JP2016018192A - Mask blank, phase shift mask, manufacturing method of phase shift mask and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask blank having a phase shift film having high resistance to an exposure light of ArF excimer laser and easy to detect etching endpoint for detecting a boundary with a transparent substrate when conducting EB defect correction.SOLUTION: The mask blank has a phase shift film having one pair or more of combination of laminate structures of low transmission layer and high transmission layer on a transparent substrate, the phase shift film has a function transmitting an exposure light of ArF excimer laser at a predetermined transmission coefficient and generating predetermined phase difference, the low transmission layer and the high transmission layer are formed by a material consisting of silicon and nitrogen or a material containing one or more elements selected from semi-metallic element, non-metallic element and inert gas, the phase shift film has a bottom layer at a position contacting the transparent substrate, the bottom layer contains silicon and nitrogen and is formed by a material containing substantially no metal nor oxygen and having a percentage of the content of silicon to the total content of silicon and nitrogen of 50% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mask blank, a phase shift mask manufactured using the mask blank, and a manufacturing method thereof. The present invention also relates to a method of manufacturing a semiconductor device using the phase shift mask.

  In the manufacturing process of a semiconductor device, a fine pattern is formed using a photolithography method. A transfer mask is used in the transfer process of the fine pattern in the photolithography method. In recent years, with the demand for miniaturization of semiconductor devices, a halftone phase shift mask (hereinafter simply referred to as a phase shift mask) has been put to practical use as one of transfer masks. The phase shift mask is obtained by using a mask blank in which a phase shift film is provided as a thin film on the main surface of a light-transmitting substrate as an intermediate, and forming a transfer pattern on the phase shift film of the mask blank.

  A molybdenum silicide (MoSi) -based material is widely used for the phase shift film of the halftone phase shift mask. However, as disclosed in Patent Document 1, it has recently been found that MoSi-based films have low resistance to ArF excimer laser exposure light (so-called ArF light resistance). In Patent Document 1, plasma treatment, UV irradiation treatment, or heat treatment is performed on the MoSi-based film after the pattern is formed, and a passive film is formed on the surface of the MoSi-based film pattern. Sexuality is enhanced. Patent Document 2 discloses a phase shift mask including a phase shift film made of SiNx.

On the other hand, in Patent Document 3, the black defect portion of the light shielding film is removed by etching the black defect portion by supplying xenon difluoride (XeF ₂ ) gas to the black defect portion and irradiating the portion with an electron beam. (Hereinafter, defect correction performed by irradiating charged particles such as an electron beam is simply referred to as EB defect correction). This EB defect correction was originally used for correcting black defects in the absorber film of a reflective mask for EUV lithography, but in recent years, it has also been used for correcting black defects in MoSi halftone masks.

JP 2010-217514 A Japanese Patent Laid-Open No. 8-220731 JP-T-2004-537758

  The method for improving ArF light resistance for forming a passive film on the surface of a pattern formed of a MoSi-based film in Patent Document 1 does not change even the internal structure of the MoSi-based film. That is, it can be said that the ArF light resistance is equivalent to the conventional one in the MoSi-based film. For this reason, it is necessary to form a passivation film not only on the upper surface layer of the MoSi-based film pattern but also on the surface layer of the side wall. In Patent Document 1, after a pattern is formed on a MoSi-based film, a passive film is formed by performing plasma treatment, UV irradiation treatment, or heat treatment. However, the pattern formed on the MoSi-based film has a large in-plane density difference, and the distance between the side walls of adjacent patterns is often greatly different. Therefore, there is a problem that it is not easy to form a passive film having the same thickness on the sidewalls of all patterns.

On the other hand, although it is a film made of SiN _x that does not contain a transition metal as described in Patent Document 2, an ArF excimer laser is irradiated for a long time on a pattern formed on this SiN _x film. As a result, the change in pattern width (thickness) was very small compared to the transition metal silicon-based material film, and it was confirmed by the present inventors that the film has high ArF light resistance.

However, when SiN _x is applied to a material for forming a halftone phase shift film (hereinafter simply referred to as “phase shift film”) in a mask blank, it has become clear that there are the following problems. When a black defect is found in the phase shift film in the mask inspection when the phase shift mask is manufactured from the mask blank, it is often corrected by EB defect correction. When the black defect of the phase shift film to which SiN _x is applied is corrected by EB defect correction, the etching end point detection for detecting the boundary between the phase shift film and the translucent substrate is a single layer made of MoSiN. It was newly found that it is difficult compared to the phase shift film of the structure.

  Therefore, the present invention has been made to solve the above-mentioned problems, and in a mask blank in which a silicon-based material that does not contain a transition metal is applied as a material of the phase shift film, the phase shift film at the time of EB defect correction and An object of the present invention is to provide a mask blank in which detection of an etching end point for detecting a boundary with a light-transmitting substrate is relatively easy. Another object of the present invention is to provide a phase shift mask manufactured using such a mask blank. Furthermore, the present invention aims to provide a method for manufacturing such a phase shift mask. An object of the present invention is to provide a method of manufacturing a semiconductor device using such a phase shift mask.

In order to achieve the above object, the present invention has the following configuration.
(Configuration 1)
A mask blank provided with a phase shift film on a translucent substrate,
The phase shift film has a function of transmitting the exposure light of the ArF excimer laser at a predetermined transmittance, and exposure light that has passed through the air by the same distance as the thickness of the phase shift film with respect to the exposure light that has passed through the phase shift film. And a function of causing a predetermined phase difference between
The phase shift film has at least one combination of a laminated structure of a low transmission layer and a high transmission layer,
The low-permeability layer and the high-permeability layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a nonmetal element, and a rare gas in the material,
The phase shift film has a lowermost layer at a position in contact with the translucent substrate,
The lowermost layer is formed of a material containing silicon and nitrogen, substantially free of metal and oxygen, and a ratio of nitrogen content to the total content of silicon and nitrogen being 50% or more. A mask blank characterized by

(Configuration 2)
A mask blank provided with a phase shift film on a translucent substrate,
The phase shift film has a function of transmitting the exposure light of the ArF excimer laser at a predetermined transmittance, and exposure light that has passed through the air by the same distance as the thickness of the phase shift film with respect to the exposure light that has passed through the phase shift film. And a function of causing a predetermined phase difference between
The phase shift film has at least one combination of a laminated structure of a low transmission layer and a high transmission layer,
The low-permeability layer and the high-permeability layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a nonmetal element, and a rare gas in the material,
The phase shift film has a lowermost layer at a position in contact with the translucent substrate,
A mask blank, wherein the lowermost layer is formed of a material containing metal and silicon.

(Configuration 3)
3. The mask blank according to Configuration 2, wherein the lowermost layer is made of a material that does not substantially contain oxygen.
(Configuration 4)
4. The mask blank according to Configuration 2 or 3, wherein the lowermost layer has a ratio of the metal content to the total content of metal and silicon of 5% or more.

(Configuration 5)
5. The mask blank according to any one of configurations 2 to 4, wherein the lowermost layer has a ratio of the metal content to the total content of metal and silicon of 15% or less.
(Configuration 6)
6. The mask blank according to any one of configurations 2 to 5, wherein the lowermost layer is formed of a material made of metal, silicon, and nitrogen.

(Configuration 7)
The mask blank according to any one of configurations 1 to 6, wherein the lowermost layer has a thickness of 2 nm or more.
(Configuration 8)
The mask blank according to any one of configurations 1 to 7, wherein the low transmission layer has a relatively low nitrogen content compared to the high transmission layer.

(Configuration 9)
The mask blank according to any one of configurations 1 to 8, wherein the low transmission layer and the high transmission layer are made of the same constituent element.
(Configuration 10)
The mask blank according to any one of configurations 1 to 9, wherein the highly permeable layer has a ratio of nitrogen content to a total content of silicon and nitrogen of 50% or more.

(Configuration 11)
The mask blank according to any one of configurations 1 to 10, wherein the low transmission layer and the high transmission layer are formed of a material made of silicon and nitrogen.
(Configuration 12)
12. The mask blank according to any one of configurations 1 to 11, wherein the phase shift film has two or more combinations of laminated structures of a high transmission layer and a low transmission layer.

(Configuration 13)
The phase shift film is selected from a material consisting of silicon and oxygen, a material consisting of silicon, nitrogen and oxygen, or a semi-metallic element, a non-metallic element, and a rare gas at a position farthest from the translucent substrate. 13. The mask blank according to any one of configurations 1 to 12, wherein the mask blank has an uppermost layer formed of any of materials containing one or more elements.
(Configuration 14)
14. A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to any one of Structures 1 to 13.

(Configuration 15)
A step of dry-etching the phase shift film of the mask blank according to any one of Configurations 1 to 13 to form a transfer pattern;
A step of performing mask defect inspection on the phase shift film on which the transfer pattern is formed;
A step of supplying a fluorine-containing substance to the black defect portion of the phase shift film detected by the mask defect inspection and correcting the black defect portion by performing etching by irradiating charged particles. A method of manufacturing a phase shift mask characterized by the above.

(Configuration 16)
A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to Structure 14.
(Configuration 17)
A method for manufacturing a semiconductor device comprising a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask manufactured by the method for manufacturing a phase shift mask according to Structure 15.

  The mask blank of the present invention is a mask blank provided with a phase shift film on a translucent substrate, and the phase shift film has one or more combinations of laminated structures of a low transmission layer and a high transmission layer, The transmissive layer and the highly transmissive layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a non-metallic element, and a rare gas in the material. The lowermost layer has a lowermost layer at a position in contact with the optical substrate, and the lowermost layer is a material containing silicon and nitrogen, substantially free of metal and oxygen, and nitrogen relative to the total content of silicon and nitrogen. It is characterized by being formed of a material having a content ratio of 50% or more, or formed of a material containing metal and silicon. By using a mask blank having such a structure, the phase shift film can have high resistance to exposure light of an ArF excimer laser. In addition, this phase shift film can facilitate the detection of the etching end point for detecting the boundary between the phase shift film and the translucent substrate when EB defect correction is performed, and defect correction is insufficient. It can be avoided that the transparent substrate is dug unintentionally.

It is sectional drawing which shows the structure of the mask blank in embodiment of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the phase shift mask in embodiment of this invention. It is a schematic diagram for demonstrating the film-forming mode in the case of forming a thin film by reactive sputtering.

Hereinafter, each embodiment of the present invention will be described.
The inventors of the present invention have intensively studied a suitable configuration when SiN _x is applied as a material for forming a phase shift film of a mask blank. In general, the phase shift film transmits ArF exposure light at a predetermined transmittance (for example, 1% to 30%), and the same distance as the thickness of the phase shift film with respect to ArF exposure light transmitted through the phase shift film. It is necessary to have a function of causing a predetermined phase difference (for example, 150 to 190 degrees) with the light that has passed through the air.

When the phase shift film is formed as a single layer, it is necessary to use a material having a refractive index n with respect to ArF exposure light to a certain degree and a small extinction coefficient k to a certain degree. Silicon is a material that has a somewhat large extinction coefficient k for ArF exposure light, but has a tendency that the refractive index n is significantly small. When the phase shift film is formed of a silicon nitride-based material that does not contain a metal, since silicon is a material having a significantly lower refractive index n, nitrogen, which is an element that raises the refractive index, is replaced with nitrogen that is a conventional transition metal silicon-based material. Must also be included. Further, since a large amount of nitrogen tends to increase the transmittance of the phase shift film, the oxygen content in the phase shift film needs to be reduced as much as possible. As described above, when a phase shift film having a single layer structure is formed of a silicon nitride-based material that does not contain a transition metal such as SiN _x , there are more restrictions than before.

Generally, not only the phase shift film but also a thin film for forming a mask blank pattern is formed by a sputtering method. When a thin film is formed on a light-transmitting substrate by a sputtering method, it is usually performed to select conditions that allow relatively stable film formation. For example, when a SiN _x film is formed by sputtering, a Si target is placed in the film formation chamber, and a rare gas that has been made into plasma collides with the Si target while constantly circulating a mixed gas of a rare gas such as Ar and nitrogen. Thus, the Si particles that have jumped out are taken in the process of taking in nitrogen and depositing on the light-transmitting substrate (such sputtering is generally referred to as “reactive sputtering”). The nitrogen content of the SiN _x film is mainly adjusted by increasing / decreasing the mixing ratio of nitrogen in the mixed gas, which makes it possible to form SiNx films with various nitrogen contents on the translucent substrate. It has become.

  FIG. 3 shows a reactive gas mixture ratio in a mixed gas composed of a rare gas and a reactive gas (or a flow rate of the reactive gas in the mixed gas) when a thin film is formed by reactive sputtering. FIG. 2 is a graph schematically showing a general tendency with respect to a change in film forming speed that occurs when the ratio is changed. In FIG. 3, when the mixing ratio of the reactive gas in the mixed gas is gradually increased (increase mode), the curve I of the film formation rate change and the mixing ratio of the reactive gas in the mixed gas are gradually decreased. A curve D of the change in the film forming speed in the case of being reduced (decrease mode) is shown. In general, a region in which the mixing ratio of the reactive gas in the mixed gas is low (a region in the metal mode M in FIG. 3; hereinafter, a region having such a film forming condition is referred to as “metal mode”), and in the mixed gas. In the region where the mixing ratio of the reactive gas is high (region of reaction mode R in FIG. 3, the region under such film formation conditions is hereinafter referred to as “reaction mode” or “poison mode”). In both the reduction modes, the fluctuation range of the film formation rate accompanying the change in the reactive gas mixture ratio in the mixed gas is small. Further, the difference in film formation rate between the increasing mode and the decreasing mode in the mixing ratio of the reactive gas in the same mixed gas is also small. Therefore, a thin film can be stably formed in the metal mode M region and the reaction mode R region. That is, it can be said that the region of the metal mode M and the region of the reaction mode R are regions where the composition and optical characteristics are highly uniform and a thin film having a low defect can be formed.

  On the other hand, in the region of transition mode T sandwiched between the region of metal mode M and the region of reaction mode R in FIG. In both the reduction modes, the fluctuation range of the film forming rate with the change of the reactive gas mixture ratio in the mixed gas is large. In addition, the difference in deposition rate between the increase mode and the decrease mode in the mixing ratio of the reactive gas in the same mixed gas is large. In the region of the transition mode T, the film formation speed fluctuates greatly due to a minute change in the reactive gas mixture ratio in the mixed gas in the film formation chamber, and the shift from the increase mode to the decrease mode is caused by the minute change in the mixture ratio. The film forming speed fluctuates due to. For this reason, a thin film is formed in the state where the film-forming speed is unstable. Variation in the deposition rate affects the amount of reactive gas components contained in the thin film. That is, the region of the transition mode T is a region where the uniformity of the composition and optical characteristics is high and it is difficult to form a thin film with low defects.

  When the phase shift film to which ArF exposure light is applied is formed by reactive sputtering having a single layer structure made of a silicon nitride-based material film that does not contain a metal, the film is formed in the region of the transition mode T due to the required optical property restrictions. The need to do is high. There is also a method of searching for a combination of reactive gases having a small difference in film formation rate between the increasing mode and the decreasing mode in the transition mode T in the mixing ratio of the reactive gases in the same mixed gas. However, even if such a combination of reactive gases is found, the problem that the fluctuation range of the film forming speed due to the change in the mixing ratio of the reactive gas in the mixed gas in the transition mode T is not solved. .

  When forming a silicon nitride-based material film that does not contain a metal by reactive sputtering using a metal mode region, if the thickness of the film for obtaining a phase difference required as a phase shift film is to be secured, this formed film Since the extinction coefficient k of the material is high, it becomes lower than the required transmittance for ArF exposure light. Such a film hardly causes a phase shift effect and is not suitable for a phase shift film. On the other hand, when a silicon nitride-based material film that does not contain a metal is formed by reactive sputtering in a reaction mode region, this film is formed if an attempt is made to secure a film thickness for obtaining a phase difference required as a phase shift film. Since the extinction coefficient k of the film material is low, it becomes higher than the required transmittance for ArF exposure light. Although such a film can provide a phase shift effect, there is a possibility that the resist film on the semiconductor wafer may be exposed to transmitted light from a pattern portion other than the region where the phase shift effect occurs. Is not suitable.

As a result of earnestly researching means for solving many technical problems that occur in realizing a phase shift film suitable for ArF exposure light using a silicon nitride-based material film that does not contain a metal, it is formed by reactive sputtering in a metal mode region. We have come up with a phase shift film having a structure in which a low transmission layer, which is a silicon nitride material film, and a high transmission layer, which is a silicon nitride material film formed by reactive sputtering in a reaction mode region, are laminated. However, in the case of a mask blank to which such a phase shift film is applied, if a black defect is found in the phase shift film in the mask inspection when the phase shift mask is manufactured from the mask blank, a new technical problem arises. There was found.
In recent years, EB defect correction has been increasingly applied when correcting black defects. When correcting a black defect of a phase shift film having a structure in which a low transmission layer and a high transmission layer of a silicon-based material film are stacked, the boundary between the phase shift film and the translucent substrate is detected when the defect is corrected by EB defect correction. Therefore, it was newly found that the detection of the etching end point is difficult compared to a phase shift film having a single layer structure made of MoSiN.

  The present inventors are a phase shift film having a structure in which a low transmission layer and a high transmission layer of a silicon nitride-based material film not containing a metal are laminated, and when the correction is performed by correcting an EB defect Intensive research was conducted on a phase shift film that can easily detect the end point of etching for detecting the boundary between the substrate and the light-transmitting substrate.

  In EB defect correction, when an electron beam is irradiated to a black defect, at least one of Auger electrons, secondary electrons, characteristic X-rays, and backscattered electrons emitted from the irradiated portion is detected. The etching end point is detected by observing the change. For example, when detecting Auger electrons emitted from a portion irradiated with an electron beam, changes in material composition are mainly observed by Auger electron spectroscopy (AES). When detecting secondary electrons, the surface shape change is mainly observed from the SEM image. Furthermore, when detecting characteristic X-rays, changes in material composition are mainly observed by energy dispersive X-ray spectroscopy (EDX) and wavelength dispersive X-ray spectroscopy (WDX). When detecting backscattered electrons, changes in material composition and crystal state are mainly observed by electron beam backscatter diffraction (EBSD).

  In the case of a phase shift film having a single layer structure made of a metal silicide nitride typified by conventional MoSiN, the metal content is relatively small, but any etching end point detection method described above can be used in EB defect correction. The etching end point could be detected. The translucent substrate used for the mask blank is generally formed of a material mainly composed of silicon oxide. In the etching end point detection in the EB defect correction between the conventional phase shift film made of metal silicide nitride and the translucent substrate, silicon is an element that is commonly contained in the material forming both, This is done by observing changes in the detection intensity of other elements, particularly metal elements.

  However, between the phase shift film and the translucent substrate when EB defect correction is performed on a phase shift mask having a phase shift film pattern made of a silicon nitride-based material film not containing metal on the translucent substrate. In the etching end point detection, the determination is made by looking at the change from the decrease in the nitrogen detection intensity to the increase in the oxygen detection intensity as the etching progresses. However, although the processing chamber at the time of EB defect correction is almost in a vacuum state, detection of nitrogen and oxygen is still susceptible to disturbances and the like. In the case of a phase shift film of a metal silicide nitride, it is easy to obtain the detection intensity of a metal element at the time of EB defect correction even with a small metal content. However, in the case of a phase shift film of a silicon nitride material, a small amount of nitrogen With the content, it is difficult to obtain the detection intensity of nitrogen at the time of EB defect correction.

  As a result of further intensive research, the inventors of the present application have found that a phase shift film having one or more combinations of a laminated structure of a low-transmission layer and a high-transmission layer made of a silicon nitride-based material is positioned in contact with the translucent substrate. The lowermost layer is provided, and the lowermost layer is a material that contains silicon and nitrogen, does not contain metal and oxygen, and has a silicon content of 50% or more with respect to the total content of silicon and nitrogen. As a result, it was concluded that the etching end point between the phase shift film and the translucent substrate at the time of EB defect correction can be detected with sufficient sensitivity.

  The same effect can be obtained when the low-permeability layer and the high-permeability layer are formed of a material containing one or more elements selected from metalloid elements, non-metal elements, and rare gases in addition to silicon and nitrogen. I was able to confirm that. Therefore, the mask blank according to the first embodiment of the present invention includes a phase shift film on a translucent substrate, and the phase shift film has a function of transmitting ArF excimer laser exposure light with a predetermined transmittance. And a function of causing a predetermined phase difference between the exposure light transmitted through the phase shift film and the exposure light that has passed through the air by the same distance as the thickness of the phase shift film. Has one or more combinations of laminated structures of a low-permeability layer and a high-permeability layer, and the low-permeability layer and the high-permeability layer are made of a material composed of silicon and nitrogen, or a semi-metal element, a non-metal element, and a rare element. The phase shift film is formed of a material containing one or more elements selected from gases, and has a lowermost layer at a position in contact with the translucent substrate. The lowermost layer contains silicon and nitrogen, and contains metal and oxygen. Is a material that does not substantially contain And is characterized in that the ratio of the content of nitrogen to the total content of silicon and nitrogen is formed of a material is 50% or more.

  On the other hand, the inventors of the present application can detect the etching end point between the phase shift film and the translucent substrate at the time of EB defect correction with sufficient sensitivity by forming the lowermost layer with a material containing metal and silicon. It came to the conclusion that it will become detectable.

  That is, the mask blank according to the second embodiment of the present invention includes a phase shift film on a translucent substrate, and the phase shift film has a function of transmitting ArF excimer laser exposure light with a predetermined transmittance. And a function of causing a predetermined phase difference between the exposure light transmitted through the phase shift film and the exposure light that has passed through the air by the same distance as the thickness of the phase shift film. Has one or more combinations of laminated structures of a low-permeability layer and a high-permeability layer. The phase shift film is formed of a material containing one or more elements selected from gases, and the phase shift film has a lowermost layer at a position in contact with the translucent substrate, and the lowermost layer is formed of a material containing metal and silicon. It is characterized by having A.

  FIG. 1 is a cross-sectional view showing a configuration of a mask blank 100 according to the first and second embodiments of the present invention. A mask blank 100 of the present invention shown in FIG. 1 has a structure in which a phase shift film 2, a light shielding film 3, and a hard mask film 4 are laminated in this order on a translucent substrate 1.

The translucent substrate 1 can be formed of quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass or the like), in addition to synthetic quartz glass. Among these, synthetic quartz glass has a high transmittance with respect to ArF excimer laser light (wavelength 193 nm), and is particularly preferable as a material for forming a light-transmitting substrate of a mask blank.

  The phase shift film 2 in the mask blank of the present invention has a transmittance for exposure light (hereinafter referred to as ArF exposure light) having a wavelength of 200 nm or less, such as an ArF excimer laser, in order to make the phase shift effect function effectively. It is preferably 1% or more, and more preferably 2% or more. Further, the phase shift film is preferably adjusted so that the transmittance with respect to ArF exposure light is 30% or less, more preferably 20% or less, and further preferably 18% or less.

  In order to obtain an appropriate phase shift effect, the phase shift film 2 gives a predetermined phase difference between the transmitted ArF exposure light and the light that has passed through the air by the same distance as the thickness of the phase shift film 2. It is required to have a function to be generated. Moreover, it is preferable that the phase difference is adjusted to be in a range of 150 degrees to 190 degrees. The lower limit value of the phase difference in the phase shift film 2 is more preferably 160 degrees or more, and further preferably 170 degrees or more. On the other hand, the upper limit value of the phase difference in the phase shift film 2 is more preferably 180 degrees or less, and further preferably 179 degrees or less. The reason for this is to reduce the influence of an increase in phase difference caused by minute etching of the translucent substrate 1 during dry etching when forming a pattern on the phase shift film 2. Further, in recent years, ArF exposure light is applied to the phase shift mask by an exposure apparatus, and the number of ArF exposure light incident from a direction inclined at a predetermined angle with respect to the direction perpendicular to the film surface of the phase shift film 2 is increasing. It is because it is.

  The phase shift film 2 has a structure in which a lowermost layer 24, a low transmission layer 21, a high transmission layer 22, and an uppermost layer 23 are laminated from the translucent substrate 1 side. The lowermost layer 24 is provided at a position in contact with the surface of the translucent substrate 1. In the first embodiment, the lowermost layer 24 is a material containing silicon and nitrogen, substantially free of metal and oxygen, and the ratio of the content of silicon to the total content of silicon and nitrogen is 50%. It is formed with the material which is the above.

  The lowermost layer 24 of the first embodiment uses a material that does not substantially contain a metal in order to eliminate as much as possible an element that decreases the light resistance to ArF exposure light. For this reason, at the time of EB defect correction, it becomes difficult to detect the interface (etching end point) between the lowermost layer 24 and the translucent substrate 1. In order to have a difference from the elemental structure with silicon oxide, which is the main component of the material forming the translucent substrate 1, the lowermost layer 24 of the first embodiment is a material that does not substantially contain oxygen. And the ratio of the nitrogen content [atomic%] to the total content of silicon and nitrogen [atomic%] (that is, the nitrogen content [atomic%] is divided by the total content of silicon and nitrogen [atomic%]. Hereinafter, this ratio is referred to as “N / [N + Si] ratio”). By adopting such a configuration, the detection intensity of nitrogen when the lowermost layer 24 is etched is greatly increased. And it becomes easy to catch the change in the detected intensity of nitrogen in the course of changing the etching target from the lowermost layer 24 to the translucent substrate 1.

  The lowermost layer 24 of the first embodiment is a material composed of silicon and nitrogen, and a material having a ratio of silicon content to the total content of silicon and nitrogen (N / [N + Si] ratio) of 50% or more. Is preferably formed. This is because it becomes easier to detect the etching end point between the lowermost layer 24 and the translucent substrate 1 when the EB defect is corrected. The N / [N + Si] ratio in the material forming the lowermost layer 24 of the first embodiment is more preferably 52% or more. On the other hand, the N / [N + Si] ratio of the material formed by the lowermost layer 24 of the first embodiment is preferably 57% or less, and more preferably 55% or less.

  Here, the material substantially not containing oxygen is a material having an oxygen content in the material of at least 5 atomic% or less (the same applies to the lowermost layer 24 of the second embodiment described later). The oxygen content of the material formed by the lowermost layer 24 of the first embodiment is preferably 3 atomic% or less, and more preferably lower than the detection lower limit when composition analysis is performed by X-ray photoelectron spectroscopy or the like. preferable. The lowermost layer 24 of the first embodiment may contain any nonmetallic element other than oxygen. Among these nonmetallic elements, it is preferable to include one or more elements selected from carbon, fluorine and hydrogen. Further, the lowermost layer 24 of the first embodiment may contain a metalloid element and a rare gas. Among these metalloid elements, it is preferable to include one or more elements selected from boron, germanium, antimony, and tellurium because it can be expected to increase the conductivity of silicon used as a sputtering target.

  On the other hand, in the second embodiment, the lowermost layer 24 is formed of a material containing metal and silicon. From the viewpoint of light resistance to ArF exposure light, it is desirable that all the layers of the phase shift film 2 do not contain a metal. If only the lowermost layer 24 has a small thickness ratio as viewed from the total thickness of the phase shift film, even if it is allowed to contain a metal, the influence on the light resistance against ArF exposure light is small. In this second embodiment, by forming only the lowermost layer 24 with a material containing metal and silicon, it is easy to detect the interface (etching end point) between the lowermost layer 24 and the translucent substrate 1 at the time of EB defect correction. doing.

  The metal element contained in the material forming the lowermost layer 24 in the second embodiment is preferably a transition metal element. As transition metal elements in this case, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V), zirconium One or more metal elements may be mentioned among (Zr), ruthenium (Ru), rhodium (Rh), zinc (Zn), niobium (Nb) and palladium (Pd). In addition, examples of the metal element other than the transition metal element to be included in the material forming the lowermost layer 24 in the second embodiment include aluminum (Al), indium (In), tin (Sn), and gallium (Ga). Can be mentioned.

  In addition to the above elements, the material forming the lowermost layer 24 in the second embodiment includes elements such as carbon (C), hydrogen (H), boron (B), germanium (Ge), and antimony (Sb). May be included. In addition, the material forming the lowermost layer 24 in the second embodiment may include an inert gas such as helium (He), argon (Ar), krypton (Kr), and xenon (Xe).

  The lowermost layer 24 of the second embodiment is preferably formed of a material that does not substantially contain oxygen, similarly to the lowermost layer 24 of the first embodiment. This makes it easier to detect the etching end point. Moreover, it is preferable that the lowermost layer 24 of 2nd Embodiment is formed with the material which consists of a metal, silicon, and nitrogen. This is because it becomes easier to detect the etching end point.

  The material forming the lowermost layer 24 of the second embodiment is a ratio of the metal content [atomic%] to the total content [atomic%] of metal and silicon (that is, the metal content [atomic%] is changed to metal And the ratio divided by the total content [atomic%] of silicon, which is hereinafter referred to as “M / [M + Si] ratio”) is preferably 5% or more. Thereby, the detection intensity of the metal when the lowermost layer 24 is etched can be secured, and the interface (etching end point) between the lowermost layer 24 and the translucent substrate 1 can be easily detected. In addition, when the phase shift film 2 is patterned by dry etching using a fluorine-based gas, it becomes easy to ensure etching selectivity with the light-transmitting substrate 1. The M / [M + Si] ratio of the lowermost layer 24 of the second embodiment is preferably 6% or more, and more preferably 7% or more.

  The M / [M + Si] ratio in the material forming the lowermost layer 24 of the second embodiment is required to be at least 15% or less. If the M / [M + Si] ratio of the lowermost layer 24 is larger than 15%, the extinction coefficient k of the lowermost layer 24 becomes too high, and the transmittance and phase difference with respect to ArF exposure light in the entire phase shift film 10 are increased. It becomes difficult to adjust to achieve both. Moreover, the tolerance with respect to the integrated irradiation of the ArF exposure light in the lowermost layer 24 of 2nd Embodiment also falls. The M / [M + Si] ratio in the material forming the lowermost layer 24 is preferably 12% or less, and more preferably 10% or less.

  The N / [N + Si] ratio of the material formed by the lowermost layer 24 of the second embodiment is preferably 15% or more, more preferably 20% or more, and further preferably 30% or more. On the other hand, the N / [N + Si] ratio of the material formed by the lowermost layer 24 of the second embodiment is preferably 57% or less, and more preferably 55% or less.

  The refractive index n of the lowermost layer 24 of the second embodiment is preferably 2.25 or more, and more preferably 2.35 or more. Further, the refractive index n of the lowermost layer 24 is preferably 2.60 or less, and more preferably 2.50 or less. The extinction coefficient k of the lowermost layer 24 is preferably 0.35 or more, and more preferably 0.45 or more. Further, the extinction coefficient k of the lowermost layer 24 is preferably 0.75 or less, and more preferably 0.65 or less.

  The refractive index n and extinction coefficient k of a thin film are not determined only by the composition of the thin film. The film density and crystal state of the thin film are factors that influence the refractive index n and the extinction coefficient k. For this reason, various conditions when forming a thin film by reactive sputtering are adjusted, and the thin film is formed so as to have a desired refractive index n and extinction coefficient k. In the method of setting the lowermost layer 24 of the second embodiment within the range of the above-mentioned refractive index n and extinction coefficient k, when the film is formed by reactive sputtering, the ratio of the mixed gas of rare gas and reactive gas is set. It is not limited only to the adjustment method. There are a variety of positional relationships such as the pressure in the film formation chamber during reactive sputtering, the power applied to the target, and the distance between the target and the translucent substrate. These film forming conditions are unique to the film forming apparatus, and are appropriately adjusted so that the formed thin film has a desired refractive index n and extinction coefficient k. This also applies to the case of a low transmission layer 21 and a high transmission layer 22 described later.

  The lowermost layer 24 in the first and second embodiments has a thickness of 2 nm or more in order to exhibit a function of facilitating detection of an etching end point between the lowermost layer 24 and the light-transmitting substrate 1 at the time of EB defect correction. It is required to be. The lowermost layer 24 in the first and second embodiments is preferably 3 nm or more, and more preferably 5 nm or more. On the other hand, if the lowermost layer 24 is too thick, it is difficult to set the transmittance for ArF exposure light in the entire phase shift film 2 to 10% or less. Considering this point, the lowermost layer 24 in the first and second embodiments is required to have a thickness of 20 nm or less, preferably 15 nm or less, and more preferably 10 nm or less.

  The low transmissive layer 21 and the high transmissive layer 22 in the phase shift film 2 contain one or more elements selected from a semi-metallic element, a non-metallic element, and a rare gas in a material composed of silicon and nitrogen, or a material composed of silicon and nitrogen. It is made of a material that Further, the low transmission layer is formed of a material having a relatively small nitrogen content as compared with the high transmission layer. The low transmissive layer 21 and the high transmissive layer 22 do not contain a transition metal that may cause a decrease in light resistance to ArF exposure light. In addition, it is desirable that the low transmissive layer 21 and the high transmissive layer 22 do not contain any metal element other than the transition metal because the possibility that light resistance to ArF exposure light may be reduced cannot be denied. The low transmission layer 21 and the high transmission layer 22 may contain any metalloid element in addition to silicon. Among these metalloid elements, it is preferable to include one or more elements selected from boron, germanium, antimony, and tellurium because it can be expected to increase the conductivity of silicon used as a sputtering target.

  The low transmission layer 21 and the high transmission layer 22 may contain any nonmetallic element in addition to nitrogen. Among these nonmetallic elements, it is preferable to include one or more elements selected from carbon, fluorine and hydrogen. The low transmission layer 21 and the high transmission layer 22 preferably have an oxygen content of 10 atomic% or less, more preferably 5 atomic% or less, and do not actively contain oxygen (X-rays). More preferably, it is below the lower limit of detection when compositional analysis is performed by photoelectron spectroscopy. When oxygen is contained in the silicon nitride-based material film, the extinction coefficient k tends to be greatly reduced, and the entire thickness of the phase soft film 2 is increased. The order of stacking the low transmission layer 21 and the high transmission layer 22 from the light transmitting substrate 1 side in the phase shift film 2 may be any order.

  In the method for producing a mask blank of the present invention, the low-transmission layer 21 and the high-transmission layer 22 of the phase shift film 2 are a silicon target or a material containing one or more elements selected from semimetal elements and nonmetal elements in silicon. A low transmission layer forming step of forming a low transmission layer 21 on the translucent substrate 1 by reactive sputtering in a sputtering gas containing a nitrogen-based gas and a rare gas, and a silicon target or silicon A sputtering gas containing a nitrogen-based gas and a rare gas, using a target made of a material containing one or more elements selected from a metalloid element and a non-metal element. The high transmission layer 22 is formed on the translucent substrate 1 by reactive sputtering in a sputtering gas having a high mixing ratio. It is preferably formed by forming process.

  In a target composed of a material containing one or more elements selected from a metalloid element and a nonmetal element in silicon, it is preferable to include one or more elements selected from boron, germanium, antimony, and tellurium as the metalloid element. These metalloid elements can be expected to increase the conductivity of the target. Therefore, when forming a low-transmission layer and a high-transmission layer by DC sputtering, the target may contain these metalloid elements. desirable.

  The low transmission layer 21 and the high transmission layer 22 may contain a rare gas. A rare gas is an element that can increase the deposition rate and improve the productivity by being present in the deposition chamber when a thin film is formed by reactive sputtering. When the rare gas is turned into plasma and collides with the target, the target constituent element is ejected from the target, and a thin film is formed on the translucent substrate 1 while taking in the reactive gas in the middle. The rare gas in the film formation chamber is slightly taken in until the target constituent element jumps out of the target and adheres to the translucent substrate. Preferred examples of the rare gas required for the reactive sputtering include argon, krypton, and xenon. Moreover, in order to relieve the stress of the thin film, helium and neon having a small atomic weight can be actively incorporated into the thin film.

In the low transmission layer forming step for forming the low transmission layer 21 and the high transmission layer forming step for forming the high transmission layer 22, a nitrogen-based gas is included in the sputtering gas. As the nitrogen-based gas, any gas can be used as long as it contains nitrogen. As described above, the low-permeability layer 21 and the high-permeability layer 22 preferably have a low oxygen content. Therefore, it is preferable to apply a nitrogen-based gas that does not contain oxygen, and to apply a nitrogen gas (N ₂ gas). It is more preferable.

  In addition, the sputtering gas used in the low-permeability layer forming step is selected to have a nitrogen-based gas mixing ratio that is less than the range of the nitrogen-based gas mixing ratio that becomes a transition mode that tends to make the film formation unstable. As the sputtering gas used in the highly transmissive layer forming step, it is preferable to select a nitrogen gas mixing ratio that is greater than the range of the nitrogen gas mixing ratio in the transition mode.

  The low transmission layer 21 and the high transmission layer 22 preferably have a structure in which the low transmission layer 21 and the high transmission layer 22 are laminated in direct contact with each other without using another film. Moreover, it is preferable that it is a film | membrane structure where the film | membrane which consists of a material containing a metal element does not contact | connect neither the low permeable layer 21 and the high permeable layer 22 except the lowest layer 24 of 2nd Embodiment. This is because when a heat treatment or irradiation with ArF exposure light is performed in a state where a film containing a metal element is in contact with a film containing silicon, the metal element tends to diffuse into the film containing silicon.

  The low transmission layer 21 and the high transmission layer 22 are preferably made of the same constituent elements. When either the low transmission layer 21 or the high transmission layer 22 contains different constituent elements, and these layers are in contact with each other and are subjected to heat treatment or ArF exposure light irradiation, the different constituent elements are , There is a risk of moving and diffusing to the layer not containing the constituent elements. And there exists a possibility that the optical characteristic of the low transmissive layer 21 and the high transmissive layer 22 may change a lot from the beginning of film-forming. In particular, when the different constituent element is a metalloid element, the low transmission layer 21 and the high transmission layer 22 must be formed using different targets.

  The N / [N + Si] ratio of the material forming the highly transmissive layer 22 is preferably 50% or more, and more preferably 52% or more. Further, the nitrogen content of the material formed by the high transmission layer 22 is preferably 57% or less, and more preferably 55% or less. On the other hand, the N / [N + Si] ratio of the material forming the low transmission layer 21 is preferably 20% or more, more preferably 25% or more, and further preferably 30% or more. Further, the N / [N + Si] ratio of the material formed by the low transmission layer 21 is preferably 48% or less, and more preferably 45% or less.

  The low transmission layer 21 and the high transmission layer 22 are preferably formed of a material made of silicon and nitrogen. Further, in the method for producing a mask blank of the present invention, in the low transmission layer forming step, the silicon film is used to form the low transmission layer 21 by reactive sputtering in a sputtering gas composed of nitrogen gas and a rare gas. In the highly permeable layer forming step, the highly permeable layer 22 is preferably formed by reactive sputtering in a sputtering gas composed of a nitrogen gas and a rare gas using a silicon target.

  As described above, the inclusion of a transition metal in the low transmission layer 21 and the high transmission layer 22 can be a factor in reducing the light resistance to ArF exposure light. When the low permeable layer 21 and the high transmissive layer 22 contain a metal other than a transition metal or a metalloid element other than silicon, the contained metal or metalloid element is formed between the low transmissive layer 21 and the high transmissive layer 22. There is a possibility that the optical characteristics change with the movement between the two. Even in the case of a non-metallic element, if oxygen is contained in the low transmission layer 21 and the high transmission layer 22, the transmittance for ArF exposure light is greatly increased. Considering these matters, it is more preferable that the low-permeability layer 21 and the high-permeability layer 22 are formed of a material made of silicon and nitrogen. The rare gas is an element that is difficult to detect even if a composition analysis such as RBS or XPS is performed on the thin film. For this reason, it can be considered that the material containing silicon and nitrogen includes a material containing a rare gas.

  It is preferable that the phase shift film 2 has two or more sets of a laminated structure including one low transmission layer 21 and one high transmission layer 22. Moreover, it is preferable that the low permeable layer 21 and the high transmissive layer 22 have a thickness of 20 nm or less per layer. Since the required optical characteristics of the low transmission layer 21 and the high transmission layer 22 are greatly different, the difference in the nitrogen content in the film between them is large. For this reason, the difference in etching rate between the low-permeability layer 21 and the high-permeability layer 22 by dry etching with a fluorine-based gas is large. When the phase shift film has a two-layer structure composed of one low transmission layer 21 and one high transmission layer 22, the phase shift film 2 after etching is formed when a pattern is formed by dry etching using a fluorine-based gas. A step is likely to occur in the cross section of the pattern. By making the phase shift film 2 into a structure having two or more sets of one layered structure composed of one layer of the low transmission layer 21 and one layer of the high transmission layer 22, the low transmission layer 21 and the high transmission layer 22 Since the thickness of each layer (one layer) is smaller than that in the case of the two-layer structure (one set of stacked structures), the step generated in the cross section of the phase shift film pattern after etching can be reduced. Further, by limiting the thickness of each layer (one layer) in the low transmission layer 21 and the high transmission layer 22 to 20 nm or less, a step generated in the cross section of the pattern of the phase shift film 2 after etching can be further suppressed. .

In EB defect correction, a non-excited substance such as XeF ₂ is gasified and supplied to the black defect portion, and the black defect portion is irradiated with an electron beam, thereby converting the thin film of the black defect portion into a volatile fluoride. It is a technology to remove by changing. Conventionally, since a fluorine-based gas such as XeF ₂ used for EB defect correction is supplied in an unexcited state, it has been considered that a portion of a thin film not irradiated with an electron beam is hardly affected. However, it has been found that when the mask blank thin film is formed of a silicon-based compound, if the oxygen or nitrogen content is low, the mask blank is etched by a non-excited fluorine-based gas such as XeF ₂ . .

Since the low transmission layer 21 of the phase shift film 2 in the present invention is a silicon-based material film that has a relatively low nitrogen content and does not actively contain oxygen, an unexcited state such as XeF ₂ at the time of correcting this EB defect It tends to be easily etched by the fluorine-based gas. For this reason, it is desirable to place the low-permeability layer 21 in a state in which non-excited fluorine-based gas such as XeF ₂ is difficult to contact. On the other hand, since the highly permeable layer 22 is a silicon-based material film having a high nitrogen content, it is unlikely to be affected by a non-excited fluorine-based gas such as XeF ₂ . As described above, the phase shift film 2 has a structure having two or more combinations of the laminated structures of the low transmission layer 21 and the high transmission layer 22 so that the low transmission layer 21 is between the two high transmission layers 22. Or a state of being sandwiched between the lowermost layer 24 and the highly transmissive layer 22. As a result, the fluorine-based gas in an unexcited state such as XeF ₂ may initially contact and etch the low-permeability layer 21, but thereafter, it is difficult to contact the low-permeability layer 21 (low-permeability layer 21). (Since the surface of the side wall of the layer 21 is more intricate than the surface of the side wall of the highly permeable layer 22, gas is less likely to enter.) Therefore, with such a stacked structure, it is possible to suppress the low transmission layer 21 from being etched by a non-excited fluorine-based gas such as XeF ₂ . Further, by limiting the thickness of each layer in the low transmission layer 21 and the high transmission layer 22 to 20 nm or less, the low transmission layer 21 is further suppressed from being etched by a non-excited fluorine-based gas such as XeF _2. be able to.

  The low transmission layer 21 has a refractive index n with respect to ArF exposure light of less than 2.5 (preferably 2.4 or less, more preferably 2.2 or less, and further preferably 2.0 or less), and an extinction coefficient k. Is preferably 1.0 or more (preferably 1.1 or more, more preferably 1.4 or more, still more preferably 1.6 or more). On the other hand, the high transmission layer 22 has a refractive index n with respect to ArF exposure light of 2.5 or more (preferably 2.6 or more) and an extinction coefficient k of less than 1.0 (preferably 0.9 or less. 0.7 or less is more preferably 0.4 or less). In the case where the phase shift film 2 is configured with a laminated structure of two or more layers, in order to satisfy a predetermined phase difference and a predetermined transmittance with respect to ArF exposure light, which are characteristics required for the phase shift film, This is because the transmissive layer 22 cannot be realized unless the refractive index n and the extinction coefficient k are within the above ranges.

  In the case where a material in which the high transmission layer 22 of the phase shift film 2 does not substantially contain oxygen and the N / [N + Si] ratio is 50% or more is applied, the same material as the high transmission layer 22 is used as the first material. It is possible to apply to the material which forms the lowest layer 24 of embodiment. This is because the material forming the highly transmissive layer 22 in this case is a material applicable as the material of the lowermost layer 24 of the first embodiment.

  The phase shift film 2 is required to have a thickness of at least 90 nm or less. This is to reduce the bias (EMF bias) related to the electromagnetic field effect. The thickness of the phase shift film 2 is preferably 85 nm or less, and more preferably 80 nm or less. Further, the thickness of the phase shift film 2 is required to be 50 nm or more, preferably 55 nm or more, and more preferably 60 nm or more.

  The phase shift film 2 contains at least one element selected from a material composed of silicon, nitrogen, and oxygen, or a metalloid element, a non-metal element, and a rare gas at a position farthest from the translucent substrate 1. It is preferable to provide an uppermost layer 23 formed of a material to be used. Further, in this method of manufacturing a mask blank, sputtering is performed in a sputtering gas containing a rare gas using a silicon target or a target made of a material containing one or more elements selected from metalloid and nonmetal elements. Thus, it is preferable to have an uppermost layer forming step of forming the uppermost layer 23 at a position farthest from the translucent substrate 1 of the phase shift film 2. Furthermore, in this method of manufacturing a mask blank, the uppermost layer is formed at a position farthest from the translucent substrate of the phase shift film by reactive sputtering in a sputtering gas composed of a nitrogen gas and a rare gas using a silicon target. It is more preferable to have an uppermost layer forming step of forming a layer 23 and performing a process of oxidizing at least the surface layer of the uppermost layer 23.

  A silicon-based material film that does not actively contain oxygen and contains nitrogen has high light resistance to ArF exposure light, but has lower chemical resistance than a silicon-based material film that actively contains oxygen. Tend. Further, as the uppermost layer 23 on the opposite side of the phase shift film 2 from the translucent substrate 1 side, a high transmission layer 22 or a low transmission layer 21 that does not actively contain oxygen and contains nitrogen is disposed. In the case of the mask blank 100 configured, the surface layer of the phase shift film 2 is oxidized by performing mask cleaning on the phase shift mask produced from the mask blank 100 or storing it in the air. It is difficult to avoid. When the surface layer of the phase shift film 2 is oxidized, the optical characteristics at the time of film formation are greatly changed. In particular, in the case of the configuration in which the low transmission layer 21 is provided as the uppermost layer 23 of the phase shift film 2, the increase in transmittance due to the oxidation of the low transmission layer 21 becomes large. The phase shift film 2 is selected on the laminated structure of the low transmission layer 21 and the high transmission layer 22, and further selected from a material composed of silicon, nitrogen and oxygen, or a semi-metal element, a non-metallic element and a rare gas. By providing the uppermost layer 23 formed of a material containing one or more elements, surface oxidation of the low transmission layer 21 and the high transmission layer 22 can be suppressed.

The uppermost layer 23 formed of a material composed of silicon, nitrogen, and oxygen, or a material containing one or more elements selected from a metalloid element, a nonmetallic element, and a rare gas in the material is substantially in the thickness direction of the layer. In addition to the composition having the same composition, the composition has a composition gradient in the layer thickness direction (the composition having a composition gradient in which the oxygen content in the layer increases as the uppermost layer 23 moves away from the translucent substrate 1) Is also included. Examples of a material suitable for the uppermost layer 23 having a configuration having substantially the same composition in the layer thickness direction include SiO ₂ and SiON. As the uppermost layer 23 having a composition gradient in the thickness direction of the layer, the translucent substrate side is SiN, the oxygen content increases as the distance from the translucent substrate 1 increases, and the surface layer is composed of SiO ₂ or SiON. A certain configuration is preferable.

The uppermost layer 23 is formed by using a silicon target or a target made of a material containing at least one element selected from a metalloid element and a nonmetal element in silicon, and a sputtering gas containing nitrogen gas, oxygen gas, and rare gas. An uppermost layer forming process formed by reactive sputtering in the inside can be applied. This uppermost layer forming step can be applied to the formation of the uppermost layer 23 having a composition having substantially the same composition in the layer thickness direction and the uppermost layer 23 having a composition-graded structure. The uppermost layer 23 is formed by using a silicon dioxide (SiO ₂ ) target or a target made of a material containing one or more elements selected from a metalloid element and a non-metal element in silicon dioxide (SiO ₂ ). An uppermost layer forming step of forming by sputtering in a sputtering gas containing a gas can be applied. This uppermost layer forming step can also be applied to the formation of the uppermost layer 23 having a composition having substantially the same composition in the layer thickness direction and the uppermost layer 23 having a composition gradient.

  The uppermost layer 23 is formed by using a silicon target or a target made of a material containing at least one element selected from a metalloid element and a nonmetal element in silicon, and reactive in a sputtering gas containing a nitrogen gas and a rare gas. It is possible to apply a step of performing sputtering and further performing a process of oxidizing at least the surface layer of the uppermost layer 23 formed by this sputtering to form the uppermost layer. This uppermost layer forming step can basically be applied to the formation of the uppermost layer 23 having a composition gradient in the thickness direction of the layer. Examples of the process for oxidizing the surface layer of the uppermost layer 23 in this case include a heat treatment in a gas containing oxygen such as the air, and a process of bringing ozone or oxygen plasma into contact with the uppermost layer.

  The lowermost layer 24, the low transmission layer 21, the high transmission layer 22, and the uppermost layer 23 in the phase shift film 2 are formed by sputtering, but any sputtering method such as DC sputtering, RF sputtering, and ion beam sputtering can be applied. is there. In the case of using a target with low conductivity (such as a silicon target or a silicon compound target that does not contain a metalloid element or has a low content), it is preferable to apply RF sputtering or ion beam sputtering, but the film formation rate is considered. Then, it is more preferable to apply RF sputtering.

  In the step of forming the low transmission layer 21 and the high transmission layer 22 in the phase soft film 2 by sputtering, respectively, the low transmission layer 21 and the high transmission layer 22 are formed in the same film formation chamber and in different film formation chambers. Any of the cases can be applied. In addition, when the low transmission layer 21 and the high transmission layer 22 are formed in the same film formation chamber, the low transmission layer 21 and the high transmission layer 22 may be formed using the same target and may be formed using different targets. Any of these can be applied. In the case where the low transmission layer 21 and the high transmission layer 22 are formed in different film formation chambers, it is preferable that the film formation chambers are connected to each other through, for example, separate vacuum chambers. In this case, it is preferable to connect the load lock chamber through which the translucent substrate in the atmosphere is introduced into the vacuum chamber to the vacuum chamber. In addition, it is preferable to provide a transfer device (robot hand) for transferring the translucent substrate between the load lock chamber, the vacuum chamber, and each film formation chamber.

  On the other hand, in the step of forming the lowermost layer 24 by sputtering in the first and second embodiments, it is preferable that the film forming chamber for forming the lowermost layer 24 is connected to the vacuum chamber. Thereby, the translucent substrate 1 after forming the lowermost layer 24 can be transferred by the transfer device to the film forming chamber in which the low transmission layer 21 or the high transmission layer 22 is formed through the vacuum chamber. The surface of the lowermost layer 24 can be prevented from being exposed to the atmosphere, and the surface oxidation of the lowermost layer 24 can be suppressed. Further, when the target material used when forming the lowermost layer 24 in the first embodiment is the same as the target material used when forming the low transmission layer 21 or the high transmission layer 22, The lowermost layer 24 may be deposited in a deposition chamber in which targets of the same material are installed.

  The mask blank 100 includes a light shielding film 3 on the phase shift film 2. In general, in a binary transfer mask, the outer peripheral region of a region where a transfer pattern is formed (transfer pattern forming region) is transmitted through the outer peripheral region when exposed and transferred to a resist film on a semiconductor wafer using an exposure device. It is required to secure an optical density (OD) of a predetermined value or higher so that the resist film is not affected by exposure light. This also applies to the phase shift mask. Usually, in the outer peripheral area of the transfer mask including the phase shift mask, it is desirable that the OD is 3.0 or more, and at least 2.8 or more is required. The phase shift film 2 has a function of transmitting exposure light with a predetermined transmittance, and it is difficult to ensure a predetermined optical density with the phase shift film 2 alone. For this reason, it is necessary to laminate the light shielding film 3 on the phase shift film 2 at the stage of manufacturing the mask blank 100 in order to ensure an insufficient optical density. With such a mask blank 100 configuration, the light shielding film 3 in the region (basically the transfer pattern forming region) where the phase shift effect is used is removed in the course of manufacturing the phase shift mask 200 (see FIG. 2). By doing so, it is possible to manufacture the phase shift mask 200 in which an optical density of a predetermined value is secured in the outer peripheral region.

  The light shielding film 3 can be applied to either a single layer structure or a laminated structure of two or more layers. In addition, each layer of the light shielding film having a single layer structure and the light shielding film having a laminated structure of two or more layers has a composition gradient in the thickness direction of the layer even if the layers have almost the same composition in the film thickness direction. It may be a configuration.

  The mask blank 100 in the form shown in FIG. 1 has a configuration in which the light shielding film 3 is laminated on the phase shift film 2 without interposing another film. For the light shielding film 3 in this configuration, it is necessary to apply a material having sufficient etching selectivity with respect to an etching gas used when a pattern is formed on the phase shift film 2. In this case, the light-shielding film 3 is preferably formed of a material containing chromium. Examples of the material containing chromium forming the light-shielding film 3 include a material containing one or more elements selected from oxygen, nitrogen, carbon, boron and fluorine in addition to chromium metal. In general, a chromium-based material is etched with a mixed gas of a chlorine-based gas and an oxygen gas, but chromium metal does not have a high etching rate with respect to this etching gas. In consideration of increasing the etching rate of the mixed gas of chlorine-based gas and oxygen gas with respect to the etching gas, the material for forming the light shielding film 3 is one or more elements selected from chromium, oxygen, nitrogen, carbon, boron and fluorine A material containing is preferred. Moreover, you may make the material containing chromium which forms a light shielding film contain one or more elements among molybdenum and tin. By including one or more elements of molybdenum and tin, the etching rate with respect to the mixed gas of chlorine-based gas and oxygen gas can be further increased.

  On the other hand, the present invention includes a configuration in which another film (etching stopper film) is interposed between the phase shift film 2 and the light shielding film 3 as the mask blank 100 of another embodiment. In this case, it is preferable that the etching stopper film is formed with the material containing chromium and the light-shielding film 3 is formed with a material containing silicon.

  The silicon-containing material forming the light shielding film 3 may contain a transition metal or a metal element other than the transition metal. This is because when the phase shift mask 200 is manufactured from the mask blank 100, the pattern formed by the light shielding film 3 is basically a light shielding band pattern in the outer peripheral region, and is irradiated with ArF exposure light as compared with the transfer pattern region. This is because it is rare that the integrated amount is small or the light shielding film 3 remains in a fine pattern, and even if the ArF light resistance is low, a substantial problem hardly occurs. In addition, when the light shielding film 3 contains a transition metal, the light shielding performance is greatly improved as compared with the case where no transition metal is contained, and the thickness of the light shielding film 3 can be reduced. As transition metals to be contained in the light shielding film 3, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V) , Zirconium (Zr), ruthenium (Ru), rhodium (Rh), niobium (Nb), palladium (Pd), or any one metal or an alloy of these metals.

  The mask blank 100 preferably has a structure in which a hard mask film 4 formed of a material having etching selectivity with respect to an etching gas used when the light shielding film 3 is etched is further laminated on the light shielding film 3. Since the light-shielding film 3 has a function of ensuring a predetermined optical density, there is a limit to reducing its thickness. It is sufficient for the hard mask film 4 to have a film thickness that can function as an etching mask until dry etching for forming a pattern on the light shielding film 3 immediately below the hard mask film 4 is completed. There are no restrictions. For this reason, the thickness of the hard mask film 4 can be made much thinner than the thickness of the light shielding film 3. The resist film made of an organic material is sufficient to have a thickness sufficient to function as an etching mask until dry etching for forming a pattern on the hard mask film 4 is completed. The thickness can be greatly reduced. Thinning the resist film is effective in improving resist resolution and preventing pattern collapse, and is extremely important in meeting the demand for miniaturization.

When the light shielding film 3 is formed of a material containing chromium, the hard mask film 4 is preferably formed of the material containing silicon. Since the hard mask film 4 in this case tends to have low adhesion to the organic material resist film, the surface of the hard mask film 4 is subjected to HMDS (Hexamethyldisilazane) treatment to improve surface adhesion. It is preferable. In this case, the hard mask film 4 is more preferably formed of SiO ₂ , SiN, SiON or the like.

  In addition to the above, a material containing tantalum is also applicable as the material of the hard mask film 4 when the light shielding film 3 is formed of a material containing chromium. Examples of the material containing tantalum in this case include a material in which tantalum contains one or more elements selected from nitrogen, oxygen, boron, and carbon in addition to tantalum metal. Examples thereof include Ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN, and the like. Moreover, when the light shielding film 3 is formed of a material containing silicon, the hard mask film 4 is preferably formed of the material containing chromium.

  In the mask blank 100, it is preferable that a resist film of an organic material is formed with a thickness of 100 nm or less in contact with the surface of the hard mask film 4. In the case of a fine pattern corresponding to the DRAM hp32 nm generation, a transfer pattern (phase shift pattern) to be formed on the hard mask film 4 may be provided with SRAF (Sub-Resolution Assist Feature) having a line width of 40 nm. However, even in this case, since the cross-sectional aspect ratio of the resist pattern can be reduced to 1: 2.5, it is possible to prevent the resist pattern from collapsing or detaching during development or rinsing of the resist film. The resist film is more preferably 80 nm or less in thickness.

  FIG. 2 is a schematic cross-sectional view illustrating a process of manufacturing the phase shift mask 200 from the mask blank 100 according to the first and second embodiments of the present invention. The phase shift mask 200 is characterized in that a transfer pattern (phase shift pattern) is formed on the phase shift film 2 of the mask blank 100 and a light shielding band pattern is formed on the light shielding film 3. In the case where the hard mask film 4 is provided on the mask blank 100, the hard mask film 4 is removed while the phase shift mask 200 is being formed.

  The method of manufacturing a phase shift mask according to the present invention uses the mask blank 100 described above, a step of forming a transfer pattern on the light shielding film 3 by dry etching, and a dry process using the light shielding film 3 having the transfer pattern as a mask. The method includes a step of forming a transfer pattern on the phase shift film 2 by etching and a step of forming a light shielding band pattern on the light shielding film 3 by dry etching using the resist film 6b having the light shielding band pattern as a mask. Hereinafter, according to the manufacturing process shown in FIG. 2, the manufacturing method of the phase shift mask 200 of this invention is demonstrated. Here, a method of manufacturing the phase shift mask 200 using the mask blank 100 in which the hard mask film 4 is laminated on the light shielding film 3 will be described. Further, a material containing chromium is applied to the light shielding film 3, and a material containing silicon is applied to the hard mask film 4.

  First, a resist film is formed by spin coating in contact with the hard mask film 4 in the mask blank 100. Next, a first pattern, which is a transfer pattern (phase shift pattern) to be formed on the phase shift film, is exposed and drawn on the resist film with an electron beam, and further subjected to a predetermined process such as a development process, so that the phase shift is performed. A first resist pattern 5a having a pattern was formed (see FIG. 2A). Subsequently, dry etching using a fluorine-based gas was performed using the first resist pattern 5a as a mask to form the first pattern on the hard mask film 4 (hard mask pattern 4a) (see FIG. 2B). .

  Next, after removing the resist pattern 5a, dry etching using a mixed gas of chlorine gas and oxygen gas is performed using the hard mask pattern 4a as a mask to form a first pattern on the light shielding film 3 (light shielding pattern 3a) (see FIG. 2C). Subsequently, dry etching using a fluorine-based gas is performed using the light-shielding pattern 3a as a mask to form a first pattern on the phase shift film 2 (phase shift pattern 2a), and at the same time, the hard mask pattern 4a is also removed ( (Refer FIG.2 (d)).

  Next, a resist film was formed on the mask blank 100 by a spin coating method. Next, a second pattern, which is a pattern (light-shielding pattern) to be formed on the light-shielding film 3, is exposed and drawn with an electron beam on the resist film, and a predetermined process such as a development process is performed to provide a light-shielding pattern. A second resist pattern 6b was formed (see FIG. 2E). Subsequently, dry etching using a mixed gas of chlorine-based gas and oxygen gas is performed using the second resist pattern 6b as a mask to form a second pattern (light-shielding pattern 3b) on the light-shielding film 3 (FIG. 3 ( f)). Further, the second resist pattern 6b was removed, and a predetermined process such as cleaning was performed to obtain a phase shift mask 200 (see FIG. 3G).

The chlorine-based gas used in the dry etching is not particularly limited as long as it contains Cl. For example, Cl ₂ , SiCl ₂ , CHCl ₃ , CH ₂ Cl ₂ , CCl ₄ , BCl _{3 and the} like can be mentioned. Further, the fluorine-based gas used in the dry etching is not particularly limited as long as F is contained. For _{example, CHF 3, CF 4, C} 2 F 6, C 4 F 8, SF 6 and the like. In particular, since the fluorine-based gas not containing C has a relatively low etching rate with respect to the glass substrate, damage to the glass substrate can be further reduced.

  Since the phase shift mask 200 of the present invention is manufactured using the mask blank 100 described above, the CD of the phase shift pattern 2a can be obtained even after being irradiated with the exposure light of the ArF excimer laser. The change (weight) can be suppressed to a small range. Therefore, even if the phase shift mask 200 after this integrated irradiation is set on a mask stage of an exposure apparatus using ArF excimer laser as exposure light, and the phase shift pattern is exposed and transferred to the resist film on the semiconductor device, the semiconductor device The pattern can be transferred to the upper resist film with sufficient accuracy to meet the design specifications. In addition, the etching end point can be detected relatively easily at the time of correcting the EB defect for the black defect found by the mask inspection performed in the process of manufacturing the phase shift mask 200.

  The semiconductor device manufacturing method of the present invention uses the phase shift mask 200 manufactured using the phase shift mask 200 or the mask blank 100 to expose and transfer a pattern onto a resist film on a semiconductor substrate. It is said. Since the phase shift mask 200 and the mask blank 100 of the present invention have the effects as described above, the mask stage of the exposure apparatus using the ArF excimer laser as the exposure light is subjected to the integrated irradiation of the exposure light of the ArF excimer laser. Even if the phase shift mask 200 of the present invention is set and the phase shift pattern 2a is exposed and transferred to the resist film on the semiconductor device, the pattern can be transferred to the resist film on the semiconductor device with sufficient accuracy to satisfy the design specifications. it can.

  Further, even when the black defect portion is exposed and transferred to the resist film on the semiconductor device using the phase shift mask 200 in which the black defect portion is corrected by the EB defect correction in the course of the production, the black defect of the phase shift mask 200 exists. No transfer failure occurs in the resist film on the semiconductor device corresponding to the pattern portion. For this reason, when a circuit pattern is formed by dry etching the lower layer film using the resist film pattern as a mask, a highly accurate circuit pattern without wiring short-circuiting or disconnection due to insufficient accuracy or transfer failure may be formed. it can.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.
Example 1
[Manufacture of mask blanks]
A translucent substrate 1 made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. The translucent substrate 1 had an end face and a main surface polished to a predetermined surface roughness, and then subjected to a predetermined cleaning process and a drying process.

First, the translucent substrate 1 is installed in a single-wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) (flow rate ratio: Ar: N ₂ = 1) : 3, pressure = 0.09 Pa) is used as the sputtering gas, the power of the RF power source is set to 2.8 kW, and the lowermost layer 24 made of silicon and nitrogen is formed on the translucent substrate 1 by reactive sputtering (RF sputtering). Si: N = 44 atomic%: 56 atomic%) was formed with a thickness of 9 nm. Only the lowermost layer 24 is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of the lowermost layer 24 are measured using a spectroscopic ellipsometer (JA Woollam M-2000D). When measured, the refractive index n at a wavelength of 193 nm was 2.52, and the extinction coefficient k was 0.39. Note that the conditions used when forming the lowermost layer 24 are as follows: the flow rate of N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the sputtering gas in advance with the used single wafer RF sputtering apparatus. The relationship between the ratio and the film formation rate is verified, and film formation conditions such as a flow rate ratio capable of stably forming a film in the reaction mode (poison mode) region are selected. The composition of the lowermost layer 24 is a result obtained by measurement by X-ray photoelectron spectroscopy (XPS). The same applies to other films.

Next, the translucent substrate 1 on which the lowermost layer 24 is formed is installed in a single wafer RF sputtering apparatus, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) using a silicon (Si) target ( The flow rate ratio Ar: N ₂ = 2: 3, pressure = 0.035 Pa) is used as the sputtering gas, the power of the RF power source is set to 2.8 kW, and reactive sputtering (RF sputtering) causes silicon and A low transmission layer 21 made of nitrogen (Si: N = 59 atomic%: 41 atomic%) was formed to a thickness of 7 nm. Only the low transmission layer 21 is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of the low transmission layer 21 are measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 1.85, and the extinction coefficient k was 1.70. Incidentally, the conditions used in forming the low-permeability layer 21, in advance at the single-wafer RF sputtering apparatus used, the N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the sputtering gas The relationship between the flow rate ratio and the film formation rate is verified, and film formation conditions such as a flow rate ratio that enables stable film formation in the metal mode region are selected.

Subsequently, the translucent substrate 1 on which the low transmission layer 21 is formed is installed in a single wafer RF sputtering apparatus, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) using a silicon (Si) target. (Flow rate ratio Ar: N ₂ = 1: 3, pressure = 0.09 Pa) is used as a sputtering gas, the power of the RF power source is set to 2.8 kW, and reactive sputtering (RF sputtering) is performed on the low transmission layer 21. A high transmission layer 22 (Si: N = 44 atomic%: 56 atomic%) made of silicon and nitrogen was formed to a thickness of 17 nm. Only the highly transmissive layer 22 is formed on the main surface of another translucent substrate under the same conditions, and the optical property of the highly transmissive layer 22 is measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 2.52, and the extinction coefficient k was 0.39. Incidentally, the conditions used in forming the high-permeability layer 22, in advance at the single-wafer RF sputtering apparatus used, the N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the sputtering gas The relationship between the flow rate ratio and the film formation rate is verified, and film formation conditions such as a flow rate ratio capable of stably forming a film in the reaction mode (poison mode) region are selected.

  Next, the translucent substrate 1 in which the lowermost layer 24, the low transmission layer 21 and the high transmission layer 22 are stacked is installed in a single wafer RF sputtering apparatus, and under the same conditions as when the low transmission layer 21 is formed. The low transmission layer 21 was formed on the high transmission layer 22 with a thickness of 7 nm. The composition and optical characteristics of the formed low transmission layer 21 are the same as those of the low transmission layer 21 previously formed.

  Next, the translucent substrate 1 in which the lowermost layer 24, the low transmission layer 21, the high transmission layer 22, and the low transmission layer 21 are stacked is installed in the single wafer RF sputtering apparatus, and the high transmission layer 22 is formed. The uppermost layer 23 was formed to a thickness of 18 nm on the low transmission layer 21 under the same conditions as the time. The composition and optical characteristics of the deposited uppermost layer 23 are the same as those of the high transmission layer 22. The phase shift film 2 having a structure in which the lowermost layer 24, the low transmission layer 21, the high transmission layer 22, the low transmission layer 21, and the uppermost layer 23 are laminated on the translucent substrate 1 by the above procedure.

  Then, the translucent substrate 1 on which the phase shift film 2 was laminated was subjected to a heat treatment in the atmosphere under the conditions of a heating temperature of 500 ° C. and a treatment time of 1 hour. The uppermost layer 23 of the phase shift film 2 after the heat treatment has an internal structure having a composition gradient in which the oxygen content increases as the distance from the substrate side increases. When the transmittance and phase difference at the wavelength (approximately 193 nm) of the light of the ArF excimer laser were measured for this phase shift film 2 with a phase shift amount measuring device, the transmittance was 5.97% and the phase difference was 177.7. It was a degree.

Next, the translucent substrate 1 on which the phase shift film 2 is formed is installed in a single-wafer DC sputtering apparatus, and using a chromium (Cr) target, argon (Ar), carbon dioxide (CO ₂ ), nitrogen ( N ₂ ) and helium (He) mixed gas (flow ratio Ar: CO ₂ : N ₂ : He = 22: 39: 6: 33, pressure = 0.2 Pa) is used as sputtering gas, and the power of the DC power source is 1. The lowermost layer of the light shielding film 3 made of CrOCN was formed to a thickness of 30 nm on the phase shift film 2 by reactive sputtering (DC sputtering).

Next, using the same chromium (Cr) target, a mixed gas of argon (Ar) and nitrogen (N ₂ ) (flow rate ratio Ar: N ₂ = 83: 17, pressure = 0.1 Pa) is used as a sputtering gas, and a DC power source The lower layer of the light-shielding film 3 made of CrN was formed to a thickness of 4 nm on the phase shift film 2 by reactive sputtering (DC sputtering) with a power of 1.4 kW.

Next, using the same chromium (Cr) target, a mixed gas of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He) (flow rate ratio: Ar: CO ₂ : N ₂ : He = 21: 37: 11: 31, pressure = 0.2 Pa) as the sputtering gas, the power of the DC power source is 1.9 kW, and the light-shielding film made of CrOCN is formed on the phase shift film 2 by reactive sputtering (DC sputtering). The upper layer of 3 was formed with a thickness of 14 nm. By the above procedure, the light-shielding film 3 made of a chromium-based material having a three-layer structure of the lowermost layer made of CrOCN, the lower layer made of CrN, and the upper layer made of CrOCN was formed with a total film thickness of 48 nm from the phase shift film 2 side.

Furthermore, the translucent substrate 1 in which the phase shift film 2 and the light shielding film 3 are laminated is installed in a single wafer RF sputtering apparatus, and a silicon dioxide (SiO ₂ ) target is used, and argon (Ar) gas (pressure = pressure = 0.03 Pa) was used as the sputtering gas, the power of the RF power source was set to 1.5 kW, and the hard mask film 4 made of silicon and oxygen was formed on the light shielding film 3 by RF sputtering to a thickness of 5 nm. By the above procedure, a mask blank 100 having a structure in which a phase shift film 2 having a five-layer structure, a light shielding film 3 and a hard mask film 4 were laminated on a translucent substrate 1 was manufactured.

[Manufacture of phase shift mask]
Next, using the mask blank 100 of Example 1, the phase shift mask 200 of Example 1 was produced according to the following procedure. First, the surface of the hard mask film 4 was subjected to HMDS treatment. Subsequently, a resist film made of a chemically amplified resist for electron beam drawing with a film thickness of 80 nm was formed in contact with the surface of the etching mask film 4 by spin coating. Next, a first pattern, which is a phase shift pattern to be formed on the phase shift film, is drawn on the resist film by electron beam, predetermined development processing and cleaning processing are performed, and the first pattern having the first pattern is formed. The resist pattern 5a was formed (see FIG. 2A). At this time, in addition to the phase shift pattern that should be originally formed, a program defect is added to the first pattern drawn by the electron beam so that a black defect is formed in the phase shift film 2.

Next, dry etching using CF ₄ gas was performed using the first resist pattern 5a as a mask to form a first pattern (etching mask pattern 4a) on the hard mask film 4 (see FIG. 2B). .

Next, the first resist pattern 5a was removed. Subsequently, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed using the hard mask pattern 4 a as a mask to form a first pattern on the light shielding film 3. (Light shielding pattern 3a) (see FIG. 2C). Next, using the light shielding pattern 3a as a mask, dry etching using fluorine-based gas (SF ₆ + He) is performed to form a first pattern on the phase shift film 2 (phase shift pattern 2a), and at the same time, a hard mask pattern 4a was removed (see FIG. 3 (d)).

Next, a resist film made of a chemically amplified resist for electron beam drawing was formed on the light-shielding film pattern 3a with a film thickness of 150 nm by spin coating. Next, a second pattern, which is a pattern (light-shielding pattern) to be formed on the light-shielding film, is exposed and drawn on the resist film, and a predetermined process such as a development process is further performed, so that the second resist having the light-shielding pattern is obtained. A pattern 6b was formed (see FIG. 2E). Subsequently, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed using the second resist pattern 6 b as a mask, and the second pattern is formed on the light-shielding film 3. Was formed (light-shielding pattern 3b) (see FIG. 2F). Further, the second resist pattern 6b was removed, and a predetermined process such as cleaning was performed to obtain a phase shift mask 200 (see FIG. 2G).

  When the mask pattern was inspected by the mask inspection apparatus with respect to the manufactured halftone phase shift mask 200 of Example 1, it was confirmed that black defects were present in the phase shift pattern 2a where the program defects were arranged. It was done. When the EB defect correction was performed on the black defect portion, the etching end point could be easily detected, and the etching on the surface of the translucent substrate 1 could be minimized.

The ArF excimer laser light was irradiated to the phase shift pattern of the halftone phase shift mask 200 of Example 1 at an integrated dose of 20 kJ / cm ² . The CD change amount of the phase shift pattern before and after this irradiation treatment was about 2 nm, and the CD change amount was within a range usable as a phase shift mask. Using the AIMS 193 (manufactured by Carl Zeiss) on the semiconductor device with the exposure light having a wavelength of 193 nm on the halftone phase shift mask 200 of Example 1 after performing the EB defect correction and the ArF excimer laser light irradiation treatment The transfer image when exposed and transferred to the resist film was simulated.

  When the exposure transfer image of this simulation was verified, the design specifications were sufficiently satisfied. Further, the transfer image of the portion where the EB defect correction was performed was incomparable as compared with the transfer image of other regions. From this result, even if the phase shift mask 200 of Example 1 after performing the EB defect correction and the integrated irradiation of the ArF excimer laser is set on the mask stage of the exposure apparatus, and transferred to the resist film on the semiconductor device, It can be said that the circuit pattern finally formed on the semiconductor device can be formed with high accuracy.

(Example 2)
[Manufacture of mask blanks]
The mask blank of Example 2 was manufactured in the same procedure as the mask blank of Example 1 except for the step of forming the lowermost layer 24. The bottom layer 24 of Example 2 was formed by the following procedure.

The translucent substrate 1 is installed in a single-wafer DC sputtering apparatus, and using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 8 atomic%: 92 atomic%), argon (Ar), By reactive sputtering (DC sputtering) using a mixed gas of nitrogen (N ₂ ) and helium (He) as a sputtering gas, the lowermost layer 24 (Mo: Si :) made of molybdenum, silicon, and nitrogen is formed on the translucent substrate 1. N = 3 atomic%: 48 atomic%: 49 atomic%) was formed with a thickness of 5 nm. Only the lowermost layer 24 is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of the lowermost layer 24 are measured using a spectroscopic ellipsometer (JA Woollam M-2000D). When measured, the refractive index n at a wavelength of 193 nm was 2.41 and the extinction coefficient k was 0.51.

  When the transmittance and phase difference at the wavelength of the ArF excimer laser light (approximately 193 nm) were measured with respect to the phase shift film 2 of Example 2, the transmittance was 5.61% and the phase difference was measured. Was 178.8 degrees. By the above procedure, the phase shift film 2 having the laminated structure of the lowermost layer 24 made of MoSiN, the low transmission layer 21, the high transmission layer 22, the low transmission layer 21 and the uppermost layer 23, and the light shielding film are formed on the translucent substrate 1. 3 and the mask blank of Example 2 in which the hard mask film 4 was laminated were manufactured.

[Manufacture of phase shift mask]
Next, using the mask blank 100 of Example 2, the phase shift mask 200 of Example 2 was produced in the same procedure as in Example 1. When the mask pattern was inspected by the mask inspection apparatus for the halftone phase shift mask 200 of Example 2 produced, the presence of black defects was confirmed in the phase shift pattern 2a where the program defects were placed. It was done. When the EB defect correction was performed on the black defect portion, the etching end point could be easily detected, and the etching on the surface of the translucent substrate 1 could be minimized.

For the phase shift pattern of the halftone phase shift mask 200 of Example 2, a process of irradiating ArF excimer laser light at an integrated dose of 20 kJ / cm ² was performed. The CD change amount of the phase shift pattern before and after this irradiation treatment was about 3 nm, which was the CD change amount in a range usable as a phase shift mask. Using the AIMS 193 (manufactured by Carl Zeiss) on the semiconductor device with the exposure light having a wavelength of 193 nm on the halftone phase shift mask 200 of Example 2 after the EB defect correction and the ArF excimer laser light irradiation treatment The transfer image when exposed and transferred to the resist film was simulated.

  When the exposure transfer image of this simulation was verified, the design specifications were sufficiently satisfied. Further, the transfer image of the portion where the EB defect correction was performed was incomparable as compared with the transfer image of other regions. From this result, even if the phase shift mask 200 of Example 2 after performing the EB defect correction and the integrated irradiation of the ArF excimer laser is set on the mask stage of the exposure apparatus, and is exposed and transferred to the resist film on the semiconductor device, It can be said that the circuit pattern finally formed on the semiconductor device can be formed with high accuracy.

(Comparative Example 1)
[Manufacture of mask blanks]

  The mask blank of Comparative Example 1 uses a low transmission layer 21 and a high transmission layer 22 having the same composition and optical characteristics as Example 1, and the phase shift film from the light transmitting substrate side to the low transmission layer and the high transmission layer. The difference is that the structure is formed by laminating a low transmission layer and a high transmission layer in this order. Further, a low-transmitting layer (a layer containing no metal and having a nitrogen content of 41 atomic% and less than 50 atomic%) on the translucent substrate side is in contact with the surface of the translucent substrate. This is also very different from the mask blank of Example 1.

  Specifically, a low transmission layer (thickness 8 nm), a high transmission layer (thickness 21 nm), a low transmission layer (thickness 8 nm), and a high transmission are formed on the translucent substrate under the same film formation conditions as in Example 1. Layers (thickness 21 nm) were sequentially formed to form a phase shift film. Next, the light-transmitting substrate on which the phase shift film was laminated was subjected to heat treatment under the same conditions as in Example 1. As a result, the highly transmissive layer on the top of the phase shift film has an internal structure having a composition gradient in which the oxygen content increases as the distance from the substrate side increases. When the transmittance and phase difference at the wavelength of the ArF excimer laser light (about 193 nm) were measured with this phase shift film measuring device, the transmittance was 5.99% and the phase difference was 177.1 degrees. Met.

  Further, the same light shielding film and hard mask film as in Example 1 were appropriately formed on the phase shift film. The mask blank 100 of the comparative example 1 provided with the structure which laminated | stacked the phase shift film of the 4 layer structure, the light shielding film, and the hard mask film | membrane on the translucent board | substrate with the above procedure was manufactured.

[Manufacture of phase shift mask]
Next, using the mask blank of Comparative Example 1, a phase shift mask of Comparative Example 1 was produced in the same procedure as in Example 1. When the mask pattern was inspected with the mask inspection apparatus for the halftone type phase shift mask of Reference Example 1 produced, the presence of black defects was confirmed in the phase shift pattern at the place where the program defects were arranged. . When EB defect correction was performed on the black defect portion, it was difficult to detect the etching end point, and etching progressed from the surface of the translucent substrate.

A process of irradiating ArF excimer laser light with an integrated dose of 20 kJ / cm ² was performed on the phase shift pattern of the halftone phase shift mask of Comparative Example 1. The CD change amount of the phase shift pattern before and after this irradiation treatment was about 2 nm, and the CD change amount was within a range usable as a phase shift mask. For the halftone phase shift mask of Comparative Example 1 after the EB defect correction and ArF excimer laser light irradiation treatment, AIMS 193 (manufactured by Carl Zeiss) was used to expose the semiconductor device with exposure light having a wavelength of 193 nm. The transfer image was simulated when exposed and transferred to the resist film.

  When the exposure transfer image of this simulation was verified, the design specifications were generally sufficiently satisfied except for the portion where the EB defect was corrected. However, the transfer image of the portion where the EB defect was corrected was at a level at which transfer failure occurred due to the influence of etching on the translucent substrate. From this result, when the mask stage of the exposure apparatus is set to the phase shift mask of Comparative Example 1 after correcting the EB defect and exposed and transferred to the resist film on the semiconductor device, it is finally formed on the semiconductor device. It is expected that the circuit pattern is disconnected or short-circuited.

(Comparative Example 2)
[Manufacture of mask blanks]
A light-transmitting substrate made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared in the same procedure as in Example 1. Next, a translucent substrate is installed in a single wafer DC sputtering apparatus, and a mixed sintered target of molybdenum (Mo) and silicon (Si) (Mo: Si = 12 atomic%: 88 atomic%) is used. Reactive sputtering (DC) using a mixed gas of argon (Ar), nitrogen (N ₂ ) and helium (He) (flow rate ratio: Ar: N ₂ : He = 8: 72: 100, pressure = 0.2 Pa) as a sputtering gas. By sputtering, a phase shift film made of molybdenum, silicon, and nitrogen was formed on the translucent substrate 1 to a thickness of 69 nm.

  Next, heat treatment in the atmosphere was performed on the phase shift film on the light-transmitting substrate. This heat treatment was performed at 450 ° C. for 1 hour. With respect to the phase shift film of Comparative Example 2 after this heat treatment was performed, the transmittance and phase difference at the wavelength of the ArF excimer laser light (about 193 nm) were measured with a phase shift amount measuring device. The phase difference was 6.02% and 177.9 degrees.

  Next, a light shielding film of a chromium-based material having a three-layer structure was formed on the phase shift film with a total film thickness of 48 nm in the same procedure as in Example 1. Subsequently, a hard mask film made of silicon and oxygen was formed to a thickness of 5 nm on the light shielding film in the same procedure as in Example 1. The mask blank of the comparative example 2 provided with the structure which laminated | stacked the phase shift film which consists of MoSiN, the light shielding film, and the etching mask film on the translucent board | substrate with the above procedure was manufactured.

[Manufacture of phase shift mask]
Next, using the mask blank of Comparative Example 2, a phase shift mask of Comparative Example 2 was produced in the same procedure as in Example 1. When the mask pattern was inspected by the mask inspection apparatus with respect to the produced halftone phase shift mask of Comparative Example 2, the presence of black defects was confirmed in the phase shift pattern at the place where the program defects were arranged. . When the EB defect correction was performed on the black defect portion, the etching end point could be easily detected, and the etching on the surface of the translucent substrate could be minimized.

The ArF excimer laser light was irradiated to the phase shift pattern of the halftone phase shift mask of Comparative Example 2 at an integrated dose of 20 kJ / cm ² . The CD change amount of the phase shift pattern before and after this irradiation treatment was 20 nm or more, which was a CD change amount greatly exceeding the range usable as a phase shift mask.

The resist film on the semiconductor device is exposed to light having a wavelength of 193 nm using AIMS 193 (manufactured by Carl Zeiss) with respect to the halftone phase shift mask 200 of Comparative Example 2 after being irradiated with ArF excimer laser light. The transferred image was simulated when exposed and transferred. When the exposure transfer image of this simulation was verified, the design specification could not be satisfied due to the influence of the CD change of the phase shift pattern. From this result, when the phase shift mask of Comparative Example 2 after the ArF excimer laser is irradiated at an integrated dose of 20 kJ / cm ² is set on the mask stage of the exposure apparatus and exposed and transferred to the resist film on the semiconductor device, It is expected that the circuit pattern finally formed on the semiconductor device will be disconnected or short-circuited.

DESCRIPTION OF SYMBOLS 1 Translucent substrate 2 Phase shift film 21 Low transmission layer 22 High transmission layer 23 Uppermost layer 24 Lowermost layer 2a Phase shift pattern 3 Light shielding film 3a, 3b Light shielding pattern 4 Hard mask film 4a Hard mask pattern 5a First resist pattern 6b Second resist pattern 100 Mask blank 200 Phase shift mask

Claims (17)

A mask blank provided with a phase shift film on a translucent substrate,
The phase shift film transmits the ArF excimer laser exposure light with a predetermined transmittance, and passes through the air by the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. And a function of causing a predetermined phase difference with the exposure light,
The phase shift film has at least one combination of a laminated structure of a low transmission layer and a high transmission layer,
The low-permeability layer and the high-permeability layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a nonmetal element, and a rare gas in the material,
The phase shift film has a lowermost layer at a position in contact with the translucent substrate,
The lowermost layer is formed of a material containing silicon and nitrogen, substantially free of metal and oxygen, and a ratio of the content of nitrogen to the total content of silicon and nitrogen being 50% or more. A mask blank characterized by A mask blank provided with a phase shift film on a translucent substrate,
The phase shift film transmits the ArF excimer laser exposure light with a predetermined transmittance, and passes through the air by the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. And a function of causing a predetermined phase difference with the exposure light,
The phase shift film has at least one combination of a laminated structure of a low transmission layer and a high transmission layer,
The low-permeability layer and the high-permeability layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a nonmetal element, and a rare gas in the material,
The phase shift film has a lowermost layer at a position in contact with the translucent substrate,
The lowermost layer is made of a material containing metal and silicon, and is a mask blank.   3. The mask blank according to claim 2, wherein the lowermost layer is made of a material that does not substantially contain oxygen.   The mask blank according to claim 2 or 3, wherein the lowermost layer has a ratio of the metal content to the total content of the metal and silicon of 5% or more.   The mask blank according to any one of claims 2 to 4, wherein the lowermost layer has a ratio of the content of the metal to the total content of the metal and silicon of 15% or less.   6. The mask blank according to claim 2, wherein the lowermost layer is formed of a material made of metal, silicon, and nitrogen.   The mask blank according to claim 1, wherein the lowermost layer has a thickness of 2 nm or more.   The mask blank according to claim 1, wherein the low transmission layer has a relatively low nitrogen content as compared with the high transmission layer.   The mask blank according to claim 1, wherein the low transmission layer and the high transmission layer are made of the same constituent element.   The mask blank according to any one of claims 1 to 9, wherein the highly permeable layer has a ratio of nitrogen content to a total content of silicon and nitrogen of 50% or more.   The mask blank according to claim 1, wherein the low transmission layer and the high transmission layer are made of a material made of silicon and nitrogen.   The mask blank according to claim 1, wherein the phase shift film has two or more combinations of laminated structures of the high transmission layer and the low transmission layer.   The phase shift film is formed at a position farthest from the translucent substrate by a material composed of silicon and oxygen, a material composed of silicon, nitrogen and oxygen, or a semi-metal element, a non-metal element, and a rare gas. The mask blank according to any one of claims 1 to 12, which has an uppermost layer formed of any one of materials containing one or more selected elements.   A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to claim 1. A step of performing dry etching on the phase shift film of the mask blank according to claim 1 to form a transfer pattern;
Performing a mask defect inspection on the phase shift film on which the transfer pattern is formed;
A step of supplying a fluorine-containing substance to the black defect portion of the phase shift film detected by the mask defect inspection and correcting the black defect portion by performing etching by irradiating charged particles. A method of manufacturing a phase shift mask, comprising:   A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the phase shift mask according to claim 14.   A method for manufacturing a semiconductor device, comprising: a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask manufactured by the method for manufacturing a phase shift mask according to claim 15.

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