JP2002353124A - Manufacturing method of mask for charged beam projection exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a mask for charged beam projection exposure, for making the corner shape of the opening pattern of an aperture for drawing to approximate a design pattern as much as possible. SOLUTION: An auxiliary pattern 2 is added to a drawing opening pattern 1, when pattern drawing is carried out to a photosensitive layer by an electron beam in advance, thus obtaining an accurate opening pattern having an extremely small corner R value, when a base is subjected to etching. In this case, the auxiliary pattern 2 relieves the amount of change in the corner shape of an opening pattern due to side etching when a drawing aperture, having the opening pattern, is formed in the base comprising a silicon film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a transfer mask for performing projection exposure using a charged beam used in semiconductor manufacturing.

[0002]

2. Description of the Related Art A lithography system using a charged beam as a projection exposure source has recently attracted attention as a technology for manufacturing a next-generation ultra-fine element. Looking at the flow of technological development so far, first, a pattern that uses a figure repeatedly used in a fine pattern as a basic unit is arranged on a mask, and a partial batch exposure (block Exposure, cell projection exposure, or character projection)
In recent years, an EPL (Electron Beam) method has been proposed, in which a fine pattern divided into a plurality of blocks is arranged on a mask, and a large-capacity charged beam is scanned to connect the divided blocks to perform exposure.
A projection exposure method called “Projection Lithography” has been proposed.

FIG. 7 shows an example of a charged beam projection exposure mask. In general, a charged beam projection exposure mask has a stencil having a drawing aperture in which a square or rectangular opening pattern 62 through which a charged beam passes is formed on a silicon film 61 supported on a support 91 via a silicon oxide film 81. A mold transfer mask is used. This transfer mask is manufactured by processing an SOI (Silicon On Insulator) substrate, and has a thickness of 10 to 20 μm in the partial batch exposure method.
In the EPL method, a silicon film having a thickness of about 2 μm is used. The opening pattern 62 is formed by dry etching a silicon film using a resist pattern formed on the silicon film as a mask.

In the projection exposure method using a charged beam, since a charged beam is formed by a square or rectangular opening pattern of a writing aperture to form a writing pattern, the size and shape of the opening pattern greatly affect writing accuracy. Effect. Therefore, it is necessary to form an opening pattern with high accuracy.

[0005]

In particular, in the case of the partial batch exposure method, the orthogonal corner of the large-area opening pattern is used as an aperture for variable shaping exposure. Therefore, when the corner R value is large, the shape of the transfer pattern becomes large. It will be significantly deteriorated.

A method of forming an opening pattern of a mask for charged beam projection exposure will be described. FIG. 5A is a schematic partial plan view showing a state where a resist pattern 71 having a resist pattern opening 72 is formed on a silicon film 61.
FIG. 5B is a schematic partial cross-sectional view of FIG. 5A taken along the line CC ′. FIG. 6A is a schematic partial plan view showing a state in which the opening pattern 62 is formed in the silicon film 61 by etching the silicon film 61 using the resist pattern 71 as a mask, and FIG.
(A) is a schematic partial sectional view taken along line EE '.

First, a photosensitive layer is formed on the silicon film 61, and a series of patterning processes such as pattern drawing and development are performed to form a resist pattern opening 7 on the silicon film 61.
5 is formed (FIG. 5)
(See (a) and (b)). Next, the resist pattern 71
Is used as a resist mask to etch the silicon film 61 to form a drawing aperture having an opening pattern 62 in the silicon film 61 (see FIGS. 6A and 6B). Depending on the etching method and etching conditions, the four corners of the opening pattern 62 are rounded due to the side etching that proceeds in the horizontal direction with respect to the silicon film surface, depending on the etching method and etching conditions, and the resulting silicon film is obtained as a result. The corner R value of the opening pattern 62 becomes large, which causes a problem in reproducibility of the corner shape of the opening pattern.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing a charged beam projection exposure mask that makes the corner shape of an opening pattern of a drawing aperture as close as possible to a design pattern. .

[0009]

In order to achieve the above object, according to the present invention, there is provided a charged beam projection exposure apparatus having a drawing aperture in which an opening pattern is formed by etching a substrate. A method for manufacturing a mask for charged beam projection exposure, wherein an auxiliary pattern is added in advance to a corner portion of a drawing opening pattern when forming a resist pattern for forming an opening pattern on the base material. Method.

According to a second aspect of the present invention, the auxiliary pattern has an isosceles triangular shape, and the vertex of the isosceles triangle defines the corner angle of the drawing aperture pattern by two.
The distance between the vertex of the isosceles triangle and each side of the drawing aperture pattern is on the extended straight line connecting the equally divided points, and the point at which the two sides of the isosceles triangle intersect each side of the aperture pattern is When the distance to the corner of the drawing opening pattern is B,
The method of manufacturing a mask for charged beam projection exposure, wherein the values of A and B are determined according to the amount of side etching of the substrate.

[0011]

Embodiments of the present invention will be described below. In the method of manufacturing a mask for charged beam projection exposure according to the present invention, when forming a drawing aperture having an opening pattern on a substrate made of a silicon film, the method according to claim 1, wherein a change in corner shape of the opening pattern due to side etching is provided. When a base material is etched by adding an auxiliary pattern that alleviates the patterning to the drawing opening pattern when pattern drawing is performed on the photosensitive layer with an electron beam in advance, the corner R
The aperture value is extremely small and an accurate opening pattern can be obtained.

FIG. 1 is an explanatory view showing an example of a drawing opening pattern 1 to which an auxiliary pattern 2 is added. FIG. 2A is a diagram showing a substrate 11 made of a silicon film using the drawing opening pattern to which an auxiliary pattern is added. FIG. 2B is a schematic partial plan view showing an example in which a resist pattern 21 is formed on the top.
FIG. 2A is a schematic partial cross-sectional view taken along line CC ′, and FIG. 3A shows an embodiment in which an opening pattern 12 is formed in the silicon film 11 by etching the silicon film 11. FIG. 3B is a schematic partial plan view, and FIG.
Is a schematic partial sectional view taken along line EE ′.

In the invention according to claim 2 of the present invention, as shown in FIG. 1, the auxiliary pattern 2 has an isosceles triangular shape, and a vertex 2a of the isosceles triangle is square or rectangular. A point 1b on the extended straight line 3 connecting the corner 1c of the opening pattern 1 and a point obtained by dividing the corner angle into two equal parts, and a point 1b at which two sides of the isosceles triangle intersect with the drawing opening pattern 1
The distance from the corner 1c to B is the vertex 2a of an isosceles triangle.
When the distance from each side of the drawing opening pattern 1 is A, for example, when a 20 μm thick silicon film is used as a base material and the opening width of the drawing opening pattern 1 is 5 μm, as shown in Table 1, What is necessary is just to set the value of A and B of an auxiliary pattern according to the side-etch amount S of a base material. 20 μm
Table 1 shows an example of the relationship between the side etch amount S of the substrate and the auxiliary patterns A and B when the opening width of the drawing aperture pattern is 5 μm using a thick silicon film substrate.

[0014]

[Table 1]

According to Table 1, the side etch amount S of the substrate is 0.1
Assuming that the auxiliary pattern has a thickness of μm, the center values of A and B of the auxiliary pattern are 1.0 μm and 1.5 μm, respectively. Since the size of the auxiliary pattern varies depending on the thickness of the base material, the etching method, and the etching conditions, it is necessary to create the auxiliary pattern each time in a process that is actually used.

The side etch amount S can be obtained by measuring the opening width of the resist pattern before the etching process, and subsequently measuring and subtracting the opening width of the opening pattern of the base material after etching. The corner R value is related as a value that is substantially proportional to the side etch amount.

Next, a resist for electron beam exposure is applied to a substrate 11 made of a silicon film to form a photosensitive layer, and a drawing opening pattern 1 provided with an auxiliary pattern 2 shown in FIG. A resist pattern 21 having an auxiliary pattern 23 and a resist pattern opening 22 on the substrate 11 by performing a series of patterning processes such as
(See FIGS. 2A and 2B). Further, the substrate 11 made of a silicon film is dry-etched by using the resist pattern 21 as a mask, thereby producing a drawing aperture having an opening pattern 12 in the substrate 11 made of a silicon film (FIGS. 3A and 3A). b)), the other silicon material is etched to form a support 41, and the manufacturing method of the present invention having the opening mask 12 in the silicon film 11 supported on the support 41 via the silicon oxide film 51. (FIG. 4)
reference).

[0018]

The present invention will be described in detail with reference to the following examples.
First, a positive electron beam resist PMMA (polymethyl methacrylate) was applied on a 20 μm thick silicon film 11 bonded to a silicon material via a silicon oxide film to form a 0.5 μm thick photosensitive layer. Next, the drawing aperture pattern 1 of 5 μm square shown in FIG.
= Electron beam writing on the photosensitive layer with an electron beam lithography system using a variable shaping method with an accelerating voltage of 20 kV using a writing pattern to which an auxiliary pattern 2 of 1.2 μm is added, development with MIBK (methyl isobutyl ketone), and drying And silicon film 1
A resist pattern 21 having an auxiliary pattern opening 23 and a resist pattern opening 22 was formed on 1 (see FIGS. 2A and 2B).

Next, dry etching was performed using a resist pattern 21 as a mask by a dry etching apparatus using a fluorine-based gas to produce a drawing aperture having an opening pattern 12 in the silicon film 11 (FIG. 3).
(See (a) and (b)).

Next, a protective film is formed on the silicon film on which the opening pattern 12 is formed, and a resist pattern is formed on the other silicon material. The silicon material is etched to remove the protective film and the resist pattern. Thus, a support 41 was formed, and a mask for charged beam projection exposure according to the manufacturing method of the present invention having the opening mask 12 in the silicon film 11 supported on the support 41 via the silicon oxide film 51 was obtained (FIG. 4).

<Comparative Example> First, a photosensitive layer is formed on a silicon film in substantially the same steps as in the embodiment, and a resist pattern is formed by pattern drawing without adding an auxiliary pattern to the drawing opening pattern 1. A drawing aperture having an opening pattern in the silicon film was manufactured by dry etching, and the other silicon material was etched to manufacture a charged beam projection exposure mask of a comparative example.

Table 2 shows the results of measuring the opening pattern shapes of the charged beam projection exposure masks obtained in the examples and comparative examples.

[0023]

[Table 2]

As shown in Table 2, when the auxiliary pattern is added and when the auxiliary pattern is not added, the corner R of the opening pattern is changed.
When the auxiliary pattern was added, the corner R value was 0.2 μm, confirming the effect of the auxiliary pattern.

[0025]

According to the method of manufacturing a charged beam projection exposure mask of the present invention, a resist pattern is formed by adding an auxiliary pattern to an opening pattern to form a resist pattern. Therefore, the corner shape of the opening pattern of the writing aperture is limited. Therefore, the production of a transfer mask having an accurate opening pattern and the transfer exposure of a fine pattern can be easily performed, and the production yield can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a drawing opening pattern to which an auxiliary pattern is added.

FIG. 2A is a schematic partial plan view showing one embodiment in which a resist pattern is formed on a base material made of a silicon film using a drawing opening pattern to which an auxiliary pattern is added. (B) is a schematic partial configuration cross-sectional view of (a) cut along the line CC ′.

FIG. 3A is a schematic partial plan view showing one embodiment in which an opening pattern is formed in a base material formed by etching a base material made of a silicon film. (B) shows (a) as E-E '
FIG. 3 is a schematic partial cross-sectional view taken along a line.

FIG. 4 is a schematic sectional view showing an example of a charged beam projection exposure mask.

FIG. 5A is a schematic partial plan view showing one embodiment in which a resist pattern is formed on a base material made of a silicon film using a drawing opening pattern without adding an auxiliary pattern. (B) is a schematic partial cross-sectional view of (a) taken along the line CC ′.

FIG. 6A is a schematic partial plan view showing an example in which an opening pattern is formed in a base material formed by etching a base material made of a silicon film. (B) shows (a) as E-E '
It is the schematic partial structure sectional drawing cut | disconnected by the line.

FIG. 7 is a schematic sectional view showing an example of a charged beam projection exposure mask.

[Explanation of symbols]

1 ...... Drawing opening pattern 1b ... Point where two sides of an isosceles triangle intersect 1c ... Corner of a square or rectangular drawing opening pattern 2 ... Auxiliary pattern 2a ... Vertex of isosceles triangle 3 ... An extended straight line connecting the corner 1c of the square or rectangular drawing opening pattern 1 and a point obtained by dividing the corner angle into two equal parts 11 Base member 12 Opening pattern 21 Resist pattern 22 Resist pattern opening 23 ... Auxiliary pattern opening 41 ... Support 51 ... Silicon oxide film 61 ... Base material 62 ... Opening pattern 71 ... Resist pattern 72 ... Resist pattern opening 81 ... Silicon oxide film 91 ... Support A ... Distance from vertex 2a of isosceles triangle to each side of drawing aperture pattern 1 B: Point 1b at which two sides of isosceles triangle intersect with drawing aperture The distance between the corner 1c of over down 1

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Kojiro Ito 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Inventor Hironobu Sasaki 1-15-1, Taito, Taito-ku, Tokyo Toppan Inside Printing Co., Ltd. (72) Inventor Hideyuki Eguchi 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. F-term (reference) 2H095 BA01 BA08 BB01 BB31 5F056 AA22 FA10

Claims (2)

[Claims] In a method of manufacturing a charged beam projection exposure mask having a drawing aperture in which an opening pattern is formed by etching a base material, a resist pattern for forming an opening pattern is formed in the base material. A method for manufacturing a mask for charged beam projection exposure, wherein an auxiliary pattern is added in advance to a corner portion of a writing opening pattern. 2. The auxiliary pattern has an isosceles triangle shape, and vertices of the isosceles triangle are on an extended straight line connecting a corner of the drawing opening pattern and a point obtained by dividing the corner angle into two equal parts, When the distance between the vertex of the isosceles triangle and each side of the drawing opening pattern is A, and the distance between the point where the two sides of the isosceles triangle intersects each side of the opening pattern and the corner of the drawing opening pattern is B Wherein the values of A and B are determined in accordance with the amount of side etching of the base material.