JP2003203857A - Electron beam exposure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron beam exposure system, equipped with an electron optics system with a short-length optical lens tube and with little geometrical aberrations. <P>SOLUTION: In an electron beam exposure system, a solenoid lens of a projecting optical system comprises a first projecting lens 15 on the side of a reticle, and a second projection lens 19 on the side of a sensitive substrate, both lenses have an excitation coil respectively, both coils being similar shapes of 4:1 with an excitation current ratio of 1:-1 in equal ampere turns. A distance L1 from the reticle 10 to a sensitive substrate 23 is 400 mm, a distance L2 up to the center of the first projecting lens 15 is 160 mm, and a distance L3 up to the center of the second projection lens 19 is 360 mm. Further, the first projection lens 15 has an inner diameter D1 of 42 mm with a gap G1 of 160 mm, and the second projection lens 19 has an inside diameter D2 of 10.5 mm with a gap G2 of 40 mm. Furthermore, a deflector 16 has prescribed optical axis direction, scale factor, current ratio, and angle of deflected magnetic field formed in a plane perpendicular to the optical axis. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam exposure apparatus for exposing and transferring a pattern formed on a reticle onto a sensitive substrate such as a wafer using an electron beam. In particular, the present invention relates to an electron beam exposure apparatus having a relatively short projection optical system barrel length and a large-area batch transfer area.

[0002]

2. Description of the Related Art Exposure using an electron beam, which is a type of charged particle beam, has a drawback of high accuracy but low throughput, and various technical developments have been made to solve the drawback. In recent years, as an electron beam transfer exposure method aiming at dramatically high throughput, an electron beam is irradiated onto a partial area of a reticle that has a circuit pattern for the entire semiconductor chip, and the image of the pattern in the irradiation area is double-stepped. An electron beam projection exposure apparatus for reducing and transferring the image onto a wafer by using the projection lens is being developed. In this type of device, it is usually impossible to obtain a wide field of view with low aberration so that the electron beam flux can be collectively irradiated onto the entire range of the reticle to transfer the pattern at one time.
Therefore, the field of view of the optical system is divided into a large number of small regions, the patterns are sequentially transferred onto the wafer while changing the conditions of the electron beam optical system for each small region, and the image of each small region on the wafer (Dimension example 2).
It has been proposed that the entire circuit pattern be transferred by connecting and arranging (50 μm square) (divided transfer method, for example, see US Pat. No. 5,260,151).

As one of the techniques for reducing the aberration of the projection optical system of such an electron beam projection exposure apparatus, there is a symmetrical magnetic doublet type lens. This lens has a two-stage projection lens shape (pole pole Bohr diameter, lens gap) of the projection optical system with a similar point symmetry with the entrance pupil as the center, the magnetism of both lenses is reversed, and the excitation coil ampere of both lenses is reversed. It has the same turn (J. Vac. Sci. Technol., Vol.12, No.
6, Nov. Dec. 1975). With this optical arrangement, all θ-direction aberrations, distortions, and chromatic aberrations of magnification are canceled and become zero.

Similarly, as an aberration reducing technique, it is also known that the off-axis aberration can be reduced by using an axial movement type electromagnetic lens such as MOL or VAL (MOL (Movi
ng Objective Lens, H. Ohiwa et al., Electron Commun. Jp
n. 54-B, 44 (1971)), VAL (Variable Axis Lens,
HC Pfeiffer et al., Apl. Phys. Lett. Vol. 39, No. 9.1
Nov. 1981)). Further, a technique of providing a plurality of deflectors in the projection optical system to remove the third-order geometrical optical aberration is also known (T. Hosokawa, Optik, 56, No. 1 (1980) 21-30).

FIG. 4 is a side sectional view schematically showing an example of a projection optical system to which these aberration reducing techniques are applied. Reticle (reticle) 101 shown at the top of the figure
Receives electron beam illumination from above by an illumination optical system (not shown). Below the reticle 101, in order, a first projection lens 102, a contrast aperture 105, a second projection lens 103, and a wafer (sensitive substrate) 104 are arranged along an optical axis (a dot-dash line in the center).

The first projection lens 102 has a U-shaped rotationally symmetric magnetic pole 102b having an inward cross section, and a coil 102c arranged on the inner circumference thereof. The upper magnetic pole 102a and the lower magnetic pole 102d protrude toward the optical axis, and a magnetic field is formed in the first projection lens 102, which rises at the upper magnetic pole 102a and then rises at a constant lower magnetic pole 102d. .

Inside the first lens 102, a plurality of deflectors 106, 107 and 108 for correcting aberrations are arranged. The deflector 106 has a magnetic pole 102a on the lens 102.
Inside, the deflector 107 is located at the center of the lens 102 in the vertical direction, and the deflector 108 is located below the lens 102.
It is located directly above 2d.

The second lens 103 has a shape similar to that of the first lens 102, and has an inverted size. The polarity of the second lens 103 is opposite to that of the first lens 102. Inside the second lens 103, the aberration correcting deflectors 109, 110 and 111 are arranged as in the case of the first lens 102.

First projection lens 102 and second projection lens 1
The contrast aperture 104 is arranged at a position where the crossover 105 between the positions 03 is formed. The contrast aperture 104 blocks the electron beam scattered by the non-patterned portion of the reticle 101.

[0010]

In the electron beam exposure apparatus as described above, it is known that the transferred and exposed pattern is blurred or distorted due to the Coulomb effect. In particular, in the above-described division transfer method, the area (subfield) transferred at one time is as large as about 1 mm square, for example, and therefore, when exposing a small area where the pattern is unevenly distributed, the appearance of the Coulomb effect differs depending on the location.

The Coulomb effect can be reduced by shortening the length of the electron optical system, that is, the length of the lens barrel. However, if the length of the lens barrel is shortened, the geometrical aberration increases, so that the length of the lens barrel has a lower limit. However, if an optical system having a short lens barrel and a small geometric aberration is developed, the resolution of the optical system can be improved and the CD (minimum line width) can be reduced to form a finer pattern. be able to. Alternatively, since the large current can be passed by reducing the Coulomb effect, the throughput is improved.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electron beam exposure apparatus provided with an electron optical system having a short optical barrel and small geometric aberration. To do.

[0013]

In order to solve the above problems, a first electron beam exposure apparatus of the present invention is an illumination optical system for irradiating a reticle having a device pattern to be transferred onto a sensitive substrate with an electron beam. And a projection optical system including an electromagnetic lens and a deflector for projecting an image of an electron beam passing through the reticle onto the sensitive substrate to form an image, and substantially satisfy the following conditions: Electron beam exposure apparatus: (1) The electromagnetic lens of the projection optical system is composed of a first projection lens on the reticle side and a second projection lens on the sensitive substrate side, and these lenses have a 4: 1 similar shape. And (2) having an exciting coil with an equal ampere-turn and an exciting current ratio of 1: -1, (2) the accelerating voltage of the electron beam is 15 keV or more (representative value 100 keV), (3) all on the sensitive substrate Exposure area The size of the area (subfield) can be up to 0.5 mm × 0.25 mm. (4) The convergence half-angle of the electron beam to the sensitive substrate is 1.4 mrad.
(5) The distance from the reticle to the sensitive substrate is 400 mm (± 0.75% acceptable), (6)
Position Z in the optical axis direction of the center of the first projection lens on the reticle side
Is Z = 160 mm (± 0.3 mm is possible) (however,
The position of the reticle is Z = 0), and the optical axis position Z of the center of the second projection lens on the side of the sensitive substrate is Z = 360 mm (±
(7) The inner diameter of the first projection lens is 42 mm and the gap is 160 mm (± 0.3% when the gap and the inner diameter are changed at the same time), and Inner diameter is 10.5 mm and gap is 40
mm (If the gap and inner diameter are changed at the same time, ±
(8%) Six aberration-deflecting deflectors are arranged, and their positions in the optical axis direction are Z = 43.7 to 45.0 mm from the reticle-side deflector (typical value). 44.
3645 mm), 195.9 to 196.7 mm (representative value 196.282 mm), 253.9 to 255.6 mm
(Representative value 254.756 mm), 321.1 to 324.
1 mm (typical value 322.547 mm), 360.09-
360.18 mm (representative value 360.1 mm), 377.
(9) The scale factor of each deflector, which is 39 to 377.69 mm (representative value 377.54 mm), is 1.554 to 1.589 (representative value 1.57049), 1 from the reticle side deflector. .102 to 1.112 (representative value 1.10669), 1.470 to 1.479 (representative value 1.47453), 0.764 to 0.773 (representative value 0.768852), 0.2474 to 0. 2494 (typical value 0.248376), 0.3579 to 0.3616
(Representative value 0.359744), where the scale factor is 70 mm in length, 80 mm in inner diameter, 90 mm in outer diameter,
(10) The current ratio of each deflector, where the strength of the magnetic field produced by the deflector with one coil turn is 1 / scale factor,
From the reticle side deflector, 0.987-1.010
(Typical value 1), -1.145 to -1.138 (typical value-
1.14122), 1.096 to 1.102 (representative value 1.09899), -0.680 to -0.676 (representative value -0.677847), 1.017 to 1.026 (representative value 1. 02177), -1.143 to -1.129.
(Representative value-1.13566), where the current ratio is a value when normalized by the current of the first deflector, (1
1) The angle formed by the deflecting magnetic field of each deflector in the plane perpendicular to the optical axis is 62.074 ° from the deflector on the reticle side.
63.391 ° (representative value 62.7171 °), 55.3
65 ° to 55.744 ° (representative value 55.553 °), −
5.065 ° to -4.74 ° (representative value -4.8972)
), -23.632 ° to -23.253 ° (typical value-
23.4464 °), 62.917 ° to 63.443 °
(Representative value 63.1591 °), 56.518 ° to 57.
245 ° (representative value 56.9106 °), where the angle is the angle between the X-axis set in the plane perpendicular to the optical axis and the deflection magnetic field.

Under the conditions where the above numerical values are satisfied, according to the numerical simulations of the present inventors, the vertical incidence of the beam on the sensitive substrate (wafer) is 0.5 mrad or less, the blur is 34 nm or less, the distortion is 3.5 nm or less, Alternatively, an imaging performance equivalent to that can be obtained.

A second electron beam exposure apparatus of the present invention is an illumination optical system for irradiating a reticle having a device pattern to be transferred on a sensitive substrate with an electron beam, and an electron beam passing through the reticle to the sensitive substrate. A projection optical system including an electromagnetic lens and a deflector for projecting and forming an image thereon,
An electron beam exposure apparatus which substantially satisfies the following conditions: (1) The acceleration voltage of the electron beam is 13 keV or more (representative value 100 keV), (2) the collective exposure area on the sensitive substrate ( Maximum size of subfield is 1 mm ×
(3) The opening half-angle of the electron beam to the sensitive substrate is 0.4 mrad or less (representative value 0.1 m).
(4) The distance from the reticle to the sensitive substrate is 398.5-401.5 mm (typical value 40).
(5) The position Z of the contrast aperture in the optical axis direction is Z = 321.86 to 322.02 mm (representative value 3).
21.94 mm) (however, set the reticle position to Z
= 0), (6) the electromagnetic lens of the projection optical system is
From the reticle side, a first projection lens, a second projection lens,
The third projection lens is used, and the position Z of the center of the first projection lens in the optical axis direction is Z = 70.50 to 70.82 mm (representative value 70.6606 mm) (where the reticle position is Z = 0. The optical axis position Z of the center of the second projection lens is Z = 266.26 to 266.66 mm (representative value 266.458 mm), and the optical axis position Z of the center of the third projection lens is Z = 359. 51-359.60 mm
(Representative value 359.552 mm), (7) the first
The current ratio of the projection lens is 0.996 to 1.004 (typical value 1), and the current ratio of the second projection lens is 2.768 to 2.
775 (typical value 2.77144), the current ratio of the third projection lens is -11.254 to -11.220 (typical value-
11.2377), where the current ratio is a value when normalized by the current of the first electromagnetic lens. (8) The inner diameter of the first projection lens is 117 mm and the gap is 60.9.
8 mm (± 0.2% when the gap and inner diameter are changed at the same time), and the inner diameter of the second projection lens is 90 mm
And the gap is 47.78 mm (± 0.3% is possible when the gap and the inner diameter are changed at the same time), and the inner diameter of the third projection lens is 59.5 mm and the gap is 30.04 mm.
(If the gap and inner diameter are changed at the same time, ± 0.
(2% acceptable), (9) Six aberration-deflecting deflectors are arranged, and their positions in the optical axis direction are Z = 26.171 to 27.810 mm from the deflector on the reticle side (representative value 2
7.0199 mm), 117.729 to 118.688
mm (representative value 118.209 mm), 169.305-
170.317 mm (typical value 169.808 mm), 2
72.344 to 272.663 mm (representative value 272.5
06 mm), 341.150 to 341.233 mm (representative value 341.192 mm), 368.007 to 368.
621 mm (representative value 368.315 mm), (1
0) The length, inner diameter, and outer diameter of the aberration correcting deflector are as follows: length = 15.2 mm from the reticle-side deflector; inner diameter =
43.35 mm; outer diameter = 63.4 mm (± 2.7% when the length, inner diameter, and outer diameter are changed at the same time), length = 1
6.35 mm; inner diameter = 33.775 mm; outer diameter = 72.
675 mm (± 1.9% when the length, inner diameter, and outer diameter are changed at the same time), length = 13.2 mm; inner diameter = 26.3
5 mm; outer diameter = 63.4 mm (± 4.0% when the length, inner diameter, and outer diameter are changed at the same time), length = 13.2 m
m; inner diameter = 25.35 mm; outer diameter = 70.4 mm (± 0.6% when the length, inner diameter, and outer diameter are changed at the same time)
OK), length = 16.65 mm; inner diameter = 19.35 mm;
Outer diameter = 41.6 mm (± 0.3% is possible if the length, inner diameter, and outer diameter are changed at the same time), length = 13.2 mm; inner diameter =
19.35 mm; outer diameter = 41.6 mm (± 1.6% when the length, inner diameter, and outer diameter are changed at the same time), (11) The current ratio of the aberration correction deflector is on the reticle side. From the deflector, 0.975 to 1.025 (typical value 1), 0.9
69 to 0.988 mm (typical value 0.97837), 1.
253-1.265 (representative value 1.25925), 1.7
17-1.722 (representative value 1.71940), -2.0
23 to -2.018 (representative value -2.02026), 0.
594 to 0.632 (representative value 0.61242), where the current ratio is a value when normalized by the current of the first deflector. (12) Optical axis of the deflection magnetic field of each deflector The angle formed in the vertical plane is 8 degrees from the deflector on the reticle side.
3.517 to 86.503 ° (typical value 84.9883)
°), -117.527 to -116.346 ° (representative value -116.9456 °), -26.332 to -25.7.
55 ° (typical value −26.0417 °), −75.690
~ -75.483 ° (typical value -75.5877 °),-
54.301 to -54.126 ° (representative value -54.21)
31 °), −79.450 to −75.817 ° (representative value −77.6344 °), where the angle is the angle formed by the X axis set in the plane perpendicular to the optical axis and the deflection magnetic field. .

Under the condition that the above numerical values are satisfied, according to the numerical simulation of the present inventors, the blurring of 34 nm
Hereinafter, an image forming performance with a distortion of 3.5 nm or less, or equivalent thereto, can be obtained. Particularly, in the case of the representative value of each element, performance with blurring of 8.84 nm and distortion of 2.64 nm can be obtained.

A third electron beam exposure apparatus of the present invention is an electron beam exposure apparatus in which the distance from the reticle to the sensitive substrate exceeds the stipulations of claim 1 or 2, and the other specifications are It is characterized in that the adjustment is optimized by the idea of giving a current value or an angle that returns the change in the magnetic field due to the change in the shape of the optical system.

[0018]

DETAILED DESCRIPTION OF THE INVENTION A description will be given below with reference to the drawings. FIG. 1 is a diagram schematically showing the positional relationship of each part of the projection optical system of the electron beam exposure apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram schematically showing electron beam trajectories on the wafer of the projection optical system of FIG. FIG. 3 is a diagram schematically showing an example of the configuration and image formation relationship of the entire optical system of the electron beam exposure apparatus. First, a configuration example of a split transfer type electron beam exposure apparatus and a state of image formation will be described with reference to FIG. The electron gun 1 arranged in the uppermost stream of the optical system is directed downward,
The electron beam is emitted at an acceleration voltage of 100 keV. Electron gun 1
Is provided with two-stage condenser lenses 2 and 3, and the electron beam is converged by these condenser lenses 2 and 3 and crosses over the blanking aperture 7 at the crossover C.I. O. Image.

Below the second-stage condenser lens 3,
A rectangular opening 4 is provided. The rectangular aperture (illumination beam shaping aperture) 4 allows only an illumination beam that illuminates one subfield (a pattern small region that is one unit of exposure) of the reticle 10. The image of the opening 4 is formed on the reticle 10 by the lens 9.

A blanking deflector 5 is arranged below the beam shaping aperture 4. The deflector 5 deflects the illumination beam when necessary and strikes the non-aperture portion of the blanking aperture 7 so that the beam does not strike the reticle 10.
An illumination beam deflector 8 is arranged below the blanking aperture 7. The deflector 8 mainly sequentially scans the illumination beam in the X direction in the drawing to illuminate each subfield of the reticle 10 within the field of view of the illumination optical system. An illumination lens 9 is arranged below the deflector 8. The illumination lens 9 forms an image that has passed through the beam shaping aperture 4 on the reticle 10.

The reticle 10 actually has a large number of subfields (only one subfield is shown in the figure), and is mounted on the movable reticle stage 11. By moving the reticle stage 11 in the XY directions in the plane perpendicular to the optical axis, each subfield on the reticle that spreads over a wider range than the field of view of the illumination optical system is illuminated. A position detector 12 is attached to the reticle stage 11.

Below the reticle 10, a first projection lens 1 is provided.
5, a second projection lens 19 and a deflector 16 used for aberration correction and image position adjustment are provided (detailed dimensions and positional relationship of the projection lens and the deflector will be described later). The electron beam that has passed through one subfield of the reticle 10 is imaged at a predetermined position on the wafer (sensitive substrate) 23 by the projection lenses 15 and 19 and the deflector 16.
At this time, the half-angle of convergence of the electron beam on the wafer 23 (θ in FIG. 2) is 1 mrad.

In this example, the distance between the wafer 23 and the reticle 10 (L1 in FIG. 1) is 400 mm. The distance between the reticle 10 and the wafer 23 is a number representing the length of the lens barrel of the projection optical system. The conventional typical value of this dimension is 6
It is 00 mm. An appropriate resist is applied on the wafer 23, and a dose of an electron beam is applied on the resist to reduce the pattern on the reticle 10 (1/4 in one example).
Then, it is transferred onto the wafer 23. The maximum size of the subfield transferred onto the wafer 23 is 0.5 mm ×
It can be up to 0.25 mm. The size of the subfield on the wafer is 0.25 mm square in the related art, and the area of the subfield in this example is twice the size of the conventional one. In this case, the size of the subfield on the reticle 10 is the size on the wafer 23 divided by the reduction ratio ¼, which is 2 mm × 1 mm in this example.

At the point where the reticle 10 and the wafer 23 are internally divided by the reduction ratio, the crossover C.I. O. And a contrast opening 18 is provided at the crossover position. The opening 18 blocks the electron beam scattered by the non-patterned portion of the reticle 10 from reaching the wafer 23.

The backscattered electron detector 22 is located directly above the wafer 23.
Are arranged. The backscattered electron detector 22 detects the amount of electrons reflected by the exposed surface of the wafer 23 or the mark on the stage. From this detection information, it is possible to know the relative positional relationship between the reticle 10 and the wafer 23 and the beam characteristics in the projection optical system.

The wafer 23 is moved in the XY direction through the electrostatic chuck.
It is mounted on a wafer stage 24 that can move in any direction. A position detector 25 is attached to the wafer stage 24. By synchronously scanning the reticle stage 11 and the wafer stage 24 in opposite directions based on the positions detected by the position detectors 12 and 25, each part of the device pattern that extends beyond the visual field of the projection optical system can be detected. It exposes sequentially.

The lenses 2, 3, 9, 15, and 19 and the deflectors 5, 8 and 16 are respectively power supply control units 2a, 3a and 9 respectively.
It is controlled by the controller 31 via a, 15a, 19a and 5a, 8a, 16a. The reticle stage 11 and wafer stage 24 are also controlled by the controller 31 via the control units 11a and 24a. Further, the stage position detectors 12 and 25 and the backscattered electron detector 22 also send signals to the controller 31 via the interfaces 12a, 25a and 22a. The controller 31 controls the stage position, the beam position, etc. from the sent signal.

The dimensions and positional relationship of the first projection lens 15 and the second projection lens 19 will be described with reference to FIG. The first projection lens 15 has a U-shaped rotationally symmetric magnetic pole having an inward cross-section, and a coil arranged on the inner circumference thereof. The upper magnetic pole and the lower magnetic pole protrude toward the optical axis, and
In the projection lens 15, a magnetic field is formed which rises at the upper magnetic pole and then falls at a constant lower magnetic pole.

The second projection lens 19 is the first projection lens 1
The shape of 5 is downsized and inverted. The shapes of the first projection lens 15 and the second projection lens 19 (pole Bohr diameter, lens gap) are similar, and the dimensions are the first projection lens: the second projection lens.
Projection lens = 4: 1. Further, each projection lens is arranged in a point symmetrical position. Further, each projection lens has an exciting coil with an ampere-turn whose polarities are opposite to each other, and satisfies the condition of the symmetrical magnetic doublet type lens. The first projection lens 15 has an inner diameter D1 of 42 mm and a gap G1 of 160 mm.
And the second projection lens 19 has an inner diameter D2 of 10.5 mm.
The gap G2 is 40 mm.

The distance L1 between the reticle 10 and the wafer 23 is 400 mm as described above, and the distance L2 from the reticle 10 to the center of the first projection lens 15 in the optical axis direction is 16.
The distance L3 from the reticle 10 to the center of the second projection lens 19 in the optical axis direction is 360 mm.

The distance L4 from the reticle 10 to the first deflector 16-1 is 44.3645 mm, and the second deflector 16-
The distance L5 to 2 is 196.282 mm, the third deflector 1
The distance L6 up to 6-3 is 254.756 mm, the distance L7 up to the fourth deflector 16-4 is 322.547 mm, fifth.
The distance L8 to the deflector 16-5 is 360.1 mm, the sixth
The distance L9 to the deflector 16-6 is 377.54 mm.

Table 1 shows the scale factor of each deflector,
The current ratio and the angle formed by the deflection magnetic field in the plane perpendicular to the optical axis are shown. The scale factor is 70 mm in length and 80 in inside diameter
This is a value when the strength of the magnetic field produced by a deflector having a diameter of mm, an outer diameter of 90 mm, and a coil turn number of 1 is 1 / scale factor. The current ratio is a value when normalized by the current of the first deflector. The angle formed in the plane perpendicular to the optical axis is
It is the angle formed by the deflection magnetic field and the X axis set in the plane perpendicular to the optical axis.

[0033]

[Table 1]

Under the condition that the above numerical values are satisfied,
As a result of a numerical simulation, the vertical incidence of the beam on the sensitive substrate (wafer) was 0.5 mrad or less, the blur was 34 nm or less, and the strain was 3.5 nm or less.

Next, an electron beam exposure apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram schematically showing the positional relationship of each part of the projection optical system of the electron beam exposure apparatus according to the second embodiment of the present invention. In the projection optical system of the electron beam exposure apparatus of FIG. 5, three stages of projection lenses 65, 67 and 69 are arranged. This is done, so to speak, by dividing the upper stage projection lens of the projection optical system of the electron beam exposure apparatus of FIG. 1 into two. The purpose is to increase the degree of freedom and design a higher performance optical system.

Next, the dimensions and positional relationship of the first projection lens 65, the second projection lens 67, the third projection lens 69, and the deflector 66 will be described. Here, each lens 65, 67,
69 and the size and positional relationship of the deflector 66, the accelerating voltage of the electron gun described above, the reticle 10 to the contrast aperture 1
The distance L60 up to 8 is such that the size of the subfield is as large as possible and the distance L50 between the reticle and the wafer is L50.
Is calculated as a simulation by optimizing so that geometric blurring and distortion are as small as possible. In this example, the wafer 23
The distance between the reticle 10 and the reticle 10 (L50 in FIG. 5) is 400 mm.
Is. The size of the subfield transferred onto the wafer 23 can be up to 1 mm × 1 mm. Incidentally, the size of the subfield on the wafer is conventionally 0.
The area is 25 mm square, and the area of the subfield in this example is 16 times larger than the conventional size. In this case, the size of the sub-field on the reticle 10 is the size on the wafer 23 divided by the reduction ratio 1/4, which is 4 mm in this example.
× 4 mm.

The first projection lens 65 and the second projection lens 6
7. The three projection lenses of the third projection lens 69 have a U-shaped rotationally symmetric magnetic pole having an inward cross-section, and a coil arranged on the inner circumference thereof. The upper magnetic pole and the lower magnetic pole are
It projects toward the optical axis. Table 2 shows the inner diameter D and the gap G of each lens.

[Table 2]

Table 3 shows the distance L from the reticle 10 to the center of the optical axis of each lens and the current ratio of each lens. Here, the current ratio is a value when normalized by the current of the first lens.

[Table 3]

Table 4 shows the length, inner diameter, and outer diameter of each deflector 56.

[Table 4]

Table 5 shows the distance L from the reticle 10 to the center of the optical axis of each deflector, the current ratio of each deflector, and the angle of the deflection magnetic field. Here, the current ratio is a value when normalized by the current of the first deflector. The angle of the deflection magnetic field is the angle formed by the deflection magnetic field and the X axis set in the plane perpendicular to the optical axis.

[Table 5]

Under the condition that the above numerical values are satisfied,
As a result of the numerical simulation, the blurring is 8.84n.
m, and the strain was 2.64 nm.

[0042]

As is apparent from the above description, according to the present invention, even if the distance between the reticle and the wafer is as short as 400 mm, the emission angle of the electron beam from the reticle and the incident angle to the wafer are zero. Less than 0.5 mrad, blurring less than 34 nm,
It is possible to form a projection optical system having a distortion of about 3.5 nm or less. As described above, since it is possible to provide a projection optical system having a short lens barrel and a small geometrical aberration, it is possible to improve the resolution of the optical system and form a finer pattern in the electron beam exposure apparatus. Alternatively, since the large current can be passed by reducing the Coulomb effect, the throughput is also improved. Further, since the subfield can be made larger than usual, the throughput is further improved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a positional relationship between respective parts of a projection optical system of an electron beam exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing electron beam trajectories on a wafer in the projection optical system of FIG.

FIG. 3 is a diagram schematically showing an example of a configuration of an entire optical system of an electron beam exposure apparatus and an image forming relationship.

FIG. 4 is a side sectional view schematically showing an example of a projection optical system to which an aberration reduction technique is applied.

FIG. 5 is a diagram schematically showing a positional relationship of each part of a projection optical system of an electron beam exposure apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

1 electron gun 2, 3 condenser lens 4 rectangular aperture 5 blanking deflector 7 blanking aperture 9 illumination lens 10 reticle 11 reticle stage 12 position detector 15 first projection lens 16 deflector 18 contrast aperture 19 second projection lens 22 reflection Electron detector 23 Wafer (sensitive substrate) 24 Wafer stage 25 Position detector 31 Controller 65 First projection lens 66 Deflector 67 Second projection lens 69 Third projection lens

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) H01J 37/305 H01L 21/30 541A

Claims (3)

[Claims] 1. An illumination optical system for irradiating a reticle having a device pattern to be transferred onto a sensitive substrate with an electron beam, an electromagnetic lens for projecting an image of an electron beam passing through the reticle onto the sensitive substrate, and A projection optical system including a deflector, and an electron beam exposure apparatus substantially satisfying the following conditions: (1) A first projection lens in which the electromagnetic lens of the projection optical system is on the reticle side And a second projection lens on the side of the sensitive substrate, the lenses having a similar shape of 4: 1 and having exciting coils with equal ampere turns and an exciting current ratio of 1: -1, (2) The acceleration voltage of the electron beam is 15 keV or more (representative value 100 keV). (3) The size of the collective exposure region (subfield) on the sensitive substrate can be up to 0.5 mm × 0.25 mm. ) Convergence half of said electron beam to the sensitive substrate is 1.4mrad
(5) The distance from the reticle to the sensitive substrate is 400 mm (± 0.75% acceptable), (6)
Position Z in the optical axis direction of the center of the first projection lens on the reticle side
Is Z = 160 mm (± 0.3 mm is possible) (however,
The position of the reticle is Z = 0), and the optical axis position Z of the center of the second projection lens on the side of the sensitive substrate is Z = 360 mm (±
(7) The inner diameter of the first projection lens is 42 mm and the gap is 160 mm (± 0.3% when the gap and the inner diameter are changed at the same time), and Inner diameter is 10.5 mm and gap is 40
mm (If the gap and inner diameter are changed at the same time, ±
(8%) Six aberration-deflecting deflectors are arranged, and their positions in the optical axis direction are Z = 43.7 to 45.0 mm from the reticle-side deflector (typical value). 44.
3645 mm), 195.9 to 196.7 mm (representative value 196.282 mm), 253.9 to 255.6 mm
(Representative value 254.756 mm), 321.1 to 324.
1 mm (typical value 322.547 mm), 360.09-
360.18 mm (representative value 360.1 mm), 377.
(9) The scale factor of each deflector, which is 39 to 377.69 mm (representative value 377.54 mm), is 1.554 to 1.589 (representative value 1.57049), 1 from the reticle side deflector. .102 to 1.112 (representative value 1.10669), 1.470 to 1.479 (representative value 1.47453), 0.764 to 0.773 (representative value 0.768852), 0.2474 to 0. 2494 (typical value 0.248376), 0.3579 to 0.3616
(Representative value 0.359744), where the scale factor is 70 mm in length, 80 mm in inner diameter, 90 mm in outer diameter,
(10) The current ratio of each deflector, where the strength of the magnetic field produced by the deflector with one coil turn is 1 / scale factor,
From the reticle side deflector, 0.987-1.010
(Typical value 1), -1.145 to -1.138 (typical value-
1.14122), 1.096 to 1.102 (representative value 1.09899), -0.680 to -0.676 (representative value -0.677847), 1.017 to 1.026 (representative value 1. 02177), -1.143 to -1.129.
(Representative value-1.13566), where the current ratio is a value when normalized by the current of the first deflector, (1
1) The angle formed by the deflecting magnetic field of each deflector in the plane perpendicular to the optical axis is 62.074 ° from the deflector on the reticle side.
63.391 ° (representative value 62.7171 °), 55.3
65 ° to 55.744 ° (representative value 55.553 °), −
5.065 ° to -4.74 ° (representative value -4.8972)
), -23.632 ° to -23.253 ° (typical value-
23.4464 °), 62.917 ° to 63.443 °
(Representative value 63.1591 °), 56.518 ° to 57.
245 ° (representative value 56.9106 °), where the angle is the angle between the X-axis set in the plane perpendicular to the optical axis and the deflection magnetic field. 2. An illumination optical system for irradiating a reticle having a device pattern to be transferred onto a sensitive substrate with an electron beam, an electromagnetic lens for projecting an image of an electron beam passing through the reticle onto the sensitive substrate, and An electron beam exposure apparatus comprising: a projection optical system including a deflector and substantially satisfying the following conditions: (1) The acceleration voltage of the electron beam is 13 keV or more (representative value 100 keV) (2) The maximum size of the batch exposure area (subfield) on the sensitive substrate is 1 mm ×
(3) The opening half-angle of the electron beam to the sensitive substrate is 0.4 mrad or less (representative value 0.1 m).
(4) The distance from the reticle to the sensitive substrate is 398.5-401.5 mm (typical value 40).
(5) The position Z of the contrast aperture in the optical axis direction is Z = 321.86 to 322.02 mm (representative value 3).
21.94 mm) (however, set the reticle position to Z
= 0), (6) the electromagnetic lens of the projection optical system is
From the reticle side, a first projection lens, a second projection lens,
The third projection lens is used, and the position Z of the center of the first projection lens in the optical axis direction is Z = 70.50 to 70.82 mm (representative value 70.6606 mm) (where the reticle position is Z = 0. The optical axis position Z of the center of the second projection lens is Z = 266.26 to 266.66 mm (representative value 266.458 mm), and the optical axis position Z of the center of the third projection lens is Z = 359. 51-359.60 mm
(Representative value 359.552 mm), (7) the first
The current ratio of the projection lens is 0.996 to 1.004 (typical value 1), and the current ratio of the second projection lens is 2.768 to 2.
775 (typical value 2.77144), the current ratio of the third projection lens is -11.254 to -11.220 (typical value-
11.2377), where the current ratio is a value when normalized by the current of the first electromagnetic lens. (8) The inner diameter of the first projection lens is 117 mm and the gap is 60.9.
8 mm (± 0.2% when the gap and inner diameter are changed at the same time), and the inner diameter of the second projection lens is 90 mm
And the gap is 47.78 mm (± 0.3% is possible when the gap and the inner diameter are changed at the same time), and the inner diameter of the third projection lens is 59.5 mm and the gap is 30.04 mm.
(If the gap and inner diameter are changed at the same time, ± 0.
(2% acceptable), (9) Six aberration-deflecting deflectors are arranged, and their positions in the optical axis direction are Z = 26.171 to 27.810 mm from the deflector on the reticle side (representative value 2
7.0199 mm), 117.729 to 118.688
mm (representative value 118.209 mm), 169.305-
170.317 mm (typical value 169.808 mm), 2
72.344 to 272.663 mm (representative value 272.5
06 mm), 341.150 to 341.233 mm (representative value 341.192 mm), 368.007 to 368.
621 mm (representative value 368.315 mm), (1
0) The length, inner diameter, and outer diameter of the aberration correcting deflector are as follows: length = 15.2 mm from the reticle-side deflector; inner diameter =
43.35 mm; outer diameter = 63.4 mm (± 2.7% when the length, inner diameter, and outer diameter are changed at the same time), length = 1
6.35 mm; inner diameter = 33.775 mm; outer diameter = 72.
675 mm (± 1.9% when the length, inner diameter, and outer diameter are changed at the same time), length = 13.2 mm; inner diameter = 26.3
5 mm; outer diameter = 63.4 mm (± 4.0% when the length, inner diameter, and outer diameter are changed at the same time), length = 13.2 m
m; inner diameter = 25.35 mm; outer diameter = 70.4 mm (± 0.6% when the length, inner diameter, and outer diameter are changed at the same time)
OK), length = 16.65 mm; inner diameter = 19.35 mm;
Outer diameter = 41.6 mm (± 0.3% is possible if the length, inner diameter, and outer diameter are changed at the same time), length = 13.2 mm; inner diameter =
19.35 mm; outer diameter = 41.6 mm (± 1.6% when the length, inner diameter, and outer diameter are changed at the same time), (11) The current ratio of the aberration correction deflector is on the reticle side. From the deflector, 0.975 to 1.025 (typical value 1), 0.9
69 to 0.988 mm (typical value 0.97837), 1.
253-1.265 (representative value 1.25925), 1.7
17-1.722 (representative value 1.71940), -2.0
23 to -2.018 (representative value -2.02026), 0.
594 to 0.632 (representative value 0.61242), where the current ratio is a value when normalized by the current of the first deflector. (12) Optical axis of the deflection magnetic field of each deflector The angle formed in the vertical plane is 8 degrees from the deflector on the reticle side.
3.517 to 86.503 ° (typical value 84.9883)
°), -117.527 to -116.346 ° (representative value -116.9456 °), -26.332 to -25.7.
55 ° (typical value −26.0417 °), −75.690
~ -75.483 ° (typical value -75.5877 °),-
54.301 to -54.126 ° (representative value -54.21)
31 °), −79.450 to −75.817 ° (representative value −77.6344 °), where the angle is the angle formed by the X axis set in the plane perpendicular to the optical axis and the deflection magnetic field. . 3. An electron beam exposure apparatus in which the distance from the reticle to the sensitive substrate exceeds the stipulations of claim 1 or 2, wherein the other specifications are the change in magnetic field due to the change in shape of the optical system. An electron beam exposure apparatus characterized by being adjusted and optimized on the basis of giving an electric current value or an angle for returning.