JP2007073666A - Method of correcting mask, method of manufacturing mask, and mask for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the deterioration of the fidelity of a transfer image on a wafer by making it possible to correct a mask pattern so as to appropriately respond to the influence of an inclination, even in a case that the inclination has arisen on the pattern side wall which forms a mask pattern, with respect to the mask for exposure corresponding to an extremely short ultraviolet light. <P>SOLUTION: A mask correction method concerning the mask for exposure carries out exposure transfer of the transfer image of a shape according to the mask pattern onto the wafer. An angle formed by a projection vector which projects an oblique incidence light on the mask surface and a mask pattern composition side, and corresponding relation between the angle of inclination of an absorption film side wall forming the composition side and the amount of the transfer image deformation or the pupil passage light volume for obtaining the transfer image, are specified beforehand. The angle of inclination of the side wall of the absorption film is recognized (S102), and the correction processing to the mask pattern is performed by using the correction amount which is determined for the correction amount to the mask pattern from the recognition result and the corresponding relation (S103). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mask correction method and a mask manufacturing method for an exposure mask used in a lithography process for forming a circuit pattern of a semiconductor device, particularly a reflective exposure mask corresponding to so-called ultrashort ultraviolet light. . Further, the present invention relates to the exposure mask.

  In recent years, with the miniaturization of semiconductor devices, a resist pattern formed by exposing and developing a resist, which is a photosensitive material applied on a wafer, and a circuit pattern obtained by etching using the resist pattern as an etching mask The line width is increasingly required to be minimized. Further, not only the line width but also the pitch between patterns is required to be further minimized. This minimization requirement can be addressed by making the wavelength of light used for resist exposure shorter, but the relationship between the wavelength of light and the resolution is expressed by the Rayleigh equation shown below. It is known that

  w = k1 × (λ / NA) (1)

  In this equation (1), w is the minimum pattern width to be resolved, NA is the numerical aperture of the lens of the projection optical system, and λ is the wavelength of the exposure light. Further, k1 is a process constant mainly determined by selection of resist performance and super-resolution technique, and it is known that k1 = 0.35 can be selected by using an optimum resist and super-resolution technique. Yes. The super-resolution technique is intended to obtain a pattern smaller than the wavelength by selectively using ± first-order diffracted light that is transmitted or reflected through the mask and diffracted by the light shielding pattern on the mask. is there.

According to Rayleigh's equation, for example, the minimum pattern width that can be handled when using a wavelength of 157 nm is w = 61 nm if a lens with NA = 0.9 is used. That is, in order to obtain a pattern width smaller than 61 nm, exposure light having a shorter wavelength or an immersion lens must be used. For example, when an immersion lens is used with a wavelength of 157 nm, the minimum pattern width when a lens with NA = 1.2 is used is 46 nm.
For this reason, from the generation of 45 nm, it is considered to use exposure light having a wavelength band of about 0.6 nm centered on 13.5 nm called extreme ultraviolet light (EUV; Extreme Ultra Violet) (for example, Patent Document 1). When using extremely short ultraviolet light, for example, in an exposure apparatus with NA = 0.25, a line width of w ≧ 32.4 nm can be formed from the Rayleigh equation under the condition of k1 ≧ 0.6, which has not been achieved previously. This is because it is possible to cope with minimization of the pattern width, pattern pitch, and the like.

However, when using ultrashort ultraviolet light with a wavelength of 13.5 nm, the mask for exposure and the optical system are composed of a reflective mask and a reflective optical system that reflect light, not a light transmissive mask and optical system. There is a need to. This is because up to ultraviolet light having a wavelength of 157 nm, for example, there are optically transparent materials such as CaF ₂ (calcium fluoride) and SiO ₂ (silicon dioxide). This is because there is no material that transmits ultrashort ultraviolet light having a desired thickness for ultrashort ultraviolet light having a wavelength of 13.5 nm.
When a reflective mask is used, the light reflected by the mask surface must be guided to the projection optical system without interfering with the light incident on the mask. Therefore, the light incident on the reflective mask is inevitably incident obliquely at an angle θ with respect to the normal of the mask surface. That is, when exposure is performed using ultrashort ultraviolet light, the light incident on the mask surface of the exposure mask is obliquely incident with an angle with respect to the normal of the mask surface (for example, Patent Document 2). This angle is determined from the numerical aperture NA of the lens of the projection optical system, the mask magnification m, and the size σ of the illumination light source. Specifically, for example, when a mask having a reduction ratio of 4 is used on a wafer, in an exposure apparatus with NA = 0.3, the light has an incident angle larger than 4.30 ° with respect to the normal of the mask surface. Must be incident on the mask. Similarly, in an exposure apparatus with NA = 0.25, light must be incident on the mask with an incident angle greater than 3.58 °. However, the actual exposure apparatus is designed to be larger than the above-described incident angle because of the limitation of the spatial arrangement of the optical system constituted by the mirror and the reduction of the design residual aberration. When the angle is 6 ° or more and NA = 0.30, the incident angle is generally 7 ° or more.

  As a reflection-type exposure mask corresponding to such oblique incidence, a multilayer film that reflects ultrashort ultraviolet light is provided on a substrate, and an absorption film that absorbs ultrashort ultraviolet light is provided on the multilayer film. (See, for example, Patent Document 3). Specifically, as shown in FIG. 58, for example, in a reflective exposure mask corresponding to ultrashort ultraviolet light, a multilayer in which Si (silicon) layers and Mo (molybdenum) layers are alternately stacked on the substrate 11. A mask blank film 12 having a film structure is formed, and an absorption film 13 is patterned on the mask blank film 12 to form a film. The ultra-short ultraviolet light incident obliquely is reflected by the mask blanks film 12 and is absorbed without being reflected by the portion where the pattern of the absorption film 13 is formed. As a result, a high contrast is obtained between the reflection part and the absorption part of the ultra-short ultraviolet light, thereby enabling pattern transfer onto an object to be exposed such as a wafer.

JP 2002-365785 A JP 2003-257810 A Japanese Patent Laid-Open No. 2002-222864

  However, when using ultra-short ultraviolet light, the light incident on the mask surface of the exposure mask is obliquely incident at an angle with respect to the normal of the mask surface, so that a good pattern transfer is not necessarily required. An image is not always obtained.

  For example, as shown in FIG. 58, when the exposure light is incident obliquely on the mask surface of the exposure mask, the projection vector obtained by projecting the incident light onto the mask surface and the constituent sides of the mask pattern are orthogonal to each other (hereinafter, In this case (referred to as “orthogonal incidence”), a shadow is generated by the absorption film 13 patterned on the mask blanks film 12, and a loss occurs in the amount of light transmitted from the mask onto the wafer. Alternatively, when the exposure light is incident obliquely on the mask surface, the incident light is absorbed and reflected by the pattern side wall of the absorption film 13, and a loss occurs in the amount of light transmitted from the mask onto the wafer. Alternatively, after the exposure light is incident on the mask blank film 12 obliquely and reflected by the mask blank film 12, the reflected light is absorbed and reflected by the pattern side wall of the absorption film 13 and transmitted from the mask onto the wafer. Loss occurs in the amount of light. Due to these loss of light quantity, in the case of orthogonal incidence, contrast deterioration occurs on the transfer pattern on the wafer, resolution performance declines, rectangularity of resist pattern cross-sectional shape, resist pattern side wall roughness increases, etc. cause.

  On the other hand, even if the exposure light is incident on the mask surface obliquely, as shown in FIG. 59, for example, the projection vector obtained by projecting the incident light onto the mask surface and the constituent sides of the mask pattern are parallel ( Hereinafter, this case is referred to as “parallel incidence”), and exposure light is not shielded by the shadow of the absorption film 13 patterned on the mask blanks film 12. Further, incident light is not absorbed and reflected by the pattern side wall of the absorption film 13. Alternatively, after the exposure light is obliquely incident on the mask blank film 12 and reflected by the mask blank film 12, the reflected light is not absorbed and reflected by the pattern side wall of the absorption film 13. That is, in the case of parallel incidence, contrast deterioration does not occur in the transfer pattern on the wafer as in the case of orthogonal incidence.

However, even in the case of parallel incidence, if the pattern side wall of the absorption film 13 is inclined, the influence of the inclination angle appears on the on-wafer transfer pattern. Further, in the case of orthogonal incidence, if the pattern side wall of the absorption film 13 is inclined, the amount of light loss that causes contrast deterioration varies depending on the inclination angle. In other words, if the mask absorption pattern side wall is inclined, the pattern transfer image on the wafer will be different from the desired shape due to the influence of the inclination angle, not only in the case of orthogonal incidence but also in the case of parallel incidence. .
Moreover, in the case of photolithography using a general transmissive exposure mask, exposure light is irradiated vertically onto the mask surface, so even if the pattern side wall forming the mask pattern is inclined, the inclination The angle and the deformation amount of the transferred image are unambiguous. However, in the reflective exposure mask corresponding to the ultrashort ultraviolet light, the inclination angle on the pattern side wall of the absorption film 13 is uniform. However, the amount of deformation of the transferred image in each case differs between parallel incidence and orthogonal incidence. The same can be said for the case where the projection vector on the mask surface and the angle formed by the sides of the mask pattern are arbitrarily different from each other.

  Therefore, the present invention can appropriately cope with the influence of the inclination of the exposure mask in the lithography process using the obliquely incident exposure light even when the pattern side wall forming the mask pattern is inclined. The mask pattern can be corrected so that the fidelity of the transferred image on the wafer can be prevented from being lowered, thereby improving the performance of the semiconductor device obtained through the lithography process. An object of the present invention is to provide a mask correction method, a mask manufacturing method, and an exposure mask.

  The present invention is a mask correction method devised to achieve the above object. That is, a mask blanks film having an action of reflecting ultrashort ultraviolet light, and an absorption film that is patterned on the mask blanks film and absorbs the ultrashort ultraviolet light, and is obliquely incident on the mask surface. A mask correction method for an exposure mask that exposes and transfers onto a wafer a transfer image having a shape corresponding to a mask pattern formed by the absorbing film by reflecting short ultraviolet light, and is obliquely incident on the mask surface. An angle formed by a projection vector obtained by projecting ultrashort ultraviolet light onto the mask surface and a constituent side of the mask pattern, an inclination angle of a side wall of the absorption film forming the constituent side, a deformation amount of the transfer image, or the Predetermining the correspondence relationship between the pupil passing light amount for obtaining a transfer image, recognizing the inclination angle of the side wall of the absorption film, from the recognition result and the correspondence relationship, And determining a correction amount for the serial mask pattern.

  The present invention is also a mask manufacturing method devised to achieve the above object. That is, a mask blanks film having an action of reflecting ultrashort ultraviolet light, and an absorption film that is patterned on the mask blanks film and absorbs the ultrashort ultraviolet light, and is obliquely incident on the mask surface. A mask manufacturing method for an exposure mask that exposes and transfers onto a wafer a transfer image having a shape corresponding to a mask pattern formed by the absorbing film by reflecting short ultraviolet light, wherein the mask is obliquely incident on the mask surface. An angle formed by a projection vector obtained by projecting ultrashort ultraviolet light onto the mask surface and a constituent side of the mask pattern, an inclination angle of a side wall of the absorption film forming the constituent side, a deformation amount of the transfer image, or the A correspondence relationship between the amount of light passing through the pupil for obtaining a transfer image is specified in advance, the inclination angle of the side wall of the absorption film in the exposure mask to be manufactured is recognized, and The correction amount for the mask pattern is determined from the recognition result and the correspondence relationship, and after the correction process for the mask pattern with the determined correction amount, the absorption film constituting the mask pattern is patterned. Features.

  The present invention also provides an exposure mask designed to achieve the above object. That is, a mask blanks film having an action of reflecting ultrashort ultraviolet light, and an absorption film that is patterned on the mask blanks film and absorbs the ultrashort ultraviolet light, and is obliquely incident on the mask surface. An exposure mask for exposing and transferring a transfer image having a shape corresponding to a mask pattern formed by the absorption film by reflecting short ultraviolet light onto a wafer, and the ultra short ultraviolet light incident obliquely on the mask surface. Depending on the angle formed by the projection vector projected onto the mask surface and the component side of the mask pattern, a correction process is performed with different correction amounts depending on the inclination angle of the side wall of the absorption film forming the component side, A mask pattern is formed.

In the mask correction method and mask manufacturing method of the above procedure, and the exposure mask of the above configuration, the inclination angle of the side wall of the absorption film is recognized, and the correction amount for the mask pattern is determined from the recognition result. At this time, the correction amount is determined by determining the angle formed by the projection vector obtained by projecting the ultra-short ultraviolet light obliquely incident on the mask surface onto the mask surface and the constituent side of the mask pattern, and the absorption film forming the constituent side. This is performed based on the correspondence between the inclination angle of the side wall and the amount of deformation of the transferred image or the amount of light passing through the pupil for obtaining the transferred image. That is, the amount of correction differs depending on the angle formed by the projection vector obtained by projecting the ultra-short ultraviolet light onto the mask surface and the constituent side of the mask pattern depending on the inclination angle of the side wall of the absorption film forming the constituent side. .
Therefore, the exposure mask obtained through the correction process with the determined correction amount is corrected appropriately corresponding to the influence of the inclination even if the pattern side wall is inclined when the exposure light is incident obliquely. Since the processing has been performed, it is possible to avoid the deterioration of the fidelity of the transferred image on the wafer.

  According to the mask correction method, the mask manufacturing method, and the exposure mask of the present invention, when exposure light is incident obliquely on the mask surface, even if the pattern side wall constituting the mask pattern is inclined on the mask surface, Since the fidelity of the transfer image on the wafer can be avoided, the pattern transfer image on the exposure object can be made as desired (as designed). That is, by using the present invention, the performance of a semiconductor device obtained through a lithography process using obliquely incident exposure light can be improved.

  Hereinafter, a mask correction method and an exposure mask according to the present invention will be described with reference to the drawings. Of course, the present invention is not limited to the embodiments described below.

[Outline of exposure mask]
First, a schematic configuration of the exposure mask will be briefly described. The exposure mask described here is used to transfer a desired pattern (for example, a circuit pattern) onto a wafer by reflecting ultrashort ultraviolet light in a lithography process, which is one process in a method for manufacturing a semiconductor device. It is. As used herein, “extremely short ultraviolet light” includes a wavelength shorter than the ultraviolet light used in the previous lithography process (for example, 1 nm to 100 nm, as represented by a wavelength of 13.5 nm). ) Is applicable.

As shown in FIG. 1, an exposure mask is a substrate such as SiO ₂ (silicon dioxide) glass or low expansion glass in order to expose and transfer a transfer image of a desired pattern onto the wafer by reflection of such ultrashort ultraviolet light. A mask blanks film 2 having an action of reflecting ultrashort ultraviolet light and an absorption film 3 that is patterned on the mask blanks film 2 and absorbs ultrashort ultraviolet light are formed on 1.
The mask blank film 2 has a structure in which, for example, Si (silicon) layers and Mo (molybdenum) layers are alternately laminated, and the number of repetitions of the lamination is generally 40 or more.
The absorption film 3 is made of a material that absorbs ultrashort ultraviolet light, and is composed of, for example, a TaN (tantalum nitride) layer. However, the absorption film 3 may be made of other materials as long as it can be used as a mask material for ultrashort ultraviolet light. Specifically, in addition to TaN, Ta (tantalum) or Ta compound, Cr (chromium) or Cr compound, W (tungsten) or W compound, and the like are conceivable.
For example, Ru (ruthenium) is used between the mask blanks film 2 and the absorption film 3 as an etching stopper when forming the absorption film 3 or for the purpose of avoiding damage when removing defects after the absorption film 3 is formed. It is conceivable to provide a buffer film 4 composed of a layer or SiO ₂ (silicon dioxide) or Cr (chromium).

When manufacturing an exposure mask having the above-described configuration, a mask blank film 2 is formed on the substrate 1, and a buffer film 4 is formed on the mask blank film 2 as necessary. Further, an absorption film 3 is formed, and the absorption film 3 may be patterned into a shape corresponding to a desired pattern using a known lithography technique.
Here, patterning refers to a pattern shape corresponding to a desired pattern to be transferred onto the wafer, that is, a pattern shape that is substantially the same as or substantially similar to the desired pattern. A typical example of such a pattern shape is a so-called line and space pattern.
When patterning, if the buffer film 4 is formed between the mask blank film 2 and the absorption film 3, the buffer film 4 functions as an etching stopper. Note that the buffer film 4 may be omitted if a sufficient etching selectivity between the mask blanks film 2 and the absorption film 3 can be secured and there is no damage at the time of defect removal.
By performing such patterning, a reflection exposure mask for extreme short ultraviolet light having a mask pattern for exposing and transferring a desired pattern as described above can be obtained.

  However, in manufacturing an exposure mask, it is assumed that correction processing is performed on a pattern formed by the patterning prior to patterning. That is, after the correction process for the mask pattern, the absorption film 3 constituting the mask pattern is patterned. This is because, for example, even if the pattern side wall of the absorption film 3 is inclined, the influence of the inclination is eliminated and the fidelity of the transferred image on the wafer is prevented from being lowered.

[Explanation of the effect of pattern side wall inclination]
Here, the influence of the inclination on the transferred image on the wafer when the pattern side wall is inclined will be described.

  As described above, with respect to the exposure mask, the absorption film 3 is patterned using a well-known lithography technique. Therefore, depending on the technique and procedure of the lithography technique, the side wall portion of the absorption film 3 may be mask blank film 2. It should be perpendicular (90 °) to the upper surface of the substrate, but if it is more, it may be inclined to about 70 °, generally about 80 to 90 °.

  When such a tilt occurs on the side wall of the mask pattern, in a transmissive exposure mask used in general photolithography, if the tilt angle is different, the transferred image on the wafer is often different. Are known. However, in a transmissive exposure mask, since exposure light is incident perpendicularly to the mask surface, the difference that occurs in the transferred image on the wafer does not depend on the arrangement of the mask pattern.

  On the other hand, even in the reflection type exposure mask that reflects the ultra-short ultraviolet light having the configuration shown in FIG. 1, if the pattern sidewall of the absorption film 3 is inclined, if the sidewall angle is different, the wafer The top transfer image will be different. However, in a reflective exposure mask, ultra-short ultraviolet light is incident obliquely on the mask surface, so depending on the angle formed by the projection vector that projects the incident light onto the mask surface and the sides of the mask pattern, Differences occur in the different ways of the upper transfer image. That is, in the reflection type exposure mask, when the side wall angle of the mask pattern is different, the transferred image on the wafer is different depending on the arrangement of the mask pattern.

  For example, as shown in FIG. 2 and FIG. 3, the cross section of the absorption film 3 has a forward taper shape on the pattern side wall of the absorption film 3 (a shape in which the width of the absorption pattern narrows from the bottom surface of the mask absorption pattern to the surface). ) Is taken as an example, incident light is incident on the mask pattern side (see FIG. 58) perpendicularly (see FIG. 2) and parallel incident (see FIG. 59). This is because the angle relationship between the incident light and the pattern side wall is different in the case (see FIG. 3), and the way in which the light is reflected differs accordingly. For example, as shown in FIGS. 4 and 5, the absorption film 3 has a reverse taper on the pattern side wall (a shape in which the absorption pattern width increases from the bottom surface of the mask absorption pattern to the surface). The same applies to the case where the tilt is generated, and the incident light is different between the case where the incident light is orthogonally incident on the sides of the mask pattern (see FIG. 4) and the case where the incident light is parallel incident (see FIG. 5). This is because the angle relationship with the pattern side wall is different, and the way in which light is reflected differs accordingly.

  As described above, in the reflection type exposure mask, depending on the angle formed by the projection vector of obliquely incident light onto the mask and the side of the mask pattern, the influence of the inclination generated on the side wall of the mask pattern differs. It appears in the transfer image on the wafer (specifically, different deformation amounts). Therefore, it can be obtained when the incident angle of the incident light is perpendicularly incident on the side of the mask pattern and when the incident is parallel, assuming that the side wall angle of the mask pattern is perpendicular to the mask surface, that is, an angle of 90 °. Even if correction processing using a known technique is performed so that the transferred images on the wafer are substantially the same, if the side wall of the mask pattern is inclined, the influence of the inclination cannot be eliminated, and the inclination As a result, the fidelity of the transferred image on the wafer decreases.

[Outline of mask correction method]
As described above, when the fidelity of the transfer image on the wafer is lowered due to the influence of the inclination generated on the side wall of the mask pattern, a transfer image different from the desired shape is obtained. Therefore, when the exposure mask shown in FIG. 1 is manufactured, even if the side wall of the absorption film 3 is inclined, the absorption film 3 is patterned to obtain a transfer image having a desired shape. Prior to this, the mask pattern is corrected.

  Here, the mask correction method according to the present invention will be described. The mask correction method described here is for correcting the deformation of the transfer image on the wafer due to the influence of the inclination of the mask pattern side wall described above.

In the mask correction method described here, as shown in FIG. 6, first, the figure shape on the mask is corrected so that the on-wafer transfer pattern widths are substantially the same in the case of orthogonal incidence and in the case of parallel incidence. (Step 101, the following steps are abbreviated as “S”). Specifically, in order to make the amount of light passing through the pupil substantially the same in the case of orthogonal incidence and parallel incidence, the pupil patterning light amount is increased by narrowing the line pattern width for orthogonal incidence on the quadruple mask, What is necessary is just to compensate the light quantity loss by orthogonal incidence on a mask. That is, the ratio Q _r of the pupil passing light quantity Q _{off-axis in} the case of oblique incidence with respect to the pupil passing light quantity Q _{parallel in} the case of parallel incidence is obtained using the following equation (2), and the pupil passing light quantity The line pattern width for orthogonal incidence may be narrowed so that the ratio Q _r becomes equal to “1”. At this time, Q _r is obtained when the mask pattern side wall angle is 90 °.

Q _r = Q _off-axis / Q _parallel (2)

This is equivalent to using the pupil passing light amount at parallel incidence as a reference. When correction is performed to narrow the line pattern width for orthogonal incidence so that the pupil-passing light quantity ratio Q _r is equal to “1”, for example, the absorption film 3 is formed of Ta, the thickness thereof is 108 nm, and the mask If the oblique incident angle with respect to the upper normal is 6.6 °, the line width corresponding to the 22 nm line on the wafer is 88 nm on the quadruple mask before correction of the amount of light passing through the pupil, whereas the mask after correction is 88 nm. The upper line width is 70 nm. That is, 18 nm correction is performed as a negative bias amount. Therefore, the pattern width of the absorption film 3 for forming the on-mask line pattern may be 78 nm. Alternatively, the on-mask pattern width may be appropriately set so that the on-wafer transfer pattern width is substantially the same for parallel incidence and orthogonal incidence.

  Then, after correcting the transfer pattern width on the wafer to be substantially the same in the case of parallel incidence and orthogonal incidence, correction for the influence of the inclination of the mask pattern side wall is then performed. For this purpose, first, the inclination angle of the side wall of the absorption film 3 that will be formed after the correction processing is recognized (S102). If the inclination angle is not uniform, the side wall shape is also recognized. The methods for recognizing the side wall inclination angle or the side wall shape are roughly classified into the following three types.

  In the first method, a test model of the exposure mask is formed under the same conditions as the formation conditions for the absorption film 3 that will be formed after the correction process, and the mask pattern side wall angle is determined from the mask cross-sectional shape in the test model. By detecting directly, the side wall angle is recognized. The side wall angle may be detected by, for example, observing the mask cross section with a scanning electron microscope.

  In the second method, a test model is formed in the same manner as in the first method, and the pattern sidewall angle in the test model is directly detected by a probe method such as an atomic force microscope. Recognize corners. You may carry out using nondestructive inspections other than an atomic force microscope.

In the third method, a test model is formed in the same manner as in the first or second method and the test model is used, or a known simulation technique is used without using the test model. By detecting the intensity of diffracted light from the mask pattern obtained by reflection, the side wall angle in the mask pattern is recognized. This, even when the pupil passes light quantity ratio Q _r is allowed thinned line pattern width to orthogonal incidence to equal "1", when there is a tilt in the mask on the pattern sidewalls, the pupil passes light quantity ratio by the sidewall angle This is based on the change of Q _r . That is, a phenomenon in which the intensity of low-order diffracted light that contributes to image formation on the wafer and the intensity of high-order diffracted light that does not contribute to image formation differ depending on the side wall angle. The details of the recognition of the sidewall angle by the third method will be described later.

  After recognizing the inclination on the side wall of the absorption film 3, that is, the mask pattern side wall angle or the side wall shape, by any one of the first to third methods as described above, the mask pattern side wall angle or the side wall shape is subsequently recognized. Based on the result, a correction amount for the mask pattern is determined, and a correction process for the mask pattern with the determined correction amount is performed (S103).

  The correction amount is determined by the difference between the angle formed by the projection vector obtained by projecting the oblique incident light onto the mask surface and the constituent side of the mask pattern, the inclination angle of the side wall of the absorption film 3 forming the constituent side, and the inclination angle. The correspondence relationship between the deformation amount of the transferred image by the above is specified in advance and stored as correspondence information in a table format, for example, and when the side wall angle is recognized, the recognition result and the correspondence relationship stored and retained It can be done based on information. Details of the correspondence relationship based on this will be described later.

  The correction process for the mask pattern may be performed by figure correction of the mask pattern, for example, in the case of the mask pattern. Examples of the figure correction include variable pattern line width. In addition, the formed film thickness of the absorbing film 3 to be formed may be corrected instead of the figure correction. Furthermore, it may be performed not on the mask pattern but on the optical system. Specifically, it is conceivable to correct a wavefront generated in the optical system. Since these correction processes may be performed using a known technique, a detailed description thereof is omitted here.

  With this correction process, in the mask pattern after correction, even when the exposure light is incident obliquely, even if the mask pattern side wall is inclined, correction is performed with a correction amount appropriately corresponding to the influence of the inclination. It will be broken. That is, according to the mask pattern after the correction process, a transfer image having a desired line width and shape can be exposed and transferred onto the wafer.

  Therefore, according to the mask correction method including the steps described above and the exposure mask obtained through the mask correction method, when the exposure light is obliquely incident on the mask surface, the sidewall of the absorption film 3 constituting the mask pattern Even if the pattern has an inclination, a transfer image having a desired line width and a desired shape can be exposed and transferred onto the wafer by correcting the mask pattern, so that the influence of the inclination of the pattern side wall can be eliminated. Therefore, it becomes possible to avoid the fidelity of the transferred image on the wafer from being deteriorated due to the influence of the inclination of the pattern side wall, and the transferred image can be made as desired (as designed). In other words, by performing the correction including the above-described steps, it is possible to improve the performance of the semiconductor device obtained through the lithography process using ultrashort ultraviolet light.

[Specific example of side wall angle recognition]
Next, in the series of mask correction processes described above, a case where the recognition of the mask pattern sidewall angle or the sidewall shape is performed using the third method will be described with a specific example.

First, how the intensity of low-order diffracted light that contributes to image formation on the wafer varies depending on the side wall angle will be described.
Here, the ratio Q _rs of the pupil passing light amount Q _sidewall when the mask pattern side wall is inclined with reference to the pupil passing light amount Q _parallel with respect to the mask pattern side wall angle 90 ° in parallel incidence is again shown in the following (3). Define it like an expression.

Q _rs = Q _sidewall / Q _parallel (3)

In this equation (3), the pupil passing light amount Q _sidewall is defined for both parallel incidence and orthogonal incidence.
_7-10 is explanatory drawing which shows the specific example of pupil passing light quantity Q _sidewall . 7 shows Q _rs for the case where the mask pattern side wall is inclined in a forward tapered shape to obtain a desired line pattern width of 22 nm on the wafer at a pitch of 44 nm, and FIG. 8 shows the desired line pattern width of 44 nm on the wafer at a pitch of 88 nm. Q _rs for the case where the mask pattern side wall has a forward tapered inclination. FIG. 9 shows Q _rs for the case where the mask pattern side wall is inclined in an inversely tapered shape to obtain a desired line pattern width of 22 nm on the wafer at a pitch of 88 nm, and FIG. 10 shows the desired line pattern width of 44 nm on the wafer. Q _rs for the case where the mask pattern side wall has an inversely tapered slope for obtaining a pitch of 88 nm. The line pattern is a pattern that is light-shielded by the absorption film 3 on the mask surface and transferred onto the wafer, and the desired line pattern width on the wafer is obtained with a mask pattern sidewall angle of 90 °. It is the line pattern width.

As is apparent from Q _rs for the case of the forward tapered shape shown in FIGS. 7 and 8, the amount of light passing through the pupil with respect to the mask pattern side wall angle differs between parallel incidence and orthogonal incidence. Similarly, in the case of the inversely tapered shape shown in FIGS. 9 and 10, the amount of light passing through the pupil with respect to the mask pattern side wall angle is different between parallel incidence and orthogonal incidence. That is, when the exposure light is incident obliquely on the mask, the amount of light passing through the pupil with respect to the mask pattern side wall angle differs between parallel incidence and orthogonal incidence, so the pattern width transferred onto the wafer also differs between parallel incidence and orthogonal incidence. It becomes.

  Next, the relationship between the intensity of higher-order diffracted light that does not contribute to image formation and the sidewall angle will be described. FIG. 11 is an explanatory view schematically showing an outline when the mask pattern side wall angle is recognized by detecting the intensity of high-order diffracted light. As shown in the figure, the mask pattern formed by the absorption film 3 is preferably composed of a line and space pattern. However, the pattern is not limited to the line and space pattern, and may be another pattern, for example, a hole pattern densely arranged. Here, since the 0th-order diffracted light propagates along the reflected optical axis, the minus and plus orders of the diffracted light are defined as shown in the figure.

  In order to measure the intensity of diffracted light, for example, it is conceivable to detect the intensity of minus-order high-order diffracted light.

  FIG. 12 is a diagram showing the high-order diffracted light intensity obtained from the on-mask line-and-space pattern for obtaining a pattern with a line width of 44 nm on the wafer at a pitch of 88 nm, as a relation of the mask pattern sidewall angle. Here, since the oblique incident angle on the mask is set to 6.6 °, the propagation direction of the −6th order diffracted light coincides with the incident direction of the exposure light on the mask. Therefore, in order to detect the intensity of higher-order diffracted light of −7th order or higher, the intensity of these diffracted lights is shown. The intensity of the −7th order diffracted light to the −10th order diffracted light is as the side wall deviates from the vertical shape in both the forward taper shape and the reverse taper shape (as the inclination angle decreases from 90 °). It shows a decreasing trend. The difference between the forward tapered shape and the reverse tapered shape can be distinguished by comparing the −9th order diffracted light and the −10th order diffracted light. In the case of the forward tapered shape, as shown in FIG. 12A, the intensities of the −9th order diffracted light and the −10th order diffracted light are different between the side wall angles of 80 ° and 70 °. On the other hand, in the case of the reverse taper shape, as shown in FIG. 12B, the intensities of the −9th order diffracted light and the −10th order diffracted light are substantially equal when the side wall angle is 80 ° or less. Furthermore, the difference between the forward taper shape and the reverse taper shape can also be distinguished by comparing the −7th order diffracted light and the −8 diffracted light. In the case of a forward tapered shape, as shown in FIG. 12A, the intensities of the −7th order diffracted light and the −8th diffracted light are substantially equal when the side wall angle is 70 ° or less. On the other hand, in the case of the reverse taper shape, as shown in FIG. 12B, the intensities of the −7th order diffracted light and the −8th diffracted light are different regardless of the side wall angle.

  FIG. 13 is a diagram showing the high-order diffracted light intensity obtained from the on-mask line-and-space pattern for obtaining a pattern with a line width of 22 nm on the wafer at a pitch of 44 nm, as a relation of the mask pattern side wall angle. Here, since the oblique incidence angle on the mask is set to 6.6 °, the propagation direction of the third-order diffracted light coincides with the incident direction of the exposure light on the mask. Therefore, the intensity of higher-order diffracted light of −4th order or higher is shown. The intensity of the fourth-order diffracted light tends to decrease as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °) in both the forward tapered shape and the reverse tapered shape. ing. The difference between the forward taper shape and the reverse taper shape can be distinguished by comparing the intensity of the −5th order diffracted light and the intensity of higher order diffracted light higher than the −6th order diffracted light. In the case of the forward taper shape, as shown in FIG. 13A, the intensity of the −6th order diffracted light is hardly detected regardless of the side wall angle. On the other hand, in the case of the reverse taper shape, as shown in FIG. 13B, the intensity of the -6th order or higher diffracted light increases as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °). To do.

  Thus, when the mask pattern sidewall has a forward tapered shape or an inversely tapered shape, the sidewall angle is specified by detecting high-order diffracted light, and the forward tapered shape and the reverse tapered shape are detected. Can be distinguished. That is, if high-order diffracted light is detected, the mask pattern side wall angle or side wall shape can be recognized based on the detection result.

[Specific example of correspondence based on correction amount determination]
Next, the correspondence based on determining the correction amount from the recognition of the side wall angle or the side wall shape, that is, the angle formed by the projection vector obtained by projecting the oblique incident light on the mask surface and the side of the mask pattern, The correspondence relationship between the inclination angle of the side wall of the mask pattern forming the constituent side and the deformation amount of the transferred image will be described with a specific example.

  First, as a specific example of the correspondence relationship, the characteristics of the relationship between the pattern sidewall angle at parallel incidence and orthogonal incidence and the line width of the transferred image are shown. The pattern sidewall has a forward taper shape and the desired pattern line width on the wafer. The case where is 44 nm will be described as an example. In the following description, the oblique incident angle of the exposure light with respect to the normal on the mask is 6.6 °, the numerical aperture (NA) of the lens of the projection optical system is 0.25, and the effective light source diameter (σ) is 0.8.

FIG. 14 is a diagram showing the relationship between the pattern line width and the pattern pitch for each of parallel incidence and orthogonal incidence with the pattern side wall angle in the forward tapered shape as a parameter. According to the example of the figure, it can be seen that as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °), the line width difference between parallel incidence and orthogonal incidence increases.
FIG. 15 to FIG. 17 are graphs showing the result of normalizing the difference in line width difference between parallel incidence and orthogonal incidence with a desired line width and representing it as a percentage, using the pattern pitch as a parameter. 15 shows an example when the film thickness of the absorption film 3 made of Ta is 64 nm, FIG. 16 shows an example when the film thickness of the absorption film 3 made of Ta is 86 nm, and FIG. 17 shows an absorption film made of Ta. This is an example when the film thickness of No. 3 is 108 nm. According to these figures, it can be seen that, regardless of the pattern pitch, the line width difference increases as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °). Furthermore, as the film thickness of the absorption film 3 increases, the line width difference also increases.

FIG. 18 is a diagram showing a specific example of the tolerance (allowable deviation angle from 90 °) that the pattern sidewall deviates from the vertical shape. In the illustrated example, the allowable line width difference is set to 0.5%, 1.0%, and 2.0% with respect to the desired line width.
As shown in the figure, the allowable deviation angle of the pattern side wall increases when the Ta film thickness of the absorption film 3 that forms the pattern side wall is small. In particular, when the allowable line width difference is set to 2.0%, the allowable deviation angle becomes larger than 10 °. When the Ta film thickness is 64 nm, the allowable deviation angle is further larger than 30 °. Further, when the allowable line width difference is set to 1.0%, the allowable deviation angle can be ensured to 5 ° even if the Ta film thickness is large.
Here, the difference in line width between parallel incidence and orthogonal incidence is a phenomenon that occurs when exposure light is incident obliquely on the mask, and when exposure light is incident vertically on the mask as in conventional photolithography. Therefore, it is desirable that the allowable line width difference be as small as possible.
However, when the allowable line width difference is set to 0.5%, if the Ta film thickness is large, the allowable deviation angle becomes 5 ° or less, which may make it difficult to form the mask pattern. Therefore, in that case, the Ta film thickness may be reduced to, for example, 64 nm, or the mask pattern may be corrected.

Next, the characteristics of the relationship between the pattern sidewall angle at parallel incidence and orthogonal incidence and the line width of the transferred image are shown as an example when the pattern sidewall has a forward taper shape and the desired pattern line width on the wafer is 22 nm. Will be described.
FIG. 19 is a diagram showing the relationship between the pattern line width and the pattern pitch for each of parallel incidence and orthogonal incidence with the pattern side wall angle in the forward tapered shape as a parameter. According to the example of the figure, it can be seen that as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °), the line width difference between parallel incidence and orthogonal incidence increases.
20 to 22 are graphs showing the result of normalizing the increase in the line width difference between the parallel incidence and the orthogonal incidence with a desired line width and representing the result as a percentage, using the pattern pitch as a parameter. 20 shows an example when the film thickness of the absorption film 3 made of Ta is 64 nm, FIG. 21 shows an example when the film thickness of the absorption film 3 made of Ta is 86 nm, and FIG. 22 shows an absorption film made of Ta. This is an example when the film thickness of No. 3 is 108 nm. According to these figures, it can be seen that, at any pattern pitch, the line width difference increases as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °). Furthermore, as the film thickness of the absorption film 3 increases, the line width difference also increases. This is particularly remarkable in a dense pattern arrangement with a pattern pitch of 44 nm. This is because the dense pattern reduces the light intensity contrast on the wafer and increases the influence of the sidewall angle.

FIG. 23 is a diagram illustrating a specific example of the tolerance (allowable deviation angle from 90 °) that the pattern side wall deviates from the vertical shape. In the illustrated example, the line width difference in a dense pattern having a pattern pitch of 44 nm is not considered. In the example of the figure, the allowable line width difference is set to 1.0% and 2.0% with respect to the desired line width.
As shown in the figure, the allowable deviation angle of the pattern side wall increases when the Ta film thickness of the absorption film 3 that forms the pattern side wall is small. For example, when the allowable line width difference is set to 1.0%, the Ta film thickness is 64 nm and the allowable deviation angle can be secured to 5 °. Further, when the allowable line width difference is set to 2.0%, the Ta film thickness is 90 nm or less, and the allowable deviation angle can be secured to 5 ° or more. On the other hand, when the allowable line width difference is 0.5%, the allowable deviation angle cannot be obtained. Furthermore, when considering a dense pattern with a pattern pitch of 44 nm, an allowable deviation angle cannot be obtained even if the allowable line width difference is set large. Therefore, in these cases, it is necessary to correct the mask pattern.

Next, the characteristics of the relationship between the pattern sidewall angle at parallel incidence and orthogonal incidence and the line width of the transferred image are taken as an example when the pattern sidewall has an inversely tapered shape and the desired pattern line width on the wafer is 44 nm. I will give you a description.
FIG. 24 is a diagram showing the relationship between the pattern line width and the pattern pitch for each of parallel incidence and orthogonal incidence with the pattern side wall angle in the inversely tapered shape as a parameter. According to the example of the figure, it can be seen that as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °), the line width difference between parallel incidence and orthogonal incidence increases.
FIG. 25 to FIG. 27 are graphs showing the result of normalizing the increase in the line width difference between parallel incidence and orthogonal incidence with a desired line width and representing the result as a percentage, using the pattern pitch as a parameter. 25 shows an example when the film thickness of the absorption film 3 made of Ta is 64 nm, FIG. 26 shows an example when the film thickness of the absorption film 3 made of Ta is 86 nm, and FIG. 27 shows an absorption film made of Ta. This is an example when the film thickness of No. 3 is 108 nm. According to these figures, it can be seen that, at any pattern pitch, the line width difference increases as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °). Furthermore, as the film thickness of the absorption film 3 increases, the line width difference also increases.

FIG. 28 is a diagram showing a specific example of the tolerance (allowable deviation angle from 90 °) that the pattern side wall deviates from the vertical shape. In the illustrated example, the allowable line width difference is set to 0.5%, 1.0%, and 2.0% with respect to the desired line width.
As shown in the figure, the allowable deviation angle of the pattern side wall increases when the Ta film thickness of the absorption film 3 that forms the pattern side wall is small. In particular, when the allowable line width difference is set to 2.0% or more, the allowable deviation angle becomes larger than 10 °. When the Ta film thickness is 64 nm and the allowable line width difference is 2.0%, the allowable deviation angle is further larger than 30 °. Further, when the allowable line width difference is set to 1.0%, the allowable deviation angle can be ensured to be 5 ° even if the Ta film thickness is 94 nm or less.
Here, the difference in line width between parallel incidence and orthogonal incidence is a phenomenon that occurs when exposure light is incident obliquely on the mask, and when exposure light is incident vertically on the mask as in conventional photolithography. Therefore, it is desirable that the allowable line width difference be as small as possible.
However, when the allowable line width difference is set to 0.5%, if the Ta film thickness is large, the allowable deviation angle becomes 5 ° or less, which may make it difficult to form the mask pattern. Therefore, in that case, the Ta film thickness may be reduced to, for example, 77 nm, or the mask pattern may be corrected.

Next, the characteristics of the relationship between the pattern sidewall angle at parallel incidence and orthogonal incidence and the line width of the transferred image are shown as an example when the pattern sidewall has an inversely tapered shape and the desired pattern line width on the wafer is 22 nm. Will be described.
FIG. 29 is a diagram showing the relationship between the pattern line width and the pattern pitch for each of parallel incidence and orthogonal incidence with the pattern side wall angle in the inversely tapered shape as a parameter. According to the example of the figure, it can be seen that as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °), the line width difference between parallel incidence and orthogonal incidence increases.
FIG. 30 to FIG. 32 are graphs showing the results of normalizing the difference in line width difference between parallel incidence and orthogonal incidence with a desired line width and representing them as a percentage, using the pattern pitch as a parameter. 30 shows an example when the film thickness of the absorption film 3 made of Ta is 64 nm, FIG. 31 shows an example when the film thickness of the absorption film 3 made of Ta is 86 nm, and FIG. 32 shows an absorption film made of Ta. This is an example when the film thickness of No. 3 is 108 nm. According to these figures, it can be seen that, at any pattern pitch, the line width difference increases as the side wall deviates from the vertical shape (as the inclination angle decreases from 90 °). Furthermore, as the film thickness of the absorption film 3 increases, the line width difference also increases.

FIG. 33 is a diagram showing a specific example of the tolerance (allowable deviation angle from 90 °) that the pattern side wall deviates from the vertical shape. In the illustrated example, the allowable line width difference is set to 0.5%, 1.0%, and 2.0% with respect to the desired line width. In the example shown in the figure, the result excluding the case where the pattern pitch is 44 nm is shown.
As shown in the figure, the allowable deviation angle of the pattern side wall increases when the Ta film thickness of the absorption film 3 that forms the pattern side wall is small. For example, when the allowable line width difference is set to 2.0%, the allowable deviation angle can be secured to 5 ° or more when the Ta film thickness is small. On the other hand, when the allowable line width difference is 0.5%, the allowable deviation angle cannot be obtained. Furthermore, when considering a dense pattern with a pattern pitch of 44 nm, an allowable deviation angle cannot be obtained even if the allowable line width difference is set large. Therefore, in these cases, it is necessary to correct the mask pattern.

From the characteristics of the relationship between the pattern side wall angle and the line width of the transferred image as described above, the angle formed by the projection vector onto the mask surface of oblique incident light and the pattern component side (that is, the distinction between parallel incidence and orthogonal incidence). ), The pattern side wall angle, and the amount of deformation of the line width of the transferred image, it is possible to specify the correspondence as described below.
Here, as an example of the condition for reducing the light intensity contrast on the wafer, the pattern line width 22 nm on the wafer is formed at a pitch of 44 nm, and for comparison, the pattern line width 22 nm is formed at a pitch of 88 nm. And a case where the pattern line width is 44 nm and the pitch is 88 nm.

34 to 36 are diagrams showing specific examples of results obtained by plotting the pattern line width on the wafer obtained by using the mask before mask pattern correction with respect to the mask pattern sidewall angle in the forward tapered shape. is there. FIG. 34 shows the pattern line width on the wafer with respect to the forward tapered shape for obtaining the desired pattern line width 22 nm on the wafer at a pitch of 44 nm, and FIG. 35 shows the order for obtaining the desired pattern line width 22 nm on the wafer at the pitch of 88 nm. FIG. 36 shows the pattern line width on the wafer for the forward taper shape for obtaining a desired pattern line width of 44 nm on the wafer at a pitch of 88 nm.
According to these examples, the pattern line width on the wafer monotonously increases in parallel incidence with respect to the mask pattern side wall angle in the forward taper shape, but on the wafer pattern line width in the case of orthogonal incidence. It turns out that once it gets thinner, it starts to increase monotonously. Thus, the correspondence between the pattern side wall angle and the line width deformation amount of the transferred image varies depending on the desired pattern width on the wafer, and also varies depending on whether parallel incidence or orthogonal incidence is performed.

FIGS. 37 to 39 are diagrams showing specific examples of results obtained by plotting the pattern line width on the wafer obtained by using the mask before mask pattern correction with respect to the mask pattern side wall angle in the reverse taper shape. is there. FIG. 37 shows an on-wafer pattern line width for obtaining a desired pattern line width of 22 nm on the wafer at a pitch of 44 nm, and FIG. 38 shows an inverse pattern for obtaining the desired pattern line width of 22 nm on the wafer at a pitch of 88 nm. 39 shows the pattern line width on the wafer with respect to the taper shape, and FIG. 39 shows the pattern line width on the wafer with respect to the reverse taper shape for obtaining a desired pattern line width of 44 nm on the wafer at a pitch of 88 nm.
According to these figure examples, with respect to the mask pattern side wall angle in the reverse taper shape,
It can be seen that the pattern line width on the wafer monotonously decreases with respect to the side wall angle of the mask absorption pattern with the reverse taper in both cases of parallel incidence and orthogonal incidence. However, the on-wafer pattern line width differs between parallel incidence and orthogonal incidence.

  Here, the correspondence between the parallel incidence and the orthogonal incidence, the pattern side wall angle, and the amount of deformation of the line width of the transferred image is illustrated, but the correspondence is related to the line width of the transferred image. It may be about the amount of light passing through the pupil instead of. This is because the pupil passing light amount is one of parameters for specifying the line width of the transferred image, and if the pupil passing light amount is determined, the line width of the transferred image is also determined.

[Specific example of correction amount determination]
As described above, in the case of a reflective exposure mask, since exposure light is incident on the mask surface obliquely, the line width of the transferred image on the wafer differs between parallel incidence and orthogonal incidence. Therefore, it is necessary to correct the graphic width of the pattern on the mask in order to widen the allowable range of the mask pattern side wall angle or to make the pattern line width on the wafer substantially the same for parallel incidence and orthogonal incidence. Also, in order to transfer the figure on the mask onto the wafer with the desired fidelity, it is necessary to deform the pattern figure on the mask.
For this purpose, the figure on the mask may be corrected so that the line width of the transferred image becomes a desired value. Alternatively, the figure on the mask may be corrected so that the pupil passing light amount ratio Q _rs becomes equal to “1”. With either method, substantially the same correction amount can be obtained.

  The correction amount for the figure on the mask is the recognition result of the inclination angle of the pattern side wall by the absorption film 3, the amount of deformation of the pattern side wall angle and the line width of the transferred image (or the amount of light passing through the pupil). It may be determined based on the correspondence between the two.

  Here, when the mask pattern side wall has a forward taper shape, in order to reduce the line width difference between parallel incidence and orthogonal incidence, a specific example will be given regarding the correction amount when performing line width correction of the figure on the mask. explain. Here, in addition to the correction for the mask pattern side wall angle, the correction for the oblique incidence effect and the correction for the optical proximity effect correction are performed simultaneously. Detailed description will be omitted because it may be performed using a known technique.

  40 to 42 are diagrams showing specific examples of the correction amount of the pattern line width on the quadruple mask with respect to the side wall angle of the mask pattern having a forward taper shape. The figure shows a case where the oblique incident angle of the exposure light with respect to the normal on the mask is 6.6 °, the numerical aperture (NA) of the lens of the projection optical system is 0.25, and the effective light source diameter (σ) is 0.8. The film thickness of the absorption film 3 made of Ta is 108 nm. FIG. 40 shows a correction amount for a mask pattern having a forward taper shape for obtaining a desired pattern line width of 22 nm on the wafer at a pitch of 44 nm, and FIG. 41 shows a desired pattern line width of 22 nm on the wafer for obtaining a desired pattern line width of 22 nm at a pitch of 88 nm. 42 is a correction amount for a mask pattern having a forward taper shape for obtaining a desired pattern line width of 44 nm on the wafer at a pitch of 88 nm.

  Specific examples of the pattern line width of the on-wafer transfer image obtained with the mask pattern to which these correction amounts are given are shown in FIGS. FIG. 43 shows the pattern line width actually obtained on the wafer, and the pattern line width of 22 nm was obtained at a pitch of 44 nm. FIG. 44 shows the pattern line width actually obtained on the wafer, and the pattern line width of 22 nm was obtained at a pitch of 88 nm. FIG. 45 shows the pattern line width actually obtained on the wafer, and the pattern line width of 44 nm was obtained with a pitch of 88 nm.

The line width difference between the parallel incidence and the orthogonal incidence in the transfer image on the wafer obtained with the mask pattern after correction with these correction amounts is normalized with the desired line width and expressed as a percentage. FIG. 46 to FIG. 48 show the width. FIG. 46 shows a line width difference when a pattern line width of 22 nm is obtained at a pitch of 44 nm. FIG. 47 shows a line width difference when a pattern line width of 22 nm is obtained at a pitch of 88 nm. FIG. 48 shows a line width difference when a pattern line width of 44 nm is obtained at a pitch of 88 nm.
From these results, it can be seen that even when the thickness of the absorption film 3 is as large as 108 nm, the allowable line width difference can be made 1.0% or less in absolute value.

  Subsequently, in order to reduce the line width difference between parallel incidence and orthogonal incidence when the mask pattern side wall has an inversely tapered shape, a specific example will be given regarding the correction amount when performing line width correction of the figure on the mask. explain. Here, it is assumed that correction for the oblique incidence effect and correction for the optical proximity effect correction are simultaneously performed in addition to the correction for the mask pattern side wall angle.

  49 to 51 are diagrams showing specific examples of the correction amount of the pattern line width on the quadruple mask with respect to the mask pattern side wall angle having the inversely tapered shape. The figure shows a case where the oblique incident angle of the exposure light with respect to the normal on the mask is 6.6 °, the numerical aperture (NA) of the lens of the projection optical system is 0.25, and the effective light source diameter (σ) is 0.8. The film thickness of the absorption film 3 made of Ta is 108 nm. 49 shows a correction amount for a mask pattern having a reverse taper shape to obtain a desired pattern line width of 22 nm on the wafer at a pitch of 44 nm, and FIG. 50 shows a desired pattern line width of 22 nm on the wafer at a pitch of 88 nm. FIG. 51 shows a correction amount for a mask pattern having a reverse taper shape for obtaining a desired pattern line width of 44 nm at a pitch of 88 nm on the wafer.

  Specific examples of the pattern line width of the on-wafer transfer image obtained with the mask pattern to which these correction amounts are given are shown in FIGS. FIG. 52 shows the pattern line width actually obtained on the wafer, and the pattern line width of 22 nm was obtained with a pitch of 44 nm. FIG. 53 shows the pattern line width actually obtained on the wafer, and the pattern line width of 22 nm was obtained with a pitch of 88 nm. FIG. 54 shows the pattern line width actually obtained on the wafer, and the pattern line width of 44 nm is obtained at a pitch of 88 nm.

The line width difference between the parallel incidence and the orthogonal incidence in the transfer image on the wafer obtained with the mask pattern after correction with these correction amounts is normalized with the desired line width and expressed as a percentage. FIG. 55 to FIG. 57 show the width. FIG. 55 shows a line width difference when a pattern line width of 22 nm is obtained at a pitch of 44 nm. FIG. 56 shows a line width difference when a pattern line width of 22 nm is obtained at a pitch of 88 nm. FIG. 57 shows a line width difference when a pattern line width of 44 nm is obtained at a pitch of 88 nm.
From these results, it can be seen that when the pattern line width is 22 nm, the allowable line width difference can be made 1.0% or less in absolute value even when the film thickness of the absorption film 3 is as large as 108 nm and the side wall angle is 73 °. . Further, in the case of the pattern line width of 44 nm, the allowable line width difference can be reduced to 1.0% or less in absolute value even when the thickness of the absorption film 3 is as large as 108 nm and the side wall angle is 60 °.

  As described above in detail, in the mask correction method, the mask manufacturing method, and the exposure mask in this embodiment, the inclination angle of the mask pattern side wall is recognized, and the recognition result is used as one of the parameters to correct the mask pattern. After the correction process, even if the mask pattern side wall is inclined when the exposure light is incident obliquely on the mask surface, the figure shape of the transferred image on the wafer can be obtained by parallel incidence and orthogonal incidence. (For example, the pattern line width) can be made substantially the same. Specifically, if the mask pattern correction described in the present embodiment is performed, a dense pattern having a pattern line width of 22 nm and a pitch of 44 nm may be used, or the absorption film 3 constituting the mask pattern may be thick. However, it is possible to obtain a good allowable line width difference that is impossible with the conventional technique.

  This means that the allowable range of the inclination angle of the mask pattern side wall that can be used as an exposure mask can be expanded. That is, even if the pattern side wall angle is not allowed in the prior art, the influence of the inclination angle can be eliminated by the correction processing using the inclination angle as a parameter, so that it can be used as an exposure mask. . Therefore, if the mask pattern correction described in this embodiment is performed, it can contribute to the improvement of the manufacturing yield of the exposure mask.

  That is, according to the mask correction method, the mask manufacturing method, and the exposure mask described in the present embodiment, even when the pattern side wall forming the mask pattern is inclined, the influence of the inclination is appropriately handled. Since the mask pattern to be obtained can be corrected, the fidelity of the transferred image on the wafer can be avoided, and as a result, the performance of the semiconductor device obtained through the lithography process using the exposure mask is improved. It becomes possible. In addition, the allowable range of the mask pattern sidewall angle can be expanded, and an improvement in the manufacturing yield of the exposure mask can be expected.

  In addition, although this embodiment demonstrated the suitable Example of this invention, this invention is not limited to the content. For example, in this embodiment, the case where the pattern side wall is inclined is exemplified by the case where the cross-sectional shape is a forward taper shape and the case of a reverse taper shape. The present invention can be applied to the combined triangular side wall, corrugated side wall, and the like in exactly the same manner. That is, a desired on-wafer line width and a desired on-wafer transfer shape can be obtained by performing on-mask figure correction on an arbitrarily shaped side wall.

It is a schematic diagram which shows the structural example of the mask for exposure which concerns on this invention. It is explanatory drawing which shows the relationship in the case where the projection vector on the mask of diagonally incident light is orthogonally incident on the pattern constituting side with respect to the pattern side wall having the forward taper shape inclination, and W in the figure indicates the middle of the pattern side wall inclination. The pattern width defined by dots, P is the width of the pattern pitch defined by the midpoint of the pattern side wall slope. It is explanatory drawing which shows the relationship when the projection vector on the mask of diagonally incident light injects into a pattern structure side in parallel with respect to the pattern side wall with the inclination of a forward taper shape, in the figure, W is a pattern side wall inclination. The pattern width defined by dots, P is the width of the pattern pitch defined by the midpoint of the pattern side wall slope. It is explanatory drawing which shows the relationship when the projection vector on the mask of a diagonally incident light is orthogonally incident on a pattern structure side with respect to the pattern side wall with a reverse taper-shaped inclination, and W is an upper surface of a pattern side wall inclination in the figure. , P is the pattern pitch width defined on the upper surface of the pattern side wall slope. It is explanatory drawing which shows the relationship in the case where the projection vector on the mask of oblique incident light injects into the pattern structure side in parallel with respect to the pattern side wall with the reverse taper-shaped inclination, and W is an upper surface of the pattern side wall inclination in the figure. , P is the pattern pitch width defined on the upper surface of the pattern side wall slope. It is a flowchart which shows an example of the procedure of the mask correction method which concerns on this invention. It is explanatory drawing which shows the specific example of pupil passing light quantity ratio _Qrs with respect to the case where the mask pattern side wall is the inclination of a forward taper shape in order to obtain desired line pattern width 22nm with a pitch of 44nm on a wafer. FIG. 10 is an explanatory diagram showing a specific example of a pupil passing light amount ratio Q _rs for a case where a mask pattern side wall is inclined in a forward taper shape for obtaining a desired line pattern width of 44 nm on a wafer at a pitch of 88 nm. It is explanatory drawing which shows the specific example of pupil passing light quantity ratio _Qrs with respect to the case where the mask pattern side wall is the inclination of a reverse taper shape in order to obtain desired line pattern width 22nm with a pitch of 44nm on a wafer. FIG. 9 is an explanatory diagram showing a specific example of a pupil passing light amount ratio Q _rs for a case where a mask pattern side wall has an inversely tapered inclination in order to obtain a desired line pattern width of 44 nm on a wafer at a pitch of 88 nm. It is explanatory drawing which shows typically the outline | summary in the case of recognizing a pattern side wall angle by detecting the diffracted light intensity which does not contribute to image formation on a wafer. FIG. 7 is an explanatory diagram showing the negative order high-order diffracted light intensity obtained from a line-and-space pattern on a mask for obtaining a pattern with a line width of 44 nm on a wafer at a pitch of 88 nm, as a relation of a mask pattern sidewall angle. It is explanatory drawing which showed the high-order diffracted light intensity | strength of the minus order obtained from the line-and-space pattern on a mask for obtaining the pattern of line width 22nm on a wafer with a pitch of 44 nm as the relationship of the mask pattern side wall angle. FIG. 6 is an explanatory diagram showing a specific example of pitch dependence of line width when a mask pattern sidewall angle of a forward taper is used as a parameter in an exposure amount for obtaining a line width of 44 nm at a pattern pitch corresponding to an isolated line pattern; It is the figure which illustrated the case where thickness was 108 nm. In the exposure amount to obtain a line width of 44 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 44 nm when the pattern pitch in the forward taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 64 nm. In the exposure amount to obtain a line width of 44 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 44 nm when the pattern pitch in the forward taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 86 nm. In the exposure amount to obtain a line width of 44 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 44 nm when the pattern pitch in the forward taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and is a diagram illustrating the case where the Ta film thickness is 108 nm. In the exposure amount to obtain a line width of 44 nm at a pattern pitch corresponding to an isolated line pattern, the allowable value of the ratio of the line width difference between the parallel incidence and the orthogonal incidence in the forward tapered shape to 44 nm is used as a parameter. FIG. 5 is an explanatory diagram showing a specific example of the relationship between the Ta film thickness and the pattern sidewall allowable inclination angle. FIG. 8 is an explanatory diagram showing a specific example of the pitch dependence of the line width when the mask pattern side wall angle of the forward taper shape is used as a parameter in the exposure amount for obtaining the line width of 22 nm at the pattern pitch corresponding to the isolated line pattern; It is the figure which illustrated the case where thickness was 108 nm. In the exposure amount to obtain a line width of 22 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence with respect to 22 nm when the pattern pitch in the forward taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 64 nm. In the exposure amount to obtain a line width of 22 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence with respect to 22 nm when the pattern pitch in the forward taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 86 nm. In the exposure amount to obtain a line width of 22 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence with respect to 22 nm when the pattern pitch in the forward taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and is a diagram illustrating the case where the Ta film thickness is 108 nm. In the exposure amount to obtain a line width of 22 m at a pattern pitch corresponding to an isolated line pattern, the allowable value of the ratio of the line width difference of 22 nm between parallel incidence and orthogonal incidence in the forward tapered shape to 22 nm is used as a parameter. FIG. 5 is an explanatory diagram showing a specific example of the relationship between the Ta film thickness and the pattern sidewall allowable inclination angle. FIG. 5 is an explanatory diagram showing a specific example of the pitch dependence of the line width when the mask pattern side wall angle of the reverse taper is used as a parameter in the exposure amount for obtaining a line width of 44 nm at a pattern pitch corresponding to an isolated line pattern, It is the figure which illustrated the case where thickness was 108 nm. In the exposure amount to obtain a line width of 44 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 44 nm when the pattern pitch in the reverse taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 64 nm. In the exposure amount to obtain a line width of 44 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 44 nm when the pattern pitch in the reverse taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 86 nm. In the exposure amount to obtain a line width of 44 nm with a pattern pitch corresponding to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 44 nm when the pattern pitch in the reverse taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 108 nm. In the exposure amount to obtain a line width of 44 nm at a pattern pitch corresponding to an isolated line pattern, the line width difference between the parallel incidence and the orthogonal incidence in the reverse taper shape is a parameter when the allowable value of the ratio to 44 nm is used as a parameter. FIG. 5 is an explanatory diagram showing a specific example of the relationship between the Ta film thickness and the pattern sidewall allowable inclination angle. It is a figure showing the pitch dependence of the line width when the mask pattern side wall angle of the reverse taper shape is used as a parameter in the exposure amount for obtaining the line width of 22 nm with the pattern pitch corresponding to the isolated line pattern, and the Ta film thickness is 108 nm. It is the figure which illustrated the case. In the exposure amount to obtain a line width of 22 nm with a pattern pitch equivalent to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 22 nm when the pattern pitch in the reverse taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and is a diagram illustrating the case where the Ta film thickness is 64 nm. In the exposure amount to obtain a line width of 22 nm with a pattern pitch equivalent to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 22 nm when the pattern pitch in the reverse taper shape is used as a parameter. Is a diagram showing a specific example of the relationship between the obtained value and the pattern side wall angle, and is a diagram illustrating the case where the Ta film thickness is 86 nm. In the exposure amount to obtain a line width of 22 nm with a pattern pitch equivalent to an isolated line pattern, the ratio of the line width between the parallel incidence and the orthogonal incidence to the ratio of 22 nm when the pattern pitch in the reverse taper shape is used as a parameter. Is a diagram illustrating a specific example of the relationship between the obtained value and the pattern side wall angle, and illustrates the case where the Ta film thickness is 108 nm. In the exposure amount to obtain a line width of 22 nm with a pattern pitch corresponding to an isolated line pattern, the line width difference between parallel incidence and orthogonal incidence in a reverse taper shape is a parameter when the allowable value of the ratio to 22 nm is used as a parameter. FIG. 5 is an explanatory diagram showing a specific example of the relationship between the Ta film thickness and the pattern sidewall allowable inclination angle. Explanatory drawing showing a specific example of the correspondence relationship between the forward tapered taper pattern side wall angle and the line width on the wafer when the desired line width of 22 nm is obtained with a pitch of 44 nm on the wafer if the pattern side wall angle is 90 ° It is. Explanatory drawing showing a specific example of the correspondence relationship between the forward tapered taper pattern side wall angle and the line width on the wafer when the desired line width of 22 nm is obtained with a pitch of 88 nm on the wafer if the pattern side wall angle is 90 ° It is. Explanatory drawing showing a specific example of the correspondence relationship between the forward tapered taper pattern side wall angle and the line width on the wafer when a desired line width of 44 nm can be obtained at a pitch of 88 nm on the wafer when the pattern side wall angle is 90 ° It is. Explanatory diagram showing a specific example of the correspondence relationship between the reverse tapered taper pattern side wall angle and the line width on the wafer when the desired line width of 22 nm can be obtained at a pitch of 44 nm on the wafer if the pattern side wall angle is 90 ° It is. Explanatory drawing showing a specific example of the correspondence relationship between the reverse tapered taper pattern side wall angle and the line width on the wafer when the desired line width of 22 nm can be obtained on the wafer with a pitch of 88 nm if the pattern side wall angle is 90 ° It is. Explanatory drawing showing a specific example of the correspondence relationship between the pattern side wall angle of the reverse taper shape and the line width on the wafer when a desired line width of 44 nm is obtained with a pitch of 88 nm on the wafer when the pattern side wall angle is 90 ° It is. It is explanatory drawing which shows the specific example of the correction amount of the line width on a 4 times mask with respect to the pattern side wall angle of a forward taper shape in order to obtain desired line width 22nm on a wafer with the pitch of 44nm. It is explanatory drawing which shows the specific example of the correction amount of the line width on a 4 times mask with respect to the pattern side wall angle of a forward taper shape in order to obtain desired line width 22nm with a pitch of 88nm on a wafer. It is explanatory drawing which shows the specific example of the amount of correction | amendment of the line width on 4 times mask with respect to the pattern side wall angle of a forward taper shape in order to obtain desired line width 44nm on a wafer with the pitch of 88nm. Explanatory drawing which shows the specific example of the line width on the wafer with respect to the pattern side wall angle of the forward taper shape after correcting the line width on the mask four times in order to obtain a desired line width of 22 nm on the wafer with a pitch of 44 nm. It is. Explanatory drawing which shows the specific example of the line width on the wafer with respect to the pattern side wall angle of the forward taper shape after correcting the line width on the mask four times in order to obtain a desired line width of 22 nm on the wafer with a pitch of 88 nm. It is. Explanatory drawing showing a specific example of the line width on the wafer with respect to the pattern side wall angle of the forward taper shape after correcting the line width on the mask four times in order to obtain a desired line width of 44 nm on the wafer at a pitch of 88 nm. It is. Line width difference between parallel incidence and normal incidence in the forward taper shape after correcting the line width on the quadruple mask when obtaining the desired line width of 22 nm on the wafer at a pitch of 44 nm It is explanatory drawing which shows the specific example of the relationship between the value obtained as a ratio with respect to 22 nm, and a pattern side wall angle. Line width difference between parallel incidence and normal incidence in the forward taper shape after correcting the line width on the quadruple mask when obtaining the desired line width of 22 nm on the wafer at a pitch of 88 nm It is explanatory drawing which shows the specific example of the relationship between the value obtained as a ratio with respect to 22 nm, and a pattern side wall angle. Line width difference between parallel incidence and normal incidence in the forward taper shape after correcting the line width on the quadruple mask when obtaining the desired line width of 44 nm on the wafer at a pitch of 88 nm. It is explanatory drawing which shows the specific example of the relationship between the value obtained as a ratio with respect to 44 nm, and a pattern side wall angle. It is explanatory drawing which shows the specific example of the correction amount of the line width on a 4 times mask with respect to the pattern side wall angle of a reverse taper shape in order to obtain desired line width 22nm on a wafer with a pitch of 44 nm. It is explanatory drawing which shows the specific example of the correction amount of the line width on 4 times mask with respect to the pattern side wall angle of a reverse taper shape in order to obtain desired line width 22nm with a pitch of 88nm on a wafer. It is explanatory drawing which shows the specific example of the correction amount of the line width on 4 times mask with respect to the pattern side wall angle of a reverse taper shape in order to obtain desired line width 44nm on a wafer with the pitch of 88nm. Explanatory drawing which shows the specific example of the line width on a wafer with respect to the pattern side wall angle of a reverse taper shape, after correcting the line width on a 4 times mask in order to obtain desired line width 22nm on a wafer with a pitch of 44 nm It is. Explanatory drawing which shows the specific example of the line width on a wafer with respect to the pattern side wall angle of a reverse taper shape after correcting the line width on a 4 times mask in order to obtain desired line width 22nm on a wafer with a pitch of 88 nm. It is. Explanatory drawing which shows the specific example of the line width on a wafer with respect to the pattern side wall angle of a reverse taper shape after correcting the line width on a 4 times mask in order to obtain desired line width 44nm on a wafer with a pitch of 88nm. It is. Line width difference between parallel incidence and orthogonal incidence in reverse taper shape after correcting line width on quadruple mask when obtaining desired line width 22nm on wafer with pitch 44nm It is explanatory drawing which shows the specific example of the relationship between the value obtained as a ratio with respect to 22 nm, and a pattern side wall angle. Line width difference between parallel incidence and normal incidence in the forward taper shape after correcting the line width on the quadruple mask when obtaining the desired line width of 22 nm on the wafer at a pitch of 88 nm It is explanatory drawing which shows the specific example of the relationship between the value obtained as a ratio with respect to 22 nm, and a pattern side wall angle. Line width difference between parallel incidence and normal incidence in the forward taper shape after correcting the line width on the quadruple mask when obtaining the desired line width of 44 nm on the wafer at a pitch of 88 nm. It is explanatory drawing which shows the specific example of the relationship between the value obtained as a ratio with respect to 22 nm, and a pattern side wall angle. It is explanatory drawing which shows the outline | summary in the case of the orthogonal incidence in which the projection vector on the mask of the diagonally incident light on a mask orthogonally crosses with respect to a mask pattern structure side. It is explanatory drawing which shows the outline | summary in case the projection vector on the mask of the diagonally incident light on a mask is parallel incidence parallel to a mask pattern structure side.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Mask blank film, 3 ... Absorption film

Claims (4)

A mask blank film having a reflection function of ultra-short ultraviolet light, and an absorption film patterned on the mask blank film to absorb the ultra-short ultraviolet light, and obliquely incident on the mask surface. A mask correction method for an exposure mask for exposing and transferring a transfer image having a shape corresponding to a mask pattern formed by the absorption film by reflecting light onto a wafer,
An angle formed by a projection vector obtained by projecting the ultra-short ultraviolet light obliquely incident on the mask surface onto the mask surface and the constituent side of the mask pattern, an inclination angle of the side wall of the absorption film forming the constituent side, and The correspondence relationship between the deformation amount of the transfer image or the amount of light passing through the pupil for obtaining the transfer image is specified in advance,
A mask correction method, comprising: recognizing an inclination angle of a side wall of the absorption film and determining a correction amount for the mask pattern from the recognition result and the correspondence relationship. The inclination angle of the side wall of the absorption film is recognized based on the intensity of diffracted light obtained by reflecting the ultrashort ultraviolet light obliquely incident on the mask surface on the mask surface. Item 2. The mask correction method according to Item 1. A mask blank film having a reflection function of ultra-short ultraviolet light, and an absorption film patterned on the mask blank film to absorb the ultra-short ultraviolet light, and obliquely incident on the mask surface. A mask manufacturing method for an exposure mask that exposes and transfers a transfer image having a shape corresponding to a mask pattern formed by the absorbing film by reflecting light onto a wafer,
An angle formed by a projection vector obtained by projecting the ultra-short ultraviolet light obliquely incident on the mask surface onto the mask surface and the constituent side of the mask pattern, an inclination angle of the side wall of the absorption film forming the constituent side, and The correspondence relationship between the deformation amount of the transfer image or the amount of light passing through the pupil for obtaining the transfer image is specified in advance,
Recognizing the inclination angle of the sidewall of the absorption film in the exposure mask to be manufactured, and determining the correction amount for the mask pattern from the recognition result and the correspondence relationship;
A mask manufacturing method, wherein after the correction process for the mask pattern with the determined correction amount, the absorption film constituting the mask pattern is patterned. A mask blank film having a reflection function of ultra-short ultraviolet light, and an absorption film patterned on the mask blank film to absorb the ultra-short ultraviolet light, and incident on the mask surface obliquely. An exposure mask for exposing and transferring a transfer image having a shape corresponding to a mask pattern formed by the absorbing film by reflecting light onto the wafer,
Depending on the angle formed by the projection vector obtained by projecting the ultra-short ultraviolet light obliquely incident on the mask surface onto the mask surface and the constituent side of the mask pattern, the difference in the inclination angle of the side wall of the absorbing film forming the constituent side An exposure mask characterized in that the mask pattern is formed by performing correction processing with different correction amounts.

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