JP3893239B2 - Stencil mask and manufacturing method thereof - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an electron beam lithography technique used when manufacturing a semiconductor element. More specifically, the present invention relates to a stencil mask used in an electron beam lithography apparatus and a method for manufacturing the stencil mask.
[0002]
[Prior art]
FIG. 2 is a perspective view for explaining the outline of electron beam exposure (EB exposure), and particularly for explaining the configuration of the batch transfer mask. In FIG. 2, an electron beam generated from an electron gun (not shown) is shaped into a beam that covers the collective transfer region 10 by the first shaping aperture 7 and is applied to the collective transfer region 10 on the stencil mask 9. The electron beam 8 that has passed through the stencil mask 9 transfers the pattern data of the stencil mask 9 onto the wafer 11.
As described above, in the EB projection exposure method and the partial batch EB exposure method, the stencil mask used as the mask has a complete opening portion without any mask material as shown in FIG. Therefore, the electron beam that has passed through the opening is reduced and transferred onto the wafer.
[0003]
In general, an SOI (Si on Insulator) wafer is used as the material of the stencil mask in consideration of the light shielding property of an electron beam and the workability as a mask.
FIG. 3 shows a general flow of manufacturing a stencil mask, and shows an outline of a flow of creating a stencil mask using an SOI wafer. FIG. 3 shows a cross-sectional view of a certain arbitrary batch transfer region in the stencil mask, and a top view seen from the SOI layer side. In this cross-sectional view, the cross section taken along line AB in the top view is taken as a cross-sectional observation position 15.
[0004]
The manufacturing process will be described. First, as shown in FIG. 3A, a wafer in which an SOI layer 12, an insulating film layer 13, and a base wafer layer 14 are laminated is prepared. In general, the base wafer layer 14 is a silicon wafer, and the insulating film layer 13 is a silicon oxide film.
Next, as shown in FIG. 3B, the base wafer layer 14 is etched to open a large opening 14a. In both the EB projection exposure method and the partial batch EB exposure method, the opening region 14a is usually a region that is collectively transferred in one shot.
[0005]
Next, as shown in FIG. 3C, a pattern serving as an electron beam mask is formed in the SOI layer 12. The insulating film layer 13 is used as a stopper film for these Si etches.
Next, as shown in FIG. 3D, after the patterning, the insulating film layer 13 is removed.
[0006]
In general, in these stencil masks, a donut having a structure in which a light shielding pattern portion for shielding an electron beam is surrounded by an opening pattern portion that transmits the electron beam and the light shielding portion floats in the air due to its structure. Structural patterns cannot be produced.
[0007]
FIG. 4 shows a conventional solution for a donut-shaped pattern. 4A, in the batch exposure region 16 having a donut-shaped opening pattern, the island-shaped light shielding pattern 12a of the SOI layer 12 is surrounded by an annular opening pattern 12b. The divided mask 17 is divided into a left half pattern 17a and a right half pattern 17b. Thus, for example, in the EB projection exposure method, the original pattern is obtained by dividing an area that is originally exposed at one time into two or more, drawing each separately separately, and overlaying them on the wafer. The method to take is taken.
[0008]
As another approach, as shown in FIG. 4B, the pattern data of the batch exposure region 16 itself is changed, and the pattern is lost by inserting the beam 12c into the pattern as in the mask 18 after data processing. Prevention is also done.
[0009]
[Problems to be solved by the invention]
Generally, when dividing a place to be drawn at one time into two or more, the number of drawing is substantially increased, resulting in a decrease in throughput. In addition, since the single batch transfer region is divided into two or more, the mask area naturally increases, and the data that can be drawn on one stencil mask decreases. In the EB projection exposure method, the chip area that can be drawn with a single stencil mask is reduced and the throughput is reduced. In the partial batch EB exposure, the throughput is reduced due to the reduction in the number of selectable blocks. It was supposed to decrease. Furthermore, when pattern data is changed, the technical difficulty is high, for example, a data processing system must be established.
[0010]
The present invention has been made in view of the above-described problems of the prior art, and it is possible to arrange donut patterns on a stencil mask without burdening pattern data processing and without reducing the drawing area and throughput. An object is to provide a method for creating such a stencil mask.
[0011]
[Means for solving the problems]
In order to achieve the above object, the present invention has a structure in which an insulating film portion of an SOI wafer, which is a material for a stencil mask, has a beam function, so that data conversion is not performed and throughput and drawing area are reduced. It is possible to arrange a donut pattern on a stencil mask without causing a decrease.
[0012]
The stencil mask of the present invention is a stencil mask used in an electron beam lithography apparatus, and includes an island-shaped light shielding pattern portion having an isolated surface pattern layer and an annular opening pattern portion surrounding the island-shaped light shielding pattern portion. Have. Moreover, the beam-like pattern which is joined to the back of the surface pattern layer is obtained so as to support the light shielding pattern portion.
The stencil mask of the present invention is a stencil mask used in an electron beam lithography apparatus, and the surface pattern layer is made of a silicon layer and is an isolated island-shaped light shielding pattern portion and an annular opening surrounding the island-shaped light shielding pattern portion. And a pattern portion. Moreover, in which so as to support the light shielding pattern portion by the beam-shaped pattern which is joined to the back of the surface pattern layers made of the insulating film layer.
[0013]
The stencil mask of the present invention includes a base wafer having an opening, an insulating film layer formed on the base wafer and having a beam-like pattern in the opening of the base wafer, and on the insulating film layer. And a surface pattern layer having an isolated light shielding pattern supported on the beam-like pattern of the insulating film layer.
The stencil mask of the present invention includes a base wafer having an opening, an insulating film layer formed on the base wafer and having a beam-like pattern in the opening of the base wafer, and on the insulating film layer. And a surface pattern layer having an isolated light-shielding pattern, which is formed of a silicon layer and supported on a beam-like pattern of the insulating film layer.
[0014]
In the stencil mask of the present invention, the beam-like pattern is made to be below the resolution limit of the electron beam drawing apparatus.
[0015]
In the stencil mask of the present invention, the beam-like pattern is a line pattern or a lattice pattern.
[0016]
In the stencil mask manufacturing method of the present invention, an insulating film layer is formed on a base wafer, and a silicon layer is formed thereon. Also, a predetermined opening reaching the insulating film layer is formed in the base wafer. Further, an island-shaped light shielding pattern surrounded by an annular opening pattern is formed in the silicon layer at a position corresponding to the opening of the base wafer. Moreover, and a step of forming a beam-like pattern, wherein the insulating film layer through the opening of the base wafer selectively etched away to hold the island-shaped light shielding pattern.
[0017]
In the stencil mask manufacturing method of the present invention, the beam-like pattern of the insulating film layer is formed below the resolution limit of the electron beam drawing apparatus.
[0018]
In the stencil mask manufacturing method of the present invention, the beam-like pattern of the insulating film layer is formed into a line pattern or a lattice pattern.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a flow of a method for manufacturing a stencil mask according to the present invention. In FIG. 1, a top view shows a view seen from the SOI layer side, and a bottom view shows a view seen from the base wafer side. The cross-sectional view shows a cross section viewed from the cross-section observation position 6 along the line AB in the top view and the bottom view.
[0020]
The manufacturing process will be described. First, FIG. 1A shows an SOI wafer to be a stencil mask material. The SOI wafer includes an SOI layer 1, an insulating film layer 2, and a base wafer 3.
Next, as shown in FIG. 1B, a batch transfer opening region 4 is formed in the base wafer 3 by etching. At this time, the insulating film layer 2 acts as an etching stopper.
[0021]
Next, as shown in FIG. 1C, a pattern is formed in the SOI layer 1 by selective etching. This pattern includes an isolated island-shaped pattern 1a formed at a position corresponding to the collective transfer opening region 4 and an opening pattern 1b surrounding the island-shaped pattern 1a.
Next, as shown in FIG. 1D, the insulating film layer 2 is selectively etched from the opening 4 side to leave a part of the insulating film layer 2 and form a beam pattern 5.
[0022]
As described above, in this embodiment, the beam pattern 5 is formed by selectively leaving the insulating film layer 2 after the surface pattern is formed. In order to form the beam pattern 5, resist patterning by an exposure apparatus and etching using the resist pattern as a mask are performed. For simplicity, the state after etching is shown.
[0023]
The pattern data used for this beam can be the same data for all stencil masks used in drawing devices with the same resolution, or simple line / space (L / S) or lattice data. Therefore, it does not impose a load such as data conversion.
Furthermore, since the pattern to be left as a beam is a size that can be patterned by light exposure, it is possible to handle many stencil masks by creating only one reticle when patterning using an optical stepper. It is.
[0024]
By adopting such a structure, the insulating film portion left selectively forms the beam pattern 5, and serves as a beam for holding the light shielding pattern portion 1a surrounded by the opening pattern portion 1b. It is possible to create a donut-shaped pattern in which 1a floats in the air on a stencil mask without performing data processing or the like.
Moreover, patterning performance is not impaired by making the pattern used as a beam below the resolution limit of the exposure apparatus in which the corresponding stencil mask is used.
In FIG. 1, a vertical line / space (vertical L / S) is used as the beam pattern 5 of the insulating film layer 2. However, a horizontal L / S or a lattice pattern may be used.
[0025]
As described above, according to the present invention, a stencil mask used in an electron beam lithography apparatus, which includes a substrate (base wafer 3) having an opening 4 and the base wafer 3 formed on the base wafer 3. The surface having the insulating film layer 2 having the beam-like pattern 5 in the opening 4 and the light-shielding pattern portion 1a formed on the insulating film layer 2 and isolated on the beam-like pattern 5 of the insulating film layer 2 And a pattern layer (SOI layer 1).
[0026]
Further, as described above, in the stencil mask manufacturing method of the present invention, the predetermined opening 4 reaching the insulating film layer 2 is formed in the base wafer 3 using an SOI wafer. An island-shaped light shielding pattern 1 a surrounded by an annular opening pattern 1 b is formed in the silicon layer 1 at a position corresponding to the opening 4 of the base wafer 3. Further, the insulating film layer 2 is selectively etched away from the opening 4 of the base wafer 3 to form a beam-like pattern 5 that holds the island-like light-shielding pattern 1a.
[0027]
【The invention's effect】
According to the present invention, in a batch transfer region of a stencil mask used in an electron beam drawing apparatus or the like, the light shielding pattern portion for shielding the electron beam is surrounded by the opening pattern portion that transmits the electron beam, and the light shielding portion is suspended. A so-called donut-shaped pattern can be formed. Therefore, it greatly contributes to improving the throughput of EB projection exposure and partial batch EB exposure.
[Brief description of the drawings]
FIG. 1 is a diagram showing a manufacturing flow of a stencil mask in the present invention.
FIG. 2 is a perspective view showing a schematic configuration of a general electron beam drawing apparatus and a batch transfer mask.
FIG. 3 is a diagram showing a manufacturing flow of a general stencil mask.
FIG. 4 is a diagram showing how to deal with an isolated pattern using a conventional stencil mask.
[Explanation of symbols]
1 SOI layer, 1a island pattern, 1b opening pattern, 2 insulating film layer, 3 base wafer, 4 opening area, 5 beam pattern.

Claims (9)

A stencil mask used in an electron beam lithography apparatus, comprising a surface pattern layer having an isolated island-shaped light shielding pattern and an annular opening pattern surrounding the island-shaped light shielding pattern, and the back surface of the light shielding pattern A stencil mask comprising a beam-like pattern bonded to the back surface of the surface pattern layer and supporting the light shielding pattern. A stencil mask used in an electron beam lithography apparatus, comprising a surface pattern layer having an isolated island-shaped light shielding pattern made of a silicon layer and an annular opening pattern surrounding the island-shaped light shielding pattern, and an insulating film layer A stencil mask comprising: a beam-like pattern bonded to the back surface of the surface pattern layer including the back surface of the light shielding pattern and supporting the light shielding pattern. A stencil mask used in an electron beam lithography apparatus, comprising: a base wafer having an opening; an insulating film layer formed on the base wafer and having a beam-like pattern in the opening of the base wafer; and the insulating film A stencil mask comprising: a surface pattern layer having an isolated light shielding pattern formed on a layer and supported on a beam-like pattern of the insulating film layer. A stencil mask used in an electron beam lithography apparatus, comprising: a base wafer having an opening; an insulating film layer formed on the base wafer and having a beam-like pattern in the opening of the base wafer; and the insulating film A stencil mask comprising: a surface pattern layer having an isolated light-shielding pattern formed from a silicon layer on the layer and supported on the beam-like pattern of the insulating film layer.   The stencil mask according to any one of claims 1 to 4, wherein the beam-like pattern is set to a resolution limit or less of an electron beam drawing apparatus.   The stencil mask according to any one of claims 1 to 5, wherein the beam-like pattern is a line pattern or a lattice pattern. Forming an insulating film layer on the base wafer and forming a silicon layer thereon;
Forming a predetermined opening reaching the insulating film layer in the base wafer;
Forming an island-shaped light shielding pattern surrounded by an annular opening pattern in the silicon layer at a position corresponding to the opening of the base wafer;
And a step of selectively etching away the insulating film layer from the opening of the base wafer to form a beam-like pattern that retains the island-shaped light-shielding pattern.   8. The method for manufacturing a stencil mask according to claim 7, wherein the beam-like pattern of the insulating film layer is formed below a resolution limit of an electron beam lithography apparatus.   9. The method for manufacturing a stencil mask according to claim 7, wherein the beam-like pattern of the insulating film layer is formed into a line pattern or a lattice pattern.

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