JP6544964B2 - Mask blank, method of manufacturing phase shift mask, and method of manufacturing semiconductor device - Google Patents

Description

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

  As a mask blank for a phase shift mask, a mask blank having a light shielding film made of a chromium material on a light transmitting substrate has been known. The phase shift mask formed using such a mask blank is provided with a light shielding pattern formed by patterning a light shielding film by dry etching using a mixed gas of chlorine gas and oxygen gas.

  Generally, a thin film such as a light shielding film provided on a light transmitting substrate of a mask blank is often deposited by sputtering. Such thin films tend to have film stress. When a pattern is formed on a thin film by dry etching, the formed thin film pattern is released from the film stress of the thin film present around it, resulting in displacement of the thin film pattern. The displacement amount of the thin film pattern tends to increase as the film stress of the thin film increases.

  In order to suppress misalignment of the pattern of the light shielding film that occurs when manufacturing a transfer mask from such a mask blank, the light shielding film of the mask blank is formed of a chromium-based material with a small film stress, and the film stress of the light shielding film It has been considered to reduce the (see, for example, Patent Document 1 and Patent Document 2).

JP 2001-305713 A JP-A-8-286359

  In the case of a light shielding film of a chromium-based material, it is possible to reduce the film stress to some extent by adjusting the conditions at the time of sputtering film formation, but it is difficult to reduce it to near zero. In the case of a light shielding film of a silicon-based material, it is possible to reduce the film stress to near zero by performing a high temperature (for example, 300 ° C. or more) annealing process. However, in the case of a light shielding film of a chromium-based material, when such high temperature annealing is performed, the film quality of the light shielding film becomes extremely fragile, and it becomes impossible to form a pattern in the light shielding film.

  In recent years, with the phase shift mask, the miniaturization of patterns has progressed, and along with this, the range of misalignment of the transfer pattern permitted is smaller than in the past. In particular, in the case of a buried Levenson-type phase shift mask which is a phase shift mask of a type in which a light shielding film is left as a transfer pattern in a transfer pattern region irradiated with exposure light, the phase shift is significant. The required level of displacement of the pattern with respect to the light shielding film of the mask blank used when manufacturing the shift mask is severe.

  On the other hand, even in the case of a halftone phase shift mask which is a phase shift mask of a type in which a phase shift film is left as a transfer pattern in a transfer pattern region irradiated with exposure light, The required level of is severe. When a phase shift mask is manufactured from a mask blank, a transfer pattern is once formed on a light shielding film, and then a process of forming a transfer pattern on the phase shift film by patterning for masking the pattern of the light shielding film is performed. The conventional light-shielding film whose film stress is reduced to some extent has insufficient performance when applied to a mask blank for manufacturing any type of phase shift mask. However, as described above, there is a limit to reduce the film stress of the light shielding film of the chromium material at present. Therefore, it is required to suppress the influence of the film stress of the light shielding film of the mask blank on the positional deviation of the transfer pattern provided on the phase shift mask finally manufactured from the mask blank.

  In order to solve the problems described above, the present invention provides a mask blank for a phase shift mask capable of suppressing displacement of a transfer pattern of a phase shift mask caused by film stress of a light shielding film. The present invention also provides a method of manufacturing a phase shift mask capable of forming a transfer pattern with good accuracy by using this mask blank, and a method of manufacturing a semiconductor device.

  The present invention has the following configuration as means for solving the above-mentioned problems.

(Configuration 1)
A mask blank having a structure in which a light shielding film and a hard mask film are sequentially laminated on a translucent substrate,
The light shielding film has a single layer or a laminated structure of two or more layers,
The hard mask film is provided in contact with the surface of the light shielding film,
The layer constituting the light shielding film is formed of a material containing chromium and oxygen, and further containing at least one metal element selected from indium, tin and molybdenum,
The total content of chromium and the metal element in the layer constituting the light shielding film is 50 atomic% or more and 80 atomic% or less,
The hard mask film is formed of a material containing tantalum and oxygen,
The oxygen content of the said hard mask film | membrane is 50 atomic% or more, The mask blank characterized by the above-mentioned.

(Configuration 2)
The mask blank according to Configuration 1, wherein the chromium content in all the layers of the light shielding film is 40 atomic percent or more and 60 atomic percent or less.

(Configuration 3)
The mask blank according to Configuration 1 or 2, wherein the difference in chromium content between all the layers of the light shielding film is 20 atomic% or less.

(Configuration 4)
In any of the configurations 1 to 3, the ratio of the total content of the metal element to the total content of chromium and the metal element in all the layers of the light shielding film is 50% or less in any case. Mask blank.

(Configuration 5)
5. The mask blank according to any one of the configurations 1 to 4, wherein the light shielding film has an optical density of 2.8 or more with respect to ArF excimer laser light.

(Configuration 6)
5. The mask blank according to any one of the configurations 1 to 5, wherein the light shielding film has a thickness of 70 nm or less.

(Configuration 7)
4. The mask blank according to any one of the configurations 1 to 4, further comprising a phase shift film between the light transmitting substrate and the light shielding film.

(Configuration 8)
The mask blank according to Configuration 7, wherein an optical density to ArF excimer laser light in the laminated structure of the light shielding film and the phase shift film is 2.8 or more.

(Configuration 9)
7. The mask blank according to configuration 7 or 8, wherein the light shielding film has a thickness of 60 nm or less.

(Configuration 10)
A method of manufacturing a phase shift mask using the mask blank according to any one of configurations 1 to 6,
Forming a light shielding pattern on the hard mask film by dry etching using a fluorine-based gas using a resist film having a light shielding pattern formed on the hard mask film as a mask;
Forming a light shielding pattern on the light shielding film by dry etching using a mixed gas of a chlorine gas and an oxygen gas using the hard mask film on which the light shielding pattern is formed as a mask;
And forming a digging pattern in the light transmitting substrate by dry etching using a fluorine-based gas using a resist film having a digging pattern formed on the light shielding film as a mask. Method of manufacturing a phase shift mask.

(Configuration 11)
A method for producing a phase shift mask using the mask blank according to any one of constitutions 7 to 9, wherein
Forming a phase shift pattern on the hard mask film by dry etching using a fluorine-based gas using a resist film having a phase shift pattern formed on the hard mask film as a mask;
Forming a phase shift pattern on the light shielding film by dry etching using a mixed gas of chlorine gas and oxygen gas, using the hard mask film on which the phase shift pattern is formed as a mask;
Forming a phase shift pattern on the phase shift film by dry etching using a fluorine-based gas using the light shielding film on which the phase shift pattern is formed as a mask;
Forming a light shielding pattern on the light shielding film by dry etching using a mixed gas of a chlorine gas and an oxygen gas using a resist film having the light shielding pattern formed on the light shielding film as a mask. And a method of manufacturing a phase shift mask.

(Configuration 12)
According to a tenth aspect of the present invention, there is provided an exposure step of transferring a transfer pattern of the phase shift mask onto a semiconductor substrate by a lithography method using the phase shift mask manufactured by the method of manufacturing a phase shift mask according to the tenth or eleventh aspect. Semiconductor device manufacturing method.

  According to the present invention, it is possible to provide a mask blank for a phase shift mask capable of suppressing displacement of the transfer pattern of the phase shift mask caused by the film stress of the light shielding film. Further, according to the present invention, it is possible to provide a method of manufacturing a phase shift mask capable of forming a pattern with good accuracy by using this mask blank, and to provide a method of manufacturing a semiconductor device. Can.

It is a figure which shows schematic structure of a mask blank. It is a figure which shows schematic structure of a mask blank. It is a figure which shows schematic structure of a mask blank (phase shift film | membrane). It is a figure which shows schematic structure of a mask blank (phase shift film | membrane). It is a manufacturing-process figure of a phase shift mask (a digging Levenson type | mold). It is a manufacturing-process figure of a phase shift mask (a digging Levenson type | mold). It is a manufacturing-process figure of a phase shift mask (a digging Levenson type | mold). It is a manufacturing-process figure of a phase shift mask (a digging Levenson type | mold). It is a manufacturing-process figure of a phase shift mask (a digging Levenson type | mold). It is a manufacturing-process figure of a phase shift mask (a digging Levenson type | mold). It is a manufacturing-process figure of a phase shift mask (half tone type). It is a manufacturing-process figure of a phase shift mask (half tone type). It is a manufacturing-process figure of a phase shift mask (half tone type). It is a manufacturing-process figure of a phase shift mask (half tone type). It is a manufacturing-process figure of a phase shift mask (half tone type). It is a manufacturing-process figure of a phase shift mask (half tone type). It is a manufacturing-process figure of a phase shift mask (half tone type).

Hereinafter, each embodiment of the present invention will be described.
Generally, in thin films of chromium (Cr) -based materials, it is known that CrN films, which are high Cr materials, have relatively strong tensile stress. It is also known that CrOCN films and CrOC films which are low Cr materials have a tendency of compressive stress. For example, Patent Document 2 mentioned above describes that the film stress of the CrN film is adjusted depending on the film forming conditions. Specifically, it is described that the film stress of a CrN film is set as a tensile stress or a compressive stress by adjusting the nitrogen content of the CrN film at the time of film formation. And, the tendency of the N content and the film stress of the CrN film is described.

Moreover, it is described in JP 2010-237501 A that a thin film of SiON material or SiO ₂ material has a tendency of compressive stress, and JP 2009-230113 A is a TaO material. It is stated that thin films have a tendency to tensile stress.

On the other hand, in accordance with the demand for miniaturization of the pattern of the phase shift mask, it is required to enhance the etching anisotropy of the light shielding film. Then, as a method of enhancing the etching anisotropy of the light shielding film made of a Cr-based material, an oxygen-containing chlorine-based gas (for example, a mixture of Cl ₂ and O _{2) in} which the mixing ratio of chlorine-based gas is greatly enhanced Dry etching (high bias etching conditions) under conditions where a bias voltage much higher than before is applied using a gas (high bias etching conditions) has been studied. However, when the above conditions are applied, it becomes difficult to form a light shielding film with a resist pattern mask made of an organic material, which is used when producing a transfer mask from a conventional mask blank. There is.

  For this reason, a hard mask film made of an inorganic material is formed on the mask blank so that application of high bias etching conditions using an oxygen-containing chlorine gas is possible, and a transfer mask is formed using this hard mask film. The thing is being done. As the hard mask film of the inorganic material, it is important that the etching selectivity with the material constituting the light shielding film made of the Cr material is high.

When a thin film of SiON material or SiO ₂ material having the above-mentioned compressive stress is applied to a hard mask, high bias etching conditions using oxygen-containing chlorine gas are applied to pattern the light shielding film made of Cr material When manufacturing a transfer mask, the etching resistance of the hard mask film is not sufficiently obtained. In particular, the side etching of the pattern of the hard mask film becomes remarkable, and the mask pattern is shrunk due to the decrease of the peripheral edge of the mask pattern. Then, along with the reduction of the mask pattern, the pattern formed on the light shielding film is also reduced, which makes it difficult to improve the pattern accuracy, which is disadvantageous to the miniaturization of the pattern of the phase shift mask.

  Therefore, when applying a high bias etching condition using an oxygen-containing chlorine gas and patterning a light shielding film comprising a Cr material to produce a phase shift mask, a hard mask is produced from a material other than the SiO material. There is a need to. Therefore, attention was paid to etching selectivity with a Cr-based material, and using a TaO-based material as a hard mask film was examined. For example, in JP 2013-83933 A, as a mask blank for patterning a light shielding film by dry etching using a mixed gas of chlorine gas and oxygen, on a light shielding film in which a TaO material having a different composition is laminated on the upper layer. Further, a configuration having a hard mask film made of a Cr-based material such as CrN, CrON, CrCN, CrOCN, CrBN, CrOBN, or CrOCBN is described.

  In the process of manufacturing a transfer mask from a mask blank, a resist pattern is used as a mask, and a hard mask film of a Cr-based material is patterned by dry etching using an oxygen-containing chlorine gas. As a mask, the light shielding film including the upper layer of the TaO-based material is patterned by dry etching using an oxygen-free chlorine-based gas. However, the etching of the hard mask film is not performed under high bias etching conditions because a resist pattern of an organic material is used as a mask. In addition, since the dry etching with oxygen-free chlorine-based gas performed when patterning the light-shielding film is etching based on ions, sufficient etching anisotropy is obtained even under normal bias conditions. Be That is, this publication does not disclose the etching selectivity between the Cr-based material and the TaO-based material under high bias etching conditions using an oxygen-containing chlorine-based gas.

  Based on the above, as a result of further studies, we came to think of the configuration of a mask blank comprising a light shielding film made of a Cr-based material and a hard mask made of a TaO-based material. According to the mask blank of this configuration, the TaO-based mask can be used for patterning a light-shielding film made of a Cr-based material even when high bias etching conditions using an oxygen-containing chlorine-based gas are applied to enhance etching anisotropy. A hard mask film made of a material has sufficient etching resistance. Therefore, when a light shielding film made of a Cr-based material is patterned to form a transfer mask, side etching of the hard mask film pattern can be suppressed, and the mask pattern is reduced and the light shielding film is formed accordingly. It is possible to suppress the decline of the As a result, it is possible to enhance the pattern accuracy when producing the phase shift mask from the mask blank, and it becomes possible to miniaturize the pattern of the phase shift mask.

  As mentioned above, the thin film of the TaO-based material has a tendency of tensile stress. For this reason, it is not preferable to select a TaO-based material as the material for forming the hard mask film and to select a Cr-based material having a tensile stress as the material for forming the light shielding film. In this configuration, the direction of displacement of the hard mask pattern when the transfer pattern is formed on the hard mask film is the same as the direction of displacement of the light shielding pattern when the transfer pattern is formed on the light shielding film. For this reason, when the position of the light shielding pattern at the time of design is used as a reference, the amount of deviation of the position of the light shielding pattern actually formed on the light shielding film becomes very large.

  Therefore, it was considered to provide a light shielding film having a film stress (compressive stress) opposite to that of the hard mask film of a TaO-based material. That is, the direction of displacement of the hard mask pattern caused by the compressive stress of the light shielding film is made opposite to the direction of displacement of the hard mask pattern caused by the tensile stress of the hard mask film. As a result, the amount of positional deviation of the light shielding pattern actually formed on the light shielding film based on the position of the light shielding pattern at the time of design can be made smaller than in the case where the hard mask film is not stacked.

  It is desirable that the chromium-based material forming the light shielding film has a high etching rate to the oxygen-containing chlorine-based gas, while making it possible to fill the predetermined optical density with a film thickness as thin as possible. Cr contains oxygen (O) and at least one metal element (hereinafter referred to as metal element M such as indium) selected from indium (In), tin (Sn), and molybdenum (Mo) The Cr-based material (hereinafter, CrOM-based material) is suitable for the conditions as the material of the light shielding film described above. Also, it has been found that this CrOM-based material has compressive stress depending on its composition. Furthermore, it has been found that this CrOM-based material can adjust the magnitude of the compressive stress of the film by adjusting the content of Cr and the metal element M such as indium. It has not been disclosed that a thin film of such a CrOM-based material has compressive stress, and a method of adjusting the compressive stress of the CrOM-based material by the composition of a metal element M such as indium and the like and Cr.

  Therefore, the mask blank of the present invention is configured to include a light shielding film made of a CrOM based material having compressive stress and a hard mask film made of a TaO based material having tensile stress. By the mask blank of this configuration, it is possible to suppress positional deviation of the pattern formed on the light shielding film, which is caused by the film stress of the light shielding film and the hard mask film. Furthermore, even when the light shielding film is patterned by dry etching with high bias voltage using an oxygen-containing chlorine gas as the etching gas with the mask blank of this configuration, the optical characteristics of the light shielding film having a pattern formed thereon are obtained. It becomes possible to produce a phase shift mask with good pattern accuracy while maintaining it. As a mask blank that is preferably applied with a configuration provided with a light shielding film made of a CrOM-based material having this compressive stress and a hard mask film made of a TaO-based material having a tensile stress, it is suitable for trenched Levenson-type phase shift masks Mask blanks, and mask blanks for halftone phase shift masks.

  Hereinafter, the detailed configuration of the present invention described above will be described based on the drawings. The same components in the drawings will be described with the same reference numerals.

<Mask blank>
1 and 2 show a schematic configuration of an embodiment of a mask blank. The mask blank 10 shown in FIG. 1 has a configuration in which the light shielding film 12 and the hard mask film 13 are sequentially stacked on the one main surface 11S of the translucent substrate 11 from the main surface 11S side. 12 is composed of a single layer. The mask blank 10A shown in FIG. 2 has a configuration in which the light shielding film 12 and the hard mask film 13 are sequentially stacked from the main surface 11S side on one main surface 11S of the translucent substrate 11, and the light shielding film A plurality of layers 12 (two layers in this example) of the lower layer 12A and the upper layer 12B are formed from the main surface 11S side. In the following description, the lower layer 12A and the upper layer 12B are collectively referred to as a light shielding film 12. The mask blanks 10 and 10A shown in FIG. 1 and FIG. 2 may have a configuration in which a resist film 14 is provided on the hard mask film 13 as necessary. The details of the main components of the mask blank 10 and the mask blank 10A will be described below.

  In the following, the film stress of the thin film in the mask blank uses the PV value of the difference shape as its index. When the target thin film is provided in contact with the surface of the other thin film (the surface opposite to the substrate), the difference shape of the thin film means the surface shape of the target thin film (opposite to the substrate) The difference shape obtained by subtracting the surface shape of the other thin film (surface shape on the opposite side to the substrate side) from the surface shape on the side). When the target thin film is provided in contact with the surface of the substrate (the surface on which the target thin film is formed), the difference between the thin films means the surface shape of the target thin film (substrate The difference shape obtained by subtracting the surface shape of the substrate (the surface shape on the side where the target thin film is formed) from the surface shape on the opposite side to the side.

  This difference shape is a change distribution of the surface shape of the substrate or other thin film which is caused by forming a thin film having film stress. A thin film whose differential shape is a convex shape has compressive stress, and a thin film whose differential shape has a concave shape has tensile stress. The PV value of the differential shape of the thin film refers to the difference between the maximum height and the minimum height in the inner region of a square having a side of 142 mm on the basis of the center of the substrate related to the differential shape. When the difference shape is a convex shape, the PV value of the difference shape is a positive value, and when the difference shape is a concave shape, the PV value of the difference shape is a negative value. That is, when the differential shape PV is a positive value, the thin film has a compressive stress, and when the differential shape PV has a negative value, the thin film has a tensile stress.

  The surface shapes of the light transmitting substrate 11, the light shielding film 12, and the phase shift film 21 (see FIG. 3) described later are measured by a surface shape analyzer, for example, UltraFLAT 200M (manufactured by Corning Tropel). The area for measuring the surface shape is an area including a difference shape and an inner area of a quadrangle 142 mm on one side with respect to the center of the substrate which is an area for calculating the PV value. Specifically, for example, the area for measuring the surface shape is an area including a quadrangular inner area having a side of 148 mm on the basis of the center of the substrate.

[Transparent substrate]
The translucent substrate 11 is made of a material having good transparency to exposure light used in an exposure process in lithography. As such a material, synthetic quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ -TiO ₂ glass etc.), and various other glass substrates can be used. In particular, since the quartz substrate using synthetic quartz glass has high transparency to ArF excimer laser light (wavelength: 193 nm), it can be suitably used as the translucent substrate 11 of the mask blanks 10 and 10A.

  Incidentally, the exposure step in lithography referred to herein is an exposure step in lithography using a phase shift mask manufactured using this mask blank 10, 10A, and in the following, exposure light is used in this exposure step It is assumed that it is exposure light. As this exposure light, any of ArF excimer laser light (wavelength: 193 nm), KrF excimer laser light (wavelength: 248 nm) and i-line light (wavelength: 365 nm) can be applied. From the viewpoint of miniaturization, it is desirable to apply ArF excimer laser light to the exposure light. Therefore, in the following, an embodiment in which ArF excimer laser light is applied to exposure light will be described.

[Light shielding film]
The light shielding film 12 applied to the mask blanks 10 and 10A may be formed as a single layer as shown in FIG. 1, and even if it is divided into a plurality of layers as shown in FIG. Good. The mask blank 10A shown in FIG. 2 shows a configuration in which the lower layer 12A and the upper layer 12B are formed from the main surface 11S side as an example in which the light shielding film 12 is divided into a plurality of layers.

  The light shielding film 12 is a film constituting a light shielding pattern formed on the mask blanks 10 and 10A, and is a film having a light shielding property to exposure light used in an exposure process in lithography. In the case of the mask blank of the configuration of FIG. 1 in which the phase shift film 21 is not interposed between the light transmitting substrate 11 and the light shielding film 12 described later, the light shielding film 12 has an optical density (OD Is preferably 2.8 or more, and more preferably 3.0 or more. In addition, in the exposure process in lithography, the surface reflectance of the exposure light on both main surfaces is suppressed to a low level in order to prevent the problem of the exposure transfer due to the reflection of the exposure light. In particular, the reflectance of the surface side (the surface farthest from the light transmitting substrate 11) on the light shielding film 12 to which the reflected light of the exposure light from the reduction optical system of the exposure apparatus is applied is, for example, 40% or less (preferably, 30% or less) is desired. This is to suppress stray light generated by multiple reflection between the surface of the light shielding film 12 and the lens of the reduction optical system.

  On the other hand, the reflectance of the back surface side (surface on the side of the translucent substrate 11) in the light shielding film 12 to which exposure light from the projection optical system of the exposure apparatus is applied is, for example, less than 50% (preferably 40% or less) Is desired. This is to suppress stray light generated by multiple reflection between the interface between the light transmitting substrate 11 and the back surface of the light shielding film 12 and the main surface of the light transmitting substrate 11 on the projection optical system side.

  The light shielding film 12 is configured to have a film thickness that is at least the minimum degree that satisfies the required light shielding property. The thickness of the light shielding film 12 is preferably 30 nm or more, more preferably 35 nm or more, and particularly preferably 40 nm or more. The thickness of the light shielding film 12 is preferably 70 nm or less, more preferably 65 nm or less, and particularly preferably 60 nm or less.

  When the light shielding film 12 is formed of a plurality of layers, the light shielding property required of the whole of the plurality of light shielding films 12 may be satisfied. Therefore, when the light shielding film 12 is formed of a plurality of layers, the total film thickness of the plurality of layers is preferably 30 nm or more, more preferably 35 nm or more, and particularly preferably 40 nm or more. . The total film thickness of the light shielding film 12 is preferably 70 nm or less, more preferably 65 nm or less, and particularly preferably 60 nm or less.

  Furthermore, when the light shielding film 12 is formed of a plurality of layers, the thickness of each layer is not particularly limited as long as the total thickness satisfies the above, but for example, the thickness of each layer is 35 nm or less Is preferably 30 nm or less, more preferably 25 nm or less. The thickness of each layer is preferably 10 nm or more, more preferably 15 nm or more, and more preferably 20 nm or more.

  As the light shielding film 12, it is necessary to apply a material having sufficient etching selectivity to an etching gas (fluorine-based gas) used when forming a recess pattern in the light transmitting substrate 11.

  Moreover, the light shielding film 12 is comprised from the chromium (Cr) type | system | group material of the composition which has a compressive stress. When the light shielding film 12 is formed of a plurality of layers, all layers constituting the light shielding film 12 are formed of a chromium (Cr) -based material having a composition having a compressive stress.

  As a Cr-based material having compressive stress, at least one or more metal elements selected from Cr, oxygen (O), indium (In), tin (Sn), and molybdenum (Mo) (a metal element M such as indium) ) Is made of a material whose main component is Here, having the metal element M such as chromium, oxygen and indium as the main component means that the total content of the metal element M such as chromium, oxygen and indium in the light shielding film 12 is 95 atomic% or more. In addition, preferably, the total content of the metal elements M such as chromium, oxygen and indium is 98% or more. Furthermore, except for the inevitable impurities described later, it is preferable that all of the metal elements M such as chromium, oxygen and indium are contained. Hereinafter, a material containing a metal element M such as chromium, oxygen and indium as a main component is described as CrOM. In addition, the light shielding film 12 mainly composed of CrOM may be referred to as a CrOM film.

  In the light shielding film 12 containing CrOM as a main component, the light shielding film 12 having compressive stress is configured by setting the total content of Cr and a metal element M such as indium to 50 atomic% or more and 80 atomic% or less. Can. At this time, the remainder is preferably oxygen. Furthermore, when the total content of Cr and metal element M such as indium is 50 atomic% or more, sufficient light shielding property can be secured. Further, if the total content of Cr and metal element M such as indium is 80 atomic% or less, the etching rate for dry etching of the oxygen-containing chlorine-based gas can be sufficiently secured.

  Moreover, in the light shielding film 12, it is preferable that Cr content is 40 atomic% or more and 60 atomic% or less. When the content of Cr is 40 atomic% or more, sufficient light shielding property can be secured. In addition, if the Cr content is 60 atomic% or less, the etching rate for dry etching of the oxygen-containing chlorine-based gas can be sufficiently secured.

  Furthermore, in the light shielding film 12, the ratio of the content of the metal element M such as indium to the total content of Cr and the metal element M such as indium is preferably 50% or less. This is because the metal element M such as indium has lower resistance to chemical solution cleaning and warm water cleaning than Cr.

  When the light shielding film 12 is formed of a plurality of layers, the difference in the Cr content of each layer is preferably 20 atomic% or less. By setting the difference in the Cr content to 20 atomic% or less, it is possible to suppress the difference in the etching rate for the dry etching of the oxygen-containing chlorine-based gas in each layer. Therefore, when the light shielding film 12 is patterned to produce a transfer mask, the difference in the side etching amount of the light shielding film 12 can be reduced, and the shape stability of the pattern side wall can be secured. It is possible to suppress the decrease in the accuracy of the pattern shape.

  In addition, in the case where the light shielding film 12 is formed of a plurality of layers, a layer formed on the light transmitting substrate 11 side is formed on the above (the opposite side to the light transmitting substrate 11). It is preferable that the total content of Cr and a metal element M such as indium be larger than that. The total content of Cr and a metal element M such as indium in the layer formed closest to the light transmitting substrate 11 is preferably 50 atomic% or more and 80 atomic% or less. And it is preferable that content of the sum total of Cr and metal elements, such as indium, of the layer formed in the opposite side to the translucent board | substrate 11 is 50 atomic% or more and 70 atomic% or less.

  For example, in the light shielding film 12 shown in FIG. 2, the total content of Cr and metal element M such as indium in the lower layer 12A provided on the translucent substrate 11 side may be 50 atomic% or more and 80 atomic% or less preferable. The total content of Cr in the upper layer 12B provided on the lower layer 12A and the metal element M such as indium is preferably 50 atomic% to 70 atomic%. Furthermore, the total content of Cr in the lower layer 12A and the metal element M such as indium is preferably larger than the total content of Cr and the metal element M such as indium in the upper layer 12B.

  The light shielding film 12 may contain nitrogen (N), carbon (C), boron (B), hydrogen (H) and the like in addition to the metal element M such as chromium, oxygen and indium. In addition, in the light shielding film 12, when forming the CrOM film, an element such as argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), etc. is mixed during film formation. It is hard to avoid. An element in which such contamination can not be avoided is called an unavoidable impurity. In the light shielding film 12, as long as the composition of the CrOM film satisfies the above range and the composition has a compressive stress, other elements or unavoidable impurities other than the metal element M such as chromium, oxygen and indium may be mixed.

  The CrOM film is a substrate by reactive sputtering using a mixed target of chromium and a metal element M such as indium or by reactive sputtering (co-sputtering) using a chromium target and a target of a metal element M such as indium. It can form by forming into a film one by one from the side. As a sputtering method, a direct current (DC) power source may be used, a radio frequency (RF) power source may be used, a magnetron sputtering method, or a conventional method may be used. DC sputtering is preferable in that the mechanism is simple. In addition, it is preferable to use a magnetron because the film forming speed is increased and the productivity is improved. Note that the film formation apparatus may be in-line type or single-wafer type. The target mentioned above may contain nitrogen, boron and carbon in addition to the above-mentioned constituent elements.

When a CrOM film is formed, as a sputtering gas, a gas containing oxygen (CO ₂ , NO ₂ , NO, O ₂ , O _3, etc.) and a rare gas (Ar, Ne, Kr, Xe, He, Ne, etc.) Etc.) can be used. Further, as the sputtering gas, a gas (CH ₄ , C ₂ H ₄ , C ₂ H ₆ or the like) which does not contain nitrogen gas or oxygen and contains carbon may be further mixed with the above mixed gas. In particular, it is safe to use a mixed gas of CO ₂ and a rare gas as the sputtering gas, and since the CO ₂ gas is less reactive than oxygen etc., the gas can uniformly flow around a wide range in the chamber, It is preferable from the viewpoint that the film quality of the CrOM film to be formed becomes uniform. The introduction method may be separately introduced into the chamber, or several gases may be introduced collectively or all gases may be introduced in a mixed manner.

  The light shielding film 12 preferably contains substantially no silicon (Si). It is preferable that content of Si in the light shielding film 12 is 1 atomic% or less, and it is preferable that it is below a detection limit value. Therefore, as a target used for forming the CrOM film, it is preferable not to use chromium containing silicon and other materials containing silicon.

[Hard mask film]
The hard mask film 13 is provided in contact with the surface of the light shielding film 12. The hard mask film 13 is a film formed of a material having etching resistance to an etching gas used when etching the light shielding film 12. It is sufficient for the hard mask film 13 to have a film thickness sufficient to function as an etching mask until dry etching for forming a pattern on the light shielding film 12 is completed, and basically the optical characteristics Not subject to Therefore, the thickness of the hard mask film 13 can be made much thinner than the thickness of the light shielding film 12.

  The thickness of the hard mask film 13 is required to be 20 nm or less, preferably 15 nm or less, and more preferably 10 nm or less. If the thickness of the hard mask film 13 is too thick, the thickness of a resist film to be a mask is required in dry etching for forming a light shielding pattern on the hard mask film 13. The thickness of the hard mask film 13 is required to be 3 nm or more, preferably 5 nm or more. If the thickness of the hard mask film 13 is too thin, the pattern of the hard mask film 13 disappears before the dry etching for forming the light shielding pattern on the light shielding film 12 is finished, depending on the conditions of high bias etching with oxygen containing chlorine gas Because there is a risk of

  Then, in dry etching with a fluorine-based gas to form a pattern on the hard mask film 13, the resist film 14 of an organic material used as an etching mask functions as an etching mask until dry etching of the hard mask film 13 is completed. It is sufficient if the thickness of the membrane is sufficient. Therefore, the thickness of the resist film 14 can be made much thinner by providing the hard mask film 13 than the conventional configuration in which the hard mask film 13 is not provided.

  The hard mask film 13 is made of a TaO-based material having a tensile stress. In order to form the hard mask film 13 from a TaO-based material having a tensile stress, a material containing tantalum (Ta) and oxygen (O) and having an O content of 50 atomic% or more is used as the TaO-based material . Hereinafter, a material containing tantalum (Ta) and oxygen (O) will be described as TaO.

In addition, the TaO film constituting the hard mask film 13 has a content of O of 50 atomic% or more, so that high bias etching conditions using an oxygen-containing chlorine-based gas applied to the patterning of the light shielding film 12 are also performed. , High etching resistance.
The hard mask film 13 needs to have sufficiently high etching resistance under high bias etching conditions using a mixed gas of a chlorine-based gas and an oxygen gas, which is performed when the light shielding film 12 is etched. If the etching resistance is not sufficient, the edge portion of the pattern of the hard mask film 13 is etched and the mask pattern is reduced, so that the accuracy of the light shielding pattern is deteriorated. The material containing Ta can sufficiently enhance the resistance to dry etching by a mixed gas of a chlorine-based gas and an oxygen gas by setting the oxygen content in the material to at least 50 atomic% (atomic%) or more. .

It is desirable that the TaO film constituting the hard mask film 13 be microcrystalline, preferably amorphous. If the crystal structure in the hard mask film 13 is microcrystalline or amorphous, it is difficult to be a single structure, and a plurality of crystal structures are easily mixed. Therefore, TaO in the hard mask film 13 tends to be in a state (mixed crystal state) in which TaO bond, Ta ₂ O ₃ bond, TaO ₂ bond, and Ta ₂ O ₅ bond are mixed. The resistance of the TaO in the hard mask film 13 to the dry etching by the mixed gas of the chlorine gas and the oxygen gas tends to improve as the existence ratio of the Ta ₂ O ₅ bond increases. Further, TaO in the hard mask film 13 tends to increase the characteristics to inhibit hydrogen penetration, the chemical resistance, the hot water resistance and the ArF light resistance as the proportion of the Ta ₂ O ₅ bond increases.

When the oxygen content of the TaO film constituting the hard mask film 13 is 50 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 bonding. The most unstable bond TaO bond is considered to be much smaller than that in the case where the oxygen content in the layer is less than 50 atomic%. If the content of oxygen in the layer is 66.7 atomic% or more, the TaO film constituting the hard mask film 13 is considered to have a high tendency for the bonding state of tantalum and oxygen to be dominated by the TaO ₂ bond. It is considered that the number of unstable labile TaO bonds and the subsequent unstable labile Ta ₂ O ₃ bonds are both very small.

In addition, when the oxygen content of the TaO film constituting the hard mask film 13 is 67 atomic% or more, it is considered that the ratio of the bonding state of Ta ₂ O ₅ instead of the TaO ₂ bond becomes high. With such an oxygen content, the bonding state of Ta ₂ O ₃ and TaO ₂ becomes rare, and the bonding state of TaO can not exist. When the oxygen content of the TaO film constituting the hard mask film 13 is 71.4 atomic%, it is considered that the film is formed substantially only in the bonding state of Ta ₂ O ₅ .

If the oxygen content of the TaO film constituting the hard mask film 13 is 50 atomic% or more, not only the most stable bonded state Ta ₂ O ₅ but also the bonded states of Ta ₂ O ₃ and TaO ₂ are included. Will be On the other hand, in the TaO film constituting the hard mask film 13, the lower limit value of the oxygen content at which the amount of the most unstable bond TaO bond is small to such an extent that dry etching resistance is not affected is at least 50 atomic%. It is considered to be.

The Ta ₂ O ₅ bond is a bonded state having very high stability, and high bias etching conditions using a mixed gas of chlorine gas and oxygen gas by increasing the abundance ratio of the Ta ₂ O ₅ bond The resistance to dry etching is greatly enhanced. In addition, properties for preventing hydrogen penetration, resistance to chemicals such as chemicals, resistance to hot water and other mask cleaning, and ArF light resistance are also greatly enhanced. In particular, the TaO film constituting the hard mask film 13 is most preferably formed only in the bonded state of Ta ₂ O ₅ . The TaO film constituting the hard mask film 13 is preferably in a range that does not affect the effects of nitrogen and other elements, and is preferably not substantially contained.

Further, the TaO film constituting the hard mask film 13 is a chlorine material by making the narrow spectrum of Ta 4 f when it is subjected to X-ray electron spectroscopic analysis (XPS analysis) into a material having the maximum peak at a binding energy larger than 23 eV. The resistance to dry etching under high bias etching conditions using a mixed gas of a system gas and an oxygen gas can be greatly enhanced. Materials having high binding energy tend to improve resistance to dry etching by a mixed gas of chlorine gas and oxygen gas. In addition, properties to inhibit hydrogen penetration, chemical resistance, hot water resistance, and ArF light resistance also tend to be high. The bonding state having the highest binding energy in the tantalum compound is a Ta ₂ O ₅ bond.

That is, the resistance of the TaO film constituting the hard mask film 13 to dry etching under high bias etching conditions using a mixed gas of a chlorine gas and an oxygen gas improves as the abundance ratio of the Ta ₂ O ₅ bond is higher. . Furthermore, by controlling the oxygen content of the TaO film constituting the hard mask film 13, it is possible to urge the abundance ratio of the Ta ₂ O ₅ bond to be high. However, in order to form a TaO film having a high proportion of Ta ₂ O ₅ bonds with certainty, X-ray electron spectroscopic analysis is performed on the actually formed TaO film to observe the narrow spectrum of Ta 4 f. It is better to control. For example, a plurality of conditions are set for the film forming conditions of the sputtering film forming apparatus and the processing conditions of the surface treatment for forming the TaO film, and a mask blank on which a TaO film is formed as the hard mask film 13 under each condition Manufacture. Then, X-ray electron spectroscopy analysis is performed on the hard mask film 13 of each mask blank, the narrow spectrum of Ta 4 f is observed, and conditions for forming a TaO film having high binding energy are selected. A mask blank comprising a TaO film formed under the selected conditions is manufactured. In the mask blank manufactured in this manner, the proportion of Ta ₂ O ₅ bonds in the hard mask film 13 formed on the surface layer of the light shielding film is surely increased.

As described above, it is preferable that the TaO film constituting the hard mask film 13 has a maximum peak at a binding energy larger than 23 eV when the narrow spectrum of Ta 4 f when X-ray electron spectroscopic analysis is performed. This is because a material containing tantalum having a binding energy of 23 eV or less is unlikely to have a Ta ₂ O ₅ bond. Furthermore, the TaO film constituting the hard mask film 13 preferably has a binding energy of 24 eV or more, more preferably 25 eV or more, and more preferably 25.4 eV in the narrow spectrum of Ta 4 f when X-ray electron spectroscopic analysis is performed. It is especially preferable that it is more than. When the binding energy of the TaO film constituting the hard mask film 13 is 25 eV or more, the bonding state of tantalum and oxygen in the TaO film is mainly Ta ₂ O ₅ bonding, and a mixed gas of chlorine gas and oxygen gas The resistance to dry etching under high bias etching conditions using the

[Resist film]
The mask blanks 10 and 10A are preferably in contact with the surface of the hard mask film 13 so that a resist film 14 of an organic material is formed to a thickness of 100 nm or less. In the case of a fine pattern corresponding to the DRAM hp 32 nm generation, a light shielding pattern to be formed in the light shielding film 12 may be provided with a sub-resolution assist feature (SRAF) having a line width of 40 nm. However, even in this case, the film thickness of the resist film 14 can be suppressed by providing the hard mask film 13 as described above, whereby the cross-sectional aspect ratio of the resist pattern formed of the resist film 14 is 1: 2 It can be as low as .5. Therefore, collapse and detachment of the resist pattern can be suppressed at the time of development and rinse of the resist film 14. The resist film 14 more preferably has a thickness of 80 nm or less. The resist film 14 is preferably a resist for electron beam lithography exposure, and more preferably the resist is a chemically amplified resist.

[Mask blank manufacturing procedure]
The mask blanks 10 and 10A of the above configuration are manufactured in the following procedure. First, the translucent substrate 11 is prepared. In this light-transmissive substrate 11, the end face and the main surface 11S are polished to a predetermined surface roughness (for example, the root-mean-square roughness Rq is 0.2 nm or less in the inner region of one side of 1 μm), and then Predetermined cleaning and drying were performed.

  Next, a CrOM film is formed as the light shielding film 12 on the light transmitting substrate 11 by sputtering. When the light shielding film 12 is formed of a plurality of layers, the film formation is performed a plurality of times so that the composition of the CrOM film is different. Then, a TaO film is formed as the hard mask film 13 on the light shielding film 12 by sputtering. In the film formation of each layer by the sputtering method, a sputtering target and a sputtering gas containing materials constituting each layer at a predetermined composition ratio are used, and further, a mixed gas of the above-mentioned rare gas and reactive gas is used as needed. The film formation used as sputtering gas is performed.

  Thereafter, when the mask blanks 10 and 10A have the resist film 14, the surface of the hard mask film 13 is subjected to the HMDS process. Then, a resist film 14 is formed on the surface of the hard mask film 13 subjected to the HMDS treatment by a coating method such as a spin coating method to complete the mask blanks 10 and 10A.

<Mask blank (phase shift film)>
The configuration of the mask blank made of the light transmitting substrate, the light shielding film, and the hard mask film described above is also applicable to a mask blank including a phase shift film. FIG. 3 and FIG. 4 show a schematic configuration of a mask blank provided with a phase shift film together with a light shielding film and a hard mask film.

  In the mask blank 20 shown in FIG. 3, the phase shift film 21, the light shielding film 12, and the hard mask film 13 are formed on the main surface 11 S on one side of the light transmitting substrate 11 sequentially from the light transmitting substrate 11 side. It is a laminated structure. Further, in the mask blank 20A shown in FIG. 4, the phase shift film 21, the light shielding film 12, and the hard mask film 13 are sequentially stacked on the main surface 11S of one side of the translucent substrate 11 from the main surface 11S side. The light shielding film 12 is composed of a plurality of layers (two layers in this example) of the lower layer 12A and the upper layer 12B from the main surface 11S side. In the following description, the lower layer 12A and the upper layer 12B are collectively referred to as a light shielding film 12. Further, the mask blanks 20 and 20A shown in FIG. 3 and FIG. 4 may be configured to have a resist film 14 on the hard mask film 13 as necessary. The details of the main components of the mask blank 20 and the mask blank 20A will be described below.

  In the mask blanks 20 and 20A shown in FIGS. 3 and 4, the light transmitting substrate 11, the light shielding film 12, the lower layer 12A, the upper layer 12B, the hard mask film 13 and the resist film 14 are the same as those described above. The configuration is the same as that described in the embodiment. Therefore, in the following, in the main configuration of the mask blanks 20 and 20A, only the configuration related to the phase shift film 21 will be described.

[Phase shift film]
The phase shift film 21 is formed between the light transmitting substrate 11 and the light shielding film 12. The phase shift film 21 has a predetermined transmittance to the exposure light used in the exposure and transfer process, and the exposure light transmitted through the phase shift film is transmitted through the atmosphere by the same distance as the thickness of the phase shift film. It has an optical characteristic that the exposure light has a predetermined phase difference.

  Here, such phase shift film 21 is formed of a material containing silicon (Si). The phase shift film 21 is preferably formed of a material containing nitrogen (N) in addition to silicon. Such a phase shift film 21 can be patterned by dry etching using a fluorine-based gas, and a material having sufficient etching selectivity to the CrOM film constituting the light shielding film 12 described above is used.

The phase shift film 21 may further contain one or more elements selected from a metalloid element, a nonmetal element, and a metal element, as long as patterning is possible by dry etching using a fluorine-based gas.
Among these, the metalloid element may be any metalloid element in addition to silicon. The nonmetallic element may be any nonmetallic element in addition to nitrogen, and for example, it contains one or more elements selected from oxygen (O), carbon (C), fluorine (F) and hydrogen (H) Preferred. The metal elements are molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), niobium (Nb), vanadium (V), cobalt (Co), chromium Examples include (Cr), nickel (Ni), ruthenium (Ru), tin (Sn), boron (B) and germanium (Ge).

  Such phase shift film 21 is made of, for example, MoSiN, and has a predetermined phase difference (for example, 150 [deg] to 180 [deg]) and a predetermined transmittance (for example, for example) with respect to exposure light (for example, ArF excimer laser light). The refractive index n, extinction coefficient k and film thickness of the phase shift film 21 are selected so as to satisfy 1% to 30%), and the composition of the film material and the refractive index n and extinction coefficient k The film forming conditions of the film are adjusted.

  In the case of the light shielding film 12 of the mask blank 20, it is not necessary to satisfy the lower limit of the optical density (OD) with respect to the above-mentioned ArF excimer laser light with only the light shielding film 12. The lower limit value (2.8, more preferably 3.0) of the optical density to the above ArF excimer laser light may be satisfied by the laminated structure of the phase shift film 21 and the light shielding film 12. Further, the film thickness of the light shielding film 12 in this case is preferably 25 nm or more, and more preferably 30 nm or more. The film thickness of the light shielding film 12 is preferably 60 nm or less, and more preferably 55 nm or less.

[Mask blank manufacturing procedure]
The mask blanks 20 and 20A configured as described above are manufactured in the following procedure. First, the translucent substrate 11 is prepared. In the light-transmissive substrate 11, the end face and the main surface 11S are polished to a predetermined surface roughness, and then predetermined cleaning processing and drying processing are performed.
Next, the phase shift film 21 is formed on the light transmitting substrate 11 by sputtering. After the phase shift film 21 is formed, annealing is performed at a predetermined heating temperature as post-processing.
Next, a CrOM film is formed as the light shielding film 12 on the phase shift film 21 by sputtering. When the light shielding film 12 is formed of a plurality of layers, the film formation is performed a plurality of times so that the composition of the CrOM film is different. Then, a TaO film is formed as the hard mask film 13 on the light shielding film 12 by sputtering. In the film formation of each layer by sputtering, a sputtering target and a sputtering gas containing materials constituting each layer at a predetermined composition ratio are used, and further, if necessary, a mixed gas of the above-mentioned rare gas and reactive gas is used. The film formation used as sputtering gas is performed.

  Thereafter, when the mask blanks 20 and 20A have the resist film 14, the surface of the hard mask film 13 is subjected to the HMDS process. Then, a resist film 14 is formed on the surface of the hard mask film 13 subjected to the HMDS treatment by a coating method such as a spin coating method to complete the mask blanks 20 and 20A.

<Method of manufacturing phase shift mask (drilled Levenson type)>
Next, the manufacturing method of the phase shift mask using the above-mentioned mask blank is demonstrated. In the following method of manufacturing a phase shift mask, a method of manufacturing a recessed Levenson-type phase shift mask using a mask blank having a configuration shown in FIG. 1 will be described as an example. Even when the light shielding film as shown in FIG. 2 is formed of a plurality of layers, a Levenson-type phase shift mask can be manufactured by the same method.

  First, as shown in FIG. 5, a light shielding pattern to be formed on the light shielding film 12 is exposed and drawn on the resist film (first resist film) 14 of the mask blank. At this time, a central portion of the light transmitting substrate 11 is made a phase shift pattern (transfer pattern) forming area 11A, and a light shielding pattern to be a phase shift pattern is exposed and drawn here. Further, in the outer peripheral area 11B of the phase shift pattern formation area 11A, for example, a light shielding pattern to be an alignment pattern is exposed and drawn. Thereafter, predetermined processing such as PEB processing, development processing, post-baking processing and the like is performed on the resist film 14 to form a light shielding pattern and an alignment pattern on the resist film 14.

  In addition, in the phase shift mask of the digging Levenson type described here, the phase shift pattern is composed of a light shielding pattern and a digging pattern. Further, in many cases, an electron beam is used for exposure drawing of the resist film 14.

  Next, as shown in FIG. 6, the hard mask film 13 made of TaO is dry etched using a fluorine-based gas using the resist film 14 on which the light shielding pattern and the alignment pattern are formed as a mask. Form a light shielding pattern and an alignment pattern. Thereafter, the resist film 14 is removed. Alternatively, the light shielding film 12 may be dry etched while the resist film 14 remains without being removed. Also in this case, the resist film 14 disappears during dry etching of the light shielding film 12.

  Next, as shown in FIG. 7, using the hard mask film 13 made of TaO on which a light shielding pattern and an alignment pattern are formed as a mask, light shielding using a mixed gas of chlorine gas and oxygen gas (oxygen containing chlorine gas) Dry etching of the film 12 is performed, and the light shielding film 12 made of CrOM is patterned. At this time, dry etching using an oxygen-containing chlorine-based gas uses an etching gas having a higher mixing ratio of chlorine-based gas than in the past. The mixing ratio of the mixed gas of chlorine-based gas and oxygen gas in dry etching of the light shielding film 12 is preferably a chlorine-based gas: oxygen gas = 10: 1 or more at a gas flow rate ratio in the etching apparatus, 15 The ratio is more preferably 1 or more, and more preferably 20 or more. By using an etching gas with a high mixing ratio of chlorine-based gas, the anisotropy of dry etching can be enhanced. In the dry etching of the light shielding film 12, the mixing ratio of the mixed gas of chlorine gas and oxygen gas is chlorine gas: oxygen gas = 40 or less: 1 in the gas flow ratio in the etching chamber. preferable.

  Even when the light shielding film 12 is composed of a plurality of layers of CrOM materials having different compositions, etching can be performed at once by the above method. For example, as in the mask blank 10A shown in FIG. 2 described above, even when the light shielding film 12 is composed of the lower layer 12A and the upper layer 12B, patterning may be performed simultaneously by one dry etching if it is made of a CrOM-based material. it can.

Further, in the dry etching of the oxygen-containing chlorine-based gas with respect to the light shielding film 12, the bias voltage applied from the back surface side of the light transmitting substrate 11 is also made higher than in the prior art. Although the effect of increasing the bias voltage is different depending on the etching apparatus, for example, the bias voltage is preferably 15 W or more, more preferably 20 W or more, and 30 W or more. And more preferred. By increasing the bias voltage, the anisotropy of dry etching of the oxygen-containing chlorine-based gas can be increased.
The light shielding pattern formed of the light shielding film 12 is formed by the above method. The light shielding pattern has a light shielding pattern in the phase shift pattern formation region 11A and a hole-shaped alignment pattern 15 in the outer peripheral region 11B.

Next, as shown in FIG. 8, a resist film (second resist film) 16 having a recessed pattern is formed on the hard mask film 13 on which the light shielding pattern is formed.
At this time, first, a resist film 16 is formed on the translucent substrate 11 by spin coating. Next, after exposure drawing is performed on the applied resist film 16, predetermined processing such as development processing is performed. As a result, a digging pattern in which the translucent substrate 11 is exposed is formed in the resist film 16 of the phase shift pattern formation region 11A. Here, a recess pattern is formed in the resist film 16 with an opening width with a margin for misalignment in lithography, and the recess pattern opening formed in the resist film 16 completely exposes the opening of the light shielding pattern. So as to form a digging pattern.

  The resist film 16 formed on the hard mask film 13 at the end of the dry etching of the light-transmissive substrate 11 using a fluorine-based gas in the subsequent step of forming a recess pattern in the light-transmissive substrate 11 is It disappears with the hard mask film 13. However, the resist film 16 filled in between the light shielding patterns may remain to such an extent that at least the main surface 11S of the translucent substrate 11 is not exposed even at the end of the dry etching in the process of forming the recess pattern. Preferred (see FIG. 9). For this reason, it is preferable to form the resist film 16 with such a thickness that the main surface 11S of the translucent substrate 11 is not exposed after dry etching in the step of forming a recess pattern.

  Next, as shown in FIG. 9, dry etching of the light transmitting substrate 11 is performed using a fluorine-based gas, using the resist film 16 having a recessed pattern and the light shielding film 12 on which a light shielding pattern is formed as a mask. Thereby, in the phase shift pattern formation region 11A of the translucent substrate 11, a digging pattern is formed on the main surface 11S. This digging pattern is formed to a depth such that the phase is shifted by a half cycle (180 degrees) with respect to the exposure light used in the lithography exposure step using the phase shift mask obtained here. For example, if ArF excimer laser light is applied to the exposure light, the digging pattern is formed to a depth of about 173 nm.

  In addition, during the dry etching of the light-transmissive substrate 11 with the fluorine-based gas, the resist film 16 is reduced, and the resist film 16 on the hard mask film 13 is completely lost. Furthermore, the hard mask film 13 also disappears by dry etching with a fluorine-based gas. As a result, the phase shift pattern 17 is formed in the phase shift pattern formation region 11A, which is composed of the light shielding pattern and the digging pattern formed on the light transmitting substrate 11. Thereafter, the remaining resist film 16 is removed.

  By the above steps, a phase shift mask 30 as shown in FIG. 10 is obtained. In the phase shift mask 30 manufactured by the above steps, a digging pattern is formed on one main surface 11S side of the light transmitting substrate 11, and a light shielding pattern is formed on the main surface 11S of the light transmitting substrate 11. The light shielding film 12 thus formed is laminated. The digging pattern is formed on the main surface 11S of the translucent substrate 11 in a state of being continuous with the opening bottom of the light shielding pattern in the phase shift pattern forming region 11A of the translucent substrate 11. In the phase shift pattern formation area 11A, the phase shift pattern 17 composed of the digging pattern and the light shielding pattern is disposed. Further, in the outer peripheral region 11B, a hole-shaped alignment pattern 15 penetrating the light shielding film 12 is provided.

In the above steps, the chlorine-based gas used in dry etching is not particularly limited as long as it contains Cl. For example, Cl ₂ , SiCl ₂ , CHCl ₃ , CH ₂ Cl ₂ , CCl ₄ , BCl _{3 and the} like can be mentioned as a chlorine-based gas. Further, in the above steps, the fluorine-based gas used in dry etching is not particularly limited as long as it contains F. For example, as the fluorine-based gas, CHF ₃ , CF ₄ , C ₂ F ₆ , C ₄ F ₈ , SF _{6 and the} like can be mentioned.

  In the phase shift mask manufacturing method described above, the phase shift mask is manufactured using the mask blank 10 described with reference to FIG. In the manufacture of such a phase shift mask, dry etching with an oxygen-containing chlorine-based gas having a tendency of isotropic etching is applied in the dry etching step of the light shielding film 12 made of CrOM described with reference to FIG. There is. Furthermore, the dry etching with the oxygen-containing chlorine gas in the step of FIG. 7 is performed under etching conditions under which the ratio of the chlorine gas of the oxygen-containing chlorine gas is high and a high bias is applied. Thereby, in the dry etching process of the light shielding film 12 made of CrOM, it is possible to increase the tendency of the etching anisotropy while suppressing the decrease in the etching rate. Thereby, side etching when forming a pattern in the light shielding film 12 is reduced.

In the dry etching process of the light shielding film 12 made of CrOM, the hard mask film 13 made of TaO is used as a pattern mask. As a result, even in dry etching under high bias conditions where the physical etching action is intensified, deformation or reduction of the pattern shape of the hard mask film 13 is suppressed, and patterning of the light shielding film 12 with high accuracy becomes possible.
By the above operation, the sidewall shape of the pattern of the light shielding film 12 formed by dry etching with the oxygen-containing chlorine-based gas becomes good, and the phase shift mask 30 with good pattern accuracy can be manufactured.

<Method of manufacturing phase shift mask (halftone type)>
Next, a method of manufacturing a halftone phase shift mask using the mask blank having the configuration shown in FIG. 3 will be described as an example. Even when the light shielding film as shown in FIG. 4 is formed of a plurality of layers, a Levenson-type phase shift mask can be manufactured by the same method.

  First, as shown in FIG. 11, the resist film 14 (first resist film) of the mask blank is exposed to a phase shift pattern and an alignment mark pattern to be formed on the phase shift film 21 using an electron beam or the like. draw. At this time, the central portion of the translucent substrate 11 is taken as a phase shift pattern formation region 11A, and a pattern corresponding to the phase shift pattern is exposed and drawn here. Further, in the outer peripheral region 11B of the phase shift pattern formation region 11A, the pattern of the alignment mark is exposed and drawn without forming the phase shift pattern. Thereafter, predetermined processing such as PEB processing, development processing, post-baking processing and the like is performed on the resist film 14 to form a first resist pattern 22 having a phase shift pattern and an alignment mark pattern.

  Next, as shown in FIG. 12, using the first resist pattern 22 as a mask, the hard mask film 13 made of TaO is dry etched using a fluorine-based gas to form the hard mask film pattern 23 on the hard mask film 13. . Thereafter, the first resist pattern 22 is removed. Here, dry etching of the light shielding film 12 may be performed with the first resist pattern 22 remaining without being removed. Even in this case, the first resist pattern 22 disappears during dry etching of the light shielding film 12.

  The dry etching using the oxygen-containing chlorine-based gas with respect to the light shielding film 12 uses an etching gas having a higher mixing ratio of the chlorine-based gas than in the past. The mixing ratio of the mixed gas of chlorine-based gas and oxygen gas in dry etching of the light shielding film 12 is preferably a chlorine-based gas: oxygen gas = 10: 1 or more at a gas flow rate ratio in the etching apparatus, 15 The ratio is more preferably 1 or more, and more preferably 20 or more. By using an etching gas with a high mixing ratio of chlorine-based gas, the anisotropy of dry etching can be enhanced. In the dry etching of the light shielding film 12, the mixing ratio of the mixed gas of chlorine gas and oxygen gas is chlorine gas: oxygen gas = 40 or less: 1 in the gas flow ratio in the etching chamber. preferable.

Further, in the dry etching of the oxygen-containing chlorine-based gas with respect to the light shielding film 12, the bias voltage applied from the back surface side of the light transmitting substrate 11 is also made higher than in the prior art. Although the effect of increasing the bias voltage is different depending on the etching apparatus, for example, the bias voltage is preferably 15 W or more, more preferably 20 W or more, and 30 W or more. And more preferred. By increasing the bias voltage, the anisotropy of dry etching of the oxygen-containing chlorine-based gas can be increased.
The light shielding pattern formed of the light shielding film 12 is formed by the above method. The light shielding pattern has a light shielding pattern in the phase shift pattern formation region 11A and a hole-shaped alignment pattern in the outer peripheral region 11B.

  Next, as shown in FIG. 13, using the hard mask film pattern 23 made of TaO as a mask, dry etching of the light shielding film 12 is performed using a mixed gas of chlorine gas and oxygen gas (oxygen containing chlorine gas). Patterning the light shielding film 12 made of CrOM. Thereby, the light shielding pattern 24 is formed.

  Even when the light shielding film 12 is formed of a plurality of layers of CrOM materials having different compositions, etching can be performed at once by the above method. For example, as in the mask blank 10A shown in FIG. 4 described above, even when the light shielding film 12 is composed of the lower layer 12A and the upper layer 12B, patterning can be performed simultaneously by one dry etching if it is made of a CrOM-based material. it can.

  Next, as shown in FIG. 14, using the light shielding pattern 24 as a mask, dry etching of the phase shift film 21 is performed using a fluorine-based gas to pattern the phase shift film 21. Thereby, the phase shift pattern 25 is formed in the phase shift pattern formation region 11A of the translucent substrate 11. Further, the alignment mark pattern 26 is formed in the outer peripheral region 11 B of the translucent substrate 11. In the dry etching of the phase shift film 21, the hard mask film pattern 23 is simultaneously removed.

  Next, as shown in FIG. 15, a resist film (second resist film) is formed in a shape covering the outer peripheral region 11B of the translucent substrate 11, and a second resist pattern 27 is formed. At this time, first, a resist film (second resist film) is formed on the translucent substrate 11 by a spin coating method. Next, exposure drawing is performed on the resist film so that the resist film having a shape covering the outer peripheral region 11B of the translucent substrate 11 remains. Thereafter, predetermined processing such as development processing is performed on the resist film. Thus, the second resist pattern 27 is formed in a shape covering the outer peripheral region 11B of the translucent substrate 11.

Next, as shown in FIG. 16, using the second resist pattern 27 as a mask, dry etching of the light shielding film 12 is performed using a mixed gas of chlorine gas and oxygen gas to form a band of light shielding film covering the outer peripheral region 11B. 12 are patterned to form a light shielding pattern 28. The dry etching of the light shielding film 12 at this time may be performed under the conventional conditions for the mixing ratio of chlorine gas and oxygen gas and the bias voltage. Also in this case, even if the light shielding film 12 is formed of a plurality of layers of CrOM materials having different compositions, patterning can be performed simultaneously by one dry etching.
Further, as shown in FIG. 17, the second resist pattern 27 is removed, and predetermined processing such as cleaning is performed to obtain a phase shift mask 31.

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

  In the phase shift mask 31 manufactured by the above steps, the light shielding pattern 28 and the phase shift film 21 in which the phase shift pattern 25 is formed in order from the light transmitting substrate 11 side are formed on the light transmitting substrate 11. The light shielding film 12 is stacked. The laminated portion of the phase shift film 21 and the light shielding film 12 has a hole-shaped alignment mark pattern 26 penetrating these.

  Among these, the phase shift pattern 25 is provided in the phase shift pattern formation region 11A set in the central portion of the translucent substrate 11. In addition, the light shielding pattern 28 is formed in a band shape surrounding the phase shift pattern formation region 11A in the outer circumferential region 11B surrounding the phase shift pattern formation region 11A. The alignment mark pattern 26 is provided in the outer peripheral region 11B.

Also in the method of manufacturing a halftone phase shift mask described above, the same effect as that of the above-described recessed Levenson phase shift mask can be obtained.
In the dry etching process of the light shielding film 12 made of CrOM, under the dry etching conditions of applying a high bias voltage using an oxygen-containing chlorine-based gas, the etching anisotropy is suppressed while suppressing the decrease in the etching rate of the light shielding film 12 made of CrOM. It is possible to enhance the tendency of sex. Thereby, side etching when forming a pattern in the light shielding film 12 is reduced.
Furthermore, by using the hard mask film 13 made of TaO as a pattern mask, deformation and reduction of the shape of the pattern mask are suppressed even under the above-mentioned conditions in which the etching rate is accelerated, and patterning of the light shielding film 12 with high accuracy is possible. Become.
Therefore, the sidewall shape of the pattern of the light shielding film 12 becomes good, and the phase shift mask 31 having good pattern accuracy can be manufactured.

<Method of manufacturing semiconductor device>
Next, a method of manufacturing a semiconductor device using the phase shift mask manufactured by the above-described manufacturing method will be described. A method of manufacturing a semiconductor device includes transferring a phase shift mask to a resist film on a substrate using a trenched Levenson type phase shift mask manufactured by the above-described manufacturing method and a halftone phase shift mask. It is characterized in that the pattern (phase shift pattern) is exposed and transferred. The manufacturing method of such a semiconductor device is performed as follows.

  First, a substrate on which a semiconductor device is to be formed is prepared. The substrate may be, for example, a semiconductor substrate, a substrate having a semiconductor thin film, or a microfabricated film may be formed on top of these. Then, a resist film is formed on the prepared substrate, and this resist film is formed using the dug-out Levenson-type phase shift mask or halftone phase shift mask manufactured by the above-described manufacturing method. Perform pattern exposure. Thereby, the transfer pattern formed on the phase shift mask is exposed and transferred onto the resist film. At this time, as the exposure light, exposure light corresponding to the phase shift film constituting the transfer pattern is used, and here, for example, ArF excimer laser light is used.

After the above, the resist film on which the transfer pattern is exposed and transferred is developed to form a resist pattern, or the resist pattern is used as a mask to etch the surface layer of the substrate, or to introduce an impurity, etc. I do. After the processing is completed, the resist pattern is removed.
The above-described processing is repeated on the substrate while exchanging the transfer mask, and the necessary processing is performed to complete the semiconductor device.

  In the manufacture of semiconductor devices as described above, initial design specifications can be obtained on a substrate by using a pitted Levenson-type phase shift mask manufactured according to the above-described manufacturing method and a halftone-type phase shift mask. It is possible to form a resist pattern with sufficient accuracy. Therefore, when the circuit pattern is formed by dry etching the lower layer film using the pattern of the resist film as a mask, it is possible to form a highly accurate circuit pattern without wiring shorts or disconnections due to insufficient accuracy.

  Hereinafter, embodiments of the present invention will be more specifically described by way of examples.

Example 1
[Manufacturing of mask blanks]
Referring to FIG. 1, a translucent substrate 11 made of synthetic quartz glass having a main surface size of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. The light-transmissive substrate 11 has its end face and main surface polished to a predetermined surface roughness (0.2 nm or less in root-mean-square roughness Rq), and is then subjected to a predetermined cleaning treatment and drying treatment.

  The surface shape of the main surface 11S on the side where the light shielding film is formed on the light transmitting substrate 11 was measured by a surface shape analyzer UltraFLAT 200M (manufactured by Corning Tropel). The area for measuring the surface shape was an area including a square inner area having a side of 142 mm on the basis of the center of the translucent substrate 11. Specifically, the area for measuring the surface shape is an area including the inner area of a square having a side of 148 mm on the basis of the center of the translucent substrate 11. In addition, also about measurement of the surface shape of each thin film formed on the translucent board | substrate 11 and the translucent board | substrate 11 currently implemented by the following Example and a comparative example, using the method similar to the above There is.

Next, the light-transmissive substrate 11 is placed in a single-wafer DC sputtering apparatus, and a mixed target of chromium (Cr) and indium (In) (Cr: In = 90 at%: 10 at%) is used. Reactive sputtering (DC sputtering) was performed in a mixed gas atmosphere of Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ) and helium (He). Thus, a light shielding film (CrInOCN film) 12 made of chromium, indium, oxygen, carbon and nitrogen was formed on the light transmitting substrate 11 to a thickness of 58 nm.

  The light transmitting substrate 11 on which the light shielding film (CrInOC film) 12 was formed was subjected to heat treatment. Specifically, heat treatment was performed using a hot plate at a heating temperature of 280 ° C. and a heating time of 5 minutes in the air. Then, for the light shielding film 12 after the heat treatment, the surface shape of the light shielding film 12 was measured using a surface shape analysis device.

  Next, the difference shape was obtained by subtracting the surface shape of the light transmitting substrate 11 from the surface shape of the light shielding film 12. For this difference shape, the difference between the maximum height and the minimum height in the inner region of the square having a side of 142 mm with respect to the center of the substrate, that is, the PV value was calculated. The PV value of the difference shape was +71 nm (the difference shape in the convex direction is “+”. The same applies hereinafter). This means that the light shielding film 12 has a compressive stress which deforms the surface shape of the light transmitting substrate 11 by the numerical value of the PV value in the inside area of a square of 142 mm on one side with respect to the center of the substrate. means.

  After a light shielding film was formed on another light transmitting substrate in the same manner, analysis was performed by X-ray photoelectron spectroscopy (ESCA, with RBS correction). The content of each constituent element of the light shielding film in the region excluding the outermost layer where oxidation proceeds is Cr = 61 at%, In = 7 at%, O = 14 at%, C = 9 at%, N = 9 It was found to be atomic%. In addition, the analysis method similar to the above is used also about the composition of the thin film in a subsequent example and a comparative example.

  The light density of the light shielding film 12 after the heat treatment is measured using a spectrophotometer (Cary 4000 manufactured by Agilent Technologies) and the optical density at the wavelength (about 193 nm) of ArF excimer laser light is 3.0 or more. It could be confirmed.

Next, the translucent substrate 11 on which the light shielding film 12 is formed is placed in a single-wafer DC sputtering apparatus, and a tantalum (Ta) target is used in a mixed gas atmosphere of argon (Ar) and oxygen (O ₂ ). Reactive sputtering (DC sputtering) was performed. Thus, a hard mask film 13 (TaO film, composition: Ta = 42 atomic%, O = 58 atomic%) consisting of tantalum and oxygen was formed in a film thickness of 6 nm in contact with the surface of the light shielding film 12. Furthermore, with respect to the hard mask film 13, the surface shape of the hard mask film 13 was measured using a surface shape analysis device. Further, predetermined cleaning treatment was performed to obtain a mask blank 10 of Example 1.

  The difference shape was obtained by subtracting the surface shape of the light transmitting substrate 11 from the surface shape of the hard mask film 13. For this difference shape, the difference between the maximum height and the minimum height in the inner region of the square having a side of 142 mm with respect to the center of the substrate, that is, the PV value was calculated. The PV value of the difference shape was +29 nm. This is because the laminated structure of the light shielding film 12 and the hard mask film 13 deforms the surface shape of the substrate by the numerical value of the PV value in an inner area of a square having 142 mm on one side with respect to the center of the substrate. It means having the From these results, it can be seen that by laminating the hard mask film 13 having a tensile stress on the light shielding film 12 having a compressive stress, it is possible to sufficiently reduce the overall film stress due to the laminated structure of two thin films. .

[Production of phase shift mask]
With reference to FIGS. 5-10, the phase shift mask 30 of Example 1 was produced in the following procedures using the mask blank 10 of Example 1 produced. First, a resist film (first resist film) 14 was formed on the hard mask film 13. Then, referring to FIG. 5, a light shielding pattern to be formed on the hard mask film 13 is drawn with an electron beam on the resist film 14, and thereafter, predetermined development processing and cleaning processing of the resist film 14 are performed. A pattern (hereinafter, these patterns are collectively referred to as a light shielding pattern etc.) was formed.

Next, as shown in FIG. 6, the hard mask film 13 is dry etched using a fluorine-based gas (CF ₄ ) using the resist film 14 having a light shielding pattern or the like as a mask, and the light mask pattern Formed. After this, the resist film 14 was removed.

Next, as shown in FIG. 7, using the hard mask film 13 having a light shielding pattern or the like as a mask, a mixed gas of chlorine gas (Cl ₂ ) and oxygen gas (O ₂ ) (gas flow ratio Cl ₂ : O ₂ = 20) Dry etching (bias voltage: 30 [W]) of the light shielding film 12 using B.1: 1) was performed to form a light shielding pattern.

  Next, as shown in FIG. 8, a resist film (second resist film) 16 in which a recess pattern is formed is formed on the hard mask film 13 in which the light shielding pattern is formed. Specifically, a resist film 16 formed of a chemically amplified resist for electron beam lithography (PRL 009 manufactured by Fujifilm Electronics Materials Co., Ltd.) was formed to a film thickness of 50 nm in contact with the surface of the hard mask film 13 by spin coating. . The film thickness of the resist film 16 is a film thickness on the hard mask film 13. Then, a digging pattern was drawn on the resist film 16 by electron beam, predetermined development processing and cleaning processing of the resist film 16 were performed, and a resist film 16 having the digging pattern was formed. At this time, the recess pattern was formed in the resist film 16 with an opening width with a margin for misalignment of lithography so that the aperture of the recess pattern formed in the resist film 16 completely exposed the aperture of the light shielding pattern. .

Thereafter, as shown in FIG. 9, dry etching of the light-transmissive substrate 11 using a fluorine-based gas (CF ₄ ) was performed using the resist film 16 having a recessed pattern as a mask. Thus, a digging pattern was formed with a depth of 173 nm in the phase shift pattern forming region 11A on the one main surface 11S side of the translucent substrate 11. In the dry etching using the fluorine-based gas, the resist film 16 was reduced in thickness, and the resist film 16 on the hard mask film 13 completely disappeared at the end of the dry etching. Furthermore, the hard mask film 13 was also removed by dry etching using a fluorine-based gas. Then, as shown in FIG. 10, the remaining resist film 16 was removed, and processing such as cleaning was performed to obtain the phase shift mask 30 of Example 1.

[Evaluation of pattern transfer performance]
A simulation of a transferred image when the phase shift mask 30 manufactured by obtaining the above procedure is exposed and transferred onto a resist film on a semiconductor device with exposure light of wavelength 193 nm using AIMS 193 (manufactured by Carl Zeiss) went. When the exposure transfer image of this simulation was verified, the design specification was sufficiently satisfied. From this result, even if the phase shift mask 30 of the first embodiment is set on the mask stage of the exposure apparatus and exposure transfer is performed on the resist film on the semiconductor device, the circuit pattern finally formed on the semiconductor device is high. It can be said that it can be formed with accuracy.

Example 2
[Manufacturing of mask blanks]
Referring to FIG. 1, in the preparation of the mask blank 10 of the above-mentioned Example 1, a CrSnOCN film (film thickness: 57 nm, composition: Cr = 60 at%) consisting of chromium, tin, oxygen, carbon and nitrogen is used as the light shielding film 12 Mask blank 10 of Example 2 in the same manner as Example 1 described above, except that Sn = 8 atomic%, O = 13 atomic%, C = 9 atomic%, N = 10 atomic%). Was produced.

Specifically, for the light shielding film 12 of the mask blank 10 of Example 2, the light transmitting substrate 11 is placed in a single-wafer type DC sputtering apparatus, and a mixed target (Cr: Cr) and tin (Sn) is used. Sn = 90 at%: 10 at%) formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ) and helium (He) did. In addition, it was 3.0 or more when the optical density in the wavelength (about 193 nm) of the light of ArF excimer laser was measured with respect to the light shielding film 12 after heat-processing in the procedure similar to Example 1. FIG.

  Similar to Example 1, the difference shape obtained by subtracting the surface shape of the light transmitting substrate 11 from the surface shape of the light shielding film 12 of the mask blank 10 of Example 2 was obtained, and the PV value of the difference shape was calculated. By the way, it was +70 nm. Further, the difference shape was obtained by subtracting the surface shape of the light transmitting substrate 11 from the surface shape of the hard mask film 13, and the PV value of the difference shape was calculated to be +28 nm. From this result, also in the case of the mask blank 10 of Example 2, by laminating the hard mask film 13 having tensile stress on the light shielding film 12 having compressive stress, the whole of the laminated structure of two thin films is obtained. It can be seen that the film stress can be sufficiently reduced.

[Production of phase shift mask]
The phase shift mask 30 of Example 2 was produced by the method similar to the above-mentioned Example 1 using the mask blank 10 produced in Example 2.

[Evaluation of pattern transfer performance]
Transfer to the resist film on the semiconductor device with the exposure light of wavelength 193 nm using AIMS 193 (manufactured by Carl Zeiss) with respect to the phase shift mask 30 of Example 2 manufactured by obtaining the above procedure The image was simulated. When the exposure transfer image of this simulation was verified, the design specification was sufficiently satisfied. From this result, even if the phase shift mask 30 of the second embodiment is set on the mask stage of the exposure apparatus and the exposure transfer is performed to the resist film on the semiconductor device, the circuit pattern finally formed on the semiconductor device is high. It can be said that it can be formed with accuracy.

Example 3
[Manufacturing of mask blanks]
With reference to FIG. 3, a translucent substrate 11 was prepared in the same manner as in Example 1. And about this translucent substrate 11, the surface shape of the main surface 11S of the side in which a light shielding film is formed was measured. The hydrogen content of the light-transmissive substrate 11 was measured by laser Raman spectroscopy and found to be 3.0 × 10 ¹⁷ molecules / cm ³ .

Next, the translucent substrate 11 is placed in a single-wafer DC sputtering apparatus, and a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 12 atomic%: 88 atomic%), argon ( Reactive sputtering (DC sputtering) was performed in a mixed gas atmosphere of Ar), nitrogen (N ₂ ) and helium (He). Thus, a phase shift film (MoSiN film) 21 composed of molybdenum, silicon and nitrogen was formed on the light transmitting substrate 11 to a film thickness of 69 nm.

  On the light transmitting substrate 11 on which the phase shift film (MoSiN film) 21 was formed, a process of forming an oxide layer on the surface layer of the phase shift film 21 was performed. Specifically, heat treatment was performed using a heating furnace (electric furnace) with the heating temperature set to 450 ° C. and the heating time set to 1 hour in the air. The phase shift film 21 after heat treatment has a composition in which the region near the surface opposite to the light transmitting substrate 11 (region from the surface to a depth of about 2 nm) has a higher oxygen content than the other regions. It could be confirmed that it had a sloped portion (oxygen content is 50 atomic% or more).

  In addition, it has been found that the content of each constituent element in the region excluding the composition inclined portion of the phase shift film 21 is Mo = 11 atomic%, Si = 40 atomic%, and N = 49 atomic% in average value. Furthermore, it was confirmed that the difference between the respective constituent elements in the thickness direction of the region excluding the composition inclination portion of the phase shift film 21 is 3 atomic% or less in all and that the composition inclination in the thickness direction is substantially not .

  The transmittance and the phase difference of the light of the ArF excimer laser at the wavelength (about 193 nm) of the heat-treated phase shift film 21 were measured using a phase shift amount measuring apparatus. The phase difference was 177.3 degrees.

  In addition, the surface shape of the phase shift film 21 after the heat treatment was measured, and the surface shape of the light transmitting substrate 11 was subtracted from the surface shape of the phase shift film 21 to obtain a difference shape. For this difference shape, the difference between the maximum height and the minimum height in the inner region of the square having a side of 142 mm with respect to the center of the substrate, that is, the PV value was calculated. The PV value of the difference shape was +27 nm. This is because the phase shift film 21 only has a compressive stress that causes the surface shape of the light transmitting substrate 11 to be deformed by the numerical value of the PV value in a rectangular inner area having a side of 142 mm on one side with respect to the center of the substrate. It means not having.

Next, the translucent substrate 11 on which the phase shift film 21 is formed is placed in a single-wafer DC sputtering apparatus, and a mixed target of chromium (Cr) and indium (In) (Cr: In = 90 at%: 10) Reactive sputtering (DC sputtering) was performed in a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ) and helium (He) using atomic percent). Thereby, a light shielding film (CrInOCN film, composition: Cr = 61 at%, In = 7 at%, O = 14 at%, C = C) on the light transmitting substrate 11 is formed of chromium, indium, oxygen, carbon and nitrogen. 9 atomic percent, N = 9 atomic percent) 12 was formed to a thickness of 41 nm.

  The light transmitting substrate 11 on which the light shielding film (CrInOCN film) 12 was formed was subjected to a heat treatment. Specifically, heat treatment was performed using a hot plate at a heating temperature of 280 ° C. and a heating time of 5 minutes in the air. With respect to the light shielding film 12 after the heat treatment, the surface shape of the light shielding film 12 was measured using a surface shape analysis device.

  Next, the difference shape was obtained by subtracting the surface shape of the phase shift film 21 from the surface shape of the light shielding film 12. For this difference shape, the difference between the maximum height and the minimum height in the inner region of the square having a side of 142 mm with respect to the center of the substrate, that is, the PV value was calculated. The PV value of the difference shape was +52 nm.

  In addition, with respect to the laminated structure of the phase shift film 21 and the light shielding film 12, the optical density at the wavelength (about 193 nm) of ArF excimer laser light was measured using a spectrophotometer (Cary 4000 manufactured by Agilent Technologies). It was confirmed that it was more than .0.

  Next, in the same procedure as in Example 1, a hard mask film 13 (TaO film, composition: Ta = 42 atomic%, O = 58 atomic%) consisting of tantalum and oxygen in contact with the surface of the light shielding film 12 ) Was formed to a film thickness of 6 nm. Furthermore, with respect to the hard mask film 13, the surface shape of the hard mask film 13 was measured using a surface shape analysis device. Further, a predetermined cleaning process was performed to obtain a mask blank 20 of Example 3.

  The difference shape is obtained by subtracting the surface shape of the phase shift film 21 from the surface shape of the hard mask film 13. For this difference shape, the difference between the maximum height and the minimum height in the inner region of the square having a side of 142 mm with respect to the center of the substrate, that is, the PV value was calculated. The PV value of the difference shape was +10 nm. This is because the laminated structure of the light shielding film 12 and the hard mask film 13 deforms the surface shape of the substrate by the numerical value of the PV value in an inner area of a square having 142 mm on one side with respect to the center of the substrate. Is meant to have. From this result, it can be seen that by laminating the hard mask film 13 having a tensile stress on the light shielding film 12 having a compressive stress, it is possible to sufficiently reduce the entire film stress due to the laminated structure of two thin films. .

[Production of phase shift mask]
The phase shift mask 31 of Example 3 was produced in the following procedure using the mask blank 20 of Example 3 produced with reference to FIGS. 11-17. First, a resist film (first resist film) 14 was formed on the hard mask film 13. Then, referring to FIG. 11, a first pattern including a phase shift pattern to be formed on the phase shift film and an alignment mark pattern is drawn on the resist film 14 by electron beam, and predetermined development processing and cleaning processing are performed. A first resist pattern 22 was formed. The first resist pattern 22 formed a 40 nm wide line-and-space phase shift pattern corresponding to the pattern dimension of the SRAF pattern.

Next, as shown in FIG. 12, using the first resist pattern 22 as a mask, the hard mask film 13 is dry etched using a fluorine-based gas (CF ₄ ), and the hard mask film pattern 23 is formed on the hard mask film 13. It formed. Thereafter, the first resist pattern 22 was removed.

Next, as shown in FIG. 13, using the hard mask film pattern 23 as a mask, the light shielding film 12 is dry etched using a mixed gas of chlorine gas (Cl ₂ ) and oxygen gas (O) to form the light shielding pattern 24. It formed.

Next, as shown in FIG. 14, using the light shielding pattern 24 as a mask, dry etching of the phase shift film 21 was performed using a fluorine-based gas (SF ₆ ). Thus, the phase shift pattern 25 is formed in the phase shift pattern formation region 11A of the translucent substrate 11. Further, in the outer peripheral region 11B of the translucent substrate 11, a hole-shaped alignment mark pattern 26 penetrating the light shielding film 12 and the phase shift film 21 is formed. At this time, the hard mask film pattern 23 was also removed simultaneously.

Next, as shown in FIG. 15, a second resist pattern 27 was formed in a shape covering the outer peripheral region 11B of the translucent substrate 11. Thereafter, as shown in FIG. 16, dry etching of the light shielding film 12 was performed using a mixed gas of chlorine (Cl ₂ ) gas and oxygen gas (O) using the second resist pattern 27 as a mask. Thereby, the light shielding film 12 is patterned to form a belt-like light shielding pattern 28 covering the outer peripheral region 11B. Next, as shown in FIG. 17, the second resist pattern 27 was removed, and predetermined processing such as cleaning was performed to obtain a phase shift mask 31 of Example 3.

[Evaluation of pattern transfer performance]
Transfer to the resist film on the semiconductor device with exposure light of wavelength 193 nm using AIMS 193 (manufactured by Carl Zeiss) with respect to the phase shift mask 31 of Example 3 manufactured by obtaining the above procedure The image was simulated. When the exposure transfer image of this simulation was verified, the design specification was sufficiently satisfied. From this result, even if the phase shift mask 31 of the third embodiment is set on the mask stage of the exposure apparatus and exposed and transferred onto the resist film on the semiconductor device, the circuit pattern finally formed on the semiconductor device is high. It can be said that it can be formed with accuracy.

Example 4
[Manufacturing of mask blanks]
Referring to FIG. 3, in the preparation of the mask blank 20 of Example 3 described above, the light shielding film 12 is formed of a CrSnOCN film (film thickness: 42 nm, composition: Cr = 60 at%) consisting of chromium, tin, oxygen, carbon and nitrogen Mask blank 20 of Example 4 in the same manner as Example 3 described above, except that it is formed of Sn = 8 atomic percent, O = 13 atomic percent, C = 9 atomic percent, N = 10 atomic percent). Was produced.

Specifically, for the light shielding film 12 of the mask blank 20 of Example 4, the light transmitting substrate 11 on which the phase shift film 21 is formed is placed in a single-wafer type DC sputtering apparatus, and chromium (Cr) and tin ( Reaction in a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ) and helium (He) using a mixed target of Sn) (Cr: Sn = 90 at%: 10 at%) Sputtering (DC sputtering). In the laminated structure of the phase shift film 21 and the light shielding film 12 of Example 3, the optical density at the wavelength (about 193 nm) of light of ArF excimer laser was measured, and was 3.0 or more.

  Similar to the third embodiment, the difference shape obtained by subtracting the surface shape of the phase shift film 21 from the surface shape of the light shielding film 12 of the mask blank 20 of the fourth embodiment is obtained, and the PV value of the difference shape is calculated. , +51 nm. Further, the difference shape is obtained by subtracting the surface shape of the phase shift film 21 from the surface shape of the hard mask film 13, and the PV value of the difference shape is calculated to be +9 nm. From this result, also in the case of the mask blank 20 of Example 4, by laminating the hard mask film 13 having a tensile stress on the light shielding film 12 having a compressive stress, the whole of the laminated structure of two thin films is obtained. It can be seen that the film stress can be sufficiently reduced.

[Production of phase shift mask]
The phase shift mask 31 of Example 4 was produced by the method similar to the above-mentioned Example 1 using the mask blank 20 produced in Example 4.

[Evaluation of pattern transfer performance]
Transfer to the resist film on the semiconductor device with exposure light of wavelength 193 nm using the AIMS 193 (manufactured by Carl Zeiss) with respect to the phase shift mask 31 of Example 4 manufactured by obtaining the above procedure The image was simulated. When the exposure transfer image of this simulation was verified, the design specification was sufficiently satisfied. From this result, even if the phase shift mask 31 of the fourth embodiment is set on the mask stage of the exposure apparatus and exposed and transferred onto the resist film on the semiconductor device, the circuit pattern finally formed on the semiconductor device is high. It can be said that it can be formed with accuracy.

Example 5
[Manufacturing of mask blanks]
Referring to FIG. 4, in the preparation of the mask blank 20 of Example 3 described above, the light shielding film 12 is formed of the lower layer 12A (CrSnOC film, film thickness: 45 nm, composition: Cr = 65 atoms) made of chromium, tin, oxygen and carbon. %, Sn = 8 atomic%, O = 16 atomic%, C = 11 atomic%), upper layer 12 B consisting of chromium, tin, oxygen and carbon (CrSnOC film, film thickness: 5 nm, composition: Cr = 47 atomic%, A mask blank 20A of Example 5 was produced by the same method as Example 3 described above except that it was formed in a laminated structure of Sn = 5 atomic%, O = 16 atomic%, C = 11 atomic%). .

Specifically, in the lower layer 12A of the mask blank 20A of the fifth embodiment, the light transmitting substrate 11 on which the phase shift film 21 is formed is placed in a single-wafer type DC sputtering apparatus, and chromium (Cr) and tin (Sn) are provided. ) By reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ) and helium (He) using the mixed target (Cr: Sn = 90 at%: 10 at%) It formed. Similar to the lower layer 12A, the upper layer 12B uses a mixed target of chromium (Cr) and tin (Sn) (Cr: Sn = 90 at%: 10 at%), and argon (Ar), carbon dioxide (CO ₂ ) and helium It was formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of (He).

  The heat treatment was performed under the same conditions as in Example 1 on the light transmitting substrate 11 on which the light shielding film 12 having a two-layer structure of the lower layer 12A and the upper layer 12B was formed. With respect to the light shielding film 12 after the heat treatment, the surface shape of the light shielding film 12 was measured using a surface shape analysis device. In the laminated structure of the phase shift film 21 and the light shielding film 12 of Example 5, the optical density at the wavelength (about 193 nm) of the light of the ArF excimer laser was measured, and was 3.0 or more.

  In the same manner as in Example 3, a difference shape obtained by subtracting the surface shape of the phase shift film 21 from the surface shape of the light shielding film 12 of the mask blank 20A of Example 5 was obtained, and the PV value of the difference shape was calculated. , +62 nm. Further, the difference shape is obtained by subtracting the surface shape of the phase shift film 21 from the surface shape of the hard mask film 13, and the PV value of the difference shape is calculated to be +20 nm. From this result, also in the case of the mask blank 20A of Example 5, by laminating the hard mask film 13 having tensile stress on the light shielding film 12 having compressive stress, the whole of the laminated structure of two thin films is obtained. It can be seen that the film stress can be sufficiently reduced.

[Production of phase shift mask]
The phase shift mask 31 of Example 5 was produced by the method similar to the above-mentioned Example 3 using mask blank 20A produced in Example 5.

[Evaluation of pattern transfer performance]
Transfer to the resist film on the semiconductor device with the exposure light of wavelength 193 nm using the AIMS 193 (manufactured by Carl Zeiss) with respect to the phase shift mask 31 of Example 5 manufactured by obtaining the above procedure The image was simulated. When the exposure transfer image of this simulation was verified, the design specification was sufficiently satisfied. From this result, even if the phase shift mask 31 of the fifth embodiment is set on the mask stage of the exposure apparatus and exposed and transferred onto the resist film on the semiconductor device, the circuit pattern finally formed on the semiconductor device is high. It can be said that it can be formed with accuracy.

Comparative Example 1
[Manufacturing of mask blanks]
In the preparation of the mask blank 10 of Example 1 described above, the hard mask film 13 is a SiON film (film thickness: 10 nm, composition: Si = 37 at%, O = 44 at%, N = 19) consisting of silicon, oxygen and nitrogen. A mask blank 10 of a comparative example was produced in the same manner as in Example 1 described above except that it was formed in atomic percent).

Specifically, for the hard mask film 13 of the mask blank 10 of the comparative example, a translucent substrate 11 on which the light shielding film 12 is formed is placed in a single-wafer type DC sputtering apparatus, and a silicon (Si) target is used. It was formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar), oxygen (O ₂ ), nitrogen (N ₂ ) and helium (He).

  Similar to Example 1, the difference shape obtained by subtracting the surface shape of the light transmitting substrate 11 from the surface shape of the light shielding film 12 of the mask blank 10 of the comparative example is obtained, and the PV value of the difference shape is calculated. , +71 nm. Further, the difference shape was obtained by subtracting the surface shape of the light transmitting substrate 11 from the surface shape of the hard mask film 13, and the PV value of the difference shape was calculated to be +123 nm. From this result, it was found that the hard mask film 13 in the mask blank 10 of Comparative Example 1 had the same compressive stress as the light shielding film 12. It is also understood that by laminating the hard mask film 13 having the same compressive stress on the light shielding film 12 having the compressive stress, the overall film stress due to the laminated structure of the two thin films is increased reversely.

[Production of phase shift mask]
Using the mask blank 10 of Comparative Example 1 described above, the phase shift mask 30 of Comparative Example 1 was manufactured in the same procedure as that of manufacturing the phase shift mask 30 of Example 1 described above.

[Evaluation of pattern transfer performance]
With respect to the phase shift mask 30 of Comparative Example 1, a transfer image was simulated when exposed and transferred onto a resist film on a semiconductor device with exposure light of wavelength 193 nm using AIMS 193 (manufactured by Carl Zeiss). When the exposure transfer image of this simulation was verified, transfer failure was confirmed. It is surmised that the cause of the transfer failure is that the verticality of the pattern side wall shape of the light shielding pattern is bad and the line edge roughness is also bad. From this result, when the phase shift mask 30 of this comparative example 1 is set on the mask stage of the exposure apparatus and exposed and transferred onto the resist film on the semiconductor device, the defective portion in the circuit pattern finally formed on the semiconductor device Can be said to occur.

  The present invention is not limited to the configuration described in the above-described embodiment, and various modifications and changes can be made without departing from the configuration of the present invention.

  10, 10A, 20, 20A mask blank, 11 translucent substrate, 11A phase shift pattern formation region, 11B peripheral region, 11S main surface, 12 light shielding film, 12A lower layer, 12B upper layer, 13 hard mask film, 14, 16 resist Film, 15 alignment pattern, 17, 25 phase shift pattern, 21 phase shift film, 22 first resist pattern, 23 hard mask film pattern, 24, 28 light shielding pattern light shielding pattern, 26 alignment mark pattern, 27 second resist pattern, 30 , 31 phase shift mask

Claims (12)

A mask blank having a structure in which a light shielding film and a hard mask film are sequentially laminated on a translucent substrate,
The light shielding film has a single layer or a laminated structure of two or more layers,
The hard mask film is provided in contact with the surface of the light shielding film,
All the layers constituting the light shielding film are formed of a material containing chromium and oxygen and further containing at least one metal element selected from indium, tin and molybdenum.
The total content of chromium and the metal element in all the layers constituting the light shielding film is 50 atomic% or more and 80 atomic% or less,
The chromium content in all the layers constituting the light shielding film is at least 40 at% and at most 60 at%,
The hard mask film is formed of a material containing tantalum and oxygen,
The oxygen content of the hard mask film state, and are more than 50 atomic%,
All layers constituting the light shielding film have a compressive stress,
The mask blank , wherein the hard mask film has a tensile stress . The mask blank according to claim 1, wherein the total content of chromium, oxygen and the metal element is 95 atomic% or more in all layers constituting the light shielding film. The mask blank according to claim 1 or 2, wherein the difference in chromium content among all the layers constituting the light shielding film is 20 atomic% or less. The ratio of the total content of the metal element to the total content of chromium and the metal element in all the layers constituting the light shielding film is 50% or less in any one of claims 1 to 3. Mask blank described in.   5. The mask blank according to claim 1, wherein the light shielding film has an optical density of 2.8 or more with respect to ArF excimer laser light.   The mask blank according to any one of claims 1 to 5, wherein the light shielding film has a thickness of 70 nm or less.   The mask blank according to any one of claims 1 to 4, further comprising a phase shift film between the light transmitting substrate and the light shielding film.   8. The mask blank according to claim 7, wherein an optical density to ArF excimer laser light in the laminated structure of the light shielding film and the phase shift film is 2.8 or more.   The said light shielding film is 60 nm or less in thickness, The mask blank of Claim 7 or 8 characterized by the above-mentioned. A method of manufacturing a phase shift mask using the mask blank according to any one of claims 1 to 6,
A resist film having a light-shielding pattern formed on the hard mask layer as a mask by dry etching using a fluorine-based gas, and forming a light shielding pattern on the hard mask layer,
The hard mask layer in which the light-shielding pattern is formed as a mask by dry etching using a mixed gas of chlorine gas and oxygen gas, and forming a light shielding pattern in the light-shielding film,
And D. forming a digging pattern on the light transmitting substrate by dry etching using a fluorine-based gas using the resist film having the digging pattern formed on the light shielding film as a mask. Method of manufacturing shift mask. A method of manufacturing a phase shift mask using the mask blank according to any one of claims 7 to 9,
Forming a phase shift pattern on the hard mask film by dry etching using a fluorine-based gas using a resist film having a phase shift pattern formed on the hard mask film as a mask;
The hard mask layer in which the phase shift pattern is formed as a mask by dry etching using a mixed gas of chlorine gas and oxygen gas, and forming a phase shift pattern in the light-shielding film,
Forming a phase shift pattern on the phase shift film by dry etching using a fluorine-based gas using the light shielding film on which the phase shift pattern is formed as a mask;
Forming a light shielding pattern on the light shielding film by dry etching using a mixed gas of a chlorine gas and an oxygen gas using a resist film having the light shielding pattern formed on the light shielding film as a mask. And a method of manufacturing a phase shift mask.   An exposure step of transferring a transfer pattern of the phase shift mask onto a semiconductor substrate by lithography using the phase shift mask manufactured by the method of manufacturing a phase shift mask according to claim 10 or 11. Semiconductor device manufacturing method.