JP2001237176A - Electron beam writing method and apparatus - Google Patents

Abstract

(57) [Summary] (Modified) [PROBLEMS] To provide an electron beam writing method and apparatus capable of enabling more efficient operation of the collective figure irradiation method. And improve productivity. An electron beam writing apparatus that performs pattern writing using at least three masks has one rectangular opening on a first mask, a plurality of diagrammatic openings on a second mask, and a third opening. One rectangular opening is provided on the mask 103, and the maximum irradiation area of the beam irradiated on the sample 110 is defined by the overlapping state of the first mask opening image and the rectangular opening on the third mask. The configuration is such that the shape of the upper drawing opening 301 defines the irradiation pattern shape of the beam irradiated on the sample 110. The graphic aperture on the second mask can be arranged close to the optical axis, so that the beam deflection distance for selecting the graphic aperture can be shortened, and a high-speed graphic selection operation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electron beam writing method and an electron beam writing apparatus, and more particularly to an electron beam writing method and an electron beam writing apparatus suitable for high-speed writing.

[0002]

2. Description of the Related Art In recent years, in order to increase the speed of an electron beam lithography apparatus, a batch pattern irradiation method for forming an electron beam having a complicated shape has been developed. In this method, for example, Sakamoto et al., Journal of Vacuum Science and Technology, B11 (1993), p.
As described on page 61, using two masks, the shape of the electron beam is determined by a combination of a fixed rectangular opening and a diagrammatic opening.

The idea of forming a pattern using three or more masks is disclosed in Japanese Patent Application Laid-Open Nos. 4-100208, 4-360516, and 1
It is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-40485.

[0004]

In order to apply these collective figure irradiation methods to an actual LSI, especially to a logic LSI, a figure opening of at least 100 figures is required. Moreover, it is important to select those figures at high speed.
However, the above method cannot sufficiently cope with an increase in beam deflection amount and an increase in off-axis aberration for selecting a figure with an increase in the number of figures.

Accordingly, it is an object of the present invention to provide an electron beam lithography capable of alleviating problems such as an increase in the amount of beam deflection and an increase in off-axis aberrations due to an increase in the number of figures, and enabling high-speed lithography. It is an object of the present invention to provide a method and an electron beam writing apparatus suitable for implementing the method.

[0006]

SUMMARY OF THE INVENTION In order to alleviate the above-mentioned problems in the prior art, the present invention makes the above-described electron beam drawing method and apparatus using three masks more practical and effective. Improvements have been made to

That is, according to the present invention, at least 3
An electron beam writing apparatus having two masks, comprising:
The mask and the third mask are each provided with a rectangular opening, and the second mask is provided with a plurality of diagrammatic openings. The rectangular opening image of the first mask or its virtual rectangular opening image and the rectangular opening of the third mask are provided. The maximum area of the electron beam pattern projected on the sample is defined by the degree of overlap, and the shape of the electron beam figure projected on the sample is defined by the shape of the diagrammatic opening on the second mask. An electron beam drawing apparatus is provided.

In the electron beam lithography system having the above three masks, one rectangular opening is provided in each of the first and third masks, and a plurality of diagrammatic openings are provided in the second mask. Then, the rectangular aperture image of the first mask or its virtual rectangular aperture image (the virtual aperture image referred to here is the second aperture image).
This is the opening image of the first mask formed on the third mask when there is no mask) and the maximum irradiation area of the electron beam irradiated on the sample by the overlapping state of the rectangular opening on the third mask. Stipulate. The shape of the electron beam pattern irradiated on the sample is determined by the shape of the illustrated opening on the second mask. Further, the maximum irradiation area of the beam irradiated on the sample is defined by a figure formed by an opening image of the first mask or a virtual opening image of the first mask and an opening of the third mask. When defining the shape of the electron beam pattern irradiated on the sample by the shape of the diagrammatic opening on the mask, the plurality of diagrammatic openings formed on the second mask have a plurality of different sizes, The plurality of diagrammatic openings are arranged at intervals according to the size. Further, in order to determine the maximum irradiation area efficiently, two sides of the maximum area projected on the sample at the opening on the second mask by the opening on the first mask are set to the remaining two sides by the opening on the third mask. What is necessary is just to define an edge. It is also effective to make the opening on the third mask larger than the diagrammatic opening image of the second mask so as not to inadvertently reduce the maximum irradiation area.
In these methods, a pseudo-variable rectangular method can be realized by providing the figure-shaped opening on the second mask with a plurality of one rectangular openings.

As a specific method, an opening on the second mask is selected by a deflector above the second mask, and a third opening is selected according to the size of the opening used by the deflector below the second mask. By changing the position of the second mask image on the mask, it is proposed to block, on the third mask, the electron beam portion transmitted through the opening near the opening to be used on the second mask. Further, when an opening on the second mask is selected by a deflector above the second mask, and a second mask image is returned onto the third mask opening on the optical axis by a return deflector above the third mask. When changing the position of the second mask image on the third mask in accordance with the size of the pattern used for writing on the sample,
It is also effective to use the above deflectors together. Thereby, the column structure can be simplified.

In order to make these possible, it is necessary to incorporate a memory storing data corresponding to the size of each opening in the data control system. Further, the deflector between the second mask and the third mask is preferably controlled using the data. Further, as the optical system, it is desirable that both the beam shape forming function and the reduction function be achieved by reducing and irradiating the opening on the second mask onto the third mask. The reduction ratio is set to 1 / 1.5 to 1/4 to enable both functions. The reduction ratio of the second mask on the sample is 1 /
20 is desirable. This is because the smaller the deflection of the electron beam on the second mask, the faster the pattern can be selected.
This is because it is important for improving the throughput. Considering the processing accuracy of the figure selecting deflector and the analog output that can be applied to the deflector, a reduction ratio of 1/20 or less is required. Further, by supplying a high voltage and a low voltage to the deflector used for selecting an opening on the second mask and swinging back onto the third mask by floating coupling, the electron beam can be controlled more efficiently. Further, in order to properly maintain the imaging relationship of the three masks and the imaging relationship of the crossover, the first mask opening image is placed on the second mask using the at least two lenses, and the second mask opening image is placed on the third mask. Forming on a mask is one means. As an optical condition, when the first mask aperture image is formed on the second mask, it is preferable that an electron beam is incident on the second mask almost vertically by a lens immediately above the second mask.

FIG. 1 shows a basic configuration of a drawing apparatus according to the present invention.
This will be described with reference to FIG. In FIG. 1, the electron beam emitted from the electron source 100 directly irradiates the first mask 101 as indicated by a crossover orbit 115. The first mask opening image is formed by first and second two transfer lenses 104 and 10.
5 is projected onto the second mask 102. The projection position of the first mask aperture image on the second mask 102 is deflection controlled by the first deflector 113. The electron beam is further imaged on the third mask 103 by the third and fourth transfer lenses 106 and 107 at the subsequent stage. The image forming position on the third mask 103 is also determined by the second deflector 11 for selecting a figure.
4 controls the deflection. The electron beam that has passed through the third mask 103 is transferred to the sample 1 held on the stage 111 by the first reduction lens 108 and the first objective lens 109.
10 is projected. A deflector is usually installed in the objective lens and determines the position of the electron beam on the sample. Note that FIG. 1 also shows the mask image trajectory 116 together with the crossover trajectory 115.

The structures of the first, second and third masks are shown in FIGS. 2, 3 and 4, respectively. One rectangular opening 201 is provided on the first mask 101. In contrast,
On the second mask 102, a drawing opening 301 having a pattern shape of a fine element is arranged in addition to the rectangular opening. Here, the figure-shaped aperture refers to an aggregate of a group of beam-passing apertures in a region surrounded by the rectangular outline in FIG. The electron beam is irradiated on the sample 110 on a per aperture basis. A plurality of diagrammatic openings are arranged on the second mask 102, and the sizes of the respective openings are different as can be seen in the figure. This is apparent from the fact that the size of the square drawn in the figure as a mark of the area occupied by each unit opening differs. The area occupied by the opening is not limited to a square, but may be vertically long, horizontally long, or the like. One of the features of the present invention lies in the arrangement of the figures on the second mask. By arranging the arrangement pitch in accordance with the size of each unit opening, the arrangement of the figures is high and the arrangement density is high. Is possible. Although only one rectangular opening 401 is provided at the center of the third mask 103, this rectangular opening 401 is larger than any unit opening on the second mask 102 and passes through the second mask 102. The entire electron beam can pass through as it is. FIG. 4 shows the second mask opening image 403 and the first mask opening image 403.
A virtual image 404 of the mask opening is also illustrated.

An opening image 302 of the first mask is also drawn on the second mask 102 (FIG. 3). This first mask opening image 3
02 on the second mask 102 is the first deflector 1
13, the first mask opening image is larger than some of the figure-shaped openings, and in some cases, irradiates a plurality of openings as shown in FIG. 3. The electron beam transmitted through the second mask 102 is returned to the column axis by the second deflector 114. This rewind is very important,
If this is not done, the electron beam will always pass off-axis of the reduction lens 108 and the objective lens 109, causing large off-axis aberrations. By turning back on the axis, the beam always passes near the lens axis, so that high-precision drawing is possible. Therefore, in the present invention,
It is only necessary to provide one opening on the third mask 103, and when irradiating an electron beam with another opening provided on the third mask 103, it is necessary to prepare for the deterioration of the drawing accuracy. When the electron beam passing through the second mask 102 is returned to the central portion of the third mask 103, by adjusting the amount of the return, as shown in FIG.
By adjusting the relative position of the second mask image with respect to the rectangular opening 401 on the third mask, an image portion other than the desired second mask opening image is blocked on the third mask 103. FIG. 4 also shows a virtual image of the first mask (a first mask opening image formed on the third mask when there is no second mask).

As described above, according to the present invention, the maximum irradiation area of the electron beam on the sample is determined by the overlapping portion of the first mask virtual image and the third mask opening, and the diagrammatic opening on the second mask is determined. This determines the shape of the drawing figure formed within the maximum irradiation area.
Two sides of the maximum irradiation area are formed by two sides of the first mask opening, and the remaining two sides are formed by two sides of the third mask opening. This maximum irradiation area can be adjusted by using the second deflector 114, and the first mask opening 201 can be adjusted.
(That is, the first mask virtual image) and the third mask opening 40
A rectangular maximum irradiation area of any size can be used as long as the size of 1 permits. This is a great merit of combining the first mask and the third mask. This makes it possible to optimally arrange the openings on the second mask in accordance with the size of the figure-shaped openings, and to reduce the deflection distance on the second mask. This results in a reduction in the deflection aberration, and the reduction in the aberration enables an increase in the number of figures that can be arranged on the second mask and a high-speed figure selection. Further, since only the opening at the center of the third mask is used as the third mask opening for defining the maximum irradiation area, the amount of off-axis of the electron beam can be suppressed, and the optical aberration can be suppressed to a small value. A great advantage.
The size of the second mask image on the third mask is set so that the size of the second mask image on the third mask is equal to the size of the first mask image or the third mask opening. Desirably, it is smaller than three mask openings. Furthermore, if the size of each opening is set so as to satisfy the relationship of the opening of the third mask> the virtual opening image of the first mask> the opening image of the second mask, the first mask image and the third mask opening can be obtained. It is possible to make a figure-shaped opening that does not need to be cut. For the variable rectangular shaping, the rectangular opening on the second mask may be enlarged to form a variable rectangular beam from the first mask and the third mask. Seems to be advantageous.

The above-described electron optical system of the three-stage mask uses an electromagnetic lens having a two-stage configuration in order to simultaneously satisfy two orbits of a crossover image and a mask image.
Here, the second mask image is reduced and transferred onto the third mask. Since the three-stage mask configuration makes the column longer and is less susceptible to disturbances such as vibrations, it is particularly important to provide a reduction function to shorten the reduction lens unit in order to ensure accuracy. In the present invention, it is important to suppress the Coulomb effect between the second mask and the surface of the sample. From this viewpoint as well, a single reduction lens reduces the beam irradiation on the third mask so that the single reduction lens can be configured in one stage. It is effective to do it. Since the third mask does not have a figure-shaped opening, the load on the opening processing is relatively small, and the reduction ratio on the sample may be small. Therefore, the above-described configuration is possible. Further, as can be seen from the crossover trajectory 115 in FIG. 1, the electron beam is incident on the second mask almost perpendicularly. Since oblique incidence causes a positional shift due to a height error of the mask, such vertical incidence is desirable.
A high voltage and a low voltage are floating-coupled to the deflector, and the control of the narrow area and the overlap between the first mask and the third mask is performed by low voltage driving, and selection of a figure far away from the axis is performed by high voltage. It is performed by driving. Thereby, space can be used efficiently. The data control system 120 shown in FIG. 1 has a built-in memory for storing information corresponding to the size of the figure-shaped opening on the second mask. Based on the stored size information, the analog circuit 121 is operated. Via the second deflector 1
The deflection voltage applied to 14 is controlled.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIG. 5 shows a schematic configuration of an electron beam writing apparatus according to a first embodiment of the present invention. In addition,
This drawing mainly shows the electron optical system in the system configuration of the whole drawing apparatus.

In FIG. 5, the electron beam emitted from the electron source 100 is once imaged by the condenser lens 501 as shown by the crossover trajectory 115,
The first mask 101 is irradiated. By doing this,
The first mask 101 can be irradiated with a higher beam current density. In the present embodiment, high-speed figure selection on the second mask 102 is performed by reducing the reduction ratio of the first mask image. Therefore, a high beam current density is obtained on the sample 110 to improve the throughput. Therefore, it is important to increase the current density of the first mask irradiation using the condenser lens 501.

Although a method of using a reduction optical system between the first mask 101 and the second mask 102 is conceivable, reducing the distance between the first deflector 113 and the second mask 102 reduces the deflection sensitivity. Lowering the speed will hinder high-speed figure selection. Therefore, the first mask 101 and the first deflector 113
When the crossover imaging system is taken into consideration, the design of the reduction optical system becomes difficult.

In the present embodiment, the condenser lens 501 is designed at approximately the same magnification. In order to increase the current density on the mask, it is preferable to use the same magnification or enlargement system (preferably three times or less in consideration of the length). FIG.
Reference numeral 116 denotes a mask image trajectory.

On the first mask 101, as shown in FIG. 6, a rectangular (square) opening 201 is provided.
The side is 75 μm. The rectangular aperture image of the first mask is the first
Then, the light is projected onto the second mask 102 at the same magnification by the second two transfer lenses 104 and 105. Second mask 1
As shown in FIG. 7, a plurality of diagrammatic openings 301 having various shapes and dimensions are arranged on the surface 02. 1st, 2nd
A first deflector 113 is provided between the masks, whereby the opening image 302 of the first mask is deflected and scanned, and can be selectively superimposed and projected on a desired diagrammatic opening on the second mask. . Since high-speed deflection performance is required for the first deflector 113, an electrostatic deflector was used.

FIG. 11 shows the trajectory of the electron beam when a figure is selected on the second mask 102. The electron beam (first mask image) is incident on the second mask 102 almost perpendicularly (parallel to the column axis 1101) as shown by the trajectory 1100.
In FIG. 11, the opening angle of the electron beam is exaggerated.

In FIG. 7, only the diagrammatic opening 301 on the second mask 102 is shown near the center of the mask. Although the vertical direction of each figure-shaped opening is the same length, the horizontal direction is set to various lengths. Each figure-shaped opening is arranged so as to change the interval according to its size, and is densely arranged as close as possible to the center of the mask. In FIG. 7, they are arranged at irregular intervals at intervals substantially equal to the size of the openings. On the other hand, if these figure-shaped openings are arranged at regular intervals as in the related art, as shown in FIG. 12, the area occupied by the group of equally-spaced figure-shaped openings 1201 increases by 20%.

The position of the first mask opening image 302 on the second mask 102 is controlled by the first deflector 113. In the present embodiment, about 120 figure-shaped openings are arranged within a range of 700 μm square in the central portion on the second mask 102, and a maximum deflection voltage of 30 V is applied to the first deflector (electrostatic deflector) 113. By doing so, all figures can be selected. If the deflection voltage is 30 V, the setting is made in about 100 nsec. This is a value equivalent to the shot cycle of a normal drawing apparatus, and the figure selection time does not become a major factor in decreasing the throughput. In a regular equispaced arrangement, the number of figures that can be arranged in the above range is limited to 80. The number of main figures in the logic LSI is about 100, and this embodiment can sufficiently cope with this, but cannot be coped with by regular regular arrangement. However, in the unequally-spaced arrangement of the figure-shaped openings according to the present embodiment, the second mask 1
Since some of the figure-shaped openings on 02 are small, there arises a problem that adjacent figure-shaped openings are partially irradiated as shown in FIG. A solution to this problem will be described later.

The electron beam that has passed through the illustrated opening of the second mask 102 is imaged on the third mask 103 by the third and fourth transfer lenses 106 and 107 at the subsequent stage. At that time, the electron beam is returned to the column axis by the second deflector 114. If this swingback is not performed, aberration caused by the electron beam passing off the axis of the fourth transfer lens 107 or the first reduction lens 108 deteriorates the drawing accuracy. In the configuration of the present embodiment, the resolution is degraded by 0.1 μm at the maximum when the swingback is not performed. In particular, aberration is increased because the reduction lens 108 usually has a small diameter. Therefore, the third mask 10
Only one rectangle on 3 is used. The transfer onto the third mask 103 is performed at a reduction ratio of 1/2. As mentioned above,
The use of three masks increases the column length. Therefore, it is desirable to use as few reduction lenses as possible. Therefore, it is effective to reduce the size of the second mask, which actually determines the pattern shape, even in the transfer portion at the subsequent stage. As will be described later, a part of the shape of the variable rectangular beam is determined by the edge of the opening on the third mask 103. Since this opening is only a rectangular opening, a small opening can be formed with high accuracy. Therefore, the reduction ratio by the reduction lens may be small. In some cases, the third mask 103 may be formed by superposing a plurality of masks each having a linear edge portion. Of course, the transfer onto the third mask may be at the same magnification. FIG. 9 shows the configuration of the third mask. A large rectangular opening 401 is arranged near the column axis. FIG. 9 also shows a second mask opening image 403 and a virtual image 404 of the first mask opening. As can be seen from the drawing, only the second mask opening image portion 403 that has passed through the region surrounded by the two sides of the first mask opening virtual image 404 and the two sides of the third mask opening 401 is projected on the sample to be drawn. You. For this reason, the image portion of the adjacent opening on the second mask is excluded from the projection on the sample to be drawn. FIG. 8 shows a third example in which the uppermost figure-shaped opening in FIG. 7 is selected.
This shows a state of projection on the mask 103. Second
Since this figure-shaped opening on the mask 102 is large, the neighboring openings on the second mask will not be irradiated at the same time.
01 is transmitted. As shown, the third mask opening 4
When 01 is larger than the second mask opening image 803 and the first mask virtual image 404, it is not necessary to use the two sides of the third mask opening for the maximum irradiation area of all diagrammatic openings.

FIG. 10 shows a case where a variable rectangular beam is formed. In this figure, a rectangular figure of any size is formed from the rectangular opening image 1003 of the second mask and the rectangular opening 401 of the third mask. This combination is best from the viewpoint of the Coulomb effect, but it can also be formed by a combination of rectangular openings on any two masks. However, in order to variably form a rectangular figure with the first mask and the second mask, the second mask is required.
It is necessary to provide a region where no opening exists around the rectangular opening on the mask.

Other advantages of being able to change the maximum irradiation area while minimizing axis deviation are as follows. For example, the required maximum irradiation area is different for LSIs with different design rules (generally, an LSI with a looser rule has a larger figure-shaped opening), but in the present invention, it can be dealt with only by replacing the second mask or the group of openings on the second mask. . In the conventional method, it is necessary to exchange another mask. Therefore, in the present invention, the exchange time can be shortened and the apparatus configuration can be simplified.

In this embodiment, a 5 μm-thick silicon mask is used in order to increase the workability of the second mask. Since an electron beam of 50 KV is used, since the thickness is smaller than the cutoff distance of electrons, drawing is performed by using a scattering contrast method. For that purpose, a technique of setting the maximum irradiation area on the third mask to zero is also used for blanking. This blanking method on the third mask is important for utilizing the present invention.

In the analog circuit 121 for controlling the second deflector 114, data corresponding to the size of the figure-shaped opening built in the data control system 120 (in this embodiment, the size is stored in the memory 122). ) Is sent, and the deflection amount of the second deflector is adjusted accordingly. The size mentioned here is, in other words, the maximum irradiation area. If the size is limited to some, data may be managed by a number corresponding to the size. This allows control of the maximum irradiation area. The data control system 120 also stores information relating to the position of the figure-shaped aperture on the second mask, and the second deflector 114 is shared by the function of returning to the column axis and the function of the deflector. . The first deflector 11
If a high voltage analog circuit is floating-coupled to the third deflector 114 and the second deflector 114, it is possible to increase the number of selected figures although the speed is slightly reduced. For example, if a deflection voltage of 100 V is used, 1,000 figures can be selected.

The electron beam that has passed through the third mask 103 is reduced to 1/6 by the reduction lens 108, and projected onto the surface of the sample 110 on the stage 111 while the projection position on the sample is controlled by the objective lens 109. Is done.

The drawing apparatus according to the present embodiment was applied to direct drawing on a wafer to draw a wiring layer of a 0.2 μm CMOS logic LSI. The size of the figure opening on the wafer is 5
μm × 2.5 μm to 5 μm × 5 μm. As a result, it was possible to select 120 figures at high speed, and the throughput of 2 sheets / hour was improved to 3 sheets / hour, thereby contributing to an improvement in productivity. The present drawing apparatus is also applicable to reticle drawing. When drawing on a reticle, the LSI pattern becomes large. For example, with a 4X reticle, about 1600 figure-shaped openings are used or 1
This can be dealt with by using a figure-shaped opening having a six-fold opening area or by reducing the reduction ratio of the optical system by １ ／.

Embodiment 2 FIG. 13 shows a schematic configuration of an electron optical system in an electron beam writing apparatus according to a second embodiment of the present invention. In the second embodiment, writing is performed using the optical system shown in FIG. 13 and the mask configuration shown in FIGS. 14, 15 and 16. Here, fine rectangular openings 301 of various sizes are arranged on the second mask 102. That is, here, each rectangular opening 301 corresponds to the figure-shaped opening. In FIG. 15, the vertically long patterns are arranged horizontally and the horizontally long patterns are arranged vertically, so that more patterns can be efficiently arranged in a small area. Further, as shown in FIG. 25 and FIG. 26, even if the pattern is vertically long, if it is a pattern that is short vertically, it can be packed vertically and used. If the pattern is used, it can be packed horizontally, but in this embodiment, in order to simplify the pattern arrangement, a mask configuration in which only one direction is compressed is used. Then, the maximum irradiation area is determined by the first mask opening and the third mask opening, and only one opening image 403 passing through one rectangular opening on the second mask is projected on the sample (FIG. 16). Reference numeral 130 in FIG. 13 denotes a scattering stop for removing a scattered beam.

In the present embodiment, 40
It is possible to provide a rectangular opening of 0 pattern, and a pseudo variable rectangular beam can be formed. As described above, the use of the built-in opening improves the dimensional accuracy of the drawn figure.

In this embodiment, a reticle is drawn.
The rectangular opening on the second mask 102 is 0.2 mm above the wafer.
It is formed for μm wiring (for a 0.8 μm figure on a reticle). One side is 0.8 μm above the sample, and the other side is 0.008 μm in pitch from 0.008 μm to 1.
Up to 6 μm and 2 μm are prepared, and there are a total of about 400 rectangles in the XY directions. The reduction ratio from the second mask 102 onto the sample 110 is 1 / 12.5. In the present embodiment, the size is limited to 0.8 μm rectangle, but the dimensional accuracy of the drawn figure is improved, and the in-plane non-uniformity which was conventionally 20 nm is reduced by 1
It was able to be suppressed to 0 nm. Since the variable rectangle method is simulated by the collective figure irradiation method, extremely high speed is required for selecting a figure, but the apparatus configuration of the present invention is also effective.

Since the mask shown in FIG. 15 is limited to a rectangular figure having a side of 0.8 μm, the LS of the rule having different dimensions is used.
When drawing I, it is necessary to replace the second mask or the group of rectangular openings on the second mask. Data control system 12
Information regarding the position and size of each rectangular opening is stored in the memory 122 in the area 0, and the data control system 120 controls the second deflector 114 based on the information.

FIGS. 17 and 18 show examples of the configuration of the mask when the dimensions are changed in both the vertical and horizontal directions. If the mask of this configuration example is used, the pitch of the dimensional change becomes large, but it is possible to cope with the formation of rectangular figures of various vertical and horizontal widths. In these examples, those not registered as the figure-shaped openings are formed by the conventional variable rectangle method, and two out of three masks are used.
A rectangular figure is formed by the openings of the two masks. Also in this embodiment, since the electron beam is always returned to the vicinity of the column axis, the aberration of all rectangular beams can be reduced. Also, if the number of figure-shaped openings is large,
An opening for OPC (Optical Proximity Correction) drawing can also be provided. As a result of manufacturing the reticle according to the present invention, it was possible to reduce the non-uniformity of dimensions within the reticle, which was as large as 20 nm in the ordinary variable rectangle method, to 10 nm.

<Embodiment 3> FIG. 19 shows a schematic configuration of an electron optical system in an electron beam writing apparatus according to a third embodiment of the present invention. In the second embodiment, writing was performed using the optical system shown in FIG. 19 and the mask configuration shown in FIGS. 20, 21 and 22. In the present embodiment, the first mask 101 is directly irradiated by the emission beam itself from the electron source 100, and the first mask image is reduced to half, and
2 is projected. The reason why the reduction system is provided between the first mask and the second mask is to facilitate opening processing of the first mask. On the first mask, a 2 μm square (reduction ratio 1 /
25) and a rectangular aperture 2001 on the sample within 5 μm square
A mesh opening 2002 provided with a mesh having a width of 0 nm
Is provided (FIG. 20). The number of electrons passing through this mesh opening is reduced to 1/4. A 10 nm mesh on the sample is not resolved on the sample because it is smaller than the device resolution of 50 nm. Further, since the electron beam irradiates the two openings simultaneously, the electron beam transmitted through the first mask 101 is composed of two rectangular beams having substantially different current densities. The projection positions of these two rectangular beams on the second mask 102 are controlled by changing the deflection voltage applied to the second deflector 114 based on the data from the memory 123 storing the rectangular aperture data.

An object of the present embodiment is to form a figure-shaped beam using a rectangular beam having a lower current density and to form a variable rectangle using a rectangular beam having a higher current density. It is efficient to form the figure-shaped beam with an electron beam image of a certain size, but the current density must be limited due to the influence of the Coulomb effect. On the other hand, a variable rectangular beam generally has a smaller electron beam size when drawing a fine pattern than a diagrammatic beam, and can be drawn with a higher current density. . Therefore, the ability to change the beam current density between the two greatly contributes to an improvement in throughput.

FIGS. 21 and 22 show the projection state of the electron beam on the second and third masks when forming the figure-shaped beam, and FIGS. 23 and 24 show the second and third states when forming the variable rectangular beam. The projection state of the electron beam on the third mask is shown.
From these figures, it can be seen that an electron beam having a desired shape can be obtained by removing each unnecessary electron beam.

Using the drawing apparatus of this embodiment, 0.2 μm C
As a result of drawing a MOS logic pattern, it was possible to improve the throughput of 3 wafers / hour when the current density was constant at 4 wafers / hour.

[0041]

As described above, according to the present invention, more efficient operation of the collective figure irradiation method can be achieved, and thereby, semiconductor integrated circuits and microstructured elements can be manufactured with high productivity. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration example of an electron optical system of an electron beam writing apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration example of a first mask used in a writing apparatus according to the present invention.

FIG. 3 is a diagram showing a configuration example of a first mask used in a writing apparatus according to the present invention.

FIG. 4 is a diagram showing a configuration example of a first mask used in a writing apparatus according to the present invention.

FIG. 5 is a diagram showing a configuration of an electron optical system of the electron beam writing apparatus according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a configuration example of a first mask used in the first embodiment.

FIG. 7 is a diagram showing a configuration example of a second mask used in the first embodiment.

FIG. 8 is a diagram showing a configuration example of a third mask used in the first embodiment.

FIG. 9 is a diagram showing a second beam forming example in the first embodiment.

FIG. 10 is a diagram showing a third example of beam formation in the first embodiment.

FIG. 11 is a diagram showing an electron optical system when a figure is selected in the first embodiment.

FIG. 12 is a diagram showing a configuration example of a second mask in the case where the figure-shaped openings are arranged at equal intervals.

FIG. 13 is a diagram showing a configuration of an electron optical system of an electron beam writing apparatus according to a second embodiment of the present invention.

FIG. 14 is a diagram showing a configuration example of a first mask used in the second embodiment.

FIG. 15 is a diagram showing a configuration example of a second mask used in the second embodiment.

FIG. 16 is a diagram showing a configuration example of a third mask used in the second embodiment.

FIG. 17 is a diagram showing another configuration example of the second mask used in the second embodiment.

FIG. 18 is a diagram showing another configuration example of the third mask used in the second embodiment.

FIG. 19 is a diagram showing a configuration of an electron optical system of an electron beam writing apparatus according to a third embodiment of the present invention.

FIG. 20 is a diagram showing a configuration example of a first mask used in the third embodiment.

FIG. 21 is a diagram showing a configuration example of a second mask used in the third embodiment.

FIG. 22 is a diagram showing a configuration example of a third mask used in the third embodiment.

FIG. 23 is a diagram showing another configuration example of the second mask used in the third embodiment.

FIG. 24 is a diagram showing another configuration example of the third mask used in the third embodiment.

FIG. 25 is a diagram showing a modified configuration example of the second mask in the second embodiment.

FIG. 26 is a view showing an example of use of the second mask shown in FIG. 25;

[Explanation of symbols]

100: electron source, 101: first
Mask, 102: Second mask, 10
3: Third mask, 104: First transfer lens,
105: second transfer lens, 106: third transfer lens, 107: fourth transfer lens, 108:
1st reduction lens, 109: 1st objective lens, 110: sample, 111:
Stage, 113: first deflector, 11
4: second deflector, 115: crossover orbit,
116: mask image orbit, 120: data control system, 121: analog circuit, 122:
Aperture area memory, 123: rectangular aperture memory, 130: scattering aperture, 201:
Rectangular opening, 301: figure-shaped opening, 30
2: first mask image, 401: rectangular opening,
402: second mask image, 404: first mask virtual image.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Someda 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 2H097 CA16 JA02 LA10 5C034 BB05 5F056 AA04 AA06 AA22 CB11 EA04

Claims (5)

[Claims] An electron beam writing apparatus having at least three masks, wherein a first mask and a third mask are provided with rectangular openings, respectively, and a second mask is provided with a plurality of drawing openings. The maximum area of the electron beam pattern projected on the sample is defined by the overlapping state of the rectangular opening image of the mask or the virtual rectangular opening image thereof and the rectangular opening of the third mask. An electron beam drawing apparatus characterized in that the shape of an electron beam pattern projected on a sample is defined by the shape. 2. An electron beam writing apparatus having at least three masks, wherein one opening is provided in each of a first mask and a third mask, and a plurality of diagrammatic openings are provided in a second mask. The maximum area of the electron beam pattern projected on the sample is defined by the degree of overlap between the opening image of one mask or its virtual opening image and the opening of the third mask, and is determined by the shape of the diagrammatic opening on the second mask. The configuration is such that the shape of the electron beam pattern projected on the sample is defined, and the plurality of diagrammatic openings on the second mask are arranged closely at intervals according to their sizes. An electron beam drawing apparatus characterized by the above-mentioned. 3. An electron beam writing apparatus having at least three masks, wherein one opening is provided in each of the first mask and the third mask, and a plurality of diagrammatic openings are provided in the second mask. The two sides of the maximum area projected on the sample in the aperture image on the second mask are defined by the opening of the one mask, and the remaining two sides of the maximum area projected on the sample are defined by the opening on the third mask. An electron beam writing apparatus characterized in that it is configured to be operated. 4. An electron beam writing apparatus having at least three masks, wherein one opening is provided in each of the first mask and the third mask, and a plurality of drawing-shaped openings are provided in the second mask. By changing the position of the opening image of the first mask on the second mask with the first deflector provided above the second mask, a figure-shaped opening to be used for drawing is selected and provided above the third mask. By changing the position of the opening image of the second mask on the third mask in accordance with the size of the drawing opening used in the second deflector, the vicinity of the drawing opening used on the second mask An electron beam drawing apparatus configured to block an electron beam passing through the opening on the third mask. 5. An electron beam drawing method for drawing a figure by projecting an electron beam from an electron source through a first, a second and a third mask in sequence and projecting the pattern on a sample. One rectangular opening is provided in each of the mask and the third mask, and a plurality of diagrammatic openings are provided in the second mask. The image of the rectangular opening on the first mask or a virtual image thereof is The maximum area of the electron beam figure projected on the sample is defined by the degree of overlap with the rectangular opening on the third mask, and the figure of the electron beam figure projected on the sample is determined by the shape of the figure-shaped opening on the second mask. An electron beam writing method characterized in that the shape of the electron beam is defined.