JP2023082515A - Mask blanks and halftone mask - Google Patents

Abstract

To provide an overlay type halftone mask with which it is possible to improve vertical cross-section properties of a pattern, and which is less prone to transmittance change with respect to wavelengths.SOLUTION: A mask blanks MB includes, as a mask layer, a transparent substrate S, a shading layer 11 composed mainly of chromium laminated on a surface of the transparent substrate, an antireflection layer 12 composed mainly of chromium laminated on the shading layer, and a halftone layer 13 composed mainly of chromium laminated on the antireflection layer. The halftone layer contains carbon, and an average value of C/Cr that is a ratio of carbon and chromium is set to a range of 0.26-0.34.SELECTED DRAWING: Figure 1

Description

The present invention relates to mask blanks and halftone masks.

Substrates for FPDs (flat panel displays) such as liquid crystal displays and organic EL displays are manufactured using a plurality of masks. The number of masks can be reduced. Furthermore, for color filters and organic EL displays, it is possible to form spacers and openings with appropriate shapes by controlling the shape of the photosensitive organic resin by exposing and developing it using a semi-transparent mask. be possible. For this reason, the importance of halftone masks is increasing.

As described in Patent Document 1, halftone masks include a lower type in which a light-shielding layer is laminated on a semi-transparent halftone layer, and an upper type in which the layering order is reversed. do.

In the FPD exposure using such a halftone mask, a composite wavelength of g-line (436 nm), h-line (405 nm) and i-line (365 nm) is used because the glass substrate is large.
Moreover, these days, it is demanded to improve the accuracy of patterning in FPD, to make the line width size finer, and to greatly improve the image quality. Therefore, in addition to the above wavelengths, there has been a demand to make it possible to adapt composite wavelengths including exposure light with a wavelength of 312 nm.

JP 2020-197698 A JP 2011-013283 A

However, in the halftone layer of the conventional top-mounted type halftone mask, the transmittance of exposure light having a short wavelength of 365 nm or less is low relative to other wavelengths, and in the exposure light having a compound wavelength, the transmittance is low. Since the amount of change in transmittance within the wavelength range is too large, there has been a demand to improve this.

In addition, in the underlay type halftone layer, there is a large difference in etching rate between the halftone layer and the light shielding layer, and there is a problem that verticality of the cross section after patterning is not required. This is because the amount of side etching of the halftone layer with respect to the light shielding layer portion is large, so the halftone layer close to the resist is etched more, resulting in the problem that the light shielding layer protrudes into the removal area of the patterning. .

The present invention has been made in view of the above circumstances, and aims to achieve the following objects.
1. To improve cross-sectional perpendicularity in an overlaid halftone mask.
2. To enable patterning using exposure light with compound wavelengths including shorter wavelengths in an overlying halftone mask.

The mask blanks of the present invention are
a transparent substrate;
a light-shielding layer mainly composed of chromium laminated on the surface of the transparent substrate;
an antireflection layer mainly composed of chromium laminated on the light shielding layer;
a halftone layer mainly composed of chromium laminated on the antireflection layer;
as a mask layer,
The halftone layer contains carbon, and the average value of C/Cr, which is the ratio of carbon to chromium, is set in the range of 0.26 to 0.34.
Thus, the above problem was solved.
The mask blanks of the present invention are
wherein the antireflection layer contains carbon;
The halftone layer contains carbon, and the value of C/Cr, which is the ratio of carbon to chromium at the boundary with the antireflection layer, is set in the range of 0.42 to 0.59.
be able to.
The mask blanks of the present invention are
The halftone layer contains nitrogen, and the average value of C/N, which is the ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63.
be able to.
The mask blanks of the present invention are
The halftone layer contains nitrogen, and the average value of N/Cr, which is the ratio of nitrogen to chromium, is set in the range of 0.47 to 0.54.
be able to.
The halftone mask of the present invention is
A halftone mask manufactured from the mask blank according to any one of the above,
The halftone layer has a wavelength-dependent transmittance change of less than 0.5% in exposure light having a compound wavelength in a wavelength range of 436 nm to 312 nm.
be able to.
The halftone mask of the present invention is
a mask pattern having a contour line at the edge of the outermost surface that is the most distant from the transparent substrate in the thickness direction after the mask layer is removed by patterning;
The end face of the mask pattern, which is erected with the contour line as the upper end and the transparent substrate surface as the lower end, extends from the contour line at the end of the outermost surface in a direction perpendicular to the contour line and along the outermost surface. the maximum protruding dimension α is less than 50 nm,
be able to.

The mask blanks of the present invention are
a transparent substrate;
a light-shielding layer mainly composed of chromium laminated on the surface of the transparent substrate;
an antireflection layer mainly composed of chromium laminated on the light shielding layer;
a halftone layer mainly composed of chromium laminated on the antireflection layer;
as a mask layer,
The halftone layer contains carbon, and the average value of C/Cr, which is the ratio of carbon to chromium, is set in the range of 0.26 to 0.34.
As a result, in the etching for patterning the mask layer with the necessary optical properties, the etching rate in the halftone layer increases, and the side etching in the halftone layer increases compared to other portions of the mask layer. It is possible to prevent this from being put away and improve cross-sectional perpendicularity in patterning.

The mask blanks of the present invention are
wherein the antireflection layer contains carbon;
The halftone layer contains carbon, and the value of C/Cr, which is the ratio of carbon to chromium at the boundary with the antireflection layer, is set in the range of 0.42 to 0.59.
Thus, by increasing the ratio of carbon to chromium in the halftone layer, the halftone layer suppresses an increase in the etching rate compared to the binary layer, that is, the light shielding layer and the antireflection layer. Side etching can be suppressed from increasing in the halftone layer.

The mask blanks of the present invention are
The halftone layer contains nitrogen, and the average value of C/N, which is the ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63.
This makes it possible to set the etching rates of the halftone layer and the binary layer serving as the light shielding layer and the antireflection layer, and the optical characteristics of each layer as predetermined states. Here, varying the carbon ratio can be used to control the etch rate in the halftone layer, and varying the nitrogen ratio can be used to control the etch rate, optical properties.

The mask blanks of the present invention are
The halftone layer contains nitrogen, and the average value of N/Cr, which is the ratio of nitrogen to chromium, is set in the range of 0.47 to 0.54.
This makes it possible to set the etching rates of the halftone layer and the binary layer serving as the light shielding layer and the antireflection layer, and the optical characteristics of each layer as predetermined states.

The halftone mask of the present invention is
A halftone mask manufactured from the mask blank according to any one of the above,
The halftone layer has a transmittance change of less than 0.5% with respect to exposure light of a compound wavelength in a wavelength range of 436 nm to 312 nm.
As a result, even when exposure light with a compound wavelength in a wide wavelength range is used, the difference in transmittance due to wavelength is not large, so it is possible to provide a halftone mask that can be applied to a high-definition photolithography process.

The halftone mask of the present invention is
a mask pattern having a contour line at the edge of the outermost surface that is the most distant from the transparent substrate in the thickness direction after the mask layer is removed by patterning;
The end face of the mask pattern, which is erected with the contour line as the upper end and the transparent substrate surface as the lower end, extends from the contour line at the end of the outermost surface in a direction perpendicular to the contour line and along the outermost surface. The maximum protruding dimension α is smaller than 50 nm.
This makes it possible to achieve both the required optical characteristics and the realization of a precise shape for mask pattern processing. As a result, it is possible to provide a halftone mask that enables high-definition processing with a wavelength in the above-described range and that can realize high-definition processing with an accurate patterning shape.

According to the present invention, it is possible to improve the cross-sectional perpendicularity of the top-mounted halftone mask, and to enable patterning using exposure light with compound wavelengths including shorter wavelengths. becomes.

1 is a cross-sectional view showing a first embodiment of mask blanks according to the present invention; FIG. 1 is a cross-sectional view showing a first embodiment of a halftone mask according to the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a film forming apparatus in a first embodiment of a method for manufacturing mask blanks and halftone masks according to the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a film forming apparatus in a first embodiment of a method for manufacturing mask blanks and halftone masks according to the present invention; 1 is a flow chart showing a first embodiment of a mask blank manufacturing method according to the present invention. 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; 1A to 1D are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a halftone mask according to the present invention; It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention. It is a graph which shows the Example which concerns on this invention.

A mask blank and a halftone mask according to a first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing the mask blanks in this embodiment, and in the figure, the symbol MB denotes the mask blanks.

The mask blanks MB according to this embodiment are intended to be used, for example, for a halftone mask used with exposure light having a wavelength in the range of 312 nm to 436 nm.
The mask blanks MB, as shown in FIG. and a halftone layer 13 formed thereon.

As the transparent substrate S, a material having excellent transparency and optical isotropy is used, and for example, a quartz glass substrate can be used. The size of the transparent substrate S is not particularly limited, and depends on the substrate to be exposed using the mask (e.g. LCD (liquid crystal display), plasma display, organic EL (electroluminescence) display, FPD substrate, semiconductor substrate). Selected as appropriate. This embodiment can be applied to a substrate with a diameter of about 100 mm, a rectangular substrate with a side of about 50 to 100 mm to 300 mm or more, and a quartz substrate with a length of 450 mm, a width of 550 mm, and a thickness of 8 mm. A substrate of 1000 mm or more and a thickness of 10 mm or more can also be used.

Further, the flatness of the transparent substrate S may be reduced by polishing the surface of the transparent substrate S. FIG. The flatness of the transparent substrate S can be set to 20 μm or less, for example. As a result, the depth of focus of the mask is increased, making it possible to greatly contribute to fine and highly accurate pattern formation. Furthermore, the flatness is 10 μm or less, and the smaller the better.

The light shielding layer 11 contains Cr as a main component, and specifically contains chromium, carbon and nitrogen. Furthermore, the light shielding layer 11 can have different compositions in the thickness direction. It can also be configured by laminating one or two or more selected from substances.
The light shielding layer 11 is formed with a thickness (for example, 80 nm to 200 nm) that provides predetermined optical characteristics.

The antireflection layer 12 contains Cr as a main component similarly to the light shielding layer 11, and specifically contains chromium, oxygen, carbon and nitrogen. Furthermore, the antireflection layer 12 can also have different compositions in the thickness direction, in which case the antireflection layer 12 is composed of Cr oxides, nitrides, carbides, oxynitrides, carbonitrides and oxycarbonitrides. It can also be configured by laminating one selected or two or more.
The antireflection layer 12 is formed with a thickness (for example, 5 nm to 100 nm) that provides predetermined optical characteristics.
The light shielding layer 11 and the antireflection layer 12 constitute a binary layer.

The halftone layer 13 contains Cr as a main component and contains carbon and nitrogen. It can be composed of one selected from the substances, or it can be composed by laminating two or more kinds selected from these.

For example, in the halftone layer 13, the average value of C/Cr, which is the ratio of carbon and chromium, in the thickness direction is set within the range of 0.26 to 0.34.
The halftone layer 13 has a value of C/Cr, which is the ratio of carbon and chromium, in the vicinity of the interface on the side close to the glass substrate S, that is, the boundary with the antireflection layer 12, in the range of 0.42 to 0.59. is set to

In the halftone layer 13, the average value of C/N, which is the ratio of carbon to nitrogen, in the thickness direction is set in the range of 0.55 to 0.63.
In the halftone layer 13, the average value of N/Cr, which is the ratio of nitrogen and chromium, in the thickness direction is set in the range of 0.47 to 0.54.

The halftone layer 13 has optical properties that can withstand use as a halftone mask, as will be described later.
The halftone layer 13 is formed with a thickness (for example, 5 nm to 100 nm) that provides predetermined optical characteristics.
In addition, in the halftone layer 13, the amount of change in transmittance due to wavelength is set to be smaller than 0.5% in the exposure light of the compound wavelength in the wavelength range of 436 nm to 312 nm.

In addition, in the vicinity of the outermost surface position of the halftone layer 13 and in the vicinity of the position close to the antireflection layer 12, the composition ratio of oxygen may be disturbed. However, it is about several atm %, and there is no problem with the etching characteristics and optical characteristics of the halftone layer 13 .

In the halftone layer 13, the composition ratio of oxygen is continuous from the outermost surface toward the transparent substrate S, that is, from the outermost surface toward the position close to the antireflection layer 12 in the thickness direction. may decrease. The gradient of the oxygen concentration in this halftone layer 13 is set to be substantially constant in the thickness direction.

In the halftone layer 13, the carbon composition ratio may have a peak near the outermost surface in the thickness direction. The change in carbon concentration in this halftone layer 13 corresponds to the increase in oxygen concentration near the outermost surface.
Accordingly, in the halftone layer 13, the value of C/Cr, which is the ratio of carbon to chromium, may have a peak near the outermost surface in the thickness direction.

In the halftone layer 13, the value of C/N, which is the ratio of carbon to nitrogen, may have a peak near the outermost surface in the thickness direction. This C/N peak is positioned deeper than the C/Cr peak, that is, close to the antireflection layer 12 .
Also, in the halftone layer 13, the value of N/Cr, which is the ratio of nitrogen to chromium, may be set so as to be substantially uniform in the thickness direction.

Here, the halftone layer 13 and the light shielding layer 11 are both chromium-based thin films and are oxidized and nitrided. , is set to be difficult to etch.

The mask blanks MB of this embodiment can be applied, for example, when manufacturing a halftone mask M which is a patterning mask for an FPD glass substrate.

FIG. 2 is a cross-sectional view showing a halftone mask manufactured from mask blanks in this embodiment.
As shown in FIG. 2, the halftone mask M of this embodiment has a transmissive area M1, a halftone area M2, and a light shielding area M3 in the mask blank MB.

The transmissive region M1 is an exposed region of the glass substrate (transparent substrate) S. As shown in FIG.
In the halftone region M2, the antireflection layer 12 and the light shielding layer 11 in the mask blank MB are patterned, and only the halftone pattern 13p patterned from the halftone layer 13 is formed on the glass substrate (transparent substrate) S. It is considered to be an area where

The light-shielding region M3 is patterned from the light-shielding layer 11, the antireflection layer 12, and the halftone layer 13 in the mask blank MB, and is a region in which the light-shielding pattern 11p, the antireflection pattern 12p, and the halftone pattern 13p are laminated. be.

In this halftone mask M, the halftone region M2 is, for example, a region in which the halftone pattern 13p can impart translucency to transmitted light in an exposure process. The light-shielding region M3 is a region in which irradiation light cannot be transmitted by the light-shielding pattern 11p in the exposure process.

For example, according to the halftone mask M, in the exposure process, in addition to the light in the wavelength range, particularly the g-line (436 nm), the h-line (405 nm), and the i-line (365 nm), the wavelength range of 312 nm, which is a short wavelength, is used. Composite wavelengths can be used as exposure light. This makes it possible to control the shape of the organic resin with high precision by performing exposure and development, and to form spacers and openings of appropriate shapes. In addition, pattern accuracy is significantly improved, and fine and highly accurate pattern formation becomes possible.

According to this halftone mask, pattern accuracy can be improved by using light in the above wavelength range, and fine and highly accurate pattern formation becomes possible. At the same time, in the halftone layer 13, the amount of change in transmittance due to the wavelength is set to be less than 0.5% with respect to exposure light having a compound wavelength in the wavelength range of 436 nm to 312 nm. By performing this process, the shape of the organic resin can be controlled with high precision, spacers and openings of appropriate shapes can be formed, and high-quality flat panel displays and the like can be manufactured.

A method for manufacturing the mask blanks MB of this embodiment will be described below.

The mask blanks MB in this embodiment are manufactured by the manufacturing apparatus shown in FIG. 3 or FIG.
FIG. 3 is a schematic diagram showing a manufacturing apparatus for manufacturing mask blanks in this embodiment.

The manufacturing apparatus S10 shown in FIG. 3 is an apparatus capable of inter-back sputtering. The manufacturing apparatus S10 has a load/unload chamber S11 and a film formation chamber (vacuum processing chamber, film formation section) S12.

The loading/unloading chamber S11 is provided with a conveying means S11a and an exhausting means S11b.
The conveying means S11a conveys the glass substrate S carried in from the outside to the film forming chamber S12. The exhaust means S11b is a rotary pump or the like for roughly evacuating the inside of the load/unload chamber S11.
The loading/unloading chamber S11 is connected to the film forming chamber S12 via a sealing means S17.

The film forming chamber S12 is provided with a substrate holding means S12a, a cathode electrode (backing plate) S12c having a target S12b, a power source S12d, a gas introduction means S12e, and a high vacuum evacuation means S12f.

The substrate holding means S12a receives the glass substrate S transported by the transport means S11a and holds the glass substrate S so as to face the target S12b during film formation.
The substrate holding means S12a can also carry in the glass substrate S from the loading/unloading chamber S11. The substrate holding means S12a can also carry out the glass substrate S to the loading/unloading chamber S11.

The target S12b is made of a material having a composition necessary for forming a light shielding layer 11, an antireflection layer 12, and a halftone layer 13 on the glass substrate S, which will be described later.
The power source S12d applies a negative sputtering voltage to the cathode electrode (backing plate) S12c having the target S12b.

The gas introducing means S12e introduces gas into the film forming chamber S12.
The high-vacuum evacuation means S12f is a turbo-molecular pump or the like that evacuates the inside of the film forming chamber S12 to a high vacuum.
These cathode electrode (backing plate) S12c, power supply S12d, gas introduction means S12e, and high vacuum evacuation means S12f are configured to supply materials for forming the light shielding layer 11, the antireflection layer 12, and the halftone layer 13, respectively. be.

In the manufacturing apparatus S10 shown in FIG. 3, a light-shielding layer 11 as a mask layer is first formed by sputtering in a film forming chamber (vacuum processing chamber) S12 on a glass substrate S carried in from a loading/unloading chamber S11. form a film. Next, the antireflection layer 12 is formed by sputtering film formation in the film formation chamber (vacuum processing chamber) S12. At this time, the film forming gas supplied to the film forming chamber (vacuum processing chamber) S12 is switched.
Then, the glass substrate S on which the light shielding layer 11 and the antireflection layer 12 are formed is carried out from the loading/unloading chamber S11.

Next, in an etching apparatus, the light shielding layer 11 and the antireflection layer 12 are patterned to form a light shielding pattern 11p and an antireflection pattern 12p.
Further, the glass substrate S for which patterning has been completed is loaded again from the load/unload chamber S11. A halftone layer 13 is formed by sputtering film formation in a film formation chamber (vacuum processing chamber) S12 on the glass substrate S carried in from the load/unload chamber S11. At this time, a film forming gas is supplied to the film forming chamber (vacuum processing chamber) S12.
Then, the glass substrate S on which the halftone layer 13 is formed is carried out from the loading/unloading chamber S11.

During film formation, a sputtering gas and a reaction gas are supplied from the gas introducing means S12e to the film forming chamber S12, and a sputtering voltage is applied to the backing plate (cathode electrode) S12c from an external power source. Alternatively, a predetermined magnetic field may be formed on the target S12b by a magnetron magnetic circuit. Ions of the sputtering gas excited by the plasma in the film-forming chamber S12 collide with the target S12b of the cathode electrode S12c to eject particles of the film-forming material. After the ejected particles are combined with the reaction gas, they adhere to the glass substrate S, thereby forming a predetermined film on the surface of the glass substrate S. FIG.

FIG. 4 is a schematic diagram showing a manufacturing apparatus for manufacturing mask blanks in this embodiment.
The manufacturing apparatus S20 shown in FIG. 4 is an apparatus capable of in-line sputtering. The manufacturing apparatus S20 has a load chamber S21, a film formation chamber (vacuum processing chamber, film formation section) S22, and an unload chamber S23.

The load chamber S21 is provided with transport means S21a and exhaust means S21b.
The transport means S21a transports the glass substrate S carried in from the outside to the film forming chamber S22. The evacuation means S21b is a rotary pump or the like for roughly evacuating the inside of the load chamber S21.
The load chamber S21 is connected to a film formation chamber (vacuum processing chamber) S22 via a sealing means S27.

The film formation chamber S22 is provided with a substrate holding means S22a, a cathode electrode (backing plate) S22c having a target S22b, a power source S22d, a gas introduction means S22e, and a high vacuum evacuation means S22f.

The substrate holding means S22a receives the glass substrate S transported by the transport means S21a and holds the glass substrate S so as to face the target S22b during film formation.
The substrate holding means S22a can also carry in the glass substrate S from the load chamber S21. The substrate holding means S22a can also unload the glass substrate S to the unloading chamber S23.

The target S22b is made of a material having a composition necessary for forming the light shielding layer 11, the antireflection layer 12, and the halftone layer 13 on the glass substrate.
A cathode electrode (backing plate) S22c, a power source S22d, a gas introduction means S22e, and a high vacuum evacuation means S22f are configured to supply materials for forming the halftone layer 13 and the like.

The power supply S22d applies a negative sputtering voltage to the cathode electrode (backing plate) S22c having the target S22b.
The gas introducing means S22e introduces gas into the film forming chamber S22.
The high-vacuum evacuation means S22f is a turbo-molecular pump or the like that evacuates the inside of the film forming chamber S22 to a high vacuum.
The film formation chamber S22 is connected to the unload chamber S23 via a sealing means S28.

The unloading chamber S23 is provided with a conveying means S23a and an exhausting means S23b.
The transport means S23a transports the glass substrate S loaded from the film forming chamber S22 to the outside. The exhaust means S23b is a rotary pump or the like for roughly evacuating the inside of the unloading chamber S23.

In the manufacturing apparatus S20 shown in FIG. 4, the original halftone layer 11A is first formed by sputtering film formation in the film formation chamber (vacuum processing chamber) S22 on the glass substrate S loaded from the load chamber S21. Thereafter, the glass substrate S on which film formation has been completed is carried out from the unload chamber S25.

In the manufacturing apparatus S20 shown in FIG. 4, first, the light shielding layer 11 as a mask layer is formed by sputtering film formation in the film formation chamber (vacuum processing chamber) S22 on the glass substrate S carried in from the load chamber S21. . Next, the antireflection layer 12 is formed by sputtering film formation in the film formation chamber (vacuum processing chamber) S22. At this time, the film forming gas supplied to the film forming chamber (vacuum processing chamber) S22 is switched.
Then, the glass substrate S on which the light shielding layer 11 and the antireflection layer 12 are formed is carried out from the unloading chamber S23.

Next, in an etching apparatus, the light shielding layer 11 and the antireflection layer 12 are patterned to form a light shielding pattern 11p and an antireflection pattern 12p.
Further, the glass substrate S on which patterning has been completed is loaded again from the load chamber S21. A halftone layer 13 is formed by sputtering film formation in a film formation chamber (vacuum processing chamber) S22 on the glass substrate S carried in from the load chamber S21. At this time, a film forming gas is supplied to the film forming chamber (vacuum processing chamber) S12.
Then, the glass substrate S on which the halftone layer 13 is formed is carried out from the unload chamber S23.

FIG. 5 is a flow chart showing a manufacturing process for manufacturing mask blanks and halftone masks in this embodiment. 6 to 13 are cross-sectional views showing the manufacturing process of the mask blanks in this embodiment. 14 to 17 are cross-sectional views showing steps of manufacturing a halftone mask using mask blanks in this embodiment.
As shown in FIG. 5, the method of manufacturing the mask blanks MB in this embodiment includes a substrate preparation step S00, a light shielding layer forming step S01, an antireflection layer forming step S02, a photoresist layer forming step S03, A resist pattern forming step S04, a halftone pattern forming step S05, a cleaning step S05b, a halftone layer forming step S06, a photoresist layer forming step S07, a resist pattern forming step S08, and a light shielding pattern forming step S09. , and a cleaning step S09b.

Here, in the description of the method for manufacturing the mask blanks MB in this embodiment, the processing using the manufacturing apparatus S20 shown in FIG. 4 will be described. When the mask blanks MB are manufactured by the manufacturing apparatus S10 shown in FIG. 3, the reference numerals of the S20 series are replaced with the S10 series, and the unload chamber S25 is replaced with the load/unload chamber S11 and the like.

In the substrate preparation step S00 shown in FIG. 5, the glass substrate S subjected to the above-described surface treatment is prepared (FIG. 6). After that, the transparent substrate S is loaded into the load chamber S21 shown in FIG.
In the load chamber S21, the transparent substrate S is supported by the transfer means S21a, and after the load chamber S21 is sealed, the inside of the load chamber S21 is roughly evacuated by the exhaust means S21b.

In this state, the sealing means S27 is released, the transparent substrate S is transported by the transport means S21a, the glass substrate S transported by the substrate holding means S22a is received, and the transparent substrate is placed in the film formation chamber (vacuum processing chamber) S22. Bring in S.
In the film forming chamber S22, the sealing means S27 is sealed after the transparent substrate S is carried.
In the film forming chamber (vacuum processing chamber) S22, the transparent substrate S is held by the substrate holding means S22a.

In the light shielding layer forming step S01 shown in FIG. 5, the inside of the film forming chamber (vacuum processing chamber) S22 shown in FIG. A sputtering gas and a reaction gas are supplied from the gas introducing means S22e to the film forming chamber S22, and a sputtering voltage is applied to the backing plate (cathode electrode) S22c from an external power source. Alternatively, a predetermined magnetic field may be formed on the target S22b by a magnetron magnetic circuit.

Ions of the sputtering gas excited by the plasma in the film-forming chamber S22 collide with the target S22b of the cathode electrode S22c to eject particles of the film-forming material. After the ejected particles are combined with the reaction gas, they adhere to the glass substrate S, thereby forming the light shielding layer 11 on the surface of the glass substrate S (FIG. 7).

Here, the target S22b is replaced with a target S22b having a composition necessary for forming the light shielding layer 11 in advance. Further, as a film forming gas necessary for film formation of the light shielding layer 11, a predetermined flow rate of a carbon-containing gas, a nitrogen-containing gas, or the like is supplied from the gas introducing means S22e, and the partial pressure thereof is switched to control. Keep the composition within the set range.
At this time, as shown in FIG. 18 to be described later, the light-shielding layer 11 to be formed has a predetermined composition ratio of oxygen, carbon, nitrogen, and chromium in the thickness direction. can be done.

In the antireflection layer forming step S02 shown in FIG. 5, the inside of the film forming chamber S22 shown in FIG. 4 is evacuated to a high vacuum by the high vacuum evacuation means S22f. A sputtering gas and a reaction gas are supplied from the gas introducing means S22e to the film forming chamber S22, and a sputtering voltage is applied to the backing plate (cathode electrode) S22c from an external power supply. Alternatively, a predetermined magnetic field may be formed on the target S22b by a magnetron magnetic circuit.

Ions of the sputtering gas excited by the plasma in the film-forming chamber S22 collide with the target S22b of the cathode electrode S22c to eject particles of the film-forming material. After the ejected particles are combined with the reaction gas, they adhere to the glass substrate S, thereby forming an antireflection layer 12 on the surface of the glass substrate S (FIG. 8).

Here, the target S22b is replaced with a target S22b having a composition necessary for forming the antireflection layer 12 in advance. In addition, as a film forming gas necessary for film formation of the antireflection layer 12, a predetermined flow rate of an oxygen-containing gas, a carbon-containing gas, a nitrogen-containing gas, or the like is supplied from the gas introducing means S22e, and the partial pressure thereof is controlled. to bring its composition within the set range.
At this time, the antireflection layer 12 to be deposited has a predetermined composition ratio of oxygen, a composition ratio of carbon, a composition ratio of nitrogen, and a composition ratio of chromium in the thickness direction, as shown in FIG. 18 described later. be able to.

As the photoresist layer forming step S03 shown in FIG. 5, a photoresist layer PR1 is formed on the antireflection layer 12 which is the top layer in the antireflection layer forming step S02 (FIG. 9). The photoresist layer PR1 may be of a positive type or a negative type, but may be of a positive type. A liquid resist, an adhesive film, or the like is used as the photoresist layer PR1.

In the resist pattern forming step S04 shown in FIG. 5, a photoresist pattern PR1p having a predetermined pattern shape (opening pattern) is formed on the antireflection layer 12 by exposing and developing the photoresist layer PR1. (Fig. 10).
The photoresist pattern PR1p functions as an etching mask for the light shielding layer 11 and the antireflection layer 12, and its shape is appropriately determined according to the etching patterns of the light shielding layer 11 and the antireflection layer 12. FIG.
As an example, the photoresist pattern PR1p is set in a corresponding shape so as to cover the transmissive region M1 and the light shielding region M3, except for the halftone region M2 in which only the halftone pattern 13p is laminated on the glass substrate S in a later process. be.

Next, as a halftone pattern forming step S05 shown in FIG. 5, the antireflection layer 12 and the light shielding layer 11 are sequentially wet-etched using a predetermined etchant through the photoresist pattern PR1p.
At this time, in etching the antireflection layer 12 and the light shielding layer 11 containing chromium, a chromium etchant, for example, an etchant containing ceric ammonium nitrate can be used.
Thus, a light shielding pattern 11p0 and an antireflection pattern 12p0 are formed (FIG. 11).

Next, in a cleaning step S05d shown in FIG. 5, the photoresist pattern PR1p is removed using a predetermined cleaning liquid.
Sulfuric acid hydrogen peroxide mixture or ozone water can be used as the cleaning liquid.
In the mask blank MB in this state, the light shielding pattern 11p0 and the antireflection pattern 12p0 are formed, and the glass substrate S has an exposed region corresponding to the removed halftone region M2 (FIG. 12).

Next, in the halftone layer forming step S06 shown in FIG. 5, in the film forming chamber (vacuum processing chamber) S22 shown in FIG. back. A sputtering gas and a reaction gas are supplied from the gas introducing means S22e to the film forming chamber S22, and a sputtering voltage is applied to the backing plate (cathode electrode) S22c from an external power supply. Alternatively, a predetermined magnetic field may be formed on the target S22b by a magnetron magnetic circuit.

Ions of the sputtering gas excited by the plasma in the film-forming chamber S22 collide with the target S22b of the cathode electrode S22c to eject particles of the film-forming material. Then, after the ejected particles are combined with the reaction gas, they adhere to the glass substrate S, thereby forming a halftone layer on the surface of the antireflection pattern 12p0 and the surface of the glass substrate S exposed corresponding to the halftone region M2. 13 is deposited (FIG. 13). The configuration shown in FIG. 13 may be referred to as mask blanks MB in this embodiment.

Here, the target S22b is replaced with a target S22b having a composition necessary for forming the halftone layer 13 in advance. In addition, as a film forming gas necessary for film forming the halftone layer 13, a predetermined flow rate of a carbon-containing gas, a nitrogen-containing gas, or the like is supplied from the gas introduction means S22e, and the partial pressure thereof is switched so as to control the partial pressure thereof. Keep its composition within the set range.
At this time, the halftone layer 13 to be deposited has a predetermined composition ratio of oxygen, carbon, nitrogen, and chromium in the thickness direction, as shown in FIG. 18, which will be described later. be able to.

As the photoresist layer forming step S07 shown in FIG. 5, a photoresist layer PR2 is formed on the halftone layer 13 which is the uppermost layer in the halftone layer forming step S06 (FIG. 14). The photoresist layer PR2 may be of a positive type or a negative type, but may be of a positive type. A liquid resist, an adhesive film, or the like is used as the photoresist layer PR2.

In the resist pattern forming step S08 shown in FIG. 5, a photoresist pattern PR2p having a predetermined pattern shape (opening pattern) is formed on the halftone layer 13 by exposing and developing the photoresist layer PR2. (Fig. 15).
The photoresist pattern PR1p functions as an etching mask for the light shielding pattern 11p0, the antireflection pattern 12p0, and the halftone layer 13, and has an appropriate shape according to the etching patterns of the light shielding pattern 11p0, the antireflection pattern 12p0, and the halftone layer 13. Determined.
As an example, the photoresist pattern PR2p includes a light-shielding region M3 and a halftone region except for the transmissive region M1 where the surface of the glass substrate S is exposed by removing the light-shielding pattern 11p0, the antireflection pattern 12p0, and the halftone pattern 13p in a post-process. The corresponding shape is set so as to cover M2.

Next, as the light shielding pattern forming step S09 shown in FIG. 5, the halftone layer 13, the antireflection pattern 12p0, and the light shielding pattern 11p0 are sequentially wet-etched using a predetermined etchant through the photoresist pattern PR2p.
At this time, the halftone layer 13 containing chromium, the antireflection pattern 12p0, and the light shielding pattern 11p0 can be etched using a chromium etchant such as an etchant containing ceric ammonium nitrate.
Thereby, a halftone pattern 13p, an antireflection pattern 12p, and a light shielding pattern 11p are formed (FIG. 16).

Next, in a cleaning step S09b shown in FIG. 5, the photoresist pattern PR2p is removed using a predetermined cleaning liquid.
Sulfuric acid hydrogen peroxide mixture or ozone water can be used as the cleaning liquid.
In the mask blank MB in this state, a mask pattern consisting of a halftone pattern 13p, an antireflection pattern 12p, and a light shielding pattern 11p is formed, and a region where the glass substrate S is exposed corresponding to the removed transmissive region M1 is formed. (Fig. 17).

In the light-shielding pattern forming step S09 shown in FIG. 5, the halftone layer 13 having the longest etching time has an average value of C/Cr, which is the ratio of carbon and chromium, of 0.26 to 0.34 as described above. range, and the value of C/Cr, which is the ratio of carbon and chromium at the boundary with the antireflection layer 12, is set in the range of 0.42 to 0.59, and the ratio of carbon and nitrogen, C/ By setting the average value of N in the range of 0.55 to 0.63 and the average value of N / Cr, which is the ratio of nitrogen and chromium, in the range of 0.47 to 0.54, binary By suppressing the amount of side etching of the antireflection layer 12 and the light shielding layer 11, which are layers, the cross-sectional perpendicularity of the mask pattern can be improved. At the same time, predetermined optical properties in the halftone pattern 13p can be exhibited.

As a result, as shown in FIG. 17, a predetermined light shielding pattern 11p and an antireflection pattern 12p which are optically set, and a halftone pattern 13p having desired optical characteristics are provided. A halftone mask M in which M2 and a light shielding region M3 are formed can be obtained.

According to the halftone mask M of this embodiment, the halftone layer 13 having the longest etching time has an average value of C/Cr, which is the ratio of carbon and chromium, of 0.26 to 0.34. is set in the range of C /N is set in the range of 0.55 to 0.63, and the average value of N/Cr, which is the ratio of nitrogen and chromium, is set in the range of 0.47 to 0.54, The amount of side etching is suppressed for the antireflection layer 12 and the light shielding layer 11, which are binary layers, and as will be described later, the maximum protruding dimension α is smaller than 50 nm, so that the cross-sectional perpendicularity of the mask pattern is improved. It can be adapted to a high-definition photolithography process.

At the same time, in the compound wavelength exposure light in the wavelength range of 436 nm to 312 nm, the change in transmittance of the halftone layer 13 due to the wavelength is less than 0.5%, so that the halftone pattern 13p exhibits predetermined optical characteristics. A halftone mask M can be manufactured.

Examples of the present invention will be described below.

As a specific example of the mask blanks and the halftone mask in the present invention, first, the manufacture of mask blanks will be described.

<Experimental example>
First, a light shielding layer and an antireflection layer are formed on a glass substrate for forming a halftone mask. Here, as shown in FIG. 18, a film having a predetermined composition ratio of chromium, oxygen, nitrogen, carbon, and the like is used. In addition, FIG. 18 shows composition evaluation using Auger electron spectroscopy.

Furthermore, when forming a halftone mask, first, using a resist process, the light-shielding layer and the antireflection layer are processed into a desired pattern by going through the process steps of resist coating, exposure, development, etching, and resist stripping. . Here, when using a light-shielding film containing chromium as a main component, it is common to use a mixed solution of ceric ammonium nitrate and perchloric acid as an etchant.

After that, a halftone layer is formed. Here, similarly to the light shielding layer and the antireflection layer, as shown in FIGS. 18 to 22, a film having a predetermined composition ratio of chromium, oxygen, nitrogen, carbon and the like is used. In this case, it is possible to form using a reactive sputtering method. FIG. 19 shows ratio values in the film thickness direction based on composition evaluation data using Auger electron spectroscopy.

Next, the halftone layer is similarly processed into a halftone pattern by going through the process steps of resist coating, exposure, development, etching, and resist stripping using a resist process.
By removing the resist film after processing the chromium-containing film to form the halftone pattern, the process of processing the light-shielding film, the antireflection film, and the halftone film is completed.

As described above, the top type halftone mask M requires at least two patterning processes using a resist. At this time, in the second patterning process, there is a process in which the halftone film and the binary film, which are chromium films of the same system, are simultaneously treated with the same etchant and cleaning solution. At this time, if the etching rates of the halftone film and the binary film are different, the unevenness of the cross-sectional shape of the pattern, that is, the end surface of the pattern erected from the glass substrate becomes large. Then, since the dimension of the pattern width becomes inaccurate, it may become impossible to form a high-definition pattern.

In order to suppress the occurrence of such unevenness, the difference in etching rate between the halftone film and the binary film is suppressed. Specifically, in a halftone film that tends to have a high etching rate, it is necessary to devise ways to reduce the etching rate. However, in photomasks, the optical characteristics of each layer are preset for a given exposure light, and are difficult to change.

Further, the importance of a flat halftone film that reduces the wavelength dependence of the transmittance of the halftone layer 13 is increasing.
In the FPD panel exposure process, the processing speed of exposure is very important, so light of multiple wavelengths is used in the exposure process unlike the semiconductor exposure process.

Generally, exposure is performed using g-line (436 nm), h-line (405 nm), and i-line (365 nm) light, which are strong emission line spectra of a high-pressure mercury lamp. Furthermore, recently, in order to cope with high-definition processing, it is being studied to simultaneously use light of a shorter wavelength, specifically 312 nm from a low-pressure mercury lamp or the like. Moreover, it is desirable that the transmittances at these wavelengths are as close to each other as possible.
Until now, it has been common to use a metallic chromium film, which is relatively unoxidized, as the halftone film.

However, it has been found that the following problems occur when such a chromium film is used as a halftone film. The problem with this is that light with a shorter wavelength of about 312 nm cannot be used as a halftone film as it is because the transmittance varies too much. Moreover, the difference in etching rate is too large, and the occurrence of the unevenness cannot be ignored.

In the halftone film, the present inventors have increased the amount of carbon contained in the halftone film, set it to a predetermined distribution in the film thickness direction, and formed the ratio distribution with other elements, which are elements, in a predetermined state. , it is possible to provide a halftone mask capable of suppressing the occurrence of unevenness.

In other words, in order to solve the problem that the transmittance largely depends on the wavelength and the unevenness cannot be ignored, in this embodiment, the carbon concentration of the halftone film is increased to appropriately control the carbon content ratio of the surface. At the same time, by setting the carbon content ratio at the boundary with the binary film in the depth direction of the halftone film to a predetermined range, the wavelength dependence of the transmittance is suppressed to a certain level or less, and the suppression of unevenness is improved. Is possible.

Examples of the present invention will be described below.
Here, confirmation tests performed as specific examples of the halftone layer in the present invention will be described.

<Experimental example 1>
As Experimental Example 1, a halftone film was laminated on a binary film having the same composition ratio as that of a conventionally used binary film. Film formation conditions at this time are shown below.

・Light-shielding film: Sputter deposition (inter-back type)
Deposition gas; N2 _, NO, Ar, Ar-methane mixed gas Target; Cr
Depending on power supply adjustment ・Anti-reflection film: Sputter deposition (inter-back type)
Deposition gas; CO ₂ , N ₂
Target; Cr
(by power supply adjustment)

Halftone film; Sputter deposition (Inter-back type)
Deposition gas; N ₂ , Ar, Ar-methane mixed gas, CO ₂
- Target; Cr
(by power supply adjustment)

The compositions of the formed binary film and the halftone film were evaluated using Auger electron spectroscopy.
The results are shown in FIG.

Also, the following ratio values were calculated from the Auger electron spectroscopy data.
・Average value of the C/Cr ratio in the film thickness direction of the halftone film: 0.31
・C/Cr ratio value at the boundary between the halftone film and the binary film: 0.53
The results are shown in FIG.
Here, it can be seen that C/Cr forms a mountain-like waveform with the apex near the boundary between the halftone film and the binary film in the film thickness direction.

Also, the following ratio values were calculated from the Auger electron spectroscopy data.
・Average value of the C/N ratio in the film thickness direction of the halftone film: 0.60
The results are shown in FIG.
Here, it can be seen that the C/N has a mountain-like waveform with the apex near the boundary between the halftone film and the binary film in the film thickness direction.

Also, the following ratio values were calculated from the Auger electron spectroscopy data.
・Average value of the N/Cr ratio in the film thickness direction of the halftone film: 0.52
The results are shown in FIG.

・Patterning resist; resist type GRX-M237
film thickness 735nm
Pre-bake 87°C 48min
Exposure: Contact exposure machine (Tamarack)
Development: DIP type developer AZ DEVELOPER (diluted with 50% pure water)
Development time: 30 sec more than specified Etching: Paddle type Etchant: MPM-E
Etching time; 20 sec more than specified

Cross sections of the patterned binary film and the halftone film were observed. The SEM image is shown in FIG.
From this image, it can be seen that there is little unevenness on the pattern end surface, that is, the etching rate of the halftone layer is not so different from that of the binary layer, and that only the halftone layer is not etched.

Furthermore, the following dimension α was calculated from the cross-sectional SEM image.
Definition of α: In a mask pattern in which the mask layer is removed by patterning and the edge of the outermost surface that is the most distant from the glass substrate in the thickness direction is the contour line, the contour line is the upper end and the glass substrate surface is the lower end. Let α be the maximum dimension by which the end face (side face/wall surface) of the mask pattern protrudes from the edge of the outermost surface in a direction perpendicular to the contour and along the outermost surface.
In other words, on the surface of the halftone layer, which is the outermost surface of the mask layer, the outline of the contour shape, which is the edge of the patterning, is the starting point, and the patterning edge (the wall surface erected from the glass substrate surface) is rough. Let α be the maximum value among the distance dimensions from the starting point in the direction along the substrate surface.
FIG. 24 shows an explanatory diagram for the definition of the dimension α.
α in this experimental example; 26 nm

<Experimental example 2>
As Experimental Example 2, a binary film having the same composition ratio as the conventional binary film was laminated with a halftone film having the same composition ratio as the conventional halftone film. Film formation conditions at this time are shown below.

・Light-shielding film: Sputter deposition (in-line type)
(An in-line film forming apparatus having a film forming method different from that of Experimental Example 1 was used.)
Deposition gas; N _{2 ,} NO, Ar, Ar-methane mixed gas (As for the gas flow rate setting, Ar was increased and Ar-methane mixed gas was increased as compared with Experimental Example 1.)
Target; Cr
(The supplied power was increased compared to Experimental Example 1.)
・Anti-reflection film: Sputter deposition (in-line type)
(An in-line film forming apparatus having a film forming method different from that of Experimental Example 1 was used.)
Deposition gas; CO ₂ , N ₂ , Ar
(As for the gas flow rate settings, compared to Experimental Example 1, Ar was added, _CO2 was decreased, and _N2 was increased.)
Target; Cr
(The supplied power was made larger than in Experimental Example 1.)

Halftone film; Sputter deposition (Inter-back type)
Deposition gas; N ₂ , Ar, Ar-methane mixed gas, CO ₂
(As for the gas flow rate settings, compared to Experimental Example 1, Ar and _CO2 were decreased, and _N2 was increased.)
- Target; Cr
(The supplied power was made smaller than in Experimental Example 1.)

The compositions of the formed binary film and the halftone film were evaluated using Auger electron spectroscopy.
The results are shown in FIG.

Also, the following ratio values were calculated from the Auger electron spectroscopy data.
・Average value of the C/Cr ratio in the film thickness direction of the halftone film: 0.14
・C/Cr ratio value at the boundary between the halftone film and the binary film: 0.20
The results are shown in FIG.

Also, the following ratio values were calculated from the Auger electron spectroscopy data.
・Average value of the C/N ratio in the film thickness direction of the halftone film: 0.21
The results are shown in FIG.

Also, the following ratio values were calculated from the Auger electron spectroscopy data.
・Average value of the N/Cr ratio in the film thickness direction of the halftone film: 0.67
The results are shown in FIG.

・Patterning resist; resist type GRX-M237
film thickness 735nm
Pre-bake 87°C 48min
Exposure: Contact exposure machine (Tamarack)
Development: DIP type developer AZ DEVELOPER (diluted with 50% pure water)
Development time: 30 sec more than specified Etching: Paddle type Etchant: MPM-E
Etching time; 20 sec more than specified

Cross sections of the patterned binary film and the halftone film were observed. The SEM image is shown in FIG.
From this image, it can be seen that unevenness occurs on the pattern end face, that is, the etching rate of the halftone layer is higher than that of the binary layer, and only the halftone layer is etched to a large extent.

Furthermore, the following dimension α was calculated from the cross-sectional SEM image.
FIG. 30 shows an explanatory diagram for the definition of the dimension α.
α in this experimental example; 53 nm

<Experimental example 3>
As Experimental Example 3, a binary film and a halftone film were formed in the same manner as in Experimental Example 2. Film formation conditions at this time are shown below.

・Light-shielding film: Sputter deposition (in-line type)
(An in-line film forming apparatus having a film forming method different from that of Experimental Example 1 was used.)
Film-forming gas: N2 _, NO, Ar, Ar-methane mixed gas (The gas flow rate setting was the same as in Experimental example 2.)
Target; Cr
The power supplied was the same as in Experimental Example 2.
・Anti-reflection film: Sputter deposition (in-line type)
(An in-line film forming apparatus having a film forming method different from that of Experimental Example 1 was used.)
Deposition gas; CO ₂ , N ₂ , Ar
(The gas flow rate setting was the same as in Experimental Example 2.)
Target; Cr
(The supplied power was the same as in Experimental Example 2.)

Halftone film; Sputter deposition (Inter-back type)
Deposition gas; N ₂ , Ar, Ar-methane mixed gas, CO ₂
( _The gas flow rates were set to less Ar and _CO2 and more N2 than in Experimental Example 1, and less _N2 and more _CO2 than Experimental Example 2.)
- Target; Cr
(The supplied power was made larger than in Experimental Example 2.)

Similarly, each ratio based on the compositional evaluation was determined using Auger electron spectroscopy in this experimental example. The results are shown in FIG. In particular, the composition ratio of the halftone film that forms the boundary with the antireflection film is also shown.
Similarly, the dimension α in the experimental example was obtained. The results are shown in FIG. In addition, in FIG. 31, the halftone film is written as HT.

<Experimental example 4>
As Experimental Example 4, a binary film and a halftone film were formed in the same manner as in Experimental Example 2. FIG. Film formation conditions at this time are shown below.

・Light-shielding film: Sputter deposition (inter-back type)
Film forming gas; N2 _, NO, Ar, Ar-methane mixed gas (The gas flow rate setting was the same as in Experimental Example 1.)
Target; Cr
(The supplied power was the same as in Experimental Example 1.)
・Anti-reflection film: Sputter deposition (inter-back type)
Deposition gas; CO ₂ , N ₂
(The gas flow rate setting was the same as in Experimental Example 1.)
Target; Cr
(The supplied power was the same as in Experimental Example 1.)

Halftone film; Sputter deposition (Inter-back type)
Deposition gas; N ₂ , Ar, Ar-methane mixed gas, CO ₂
(The gas flow rate setting was more _CO2 than Experimental Example 1.)
- Target; Cr
(The supplied power was made larger than in Experimental Example 1.)

Similarly, each ratio based on the compositional evaluation was determined using Auger electron spectroscopy in this experimental example. The results are shown in FIG. In particular, the composition ratio of the halftone film that forms the boundary with the antireflection film is also shown.
Similarly, the dimension α in the experimental example was obtained. The results are shown in FIG.

Furthermore, in each of the above experimental examples, the rate of change in transmittance with respect to wavelength was measured for each halftone film. Here, the wavelengths of light for measuring transmittance were g-line (436 nm), h-line (405 nm), i-line (365 nm), and 312 nm. Furthermore, the transmittance difference for these wavelengths was calculated.
The results are shown in FIGS. 31 and 32. FIG.

From these results, in the halftone mask of the present invention, the side etching of the halftone layer portion is not large with respect to the binary portion, so that the interface between the resist and the halftone layer bites in and the binary portion protrudes. is found to be suppressed. In other words, in the halftone mask of the present invention, the difference in etching rate between the halftone layer portion and the binary portion is suppressed. It can be seen that the verticality is excellent.

Furthermore, the exposure wavelength range has increased from 312 nm to 436 nm as masks have become more precise, and there is a demand for a shorter wavelength. , the transmittance for light with a short wavelength of 365 nm or less is not in a situation where the transmittance is lower than the transmittance for light with other wavelengths, but it is possible to suppress the amount of change in the exposure wavelength range expanded to the short side. I understand.
As a result, the halftone mask of the present invention can be suitably applied to an overlying halftone mask for a higher definition FPD.

MB... mask blanks M... halftone mask M1... transmissive area M2... halftone area M3... light shielding area S... glass substrate (transparent substrate)
PR1, PR2 Photoresist layer PR1p, PR2p Photoresist pattern 11 Light shielding layer 11p, 11p0 Light shielding pattern 12 Antireflection layer 12p, 12p0 Antireflection pattern 13 Halftone layer 13p Halftone pattern

Claims (6)

a transparent substrate;
a light-shielding layer mainly composed of chromium laminated on the surface of the transparent substrate;
an antireflection layer mainly composed of chromium laminated on the light shielding layer;
a halftone layer mainly composed of chromium laminated on the antireflection layer;
as a mask layer,
The halftone layer contains carbon, and the average value of C/Cr, which is the ratio of carbon to chromium, is set in the range of 0.26 to 0.34.
Mask blanks characterized by wherein the antireflection layer contains carbon;
The halftone layer contains carbon, and the value of C/Cr, which is the ratio of carbon to chromium at the boundary with the antireflection layer, is set in the range of 0.42 to 0.59.
The mask blank according to claim 1, characterized by: The halftone layer contains nitrogen, and the average value of C/N, which is the ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63.
3. The mask blank according to claim 1 or 2, characterized in that: The halftone layer contains nitrogen, and the average value of N/Cr, which is the ratio of nitrogen to chromium, is set in the range of 0.47 to 0.54.
4. The mask blank according to any one of claims 1 to 3, characterized in that: A halftone mask manufactured from the mask blank according to any one of claims 1 to 4,
The halftone layer has a wavelength-dependent transmittance change of less than 0.5% in exposure light having a compound wavelength in a wavelength range of 436 nm to 312 nm.
A halftone mask characterized by: a mask pattern having a contour line at the edge of the outermost surface that is the most distant from the transparent substrate in the thickness direction after the mask layer is removed by patterning;
The end face of the mask pattern, which is erected with the contour line as the upper end and the transparent substrate surface as the lower end, extends from the contour line at the end of the outermost surface in a direction perpendicular to the contour line and along the outermost surface. 6. A halftone mask according to claim 5, wherein the maximum projected dimension [alpha] is less than 50 nm.

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