JP5085366B2 - Photomask defect correction method and photomask manufacturing method - Google Patents

Description

  The present invention relates to a photomask defect correction method, a photomask manufacturing method, and a photomask used when a fine pattern such as an LSI is transferred by a projection exposure apparatus.

  Conventionally, high integration and circuit pattern miniaturization have progressed in large scale integrated circuits (LSIs). A photomask for manufacturing such a device is formed by forming a light-shielding film having a light-shielding property such as chromium on a transparent substrate that transmits exposure light such as quartz, and patterning this to form a light-shielding portion and a light-transmitting portion. Although it is manufactured, it is not possible to completely prevent the occurrence of defects.

  On the other hand, a phase shift mask has been proposed and put into practical use as a super-resolution technique. The phase shift mask is frequently used for manufacturing a semiconductor device having a fine pattern because of the advantages of resolution performance and depth of focus.

  Various types of phase shift masks such as Levenson type, edge enhancement type, auxiliary pattern type, chromeless type, and halftone type have been proposed.

  Among the phase shift masks, an alternating phase shift technique (alternating PSM or Levenson type phase shift mask) is useful for line and space in which the opening pattern is regularly repeated. In this phase shift mask, the resolution performance can be improved by giving a phase difference of about 180 ° to the light transmitted through the adjacent light transmitting portions. As a layer (phase shifter) that gives a phase difference, a quartz substrate is etched to form a digging portion, or a phase shift film that transmits exposure light can be used.

  For example, the Levenson-type phase shift mask is configured to include a light shielding pattern formed of a metal film such as chromium on a transparent substrate, and the light shielding portion and the light transmitting portion are repeated like a line and space pattern. When present, the phase of transmitted light transmitted through the adjacent light transmitting part via the light shielding part is configured to be shifted by 180 °. Since the phase of the transmitted light transmitted through these light transmitting portions is shifted, the resolution is prevented from being lowered due to interference of diffracted light, and the resolution of the line and space pattern can be improved.

  In such a phase shift mask, the optical path of [λ (2m−1) / 2] (∵m is a natural number) with respect to the transmitted light having the wavelength λ between the light transmitting parts adjacent via the light shielding part. By producing a length difference, a phase difference of 180 ° is produced between these transmitted lights. In order to generate such an optical path length difference, when the transparent substrate thickness difference d between the light transmitting portions adjacent to each other through the light shielding portion is n, the refractive index of the transparent substrate is expressed as [d = λ (2m-1) / 2n] may be satisfied.

  In the phase shift mask, in order to cause a difference in the thickness of the transparent substrate between the light transmitting portions, the thickness is reduced by digging the transparent substrate in one light transmitting portion. Alternatively, there is a method of increasing the optical path length by forming a film (shifter film) on the transparent substrate in one light transmitting portion. That is, the phase shift portion of the shifter-attached (convex portion) phase shift mask in which a light-transmitting film is deposited on a transparent substrate has a thickness d (= λ (2m−1) / 2n ′) ( n ′ is covered with a film (shifter) of the refractive index of the shifter film. In the phase shift portion of the digging-type phase shift mask in which the transparent substrate is dug, the transparent substrate is etched by a depth d (= λ (2m−1) / 2n). It should be noted that the light-transmitting portion where neither the shifter is deposited nor dug, or when the light-transmitting portion has a shallow dug portion and a deep dug portion, the shallow dug portion becomes a non-phase shift portion. .

  By the way, also in the phase shift mask, like the other masks, it is completely unavoidable that a pattern shape defect occurs at the time of manufacture. These defects include missing defects in the light-shielding film formed on the transparent substrate, or opaque defects generated on the transparent substrate, missing phase shifters in the phase shift region, and phase shift position shifts. Etc. are included. Such defects are corrected if possible, otherwise the entire mask is unusable.

  In the phase shift mask manufacturing process, a single mask is etched a plurality of times to complete the mask. In the manufacture of a phase shift mask, the manufacturing process is complicated and time consuming, and the probability of defect generation is also increased, compared with the case where a mask is completed by etching a light shielding film once in a normal mask (binary mask). .

  For example, a laser beam or FIB (Focused Ion Beam) is used as a method for correcting a surplus defect (a form in which a portion to be etched is not etched) generated when a phase shift portion is formed by etching a quartz substrate. In general, a method of removing the surplus portion of the defect or a method of scraping off the surplus portion of the defect with an extremely fine needle is generally applied.

  On the other hand, in the case of a missing defect (a form in which a portion that should not be etched is etched), the following defect correcting method has been proposed. That is, in Patent Document 1, when a concave phase defect occurs in a halftone phase shift mask or a Levenson type phase shift mask, an electron beam CVD film having a phase effect such as tetramethoxysilane is formed to a predetermined thickness. Therefore, a defect correction method for correcting the phase so as to be in phase is described.

  Patent Document 2 describes a method for preventing the occurrence of a divot caused by a pinhole in a resist pattern in a light transmitting portion of a Levenson type phase shift mask. According to this method, a protective film and a light shielding layer are sequentially formed in advance, and after patterning of the light shielding layer, if a pinhole occurs in the resist pattern for forming the digging portion, the protective film is used to form the pinhole. I am trying to fix it.

JP 2005-189492 A JP 2004-333800 A

  By the way, in the photomask, when a missing defect generated in the light transmitting portion is detected by inspection, the defect correction method described in Patent Document 1 cannot avoid a decrease in transmittance due to film deposition. There is. In addition, a method for correcting a missing defect in a quartz substrate by depositing a film is complicated and cannot be said to be simple.

  In addition, in the method described in Patent Document 2, a protective film is newly added to a normal Levenson mask, so that an additional film forming process is required, and a photolithography process (resist coating, etching) is performed on the protective film. , Resist stripping) is required. Therefore, there is a problem that the manufacturing process is increased and a new defect generation opportunity is generated.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and it is possible to easily and accurately correct a defect in a photomask that can be corrected for a missing defect generated during etching of a transparent substrate. It is an object of the present invention to provide a method, a method of manufacturing a photomask including such a defect correction, and a photomask having such a defect correction.

  In order to solve the above-described problems and achieve the object, the present invention has any one of the following configurations.

[Configuration 1]
The photomask defect correcting method according to the present invention is a photomask defect correcting method in which at least a light transmitting part and a light shielding part are provided by patterning a light shielding film formed on a transparent substrate and having a predetermined light shielding property. Then, when a defect occurs in the light transmitting portion, a light shielding film removing step of removing a predetermined amount of the light shielding film at the boundary portion between the light shielding portion adjacent to the light transmitting portion including the defect and the light transmitting portion ; And a step of flattening the recess caused by the defect by digging a predetermined amount of the light-transmitting portion including the defect, and in the light shielding film removing step, the light-transmitting portion is dug for flattening. The reduction of the amount of transmitted light due to the increase in side reflection is performed so as to reduce .

[Configuration 2]
The present invention provides a defect correction method of a photomask having the structure 1, the defect is characterized in that a missing defect occurring in the surface portion of the transparent portion.

[Configuration 3]
The present invention provides a photomask defect correcting method having Configuration 2, wherein the photomask is a light transmitting part, and a predetermined phase difference between the main light transmitting part and the exposure light transmitted through the main light transmitting part to the transmitted light. A phase shift mask having an auxiliary translucent portion that provides a predetermined amount of the main translucent portion in which a missing defect has been dug and a predetermined amount of the auxiliary translucent portion that has passed through the main translucent portion. The exposure light and the exposure light transmitted through the auxiliary light transmitting portion have a predetermined phase difference.

[Configuration 4]
The present invention is characterized in that, in the photomask defect correcting method having the configuration 3, the auxiliary light-transmitting portion has a line width that is not resolved when the photomask is exposed.

[Configuration 5]
The present invention is characterized in that in the photomask defect correcting method having the configuration 3 or the configuration 4, the transparent substrate is exposed in the light-transmitting portion in which the missing defect is generated.

[Configuration 6]
The present invention is the photomask defect correction method having the configuration 3 or the configuration 4, wherein the light-transmitting portion in which the missing defect is generated has a film formed on the transparent substrate exposed. It is.

[Configuration 7]
A photomask manufacturing method according to the present invention is a photomask manufacturing method in which at least a light-transmitting part and a light-shielding part are provided by patterning a light-shielding film formed on a transparent substrate and having a predetermined light-shielding property, It includes a defect correcting step by a defect correcting method having any one of Configurations 1 to 6.

In the photomask correction method having configuration 1, when a defect occurs in the light transmitting portion, a predetermined amount of the light shielding film at the boundary between the light shielding portion adjacent to the light transmitting portion including the defect and the light transmitting portion is provided. Since it has the process of reducing the reduction | decrease of the exposure light transmission amount of the translucent part by a defect by removing, the reduction | decrease of the transmitted light amount which arises in a defective part can be suppressed. Furthermore, the correction can be performed by adding a relatively simple process, and the yield of the photomask can be improved. Further, the correction of the missing defect includes flattening the concave portion caused by the missing defect by digging a predetermined amount of the light transmitting part including the missing defect, and the step of removing the predetermined amount of the light shielding film is performed by digging. Since the reduction in the amount of exposure light transmitted through the light transmitting portion is reduced, the concave portion caused by the missing defect is flattened, so that the defect is not transferred to the transfer object when the mask is used, and the pattern of the light transmitting portion Is accurately transcribed. Furthermore, the reduction of the amount of transmitted light due to side reflection is suppressed by digging the light transmitting part. Furthermore, correction can be performed with high accuracy by adding a relatively simple process.

  Here, the light-shielding film is not limited to a light-shielding film (optical density of about 3.0) that substantially completely shields the exposure light, but may be a part that shields part of the exposure light. For example, the exposure light transmittance may be about 30% or less.

In the defect correction method of a photomask according to the present invention having the structure 2, a defect may I missing defect der occurring in the surface portion of the transparent portion.

  Note that the term “digging” as used herein includes reducing the thickness of the transparent portion when the thin film is formed on the substrate.

  In the photomask defect correcting method according to the present invention having the configuration 3, the main light transmitting portion is dug by a predetermined amount and the auxiliary light transmitting portion is dug by a predetermined amount while the main light transmitting portion in which the missing defect is generated is dug. Since the transmitted exposure light and the exposure light transmitted through the auxiliary light-transmitting portion have a predetermined phase difference, the auxiliary light-transmitting is performed with respect to the phase shift amount in the main light-transmitting portion changed by digging in the missing defect. By adjusting the phase shift amount of the part, it is possible to give an appropriate phase difference between the two. Furthermore, correction can be performed with high accuracy by adding a relatively simple process.

  Here, the main light-transmitting portion and the auxiliary light-transmitting portion are not limited to an embodiment in which the size of the latter pattern is smaller than the former. As will be described later, patterns of the same size provided for the purpose of increasing the resolution by the phase shift effect may be used as in the case of line and space. Alternatively, the auxiliary light-transmitting portion may have a line width that is not resolved, and may be exclusively intended to increase the resolution of the main light-transmitting portion.

  Here, the predetermined phase difference is preferably 180 °. However, if it is in the range of about 180 ° ± 30 °, the effect of the present invention can be obtained. The main light-transmitting part and the auxiliary light-transmitting part are also included when both dimensions are equal. In addition, when the digging amount of the light-transmitting part in which the defect has occurred does not reach 30 ° as the phase shift amount, the auxiliary light-transmitting part may not be dug.

  In the photomask correction method according to the present invention having the configuration 4, the auxiliary light-transmitting portion has a line width that is not resolved at the time of exposure of the photomask, so-called for the purpose of assisting the resolution of the main light-transmitting portion. Since it is an auxiliary pattern, it is useful as a high-resolution phase shift mask. In such a case, the main light-transmitting portion can be accurately transferred and a suitable amount of transmitted light can be secured. In this case, the main light-transmitting part and the auxiliary light-transmitting part are adjacent to each other through the light shielding part. Here, when removing a predetermined amount of the light-shielding film at the boundary portion between the light-shielding portion and the light-shielding portion directly adjacent to the light-transmitting portion, the amount by which the line width of the light-shielding portion is halved is limited. It can be carried out. Also in this case, defect correction can be performed with high accuracy by adding a relatively simple process.

  In the photomask correcting method according to the present invention having the configuration 5, in the phase shift mask using the excavation of the substrate, the missing defect of the substrate can be corrected by a simple process. Alternatively, in a phase shift mask in which a shifter film is formed on a substrate and subjected to pattern processing, a missing defect generated in a light transmitting portion having an opening in the shifter film can be corrected by a simple process.

  In the photomask correction method according to the present invention having the configuration 6, in the phase shift mask in which the shifter film is formed on the substrate and subjected to pattern processing, the missing defect generated in the shifter film is corrected by a simple process. Can do.

  The method for manufacturing a photomask according to the present invention having the structure 7 includes a defect correcting step by the defect correcting method having any one of the structures 1 to 6, so that the defects generated during the etching of the transparent substrate can be easily obtained. And it can correct with high precision and can improve a yield.

  That is, the present invention provides a photomask defect correction method capable of easily and highly accurately correcting missing defects generated during etching of a transparent substrate, and a photo including such defect correction. It is possible to provide a mask manufacturing method and a photomask having such defect correction.

  Hereinafter, embodiments of a photomask defect correcting method according to the present invention will be described in detail with reference to the drawings, using a phase shift mask as an example. The phase shift mask is one of super-resolution techniques in recent photolithography. Various types of phase shift masks have been proposed. Among them, there is an auxiliary pattern type phase shift mask as a phase shift mask for forming an isolated pattern such as a contact hole.

  1A is a plan view of the auxiliary pattern type phase shift mask, and FIGS. 1B and 1C are cross-sectional views taken along a dotted line A in FIG.

  As shown in FIG. 1, the auxiliary pattern type phase shift mask is provided on the transparent substrate 1 by forming a light shielding film 21 having a predetermined pattern and a peripheral portion thereof. An auxiliary opening 23 is provided. For example, as shown in FIG. 1B, this phase shift mask is arranged so that the light passing through the main opening 22 and the light passing through the auxiliary opening 23 have a phase difference of about 180 degrees. The transparent substrate 1 in the portion 22 has a substrate digging portion 24 that becomes a phase shift portion digged into a predetermined depth. In this case, the auxiliary opening 23 is a non-phase shift portion. The auxiliary opening 23 is set to have a fine line width and a formation position so that the light passing through the auxiliary opening 23 does not resolve the resist on the transferred substrate. Here, the main opening and the auxiliary opening correspond to the main light transmitting portion and the auxiliary light transmitting portion in the present invention.

  Further, as shown in FIG. 1C, the transparent substrate 1 in the auxiliary opening 23 may have a substrate digging portion 25 that becomes a phase shift portion digged into a predetermined depth. . In this case, the main opening 22 is a non-phase shift portion.

  A manufacturing process of such an auxiliary pattern type phase shift mask will be described with reference to FIG.

  First, as shown in FIG. 2A, the light shielding film 2 and the first resist film 3 are sequentially formed on the transparent substrate 1. This light shielding film may be a single layer or a laminate.

  Next, as shown in FIGS. 2B and 2C, for example, using an electron beam drawing apparatus, a pattern corresponding to the main opening and the auxiliary opening is drawn, developed, and developed. A resist pattern 31 is formed. The light-shielding film 2 is etched by using the first resist pattern 31 as a mask to form the light-shielding film pattern 21 having the main opening 22 and the auxiliary opening 23, and then the remaining first resist pattern is peeled off. .

  Next, as shown in FIG. 2D, a second resist film 4 is formed on the light shielding film pattern 21.

  Then, as shown in FIG. 2 (e), for example, by using an electron beam drawing apparatus, a pattern corresponding to the auxiliary opening 23 is drawn on the second resist film 4, developed, and the second A resist pattern 41 is formed. By etching the transparent substrate 1 using the second resist pattern 41 as a mask, the substrate digging portion 25 is formed.

  Thereafter, as shown in FIG. 2F, the remaining second resist pattern 41 is peeled off to complete the auxiliary pattern type phase shift mask.

  In addition, although this manufacturing process is a form which digs the transparent substrate 1 in the auxiliary opening part 23, even when digging the transparent substrate 1 of the main opening 22, the manufacturing process is the same. That is, in FIG. 2E, the pattern corresponding to the main opening 22 is exposed and developed on the second resist film 4, and the transparent substrate 1 is etched using this resist pattern as a mask.

  FIG. 3 is a cross-sectional view showing a process in which defects occur in the manufacturing process of the phase shift mask and a defect correcting method according to the present invention.

  In such a manufacturing process, when the transparent substrate 1 shown in FIG. 2E is etched, as shown in FIG. 3A, for example, a pinhole is formed in the resist film 4 on the main opening 22. When there is a defect 4a, as shown in FIG. 3B, the transparent substrate 1 is etched, and a missing defect 1a is generated. Thereafter, as shown in (c) of FIG. 3, when the remaining second resist pattern 41 is peeled off, the main opening 22 has a missing defect.

  In the correction method according to the present invention, when the location of such a missing defect is specified by defect inspection, first, as shown in (d) of FIG. 3, the light shielding that forms the edge of the main opening 22 is performed. The membrane 2 is shaved to enlarge the main opening 22. As a result, it is possible to suppress a decrease in the amount of exposure light transmitted through the main opening caused by a missing defect. This is not limited to missing defects, and can also be applied to surplus defects generated in the main opening (when the light shielding film on the main opening is not sufficiently etched and the light shielding film remains or foreign matter adheres).

  Next, as shown in FIG. 3E, the transparent substrate 1 in the enlarged main opening 22 is cut and flattened to the deepest part of the missing defect. Accordingly, it is possible to reliably prevent the above-described defect from being transferred onto the transfer object when the mask is used. It should be noted that the exposure light incident on the main opening due to the digging for the flattening tends to reduce the amount of transmitted light because side reflection increases. However, as described above, since the size of the opening is enlarged, such a decrease in the amount of transmitted light can be offset. In other words, the dimension of the opening can be enlarged in consideration of the amount of transmitted light reduction due to side reflection of the dug blank accompanying the flattening when determining the enlarged dimension.

  Further, the transparent substrate 1 in the auxiliary opening 23 adjacent to the main opening 22 via the light shielding portion is cut and dug by the same depth as the main opening 22 is cut. This is because the amount of phase shift of the main opening changes with respect to the original design value by digging the main opening, so that the auxiliary opening is dug and the phase difference between them is within a predetermined range. It is. The predetermined range may be 180 ° ± 30 °. That is, the digging amount of the auxiliary opening is an amount that satisfies this phase difference range. If the depth of the missing defect is very small and the phase difference between the main opening and the auxiliary opening in the case of flattening is within the above range, the auxiliary opening may not be dug. is there. The defect correction is completed by the above process. In this way, as shown in FIG. 3F, an auxiliary pattern type phase shift mask with defect correction completed. The inspection after the defect correction can be performed by using a transfer microscope apparatus simulating a transfer optical system by an exposure machine when using a photomask, and comparing with a normal part pattern having no defect.

  The missing defects in the transparent substrate 1 that occur when the transparent substrate 1 is etched using the second resist pattern 41 are mainly voids generated in the resist film 4 as shown in FIG. (Pinhole) 4a is often the cause. As shown in (b) of FIG. 4, when etching is performed in a state where there is a gap 4a in the resist film 4, as shown in (c) and (d) of FIG. The missing defect 1a having a shape, size and depth corresponding to the size of the void in the resist film 4 is formed. The shape, size, and depth of the missing defect 1 a vary depending on the etching selectivity between the resist film 4 and the transparent substrate 1.

  The missing defect 1a of the transparent substrate 1 thus formed not only affects the pattern to be transferred, but also the light passing through this portion causes irregular reflection, thereby reducing the transmittance. In addition, depending on the shape and size of the defect, a phase difference may occur and transfer characteristics may be deteriorated. That is, in order to correct the missing defect of the transparent substrate 1, it is necessary to eliminate the defect, restore the transmittance, and return the phase difference of the transmitted light to the design value.

  FIG. 5 is a cross-sectional view illustrating a defect correcting method for a phase shift mask according to the present invention.

  In the defect correction method according to the present invention, first, as shown by an arrow A in FIG. 5, in order to recover the transmittance, the light shielding film 2 serving as the edge portion of the main opening 22 where the missing defect 1a occurs is Using an atomic force microscope (AFM) type correction device, it is shaved to increase the aperture area and increase the amount of light transmission as a whole. This takes into account the decrease in the amount of light transmitted on the side wall formed when the transparent substrate 1 is shaved in the next step, along with the decrease in the amount of transmitted light due to the missing defect.

  Next, as shown by an arrow B in FIG. 5, the entire transparent substrate 1 in the main opening 22 including the missing defect obtained by cutting the light shielding film 2 to increase the area is shaved to the deepest depth of the missing defect 1a. . In this state, the shape of the missing defect 1a itself disappears, but the phase difference of the transmitted light is deviated from a predetermined value set in advance with the auxiliary opening 23 due to the shaving. For example, when the auxiliary opening 23 is dug to a depth corresponding to a phase difference of 180 °, if the main opening 22 is cut by 50 ° including the missing defect 1a, the phase difference of 130 ° is subtracted. As a result, transfer characteristics are affected. Therefore, as shown by an arrow C in FIG. 5, the transparent substrate 1 in the auxiliary opening 23 is cut by the same depth as in the main opening 22, and the phase difference is returned to the original 180 °, thereby correcting the defect. Is completed.

  As described above, in the present invention, the transmittance and the phase difference can be returned to the normal state by using only one correcting means, and the defect correction is completed.

  In addition, as shown in FIG. 1B, the defect defect generated in the non-phase shift portion (auxiliary opening portion 23) also in the auxiliary pattern type phase shift mask in which the main opening portion 22 becomes the phase shift portion. This can be corrected by the same process as described above.

[Other Embodiments]
In the above-described embodiment, the defect correction in the auxiliary pattern type phase shift mask has been described. However, the present invention is not limited to the auxiliary pattern type phase shift mask, and other various phase shift masks such as FIG. As shown in FIG. 7, a phase shift mask having a main opening 22 of a line and an auxiliary opening 23 formed on both sides of the main opening 22, or a plurality of main openings 22 as shown in FIG. A phase shift mask arranged in close proximity to form one pattern, or a Levenson type in which a phase shift unit 22a and a non-phase shift unit 23a are arranged in parallel via a light shielding unit as shown in FIG. It can also be applied to defect correction in a phase shift mask.

  That is, the present invention can be applied to various phase shift masks in which a light shielding film processed into a desired pattern is used as a mask and a lower layer of the light shielding film is etched to form a recess in the lower layer. The light-shielding film only needs to have a transmittance having an effective light-shielding effect with respect to the resist of the transfer object used when the mask is used. This light shielding film may or may not have a phase shift effect.

  Furthermore, in the present invention, as shown in FIG. 9, the light-shielding film 21 formed on the substrate is subjected to pattern processing, and further, the shifter film is formed to perform pattern processing, whereby the shifter film is provided on the substrate. A phase shift mask having a main opening, or a shifter film 51 is formed under the light shielding film 21 as shown in FIGS. The present invention can also be applied to defect correction in a phase shift mask in which is formed.

  For example, the defect correction of the phase shift mask shown in (a) of FIG. 10 can be performed as follows. As shown in FIG. 11A, a shifter film 51 and a light-shielding film 21 are formed in this order on a substrate, and each is patterned to form a main opening formed by forming a shifter film on the substrate; An auxiliary opening is formed through which the transparent substrate is exposed. The exposure light phase difference between the main opening and the auxiliary opening is set to 180 °. Here, when the missing defect 51a occurs in the main opening 22, the location of the missing defect 51a is specified by defect inspection. First, as shown in FIG. 11B, the edge of the main opening 22 is detected. The light shielding film 21 forming the above is shaved to enlarge the main opening 23.

  Next, as shown in FIG. 11C, the shifter film 51 is cut down to the deepest part of the missing defect 51a to reduce the film and to flatten it. Next, as shown in FIG. 11 (d), the transparent substrate 1 in the auxiliary opening 23 in the vicinity of the main opening 22 is moved to the depth of the missing defect 51 a of the translucent film 51 in the main opening 22. Sharpen the corresponding depth. In this way, an auxiliary pattern type phase shift mask with defect correction completed.

  A manufacturing process of the phase shift mask according to the embodiment of the present invention will be described with reference to FIGS.

  As the transparent substrate 1, a quartz glass substrate having a 6-inch square size and a 0.25-inch thickness mirror-polished surface was used and subjected to predetermined cleaning. First, the light shielding film 2 made of chromium was formed on the transparent substrate 1 by a 100 nm-thickness sputtering method. Next, as shown in FIG. 2A, a positive electron beam resist (“ZEP7000” manufactured by Nippon Zeon Co., Ltd.) 3 was applied by spin coating to a film thickness of 500 nm.

Next, as shown in FIG. 2B, using the electron beam drawing apparatus, a pattern corresponding to the main opening 22 and the auxiliary opening 23 is drawn and developed to form the first resist pattern 21. Formed. Using this first resist pattern 21 as a mask, dry etching using a mixed gas of Cl ₂ and O ₂ was performed, so that the light shielding film 2 was formed as a light shielding film pattern 21 having a main opening 22 and an auxiliary opening 23. Then, as shown in FIG. 2C, the remaining first resist pattern was peeled off.

  Next, as shown in FIG. 2 (d), a positive electron beam resist (“ZEP7000” manufactured by Nippon Zeon Co., Ltd.) is used as the second resist film 4 on the light shielding film pattern 21 by spin coating. Application was at 500 nm.

As shown in FIG. 3A, an electron beam drawing apparatus is used to draw a pattern corresponding to the auxiliary opening 23 on the second resist film 4 and develop the second resist pattern 41. Formed. As shown in FIG. 3B, the quartz substrate was dry-etched by 170 nm with a mixed gas of CHF ₃ and O _{2 using} the resist pattern 41 as a mask.

  Thereafter, as shown in FIG. 3 (c), the remaining second resist pattern 41 was peeled off and defect inspection was carried out. As a result, a portion of the main opening 22 originally covered with the resist was resisted. It was found that there was a pinhole, and the substrate in that portion was etched and had a defect.

  Next, as shown in FIG. 3 (d), the edge portion of the main opening 22 where the missing defect occurred is cut using an atomic force microscope (AFM) type correction device to widen the main opening. .

  And as shown to (e) in FIG. 3, the transparent substrate 1 in the main opening part 22 containing a missing defect was shaved to the deepest part of a missing defect using the same apparatus, and was planarized. By using the probe of an atomic force microscope (AFM), it was possible to correct the light shielding film and the light transmitting part constituting the photomask in a simple manner.

  Next, as shown in FIG. 3 (f), in the auxiliary opening 23 in which the transparent substrate 1 has already been dug, the same depth as the main opening 22 is cut is added and the defect is corrected. Completed and completed an auxiliary pattern type phase shift mask. In addition, with respect to the mask for which the defect correction was completed, an inspection was performed using a transfer microscope apparatus (AIMS, manufactured by Carl Zeiss) that imitated the transfer optical system of the exposure machine, and the effect of the correction was confirmed.

  The auxiliary pattern type phase shift mask manufactured through the defect correction process described above showed good results equivalent to the normal part even in the defect correction part in the subsequent transfer to the wafer.

(A) is a top view of the auxiliary | assistant pattern type | mold phase shift mask used as the object of the defect correction method of the phase shift mask which concerns on this invention, (b) And (c) is sectional drawing in the dotted line A of (a). . It is sectional drawing which shows the manufacturing process of an auxiliary | assistant pattern type | mold phase shift mask. It is sectional drawing which shows the process in which a defect arises about the manufacturing process of a phase shift mask, and the correction method which concerns on this invention. It is sectional drawing and a top view which show the process in which a defect arises about the manufacturing process of a phase shift mask. It is sectional drawing which shows the defect correction method of the phase shift mask which concerns on this invention. It is a top view which shows the phase shift mask which has the main opening part of a filament, and the auxiliary opening part was formed in the both sides of this main opening part. FIG. 6 is a cross-sectional view and a plan view showing a phase shift mask in which a plurality of main openings are arranged close to each other to form one pattern. It is sectional drawing and a top view which show a Levenson type | mold phase shift mask. It is sectional drawing which shows the phase shift mask in which the shifter film which comprises a phase shift part is formed on the patterned light shielding film. It is sectional drawing which shows the phase shift mask in which the shifter film which comprises a phase shift part is formed in the lower layer of the patterned light shielding film. It is sectional drawing which shows the defect correction process in the phase shift mask shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 1a Missing defect 2 Light shielding film 21 Light shielding film pattern 22 Main opening 23 Auxiliary opening 24 Substrate digging part 25 Substrate digging part 51 Shifter film 51a Missing defect

Claims (7)

A photomask defect correcting method in which at least a light transmitting part and a light shielding part are provided by patterning a light shielding film formed on a transparent substrate and having a predetermined light shielding property,
A light-shielding film removing step of removing a predetermined amount of a light- shielding film at a boundary portion between the light-shielding part adjacent to the light-transmitting part and the light-transmitting part when a defect occurs in the light-transmitting part ;
Flattening the recesses caused by the defects by digging a predetermined amount of the light-transmitting part including the defects, and
In the light shielding film removing step, the defect correction of the photomask is performed so as to reduce the amount of transmitted light due to an increase in side reflection that occurs in the light transmitting portion dug for the planarization. Method. The defect, defect correction method of a photomask according to claim 1, wherein the a missing defect occurring in the surface portion of the transparent portion. The photomask is a phase shift mask having, as the light transmitting part, a main light transmitting part and an auxiliary light transmitting part that gives a predetermined phase difference to the exposure light transmitted through the main light transmitting part to the transmitted exposure light. Yes,
While digging a predetermined amount of the main translucent part in which the missing defect has occurred, by digging a predetermined amount of the auxiliary translucent part, the exposure light transmitted through the main translucent part and the auxiliary translucent part were transmitted. The photomask defect correction method according to claim 2, wherein exposure light has the predetermined phase difference. The defect correction method for a photomask according to claim 3 , wherein the auxiliary light-transmitting portion has a line width that is not resolved when the photomask is exposed. The resulting translucent portion of said missing defect, claim 3 or defect correction method of a photomask according to claim 4, wherein the transparent substrate is exposed. The resulting translucent portion of said missing defect, claim 3 or defect correction method of a photomask according to claim 4, characterized in that the film formed on the transparent substrate is exposed. A method of manufacturing a photomask that provides at least a light-transmitting part and a light-shielding part by patterning a light-shielding film having a predetermined light-shielding property formed on a transparent substrate,
Photomask manufacturing method, characterized in that it comprises a defect correction process by the defect correction method according to any one of claims 1 to 6.

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