JP3312703B2 - How to fix a phase shift photomask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reticle used for manufacturing high-density integrated circuits such as LSIs and VLSIs and a method for manufacturing the reticle, and more particularly to a reticle used for forming a fine pattern with high precision. The present invention relates to a method for repairing a photomask having a phase shift layer.

[0002]

2. Description of the Related Art A semiconductor integrated circuit such as an IC, an LSI, and a super LSI is coated with a resist on a substrate to be processed such as a silicon wafer, exposed to a desired pattern by a stepper or the like, and then developed, etched, doped, and CVD. And the like, that is, by repeating a so-called lithography process.

A photomask called a reticle used in such a lithography process tends to be required to have higher and higher accuracy as the performance and integration of a semiconductor integrated circuit become higher. DRA which is LSI
Taking M as an example, the dimensional deviation of a 5-fold reticle for a 1-Mbit DRAM, that is, a reticle having a size five times the size of a pattern to be exposed, can be obtained even when an average ± 3σ (σ is a standard deviation) is taken. , 0.15 μm is required. Similarly, a quintuple reticle for a 4 Mbit DRAM has a dimensional accuracy of 0.1 to 0.15 μm, and a quintuple reticle for a 16 Mbit DRAM has a dimensional accuracy of 0.05 to 0.1 μm. The dimensional accuracy of a 5X reticle for 64Mbit DRAM is 0.
A dimensional accuracy of 03 to 0.07 μm is required.

Furthermore, the line width of a device pattern formed using these reticles is 1 Mbit DRAM.
1.2 μm, 0.8 μm for 4 Mbit DRAM, 1 μm
0.5 μm for 6 Mbit DRAM, 64 Mbit DR
AM requires 0.35 μm more and more miniaturization, and various exposure methods have been studied to meet such a demand.

However, in the case of a next-generation device pattern of, for example, a 64-Mbit DRAM class, the resolution of a resist pattern is limited by a conventional stepper exposure method using a reticle. A reticle based on a new concept called a phase shift reticle has been proposed as disclosed in Japanese Patent Publication No. 58-173744 and Japanese Patent Publication No. 62-59296. Phase shift lithography using a phase shift reticle is a technique for improving the resolution and contrast of a projected image by manipulating the phase of light passing through the reticle.

[0006] Phase shift lithography will be briefly described with reference to the drawings. FIG. 2 is a diagram showing the principle of the phase shift method,
FIG. 3 is a diagram showing a conventional method, and FIG. 2 (a) and FIG.
(A) is a cross-sectional view of the reticle, FIG. 2 (b) and FIG. 3 (b)
2 (c) and 3 (c) show the light amplitude on the wafer, FIGS. 2 (d) and 3 (d) show the light intensity on the wafer, respectively, and 1 denotes the light intensity on the wafer. A substrate 2, a light shielding film 3, a phase shifter 3, and an incident light 4 are shown.

In the conventional method, as shown in FIG. 3A, only a light-shielding film 2 made of chrome or the like is formed on a substrate 1 made of glass or the like, and a light transmitting portion of a predetermined pattern is formed. However, in phase shift lithography,
As shown in FIG. 2A, a phase shifter 3 made of a transmission film for inverting the phase (a phase difference of 180 °) is provided on one of the adjacent light transmission portions on the reticle. Therefore, in the conventional method, the amplitude of light on the reticle is in phase as shown in FIG. 3 (b), and the amplitude of light on the wafer is also in phase as shown in FIG. 3 (c). While the pattern on the wafer cannot be separated as shown in FIG. 3D, in phase shift lithography, the light transmitted through the phase shifter
As shown in FIG. 2B, since the phases are made opposite to each other between the adjacent patterns, the light intensity becomes zero at the boundary of the patterns, and the adjacent patterns are clearly separated as shown in FIG. 2D. be able to. As described above, in the phase shift lithography, a pattern that cannot be separated conventionally can be separated, and the resolution can be improved.

Various structures have been studied for photomasks having such a phase shift layer, but each has its advantages and disadvantages.

A description will now be given, with reference to the drawings, of an example of a manufacturing process of a halftone type phase shift reticle which has a simple structure and is considered to be the most practical.

FIG. 5 is a sectional view showing a manufacturing process of a halftone type phase shift reticle.
32 is an etching stopper layer, 33 is a halftone light shielding layer made of chrome or the like, 34 is a phase shifter layer, 35 is a resist layer, 36 is ionizing radiation such as laser light or electron beam, 37 is an exposed portion, 38 is a light shielding layer 33 Is an etching gas plasma for the phase shifter layer, and reference numeral 40 is an oxygen plasma.

First, as shown in FIG.
On top, the etching stopper layer 32 and the phase shift layer 3
4. A halftone type phase shift photomask substrate is formed by laminating the light-shielding layers 33 in this order, and a resist is uniformly applied on the light-shielding layers 33 by a conventional method such as spin coating. A resist layer 35 having a thickness of about 0.1 to 2.0 μm is formed. The heating and drying treatment is usually performed at 80 to 200 ° C. for 5 hours, depending on the type of resist used.
Perform for about 60 minutes. Next, as shown in FIG.
A desired pattern is drawn on the resist layer 35 by ionizing radiation 36 using an exposure apparatus such as an electron beam drawing apparatus according to a conventional method. Subsequently, the resist pattern is developed with a predetermined developing solution and rinsed with a predetermined rinsing solution to form a resist pattern as shown in FIG.

Next, after performing a heat drying process and a descum process as required, the light shielding layer 33 exposed from the opening of the resist pattern is dried by the etching gas plasma 38 as shown in FIG. Etching is performed to form a light-shielding pattern (FIG. 3D). It is obvious to those skilled in the art that the formation of the light-shielding pattern may be performed by wet etching instead of dry etching by the etching gas plasma 38.

Subsequently, as shown in FIG. 1D, a portion of the phase shifter layer 34 exposed from the opening of the resist pattern and the light-shielding pattern is dry-etched by the etching gas plasma 39 to form a phase shifter pattern. Figure (e). It is obvious to those skilled in the art that the formation of this phase shifter pattern may be performed by wet etching instead of dry etching by the etching gas plasma 39.

Next, the remaining resist is ashed and removed by oxygen plasma 40 as shown in FIG.

Through the above steps, a halftone type phase shift reticle having a phase shifter 34 as shown in FIG.

In the above example of the manufacturing method, the structure in which the halftone light-shielding layer is formed on the phase shifter layer has been described. However, in the reverse structure in which the phase shifter layer is formed on the halftone light-shielding layer, It is clear that the same applies to

[0017]

However, in the conventional method of manufacturing a phase shift reticle as exemplified above, although the process of manufacturing a phase shift photomask is relatively easy, defect correction of a completed mask is difficult. There is a problem that is very difficult.

[0018] That is, residual defects of the light-shielding pattern missing defect, conventional laser repair device or focused ion beam but can be modified in defect repair device using (FIB) or the like, the phase made of SOG or SiO ₂ or the like Because the shifter is transparent, its residual and missing defects are very difficult to correct, and resolving this was one of the major missions of researchers.

The present invention has been made in view of such circumstances, and an object of the present invention is to inspect and correct defects in a phase shifter pattern in the state of a resist pattern during a phase shift photomask processing step, It is an object of the present invention to provide a more practical method for repairing a phase shift photomask, which can manufacture a highly accurate phase shift reticle having no defect in a phase shifter pattern after etching a shifter.

[0020]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has developed a method for stably manufacturing a high-accuracy phase shift photomask without greatly changing the conventional reticle manufacturing process. As a result of extensive studies, the present invention has been completed.

That is, according to the present invention, in the phase shift photomask manufacturing process, the defect is inspected and corrected in the state of the resist pattern serving as a direct or indirect mask for etching the phase shifter layer. A method for manufacturing a reticle having a phase shift layer, wherein the phase shifter layer is etched in a defect state.

The correction method of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a method of correcting a defect at a resist pattern stage in a manufacturing process of a halftone type phase shift reticle, in which 11 is a transparent glass substrate such as quartz glass, 12 is an etching stopper layer, Reference numeral 13 denotes a halftone light-shielding layer made of a metal such as chromium, molybdenum, silicon, aluminum, and titanium, and has a transmittance of 1 to 30% for excimer laser light, for example.
(Spin-on-glass), phase shifter layer made of deposited SiO _2, etc., 15 is a resist layer, 16 is a residual defect, 1
7 is a missing defect, 18 is a laser beam or a focused ion beam, 19 is a focused ion beam, 20 is a carbon-rich gas, 21 is a deposited carbon film, and 22 is an etching gas plasma.

First, as shown in FIG. 1A, in a manufacturing process of a halftone type phase shift photomask, after patterning a resist layer 15, a portion of the halftone light shielding layer 13 exposed from an opening of the resist pattern is removed. In the resist pattern state after the light-shielding pattern is formed by etching, a residual defect 16 and a missing defect 17 are present.
In this state, the resist pattern is inspected for defects. Then, as shown in FIG. 3B, the residual defect 16 is removed by sublimation of both the resist layer and the light shielding layer with a laser beam or a focused ion beam 18 to remove the remaining defect. The defect 17 is filled by depositing a carbon film 21 by irradiating a focused ion beam 19 in a carbon-rich atmosphere 20 such as pyrene.

Next, as shown in FIG. 2C, after the phase shifter layer 14 is etched with the etching gas plasma 22 in the state where the resist pattern has been corrected in this manner, the remaining resist is removed. Thus, a halftone type phase shift photomask as shown in FIG.

In this method, instead of the above, it is also possible to similarly modify only the resist pattern in a state before the light-shielding layer 13 is etched.

In the above description, the halftone light-shielding layer 13 is provided directly on the glass substrate 11 without providing the etching stopper layer 12 and the phase shifter layer 14.
In the case where a predetermined depth portion from the surface 1 is etched to form a phase shifter layer (for example, see Japanese Patent Application Laid-Open No. 3-172845), the inspection and correction can be similarly performed at the resist pattern stage of the etching mask.

Incidentally, the halftone type phase shift reticle is not limited to the one in which the light shielding film pattern 13 is located on the phase shifter pattern 14 as shown in FIG. There are those that arrange patterns. In this case, a halftone light-shielding layer and a phase shifter layer are formed in this order on a glass substrate, a resist layer is formed thereon, and the resist layer is patterned with ionizing radiation from an electron beam exposure apparatus or the like. Performing drawing, developing the resist layer after pattern drawing to form a resist pattern, etching the exposed phase shifter layer using the resist pattern as a mask, and subsequently exposing using the resist pattern and the phase shifter layer as a mask It is manufactured by etching the halftone light shielding layer and removing the remaining resist. In such a halftone phase shift reticle, when a resist pattern is formed, its defect is inspected and corrected in the same manner as described above.

Further, as one of the halftone type phase shift reticles, a structure in which a semitransparent thin film layer serving as a halftone light shielding layer and a phase shifter layer is provided on a glass substrate and patterned is disclosed by the applicant of the present invention in Japanese Patent Application No. H10-157,086. 3-28783
No. 2 proposes. In this reticle, a translucent thin film layer having a phase difference of 180 ° is formed on a glass substrate, a resist layer is formed thereon, and a pattern is drawn on the resist layer by ionizing radiation from an electron beam exposure apparatus or the like. Then, the resist layer after pattern drawing is developed to form a resist pattern, the exposed semi-transparent thin film layer is etched using the resist pattern as a mask, and the remaining resist is removed. Similarly, in such a halftone phase shift reticle, the defect is inspected at the stage of forming the resist pattern, and the defect is corrected in the same manner as described above.

As described above, before actually etching the phase shifter layer, the defects in the phase shifter pattern of the halftone type phase shift reticle are inspected and inspected in the state of the resist pattern as an etching mask. Although the correction has been made, the residual defect and the defective defect of the phase shifter pattern of the ordinary phase shift reticle as shown in FIGS. 4A and 4B can be similarly corrected.

FIG. 4A shows a phase shift reticle of a phase shifter lower type, in which an etching stopper layer 12, a phase shifter layer 14, and a light shielding layer 23 are formed on a glass substrate 11 in this order. A first resist layer is formed thereon, a pattern is drawn on the first resist layer by ionizing radiation from an electron beam exposure device or the like, and the first resist layer after pattern drawing is developed to form a first resist pattern Then, using the first resist pattern as a mask, the exposed light shielding layer 23 is etched to form a light shielding pattern. Subsequently, a second resist layer is formed on the light shielding pattern,
A pattern is drawn on the second resist layer with ionizing radiation from an electron beam exposure device or the like, and the second resist layer after pattern drawing is developed to form a second resist pattern. The exposed phase is formed using the second resist pattern as a mask. Shifter layer 14
Is etched to remove the remaining resist. Also in the phase shift reticle under the phase shifter, when the second resist pattern is formed, the defect can be inspected and corrected in the same manner as described above.

FIG. 4B shows a phase shift reticle placed on a phase shifter, in which an etching stopper layer 12 and a light shielding layer 23 are formed on a glass substrate 11 in this order. A resist layer is formed, a pattern is drawn on the first resist layer by ionizing radiation from an electron beam exposure device or the like, and the first resist layer after pattern drawing is developed to form a first resist pattern. The light-shielding layer 23 exposed by using the pattern as a mask is etched to form a light-shielding pattern. Subsequently, a phase shifter layer 14 and a second resist layer are formed on the light-shielding pattern in this order, and an electron beam is formed on the second resist layer. A pattern is drawn with ionizing radiation from an exposure device or the like, and the second resist layer after pattern drawing is developed to form a second resist pattern. Phase shifter layer 14 etched to expose a click has been prepared by removing the remaining resist. Also in this phase shifter-mounted phase shift reticle, when the second resist pattern is formed, its defect can be inspected and corrected in the same manner as described above.

In a phase shift reticle of a phase shifter underlay type, this function can be performed on an exposed portion of a glass substrate without providing a phase shifter layer under a light-shielding layer (for example, see Japanese Unexamined Patent Publication No. No. 172845). In this case, a light-shielding layer 23 is formed on a glass substrate, a first resist layer is formed thereon, and a pattern is drawn on the first resist layer by ionizing radiation from an electron beam exposure apparatus or the like. The first resist layer after drawing is developed to form a first resist pattern, and the exposed light shielding layer is etched using the first resist pattern as a mask to form a light shielding pattern. (2) forming a second resist layer, performing pattern drawing on the second resist layer with ionizing radiation from an electron beam exposure device or the like, developing the second resist layer after pattern drawing to form a second resist pattern, It is manufactured by etching a predetermined depth from the exposed surface of the glass substrate using the pattern as a mask and removing the remaining resist. In the phase shift reticle under the phase shifter, also at the stage when the second resist pattern is formed,
The defect can be inspected and corrected as described above.

In order to correct a missing defect of the phase shifter pattern of the halftone type phase shift reticle,
Since carbon filling the missing portion of the etching resist pattern finally remains on the reticle, its thickness is desirably controlled to a thickness at which the transmittance becomes almost the same as the transmittance of the halftone light-shielding layer. Also, in the case of a normal phase shift reticle, it is desirable to control the thickness so that the transmittance is reduced to some extent. Further, the material for filling the missing defects of the resist pattern serving as a mask for etching the phase shifter layer is not limited to carbon, has etching resistance, and has a transmittance and a phase difference even when remaining on the phase shifter pattern. Other materials can be used as long as they are of no problem and of sufficient thickness.

As is apparent from the above description, the method of correcting a phase shift photomask according to the present invention forms a resist thin film via a halftone light shielding layer provided on a phase shifter layer, and draws a pattern on the resist thin film. And then developed to form a resist pattern, in the step of manufacturing a phase shift photomask by etching the exposed halftone light shielding layer and the phase shifter layer using the resist pattern as a mask, in the step of manufacturing the phase shift photomask, Before the etching and after the etching of the halftone light-shielding layer, a defect of the resist pattern is inspected, and the defect defect portion of the resist pattern is a correction material having a transmittance substantially equal to the transmittance of the halftone light-shielding layer. The repair is characterized in that it is finally filled and repaired with a repair material remaining on the photomask. It is a method.

More specifically, for example, an etching stopper layer, a phase shifter layer, and a halftone light-shielding layer are formed in this order on a transparent substrate, and then a resist thin film is formed thereon. Perform pattern drawing,
Thereafter, a resist pattern is formed by development, and the exposed halftone light-shielding layer is etched using the resist pattern as a mask. Subsequently, the exposed phase shifter layer is etched using the resist pattern and the halftone light-shielding layer as a mask to perform phase shift. In the step of manufacturing a photomask, a defect of the resist pattern is inspected before the etching of the phase shifter layer and after the etching of the halftone light-shielding layer, and the transmittance of the halftone light-shielding layer is detected at a missing defect portion of the resist pattern. This correction method is characterized in that the correction material has substantially the same transmittance as that of the correction material, and is finally filled with the correction material remaining on the photomask and corrected.

[0036]

A halftone light-shielding layer is formed on a transparent substrate, a resist thin film is formed thereon, a pattern is drawn on the resist thin film, and then developed to form a resist pattern. Etching the exposed halftone light-shielding layer with the mask as a mask, and subsequently etching the exposed transparent substrate using the resist pattern and the halftone light-shielding layer as a mask to a predetermined depth to produce a phase shift photomask, Before the etching of the halftone light-shielding layer after the etching of the resist pattern is inspected for defects, the defect defect portion of the resist pattern is a correction material having a transmittance substantially the same as the transmittance of the halftone light-shielding layer, The feature is that it is finally filled and repaired with the repair material remaining on the photomask. It is a modified how.

[0038]

[0039]

[0040]

[0041]

[0042]

According to the present invention, in the step of manufacturing the phase shift photomask, the resist pattern is inspected for defects before the etching of the phase shifter layer and after the etching of the halftone light-shielding layer. The correction material that has almost the same transmittance as the transmittance of the halftone light-shielding layer, and is finally filled with the correction material remaining on the photomask and repaired. The correction can be easily performed without significantly changing the manufacturing process, and a high-precision halftone phase shift photomask can be manufactured.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for repairing a phase shift photomask according to the present invention will be specifically described below with reference to several embodiments.

Example 1 An SOG film was formed on a mask substrate formed by forming an etching stopper layer composed of an alumina thin film having a thickness of about 100 nm on an optically polished 5-inch square ultra-high purity synthetic quartz glass substrate. Coated by spin coating, heat dried, 0.38μm thick
A phase shifter layer made of SOG was formed. On this, a tungsten silicide thin film having a transmittance of about 15% was sputtered in an i-line region of a mercury lamp to produce a halftone type phase shifter photomask substrate having a three-layer structure. Subsequently, an electron beam resist CMS-EX is formed on the substrate.
(S) is applied by a spin coating method,
For 30 minutes to obtain a uniform resist thin film having a thickness of 0.6 μm.

Next, a pattern was drawn on this substrate by an electron beam exposure apparatus according to a conventional method. At this time, the exposure was performed at an acceleration voltage of 10 kV and an exposure amount of ² μC / cm ² .

Subsequently, the resist was developed with an organic solvent containing ethyl cellosolve and isoamyl acetate as main components, and rinsed with isopropyl alcohol to form a resist pattern.

Next, after post-baking at 150 ° C. for 30 minutes and descum treatment with oxygen plasma for 3 minutes, the tungsten silicide layer exposed from the opening of the resist pattern is formed using a gas mainly containing a fluorine-based gas. And dry-etched.

After the pattern formed of the light-shielding layer and the resist thus formed was inspected by a conventional photomask defect inspection apparatus, the detected defect was corrected using a laser repair defect removal apparatus and a FIB defect correction apparatus.

Subsequently, the phase shifter layer was dry-etched using a gas mainly containing a fluorine-based gas.

The remaining resist was ashed and removed by oxygen plasma to complete a halftone phase shift reticle.

The halftone phase shift photomask completed in this way was of a high quality in which no defect could be detected even when the appearance inspection was performed by a defect inspection apparatus.

Example 2 An etching stopper layer composed of a tin oxide thin film having a thickness of about 100 nm was formed on an optically polished 5-inch square ultra-high purity synthetic quartz glass substrate, and a SiO 2 film was formed on a mask substrate. _{The two} films were applied by a CVD method to form a phase shifter layer made of a 0.35 μm thick SiO ₂ film. A chromium thin film having a transmittance of about 15% in the i-line region of the mercury lamp was sputtered thereon to produce a halftone type phase shifter photomask substrate having a three-layer structure. Subsequently, an electron beam resist ZE is formed on the substrate.
P-520 (manufactured by ZEON CORPORATION) is applied by a spin coating method, and is heated at 180 ° C. for 30 minutes.
A uniform resist thin film having a thickness of 0.6 μm was obtained.

Next, a pattern was drawn on the substrate by an electron beam exposure apparatus according to a conventional method. At this time, the exposure was performed at an acceleration voltage of 10 kV and an exposure amount of 10 μC / cm ² .

Subsequently, the resist pattern was developed with a special developing solution and rinsed with a special rinsing solution to form a resist pattern.

Next, after descum processing is performed as required,
The halftone chromium layer exposed from the opening of the resist pattern was dry-etched using a gas mainly containing a fluorine-based gas.

After the pattern formed of the light-shielding layer and the resist thus formed was inspected by a conventional photomask defect inspection apparatus, the detected defect was corrected using a laser repair defect removal apparatus and a FIB defect correction apparatus.

Subsequently, the phase shifter layer was dry-etched using a gas mainly containing a fluorine-based gas.

The remaining resist was ashed and removed by oxygen plasma to complete a halftone phase shift reticle.

The halftone type phase shift photomask completed in this way was of a high quality in which no defect could be detected even when the appearance inspection was performed by a defect inspection apparatus.

Example 3 A chromium thin film having a transmittance of about 15% in the i-line region of a mercury lamp was sputtered on an optically polished 5-inch square ultra-high purity synthetic quartz glass substrate to form a halftone phase A shift photomask substrate was manufactured.
Subsequently, an electron beam resist ZEP-520 is formed on the substrate.
(Manufactured by ZEON CORPORATION) by a spin coating method, and heat-treated at 180 ° C. for 30 minutes to have a thickness of 0.6
A uniform resist thin film of μm was obtained.

Next, a pattern was drawn on this substrate by an electron beam exposure apparatus according to a conventional method. At this time, the exposure was performed at an acceleration voltage of 10 kV and an exposure amount of 10 μC / cm ² .

Subsequently, the resist was developed with a special developing solution and rinsed with a special rinsing solution to form a resist pattern.

Next, after descum processing is performed as necessary,
The chromium layer exposed from the opening of the resist pattern was dry-etched using a gas mainly containing a fluorine-based gas.

After the pattern formed of the light-shielding layer and the resist thus formed was inspected by a conventional photomask defect inspection device, the detected defect was corrected using a laser repair defect removal device and a FIB defect correction device.

Subsequently, the exposed quartz substrate was dry-etched using a gas mainly containing a fluorine-based gas.

The remaining resist was ashed and removed by oxygen plasma to complete a halftone type phase shift reticle.

The halftone phase shift photomask completed in this way was of a high quality in which no defect could be detected at all even when an appearance inspection was performed by a defect inspection apparatus.

(Comparative Example) SOG was spun on a mask substrate formed by forming an etching stopper layer composed of an alumina thin film having a thickness of about 100 nm on an optically polished 5-inch square ultra-high purity synthetic quartz glass substrate. The coating was applied by coating and subjected to a heat drying treatment to form a phase shifter layer made of SOG having a thickness of 0.38 μm. On top of this,
A half-tone type phase shifter photomask substrate having a three-layer structure was prepared by sputtering a tungsten silicide thin film having a transmittance of about 15% in the i-line region of a mercury lamp.
Subsequently, an electron beam resist CMS-EX is formed on the substrate.
(S) is applied by a spin coating method,
For 30 minutes to obtain a uniform resist thin film having a thickness of 0.6 μm.

Next, a pattern was drawn on this substrate by an electron beam exposure apparatus according to a conventional method. At this time, the exposure was performed at an acceleration voltage of 10 kV and an exposure amount of ² μC / cm ² .

Subsequently, the resist was developed with an organic solvent containing ethyl cellosolve and isoamyl acetate as main components, and rinsed with isopropyl alcohol to form a resist pattern.

Next, after post-baking at 150 ° C. for 30 minutes and descum treatment with enzyme plasma for 3 minutes, the tungsten silicide layer exposed from the opening of the resist pattern is formed using a gas mainly containing a fluorine-based gas. And dry-etched.

Subsequently, the phase shifter layer was dry-etched using a gas mainly containing a fluorine-based gas.

The remaining resist was ashed and removed by oxygen plasma to produce a halftone type phase shift reticle.

After the thus produced phase shift photomask was inspected for its appearance using a photomask defect inspection device, the detected defect was corrected using a laser repair defect removal device and a FIB defect correction device. It took a long time to remove the missing defects of the FIB etching, and the correction accuracy was poor.

[0075]

As is apparent from the above description, according to the method for correcting a phase shift photomask of the present invention, in the step of manufacturing the phase shift photomask, before the etching of the phase shifter layer, the halftone light shielding layer is formed. After the etching of the resist pattern, the defect of the resist pattern is inspected, and a repair material having substantially the same transmittance as the transmittance of the halftone light-shielding layer in the missing defect portion of the resist pattern, and finally a repair material remaining on the photomask Filling and repairing, making it possible to easily correct especially missing defects in the transparent phase shifter without significantly changing the conventional manufacturing process, and produce a high-precision halftone phase shift photomask Can be.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view in a case where the correction method of the present invention is applied during a manufacturing process of a halftone type phase shift reticle.

FIG. 2 is a diagram illustrating the principle of phase shift lithography.

FIG. 3 is a diagram showing a conventional method.

FIG. 4 is a sectional view showing a configuration of a normal phase shift reticle.

FIG. 5 is a cross-sectional view showing a process of manufacturing a halftone phase shift reticle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Light shielding film 3 ... Phase shifter 4 ... Incident light 11 ... Substrate 12 ... Etching stopper layer 13 ... Halftone light shielding layer 14 ... Phase shifter layer 15 ... Resist layer 16 ... Residual defect 17 ... Missing defect 18 ... Laser beam Or focused ion beam 19: focused ion beam 20: carbon-rich gas 21: deposited carbon film 22: etching gas plasma 23: light shielding layer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-172844 (JP, A) JP-A-62-215957 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (3)

(57) [Claims] 1. A resist thin film is formed via a halftone light-shielding layer provided on a phase shifter layer, a pattern is drawn on the resist thin film, and then developed to form a resist pattern. The resist pattern is used as a mask. In the step of manufacturing a phase shift photomask by etching the exposed halftone light-shielding layer and the phase shifter layer in this order, before the etching of the phase shifter layer and after the etching of the halftone light-shielding layer, a defect of the resist pattern is obtained. Is inspected, and a correction material having substantially the same transmittance as the transmittance of the halftone light-shielding layer in the missing defect portion of the resist pattern and finally remaining on the photomask
A method for repairing a phase shift photomask, wherein the repair is performed by filling with a repair material . 2. An etching stopper layer, a phase shifter layer, and a halftone light-shielding layer are formed in this order on a transparent substrate, a resist thin film is formed thereon, and a pattern is drawn on the resist thin film. Develop to form a resist pattern, etch the exposed halftone shading layer using this resist pattern as a mask, and then etch the exposed phase shifter layer using the resist pattern and the halftone shading layer as a mask to phase shift photo In the step of manufacturing a mask, before etching the phase shifter layer and inspecting the resist pattern for defects after the etching of the halftone light-shielding layer, the transmittance of the halftone light-shielding layer in the missing defect portion of the resist pattern and A correction material with almost the same transmittance
A method of repairing a phase shift photomask , which comprises finally burying and repairing with a repair material remaining on the photomask . 3. A halftone light-shielding layer is formed on a transparent substrate, a resist thin film is formed thereon, a pattern is drawn on the resist thin film, and then developed to form a resist pattern. Etching the exposed halftone light-shielding layer with the mask as a mask, and subsequently etching the exposed transparent substrate using the resist pattern and the halftone light-shielding layer as a mask to a predetermined depth to produce a phase shift photomask, a of a front etching inspect defects of the resist pattern after etching of the halftone shading layer, a resist pattern almost identical to the transmittance becomes modified material and the half-tone light shielding layer of the transmittance missing defect portion of Final
A method of repairing a phase shift photomask, wherein the correction is performed by filling the surface with a repair material remaining on the photomask .