JP3324749B2 - Electron beam drawing method and electron beam drawing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam lithography technique used in the manufacture of semiconductor integrated circuits and the like. The present invention relates to an electron beam lithography method and an electron beam lithography apparatus capable of high-speed image writing.

[0002]

2. Description of the Related Art In recent years, miniaturization and integration of semiconductor integrated circuits have been advanced, and lithography apparatuses for realizing the fine processing have been improved in accuracy. However, the processing method is approaching the wavelength of the light source for light exposure, and the lithography technique is approaching its limit. Therefore, in order to promote further miniaturization and higher precision, an electron beam lithography apparatus, which is a kind of charged particle beam apparatus, has been used instead of the lithography technique. In order to increase the speed of an electron beam lithography apparatus, a collective pattern irradiation method for forming a complicated shape electron beam by combining masks of various shapes and irradiating them collectively with an electron beam has been developed. This technique includes:
For example, Sakamoto et al. Published the Journal of Vacuum Science and Technology (J.Vac.Sci.Techno.
l.), B11 (1993), pp. 2357 to 2361, an electron beam shape is determined by a combination of a fixed rectangular aperture and a graphic aperture using two masks. Fortagun et al., Microelectronic Engineering, 27 (1995)
As described on pages 151 to 154, there is a type in which a rectangle rotated by 45 degrees is prepared for one mask so that a triangular beam can be formed.

[0003]

However, the above-mentioned conventional method cannot respond to various recent demands. For example, as the number of required figures increases, the amount of electron beam deflection for figure selection increases. As a result, off-axis aberration increases. Therefore, it is an important issue how to select a large number of graphic patterns while reducing the amount of off-axis. As the number of figures further increases, it is necessary to consider a figure arrangement for drawing them with higher accuracy. Also, when the size of the fine pattern becomes smaller,
Processing of the mask becomes difficult. It is necessary to devise ways to reduce this effect.

[0004] To alleviate this problem, a method using three masks has been proposed by Koyama (Japanese Patent Application Laid-Open No. Sho 6 (1994)).
No. 3-114125, "Charged beam exposure apparatus"). The proposal here uses three masks, the first of which is a beam limiting mask and the second and third are beam shaping masks, of which The third mask had only one opening, and was insufficient to draw a large number of graphic patterns on the sample with high accuracy. SUMMARY OF THE INVENTION It is an object of the present invention to provide an electron beam lithography method and an electron beam lithography apparatus which can solve the above-mentioned problem and can draw a large number of figures on a sample with higher accuracy.

[0005]

According to the present invention, in order to achieve the above object, three or more masks are used, and their openings and device configurations are devised. That is, one of a plurality of openings provided in the second mask (102) is selected by a deflector (first figure selecting deflector 112) provided in a stage subsequent to the first mask (101). The image formed thereby is selected by a deflector (second figure selection deflector 114) from one of a plurality of openings provided in the third mask (103), and the image formed by this is selected. The sample is focused and deflected to irradiate the target sample. At least one of the second mask and the third mask has an opening of a repetitive figure of a fine element pattern. One of the second mask and the third mask selects or defines the maximum irradiation area, and the other selects the shape of the electron beam. Further, one of the second mask and the third mask is a thin mask, and the other is a thick mask used for electron beam blanking. Further, one of the second mask and the third mask has a sufficiently large opening without damaging the image formed by the other mask, and the variable shaping method is performed on the other mask.
Note that the variable shaping deflector is provided in the space with the longer mask interval to reduce structural restrictions.

Further, in the above-mentioned electron beam lithography apparatus, a figure having a repetitive pattern of a fine element pattern on the second mask and the third mask, and a figure having a small opening area is arranged on the mask far from the sample to reduce the Coulomb effect. This prevents blurring of the resulting electron beam. A mask having a rectangular opening is arranged in front of the mask for selecting or defining the maximum irradiation area. Further, the maximum irradiation area is selected or specified according to the size of the opening that determines the shape of the electron beam. Thereby, the graphic density can be increased. In addition, the second mask has a figure opening having a fine pattern that cannot be resolved on the sample and having a current density that can be adjusted. Furthermore, it has a plurality of rectangular openings having different sizes of 10 times or more on the mask,
The maximum irradiation area is selected or specified according to the size of the opening that determines the shape of the electron beam. As a result, an optimal rectangular opening can be selected.

It is desirable that the reduction ratio of the two masks on the sample is basically equal. By making them the same size, the designs of the second mask and the third mask can be shared. However, depending on the pattern of the mask opening, processing may be difficult at a low reduction ratio. In this case, the drawing accuracy can be improved by increasing the reduction ratio of the mask that is difficult to process. Further, as for the arrangement of the openings in the mask, the smaller the opening area is, the more the pattern is arranged from the outside. A pattern having a large opening area requires a large Coulomb correction. The accompanying error increases with the outer circumference. Therefore, it is effective to arrange a pattern having a small opening area on the outer periphery. This is an important advantage, especially in the present invention, which can have patterns of various opening areas.
By using the above-described electron beam drawing technique, an LSI pattern can be drawn accurately and at high speed, and the productivity of a semiconductor integrated circuit can be improved.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) First, a first embodiment of the present invention will be described.
The electron beam lithography apparatus of this embodiment is an embodiment in which three or more masks are used, and a plurality of openings are provided in each of two masks. FIG. 1 shows an outline of an electron beam lithography apparatus of the present embodiment. In the figure, an electron beam emitted from an electron source 100 directly irradiates a first mask 101. The first mask 101 is provided with a single rectangular opening as described later, and an opening image can be obtained by the irradiated electron beam. The aperture image of the first mask 101 has two lenses (a first transfer lens 104 and a second transfer lens 10).
5) is formed on the second mask 102.

The image forming position on the second mask 102 is controlled by a first figure selecting deflector 112 and a first variable shaping deflector 113. After passing through the opening of the second mask 102, the electron beam forms an image on the third mask 103 by two lenses (third transfer lens 106 and fourth transfer lens 107) at the subsequent stage. This image formation position is also controlled by the second figure selection deflector 114. The electron beam that has passed through the opening of the third mask 103 passes through the reduction lens 108 and the objective lens 1
09 projects onto the sample 110 placed on the stage 111. Usually, a deflector is provided in the objective lens 109, and the image forming position of the electron beam on the sample 110 is determined by the deflector.

Next, the first mask 101 and the second mask 10
2. Details of the structure of the third mask 103 are shown as a first mask 200 in FIG. 2, a second mask 300 in FIG. 3, and a third mask 400 in FIG. 4, respectively. As shown in FIG. 2, the first mask 200 has a rectangular opening 201. On the other hand, as shown in FIG. 3 and FIG.
The 00 and third masks 400 have rectangular openings 301 and 401 similar to the first mask 200, as well as graphic openings 302 (for example, hole patterns) and 402 of fine elements.
(For example, a wiring pattern).

As shown in FIG. 3, the second mask 300 has a large rectangular opening 301 at the center. The locations corresponding to the three graphic positions adjacent to the rectangular opening 301 are shielded, and the rectangular opening 2 of the first mask 200 is closed.
The position of the image No. 01 (the first mask image 303) is adjusted and the second image is adjusted.
It is possible to partially overlap the rectangular opening 301 of the mask. It is possible to form a new smaller rectangular image of any shape by a method based on this superposition, that is, a variable forming method.

As shown in FIG. 4, the third mask 400 has a central rectangular opening 401 larger than any opening of the second mask 300, so that the electron beam passing through the second mask 300 can pass through as it is. ing. In the third mask 400, similarly to the second mask 300, the rectangular opening 40 is formed.
The locations corresponding to the three graphic positions adjacent to 1 are shielded, and the rectangular openings 301 of the second mask 300, 21 graphic patterns other than the three blocked graphic positions, and the rectangular openings 401 of the third mask 400. , And a total of 42 figure patterns can be selected by combining 21 figures which have passed through the rectangular opening 301 of the second mask 300 and the 21 figure patterns of the third mask.

As a result, a total of 42 figures can be selected. In addition, it can be realized with a 2/3 off-axis amount when 42 selections are made on one mask. Some aberrations due to off-axis are proportional to the cube of the deflection, and this difference is extremely important in performing a high-precision collective figure irradiation method. Note that, in the above description, the places corresponding to the three graphic positions adjacent to the rectangular opening 401 of the third mask 400 are shown as being shielded, but graphic patterns can also be provided at these three shielded graphic positions. . In this case, a total of 45 graphic patterns can be selected from the 21 graphic patterns of the second mask 300 and the 24 graphic patterns of the third mask 400. In addition, if the rectangular opening 401 is arranged at the center of the third mask 400, the figure opening selected on the second mask 300 can be used by swinging back on the axis, and the electron beam passes off-axis. Occurrence of aberration can be reduced.

In order to design an electron optical system of a three-stage mask, it is necessary to consider two orbits of a crossover image and a mask image at the same time. Further, it is preferable from the viewpoint of the manufacture of the mask that the reduction ratio of these three mask images on the sample is the same or about twice. As an example of realizing a condition close to this, Pfeiffer et al. Published “Journal of Vacuum Science and Technology” B11 (1993).
As described on pages 2332 to 2341, 3
There is a method using one condenser lens (Auxiliary lens is an auxiliary lens for adjustment). However, in this method, since the second mask is located in the lens, it is not suitable for frequently moving or exchanging the mask as in the collective figure irradiation method. On the other hand, in the present embodiment, as in the case of the electron optical system of FIG. 1, each of the lenses has a two-stage lens structure (first transfer lens 104 / second transfer lens 105,
And third transfer lens 106 / fourth transfer lens 107)
By performing image formation on the mask by using the second mask 102, the second mask 102 can be easily moved or replaced, and the operability is significantly improved.

The crossover trajectory 11 shown in FIG.
5 and the mask image trajectory 116, proper trajectories are obtained for both trajectories. First transfer lens 10
4. By making the focal lengths of the second transfer lens 105, the third transfer lens 106, and the fourth transfer lens 107 equal, the reduction ratios of the first to third masks on the sample are equalized. can do. Especially the second
Since the magnification at the time of transferring the mask 102 onto the third mask 103 needs to be strictly adjusted, both the crossover image and the mask image can be controlled by a two-stage lens. A further advantage of this optical system is that the electron beam can be incident on the second mask 102 perpendicularly to the mask surface. By irradiating the electron beam perpendicularly to the mask surface, there is an effect that the influence of penumbra caused by the thickness of the mask can be reduced.

In the configuration shown in FIG. 1, since there is only a figure selecting deflector before the third mask 103, a highly sensitive deflection system can be formed. As a result, it is easy to realize an increase in the number of figures and a reduction in deflection voltage.

Further, the second mask 300 and the third
As can be seen by comparing FIGS. 3 and 4 as a feature of the graphic arrangement of the mask 400, a wiring layer having a larger opening area is arranged on the third mask 400. In general, when the current density, that is, the density between electrons, increases, Coulomb force acts between the electrons and repels each other, resulting in blurring of the electron beam. In this configuration, a mask (third mask) having a figure with a large opening area where a large current flows and the Coulomb effect is relatively large is used in a state where the traveling length of the electron beam is shorter (disposed at a position close to the sample 110). This reduces the effect of the Coulomb effect. A mask having a small opening area like a hole layer (second mask)
May be arranged at a position far from the sample 110 because the amount of current is small and the influence of the Coulomb effect is small even if the running distance is somewhat longer. In this way, beam degradation is substantially reduced.

In this embodiment, an electron beam lithography apparatus having the structure shown in FIG. 1 and a mask having the structure shown in FIGS. 2 to 4 are used. The first transfer lens 104 and the second transfer lens
Transfer lens 105, third transfer lens 106, and fourth
The focal length of the transfer lens 107 is 35 mm. In addition,
The first variable shaping deflector 113 is a four-pole electrostatic deflector,
The first and second figure selection deflectors 112 and 114
It is a polar electrostatic deflector. An 8-pole electrostatic deflector is provided with a relative point correction voltage. Although not shown in the drawing, a focus corrector is also provided in the transfer section. Therefore,
The second mask 102 can be transferred to the third mask 103 at the same magnification.

The reduction ratio of the reduction lens 108 is 1/30, and together with the objective lens 109, the reduction ratio is 1/25 on the sample 110 (wafer). Since the maximum size of the collective figure is 5 μm square on the wafer, it is 12 μm on both masks.
It is 5 μm square. A hole layer having a small Coulomb effect is formed on the second mask 102. The mask is silicon 20 μm thick. The mask for the hole layer needs to form holes having a high aspect ratio. For example, 0.15μm on wafer
Is 3.75 μm on the mask. Therefore, it is effective to reduce the hole pattern that is difficult to process to a reduction ratio of about 1/50.

The rectangular openings on the first mask 101, the second mask 102 and the third mask 103 are 150 μm square. Therefore, a rectangular aperture or a figure beam that has passed through the second mask can pass through the third mask without losing its shape. Conversely, the figure pattern on the third mask can be irradiated with a sufficient margin. In addition, variable molding is the second
Although the operation is performed on the mask 102, this arrangement is also possible on the third mask 103. The second figure selection deflector may have one stage as shown in FIG. 1, but it is also effective to provide two stages like the first figure selection deflector in order to prevent axis deviation during deflection. The electron acceleration voltage is 50 kV, and the current density is 10 A / cm ² on the wafer.

Using the above electron beam drawing apparatus, the wafer 11
An LSI pattern was drawn on the “0”. As a result of drawing the hole layer using the electron beam positive resist PSR and the graphic opening on the second mask 102, a throughput of 5 wafers / hour was obtained with an 8-inch wafer. The dimensional accuracy was ± 10 nm. When a similar pattern was drawn only by the variable molding method, it was not possible to draw one sheet / hour. Also,
The wiring layer was drawn using the graphic opening on the third mask and the electron beam negative resist SAL. As a result, a throughput of 3 wafers / hour was obtained with an 8-inch wafer. The dimensional accuracy was also ± 10 nm. When the same pattern was drawn only by the variable forming method, it was not possible to draw one sheet / hour. As described above, it has become possible to effectively utilize the collective figure irradiation method.

(Second Embodiment) In the first embodiment, a fine figure opening 302 (for example, a hole pattern) of a second mask is used.
The drawing pattern is generated by the combination of the rectangular opening 401 of the third mask and the rectangular opening 301 of the second mask and the minute figure opening (for example, a wiring pattern) of the third mask. In the example,
The second mask has a rectangular opening similar to that of the first embodiment, and a plurality of rectangular openings having different shapes and sizes smaller than the rectangular opening.

FIG. 5 shows an outline of an electron beam drawing apparatus according to the present embodiment. This electron beam lithography apparatus is almost the same as that of the first embodiment except that the first figure selection deflector 112 of the electron beam lithography apparatus of FIG. 1 is replaced with a first rectangular selection deflector 501. In this embodiment, the second mask 102 and the third mask
Details of the structure of the mask 103 are shown as a second mask 600 in FIG. 6 and a third mask 700 in FIG. 7 (the first mask 101 is the same as in FIG. 2).

As shown in FIG. 6, the second mask 600 has a rectangular opening 601 similar to the rectangular opening 301 shown in FIG. On the other hand, the second mask 300 and the third mask
As shown in FIG. 3 and FIG.
In addition to rectangular openings 301 and 401 similar to mask 200, graphic openings 302 and 402 for fine elements are arranged.

The second mask 600 has rectangles 604 of various sizes and various shapes in addition to the rectangular openings 601, which are different from the examples of the font tag and the like. Further, the first mask has a rectangular opening, and the first mask image (FIG. 6)
In order to form an aperture image on the third mask (see a large second mask image 702 and a small second mask image 703 in FIG. 7) by superimposing the aperture group on the second mask, the aperture group on the second mask is dense. Can be arranged. Thus, the amount of off-axis can be reduced. As shown in FIG. 7, the third mask 700 is provided with a rectangular opening 701 at the center and a plurality of graphic openings of the same size around the opening. As the graphic opening, it is preferable that a wiring pattern is provided inside and a hole pattern is provided outside.

In this embodiment, first, as shown in FIG.
The third mask 70 is formed by the second mask image 702 having a large rectangular opening.
By illuminating 0, one entire graphic opening can be selected, while by irradiating the third mask 700 with the second mask image 703 of a small rectangular opening, a part of one graphic opening can be selected. As a result, the present invention can be applied to a part of a pattern (a half part) that cannot be formed by merely repeating the graphic opening of the third mask 700, a peripheral circuit of a memory LSI, and the like.

The size of the rectangle may be adjusted by the degree of overlap between the first mask image 603 of the large rectangular opening and the rectangular opening 601 of the second mask as shown in FIG.
If the size of the required rectangle is determined, several rectangular openings of that size are prepared and placed, and the rectangular opening is selected with the first mask image 603 of the large rectangular opening, so that the size of the rectangle can be made more accurate. Suitable for It should be noted that the above arrangement is possible even if the arrangement of the second mask and the third mask is exchanged. However, in consideration of the Coulomb effect, it is better to arrange the third mask 700 having a figure opening in the subsequent stage.

The present embodiment uses an electron beam lithography apparatus having the structure shown in FIG. 5 and a mask having the structure shown in FIGS. 2, 6 and 7. An LSI pattern was drawn on the wafer using the gate pattern of FIG. Electron beam negative resist SA
As a result of drawing the gate layer using L and the graphic opening on the second mask, a throughput of 4 wafers / hour was obtained with an 8-inch wafer. The periphery of the memory cell was formed by combining the upper right rectangle in FIG. 6 with a graphic pattern. Drawing was performed using partial beams of a collective figure. This makes it possible to draw even portions of the memory graphic using the collective mask. Further, the exposure amount of the pattern partially cut out for correcting the proximity effect was set to be 20% more. As a result, the dimensional accuracy could be suppressed to ± 9 nm. The same is also possible by forming a rectangular beam by a variable shaping method on the second mask.

(Third Embodiment) In a third embodiment of the present invention, the first mask and the second mask are the same as the above-described second embodiment, and a mask having a graphic opening having a different size is used as the third mask. This is an example. In the conventional method, only a large rectangular opening could be used, so it was necessary to arrange small graphic openings at the same interval as large graphic openings. Because of that, the off-axis distance was unnecessarily increased,
This embodiment improves this.

In the present embodiment, as in the third embodiment, the first
A first mask 200 shown in FIG. 2 is used as a mask, and a second mask 600 shown in FIG. 6 is used as a second mask. As the third mask, various graphic openings having different sizes are provided as shown in FIG. The third mask 800 is used. Then, similarly to the second embodiment, by selecting rectangular openings 604 of various sizes on the second mask 600 in the first mask image 603, or by selecting the first mask image 603 and the rectangular openings 601 of the second mask. Is used to form a rectangular aperture image having a size corresponding to the size of the graphic aperture of the third mask to be selected, and irradiate the rectangular aperture image with the graphic aperture to be selected on the third mask.

According to the present embodiment, the arrangement of the graphic openings on the third mask 800 can be made dense, so that a large number of graphic opening patterns can be provided, and the off-axis distance can be increased. Can be prevented. The central rectangular aperture in FIGS. 7 and 8 is larger than any of the apertures in FIG. 6 so that the variable shaped beams formed by the first and second masks can be passed without interruption. It should be noted that the second mask and the third mask can be used even if the arrangement is switched at the same time as the deflector.

The present embodiment uses an electron beam lithography apparatus having the structure shown in FIG. 5 and a mask having the structure shown in FIGS. 2, 6, and 8. As described above, in the present embodiment, on the third mask, not a part of the collective figure (graphic opening), but a collective figure having a different area is arranged on the same mask. Since the size of the rectangle for irradiating the collective figure pattern on the third mask can be changed by the second mask, a figure opening can be more compactly arranged on the third mask. Can be reduced. This makes it possible to simultaneously draw LSIs of different types and dimensions. As a result of drawing 256MDRAM and 1GDRAM using electron beam negative resist SAL,
An 8-inch wafer provided a throughput of 4 wafers / hour. The dimensional accuracy also secures ± 9 nm. In the second embodiment and the third embodiment, the graphic openings of the fine elements are not arranged on the second mask, but the graphic openings may be arranged around the rectangular openings so that more figures can be used. It is valid.

As an application of this method, there is a method of arranging, as a rectangular opening on the second mask 600 in FIG. 6, a figure opening having a fine opening pattern as shown in FIG. Conceivable. Thus, when an opening having a large Coulomb effect is used like a wiring pattern, by passing through the fine opening pattern, the total current amount can be reduced and the Coulomb effect can be reduced. FIG.
In FIG. 6A, a fine opening pattern is provided uniformly, and the current amount can be reduced to １ ／. Also,
In FIG. 16B, a fine opening pattern in the center is provided more densely on both sides to reduce the current density in the center. By adjusting the density of the fine pattern in this way, it is possible to adjust the current density in the collective figure, which is also effective for proximity effect correction.

(Fourth Embodiment) FIG. 9 is a schematic view of an electron beam drawing apparatus for explaining a fourth embodiment. A major difference between this embodiment and each of the above-described embodiments is that blanking is performed by a blanking deflector 913 provided in a stage preceding the second mask 102. This method is particularly applicable to the second mask 1
It is effective when a thin film mask 903 (see third mask 1103 shown in FIG. 11) that obtains an image contrast by scattering electrons rather than absorbing electrons is disposed as a third mask after 02. This method is a method of blocking the scattered electrons from the thin film mask by the angle limiting aperture 910 at the subsequent stage of the thin film mask 903 to obtain a contrast on the sample.
By making the mask thinner, a finer figure pattern can be formed on the mask.

However, a problem with this method is that when blanking is performed on the angle limiting aperture 910 using the conventional blanking deflector 915, a small amount of scattered electrons that have been blocked prematurely reach the sample 110. Is to start to do so. Therefore, when blanking for a relatively long time, it is necessary to use another blanking method together. In this embodiment, an effective blanking can be performed by disposing a thick mask (the second mask 102) in addition to the thin film mask 903 and deflecting the electron beam and blocking the electron beam with the thick mask. The mask in this case is rectangular (1001) as shown as a second mask 1000 in FIG.
One or more graphic openings can be arranged at the same time. This method is effective even if the order of the blanking mask and the drawing mask is reversed.

The present embodiment uses an electron beam lithography apparatus having the structure shown in FIG. 9 and a mask having the structure shown in FIGS. 2, 10 and 11. In this embodiment, the third mask is a thin film mask and has a thickness of 2 μm. Since a thin film mask can reduce the aspect ratio of a fine pattern in a figure opening, it is easy to obtain a mask with high accuracy.
The rectangular opening at the center of the third mask 903 (see 1103 in FIG. 11) is 125 μm, and the first mask and the second
As the mask 1000, an ordinary mask having a thickness of 20 μm was used. Drawing is performed between shots using a conventional blanking deflector 9.
At step 15, blanking is performed, and during a long waiting time such as waiting for stabilization of the stage movement, the electron beam is deflected on the second mask 102 (1000 in FIG. 10) by the blanking deflector 913 in front of the second mask. Complete blanking (first blanked mask image 1 in FIG. 10)
004). The blanking deflector 913 is a two-pole electrostatic deflector. 1 using electron beam negative resist SAL
As a result of writing on the GDRAM, when blanking was not performed on the second mask 102, photosensitive areas due to blanking leakage were observed at 10 places.
This could be eliminated by performing the blanking above.

(Fifth Embodiment) In the present embodiment, as shown in FIG.
Variable shaping is performed on the mask 103. In this electron optical system, the distance between the second mask 102 and the third mask 103 is longer than the distance between the first mask 101 and the second mask 102, and the variable shaping deflector 1214 is arranged longer. Since the molding deflection requires high speed, the variable shaping deflector is usually made thin and long. Accordingly, in a narrow space, the lens magnetic field is affected. This prevents accurate deflection. Therefore, the variable shaping deflector is preferably arranged at a place where the distance between masks is long.
In FIG. 12, the light is obliquely incident on the second mask 102. However, when the number of figures is large, vertical incidence is desirable as shown in FIG. Also in this case, by increasing the focal length of the third transfer lens 106 and the fourth transfer lens 107, it is possible to easily arrange the variable shaping deflector 1214.

In this embodiment, an electron beam lithography apparatus having the structure shown in FIG. 12 and a mask having the structure shown in FIGS. 2, 13 and 14 are used. In this embodiment, the variable shaping deflector 12
14 is arranged between the second mask 102 and the third mask 103. The distance between the first mask 101 and the second mask 102 is 100 mm, the distance between the second mask 102 and the third mask 103 is 120 mm, and a variable shaping deflector 1214 is disposed between the second mask 102 and the third mask 103. This avoids the effect of the magnetic field of the transfer lens. Note that the variable shaping deflector 1214 is φ5 mm × 50 mm. The incident angle on the second mast 102 is smaller than that on the third mask, which is advantageous for increasing the number of figures. As shown in FIG. 9, it is also possible to make vertical incidence, which is suitable for arranging more collective figures.

(Sixth Embodiment) In this embodiment, an electron beam lithography apparatus having the structure shown in FIG. 5 and a mask having the structure shown in FIGS. 2, 17 and 18 are used. However, the figure selection deflector shown in FIG. In this embodiment, the second
As shown in FIG. 17, the mask 1700 has a rectangular opening 1701 at the center, and forms a variable rectangle by partially overlapping the first mask image 1702 and the rectangular opening. The third mask 1800 has a rectangular opening 18 in the center.
In addition, a plurality of collective figures 1802 and various kinds of fine aperture groups 1804 having different shapes are provided therearound.
As for the group of fine apertures, the upper right corner of the rectangular aperture has a minimum height of 0.
Square apertures of minute dimensions, including 1 μm square squares, are surrounded by rectangular apertures of various widths / lengths. These openings are provided for the purpose of improving the accuracy of the variable rectangle method (variable forming method). The normal variable rectangle method can form a rectangle of any size,
Calibration of the size is required. That is, as the dimensions to be drawn become smaller, it becomes more difficult to obtain the accuracy required for the dimensions.

However, especially for fine dimensions, a necessary rectangular opening is prepared in advance and the required accuracy can be ensured by substituting the opening. Since the size of the mask is 25 times the size of the sample, the dimensional accuracy of the opening on the mask can be sufficiently ensured. However, when the number of the rectangles is large, the interval of the arrangement of the figures is limited by the ordinary collective figure irradiation method, so that the number of figures is insufficient.

Therefore, in this embodiment, the first mask and the second mask
A small rectangle is formed using a mask, and this rectangular aperture image 1803 is formed.
Selectively irradiates one of the groups of minute openings 1804 on the third mask. Thus, the rectangular openings can be efficiently arranged on the third mask. Particularly, in this embodiment, the rectangular opening is small, and the effect is extremely large. The minute rectangle may be defined only by the opening shape of the third mask, but may be used in combination with another opening shape. An elongated opening is disposed on the right and above the large rectangular opening in the center. The narrow direction of this opening is the third mask, and the length in the longitudinal direction is the first mask image and the second mask.
It is defined by the overlap of the mask images. Thereby, the dimension in the small direction where the dimensional accuracy is severe can be defined with high accuracy. At the same time, by arranging the collective figure 1802 on the third mask 1800, the ordinary collective figure irradiation method can be used together. The method of this example was used for drawing a logic LSI having a size of 0.15 μm. As a result, the dimensional accuracy is reduced to ± 20 n of the conventional variable rectangle method.
m to ± 10 nm.

Next, an embodiment in which an LSI is formed using an electron beam lithography apparatus to which the present invention is applied will be described. FIG.
(A)-(d) is sectional drawing of the element in each process at the time of manufacturing a semiconductor integrated circuit using this invention. (1) First, as shown in FIG.
On an N minus silicon substrate 45, a P well layer 46, a P layer 47, a field oxide film 48, a polycrystalline silicon / silicon oxide film gate 49, a P high concentration diffusion layer 50, an N high concentration diffusion layer 51, and the like are formed. (2) Next, as shown in FIG. 2B, an insulating film 52 of phosphor glass (PSG) is applied by a normal method, and an electron beam resist 53 is applied thereon, and the electron beam of the present invention is applied. A hole pattern 54 is formed by a drawing apparatus.

(3) Next, as shown in FIG. 3C, the insulating film 52 is dry-etched using an electron beam resist (not shown) as a mask to form a contact hole 55. (4) Next, as shown in FIG.
/ TiN electrode wiring 56 was formed, and then an interlayer insulating film 57 was formed. Next, an electron beam resist (not shown) is applied, and the hole pattern 58 is drawn by the electron beam drawing apparatus of the present invention.
To form The hole pattern 58 is embedded with a W plug, and the A1 second wiring 59 is connected. The conventional method was used for the subsequent passivation process.

In this embodiment, only the main manufacturing steps are described and details are omitted. However, the same steps as those of the conventional method are used except that the electron beam lithography technique of the present invention is used in the lithography step of forming a contact hole. Was. With the above process, CMO
SLSI could be manufactured with high yield. As a result of manufacturing a semiconductor device using the present invention, it is possible to prevent the occurrence of misalignment due to the distortion of a figure and the occurrence of a connection failure of a hole-embedded metal due to non-uniformity of resolution and current density, which has conventionally occurred. Significantly improved.

Although only a specific type of collective figure is used in this specification, it is apparent that the present invention can be applied to other various figures. The electronic optical system such as the structure of the objective lens and the reduction ratio is not limited to this embodiment, and the present invention is effective for all electronic drawing apparatuses that select a figure by deflection, reduce the figure, and project it on a sample.

[0046]

As described above, by using the present invention, the speed and accuracy of the collective figure irradiation method can be improved. More specifically, effects such as suppressing the off-axis and increasing the number of figures, vertically incident electrons on the mask, and making the mask thinner are obtained. Thereby, a semiconductor integrated circuit or a microstructure element can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electron beam drawing apparatus for explaining a first embodiment of the present invention.

FIG. 2 is a first mask diagram according to the present invention.

FIG. 3 is a second mask diagram according to the first embodiment of the present invention.

FIG. 4 is a third mask diagram according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of an electron beam lithography apparatus for explaining second and third embodiments of the present invention.

FIG. 6 is a second mask diagram in which various rectangles are arranged in the second embodiment of the present invention.

FIG. 7 is a third mask diagram for explaining partial selection of a collective figure according to the second embodiment of the present invention.

FIG. 8 is a third mask diagram in which collective figures having different sizes are arranged according to the third embodiment of the present invention.

FIG. 9 is a configuration diagram of an electron beam lithography apparatus using a thin film mask according to a fourth embodiment of the present invention.

FIG. 10 is a second mask diagram for blanking in the fourth embodiment of the present invention.

FIG. 11 is a diagram (third mask) of a thin film mask according to a fourth embodiment of the present invention.

FIG. 12 is a configuration diagram of an electron beam lithography apparatus for explaining a fifth embodiment of the present invention.

FIG. 13 is an example of a second mask diagram according to the fifth embodiment of the present invention.

FIG. 14 is an example of a third mask diagram in the fifth embodiment of the present invention.

FIG. 15 is a cross-sectional view of an element in each step when a semiconductor integrated circuit is manufactured using the present invention.

FIG. 16 is a diagram for explaining a figure opening having an unresolvable fine pattern used for application of the present invention.

FIG. 17 is a second mask diagram according to the sixth embodiment of the present invention.

FIG. 18 is a third mask diagram according to the sixth embodiment of the present invention.

[Explanation of symbols]

45: N minus silicon substrate, 46: P well layer, 4
7: P layer, 48: field oxide film, 49: polycrystalline silicon / silicon oxide gate, 50: P high concentration diffusion layer,
51: N high concentration diffusion layer, 52: insulating film, 53: electron beam resist, 54: hole pattern, 55: contact hole, 56: W / Ti electrode wiring, 57: interlayer insulating film, 5
8: hole pattern, 59: second aluminum wiring, 100:
Electron source, 101: first mask, 102: second mask, 1
03: Third mask, 104: First transfer lens, 105:
Second transfer lens, 106: third transfer lens, 107: fourth transfer lens, 108: first reduction lens, 110: sample, 111: stage, 112: first figure selection deflector,
113: first variable shaping deflector, 114: second figure selection deflector, 115: crossover orbit, 116: mask image orbit, 200: first mask, 201: rectangular aperture, 300:
Second mask, 301: rectangular opening, 302: figure opening, 3
03: first mask image, 400: third mask, 401: rectangular opening, 402: figure opening, 403: second mask image, 5
01: first rectangular selection deflector, 600: second mask, 60
1: rectangular aperture, 603: first mask image, 604: small rectangular aperture, 700: third mask, 701: rectangular aperture, 7
02: large second mask image, 703: small second mask image, 800: third mask, 801: small rectangular opening, 8
02: Large rectangular aperture image, 803: Small rectangular aperture image,
901: First figure selection deflector, 903: Thin film mask, 9
10: Angle limiting aperture, 913: Blanking deflector,
914: first variable shaping deflector, 915: conventional blanking deflector, 1000: second mask, 1001: rectangular aperture, 1003: first mask image, 1004: blanked first mask image, 1103: Thin film mask, 100
2: second mask image, 1101: rectangular aperture, 1201: second figure selection deflector, 1213: first figure selection deflector, 1
214: first variable shaping deflector, 1300: second mask,
1301: rectangular opening, 1302: figure opening, 1303:
First mask image, 1401: rectangular aperture, 1402: second mask image, 1403: third mask, 1700: second mask, 1701: rectangular aperture, 1702: first mask image, 1
800: third mask, 1801: rectangular opening, 1802:
Collective figure, 1803: rectangular aperture image, 1804: fine aperture group.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Matsuzaka 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Tokuro Saito 1-280 Higashi Koigakubo, Kokubunji, Tokyo Central Research Laboratory (72) Inventor Yoshinori Nakayama 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside Hitachi, Ltd.Central Research Laboratory (72) Inventor Hiroyuki Ito 882 Ma, Hitachinaka-shi, Ibaraki Pref. 56) References JP-A-4-137520 (JP, A) JP-A-4-100208 (JP, A) JP-A-6-5500 (JP, A) JP-A-5-304083 (JP, A) Hei 4-360516 (JP, A) JP-A-64-76656 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7 / 20 H01J 37/305

Claims (7)

(57) [Claims] 1. A first having an electron source for generating an electron beam, a first rectangular opening for the electron beam in a rectangular
A second mask having a mask, a first deflector for deflecting the rectangular electron beam passing through the first mask, and a second rectangular opening for irradiating the rectangular electron beam deflected by the first deflector And a figure including a first transfer lens on the first mask side between the first mask and the second mask, and a second transfer lens on the second mask side, and passing through the second mask. A second deflector for deflecting the beam, a third rectangular opening for irradiating the figure beam deflected by the second deflector to the plurality of figure positions, and a first batch pattern opening; A third thinner than the second mask;
A figure having a mask, a third transfer lens on the second mask side between the second mask and the third mask, a fourth transfer lens on the third mask side, and passing through the third mask An electron beam lithography apparatus comprising: a reduction lens for reducing a beam to a predetermined size; and an objective lens for irradiating a sample. 2. A first source having an electron source for generating an electron beam, and a first rectangular opening for making the electron beam rectangular.
A mask; a first deflector for deflecting the rectangular electron beam passing through the first mask; and a second rectangular opening for irradiating the plurality of graphic positions with the rectangular electron beam deflected by the first deflector. A second mask having a portion and a first batch pattern opening; a first transfer lens between the first mask and the second mask on the first mask side; and a second transfer lens on the second mask side A second deflector comprising a lens and deflecting the graphic beam passing through the second mask; and a third irradiating the graphic beam deflected by the second deflector to the plurality of graphic positions. A third mask having a rectangular opening and a second collective pattern opening, the third mask being thicker than the second mask; and a third mask disposed between the second mask and the third mask on the second mask side. A transfer lens, and a fourth transfer lens on the third mask side. And a reduction lens for reducing the figure beam passing through the third mask to a predetermined size, the electron beam drawing apparatus characterized by comprising an objective lens for irradiating the sample. 3. A first source having an electron source for generating an electron beam, and a first rectangular opening for making the electron beam rectangular.
A mask; a first deflector for deflecting the rectangular electron beam passing through the first mask; and a second rectangular opening for irradiating the plurality of graphic positions with the rectangular electron beam deflected by the first deflector. Part having a first pattern opening and a third pattern opening adjacent to the second rectangular opening.
A second mask in which two graphic positions are shielded, a second deflector for deflecting the graphic beam that has passed through the second mask, and a graphic beam deflected by the second deflector in a plurality of graphic positions. A third rectangular opening to be irradiated and a second pattern opening adjacent to the third rectangular opening and arranged with a small off-axis distance so as to increase the graphic density; An electron beam lithography comprising: a third mask having a small thickness; a reducing lens for reducing a figure beam passing through the third mask to a predetermined size; and an objective lens for irradiating a sample. apparatus. 4. A first having an electron source for generating an electron beam, a first rectangular opening for the electron beam in a rectangular
A mask; a first deflector for deflecting the rectangular electron beam passing through the first mask; a second rectangular opening for irradiating the plurality of graphic positions with the rectangular electron beam deflected by the deflector; A second pattern opening and a first pattern opening adjacent to the second rectangular opening and arranged with a small off-axis distance to increase the graphic density; A second mask in which three adjacent graphic positions are shielded, a second deflector that deflects the graphic beam that has passed through the second mask, and a plurality of graphic beams deflected by the second deflector. A third rectangular opening for irradiating the graphic position, a third mask thicker than the second mask in which three graphic positions adjacent to the third rectangular opening are shielded, and passing through the third mask To reduce the figure beam into a predetermined size. Electron beam lithography system, characterized by comprising: a's, and an objective lens for irradiating the sample. 5. A first having an electron source for generating an electron beam, a first rectangular opening for the electron beam in a rectangular
A mask; a first deflector for deflecting the rectangular electron beam passing through the first mask; and a second rectangular opening for irradiating the plurality of graphic positions with the rectangular electron beam deflected by the first deflector. A second mask having a portion and a first batch pattern opening; a first transfer lens between the first mask and the second mask on the first mask side; and a second transfer lens on the second mask side A second deflector comprising a lens and deflecting the figure beam passing through the second mask; a third rectangular opening for irradiating the figure beam deflected by the second deflector; 3rd thicker than 2 masks
A mask, a third transfer lens on the second mask side between the second mask and the third mask, and a fourth transfer lens on the third mask side, and have passed through the third mask. An electron beam lithography apparatus comprising: a reduction lens for reducing a figure beam to a predetermined size; and an objective lens for irradiating a sample. 6. A method for generating an electron beam by the electron source, the steps of the rectangle by irradiating the electron beam to the first rectangular aperture of the first mask, a rectangular electron beam passed through the first mask Using a first deflector, and deflecting the rectangular electron beam deflected by the first deflector into a plurality of figures using a second rectangular opening and a first collective pattern opening of a second mask. Irradiating the second mask with a first transfer lens on the first mask side and a second transfer lens on the second mask side between the first mask and the second mask; Deflecting the graphic beam that has passed through the second deflector by the second deflector;
Irradiating a plurality of graphic positions with a third rectangular opening and a second collective pattern opening of a third mask having a thickness smaller than that of the third mask; and a second mask between the second mask and the third mask. Reducing the graphic beam having passed through the third transfer lens on the mask side and the fourth transfer lens on the third mask side and passing through the third mask to a predetermined size with a reduction lens; Passing the graphic beam reduced in step (1) through an objective lens to irradiate the sample with a sample beam. 7. A step of generating an electron beam, a step of forming a rectangular beam from the generated electron beam using a first mask, and a step of applying the formed rectangular beam to a second mask provided below the first mask. A deflecting step, a first irradiating step of irradiating the collective pattern on the second mask with the deflected rectangular beam, and a rectangular opening disposed below the second mask.
The third mask, which is thinner than the second mask,
A second irradiation step of irradiating the figure beam obtained by the mask, a first drawing step of drawing the figure beam obtained in the second irradiation step on a sample substrate placed on a sample table, Forming a partial beam having a different area of the graphic beam from the graphic beam obtained in the second irradiation step by the rectangular opening of the third mask; and a sample substrate having the partial beam mounted on a sample stage. And a second drawing step of drawing on the electron beam.