JP2010079113A - Method of manufacturing photomask and photomask - Google Patents

Abstract

Provided is a photomask manufacturing method having a defect correction process capable of efficiently and accurately correcting even a large black defect.
A step of preparing a photomask blank having a light shielding film formed on a transparent substrate, a step of patterning a resist film formed on the light shielding film to form a resist pattern, and a light shielding film using the resist pattern as a mask Are etched to form a light-shielding film pattern, and a defect inspection of the formed light-shielding film pattern is performed, and when there is a black defect due to surplus, the defective portion is corrected. In the process of correcting the defective portion, a resist film is formed again on the photomask, a predetermined pattern is drawn in a predetermined region including the defective portion, developed to form a correction resist pattern, and the resist pattern as a mask. Etching is performed to remove the excess of the defective portion.
[Selection] Figure 1

Description

The present invention relates to a photomask manufacturing method and photomask used for manufacturing semiconductor devices and the like.

For example, in the case of a binary mask, a photomask used for manufacturing a semiconductor device has a light shielding film formed in a pattern on a transparent substrate. Such a photomask includes a step of preparing a photomask blank in which a light-shielding film is formed on a transparent substrate, a step of patterning a resist film formed on the light-shielding film to form a resist pattern, and the resist pattern The light shielding film is etched by using the mask as a mask to form a light shielding film pattern.

Incidentally, in the photomask as described above, it is inevitable that a defect occurs in the light shielding film pattern during the manufacturing process. Here, a defect due to the surplus of the film pattern or adhesion of foreign matter is referred to as a black defect, and a defect due to a lack of the film pattern is referred to as a white defect.

When a defect inspection of the light shielding film pattern formed on the photomask is performed and a white defect or a black defect exists, usually, for example, a laser CVD method or a focused ion beam (FIB) method is used to locally detect the defect. It is conceivable to correct the membrane. That is, suitable correction is possible by forming a correction film locally on the white defect portion. On the other hand, as a method for correcting a black defect, a method of removing, for example, a light shielding film component by FIB or laser is common.

However, even if a conventional black defect correction method can correct a minute black defect area, it is very time-consuming and inefficient to correct a large black defect area by a conventional black defect correction method. It is. Further, in the conventional general black defect correction method, the scattered foreign matter is likely to adhere to the normal part (translucent part) around the defect, and correction is necessary again.

The present invention has been made in view of the above-described conventional circumstances, and the object of the present invention is firstly a defect correction step that can efficiently and accurately correct even a large black defect. A photomask manufacturing method and a photomask having a photomask, and secondly, a photomask manufacturing method and a photomask capable of quantitatively evaluating misalignment that may occur at a defect correction stage of the photomask. It is.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) A step of preparing a photomask blank having a light shielding film formed on a transparent substrate, a step of patterning a resist film formed on the light shielding film to form a resist pattern, and using the resist pattern as a mask Etching the light-shielding film to form a light-shielding film pattern; and performing a defect inspection of the formed light-shielding film pattern and correcting a defective portion when a black defect due to surplus exists. In the mask manufacturing method, the step of correcting the defective portion includes the step of identifying the defective portion, the step of forming a resist film again on the photomask, and the predetermined region including the defective portion, Performs pattern drawing based on drawing pattern data created based on the position and shape of the identified defective part, and after development, develops and corrects the resist A step of forming a turn, and a step of removing excess of the defective portion by performing etching using the correction resist pattern as a mask, the resist pattern including a first mark, and the correction resist The pattern includes a second mark, and further includes a step of inspecting at least one of after the formation of the correction resist pattern or after the step of removing the excess of the defective portion, When inspecting after the formation of the correction resist pattern, the distance between the edge of the light shielding film pattern corresponding to the first mark and the edge of the second mark in the correction resist pattern is measured, and the defect portion When inspection is performed after the process of removing surplus, it corresponds to the edge of the light shielding film pattern corresponding to the first mark and the second mark. That the distance between the edge of the light shielding film pattern is measured, the photomask manufacturing method of the distance, characterized in that it comprises a step of inspecting whether or not within a predetermined range.

(Configuration 2) When the first mark and the second mark formed when performing the step of correcting the defective portion are formed on the transparent substrate, the outer shape of one mark is the other. 2. The method of manufacturing a photomask according to Configuration 1, wherein the photomask is a combination of shapes included in the outer shape of the mark.
(Configuration 3) The photomask manufacturing method according to Configuration 2, wherein the first mark and the second mark each have a symmetrical pattern in one direction and a direction orthogonal thereto. Method.

(Structure 4) The photomask manufacturing method according to Structure 2 or 3, wherein the outer shape of the first mark and the outer shape of the second mark are similar.
(Configuration 5) The photomask manufacturing method according to any one of Configurations 2 to 4, wherein the first mark and the second mark both include a rectangular pattern.

(Structure 6) The photomask manufacturing method according to any one of structures 1 to 5, wherein the inspection step is performed by irradiating the photomask with light and receiving the transmitted light.
(Structure 7) The photomask manufacturing method according to any one of Structures 1 to 5, wherein the inspection step is performed by irradiating the photomask with light and receiving reflected light.

(Configuration 8) In a photomask having a light shielding film pattern on a transparent substrate, which is manufactured by forming a pattern on the light shielding film formed on the transparent substrate using a patterning process including a drawing process The photomask has a first mark formed on the light-shielding film by patterning including the drawing step, and performs a defect inspection of the light-shielding film pattern formed on the photomask, and black defects due to surplus materials are detected. When present, the defect portion is corrected by patterning including a drawing step, and the first mark is a light shielding film or resist formed by patterning including the first mark and a second drawing step for correcting the defect portion. The second drawing is performed by measuring the distance to the second mark formed on the film and checking whether the distance is within a predetermined range. To allow evaluation of misalignment, a photomask, wherein said in relation to the second mark, a rectangular pattern profile of one mark is contained within the outline of the other marks.

According to the photomask manufacturing method of the present invention, the light-shielding film pattern formed on the photomask is inspected for defects, and when there are black defects due to surplus, the defective portions are corrected by patterning including a drawing process. Therefore, even if there is a large black defect, efficient correction is possible. Further, in the case of correcting the black defect, the drawing for forming the light shielding film pattern and the drawing for correcting the black defect are performed twice. In the present invention, the drawing is performed twice. Since it includes an inspection process for quantitatively inspecting the misalignment of the drawing, whether or not the misalignment has occurred at the stage of correcting the black defect of the photomask, and if so, quantitatively inspect the size of the misalignment. be able to. That is, a specific mark (first mark) is created at the time of drawing for forming the first light-shielding film pattern, and a specific mark (second mark) is drawn at the time of drawing for correcting the second black defect, By evaluating the misalignment of two writings, for example, by the distance between the edges of these marks, it is possible to quantitatively inspect the misalignment actually generated in the black defect correction stage. In addition, since it is possible to evaluate misalignment during mask manufacturing, it is possible to make corrections possible at that stage if necessary, and even large black defects can be corrected efficiently and accurately. This is a great advantage for mask production.

Further, according to the photomask of the present invention, by having a specific mark (first mark) formed simultaneously with the formation of the light shielding film pattern, the defect inspection of the light shielding film pattern formed on the photomask is performed, When a black defect due to surplus is present and the defective portion is corrected by patterning including a drawing process, the magnitude of the alignment deviation actually generated at the black defect correction stage can be quantitatively inspected. That is, the outer shape of one mark is inside the outer shape of the other mark in relation to the specific mark (second mark) formed on the light shielding film at the time of drawing for correcting the black defect. By evaluating the distance between, for example, edges of these marks, the misalignment actually generated at the black defect correction stage can be quantitatively inspected. Since such an alignment shift can be evaluated during the mask manufacturing, it is possible to perform a possible correction at that stage if necessary.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic plan view for explaining an embodiment of a photomask manufacturing method according to the present invention in the order of steps.
In the mask blank to be used, a light shielding film 2 mainly composed of chromium is formed on a transparent substrate 1, and a resist film is formed thereon by applying a resist. First, a predetermined pattern is drawn. For drawing, an electron beam or light (short wavelength light) is usually used in many cases, but an electron beam is used in this embodiment. Therefore, a positive photoresist is used as the resist. Then, a predetermined device pattern is drawn on the resist film, and development is performed after the drawing, thereby forming a resist pattern 3 (see FIG. 1A). A specific mark pattern is simultaneously drawn when the device pattern is drawn. This specific mark pattern is used to evaluate misalignment at the time of drawing when black defect correction is performed later. For example, the specific mark pattern is drawn in an area outside the area where the device pattern is formed on the substrate. Accordingly, the resist pattern includes a mark (first mark) formed by drawing and developing the specific mark pattern. Details of the first mark will be described later.

Next, the light shielding film 2 is etched using the resist pattern 3 as an etching mask to form a light shielding film pattern (see FIG. 1B). Since the light shielding film 2 containing chrome as a main component is used, either dry etching or wet etching can be used as an etching means, but wet etching is used in the present embodiment.
Thus, a photomask having a predetermined light shielding film pattern formed on the transparent substrate 1 is obtained (see FIG. 1C).

As a result of the defect inspection using the defect inspection apparatus, a black defect including a small region and a large region as shown in FIG. 6 existed. As shown in FIGS. 1 (a) and 1 (b), this is a defect caused by, for example, foreign matter 5 covering the opening of the resist pattern 3 adhering and preventing the etching of the light shielding film in the opening. It is.
Next, based on the position information and shape information of the black defect 6 specified by the defect inspection, normal drawing pattern data in the black defect 6 or a predetermined region including the black defect 6 is produced.

Next, the same positive type resist film as the above is formed on the entire surface of the photomask, for example, and necessary information including the drawing pattern data prepared above is input to the drawing machine, and the black defect 6 or a predetermined containing the black defect 6 is input. Pattern drawing based on the drawing pattern data is performed on the area. And after drawing, it develops and the resist pattern 4 is formed. As a result, the resist film on the black defect 6 region is removed and the light shielding film 2 is exposed (see FIG. 1D). Note that alignment in this drawing step uses alignment marks provided in advance at the corners of the photomask. In addition, a specific mark pattern is simultaneously drawn at the time of drawing for the second defect correction. This specific mark pattern is for evaluating the misalignment at the time of this second drawing by combining with the first mark. For example, the device pattern on the substrate is the same as the case of the first mark. It is an area outside the area to be formed, and is drawn so as to have a predetermined positional relationship (distance relationship) with the first mark. Therefore, the resist pattern 4 includes a mark (second mark) formed by the second drawing and development. Details of the second mark will be described later.

Next, etching is performed using the resist pattern 4 as a mask. As the etching method, in the case of the chromium light-shielding film, for example, either dry etching or wet etching may be used, but in this embodiment, wet etching capable of performing local etching is used.

The unnecessary light shielding film 2 on the black defect 6 region is removed by the etching, and the transparent substrate 1 is exposed (see FIG. 1E).
Then, by removing the remaining resist pattern, a photomask having the black defect corrected is obtained (see FIG. 1F).

Next, with reference to FIG. 2, a method for inspecting misalignment when the second drawing is performed in order to correct the above-described black defect will be described. FIG. 2 is a cross-sectional view (left half) and a plan view (right half) of a specific mark pattern forming portion in order of the manufacturing process for explaining the inspection method in the above embodiment.
In the present embodiment, four types of patterns A, B, C, and D are used as one set as the first mark included in the resist pattern 3 for forming the light shielding film pattern (mask pattern) (see FIG. 2 (a)). Both are rectangular patterns, A is a pattern having a small rectangular hole (no resist) in the center, B is a small rectangular resist pattern in the center, and C is a predetermined width. Is a pattern having a rectangular opening portion, and D is a pattern having a large rectangular opening portion in the center.

The subsequent steps are exactly the same as the steps shown in FIG. That is, when the light shielding film 2 is etched using the resist pattern 3 including the first mark as an etching mask (see FIG. 2B) and the remaining resist pattern is removed, the first marks A, B, C, A photomask having a light-shielding film pattern corresponding to D is obtained (see FIG. 2C).
Next, when a black defect requiring correction is found by pattern inspection of the obtained photomask, a resist film is formed again on the photomask, and pattern drawing based on the drawing pattern data corresponding to the black defect is performed. After drawing, drawing, and developing to form a resist pattern 4 (see FIG. 2D).

In the present embodiment, as the second mark included in the resist pattern 4, four types of patterns a, b, c, d are set as one set in correspondence with the first marks A, B, C, D, respectively. Used (see FIG. 2D). Both are rectangular patterns, a is a rectangular pattern larger than the first mark A, b is a rectangular pattern larger than the first mark B, and c is smaller than the first mark C. It is a rectangular pattern, and d is a rectangular pattern smaller than the first mark D.
Thus, in this embodiment, the first mark A and the second mark a, the first mark B and the second mark b, the first mark C and the second mark c, the first mark D and the second mark d are respectively Use in combination. When the first mark and the second mark are formed on the transparent substrate 24, the outer shape of one mark is included in the outer shape of the other mark. The first mark and the second mark both have a symmetrical pattern in one direction and a direction orthogonal thereto. In addition, the outer shape of the first mark and the outer shape of the second mark are similar to each other in a rectangular shape, and the pattern data of these marks includes a rectangular pattern having a common center of gravity.

Therefore, when the first marks A, B, C, and D and the second marks a, b, c, and d in the present embodiment are formed on the transparent substrate 24, the surface of the transparent substrate 24 is combined in each combination. In one direction in the plan view of, the first mark edge, the second mark edge, the second mark edge, the first mark edge arrangement in order, or the second mark edge, the first mark edge, The first mark edge and the second mark edge are arranged in this order (see FIG. 2D).

In this case, that is, when inspection is performed after the formation of the resist pattern 4 formed by the second drawing (step in FIG. 2D) when the black defect is corrected, the film pattern corresponding to the first mark The distance between the edge and the edge of the second mark in the resist pattern 4 is measured, and whether or not this distance is within a predetermined range is evaluated to evaluate misalignment during the second drawing. That is, in this embodiment, as shown in FIG. 3, in any of the four types of patterns, for example, in the X direction, the edge of the light shielding film 2 pattern corresponding to the first mark and the second mark in the resist pattern 4 Measure the distances m and n to the edge, evaluate the size of the misalignment with (mn) / 2, and check whether this value is within a predetermined range (allowable range) set in advance. . Further, the misalignment in the Y direction can be similarly evaluated. In FIG. 2 (d) and FIG. 3, the locations marked with a circle are the preferred measurement locations in this embodiment.

As described above, after the resist pattern 4 formed by the second drawing for correcting the black defect is inspected, the resist pattern 4 is removed when the alignment deviation exceeds the allowable range. Then, it is possible to make corrections by performing resist film formation and drawing again (re-doing resist patterning).
As described above, after the resist pattern 4 is formed as necessary, the light shielding film 2 is etched using the resist pattern 4 including the second mark as an etching mask (see FIG. 2E) and remains. When the resist pattern is removed, a film pattern corresponding to (a combination of) the first marks A, B, C, D and the second mark is formed (see FIG. 2F).

Even in the case of inspecting misalignment after the final process, for example, in the X direction, the distances m and n between the edge of the light shielding film pattern corresponding to the first mark and the edge of the light shielding film pattern corresponding to the second mark are measured. Then, the magnitude of the alignment deviation is evaluated by (mn) / 2, and it is inspected whether or not this value is within a predetermined range (allowable range) set in advance. Further, the misalignment in the Y direction can be similarly evaluated. In FIG. 2 (f), the locations marked with ◯ are the preferred measurement locations in this embodiment. At this stage, the mark pattern may have disappeared (for example, the first mark A, the second mark b, and the second mark d), but at the stage after the formation of the resist pattern 4 described above, Inspection can be performed by a combination of the first mark and the second mark.

In order to eliminate the element of CD deviation (pattern narrowing) due to the manufacturing process and evaluate only the element of alignment deviation purely, for example, it is possible to detect the presence or absence of alignment deviation in the X-axis and Y-axis directions. It is preferable that each of the one mark and the second mark has a pattern having a symmetrical shape (for example, left-right symmetry or vertical symmetry) in one direction and a direction perpendicular thereto. Further, it is desirable that the first mark and the second mark are arranged in a positional relationship such that the distance between these edges can be measured with high accuracy by a single measurement. Moreover, it is preferable that the external shape of the first mark and the external shape of the second mark are similar so that the distance between the edges of the first mark and the second mark can be easily measured.

Further, as in the present embodiment, it is also preferable to use a plurality of patterns as a set of inspection mark patterns. In particular, when the inspection is performed at a stage after the formation of the resist pattern 4 by the second drawing, the inspection is performed with the resist pattern on the substrate, so that the resist transmittance is also affected. In addition, it is preferable to measure with reflected light or transmitted light because it is possible to select a mark pattern that is easy to measure at the time of measurement depending on whether the measurement accuracy is high (in which case higher contrast is obtained). is there. In some cases, inspection can be performed with both reflected light and transmitted light.

That is, as in this embodiment, a plurality of inspection mark patterns (a combination of the first mark and the second mark) may be used as a set for every product, or one type of mark pattern may be used for each product. Or about two types may be selected and used.

  The first marks A, B, C, and D and the second marks a, b, c, and d used in the above embodiments are merely representative examples, and the effects of the present invention can be obtained. Needless to say, the shape and size of the mark, the combination of the first mark and the second mark, the positional relationship thereof, and the like are not necessarily limited to those of the above-described embodiments.

As described in the above embodiment, according to the present invention, the following effects can be obtained.
(1) The defect inspection of the light shielding film pattern formed on the photomask is performed, and when there is a black defect due to surplus, the defective part is corrected by patterning including a drawing process, so even if there is a large black defect An efficient correction is possible.
(2) When correcting a black defect, drawing for forming a light shielding film pattern and drawing for correcting a black defect are performed twice. In the present invention, a photomask is used. It is possible to quantitatively inspect the magnitude of the misalignment actually generated in the black defect correction stage. That is, a specific mark (first mark) is created at the time of drawing for forming the first light-shielding film pattern, and a specific mark (second mark) is drawn at the time of drawing for correcting the second black defect, By evaluating the misalignment of two writings, for example, by the distance between the edges of these marks, it is possible to quantitatively inspect the misalignment actually generated in the black defect correction stage.
(3) In addition, since it is possible to evaluate misalignment during the mask manufacturing, it is possible to make corrections possible at that stage if necessary, and even for large black defects, it is efficient and accurate. It can be corrected well and has great advantages in mask production.

It is a schematic plan view which shows embodiment of the manufacturing method of the photomask by this invention in order of a process. It is sectional drawing and the top view of the order of a process of the specific mark pattern formation part for demonstrating the inspection method of the alignment gap in the said embodiment. It is a top view of the specific mark pattern formation part for demonstrating the said inspection method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Light shielding film 3, 4 Resist pattern 5 Foreign material 6 Black defect A, B, C, D First mark a, b, c, d Second mark

Claims (8)

A step of preparing a photomask blank having a light shielding film formed on a transparent substrate; a step of patterning a resist film formed on the light shielding film to form a resist pattern; and the light shielding film using the resist pattern as a mask. Etching to form a light shielding film pattern, and performing a defect inspection of the formed light shielding film pattern, and correcting a defective portion when a black defect due to surplus exists, a photomask manufacturing method Because
The step of correcting the defective portion includes the step of identifying the defective portion;
Forming a resist film again on the photomask;
Performing pattern drawing based on drawing pattern data produced based on the position and shape of the specified defective portion in a predetermined area including the defective portion, and after drawing, developing to form a correction resist pattern;
Etching using the correction resist pattern as a mask to remove excess of the defective portion, and
The resist pattern includes a first mark, the correction resist pattern includes a second mark,
Furthermore, it has a step of inspecting at least one of after the formation of the correction resist pattern or after the step of removing the surplus of the defective portion,
In the inspection step, when the inspection is performed after the correction resist pattern is formed, the distance between the edge of the light shielding film pattern corresponding to the first mark and the edge of the second mark in the correction resist pattern is measured. ,
When performing inspection after the step of removing the excess of the defective portion, measure the distance between the edge of the light shielding film pattern corresponding to the first mark and the edge of the light shielding film pattern corresponding to the second mark, A method of manufacturing a photomask, comprising a step of inspecting whether or not the distance is within a predetermined range.   The first mark and the second mark formed when performing the step of correcting the defective portion are formed when the outer shape of one mark is the outer shape of the other mark when formed on the transparent substrate. The method of manufacturing a photomask according to claim 1, wherein the photomask is a combination of shapes included therein.   3. The method of manufacturing a photomask according to claim 2, wherein the first mark and the second mark each have a symmetrical pattern in one direction and a direction orthogonal thereto.   4. The method of manufacturing a photomask according to claim 2, wherein the outer shape of the first mark and the outer shape of the second mark are similar.   5. The method of manufacturing a photomask according to claim 2, wherein each of the first mark and the second mark includes a rectangular pattern.   6. The method of manufacturing a photomask according to claim 1, wherein the inspection step is performed by irradiating the photomask with light and receiving the transmitted light.   6. The method of manufacturing a photomask according to claim 1, wherein the inspection step is performed by irradiating the photomask with light and receiving the reflected light. A photomask having a light shielding film pattern on a transparent substrate, which is manufactured by forming a pattern on a light shielding film formed on a transparent substrate using a patterning process including a drawing process.
The photomask has a first mark formed on the light shielding film by patterning including the drawing step,
Perform a defect inspection of the light-shielding film pattern formed on the photomask, and correct the defective portion by patterning including a drawing step when a black defect due to surplus exists.
The first mark measures a distance between the first mark and a second mark formed on the light-shielding film or the resist film by patterning including a second drawing process for correcting the defective portion, and the distance In the relationship with the second mark, the outer shape of one mark is the same as that of the other mark so that it is possible to evaluate the misalignment of the second drawing. A photomask, which is a rectangular pattern included in an outer shape.

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