WO2014103867A1

WO2014103867A1 - Phase shift mask and method for producing same

Info

Publication number: WO2014103867A1
Application number: PCT/JP2013/084059
Authority: WO
Inventors: 聖望月; 中村　大介; 影山　景弘
Original assignee: アルバック成膜株式会社
Priority date: 2012-12-27
Filing date: 2013-12-19
Publication date: 2014-07-03
Also published as: KR20150102004A; CN104737072B; TW201435476A; JP5982013B2; KR102168151B1; JPWO2014103867A1; CN104737072A; TWI592738B

Abstract

A method for producing a phase shift mask includes the step of sputtering a target made of a chromium-based material in an atmosphere of a mixture gas containing 10.4 % or less of an acidic gas.

Description

Phase shift mask and manufacturing method thereof

The present invention relates to a phase shift mask capable of forming a fine and highly accurate exposure pattern and a manufacturing method thereof, and more particularly to a technique suitable for use in manufacturing a flat panel display.
This application claims priority based on Japanese Patent Application No. 2012-285845 filed in Japan on December 27, 2012, the contents of which are incorporated herein by reference.

In a manufacturing process of a semiconductor device or a flat panel display (FPD), a phase shift mask is used to expose and transfer a fine pattern onto a resist film formed on a substrate made of silicon, glass, or the like.
In the FPD, the line width size has been further refined by improving the patterning accuracy, and the image quality has been greatly improved. As the line width accuracy of the photomask and the line width accuracy of the substrate on the transfer side become finer, the gap between the photomask and the substrate during exposure becomes smaller. Since the glass substrate used for the flat panel has a large size exceeding 300 mm, the waviness or surface roughness of the glass substrate becomes a large value, and it is easily affected by the depth of focus.

Since the glass substrate is a large size, the FPD exposure uses the combined wavelength of g-line (436 nm), h-line (405 nm), and i-line (365 nm), and the same-size proxy proximity exposure method is used. (For example, refer to Patent Document 1).

On the other hand, patterning with a single wavelength of ArF (193 nm) is performed on semiconductors, and a halftone phase shift mask is used as a technique for achieving further miniaturization (see, for example, Patent Document 2). According to this method, when the phase is 180 ° at 193 nm, it is possible to set the location where the light intensity becomes zero and improve the patterning accuracy. Further, since there is a portion where the light intensity becomes zero, it is possible to set a large depth of focus, and it is possible to ease exposure conditions or improve patterning yield.

Japanese Unexamined Patent Publication No. 2007-271720 (paragraph [0031]) Japanese Unexamined Patent Publication No. 2006-78953 (paragraphs [0002] and [0005])

With the recent miniaturization of FPD wiring patterns, there is an increasing demand for fine line width accuracy in photomasks used in FPD manufacturing. However, it has become very difficult to deal with only the exposure conditions and development conditions for photomask miniaturization, and new techniques for achieving further miniaturization have been demanded.
In particular, when the composite wavelength of g-line, h-line, and i-line is used as described above, the transmittance in the mask for each wavelength is different, so when performing an exposure process for a large area like an FPD. However, in high-definition patterning, a problem due to light shielding or phase shift occurs, resulting in a problem that high-definition cannot be handled.
In addition, when trying to handle a high-definition process that is limited to a specific wavelength in order to support high-definition, light in other wavelength ranges cannot be used efficiently, resulting in a reduction in processing efficiency and manufacturing costs. There was a problem that increased.

An aspect according to the present invention has been made to solve the above-described problems, and provides a phase shift mask capable of efficiently forming a fine, high-precision exposure pattern with a large area as in FPD manufacturing, and a method for manufacturing the same. The purpose is to do.

(1) A method of manufacturing a phase shift mask according to one aspect of the present invention includes a step of forming a light shielding layer mainly composed of Cr patterned on a transparent substrate; an inert gas, a nitriding gas, and an oxidizing gas Is sputtered with a target of a chromium-based material in an atmosphere of a mixed gas that includes: and a phase difference of about 180 ° with respect to i-line, and the oxidizing gas in the mixed gas is 10.4% or less forming and patterning a phase shift layer mainly composed of Cr capable of setting the difference between the g-line transmittance and the i-line transmittance to 5% or less.
(2) A phase shift mask according to one aspect of the present invention includes a light-shielding layer mainly composed of Cr formed on a transparent substrate; a phase difference of about 180 ° with respect to i-line; A phase shift layer containing Cr as a main component, which can make the difference between the transmittance and the transmittance of the i-line 5% or less.
(3) In the aspect of the above (2), the phase shift mask is formed such that the light shielding layer is formed on the surface of the transparent substrate, the phase shift layer is formed on the light shielding layer, or the transparent substrate Etching mainly comprising at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf on the surface. A stopper layer may be formed, and the light shielding layer may be formed on the etching stopper layer.

According to the above aspect (1), a step of forming a light shielding layer mainly composed of Cr patterned on a transparent substrate, and under an atmosphere of a mixed gas containing an inert gas, a nitriding gas, and an oxidizing gas Sputtering a chromium-based material target gives a phase difference of about 180 ° with respect to the i-line, and reduces the oxidizing gas in the mixed gas to 10.4% or less and the transmittance of the g-line. forming a phase shift layer mainly composed of Cr capable of making the difference from the transmittance of the i-line 5% or less, and patterning the composite wavelength region of 300 nm to 500 nm. It is possible to provide a phase shift mask blank having substantially the same transmittance with respect to any light and a manufacturing method capable of manufacturing the phase shift mask.
The phase shift mask blank can be a phase shift mask blank for a photomask used for exposure processing with a composite wavelength including g-line (436 nm), h-line (405 nm), and i-line (365 nm).

According to the above aspect (2), the light shielding layer mainly composed of Cr formed on the transparent substrate, the phase difference of about 180 ° with respect to the i-line, and the transmittance of the g-line By having a phase shift layer mainly composed of Cr that can make the difference between the transmittance of the h-line and the transmittance of the i-line 5% or less, it has a large area such as an FPD. Even in the object to be processed, high-definition exposure processing can be performed, and the manufacturing cost can be reduced.

In the case of (3) above, in the phase shift mask, the light shielding layer is formed on the surface of the transparent substrate, and the phase shift layer is formed on the light shielding layer, or the phase shift layer is formed on the surface of the transparent substrate. An etching stopper layer mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf is formed on the phase shift layer; The light shielding layer may be formed of a phase shift mask blank on which the light shielding layer is formed on the etching stopper layer.

According to the aspect of the present invention, a phase shift mask blank having a reduced difference in transmittance due to wavelength can be manufactured, so that a defect in an exposure process can be reduced in an object having a large area such as an FPD, and a high definition can be achieved. It is possible to provide a manufacturing method, a phase shift mask blank, and a manufacturing method thereof capable of manufacturing a phase shift mask capable of manufacturing a large object to be processed with a high yield.

It is process drawing explaining the manufacturing method of the phase shift mask which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between the transmittance | permeability of the phase shift layer of the said phase shift mask, and a transmitted light wavelength. It is an experimental result which shows the relationship between the film-forming conditions of the phase shift layer of the said phase shift mask, and an optical characteristic. It is process drawing explaining the manufacturing method of the phase shift mask which concerns on the 2nd Embodiment of this invention.

The production method of the present invention may include a step of patterning the light shielding layer on the transparent substrate. A phase shift layer is formed on the transparent substrate so as to cover the light shielding layer. The phase shift layer has an atmosphere of a mixed gas containing at least an inert gas, a nitriding gas of 40% or more and 90% or less, and an oxidizing gas of 10.4% or less, more preferably 40% or more and 70%. It is formed by sputtering a target of a chromium-based material in an atmosphere of a mixed gas containing the following nitriding gas and 9.2% to 10.4% oxidizing gas. The phase shift layer has a phase difference of 180 ° with respect to any light in a wavelength region of 300 nm or more and 500 nm or less, and light having a composite wavelength including g-line (436 nm), h-line (405 nm), and i-line (365 nm). Thus, the difference between the g-line transmittance, the h-line transmittance, and the i-line transmittance is 5% or less. Further, the formed phase shift layer is patterned into a predetermined shape.

In the phase shift mask of the present invention, the difference between the g-line transmittance, the h-line transmittance, and the i-line transmittance may be 5% or less and have a phase difference of about 180 °. It has a possible phase shift layer. Therefore, according to the phase shift mask, the inversion action of the phase can be achieved by using the composite wavelength including light in the above-mentioned wavelength region, particularly g-line (436 nm), h-line (405 nm), and i-line (365 nm) as exposure light. Thus, a region where the light intensity is minimized can be formed, and the exposure pattern can be made clearer. By such a phase shift effect, the pattern accuracy is greatly improved, and a fine and highly accurate pattern can be formed. The difference between the g-line transmittance and the i-line transmittance is more preferably 2.5% or more and 5% or less. By reducing the difference between the transmittance of the g-line and the transmittance of the i-line, the difference in transmittance at each wavelength is reduced, and the phase shift effect at each wavelength is increased.

When the phase shift layer is formed of a chromium oxynitride-based material, a sputtered film having a desired transmittance and refractive index can be stabilized by using a mixed gas atmosphere containing an oxidizing gas of 10.4% or less. Can be formed. If the oxidizing gas is 9.2% or more, a desired refractive index can be obtained. Therefore, the transmittance of g-line, h-line, and i-line is increased, and the phase shift effect is increased, which is preferable. However, even if the oxidizing gas is less than 9.2%, the transmittance value is low, and the phase shift effect is reduced, but the effect is recognized. It is good if the oxidizing gas is 6.5% or more. If the oxidizing gas exceeds 10.4%, the oxygen concentration in the film is too high and the desired transmittance and refractive index cannot be obtained, and oxidation of the target cannot be suppressed and stable sputtering can be performed. It becomes difficult. On the other hand, when the nitriding gas is less than 40%, target oxidation cannot be suppressed, and stable sputtering becomes difficult. If the nitriding gas exceeds 70%, it is difficult to obtain desired film properties such as transmittance and refractive index. By forming a film in a mixed gas atmosphere under the above conditions, for example, a phase shift layer having a transmittance of 1 to 20% with respect to i-line can be obtained. Even if the transmittance of the i-line is less than 1%, it is possible to obtain the effect of the phase shift layer slightly, and it may be 0.5% or more.

The thickness of the phase shift layer can be set to a thickness that gives a phase difference of about 180 ° to the i-line. Furthermore, the above-described phase shift layer may be formed with a thickness capable of giving a phase difference of about 180 ° with respect to the h-line or the g-line.
Here, “substantially 180 °” means 180 ° or near 180 °, and is, for example, 180 ° ± 10 ° or less.

The thickness of the phase shift layer is such that the difference between the g-line transmittance, the h-line transmittance, and the i-line transmittance is 5% or less, and the phase difference applied to the i-line and g The thickness can be set such that the difference from the phase difference applied to the line is 40 ° or less.
As a result, a constant phase shift effect can be obtained for each wavelength light, thereby ensuring a fine and highly accurate pattern formation.

The mixed gas may further contain an inert gas.
Thereby, stable formation of plasma becomes possible. Further, the concentrations of the nitriding gas and the oxidizing gas can be easily adjusted.

The FPD manufacturing method using the phase shift mask of the present invention includes a step of forming a photoresist layer on a substrate. A phase shift mask is disposed in proximity to the photoresist layer. The phase shift mask has a phase difference of 180 ° with respect to any light in a wavelength region of 300 nm or more and 500 nm or less, and transmits the g-line transmittance, the h-line transmittance, and the i-line transmittance. The phase shift layer is made of a chromium oxynitride-based material that can be 5% or less. The photoresist layer irradiates the phase shift mask with light having a composite wavelength including g-line (436 nm), h-line (405 nm), and i-line (365 nm) as light having a composite wavelength of 300 nm to 500 nm. It is exposed with.

In the phase shift mask, the difference between the transmittance of the g-line, the transmittance of the h-line, and the transmittance of the i-line is 5% or less, and any of wavelength regions of 300 nm to 500 nm is used. It has a phase shift layer capable of giving a phase difference of 180 ° to light. Therefore, according to the manufacturing method, the pattern accuracy based on the phase shift effect can be improved by using the light in the wavelength region, and a fine and highly accurate pattern can be formed. Thereby, a high-quality flat panel display can be manufactured.

As the light having the composite wavelength, light including g-line (436 nm), h-line (405 nm), and i-line (365 nm) can be used.

The phase shift mask of the present invention includes a transparent substrate, a light shielding layer, and a phase shift layer. The light shielding layer is formed on the transparent substrate. The phase shift layer is formed around the light-shielding layer, and the difference in transmittance between g-line, h-line, and i-line is 5% or less, and any of composite wavelength regions of 300 nm to 500 nm. It is made of a chromium oxynitride material capable of having a phase difference of 180 ° with respect to the light.

According to the phase shift mask, it is possible to improve the pattern accuracy based on the phase shift effect by using the light of the composite wavelength, and it is possible to form a fine and highly accurate pattern. The above effect becomes more prominent by using an exposure technique in which light having different wavelengths (for example, g-line (436 nm), h-line (405 nm), i-line (365 nm)) in the wavelength range is combined.

The thickness of the phase shift layer is such that the difference in transmittance between g-line, h-line and i-line is 5% or less, and the difference between the phase difference applied to i-line and the phase difference applied to g-line The thickness can be set to 30 ° or less.
As a result, a constant phase shift effect is obtained for each wavelength light, and fine and highly accurate pattern formation can be ensured.

<First Embodiment>
Below, one Embodiment of the manufacturing method of the phase shift mask which concerns on this invention is described based on drawing.
FIG. 1 is a process diagram schematically showing a method of manufacturing a phase shift mask according to the present embodiment.

The phase shift mask of this embodiment is configured as a patterning mask for an FPD glass substrate, for example. As will be described later, for the patterning of the glass substrate using the mask, a composite wavelength of i-line, h-line and g-line is used for exposure light.

In the method of manufacturing a phase shift mask according to the present embodiment, first, as shown in FIG. 1A, a light shielding layer 11 is formed on a transparent substrate 10.

As the transparent substrate 10, a material excellent in transparency and optical isotropy is used, for example, a quartz glass substrate is used. The size in particular of the transparent substrate 10 is not restrict | limited, According to the board | substrate (for example, board | substrate for FPD, a semiconductor substrate) exposed using the said mask, it selects suitably. In this embodiment, the present invention can be applied to a substrate having a diameter of about 100 mm, a rectangular substrate having a side of about 50 to 100 mm to a side of 300 mm or more, a quartz substrate having a length of 450 mm, a width of 550 mm, and a thickness of 8 mm. Even a substrate of 1000 mm or more can be used.

Further, the surface roughness of the transparent substrate 10 may be reduced by polishing the surface of the transparent substrate 10. The flatness of the transparent substrate 10 can be set to 50 μm or less, for example. As a result, the depth of focus of the mask is increased, and it is possible to greatly contribute to the formation of a fine and highly accurate pattern. The flatness of the transparent substrate is more preferably 20 μm or less, and it is preferably 10 μm or less because the contribution to the formation of a fine and high-definition pattern is further increased.

The light shielding layer 11 is made of metal chromium or a chromium compound (hereinafter also referred to as a chromium-based material), but is not limited thereto, and is a metal silicide-based material (for example, MoSi, TaSi, TiSi, WSi) or an oxide thereof. Nitride and oxynitride are applicable. The thickness of the light shielding layer 11 is not particularly limited, and may be a thickness (for example, 80 to 200 nm) at which an optical density equal to or higher than a predetermined value is obtained. As a film forming method, an electron beam vapor deposition method, a laser vapor deposition method, an atomic layer film formation method (ALD method), an ion assist sputtering method, or the like can be applied. Especially in the case of a large substrate, the film thickness is uniform by a DC sputtering method. It is possible to form a film with excellent properties.

Next, as shown in FIG. 1B, a photoresist layer 12 is formed on the light shielding layer 11. The photoresist layer 12 may be a positive type or a negative type. As the photoresist layer 12, a liquid resist is used, but a dry film resist may be used.

Subsequently, as shown in FIGS. 1C and 1D, the photoresist layer 12 is exposed and developed to remove the region 12a and form a resist pattern 12P1 on the light shielding layer 11 (FIG. 1). (C)). The resist pattern 12P1 functions as an etching mask for the light shielding layer 11, and the shape is appropriately determined according to the etching pattern of the light shielding layer 11.

Subsequently, as shown in FIG. 1E, the light shielding layer 11 is etched into a predetermined pattern shape. Thereby, the light shielding layer 11P1 patterned into a predetermined shape is formed on the transparent substrate 10.

A wet etching method or a dry etching method can be applied to the etching process of the light shielding layer 11, and in particular, when the substrate 10 is large, an etching process with high in-plane uniformity can be realized by adopting the wet etching method. Become.

The etching solution for the light shielding layer 11 can be appropriately selected. When the light shielding layer 11 is a chromium-based material, for example, an aqueous solution of ceric ammonium nitrate and perchloric acid can be used.
Since this etching solution has a high selection ratio with the glass substrate, the substrate 10 can be protected when the light shielding layer 11 is patterned. On the other hand, when the light shielding layer 11 is made of a metal silicide material, for example, ammonium hydrogen fluoride can be used as the etchant.

After the patterning of the light shielding layer 11P1, the resist pattern 12P1 is removed as shown in FIG. For example, a sodium hydroxide aqueous solution can be used for removing the resist pattern 12P1.

Next, as shown in FIG. 1G, the phase shift layer 13 is formed. The phase shift layer 13 is formed on the transparent substrate 10 so as to cover the light shielding layer 11P1.

As a film formation method of the phase shift layer 13, an electron beam (EB) vapor deposition method, a laser vapor deposition method, an atomic layer film formation (ALD) method, an ion assisted sputtering method, or the like can be applied. By adopting the DC sputtering method, it is possible to form a film with excellent film thickness uniformity. Note that the present invention is not limited to the DC sputtering method, and an AC sputtering method or an RF sputtering method may be applied.

The phase shift layer 13 is made of a chromium-based material. In particular, in the present embodiment, the phase shift layer 13 is made of chromium nitride oxide. According to the chromium-based material, good patternability can be obtained particularly on a large substrate. In addition, it is not restricted to chromium system material, For example, metal silicide type materials, such as MoSi, TaSi, WSi, CrSi, NiSi, CoSi, ZrSi, NbSi, TiSi, or these compounds, may be used. Furthermore, Al, Ti, Ni, or a compound thereof may be used.

When the phase shift layer 13 made of chromium oxynitride is formed by sputtering, a mixed gas of a nitriding gas and an oxidizing gas, or a mixed gas of an inert gas, a nitriding gas, and an oxidizing gas is used as a process gas. be able to. The film forming pressure can be set to 0.1 Pa to 0.5 Pa, for example. As the inert gas, halogen, especially argon can be applied.

The oxidizing gas includes CO, CO ₂ , NO, N ₂ O, NO ₂ , O _{2 and the} like. The nitriding gas includes NO, N ₂ O, NO ₂ , N _{2 and the} like. Ar, He, Xe or the like is used as the inert gas, but typically Ar is used. Note that the mixed gas may further contain a carbonizing gas such as CH ₄ .

The flow rate (concentration) of the nitriding gas and the oxidizing gas in the mixed gas is an important parameter for determining the optical properties (transmittance, refractive index, etc.) of the phase shift layer 13. In the present embodiment, the mixed gas is adjusted under conditions of a nitriding gas of 40% to 70% and an oxidizing gas of 9.2% to 10.4%. By adjusting the gas conditions, it is possible to optimize the refractive index, transmittance, reflectance, thickness and the like of the phase shift layer 13.

When the oxidizing gas is less than 9.2%, the oxygen concentration in the film is too low and the transmittance is too low. Further, when the oxidizing gas exceeds 10.4%, the oxygen concentration in the film is too high, and the variation in transmittance due to the wavelength of light becomes too large, and the oxidation of the target cannot be suppressed and is stable. Sputtering becomes difficult. Here, carbon dioxide can be raised as the oxidizing gas. If the nitriding gas is less than 40%, target oxidation cannot be suppressed, and stable sputtering becomes difficult. On the other hand, if the nitriding gas exceeds 90%, the oxygen concentration in the film is too low and it becomes difficult to obtain a desired refractive index. Here, nitrogen gas can be given as the nitriding gas. By forming a film in a mixed gas atmosphere under the above conditions, for example, a phase shift layer having a transmittance of 1 to 20% with respect to i-line can be obtained. The transmittance may be 0.5% or more.

The thickness of the phase shift layer 13 is set to a thickness capable of giving a phase difference of 180 ° to any of g-line, h-line, and i-line light in a wavelength region of 300 nm to 500 nm. The light to which the phase difference of 180 ° is given is inverted in phase, so that the intensity of the light is canceled by the interference action with the light that does not pass through the phase shift layer 13. By such a phase shift effect, a region where the light intensity is minimum (for example, zero) is formed, so that the exposure pattern becomes clear and a fine pattern can be formed with high accuracy.

In the present embodiment, the light in the wavelength region is a composite light (polychromatic light) of i-line (wavelength 365 nm), h-line (wavelength 405 nm), and g-line (wavelength 436 nm). Thus, the phase shift layer 13 is formed with a thickness that can give a phase difference of 180 °. The light having the target wavelength may be any of i-line, h-line, and g-line, or light in a wavelength region other than these. As the light whose phase is to be inverted has a shorter wavelength, a finer pattern can be formed.

In this embodiment, the phase shift layer 13 can be formed with a thickness such that the difference between the phase difference applied to the i-line and the phase difference applied to the g-line is 30 ° or less. Thereby, a fixed phase shift effect can be obtained for light of each wavelength. For example, the phase shift layer can be formed to a film thickness that can give a phase difference of about 180 ° (180 ° ± 10 °) to the h-line that is the intermediate wavelength region of the composite wavelength. As a result, a phase difference close to 180 ° can be imparted to any of the i-line and g-line light, and the same phase shift effect can be obtained for each light.

The film thickness of the phase shift layer 13 is preferably uniform in the plane of the transparent substrate 10.
In the present embodiment, the phase shift layer 13 is formed with a film thickness difference such that the difference in phase difference in the substrate plane is 20 ° or less for each single wavelength light of g-line, h-line, and i-line. . If the difference in phase difference exceeds 20 °, the intensity of light intensity decreases due to the effect of superimposing the light intensity at the composite wavelength, and the patterning accuracy decreases. By setting the difference of the phase difference to 15 ° or less, further 10 ° or less, the patterning accuracy can be further improved.

The transmittance of the phase shift layer 13 can be in the range of 1% to 20% for i-line, for example. The transmittance may be 0.5% or more. When the transmittance is less than 0.5%, it is difficult to obtain a sufficient phase shift effect, and it becomes difficult to expose a fine pattern with high accuracy. On the other hand, when the transmittance exceeds 20%, the film forming rate is lowered and the productivity is deteriorated.
In the above range, the transmittance can be in the range of 2% to 15%. Further, in the above range, the transmittance can be 3% or more and 10% or less.

The reflectance of the phase shift layer 13 is 40% or less, for example. Thereby, it is difficult to form a ghost pattern when patterning a substrate to be processed (flat panel substrate or semiconductor substrate) using the phase shift mask, and good pattern accuracy can be ensured.

The transmittance and reflectance of the phase shift layer 13 can be arbitrarily adjusted according to the gas conditions during film formation. According to the mixed gas conditions described above, a transmittance of 1% to 20% and a reflectance of 40% or less can be obtained with respect to i-line. The transmittance may be 0.5% or more.

The thickness of the phase shift layer 13 can be appropriately set within the range in which the above-described optical characteristics can be obtained. In other words, the optical characteristics described above can be obtained by optimizing the thickness of the phase shift layer 13. For example, the film thickness of the phase shift layer 13 that can obtain the optical characteristics depending on the gas conditions is, for example, 100 nm or more and 130 nm or less. In this range, the thickness of the phase shift layer 13 can be in the range of 110 nm to 125 nm.

For example, when the flow rate ratio of the mixed gas during sputtering film formation is Ar: N ₂ : CO ₂ = 71: 21.5: 120 and the film thickness is 114 nm, the transmittance for i-line is 3.10. %, The phase difference at the i-line can be 180 °, the transmittance at the g-line can be 7.95%, and the phase difference can be 150 °.

2 and 3 show experimental results showing the relationship between the film formation conditions during the film formation of the phase shift layer 13, the phase difference of each wavelength component, and the i-line transmittance. In this example, N ₂ was used as the nitriding gas, CO ₂ was used as the oxidizing gas, and Ar was used as the inert gas. The film forming pressure was 0.4 Pa.

As shown in Experimental Example 2, under conditions of a mixed gas containing an oxidizing gas of 9.2% or more and 10.4% or less, the transmittance for i-line is 3.10% and the phase difference for i-line is 180 °. , The transmittance in g-line can be 7.95%. Further, by forming the phase shift layer with a thickness that can give a phase difference of 180 ° ± 10 ° to the i-line, the difference in transmittance between the i-line, the h-line, and the g-line is reduced to 5% or less. Can be suppressed. Furthermore, the transmittance of i-line can be set in the range of 1% to 10%.

On the other hand, in Experimental Example 1 where the oxidizing gas is not in the range of 9.2% or more and 10.4% or less, the degree of oxidation of the film is small, and even if the film thickness is increased, i-line and g The difference in transmittance from the line could not be set within the required range. In Experimental Examples 3 and 4, although the transmittance was low, the transmittance difference between the i-line and the g-line could be reduced.

Subsequently, as shown in FIG. 1 (h), a photoresist layer 14 is formed on the phase shift layer 13. The photoresist layer 14 may be a positive type or a negative type. As the photoresist layer 14, a liquid resist is used.

Next, as shown in FIGS. 1J and 1K, the photoresist layer 14 is exposed and developed to form a resist pattern 14P1 on the phase shift layer 13. The resist pattern 14 </ b> P <b> 1 functions as an etching mask for the phase shift layer 13, and the shape is appropriately determined according to the etching pattern for the phase shift layer 13.

Subsequently, as shown in FIG. 1 (m), the phase shift layer 13 is etched into a predetermined pattern shape. Thereby, the phase shift layer 13P1 patterned in a predetermined shape is formed on the transparent substrate 10.

A wet etching method or a dry etching method can be applied to the etching process of the phase shift layer 13, and when the substrate 10 is large, an etching process with high in-plane uniformity can be realized by adopting the wet etching method. It becomes.

The etching solution for the phase shift layer 13 can be appropriately selected. In this embodiment, an aqueous solution of ceric ammonium nitrate and perchloric acid can be used. Since this etching solution has a high selectivity with respect to the glass substrate, the substrate 10 can be protected when the phase shift layer 13 is patterned.

After the patterning of the phase shift layer 13P1, the resist pattern 14P1 is removed as shown in FIG. For example, a sodium hydroxide aqueous solution can be used to remove the resist pattern 14P1.

As described above, the phase shift mask 1 according to this embodiment is manufactured. According to the phase shift mask 1 of the present embodiment, the phase shift layer 13P1 having the above-described configuration is formed around the light shielding layer pattern 11P1. As a result, when forming an exposure pattern on the substrate to be exposed using light of a composite wavelength including g-line (436 nm), h-line (405 nm), and i-line (365 nm), the i-line, h-line, and g-line The difference in transmittance between them can be suppressed to 5% or less, and the pattern accuracy based on the phase shift effect can be improved, so that a fine and highly accurate pattern can be formed. In particular, according to the present embodiment, it becomes more prominent by using an exposure technique in which light (g-line, h-line, and i-line) having different wavelengths in the above wavelength range is combined.

Hereinafter, a method for manufacturing a flat panel display using the phase shift mask 1 according to the present embodiment will be described.

First, a photoresist layer is formed on the surface of the glass substrate on which the insulating layer and the wiring layer are formed. For example, a spin coater is used to form the photoresist layer. The photoresist layer is subjected to a heating (baking) process and then subjected to an exposure process using the phase shift mask 1. In the exposure process, the phase shift mask 1 is disposed in the vicinity of the photoresist layer. The surface of the glass substrate is irradiated with a composite wavelength including g-line (436 nm), h-line (405 nm), and i-line (365 nm) of 300 nm to 500 nm through the phase shift mask 1. In the present embodiment, composite light of g-line, h-line, and i-line is used as the light of the composite wavelength. Thereby, the exposure pattern corresponding to the mask pattern of the phase shift mask 1 is transferred to the photoresist layer.

According to this embodiment, the phase shift mask 1 suppresses the difference in transmittance between the i-line, the h-line, and the g-line to 5% or less, and applies any light in a wavelength region of 300 nm to 500 nm. On the other hand, the phase shift layer 13P1 capable of giving a phase difference of 180 ° is provided. Therefore, according to the manufacturing method, since the pattern accuracy based on the phase shift effect can be improved by using the light in the wavelength region, and the depth of focus can be increased, a fine and highly accurate pattern can be obtained. Formation is possible. Thereby, a high-quality flat panel display can be manufactured.

According to the experiments by the present inventors, when exposure was performed using a mask that does not have the phase shift layer, a pattern width deviation of 30% or more with respect to the target line width (2 μm) occurred. When exposure was performed using the phase shift mask 1 of the present embodiment, it was confirmed that the deviation was suppressed to about 7%.

<Second Embodiment>
FIG. 4 is a process diagram for explaining a method of manufacturing a phase shift mask according to the second embodiment of the present invention. In FIG. 4, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

The phase shift mask 2 (FIG. 4 (J)) of the present embodiment has an alignment mark for alignment at the periphery, and this alignment mark is formed by the light shielding layer 11P2. Hereinafter, a method for manufacturing the phase shift mask 2 will be described.

First, the light shielding layer 11 is formed on the transparent substrate 10 (FIG. 4A). Next, a photoresist layer 12 is formed on the light shielding layer 11 (FIG. 4B). The photoresist layer 12 may be a positive type or a negative type. Subsequently, by exposing and developing the photoresist layer 12, a resist pattern 12P2 is formed on the light shielding layer 11 (FIG. 4C).

The resist pattern 12P2 functions as an etching mask for the light shielding layer 11, and the shape is appropriately determined according to the etching pattern of the light shielding layer 11. FIG. 4C shows an example in which a resist pattern 12P2 is formed so as to leave the light shielding layer over a predetermined range on the periphery of the substrate 10.

Subsequently, the light shielding layer 11 is etched into a predetermined pattern shape. Thereby, the light shielding layer 11P2 patterned in a predetermined shape is formed on the transparent substrate 10 (FIG. 4D). After the patterning of the light shielding layer 11P2, the resist pattern 12P2 is removed (FIG. 4E). For example, an aqueous sodium hydroxide solution can be used to remove the resist pattern 12P2.

Next, the phase shift layer 13 is formed. The phase shift layer 13 is formed on the transparent substrate 10 so as to cover the light shielding layer 11P2 (FIG. 4F). The phase shift layer 13 is made of a chromium oxynitride material and is formed by a DC sputtering method. In this case, a mixed gas of a nitriding gas and an oxidizing gas, or a mixed gas of an inert gas, a nitriding gas, and an oxidizing gas can be used as the process gas. The phase shift layer 13 is formed under the same film formation conditions as in the first embodiment described above.

Subsequently, a photoresist layer 14 is formed on the phase shift layer 13 (FIG. 4G).
Next, by exposing and developing the photoresist layer 14, a resist pattern 14P2 is formed on the phase shift layer 13 (FIG. 4H). The resist pattern 14P2 functions as an etching mask for the phase shift layer 13, and the shape is appropriately determined according to the etching pattern for the phase shift layer 13.

Subsequently, the phase shift layer 13 is etched into a predetermined pattern shape. Thereby, the phase shift layer 13P2 patterned in a predetermined shape is formed on the transparent substrate 10 (FIG. 4I). After the patterning of the phase shift layer 13P2, the resist pattern 14P2 is removed (FIG. 4J). For example, a sodium hydroxide aqueous solution can be used to remove the resist pattern 14P2.

As described above, the phase shift mask 2 according to this embodiment is manufactured. According to the phase shift mask 2 of the present embodiment, since the alignment mark is formed of the light shielding layer 11P2, the alignment mark can be easily recognized optically, and high-accuracy alignment is possible.
This embodiment can be implemented in combination with the first embodiment described above.

Further, the phase shift layer 13 can function as a halftone layer (semi-transmissive layer). In this case, it is possible to make a difference in exposure amount between light transmitted through the phase shift layer 13 and light not transmitted.

As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to this, A various deformation | transformation is possible based on the technical idea of this invention.

For example, in the first embodiment described above, the phase shift layer is formed and patterned after the light shielding layer is patterned. However, the present invention is not limited to this. After the phase shift layer is formed and patterned, the light shielding layer is formed. Films and patterning may be performed. That is, it is possible to change the stacking order of the light shielding layer and the phase shift layer. In this case, the etching (not shown) whose main component is at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W, and Hf is provided between the light shielding layer and the phase shift layer. A stopper layer is preferably provided.

In the above embodiment, after the light shielding layer 11 is formed on the entire surface of the substrate 10, the light shielding layer 11P1 is formed by etching a necessary portion. Instead, the formation region of the light shielding layer 11P1 is opened. After the resist pattern to be formed is formed, the light shielding layer 11 may be formed. After the formation of the light shielding layer 11, the light shielding layer 11P1 can be formed in a necessary region by removing the resist pattern (lift-off method).

The embodiment of the present invention has been described above, but the present invention is not limited to this, and can be appropriately changed without departing from the spirit of the invention.

1, 2 ... Phase shift mask 10 ... Transparent substrate 11, 11P1 ... Light shielding layer 12P1, 14P1 ... Resist pattern 13P1 ... Phase shift layer

Claims

Forming a light-shielding layer mainly composed of Cr patterned on a transparent substrate;
Sputtering a chromium-based material target in an atmosphere of a mixed gas containing an inert gas, a nitriding gas, and an oxidizing gas gives a phase difference of about 180 ° with respect to the i-line. Patterning is performed by forming a phase shift layer containing Cr as a main component, wherein the oxidizing gas is 10.4% or less, and the difference between the g-line transmittance and the i-line transmittance is 5% or less. And a step of manufacturing the phase shift mask.
A light-shielding layer mainly composed of Cr formed on a transparent substrate;
a phase shift layer containing Cr as a main component and having a phase difference of about 180 ° with respect to the i-line and a difference between the g-line transmittance and the i-line transmittance being 5% or less; A phase shift mask characterized by comprising:
The light shielding layer is formed on the surface of the transparent substrate,
The phase shift layer is formed on the light shielding layer, or the phase shift layer is formed on the surface of the transparent substrate,
An etching stopper layer mainly composed of at least one metal selected from Ni, Co, Fe, Ti, Si, Al, Nb, Mo, W and Hf is formed on the phase shift layer,
The phase shift mask according to claim 2, wherein the light shielding layer is formed on the etching stopper layer.