KR20030014098A - Mask for measuring flare, method for fabricating the same, method for measuring flare-affected range on a wafer, and method for correcting patterns in flare-affected range using the same - Google Patents

Abstract

PURPOSE: A mask for measuring flare is provided to determine whether flare of a lens occurs by performing a photolithography process while using a mask having a light blocking region and a light transmitting region which have a plurality of light transmitting patterns. CONSTITUTION: The light blocking region and the light transmitting region are defined on a mask substrate. A plurality of line patterns blocking light and a plurality of light transmitting patterns transmiting light are formed in the light blocking region and the light transmitting region, respectively. The line patterns and the light transmitting patterns correspond to each other in the light blocking region and the light transmitting region. The line patterns have the same line width. The light transmitting patterns have the same line width. The line transmitting pattern is a groove between the line patterns.

Description

Mask for measuring flare and manufacturing method thereof, method for measuring region affected by flare on wafer and using pattern correction method for region affected by flare (Mask for measuring flare, method for fabricating the same, method for measuring flare- affected range on a wafer, and method for correcting patterns in flare-affected range using the same}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a photolithography system, and more particularly, to a mask for flare measurement of a lens mounted in a photolithography apparatus, a method for manufacturing the same, and a method for measuring an area affected by flare on a wafer using the same and A method of correcting a pattern in a mask of an affected area.

In general, flare refers to a phenomenon in which photoexposure is generated in a photolithography process due to a defect such as a projection lens mounted on an exposure apparatus of a photolithography system. That is, when a defect occurs on the surface of the lens, light scattering occurs at the lens defect site, and shape deformation of the photoresist pattern occurs. Here, surface defects of the lens may include surface contamination, scratches, or partial refractive index differences, and scattering may occur when light is not focused through the lens at the sites of such defects.

This flare phenomenon will be described in more detail with reference to FIGS. 1A and 1B.

1A and 1B, an exposure apparatus for performing a photolithography process reduces and projects a shape of a blocking pattern 11 of a mask 10 having a predetermined blocking pattern 11 to a predetermined portion of a wafer 12. It includes a lens 14 to make. This lens 14 is interposed between the mask 10 and the wafer 12. In addition, a photoresist film (not shown) is coated on the wafer 12.

At this time, as in FIG. 1A, when no defect occurs on the surface of the lens 14, the shape of the blocking pattern 11 drawn on the mask 10 is transferred to the photoresist film. Accordingly, the photoresist pattern 12a is formed on the wafer 12 in a form in which the pattern 11 of the mask 10 is reduced.

On the other hand, as shown in FIG. 1B, when a defect occurs on the surface of the lens 14, light scattering occurs at the defect generation part 15. Such light scattering causes a non-uniform distribution of light upon exposure of the photoresist film, as described above, thereby lowering the contrast of the aerial image. In addition, such light scattering increases the exposure amount of the region adjacent to the defect occurrence region 15, so that overexposure occurs on the wafer corresponding to the defect occurrence region 15 and the region adjacent thereto. As a result, the shape of the photoresist pattern 12b on the wafer 12 may be deformed, or an on chip variation phenomenon in which the width of the photoresist pattern 12b formed in one field is different may occur. .

These phenomena are collectively referred to as flares, and the flare amount changes as the defect of the lens of the exposure apparatus is further deepened as the photolithography process is continuously performed.

Accordingly, it is necessary to provide a photoresist pattern free of pattern defects during the photolithography process by measuring the flare amount of the lens and the wafer position where the flare is generated for each process.

However, the conventional photolithography system does not include a tool for measuring the flare of the lens, the amount of flare of the flare generating portion, and the area where the flare affects each process. Difficult to do In addition, when the correction tool for measuring such flare is mounted on the photolithography system, there is a problem that the process cost increases.

Accordingly, the technical problem to be achieved by the present invention is to provide a flare measuring mask that can measure the flare of the lens and the amount of flare without increasing the manufacturing cost.

Another object of the present invention is to provide a method of manufacturing the above-described flare mask.

In addition, another technical problem to be achieved by the present invention is to measure the area affected by the flare on the wafer by measuring the area of the photoresist line width is affected by the flare on the wafer using the above-described flare measuring mask. To provide a way.

Another object of the present invention is to provide a method for correcting the line width of a photoresist pattern formed in a wafer region affected by the flare using the flare measuring mask.

Another object of the present invention is to provide a method for correcting the line width of a transmission pattern (or blocking pattern) of a flare mask using the flare measuring mask.

1A and 1B are cross-sectional views for explaining a general flare phenomenon.

FIG. 2 is a flowchart illustrating a method of measuring flare amount and an area affected by flare and a pattern correction method of an area affected by flare according to the present invention.

3 is a plan view of a first mask for flare measurement according to the present invention.

4 is a diagram for explaining a first photolithography process of the present invention.

5 is a graph showing a line width of a photoresist pattern formed by a first photolithography process for each wafer region.

6 is a plan view of a second mask for flare measurement according to the present invention.

7 is a diagram for explaining a second photolithography process of the present invention.

8 is a graph showing a line width of a photoresist pattern formed by a second photolithography process for each wafer region.

9 is a graph showing the line width change of the photoresist pattern according to the flare amount.

10, 11, 12A, 12B, 13A, 13B, 14, and 15 are plan views showing modifications of the second mask.

16 is a plan view of a wafer for explaining a method of correcting a line width of a pattern in a mask by convolution.

(Explanation of symbols for the main parts of the drawing)

100, 200: flare measurement mask 110: light transmission pattern

120: light blocking layer 120a: main light blocking layer

121: sub light blocking layer 210: light blocking area

220: light transmission region

Other objects and novel features thereof, together with the objects of the present invention, will be apparent from the description and the accompanying drawings.

Among the inventions disclosed herein, an outline of representative features is briefly described as follows.

First, in the flare measurement mask according to an embodiment of the present invention, a light blocking region and a light transmitting region are defined on a mask substrate, and are formed in the light blocking region and the light transmitting region, respectively, A plurality of line patterns for blocking and a plurality of light transmission patterns for transmitting light are formed to correspond to each other in the light blocking region and the light transmitting region.

Here, each line pattern may have the same line width, each light transmission pattern may also have the same line width, and the light transmission pattern may be a groove between the line patterns.

In addition, the flare measurement mask according to another embodiment of the present invention is formed on a mask substrate and a predetermined region of the mask substrate, and divides the mask substrate into a light blocking region and a light transmitting region, and at least one or more At least one main light blocking layer having a light transmission pattern formed thereon, and at least one light transmission pattern formed on a light transmission region of the mask substrate on which the main light blocking layer is not formed, and corresponding to the light transmission pattern of the main light blocking layer; It consists of a sub light blocking layer.

Here, the light transmission patterns of the main light blocking layer are plural in the longitudinal direction, and the sub light blocking layers are plural in the longitudinal direction with the same size as each other.

In addition, each light transmission pattern is the same size, and the transverse spacing and longitudinal spacing of each light transmission pattern are the same.

The boundary between the main light blocking layer and the light transmitting region forms a straight line, and the straight line is orthogonal to the line connecting the center of the light transmitting pattern.

In addition, the main light blocking layer, that is, the light blocking region and the light transmitting region are the same size, each light transmission pattern may be arranged in the center of the mask substrate, or may be arranged on the left or right of the mask substrate.

In addition, the flare is measured at the main light blocking layer and the portion where the light transmission pattern is arranged among the boundary portions of the light transmission region. The light transmission pattern may be a groove formed in the main light blocking layer and the sub light blocking layer.

Moreover, the manufacturing method of the flare measurement mask which concerns on another aspect of this invention is as follows. First, a light blocking layer is formed on a mask substrate, and then at least one light transmission pattern is formed on the light blocking layer. Subsequently, a predetermined portion of the light blocking layer is removed to form a main light blocking layer defining the light blocking region and the light transmitting region, and at the same time, the light blocking layer is left to include a light transmission pattern in the light transmitting region to thereby sub-light blocking layer. To form.

Here, the at least one light transmission pattern is formed to be arranged in a plurality in the longitudinal direction of the mask substrate, each light transmission pattern is formed to have the same size. In addition, each light transmission pattern has the same transverse spacing and longitudinal spacing, respectively.

In addition, the light blocking layer is preferably removed so that the size of the light blocking region and the size of the light transmitting region is the same. Each light transmission pattern may be arranged at the center of the mask substrate, or may be arranged at the left side or the right side.

Further, in the forming of the light transmission pattern and in the forming of the main light blocking layer, the light transmission pattern is formed such that the boundary between the main light blocking layer and the light transmission region and the light transmission pattern meet a portion to measure the flare. And a predetermined portion of the main light blocking layer can be removed.

In addition, a method of measuring an area affected by flares on a wafer according to another embodiment of the present invention is as follows. First, a photoresist pattern is formed on a wafer using the flare measuring mask. Next, the line width of each photoresist pattern formed by the line pattern of the light blocking region of the flare measuring mask and the photoresist pattern formed by the line pattern of the light transmitting region is measured. Thereafter, the line widths of the photoresist patterns formed corresponding to the respective regions are compared, and the line width difference of the photoresist patterns in the two regions is measured. At this time, if there is a line width difference, it is determined that flare exists, and the flare amount is calculated from the line width difference. Then, the section in which the line width changes rapidly between the photoresist patterns between the regions is measured. Next, a circle having a radius as the distance to the section where the line width is rapidly changed is set, and the wafer portion corresponding to the area inside the circle is estimated as an area affected by flare.

In addition, according to another embodiment of the present invention, a pattern correction method of an area affected by another flare is as follows. That is, by the above-described methods, the effective flare amount of the region affected by the flare is measured. Next, correcting the line width of the line pattern and the line width of the light transmission pattern formed in the mask region corresponding to the region affected by the flare in consideration of the effective flare amount.

Here, in the measuring the effective flare amount, the opening and closing ratio in the area affected by the flare is calculated, and then the flare amount of the lens is converted into the opening and closing ratio, so that the effective flare amount in the area affected by the flare. To calculate.

In addition, the line pattern of a mask uses the method of making the blocking pattern size of the mask of the position of the mask corresponding to the area | region which is affected by flare large enough by the line width change amount corresponding to the said effective flare amount.

In addition, a method of correcting a photoresist pattern formed on an area on a wafer affected by flare is first exposed by using a flare measuring mask to form a photoresist pattern on the wafer, and to form a wafer on which the photoresist pattern is formed. The region of the image is classified into a plurality of mesh regions, and then a convolution value according to the flare of each of the mesh regions is measured. Then, the critical dimension error value of the photoresist pattern of the mesh area is measured by the following equation, and the critical dimension of the pattern of the mask corresponding to the mesh is reduced by the critical dimension error value. At this time, the error value of the critical dimension of the photoresist pattern of the mesh area is X CD error, where "CD error wafer" represents the critical error value of the wafer mesh area, "convolution value" represents the convolution value of the wafer mesh area, and "convolution max" The maximum value of the convolution value in the mesh region is shown, and "Max CD error" represents the maximum line width difference of the maximum photoresist pattern.

In addition, the method for measuring the error value of the pattern in the mask affected by the flare and correcting the error value by the error value, first, by using the mask for flare measurement to expose, to form a photoresist pattern on the wafer, The area on the wafer on which the photoresist pattern is formed is classified into a plurality of mesh areas, and then a convolution value according to the flare of each of the mesh areas is measured. Then, the critical dimension error value of the photoresist pattern of the mesh area is measured by the following Equation 1, and the error factor MEEF of the reduced-projection exposure equipment for forming the photoresist pattern is calculated. Thereafter, using the critical dimension error value of the photoresist pattern and the error factor (MEEF) of the reduction projection exposure equipment, the error value of the critical dimension of the pattern in the mask is measured by the following equation 2, and the pattern in the mask Correct the critical dimension of the pattern in the mask by the error value of the critical dimension of. At this time, the error value of the critical dimension of the photoresist pattern of the corresponding mesh region of Equation 1 is The error value of the critical dimension of the pattern in the mask, obtained by x CD error, is Where "CD error wafer" represents the critical dimension error value of the corresponding wafer mesh region, "convolution value" represents the convolution value of the corresponding wafer mesh region, and "convolution max" represents the convolut of the entire mesh region. "Max CD error" represents the maximum line width difference of the maximum photoresist pattern, "MEEF" represents the error factor of the reduction projection exposure equipment, and "Mag" represents the reduction projection multiple of the exposure equipment. Characterized in that represents.

According to the present invention, by performing a photolithography process using a light blocking region having a plurality of light transmission patterns and a mask having a light transmission region, it is possible to measure whether a lens flare occurs. In addition, the line widths of the photoresist patterns formed corresponding to the blocking region and the light transmitting region are compared to measure the flare amount of the lens and the region affected by flare on the wafer. In addition, by using the opening and closing ratio in the region affected by the flare, it is possible to measure the effective flare amount of the region affected by the flare. Accordingly, the line width change of the photoresist pattern on the wafer can be estimated from the effective flare amount of the region affected by the flare. In addition, a uniform pattern can be obtained on the wafer by correcting the line width of the mask pattern formed in the region affected by the flare.

In addition, since the exposure apparatus does not need to install a separate device for measuring the flare of the lens and the amount of flare, and to measure the area affected by the flare, manufacturing costs are greatly reduced.

(Example)

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and the like of the elements in the drawings are exaggerated to emphasize a more clear description, and the elements denoted by the same reference numerals in the drawings means the same elements. In addition, where a layer is described as being "on" another layer or semiconductor substrate, a layer may exist in direct contact with the other layer or semiconductor substrate, or a third layer therebetween. Can be done.

2 is a flowchart illustrating a method of measuring a region affected by a flare and a pattern correction method of a region affected by a flare according to the present invention, and FIG. 3 is a first flowchart for measuring flares according to the present invention. Top view of the mask. 4 is a view for explaining the first photolithography process of the present invention, Figure 5 is a graph showing the line width of the photoresist pattern formed by the first photolithography process for each region of the wafer. FIG. 6 is a plan view of a second mask for measuring flare according to the present invention, FIG. 7 is a view for explaining a second photolithography process of the present invention, and FIG. 8 is formed by a second photolithography process for each region of a wafer. It is a graph which shows the line width of a photoresist pattern. 9 is a graph showing a change in line width of the photoresist pattern according to the flare amount, and FIGS. 10, 11, 12A, 12B, 13A, 13B, 14, and 15 show a modification of the second mask. Top view. 16 is a plan view of a wafer for explaining a method of correcting a line width of a pattern in a mask by convolution.

First, referring to FIG. 2, in order to measure flare of a lens, a first mask 100 for measuring flare is formed (S1).

Here, as shown in FIG. 3, the first mask 100 includes a mask substrate (not shown); The light blocking layer 120 is covered on the surface of the mask substrate and has a plurality of light transmission patterns spaces 110 arranged in a predetermined rule. Here, the line pattern 130 is defined in the light blocking layer 120 by the light transmission pattern 110. That is, the line pattern 130 is a space between the light transmission patterns 110. The substrate of the first mask 100 may be a transparent substrate, for example, a quartz substrate, and the light blocking layer 120 may be a material that blocks incident light such as chromium (Cr). Here, the light transmission patterns 110 may be, for example, a space formed in the light blocking layer 120, and a plurality of light transmission patterns 110 are arranged in the longitudinal direction. (In addition, the line patterns 130 are limited by the light transmission patterns 110.) Here, the light transmission patterns 110 are all formed in the same size, and the horizontal widths, that is, the line widths of the line patterns 130 are respectively same. In addition, each light transmission pattern 110 has the same longitudinal spacing. In addition, the light transmission patterns 110 may be disposed in the center of the mask. In the present embodiment, the width of the light transmission pattern 110 and the line pattern 130 defined by the light transmission pattern 110 is set to 0.15 μm, respectively, and the light transmission patterns 110 are horizontally, for example, 7. Are arranged one by one.

Again, referring to FIG. 2, the first photolithography process is performed using the first mask 100 (S2).

As shown in FIG. 4, a first mask 100 is first disposed on a wafer 160 coated with a photoresist film (not shown), and then a first photolithography process is performed in a known manner. In this case, the lens 150 is interposed between the first mask 100 and the wafer 160, and the lens 150 reduces and projects the shape of the light blocking layer 120 of the first mask 100. Thereafter, light 170 is incident from the outside of the first mask 100 toward the wafer 160, and the light 170 is absorbed at a portion where the light blocking layer 120 of the first mask 100 is formed, In the portion of the light transmission pattern 110 is passed. The light passing through the first mask 100 is focused on the photoresist film (not shown) of the wafer 160 by the lens 150, so that the photoresist film (not shown) is partially exposed. In this embodiment, for example, ASML U-line exposure equipment was used as the exposure equipment. Thereafter, the exposed photoresist film is developed to form a photoresist pattern 162. (Herein, reference numeral 101 in FIG. 4 denotes a substrate of the first mask 100.

Referring to FIG. 2, the distance a2 between the line width a1 of the photoresist pattern 162 formed by the first photolithography process and the photoresist pattern 162, that is, the critical dimension (CD) is measured. (S3). At this time, as described above, since the light transmission patterns 110 of the first mask 100 are all designed to have a constant size, unless there is a special defect of the exposure apparatus (not shown), the first mask 100 The line width a1 and the spacing a2 of the photoresist pattern 162 defined by the same are also constant. FIG. 5 is a graph showing the line width a1 of the photoresist pattern 162 for each wafer region. The line width of the photoresist pattern 162 formed by attaching a mask to the exposure apparatus and scanning the mask in the longitudinal and lateral directions. Is a graph measured. According to the graph of FIG. 5, the size of the photoresist pattern 162 defined by the light transmission pattern 110 is uniform over the entire area, and is formed with a line width of about 150 nm. In this manner, the photolithography process using the first mask 100 measures whether the design of the first mask 100 is uniform in a desired shape. In addition, in the photolithography process by the first mask 100, when the open ratio is almost " 0 " (when most regions of the mask are blocked), the line width change of the photoresist pattern even if a flare is present Proceeds to show that there is little.

Subsequently, with reference to FIG. 2, a predetermined portion of the light blocking layer 120 of the first mask 100 is removed to form a second mask 200 for flare measurement (S4). As illustrated in FIG. 6, the second mask 200 is formed by removing a predetermined portion of the light blocking layer 120 of the first mask 100 to form the main light blocking layer 120a. In this case, the second mask 200 is limited to the light blocking region 210 and the light transmitting region 220 by the main light blocking layer 120a. Since the second mask 200 is obtained by removing a predetermined portion of the light blocking layer 120 of the first mask 100, the second mask 200 has the same size, longitudinal spacing, and lateral spacing as the first mask 100 in the main light blocking layer 120a. A plurality of identical light transmission patterns 110 are formed, respectively. Meanwhile, at least one sub light blocking layer 121 in which at least one light transmission pattern 110 corresponding to the light transmission pattern 110 of the main light blocking layer 120a is formed is formed in the light transmitting region 220. . In this case, the sub light blocking layer 121 is formed at the same time as the main light blocking layer 120a and is positioned on the same plane. Here, forming the sub light blocking layer 121 is not limited to the light transmission pattern 110 when all the light blocking layers 120 in the light transmission region 220 are removed. It is left to limit. The sub light blocking layers 121 have the same size and are arranged in the longitudinal direction. That is, the sub light blocking layer 121 is arranged in an island form on the light transmission region 220 and is formed to surround the light transmission patterns 110 formed in the same row. In the second mask 200 according to the present exemplary embodiment, the light blocking region 210 and the light transmitting region 220 in which the main light blocking layer 120a is formed may have the same size. In addition, the boundary between the light blocking region 210 and the light transmitting region 220 may be a straight line L1, which is the center and the light of the light transmission patterns 110 of the light blocking region 210. It is preferable to be orthogonal to the line L2 connecting the centers of the light transmission patterns 110 of the transmission region 220. In addition, the area occupied by the sub light blocking pattern 121 formed in the light transmission region 220 is very small compared to the area of the entire light transmission region 220. Here, reference numeral x1, which is not described, indicates a lateral length of the sub light blocking pattern 121.

Subsequently, with reference to FIG. 2, a second photolithography step is performed using the second mask 200 produced as described above (S5).

That is, as shown in FIG. 7, first, the wafer 180 covered with the photoresist film (not shown) is exposed using the second mask 200. Here, the wafer 180 may reuse the wafer 160 used in the first photolithography process or use a new test wafer. In addition, when using the wafer used for the first photolithography process, the photoresist pattern formed in the first photolithography process is removed and used with a new photoresist film applied. Similar to the first photolithography step S2, a lens 150 which performs a reduced projection between the second mask 200 and the wafer 180 is interposed. Light 170 is irradiated toward the wafer 180 from the outside of the second mask 200. The incident light 170 is absorbed at a portion where the main light blocking layer 120a and the sub light blocking layer 121 of the second mask 200 are formed, and passes through the light transmission pattern 110. The light passing through the second mask 200 is focused on the photoresist film (not shown) of the wafer 180 by the lens 150 to form the photoresist pattern 184. As the light source used in the second photolithography process, the ASML U-line exposure equipment used in the first photolithography process is used as it is. Here, reference numeral b1 in FIG. 7 denotes a width of the photoresist pattern 184, and b2 denotes an interval of the photoresist pattern 184.

Referring again to FIG. 2, the width b1 and the spacing b2 of the photoresist patterns 184 formed by the second photolithography process, that is, the critical dimension CD are measured (S6). FIG. 8 is a graph showing the line width b1 of the photoresist pattern 184 for each wafer region by the second photolithography process. Similar to FIG. 5, a mask is mounted on the exposure apparatus to vertically and laterally. The line width b1 of the photoresist pattern 184 formed by scanning is measured. Referring to the graph of FIG. 8, it can be seen that the difference in width between the photoresist pattern 184 formed in the light blocking region 210 and the photoresist pattern 184 formed in the light transmitting region 220 occurs significantly. As such, the difference in width between the photoresist pattern 184 in the light blocking region 210 and the light transmitting region 220 is caused by the flare phenomenon of the lens. In general, if there is no defect in the lens 150 (see FIG. 7), even if the exposure process is performed using the second mask 200, as shown in FIG. 5, the photoresist pattern 184 having a uniform line width may be formed. It must be formed. However, if the lens 150 is defective, severe light scattering occurs at this defect site (300 in FIG. 7), and unwanted scattered light (310 in FIG. 7) is irradiated onto the wafer 180 surface. Accordingly, due to light scattering during the photolithography process, overexposure occurs on the wafer corresponding to the defect-producing region of the lens and the region adjacent thereto, thereby deforming the line width of the photoresist pattern 184. According to the graph of FIG. 8, the average width of the photoresist patterns 184 formed in the light blocking region 210 is about 150 nm, while the average width of the photoresist patterns 184 formed in the transmission region 220 is about. It is about 130nm. Accordingly, the line width difference of the photoresist patterns 184 formed in the blocking region 210 and the transmission region 220 is about 20 nm on average.

Still, referring to FIG. 2, the flare amount of the lens is estimated by referring to the difference between the average line widths of the respective photoresist patterns 184 formed in the blocking region 210 and the transmission region 220, and the line width difference is measured by the measurement equipment. If the measurement error is greater than or equal to, the area affected by the flare on the wafer is measured (S7).

Here, the flare amount of the lens is a value that is applied to the entire area where the exposure is performed by the second mask 200, that is, the entire exposure field, and is easily obtained by a general computer program due to the difference in the line width of the photoresist pattern. 9 is a graph showing a change in the line width of the photoresist pattern according to the flare amount for each exposure condition, by the above program. In this embodiment, the exposure condition (equipment) C was used, and the difference in the photoresist pattern was 20 nm, and the line width of the photoresist pattern formed by the light transmission region 220 was 130 nm, so that about 5% of flare amount was obtained. .

Next, a method of measuring the area affected by flare due to the line width difference will be described.

According to the graph of FIG. 8, the line width of the photoresist pattern 184 shows a drastic change in the interface between the light blocking region 210 and the light transmitting region 220, in particular in the range of 0 to 500 μm from the interface (see FIG. 8). In r), the line width is drastically reduced, and the line width is no longer changed at 500 µm or more. At this time, the sudden change in the line width is due to the flare phenomenon of the lens, and the 0 to 500 μm section in which the line width is rapidly changed becomes an area affected by the flare. On the other hand, the graph showed a sharp change only in the 0 ~ 500㎛ corresponding to the light transmission region 220, but it is predicted that all the 500㎛ radius region including the light blocking region 210 based on the interface will be affected by the flare. Can be.

More specifically, referring to FIGS. 8 and 10, a section r (0 to 500 μm in the present embodiment) in which the line width of the photoresist pattern 184 changes rapidly is measured. Subsequently, a circle 400 having a radius of a distance corresponding to the line width change section r is set around the point where the line width of the photoresist pattern 184 starts to change (zero point in this embodiment). The wafer area corresponding to the area inside the circle 400 is assumed to be a flare influenced area.

Thereafter, the photoresist pattern 184 formed in the region affected by the flare is corrected (S8). More specifically, as described above, the photoresist pattern 184 formed in the region affected by the flare has a line width relatively smaller than the line width (size) determined by light scattering due to the flare of the lens. do. Accordingly, the linewidth reduction of the pattern can be calculated by the following method, and in the subsequent mask fabrication, the linewidth can be compensated by the linewidth reduction.

The decrease in line width of this pattern is calculated as follows.

First, the opening and closing ratio of the pattern in the region affected by flare on the wafer is measured. The opening and closing ratio is generally defined as the ratio CL of the open area CL to the shielding area DK (CL / DK), and the opening and closing ratio in the present invention is the main and sub light blocking layers 120a and 121 in the flare area. It is obtained by the ratio of the sum of the area of the light transmission pattern 110 and the area of the exposed quartz substrate 101 to the total area covered by.

Thereafter, the flare amount of the lens obtained in the graph of FIG. 9 is converted into an opening / closing ratio corresponding to the flare generation area, and the effective flare amount of the area is measured. That is, since the flare amount obtained in the graph of FIG. 9 is the flare amount when the opening and closing ratio is 100%, the effective flare amount in the region affected by the flare is the flare amount when the opening and closing ratio of the corresponding region is 100%. Is multiplied.

According to the flare amount of the flare region thus obtained, the line width of the mask line pattern 130 (see FIG. 3) corresponding to the region affected by the flare during the subsequent mask fabrication process is designed to be as large as the line width variation amount corresponding to the effective flare amount. do. Then, during the photolithography process, even if flare occurs, a photoresist pattern having a uniform size is formed on the wafer.

In this embodiment, since the center is located at the interface between the light blocking area 210 and the light transmitting area 220, the opening and closing ratio is about 50%, and since the flare amount of the lens is about 5%, the area affected by flare. The actual flare amount of is about 2.5%.

As described above, according to the present exemplary embodiment, a single mask can be used to measure the flare of the lens, the amount of flare of the lens, and the area of the wafer affected by the flare without any tools. It is possible to correct the line width of the pattern of the area receiving the.

In addition, the present invention can further correct the photoresist pattern line width by the following method.

That is, exposure is performed by the flare measuring mask 200 to form a predetermined photoresist pattern (not shown) on the wafer. Next, the region in which the photoresist pattern is formed by the flare measurement mask 200 is classified vertically and horizontally as shown in FIG. 16 to form a mesh region 310 in a matrix form. Subsequently, the line width of the photoresist pattern (not shown) in each mesh region 310 is measured, and then the measured line width is represented by a Gaussian distribution, which is then convolutionally calculated to obtain each mesh region 310. The convolution value for the line width of the photoresist pattern is measured. The convolution operation is, as is known, overlapping and integrating two functions while y-axis flipping one of the two functions in the time domain or the frequency domain.

Using the convolution values for the line width of the photoresist pattern thus measured, the error value of the critical dimension (CD) per mesh area is measured by the following equation. Here, the critical dimension error value indicates how far from the determined critical dimension.

× Max CD error

Here, "CD error wafer" represents the critical dimension error value of the wafer mesh region 310 as described above, and "convolution value" represents the convolution value of the line width of the photoresist pattern of the wafer mesh region 310. Indicates. In addition, "convolution max" represents the maximum value of the convolution value in the entire mesh area 310. Since "1" appears in the area where the opening and closing ratio is 0%, the maximum value of the convolution value is 1. In addition, the "Max CD error" represents the line width difference of the maximum photoresist pattern. For example, the "Max CD error" is 20 nm in the graph of FIG. 8.

Accordingly, the convolution value for each mesh region 310 may be measured by Equation 1 to measure the critical dimension error value of each mesh. When the critical dimension error value is measured in this way, the line width of the line pattern 130 between the transmission pattern (see 110 in FIG. 6) or the transmission pattern 110 of the mask region corresponding to the mesh region 310 is adjusted by this error value. The line width of the photoresist pattern is corrected.

For example, FIG. 16 illustrates a convolution value of each mesh area 310, and a specific area having a convolution value of 0.3 will be described by way of example.

First, assuming that the convolution value of the mesh region 310 is 0.3, the CD value of the original photoresist pattern is 100 nm, and the maximum critical dimension error value is 20 nm, the critical dimension of the photoresist pattern of the mesh region 310 is The error value is 6 nm, and the size of the photoresist pattern formed in the mesh region 310 is 94 nm, which is as small as 6 nm than the original size. That is, overexposure is caused by scattered light under the influence of the flare, so that the photoresist pattern is formed smaller by 6 nm.

Accordingly, to correct this, the pattern in the mask corresponding to the mesh region 310, that is, the interval between the line patterns 130, is corrected so that the line width of the photoresist pattern can be made as large as 6 nm when exposed on the wafer. do. In this case, when the reduction projection multiple of the exposure equipment is 1: 1, the interval of the line pattern 130 may be formed to be about 6 nm larger, but when the reduction projection multiple is 4: 1, for example, it is about 24 nm larger. Then, when exposed with a mask having such a pattern, a photoresist pattern having a line width of 100 nm can be formed on the wafer in consideration of the flare value.

On the other hand, in order to correct more accurately, it is possible to consider a reduced projection multiple of the exposure equipment.

The error value of the critical dimension is not only an error due to the flare effect, but also an error of the exposure equipment itself. Accordingly, in the present embodiment, the mask error enhancement factor (MEEF), which is an error factor of the mask itself, is obtained, and then the critical dimension correction value of the mask is obtained based on this.

Here, MEEF is obtained as follows.

For example, when the size (line width) of the pattern in the mask is 0.42 mu m, when the substrate is exposed to the substrate, the photoresist pattern is formed with a line width of 0.105 mu m because there is no error in the exposure apparatus itself. In this case, MEEF is one. However, when exposed with a 0.42 μm pattern, if a photoresist pattern having a line width of 0.11 μm is formed, the MEEF becomes 2 in this case because the photoresist pattern is formed large by about 0.05 μm due to an error in the exposure apparatus itself.

By the critical dimension error values of the MEEF and the photoresist pattern thus obtained, the critical dimension correction value of the mask is implemented by the following equation.

Here, "CD correction mask" represents the pattern critical dimension error value of the mask, "MEEF" represents the error factor of the reduction projection exposure equipment, and "Mag" represents the reduction projection multiple. Since the current exposure equipment uses a 4x reduction projection exposure apparatus, "Mag" becomes four. "CD error wafer" represents the critical dimension error value of each mesh area of the wafer obtained above.

In view of such a convolution value and an error factor of the exposure equipment, the mask pattern critical dimension error value is obtained more accurately, and the critical dimension of the pattern in the mask is corrected by this error value.

11, 12A, 12B, 13A, 13B, 14, and 15 are plan views illustrating modified examples of the second mask, and the second mask may be modified in various forms.

First, as shown in FIG. 11, the sub light blocking layer 122 formed in the light transmission region 220 surrounds all the light transmission patterns 110 formed in the light transmission region 220. It can be formed in the form. The horizontal length x2 of the bar-shaped sub light blocking layer 122 may be the same as the horizontal length x1 of the sub light blocking layer 121 illustrated in FIG. 6. As a result, the sub light blocking layer 122 having the bar shape illustrated in FIG. 11 has a shape in which the light blocking layer is further disposed at the longitudinal interval of the sub light blocking layer 121 of FIG. 6. In this case, the area corresponding to the longitudinal interval between the sub light blocking layers 121 in FIG. 6 is very fine compared to the area of the entire transmissive region 220, and thus the same effect can be obtained even when the light blocking layer is formed in this portion.

In addition, the size of the light blocking region 210 may be arbitrarily adjusted.

That is, as shown in FIGS. 12A and 12B, the boundary line between the light blocking region 210 and the light transmitting region 220 may be moved in the longitudinal direction of the mask. Since the amount of flare and the area affected by the flare may be different for each position of the projection lens, as described above, by adjusting the size of the light blocking area 210, the amount of flare and the flare of each part of the projection lens in the longitudinal direction are affected. The area can be measured. In addition, the sub light blocking layer 121 in the light transmission region 220 may be formed in a bar shape as shown in FIG. 11.

In addition, as illustrated in FIG. 13, the light transmission patterns 110 formed at a predetermined size and at a predetermined interval may move in the transverse direction of the mask. As described above, since the flare area may be measured at the portions of the light transmission patterns 110, that is, the photoresist pattern, the light transmission patterns 110 may be designed to be suitable for the position where the flare is to be measured. .

In addition, as shown in FIG. 14, it is also possible to change both the size of the light blocking region 120 and the formation position of the light transmission pattern 110 so as to easily measure the flare of the desired wafer region. Here, in FIG. 14, the interface between the light blocking region 210 and the light transmitting region 220 is moved in the longitudinal direction of the mask 200, and the light transmission pattern 110 is disposed to the right side of the mask 200. Indicates a state of presence.

15A and 15B, the second mask shown in FIGS. 6, 11, 12A, 12B, 13, and 14 may be formed in a state of being rotated by 90 degrees. That is, in the above-described second masks 200, the light blocking region 210 and the light transmitting region 220 are divided into two horizontal directions. However, as shown in FIGS. 15A and 15B, the blocking region 210 and the transmission region 220 may be divided into two vertical directions to measure flare in the horizontal direction of the wafer.

As described in detail above, according to the present invention, by performing a photolithography process using a light blocking region having a plurality of light transmission patterns and a mask having a light transmission region, it is possible to measure whether a lens flare occurs. . In addition, the line widths of the photoresist patterns formed corresponding to the blocking region and the light transmitting region are compared to measure the flare amount of the lens and the region affected by flare on the wafer. In addition, by using the opening and closing ratio in the region affected by the flare, it is possible to measure the effective flare amount of the region affected by the flare. Accordingly, the line width change of the photoresist pattern on the wafer can be estimated from the effective flare amount of the region affected by the flare. In addition, a uniform pattern can be obtained on the wafer by correcting the line width of the mask pattern formed in the region affected by the flare.

In addition, since the exposure apparatus does not need to install a separate device for measuring the flare of the lens and the amount of flare, and to measure the area affected by the flare, manufacturing costs are greatly reduced.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. .

Claims (43)

The light blocking area and the light transmitting area are defined on the mask substrate, Flare measurement, which is formed in each of the light blocking region and the light transmitting region, wherein a plurality of line patterns blocking light and a plurality of light transmitting patterns transmitting light are formed to correspond to each other in the light blocking region and the light transmitting region Dragon mask. The method of claim 1, And each line pattern has the same line width. The method of claim 1, Each of the light transmission patterns has the same line width, flare mask for measuring. The method of claim 1, The light transmission pattern is a flare measuring mask, characterized in that the groove between the line pattern. A mask substrate; A main light blocking layer formed on a predetermined area of the mask substrate, dividing the mask substrate into a light blocking region and a light transmitting region, and having at least one light transmitting pattern formed thereon; And And at least one sub light blocking layer formed on a light transmission region of the mask substrate on which the main light blocking layer is not formed, and at least one light transmission pattern corresponding to the light transmission pattern of the main light blocking layer. Flare mask to measure. The method of claim 5, The light transmission pattern of the main light blocking layer is a plurality of arranged in the longitudinal direction, And the sub light blocking layer has a same size and is arranged in a longitudinal direction. The method of claim 6, The flare measurement mask, characterized in that each light transmission pattern is the same size. The method of claim 6, A flare measurement mask, characterized in that the lateral spacing of each light transmission pattern is the same. The method of claim 6, Flare measurement mask, characterized in that the longitudinal interval of each light transmission pattern is the same. The method of claim 5, The flare measuring mask of claim 1, wherein the boundary between the main light blocking layer and the light transmitting region is a straight line. The method of claim 10, The straight line is a mask for flare measurement, characterized in that orthogonal to the line connecting the center of the light transmission pattern. The method of claim 5, And the light blocking area and the light transmitting area have the same size. The method of claim 12, The flare measuring mask of claim 1, wherein the boundary between the main light blocking layer and the light transmitting region is a straight line. The method of claim 13, The straight line is a mask for flare measurement, characterized in that orthogonal to the line connecting the center of the light transmission pattern. The method according to claim 5 or 14, And each light transmission pattern is arranged at the center of the mask substrate. The method according to claim 5 or 14, And the respective light transmission patterns are arranged on the left side or the right side of the mask substrate. The method of claim 5, The flare is a mask for measuring flare, characterized in that the measurement at the portion of the main light blocking layer and the light transmission pattern of the boundary portion of the light transmission region. The method of claim 5, The light transmission pattern is a flare measuring mask, wherein the groove is formed in the main light blocking layer and the sub light blocking layer. Forming a light blocking layer on the mask substrate; Forming at least one light transmission pattern on the light blocking layer; And A predetermined portion of the light blocking layer is removed to form a main light blocking layer defining the light blocking region and the light transmitting region, and at the same time, the light blocking layer is left to include a light transmitting pattern in the light transmitting region to form a sub light blocking layer. Method for producing a mask for measuring flare comprising the step of. The method of claim 19, The method of manufacturing a mask for flare measurement, characterized in that formed in the plurality of at least one light transmission pattern arranged in the longitudinal direction of the mask substrate. The method of claim 20, The method of manufacturing a mask for flare measurement, characterized in that each light transmission pattern is formed to have the same size. The method of claim 20, The method of manufacturing a mask for flare measurement, wherein the light transmission patterns are formed to have the same horizontal spacing. The method of claim 20, The method of manufacturing a mask for flare measurement, characterized in that the light transmission pattern is formed so that the longitudinal spacing is the same. The method of claim 19, And removing the light blocking layer such that the size of the light blocking area is equal to the size of the light transmitting area. The method according to claim 19 or 24, Wherein each light transmission pattern is arranged at the center of the mask substrate. The method according to claim 19 or 24, Wherein each light transmission pattern is arranged on the left or right side of the mask substrate. The method of claim 19, Forming the light transmission pattern and forming the main light blocking layer; A method of manufacturing a mask for flare measurement, comprising forming a light transmission pattern and removing a predetermined portion of the main light blocking layer such that a main light blocking layer, a boundary portion of the light transmitting region, and a light transmission pattern meet a portion to measure the flare. . A method of measuring an area affected by flares on a wafer by using the flare measuring mask according to claim 1, Forming a photoresist pattern on a wafer using the flare measuring mask; Measuring a line width of each photoresist pattern formed by the line pattern of the light blocking region of the flare mask and the photoresist pattern formed by the line pattern of the light transmission region; Determining whether flares are generated by comparing line widths of the photoresist patterns formed corresponding to the respective areas; Calculating a flare amount on the entire region exposed by the mask by a line width difference of the photoresist pattern between the regions when the flare is generated in the wafer; Measuring a section in which a line width changes rapidly between the photoresist patterns between the regions; And And setting a circle having a radius as a distance to a section where the line width is rapidly changed, and estimating a portion of the wafer corresponding to an area inside the circle as an area affected by flare. Method of measuring the area affected by flare. The method of claim 28, And before forming the photoresist pattern by using the flare measuring mask, checking whether the line patterns of each region of the flare measuring mask have a uniform size. How to measure the area affected by The method of claim 28, In determining whether the flare occurs, If the line width difference of the photoresist pattern between the regions is less than the measurement error of the measurement equipment, no flare is generated. If the line width difference is greater than the measurement error of the measurement equipment, the flare is affected by the flare on the wafer, characterized in that for determining the area. A method of measuring a flare-affected area on a wafer using a flare measuring mask according to claim 5, Forming a photoresist pattern on a wafer using the flare measuring mask; Measuring a line width of each photoresist pattern formed by the main light blocking layer of the light blocking region of the flare measuring mask and the photoresist pattern formed by the sub light blocking layer; Comparing the line width of the photoresist pattern formed by the main light blocking layer with the line width of the photoresist pattern formed by the sub light blocking layer to determine whether flares are generated; Calculating the amount of flare on the entire area exposed by the mask from the line width difference between the photoresist pattern formed by the main light blocking layer and the photoresist pattern formed by the sub light blocking layer when the flare is generated; Extracting a section in which the line width changes rapidly between the photoresist pattern formed by the main light blocking layer and the photoresist patterns formed by the sub light blocking layer; And And setting a circle having a radius as a distance to a section where the line width is rapidly changed, and estimating a portion of the wafer corresponding to an area inside the circle as an area affected by flare. How to measure areas affected by flares. The method of claim 31, wherein Before forming a photoresist pattern using the flare measuring mask, And determining whether each light transmission pattern of the flare measuring mask has a uniform size. The method of claim 31, wherein In determining whether the flare occurs, If the line width difference between the photoresist pattern formed by the main blocking layer and the photoresist pattern formed by the sub blocking layer is less than or equal to a measurement error of the measurement equipment, no flare occurs. If the line width difference between the photoresist pattern formed by the main blocking layer and the photoresist pattern formed by the sub blocking layer is greater than or equal to the measurement error of the measurement equipment, the flare is determined on the wafer. How to measure the area receiving. A method of correcting a photoresist pattern formed in a region affected by the flare of claim 26, Measuring an effective flare amount corresponding to an area affected by the flare; And And correcting the line width of the line pattern and the line width of the light transmission pattern formed in the mask area corresponding to the area affected by the flare in consideration of the effective flare amount of the area of the area affected by the flare. Pattern correction method. The method of claim 34, wherein Measuring the effective flare amount corresponding to the area affected by the flare, Calculating an opening / closing ratio of an area affected by the flare; And And calculating an effective flare amount of the region affected by the flare by converting the flare amount of the entire exposed region into the opening / closing ratio. 36. The method of claim 35 wherein Calculating the opening and closing ratio of the area affected by the flare, And calculating the ratio of the respective light transmission patterns to the total area of the light blocking layer in the area affected by the flare and the total area of the area. The method of claim 34, wherein Correcting the line width of the line pattern and the light transmission pattern of the mask, And increasing the line pattern size of the mask at a position corresponding to the area affected by the flare as much as the effective flare amount. A method of correcting a photoresist pattern formed in an area affected by a flare of claim 31, Measuring an effective flare amount corresponding to an area affected by the flare; And And correcting the line width of the light transmission pattern formed in the mask area corresponding to the area affected by the flare and the gap therebetween in consideration of the effective flare amount of the area of the area affected by the flare. Pattern correction method. The method of claim 38, Measuring the effective flare amount corresponding to the area affected by the flare, Calculating an opening / closing ratio of an area affected by the flare; And And calculating the flare amount of the area affected by the flare by converting the flare amount of the entire exposed area into the opening / closing ratio. The method of claim 39, Calculating the opening and closing ratio of the area affected by the flare, And calculating the ratio of each light transmission pattern to the total area of each light blocking layer in the area affected by the flare, and the ratio of the total area of the area to the flare. The method of claim 38, Correcting the line width of the light transmission pattern of the mask and the interval therebetween, The method for correcting a pattern of a flare-affected region, wherein the blocking pattern size of the mask at a position corresponding to the flare-affected region is made larger by the effective flare amount. Forming a photoresist pattern on the wafer by exposing using a flare measuring mask; Classifying a region on the wafer on which the photoresist pattern is formed into a plurality of mesh regions; Measuring a convolution value according to the flare of each of the mesh regions; Measuring a critical dimension error value of the photoresist pattern of the mesh area by the following equation; And Adjusting the line width of the line pattern of the mask corresponding to the mesh area by the critical dimension error value, The error value of the critical dimension of the photoresist pattern of the mesh area is Obtained by × Max CD error, Here, "CD error wafer" represents the critical dimension error value of the wafer mesh region, "convolution value" represents the convolution value of the corresponding wafer mesh region, and "convolution max" represents the maximum of the convolution value of the entire mesh region. A value representing " Max CD error " represents a maximum line width difference of the maximum photoresist pattern. Forming a photoresist pattern on the wafer by exposing using a flare measuring mask; Classifying a region on the wafer on which the photoresist pattern is formed into a plurality of mesh regions; Measuring a convolution value according to flares of each of the mesh regions; Measuring a critical dimension error value of the photoresist pattern of the mesh area by the following Equation 1; Calculating an error factor (MEEF) of the reduced projection exposure apparatus for forming the photoresist pattern; Using the critical dimension error value of the photoresist pattern and the error factor (MEEF) of the reduced projection exposure equipment, measuring the error value of the critical dimension of the pattern in the mask according to the following equation (2); And Correcting the critical dimension of the pattern in the mask by an error value of the critical dimension of the pattern in the mask, The error value of the critical dimension of the photoresist pattern of the corresponding mesh region of Equation 1 is Obtained by × Max CD error, The error value of the critical dimension of the pattern in the mask of Equation 2 is Is obtained by Here, "CD error wafer" represents the critical dimension error value of the wafer mesh region, "convolution value" represents the convolution value of the wafer mesh region, and "convolution max" represents the maximum of the convolution value of the whole mesh region. Value, " Max CD error " represents the maximum line width difference of the maximum photoresist pattern, " MEEF " represents the error factor of the reduced projection exposure equipment, and " Mag " The mask pattern correction method of the flare-affected area.