Electron beam illumination device, and exposure apparatus with electron beam illumination device

An electron beam illumination device has an electron gun for emitting an electron beam, a slit plate formed with a slit opening portion, which has the beam axis of the electron gun as the center, and a deflector for scanning the electron beam along the slit opening portion by deflecting the electron beam, and rotating or reciprocally moving the electron beam to have the beam axis as the center. The electron beam irradiation region on the mask and the exposure region on the wafer can be broadened, and the electron beam can be irradiated onto these regions at uniform irradiation intensity.

BACKGROUND OF THE INVENTION 
The present invention relates to an electron beam illumination device used 
in the lithography process in the manufacture of semiconductor devices, 
and an exposure apparatus with the electron beam illumination device. 
Conventionally, in the lithography process in mass-production of 
semiconductor devices, an exposure technique based on light exposure is 
used. However, in recent years, as semiconductor devices continue to have 
a higher degree of integration, the line width in the device is shrinking. 
Especially, in semiconductor memory devices such as 1 G and 4 G DRAMs the 
line width is 0.2 .mu.m or less, which is considerably small. As an 
alternative exposure technique to light exposure, an exposure apparatus 
using electron beams with higher resolution is beginning to gain 
attention. 
However, existing electron beam exposure apparatuses mainly use a Gaussian 
method and variable forming method using a single beam, and require much 
time in the lithography process in the manufacture of semiconductor 
devices. Hence, owing to low productivity of semiconductor devices, the 
electron beam exposure apparatus is used in only limited applications that 
particularly require its excellent resolution performance, such as mask 
drawing, study and development of VLSIs, exposure of ASIC devices that are 
produced in small quantity, and the like. For this reason, improvements in 
the productivity of semiconductor devices are a major problem upon 
applying the electron beam exposure apparatus to the mass-production of 
semiconductor devices. 
As a means for solving the above problem, in recent years, so-called 
stepping transfer has been proposed. FIG. 17 is a perspective view showing 
an exposure apparatus using conventional stepping transfer. In the 
stepping transfer, as shown in FIG. 17, circuit patterns 101 to be 
repetitively formed on a wafer 102 are formed into cells, thereby 
improving productivity upon drawing interconnect patterns on the wafer 102 
by exposure. 
Since the maximum region of the wafer that can be exposed at one time using 
the stepping transfer is as small as about several .mu.m as in the 
variable forming method, a plurality of (e.g., two or three) deflectors 
must be used, and chromatic aberrations, distortion, and the like produced 
upon deflection must be removed using an MOL (movable objective lens 
system) to obtain a wider exposure region. In order to improve the 
productivity of semiconductor devices, it is again required to broaden the 
exposure region. However, it is hard to broaden the exposure region while 
maintaining both high overlay accuracy of exposure regions and high 
exposure resolution. For example, when the overlay accuracy of exposure 
regions ranges from 20 to 30 nm, and the exposure resolution is 0.2 .mu.m 
or less, the exposure region can be broadened to about 1 mm by deflection. 
As described above, in the conventional electron beam exposure apparatus, 
since the region of the wafer that can be exposed at one time is smaller 
than the entire region to be exposed on the wafer, means for scanning an 
electron beam or reciprocally moving a stage that carries a wafer or 
exposure mask is used to expose the entire region to be exposed on the 
wafer. 
However, as described above, since the exposure region of the electron beam 
is smaller than the region to be exposed on the wafer, the wafer must be 
reciprocally moved many times or the electron beam must be repetitively 
scanned to expose the entire region to be exposed on the wafer. For this 
reason, a longer wafer exposure time is required than a light exposure 
type exposure apparatus. 
In order to shorten the wafer exposure time, at least one of means for 
increasing the scanning speed of the electron beam or the moving speed of 
the stage that carries the wafer or exposure mark, and means for 
broadening the exposure region of the electron beam is required. 
However, with the means for increasing the scanning speed of the electron 
beam or the moving speed of the stage, the amount of irradiated electron 
beam may become short, and the wafer may not be sufficiently exposed. In 
such case, the irradiation intensity of the electron beam may be 
increased, but then the exposure image is blurred. 
On the other hand, with the means for broadening the exposure region of the 
electron beam, the electron beam must be irradiated at a uniform intensity 
within the exposure region so as to obtain a uniform line width on the 
wafer. However, the exposure region on the wafer by a single electron beam 
is as small as several .mu.m, and even when a conventional emittance LaB6 
electron gun having a deflector is used, the emittance value (the product 
of the crossover and electron beam output angle) is as low as about 
several 10 .mu.m mrad. For this reason, when a conventional electron beam 
illumination system is used, it is difficult to further broaden the 
exposure region and to uniformly irradiate the electron beam onto that 
exposure region. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide an electron 
beam illumination device, which can uniformly illuminate an electron beam 
onto an exposure region while broadening that exposure region. It is 
another object of the present invention to provide an exposure apparatus 
which can decrease the number of exposure scans onto the wafer and can 
shorten the exposure time using such electron beam illumination device. 
In order to achieve the above objects, an electron beam illumination device 
according to the present invention comprises an electron gun for emitting 
an electron beam, a slit plate unit formed with an arcuated slit opening 
portion which has as the center an extending line of a path of the 
electron beam emitted by the electron gun, and deflection means for 
scanning the electron beam along the slit opening portion by deflecting 
the electron beam emitted by the electron gun before the electron beam is 
irradiated onto the slit plate unit, and rotating or reciprocally moving 
the electron beam to have as the center the extending line of the path of 
the electron beam. 
With this arrangement, of the electron beam scanned along the slit opening 
portion, the electron beam that has passed through the slit opening 
portion forms an arcuated electron beam band, thus broadening the 
illumination region. 
According to a preferred aspect of the present invention, a speed of the 
electron beam that scans the slit opening portion makes an irradiation 
intensity of an arcuated electron beam band formed when the electron beam 
has passed through the slit opening portion uniform in the entire arcuated 
electron beam band. Hence, thermal strain of a mask and wafer irradiated 
with the electron beam can be reduced. 
Also, according to a preferred aspect of the present invention, the slit 
plate unit comprises a convex blade formed with an arcuated convex edge, 
and a concave blade formed with an arcuated concave edge having the same 
diameter as a diameter of the convex edge, the slit opening portion is 
defined by disposing the convex and concave blades with the arcuated edges 
thereof opposing each other, and at least one of the convex and concave 
blades is attached with a drive unit for adjusting a spacing between the 
convex and concave blades, thereby adjusting the arc width of the arcuated 
electron beam band. By controlling the arc width, the irradiation 
intensity of the arcuated electron beam band can be finely adjusted, and 
the resolution of a pattern image can also be adjusted. 
In addition, according to a preferred aspect of the present invention, the 
slit plate unit comprises a light-shielding blade for adjusting a length 
of the slit opening portion defined by the convex and concave blades, 
thereby adjusting the arc length of the arcuated electron beam band. 
Hence, the arc length can be optimally set in correspondence with the size 
of the region to be exposed. 
Furthermore, according to a preferred aspect of the present invention, the 
center of rotation or reciprocal movement of the electron beam that scans 
the slit opening portion is shifted from the center of the slit opening 
portion along the central axis of the slit opening portion by the 
deflection means, thereby adjusting the arc width of the arcuated electron 
beam band, since the electron beam that scans the slit opening portion 
hits only one edge of the slit opening portion and the arc width of the 
arcuated electron beam band is decreased. 
According to a preferred aspect of the present invention, an exposure 
apparatus of the present invention, which comprises an illumination device 
for projecting a circuit pattern drawn on the mask onto a wafer, and 
projects the circuit pattern onto the wafer by exposure while 
synchronously moving the wafer and mask, uses one of the electron beam 
illumination devices of the present invention as the illumination device. 
According to a preferred aspect of the present invention, a scanning cycle 
of the electron beam onto the slit opening portion is a cycle which is 
shorter than a moving time of the mask by a distance equal to a width of 
the arcuated electron beam band when the arcuated electron beam band 
formed by the electron beam that has passed through the slit opening 
portion is projected onto the mask, and is a divisor of the moving time, 
thereby preventing exposure errors such as formation of non-exposed 
portions, double exposure, and the like of the wafer. 
Moreover, according to a preferred aspect of the present invention, since 
the exposure apparatus further comprises an electron detection unit for 
detecting an electron emitted by the mask irradiated with the electron 
beam, and a blanking electrode unit for controlling irradiation of the 
electron beam onto the mask on the basis of information obtained from the 
electron detection unit, the electron beam can be prevented from being 
unnecessarily irradiated onto a portion without any circuit pattern on the 
mask, thus preventing thermal strain of the mask. 
Lastly, according to a preferred aspect of the present invention, since the 
exposure apparatus further comprises mask reference mark detection means 
for detecting a position reference mark formed on the mask, and wafer 
reference mark detection means for detecting a position reference mark 
formed on the wafer, the position reference mark positions formed on the 
mask and wafer can be detected. The mask and wafer are moved relative to 
each other based on the detection results, thus aligning them.

DETAILED DESCRIPTION OF THE INVENTION 
Preferred embodiment of the present invention will be described in detail 
in accordance with the accompanying drawings. 
FIG. 1 shows the overall arrangement of an exposure apparatus according to 
an embodiment of the present invention. As shown in FIG. 1, an exposure 
apparatus 1 of this embodiment comprises an electron beam illumination 
device 2 as an illumination source of an electron beam 5, and a projection 
device 3 for projecting an electron beam coming from the electron beam 
illumination device 2 onto a wafer 32. 
The electron beam illumination device will be explained below with 
reference to FIGS. 1 and 2. FIG. 2 shows the overall arrangement of the 
electron beam illumination device shown in FIG. 1. 
As shown in FIGS. 1 and 2, the electron beam illumination device 2 has an 
electron gun 4 for irradiating an electron beam 5, condencer lenses 6a and 
6b for converging the electron beam 5 emitted by the electron gun 4, 
magnetic or electric field type deflector units 7 and 8 for deflecting the 
electron beam 5, and a slit plate 9 formed with an arcuated slit opening 
portion 9a and an electron beam through hole 9b. Note that the slit 
opening portion 9a is an arcuated slit having a beam axis 24 (i.e., the 
extending line of the path of the electron beam 5 emitted by the electron 
gun 4) of the electron beam illumination device 2 as the center, and the 
electron beam through hole 9b is formed on the beam axis 24 of the 
electron beam illumination device 2. Furthermore, a blanking electrode 10 
for suppressing irradiation of the electron beam 5, and an aperture 11 for 
helping to converge the electron beam at the condencer lenses 6a and 6b 
are inserted between the condencer lenses 6a and 6b as needed. 
As shown in FIG. 3, the deflector units 7 and 8 respectively comprise four 
deflectors 7a, 7b, 8a, and 8b, i.e., the deflectors 7a and 8a which face 
each other in the X-direction, and the deflectors 7b and 8b which face 
each other in the Y-direction. In the upper deflector unit 7, sine 
components of a deflection signal are input to the deflectors 7a facing 
each other in the X-direction, and cosine components of the deflection 
signal are input to the deflectors 7b facing each other in the 
Y-direction. In the lower deflector unit 8 as well, sine components of a 
deflection signal are input to the deflectors 8a facing each other in the 
X-direction, and cosine components of the deflection signal are input to 
the deflectors 8b facing each other in the Y-direction. 
With this arrangement, as shown in FIGS. 1 and 2, the deflector units 7 and 
8 rotate the electron beam 5, that has been converged by the condencer 
lenses 6a and 6b, about the beam axis 24 of the electron beam illumination 
device 2, and scan the beam 5 along the slit opening portion 9a. 
FIG. 4 shows the arrangement of the slit plate in the electron beam 
illumination device shown in FIG. 2 in detail. 
As shown in FIG. 4, a convex blade 12 formed with an arcuated convex edge 
12a, and a concave blade 13 having an arcuated concave edge 13a, which has 
the same diameter as that of the arc of the convex edge 12a, are disposed 
so that their arcuated edges 12a and 13a oppose each other, thus defining 
a constant slit width of the slit opening portion 9a. Drive units 14 for 
driving the convex and concave blades 12 and 13 in the X-direction are 
attached to these blades. Hence, when at least one of the convex and 
concave blades 12 and 13 is driven by operating the drive units 14, the 
arc width of the arcuated electron beam band can be adjusted. 
Light-shielding blades 15 and 16 for adjusting the length of the slit 
opening portion 9a are arranged above (front side in FIG. 4) the convex 
and concave blades 12 and 13. Drive units 17 for moving the 
light-shielding blades 15 and 16 are respectively attached to these 
blades. When the light-shielding blades 15 and 16 are moved by operating 
the drive units 17, the length of the slit opening portion 9a can be 
adjusted. Hence, the slit length of the slit opening portion 9a can be 
optimally set in correspondence with the size of the region to be exposed 
on the wafer 32 (see FIG. 1), thus adjusting the arc length of the 
arcuated electron beam band. 
The arrangement of the projection device 3 will be explained below with the 
aid of FIG. 1 again. 
As shown in FIG. 1, the projection device 3 has a mask 18 on which a 
circuit pattern (not shown) is formed by electron beam transmission and 
non-transmission portions, and a reduction electron optical system 20 made 
up of projection lenses 19a and 19b for forming a pattern image defined by 
the electron beam 5 transmitted through the circuit pattern onto the wafer 
32. 
As the mask 18, either a scattering type mask prepared by forming a 
scattering pattern for scattering the electron beam 5 on a membrane that 
transmits the electron beam 5, or a stencil type mask prepared by forming 
an absorbing pattern for intercepting or attenuating the electron beam 5 
may be used. The mask 18 of this embodiment uses the scattering type mask. 
The mask 18 is placed on a mask stage 21 which is movable at least in the 
X- and Y-directions. 
In the projection device 3, a first electron detector 22 for detecting 
secondary electrons or reflected electrons emitted by the mask when the 
electron beam 5 is irradiated onto the mask 18 is disposed near the mask 
18. An aberration correction optical system 23 for correcting in advance 
aberrations (especially, astigmatism) produced when the electron beam 5 
passes through the reduction electron optical system 20 is inserted 
between the mask 18 and the upper projection lens 19a. 
Also, a rotation correction lens 25 for rotating the electron beam 5 about 
the beam axis 24 as the center, a scattered electron intercepting aperture 
26 for intercepting the electron beam 5 that has been transmitted through 
and scattered by the scattering pattern on the mask 18, and transmitting 
the electron beam 5 that has been transmitted through a portion other than 
the scattering pattern, and a position correction deflector 27 for 
correcting the position of the pattern image to be projected onto the 
wafer 32 are interposed between the projection lenses 19a and 19b. 
Furthermore, a focal point correction lens 28 for correcting the focal 
point of the reduction electron optical system 20 is disposed beneath the 
reduction electron optical system 20, and a second electron detector 29 
for detecting secondary electrons and reflected electrons emitted by the 
wafer 32 upon irradiation of the electron beam 5 onto the wafer 32 is 
disposed near the wafer 32. 
A wafer chuck 31 that fixes the wafer 32 is placed on a wafer stage 30 
which is movable in the X- and Y-directions, and is rotatable in the X-Y 
plane. The wafer 32 is placed on the wafer chuck 31. 
The arrangement of the aberration correction optical system 23 will be 
described in detail below with reference to FIGS. 5 and 6. FIG. 5 is a top 
view of the aberration correction optical system shown in FIG. 1, and FIG. 
6 is a sectional view of the aberration correction optical system taken 
along a line A--A in FIG. 5. 
As shown in FIG. 5, the aberration correction optical system 23 is formed 
with an arcuated opening portion 23d having the beam axis 24 (see FIG. 1) 
as the center like the slit opening portion 9a (see FIG. 1) of the slit 
plate 9. The arcuated opening portion 23d is formed at a position where it 
does not intercept the electron beam 5 that has been transmitted through 
the slit plate 9 and mask 18 (see FIG. 1). 
As shown in FIG. 6, the aberration correction optical system 23 comprises a 
unipotential lens made up of three electrodes 23a, 23b, and 23c. The 
electrodes 23a and 23c are set at the same potential V.sub.0 as that of an 
acceleration electrode (not shown), and the middle electrode 23b between 
the two electrodes 23a and 23c is set at a potential V.sub.1 different 
from V.sub.0. With this arrangement, the aberration correction optical 
system 23 serves as an electron lens, which has different divergence or 
convergence effects (i.e., different focal lengths) in the circumferential 
and radial directions of the arcuated opening portion 23d. Note that the 
aberration correction optical system 23 of this embodiment uses the 
unipotential lens made up of the three electrodes 23a, 23b, and 23c, as 
described above, but may use an electron lens made up of a single 
electrode as long as it can accelerate or decelerate the electron beam 
that has been transmitted through the slit plate and mask, and can have 
different divergence or convergence effects in the circumferential and 
radial directions of the arcuated opening portion. 
FIG. 7 is a block diagram showing the arrangement of principal part of the 
exposure apparatus according to the embodiment of the present invention. 
As shown in FIG. 7, the exposure apparatus 1 comprises an illumination 
distribution control circuit 33 for controlling the condencer lenses 6a 
and 6b, and deflector units 7 and 8, an aperture control circuit 34 for 
controlling the drive units 14 and 17 that move the blades 12, 13, 15, and 
16 shown in FIG. 4, a mask stage drive control circuit 35 for controlling 
the movement of the mask stage 21, a first laser interferometer 36 for 
measuring the position of the mask stage 21 in real time, an aberration 
control circuit 37 for controlling the aberration correction 
characteristics of the aberration correction optical system 23, and a 
deflection position correction circuit 38 for controlling the position 
correction deflector 27 that corrects the position of the pattern image to 
be projected onto the wafer 32. 
Also, the exposure apparatus 1 comprises a magnification control circuit 39 
for controlling the reduction magnification of the reduction electron 
optical system 20, an optical characteristic control circuit 40 for 
controlling the rotation correction lens 25 and focal point correction 
lens 28 which adjust the optical characteristics such as the focal point 
position, image rotation, and the like, a wafer stage drive control 
circuit 41 for controlling the movement of the wafer stage 30, a second 
laser interferometer 42 for measuring the position of the wafer stage 30 
in real time, and an electron detection circuit 43 for transferring the 
detection signals detected by the electron detectors 22 and 29 to a 
control system 44 (to be described below). 
Furthermore, the exposure apparatus 1 comprises the control system 44 for 
controlling the above-mentioned circuits, a CPU 45 for systematically 
controlling the above-mentioned circuits via the control system 44, a 
memory 46 for storing control data for the control system 44, and an 
interface 47 serving as an information transmission medium between the CPU 
45 and control system 44. 
The operation of the electron beam illumination device 2 will be explained 
below mainly using FIGS. 1, 8, and 9. 
The electron beam 5 emitted by the electron gun 4 is adjusted by the 
condencer lenses 6a and 6b to converge on the mask 18. The electron beam 5 
is deflected by the deflector unit 7, and enters the lower deflector unit 
8 in a direction to separate from the beam axis 24. The electron beam 5 is 
deflected again by the deflector unit 8, passes through the slit opening 
portion 9a of the slit plate 9, and strikes the mask 18 perpendicularly. 
As has been described above with the aid of FIG. 3, the deflectors 7a, 7b, 
8a, and 8b of the deflector units 7 and 8 receive the deflection signals 
so as to rotate the electron beam 5 about the beam axis 24. Hence, since 
the electron beam 5 rotates about the beam axis 24 while scanning the slit 
opening portion 9a, as shown in FIG. 8, the electron beam 5 that has 
passed through the slit opening portion 9a artificially forms an arcuated 
electron beam band. 
Alternatively, as shown in FIG. 9, an arcuated electron beam band may be 
formed by controlling the deflection of the electron beam 5 so that the 
electron beam 5 reciprocally scans the slit opening portion 9a to have the 
beam axis 24 as the center. However, in this case, the electron beam 
scanning speed on the slit opening portion 9a may not become constant due 
to the hysteresis of the deflector units 7 and 8 (see FIG. 1). For this 
reason, in order to reliably form an arcuated electron beam band with a 
uniform irradiation intensity of the electron beam 5, the electron beam 5 
is preferably rotated and scanned, as described above. 
The arc width of the arcuated electron beam band can be adjusted by the 
condencer lenses 6a and 6b, and is preferably adjusted to fall within the 
range from several .mu.m to several hundred .mu.m on the mask 18. 
Upon scanning of the electron beam 5, the mask 18 and wafer 32 may suffer 
thermal strain. However, such thermal strain can be eliminated by scanning 
the slit opening portion 9a at a scanning speed thermally equivalent to 
that in a case wherein the entire slit opening portion 9a is 
simultaneously irradiated with the electron beam, i.e., at a scanning 
speed at which the irradiation intensity of the electron beam 5 becomes 
thermally uniform on the entire arcuated electron beam band. Note that the 
scanning speed is preferably equal to or lower than about several .mu.sec. 
As described above, since the arcuated electron beam band is artificially 
formed by scanning the electron beam 5 along the slit opening portion 9a 
at high speed, even when a single electron beam or a conventional 
emittance LaB6 electron gun is used, the irradiation region of the 
electron beam 5 on the mask 18 and the exposure region on the wafer 32 can 
be broadened, and the electron beam 5 can be irradiated onto these regions 
at uniform irradiation intensity. 
In the above-mentioned electron beam illumination device 2, as shown in 
FIG. 8, since the electron beam 5 is scanned to extend on the edges on 
both sides of the slit opening portion 9a, the arc width of the arcuated 
electron beam band formed via the slit opening portion 9a depends on the 
slit width of the slit opening portion 9a. Hence, the arc width of the 
arcuated electron beam band is adjusted by changing the spacing between 
the convex and concave blades 12 and 13. In place of changing the spacing 
between the convex and concave blades 12 and 13, an offset signal may be 
input to the lower deflector unit 8 to shift the center of rotation of the 
electron beam 5 by .DELTA.x in the X-direction of the central axis of the 
slit opening portion 9a, so that the electron beam 5 scans only one edge 
of the slit opening portion 9a, as shown in FIG. 10. When the arc width of 
the arcuated electron beam band is controlled by scanning the electron 
beam 5 in such way, reduction adjustment of the irradiation intensity of 
the arcuated electron beam band can be attained, and the resolution of the 
pattern image can also be adjusted. 
The operation of the exposure apparatus 1 of this embodiment will be 
explained below. 
Alignment of the mask 18 and wafer 32 with respect to the beam axis 24 of 
the electron beam illumination device 2 will be explained below with 
reference to FIG. 11. 
Initially, the electron beam 5 is emitted by the electron gun 4, and is 
converged on the mask 18 by the condencer lenses 6a and 6b. At this time, 
the electron beam 5 passes through the electron beam through hole 9b 
formed on the slit plate 9. Subsequently, the electron beam 5 is scanned 
along the slit opening portion 9a by the deflector units 7 and 8, and 
secondary electrons or reflected electrons emitted by the mask 18 
irradiated with the electron beam 5 are detected by the first electron 
detector 22. With such mask reference mark detection means, position 
reference marks (not shown) formed on the mask 18 are detected. 
The mask 18 is removed from the position on the beam axis 24, and the 
electron beam 5 is converged on the wafer 32 by the projection lenses 19a 
and 19b. Subsequently, the electron beam 5 is deflected by the position 
correction deflector 27 to scan the wafer 32, and secondary electrons or 
reflected electrons emitted by the wafer 32 are detected by the second 
electron detector 29. With such wafer reference mark detection means, 
position reference marks (not shown) formed on the wafer 32 are detected. 
By aligning the mask stage 21 or wafer stage 30 on the basis of the 
position information of the detected position reference marks, the mask 18 
and wafer 32 are aligned with the beam axis 24 of the electron beam 
illumination device 2. 
The exposure operation of the exposure apparatus 1 will be explained below 
mainly using FIGS. 1 and 7. 
Upon reception of an "exposure" command from the CPU 45, the control system 
44 operates the drive units 14 and 17 via the aperture control circuit 34, 
thus moving the blades 12, 13, 15, and 16 (FIG. 4). With this control, the 
slit width and length of the slit opening portion 9a are set in 
correspondence with the exposure conditions. 
When the arc shape of the slit opening portion 9a is set, the illumination 
distribution control circuit 33 controls the condencer lenses 6a and 6b, 
and deflector units 7 and 8, so that the electron beam 5 that scans the 
slit opening portion 9a has a scanning speed and irradiation intensity 
corresponding to the set arc shape of the slit opening portion 9a. 
The arcuated electron beam band formed by the electron beam illumination 
device 2 projects a circuit pattern formed on the mask 18 and images it on 
the wafer 32, thus exposing the wafer 32. At this time, the mask stage 21 
and wafer stage 30 synchronously move to have a speed difference 
corresponding to the reduction magnification of the reduction electron 
optical system 20, thereby transferring the entire circuit pattern formed 
on the mask 18 onto the wafer 32 by exposure. 
FIG. 12 is a top view showing the exposure region of the arcuated electron 
beam band projected onto the wafer. Note that Sx in FIG. 12 indicates the 
arc width of the arcuated electron beam band, and Sy indicates its length. 
The arc width Sx and band length Sy of the arcuated electron beam band 
formed by the exposure apparatus 1 of this embodiment can be adjusted 
respectively within the range from about 0.01 mm to 1 mm and the range 
from about 1 mm to 10 mm by moving the blades 12, 13, 15, and 16 (see FIG. 
4). 
In general, a pattern image projected onto the wafer suffers larger 
aberrations (especially, curvature of field, astigmatism) with increasing 
distance from the beam axis. However, as shown in FIG. 1, since the 
arcuated electron beam band formed by the electron beam illumination 
device 2 of this embodiment is defined by the electron beam 5 that has 
been scanned to have the beam axis 24 as the center, the distance from the 
beam axis 24 is constant. For this reason, the curvature of field of the 
pattern image is negligibly small. Also, as shown in FIG. 13, the 
influences of astigmatism become larger with increasing distance from the 
beam axis 24. However, since such influences are negligible, the 
influences of astigmatism can be removed by correcting the astigmatism 
using the aberration correction optical system 23 shown in FIG. 6. 
Consequently, the pattern image (i.e., the exposure region) to be 
projected onto the wafer 32 can be broader than that formed by a 
conventional electron beam method, the influences of aberrations can be 
removed, and the electron beam 5 can have uniform irradiation intensity. 
Note that the cycle of the electron beam 5 that scans the slit opening 
portion 9a is preferably a cycle which is shorter than the moving time of 
the mask 18 by a distance equal to the arc width of the arcuated electron 
beam band irradiated onto the mask 18, and is a divisor of the moving 
time. With this cycle, exposure errors such as formation of non-exposed 
portions, double exposure, and the like can be prevented, and the wafer 32 
can be uniformly exposed. 
Since the projection device 3 comprises the first electron detector 22 for 
detecting secondary electrons or the like emitted by the mask 18 
irradiated with the electron beam 5, whether or not a circuit pattern is 
formed on a portion of the mask 18 irradiated with the electron beam 5 can 
be recognized by detecting such secondary electrons. Furthermore, since 
the electron beam illumination device 2 comprises the blanking electrode 
10 for controlling irradiation of the electron beam 5 onto the mask 18 as 
needed on the basis of the information supplied from the first electron 
detector 22, when the electron beam is irradiated onto a portion where no 
circuit pattern is formed of the mask 18, the blanking electrode 10 is 
activated to suppress wasteful irradiation of the electron beam 5, thereby 
preventing thermal strain of the mask 18. 
FIG. 14 is a perspective view showing the exposure route when the pattern 
image (exposure region) exposes the wafer. Four chips each having a size 
of 35 mm (X-direction).times.20 mm (Y-direction) are to be formed on the 
wafer 32 shown in FIG. 14. 
Before the beginning of exposure, the length (Y-size) of the arcuated 
pattern image on the wafer 32 is set at 5 mm. In this case, the number of 
exposure scans is four since 20 mm/5 mm=4. When exposure is started from 
the position of arc a in FIG. 14, the wafer stage 21 and mask stage 30 
(see FIG. 1) are synchronously moved in the X-direction, and when arc a 
has reached the right end of a chip region, the first scan is complete. 
Upon completion of the first scan, the wafer stage 30 and mask stage 21 
are moved in the Y-direction at step widths of 5 mm and 20 mm, 
respectively, thereby setting arc a at the second scan start position. 
Subsequently, the second scan is started by synchronously moving the wafer 
stage 30 and mask stage 20 in a direction opposite to that in the first 
scan. By repeating the above operation, exposure for one chip is completed 
after a total of four scans. When such exposure operation is repeated for 
four chips, exposure for one wafer is complete. 
In the above description, the step width of the wafer stage 21 is 5 mm, 
while that of the mask stage 30 is 20 mm, since the reduction 
magnification of the reduction electron optical system 20 (see FIG. 1) in 
the projection device 3 is 1/4. However, the reduction magnification of 
the reduction electron optical system 20 of this embodiment is not limited 
to 1/4, and can be arbitrarily set at about 1/4 to 1/2. Depending on this 
setup, the step width of the mask stage 21 varies. 
As described above, since the exposure apparatus 1 of this embodiment uses 
the above-mentioned electron beam illumination device 2 and exposes the 
wafer 32 by scanning the broadened exposure region, the number of exposure 
scans onto the wafer 32 can be greatly reduced and the exposure time can 
be shortened as compared to those of a conventional exposure apparatus 
using a single electron beam. 
Also, since the exposure apparatus 1 comprises the first laser 
interferometer 36 for detecting the position of the mask stage 21 and the 
second laser interferometer 41 for detecting the position of the wafer 
stage 30, as has been described above with the aid of FIG. 7, any 
positional deviations of the mask stage 21 and wafer stage 30 from their 
original positions can be detected. Furthermore, since the projection 
device 3 comprises the position correction deflector 27 for correcting the 
position of the pattern image to be projected onto the wafer 32, as shown 
in FIG. 1, even when the mask stage and wafer stage deviate from their 
original positions, the pattern image can be projected onto the original 
position by the position correction deflector 27. 
In a normal exposure process, the circuit pattern on the mask is 
overlay-exposed on the circuit pattern formed in advance on the wafer. In 
this case, the patterns must overlap each other with high accuracy. 
However, when the pattern is formed on the wafer, the wafer must undergo a 
film formation process. Since the wafer has expanded or shrunk after the 
film formation process, even when the projection pattern formed on the 
mask is projected onto the wafer at an original reduction factor, the 
patterns cannot overlap each other with high accuracy. For this reason, 
the control system 44 (see FIG. 7) acquires the expansion/shrinkage ratio 
of the wafer 32 in advance, and adjusts the reduction magnification of the 
reduction electron optical system 20 via the magnification control circuit 
39 (see FIG. 7) on the basis of the expansion/shrinkage ratio. At the same 
time, the control system 44 changes the setups of the wafer stage drive 
control circuit 41 so that the wafer stage 30 moves at a speed 
corresponding to the adjusted reduction magnification of the reduction 
electron optical system 20, and also changes the step width of the wafer 
stage 30. 
An embodiment of the manufacturing method of semiconductor devices using 
the above-mentioned exposure apparatus will be explained below. FIG. 15 
shows the flow in the manufacture of a microdevice (semiconductor chips 
such as ICs, LSIs, and the like, liquid crystal panels, thin film magnetic 
heads, micromachines, and the like). In step 1 (circuit design), the 
circuit design of a semiconductor device is made. In step 2 (manufacture 
mask), a mask formed with a designed circuit pattern is manufactured. In 
step 3 (fabricate wafer), a wafer is fabricated using materials such as 
silicon and the like. Step 4 (wafer process) is called a pre-process, and 
an actual circuit is formed by lithography using the prepared mask and 
wafer. The next step 5 (assembly) is called a post-process, in which 
semiconductor chips are assembled using the wafer obtained in step 4, and 
includes an assembly process (dicing, bonding), a packaging (encapsulating 
chips), and the like. In step 6 (inspection), inspections such as 
operation confirmation tests, durability tests, and the like of 
semiconductor devices assembled in step 5 are run. Semiconductor devices 
are completed via these processes, and are delivered (step 7). 
FIG. 16 is a flow chart showing the wafer process in detail. In step 11 
(oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an 
insulating film is formed on the wafer surface. In step 13 (electrode 
formation), electrodes are formed by deposition on the wafer. In step 14 
(ion implantation), ions are implanted into the wafer. In step 15 (resist 
process), a photosensitive agent is applied on the wafer. In step 16 
(exposure), the circuit pattern on the mask is printed on the wafer by 
exposure using the above-mentioned exposure apparatus. In step 17 
(development), the exposed wafer is developed. In step 18 (etching), a 
portion other than the developed resist image is removed by etching. In 
step 19 (remove resist), the resist film which has become unnecessary 
after the etching is removed. By repetitively executing these steps, 
multiple circuit patterns are formed on the wafer. When the manufacturing 
method of this embodiment is used, the exposure time of the circuit 
pattern formed on the mask onto the wafer can be shortened, and the 
productivity of semiconductor devices can be improved. 
As described above, since an electron beam illumination device of the 
present invention comprises an electron gun, a slit plate unit formed with 
an arcuated slit opening portion, and deflection means for scanning an 
electron beam along the slit opening portion, the electron beam 
irradiation region on the mask, and the exposure region on the wafer can 
be broadened, and the electron beam can be irradiated onto these regions 
at uniform irradiation intensity. 
As the speed of the electron beam that scans the slit opening portion makes 
the irradiation intensity of an arcuated electron beam band uniform in the 
entire arcuated electron beam band, thermal strain produced in the mask 
and wafer upon scanning of the electron beam can be eliminated. 
Furthermore, the slit plate unit has convex and concave blades, the 
arcuated edge portions of which oppose each other so as to form a slit 
opening portion. Furthermore, a drive unit for adjusting the spacing 
between the blades is attached to at least one of the blades, thus 
adjusting the arc width of the arcuated electron beam band. By controlling 
the arc width, the irradiation intensity of the arcuated electron beam 
band can be adjusted, and the resolution of the pattern image can also be 
adjusted. 
In addition, since the slit plate unit has a light-shielding blade for 
adjusting the length of the slit opening portion defined by the convex and 
concave blades, the arc length of the arcuated electron beam band can be 
adjusted, and can be optimally set in correspondence with the size of the 
region to be exposed. 
Furthermore, since the center of rotation or reciprocal movement of the 
electron beam that scans the slit opening portion is shifted from the 
center of the slit opening portion along the central axis of the slit 
opening portion by the deflection means, the arc width of the arcuated 
electron beam band can be reduced, thus adjusting the arc width of the 
arcuated electron beam band. 
Since an exposure apparatus of the present invention uses the electron beam 
illumination device of the present invention as an illumination device for 
projecting a circuit pattern onto a wafer, the wafer can be exposed by 
scanning the broadened exposure region. Hence, the number of exposure 
scans onto the wafer can be reduced, and the exposure time can be 
shortened. 
Since the scanning cycle of the electron beam onto the slit opening portion 
is set at a cycle which is shorter than the moving time of the mask by a 
distance equal to the width of the arcuated electron beam band projected 
onto the mask, and is a divisor of the moving time, exposure errors such 
as formation of non-exposed portions, double exposure, and the like of the 
wafer can be prevented. 
The exposure apparatus comprises an electron detection unit for detecting 
electrons emitted by the mask irradiated with the electron beam, and a 
blanking electrode unit that controls irradiation of the electron beam 
onto the mask on the basis of information obtained from the electron 
detection unit. Therefore, wasteful irradiation of the electron beam can 
be suppressed, and thermal strain of the mask can be prevented. 
Moreover, since the exposure apparatus comprises mask and wafer reference 
mark detection means, the mask and wafer can be accurately aligned to the 
beam axis of the electron beam illumination device. 
The present invention is not limited to the above embodiment and various 
changes and modifications can be made within the spirit and scope of the 
present invention. Therefore, to appraise the public of the scope of the 
present invention, the following claims are made.