JPH06301195A - Correcting method for phase shift photo-mask - Google Patents

Abstract

PURPOSE:To inspect and correct the defect of a phase shifter pattern in the resist pattern state during the phase shift photo-mask machining process. CONSTITUTION:A remaining defect 16 and a missing defect 17 existing in the resist pattern state when the portion of a half-tone shading layer 13 exposed from the opening section of the resist pattern is etched to form a shading pattern after the patterning of a resist layer 15 are inspected in the manufacturing process. The remaining defect 16 is subliminated and removed together with the resist layer 15 and the shading layer 13 by a laser beam or a convergent ion beam 18, and the missing defect 17 is stacked and buried with a carbon film 21 by the radiation of a convergent ion beam 19 in the carbon-rich atmosphere 20 such as pyrene. A phase shifter layer 14 is etched by etching gas plasma 22 after the resist pattern is etched, then the remaining resist is peeled, and a half-tone phase shift reticle is completed.

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 LSI and VLSI, and a method for manufacturing the reticle, and in particular, it is used for forming a fine pattern with high accuracy. The present invention relates to a method for repairing a photomask having a phase shift layer.

[0002]

2. Description of the Related Art In semiconductor integrated circuits such as IC, LSI, and VLSI, a resist is applied on a substrate to be processed such as a silicon wafer, a desired pattern is exposed by a stepper, and then development, etching, doping, CVD are performed. It is manufactured by repeating a so-called lithographic process for performing the above.

Photomasks called reticles used in such lithography processes tend to be required to have higher precision as the performance and integration of semiconductor integrated circuits become higher. DRA which is LSI
Taking M as an example, the dimensional deviation of a 5 × reticle for a 1 Mbit DRAM, that is, a reticle having a size 5 × that of a pattern to be exposed, is ± 3σ (σ is a standard deviation) on average. Accuracy of 0.15 μm is required. Similarly, a 5 × reticle for a 4M bit DRAM has a dimensional accuracy of 0.1 to 0.15 μm, and a 5 × reticle for a 16M bit DRAM has a dimensional accuracy of 0.05 to 0.1 μm. The dimensional accuracy is 0.
Dimensional accuracy of 03 to 0.07 μm is required.

Further, the line width of the device pattern formed using these reticles is 1 Mbit DRAM.
1.2 μm, 0.8 μm for 4M bit DRAM, 1
0.5 μm for 6M bit DRAM, 64M bit DR
In AM, further miniaturization of 0.35 μm is required, and various exposure methods are being researched in order to meet such requirements.

However, in the case of a next-generation device pattern of, for example, a 64 Mbit DRAM class, the conventional stepper exposure method using a reticle has a resolution limit of a resist pattern. A reticle of a new concept called a phase shift reticle has been proposed as disclosed in Japanese Patent Publication No. 58-173744, Japanese Patent Publication No. 62-59296, and the like. 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.

Phase shift lithography will be briefly described with reference to the drawings. 2 is a diagram showing the principle of the phase shift method,
FIG. 3 is a diagram showing a conventional method, and is shown in FIGS.
(A) is a cross-sectional view of the reticle, FIG. 2 (b) and FIG. 3 (b).
Is the amplitude of light on the reticle, FIGS. 2 (c) and 3 (c) are the amplitudes of light on the wafer, and FIGS. 2 (d) and 3 (d) are the light intensities on the wafer, respectively. Substrate 2, light-shielding film, 3 phase shifter, and 4 incident light.

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

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

Therefore, a manufacturing process of a halftone type phase shift reticle, which has a simple structure and seems to be most practical, will be described as an example with reference to the drawings.

FIG. 5 is a sectional view showing a manufacturing process of a halftone type phase shift reticle, in which 31 is a substrate,
32 is an etching stopper layer, 33 is a halftone light shielding layer made of chromium or the like, 34 is a phase shifter layer, 35 is a resist layer, 36 is ionizing radiation such as a laser beam or an electron beam, 37 is an exposed portion, 38 is a light shielding layer 33. , 39 is an etching gas plasma for the phase shifter layer 34, and 40 is an oxygen plasma.

First, as shown in FIG. 5A, the substrate 31
The etching stopper layer 32 and the phase shift layer 3 are formed on the upper surface.
4. A half-tone type phase shift photomask substrate is formed by stacking the light-shielding layer 33 in this order, and a resist is uniformly applied on the light-shielding layer 33 by a conventional method such as spin coating, followed by heat-drying treatment to obtain a thickness. A resist layer 35 having a thickness of about 0.1 to 2.0 μm is formed. The heat-drying treatment is usually performed at 80 to 200 ° C., 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 device such as an electron beam drawing device according to a conventional method. Subsequently, it 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 heat-drying treatment and descum treatment, if necessary, as shown in FIG. 3C, the portion of the light-shielding layer 33 exposed from the opening of the resist pattern is dried by etching gas plasma 38. Etching is performed to form a light shielding pattern ((d) in the figure). It should be apparent to those skilled in the art that the light shielding pattern may be formed by wet etching instead of dry etching using the etching gas plasma 38.

Subsequently, as shown in FIG. 3D, the phase shifter layer 34 portion exposed from the openings of the resist pattern and the light shielding pattern is dry-etched by the etching gas plasma 39 to form a phase shifter pattern (see FIG. Figure (e)). It should be apparent to those skilled in the art that the phase shifter pattern may be formed 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, the halftone type phase shift reticle having the phase shifter 34 as shown in FIG.

In the example of the above manufacturing method, the structure in which the halftone light shielding layer is formed on the phase shifter layer has been described, but in the reverse structure in which the phase shifter layer is formed on the halftone light shielding layer. Clearly, the same is true.

[0017]

However, in the conventional method of manufacturing a phase shift reticle as exemplified above, although the manufacturing process of the phase shift photomask is relatively easy, it is not possible to correct defects in the completed mask. There is the problem of being 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 Since the shifter is transparent, its residual defects and missing defects are very difficult to repair, and solving this problem was one of the major missions of researchers.

The present invention has been made in view of such a situation, and an object thereof is to inspect and correct defects of the phase shifter pattern in the state of the resist pattern in the process of processing the phase shift photomask, and An object of the present invention is to provide a more practical method of correcting a phase shift photomask capable of manufacturing a highly accurate phase shift reticle having no defect in the phase shifter pattern after etching the shifter.

[0020]

In view of the above problems, the present invention develops a method for stably manufacturing a highly accurate phase shift photomask without significantly 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 repaired in the state of the resist pattern which serves as a direct or indirect mask for etching the phase shifter layer, and A method for manufacturing a reticle having a phase shift layer, which comprises etching the phase shifter layer in a defective 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 repairing defects at the resist pattern stage in the manufacturing process of a halftone type phase shift reticle. In the figure, 11 is a transparent glass substrate such as quartz glass, 12 is an etching stopper layer, 13 is a metal such as chromium, molybdenum, silicon, aluminum, titanium, etc., for example, a halftone light shielding layer having a transmittance of excimer laser light of 1 to 30%, and 14 is an SOG.
(Spin-on-glass), phase shifter layer made of vapor-deposited SiO _2, etc., 15 is resist layer, 16 is residual defect, 1
Reference numeral 7 denotes a missing defect, 18 a laser beam or a focused ion beam, 19 a focused ion beam, 20 a carbon-rich gas, 21 a deposited carbon film, and 22 an etching gas plasma.

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

Next, as shown in FIG. 3C, the phase shifter layer 14 is etched by the etching gas plasma 22 with the resist pattern thus corrected, and the remaining resist is peeled off. Thus, a halftone type phase shift photomask as shown in FIG.

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

In the above, 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, and the substrate 1
Similarly, when etching a predetermined depth from the surface of No. 1 to form a phase shifter layer (see, for example, JP-A-3-172845), it is possible to inspect and correct the resist pattern of the etching mask in the same manner.

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. Some place patterns. In this case, a halftone light shielding layer and a phase shifter layer are formed in this order on a glass substrate, then a resist layer is formed thereon, and the resist layer is patterned by ionizing radiation such as an electron beam exposure device. Drawing is performed, the resist layer after pattern drawing is developed to form a resist pattern, the exposed phase shifter layer is etched using this resist pattern as a mask, and subsequently, this resist pattern and the phase shifter layer are exposed as a mask It is manufactured by etching the halftone light shielding layer and removing the remaining resist. In such a halftone type phase shift reticle, the defect is inspected at the stage of forming the resist pattern and is corrected in the same manner as described above.

Furthermore, as one of the halftone type phase shift reticles, the applicant of the present invention has a structure in which a semitransparent thin film layer also serving as a halftone light shielding layer and a phase shifter layer is provided on a glass substrate and patterned. 3-28783
Proposed in No. 2. In this reticle, a semitransparent thin film layer having a phase difference of 180 ° is formed on a glass substrate, and then a resist layer is formed thereon, and a pattern is drawn on this resist layer by ionizing radiation such as an electron beam exposure device. The resist layer after pattern drawing is developed to form a resist pattern, the exposed semitransparent thin film layer is etched by using this resist pattern as a mask, and the remaining resist is removed to manufacture. Also in such a halftone type phase shift reticle, the defect is inspected at the stage of forming the resist pattern and is corrected in the same manner as above.

As described above, before actually etching the phase shifter layer for residual defects and missing defects in the phase shifter pattern of the halftone type phase shift reticle, the defects are inspected in the state of the resist pattern as the etching mask. Although it was corrected, the residual defects and the missing defects of the phase shifter pattern of the normal phase shift reticle as shown in FIGS. 4A and 4B can be similarly corrected.

That is, 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 in this order on a glass substrate 11. , A first resist layer is formed on the first resist layer, a pattern is drawn on the first resist layer by ionizing radiation from an electron beam exposure device, etc., and the first resist layer after pattern drawing is developed to form a first resist pattern. Then, the exposed light shielding layer 23 is etched using the first resist pattern as a mask to form a light shielding pattern, and 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, the second resist layer after pattern drawing is developed to form a second resist pattern, and the exposed phase is obtained using this second resist pattern as a mask. Shifter layer 14
Is manufactured by etching and removing the remaining resist. Also in this phase shifter underlaying type phase shift reticle, the defect can be inspected at the stage of forming the second resist pattern and can be corrected in the same manner as described above.

Further, 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 in this order on a glass substrate 11, and then a first layer is formed thereon. A resist layer is formed, a pattern is drawn on this first resist layer with ionizing radiation from an electron beam exposure device, etc., and the first resist layer after pattern drawing is developed to form a first resist pattern. The exposed light-shielding layer 23 is etched by using the pattern as a mask to form a light-shielding pattern, and subsequently, the phase shifter layer 14 and the second resist layer are formed in this order on the light-shielding pattern, and the electron beam is applied to the second resist layer. A pattern is drawn with ionizing radiation from an exposure device, etc., 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 type phase shift reticle, the defect can be inspected at the stage of forming the second resist pattern and corrected in the same manner as described above.

Further, in the phase shift reticle under the phase shifter, it is also possible to perform this action in the manifestation portion of the glass substrate without providing the phase shifter layer under the light shielding layer (for example, Japanese Patent Laid-Open No. 3-30083). 172845). In this case, the light-shielding layer 23 is formed on the glass substrate, then the first resist layer is formed thereon, and the first resist layer is subjected to pattern drawing by ionizing radiation from an electron beam exposure device or the like to form a pattern. The first resist layer after drawing is developed to form a first resist pattern, the exposed light-shielding layer is etched by using this first resist pattern as a mask to form a light-shielding pattern, and then a first resist pattern is formed on the light-shielding pattern. A second resist layer is formed, a pattern is drawn on the second resist layer by ionizing radiation such as an electron beam exposure device, and the second resist layer after pattern drawing is developed to form a second resist pattern. It is manufactured by etching a predetermined depth portion from the surface of the glass substrate exposed using the pattern as a mask and removing the remaining resist. Also in this phase shifter lower type phase shift reticle, when the second resist pattern is formed,
The defect can be inspected and repaired as above.

In order to correct the missing defect of the phase shifter pattern of the halftone type phase shift reticle,
Since the carbon that fills the missing portion of the etching resist pattern finally remains on the reticle, it is desirable to control the thickness thereof to a thickness that is approximately 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 lowered to some extent. Furthermore, as a material for filling the missing defects in the resist pattern that serves as a mask for etching the phase shifter layer, it is not limited to carbon, it has etching resistance, and even if it remains on the phase shifter pattern, transmittance and phase difference Other materials can be used as long as they are benign material and thickness.

As is apparent from the above description, the method of correcting a phase shift photomask according to the present invention is a resist thin film directly on the phase shifter layer or via a light shielding layer or a halftone light shielding layer provided thereon. To form a pattern on the resist thin film, and then develop to form a resist pattern, and using this resist pattern as a mask, the exposed phase shifter layer is provided directly or on a light-shielding layer or a halftone light-shielding layer and In the step of manufacturing a phase shift photomask by etching the phase shifter layers in this order, a defect of the resist pattern is inspected and repaired before the etching of the phase shifter layer.

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, then a resist thin film is formed thereon, and this resist thin film is formed. Draw a pattern,
After that, a resist pattern is formed by developing, and the exposed halftone light-shielding layer is etched using this resist pattern as a mask, and then the exposed phase shifter layer is etched using this resist pattern and the halftone light-shielding layer as a mask to shift the phase. In the process of manufacturing a photomask, the repair method is characterized by inspecting and repairing defects in the resist pattern before etching the phase shifter layer and before or after etching the halftone light shielding layer.

Further, an etching stopper layer, a halftone light-shielding layer and a phase shifter layer are formed in this order on a transparent substrate, a resist thin film is subsequently formed thereon, and a pattern is drawn on this resist thin film, after which Develop to form a resist pattern, use the resist pattern as a mask to etch the exposed phase shifter layer, and then use the resist pattern and the phase shifter layer as a mask to etch the exposed halftone light-shielding layer to obtain a phase shift photomask. In the step of manufacturing (1), before the etching of the phase shifter layer, the defect of the resist pattern is inspected and repaired.

Further, a halftone light-shielding layer is formed on a transparent substrate, a resist thin film is subsequently formed thereon, a pattern is drawn on the resist thin film, and then development is performed to form a resist pattern. In the step of manufacturing the phase shift photomask by etching the exposed halftone light-shielding layer using the mask as a mask, and then etching the exposed transparent substrate using the resist pattern and the halftone light-shielding layer as a mask to a predetermined depth. Before the etching of the halftone light-shielding layer or after the etching of the halftone light-shielding layer, the defect of the resist pattern is inspected and repaired.

Further, a semitransparent thin film layer having a phase difference is formed on a transparent substrate, a resist thin film is subsequently formed thereon, a pattern is drawn on the resist thin film, and then developed to form a resist pattern. In the step of manufacturing the phase shift photomask by etching the exposed semitransparent thin film layer using this resist pattern as a mask, before the etching of the semitransparent thin film layer, it is possible to inspect and repair defects in the resist pattern. This is a characteristic correction method.

Further, an etching stopper layer, a phase shifter layer and a light shielding layer are formed in this order on a transparent substrate, then a first resist thin film is formed thereon, and a pattern is drawn on this first resist thin film. After that, development is performed to form a first resist pattern, the exposed light shielding layer is etched using the first resist pattern as a mask to form a light shielding pattern, and then a second resist thin film is formed on the light shielding pattern. In the step of producing a phase shift photomask by performing pattern drawing on the second resist thin film, then developing to form a second resist pattern, and etching the exposed phase shifter layer using this second resist pattern as a mask, Before the etching of the phase shifter layer, the defect of the second resist pattern is inspected and repaired. It is a modified method of.

Further, an etching stopper layer and a light shielding layer are formed in this order on a transparent substrate, a first resist thin film is subsequently formed on this, a pattern is drawn on this first resist thin film, and then developed. A first resist pattern is formed, the exposed light-shielding layer is etched using the first resist pattern as a mask to form a light-shielding pattern, and then a phase shifter layer and a second resist thin film are formed in this order on the light-shielding pattern. Then, a pattern is drawn on the second resist thin film, and then developed to form a second resist pattern, and the exposed phase shifter layer is etched using the second resist pattern as a mask to manufacture a phase shift photomask. In, before the etching of the phase shifter layer, the defects of the second resist pattern are inspected and repaired. A correction method characterized by and.

Further, a light-shielding layer is formed on a transparent substrate, a first resist thin film is subsequently formed thereon, a pattern is drawn on the first resist thin film, and then development is performed to form a first resist pattern. The exposed light-shielding layer is etched by using the first resist pattern as a mask to form a light-shielding pattern, a second resist thin film is subsequently formed on the light-shielding pattern, and a pattern is drawn on the second resist thin film. Develop to form a second resist pattern,
In the step of manufacturing the phase shift photomask by etching the exposed transparent substrate to a predetermined depth using the second resist pattern as a mask, the defects of the second resist pattern are inspected and corrected before the transparent substrate is etched. It is a correction method characterized by the above.

[0042]

In the present invention, in the process of manufacturing the phase shift photomask, the defect of the resist pattern used as the etching mask is inspected and corrected before the etching of the phase shifter layer, so that the transparent phase shifter remains. Defects and missing defects can be easily corrected without significantly changing the conventional manufacturing process, and a highly accurate phase shift photomask can be manufactured.

[0043]

EXAMPLES The method for correcting the phase shift photomask of the present invention will be described in detail below with reference to some examples.

Example 1 SOG was formed on a mask substrate formed by forming an etching stopper layer made 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. It is applied by spin coating, heat-dried, and has a thickness of 0.38 μm.
A phase shifter layer made of SOG of was formed. On this, a tungsten silicide thin film having a transmittance of about 15% was sputtered in the i-line region of a mercury lamp to fabricate a halftone type phase shifter photomask substrate having a three-layer structure. Then, electron beam resist CMS-EX is formed on this substrate.
(S) is applied by spin coating method and 120 ° C
And heat-treated 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 accelerating voltage was 10 kV and the exposure amount was ² μC / cm ² .

Then, the resist pattern was formed by developing with an organic solvent containing ethyl cellosolve and isoamyl acetate as main components and rinsing with isopropyl alcohol.

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 treated with a gas containing fluorine as a main component. Dry-etched.

After visually inspecting the pattern formed of the light-shielding layer and the resist thus formed with a normal photomask defect inspection apparatus, the detected defects were 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 containing a fluorine-based gas as a main component.

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

The halftone phase shift photomask thus completed was of a high quality in which no defect could be detected even when a visual inspection was carried out by a defect inspection apparatus.

(Example 2) SiO was formed on a mask substrate formed by forming an etching stopper layer made of a tin oxide thin film having a thickness of about 100 nm on a 5 inch square ultra-high purity synthetic quartz glass substrate which was optically polished. _{The two} films were applied by the CVD method to form a phase shifter layer made of a SiO ₂ film having a thickness of 0.35 μm. On this, a chromium thin film having a transmittance of about 15% was sputtered in the i-line region of a mercury lamp to fabricate a halftone type phase shifter photomask substrate having a three-layer structure. Then, electron beam resist ZE is formed on this substrate.
P-520 (manufactured by Nippon Zeon Co., Ltd.) was applied by a spin coating method and heat-treated 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 this substrate by an electron beam exposure apparatus according to a conventional method. At this time, the accelerating voltage was 10 kV and the exposure amount was 10 μC / cm ² .

Subsequently, the resist pattern was developed by developing with a dedicated developing solution and rinsing with a dedicated rinsing solution.

Next, after descumming if necessary,
The halftone chrome layer exposed from the opening of the resist pattern was dry-etched using a gas containing a fluorine-based gas as a main component.

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

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

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

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

(Example 3) A half-tone phase was obtained by sputtering a chromium thin film having a transmittance of about 15% in the i-line region of a mercury lamp on an optically polished 5-inch square ultra-high purity synthetic quartz glass substrate. A shift photomask substrate was produced.
Then, an electron beam resist ZEP-520 was formed on this substrate.
(Nippon Zeon Co., Ltd.) was applied by a spin coating method and heat-treated at 180 ° C. for 30 minutes to give 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 accelerating voltage was 10 kV and the exposure amount was 10 μC / cm ² .

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

Then, after descumming if necessary,
The chromium layer exposed from the opening of the resist pattern was dry-etched using a gas containing a fluorine-based gas as a main component.

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

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

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

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

Comparative Example SOG was spun on a mask substrate formed by forming an etching stopper layer made of an alumina thin film having a thickness of about 100 nm on a 5 inch square ultra-high purity synthetic quartz glass substrate which was optically polished. It was applied by coating and heat-dried to form a phase shifter layer of SOG having a thickness of 0.38 μm. On top of this,
A half-tone 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.
Then, electron beam resist CMS-EX is formed on this substrate.
(S) is applied by spin coating method and 120 ° C
And heat-treated 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 accelerating voltage was 10 kV and the exposure amount was ² μC / cm ² .

Subsequently, the resist pattern was formed by developing with an organic solvent containing ethyl cellosolve and isoamyl acetate as main components and rinsing with isopropyl alcohol.

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 was treated with a gas containing fluorine as a main component. Dry-etched.

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

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

After the appearance of the phase shift photomask thus manufactured was inspected by a photomask defect inspection apparatus, the detected defects were attempted to be corrected by using a laser repair defect removal apparatus and an FIB defect correction apparatus. It took a long time to remove the defect defect of No. 1 even if FIB etching was performed, 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, the phase shift photomask is used as an etching mask before the etching of the phase shifter layer in the process of manufacturing the phase shift photomask. Since the defect of the resist pattern to be inspected and repaired, the residual defect and the missing defect of the transparent phase shifter can be easily repaired without significantly changing the conventional manufacturing process, and the highly accurate phase shift can be performed. A photomask can be manufactured.

[Brief description of drawings]

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

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

FIG. 3 is a diagram showing a conventional method.

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Shading film 3 ... Phase shifter 4 ... Incident light 11 ... Substrate 12 ... Etching stopper layer 13 ... Halftone shading layer 14 ... Phase shifter layer 15 ... Resist layer 16 ... Residual defect 17 ... Missing defect 18 ... Laser beam Alternatively, focused ion beam 19 ... Focused ion beam 20 ... Carbon rich gas 21 ... Deposited carbon film 22 ... Etching gas plasma 23 ... Light shielding layer

Claims (8)

[Claims] 1. A resist thin film is formed directly on the phase shifter layer or via a light shielding layer or a halftone light shielding layer provided thereon, and a pattern is drawn on the resist thin film, and then developed to develop a resist pattern. In the step of manufacturing a phase shift photomask by directly etching the exposed phase shifter layer using this resist pattern as a mask or a light-shielding layer or a halftone light-shielding layer and a phase shifter layer provided thereon, A method for repairing a phase shift photomask, which comprises inspecting and repairing defects in the resist pattern before etching the phase shifter layer. 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 subsequently formed thereon, and a pattern is drawn on the resist thin film. After development, a resist pattern is formed, the exposed halftone light-shielding layer is etched using this resist pattern as a mask, and then the exposed phase shifter layer is etched using this resist pattern and the halftone light-shielding layer as masks to perform a phase shift photo. A method of repairing a phase shift photomask, characterized in that in the step of manufacturing a mask, a defect in the resist pattern is inspected and repaired before etching the phase shifter layer and before or after etching the halftone light shielding layer. . 3. An etching stopper layer, a halftone light shielding layer and a phase shifter layer are formed in this order on a transparent substrate, a resist thin film is subsequently formed thereon, and a pattern is drawn on this resist thin film, Develop to form a resist pattern, use the resist pattern as a mask to etch the exposed phase shifter layer, and then use the resist pattern and the phase shifter layer as a mask to etch the exposed halftone light-shielding layer to obtain a phase shift photomask. A method for repairing a phase shift photomask, comprising: inspecting and repairing a defect in the resist pattern before etching the phase shifter layer in the step of manufacturing. 4. A halftone light-shielding layer is formed on a transparent substrate, a resist thin film is subsequently formed thereon, a pattern is drawn on this resist thin film, and then developed to form a resist pattern. In the step of manufacturing the phase shift photomask by etching the exposed halftone light-shielding layer using the mask as a mask, and then etching the exposed transparent substrate using the resist pattern and the halftone light-shielding layer as a mask to a predetermined depth. Prior to the etching and before or after the halftone light-shielding layer is etched, the defect of the resist pattern is inspected and repaired. 5. A semitransparent thin film layer having a phase difference is formed on a transparent substrate, a resist thin film is subsequently formed thereon, a pattern is drawn on the resist thin film, and then development is performed to form a resist pattern. In the step of manufacturing the phase shift photomask by etching the exposed semitransparent thin film layer using this resist pattern as a mask, before the etching of the semitransparent thin film layer, it is possible to inspect and repair defects in the resist pattern. A method for correcting a characteristic phase shift photomask. 6. An etching stopper layer, a phase shifter layer, and a light shielding layer are formed in this order on a transparent substrate, and then a first resist thin film is formed thereon, and a pattern is drawn on the first resist thin film. After that, development is performed to form a first resist pattern, the exposed light shielding layer is etched using the first resist pattern as a mask to form a light shielding pattern, and then a second resist thin film is formed on the light shielding pattern. Pattern drawing on the second resist thin film,
Then, in the step of developing to form a second resist pattern, and etching the exposed phase shifter layer using the second resist pattern as a mask to manufacture a phase shift photomask, before the etching of the phase shifter layer, 2. A method for repairing a phase shift photomask, which comprises inspecting and repairing defects in a resist pattern. 7. An etching stopper layer and a light-shielding layer are formed in this order on a transparent substrate, a first resist thin film is subsequently formed thereon, a pattern is drawn on the first resist thin film, and then developed. Forming a first resist pattern,
The exposed light-shielding layer is etched by using the first resist pattern as a mask to form a light-shielding pattern, and then a phase shifter layer and a second resist thin film are formed in this order on the light-shielding pattern, and the second resist thin film is formed on the second resist thin film. In the step of manufacturing a phase shift photomask by performing pattern drawing and then developing to form a second resist pattern, and etching the exposed phase shifter layer using the second resist pattern as a mask, etching of the phase shifter layer is performed. A method for repairing a phase shift photomask, which comprises inspecting and repairing a defect in the second resist pattern. 8. A light-shielding layer is formed on a transparent substrate, a first resist thin film is subsequently formed thereon, a pattern is drawn on the first resist thin film, and then development is performed to form a first resist pattern. The exposed light-shielding layer is etched by using the first resist pattern as a mask to form a light-shielding pattern, a second resist thin film is subsequently formed on the light-shielding pattern, and a pattern is drawn on the second resist thin film. In a step of developing a second resist pattern and etching the exposed transparent substrate to a predetermined depth by using the second resist pattern as a mask to manufacture a phase shift photomask, the first substrate is etched before the etching of the transparent substrate. 2. A method for repairing a phase shift photomask, which comprises inspecting and repairing defects in a resist pattern.