JP3250415B2 - Manufacturing method of halftone type phase shift mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern exposure for photofabrication using a phase shift technique in forming an extremely fine pattern as represented by the manufacture of semiconductor integrated circuits such as LSIs and VLSIs. The present invention relates to a method for manufacturing a halftone phase shift mask used as an original.

[0002]

2. Description of the Related Art When forming an extremely fine pattern as represented by the manufacture of semiconductor integrated circuits such as LSIs and VLSIs, general photomasks used as pattern exposure masters are close to each other. Wafers (wafers with a photosensitive film), which have a fine pattern that has been made, and that the light that has passed through the light transmitting portion of the mask is diffracted and interferes with each other, thereby enhancing the light intensity emitted from the pattern boundary. There has been a problem that a fine pattern (a pattern exposed on a photosensitive film on a wafer) which is projected and exposed (projection-transferred) and photosensitive-transferred thereon does not separate and resolve well.

[0003] This phenomenon occurs more remarkably for finer patterns having a pitch equal to or less than the exposure wavelength or in the vicinity of the exposure wavelength. In the exposure method, it was impossible to resolve a fine pattern having a wavelength equal to or less than the wavelength of light.

Therefore, the phase shift of the wavelength (exposure wavelength) of the projection light transmitted through the adjacent pattern is set to a half wavelength, that is, the phase difference between the wavelengths is set to 180 °, thereby making the above-mentioned phase shift possible. A photomask (commonly referred to as a phase shift mask) using a so-called phase shift technique of improving the resolution of a fine pattern has been developed.

In a photomask pattern composed of a light-shielding portion (light-impermeable portion) and an opening (light-transmitting portion), a transparent material is provided on both sides of the opening interposed between the adjacent light-shielding portions. By providing the phase shift portion comprising, when the transmitted light diffracts and interferes with each other, the phase of the exposure wavelength is inverted, so that the light intensity at the boundary portion is weakening intensity contrary to the above case. As a result, the transfer pattern (exposure pattern) is separated and resolved.

Such a phase shift technique was proposed by Levenson et al. Of IBM in 1982, and is disclosed, for example, in Japanese Patent Application Laid-Open No. 58-173744, and in principle, disclosed in Japanese Patent Publication No. Sho 62-50811. Have been.

[0007] In order to maximize the effect of the phase shift technique, it is desirable that the phase shift be 180 ° with respect to each other. For this purpose, a phase shift layer having a film thickness d may be formed so as to satisfy the following equation: d = λ / {2 (n−1)} (1) Here, d is the film thickness of the phase shift portion, λ is the exposure wavelength, and n is the refractive index.

Generally, the phase shift mask includes a Levenson type and a halftone type phase shift mask.

In the Levenson type phase shift mask, a phase shift layer (semi-transmissive layer) is formed on a transparent glass substrate, and a phase shift mask pattern layer (light impermeable layer) is formed on the phase shift layer. A phase shift hole forming portion (transparent region) is provided in the phase shift layer in an opening portion (a portion having no phase shift mask pattern layer) adjacent to the phase shift mask pattern layer. Chromium oxide (CrO) between the glass substrate and the phase shift layer
And a phase shift layer (semi-transmissive layer) and a phase shift hole portion (transparent region).
With this, the amplitude phase of the exposure wave is inverted.

On the other hand, in a halftone type phase shift mask, a phase shift mask pattern layer (light translucent layer) is formed on a transparent glass substrate, and the transparent glass substrate and the phase shift pattern layer A transparent conductive layer of CrO is provided between them.

FIGS. 3A to 3D show a conventional method of manufacturing the halftone type phase shift mask.

First, as shown in FIG.
A transparent conductive layer 2 of CrO (a layer for preventing electrification by electron beam exposure) and a light-transmissive phase shift mask pattern forming layer 3 of chromium oxide (CrO) on a quartz glass or the like, if necessary. Then, an electron beam resist layer 5 is provided on the phase shift mask pattern forming layer 3 of the mask blank, and electron beam writing 6 is performed.

Subsequently, as shown in FIG. 2B, a developing process is performed to pattern the electron beam resist layer 5 to provide a resist pattern 5a.

Next, as shown in FIG. 2C, the semi-transparent phase shift mask pattern forming layer 3 is etched using the resist pattern 5a as an etching mask, and the phase shift mask pattern layer 3a and the opening 7 ( (Light transmitting portion).

Then, FIG. 2D, resist pattern 5
By removing a, a halftone type phase shift mask including the phase shift mask pattern 8 formed by the patterned phase shift mask pattern layer 3a (semi-transmissive layer) is formed.

The halftone type phase shift mask formed as described above is used to perform a predetermined defect inspection such as the absence of the phase shift mask pattern 8 formed on the transparent substrate 1, the presence of pinholes, and the presence of foreign matter. After performing, it is carried out and shipped to the next process.

[0017]

By the way, the above-mentioned pattern defect inspection of the above-mentioned halftone type phase shift mask involves the following steps.
By irradiating the obtained phase shift mask with visible light,
It is an appropriate inspection method to measure the light transmittance at each point of the mask pattern in terms of inspection accuracy and easiness of inspection.

However, the constituent layer of the pattern 8 is composed of the phase shift mask pattern layer 3a having a low light-shielding property and a light translucency, and has a relatively high transmittance.
Therefore, when inspected by a defect inspection machine of an inspection system that measures transmittance using visible light, most of the visible light is transmitted through the pattern 8, and particularly, the presence or absence of a missing or missing pattern, or a pinhole. It is extremely difficult to detect the presence of a defect, and it has been difficult to perform the above-described defect inspection using visible light.

The present invention has been made in view of the above-mentioned problems. The purpose of the present invention is not directly necessary for the process of manufacturing a halftone type phase shift mask. A metal layer (metal thin film) having a certain degree of light-shielding (semi-opaque) required for mask defect inspection is added to a mask blank, and a halftone type phase shift mask is formed using the blank. And performing a defect inspection using the above-mentioned metal thin film in the middle of the final step of the mask production so that a defect inspection using visible light can be performed.

[0020]

According to the present invention, a light-transmissive phase shift mask pattern forming layer 3 is formed on a transparent substrate 1.
And a halftone in which a phase shift mask pattern forming layer 3 and a metal layer 4 made of a material which can be selectively peeled off are laminated on the phase shift mask pattern forming layer 3 and which have incomplete light shielding properties for defect inspection. After applying a resist layer 5 on the metal layer 4 in the mold type phase shift mask blank, the resist layer 5 is exposed and developed into a desired halftone type phase shift mask pattern to form a resist pattern layer 5.
is formed, and then the phase shift mask pattern forming layer 3 and the metal layer 4 other than the resist pattern layer 5a forming region are subjected to an etching process to form the phase shift mask pattern-like phase shift mask pattern layer 3a and the metal pattern. After the formation of the layer 4a, the phase shift mask pattern is inspected for defects, and thereafter, only the metal pattern layer 4a is selectively peeled off from the phase shift mask pattern layer 3a to form the phase shift mask pattern 8. A method for manufacturing a halftone type phase shift mask, characterized in that:

[0021]

Further, the present invention is a method for manufacturing a halftone type phase shift mask in which the metal layer 4 is a metal or a metal oxide or / and a metal nitride in the above halftone type phase shift mask blank.

The present invention also provides a halftone type phase shift mask blank as described above, wherein a transparent conductive layer 2 is laminated between the transparent substrate 1 and the phase shift mask pattern forming layer 3. This is a method for manufacturing a phase shift mask.

[0024]

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a halftone type phase shift mask according to the present invention will be described in detail below with reference to embodiments.

FIG. 1 is a side sectional view of a halftone type phase shift mask blank used in the present invention.
A transparent conductive layer 2 (which may be transparent or semi-transparent) is provided on (a quartz glass or the like) as necessary, and a light-transmissive phase shift mask pattern forming layer 3 and a light-shielding property for defect inspection are provided. And a metal layer 4 of this type are laminated in this order.

The conductive layer 2 is provided as necessary in order to prevent the mask blank from being charged in the subsequent pattern exposure using an electron beam, and is made of a chromium (Cr) -based or silicon (Si) -based. And molybdenum (Mo) -based metal oxides and metal nitrides, such as chromium oxide (CrO) and molybdenum oxide.

The phase shift mask pattern forming layer 3 is made of chromium (Cr) such as chromium oxide or molybdenum oxide.
-Based, silicon (Si) -based, and molybdenum (Mo) -based metal oxides are used.

In the phase shift mask pattern forming layer 3, silicon oxide (SiO ₂ ) can be used as a metal oxide. In this case, the conductive layer 2 also serves as an etching stopper.

The light-shielding metal layer 4 can be made of almost any metal material, such as chromium, molybdenum, tungsten, aluminum, nickel, and molybdenum silicide, and may be any metal except silicon.

The conductive layer 2 is made of a metal (tantalum, tungsten, molybdenum, chromium, magnesia spinel, etc.). Particularly, tantalum has a high etching resistance and serves as an antistatic conductive layer and an etching stop layer. The most suitable) is obtained by reacting oxygen gas or nitrogen gas with, for example, reactive sputtering, ion beam assisted vapor deposition, ion plating, etc. By controlling the reaction amount of nitrogen, the light transmittance, the light reflectance, and the conductivity of the conductive layer 2 are controlled, and the degree of oxidation and nitriding is suppressed to a certain level or less, and the conductive layer 2 becomes conductive without complete insulation. By maintaining the property, an antistatic function for releasing charged electrons during electron beam drawing can be obtained.

The phase shift mask pattern forming layer 3,
Each of the metal layers 4 can be formed by using a known thin film forming method, such as a sputtering method, a vacuum deposition method, or a CVD method, and is not particularly limited thereto.

The thickness of the phase shift mask pattern forming layer 3 is desirably set to a thickness such that the phase inversion of the wavelength of the transmitted light is equivalent to 180 °.
It is desirably within the range of about m.

The thickness of the metal layer 4 for defect inspection is not particularly limited, but is suitably in the range of, for example, 5 nm to 100 nm. The thickness of the metal layer 4 is adjusted by adjusting the thickness of the metal layer 4 so as to obtain an appropriate light shielding property required for defect inspection.

The metal layer 4 is not an opaque light-shielding layer that completely blocks visible light, but has a semi-transmissive property of transmitting visible light to some extent, has an optical density of about 0.6 to 2.0, and has a light transmitting property. The thickness of the metal layer 4 is adjusted to about 5 to 50 nm so that the ratio becomes about 0.3 to 50%, preferably about 0.3 to 20%. By laminating on the phase shift mask pattern forming layer 3, when there is a layer missing, unevenness defect, foreign matter, or the like in the phase shift mask pattern forming layer 3, the optical density difference is emphasized.

Next, a specific method for manufacturing a halftone type phase shift mask will be described in detail with reference to an embodiment shown in FIGS. 2 (a) to 2 (e).

First, as shown in FIG. 2A, a conductive layer 2 is provided on a transparent substrate 1 as necessary, and a light-transmissive phase shift mask pattern forming layer 3 and a defect inspecting layer 3 are provided. The halftone phase shift mask blank according to the first aspect of the present invention, in which the light-shielding metal layers 4 are provided in this order, is prepared.

The transparent substrate 1 is made of an optically transparent material such as synthetic quartz glass generally used for a photomask, and its thickness is not particularly limited.
Usually, one having a size of about 1.5 mm to 7 mm is used.

Next, an electron beam resist layer 5 (positive type) is applied and formed on the metal layer 4 of the halftone type phase shift mask blank and subjected to a pre-bake treatment. Electron beam lithography 6 (positive lithography) is performed under the exposure conditions, and the electron beam resist layer 5 is alkali-soluble photolyzed (or an electron beam resist layer (negative type), not shown, is formed on the metal layer 4 by coating). Then, electron beam drawing (negative drawing) is performed to perform electron beam crosslinking polymerization curing.

In electron beam lithography, the conductive layer 2 functions as a conductive layer for preventing charging in order to prevent a charging phenomenon on the transparent substrate 1.

In the present invention, as the resist material for the electron beam resist layer 5, it is possible to use an ultraviolet-sensitive photoresist in addition to the electron beam resist material. It is appropriate to draw using.

Subsequently, as shown in FIG. 2B, the electron beam resist layer 5 on which the electron beam writing 6 has been performed is patterned by a predetermined developing process, and a mask pattern is appropriately formed on the metal layer 4. An etching resist pattern 5a (non-resist part 5b) is formed.

Next, as shown in FIG. 2C, the metal layer 4 and the phase shift mask pattern forming layer 3 are continuously dry-etched using the etching resist pattern 5a by a dry etching method. Pattern layer 4a
And the phase shift mask pattern layer 3a and the opening 7 are patterned.

Alternatively, the metal layer 4 and the phase shift mask pattern forming layer 3 are wet-etched by wet etching using an etchant such as a cerium ammonium nitrate solution (etchant for chromium metal etching) to form a metal pattern layer 4a. And the phase shift mask pattern layer 3a and the opening 7 are patterned.

Subsequently, as shown in FIG. 2D, by removing the resist pattern 5a, a light-transmissive phase shift mask pattern layer 3a is formed on the transparent substrate 1.
A lamination pattern is formed by the defect inspection metal layer 4a.

Next, a predetermined amount of light beam is applied to the entire surface of the transparent substrate 1 and the laminated pattern by a beam scanning exposure device that emits a light beam of visible light wavelength installed on one surface of the transparent substrate 1. While exposing and scanning, the amount of transmitted light is measured by a light meter (photo sensor) interlocked with the exposing and scanning installed below the transparent substrate 1, and
The transmittance is detected, and the presence / absence of a defect in the laminated pattern due to the light semi-transmissive phase shift mask pattern layer 3a and the metal layer 4a for defect inspection is inspected.

After the defect inspection by visible light is completed, as shown in FIG. 2E, the metal pattern layer 4a can be etched from above the phase shift mask pattern layer 3a, and the metal constituting the metal pattern layer 4a can be etched. A predetermined metal etchant (if the metal pattern layer 4a is chromium metal,
By stripping and removing using an etchant such as a cerium ammonium nitrate solution, a halftone phase shift mask can be obtained.

As described above, according to the method for manufacturing a halftone phase shift mask of the second aspect of the present invention, after the pattern etching process, and before the metal pattern layer 4a is peeled off, the transparent substrate 1 By irradiating the etching pattern forming layer with visible light and measuring the transmittance, the presence or absence of a defect of the phase shift mask pattern 8 after the metal pattern layer 4a is peeled is estimated and inspected.

After completion of the defect inspection, the halftone phase shift mask is obtained by removing the metal pattern layer 4a from the phase shift mask pattern 8.

Hereinafter, specific examples of the present invention will be described.

<Example 1> A cleaned synthetic quartz glass substrate (2.3 mm thick, size 5 inch square) as a transparent substrate.
On the entire surface of the substrate, tantalum nitride (thickness: about 10 to 30 nm) was formed as a conductive layer (antistatic layer) by a sputtering method or a PVD method.

Next, a 370-nm-thick light-transmissive chromium oxide was laminated as a phase shift mask pattern forming layer on the conductive layer by a sputtering method or a PVD method.

Next, a chromium metal having a thickness of 20 nm or less is formed on the phase shift mask pattern forming layer as a metal layer having a semi-transmissive property and an appropriate light shielding property for defect inspection by a sputtering method or PVD. The half-tone type phase shift mask blank of the present invention was formed by lamination.

Subsequently, a positive electron beam resist (trade name: TTCR, manufactured by Toa Gosei Chemical Co., Ltd.) was formed on the metal layer of the halftone type phase shift mask blank to a thickness of about 500 nm by spin coating. The resist was applied and subjected to a predetermined pre-bake treatment to form a resist layer.

Next, using a vector scan type electron beam lithography system, an acceleration voltage of 20 keV was applied to the resist layer.
Dose amount: about 2.5 μC / cm ² , for example, 0.3 μ
A predetermined fine pattern of m pitches is drawn, and a developing process is performed under predetermined conditions using a developing solution composed of a mixture of methyl isobutyl ketone and n-propanol at a weight ratio of 5: 5 to obtain a resist pattern layer. Was. (C; Coulomb)

Subsequently, after the resist pattern layer is subjected to a predetermined post-baking treatment, chromium of a light-shielding metal layer and chromium oxide of a light-transmissive phase shift mask pattern forming layer are used as a pattern etching mask. A wet etching method is used to form a pattern by etching using an etchant (ceric ammonium nitrate) to form a metal pattern layer and a phase shift mask pattern layer on a transparent substrate. The resist pattern layer remaining on the upper surface was peeled off with an organic solvent or an aqueous alkali solution.

Next, the metal pattern layer and the phase shift mask pattern layer are formed by using a beam exposure scanning device for a visible light wavelength and a light meter (photo sensor) interlocking and opposing the beam direction of the beam exposure scanning. The phase shift is performed by performing beam exposure scanning of visible light wavelength from one surface of the transparent substrate on which the pattern is formed, detecting the amount of light transmitted to the other surface opposite to the exposure scanning, and measuring the transmittance. An estimated defect inspection of the mask pattern layer was performed.

After completion of the defect inspection, only the metal pattern layer made of chromium metal for defect inspection on the phase shift mask pattern layer made of chromium oxide is heated as necessary using an etchant (a strong acid such as hydrochloric acid). Etching was performed while removing, removing, washing and drying to obtain a halftone phase shift mask.

<Example 2> A washed synthetic quartz glass substrate (thickness: 2.3 mm, size: 5 inch square) as a transparent substrate
On the entire surface of the substrate, tantalum nitride (thickness: about 10 to 30 nm) was formed as a conductive layer (antistatic layer) by a sputter link method or a PVD method.

Next, on this conductive layer, a 370-nm-thick light-transmissive chromium oxide was laminated as a phase shift mask pattern forming layer by a sputtering method or a PVD method.

Next, a chromium metal having a thickness of 20 nm or less is formed on the phase shift mask pattern forming layer by sputtering or PVD as a metal layer having a semi-transmissive light property and an appropriate light shielding property for defect inspection. Laminated at
A halftone type phase shift mask blank of the present invention was formed.

Subsequently, a positive electron beam resist (trade name: TTCR, manufactured by Toa Gosei Chemical Co., Ltd.) is formed on the metal layer of the halftone type phase shift mask blank to a film thickness of about 500 nm by spin coating. The resist was applied and subjected to a predetermined pre-bake treatment to form a resist layer.

Next, using a vector scan type electron beam lithography system, an acceleration voltage of 20 keV was applied to the resist layer.
Dose amount: about 2.5 μC / cm ² , for example, 0.3 μ
A predetermined fine pattern of m pitches is drawn, and a developing process is performed under predetermined conditions using a developing solution composed of a mixture of methyl isobutyl ketone and n-propanol at a weight ratio of 5: 5 to obtain a resist pattern layer. Was. (C; Coulomb)

Subsequently, using the resist pattern layer as a pattern etching mask,
The chrome of the light-shielding metal layer and the chromium oxide of the light-transmissive phase shift mask pattern forming layer are continuously etched to form a pattern, and the metal pattern layer and the phase shift mask pattern layer are formed on a transparent substrate. After that, the resist pattern layer remaining on the metal pattern layer was peeled off with an organic solvent or an aqueous alkali solution.

The dry etching was performed by using a parallel plate type reactive ion etching apparatus, and a pattern having good anisotropy and linearity and good dimensional reproducibility was obtained. Dry etching conditions are C ₂ F ₆ gas, C
Using HF ₃ gas, gas mixture ratio: C ₂ F ₆ : CHF ₃ =
5: 5, etching applied output; 300 W, gas pressure;
The etching was performed until the chromium oxide, which is the phase shift mask pattern forming layer, reached the surface of the conductive layer (etching stopper layer) with a pressure of 03 Torr and an etching time of 15 minutes.

Next, the metal pattern layer and the phase shift mask pattern layer are formed by using a beam exposure scanning device for a visible light wavelength and a light meter (photosensor) interlocking and opposing the beam direction of the beam exposure scanning. The phase shift is performed by performing beam exposure scanning of visible light wavelength from one surface of the transparent substrate on which the pattern is formed, detecting the amount of light transmitted to the other surface opposite to the exposure scanning, and measuring the transmittance. An estimated defect inspection of the mask pattern layer was performed.

After completion of the defect inspection, only the metal pattern layer made of chromium metal for defect inspection on the phase shift mask pattern layer made of chromium oxide is heated as needed using an etchant (a strong acid such as hydrochloric acid). Etching was performed while removing, removing, washing and drying to obtain a halftone phase shift mask.

Example 3 A cleaned synthetic quartz glass substrate (2.3 mm thick, size 5 inch square) as a transparent substrate
On the entire surface of the substrate, tantalum oxide (thickness: about 30 nm) was formed as a conductive layer (antistatic layer and etching stopper layer) by sputtering or PVD.

Next, on this conductive layer, a 370 nm-thick silicon oxide (SiO ₂ ) was formed by a sputtering method or a PVD method as a light-transmissive phase shift mask pattern forming layer.

Next, chromium is laminated on the phase shift mask pattern forming layer by a sputtering method or a PVD method, and a metal layer (thickness: 20 nm or Light shielding film less than that)
Was formed, washed and dried to form a halftone type phase shift mask blank of the present invention.

Then, a positive electron beam resist (trade name: TTCR, manufactured by Toa Gosei Chemical Co., Ltd.) is spin-coated on the metal layer of the halftone type phase shift mask blank to a film thickness of about 500 nm. It was applied and subjected to a predetermined pre-bake treatment.

Next, using a vector scan type electron beam lithography apparatus, an acceleration voltage: 20 keV, a dose: about 2.5
At μC / cm ² , a predetermined fine pattern having a pitch of, for example, 0.3 μm is drawn, and methyl isobutyl ketone and n-
Using a developing solution consisting of a mixed solution of propanol in a 5: 5 weight ratio, development was performed under predetermined conditions to obtain a resist pattern layer. (C; Coulomb)

Subsequently, using the resist pattern layer as a mask for pattern etching, the chromium metal of the metal layer and the silicon oxide of the phase shift mask pattern forming layer are successively etched by dry etching to form a pattern. Then, a metal pattern layer and a phase shift mask pattern layer were formed on the transparent substrate, and then the resist pattern layer remaining on the metal pattern layer was peeled off with a stripping solution using an organic solvent or an aqueous alkaline solution.

The dry etching was performed using a parallel plate type reactive ion etching apparatus, and a pattern having good anisotropy and linearity and good dimensional reproducibility was obtained. Dry etching conditions are C ₂ F ₆ gas and CH
Using F ₃ gas, gas mixture ratio; C ₂ F ₆ : CHF ₃ =
5: 5, etching applied output; 300 W, gas pressure;
The etching was performed until the chromium oxide, which is the phase shift mask pattern forming layer, reached the surface of the conductive layer (etching stopper layer) with a pressure of 03 Torr and an etching time of 15 minutes.

Next, the metal pattern layer and the phase shift mask pattern layer are formed by using a beam exposure scanning device for a visible light wavelength and a light meter (photo sensor) interlocking and opposing the beam direction of the beam exposure scanning. The phase shift is performed by performing beam exposure scanning of visible light wavelength from one surface of the transparent substrate on which the pattern is formed, detecting the amount of light transmitted to the other surface opposite to the exposure scanning, and measuring the transmittance. An estimated defect inspection of the mask pattern layer was performed.

After the completion of the defect inspection, the metal pattern layer for defect inspection on the phase shift mask pattern layer is peeled off using an etchant (ceric ammonium nitrate solution) for etching the metal constituting the metal pattern layer. Then, washing and drying were performed to obtain a halftone type phase shift mask.

Example 4 A cleaned synthetic quartz glass substrate (2.3 mm thick, size 5 inch square) as a transparent substrate
On the entire surface of the substrate, tantalum oxide (thickness: about 30 nm) was formed as a conductive layer (antistatic layer and etching stopper layer) by sputtering or PVD.

Next, on this conductive layer, a 370 nm-thick silicon oxide (SiO ₂ ) was formed by a sputtering method or a PVD method as a light-transmissive phase shift mask pattern forming layer.

Next, chromium is laminated on the phase shift mask pattern forming layer by a sputtering method or a PVD method to form a metal layer (thickness: 20 nm or Light shielding film less than that)
Was formed, washed and dried to form a halftone type phase shift mask blank of the present invention.

Thereafter, a positive type electron beam resist (trade name: TTCR, manufactured by Toa Gosei Chemical Co., Ltd.) is formed on the metal layer of the halftone type phase shift mask blank to a film thickness of about 500 nm by spin coating. It was applied and subjected to a predetermined pre-bake treatment.

Next, using a vector scan type electron beam lithography system, an accelerating voltage: 20 keV, a dose: about 2.5
At μC / cm ² , a predetermined fine pattern having a pitch of, for example, 0.3 μm is drawn, and methyl isobutyl ketone and n-
Using a developing solution consisting of a mixed solution of propanol in a 5: 5 weight ratio, development was performed under predetermined conditions to obtain a resist pattern layer. (C; Coulomb)

Subsequently, using the resist pattern layer as a mask for pattern etching, the chromium metal of the metal layer is etched by wet etching using an etching solution (ceric ammonium nitrate) to form a metal pattern layer. Then, the resist pattern layer remaining on the metal pattern layer was peeled off with a peeling solution using an organic solvent or an alkaline aqueous solution.

Next, after washing and drying the transparent substrate by a predetermined method, a positive type electron beam resist (trade name: TTCR, manufactured by Toa Gosei Chemical Co., Ltd.) is coated thereon by spin coating. After being applied to a thickness of 500 nm and subjected to a predetermined baking treatment, the above raster scan type electron beam drawing apparatus was used at an acceleration voltage of 20 kV and a dose of 10 μC / cm ² using a vector scan type electron beam drawing apparatus. A predetermined pattern similar to the one exposed is superimposed and drawn,
5 of methyl isobutyl ketone and n-propanol:
Using a developing solution composed of the five mixed solutions, a developing process was performed under predetermined conditions to obtain a resist pattern.

Subsequently, the resist pattern is used as an etching mask pattern by a wet etching method.
Using a buffered hydrofluoric acid solution, the silicon oxide (SiO ₂ ) of the phase shift mask pattern forming layer is pattern-etched,
A phase shift mask pattern layer was formed. Note that the etching was performed until the etching reached the surface of the conductive layer (etching stopper layer).

Subsequently, the resist pattern remaining on the metal pattern layer was removed by stripping with a stripping solution (such as an organic solvent), followed by washing and drying.

Next, the metal pattern layer and the phase shift mask pattern layer are formed by using a beam exposure scanning device for a visible light wavelength and a light meter (photo sensor) interlocking and opposing the beam direction of the beam exposure scanning. The phase shift is performed by performing beam exposure scanning of visible light wavelength from one surface of the transparent substrate on which the pattern is formed, detecting the amount of light transmitted to the other surface opposite to the exposure scanning, and measuring the transmittance. An estimated defect inspection of the mask pattern layer was performed.

After the completion of the defect inspection, the metal pattern layer for defect inspection on the phase shift mask pattern layer is peeled off using an etchant (ceric ammonium nitrate solution) for etching the metal constituting the metal pattern layer. Then, washing and drying were performed to obtain a halftone type phase shift mask.

[0088]

In the halftone phase shift mask blank of the present invention, a metal layer 4 made of a metal such as chromium having imperfect light shielding (semi-opaque) is formed on the phase shift mask pattern forming layer 3. Therefore, in the middle of the mask manufacturing final step after the completion of pattern etching when manufacturing a halftone type phase shift mask using the blank, through the pattern-etched incomplete light-shielding metal layer 4a, By irradiating visible light to the pattern-etched lower semi-transmissive phase shift mask pattern layer 3a, the optical density difference is emphasized by the incomplete metal layer 4a, and visible light is used. The presence or absence of a defect due to transmitted light can be estimated and inspected.

According to the method of manufacturing a halftone type phase shift mask using the above mask blank of the present invention,
After completion of the defect inspection in the process of manufacturing a halftone phase shift mask using this blank, the metal layer 4a is removed from the phase shift mask pattern layer 3a to obtain a halftone phase shift mask. be able to.

Further, the halftone type phase shift mask blank of the present invention has a phase shift mask pattern forming layer 3
Metal oxide such as chromium oxide, and a metal such as chromium as the metal layer 4 for defect inspection.
When removing the metal layer 4a from above, by using an etchant that satisfactorily etches only the metal excluding metal oxides and metal nitrides, it is possible to easily remove only the metal layer 4a from the pattern layer 3a. .

In the halftone phase shift mask blank of the present invention, the conductive layer 2 is provided on the transparent substrate 1 so that the conductive layer 2 has a sufficient charge for preventing the blank from being charged by electron beam exposure. Shows conductive performance.

Further, in the halftone type phase shift mask blank of the present invention, the conductive layer 2 is provided on a transparent substrate 1, and a silicon oxide (SiO _{2) is} formed as a phase shift mask pattern forming layer 3 on the conductive layer _2. ), The silicon oxide is subjected to pattern etching by a wet etching method using a hydrofluoric acid solution or pattern etching by a dry etching method using a C ₂ F ₆ gas and a CHF ₃ gas. Therefore, the conductive layer 2 functions as an etching stopper layer in such a silicon oxide etching step.

[0093]

The halftone phase shift mask blank of the present invention has a certain degree of light shielding (semi-opacity) required for defect inspection of a halftone phase shift mask manufactured using the blank. In the method for manufacturing a halftone phase shift mask using the mask blank, a metal layer is added. In the method for manufacturing a halftone phase shift mask using the blank, a defect inspection is performed after the mask pattern etching is completed. By irradiating the mask pattern with visible light through a metal layer having a certain light-shielding property, it is possible to emphasize and detect the difference in the amount of light transmitted through the mask pattern,
This has the effect of enabling defect inspection using visible light.

[Brief description of the drawings]

FIG. 1 is a side sectional view illustrating a halftone type phase shift mask blank of the first invention.

FIGS. 2A to 2E are side sectional views illustrating an embodiment of a method for manufacturing a halftone type phase shift mask using the halftone type phase shift mask blank of the first invention.

FIGS. 3A to 3D are side sectional views illustrating a method for manufacturing a halftone type phase shift mask using a conventional halftone type phase shift mask blank.

[Description of Signs] 1 ... Transparent substrate 2 ... Conductive layer 3 ... Phase shift mask pattern forming layer 3a ... Phase shift mask pattern layer 4 ... Metal layer 4a
... metal pattern layer 5 ... electron beam resist layer 5a ... resist pattern 5b
... non-resist part 6 ... electron beam drawing 7 ... opening 8 ... mask pattern

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-342205 (JP, A) JP-A-5-127361 (JP, A) JP-A-6-175346 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (3)

(57) [Claims] 1. A light-transmissive phase shift on a transparent substrate 1.
Mask pattern forming layer 3 and phase shift mask pattern
Has an incomplete light-shielding property for defect inspection on the
Selective peeling and removal from the phase shift mask pattern forming layer 3
Halftone type with a metal layer 4 made of a possible substance laminated
After applying a resist layer 5 on the metal layer 4 in the phase shift mask blank , the resist layer 5 is exposed and developed into a desired halftone type phase shift mask pattern to form a resist pattern layer 5a. After the phase shift mask pattern forming layer 3 and the metal layer 4 other than the resist pattern layer 5a forming region are etched to form the phase shift mask pattern-shaped phase shift mask pattern layer 3a and the metal pattern layer 4a, Phase shift
A half-tone type wherein a phase shift mask pattern 8 is formed by inspecting the presence or absence of a defect in the shift mask pattern , and thereafter selectively removing only the metal pattern layer 4a from the phase shift mask pattern layer 3a. A method for manufacturing a phase shift mask. 2. The method for manufacturing a halftone phase shift mask according to claim 1, wherein said metal layer 4 is made of metal, metal oxide or / and metal nitride. 3. The halftone phase according to claim 1, wherein a transparent conductive layer for preventing static electricity is laminated between said transparent substrate and said phase shift mask pattern forming layer. Shift mask manufacturing method.