JP5820555B2 - Manufacturing method of mask blank and phase shift mask - Google Patents

Description

  The present invention relates to a mask blank used for manufacturing a photomask (particularly, a substrate digging type phase shift mask) used in manufacturing an electronic device such as a semiconductor device, and a method for manufacturing the phase shift mask.

  In general, in a manufacturing process of a semiconductor device, a fine pattern is formed using a photolithography method. Also, a number of substrates called photomasks (hereinafter referred to as “transfer masks”) are usually used to form this fine pattern. This transfer mask is generally provided with a fine pattern made of a metal thin film on a translucent glass substrate, and the photolithographic method is also used in the production of this transfer mask.

  In recent years, as the degree of integration of semiconductor devices has been remarkably improved, the demand for pattern miniaturization in transfer masks has only increased. As a transfer mask, a binary mask having a light-shielding film pattern made of, for example, a chromium-based material is formed on a translucent substrate, or a phase shifter portion having a predetermined phase difference with respect to exposure light is formed on the translucent substrate. A phase shift mask that improves the contrast, that is, the resolution of the boundary portion between the phase shifter portion and the light transmission portion is conventionally known. As the phase shift mask, light having an intensity that does not substantially contribute to exposure (for example, 1% to 30% with respect to the exposure wavelength) is transmitted through the translucent substrate, and a predetermined phase difference (for example, 180) is used. In addition to a halftone phase shift mask having a light transflective film pattern made of, for example, a MoSi-based material having a degree of curvature, Levenson is a substrate digging type in which a phase shifter portion is digged by etching or the like. A type phase shift mask or the like is known (for example, Patent Documents 1 and 2).

  This substrate digging type Levenson type phase shift mask has the same configuration as the binary mask blank, that is, a mask blank in which a pattern forming thin film is formed on a translucent substrate. Is the same as the light shielding film of the binary mask blank. In addition to the conventional chromium-based material, a material mainly composed of tantalum has been proposed as a material for the light shielding film. A Levenson-type phase shift mask using a mask blank having the same configuration as that of the binary mask blank is manufactured as follows.

First, a predetermined transfer pattern is formed on the pattern forming thin film (light shielding film) of the mask blank.
Next, in order to produce a substrate digging portion (phase shift portion), a resist pattern of a predetermined substrate digging portion is formed on the mask blank on which the transfer pattern is formed, and then this resist pattern is used as a mask. For example, the translucent substrate is dug to a predetermined depth by dry etching using a fluorine-based gas to form a phase shift pattern.
In this way, a substrate digging type Levenson type phase shift mask is manufactured.

JP-A-9-160218 JP 2003-241360 A

  When fabricating a substrate digging type Levenson type phase shift mask using a mask blank having the same structure as a binary mask blank having a light shielding film formed on a translucent substrate, the substrate digging portion (phase shift portion) is not Control of the phase difference between the digging portions (that is, control of the substrate thickness between the digging portion and the non-digging portion) becomes important. In order to accurately control the phase difference, the dry etching for forming a transfer pattern (light-shielding film pattern) on the light-shielding film of the mask blank, which is a pre-process of the process of digging the light-transmitting substrate to a predetermined depth, is performed. It is necessary to prevent the exposed portion of the substrate from being dug as much as possible.

  When the light shielding film of the mask blank is formed of a tantalum-based material and the light-shielding film is configured to have a light-shielding performance of a predetermined thickness or less, the tantalum-based material that is not oxidized or not oxidized It is desirable to use (tantalum metal, tantalum nitride, tantalum boride, tantalum carbide, or the like). A tantalum-based material that has not been oxidized or has not progressed is a material that can be dry-etched by either a fluorine-based gas or a chlorine-based gas that does not substantially contain oxygen. However, the oxidized tantalum-based material has a remarkably low etching rate with respect to a chlorine-based gas that does not substantially contain oxygen, and is difficult to dry-etch. Therefore, etching is performed by dry etching with a fluorine-based gas.

When the tantalum-based material is dry-etched with a fluorine-based gas, a gas such as CHF ₃ or CF ₄ is used. Glass materials such as synthetic quartz that are usually used as a material for the light-transmitting substrate are easily dry-etched by these fluorine-based gases. When the lower layer which is a layer in contact with the light-transmitting substrate of the light shielding film is formed of an oxidized tantalum material, it is difficult to obtain sufficient etching selectivity with the light-transmitting substrate. Therefore, when a Levenson-type phase shift mask of a digging type substrate is produced using a tantalum-based light-shielding film mask blank made of a tantalum-based material that has not been oxidized or has not progressed, a dry process using chlorine-based gas is required. It is necessary to form a pattern on the light shielding film by etching.

  On the other hand, after forming the light shielding film pattern, a resist is applied on the mask blank to form a substrate digging portion, pattern drawing exposure and development processing are performed, and a resist pattern of the substrate digging portion is formed. For reasons such as drawing accuracy, a space portion wider than the width of the original substrate digging portion is formed. As a result, a portion where the surface of the light shielding film is exposed near the edge of the light shielding film pattern is generated. Subsequently, the substrate is dug by dry etching using the resist pattern of the substrate dug portion as a mask. As described above, the tantalum-based light-shielding film is resistant to dry etching by a fluorine-based gas when dug the substrate. Low. The depth of digging the substrate is also about 173 nm, which is deeper than the thickness of the light shielding film, even when the exposure light is an ArF excimer laser. For this reason, the exposed light shielding film may be etched.

  In order to avoid the exposed light shielding film from being etched when digging such a substrate, when manufacturing a mask blank, dry etching with fluorine gas and oxygen are applied on the tantalum light shielding film. It is necessary to stack a hard mask film (etching mask film) that is resistant to any of dry etching with a chlorine-based gas that is not substantially contained and that can be etched by other than these etchants. Examples of a material suitable for such a hard mask film include a chromium-based material.

  From the viewpoint of making the resist film thickness formed on the mask blank as thin as possible, it is desirable to increase the etching rate of the chromium-based material constituting the hard mask film. For this purpose, it is conceivable to increase the etching rate by increasing the oxygen content in the chromium-based material.

  By the way, using a mask blank in which a light shielding film of, for example, tantalum nitride is formed in contact with a glass substrate and a hard mask film of a chromium-based material is further laminated on this light shielding film, a substrate digging type Levenson type phase shift When producing a mask, first, a resist film having a light shielding film pattern is formed on a mask blank. Next, using the resist film as a mask, the hard mask film made of a chromium-based material is dry-etched to form a light shielding film pattern on the hard mask film. Then, using the hard mask film on which the light shielding film pattern is formed as a mask, the light shielding film made of tantalum nitride is dry-etched with a chlorine-based gas containing substantially no oxygen to form a light shielding film pattern on the light shielding film. Next, a resist pattern of the substrate digging portion is formed on the mask blank on which the light shielding film pattern is formed, and the substrate is dug by dry etching using the resist pattern of the substrate digging portion as a mask to form a phase shift portion. .

  As is clear from the mask manufacturing process described above, the hard mask film formed of a chromium-based material only needs to have resistance to dry etching with a fluorine-based gas when etching a glass substrate. In addition, it is necessary to have resistance to dry etching with a chlorine-based gas that does not substantially contain oxygen when etching the light-shielding film of tantalum nitride. As described above, from the viewpoint of reducing the resist film thickness, it is conceivable to increase the oxygen content in the chromium-based material in order to improve the etching rate of the hard mask film made of the chromium-based material.

  However, according to the study of the present inventors, when the light shielding film made of tantalum nitride is dry-etched with a chlorine-based gas containing substantially no oxygen, the oxygen content in the chromium-based material forming the hard mask film If there is a large amount (for example, the oxygen content in the film is more than 30 atomic%), the edge portion (side wall) of the pattern of the hard mask film is etched by the dry etching of the chlorine-based gas substantially not containing oxygen. It has been found that there is a risk of decline. In particular, when the light shielding film pattern is formed on the hard mask film, the resist pattern on the hard mask film is peeled off, and the light shielding film is dry-etched using only the hard mask film as a mask. In addition, the pattern surface may be degraded by dry etching of a chlorine-based gas that does not substantially contain oxygen. When the pattern of the hard mask film is reduced, the light shielding film directly under the hard mask film is etched during the subsequent dry etching with a fluorine-based gas for forming a dug in the glass substrate. The technical significance of forming a chromium-based hard mask film on the tantalum-based light-shielding film was lost in order to avoid damage to the light-shielding film due to dry etching of fluorine-based gas when the substrate was dug in the first place. It will be broken.

  On the other hand, when the light shielding film of the mask blank is formed of a tantalum-based material and a light shielding film having a surface reflection preventing function of a certain degree or more is formed, a laminated structure of at least a lower layer (light shielding layer) and an upper layer (surface reflection preventing layer) It is necessary to. As described above, in order to ensure etching selectivity with the light-transmitting substrate, it is necessary to apply a tantalum-based material that is not oxidized or has not been oxidized to the lower layer. Therefore, when the upper layer having a surface antireflection function is formed of a tantalum material, it is necessary to apply a tantalum material containing oxygen. In addition, when not limited to a tantalum material, a transition metal silicide material can also be used.

  For example, using a mask blank of a tantalum-based light-shielding film having a laminated structure of a tantalum nitride lower layer (light-shielding layer) and tantalum oxide upper layer (surface antireflection layer), a substrate digging type Levenson-type phase shift mask is manufactured. In this case, first, a so-called two-stage etching is employed in which a pattern is formed in the upper layer by dry etching using a fluorine-based gas, and then a pattern is formed in the lower layer by dry etching using a chlorine-based gas. Even in such a tantalum-based light-shielding film mask blank having a two-layer structure, when a substrate digging type Levenson type phase shift mask is to be manufactured without laminating a chromium-based material hard mask film, the substrate digging is performed. In the dry etching of the fluorine-based gas at that time, there is a possibility that the etching proceeds from the upper surface to the lower layer in the vicinity of the edge where the surface of the light shielding film pattern is exposed. Further, even when a hard mask film of a chromium-based material is laminated on the light-shielding film, in order to perform dry etching of a chlorine-based gas that does not substantially contain oxygen when forming a pattern under the light-shielding film, It is necessary to consider the oxygen content in the hard mask film as in the case of the light shielding film having a single layer structure of tantalum nitride.

  SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned various conventional problems and to provide a mask blank suitable for producing a substrate digging type phase shift mask having a light-shielding film pattern of a tantalum material. To do. It is another object of the present invention to provide a method for manufacturing a substrate digging type phase shift mask using such a mask blank.

The present inventor has completed the present invention as a result of intensive studies to solve the above problems.
That is, in order to solve the above problems, the present invention has the following configuration.
(Configuration 1)
A mask blank used for producing a substrate digging type phase shift mask, which is a structure in which a light shielding film and an etching mask film are sequentially laminated on a light transmitting substrate, The etching mask film is formed in contact with the light-transmitting substrate, is composed mainly of tantalum and does not substantially contain oxygen, and the etching mask film has a chromium content of 45 atomic% or more and contains oxygen. It is a mask blank characterized by being made of a material having an amount of 30 atomic% or less.

(Configuration 2)
The mask blank according to Configuration 1, wherein the light shielding film is made of a material further containing nitrogen.
(Configuration 3)
3. The mask blank according to Configuration 2, wherein the light shielding film is made of a material having a nitrogen content of less than 62 atomic%.

(Configuration 4)
The light-shielding film has a highly oxidized layer having a content of oxygen in the layer of 60 atomic% or more formed on a surface layer opposite to the light-transmitting substrate. The mask blank according to any one of the above.
(Configuration 5)
The mask blank according to Configuration 4, wherein the high oxide layer has a thickness of 1.5 nm to 4 nm.

(Configuration 6)
The mask blank according to any one of the structures 1 to 5, wherein the light shielding film is made of a material that can be dry-etched to form a pattern using a chlorine-based gas substantially not containing oxygen. is there.

(Configuration 7)
A mask blank used to fabricate a substrate digging type phase shift mask, which has a structure in which a light shielding film in which a lower layer and an upper layer are stacked and an etching mask film are sequentially stacked on a translucent substrate. The lower layer is formed in contact with the light-transmitting substrate, is made of a material mainly containing tantalum and substantially free of oxygen, and the etching mask film has a chromium content of 45 atomic% or more. The mask blank is characterized by being made of a material having an oxygen content of 30 atomic% or less.

(Configuration 8)
The mask blank according to Configuration 7, wherein the upper layer is made of a material containing tantalum as a main component and oxygen.
(Configuration 9)
The lower layer is a mask blank according to Configuration 7 or 8, further comprising a material containing nitrogen.
(Configuration 10)
The lower layer is the mask blank according to Configuration 9, wherein the lower layer is made of a material having a nitrogen content of less than 62 atomic%.

(Configuration 11)
11. The mask blank according to claim 8, wherein the upper layer is made of a material having an oxygen content of 50 atomic% or more.
(Configuration 12)
12. The structure according to any one of Structures 8 to 11, wherein the upper layer is formed with a highly oxidized layer having an oxygen content of 60 atomic% or more in a surface layer opposite to the lower layer. It is a mask blank.

(Configuration 13)
13. The mask blank according to Configuration 12, wherein the content of oxygen in the upper layer is less than the content of oxygen in the highly oxidized layer.
(Configuration 14)
14. The mask blank according to Configuration 12 or 13, wherein the high oxide layer has a thickness of 1.5 nm to 4 nm.

(Configuration 15)
The mask blank according to any one of Structures 7 to 14, wherein the lower layer is made of a material that can be dry-etched to form a pattern using a chlorine-based gas substantially not containing oxygen. .
(Configuration 16)
The mask blank according to any one of Structures 7 to 15, wherein the upper layer is made of a material that is difficult to dry-etch to form a pattern using a chlorine-based gas that does not substantially contain oxygen. .

(Configuration 17)
17. The mask blank according to any one of configurations 1 to 16, wherein the light shielding film has a thickness of less than 60 nm.
(Configuration 18)
18. The mask blank according to claim 1, wherein the etching mask film has a thickness of 5 nm to 15 nm.

(Configuration 19)
The phase shift mask is a mask blank according to any one of configurations 1 to 18, wherein exposure light having a wavelength of 200 nm or less is applied to pattern transfer.

(Configuration 20)
A method of manufacturing a substrate digging type phase shift mask using a mask blank, wherein the mask blank has a structure in which a light shielding film and an etching mask film are sequentially laminated on a light transmitting substrate, The light-shielding film is formed in contact with the light-transmitting substrate, is made of a material mainly containing tantalum and substantially free of oxygen, and the etching mask film has a chromium content of 45 atomic% or more, And a step of forming a resist film having a transfer pattern on the mask blank, and a chlorine-based gas and an oxygen gas using the resist film having the transfer pattern as a mask. Forming a transfer pattern on the etching mask film by dry etching using a mixed gas and an etchant formed with the transfer pattern Using the mask mask film as a mask, a step of forming a transfer pattern on the light shielding film by dry etching using a chlorine-based gas containing substantially no oxygen, and a phase shift pattern on the mask blank on which the transfer pattern is formed A step of forming a resist film, and a step of forming a phase shift pattern by digging the translucent substrate to a predetermined depth by dry etching using a fluorine-based gas using the resist film having the phase shift pattern as a mask. And a step of removing the remaining etching mask film after the phase shift pattern is formed on the translucent substrate.

(Configuration 21)
A method of manufacturing a substrate digging type phase shift mask using a mask blank, wherein the mask blank includes a light shielding film in which a lower layer and an upper layer are stacked on an optically transparent substrate, and an etching mask film sequentially stacked. The lower layer is formed in contact with the light-transmitting substrate, is made of a material mainly containing tantalum and substantially free of oxygen, and the etching mask film has a chromium content of 45. The step of forming a resist film having a transfer pattern on the mask blank, and using the resist film having the transfer pattern as a mask, is made of a material having an atomic% or more and an oxygen content of 30 atomic% or less. Forming a transfer pattern on the etching mask film by dry etching using a mixed gas of chlorine-based gas and oxygen gas, and the transfer pattern A transfer pattern is formed on the upper layer by dry etching using a fluorine-based gas using the etching mask film on which the carbon is formed as a mask, and then the dry etching using a chlorine-based gas substantially containing no oxygen. A step of forming a transfer pattern in a lower layer, a step of forming a resist film having a phase shift pattern on a mask blank on which the transfer pattern is formed, and a fluorine-based gas using the resist film having the phase shift pattern as a mask A step of forming a phase shift pattern by digging the translucent substrate to a predetermined depth by dry etching using, and after forming the phase shift pattern on the translucent substrate, removing the remaining etching mask film And a step of manufacturing a phase shift mask.

(Configuration 22)
The method of manufacturing a phase shift mask according to Configuration 21, wherein the upper layer is made of a material containing tantalum as a main component and oxygen.

ADVANTAGE OF THE INVENTION According to this invention, the mask blank suitable for producing the substrate digging type phase shift mask provided with the light shielding film pattern of the tantalum-type material which does not contain oxygen at least substantially can be provided.
ADVANTAGE OF THE INVENTION According to this invention, the mask blank suitable for producing the substrate digging type | mold phase shift mask provided with the light shielding film pattern which has the lower layer of the tantalum-type material which does not contain oxygen at least substantially can be provided. .
According to the present invention, a mask blank having a structure in which at least a light shielding film of a tantalum material that does not substantially contain oxygen and an etching mask film of a chromium material are laminated, a chlorine gas that does not substantially contain oxygen is used. Reduced etching mask film due to dry etching and damage to light shielding film due to dry etching of fluorine-based gas when digging a substrate, high-precision fine light-shielding film pattern, and phase shift unit with precise phase difference control Substrate digging type phase shift masks can be manufactured.
Further, according to the present invention, oxygen is substantially contained by using a mask blank having a structure in which a light shielding film having a lower layer of a tantalum-based material substantially free of oxygen and a chromium-based material etching mask film are laminated. The etching mask film can be prevented from declining due to dry etching of chlorine-based gas, and damage to the light-shielding film due to dry etching of fluorine-based gas when digging the substrate can be avoided. A substrate excavation type phase shift mask capable of forming a controlled phase shift portion can be manufactured.

It is sectional drawing which shows the layer structure of the mask blank which concerns on the 1st Embodiment of this invention. It is a figure which shows the relationship between the chromium content in an etching mask film | membrane, oxygen content, and the etching rate with respect to chlorine gas. It is a figure which shows the relationship between the chromium content in an etching mask film | membrane, oxygen content, and the etching rate with respect to fluorine-type gas. It is sectional drawing which shows the manufacturing process of the phase shift mask of a substrate digging type which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the layer structure of the mask blank which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the substrate excavation type phase shift mask which concerns on the 2nd Embodiment of this invention.

Hereinafter, the first embodiment of the present invention will be described in detail.
The present invention is a mask blank suitable for producing a substrate digging type phase shift mask having a light-shielding film pattern of a tantalum-based material. Specifically, as described in the above configuration 1, In addition, the light-shielding film and the etching mask film are sequentially stacked, and the light-shielding film is formed in contact with the light-transmitting substrate, and is made of a material containing tantalum as a main component and substantially free of oxygen. The etching mask film is made of a material having a chromium content of 45 atomic% or more and an oxygen content of 30 atomic% or less.

FIG. 1 is a cross-sectional view showing the layer structure of a mask blank according to the present invention.
A mask blank 100 of the present invention shown in FIG. 1 has a structure in which a light shielding film 8 is formed on a light-transmitting substrate 1 and an etching mask film 5 is further laminated on the light shielding film 8.

  The translucent substrate 1 is not particularly limited as long as it has transparency with respect to the exposure wavelength to be used. In the present invention, a synthetic quartz glass substrate and other various glass substrates (for example, soda lime glass, aluminosilicate glass, etc.) can be used. When miniaturizing the pattern of a semiconductor device, it is necessary to shorten the wavelength of an exposure light source used in photolithography when manufacturing a semiconductor device in addition to miniaturization of a mask pattern formed on a phase shift mask. Become. In recent years, as an exposure light source for manufacturing semiconductor devices, the wavelength has been shortened from an KrF excimer laser (wavelength 248 nm) to an ArF excimer laser (wavelength 193 nm). Among various glass substrates, a synthetic quartz glass substrate is particularly suitable as a substrate for a phase shift mask blank of the present invention used for forming a high-definition transfer pattern because it is highly transparent in an ArF excimer laser or shorter wavelength region. It is.

The light shielding film 8 is formed in contact with the translucent substrate 1 and is made of a material containing tantalum as a main component and substantially not containing oxygen. Here, the “main component” means that the content is 50 atomic% or more (hereinafter, synonymous). Further, “substantially free of oxygen” means that the content is less than 10 atomic%, more preferably 5 atomic% or less even when oxygen is contained, as well as when no oxygen is contained. It shall be said.
Examples of the material containing tantalum as a main component include tantalum alone or a tantalum compound in which one or more elements selected from elements such as nitrogen, boron, and carbon are added to tantalum. Also, an alloy containing tantalum as a main component and containing one or more metals selected from hafnium, zirconium, molybdenum, or the like, or one or more elements selected from nitrogen, boron, carbon, etc. are added to this alloy. A compound etc. are also mentioned. In addition, the material containing tantalum as a main component may contain silicon as long as the chlorine-based gas can be etched.

  The material mainly containing tantalum that forms the light-shielding film 8 and does not substantially contain oxygen is basically a material that can be dry-etched by either a fluorine-based gas or a chlorine-based gas that does not substantially contain oxygen. It is. In the present invention, since the light shielding film 8 is in contact with the translucent substrate (glass substrate) 1, as will be described in detail later, sufficient etching is performed between the light shielding film 8 and the substrate 1 when patterning the light shielding film 8. In order to obtain selectivity, dry etching of a chlorine-based gas containing substantially no oxygen is used. Therefore, the material for forming the light shielding film 8 needs to be a material that can be dry-etched with a chlorine-based gas that does not substantially contain oxygen.

  The light shielding film 8 needs to have a predetermined light shielding property. For example, the optical density (OD) of the light shielding film is adjusted to be 2.8 or more, more preferably 3.0 or more at the wavelength 193 nm of ArF excimer laser exposure light. The light shielding film 8 preferably contains nitrogen in a material mainly composed of tantalum. In particular, when the nitrogen content is less than 62 atom% (more preferably 51 atom% or less), desired light shielding properties can be obtained, and at the same time, the surface roughness can be suppressed to 0.60 nm or less by Rq.

  The light-shielding film 8 is preferably formed with a highly oxidized layer having an oxygen content of 60 atomic% or more on the surface layer on the side opposite to the translucent substrate 1 side. The surface layer opposite to the light shielding film 8 includes a surface located on the light shielding film 8 on the opposite side to the light transmissive substrate 1 side, and refers to a layer having a certain depth from this surface. And

  By forming a highly oxidized layer on the surface layer of the light shielding film 8, the produced phase shift mask is resistant to hot water and chemicals, and for short wavelength exposure light having a wavelength of 200 nm or less such as an ArF excimer laser. Irradiation tolerance can be improved. The etching mask film 5 is removed by dry etching with a mixed gas of oxygen and chlorine at the final stage of the production of the phase shift mask. The highly oxidized layer is more resistant to dry etching with a mixed gas of oxygen and chlorine than the other light shielding films 8. For this reason, damage due to dry etching of the upper surface can be minimized.

The light shielding film of the mask blank is desired to have a crystal structure that is microcrystalline, preferably amorphous, and the same applies to the light shielding film of the present invention. For this reason, the crystal structure in the light shielding film is unlikely to be a single structure, and a plurality of crystal structures are likely to be mixed. Therefore, in the case of a highly oxidized layer having an oxygen content of 60 atomic% or more, TaO bonds, Ta ₂ O ₃ bonds, TaO ₂ bonds, and Ta ₂ O ₅ bonds are likely to be mixed. As the abundance ratio of the Ta ₂ O ₅ bond increases in the high oxide layer, chemical resistance, ArF light resistance, and dry etching resistance by a mixed gas of oxygen and chlorine are improved.

When the oxygen content in the high oxide layer is 60 atomic% or more and less than 66.7 atomic%, the bonding state of tantalum and oxygen in the layer tends to be mainly Ta ₂ O ₃ bonds. It is considered that the TaO bond, which is the most unstable bond, is considered to increase, and is considered to be very small as compared with the case where the oxygen content in the layer is less than 60 atomic%.
In addition, when the oxygen content in the high oxide layer is 66.7 atomic% or more, it is considered that the bonding state between tantalum and oxygen in the layer tends to be mainly composed of TaO ₂ bonds. The TaO bond, which is the most unstable bond, and the Ta ₂ O ₃ bond, which is the next unstable bond, are considered to be very few.

When the oxygen content in the high oxide layer is 68 atomic% or more, the bonding state of tantalum and oxygen in the layer is not only mainly composed of TaO ₂ bonds but also Ta ₂ O ₅ bonds. The ratio is also expected to increase. At such an oxygen content, Ta ₂ O ₃ bonds rarely exist and TaO bonds cannot exist.
Furthermore, when the oxygen content in the high oxide layer is 71.4 atomic%, it is considered that the bonding state between tantalum and oxygen in the layer is substantially only Ta ₂ O ₅ bonds. Such a state is most preferable because chemical resistance, ArF light resistance, and dry etching resistance by a mixed gas of oxygen and chlorine are greatly enhanced.

As a method for forming a highly oxidized layer on the surface layer of the light shielding film 8, for example, a substrate on which the light shielding film 8 is formed on the translucent substrate 1 is treated with warm water, ozone-containing water treatment, and oxygen. In addition to heat treatment in gas, ultraviolet irradiation treatment in oxygen-containing gas, O ₂ plasma treatment, etc., methods such as natural oxidation can be mentioned, but a highly oxidized layer with a uniform thickness can be formed, From the viewpoint of productivity, a method using each surface treatment other than the method using natural oxidation is particularly suitable.

  The high oxide layer preferably has a thickness of 1.5 nm or more and 4 nm or less in order to obtain the above-described effects. If the thickness is less than 1.5 nm, sufficient effects cannot be obtained, and if it exceeds 4 nm, the influence on the surface reflectance becomes large, and control for obtaining a predetermined surface reflectance becomes difficult. Further, it becomes difficult to pattern the light shielding film 8 only by dry etching with respect to chlorine gas substantially not containing oxygen. Balance between each aspect of ensuring the optical density of the entire light shielding film, chemical resistance, ArF light resistance, improvement of dry etching resistance by mixed gas of oxygen and chlorine, and improvement of dry etching rate for chlorine gas containing substantially no oxygen Considering this, the thickness of the highly oxidized layer is more preferably 1.5 nm or more and 3 nm or less.

  The light shielding film 8 preferably has a thickness of less than 60 nm.

  The etching mask film 5 has a function of preventing the light-shielding film pattern from being etched by dry etching with a fluorine-based gas when the substrate is dug in a mask manufacturing process (described in detail later). . As described above, in the case of the configuration without the etching mask film 5, the resist pattern of the substrate digging portion is formed after forming the light shielding film pattern. However, due to circumstances such as drawing accuracy, the original digging portion of the substrate digging portion is formed. Since a wider space portion including a margin than the width is formed, a portion where the surface of the light shielding film is exposed near the edge of the light shielding film pattern is generated, and subsequently, the dryness by the fluorine-based gas when the substrate is dug is generated. The exposed light shielding film may be etched by the etching. In the present invention, by laminating the etching mask film 5 on the light shielding film 2, it is possible to prevent the light shielding film pattern from being etched by dry etching with a fluorine-based gas when the substrate is dug. Further, the etching mask film 5 also has a function as an etching mask when a transfer pattern is formed on the light shielding film 8.

Therefore, the etching mask film 5 needs not only to have resistance to dry etching with a fluorine-based gas at the time of etching the translucent substrate 1, for example, but also at the time of etching the light shielding film 8 of tantalum nitride, for example. It is also necessary to have resistance to dry etching with a chlorine-based gas that does not substantially contain oxygen. At the same time, it is also necessary to be a material that can be dry-etched by other than these etching gases.
Therefore, in the present invention, the etching mask film 5 is formed from a material containing chromium as a main component. Examples thereof include chromium and a chromium compound in which one or more elements selected from elements such as oxygen, nitrogen, and carbon are added to chromium. Further, from the viewpoint of making the resist film thickness for forming the transfer pattern on the etching mask film 5 as thin as possible, the oxygen content in the chromium-based material forming the etching mask film 5 is increased to increase the etching mask. It is desired to improve the etching rate of the film 5.

However, the present inventor has considered that all conditions required for the etching mask film 5 of the present invention are not necessarily satisfied as long as the chromium-based material is used. Therefore, dry etching using a chlorine-based gas (Cl ₂ ) as an etching gas and dry etching using a fluorine-based gas (CF ₄ ) as an etching gas for each of the eight sample films of chromium-based materials shown in Table 1 are performed. An experiment was conducted to confirm the etching rate of each sample film. FIG. 2 shows the etching rate of each sample film with respect to chlorine-based gas (Cl ₂ ), and FIG. 3 shows the etching rate of each sample film with respect to fluorine-based gas (CF ₄ ).

  In FIG. 2, the relationship between the oxygen content of each sample film and the etching rate with respect to the chlorine-based gas is plotted with ■, and the relationship between the chromium content of each sample film with the etching rate with respect to the chlorine-based gas is plotted with a triangle. Show. Note that the symbols assigned to the plots ▪ and ▲ in FIG. 2 correspond to the symbols of the sample film. From this result, it can be seen that there is a correlation between the oxygen content and the etching rate for the chlorine-based gas. Moreover, it turns out that the influence of containing nitrogen and carbon in a sample film | membrane is also low. On the other hand, it can be seen that the correlation between the chromium content and the etching rate for the chlorine-based gas is low.

  Further, in the result of FIG. 2, when the oxygen content in the chromium-based material film is larger than 30%, the degree of increase in the etching rate with respect to the chlorine-based gas is increased, and the etching rate itself is 6.0 nm / min or more. It turns out that it becomes high. If the resistance of the chlorine-based gas substantially free of oxygen to dry etching is low, the light-shielding film 8 made of, for example, tantalum nitride is dried with a chlorine-based gas substantially free of oxygen using the pattern of the etching mask film 5 as a mask. When etching is performed, the edge portion (side wall) and the surface of the pattern of the etching mask film 5 may be etched and deteriorated. As a result of examining the experimental results of FIG. 2 and the like, it was concluded that the oxygen content in the chromium-based material forming the etching mask film 5 needs to be 30 atomic% or less.

  On the other hand, in FIG. 3, the relationship between the oxygen content of each sample film and the etching rate with respect to the fluorine-based gas is plotted with ■, and the relationship between the chromium content of each sample film with the etching rate with respect to the fluorine-based gas is plotted with ▲. Respectively. Note that the symbols assigned to the plots ▪ and ▲ in FIG. 3 correspond to the symbols of the sample film. From this result, it can be seen that there is a correlation between the chromium content and the etching rate for the fluorine-based gas. Moreover, it turns out that the influence of containing nitrogen and carbon in a sample film | membrane is also low. On the other hand, it can be seen that the correlation between the oxygen content and the etching rate for the fluorine-based gas is low. That is, it is not sufficient for the etching mask film 5 of the present invention to specify only the oxygen content in the chromium-based material.

  In addition, the result of FIG. 3 shows that when the chromium content in the chromium-based material film is less than 45 atomic%, the etching rate increases with respect to the fluorine-based gas. If the resistance of the fluorine-based gas to dry etching is low, the surface of the etching mask film 5 is exposed when the substrate is dug by performing dry etching with a fluorine-based gas using the resist film having the pattern of the substrate digging portion as a mask. The etched portion disappears by etching, the surface of the light shielding film 8 is exposed, and further, the light shielding film 8 may disappear by etching. As a result of examining the experimental results of FIG. 3 and the like, it was concluded that the chromium content in the chromium-based material forming the etching mask film 5 needs to be 45 atomic% or more.

Taking the above into consideration, in the present invention, the etching mask film 5 has a chromium content in the material of 45 atomic% or more and an oxygen content of 30 atomic% or less.
If the chromium content in the material of the etching mask film 5 is 60 atomic% or more, the etching rate with respect to the fluorine-based gas can be 0.8 nm / min or less, and the film thickness of the etching mask film 5 can be reduced. It is desirable to be able to make it thinner. Further, when the oxygen content in the material of the etching mask film 5 is 20 atomic% or less, the etching rate with respect to a chlorine-based gas containing substantially no oxygen can be 5.0 nm / min or less. The film thickness of the mask film 5 can be further reduced. Furthermore, when the oxygen content is 15 atomic% or less, the etching rate with respect to a chlorine-based gas substantially not containing oxygen can be 4.0 nm / min or less, which is still desirable.

  Further, the film thickness of the etching mask film 5 is not particularly limited in the present invention, but the film thickness is 5 nm or more and 15 nm or less from the viewpoint of sufficiently exerting the above function. preferable. If the film thickness is less than 5 nm, sufficient function cannot be obtained, and if it exceeds 15 nm, the resist film thickness cannot be reduced from the viewpoint of miniaturization, which is not preferable.

  As a method for forming the light shielding film 8 and the etching mask film 5 on the translucent substrate 1, for example, a sputtering film forming method is preferable, but in the present invention, it is not necessary to be limited to the sputtering film forming method. .

  The mask blank of the present invention described above is a transfer mask used in an exposure apparatus that uses exposure light (ArF excimer laser or the like) having a short wavelength of 200 nm or less, in which a fine transfer pattern is required, as an exposure light source. This is a mask blank suitable for producing a substrate digging type phase shift mask provided with a light-shielding film pattern of a tantalum material.

The present invention also provides a method of manufacturing a substrate digging type phase shift mask.
FIG. 4 is a cross-sectional view showing a manufacturing process of a substrate excavation type phase shift mask according to the present invention.
A method for manufacturing a substrate digging type phase shift mask according to the present invention will be described in accordance with the manufacturing process shown in FIG.
The details of the configuration of the mask blank 100 (see FIG. 4A) used in the present invention are as described above.

First, for example, a positive resist film 6 is formed on the mask blank 100 (see FIG. 4B).
Next, a desired pattern is drawn on the resist film 6 formed on the mask blank 100, and after the drawing, development processing is performed to form a resist film 6a having a desired transfer pattern (FIG. 4 ( c)).
Next, using the resist film 6a having this transfer pattern as a mask, a transfer pattern 5a is formed on the etching mask film 5 by dry etching (see FIG. 4C). For the etching mask film 5 containing chromium as a main component of the present invention, it is preferable to use a mixed gas of a chlorine-based gas and an oxygen gas as a dry etching gas.

Here, the remaining resist film 6a may be peeled off (see FIG. 4D).
Next, dry etching of the light shielding film 8 is performed using the etching mask film 5a on which the transfer pattern is formed as a mask. The light-shielding film 8 is dry-etched using a chlorine-based gas that does not substantially contain oxygen as the dry etching gas. Examples of the chlorine-based gas used for the dry etching of the light shielding film 8 include Cl ₂ , SiCl ₄ , CHCl ₃ , CH ₂ Cl ₂ , CCl ₄ , and BCl ₃ . In the present invention, the tantalum-based light-shielding film 8 in contact with the light-transmitting substrate 1 is dry-etched with a chlorine-based gas, so that the tantalum-based light-shielding film 8 and the light-transmitting substrate (glass substrate) 1 are sufficient. Etching selectivity can be obtained. Thus, a predetermined transfer pattern 8a is formed on the tantalum-based light shielding film 8 (see FIG. 4E).

  In the present invention, the etching mask film 5 containing chromium as a main component has an oxygen content of 30 atomic% or less and has sufficient resistance to dry etching of a chlorine-based gas that does not substantially contain oxygen. When the light shielding film 8 is dry-etched with a chlorine-based gas that does not substantially contain oxygen, there is no problem that the edge portions and the surface of the pattern of the etching mask film 5 are etched and deteriorated.

Next, a resist film 7 is again formed on the entire surface of the mask blank on which the transfer pattern is formed (see FIG. 4F), and a substrate digging portion (phase shift portion) is formed with respect to the resist film 7. A phase shift pattern for forming the pattern is drawn, and after the drawing, the resist film 7 is developed to form a resist film 7a having a phase shift pattern (see FIG. 4G).
As described above, the resist film 7a forms a wider space portion with a margin slightly larger than the width of the original digging portion of the substrate due to circumstances such as drawing accuracy. As a result, a portion where the surface of the etching mask film is exposed in the vicinity of the edge of the pattern 5a of the etching mask film is generated.

Next, using the resist film 7a having the phase shift pattern as a mask, the translucent substrate 1 is dug to a predetermined depth by dry etching using a fluorine-based gas to form the phase shift pattern 1a on the translucent substrate 1. (See FIG. 4 (h)). At this time, the etching time is adjusted so that the digging depth of the substrate becomes a predetermined depth. Examples of the fluorine-based gas used for dry etching for digging the translucent substrate 1 include CHF ₃ , CF ₄ , C ₂ F ₆ , and C ₄ F ₈ .

  Finally, the remaining resist film 7a is peeled off (see FIG. 4 (i)), and the etching mask film 5a on the surface is removed by, for example, the same dry etching as described above, so that the substrate digging type phase shift mask 200 is obtained. Is obtained (see FIG. 4J).

As described above, after the formation of the light shielding film pattern 8a, the resist pattern 7a for the substrate digging portion is formed. However, in order to form a space portion wider than the width of the original digging portion due to circumstances such as drawing accuracy (FIG. 4G), the light shielding film pattern 8a is formed unless the surface etching mask film 5a is present. A portion where the surface of the light shielding film pattern 8a is exposed in the vicinity of the edge of is formed. Subsequently, using the resist pattern 7a of the substrate digging portion as a mask, the substrate is dug by dry etching. However, the tantalum-based light-shielding film has low resistance to dry etching by a fluorine-based gas when the substrate is dug. Due to the above circumstances, the exposed surface of the light shielding film pattern 8a may be etched. In the present invention, since the etching mask film 5a having resistance to the dry etching of the fluorine-based gas is laminated on the light-shielding film pattern 8a, the light-shielding film pattern 8a has a fluorine-based gas when the substrate is dug. It is possible to prevent etching by dry etching.
In addition, as described above, when the light shielding film pattern 8a is formed (FIG. 4E), the etching mask film pattern 5a is not reduced, so that the engraved portion is formed in the translucent substrate 1 thereafter. During the dry etching with the fluorine-based gas for forming the tantalum-based light shielding film pattern 8a under the etching mask film pattern 5a, the etching damage is not caused.

  As described above, according to the present invention, using a mask blank having a structure in which a tantalum-based light-shielding film and a chromium-based etching mask film are stacked, a chlorine-based material that does not substantially contain oxygen, which is a problem of the prior art. Reduces the etching mask film due to dry etching of gas and damage to the light shielding film due to dry etching of fluorine-based gas when digging the substrate, and accurately places a precise transfer pattern (light shielding film pattern). A substrate digging type phase shift mask capable of forming a phase shift pattern in which the phase difference is controlled is obtained.

Hereinafter, the second embodiment of the present invention will be described in detail.
The present invention is a mask blank suitable for producing a substrate digging type phase shift mask having a light-shielding film pattern of a tantalum-based material. Specifically, as described in the above configuration 7, In addition, a light shielding film in which a lower layer (light shielding layer) and an upper layer (surface antireflection layer) are laminated, and an etching mask film are sequentially laminated, and the lower layer is formed in contact with the translucent substrate. And the etching mask film is made of a material having a chromium content of 45 atomic% or more and an oxygen content of 30 atomic% or less. It is characterized by this.

FIG. 5 is a cross-sectional view showing the layer structure of the mask blank according to the present invention.
In the mask blank 10 of the present invention shown in FIG. 5, a light shielding film 2 in which a lower layer 3 and an upper layer 4 are laminated is formed on a translucent substrate 1, and an etching mask film 5 is further laminated on the light shielding film 2. Structure. Matters concerning the translucent substrate 1 are the same as those in the first embodiment.

  The lower layer (light shielding layer) 3 is formed in contact with the translucent substrate 1 and is formed of a material containing tantalum as a main component and substantially not containing oxygen. Matters relating to the material of the lower layer 3 are the same as those of the light shielding film 8 of the first embodiment.

  The lower layer 3 needs to have a predetermined light shielding property in a laminated structure with the upper layer (surface antireflection layer) 4. For example, the optical density (OD) of the light shielding film is adjusted to be 2.8 or more, more preferably 3.0 or more at the wavelength 193 nm of ArF excimer laser exposure light. For this purpose, the lower layer 3 preferably contains nitrogen in a material mainly composed of tantalum. In particular, when the nitrogen content is less than 62 atomic% (more preferably 51 atomic% or less), desired light shielding properties can be obtained, and at the same time, the surface roughness of the lower layer 3 can be suppressed to 0.60 nm or less by Rq. it can. Further, it is preferable that the nitrogen content is 7 atomic% or more because the back surface reflectance of the light shielding film can be suppressed to less than 40%.

  The upper layer (surface antireflection layer) 4 is formed of a material containing tantalum as a main component and containing oxygen, a material containing a transition metal and silicon, or the like. Examples of the transition metal include tantalum, molybdenum, zirconium, hafnium, titanium, nickel, chromium, vanadium, iron, zinc, niobium, ruthenium, rhodium, palladium, tungsten, iridium, silver, gold, platinum, and the like. In particular, when the upper layer is formed of a material containing tantalum as a main component and containing oxygen, a target of the same tantalum material can be used for the lower layer and the upper layer when the light shielding film is formed on the translucent substrate by the sputtering method. Therefore, it is preferable. Examples of the material mainly containing tantalum include tantalum alone or a tantalum compound in which one or more elements selected from elements such as nitrogen, boron, and carbon are added to tantalum. Also, an alloy containing tantalum as a main component and containing one or more metals selected from hafnium, zirconium, molybdenum, or the like, or one or more elements selected from nitrogen, boron, carbon, etc. are added to this alloy. A compound etc. are also mentioned.

  When the light shielding film 2 of the mask blank is formed of a material containing tantalum as a main component (hereinafter also referred to as “tantalum-based material” as appropriate) and a light shielding film having a surface antireflection function of a certain degree or more is configured. At least a lower layer (light-shielding layer) 3 and an upper layer (surface antireflection layer) 4 need to be laminated. For the upper layer 4, a tantalum-based material containing oxygen (for example, oxidized tantalum) is used. Is preferred. For example, tantalum oxide is a material that has a remarkably slow etching rate with respect to a chlorine-based gas that does not substantially contain oxygen and is difficult to dry-etch. Therefore, in the present invention, etching is performed by dry etching with a fluorine-based gas.

  The upper layer 4 preferably has an oxygen content of 50 atomic% or more. An oxygen content of 50 atomic% or more is preferable because the surface reflectance of the light shielding film can be suppressed to less than 30%.

  The upper layer 4 is preferably formed on the surface opposite to the lower layer 3 with a highly oxidized layer having an oxygen content of 60 atomic% or more on the surface layer. The surface layer opposite to the lower layer includes a surface of the upper layer 4 located on the opposite side of the lower layer 3 side, and refers to a layer having a certain depth from this surface.

  Due to the formation of a highly oxidized layer on the surface layer of the upper layer 4, the produced phase shift mask is resistant to hot water and chemicals, and moreover, for example, irradiation with short wavelength exposure light having a wavelength of 200 nm or less such as ArF excimer laser Resistance can be improved. The etching mask film 5 is removed by dry etching with a mixed gas of oxygen and chlorine at the final stage of the production of the phase shift mask. The highly oxidized layer is more resistant to dry etching with a mixed gas of oxygen and chlorine than the other upper layers. For this reason, damage due to dry etching of the upper surface can be minimized.

  Matters relating to the high oxide layer are the same as those of the high oxide layer of the light shielding film 8 of the first embodiment. The high oxide layer preferably has a thickness of 1.5 nm or more and 4 nm or less in order to obtain the above-described effects. If the thickness is less than 1.5 nm, sufficient effects cannot be obtained, and if it exceeds 4 nm, the influence on the surface reflectance becomes large, and control for obtaining a predetermined surface reflectance becomes difficult. The thickness of the high oxide layer is 1.5 nm considering the balance between the viewpoints of ensuring the optical density of the entire light-shielding film, chemical resistance, ArF light resistance, and improving dry etching resistance with a mixed gas of oxygen and chlorine. More preferably, the thickness is 3 nm or less.

  Moreover, it is preferable that the said light shielding film 2 consisting of the laminated structure of the said lower layer (light shielding layer) 3 and the upper layer (surface antireflection layer) 4 is less than 60 nm. The upper layer has a low optical density in order to provide a surface antireflection function. Therefore, it is desirable that the upper layer be as thin as possible if the function can be exhibited. For example, the upper layer is desirably 5 nm to 15 nm, and more desirably 5 nm to 10 nm.

  The etching mask film 5 has a function of preventing the light-shielding film pattern from being etched by dry etching with a fluorine-based gas when the substrate is dug in a mask manufacturing process (described in detail later). . As described above, in the case of the configuration without the etching mask film 5, the resist pattern of the substrate digging portion is formed after forming the light shielding film pattern. However, due to circumstances such as drawing accuracy, the original digging portion of the substrate digging portion is formed. Since a wider space part including the margin than the width is formed, a part where the surface of the light shielding film (upper layer) is exposed is formed near the edge of the light shielding film pattern, and then the fluorine system when the substrate is dug. By dry etching with gas, there is a possibility that the exposed light shielding film (upper layer) from the surface to the lower layer may be etched. In the present invention, by laminating the etching mask film 5 on the light shielding film 2, it is possible to prevent the light shielding film pattern from being etched by dry etching with a fluorine-based gas when the substrate is dug. Further, the etching mask film 5 also has a function as an etching mask when a transfer pattern is formed on the light shielding film 2 formed by stacking the light shielding layer 3 and the surface antireflection layer 4.

  Therefore, the etching mask film 5 needs not only to have resistance to dry etching with a fluorine-based gas when etching the upper layer 4 of tantalum oxide or the translucent substrate 1, for example, but also, for example, a lower layer of tantalum nitride. It is necessary to have resistance to dry etching with a chlorine-based gas that does not substantially contain oxygen when etching 3. At the same time, it is also necessary to be a material that can be dry-etched by other than these etching gases. Other matters relating to the etching mask film 5 are the same as those of the etching mask film 5 of the first embodiment.

  As a method for forming the light-shielding film 2 in which the lower layer 3 and the upper layer 4 are laminated on the translucent substrate 1 and the etching mask film 5, for example, a sputtering film forming method is preferable. It is not necessary to limit to the membrane method.

  The mask blank of the present invention described above is a transfer mask used in an exposure apparatus that uses exposure light (ArF excimer laser or the like) having a short wavelength of 200 nm or less, in which a fine transfer pattern is required, as an exposure light source. This is a mask blank suitable for manufacturing a substrate digging type phase shift mask having a light shielding film pattern having a lower layer of a tantalum material.

The present invention also provides a method of manufacturing a substrate digging type phase shift mask.
FIG. 6 is a cross-sectional view showing a manufacturing process of a substrate excavation type phase shift mask according to the present invention.
In accordance with the manufacturing process shown in FIG. 6, a method for manufacturing a substrate digging type phase shift mask according to the present invention will be described.
Details of the configuration of the mask blank 10 (see FIG. 6A) used in the present invention are as described above.

First, for example, a positive resist film 6 is formed on the mask blank 10 (see FIG. 6B).
Next, a desired pattern is drawn on the resist film 6 formed on the mask blank 10, and after the drawing, development processing is performed to form a resist film 6a having a desired transfer pattern (FIG. 6 ( c)).
Next, using the resist film 6a having this transfer pattern as a mask, a transfer pattern 5a is formed on the etching mask film 5 by dry etching (see FIG. 6C). For the etching mask film 5 containing chromium as a main component of the present invention, it is preferable to use a mixed gas of a chlorine-based gas and an oxygen gas as a dry etching gas.

Here, the remaining resist film 6a may be peeled off (see FIG. 6D).
Next, dry etching of the light shielding film 2 is performed using the etching mask film 5a on which the transfer pattern is formed as a mask. First, the upper surface antireflection layer 4 is dry-etched using a fluorine-based gas as a dry etching gas, and then a lower layer is formed using a chlorine-based gas substantially free of oxygen as a dry etching gas. The light shielding layer 3 is dry-etched. As the fluorine-based gas used for the dry etching of the surface antireflection layer 4, the one used when the light-transmitting substrate 1 is dry-etched in the first embodiment can be applied. As the chlorine-based gas used for the dry etching of the light shielding layer 3, the one used when the light shielding film 8 is dry etched in the first embodiment can be applied. In the present invention, the tantalum-based light-shielding layer 3 in contact with the light-transmitting substrate 1 is dry-etched with a chlorine-based gas, so that the tantalum-based light-shielding layer 3 and the light-transmitting substrate (glass substrate) 1 are sufficient. Etching selectivity can be obtained. Thus, a predetermined transfer pattern (light-shielding film pattern composed of a laminate of the light-shielding layer pattern 3a and the surface anti-reflection layer pattern 4a) 2a is formed on the tantalum-based light-shielding film 2 having a laminated structure of the light-shielding layer 3 and the surface anti-reflection layer 4 ( (Refer FIG.6 (e)).

  In the present invention, the etching mask film 5 containing chromium as a main component has an oxygen content of 30 atomic% or less and has sufficient resistance to dry etching of a chlorine-based gas that does not substantially contain oxygen. When the tantalum-based light-shielding layer 3 under the light-shielding film 2 is dry-etched with a chlorine-based gas that does not substantially contain oxygen, the edge portion and surface of the pattern of the etching mask film 5 are etched and deteriorated. Does not happen.

Next, a resist film 7 is again formed on the entire surface of the mask blank on which the transfer pattern is formed (see FIG. 6F), and a substrate digging portion (phase shift portion) is formed with respect to the resist film 7. A phase shift pattern for forming the film is drawn, and after the drawing, the resist film 7 is developed to form a resist film 7a having a phase shift pattern (see FIG. 6G).
As described above, the resist film 7a forms a wider space portion with a margin slightly larger than the width of the original digging portion of the substrate due to circumstances such as drawing accuracy. As a result, a portion where the surface of the etching mask film is exposed in the vicinity of the edge of the pattern 5a of the etching mask film is generated.

Next, using the resist film 7a having this phase shift pattern as a mask, the translucent substrate 1 is dug to a predetermined depth by dry etching using a fluorine-based gas (for example, the above-mentioned CF ₄ gas). Then, the phase shift pattern 1a is formed (see FIG. 6H). At this time, the etching time is adjusted so that the digging depth of the substrate becomes a predetermined depth.

  Finally, the remaining resist film 7a is peeled off (see FIG. 6 (i)), and the etching mask film 5a on the surface is removed by, for example, the same dry etching as described above, so that the substrate digging type phase shift mask 20 is obtained. Is obtained (see FIG. 6 (j)).

As described above, after forming the light shielding film pattern 2a, the resist pattern 7a of the substrate digging portion is formed. However, a space portion wider than the width of the original digging portion of the substrate is formed due to circumstances such as drawing accuracy. Therefore (FIG. 6G), if the surface etching mask film 5a does not exist, a portion where the surface of the light shielding film pattern 2a (surface antireflection layer pattern 4a) is exposed near the edge of the light shielding film pattern 2a is generated. . Subsequently, using the resist pattern 7a of the substrate digging portion as a mask, the substrate is dug by dry etching. However, the tantalum-based light-shielding film has low resistance to dry etching by a fluorine-based gas when the substrate is dug. The exposed surface of the light shielding film pattern 2a (surface antireflection layer pattern 4a) may be etched due to the above circumstances. In the present invention, since the etching mask film 5a having resistance to the dry etching of the fluorine-based gas is laminated on the light-shielding film pattern 2a, the light-shielding film pattern 2a has a fluorine-based gas when the substrate is dug. It is possible to prevent etching by dry etching.
In addition, as described above, when the light shielding film pattern 2a is formed (FIG. 6E), the etching mask film pattern 5a does not deteriorate, so that the engraved portion is formed in the translucent substrate 1 thereafter. During dry etching with a fluorine-based gas for forming the tantalum-based light-shielding film pattern 2a under the etching mask film pattern 5a (particularly the surface antireflection layer pattern 4a immediately below) is not damaged by etching.

  As described above, according to the present invention, a mask blank having a structure in which a light-shielding film having a lower layer of a tantalum-based material that does not substantially contain oxygen and a chromium-based etching mask film is used. It is possible to avoid deterioration of the etching mask film due to dry etching of chlorine-based gas that does not substantially contain oxygen, and damage to the light-shielding film due to dry etching of fluorine-based gas when digging the substrate. A substrate digging type phase shift mask capable of forming a transfer pattern (light shielding film pattern) and a phase shift pattern in which the phase difference is accurately controlled is obtained.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.
Example 1
A mask blank was produced as follows.
The substrate to be used is a synthetic quartz glass substrate (size: 152.4 mm × 152.4 mm, thickness: 6.35 mm).
The glass substrate was put into a predetermined film forming apparatus (sputtering apparatus), and the following light shielding film was formed on the glass substrate.
Specifically, a tantalum (Ta) target is used as a sputtering target, a mixed gas atmosphere of xenon (Xe) and nitrogen (N ₂ ) is used, and a 48 nm-thick TaN film (film) is formed by reactive sputtering (DC sputtering). (Ta = 85 atomic%, N = 15 atomic%) was formed to form a tantalum-based light-shielding film. The film composition of the light-shielding film is an analysis result by AES (Auger electron spectroscopy).

  Here, the substrate on which the tantalum-based light-shielding film is formed is once taken out from the film forming apparatus and stored before natural oxidation proceeds (for example, within 1 hour after film formation) or in an environment where natural oxidation does not proceed after film formation. Later, it was immersed in deionized water (DI water: deionized water) at 90 ° C. for 120 minutes to perform hot water treatment (surface treatment). When the tantalum-based light-shielding film after the hot water treatment was analyzed by AES, it was confirmed that a highly oxidized layer having a thickness of 2 nm was formed on the surface layer of the light-shielding film (the surface layer opposite to the glass substrate). The oxygen content of this highly oxidized layer was 71.4% to 67 atomic%. This tantalum-based light-shielding film is adjusted so that the optical density (OD) is 3.0 at a wavelength of 193 nm of ArF excimer laser exposure light.

Next, the substrate on which the tantalum-based light-shielding film was formed was again put into the film forming apparatus, and the following etching mask film was formed on the tantalum-based light-shielding film.
Specifically, a chromium (Cr) target is used as a sputtering target, and a mixed gas atmosphere of argon (Ar), nitrogen (N 2), carbon dioxide (CO ₂ ), and helium (He) is used, and reactive sputtering (DC sputtering) is performed. ) To form a 10 nm thick CrOCN film (etching mask film, film composition Cr = 48.9 atomic%, O = 26.4 atomic%, C = 10.6 atomic%, N = 14.1 atomic%). Filmed. In addition, the film | membrane composition of each layer is an analysis result by RBS (Rutherford backscattering analysis method).

  As described above, a mask blank in which a TaN light-shielding film and a CrOCN etching mask film were sequentially laminated on a glass substrate was produced.

Next, using the above mask blank, a substrate digging type Levenson type phase shift mask was fabricated according to the process shown in FIG.
First, a chemically amplified positive resist film for electron beam drawing (PRL009 manufactured by Fuji Film Electronics Materials) was formed as a resist film on the mask blank. The resist film was formed by spin coating using a spinner (rotary coating apparatus). After applying the resist film, a predetermined heat drying treatment was performed. The film thickness of the resist film was 100 nm.

Next, a transfer pattern including a DRAM hp45 nm line and space (L & S) pattern is drawn on the resist film formed on the mask blank using an electron beam drawing apparatus, and then developed with a predetermined developer. Thus, a resist pattern was formed.
Next, using the resist pattern as a mask, the etching mask film was dry-etched to form a predetermined transfer pattern on the etching mask film. A mixed gas of Cl ₂ and O ₂ was used as a dry etching gas.

Next, after removing the remaining resist pattern, the light shielding film was dry etched using the etching mask film on which the transfer pattern was formed as a mask. As a dry etching gas, a Cl ₂ gas containing no oxygen was used. Thus, a predetermined transfer pattern (light shielding film pattern) was formed on the TaN light shielding film.
Using another mask blank, the transfer pattern formed on the etching mask film under the same conditions was broken and observed in detail with a transmission electron microscope (TEM). Was not observed.

Next, the same resist film as above is formed again on the entire surface, and a phase shift pattern is drawn to form a substrate digging portion (phase shift portion). After the drawing, the resist film is developed to form a phase shift pattern. A resist pattern was formed.
Next, using the resist pattern having the phase shift pattern as a mask, the glass substrate was dug to a predetermined depth by dry etching using a fluorine-based gas (CF ₄ gas) to form a phase shift pattern on the glass substrate. At this time, the etching time was adjusted so that the digging depth of the substrate was 173 nm.

The remaining resist pattern was peeled off, and the etching mask film on the surface was removed by the same dry etching as above to obtain a Levenson type phase shift mask.
In the phase shift mask thus obtained, a fine pattern including an L & S pattern of DRAM hp45 nm was formed with good pattern accuracy, and no etching damage of the tantalum-based light shielding film pattern was observed. Further, in order to confirm the cross-sectional shape of the phase shift pattern formed on the substrate, the phase shift mask for evaluation prepared in the same manner as above was broken, and the pattern cross section was observed with a transmission electron microscope (TEM). However, it was confirmed that the substrate thickness between the digging portion and the non-digging portion was accurately controlled to a predetermined value, and the pattern depth was uniform.

  Next, using the obtained Levenson-type phase shift mask, a step of exposing and transferring the transfer pattern to the resist film on the semiconductor wafer that is the transfer target was performed. As the exposure apparatus, an immersion type apparatus using an ArF excimer laser as a light source and annular illumination was used. Specifically, the Levenson type phase shift mask of Example 1 was set on the mask stage of the exposure apparatus, and exposure transfer was performed on the resist film for ArF immersion exposure on the semiconductor wafer. The resist film after the exposure was subjected to a predetermined development process to form a resist pattern. Furthermore, a circuit pattern including an L & S pattern of DRAM hp 45 nm was formed on the semiconductor wafer using the resist pattern.

  When the circuit pattern on the obtained semiconductor wafer was confirmed with a transmission electron microscope (TEM), the specification of the DRAM hp45 nm L & S pattern was sufficiently satisfied. That is, it has been confirmed that the Levenson type phase shift mask of Example 1 can sufficiently transfer a circuit pattern including an L & S pattern of DRAM hp45 nm onto a semiconductor wafer.

(Example 2)
A mask blank was produced as follows.
The substrate to be used is a synthetic quartz glass substrate (size: 152.4 mm × 152.4 mm, thickness: 6.35 mm).
The glass substrate was put into a predetermined film forming apparatus (sputtering apparatus), and the following light shielding film was formed on the glass substrate.
Specifically, a tantalum (Ta) target is used as a sputtering target, a mixed gas atmosphere of xenon (Xe) and nitrogen (N ₂ ) is used, and a 42 nm-thick TaN layer (lower layer) is formed by reactive sputtering (DC sputtering). : Light shielding layer, film composition Ta = 85 atomic%, N = 15 atomic%). Subsequently, a mixed gas atmosphere of argon (Ar) and oxygen (O ₂ ) was used, and a TaO layer (upper layer: surface antireflection layer, film composition Ta = 39 atomic%) having a thickness of 9 nm was formed by reactive sputtering (DC sputtering). , O = 59 atomic%) to form a tantalum-based light-shielding film having a two-layer structure having a total film thickness of 50 nm. The film composition of each layer is an analysis result by AES (Auger electron spectroscopy).

  Here, the substrate on which the tantalum-based light-shielding film is formed is once taken out from the film forming apparatus and stored before natural oxidation proceeds (for example, within 1 hour after film formation) or in an environment where natural oxidation does not proceed after film formation. Later, it was immersed in deionized water (DI water: deionized water) at 90 ° C. for 120 minutes to perform hot water treatment (surface treatment). Analysis of the tantalum-based light-shielding film after hot water treatment by AES confirmed the formation of a highly oxidized layer with a thickness of 2 nm on the surface of the TaO surface antireflection layer (surface opposite to the light-shielding layer). It was done. The oxygen content of this highly oxidized layer was 71.4% to 67 atomic%.

  The tantalum-based light-shielding film having this laminated structure is adjusted so that the optical density (OD) is 3.0 at a wavelength of 193 nm of ArF excimer laser exposure light. The surface reflectance of the light shielding film with respect to the wavelength of the exposure light was 25.1%. Moreover, the reflectance (back surface reflectance) of the surface on which the light-shielding film of the translucent substrate 1 was not formed was 38.2%.

  Next, the substrate on which the tantalum-based light-shielding film was formed was put into the film forming apparatus again, and an etching mask film made of CrOCN was formed on the tantalum-based light-shielding film in the same procedure as in Example 1.

  As described above, a mask blank was prepared in which a light shielding film composed of a TaN light shielding layer (lower layer) and a TaO surface antireflection layer (upper layer) and a CrOCN etching mask film were sequentially laminated on a glass substrate.

Next, using the above mask blank, a substrate digging type Levenson type phase shift mask was fabricated according to the process shown in FIG.
First, a chemically amplified positive resist film for electron beam drawing (PRL009 manufactured by Fuji Film Electronics Materials) was formed as a resist film on the mask blank. The resist film was formed by spin coating using a spinner (rotary coating apparatus). After applying the resist film, a predetermined heat drying treatment was performed. The film thickness of the resist film was 100 nm.

Next, after drawing a transfer pattern including an L & S pattern of DRAM hp45 nm on the resist film formed on the mask blank using an electron beam drawing apparatus, the resist pattern is developed with a predetermined developer. Formed.
Next, using the resist pattern as a mask, the etching mask film was dry-etched to form a predetermined transfer pattern on the etching mask film. A mixed gas of Cl ₂ and O ₂ was used as a dry etching gas.

Next, after removing the remaining resist pattern, the light shielding film was dry etched using the etching mask film on which the transfer pattern was formed as a mask. First, dry etching of the upper TaO surface antireflection layer is performed using CF ₄ gas as the dry etching gas, and then the lower TaN light shielding is performed using Cl ₂ gas containing no oxygen as the dry etching gas. The layer was dry etched. Thus, a predetermined transfer pattern (light-shielding film pattern) was formed on the light-shielding film having a laminated structure of the TaN light-shielding layer and the TaO surface antireflection layer.
Using another mask blank, the transfer pattern formed on the etching mask film under the same conditions was broken and observed in detail with a transmission electron microscope (TEM). Was not observed.

Next, the same resist film as above is formed again on the entire surface, and a phase shift pattern is drawn to form a substrate digging portion (phase shift portion). After the drawing, the resist film is developed to form a phase shift pattern. A resist pattern was formed.
Next, using the resist pattern having the phase shift pattern as a mask, the glass substrate was dug to a predetermined depth by dry etching using a fluorine-based gas (CF ₄ gas) to form a phase shift pattern on the glass substrate. At this time, the etching time was adjusted so that the digging depth of the substrate was 173 nm.

The remaining resist pattern was peeled off, and the etching mask film on the surface was removed by the same dry etching as above to obtain a Levenson type phase shift mask.
In the phase shift mask thus obtained, a fine pattern including an L & S pattern of DRAM hp45 nm was formed with good pattern accuracy, and no etching damage of the tantalum-based light shielding film pattern was observed. Further, in order to confirm the cross-sectional shape of the phase shift pattern formed on the substrate, the phase shift mask for evaluation prepared in the same manner as above was broken, and the pattern cross section was observed with a transmission electron microscope (TEM). However, it was confirmed that the substrate thickness between the digging portion and the non-digging portion was accurately controlled to a predetermined value, and the pattern depth was uniform.

  Next, using the obtained Levenson-type phase shift mask, similarly to Example 1, a step of exposing and transferring the transfer pattern to the resist film on the semiconductor wafer as the transfer target was performed. When the circuit pattern on the obtained semiconductor wafer was confirmed with a transmission electron microscope (TEM), the specification of the DRAM hp45 nm L & S pattern was sufficiently satisfied. That is, it was confirmed that the Levenson-type phase shift mask of Example 2 can sufficiently transfer a circuit pattern including an L & S pattern of DRAM hp45 nm onto a semiconductor wafer.

(Comparative Example 1)
A mask blank was produced as follows.
The same glass substrate as in Example 1 was put into a predetermined film forming apparatus (sputtering apparatus), and a TaN layer (light-shielding layer) having a thickness of 42 nm and a film thickness were formed on this glass substrate in the same manner as in Example 1. A 9 nm TaO layer (surface antireflection layer) was formed to form a tantalum-based light-shielding film having a total thickness of 50 nm and a two-layer structure.
Here, the substrate on which the tantalum-based light-shielding film is formed is once taken out from the film forming apparatus and is immersed in deionized water (DI water: deionized water) at 90 ° C. for 120 minutes in the same manner as in Example 1. Treatment). Analysis of the tantalum-based light-shielding film after hot water treatment by AES confirmed the formation of a highly oxidized layer with a thickness of 2 nm on the surface of the TaO surface antireflection layer (surface opposite to the light-shielding layer). It was done. The oxygen content of this highly oxidized layer was 71.4% to 67 atomic%.

Next, the substrate on which the tantalum-based light-shielding film was formed was again put into the film forming apparatus, and the following etching mask film was formed on the tantalum-based light-shielding film.
Specifically, a chromium (Cr) target is used as a sputtering target, a mixed gas atmosphere of argon (Ar) and oxygen (O ₂ ) is used, and a 10 nm thick CrO layer (etching) is performed by reactive sputtering (DC sputtering). Mask film, film composition Cr = 33.7 atomic%, O = 66.3 atomic%) were formed. In addition, the film | membrane composition of each layer is an analysis result by RBS (Rutherford backscattering analysis method).

As described above, a mask blank was prepared in which a light shielding film composed of a TaN light shielding layer and a TaO surface antireflection layer and a CrO etching mask film were sequentially laminated on a glass substrate.
Next, using the mask blank (comparative example), a substrate digging type Levenson type phase shift mask was produced in the same manner as in Example 2.

  When the mask blank of this comparative example is used, a predetermined transfer pattern (light-shielding film pattern) is applied to the light-shielding film of the laminated structure of the TaN light-shielding layer and the TaO surface antireflection layer using the etching mask film on which the transfer pattern is formed as a mask. At the stage of formation, the mask blank was broken, and the transfer pattern formed on the etching mask film was observed in detail with a transmission electron microscope (TEM). It was confirmed that the surface decline occurred. This is because the chromium-containing etching mask film has a high oxygen content, so the resistance to dry etching of a chlorine-based gas that does not substantially contain oxygen decreases, and the TaN light-shielding layer under the light-shielding film substantially contains oxygen. This is presumably because the edge portion and the surface of the pattern of the etching mask film were etched when dry etching was performed with a chlorine-based gas that was not used.

  When the Levenson-type phase shift mask prepared in the same manner as above was broken and observed with a transmission electron microscope (TEM), a portion of the tantalum-based light-shielding film pattern was found to have etching damage or pattern degradation. It was. This is because, when the pattern of the etching mask film is reduced as described above, TaO directly under the etching mask film is formed in the subsequent dry etching with a fluorine-based gas for forming a dug portion in the glass substrate. This is presumably because the surface antireflection layer was damaged by etching or the TaO surface antireflection layer and the TaN light shielding layer were etched. If an etching damage portion exists in a part of such a light shielding film pattern, the pattern transfer accuracy may be lowered when the pattern transfer to the transfer target is performed using this phase shift mask.

  Next, using the obtained Levenson-type phase shift mask, similarly to Example 1, a step of exposing and transferring the transfer pattern to the resist film on the semiconductor wafer as the transfer target was performed. When the circuit pattern on the obtained semiconductor wafer was confirmed with a transmission electron microscope (TEM), there were many shorts and breaks in the L & S pattern part, and the specifications of the L & S pattern of DRAM hp45nm were sufficiently satisfied. It wasn't.

1 Translucent substrate 2, 8 Light shielding film 3 Lower layer (light shielding layer)
4 Upper layer (surface antireflection layer)
5 Etching mask films 6 and 7 Resist film 10 Mask blank 20 Phase shift mask

Claims (20)

A mask blank used for producing a substrate digging type phase shift mask,
It is a structure in which a light shielding film and an etching mask film are sequentially laminated on a light transmitting substrate,
The light shielding film is formed in contact with the translucent substrate, and has a highly oxidized layer on a surface layer opposite to the translucent substrate side,
The highly oxidized layer is made of a material containing tantalum and having an oxygen content of 68 atomic% or more,
The light shielding film other than the high oxide layer is made of a material containing one or more elements selected from nitrogen, boron and carbon in tantalum,
The etching mask film is a material containing one or more elements selected from oxygen, nitrogen and carbon in chromium, having a chromium content of 45 atomic% or more and an oxygen content of more than 0 atomic%. A mask blank comprising a material having an atomic percent or less. The mask blank according to claim 1, wherein the light shielding film other than the high oxide layer is made of tantalum and nitrogen. The mask blank according to claim 2, wherein the light shielding film other than the high oxide layer is made of a material having a nitrogen content of less than 62 atomic%. The high oxidation layer, the mask blank according to any one of claims 1 to 3 thickness is equal to or is 1.5nm or more 4nm or less. The light-shielding film, the mask blank according to any one of claims 1 to 4, characterized in that oxygen from a material capable of dry etching for forming a pattern using substantially free chlorine gas . A mask blank used for producing a substrate digging type phase shift mask,
A light-shielding film in which a lower layer and an upper layer are stacked, and an etching mask film are sequentially stacked on a translucent substrate,
The lower layer is formed in contact with the translucent substrate, and is made of a material containing one or more elements selected from nitrogen, boron, and carbon in tantalum,
The upper layer is mainly composed of tantalum and made of a material containing oxygen, and has a highly oxidized layer on the surface layer opposite to the lower layer,
The highly oxidized layer is made of a material containing tantalum and having an oxygen content of 68 atomic% or more,
The etching mask film is a material containing one or more elements selected from oxygen, nitrogen and carbon in chromium, having a chromium content of 45 atomic% or more and an oxygen content of more than 0 atomic%. A mask blank comprising a material having an atomic percent or less. The mask blank according to claim 6 , wherein the lower layer is made of tantalum and nitrogen. The mask blank according to claim 7 , wherein the lower layer is made of a material having a nitrogen content of less than 62 atomic%. The content of the upper layer of the oxygen mask blank according to any one of claims 6 to 8, characterized in that less than the oxygen content of the high oxide layer. The upper layer, the mask blank according to any one of claims 6 to 9 content of oxygen, comprising the 50 atomic% or more materials. The high oxidation layer, the mask blank according to any one of claims 6 to 10, wherein the thickness is 1.5nm or more 4nm or less. The mask blank according to any one of claims 6 to 11 , wherein the lower layer is made of a material that can be dry-etched to form a pattern using a chlorine-based gas that substantially does not contain oxygen. The mask blank according to any one of claims 6 to 12 , wherein the upper layer is made of a material that is difficult to dry-etch for forming a pattern using a chlorine-based gas that substantially does not contain oxygen. The light-shielding film, the mask blank according to any one of claims 1 to 13, wherein the film thickness is less than 60 nm. The etching mask film, the mask blank according to any one of claims 1 to 14, wherein the film thickness is 5nm or more 15nm or less. The phase shift mask, the mask blank according to any one of claims 1 to 15, characterized in that the following applies for the exposure light wavelength 200nm to pattern transfer. A method of manufacturing a substrate digging type phase shift mask using a mask blank,
The mask blank is
It is a structure in which a light shielding film and an etching mask film are sequentially laminated on a light transmitting substrate,
The light shielding film is formed in contact with the translucent substrate, and has a highly oxidized layer on a surface layer opposite to the translucent substrate side,
The highly oxidized layer is made of a material containing tantalum and having an oxygen content of 68 atomic% or more,
The light shielding film other than the high oxide layer is made of a material containing one or more elements selected from nitrogen, boron and carbon in tantalum,
The etching mask film is a material containing one or more elements selected from oxygen, nitrogen and carbon in chromium, having a chromium content of 45 atomic% or more and an oxygen content of more than 0 atomic%. Made of materials that are atomic percent or less,
Forming a resist film having a transfer pattern on the mask blank;
Using the resist film having the transfer pattern as a mask, forming a transfer pattern on the etching mask film by dry etching using a mixed gas of chlorine-based gas and oxygen gas; and
Using the etching mask film on which the transfer pattern is formed as a mask, forming a transfer pattern on the light shielding film by dry etching using a chlorine-based gas substantially not containing oxygen; and
Forming a resist film having a phase shift pattern on the mask blank on which the transfer pattern is formed;
Using the resist film having the phase shift pattern as a mask, forming a phase shift pattern by digging the translucent substrate to a predetermined depth by dry etching using a fluorine-based gas;
Removing the remaining etching mask film after forming the phase shift pattern on the translucent substrate;
A method of manufacturing a phase shift mask characterized by comprising: The method of manufacturing a phase shift mask according to claim 17 , wherein the high oxide layer has a thickness of 1.5 nm to 4 nm. A method of manufacturing a substrate digging type phase shift mask using a mask blank,
The mask blank is
A light-shielding film in which a lower layer and an upper layer are stacked, and an etching mask film are sequentially stacked on a translucent substrate,
The lower layer is formed in contact with the translucent substrate, and is made of a material containing one or more elements selected from nitrogen, boron, and carbon in tantalum,
The upper layer is mainly composed of tantalum and made of a material containing oxygen, and has a highly oxidized layer on the surface layer opposite to the lower layer,
The highly oxidized layer is made of a material containing tantalum and having an oxygen content of 68 atomic% or more,
The etching mask film is a material containing one or more elements selected from oxygen, nitrogen and carbon in chromium, having a chromium content of 45 atomic% or more and an oxygen content of more than 0 atomic%. Made of materials that are atomic percent or less,
Forming a resist film having a transfer pattern on the mask blank;
Using the resist film having the transfer pattern as a mask, forming a transfer pattern on the etching mask film by dry etching using a mixed gas of chlorine-based gas and oxygen gas; and
Using the etching mask film on which the transfer pattern is formed as a mask, a transfer pattern is formed on the upper layer by dry etching using a fluorine-based gas, and then by dry etching using a chlorine-based gas that does not substantially contain oxygen. Forming a transfer pattern in the lower layer;
Forming a resist film having a phase shift pattern on the mask blank on which the transfer pattern is formed;
Using the resist film having the phase shift pattern as a mask, forming a phase shift pattern by digging the translucent substrate to a predetermined depth by dry etching using a fluorine-based gas;
Removing the remaining etching mask film after forming the phase shift pattern on the translucent substrate;
A method of manufacturing a phase shift mask characterized by comprising: The method of manufacturing a phase shift mask according to claim 19 , wherein the high oxide layer has a thickness of 1.5 nm to 4 nm.

Images