JP7788263B2 - Mask blanks, halftone masks - Google Patents

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 multiple masks, but the number of masks can be reduced by using semi-transparent half-tone masks to reduce the number of processes. Furthermore, for color filters and organic EL displays, the photosensitive organic resin is exposed and developed using a semi-transparent mask, controlling the shape of the organic resin, making it possible to form spacers and openings of appropriate shapes. For this reason, half-tone masks are becoming increasingly important.

As described in Patent Document 1, half-tone masks come in two types: bottom-mounted types, in which a light-shielding layer is stacked on a semi-transparent half-tone layer, and top-mounted types, in which the stacking order is reversed.

In the exposure of FPDs 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 in size.
In addition, there is a demand for improving the patterning accuracy in FPDs, making line widths finer, and significantly improving image quality. Therefore, there is a demand for adapting composite wavelengths that include exposure light with a wavelength of 312 nm in addition to the above wavelengths.

Japanese Patent Application Laid-Open No. 2020-197698 JP 2011-013283 A

However, with the halftone layer of conventional top-mounted halftone masks, the transmittance for exposure light with short wavelengths of 365 nm or less is lower than for other wavelengths, and for exposure light with composite wavelengths, the amount of change in transmittance within that wavelength range is too large, so there was a demand for an improvement in this area.

Furthermore, with the bottom-mounted halftone layer, there was a large difference in etching rate between the halftone layer and the light-shielding layer, which meant that the cross-sectional perpendicularity required after patterning was not achieved. This was because the amount of side etching of the halftone layer relative to the light-shielding layer was large, so the halftone layer closest to the resist was etched more, resulting in the light-shielding layer protruding into the patterning removal area.

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

The mask blank of the present invention is
A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising as a mask layer,
the halftone layer contains carbon, and the average value of the ratio of carbon to chromium, C/Cr, is set in the range of 0.26 to 0.34 ;
the anti-reflective layer contains carbon;
the halftone layer contains carbon, and a C/Cr ratio of carbon to chromium at the boundary with the antireflection layer is set in the range of 0.42 to 0.59 ;
This solved the above problem.
The mask blank of the present invention is
A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising as a mask layer,
the halftone layer contains carbon, and the average value of the ratio of carbon to chromium, C/Cr, is set in the range of 0.26 to 0.34;
the halftone layer contains nitrogen, and an average C/N ratio, which is a ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63;
This solved the above problem.
The mask blank of the present invention is
A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising as a mask layer,
the halftone layer contains carbon, and the average value of the ratio of carbon to chromium, C/Cr, is set in the range of 0.26 to 0.34;
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 solved the above problem.
The mask blank of the present invention is
the anti-reflective layer contains carbon;
the halftone layer contains carbon, and a C/Cr ratio of carbon to chromium at the boundary with the antireflection layer is set in the range of 0.42 to 0.59;
It is possible.
The mask blank of the present invention is
the halftone layer contains nitrogen, and an average C/N ratio, which is a ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63;
It is possible.
The mask blank of the present invention is
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;
It is possible.
The halftone mask of the present invention comprises:
A halftone mask manufactured from any one of the mask blanks described above, wherein the halftone layer has a transmittance difference of less than 0.5% between exposure light having a wavelength of 436 nm and exposure light having a wavelength of 312 nm.
It is possible.
The halftone mask of the present invention comprises:
the mask layer is removed by patterning to have a mask pattern whose contour line is an edge of the outermost surface that is furthest from the transparent substrate in a thickness direction;
an end face of the mask pattern, which is erected with the contour line as an upper end and the transparent substrate surface as a lower end, has a maximum dimension α of protruding from the contour line of the end of the outermost surface in a direction perpendicular to the contour line and along the outermost surface, which is less than 50 nm;
It is possible.

The mask blank of the present invention is
A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising as a mask layer,
The halftone layer contains carbon, and the average value of the ratio of carbon to chromium, C/Cr, is set in the range of 0.26 to 0.34.
This allows the etching rate in the half-tone layer to be increased during etching to pattern the mask layer while maintaining the required optical properties, preventing side etching in the half-tone layer from becoming larger than in other parts of the mask layer, thereby improving the cross-sectional verticality in patterning.

The mask blank of the present invention is
the anti-reflective layer contains carbon;
The halftone layer contains carbon, and the C/Cr ratio of carbon to chromium at the boundary with the antireflection layer is set to a value in the range of 0.42 to 0.59.
In this way, by increasing the ratio of carbon to chromium in the halftone layer, the etching rate of the halftone layer can be prevented from becoming higher than that of the binary layer, i.e., the light-shielding layer and the anti-reflection layer, and side etching can be prevented from increasing in the halftone layer.

The mask blank of the present invention is
The halftone layer contains nitrogen, and the average value of the ratio of carbon to nitrogen, C/N, is set in the range of 0.55 to 0.63.
This allows the etching rates of the halftone layer and the binary layer (light-shielding layer and anti-reflection layer) and the optical properties of each layer to be set to predetermined states. Here, changing the carbon ratio can be used to control the etching rate of the halftone layer, and changing the nitrogen ratio can be used to control the etching rate and optical properties.

The mask blank of the present invention is
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 anti-reflection layer, as well as the optical characteristics of each layer, to predetermined states.

The halftone mask of the present invention comprises:
A halftone mask manufactured from any of the mask blanks described above,
The halftone layer has a transmittance that varies by less than 0.5% with wavelength in exposure light with a composite wavelength range of 436 nm to 312 nm.
As a result, even when exposure light with a composite wavelength in a wide wavelength range is used, the difference in transmittance due to wavelength is not large, so that a halftone mask that can be used in a high-definition photolithography process can be provided.

The halftone mask of the present invention comprises:
the mask layer is removed by patterning to have a mask pattern whose contour line is an edge of the outermost surface that is furthest from the transparent substrate in a thickness direction;
The end face of the mask pattern, which is erected with the contour line as its upper end and the transparent substrate surface as its lower end, has a maximum dimension α that protrudes from the contour line of the end of the outermost surface in a direction perpendicular to the contour line and along the outermost surface, which is less than 50 nm.
This makes it possible to achieve both the necessary optical characteristics and the realization of precise shapes for processing mask patterns, thereby making it possible to provide a halftone mask that enables high-definition processing using wavelengths in the above-mentioned range and that can achieve high-definition processing with accurate patterning shapes.

The present invention has the effect of improving the cross-sectional verticality of an overlay halftone mask and enabling it to be used for patterning using exposure light with composite wavelengths that include shorter wavelengths.

1 is a cross-sectional view showing a first embodiment of a mask blank according to the present invention. 1 is a cross-sectional view showing a first embodiment of a half-tone mask according to the present invention. 1 is a schematic diagram showing a film forming apparatus in a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention; 1 is a schematic diagram showing a film forming apparatus in a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention; 1 is a flowchart showing a first embodiment of a method for manufacturing a mask blank according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1A to 1C are process diagrams showing a first embodiment of a method for manufacturing a mask blank and a half-tone mask according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention. 1 is a graph showing an example according to the present invention.

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

The mask blanks MB according to this embodiment are intended to be used as halftone masks for use with exposure light having a wavelength in the range of 312 nm to 436 nm, for example.
As shown in FIG. 1, the mask blank MB is composed of a transparent substrate S, a light-shielding layer 11 formed on the transparent substrate S, an anti-reflection layer 12 formed on the light-shielding layer 11, and a half-tone layer 13 formed on the anti-reflection layer 12.

A material with excellent transparency and optical isotropy is used as the transparent substrate S; for example, a quartz glass substrate can be used. There are no particular restrictions on the size of the transparent substrate S, and it can be selected appropriately depending on the substrate to be exposed using the mask (for example, a substrate for an FPD such as an LCD (liquid crystal display), plasma display, or organic EL (electroluminescence) display, or a semiconductor substrate). In this embodiment, it is applicable to substrates with a diameter of approximately 100 mm, and rectangular substrates with sides ranging from approximately 50-100 mm to 300 mm or more. Furthermore, quartz substrates with a length of 450 mm, a width of 550 mm, and a thickness of 8 mm, and substrates with a maximum side dimension of 1000 mm or more and a thickness of 10 mm or more can also be used.

Furthermore, the surface of the transparent substrate S may be polished to reduce the flatness of the transparent substrate S. The flatness of the transparent substrate S can be, for example, 20 μm or less. This increases the depth of focus of the mask, which can greatly contribute to the formation of fine, highly accurate patterns. Furthermore, the smaller the flatness, the better, with 10 μm or less being preferable.

The light-shielding layer 11 is mainly composed of Cr, and specifically contains chromium, carbon, and nitrogen. Furthermore, the light-shielding layer 11 may have a composition that varies in the thickness direction. In this case, the light-shielding layer 11 may be formed by laminating one or more types selected from the group consisting of simple Cr, and oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides of Cr.
The light-shielding layer 11 is formed to a thickness (for example, 80 nm to 200 nm) that provides predetermined optical characteristics.

The antireflection layer 12 is mainly composed of Cr, similar to the light-shielding layer 11, and specifically contains chromium, oxygen, carbon, and nitrogen. Furthermore, the antireflection layer 12 may have a composition that varies in the thickness direction, and in this case, the antireflection layer 12 may be configured by laminating one or more types selected from oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides of Cr.
The anti-reflection layer 12 is formed to a thickness (for example, 5 nm to 100 nm) that provides predetermined optical characteristics.
The light-shielding layer 11 and the anti-reflection layer 12 form a binary layer.

The halftone layer 13 contains Cr as its main component, as well as carbon and nitrogen. Specifically, it can be composed of Cr alone, or one selected from Cr oxide, nitride, carbide, oxynitride, carbonitride, and oxycarbonitride. It can also be composed of a laminate of two or more selected from these.

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

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

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

Note that the oxygen composition ratio may be disturbed near the outermost surface of the halftone layer 13 and near the position close to the anti-reflection layer 12. However, this is only a few atomic percent, and does not affect the etching and optical properties of the halftone layer 13.

Furthermore, in the halftone layer 13, the oxygen composition ratio may continuously decrease in the thickness direction from the outermost surface position toward the transparent substrate S, that is, from the outermost surface toward the position closest to the anti-reflection layer 12. The gradient of the oxygen concentration in this halftone layer 13 is set to be approximately constant in the thickness direction.

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

Furthermore, in halftone layer 13, the C/N value, which is the ratio of carbon to nitrogen, may have a peak near the outermost surface in the thickness direction, which is located deeper than the C/Cr peak, i.e., closer to antireflection layer 12.
Furthermore, in halftone layer 13, the ratio of nitrogen to chromium, N/Cr, may be set to be approximately uniform in the thickness direction.

Here, both the halftone layer 13 and the light-shielding layer 11 are chromium-based thin films that are oxidized and nitrided, but in comparison, the halftone layer 13 has a higher degree of carbonization than the light-shielding layer 11, making it more difficult to etch.

The mask blanks MB of this embodiment can be used, for example, when manufacturing half-tone masks M, which are masks used for patterning glass substrates for FPDs.

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

The transmission region M1 is an exposed region of the glass substrate (transparent substrate) S.
The halftone region M2 is an area in which the anti-reflection 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.

The light-shielding region M3 is patterned from the light-shielding layer 11, anti-reflection layer 12, and half-tone layer 13 in the mask blank MB, and is an area where the light-shielding pattern 11p, anti-reflection pattern 12p, and half-tone pattern 13p are stacked.

In this halftone mask M, halftone region M2 is an area that can be made semi-transparent to transmitted light by halftone pattern 13p during exposure processing. Light-shielding region M3 is an area that can be made opaque to irradiated light by light-shielding pattern 11p during exposure processing.

For example, with the halftone mask M, it is possible to use light in the wavelength range, particularly g-line (436 nm), h-line (405 nm), and i-line (365 nm), as well as a composite wavelength including the short wavelength of 312 nm, as exposure light during the exposure process. This makes it possible to precisely control the shape of the organic resin through exposure and development, forming spacers and openings of appropriate shapes. Furthermore, pattern precision is greatly improved, enabling the formation of fine, highly accurate patterns.

This halftone mask uses light in the above wavelength range to improve pattern accuracy, enabling the formation of fine, high-precision patterns. At the same time, the halftone layer 13 is designed to have a wavelength-dependent transmittance change of less than 0.5% for exposure light with a composite wavelength range of 436 nm to 312 nm. This allows for highly precise control of the shape of the organic resin through exposure and development, forming spacers and openings of appropriate shapes, enabling the production of high-quality flat panel displays and other products.

The method for manufacturing the mask blank MB of this embodiment is 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 Figure 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 transfer means S11a and an exhaust means S11b.
The transport means S11a transports 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 that roughly evacuates 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 formation chamber S12 is equipped with a substrate holding means S12a, a cathode electrode (backing plate) S12c having a target S12b, a power supply 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 is also capable of carrying in the glass substrate S from the load/unload chamber S11. The substrate holding means S12a is also capable of carrying out the glass substrate S to the load/unload chamber S11.

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

The gas introduction means S12e introduces gas into the film formation chamber S12.
The high vacuum exhaust means S12f is a turbo molecular pump or the like that draws a high vacuum inside the film formation chamber S12.
The cathode electrode (backing plate) S12c, power source S12d, gas introduction means S12e, and high vacuum evacuation means S12f are configured to supply materials for forming the light-shielding layer 11, anti-reflection layer 12, and half-tone layer 13, respectively.

3, a light-shielding layer 11 serving 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 load/unload chamber S11. Next, an anti-reflection layer 12 is formed by sputtering in the film-forming 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 anti-reflection layer 12 are formed is carried out from the loading/unloading chamber S11 to the outside.

Next, the light-shielding layer 11 and the anti-reflection layer 12 are patterned in an etching device to form a light-shielding pattern 11p and an anti-reflection pattern 12p.
Furthermore, the glass substrate S after patterning is again carried in from the loading/unloading chamber S11. A half-tone layer 13 is formed on the glass substrate S carried in from the loading/unloading chamber S11 by sputtering in a film-forming chamber (vacuum processing chamber) S12. 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 has been formed is carried out from the loading/unloading chamber S11 to the outside.

During film formation, sputtering gas and reactive gas are supplied to the film formation chamber S12 from the gas introduction means S12e, and a sputtering voltage is applied to the backing plate (cathode electrode) S12c from an external power supply. A predetermined magnetic field may also be formed on the target S12b using a magnetron magnetic circuit. Ions of the sputtering gas excited by plasma in the film formation chamber S12 collide with the target S12b on the cathode electrode S12c, ejecting particles of the film formation material. The ejected particles then combine with the reactive gas and adhere to the glass substrate S, forming a predetermined film on the surface of the glass substrate S.

FIG. 4 is a schematic diagram showing a manufacturing apparatus for manufacturing mask blanks in this embodiment.
4 is an in-line sputtering apparatus having a load chamber S21, a film formation chamber (vacuum processing chamber, film formation unit) S22, and an unload chamber S23.

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

The film formation chamber S22 is equipped 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 is also capable of carrying in the glass substrate S from the load chamber S21, and is also capable of carrying out the glass substrate S to the unload chamber S23.

The target S22b is made of a material having a composition necessary for forming the light-shielding layer 11, the anti-reflection layer 12, and the half-tone layer 13 on the glass substrate S.
The cathode electrode (backing plate) S22c, the power source S22d, the gas introduction means S22e, and the high vacuum evacuation means S22f are components for supplying materials for forming the halftone layer 13 and other layers.

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

The unloading chamber S23 is provided with a transport means S23a and an exhaust means S23b.
The transport means S23a transports the glass substrate S carried in from the film forming chamber S22 to the outside. The exhaust means S23b is a rotary pump or the like that roughly evacuates the inside of the unload chamber S23.

In the manufacturing apparatus S20 shown in Figure 4, a glass substrate S is loaded from a loading chamber S21, and an original half-tone layer 11A is first formed on the substrate by sputtering in a deposition chamber (vacuum processing chamber) S22. The glass substrate S on which deposition has been completed is then unloaded from an unloading chamber S25 to the exterior.

4, a light-shielding layer 11 serving as a mask layer is first formed by sputtering in a film-forming chamber (vacuum processing chamber) S22 on a glass substrate S carried in from a load chamber S21. Next, an anti-reflection layer 12 is formed by sputtering in the film-forming 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 anti-reflection layer 12 are formed is carried out from the unloading chamber S23 to the outside.

Next, the light-shielding layer 11 and the anti-reflection layer 12 are patterned in an etching device to form a light-shielding pattern 11p and an anti-reflection pattern 12p.
Furthermore, the glass substrate S after patterning is again carried in from the load chamber S21. A half-tone layer 13 is formed on the glass substrate S carried in from the load chamber S21 by sputtering in the film formation chamber (vacuum processing chamber) S22. At this time, the film formation gas supplied to the film formation chamber (vacuum processing chamber) S12 is supplied.
Then, the glass substrate S on which the half-tone layer 13 has been formed is carried out from the unload chamber S23 to the outside.

Fig. 5 is a flowchart showing the manufacturing process for manufacturing a mask blank and a half-tone mask in this embodiment. Figs. 6 to 13 are cross-sectional views showing the manufacturing process for a mask blank in this embodiment. Figs. 14 to 17 are cross-sectional views showing the manufacturing process for a half-tone mask using a mask blank in this embodiment.
As shown in FIG. 5 , the method for manufacturing a mask blank MB in this embodiment includes a substrate preparation step S00, a light-shielding layer formation step S01, an anti-reflection layer formation step S02, a photoresist layer formation step S03, a resist pattern formation step S04, a half-tone pattern formation step S05, a cleaning step S05b, a half-tone layer formation step S06, a photoresist layer formation step S07, a resist pattern formation step S08, a light-shielding pattern formation step S09, and a cleaning step S09b.

Here, in describing the method for manufacturing mask blanks MB in this embodiment, processing using the manufacturing apparatus S20 shown in FIG. 4 will be described. When manufacturing mask blanks MB using the manufacturing apparatus S10 shown in FIG. 3, the reference numerals in the S20s should be read as S10s, and the unload chamber S25 should be read as the load/unload chamber S11, etc.

5, a glass substrate S that has been subjected to the above-mentioned surface treatment is prepared (FIG. 6). Thereafter, the transparent substrate S is carried into the load chamber S21 shown in FIG.
In the load chamber S21, the transparent substrate S is supported by the transport means S21a, and after the load chamber S21 is sealed, the inside of the load chamber S21 is roughly evacuated to a vacuum by the exhaust means S21b.

In this state, the sealing means S27 is opened, the transparent substrate S is transported by the transporting means S21a, the glass substrate S transported by the substrate holding means S22a is received, and the transparent substrate S is carried into the film forming chamber (vacuum processing chamber) S22.
In the film-forming chamber S22, after the transparent substrate S is carried in, the sealing means S27 is closed.
In the film forming chamber (vacuum processing chamber) S22, the transparent substrate S is held by a substrate holding means S22a.

In the light-shielding layer deposition process S01 shown in Figure 5, the interior of the deposition chamber (vacuum processing chamber) S22 shown in Figure 4 is evacuated to a high vacuum using the high-vacuum evacuation means S22f. Then, sputtering gas and reactive gas are supplied to the deposition chamber S22 from the gas introduction means S22e, and a sputtering voltage is applied to the backing plate (cathode electrode) S22c from an external power supply. A predetermined magnetic field may also be formed on the target S22b using a magnetron magnetic circuit.

Ions of the sputtering gas excited by the plasma in the film-forming chamber S22 collide with the target S22b on the cathode electrode S22c, releasing particles of the film-forming material. The released particles then combine with the reactive gas and adhere to the glass substrate S, depositing a light-shielding layer 11 on the surface of the glass substrate S (Figure 7).

Here, the target S22b is replaced in advance with a target S22b having a composition required for forming the light-shielding layer 11. Furthermore, a carbon-containing gas, a nitrogen-containing gas, or the like is supplied at a predetermined flow rate from the gas introduction means S22e as a film-forming gas required for forming the light-shielding layer 11, and the partial pressures of these gases are controlled to set the composition within a set range.
At this time, the formed light-shielding layer 11 can have predetermined composition ratios of oxygen, carbon, nitrogen, and chromium in the thickness direction, as shown in FIG. 18 described later.

In the anti-reflection layer deposition process S02 shown in Figure 5, the interior of the deposition chamber S22 shown in Figure 4 is evacuated to a high vacuum using the high-vacuum evacuation means S22f. Then, sputtering gas and reactive gas are supplied to the deposition chamber S22 from the gas introduction means S22e, and a sputtering voltage is applied to the backing plate (cathode electrode) S22c from an external power supply. A predetermined magnetic field may also be formed on the target S22b using a magnetron magnetic circuit.

Ions of the sputtering gas excited by the plasma in the film formation chamber S22 collide with the target S22b on the cathode electrode S22c, ejecting particles of the film formation material. The ejected particles then combine with the reactive gas and adhere to the glass substrate S, depositing an anti-reflection layer 12 on the surface of the glass substrate S (Figure 8).

Here, the target S22b is replaced in advance with a target S22b having a composition required for forming the antireflection layer 12. Furthermore, as the film formation gas required for forming 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 introduction means S22e, and the partial pressures of these gases are controlled to set the composition within a set range.
In this case, the antireflection layer 12 to be formed can have predetermined composition ratios of oxygen, carbon, nitrogen, and chromium in the thickness direction, as shown in FIG. 18 described later.

In the photoresist layer formation step S03 shown in Figure 5, a photoresist layer PR1 is formed on the anti-reflection layer 12, which is the uppermost layer in the anti-reflection layer deposition step S02 (Figure 9). The photoresist layer PR1 may be either positive or negative, but is preferably positive. Liquid resist, adhesive film, etc., can be used as the photoresist layer PR1.

In the resist pattern forming step S04 shown in FIG. 5, the photoresist layer PR1 is exposed and developed to form a photoresist pattern PR1p having a predetermined pattern shape (opening pattern) on the anti-reflection layer 12 (FIG. 10).
The photoresist pattern PR1p functions as an etching mask for the light-shielding layer 11 and the anti-reflection layer 12, and its shape is determined appropriately according to the etching patterns of these light-shielding layer 11 and the anti-reflection layer 12.
As an example, the photoresist pattern PR1p is set to a shape corresponding to the halftone region M2 where only the halftone pattern 13p will be laminated on the glass substrate S in a subsequent process, so as to cover the transmissive region M1 and the light-shielding region M3.

Next, in the halftone pattern forming step S05 shown in FIG. 5, the anti-reflection layer 12 and the light-shielding layer 11 are sequentially wet-etched through the photoresist pattern PR1p using a predetermined etching solution.
In this case, when etching the antireflection layer 12 and the light-shielding layer 11 containing chromium, an etching solution containing a chromium etchant, for example, cerium diammonium nitrate, can be used.
As a result, a light-shielding pattern 11p0 and an anti-reflection 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.
As the cleaning liquid, sulfuric acid/hydrogen peroxide mixture or ozone water can be used.
In the mask blank MB in this state, the light-shielding pattern 11p0 and the anti-reflection pattern 12p0 are formed, and the glass substrate S has exposed areas corresponding to the removed half-tone areas M2 (FIG. 12).

Next, in the halftone layer deposition process S06 shown in FIG. 5, the interior of the deposition chamber (vacuum processing chamber) S22 shown in FIG. 4 is evacuated to a high vacuum using the high-vacuum exhaust means S22f. Then, sputtering gas and reactive gas are supplied to the deposition chamber S22 from the gas introduction means S22e, and a sputtering voltage is applied to the backing plate (cathode electrode) S22c from an external power supply. A predetermined magnetic field may also be formed on the target S22b using a magnetron magnetic circuit.

Ions of the sputtering gas excited by the plasma in the film formation chamber S22 collide with the target S22b on the cathode electrode S22c, ejecting particles of the film formation material. The ejected particles then combine with the reactive gas and adhere to the glass substrate S, depositing a halftone layer 13 on the surface of the anti-reflection pattern 12p0 and on the surface of the glass substrate S exposed corresponding to the halftone region M2 (Figure 13). The configuration shown in Figure 13 may also be referred to as a mask blank MB in this embodiment.

Here, the target S22b is replaced in advance with a target S22b having a composition required for forming half-tone layer 13. Furthermore, as the film formation gas required for forming half-tone layer 13, a carbon-containing gas, a nitrogen-containing gas, or the like is supplied at a predetermined flow rate from gas introduction means S22e, and the partial pressures of the gases are controlled to set the composition within a set range.
At this time, the half-tone layer 13 to be formed can have predetermined composition ratios of oxygen, carbon, nitrogen, and chromium in the thickness direction, as shown in FIG. 18 described later.

In the photoresist layer formation step S07 shown in Figure 5, a photoresist layer PR2 is formed on the halftone layer 13, which is the uppermost layer in the halftone layer deposition step S06 (Figure 14). The photoresist layer PR2 may be either positive or negative, but is preferably positive. Liquid resist, adhesive film, etc., can be used as the photoresist layer PR2.

In the resist pattern forming step S08 shown in FIG. 5, the photoresist layer PR2 is exposed and developed to form a photoresist pattern PR2p having a predetermined pattern shape (opening pattern) on the halftone layer 13 (FIG. 15).
The photoresist pattern PR1p functions as an etching mask for the light-shielding pattern 11p0, the anti-reflection pattern 12p0, and the half-tone layer 13, and its shape is determined appropriately according to the etching patterns of the light-shielding pattern 11p0, the anti-reflection pattern 12p0, and the half-tone layer 13.
As an example, the photoresist pattern PR2p is set to a corresponding shape so as to cover the light-shielding region M3 and the halftone region M2, except for the transparent region M1 where the light-shielding pattern 11p0, the anti-reflection pattern 12p0, and the halftone pattern 13p are removed in a subsequent process to expose the surface of the glass substrate S.

Next, in a light-shielding pattern formation step S09 shown in FIG. 5, half-tone layer 13, anti-reflection pattern 12p0, and light-shielding pattern 11p0 are sequentially wet-etched through photoresist pattern PR2p using a predetermined etching solution.
At this time, in etching half-tone layer 13 containing chromium, anti-reflection pattern 12p0, and light-shielding pattern 11p0, an etching solution containing a chromium etchant, for example, cerium diammonium nitrate, can be used.
As a result, a halftone pattern 13p, an anti-reflection 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.
As the cleaning liquid, sulfuric acid/hydrogen peroxide mixture or ozone water can be used.
In this state, the mask blank MB has a mask pattern consisting of a halftone pattern 13p, an anti-reflection pattern 12p, and a light-shielding pattern 11p, and has exposed areas of the glass substrate S corresponding to the removed transmissive areas M1 (Figure 17).

In the light-shielding pattern formation step S09 shown in Figure 5, the halftone layer 13, which takes the longest etching time, has an average carbon-to-chromium ratio (C/Cr) set to a range of 0.26 to 0.34, as described above, a carbon-to-chromium ratio (C/Cr) at the boundary with the anti-reflection layer 12 set to a range of 0.42 to 0.59, an average carbon-to-nitrogen ratio (C/N) set to a range of 0.55 to 0.63, and an average nitrogen-to-chromium ratio (N/Cr) set to a range of 0.47 to 0.54. This reduces the amount of side etching for the binary layers of the anti-reflection layer 12 and light-shielding layer 11, improving the cross-sectional perpendicularity of the mask pattern. At the same time, the halftone pattern 13p exhibits the desired optical characteristics.

As a result, as shown in Figure 17, a halftone mask M can be obtained, which has a predetermined optically set light-shielding pattern 11p, an anti-reflection pattern 12p, and a halftone pattern 13p with the desired optical characteristics, and in which a transmissive region M1, a halftone region M2, and a light-shielding region M3 are formed.

With the halftone mask M of this embodiment, the halftone layer 13, which takes the longest time to etch, has an average carbon-to-chromium ratio (C/Cr) set to a range of 0.26 to 0.34, as described above, a carbon-to-chromium ratio (C/Cr) at the boundary with the anti-reflection layer 12 set to a range of 0.42 to 0.59, an average carbon-to-nitrogen ratio (C/N) set to a range of 0.55 to 0.63, and an average nitrogen-to-chromium ratio (N/Cr) set to a range of 0.47 to 0.54. This reduces the amount of side etching for the binary layers of the anti-reflection layer 12 and light-shielding layer 11, and as described below, the maximum protruding dimension α is less than 50 nm, improving the cross-sectional perpendicularity of the mask pattern and enabling compatibility with high-resolution photolithography processes.

At the same time, because the change in transmittance of the halftone layer 13 due to wavelength is less than 0.5% for exposure light with a composite wavelength range of 436 nm to 312 nm, it is possible to manufacture a halftone mask M that can exhibit the specified optical characteristics of the halftone pattern 13p.

The following describes examples of the present invention.

As a specific example of mask blanks and halftone masks in the present invention, we will first explain the manufacture of mask blanks.

<Experimental Example>
First, a light-shielding layer and an anti-reflection layer are formed on a glass substrate for forming a half-tone mask. Here, as shown in Fig. 18, a film having a predetermined composition ratio of chromium, oxygen, nitrogen, carbon, etc. is used. Fig. 18 shows the results of composition evaluation using Auger electron spectroscopy.

Furthermore, when forming a half-tone mask, a resist process is first used to process the light-shielding layer and anti-reflection layer into the desired pattern through the steps of resist application, exposure, development, etching, and resist removal. When using a light-shielding film whose main component is chromium, a mixture of ceric ammonium nitrate and perchloric acid is typically used as the etching solution.

Then, a halftone layer is formed. Here, as with the light-shielding layer and anti-reflection layer, a film with a predetermined composition ratio of chromium, oxygen, nitrogen, carbon, etc. is formed, as shown in Figures 18 to 22. This can be formed using a reactive sputtering method. Figure 19 shows the ratio values in the film thickness direction based on data from composition evaluation using Auger electron spectroscopy.

Next, the halftone layer is also processed into a halftone pattern by similarly using a resist process, which involves resist application, exposure, development, etching, and resist removal.
After processing the chromium-containing film that will become the halftone pattern, the resist film is peeled off, thereby completing the process of processing the light-shielding film, anti-reflection film, and halftone film.

As mentioned above, top-mounted half-tone masks M require at least two patterning processes using resist. During the second patterning process, the half-tone film and binary film, which are chrome films of the same type, are simultaneously processed with the same etching and cleaning solutions. If the etching rates of the half-tone film and binary film differ, the cross-sectional shape of the pattern, i.e., the unevenness of the pattern edge surfaces that stand out from the glass substrate, becomes significant. This can lead to inaccurate pattern width dimensions, potentially making it impossible to form high-resolution patterns.

To prevent the occurrence of such irregularities, the difference in etching rate between halftone films and binary films must be reduced. Specifically, it is necessary to find a way to reduce the etching rate of halftone films, which tend to have a high etching rate. However, in photomasks, the optical properties of each layer are preset for a specific exposure light, making it difficult to change these.

Furthermore, flat halftone films in which the wavelength dependency of the transmittance of the halftone layer 13 is reduced are becoming increasingly important.
In the exposure process of the panel in the FPD, the processing speed of the exposure is very important, so in the exposure process, light of multiple wavelengths is used, unlike in the exposure process for semiconductors.

Generally, exposure is performed using light from a high-pressure mercury lamp, which has strong bright line spectra of g-line (436 nm), h-line (405 nm), and i-line (365 nm). Furthermore, in order to accommodate high-definition processing, the simultaneous use of light of shorter wavelengths, specifically, 312 nm from a low-pressure mercury lamp, has been considered recently. Furthermore, it is desirable that the transmittance at these wavelengths be as close as possible to each other.
Up until now, it has been common to use metallic chromium films that are relatively little oxidized as halftone films.

However, it was discovered that when such a chrome film is used as a half-tone film, the following problems arise. The problem is that the variation in transmittance is too great for light of around 312 nm, which is a shorter wavelength than conventional light, making it impossible to use as a half-tone film as is. Furthermore, the difference in etching rate is too great, to the extent that the occurrence of the aforementioned unevenness cannot be ignored.

The inventors have been able to provide a halftone mask that can suppress the occurrence of unevenness by increasing the amount of carbon contained in the halftone film, achieving a predetermined distribution in the film thickness direction, and further by forming the film so that the ratio distribution with other elements is in a predetermined state.

In other words, to resolve the situation where transmittance is highly dependent on wavelength and the occurrence of unevenness cannot be ignored, in this embodiment, the carbon concentration of the halftone film is increased to appropriately control the carbon content ratio at the surface, and the carbon content ratio at the boundary with the binary film in the depth direction of the halftone film is set within a predetermined range, thereby improving the suppression of unevenness while keeping the wavelength dependence of transmittance below a certain level.

Hereinafter, examples of the present invention will be described.
Here, a confirmation test performed as a specific example of the halftone layer in the present invention will be described.

<Experimental Example 1>
In Experimental Example 1, a half-tone film was laminated on a binary film having the same composition ratio as a conventionally used binary film. The film formation conditions are as follows:

・Light-shielding film: sputtering film (interback type)
Film formation gas: _N2, NO, Ar, Ar methane mixed gas Target: Cr
By adjusting the power supply Anti-reflection film: Sputter deposition (inter-back type)
Film forming gas: CO ₂ , N ₂
Target: Cr
(due to power supply adjustment)

Halftone film: sputter deposition (interback method)
Film formation gas: _N2 , Ar, Ar-methane mixed gas, _CO2
Target: Cr
(due to power supply adjustment)

The compositions of the formed binary film and halftone film were evaluated using Auger electron spectroscopy.
The results are shown in Figure 19.

The following ratios were calculated from the Auger electron spectroscopy data:
Average value of C/Cr ratio in the film thickness direction in half-tone 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 Figure 20.
Here, it can be seen that C/Cr has a mountain-like waveform in the film thickness direction with its peak near the boundary between the halftone film and the binary film.

The following ratios were calculated from the Auger electron spectroscopy data:
Average value of C/N ratio in the film thickness direction of halftone film: 0.60
The results are shown in Figure 21.
Here, it can be seen that the C/N ratio has a mountain-like waveform in the film thickness direction, with the peak near the boundary between the halftone film and the binary film.

The following ratios were calculated from the Auger electron spectroscopy data:
Average value of N/Cr ratio in the film thickness direction in halftone film: 0.52
The results are shown in Figure 22.

・Patterning resist: Resist type GRX-M237
Film thickness: 735 nm
Pre-bake 87℃ 48min
Exposure: Contact exposure machine (Tamarack)
Development: DIP type developer AZ DEVELOPER (50% diluted with pure water)
Development time: 30 seconds longer than specified Etching: Paddle type Etching solution: MPM-E
Etching time: 20 seconds longer than specified

The cross sections of the patterned binary film and halftone film were observed, and the SEM images are shown in Figure 23.
This image shows that there are few irregularities at the pattern end faces, that is, the etching rate in the halftone layer is not so different from that in the binary layer, and it is not the case that only the halftone layer is etched.

Furthermore, the following dimension α was calculated from this 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 furthest from the glass substrate in the thickness direction is the edge line, α is the maximum dimension by which the edge face (side face/wall face) of the mask pattern, which is erected with the edge line as the upper end and the glass substrate surface as the lower end, protrudes from the edge line of the outermost surface in a direction perpendicular to the edge line 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 starting point is the contour line of the contour shape that will be the end of the patterning, and α is the maximum value of the distance dimension from the starting point in the direction along the glass substrate surface at the patterning end face (the wall surface erected from the glass substrate surface).
FIG. 24 is an explanatory diagram for the definition of the dimension α.
α in this experimental example: 26 nm

<Experimental Example 2>
In Experimental Example 2, a half-tone film having the same composition ratio as the conventional half-tone film was laminated on a binary film having the same composition ratio as the conventional binary film. The film formation conditions are as follows:

・Light-shielding film: sputtering film formation (in-line type)
(An in-line type film forming apparatus, which has a different film forming method from that in Experimental Example 1, was used.)
Film-forming gas: _N2, NO, Ar, Ar-methane mixed gas (gas flow rates were set higher for Ar and Ar-methane mixed gas than in Experimental Example 1).
Target: Cr
(The supplied power was increased compared to Experimental Example 1.)
・Anti-reflective coating: Sputtering coating (in-line type)
(An in-line type film forming apparatus, which has a different film forming method from that in Experimental Example 1, was used.)
Film-forming gas: CO ₂ , N ₂ , Ar
(The gas flow rate settings were such that Ar was added, _CO2 was reduced, and _N2 was increased compared to Experimental Example 1.)
Target: Cr
(The power supply was set to be larger than that in Experimental Example 1.)

Halftone film: sputtering (interback method)
Film formation gas: _N2 , Ar, Ar-methane mixed gas, _CO2
(The gas flow rates were set to be lower for Ar and _CO2 and higher for _N2 compared to Experimental Example 1.)
Target: Cr
(The power supply was smaller than that in Experimental Example 1.)

The compositions of the formed binary film and halftone film were evaluated using Auger electron spectroscopy.
The results are shown in Figure 25.

The following ratios were calculated from the Auger electron spectroscopy data:
Average value of C/Cr ratio in the film thickness direction in 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 Figure 26.

The following ratios were calculated from the Auger electron spectroscopy data:
Average value of C/N ratio in the film thickness direction of halftone film: 0.21
The results are shown in Figure 27.

The following ratios were calculated from the Auger electron spectroscopy data:
Average value of N/Cr ratio in the film thickness direction in half-tone film: 0.67
The results are shown in Figure 28.

・Patterning resist: Resist type GRX-M237
Film thickness: 735 nm
Pre-bake 87℃ 48min
Exposure: Contact exposure machine (Tamarack)
Development: DIP type developer AZ DEVELOPER (50% diluted with pure water)
Development time: 30 seconds longer than specified Etching: Paddle type Etching solution: MPM-E
Etching time: 20 seconds longer than specified

The cross sections of the patterned binary film and halftone film were observed, and the SEM images are shown in Figure 29.
This image shows that unevenness occurs at the pattern end face, that is, the etching rate in the halftone layer is higher than that in the binary layer, and only the halftone layer is significantly etched.

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

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

・Light-shielding film: sputtering film formation (in-line type)
(An in-line type film forming apparatus, which has a different film forming method from that in Experimental Example 1, was used.)
Film-forming gas: _N2, NO, Ar, Ar-methane mixed gas (gas flow rate settings were the same as in Experimental Example 2).
Target: Cr
The power supply was the same as in Experimental Example 2.
・Anti-reflective coating: Sputtering coating (in-line type)
(An in-line type film forming apparatus, which has a different film forming method from that in Experimental Example 1, was used.)
Film-forming gas: CO ₂ , N ₂ , Ar
(The gas flow rate was set to the same as in Experimental Example 2.)
Target: Cr
(The power supply was the same as in Experimental Example 2.)

Halftone film: sputtering (interback method)
Film formation gas: _N2 , Ar, Ar-methane mixed gas, _CO2
(The gas flow rates were set so that Ar and _CO2 were less and _N2 was more than in Experimental Example 1, and so that _N2 was less and _CO2 was more than in Experimental Example 2.)
Target: Cr
(The supplied power was set to be larger than that in Experimental Example 2.)

Similarly, the ratios based on composition evaluation were determined using Auger electron spectroscopy in this experimental example, and the results are shown in Figure 31. In particular, the composition ratios of the halftone film, which forms the boundary with the anti-reflection film, are also shown.
Similarly, the dimension α in the experimental example was determined, and the results are shown in Figure 31. In Figure 31, the halftone film is abbreviated as HT.

<Experimental Example 4>
In Experimental Example 4, a binary film and a halftone film were formed in the same manner as in Experimental Example 2. The film formation conditions are as follows:

・Light-shielding film: sputtering film (interback type)
Film formation gas: _N2, NO, Ar, Ar-methane mixed gas (gas flow rate settings were the same as in Experimental Example 1).
Target: Cr
(The power supply was the same as in Experimental Example 1.)
・Anti-reflective coating: Sputter deposition (inter-back type)
Film forming gas: CO ₂ , N ₂
(The gas flow rate was set to the same as in Experimental Example 1.)
Target: Cr
(The power supply was the same as in Experimental Example 1.)

Halftone film: sputtering (interback method)
Film formation gas: _N2 , Ar, Ar-methane mixed gas, _CO2
(The gas flow rate was set to be _higher than that of Experimental Example 1.)
Target: Cr
(The supplied power was set to be larger than that in Experimental Example 1.)

Similarly, the ratios were determined based on composition evaluation using Auger electron spectroscopy in this experimental example, and the results are shown in Figure 31. In particular, the composition ratios of the halftone film, which forms the boundary with the anti-reflection film, are also shown.
Similarly, the dimension α in the experimental example was determined, and 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. The wavelengths of light used to measure 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 Figures 31 and 32.

These results show that in the halftone mask of the present invention, side etching of the halftone layer portion is not as great as that of the binary portion, preventing the interface between the resist and the halftone layer from becoming embedded and causing the binary portion to protrude. In other words, in the halftone mask of the present invention, the difference in etching rate of the halftone layer portion relative to the binary portion is reduced, demonstrating superior pattern cross-sectional verticality compared to conventional combinations of halftone and binary films.

Furthermore, as masks become more highly precise, the exposure wavelength range has become 312 nm to 436 nm, and there is a demand for even shorter wavelengths. However, in the halftone mask of the present invention, these results show that the halftone layer does not have a lower transmittance for light of such short wavelengths of 365 nm or less than the transmittance for light of other wavelengths, and it is possible to suppress the amount of change in the exposure wavelength range that is expanded to the shorter wavelengths.
This makes it possible for the halftone mask of the present invention to be suitably applied to an overlay halftone mask for a higher-definition FPD.

MB...Mask blank M...Half-tone mask M1...Transmitting area M2...Half-tone area M3...Light-shielding area S...Glass substrate (transparent substrate)
PR1, PR2... photoresist layers PR1p, PR2p... photoresist patterns 11... light-shielding layer 11p, 11p0... light-shielding patterns 12... anti-reflection layer 12p, 12p0... anti-reflection patterns 13... half-tone layer 13p... half-tone patterns

Claims (7)

A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising as a mask layer,
the halftone layer contains carbon, and the average value of the ratio of carbon to chromium, C/Cr, is set in the range of 0.26 to 0.34 ;
the anti-reflective layer contains carbon;
the halftone layer contains carbon, and a C/Cr ratio of carbon to chromium at the boundary with the antireflection layer is set in the range of 0.42 to 0.59;
A mask blank characterized by: A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising 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 to a range of 0.26 to 0.34;
the halftone layer contains nitrogen, and an average C/N ratio, which is a ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63;
A mask blank characterized by : A transparent substrate;
a light-shielding layer containing chromium as a main component laminated on the surface of the transparent substrate;
an anti-reflection layer containing chromium as a main component and laminated on the light-shielding layer;
a halftone layer containing chromium as a main component and laminated on the anti-reflection layer;
A mask blank comprising as a mask layer,
the halftone layer contains carbon, and the average value of the ratio of carbon to chromium, C/Cr, is set in the range of 0.26 to 0.34;
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;
A mask blank characterized by : the halftone layer contains nitrogen, and an average C/N ratio, which is a ratio of carbon to nitrogen, is set in the range of 0.55 to 0.63;
2. The mask blank according to claim 1 . 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;
3. The mask blank according to claim 1 or 2 . A half-tone mask manufactured from the mask blank according to any one of claims 1 to 5 ,
the halftone layer has a transmittance difference of less than 0.5% between exposure light having a wavelength of 436 nm and exposure light having a wavelength of 312 nm;
A half-tone mask characterized by: the mask layer is removed by patterning to have a mask pattern whose contour line is an edge of the outermost surface that is furthest from the transparent substrate in a thickness direction;
The halftone mask according to claim 6, characterized in that the end face of the mask pattern, which is erected with the contour line as its upper end and the transparent substrate surface as its lower end, has a maximum dimension α protruding from the contour line of the end of the outermost surface in a direction perpendicular to the contour line and along the outermost surface, which is less than 50 nm.