and achieve high throughput.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an electron beam lithography apparatus as a first embodiment of the present invention, FIG. 2 is a schematic block diagram of a multiple beam generator of the present invention, and (a) is a cross-sectional view; (b) is a plan view. Further, FIG. 3 is a diagram showing the positional relationship between the deflection area and the writing pattern of the present invention, and FIG. 4 is a schematic configuration diagram of an electron beam writing apparatus as a second embodiment of the present invention.
FIG. 5 is a schematic block diagram of an electron beam lithography apparatus as a third embodiment of the present invention, and FIG. 6 is a schematic block diagram of a conventional multiple electron beam lithography apparatus as an example. 11... A multiple beam generator in which a two-dimensionally arranged thermal field emission type electron source and an electrostatic lens for generating, stopping, accelerating, and focusing the electron beam are laminated on the same substrate, 12...
- Control circuit for multiple beam generator, 13... Deflector for deflecting multiple electron beams, 14... System control,
Computer for inputting and outputting data such as button data and drawing conditions, 6... Board, 18... Field emission type electron source, 19.
... Blanking electrode, 20 ... Extraction electrode, 21.
...Acceleration electrode, 22...Material for insulating each electrode, 23
...Wiring to the blanking electrode, 24...Reducing lens Schematic diagram of the configuration of the electron beam lithography system Fig. 1 Schematic diagram of the configuration of the electron beam lithography system Figure 4 Schematic diagram of the configuration of the electron beam lithography system Figure 5: Schematic diagram of a conventional multiple electron beam lithography system as an example Figure 6:

Claims (3)

[Claims] (1) A two-dimensionally arranged field emission electron source, an electrostatic lens that generates, accelerates, and focuses multiple beams from the electron source, and a blanker that blanks the multiple beams are laminated on the same substrate. An electron beam lithography apparatus comprising a multiple electron beam generator and one deflector for deflecting the multiple electron beams. (2) The electron beam lithography apparatus according to claim 1, further comprising a reduction lens for reducing the number of electron beams in place of the deflector. (3) Claim 1 characterized in that it has a reduction lens and a deflector for reducing the number of electron beams instead of the deflector.
The described electron beam lithography apparatus.