JP2783279B2 - Stencil mask for charged beam and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to charged beam lithography in an LSI manufacturing process.
The present invention relates to a stencil mask for a charged beam used in a partial batch writing method and a method for manufacturing the same.

[0002]

2. Description of the Related Art The partial batch drawing method is a method of drawing a pattern by using a charged beam 8 shaped by a charged beam stencil mask 51 which is opened in a desired figure as schematically shown in FIG. . More specifically, the charged beam emitted from the electron gun 7 passes through the first aperture 9, passes through the forming section composed of the pair of forming lenses 10, 10 sandwiching the forming deflector 11, and then enters the charged beam stencil. The light is incident on the mask 51. This is a method in which a charged beam stencil mask 51 is shaped into a desired figure shape, and is incident on a sample through a reduction lens 12, a positioning deflector 13, and an objective lens. In FIG. 3, the pattern formed by the stencil mask 51 for the charged beam is incident on the hatched portion of the sample 15. Therefore, the resist pattern shape is greatly affected by the processing accuracy of the mask having the desired figure shape.

However, for example, in order to block electrons accelerated to 50 keV with silicon, which is a typical material of a stencil mask for a charged beam, a film thickness of 20 μm is required. Is very difficult to process because it must be etched by 20 μm.

Further, in order to simultaneously etch opening patterns of various shapes and areas existing on a mask,
Differences in etching rate and direction occur, and the pattern opening shape varies.

FIG. 4A is a top end view showing an example of a conventional charged beam stencil mask, and FIG.
It is sectional drawing which follows the AA 'line of (a). As shown in FIGS. 4A and 4B, a 100 μm square opening 52 a, a 10 μm square opening 52 b, and a polygonal opening 52 c having a region of about 10 μm × 100 μm are provided in the stencil mask 51 a for the charged beam. Exist at the same time. When manufacturing such a stencil mask 51a for a charged beam, the etching reactant 60 is less likely to enter the bottom of the opening in a small opening, for example, 52c, after etching, so that etching is difficult.

On the other hand, a large opening, eg, 52a,
Conversely, since etching is fast, a sufficiently thick etching stopper has to be provided at the bottom in consideration of the difference in etching rate. Figure 5 shows how to improve the processing accuracy.
This will be described with reference to (a) and (b).

FIG. 5A is a top end view showing another example of a stencil mask for a charged beam, and FIG. 5B is a view showing FIG.
It is sectional drawing in alignment with the BB 'line of FIG. As shown in FIGS. 5A and 5B, the stencil mask 5 for the charged beam is used.
As for 1b, a method of making the etching rate of the large-area opening 52a close to that of the small-area opening 52b by etching the contour 53a of the large-area opening 52a can be considered.

[0008]

FIG. 4 (a)
Even if a sufficiently thick stopper is placed at the bottom by the conventional method described with reference to (b), a large-area opening 52a and a small-area opening 52b are formed due to a microloading effect due to a difference in etching rate. The side wall shape was different, and the dimensions of the opening could not be made as designed.

For example, when the opening 52b of 10 μm square is opened vertically, the opening 52a of 100 μm square and the area 10 μm are formed.
The polygonal opening 52c of about m × 100 μm can be made smaller than the designed size at the bottom of the opening.

Therefore, as described with reference to FIGS.
When the contour 53a of the m-shaped opening 52a is etched, it is possible to suppress variations in the side wall shape of the large-area opening 52a and the small-area opening 52b, and to make the dimension of the opening close to the design value. This cannot be applied when accuracy is required due to the shape of the opening. That is, the side wall shape of the opening is different due to the difference in pattern shape between the opening 52b of 10 μm square and the polygonal opening 52c of about 10 μm × 100 μm. In addition, the side wall shape of the vertical edge and the side wall shape of the horizontal edge of the polygonal opening 52c having a region of about 10 μm × 100 μm are different.

Therefore, as shown in FIGS. 6A and 6B, for example, as shown in the top end view of the charged beam stencil mask 51c and the sectional view taken along the line CC ', the contours of the openings of all the patterns are shown. A method of etching the portions 53a, 53b and 53c can be considered. However, it becomes difficult for etching reaction species to enter, and products are difficult to come out, so that the etching rate decreases and the opening shape also deteriorates. In particular, when the opening shape is complicated, since the length of the straight line of the contour varies, the side wall shape and dimensional accuracy of the openings 52a, 52b, and 52c vary.

In this case, the contours 53a, 53b,
It is difficult to remove the internal pattern by etching only 53c, so that a stencil mask is produced and the yield is reduced.

[0013] Therefore, a technical problem of the present invention is to make it easier to form an opening, to improve the controllability of the side wall size of the opening, and to suppress a decrease in throughput and a decrease in yield. A stencil mask and a method for manufacturing the stencil mask are provided.

[0014]

According to the present invention, there is provided a stencil mask for a charged beam having an opening opened in an arbitrary figure shape used in a partial batch writing method using a beam, wherein the opening is separated from the stencil mask. A stencil mask for a charged beam is obtained, characterized in that it comprises at least two island-shaped patterns formed as possible.

According to the present invention, in a method of manufacturing a stencil mask for a charged beam used in a partial batch writing method using a beam and having an opening formed in an arbitrary figure shape, at least the inside of the opening is provided. A method for manufacturing a stencil mask for a charged beam characterized by forming two island patterns is obtained.

That is, in the present invention, in etching a pattern opening in the fabrication of a stencil mask for a charged beam, attention is paid to the fact that the side wall shape and dimensional accuracy of the opening depend on the area and shape of the etched portion. Part, and etch the outline of the divided area,
The area and the shape of the etched portion are constant or similar regardless of the shape of the opening pattern.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A is a plan view showing a stencil mask for a charged beam according to a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line DD 'in FIG. 1A. It is sectional drawing which follows. 1 (a) and 1 (b), openings 2a, 2b, 2 on a stencil mask 1 for a charged beam.
This shows a state where the contour portions 3a, 3b, and 3c have been etched using the contour portions 3a, 3b, and 3c as etching regions to form the pattern c. Openings 2a, 2b, 2 of various sizes and shapes
As shown in FIG. 1 (a),
It is divided into island-shaped patterns 5a having the same shape. The shape of the island pattern 5a is the same regardless of the opening pattern.
The reason why the island-shaped pattern 5b at the center of the relatively large opening 2a is large is that the processing accuracy and the yield can be sufficiently improved in the peripheral etching region 3a (the divided region is about a small opening). The line widths of the etching regions 3a, 3b, 3c are the same, and the shapes and sizes of the island-like patterns 5a, 5b are the same under the constraints of the size and shape of the patterns existing on the mask. It is optimized along with the line width depending on the choice, etching shape and ease of removal.

Here, FIG. 1 shows a case in which all the line widths are matched, but if it is desired to change the shape of the pattern of a part of the opening as required, another line width or an island-like pattern may be used. Can be controlled by changing the shape of. Further, the shape of the edge of the opening can also be controlled. For example, it is possible to make a certain opening smaller than required by design.

FIG. 2 is a sectional view schematically showing an opening formed in the charged beam stencil mask 1 according to the embodiment of the present invention. The charged beam stencil mask 1 is usually etched using a Si oxide film processed to a desired design dimension as a mask. As shown in FIG. 2, since the etching is performed with the same line width, the side walls of the openings 2d, 2e, and 2f after the etching all have the same tapered shape. However, it is also possible to make the shape of the side wall of the opening inversely tapered, that is, to make the taper angle 90 degrees or more by determining the line width of the etching region.

As described above, in the embodiment of the present invention, a high dimensional accuracy can be obtained by making the area and shape of the etched portion constant irrespective of the pattern shape of the opening. Further, even when the shape of the opening is complicated, not only high dimensional accuracy can be obtained by making the size and shape of the island pattern suitable, but also it becomes easy to remove the island pattern in the opening. In addition, the divided island-shaped pattern facilitates the entry and exit of etching reaction species and products, thereby increasing the etching rate.
Throughput and aperture shape are improved.

[0022]

As described above, according to the present invention, by removing the contour of the divided island-like pattern in the opening by etching, the micro-loading effect is suppressed and the island-like pattern can be removed without lowering the etching rate. A stencil mask for a charged beam and a method of manufacturing the same that can facilitate fabrication of an opening by improving simplicity, improve dimensional control of a sidewall of the opening, and suppress a decrease in throughput and a decrease in yield. Can be provided.

[Brief description of the drawings]

FIG. 1A is a plan view showing a stencil mask for a charged beam according to an embodiment of the present invention. (B) is sectional drawing which follows the DD 'line of (a).

FIG. 2 is a sectional view showing a shape of a side wall of an opening of the charged beam stencil mask of FIG. 1;

FIG. 3 is a diagram illustrating the principle of a conventional partial batch drawing method.

FIG. 4A is a top end view showing an example of a conventional charged beam stencil mask. (B) is A- of (a).
It is sectional drawing which follows the A 'line.

FIG. 5A is a top end view showing another example of a conventional charged beam stencil mask. (B) is B in (a)
It is sectional drawing which follows the -B 'line.

FIG. 6A is a top end view showing another example of a conventional charged beam stencil mask. (B) is C in (a)
It is sectional drawing which follows the -C 'line.

[Explanation of symbols]

 1, 51 Stencil mask for charged beam 2a, 2b, 2c, 52a, 52b, 52c Opening 3a, 3b, 3c Contour (etching region) 5a, 5b Island pattern 7 Electron gun 8 Charge beam 9 First aperture 10 Molding Lens 11 Molding deflector 12 Reduction lens 13 Positioning deflector 14 Objective lens 15 Sample 53a, 53b, 53c Contour 60 Etching reactive species

Claims (13)

(57) [Claims] 1. A charged beam stencil mask provided with an opening having an arbitrary figure shape used in a partial batch writing method using a beam, wherein said opening is formed in at least two islands formed so as to be detachable. A stencil mask for a charged beam, characterized by having a shape pattern. 2. The stencil mask for a charged beam according to claim 1, wherein the area and the shape of the island pattern are specified according to the area and the shape of the opening. . 3. The stencil mask for a charged beam according to claim 1, wherein each of the island-shaped patterns in the opening has the same area and shape. 4. The stencil mask for a charged beam according to claim 1, wherein the shape of the island pattern is rectangular. 5. The stencil mask for a charged beam according to claim 1, wherein the width of an etching region generated between a side wall of the opening and the island pattern is constant in the opening. Characterized in that the area and shape of the stencil are determined. 6. The stencil mask for a charged beam according to claim 1, wherein an area of the island pattern is such that a width of an etching region generated between the island patterns of the opening is constant in the opening. And a stencil mask for a charged beam, the shape of which is determined. 7. A method of manufacturing a stencil mask for a charged beam used in a partial batch writing method using a beam and having an opening formed in an arbitrary figure shape, wherein at least two island-like patterns are formed in the opening. A method for manufacturing a stencil mask for a charged beam, comprising: 8. The stencil for a charged beam according to claim 7, wherein the area and the shape of the island pattern are specified according to the area and the shape of the opening. Manufacturing method of mask. 9. The method of manufacturing a stencil mask for a charged beam according to claim 7, wherein the area and the shape of the island pattern in the opening are made to match each other. 10. The method of manufacturing a stencil mask for a charged beam according to claim 7, wherein the shape of the island pattern in the opening is rectangular. 11. The method of manufacturing a stencil mask for a charged beam according to claim 7, wherein the width of an etching region generated between each of the island patterns in the opening is constant in the opening. A method for manufacturing a stencil mask for a charged beam, comprising determining an area and a shape of a pattern. 12. The method of manufacturing a stencil mask for a charged beam according to claim 7, wherein the width of an etching region generated between a side wall in the opening and the island pattern is constant in the opening. A method for manufacturing a stencil mask for a charged beam, comprising determining an area and a shape of a shape pattern. 13. The method for manufacturing a stencil mask for a charged beam according to claim 7, wherein the width of a predetermined etching region is changed to form a desired island-shaped side wall shape. A method for manufacturing a stencil mask.