JP6490786B2 - Mask blank, phase shift mask, and semiconductor device manufacturing method - Google Patents

Description

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

  Generally, in a semiconductor device manufacturing process, a fine pattern is formed using a photolithography method. Further, a number of substrates called transfer masks are usually used for forming this fine pattern. In order to miniaturize the pattern of a semiconductor device, it is necessary to shorten the wavelength of an exposure light source used in photolithography in addition to miniaturization of a mask pattern formed on a transfer mask. In recent years, as an exposure light source for manufacturing semiconductor devices, the wavelength has been shortened from an KrF excimer laser (wavelength 248 nm) to an ArF excimer laser (wavelength 193 nm).

  As a type of transfer mask, a halftone phase shift mask is known in addition to a binary mask having a light-shielding pattern made of a chromium-based material on a conventional translucent substrate. A molybdenum silicide (MoSi) -based material is widely used for the phase shift film of the halftone phase shift mask. However, as disclosed in Patent Document 1, it has recently been found that MoSi-based films have low resistance to ArF excimer laser exposure light (so-called ArF light resistance). In Patent Document 1, the MoSi-based film after the pattern is formed is subjected to plasma treatment, UV irradiation treatment, or heat treatment, and a passive film is formed on the surface of the MoSi-based film pattern. The ArF light resistance of the film is enhanced.

  According to Patent Document 2, the reason why the ArSi light resistance of the MoSi-based film is low is that the transition metal in the film is photoexcited by ArF excimer laser irradiation and becomes unstable. And in this patent document 2, SiNx which is a material which does not contain a transition metal is applied to the material which forms a phase shift film. In Patent Document 2, when a single layer SiNx film is formed as a phase shift film on a translucent substrate, the composition of the SiNx film that can obtain the optical characteristics required for the phase shift film is formed by a reactive sputtering method. It is shown that it is necessary to form a film under unstable film formation conditions (transition mode). And in order to solve this technical subject, the phase shift film of patent document 2 is made into the laminated structure containing a highly permeable layer and a low permeable layer. Furthermore, the SiN-based film having a relatively high nitrogen content formed in the poison mode region is applied to the high transmission layer, and the nitrogen content formed in the metal mode region is relatively used for the low transmission layer. Therefore, an extremely small number of SiN films are applied.

JP 2010-217514 A JP 2014-137388 A

  The phase shift film having a SiN-based multilayer structure disclosed in Patent Document 2 has significantly improved ArF light resistance as compared with a conventional phase shift film of a MoSi-based material. The CD change (thickness) of the pattern width that occurs when the ArF exposure light is integratedly irradiated after the transfer pattern is formed on the phase shift film having the SiN multilayer structure is larger than that of the conventional phase shift film of the MoSi material. Is greatly suppressed. However, due to circumstances such as further miniaturization of the transfer pattern and application of multiple patterning technology, the difficulty of manufacturing a transfer mask including a phase shift mask is further increased. Further, the time required to manufacture the transfer mask from the mask blank is further increased. Due to these circumstances, the price of transfer masks is rising. For this reason, it is desired to further extend the life of the transfer mask including the phase shift mask.

Si ₃ N ₄ is a stoichiometrically stable material, and ArF light resistance is superior among materials made of silicon and nitrogen. The phase shift film must have a function of transmitting ArF exposure light incident on the phase shift film with a predetermined transmittance and a function of providing a predetermined phase difference. Si ₃ N ₄ has a higher refractive index n at the wavelength of ArF exposure light than SiNx having a low nitrogen content. Therefore, when Si ₃ N ₄ is applied as the material of the phase shift film, it is predetermined for ArF exposure light. It is possible to reduce the film thickness necessary for providing the above phase difference. Henceforth, when simply describing the refractive index n, it means the refractive index n with respect to the wavelength of the ArF exposure light, and when simply describing the extinction coefficient k, extinction with respect to the wavelength of the ArF exposure light. It means the coefficient k.

  The biggest cause of the CD change of the phase shift pattern, which is a problem in ArF light resistance, is that when ArF exposure light is incident on the inside of the phase shift film, the elements constituting the phase shift film are photoexcited. It is considered. In the case of the MoSi-based material, the transition metal molybdenum (Mo) is easily photoexcited, which causes the silicon (Si) oxidation from the surface to greatly progress and the pattern volume to expand greatly. For this reason, the phase shift film of the MoSi-based material has a significant CD change (thickness) before and after irradiation with ArF exposure light. In the case of a phase shift film made of a SiN-based material, since the transition metal is not contained, the CD change before and after irradiation with ArF exposure light is relatively small. However, although silicon in the phase shift film is not as remarkable as the transition metal, it is photoexcited by irradiation with ArF exposure light.

A mask blank pattern forming thin film (including a phase shift film) for manufacturing a phase shift mask or a transfer mask is formed by sputtering under film forming conditions so as to have an amorphous or microcrystalline structure. _Si 3 _{N 4} in a thin film of amorphous or microcrystalline structure, is weakly bound state than _Si 3 _{N 4} in the crystalline film. Therefore, the Si ₃ N ₄ phase shift film having an amorphous or microcrystalline structure is likely to be photoexcited by silicon in the film by irradiation with ArF exposure light. If the phase shift film is a crystal film of Si ₃ N ₄ , it is possible to suppress photoexcitation of silicon in the film. However, when a transfer pattern is formed on a crystal film by dry etching, the roughness of the pattern side wall becomes so bad that it greatly exceeds the LER (Line Edge Roughness) allowed as a transfer pattern. It cannot be applied to a phase shift film. From these facts, it is difficult to complete a phase shift mask with a longer lifetime simply by adjusting the composition etc. based on the phase shift film of SiN-based material as disclosed in Patent Document 2. there were.

Si ₃ N ₄ is a material having a large refractive index n, but a significantly small extinction coefficient k at the wavelength of ArF exposure light. For this reason, when the phase shift film is formed of Si ₃ N ₄ and an attempt is made to design the predetermined phase difference to be slightly less than 180 degrees, only a high transmittance of about 20% or less can be produced. . If the nitrogen content of the SiN-based material is lowered, it is possible to produce a phase shift film having a predetermined phase difference and a predetermined transmittance. Naturally, however, the ArF light resistance also decreases as the nitrogen content decreases. Go. Therefore, Si ₃ when the phase shift film of low transmittance than the phase shift film consisting of N ₄ is laminated structure of the layer for adjusting the layer and the transmission ratio which the phase shift film from the Si ₃ N ₄ It is necessary to. However, when a layer for adjusting the transmittance is simply provided, the ArF light resistance of the layer is not high, and thus a phase shift mask having a further longer life cannot be completed.

Therefore, the present invention has been made to solve the conventional problems, and in a mask blank having a phase shift film on a translucent substrate, a function of transmitting ArF exposure light at a predetermined transmittance. And a phase shift film having a function of generating a predetermined phase difference with respect to the transmitted ArF exposure light, and further comprising a phase shift film having a higher ArF light resistance than a phase shift film made of Si ₃ N ₄ The purpose is to provide. Moreover, it aims at providing the phase shift mask manufactured using this mask blank. An object of the present invention is to provide a method of manufacturing a semiconductor device using such a phase shift mask.

In order to achieve the above object, the present invention has the following configuration.
(Configuration 1)
A mask blank provided with a phase shift film on a translucent substrate,
The phase shift film has a function of transmitting exposure light of ArF excimer laser with a transmittance of 2% or more, and in the air by the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. Having a phase difference of not less than 150 degrees and not more than 180 degrees with the exposure light having passed through
The phase shift film includes a structure in which a lower layer and an upper layer are stacked from the translucent substrate side,
The lower layer is formed of a material containing silicon, or a material containing one or more elements selected from non-metal elements and metalloid elements other than oxygen in a material made of silicon,
The upper layer is formed of a material comprising one or more elements selected from a material composed of silicon and nitrogen, or a material composed of silicon and nitrogen, and a nonmetallic element and a metalloid element other than oxygen, excluding the surface layer portion,
The lower layer has a refractive index n of less than 1.8 and an extinction coefficient k of 2.0 or more.
The upper layer has a refractive index n of 2.3 or more and an extinction coefficient k of 1.0 or less.
The mask blank, wherein the upper layer is thicker than the lower layer.

(Configuration 2)
The mask blank according to Configuration 1, wherein the lower layer has a thickness of less than 12 nm.
(Configuration 3)
The mask blank according to Configuration 1 or 2, wherein the thickness of the upper layer is five times or more the thickness of the lower layer.

(Configuration 4)
The lower layer is formed of a material comprising silicon and nitrogen, or a material comprising one or more elements selected from nonmetallic elements and metalloid elements other than oxygen in a material comprising silicon and nitrogen. The mask blank according to any one of configurations 1 to 3.
(Configuration 5)
5. The mask blank according to any one of configurations 1 to 4, wherein the lower layer has a nitrogen content of 40 atomic% or less.

(Configuration 6)
6. The mask blank according to any one of configurations 1 to 5, wherein a surface layer portion of the upper layer is formed of a material obtained by adding oxygen to a material forming the upper layer excluding the surface layer portion.
(Configuration 7)
The mask blank according to any one of configurations 1 to 6, wherein the upper layer has a nitrogen content larger than 50 atomic%.

(Configuration 8)
The mask blank according to any one of Structures 1 to 7, wherein the lower layer is formed in contact with the surface of the translucent substrate.
(Configuration 9)
The mask blank according to any one of configurations 1 to 8, wherein a light shielding film is provided on the phase shift film.

(Configuration 10)
The mask blank according to Configuration 9, wherein the light shielding film is made of a material containing chromium.
(Configuration 11)
The mask blank according to Configuration 9, wherein the light shielding film is made of a material containing a transition metal and silicon.

(Configuration 12)
The mask blank according to Configuration 9, wherein the light shielding film has a structure in which a layer made of a material containing chromium and a layer made of a material containing transition metal and silicon are laminated in this order from the phase shift film side. .
(Configuration 13)
13. A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to any one of Structures 9 to 12, and a light shielding pattern is formed on the light shielding film.

(Configuration 14)
14. The phase shift mask according to claim 13, wherein a back surface reflectance for the exposure light incident from the light transmitting substrate side in the region of the phase shift film where the light shielding film is not laminated is 35% or more.
(Configuration 15)
The phase according to Configuration 13 or 14, wherein a back surface reflectance with respect to the exposure light incident from the translucent substrate side in the region of the phase shift film on which the light shielding film is laminated is 30% or more. Shift mask.

(Configuration 16)
A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to any one of Structures 13 to 15.

The mask blank of the present invention includes a phase shift film on a translucent substrate, and the phase shift film functions to transmit ArF exposure light at a predetermined transmittance and to transmit ArF exposure light. Thus, the ArF light resistance can be made higher than that of the phase shift film made of Si ₃ N ₄ while having a function of generating a predetermined phase difference.

It is sectional drawing which shows the structure of the mask blank in embodiment of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the phase shift mask in embodiment of this invention.

  Embodiments of the present invention will be described below. The inventors of the present application have a function of transmitting ArF exposure light at a predetermined transmittance and a function of generating a predetermined phase difference in a phase shift film using a SiN-based material that is higher in ArF light resistance than a MoSi-based material. In order to further improve the ArF light resistance, intensive research was conducted.

As a material for forming a conventional phase shift film, a material having a refractive index n as large as possible and an extinction coefficient k within a range that is neither too large nor too small is preferred. A conventional phase shift film mainly absorbs ArF exposure light inside the phase shift film to transmit ArF exposure light at a predetermined transmittance, and has a predetermined phase difference with respect to the transmitted ArF exposure light. This is because the design concept is to be generated. When the phase shift film pattern using Si ₃ N ₄ is formed on the translucent substrate and the phase shift mask is manufactured according to the conventional design concept of the phase shift film, the inside of the phase shift film is formed from the translucent substrate side. The ArF exposure light incident on is absorbed in the phase shift film, and ArF exposure light is emitted from the phase shift film with a predetermined transmittance. When ArF exposure light is absorbed in the phase shift film, silicon in the film is photoexcited. The higher the ratio of photoexcited silicon in the phase shift film, the higher the ratio of silicon that undergoes volume expansion by binding oxygen, and the CD change amount increases.

On the other hand, when the predetermined transmittance for ArF exposure light required for the phase shift film is low and the predetermined transmittance cannot be obtained only with the Si ₃ N ₄ layer, the phase shift film has a relative nitrogen content. Therefore, it is necessary to form a laminated structure of a high permeable layer of Si ₃ N ₄ and a low permeable layer of SiN having a relatively low nitrogen content. In this case, more ArF exposure light is absorbed when the ArF exposure light is transmitted through the low transmission layer of SiN than when it is transmitted through the high transmission layer of Si ₃ N ₄ . Since the SiN low transmission layer has a low nitrogen content, the silicon in the low transmission layer is more easily photoexcited than the silicon in the Si ₃ N ₄ high transmission layer, and the CD variation in the low transmission layer is larger. It is hard to avoid. As described above, even if the design concept of the conventional phase shift film is applied, it is difficult to further improve the ArF light resistance of the phase shift film of the SiN material.

  In order to set the transmittance of the phase shift film with respect to ArF exposure light to a predetermined value, the inventors have set the reflectance (back surface reflectance) at the interface between the translucent substrate and the phase shift film as compared with the conventional phase shift film. It was thought that the light resistance against ArF exposure light of the phase shift film could be increased by increasing the height of the phase shift film. When ArF exposure light is incident on the phase shift film from the translucent substrate side, the amount of ArF exposure light reflected at the interface between the translucent substrate and the phase shift film is made higher than before, thereby allowing the phase shift film The amount of exposure light incident on the inside of the substrate can be reduced. As a result, even if the amount of ArF exposure light absorbed in the phase shift film is less than the conventional amount, the amount of ArF exposure light emitted from the phase shift film can be made equal to that of the conventional phase shift film. This makes it difficult for silicon to be photoexcited inside the phase shift film, and the ArF light resistance of the phase shift film can be improved.

In a phase shift film having a single layer structure, it is difficult to make the back surface reflectance higher than that of a conventional phase shift film. Therefore, a phase shift film having a laminated structure of a SiN-based high transmission layer and a SiN-based low transmission layer was studied. When a phase shift film in which SiN having a high nitrogen content is applied to the high transmission layer and SiN having a low nitrogen content is applied to the low transmission layer is studied, the condition of the predetermined phase difference and the predetermined transmittance is satisfied. Although it is possible to design the film, it has been found that it is difficult to increase the back surface reflectance of the entire phase shift film by simply laminating these layers. SiN having a high nitrogen content such as Si ₃ N ₄ is a material having a large refractive index n and a small extinction coefficient k, and this material is applied to the lower layer disposed on the light-transmitting substrate side of the phase shift film. Even so, the back surface reflectance for ArF exposure light does not increase. For this reason, SiN having a high nitrogen content such as Si ₃ N ₄ is applied to the upper layer of the phase shift film.

  In order to increase the back surface reflectance of the phase shift film with respect to ArF exposure light, not only the reflection at the interface between the translucent substrate and the lower layer of the phase shift film but also the interface between the lower layer and the upper layer constituting the phase shift film. It is desirable to increase the reflection. In order to satisfy these conditions, a material having a small refractive index n and a large extinction coefficient k is applied to the lower layer. Since SiN having a low nitrogen content has such optical characteristics, it was decided to apply this to the lower layer of the phase shift film. That is, a mask blank provided with a phase shift film having a structure in which a lower layer of a SiN-based material having a low nitrogen content and an upper layer of a SiN-based material having a high nitrogen content are stacked on a light-transmitting substrate.

  Since the lower layer is formed of a material having a significantly larger extinction coefficient k than that of the translucent substrate, ArF exposure light irradiated from the translucent substrate side is conventionally generated at the interface between the translucent substrate and the lower layer. The light is reflected at a higher light quantity ratio than the phase shift film. Since the upper layer is made of a material having a smaller extinction coefficient k than that of the lower layer but having a large refractive index, ArF exposure light incident on the lower layer is partially reflected also at the interface between the lower layer and the upper layer. The That is, since such a phase shift film reflects ArF exposure light at two places, the interface between the translucent substrate and the lower layer and the interface between the lower layer and the upper layer, the back surface reflection with respect to ArF exposure light is higher than that of the conventional phase shift film. The rate is high. Applying such a new design concept to the phase shift film, adjusting the film forming conditions of the material forming the upper and lower layers, adjusting the refractive index n, extinction coefficient k, and film thickness of the upper and lower layers By doing so, it was possible to form a phase shift film having a predetermined back surface reflectance while having a predetermined transmittance and a predetermined phase difference for ArF exposure light. It came to the conclusion that the above technical problem could be solved by adopting the phase shift film configuration as described above.

  That is, the present invention is a mask blank having a phase shift film on a translucent substrate, the phase shift film having a function of transmitting ArF excimer laser exposure light with a transmittance of 2% or more, and a phase shift A function of causing a phase difference of not less than 150 degrees and not more than 180 degrees between the exposure light transmitted through the film and the exposure light that has passed through the air by the same distance as the thickness of the phase shift film, The shift film includes a structure in which a lower layer and an upper layer are laminated from the translucent substrate side, and the lower layer is made of silicon, or one or more selected from non-metal elements and metalloid elements other than oxygen in a material made of silicon. The upper layer is made of a material consisting of silicon and nitrogen, or a material consisting of silicon and nitrogen, or a nonmetallic element and a metalloid element excluding oxygen. The lower layer has a refractive index n of less than 1.8, an extinction coefficient k of 2.0 or more, and the upper layer has a refractive index n of 2.3. The mask blank is characterized in that the extinction coefficient k is 1.0 or less and the upper layer is thicker than the lower layer.

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

The translucent substrate 1 can be formed of quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass or the like), in addition to synthetic quartz glass. Among these, synthetic quartz glass has a high transmittance with respect to ArF excimer laser light, and is particularly preferable as a material for forming the translucent substrate 1 of the mask blank. The refractive index n of the material forming the translucent substrate 1 at the wavelength of ArF exposure light (approximately 193 nm) is preferably 1.5 or more and 1.6 or less, and is 1.52 or more and 1.59 or less. More preferably, it is 1.54 or more and 1.58 or less.

  The phase shift film 2 is required to have a transmittance of 2% or more for ArF exposure light. In order to produce a sufficient phase shift effect between the exposure light transmitted through the inside of the phase shift film 2 and the exposure light transmitted through the air, the transmittance with respect to the exposure light is required to be at least 2%. The transmittance of the phase shift film 2 with respect to exposure light is preferably 3% or more, and more preferably 4% or more. On the other hand, as the transmittance of the phase shift film 2 with respect to the exposure light increases, it becomes difficult to increase the back surface reflectance. For this reason, the transmittance with respect to the exposure light of the phase shift film 2 is preferably 30% or less, more preferably 20% or less, and further preferably 10% or less.

  In order to obtain an appropriate phase shift effect, the phase shift film 2 has a phase difference of 150 between the transmitted ArF exposure light and the light that has passed through the air by the same distance as the thickness of the phase shift film 2. It is required to be adjusted to be in the range of not less than 180 degrees and not more than 180 degrees. The phase difference in the phase shift film 2 is preferably 155 degrees or more, and more preferably 160 degrees or more. On the other hand, the phase difference in the phase shift film 2 is preferably 179 degrees or less, and more preferably 177 degrees or less. This is to reduce the influence of an increase in phase difference caused by minute etching of the translucent substrate 1 during dry etching when forming a pattern on the phase shift film 2. Further, in recent years, ArF exposure light is applied to the phase shift mask by an exposure apparatus, and the number of ArF exposure light incident from a direction inclined at a predetermined angle with respect to the direction perpendicular to the film surface of the phase shift film 2 is increasing. It is because it is.

  From the viewpoint of suppressing ArF exposure light from being incident on the inside of the phase shift film 2 and photoexciting silicon, the phase shift film 2 can be used in a state where only the phase shift film 2 exists on the translucent substrate 1. The reflectance (back surface reflectance) on the translucent substrate 1 side (back surface side) with respect to exposure light is required to be at least 35% or more. The state where only the phase shift film 2 exists on the translucent substrate 1 means that when the phase shift mask 200 (see FIG. 2G) is manufactured from the mask blank 100, the light shielding pattern is formed on the phase shift pattern 2a. This refers to a state where 3b is not laminated (a region of the phase shift pattern 2a where the light shielding pattern 3b is not laminated). On the other hand, if the back surface reflectance in the state where only the phase shift film 2 exists is too high, the phase shift mask 200 manufactured from the mask blank 100 is used to expose a transfer target (such as a resist film on a semiconductor wafer). When the transfer is performed, the influence of the reflected light on the back surface side of the phase shift film 2 on the exposure transfer image is increased, which is not preferable. From this viewpoint, the back surface reflectance of the phase shift film 2 with respect to ArF exposure light is preferably 45% or less.

  The phase shift film 2 has a structure in which a lower layer 21 and an upper layer 22 are laminated from the translucent substrate 1 side. The entire phase shift film 2 needs to satisfy at least the above-described conditions of transmittance, phase difference, and back surface reflectance. In order for the phase shift film 2 to satisfy the above conditions, the refractive index n of the lower layer 21 is required to be less than 1.80. The refractive index n of the lower layer 21 is preferably 1.75 or less, and more preferably 1.70 or less. Further, the refractive index n of the lower layer 21 is preferably 1.00 or more, and more preferably 1.10 or more. The extinction coefficient k of the lower layer 21 is required to be 2.00 or more. The extinction coefficient k of the lower layer 21 is preferably 2.10 or more, and more preferably 2.20 or more. Further, the extinction coefficient k of the lower layer 21 is preferably 2.90 or less, and more preferably 2.80 or less. The refractive index n and the extinction coefficient k of the lower layer 21 are values derived by regarding the entire lower layer 21 as one optically uniform layer.

  In order for the phase shift film 2 to satisfy the above conditions, the refractive index n of the upper layer 22 is required to be 2.30 or more. The refractive index n of the upper layer 22 is preferably 2.40 or more. Further, the refractive index n of the upper layer 22 is preferably 2.80 or less, and more preferably 2.70 or less. The extinction coefficient k of the upper layer 22 is required to be 1.00 or less. The extinction coefficient k of the upper layer 22 is preferably 0.90 or less, and more preferably 0.70 or less. Further, the extinction coefficient k of the upper layer 22 is preferably 0.20 or more, and more preferably 0.30 or more. Note that the refractive index n and the extinction coefficient k of the upper layer 22 are values derived by regarding the entire upper layer 22 including a surface layer portion described later as one optically uniform layer.

  The refractive index n and extinction coefficient k of the thin film including the phase shift film 2 are not determined only by the composition of the thin film. The film density and crystal state of the thin film are factors that influence the refractive index n and the extinction coefficient k. For this reason, various conditions when forming a thin film by reactive sputtering are adjusted, and the thin film is formed so as to have a desired refractive index n and extinction coefficient k. In order to make the lower layer 21 and the upper layer 22 in the range of the above-mentioned refractive index n and extinction coefficient k, a mixture of a rare gas and a reactive gas (oxygen gas, nitrogen gas, etc.) is used when forming a film by reactive sputtering. It is not limited to adjusting the gas ratio. There are a variety of positional relationships such as the pressure in the film forming chamber during film formation by reactive sputtering, the power applied to the sputtering target, and the distance between the target and the translucent substrate 1. These film forming conditions are unique to the film forming apparatus, and are appropriately adjusted so that the lower layer 21 and the upper layer 22 to be formed have a desired refractive index n and extinction coefficient k.

  In order for the phase shift film 2 to satisfy the above conditions, in addition to the optical characteristics of the lower layer 21 and the upper layer 22, the thickness of the upper layer 22 needs to be at least thicker than the thickness of the lower layer 21. The upper layer 22 is made of a material having a high nitrogen content in order to satisfy the required optical characteristics, and the ArF light resistance tends to be relatively high, whereas the lower layer 21 satisfies the required optical characteristics. A material having a low nitrogen content is applied to the glass, and the ArF light resistance tends to be relatively low. Considering that the reason why the back surface reflectance of the phase shift film 2 is increased is to increase the ArF light resistance of the phase shift film 2, the thickness of the lower layer 21 that tends to have a relatively low ArF light resistance. This is because it is necessary to make it thinner than the thickness of the upper layer 22 which tends to have relatively high ArF light resistance.

  It is desirable that the thickness of the lower layer 21 be as thin as possible within a range that can satisfy the conditions of predetermined transmittance, phase difference, and back surface reflectance required for the phase shift film 2. The thickness of the lower layer 21 is preferably less than 12 nm, more preferably 11 nm or less, and even more preferably 10 nm or less. Further, considering the point of the back surface reflectance of the phase shift film 2 in particular, the thickness of the lower layer 21 is preferably 3 nm or more, more preferably 4 nm or more, and further preferably 5 nm or more.

  Since the upper layer 22 is formed of a material having relatively high ArF light resistance, the entire phase shift film 2 is within a range that can satisfy the predetermined transmittance, phase difference, and back surface reflectance requirements for the phase shift film 2. It is desired to increase the ratio of the thickness of the upper layer 22 to the film thickness as much as possible. The thickness of the upper layer 22 is preferably 5 times or more than the thickness of the lower layer 21, more preferably 5.5 times or more, and even more preferably 6 times or more. The thickness of the upper layer 22 is more preferably 10 times or less the thickness of the lower layer 21. The thickness of the upper layer 22 is preferably 80 nm or less, more preferably 70 nm or less, and further preferably 65 nm or less. Further, the thickness of the upper layer 22 is preferably 50 nm or more, and more preferably 55 nm or more.

  The lower layer 21 is formed of a material made of silicon, or a material containing one or more elements selected from non-metal elements and metalloid elements excluding oxygen in a material made of silicon. The lower layer 21 does not contain a transition metal that can cause a decrease in light resistance to ArF exposure light. Since it is impossible to deny the possibility that the light resistance to ArF exposure light can be reduced, it is desirable not to include metal elements other than transition metals. The lower layer 21 may contain any metalloid element in addition to silicon. Among these metalloid elements, it is preferable to include one or more elements selected from boron, germanium, antimony, and tellurium because it can be expected to increase the conductivity of silicon used as a sputtering target.

  The lower layer 21 may contain a nonmetallic element other than oxygen. Among these nonmetallic elements, it is preferable to contain one or more elements selected from nitrogen, carbon, fluorine and hydrogen. This nonmetallic element also includes rare gases such as helium (He), argon (Ar), krypton (Kr), and xenon (Xe). The lower layer 21 does not actively contain oxygen (the oxygen content when the composition analysis is performed by X-ray photoelectron spectroscopy or the like is equal to or lower than the detection lower limit value). This is because the lowering of the extinction coefficient k of the lower layer 21 caused by containing oxygen in the material forming the lower layer 21 is larger than that of other nonmetallic elements, and the back surface reflectance of the phase shift film 2 is not greatly reduced. .

  The lower layer 21 is preferably formed of a material containing silicon and nitrogen, or a material containing one or more elements selected from a nonmetallic element and a metalloid element excluding oxygen in a material consisting of silicon and nitrogen. This is because the silicon-containing material containing nitrogen has higher light resistance to ArF exposure light than the silicon-containing material not containing nitrogen. Moreover, it is because the oxidation of the pattern side wall when the phase shift pattern is formed in the lower layer 21 is suppressed. However, as the nitrogen content in the material forming the lower layer 21 increases, the refractive index n increases and the extinction coefficient k decreases. For this reason, the nitrogen content in the material forming the lower layer 21 is preferably 40 atomic percent or less, more preferably 36 atomic percent or less, and even more preferably 32 atomic percent or less.

  The upper layer 22 is formed of a material made of silicon and nitrogen, or a material containing one or more elements selected from non-metal elements and metalloid elements excluding oxygen in a material made of silicon and nitrogen, except for the surface layer portion. . The surface layer portion of the upper layer 22 refers to the surface layer portion on the opposite side of the upper layer 22 from the lower layer 21 side. After film formation of the phase shift film 2 on the translucent substrate 1 with the film forming apparatus, the film surface is cleaned. Since the surface layer portion of the upper layer 22 is exposed to a cleaning solution or a rinsing solution during the cleaning process, it is difficult to avoid oxidation regardless of the composition during film formation. Further, the oxidation of the surface layer portion of the upper layer 22 also proceeds when the phase shift film 2 is exposed to the atmosphere or heat treatment is performed in the atmosphere. As described above, the upper layer 22 is preferably a material having a high refractive index n. Since the refractive index n tends to decrease as the oxygen content in the material increases, oxygen is not actively contained in the upper layer 22 at the time of film formation except for the surface layer portion (such as X-ray photoelectron spectroscopy). The oxygen content when the composition analysis is performed is less than the detection lower limit.) From these things, the surface layer part of the upper layer 22 is formed with the material which added oxygen to the material which forms the upper layer except a surface layer part.

  The surface layer portion of the upper layer 22 may be formed by various oxidation treatments. This is because the surface layer can be a stable oxide layer. Examples of the oxidation treatment include a heat treatment in a gas containing oxygen such as the atmosphere, a light irradiation treatment using a flash lamp in a gas containing oxygen, a treatment in which ozone or oxygen plasma is brought into contact with the surface of the upper layer 22, and the like. Is given. In particular, it is preferable to use a heat treatment that can simultaneously reduce the film stress of the phase shift film 2 or a light irradiation treatment using a flash lamp. The surface layer portion of the upper layer 22 preferably has a thickness of 1 nm or more, more preferably 1.5 nm or more. Further, the surface layer portion of the upper layer 22 preferably has a thickness of 5 nm or less, and more preferably 3 nm or less.

  The upper layer 22 does not contain a transition metal that can cause a decrease in light resistance to ArF exposure light. Since it is impossible to deny the possibility that the light resistance to ArF exposure light can be reduced, it is desirable not to include metal elements other than transition metals. The upper layer 22 may contain any metalloid element in addition to silicon. Among these metalloid elements, it is preferable to include one or more elements selected from boron, germanium, antimony, and tellurium because it can be expected to increase the conductivity of silicon used as a sputtering target.

  The upper layer 22 may contain a nonmetallic element other than oxygen. Among these nonmetallic elements, it is preferable to contain one or more elements selected from nitrogen, carbon, fluorine and hydrogen. This nonmetallic element also includes rare gases such as helium (He), argon (Ar), krypton (Kr), and xenon (Xe). The upper layer 22 is preferably a material having a higher refractive index n, and the silicon-based material tends to have a higher refractive index n as the nitrogen content increases. For this reason, it is preferable that the total content of the metalloid element and the nonmetal element contained in the material forming the upper layer 22 is 10 atomic% or less, more preferably 5 atomic% or less, and not actively contained. Further preferred. On the other hand, for the above reason, the nitrogen content in the material forming the upper layer 22 is required to be at least higher than the nitrogen content in the material forming the lower layer 21. The nitrogen content in the material forming the upper layer 22 is preferably greater than 50 atomic%, more preferably 52 atomic% or more, and even more preferably 55 atomic% or more.

  The lower layer 21 is preferably formed in contact with the surface of the translucent substrate 1. This is because the configuration in which the lower layer 21 is in contact with the surface of the translucent substrate 1 is more effective in increasing the back surface reflectance generated by the laminated structure of the lower layer 21 and the upper layer 22 of the phase shift film 2 described above. An etching stopper film may be provided between the translucent substrate 1 and the phase shift film 2 if the influence on the effect of increasing the back surface reflectance of the phase shift film 2 is very small. In this case, the thickness of the etching stopper film needs to be 10 nm or less, preferably 7 nm or less, and more preferably 5 nm or less. From the viewpoint of effectively functioning as an etching stopper, the thickness of the etching stopper film needs to be 3 nm or more. The extinction coefficient k of the material forming the etching stopper film needs to be less than 0.1, preferably 0.05 or less, and more preferably 0.01 or less. In this case, the refractive index n of the material forming the etching stopper film is required to be at least 1.9 or less, and is preferably 1.7 or less. The refractive index n of the material forming the etching stopper film is preferably 1.55 or more.

  It is preferable that both the material forming the lower layer 21 and the material forming the upper layer 22 excluding the surface layer portion are composed of the same element. The upper layer 22 and the lower layer 21 are patterned by dry etching using the same etching gas. For this reason, it is desirable to etch the upper layer 22 and the lower layer 21 in the same etching chamber. If the elements constituting each material forming the upper layer 22 and the lower layer 21 are the same, the environmental change in the etching chamber when the object to be dry-etched from the upper layer 22 to the lower layer 21 changes can be reduced. it can. When the phase shift film 2 is patterned by dry etching with the same etching gas, the ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 is preferably 3.0 or less, and is 2.5 or less. More preferred. Further, when the phase shift film 2 is patterned by dry etching with the same etching gas, the ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 is preferably 1.0 or more.

  The lower layer 21 and the upper layer 22 in the phase shift film 2 are formed by sputtering, but any sputtering such as DC sputtering, RF sputtering, and ion beam sputtering can be applied. In consideration of the deposition rate, it is preferable to apply DC sputtering. In the case of using a target with low conductivity, it is preferable to apply RF sputtering or ion beam sputtering, but it is more preferable to apply RF sputtering in consideration of the film formation rate.

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

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

  The mask blank 100 in the form shown in FIG. 1 has a configuration in which the light shielding film 3 is laminated on the phase shift film 2 without interposing another film. For the light shielding film 3 in this configuration, it is necessary to apply a material having sufficient etching selectivity with respect to an etching gas used when a pattern is formed on the phase shift film 2. In this case, the light-shielding film 3 is preferably formed of a material containing chromium. Examples of the material containing chromium forming the light-shielding film 3 include a material containing one or more elements selected from oxygen, nitrogen, carbon, boron, and fluorine in addition to chromium metal.

  In general, a chromium-based material is etched with a mixed gas of a chlorine-based gas and an oxygen gas, but chromium metal does not have a high etching rate with respect to this etching gas. In consideration of increasing the etching rate of the mixed gas of chlorine-based gas and oxygen gas with respect to the etching gas, the material for forming the light shielding film 3 is one or more elements selected from chromium, oxygen, nitrogen, carbon, boron and fluorine. A material containing is preferred. Moreover, you may make the material containing chromium which forms the light shielding film 3 contain one or more elements among molybdenum, indium, and tin. By including one or more elements of molybdenum, indium and tin, the etching rate for the mixed gas of chlorine-based gas and oxygen gas can be further increased.

  Further, the light-shielding film 3 may be formed of a material containing a transition metal and silicon as long as the etching selectivity for dry etching can be obtained with the material forming the upper layer 22 (particularly the surface layer portion). This is because a material containing a transition metal and silicon has a high light shielding performance, and the thickness of the light shielding film 3 can be reduced. As transition metals to be contained in the light shielding film 3, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V) , Zirconium (Zr), ruthenium (Ru), rhodium (Rh), zinc (Zn), niobium (Nb), palladium (Pd), and any one metal or an alloy of these metals. Examples of the metal element other than the transition metal element contained in the light shielding film 3 include aluminum (Al), indium (In), tin (Sn), and gallium (Ga).

  On the other hand, as the light-shielding film 3 of the mask blank 100 of another embodiment, the light-shielding structure has a structure in which a layer made of a material containing chromium and a layer made of a material containing a transition metal and silicon are laminated in this order from the phase shift film 2 side. A membrane 3 may be provided. The specific matters of the material containing chromium and the material containing transition metal and silicon in this case are the same as those of the light shielding film 3 described above.

  In the mask blank 100, in the state where the phase shift film 2 and the light shielding film 3 are laminated, it is preferable that the reflectance (back surface reflectance) on the light transmitting substrate 1 side (back surface side) with respect to ArF exposure light is 30% or more. When the light shielding film 3 is formed of a material containing chromium, or when the layer on the phase shift film 2 side of the light shielding film 3 is formed of a material containing chromium, ArF exposure light incident on the light shielding film 3 When the amount of light is large, a phenomenon in which chromium is photoexcited and chromium moves to the phase shift film 2 side easily occurs. By making the back surface reflectance with respect to ArF exposure light in a state where the phase shift film 2 and the light shielding film 3 are laminated to be 30% or more, the movement of chromium can be suppressed. Further, when the light shielding film 3 is formed of a material containing a transition metal and silicon, if the amount of ArF exposure light incident on the light shielding film 3 is large, the transition metal is photoexcited and the transition metal is moved to the phase shift film 2 side. The phenomenon of moving is more likely to occur. By making the back surface reflectance with respect to ArF exposure light in a state where the phase shift film 2 and the light shielding film 3 are laminated to be 30% or more, the movement of the transition metal can be suppressed.

  The mask blank 100 preferably has a structure in which a hard mask film 4 formed of a material having etching selectivity with respect to an etching gas used when etching the light shielding film 3 is further laminated on the light shielding film 3. Since the hard mask film 4 is basically not restricted by the optical density, the thickness of the hard mask film 4 can be made much thinner than the thickness of the light shielding film 3. The resist film made of an organic material is sufficient to have a thickness sufficient to function as an etching mask until dry etching for forming a pattern on the hard mask film 4 is completed. The thickness can be greatly reduced. Thinning the resist film is effective in improving resist resolution and preventing pattern collapse, and is extremely important in meeting the demand for miniaturization.

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

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

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

  FIG. 2 shows a phase shift mask 200 according to an embodiment of the present invention manufactured from the mask blank 100 of the above embodiment and its manufacturing process. As shown in FIG. 2G, in the phase shift mask 200, the phase shift pattern 2 a that is a transfer pattern is formed on the phase shift film 2 of the mask blank 100, and the light shielding pattern 3 b is formed on the light shielding film 3. It is characterized by having. In the case where the hard mask film 4 is provided on the mask blank 100, the hard mask film 4 is removed while the phase shift mask 200 is being formed.

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

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

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

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

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

  The phase shift mask 200 of the present invention is produced using the mask blank 100 described above. Therefore, the phase shift film 2 (phase shift pattern 2a) on which the transfer pattern is formed has a transmittance for ArF exposure light of 2% or more, and the thickness of the exposure light transmitted through the phase shift pattern 2a and the phase shift pattern 2a. The phase difference between the exposure light and the exposure light that has passed through the air by the same distance is within the range of 150 degrees to 180 degrees. Further, this phase shift mask 200 has a back surface reflectance of 35% or more in the region of the phase shift pattern 2a where the light shielding pattern 3b is not laminated (the region on the translucent substrate 1 where only the phase shift pattern 2a exists). It has become. As a result, the amount of ArF exposure light incident on the inside of the phase shift film 2 can be reduced, and photoexcitation of silicon in the phase shift film 2 by the ArF exposure light can be suppressed.

  The phase shift mask 200 preferably has a back surface reflectance of 45% or less in the region of the phase shift pattern 2a where the light shielding pattern 3b is not stacked. When exposure transfer is performed on an object to be transferred (such as a resist film on a semiconductor wafer) using the phase shift mask 200, the reflected light on the back side of the phase shift pattern 2a does not affect the exposure transfer image. It is to do.

  The phase shift mask 200 preferably has a back surface reflectance of 30% or more in the region on the translucent substrate 1 of the phase shift pattern 2a in which the light shielding patterns 3b are stacked. When the light shielding pattern 3b is formed of a material containing chromium, or when the layer on the phase shift pattern 2a side of the light shielding pattern 3b is formed of a material containing chromium, the chromium in the light shielding pattern 3b is the phase shift pattern. It can suppress moving in 2a. Moreover, when the light shielding pattern 3b is formed with the material containing a transition metal and silicon, it can suppress that the transition metal in the light shielding pattern 3b moves in the phase shift pattern 2a.

  The semiconductor device manufacturing method of the present invention is characterized in that the transfer pattern is exposed and transferred onto a resist film on a semiconductor substrate using the phase shift mask 200 described above. The phase shift pattern 2a of the phase shift mask 200 has significantly improved light resistance against ArF exposure light. For this reason, the phase shift mask 200 is set in an exposure apparatus, and ArF exposure light is irradiated from the light transmissive substrate 1 side of the phase shift mask 200 to an object to be transferred (such as a resist film on a semiconductor wafer). Even if the process is continuously performed, the CD change amount of the phase shift pattern 2a is small, and the desired pattern can be continuously transferred to the transfer object with high accuracy.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.
Example 1
[Manufacture of mask blanks]
A translucent substrate 1 made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. This translucent substrate 1 has its end face and main surface polished to a predetermined surface roughness, and then subjected to a predetermined cleaning process and drying process. When the optical characteristics of the translucent substrate 1 were measured, the refractive index n was 1.556 and the extinction coefficient k was 0.00.

Next, the translucent substrate 1 is set in a single wafer RF sputtering apparatus, and a surface of the translucent substrate 1 is formed by RF sputtering using a silicon (Si) target and argon (Ar) gas as a sputtering gas. In contact therewith, a lower layer 21 (Si film) of the phase shift film 2 made of silicon was formed with a thickness of 8 nm. Subsequently, a phase shift composed of silicon and nitrogen is formed on the lower layer 21 by reactive sputtering (RF sputtering) using a silicon (Si) target and a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas. The upper layer 22 of the film 2 (SiN film Si: N = 43 atomic%: 57 atomic%) was formed with a thickness of 63 nm. By the above procedure, the phase shift film 2 in which the lower layer 21 and the upper layer 22 were laminated in contact with the surface of the translucent substrate 1 was formed with a thickness of 71 nm. In the phase shift film 2, the thickness of the upper layer 22 is 7.9 times the thickness of the lower layer 21. The compositions of the lower layer 21 and the upper layer 22 are results obtained by measurement by X-ray photoelectron spectroscopy (XPS). The same applies to other films.

  Next, a heat treatment for reducing the film stress of the phase shift film 2 and forming an oxide layer on the surface layer was performed on the translucent substrate 1 on which the phase shift film 2 was formed. Using a phase shift amount measuring apparatus (MPM193 manufactured by Lasertec Corporation), the transmittance and phase difference of the phase shift film 2 with respect to light having a wavelength of 193 nm were measured. The transmittance was 6.1% and the phase difference was 177.0. Degree. Further, when this phase shift film 2 was analyzed by STEM (Scanning Electron Microscope) and EDX (Energy Dispersive X-Ray Spectroscopy), an oxide layer was formed in a surface layer portion having a thickness of about 2 nm from the surface of the upper layer 22. It was confirmed that it was formed. Further, when the optical characteristics of the lower layer 21 and the upper layer 22 of the phase shift film 2 were measured, the lower layer 21 had a refractive index n of 1.06 and an extinction coefficient k of 2.72, and the upper layer 22 had a refractive index. n was 2.63 and the extinction coefficient k was 0.37. The back surface reflectance (reflectance on the translucent substrate 1 side) of the phase shift film 2 with respect to light having a wavelength of 193 nm was 44.1%.

Next, the translucent substrate 1 on which the phase shift film 2 is formed is installed in a single-wafer DC sputtering apparatus, and using a chromium (Cr) target, argon (Ar), carbon dioxide (CO ₂ ), nitrogen ( A light shielding film 3 (CrOCN film Cr: O: C: N = 55 atoms) made of CrOCN on the phase shift film 2 by reactive sputtering (DC sputtering) using a mixed gas of N ₂ ) and helium (He) as a sputtering gas. %: 22 atomic%: 12 atomic%: 11 atomic%) was formed with a thickness of 46 nm. In the state where the phase shift film 2 and the light shielding film 3 are laminated on the light transmissive substrate 1, the back surface reflectance (reflectance on the light transmissive substrate 1 side) with respect to light having a wavelength of 193 nm was 42.7%. The optical density (OD) of light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was measured and found to be 3.0 or more. Further, another light-transmitting substrate 1 was prepared, and only the light-shielding film 3 was formed under the same film-forming conditions, and the optical characteristics of the light-shielding film 3 were measured. The refractive index n was 1.95, the extinction coefficient. k was 1.53.

Next, the translucent substrate 1 in which the phase shift film 2 and the light-shielding film 3 are laminated is placed in a single wafer RF sputtering apparatus, and argon (Ar) gas is sputtered using a silicon dioxide (SiO ₂ ) target. A hard mask film 4 made of silicon and oxygen was formed to a thickness of 5 nm on the light shielding film 3 by RF sputtering using gas. By the above procedure, a mask blank 100 having a structure in which a phase shift film 2 having a two-layer structure, a light shielding film 3 and a hard mask film 4 were laminated on a translucent substrate 1 was manufactured.

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

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

Subsequently, using the hard mask pattern 4a as a mask, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 10: 1) is performed, and the first pattern (light shielding pattern) is formed on the light shielding film 3. 3a) was formed (see FIG. 2 (c)). Next, using the light shielding pattern 3a as a mask, dry etching using fluorine-based gas (SF ₆ + He) is performed to form a first pattern (phase shift pattern 2a) on the phase shift film 2, and at the same time, a hard mask pattern 4a was removed (see FIG. 2 (d)).

Next, a resist film made of a chemically amplified resist for electron beam lithography was formed on the light-shielding pattern 3a with a film thickness of 150 nm by spin coating. Next, a second pattern, which is a pattern (light-shielding pattern) to be formed on the light-shielding film, is exposed and drawn on the resist film, and further subjected to a predetermined process such as a development process, whereby the second resist having the light-shielding pattern A pattern 6b was formed (see FIG. 2E). Subsequently, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed using the second resist pattern 6b as a mask, and the second pattern ( A light shielding pattern 3b) was formed (see FIG. 2F). Further, the second resist pattern 6b was removed, and a predetermined process such as cleaning was performed to obtain a phase shift mask 200 (see FIG. 2G). The ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 when the dry etching using SF ₆ + He was performed on the phase shift film 2 was 2.06.

In the manufactured halftone phase shift mask 200 of Example 1, the region of the phase shift pattern 2a where the light shielding pattern 3b is not stacked is intermittently irradiated with ArF excimer laser light so that the integrated dose becomes 40 kJ / cm ^2. Irradiation treatment was performed. The CD change amount of the phase shift pattern 2a before and after this irradiation treatment was 1.5 nm. This CD change amount is improved as compared with the CD change amount (3.2 nm) generated before and after the same irradiation treatment with respect to the phase shift pattern having a single layer structure of Si ₃ N ₄ .

Furthermore, when the ArF excimer laser light irradiation treatment is performed and the phase shift mask 200 is exposed and transferred to a resist film on a semiconductor device with an exposure light having a wavelength of 193 nm using an AIMS 193 (manufactured by Carl Zeiss). The exposure transfer image was simulated at. When the exposure transfer image obtained by this simulation was verified, the design specifications were sufficiently satisfied. From the above, the phase shift mask 200 manufactured from the mask blank of Example 1 is set in an exposure apparatus and subjected to exposure transfer with exposure light of an ArF excimer laser until the integrated dose reaches 40 kJ / cm ^2. However, it can be said that exposure transfer can be performed with high accuracy to the resist film on the semiconductor device.

On the other hand, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light shielding pattern 3b is laminated in the halftone phase shift mask 200 of Example 1 so that the integrated irradiation amount becomes 40 kJ / cm ^2. Irradiation treatment was performed. When the secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the region subjected to the irradiation treatment, the chromium content of the phase shift pattern 2a was very small. From the above, the phase shift mask 200 manufactured from the mask blank of Example 1 is shielded when the ArF excimer laser exposure light is irradiated to the phase shift pattern 2a on which the light shielding pattern 3b is laminated. It can be said that the chromium in the pattern 3b can be sufficiently suppressed from moving into the phase shift pattern 2a.

(Example 2)
[Manufacture of mask blanks]
The mask blank 100 of Example 2 was manufactured in the same procedure as in Example 1 except for the phase shift film 2. In the phase shift film 2 of the second embodiment, the material and thickness of the lower layer 21 are changed, and the thickness of the upper layer 22 is changed. Specifically, the translucent substrate 1 is installed in a single wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) is used as a sputtering gas. By sputtering (RF sputtering), the lower layer 21 (SiN film Si: N = 68 atomic%: 32 atomic%) of the phase shift film 2 made of silicon and nitrogen is in contact with the surface of the light-transmitting substrate 1 with a thickness of 9 nm. Formed. Subsequently, a phase shift composed of silicon and nitrogen is formed on the lower layer 21 by reactive sputtering (RF sputtering) using a silicon (Si) target and a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas. The upper layer 22 of the film 2 (SiN film Si: N = 43 atomic%: 57 atomic%) was formed with a thickness of 59 nm. By the above procedure, the phase shift film 2 in which the lower layer 21 and the upper layer 22 were laminated in contact with the surface of the translucent substrate 1 was formed with a thickness of 68 nm. In the phase shift film 2, the thickness of the upper layer 22 is 6.6 times the thickness of the lower layer 21.

  Also, the heat treatment was performed on the phase shift film 2 of Example 2 under the same processing conditions as in Example 1. Using a phase shift amount measuring apparatus (MPM193 manufactured by Lasertec Corporation), the transmittance and phase difference of the phase shift film 2 with respect to light having a wavelength of 193 nm were measured. The transmittance was 6.1% and the phase difference was 177.0. Degree. Further, when this phase shift film 2 was analyzed by STEM and EDX, it was confirmed that an oxide layer was formed in a surface layer portion having a thickness of about 2 nm from the surface of the upper layer 22. Further, when the optical properties of the lower layer 21 and the upper layer 22 of the phase shift film 2 were measured, the lower layer 21 had a refractive index n of 1.48, an extinction coefficient k of 2.35, and the upper layer 22 had a refractive index. n was 2.63 and the extinction coefficient k was 0.37. The back surface reflectance (reflectance on the translucent substrate 1 side) of the phase shift film 2 with respect to light having a wavelength of 193 nm was 39.5%.

  The mask blank of Example 2 having a structure in which the phase shift film 2, the light-shielding film 3, and the hard mask film 4 composed of the SiN lower layer 21 and the SiN upper layer 22 are laminated on the translucent substrate 1 by the above procedure. 100 was produced. Note that the mask blank 100 of Example 2 has a back-surface reflectance (a reflectance on the translucent substrate 1 side) with respect to light having a wavelength of 193 nm when the phase shift film 2 and the light-shielding film 3 are laminated on the translucent substrate 1. ) Was 37.6%. The optical density (OD) of light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was measured and found to be 3.0 or more.

[Manufacture of phase shift mask]
Next, using the mask blank 100 of Example 2, the phase shift mask 200 of Example 2 was produced in the same procedure as in Example 1. The ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 when dry etching using SF ₆ + He was performed on the phase shift film 2 was 1.09.

In the fabricated halftone phase shift mask 200 of Example 2, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light shielding pattern 3b is not laminated so that the integrated dose is 40 kJ / cm ^2. Irradiation treatment was performed. The CD change amount of the phase shift pattern 2a before and after the irradiation treatment was 1.8 nm. This CD change amount is improved as compared with the CD change amount (3.2 nm) generated before and after the same irradiation treatment with respect to the phase shift pattern having a single layer structure of Si ₃ N ₄ .

Furthermore, when the ArF excimer laser light irradiation treatment is performed and the phase shift mask 200 is exposed and transferred to a resist film on a semiconductor device with an exposure light having a wavelength of 193 nm using an AIMS 193 (manufactured by Carl Zeiss). The exposure transfer image was simulated at. When the exposure transfer image obtained by this simulation was verified, the design specifications were sufficiently satisfied. From the above, the phase shift mask 200 manufactured from the mask blank of Example 2 is set in an exposure apparatus and subjected to exposure transfer with exposure light of an ArF excimer laser until the integrated dose reaches 40 kJ / cm ^2. However, it can be said that exposure transfer can be performed with high accuracy to the resist film on the semiconductor device.

On the other hand, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light shielding pattern 3b is laminated in the halftone phase shift mask 200 of the second embodiment so that the integrated irradiation amount is 40 kJ / cm ^2. Irradiation treatment was performed. When the secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the region subjected to the irradiation treatment, the chromium content of the phase shift pattern 2a was very small. From the above, when the phase shift mask 200 manufactured from the mask blank 100 of Example 2 is irradiated with the ArF excimer laser exposure light on the phase shift pattern 2a in which the light shielding pattern 3b is laminated, It can be said that the chromium in the light shielding pattern 3b can be sufficiently suppressed from moving into the phase shift pattern 2a.

(Example 3)
[Manufacture of mask blanks]
The mask blank 100 of Example 3 was manufactured in the same procedure as Example 1 except for the phase shift film 2. In the phase shift film 2 of Example 3, the material and film thickness for forming the lower layer 21 are changed, and the film thickness of the upper layer 22 is further changed. Specifically, the translucent substrate 1 is installed in a single wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) is used as a sputtering gas. By sputtering (RF sputtering), the lower layer 21 (SiN film Si: N = 64 atomic%: 36 atomic%) of the phase shift film 2 made of silicon and nitrogen is in contact with the surface of the light-transmitting substrate 1 with a thickness of 10 nm. Formed. Subsequently, a phase shift composed of silicon and nitrogen is formed on the lower layer 21 by reactive sputtering (RF sputtering) using a silicon (Si) target and a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas. The upper layer 22 of the film 2 (SiN film Si: N = 43 atomic%: 57 atomic%) was formed with a thickness of 58 nm. By the above procedure, the phase shift film 2 in which the lower layer 21 and the upper layer 22 were laminated in contact with the surface of the translucent substrate 1 was formed with a thickness of 68 nm. In the phase shift film 2, the thickness of the upper layer 22 is 5.8 times the thickness of the lower layer 21.

  In addition, the phase shift film 2 of Example 3 was also subjected to heat treatment under the same processing conditions as in Example 1. Using a phase shift amount measuring apparatus (MPM193 manufactured by Lasertec Corporation), the transmittance and phase difference of the phase shift film 2 with respect to light having a wavelength of 193 nm were measured. The transmittance was 6.1% and the phase difference was 177.0. Degree. Further, when this phase shift film 2 was analyzed by STEM and EDX, it was confirmed that an oxide layer was formed in a surface layer portion having a thickness of about 2 nm from the surface of the upper layer 22. Further, when the optical characteristics of the lower layer 21 and the upper layer 22 of the phase shift film 2 were measured, the lower layer 21 had a refractive index n of 1.62, an extinction coefficient k of 2.18, and the upper layer 22 had a refractive index. n was 2.63 and the extinction coefficient k was 0.37. The back surface reflectivity (reflectance on the translucent substrate 1 side) of the phase shift film 2 with respect to light having a wavelength of 193 nm was 37.8%.

  The mask blank of Example 3 having a structure in which the phase shift film 2, the light-shielding film 3, and the hard mask film 4 composed of the SiN lower layer 21 and the SiN upper layer 22 are laminated on the translucent substrate 1 by the above procedure. 100 was produced. In addition, the mask blank 100 of this Example 3 has a back-surface reflectance (a reflectance on the translucent substrate 1 side) with respect to light having a wavelength of 193 nm in a state where the phase shift film 2 and the light shielding film 3 are laminated on the translucent substrate 1. ) Was 35.8%. The optical density (OD) of light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was measured and found to be 3.0 or more.

[Manufacture of phase shift mask]
Next, using the mask blank 100 of Example 3, the phase shift mask 200 of Example 3 was produced in the same procedure as in Example 1. The ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 when dry etching using SF ₆ + He was performed on the phase shift film 2 was 1.04.

In the fabricated halftone phase shift mask 200 of Example 3, the region of the phase shift pattern 2a where the light shielding pattern 3b is not laminated is intermittently irradiated with ArF excimer laser light so that the integrated dose is 40 kJ / cm ^2. Irradiation treatment was performed. The CD change amount of the phase shift pattern 2a before and after this irradiation treatment was 2.0 nm. This CD change amount is improved as compared with the CD change amount (3.2 nm) generated before and after the same irradiation treatment with respect to the phase shift pattern having a single layer structure of Si ₃ N ₄ .

Furthermore, when the ArF excimer laser light irradiation treatment is performed and the phase shift mask 200 is exposed and transferred to a resist film on a semiconductor device with an exposure light having a wavelength of 193 nm using an AIMS 193 (manufactured by Carl Zeiss). The exposure transfer image was simulated at. When the exposure transfer image obtained by this simulation was verified, the design specifications were sufficiently satisfied. In view of the above, the phase shift mask 200 manufactured from the mask blank of Example 3 is set in an exposure apparatus and subjected to exposure transfer with exposure light of an ArF excimer laser until the integrated dose reaches 40 kJ / cm ^2. However, it can be said that exposure transfer can be performed with high accuracy to the resist film on the semiconductor device.

On the other hand, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light shielding pattern 3b is laminated in the halftone phase shift mask 200 of Example 3 so that the integrated irradiation amount becomes 40 kJ / cm ^2. Irradiation treatment was performed. When the secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the region subjected to the irradiation treatment, the chromium content of the phase shift pattern 2a was very small. From the above, when the phase shift mask 200 manufactured from the mask blank 100 of Example 3 is irradiated with the ArF excimer laser exposure light on the phase shift pattern 2a on which the light shielding pattern 3b is laminated, It can be said that the chromium in the light shielding pattern 3b can be sufficiently suppressed from moving into the phase shift pattern 2a.

Example 4
[Manufacture of mask blanks]
The mask blank 100 of Example 4 was manufactured in the same procedure as in Example 1 except for the phase shift film 2. In the phase shift film 2 of Example 4, the material and film thickness for forming the lower layer 21 are changed, and the film thickness of the upper layer 22 is further changed. Specifically, the translucent substrate 1 is installed in a single wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) is used as a sputtering gas. By sputtering (RF sputtering), a lower layer 21 (SiN film Si: N = 60 atomic%: 40 atomic%) of the phase shift film 2 made of silicon and nitrogen is in contact with the surface of the light-transmitting substrate 1 with a thickness of 11 nm. Formed. Subsequently, a phase shift composed of silicon and nitrogen is formed on the lower layer 21 by reactive sputtering (RF sputtering) using a silicon (Si) target and a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas. The upper layer 22 of the film 2 (SiN film Si: N = 43 atomic%: 57 atomic%) was formed to a thickness of 56 nm. By the above procedure, the phase shift film 2 in which the lower layer 21 and the upper layer 22 were laminated in contact with the surface of the translucent substrate 1 was formed with a thickness of 67 nm. In the phase shift film 2, the thickness of the upper layer 22 is 5.1 times the thickness of the lower layer 21.

  In addition, the phase shift film 2 of Example 4 was also subjected to heat treatment under the same processing conditions as in Example 1. Using a phase shift amount measuring apparatus (MPM193 manufactured by Lasertec Corporation), the transmittance and phase difference of the phase shift film 2 with respect to light having a wavelength of 193 nm were measured. The transmittance was 6.1% and the phase difference was 177.0. Degree. Further, when this phase shift film 2 was analyzed by STEM and EDX, it was confirmed that an oxide layer was formed in a surface layer portion having a thickness of about 2 nm from the surface of the upper layer 22. Further, when the optical characteristics of the lower layer 21 and the upper layer 22 of the phase shift film 2 were measured, the lower layer 21 had a refractive index n of 1.76 and an extinction coefficient k of 2.00, and the upper layer 22 had a refractive index. n was 2.63 and the extinction coefficient k was 0.37. The back surface reflectivity (reflectance on the translucent substrate 1 side) of the phase shift film 2 with respect to light having a wavelength of 193 nm was 35.4%.

  According to the above procedure, the mask blank of Example 4 having a structure in which the phase shift film 2, the light shielding film 3, and the hard mask film 4 composed of the SiN lower layer 21 and the SiN upper layer 22 are laminated on the translucent substrate 1. 100 was produced. In addition, the mask blank 100 of this Example 4 has a back surface reflectance (a reflectance on the side of the translucent substrate 1) with respect to light having a wavelength of 193 nm in a state where the phase shift film 2 and the light shielding film 3 are laminated on the translucent substrate 1. ) Was 33.3%. The optical density (OD) of light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was measured and found to be 3.0 or more.

[Manufacture of phase shift mask]
Next, using the mask blank 100 of Example 4, the phase shift mask 200 of Example 4 was produced in the same procedure as in Example 1. In addition, the ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 when dry etching using SF ₆ + He was performed on the phase shift film 2 was 1.00.

In the fabricated halftone phase shift mask 200 of Example 4, the region of the phase shift pattern 2a where the light shielding pattern 3b is not stacked is intermittently irradiated with ArF excimer laser light so that the integrated dose is 40 kJ / cm ^2. Irradiation treatment was performed. The amount of CD change in the phase shift pattern 2a before and after this irradiation treatment was 2.4 nm. This CD change amount is improved as compared with the CD change amount (3.2 nm) generated before and after the same irradiation treatment with respect to the phase shift pattern having a single layer structure of Si ₃ N ₄ .

Furthermore, when the ArF excimer laser light irradiation treatment is performed and the phase shift mask 200 is exposed and transferred to a resist film on a semiconductor device with an exposure light having a wavelength of 193 nm using an AIMS 193 (manufactured by Carl Zeiss). The exposure transfer image was simulated at. When the exposure transfer image obtained by this simulation was verified, the design specifications were sufficiently satisfied. In view of the above, the phase shift mask 200 manufactured from the mask blank of Example 4 is set in an exposure apparatus and subjected to exposure transfer with exposure light of an ArF excimer laser until the integrated dose reaches 40 kJ / cm ^2. However, it can be said that exposure transfer can be performed with high accuracy to the resist film on the semiconductor device.

On the other hand, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light-shielding pattern 3b is laminated in the halftone phase shift mask 200 of Example 4 so that the integrated irradiation amount becomes 40 kJ / cm ^2. Irradiation treatment was performed. When the secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the region subjected to the irradiation treatment, the chromium content of the phase shift pattern 2a was very small. From the above, when the phase shift mask 200 manufactured from the mask blank 100 of Example 4 is irradiated with the ArF excimer laser exposure light on the phase shift pattern 2a on which the light shielding pattern 3b is laminated, It can be said that the chromium in the light shielding pattern 3b can be sufficiently suppressed from moving into the phase shift pattern 2a.

(Example 5)
[Manufacture of mask blanks]
The mask blank 100 of Example 5 was manufactured in the same procedure as Example 1 except for the light shielding film 3 and the hard mask film 4. The light shielding film 3 of Example 5 has a two-layer structure of a lower layer and an upper layer, and a molybdenum silicide material is used as a material for forming the lower layer and the upper layer. Specifically, the translucent substrate 1 on which the phase shift film 2 is formed is installed in a single wafer DC sputtering apparatus, and a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 13 atomic%). : 87 atomic%), and in contact with the surface of the upper layer 22 of the phase shift film 2 by reactive sputtering (DC sputtering) using a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas. And the lower layer (MoSiN film Mo: Si: N = 8 atomic%: 62 atomic%: 30 atomic%) of the light shielding film 3 made of nitrogen was formed with a thickness of 27 nm. Subsequently, using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 13 atomic%: 87 atomic%), a mixed gas of argon (Ar), oxygen (O ₂ ) and nitrogen (N ₂ ). The upper layer of the light-shielding film 3 made of molybdenum, silicon, nitrogen and oxygen (MoSiON film Mo: Si: O: N = 6) in contact with the surface of the lower layer of the light-shielding film 3 by reactive sputtering using a sputtering gas as a sputtering gas (DC sputtering). Atomic%: 54 atomic%: 3 atomic%: 37 atomic%) was formed with a thickness of 13 nm. By the above procedure, the light-shielding film 3 in which the lower layer and the upper layer were laminated in contact with the surface of the phase shift film 2 was formed with a thickness of 40 nm.

  The optical density (OD) of light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was measured and found to be 3.0 or more. Further, another light-transmitting substrate 1 was prepared, and only the lower layer of the light-shielding film 3 was formed under the same film-forming conditions, and the optical characteristics of the lower layer of the light-shielding film 3 were measured. The refractive index n was 2.23. The extinction coefficient k was 2.07. Similarly, when another light-transmitting substrate 1 is prepared, only the upper layer of the light shielding film 3 is formed under the same film formation conditions, and the optical characteristics of the upper layer of the light shielding film 3 are measured, the refractive index n is 2. 33 and the extinction coefficient k was 0.94.

The hard mask film 4 of Example 5 uses a chromium-based material. Specifically, the translucent substrate 1 on which the phase shift film 2 and the light-shielding film 3 are formed is installed in a single-wafer DC sputtering apparatus, a chromium (Cr) target is used, and argon (Ar) and nitrogen (N ₂ ) The hard mask film 4 (CrN film Cr: N = 75 atomic%: 25) made of chromium and nitrogen in contact with the surface of the upper layer of the light-shielding film 3 by reactive sputtering (DC sputtering) using a mixed gas of ₂ ) as a sputtering gas. Atom%) was formed with a thickness of 5 nm.

  By the above procedure, the phase shift film 2 composed of the SiN lower layer 21 and the SiN upper layer 22, the light shielding film 3 composed of the MoSiN lower layer and the MoSiON upper layer, and the CrN hard mask film 4 are formed on the translucent substrate 1. The mask blank 100 of Example 5 provided with the structure which laminated | stacked was manufactured. In addition, the mask blank 100 of this Example 5 has a back surface reflectance (a reflectance on the side of the translucent substrate 1) with respect to light having a wavelength of 193 nm in a state where the phase shift film 2 and the light shielding film 3 are laminated on the translucent substrate 1. ) Was 43.1%.

[Manufacture of phase shift mask]
Next, using the mask blank 100 of Example 5, fluorine gas (SF ₆ + He) is applied as an etching gas used for dry etching of the light shielding film 3, and chlorine is used as an etching gas used for dry etching of the hard mask film 4. A phase shift mask 200 of Example 5 was produced in the same procedure as in Example 1 except that a mixed gas of oxygen and oxygen (Cl ₂ + O ₂ ) was applied.

In the fabricated halftone phase shift mask 200 of Example 5, the region of the phase shift pattern 2a where the light shielding pattern 3b is not laminated is intermittently irradiated with ArF excimer laser light so that the integrated dose is 40 kJ / cm ^2. Irradiation treatment was performed. The CD change amount of the phase shift pattern 2a before and after this irradiation treatment was 1.5 nm. This CD change amount is improved as compared with the CD change amount (3.2 nm) generated before and after the same irradiation treatment with respect to the phase shift pattern having a single layer structure of Si ₃ N ₄ .

Furthermore, when the ArF excimer laser light irradiation treatment is performed and the phase shift mask 200 is exposed and transferred to a resist film on a semiconductor device with an exposure light having a wavelength of 193 nm using an AIMS 193 (manufactured by Carl Zeiss). The exposure transfer image was simulated at. When the exposure transfer image obtained by this simulation was verified, the design specifications were sufficiently satisfied. From the above, the phase shift mask 200 manufactured from the mask blank 100 of Example 5 is set in an exposure apparatus until exposure transfer with exposure light of an ArF excimer laser reaches an integrated dose of 40 kJ / cm ^2. Even if it does, it can be said that exposure transfer can be performed with high precision to the resist film on the semiconductor device.

On the other hand, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light-shielding pattern 3b is laminated in the halftone phase shift mask 200 of Example 5 so that the integrated irradiation amount becomes 40 kJ / cm ^2. Irradiation treatment was performed. When secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the irradiated region, the molybdenum content of the phase shift pattern 2a was very small. From the above, when the phase shift mask 200 manufactured from the mask blank 100 of Example 5 is irradiated with the ArF excimer laser exposure light on the phase shift pattern 2a on which the light shielding pattern 3b is laminated, It can be said that the molybdenum in the light shielding pattern 3b can be sufficiently suppressed from moving into the phase shift pattern 2a.

(Comparative Example 1)
[Manufacture of mask blanks]
The mask blank of Comparative Example 1 was manufactured in the same procedure as in Example 1 except for the phase shift film 2. In the phase shift film 2 of Comparative Example 1, the material and film thickness for forming the lower layer 21 are changed, and the film thickness of the upper layer 22 is further changed. Specifically, the translucent substrate 1 is installed in a single wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) is used as a sputtering gas. By sputtering (RF sputtering), the lower layer 21 (SiN film Si: N = 52 atomic%: 48 atomic%) of the phase shift film 2 made of silicon and nitrogen is in contact with the surface of the light-transmitting substrate 1 with a thickness of 22 nm. Formed. Subsequently, a phase shift composed of silicon and nitrogen is formed on the lower layer 21 by reactive sputtering (RF sputtering) using a silicon (Si) target and a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas. The upper layer 22 of the film 2 (SiN film Si: N = 43 atomic%: 57 atomic%) was formed to a thickness of 42 nm. By the above procedure, the phase shift film 2 in which the lower layer 21 and the upper layer 22 were laminated in contact with the surface of the translucent substrate 1 was formed with a thickness of 64 nm. In the phase shift film 2, the thickness of the upper layer 22 is 1.9 times the thickness of the lower layer 21.

  Also, the heat treatment was performed on the phase shift film 2 of Comparative Example 1 under the same processing conditions as in Example 1. Using a phase shift amount measuring apparatus (MPM193 manufactured by Lasertec Corporation), the transmittance and phase difference of the phase shift film 2 with respect to light having a wavelength of 193 nm were measured. The transmittance was 6.1% and the phase difference was 177.0. Degree. Further, when this phase shift film 2 was analyzed by STEM and EDX, it was confirmed that an oxide layer was formed in a surface layer portion having a thickness of about 2 nm from the surface of the upper layer 22. Further, when the optical characteristics of the lower layer 21 and the upper layer 22 of the phase shift film 2 were measured, the lower layer 21 had a refractive index n of 2.39 and an extinction coefficient k of 1.17, and the upper layer 22 had a refractive index of n was 2.63 and the extinction coefficient k was 0.37. The back surface reflectivity (reflectance on the translucent substrate 1 side) of the phase shift film 2 with respect to light having a wavelength of 193 nm was 19.5%.

  The mask blank of Comparative Example 1 having a structure in which the phase shift film 2, the light-shielding film 3, and the hard mask film 4 composed of the SiN lower layer 21 and the SiN upper layer 22 are laminated on the translucent substrate 1 by the above procedure. Manufactured. In addition, the mask blank of this comparative example 1 has a back surface reflectance for the light having a wavelength of 193 nm in the state where the phase shift film 2 and the light shielding film 3 are laminated on the light transmissive substrate 1 (reflectance on the light transmissive substrate 1 side). Was 17.8%. The optical density (OD) of light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was measured and found to be 3.0 or more.

[Manufacture of phase shift mask]
Next, using the mask blank of Comparative Example 1, a phase shift mask of Comparative Example 1 was produced in the same procedure as in Example 1. The ratio of the etching rate of the lower layer 21 to the etching rate of the upper layer 22 when the dry etching using SF ₆ + He was performed on the phase shift film 2 was 0.96.

In the fabricated halftone phase shift mask of Comparative Example 1, the region of the phase shift pattern 2a where the light shielding pattern 3b is not laminated is intermittently irradiated with ArF excimer laser light so that the integrated dose is 40 kJ / cm ^2. Irradiation treatment was performed. The amount of CD change in the phase shift pattern 2a before and after this irradiation treatment was 3.2 nm. This CD change amount is not different from the CD change amount (3.2 nm) generated before and after the same irradiation process with respect to the phase shift pattern having a single layer structure of Si ₃ N ₄ , and the CD change amount is improved. Is not done.

Furthermore, when the ArF excimer laser light is irradiated and transferred to the resist film on the semiconductor device with the exposure light having a wavelength of 193 nm using AIMS 193 (manufactured by Carl Zeiss) for the phase shift mask. An exposure transfer image was simulated. When the exposure transfer image obtained by this simulation was verified, the design specifications could not be satisfied. From the above, when the phase shift mask manufactured from the mask blank of Comparative Example 1 is set in an exposure apparatus and exposure transfer using exposure light of an ArF excimer laser is performed until the integrated dose reaches 40 kJ / cm ^2. It can be said that exposure transfer cannot be performed with high accuracy on the resist film on the semiconductor device.

On the other hand, the ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light shielding pattern 3b in the halftone phase shift mask of Comparative Example 1 is laminated so that the integrated irradiation amount becomes 40 kJ / cm ^2. Irradiation treatment was performed. When secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the region subjected to the irradiation treatment, the chromium content of the phase shift pattern 2a was compared with the result in each example. Has increased significantly. From this result, in the phase shift mask manufactured from the mask blank of Comparative Example 1, when the exposure light of the ArF excimer laser is irradiated to the phase shift pattern 2a on which the light shielding pattern 3b is laminated, the light shielding pattern 3b. It can be said that the inside chrome cannot be suppressed from moving into the phase shift pattern 2a.

(Comparative Example 2)
[Manufacture of mask blanks]
The mask blank of Comparative Example 2 was manufactured in the same procedure as in Example 1 except for the phase shift film 2 and the light shielding film 3. The phase shift film 2 of Comparative Example 2 is changed to a single layer structure. Specifically, the translucent substrate 1 is installed in a single wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas of argon (Ar) and nitrogen (N ₂ ) is used as a sputtering gas. A phase shift film 2 (SiN film Si: N = 43 atomic%: 57 atomic%) made of silicon and nitrogen was formed in a thickness of 60 nm in contact with the surface of the transparent substrate 1 by sputtering (RF sputtering).

  When the optical characteristics of the phase shift film 2 were measured, the refractive index n was 2.63 and the extinction coefficient k was 0.37. However, when the phase shift film 2 having a single layer structure was adjusted so that the phase difference was 177.0 degrees (deg), the transmittance was 18.1%. In order that the optical density (OD) with respect to light having a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light-shielding film 3 is 3.0 or more, the light-shielding film 3 has the same composition and optical characteristics. The thickness was changed to 57 nm. The back surface reflectance (reflectance on the translucent substrate 1 side) of the phase shift film 2 with respect to light having a wavelength of 193 nm was 16.6%.

  The mask blank of the comparative example 2 provided with the structure which laminated | stacked the phase shift film 2, the light shielding film 3, and the hard mask film | membrane 4 which consist of a single layer structure of SiN on the translucent board | substrate 1 with the above procedure was manufactured. In addition, the mask blank of this comparative example 2 is a back surface reflectance with respect to the light of wavelength 193 nm in the state which laminated | stacked the phase shift film 2 and the light shielding film 3 on the translucent board | substrate 1 (reflectance of the translucent board | substrate 1 side). Was 13.7%.

[Manufacture of phase shift mask]
Next, using the mask blank of Comparative Example 2, a phase shift mask of Comparative Example 2 was produced in the same procedure as in Example 1.

The ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light-shielding pattern 3b is not laminated in the halftone phase shift mask of Comparative Example 2 manufactured so that the integrated irradiation amount is 40 kJ / cm ^2. Irradiation treatment was performed. The amount of CD change in the phase shift pattern 2a before and after this irradiation treatment was 3.2 nm.

Furthermore, when the ArF excimer laser light is irradiated and transferred to the resist film on the semiconductor device with the exposure light having a wavelength of 193 nm using AIMS 193 (manufactured by Carl Zeiss) for the phase shift mask. An exposure transfer image was simulated. When the exposure transfer image obtained by this simulation was verified, the design specifications could not be satisfied. From the above, when the phase shift mask manufactured from the mask blank of Comparative Example 2 is set in an exposure apparatus and exposure transfer using exposure light of an ArF excimer laser is performed until the integrated dose reaches 40 kJ / cm ^2. It can be said that exposure transfer cannot be performed with high accuracy on the resist film on the semiconductor device.

On the other hand, ArF excimer laser light is intermittently irradiated to the region of the phase shift pattern 2a in which the light shielding pattern 3b in the halftone phase shift mask of Comparative Example 2 is laminated so that the integrated irradiation amount becomes 40 kJ / cm ^2. Irradiation treatment was performed. When secondary ion mass spectrometry (SIMS) was performed on the phase shift pattern 2a in the region subjected to the irradiation treatment, the chromium content of the phase shift pattern 2a was compared with the result in each example. Has increased significantly. From this result, when the phase shift mask 200 manufactured from the mask blank of Comparative Example 2 is irradiated with the ArF excimer laser exposure light on the phase shift pattern 2a on which the light shielding pattern 3b is laminated, the light shielding pattern It can be said that the chrome in 3b cannot be suppressed from moving into the phase shift pattern 2a.

DESCRIPTION OF SYMBOLS 1 Translucent substrate 2 Phase shift film 21 Lower layer 22 Upper layer 2a Phase shift pattern 3 Light shielding film 3a, 3b Light shielding pattern 4 Hard mask film 4a Hard mask pattern 5a First resist pattern 6b Second resist pattern 100 Mask blank 200 Phase Shift mask

Claims (19)

A mask blank provided with a phase shift film on a translucent substrate,
The phase shift film has an ArF excimer laser transmittance of 2% or more for exposure light,
The reflectance with respect to the exposure light incident from the light-transmissive substrate side of the phase shift film in a state where only the phase shift film exists on the light-transmissive substrate is 35% or more and 45% or less,
The phase shift film includes a structure in which a lower layer and an upper layer are stacked from the translucent substrate side,
The lower layer is formed of a material containing silicon, or a material containing one or more elements selected from non-metal elements and metalloid elements other than oxygen in a material made of silicon,
The upper layer is formed of a material containing silicon and nitrogen, or a material containing one or more elements selected from non-metal elements and metalloid elements other than oxygen in a material consisting of silicon and nitrogen, except for the surface layer portion. A mask blank characterized by   The mask blank according to claim 1, wherein the lower layer has a nitrogen content of 40 atomic% or less.   The mask blank according to claim 1, wherein the upper layer has a nitrogen content larger than 50 atomic%.   4. The mask blank according to claim 1, wherein a thickness of the upper layer is five times or more a thickness of the lower layer. 5.   The mask blank according to any one of claims 1 to 4, wherein the lower layer has a thickness of less than 12 nm. The lower layer is formed of a material comprising silicon and nitrogen, or a material comprising one or more elements selected from nonmetallic elements and metalloid elements other than oxygen in a material comprising silicon and nitrogen. The mask blank according to any one of claims 1 to 5.   The mask blank according to claim 1, wherein the lower layer is formed in contact with a surface of the translucent substrate.   The mask blank according to claim 1, further comprising a light shielding film on the phase shift film.   The mask blank according to claim 8, wherein a reflectance of the phase shift film with respect to the exposure light incident from the light transmitting substrate side in a state where the light shielding film is laminated is 30% or more. A phase shift mask including a phase shift film in which a transfer pattern is formed on a translucent substrate,
The phase shift film has an ArF excimer laser transmittance of 2% or more for exposure light,
The reflectance with respect to the exposure light incident from the light-transmissive substrate side of the phase shift film in a state where only the phase shift film exists on the light-transmissive substrate is 35% or more and 45% or less,
The phase shift film includes a structure in which a lower layer and an upper layer are stacked from the translucent substrate side,
The lower layer is formed of a material containing silicon, or a material containing one or more elements selected from non-metal elements and metalloid elements other than oxygen in a material made of silicon,
The upper layer is formed of a material containing silicon and nitrogen, or a material containing one or more elements selected from non-metal elements and metalloid elements other than oxygen in a material consisting of silicon and nitrogen, except for the surface layer portion. A phase shift mask characterized by comprising:   The phase shift mask according to claim 10, wherein the lower layer has a nitrogen content of 40 atomic% or less.   The phase shift mask according to claim 10 or 11, wherein the upper layer has a nitrogen content larger than 50 atomic%.   13. The phase shift mask according to claim 10, wherein a thickness of the upper layer is five times or more a thickness of the lower layer.   The phase shift mask according to claim 10, wherein the lower layer has a thickness of less than 12 nm.   The lower layer is formed of a material comprising silicon and nitrogen, or a material comprising one or more elements selected from nonmetallic elements and metalloid elements other than oxygen in a material comprising silicon and nitrogen. The phase shift mask according to claim 10.   The phase shift mask according to claim 10, wherein the lower layer is formed in contact with the surface of the translucent substrate.   The phase shift mask according to claim 10, further comprising a light shielding film having a light shielding pattern formed on the phase shift film.   18. The phase shift according to claim 17, wherein a reflectance with respect to the exposure light incident from the translucent substrate side in a region of the phase shift film in a state where the light shielding film is laminated is 30% or more. mask.   A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to claim 10.

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