JP3458628B2 - Electron beam lithography system - 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 drawing apparatus, and more particularly to the structure of a variable shaping aperture used in the electron beam drawing apparatus.

[0002]

2. Description of the Related Art In recent years, in a semiconductor manufacturing process, a pattern is directly formed on a wafer surface by electron beam irradiation,
The so-called electron beam direct writing method is drawing attention because of its fine workability and patterning flexibility.

Unlike the pattern transfer method using optics or X-rays, the electron beam direct writing method directly draws a pattern on a wafer from pattern data without using a register mask. Since the electron beam is used, it is excellent in fine processing and is effective in fine processing requiring a high degree of integration, for example, manufacturing of a large capacity semiconductor memory device. However, since this technique does not use a register mask, it is necessary to sequentially draw patterns on the wafer one by one. Conventionally, the pattern is filled with an electron beam that is very finely squeezed, so it takes a very long time to form the pattern, and the throughput is lower than that of the pattern transfer method using light rays or X-rays, and its application is a device. It was limited to trial production.

In order to improve the throughput, there has been proposed a so-called variable rectangular type electron beam drawing method having a certain size, for example, drawing a rectangular area at once. In this method, an aperture with a rectangular hole is prepared one by one at the top and bottom, and the electron beam deflector installed between them changes the overlap between the electron beam shaped by the upper aperture and the lower aperture. , Control the shape of the electron beam.

FIG. 5 is a conceptual diagram of the above-mentioned variable shaped beam type electron beam drawing apparatus. As shown,
The variable shaped beam electron beam drawing apparatus is an electron gun 1.
0, the first mask 20, the deflector 30, the second mask 40, the main deflector, the sub deflector, and the objective lens 50 including the sub sub deflector and the like. FIG. 6 shows the principle of the variable shaped beam system. As shown in FIG. 6, the first mask 20 and the second mask 40 are provided with, for example, apertures 22 and 42 having rectangular holes, respectively, and the electron beam overlaps the shapes of the apertures 22 and 42 and these apertures. It is controlled according to the condition.

An electron beam 12 generated from an electron gun 10
First, by using the first mask 20, the first mask 20
It is shaped according to the shape of the aperture 22 provided in the. The shaped electron beam is deflected in a predetermined direction by the deflector 30 and is irradiated on the second mask 40.
In the second mask 40, the electron beam deflected by the deflector 30 passes only through the opening portion of the aperture 42, and the other portion is blocked by the second mask 40. As a result, the electron beam that has passed through the second mask 40 is determined by the shapes of the apertures 22 and 42 of the first and second masks 20 and 40 and the deflection direction of the deflector 30. As a result, the electron beam that has passed through the second mask 40 is shaped into a predetermined shape.

The electron beam that has passed through the second mask 40 is focused by the objective lens 50 and is irradiated on the wafer 60. As a result, a pattern corresponding to the shape of the shaped electron beam is formed on the wafer 60.

[0008]

By the way, in the above-mentioned conventional electron beam drawing apparatus, when forming a large pattern (hereinafter referred to as a large pattern) and when forming a small pattern (hereinafter referred to as a small pattern). In comparison, there is a problem that the electron beam is blurred. Due to the blurring of the electron beam, for example, when a small pattern is formed near a large pattern, the two patterns are connected to each other, which causes defective elements and reduces the yield.

In the case of forming a pattern on a wafer with an electron beam, in the electron beam shaped through a large opening, the peripheral portion of the electron beam is diffused by the scattering of electrons, and the electron beam is formed using this electron beam. The outline of the pattern is blurred. On the other hand, when a pattern is formed using a small opening, the diffusion of the electron beam is smaller than when a large opening is used, and the outline of the formed pattern is less blurred.

FIG. 7 shows the overlapping state of the apertures when forming a large pattern by the apertures 22 of the first mask and the apertures 42 of the second mask and the energy intensity of the electron beam with which the wafer is irradiated. .
Note that, here, the aperture 22 and the aperture 42
Is a square having sides of 100 μm as shown in the figure. The opening 25 has a width of 50 μm, for example. As shown, the electron beam is focused by the objective lens, and a pattern is formed on the wafer according to the overlapping openings 25 of the aperture 22 of the first mask and the aperture 42 of the second mask.

For example, two holes are formed on the wafer according to the opening 25 formed by the overlapping of the apertures 22 and 42.
A pattern reduced to ⅕, that is, a pattern having a width of 2 μm is formed. However, actually, the outline of the pattern formed on the wafer is blurred, and the width of the pattern becomes 2 μm or more.

FIG. 8 shows the overlapping state of the apertures and the intensity of the electron beam energy in the wafer when a pattern having a narrow width, that is, a small pattern is formed by the apertures 22 and 42. As shown,
The width of the overlapping region 26 of the apertures 22 and 42 is as small as 5 μm, so that a pattern reduced to ⅕, that is, a small pattern having a width of 0.2 μm is formed on the wafer. When forming a small pattern, unlike the case of forming a large pattern, there is only a slight blurring of the contour portion.

FIG. 9 is a diagram showing a design pattern. As shown, adjacent large pattern 70 and small pattern 80
Is provided. Then, the first shown in FIG. 7 and FIG.
The pattern formed on the wafer according to the overlapping state of the apertures 22 and 42 of the second mask and the second mask is shown in FIG. In FIG. 10, 71 indicates a large pattern formed on the wafer, and 81 indicates a small pattern formed on the wafer.

As shown in FIG. 10, when the outline of the large pattern 71 is blurred, the two patterns that are separated by design are connected to each other in the portion where the large pattern 71 and the small pattern 81 are adjacent to each other. There is.

The present invention has been made in view of the above circumstances, and an object thereof is to suppress the beam blur of a large pattern without impairing the throughput and to maintain the resolution when the large and small patterns are formed close to each other. An object of the present invention is to provide an electron beam drawing apparatus that can be manufactured and can improve the yield.

[0016]

In order to achieve the above object, the present invention provides an overlapping state of a first aperture formed in a first mask and a second aperture formed in a second mask. Accordingly, the electron beam drawing apparatus changes the electron beam and irradiates the shaped electron beam through the lens system onto the wafer to form a desired pattern.
Fine lines for blocking the electron beam having a line width set according to the resolution on the wafer are provided on the contours of the first and second apertures, and the line width of the fine line for blocking the electron beam is on the wafer. The resolution is set below.

Further, in the present invention, preferably, the electron beam is changed according to the overlapping state of the first aperture formed on the first mask and the second aperture formed on the second mask. An electron beam drawing apparatus for irradiating a wafer with a shaped electron beam through a lens system to form a desired pattern, wherein the contours of the first and second apertures have a resolution on the wafer. An electron beam blocking thin line having a line width set according to the above is provided, and the line width of the electron beam blocking thin line is set to a value equal to or less than a value calculated according to the resolution on the wafer and the reduction rate during pattern formation. Has been done. In addition, the electron beam is changed according to the overlapping state of the first aperture formed on the first mask and the second aperture formed on the second mask, and the shaped electron beam is passed through the lens system through the lens system. And an electron beam drawing apparatus for irradiating a wafer to form a desired pattern, the electron beam having a line width set in accordance with a resolution on the wafer in a contour portion of the first and second apertures. A thin wire for blocking is provided, and the first and second apertures are rectangular.

Further, according to the present invention, the electron beam is changed and shaped according to the overlapping state of the first aperture formed on the first mask and the second aperture formed on the second mask. An electron beam drawing apparatus for irradiating a wafer with an electron beam through a lens system to form a desired pattern, wherein the contours of the first and second apertures are set according to the resolution on the wafer. An electron beam blocking thin wire having a curved line width is provided, and the first and second apertures have a shape other than a rectangle. In addition, the first aperture and the second aperture formed on the first mask.
Electron beam drawing apparatus that changes the electron beam according to the overlapping state with the second aperture formed on the mask of FIG. 3 and irradiates the shaped electron beam on the wafer through the lens system to form a desired pattern. A fine line for blocking an electron beam having a line width set according to a resolution on a wafer is provided in a contour portion of the first and second apertures, and the fine line for blocking an electron beam is the aperture. It is formed parallel to the contour of. Further, one or more thin wires for blocking the electron beam are formed in the contour portion of the aperture.

According to the present invention, in the aperture for electron beam shaping, for example, when a large pattern is formed in accordance with the overlapping state of the apertures by fine lines for blocking the electron beam provided parallel to the contour, Blurring of the contour can be suppressed. Therefore, when the large pattern and the small pattern are formed adjacent to each other, or when the large patterns are formed adjacent to each other, the contact of the adjacent patterns due to the deterioration of the resolution is prevented, the throughput is not impaired, and the yield is improved. Can be improved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment FIG. 1 is a circuit diagram showing an embodiment of an electron beam drawing apparatus according to the present invention. As shown in FIG. 1, in the present embodiment, a thin wire for blocking an electron beam is provided in parallel with the contour of the aperture. With this fine line, when an arbitrary rectangular pattern is formed, an outline having a constant width is formed. Therefore, when forming a large pattern, blurring of the pattern in the outline portion is suppressed, and the accuracy of pattern formation is improved.

In FIG. 1, reference numeral 100 indicates an aperture formed on the first mask, and 200 indicates an aperture formed on the second mask. In the aperture 100 of the first mask, 110 and 120 denote two electron beam blocking fine lines orthogonal to each other, 111 and 121 denote the gap between the fine line and the contour, and 210 and 210 in the aperture 200 of the second mask. Reference numeral 220 denotes two electron beam blocking fine lines which are orthogonal to each other, and 211 and 221 denote gaps between the fine lines and the contour.

In the apertures 100 and 200, the electron beam blocking fine wires 110, 120, 210,
The line width of 220 is set according to the resolution of the pattern on the wafer and the reduction rate at the time of pattern formation. For example, when the resolution of the pattern on the wafer is 0.1 μm and the reduction rate during pattern formation is 1/25, the line width of the electron beam blocking fine line is set to 2.5 μm or less. As a result, when the pattern is formed on the wafer, the electron beam blocking thin wires 110, 120, 210, 2 are formed.
The transfer of 20 into the pattern is avoided. Also,
Fine wires for blocking electron beams 110, 120, 210, 220
The width of the gap between the contour of the aperture and the aperture is set to, for example, 5 μm. Therefore, the electron beam passing through the narrow gap suppresses blurring in the contour of the pattern formed on the wafer.

As shown in the drawing, the opening 1 having a width of 50 μm is formed by the overlapping state of the aperture 100 and the aperture 200.
50 is formed. The electron beam is shaped by the opening 150, and a pattern corresponding to the opening 150 is formed on the wafer. As shown in FIG. 1, for example, a reduced pattern of ⅕ of the size of the opening 150 is formed. That is, a large pattern having a width of 2 μm is formed.

According to this embodiment, the outline of the opening 150 is surrounded by the fine lines 110 and 120 of the aperture 100 and the fine lines 210 and 220 of the aperture 200. And each thin wire 110, 120, 21
Due to the gap between 0 and 220 and the contour, the large pattern formed on the wafer is surrounded by the contour having a constant width. For example, in this example, each thin wire 110, 120, 210, 22
When the gap between 0 and the contour is 5 μm and the reduction rate during pattern formation is 1/25, the width on the wafer is 0.2 μm.
Is formed, and blurring is suppressed in this contour portion. As a result, the outline blur of the large pattern formed on the wafer is suppressed. As shown by the solid line in FIG. 1 (b), the energy of the shaped electron beam irradiated on the wafer is converged to a region having a width of about 2 μm, and the electron beam shaped by the conventional opening shown by the dotted line is irradiated. As compared with the intensity, the blurring of the pattern in the contour portion is reduced, and the result is that the resolution of the pattern is improved.

FIG. 2 shows the overlapping state of the apertures and the energy intensity of the electron beam with which the wafer is irradiated when a small pattern is formed by the apertures 100 and 200. For example, when forming the opening 160 having a width of 5 μm by the apertures 100 and 200,
As shown in the figure, the gap 111 in the aperture 100 and the gap 221 in the aperture 200 overlap each other to form the opening 160.

The electron beam is shaped through the opening 160, and a pattern reduced to 1/25 is formed on the wafer. That is, a small pattern having a width of 0.2 μm is formed on the wafer. As shown in FIG. 2, when forming a small pattern, as in the case of using a conventional aperture, there is little blurring in the contour portion of the pattern, and a highly accurate pattern is formed on the wafer.

FIG. 3 shows an example of the design pattern in this embodiment. As shown in the figure, the design pattern of this example is composed of a large pattern 170 and a small pattern 180. The large pattern 170 has a width of 2 μm, and the small pattern 180 has a width of 0.2 μm.

FIG. 4 shows the opening 15 shown in FIGS.
The electron beams are shaped by 0 and 160, and the actual patterns 171 and 181 formed on the wafer are shown. As shown in the drawing, the apertures 100 and 200 of the present embodiment improve the resolution of the contour portion of the pattern when a large pattern is formed by providing the electron beam blocking fine lines in each aperture. As a result, even when the large pattern 171 and the small pattern 181 are formed adjacent to each other, these patterns are formed separately from each other. As a result, the accuracy of pattern formation is improved and the yield can be improved.

In the above description, a rectangular pattern has been described as an example, but the present invention is not limited to this, and it can be said that the principle of the present invention can be applied to a pattern other than a rectangular pattern. There is no end. Further, not only one thin line but also one or more thin lines can be provided in the contour portion of the aperture. For example, two slits parallel to the contour can be provided to control the electron beam irradiation energy at the contour of the pattern. This makes it possible to control the irradiation energy intensity of the electron beam at the contour portion of the pattern formed on the wafer with higher accuracy, prevent blurring of the contour portion, and improve the accuracy of the pattern.

Further, according to the present invention, the blurring of the outline portion of the large pattern can be suppressed not only when the large pattern and the small pattern are formed adjacently but also when the plurality of large patterns are formed adjacently. The contact between the patterns can be prevented, and the yield can be improved.

As described above, according to the present embodiment, the thin lines 110 are formed on the contours of the apertures 100, 200.
120, 210, 220 are provided, the aperture 150 is formed by these apertures, the electron beam is shaped by using this, and a pattern is formed. Therefore, blurring of the outline portion in the large pattern can be prevented, and the large pattern can be formed. When the small pattern or the large pattern is formed adjacent to each other, the patterns can be formed separately, the accuracy of pattern formation is improved, and the yield can be improved.

[0032]

As described above, according to the electron beam drawing apparatus of the present invention, it is possible to suppress the outline blur when forming a large pattern, and when forming a large pattern and a small pattern adjacent to each other or between large patterns. When forming adjacently,
There is an advantage that adjacent portions of the pattern can be formed separately, the accuracy of pattern formation can be improved, and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an electron beam writing apparatus according to the present invention, showing an overlapping state of apertures when forming a large pattern.

FIG. 2 is a diagram showing an overlapping state of apertures when a small pattern is formed.

FIG. 3 is a diagram showing a design pattern.

FIG. 4 is a diagram showing a pattern formed by the aperture of the present invention.

FIG. 5 is a configuration diagram showing a configuration of a general electron beam drawing apparatus.

FIG. 6 is a conceptual diagram showing the principle of the variable beam drawing system.

FIG. 7 is a diagram showing an overlapping state of apertures when forming a large pattern.

FIG. 8 is a diagram showing an overlapping state of apertures when a small pattern is formed.

FIG. 9 is a diagram showing a design pattern.

FIG. 10 is a diagram showing a pattern formed by a conventional aperture.

[Explanation of symbols]

10 ... Electron gun, 20 ... First mask, 30 ... Deflector, 40
... second mask, 50 ... objective lens, 60 ... wafer, 2
2, 42, 100, 200 ... Aperture, 110, 12
0, 210, 220 ... Fine wire for blocking electron beam, 111,
121, 211, 221 ... Gap, 70, 170 ... Design large pattern, 80, 180 ... Design small pattern, 71, 17
1 ... Large pattern formed, 81, 181 ... Small pattern formed.

Claims (7)

(57) [Claims] 1. A lens for changing a shape of an electron beam and changing an electron beam according to an overlapping state of a first aperture formed on a first mask and a second aperture formed on a second mask. An electron beam drawing apparatus for irradiating a wafer through a system to form a desired pattern, wherein a line width set according to the resolution on the wafer is set in the contours of the first and second apertures. An electron beam drawing apparatus in which the electron beam blocking thin line is provided, and a line width of the electron beam blocking thin line is set to be equal to or less than a resolution on the wafer. 2. An electron beam which is shaped by changing an electron beam according to an overlapping state of a first aperture formed on a first mask and a second aperture formed on a second mask. An electron beam drawing apparatus for irradiating a wafer through a system to form a desired pattern, wherein a line width set according to the resolution on the wafer is set in the contours of the first and second apertures. An electron beam drawing apparatus in which the electron beam blocking thin line is provided, and the line width of the electron beam blocking thin line is set to a value equal to or less than a value calculated according to the resolution on the wafer and the reduction rate during pattern formation. 3. The electron beam is shaped and shaped by changing the electron beam according to the overlapping state of the first aperture formed on the first mask and the second aperture formed on the second mask. An electron beam drawing apparatus for irradiating a wafer through a system to form a desired pattern, wherein a line width set according to the resolution on the wafer is set in the contours of the first and second apertures. An electron beam drawing apparatus in which a thin wire for blocking the electron beam is provided, and the first and second apertures are rectangular. 4. The electron beam is shaped by changing the electron beam according to the overlapping state of the first aperture formed on the first mask and the second aperture formed on the second mask. An electron beam drawing apparatus for irradiating a wafer through a system to form a desired pattern, wherein a line width set according to the resolution on the wafer is set in the contours of the first and second apertures. An electron beam drawing apparatus having a thin wire for blocking an electron beam, the first and second apertures having a shape other than a rectangle. 5. The electron beam is shaped by changing the electron beam according to the overlapping state of the first aperture formed on the first mask and the second aperture formed on the second mask An electron beam drawing apparatus for irradiating a wafer through a system to form a desired pattern, wherein a line width set according to the resolution on the wafer is set in the contours of the first and second apertures. An electron beam drawing apparatus having an electron beam shut-off thin line that is provided, wherein the electron beam shut-off thin line is formed parallel to a contour of the aperture. 6. The electron beam drawing apparatus according to claim 5, wherein one thin wire for blocking the electron beam is formed in a contour portion of the aperture. 7. The electron beam drawing apparatus according to claim 5 , wherein a plurality of the electron beam blocking fine lines are formed in a contour portion of the aperture.