JPH06332153A - Method for correcting defective mask - Google Patents

Abstract

PURPOSE:To provide a method for correcting a defective mask by which the size of a defect correction part and the arrangement of the defect correction part are optimized and the defect correction part is positioned by giving some margin. CONSTITUTION:A defect correction area 48 provided with a rectangular plane pattern is formed and distances (W1 and L) between faced correction edges 50 are set to be >=1mum being such a distance that mutual light interference can be ignored. Besides, the shortest distance between the edges 50 and the edge 46 of the pattern is set to be >=1mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of repairing defects generated in a phase shifter of a phase difference mask used for high resolution lithography.

[0002]

2. Description of the Related Art A phase shifter will now be described with reference to the drawings.
A conventional mask defect repairing method in the case of a void type defective portion having a non-planar bottom surface will be described.

FIGS. 5A and 5B are cross-sectional views of a phase difference mask for explaining a conventional mask defect repairing method. FIG. 5A is a partial cross-sectional view of the retardation mask having an uncorrected defective portion. FIG. 5B is a partial cross-sectional view of the retardation mask after the defective portion is corrected.

In this conventional phase difference mask, a conductive layer 12 is provided on a mask substrate 10, and a light shielding pattern 14 is provided thereon. Then, in the phase shifter 16 provided on the light-shielding pattern 14 and the conductive layer 12, a void-shaped defective portion 18 having a non-planar bottom surface is generated.

In the conventional mask defect correction method, the defect portion 1
On the phase shifter 16 portion in the region including 8, the transparent film 20 having a thickness such that the phase angle of the transmitted light with respect to the incident light is 2π is formed to correct the mask defect.

[0006]

However, in the above-described mask defect repairing method, the light intensity of the transmitted light of the phase difference mask changes depending on the size of the repair pattern.
Therefore, there is a problem in that the light intensity extremely decreases depending on the size of the correction pattern, and as a result, defective transfer including unnecessary protrusions occurs in the transfer pattern.

Further, in the case of embedding in the defective portion, high accuracy is required for the alignment between the defective portion and the embedded portion.

Therefore, a first object of the present invention is to provide a mask defect repairing method in which the size of the defect repairing part and the layout of the defect repairing part are optimized.

A second object of the present invention is to provide a mask defect repairing method in which there is a margin in the alignment of the defect repairing portion.

[0010]

In order to achieve this object, according to the first invention of this application, in repairing a defect portion generated in the phase shifter of the phase difference mask, the defect correction areas are opposed to each other. The distance between the correction edges to be set is a distance at which optical interference between the correction edges can be ignored, and
The shortest distance between the correction edge of the defect correction area and the pattern edge of the light-shielding pattern of the phase difference mask is set to a distance at which optical interference between the correction edge and the pattern edge can be ignored.

Further, in carrying out the first aspect of the invention, the shortest distance between the defect edge of the defect portion and the repair edge is so small that the effect of the defect edge and the repair edge on the optical interference can be ignored. The shorter the better.

Further, according to the second aspect of the present application, in repairing a defective portion generated in the phase shifter of the phase difference mask, the distance between the facing repair edges of the defect repaired area is determined by the correction edges. It is characterized in that the optical interference due to is set to a negligible distance, and at least a part of the correction edge is overlapped with the light shielding pattern of the phase difference mask.

[0013]

According to the mask defect repairing method of the first invention of this application, the distance between the opposing repair edges of the defect repair area and the shortest distance between the pattern edge and the repair edge of the light-shielding pattern of the phase difference mask. The defect correction area is formed with a distance such that the influence of optical interference between the edges can be ignored. However, this distance is determined by the optical system using the retardation mask (for example, the numerical aperture and the coherence factor) and the light source light wavelength.

Therefore, not only the corrected edges but also
It is possible to prevent the reduction of the light intensity of the transmitted light due to the light interference between the modified edge and the pattern edge. Further, since the defect correction area is formed regardless of the size of the defect portion, the accuracy of alignment of the defect correction area can be reduced as compared with the conventional example. The repairing method of the first invention is particularly suitable for use when the distance between the defect edge of the defective portion and the pattern edge is longer than the distance at which optical interference between the edges can be ignored.

Further, in the mask defect repairing method of the first invention, the shortest distance between the defect edge and the repair edge is set shorter than the distance at which the effect of the defect edge and the pattern edge on the optical interference becomes small enough to be ignored. A correction area can also be formed. Therefore, it is possible to allow the defective portion and the repaired portion to be aligned with each other. This forming method is particularly suitable for forming a defect correction region when the distance between the defect edge of the defective portion and the pattern edge is slightly shorter than the distance at which optical interference between the edges is negligible.

Further, according to the mask defect repairing method of the second invention of this application, the distance between the opposing repair edges of the defect repair area is set to a distance at which optical interference between the edges can be ignored, and the repair edge At least a part is overlapped with the light shielding pattern of the retardation mask to form a defect correction area.

Therefore, not only the corrected edges but also
It is possible to prevent the reduction of the light intensity of the transmitted light due to the light interference between the modified edge and the pattern edge. Further, since the defect correction area is formed regardless of the size of the defect portion, the accuracy of alignment of the defect correction area can be reduced as compared with the conventional example. The repairing method of the second invention is particularly suitable for use when the distance between the defect edge of the defective portion and the pattern edge is shorter than the distance at which optical interference between the edges can be ignored.

Next, referring to FIG. 4, the relationship between the distance between edges and optical interference will be described. FIG. 4 is a graph showing the results of measuring the relationship between the distance between the opposite correction edges of the correction area of the retardation mask and the light intensity of the transmitted light of the retardation mask.

The horizontal axis of the graph represents the distance between the facing correction edges of the correction area, and the vertical axis of the graph represents the light intensity of the transmitted light as a light intensity ratio with the light intensity of the incident light as 1. .
At the time of measurement, the condition of the optical system is numerical aperture NA = 0.5,
The coherence factor was set to σ = 0.5, and the retardation mask was irradiated with i-line of a mercury lamp as a light source. In addition, the light intensity of the transmitted light was measured at the central portion between the correction edges. The measurement result under these conditions is shown by curve I in the graph.

As shown by the curve I, the light intensity ratio is lowered when the distance between the correction edges is in the range of 0.05 to 1.0 μm. In particular, when the distance between the correction edges is near 0.2 μm, it is found that the light intensity of the transmitted light is significantly reduced due to the optical interference between the correction edges.

On the other hand, when the distance between the correction edges is 1.0 μm or more, the light intensity of the transmitted light is hardly reduced. Therefore, it is understood that when the distance between the correction edges is 1.0 μm or more, the optical interference between the correction edges can be ignored.

The distance between the modified edges is 0.05 μm.
Also in the following cases, the light intensity of the transmitted light is hardly reduced. Therefore, it is understood that when the distance between the correction edges is set to 0.05 μm or less, the influence of optical interference between the correction edges becomes small enough to be ignored.

Also, regarding the distance between the correction edge and the pattern edge and between the correction edge and the defect edge, if the distance between the edges is 1 μm or more under the above-mentioned optical system conditions,
Similar to the measurement result described above, the influence of optical interference on the transmitted light can be ignored.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the invention according to this application will be described below with reference to the drawings. The figures referenced below are
The sizes, shapes, and positional relationships of the respective constituents are only schematically shown so that each invention can be understood. Therefore, it is obvious that the present invention is not limited to the illustrated examples. In the figure, hatching and the like showing the cross section are partially omitted.

Further, the phase difference mask for correcting defects in each of the following examples has the same optical system (NA = 0.5, σ = 0.5) as in the case of performing the measurement whose measurement results are shown in FIG. ) And a light source (i-line of a mercury lamp).

First Embodiment Hereinafter, the first invention according to this application will be described as a first embodiment. 1A to 1D are correction process diagrams for explaining the first embodiment. FIG. 1A is a partial plan view of a retardation mask having an uncorrected defect portion. 1B is a cross-sectional view taken along line AA of FIG. FIG. 1C is a partial plan view of the retardation mask in which the defective portion is corrected. FIG. 1D is a sectional view taken along line BB of FIG.

In the retardation mask shown in FIGS. 1A and 1B, the conductive layer 32 is provided on the mask substrate 30, and the light shielding pattern 34 is provided on a part of the conductive layer 32. Then, the conductive layer 32 and the light shielding pattern 34
A phase shifter 38 having a defective portion 36 and non-defective phase shifters 40 and 42 are formed on the upper portion. These phase shifters 38, 40 and 42 are used for the light-shielding pattern 34.
Adjacent above.

In the first embodiment, the shortest distance between the defect edge 44 of the defect portion 36 and the pattern edge 46 of the light-shielding pattern 34 is longer than the distance by which optical interference between the defect edge 44 and the pattern edge 46 can be ignored. A defective portion 36 is generated at the position.

Defect repair area 4 for repairing this defective portion 36
8 is formed, the distance (W1 and L) between the opposing repair edges 50 of the defect repair area 48 is set to a distance at which optical interference between the repair edges 50 can be ignored, and the repair edge of the defect repair area 48 is 50 and the shortest distance between the pattern edge 46 of the light shielding pattern 34 (W2)
Is a distance at which optical interference between the modified edge 50 and the pattern edge 46 can be ignored ((C) and (D) in FIG. 1).

Therefore, in the first embodiment, the defect repair area 48 having a rectangular plane pattern is formed, and the distance (W1 and L) between the repair edges 50 facing each other is 1 μm.
m or more. In addition, the shortest distance between the modified edge 50 and the pattern edge 46 is 1.0 μm or more.

As described above, in the mask defect repairing method of the first embodiment, not only the repair edges 50 but also the light intensity of the transmitted light due to the light interference between the repair edges 50 and the pattern edges 46 can be prevented. . In addition, the defective portion 3
Since the defect correction area 48 is formed regardless of the size of 6, the accuracy required for the alignment of the defect correction area 48 can be reduced and a margin can be provided for the alignment as compared with the conventional example.

Second Embodiment A second embodiment of the first invention according to this application will be described below. FIG. 2 is a partial plan view of the retardation mask in which the defective portion is corrected.

In the retardation mask shown in FIG. 2, the phase shifter 38 having the defective portion 54 and the non-defective phase shifters 40 and 42 are formed similarly to the retardation mask of the first embodiment. These phase shifters 38, 40 and 42 are adjacent to each other on the light shielding pattern 34.

Defect portion 54 of the retardation mask of the second embodiment.
Is the defect edge 56 and the pattern edge 4 of the light-shielding pattern.
6 is the shortest distance from the defect edge 56 and the pattern edge 4
It occurs at a position slightly shorter than the distance where the mutual optical interference caused by 6 and 6 can be ignored.

In order to repair the defective portion 54, in the second embodiment, as in the first embodiment, a defect repair area 58 having a rectangular plane pattern is formed, and an opposing repair edge 60 is formed. The distance (W1 and L) between them is 1 μm or more. In addition, the shortest distance between the modified edge 60 and the pattern edge 46 is 1.0 μm or more. However, in the second embodiment, the defect correction region 58 is formed by embedding in the defect portion 54. At this time, the shortest distance between the defect edge 56 of the defect portion 54 and the repair edge 60 of the defect repair area 58 is set to such a distance that the effect of the defect edge 56 and the repair edge 60 on the optical interference becomes negligible. Yes 0.05
Shorter than μm (Fig. 2).

Third Embodiment Hereinafter, the second invention according to this application will be described as a third embodiment. FIGS. 3A to 3D are correction process diagrams for explaining the third embodiment. FIG. 3A is a partial plan view of the retardation mask having an uncorrected defect portion. 3B is a cross-sectional view taken along the line C-C in FIG. FIG. 3C is a partial plan view of the retardation mask in which the defective portion is corrected. 3D is a cross-sectional view taken along the line D-D in FIG.

In the retardation mask shown in FIGS. 3A and 3B, the conductive layer 32 is provided on the mask substrate 30, and the light shielding pattern 34 is provided on a part of the conductive layer 32. Then, the conductive layer 32 and the light shielding pattern 34
The phase shifter 38 having the defective portion 62 and the non-defective phase shifters 38 and 40 are formed on the upper portion. The phase shifters 38, 40 and 42 are adjacent to each other on the light shielding pattern.

In the retardation mask of the third embodiment, the defective portion 6
The defect portion 62 occurs at a position where the shortest distance between the defect edge 64 of No. 2 and the pattern edge 46 of the light-shielding pattern 34 becomes shorter than the distance at which optical interference between the defect edge 64 and the pattern edge 46 can be ignored. ing.

Defect repair area 6 for repairing this defective portion 62
6 is formed, the distance between the correction edges 68 (W1 and L) facing each other in the defect correction area 66 is set to a distance at which optical interference between the correction edges 68 can be ignored, and at least a part of the correction edge 68 is formed. Shading pattern 3
The defect correction area 66 is formed so as to overlap 4.

Therefore, in the third embodiment, the defect correction area 66 having a rectangular plane pattern is formed, and the distance (W1 and L) between the opposed correction edges 68 is set to 1 μm.
m or more. In addition, one correction edge 68 is overlapped on the light shielding pattern 34 ((C) and (D) of FIG. 3).

As described above, according to the mask defect repairing method of the third embodiment, it is possible to prevent not only the repaired edges 68 but also the light intensity of the transmitted light from being lowered due to the light interference between the repaired edges 68 and the pattern edge 46. . In addition, the defective portion 6
Since the defect correction area 66 is formed regardless of the size of 2, it is possible to reduce the alignment accuracy of the defect correction area 66 as compared with the conventional example.

In each of the above-mentioned embodiments, the invention according to this application was described by using the specific material and under the specific condition. However, the invention is not limited to these and many Can be changed and modified. For example, in each of the above-described embodiments, the conductive layer is provided on the retardation mask, but the conductive layer is not always necessary in the present invention.

Further, in each of the above-mentioned embodiments, the correction area having the rectangular plane pattern is formed, but in the present invention, the plane pattern of the correction area has an arbitrary shape according to the design, for example, an ellipse, a triangle or the like. The polygon can be a general arbitrary shape as well as the polygon.

Further, in each of the above-mentioned embodiments, the phase difference mask when used in a specific optical system and a light source has been described. However, in the present invention, even when it is used in another optical system and a light source, it has an appropriate size. A defect correction area can be formed.

[0045]

According to the mask defect repairing method of the first invention of the present application, the distance between the repairing edges facing each other in the defect repairing area, the repairing edge, and the pattern edge of the light-shielding pattern of the phase difference mask By forming a defect repair area in which the shortest distance from the repair edge is a distance at which the influence of optical interference between the edges can be ignored, the size and placement of the repair area are static. However, this distance is determined by the optical system using the retardation mask (for example, the numerical aperture and the coherence factor) and the light source light wavelength.

Therefore, not only the corrected edges but
It is possible to prevent the reduction of the light intensity of the transmitted light due to the light interference between the modified edge and the pattern edge. Further, since the defect correction area is formed regardless of the size of the defect portion, the accuracy of alignment of the defect correction area can be reduced as compared with the conventional example. The repairing method of the first invention is particularly suitable for use when the distance between the defect edge of the defective portion and the pattern edge is longer than the distance at which optical interference between the edges can be ignored.

Further, in the mask defect repairing method of the first invention, the shortest distance between the defect edge and the repair edge is set shorter than the distance at which the effect of the defect edge and the pattern edge on the optical interference becomes negligible. A correction area can also be formed. Therefore, it is possible to allow the defective portion and the repaired portion to be aligned with each other. This forming method is particularly suitable for forming a defect correction region when the distance between the defect edge of the defective portion and the pattern edge is slightly shorter than the distance at which optical interference between the edges is negligible.

According to the mask defect repairing method of the second invention of this application, the distance between the opposing repair edges of the defect repair area is set to a distance at which optical interference between the edges can be ignored, and By optimizing at least a part of the defect correction region by overlapping the light shielding pattern of the retardation mask, the size and arrangement of the correction region are optimized.

Therefore, not only the corrected edges but also
It is possible to prevent the reduction of the light intensity of the transmitted light due to the light interference between the modified edge and the pattern edge. Further, since the defect correction area is formed regardless of the size of the defect portion, the accuracy of alignment of the defect correction area can be reduced as compared with the conventional example. The repairing method of the second invention is particularly suitable for use when the distance between the defect edge of the defective portion and the pattern edge is shorter than the distance at which optical interference between the edges can be ignored.

[Brief description of drawings]

FIG. 1A to FIG. 1D are correction process diagrams for explaining a first embodiment. (A) is a partial plan view of a retardation mask having an uncorrected defect portion. (B) is a sectional view taken along the line AA of (A). (C) is a partial plan view of a retardation mask in which a defective portion is corrected. (D) is
It is sectional drawing in BB of (C).

FIG. 2 is a partial plan view of a retardation mask in which a defective portion is corrected, which is used for explaining a second embodiment.

FIG. 3A to FIG. 3D are correction process diagrams for explaining the third embodiment. (A) is a partial plan view of a retardation mask having an uncorrected defect portion. (B) is a sectional view taken along the line CC of (A). (C) is a partial plan view of a retardation mask in which a defective portion is corrected. (D) is
It is sectional drawing in DD of (C).

FIG. 4 is a graph showing a result of measurement of a relationship between a distance between opposite correction edges of a correction area of the phase difference mask and a light intensity of transmitted light of the phase difference mask.

FIG. 5 is a repairing process diagram for explaining a conventional mask defect repairing method.

[Explanation of symbols]

 10: Mask substrate 12: Conductive layer 14: Light-shielding pattern 16: Phase shifter 18: Defect part 20: Transparent film 30: Mask substrate 32: Conductive layer 34: Light-shielding pattern 36: Defect part 38: Phase shifter 40: Phase shifter 42: Phase shifter 44: Repair edge 46: Pattern edge 48: Defect repair area 50: Repair edge 54: Defect portion 56: Defect edge 58: Defect repair area 60: Repair edge 62: Defect portion 64: Defect edge 66: Defect repair area 68 : Corrected edge

Claims (3)

[Claims] 1. When repairing a defective portion generated in a phase shifter of a retardation mask, a distance between opposing repair edges of a defect repair area is set to a distance at which optical interference between the repair edges can be ignored, and A mask defect characterized in that the shortest distance between the repair edge of the defect repair area and the pattern edge of the light-shielding pattern of the phase difference mask is set to a distance at which mutual optical interference between the repair edge and the pattern edge can be ignored. How to fix. 2. The mask defect repairing method according to claim 1, wherein the shortest distance between the defect edge of the defect portion and the repair edge has no influence on the optical interference between the defect edge and the repair edge. A method for repairing a mask defect, which is characterized in that the distance is made shorter than a distance that is as small as possible. 3. When repairing a defective portion generated in a phase shifter of a retardation mask, a distance between opposing repair edges of a defect repair area is set to a distance at which optical interference between the repair edges can be ignored, and A method of repairing a mask defect, characterized in that at least a part of a repair edge is overlapped with a light shielding pattern of a retardation mask.