JP2014232191A - Mask blank, phase shift mask, method for producing them, and method for producing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask blank capable of suppressing occurrence of a transfer failure even when a translucent substrate has minute concave defective parts.SOLUTION: Provided is a mask blank comprising a phase shift film disposed on a main surface of a translucent substrate. The translucent substrate has concave defective parts on the main surface on which the phase shift film is formed. The phase shift film includes a structure where, from a side of the translucent substrate, a high-transmission layer and a low-transmission layer having lower light transmittance than the former are laminated in this order. Inner regions of the high transmission layer formed on the concave defective parts have low-density regions, where density in the low-density region is relatively lower than that in an inner region of the high-transmission layer formed on the main surface which is free from the concave defective parts.

Description

  The present invention relates to a mask blank, a phase shift mask obtained by processing the mask blank, a mask blank manufacturing method, a phase shift mask manufacturing method, and a semiconductor device manufacturing method.

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

  The phase shift film has a predetermined transmittance with respect to the exposure light used in the transfer process, and the exposure light transmitted through the phase shift film and the exposure light transmitted through the atmosphere by the same distance as the thickness of the phase shift film. Are films having optical characteristics such that a predetermined phase difference is obtained. For example, silicon nitride (SiN) is used as such a phase shift film (see Patent Document 1 below). As another example of the phase shift film, a material using a material containing a transition metal such as MoSiON, silicon, oxygen, and nitrogen is also known (see Patent Document 2 below).

  Here, in the manufacture of a general mask blank, a thin film such as a phase shift film is formed on the main surface of a translucent substrate by a single wafer sputtering apparatus. In particular, in mask blanks and phase shift masks having a phase shift film on a translucent substrate, it is important that the transmittance and the phase shift amount of the phase shift film remain uniform in the translucent substrate plane. is there. For this reason, in the formation of the phase shift film on the main surface of the light-transmitting substrate, the oblique incidence is made so that the sputtering surface of the sputtering target is inclined and opposed to the main surface of the rotated light-transmitting substrate. Film formation using a rotary sputtering method is performed (see Patent Document 3 below).

Japanese Patent Laid-Open No. 8-220731 JP 2012-58593 A JP 2002-90978 A

  By the way, when manufacturing the above-described mask blank, even if there are minute scratches (defect portions) on the main surface of the translucent substrate, the position of the defect portions does not become a major obstacle to the formation of the transfer pattern. In some cases, it is determined that this translucent substrate can be used, and a mask blank is formed by forming a thin film. This is because when a transfer pattern is formed on a thin film, information on the plane coordinates of the defective portion and the defect type (convex defect or concave defect) on the translucent substrate is attached to the corresponding mask blank and delivered. In addition, the defect portion can be adjusted to a position that does not affect the exposure transfer.

  However, in the formation of the phase shift film to which the oblique incidence rotation sputtering method described above is applied, if a minute concave defect portion exists on the main surface of the translucent substrate, the phase shift film is formed on the concave defect portion. It was found that a low density region having a density lower than that of the surrounding area was partially formed. This is because, in the case of film formation by the oblique incidence rotary sputtering method, sputtered particles scattered from the sputtering target enter from a direction inclined from the vertical direction with respect to the main surface of the translucent substrate, and the cross section of the concave defect portion. Since the shape is often rounded, it is presumed that the invasion angle and speed of the particles reaching the light-transmitting substrate vary.

  Such a low density region is a region having higher transmittance and different optical characteristics than the surrounding region. When manufacturing a phase shift mask from a mask blank having a concave defect portion on such a translucent substrate, by covering the concave defect portion with a large-area phase shift film without using the above-described phase difference, It seems to be a pattern design in which the concave defect does not affect the fine pattern exposure transfer. However, since it is difficult to suppress the transmittance at the concave defect portion to the same level as the transmittance at the portion where the surrounding transfer pattern exists, the transfer target (on the semiconductor substrate) is used by using the completed phase shift mask. When a pattern is exposed and transferred to a resist film, etc., a transfer defect occurs in which the portion is exposed to the transfer object due to the high transmittance of the phase shift film on the concave defect portion. There was a case and it was a problem.

  Accordingly, the present invention provides a mask that does not have a white defect having a higher transmittance than the surroundings even when the translucent substrate has a minute concave defect portion, thereby suppressing the occurrence of transfer defects. It is an object of the present invention to provide a blank and a phase shift mask, and further to provide a method for manufacturing the mask blank, a method for manufacturing the phase shift mask, and a method for manufacturing a semiconductor device.

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

(Configuration 1)
A mask blank in which a phase shift film is provided on a main surface of a translucent substrate,
The translucent substrate has a concave defect portion on the main surface on which the phase shift film is formed,
The phase shift film includes a structure in which a high-transmitting layer and a low-transmitting layer having a lower light transmittance are stacked in this order from the light-transmitting substrate side,
The internal region of the high transmission layer of the portion formed on the concave defect portion has a low density region,
The mask blank, wherein the density in the low density region is relatively lower than the density in the inner region of the high transmission layer in a portion formed on the main surface without the concave defect.
(Configuration 2)
The high transmission layer and the low transmission layer are formed of a material containing silicon and nitrogen,
The mask blank according to Configuration 1, wherein the high transmission layer has a relatively high nitrogen content as compared with the low transmission layer.
(Configuration 3)
The high-permeability layer and the low-permeability layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a nonmetal element, and a rare gas in the material. The mask blank according to Configuration 1 or 2.
(Configuration 4)
The high transmissive layer and the low transmissive layer are made of the same constituent element. The mask blank according to any one of the first to third aspects, wherein:
(Configuration 5)
5. The mask blank according to any one of configurations 1 to 4, wherein the phase shift film has two or more combinations of laminated structures of the high transmission layer and the low transmission layer.
(Configuration 6)
The mask blank according to any one of configurations 1 to 5, wherein the high transmission layer and the low transmission layer are formed of a material made of silicon and nitrogen.
(Configuration 7)
The mask blank according to any one of configurations 1 to 6, wherein the high transmission layer has a film thickness larger than that of the low transmission layer.
(Configuration 8)
The mask blank according to any one of Structures 1 to 7, wherein the phase shift film includes an uppermost layer formed of a material containing silicon and oxygen at a position farthest from the translucent substrate. .
(Configuration 9)
The phase shift film is formed at a position farthest from the light-transmitting substrate, from a material consisting of silicon and oxygen, a material consisting of silicon, nitrogen and oxygen, or a metalloid element, a nonmetallic element, and a rare gas. The mask blank according to any one of configurations 1 to 8, further comprising an uppermost layer formed of any one of materials containing one or more selected elements.
(Configuration 10)
10. The configuration according to claim 8, wherein the phase shift film formed on the concave defect portion remains even after the phase shift film is washed with hot water for 5 minutes or more. Mask blank.

(Configuration 11)
A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to any one of Configurations 1 to 10.

(Configuration 12)
A method for manufacturing a mask blank in which a phase shift film is provided on a main surface of a translucent substrate,
Rotating the translucent substrate with a rotation axis passing through the center of the main surface; and disposing the sputtering surface of the sputtering target obliquely so as to face the main surface having the concave defect portion of the translucent substrate; A step of forming the phase shift film on a main surface having a concave defect portion of the light transmitting substrate by a sputtering method including:
The step of forming the position shift film includes a highly transmissive layer forming step of forming a highly transmissive layer on a main surface having a concave defect in the light transmissive substrate, and a light transmittance higher than that of the highly transmissive layer. Forming a low low transmission layer on the high transmission layer, and a low transmission layer forming step,
In the high transmission layer formed in the high transmission layer forming step, the internal region of the high transmission layer of the portion formed on the concave defect portion has a low density region, and the density in the low density region is The mask blank manufacturing method, wherein the density of the portion formed on the main surface without the concave defect portion is relatively lower than the density in the inner region of the high transmission layer.
(Configuration 13)
The high transmission layer forming step uses the sputtering target made of a material containing silicon, and forms the high transmission layer by reactive sputtering in a sputtering gas containing a nitrogen-based gas and a rare gas,
The low permeable layer forming step uses the sputtering target made of a material containing silicon, and includes a nitrogen-based gas and a rare gas, and has a lower mixing ratio of the nitrogen-based gas than in the highly permeable layer forming step. The method for producing a mask blank according to Configuration 12, wherein the low-permeability layer is formed by reactive sputtering inside.
(Configuration 14)
The high transmission layer forming step uses the sputtering target made of a material containing one or more elements selected from silicon or a metalloid element and a nonmetal element in silicon, and in a sputtering gas containing a nitrogen-based gas and a rare gas. The high transmission layer is formed by reactive sputtering of
The low transmission layer forming step uses the sputtering target made of a material containing one or more elements selected from silicon or a metalloid element and a nonmetal element in silicon, and includes a nitrogen-based gas and a rare gas, and the high transmission layer The method for producing a mask blank according to the structure 12 or 13, wherein the low transmission layer is formed by reactive sputtering in a sputtering gas having a lower mixing ratio of nitrogen-based gas than in the forming step. .
(Configuration 15)
The highly permeable layer forming step is to form the highly permeable layer by reactive sputtering in a sputtering gas composed of nitrogen gas and a rare gas, using the sputtering target composed of silicon.
The low transmission layer forming step uses the sputtering target made of silicon, and reactive sputtering in a sputtering gas made of nitrogen gas and a rare gas and having a lower nitrogen-based gas mixing ratio than in the high transmission layer forming step. The method for manufacturing a mask blank according to any one of Structures 12 to 14, wherein the low transmission layer is formed by:
(Configuration 16)
The high transmission layer forming step is to form the high transmission layer by reactive sputtering in poison mode,
The method for manufacturing a mask blank according to any one of Structures 12 to 15, wherein the low transmission layer forming step forms the low transmission layer by reactive sputtering in a metal mode.
(Configuration 17)
Any one of the constitutions 12 to 16, further comprising an uppermost layer forming step of forming an uppermost layer made of a material containing silicon and oxygen at a position farthest from the translucent substrate of the phase shift film. The manufacturing method of the mask blank of description.
(Configuration 18)
The phase shift film is selected from a material consisting of silicon and oxygen, a material consisting of silicon, nitrogen and oxygen, or a semi-metal element, a non-metal element, and a rare gas at a position farthest from the translucent substrate. A method for manufacturing a mask blank according to any one of Structures 12 to 17, further comprising: an uppermost layer forming step of forming an uppermost layer formed of any one of the materials containing one or more elements.

(Configuration 19)
A method of manufacturing a phase shift mask, comprising: forming a transfer pattern on the phase shift film of a mask blank manufactured by the method of manufacturing a mask blank according to any one of Structures 12 to 18.

(Configuration 20)
A method for manufacturing a semiconductor device, comprising using the phase shift mask according to Configuration 11 and exposing and transferring the transfer pattern of the phase shift mask to a resist film on a substrate.

(Configuration 21)
A semiconductor comprising: a step of exposing and transferring the transfer pattern of the phase shift mask to a resist film on a substrate using the phase shift mask manufactured by the method of manufacturing a phase shift mask according to Configuration 19 Device manufacturing method.

  According to the present invention having the above configuration, the transmittance of the phase shift film is mainly reduced by the configuration in which the low density region on the concave defect is formed in the high transmission layer provided on the translucent substrate side. It can be controlled by a low transmission layer that does not include a density region. For this reason, it becomes possible to improve the in-plane uniformity of the transmittance of the phase shift film on the translucent substrate having a concave defect, thereby suppressing the formation of white defects on the mask blank and the phase shift mask. Therefore, it is possible to prevent the occurrence of transfer failure using the phase shift mask.

It is sectional drawing which shows the structure of the mask blank in one Embodiment of this invention. It is sectional drawing which shows the structure of the mask blank of the modification 1 of this invention. It is a schematic diagram which shows an example of the film-forming apparatus used for the manufacturing method of the mask blank of this invention. In the film-forming apparatus used for the manufacturing method of this invention, it is a schematic diagram which shows the positional relationship of a board | substrate and a sputtering target. It is a schematic diagram for demonstrating the sputtering device used for the manufacturing method of this invention. It is sectional drawing which shows the structure of the phase shift mask of this invention. It is a manufacturing-process figure of the phase shift mask of this invention.

  In the production of a mask blank, when forming a thin film on the main surface of the light-transmitting substrate, the oblique incidence is made so that the sputtering surface of the sputtering target is inclined and opposed to the main surface of the rotated light-transmitting substrate. Film formation using a rotary sputtering method is performed.

  However, a mask blank obtained by applying such a grazing incidence rotary sputtering method to form a thin film of a transition metal silicide material typified by a MoSi material is used for transfer. In the process of manufacturing the mask, it has been found that pinhole defects of a minute size (around 100 nm) may occur on the main surface of the thin film. In addition, even though no defect was detected in the mask defect inspection immediately after the transfer mask was manufactured, the mask defect inspection was performed after the mask cleaning performed after the transfer mask was set in the exposure apparatus and used a predetermined number of times. When it did, it became clear that the pinhole defect of a minute size might generate | occur | produce on the main surface of a thin film similarly. In any case, such a pinhole defect was not detected when a defect inspection was performed on a mask blank formed by forming a thin film.

  The inventors diligently studied the cause of the occurrence of this pinhole defect. As a result, all of the mask blanks in which the pinhole defects as described above are generated are scratches (concave defects) having a minute depth (40 nm or less) on the main surface of the light-transmitting substrate immediately below the pinhole defect portion. ) Existed. Next, the cross-sectional TEM image of the concave defect part was observed with respect to the mask blank manufactured with the translucent board | substrate with a minute concave defect. As a result, it was confirmed that film formation unevenness occurred in the thin film on the concave defect portion.

  As a result of further research on the film formation uneven portion, it was found that the film formation uneven portion has a lower density than other thin film portions. Further, the low density region (low density region) where the film formation unevenness is generated has a shape extending from the translucent substrate side to the surface side of the thin film in a sectional view, and further in a plan view. It has also been confirmed that the recess extends from the vicinity of the outer periphery to the center side.

  The reason why such a low density region is formed is that the direction in which the sputtered particles scattered from the sputtering target incline from the vertical direction with respect to the main surface of the translucent substrate in the case of forming the thin film by the oblique incidence rotary sputtering method. This is presumed to be due to variations in the intrusion angle and speed of the particles reaching the translucent substrate because the shape of the cross section of the concave defect portion is often rounded.

  The problem here is that the low density region in the thin film as described above is a region having a higher transmittance than the surrounding thin film portion. For this reason, even if the thin film on the light-transmitting substrate is made of a material that does not cause a pinhole defect, if this thin film is a phase shift film, while maintaining a predetermined phase shift amount, It is difficult to suppress the transmittance at the concave defect portion to the same level as the transmittance around it. Therefore, a phase shift mask in which a concave defect exists on a translucent substrate has a concave defect even in a pattern design in which the concave defect is covered with a large-area phase shift film that does not use a phase difference. It is difficult to suppress the transmittance at the same level as the transmittance at the portion where the surrounding transfer pattern exists, and there is a risk of white defects.

  Accordingly, each mask blank of the present invention has a configuration in which the phase shift film on the main surface of the translucent substrate is laminated in the order of the high transmission layer and the low transmission layer from the translucent substrate side. Since the high transmittance layer is a layer having a high transmittance from the beginning, even if a partial low density region is formed in the high transmittance layer, the transmittance increases in the entire film thickness direction of the phase shift film due to the low density region. Even if a phase shift mask is manufactured using a mask blank having such a phase shift film, the influence of the low density region on the exposure and transfer of the pattern can be reduced.

  Further, when producing a phase shift mask from a mask blank, it is common to arrange the pattern so that the phase shift film on the concave defect portion of the translucent substrate does not become a region for forming a fine transfer pattern. . For this reason, there is no substantial problem even if the phase shift amount of the phase shift film on the concave defect portion is not in a desired range. Therefore, even if a partial low-density region is formed in the high transmission layer mainly used for adjusting the phase shift amount of the phase shift film, it is unlikely to be an obstacle when manufacturing the phase shift mask.

  The detailed configuration of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same component and it demonstrates.

≪Mask blank≫
FIG. 1 is a cross-sectional view of an essential part of a mask blank 1 showing one configuration example of the present invention. As shown in this figure, the mask blank 1 has a configuration in which a halftone phase shift film (hereinafter referred to as a phase shift film) 11 is provided on the main surface S on one side of the translucent substrate 3. The phase shift film 11 has a laminated structure 10 in which a high transmission layer 5 and a low transmission layer 7 having a light transmittance lower than that of the high transmission layer 5 are laminated in this order from the light transmitting substrate 3 side. The phase shift film 11 may include the uppermost layer 9 at a position farthest from the translucent substrate 3. Such a phase shift film 11 is formed by depositing each layer by the oblique incidence rotation sputtering method described in detail later. The mask blank 1 may have a configuration in which a light shielding film 13, an etching mask film 15, and a resist film 17 are laminated in this order on the phase shift film 11 as necessary. Hereinafter, details of main components of the mask blank 1 will be described.

<Translucent substrate 3>
The translucent substrate 3 has a scratch having a minute depth as a concave defect portion F on the main surface S on the side where the phase shift film 11 is provided. The depth of the concave defect portion F is, for example, 40 nm or less.

Such a translucent substrate 3 is made of a material having good transparency to exposure light used in an exposure process in lithography. If ArF excimer laser light (wavelength: about 193 nm) is used as exposure light, it may be made of a material having transparency to this. As such a material, synthetic quartz glass is used. In addition, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass, etc.), and other various glass substrates may be used. it can. In particular, since the quartz substrate is highly transparent in an ArF excimer laser beam or in a shorter wavelength region, it can be particularly suitably used for the mask blank of the present invention.

  Incidentally, the exposure process in lithography referred to here is an exposure process in lithography using a phase shift mask manufactured using this mask blank 1, and hereinafter, exposure light is exposure light used in this exposure process. Suppose that As this exposure light, ArF excimer laser light (wavelength: 193 nm), KrF excimer laser light (wavelength: 248 nm) and i-line light (wavelength: 365 nm) can be applied. From the viewpoint of making it easier, it is desirable to apply ArF excimer laser light to the exposure light. For this reason, an embodiment in the case where ArF excimer laser light is applied to exposure light will be described below.

<High transmission layer 5, low transmission layer 7>
Of the high transmission layer 5 and the low transmission layer 7 constituting the phase shift film 11, the high transmission layer 5 provided on the translucent substrate 3 side is mainly used for adjusting the phase shift amount in the phase shift film 11. Is a layer. In the highly transmissive layer 5, the internal region of the portion formed on the concave defect portion F of the translucent substrate 3 has a low density region D. The low density region D in the high transmission layer 5 is relatively lower than the density in the inner region of the high transmission layer 5 in the portion formed on the main surface S without the concave defect portion F in the translucent substrate 3.

  The low transmission layer 7 is a layer provided on the main surface S side of the translucent substrate 3 through the high transmission layer 5, and has a lower transmittance than the high transmission layer 5. Such a low transmission layer 7 is a layer mainly used for adjusting the transmittance in the phase shift film 11. Further, it is assumed that the low transmission layer 7 does not reach the low density region D formed on the concave defect portion F.

  The high transmission layer 5 and the low transmission layer 7 as described above are formed of a material containing silicon and nitrogen, and the high transmission layer 5 has a relatively high nitrogen content as compared with the low transmission layer 7. Such a high transmission layer 5 and a low transmission layer 7 are formed of a material (1) made of silicon and nitrogen, or are made of a metalloid element, a nonmetallic element, and a rare gas with respect to the material (1). It may be formed of a material (2) containing one or more selected elements.

  The metalloid element contained in the high-permeability layer 5 and the low-permeability layer 7 may be any metalloid element in addition to silicon, among which one or more elements selected from boron, germanium, antimony and tellurium It is. These elements are elements contained in the high transmission layer 5 and the low transmission layer 7 due to the film forming process of the phase shift film 11 by the sputtering method described below, and the conductivity of the sputtering target using silicon. It is an element introduced in order to enhance the properties.

  The nonmetallic element contained in the high transmission layer 5 and the low transmission layer 7 may be any nonmetallic element in addition to nitrogen. In particular, it is preferable that the high transmission layer 5 and the low transmission layer 7 contain one or more elements selected from carbon, fluorine and hydrogen. On the other hand, the high-permeability layer 5 and the low-permeability layer 7 preferably have an oxygen content of 10 atomic percent or less, more preferably have an oxygen content of 5 atomic percent or less, and actively contain oxygen. More preferably, for example, the result of composition analysis by RBS, XPS or the like is not more than the lower limit of detection. Thus, by suppressing the oxygen content in the high-permeability layer 5 and the low-permeability layer 7 that are silicon-based material films, the value of the extinction coefficient k can be kept to a certain extent, and the entire phase shift film 11 can be maintained. The thickness can be suppressed.

Further, when the translucent substrate 3 is formed of a material mainly composed of SiO ₂ such as synthetic quartz glass, the oxygen content in the high transmissive layer 5 provided in contact with the translucent substrate 3 is suppressed. Thus, a composition difference between the translucent substrate 3 and the highly transmissive layer 5 can be ensured. Thereby, it is possible to increase the etching selectivity between the phase shift film 11 and the translucent substrate 3 in the etching for forming the phase shift mask by patterning the phase shift film 11.

  The rare gas contained in the high transmission layer 5 and the low transmission layer 7 is contained in the high transmission layer 5 and the low transmission layer 7 due to the film forming process of the phase shift film 11 by the sputtering method described below. It is an element. The rare gas is an element that can increase the deposition rate and improve the productivity by being present in the deposition chamber when the phase shift film 11 is deposited by reactive sputtering. In film formation by reactive sputtering, this rare gas is turned into plasma and the target constituent element pops out from the target by colliding with the target, and the thin film is laminated on the translucent substrate while taking in the reactive gas in the middle. It is formed. The rare gas in the film formation chamber is slightly taken in until the target constituent element jumps out of the target and adheres to the translucent substrate. Preferred examples of the rare gas required for the reactive sputtering include argon, krypton, and xenon. Moreover, in order to relieve the stress of the phase shift film 11 including the high transmission layer 5 and the low transmission layer 7 to be formed, helium and neon having a small atomic weight can be actively incorporated into the thin film.

  It is preferable that the high permeable layer 5 and the low permeable layer 7 as described above have a structure in which they are directly in contact with each other without using another film. Moreover, it is preferable that the mask blank 1 of the present invention has a film structure in which neither the high-transmitting layer 5 nor the low-transmitting layer 7 is in contact with a film made of a material containing a metal element. With such a configuration, when heat treatment or ArF exposure light irradiation is performed in a state where the film containing the metal element is in contact with the film containing silicon, the metal element contains the silicon in the film containing silicon. The composition of the high transmission layer 5 and the low transmission layer 7 can be prevented from changing over time.

  Further, the high transmission layer 5 and the low transmission layer 7 are preferably made of the same constituent elements. When either the high transmissive layer 5 or the low transmissive layer 7 contains different constituent elements, and heat treatment or irradiation with ArF exposure light is performed in a state where these are in contact with each other, the different constituent elements are , There is a risk of moving and diffusing to the layer not containing the constituent elements. And there exists a possibility that the optical characteristic of the high transmissive layer 5 and the low transmissive layer 7 may change a lot from the beginning of film-forming. However, such a change can be suppressed by configuring the high transmission layer 5 and the low transmission layer 7 with the same constituent elements. In particular, when the different constituent element is a metalloid element, the high transmissive layer 5 and the low transmissive layer 7 must be formed using different targets, but this is not necessary.

  Of the high transmission layer 5 and the low transmission layer 7, the low transmission layer 7 may contain a transition metal for the purpose of adjusting the transmittance of the phase shift film 11. However, since transition metals can cause light resistance to ArF exposure light to decrease, transition metals can be included in the low-transmitting layer 7 if such a decrease in light resistance is not a problem. it can. The low transmission layer 7 may be made of a material containing a transition metal and not containing silicon. Examples of the transition metal contained in the low transmission layer 7 include materials containing one or more elements selected from titanium (Ti), tantalum (Ta), aluminum (Al), zirconium (Zr), and chromium (Cr). It is done. The low transmission layer 7 containing such a transition metal is in particular one of titanium nitride (TiN), tantalum nitride (TaN), aluminum nitride (AlN), zirconium nitride (ZrN), and chromium nitride (CrN). And more preferred.

  The high transmission layer 5 and the low transmission layer 7 are preferably formed of a material made of silicon and nitrogen. As a result, it is possible to prevent a decrease in light resistance due to the transition metal contained in the high transmission layer 5 and the low transmission layer 7, and the high transmission layer 5 and the low transmission layer 7 can be made of a metal other than a transition metal or silicon. It is possible to prevent a change in optical characteristics due to the movement of the metal or metalloid element between the high transmission layer 5 and the low transmission layer 7 due to the inclusion of the metalloid element. In the case of a nonmetallic element, for example, when oxygen is contained in the high transmission layer 5 and the low transmission layer 7, the transmittance with respect to ArF exposure light is greatly increased. Considering these matters, it is more preferable that the high transmission layer 5 and the low transmission layer 7 are formed of a material made of silicon and nitrogen. The rare gas is an element that is difficult to detect even if a composition analysis such as RBS or XPS is performed on thin films such as the high-permeability layer 5 and the low-permeability layer 7. For this reason, it can be considered that the material containing silicon and nitrogen includes a material containing a rare gas.

  Further, the high transmission layer 5 and the low transmission layer 7 made of each of the materials described above are composed of a single laminated structure 10 including one high transmission layer 5 and one low transmission layer 7 in the phase shift film 11. Two or more sets of the high transmission layer 5 and the low transmission layer 7 may be stacked while maintaining the stacking order. In this case, it is preferable that the thickness of each of the high transmission layer 5 and the low transmission layer 7 is 20 nm or less. The highly transmissive layer 5 and the low transmissive layer 7 are greatly different in required optical characteristics, so that the difference in nitrogen content in the film between them is large. For this reason, there is a large difference in etching rate between the high transmission layer 5 and the low transmission layer 7 when performing dry etching with a fluorine-based gas when patterning them. When the phase shift film 11 has only one set of the laminated structure 10, when forming a transfer pattern on the phase shift film 11 by dry etching with a fluorine-based gas, a step is generated in the cross section of the pattern of the phase shift film 11 after the etching. It becomes easy. Since the phase shift film 11 has a structure having two or more sets of laminated structures 10, the thicknesses of the high transmission layer 5 and the low transmission layer 7 (one layer) have only one set of laminated structures 10. Since the thickness is smaller than that in the case, the step generated in the cross section of the pattern of the phase shift film 11 after etching can be reduced. Further, by limiting the thickness of each layer (one layer) in the high transmission layer 5 and the low transmission layer 7 to 20 nm or less, a step generated in the cross section of the pattern of the phase shift film 11 after etching can be further suppressed. .

  However, the high transmission layer 5 arranged closest to the translucent substrate 3 fills the concave defect portion F of the translucent substrate 3 and covers the low density region D formed on the concave defect portion F. Thickness is preferred.

  In addition, as another example of the laminated structure of the high transmission layer 5 and the low transmission layer 7, the mask blank 1a of the modification 1 shown in FIG. 2 is illustrated. That is, as shown in FIG. 2, the mask blank 1 a of Modification 1 of the present invention is laminated on the low transmission layer 7 side in the laminated structure 10 composed of one high transmission layer 5 and one low transmission layer 7. In addition, a phase shift film 11a provided with one high transmission layer 5 is provided. As described above, two or more laminated structures 10 may be laminated. In this case, the laminated structure 10 is laminated on the low-transmitting layer 7 provided at the position farthest from the translucent substrate 3 to form one layer. The high transmission layer 5 is provided. Thereby, the mask blank 1a has the phase shift film 11a having a configuration in which the single high-transmitting layer 5 is sandwiched between the laminated structure 10 and the uppermost layer 9 described later.

  The high transmission layer 5 and the low transmission layer 7 as described above are configured so that the phase shift film 11 constituted by these satisfies a predetermined phase difference and a predetermined transmittance with respect to exposure light (for example, ArF excimer laser light). Refractive index n and extinction coefficient k are set in predetermined ranges, respectively.

  The high transmission layer 5 is a layer mainly used for adjusting the phase shift amount in the phase shift film 11. Such a high transmission layer 5 has, for example, a refractive index n of 2.5 or more (preferably 2.6 or more) with respect to ArF excimer laser light, and an extinction coefficient k of less than 1.0 (preferably 0.9 or less). More preferably 0.7 or less, and still more preferably 0.4 or less).

  The low transmission layer 7 is a layer mainly used for adjusting the transmittance in the phase shift film 11. Such a low transmission layer 7 has, for example, a refractive index n with respect to ArF excimer laser light of less than 2.5 (preferably 2.4 or less, more preferably 2.2 or less, further preferably 2.0 or less), The extinction coefficient k is preferably 1.0 or more (preferably 1.1 or more, more preferably 1.4 or more, still more preferably 1.6 or more).

  Here, the refractive index n and the extinction coefficient k of the thin film are not determined only by the composition of the thin film. The film density and crystal state of the thin film are factors that influence the refractive index n and the extinction coefficient k. For this reason, by forming the high-transmission layer 5 and the low-transmission layer 7 constituting the phase shift film 11 by adjusting the conditions for forming these layers, each of these layers has a desired refractive index n and extinction coefficient k. Suppose that

  Further, in the high transmission layer 5 and the low transmission layer 7 in which the refractive index n and the extinction coefficient k are set as described above, the film thickness of the high transmission layer 5 is larger than the film thickness of the low transmission layer 7. In addition, if it is the structure by which the laminated structure 10 which consists of one layer of the high permeable layers 5 and one layer of the low permeable layers 7 is laminated | stacked, the sum total of the film thickness of the some high permeable layers 5 will be several. It becomes larger than the total film thickness of the low transmission layer 7. Further, as shown in FIG. 2, even in a configuration in which one high-transmitting layer 5 is stacked with respect to one or a plurality of stacked structures 10, the total film thickness of the plurality of high-transmitting layers 5 is It becomes larger than the sum of the film thicknesses of the plurality of low transmission layers 7.

<Top layer 9>
The phase shift film 11 is preferably provided with an uppermost layer 9 formed of a material containing silicon and oxygen at a position farthest from the translucent substrate 3. Such a top layer 9 is formed of a material (3) consisting of silicon and oxygen, or a material (4) consisting of silicon, nitrogen and oxygen, or these materials (3) or The material (4) is made of any one of the materials (5) containing one or more elements selected from a metalloid element, a nonmetallic element, and a rare gas.

  The metalloid element, nonmetal element, and rare gas contained in the uppermost layer 9 are the same as the metalloid element, nonmetal element, and rare gas contained in the high transmission layer 5 and the low transmission layer 7.

The uppermost layer 9 made of such a material includes not only a structure having substantially the same composition in the thickness direction of the layer but also a structure having a composition gradient in the thickness direction of the layer. The composition gradient in the uppermost layer 9 is a change in the composition such that the oxygen content in the layer increases as the distance from the translucent substrate 3 increases. Among the uppermost layer 9 having such a configuration, examples of a material suitable for a configuration having substantially the same composition in the layer thickness direction include SiO ₂ and SiON. Further, as an example suitable for a composition whose composition is inclined in the thickness direction of the layer, the translucent substrate 3 side is SiN, the oxygen content increases as the distance from the translucent substrate 3 increases, and the surface layer is made of SiO _2. Or it is preferable that it is the structure which is SiON. In this configuration, the top layer 9 may be a layer obtained by oxidizing the surface layer of the high transmission layer 5 or the low transmission layer 7 to have a composition gradient.

  Since the phase shift film 11 has such an uppermost layer 9, the chemical resistance of the phase shift film 11 can be ensured. That is, the high-permeability layer 5 and the low-permeability layer 7 are formed of a material containing silicon and nitrogen, and the oxygen content is suppressed. As described above, the silicon-based material film that does not actively contain oxygen and that contains nitrogen has high light resistance against ArF excimer laser light, but compared with the silicon-based material film that actively contains oxygen. Tend to have low chemical resistance. Therefore, the phase shift film 11 has the uppermost layer 9 made of a material containing silicon and oxygen, so that the chemical resistance of the phase shift film 11 can be improved.

  By providing such an uppermost layer 9, the mask blank 1 is pinned on the phase shift film 11 on the concave defect portion F even after the phase shift film 11 is washed with hot water for 5 minutes or more. Hole defects are not formed, and the phase shift film 11 is left on the concave defect portion F.

  The phase shift film 11 (including the modified phase shift film 11a. The same applies hereinafter) composed of the above layers has a transmittance of 1% for ArF excimer laser light in order to effectively function the phase shift effect. Preferably, it is preferably 2% or more. Further, the phase shift film 11 is preferably adjusted so that the transmittance for ArF excimer laser light is 30% or less, more preferably 20% or less, and further preferably 10% or less. The phase shift film 11 has a phase difference of 170 to 190 degrees with respect to the transmitted ArF excimer laser light and the light that has passed through the air by the same distance as the thickness of the phase shift film 11. It is preferable that the adjustment is performed.

<Light shielding film 13>
In the mask blank 1 of the present invention (including the modified mask blank 1a, the same applies hereinafter), the light shielding film 13 is preferably laminated on the phase shift film 11. Generally, in a transfer mask configured using a mask blank, the outer peripheral area of a transfer pattern formation area (transfer pattern formation area) is exposed and transferred to a resist film on a semiconductor wafer using an exposure device. It is required to secure an optical density (OD) of a predetermined value or more so that the resist film is not affected by the exposure light transmitted through the outer peripheral region. This also applies to a phase shift mask configured using a mask blank 1 having a phase shift film 11. Usually, it is desirable that the OD is 3.0 or more in the outer peripheral region of the transfer mask including the phase shift mask, and an OD of at least 2.8 or more is required. As described above, the phase shift film 11 has a function of transmitting exposure light with a predetermined transmittance, and it is difficult to ensure a predetermined value of OD with the phase shift film 11 alone. For this reason, it is desirable that the light shielding film 13 is laminated on the phase shift film 11 in order to secure an insufficient OD at the stage of manufacturing the mask blank 1. With the configuration of the mask blank 1 as described above, the light shielding film 13 in a region (basically a transfer pattern forming region) using the phase shift effect in the course of manufacturing the phase shift mask by patterning the phase shift film 11. Is removed, it is possible to manufacture a phase shift mask in which a predetermined value of OD is secured in the outer peripheral region where the light shielding film 13 is left.

  The light shielding film 13 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 13 having a single-layer structure or a laminated structure of two or more layers may have a composition having almost the same composition in the thickness direction of the film or the layer, or a composition having a composition gradient in the layer thickness direction It may be.

  When the light shielding film 13 is provided in contact with the phase shift film 11, it is necessary to apply a material having sufficient etching selectivity with respect to an etching gas used when forming a transfer pattern on the phase shift film 11. There is. In this case, the light shielding film 13 is preferably formed of a material containing chromium. Examples of the material containing chromium that forms the light shielding film 13 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 13 is one or more selected from oxygen, nitrogen, carbon, boron, and fluorine as chromium. It is preferable to use a material containing an element. Further, the chromium-containing material forming the light shielding film 13 may contain one or more elements of molybdenum and tin. By including one or more elements of molybdenum and tin, the etching rate for the mixed gas of chlorine-based gas and oxygen gas can be further increased.

  On the other hand, in the mask blank 1 of the present invention, when another film is interposed between the light-shielding film 13 and the phase shift film 11, the above-described material containing chromium is used as another film (also serving as an etching stopper). It is preferable that the light-shielding film 13 be formed of a material containing silicon. A material containing chromium is etched by a mixed gas of a chlorine-based gas and an oxygen gas, but a resist film formed of an organic material is easily etched by this mixed gas. A silicon-containing material is generally etched with a fluorine-based gas or a chlorine-based gas, but these etching gases basically do not contain oxygen. Therefore, with such a configuration, it is possible to etch the light-shielding film 13 made of a material containing silicon while suppressing the amount of reduction of the resist film formed of an organic material.

  The material containing silicon that forms the light shielding film 13 may contain a transition metal or a metal element other than the transition metal. This is because, when a phase shift mask is produced from this mask blank 1, the pattern formed by the light shielding film 13 is basically a light shielding pattern in the outer peripheral region, and is irradiated with ArF excimer laser light compared to the transfer pattern forming region. This is because it is rare that the accumulated amount is small or the light shielding film 13 remains in a fine pattern, and even if the light resistance to the ArF excimer laser light is low, a substantial problem hardly occurs. In addition, when the light shielding film 13 contains a transition metal, the light shielding performance is greatly improved as compared with the case where the transition metal is not contained, and the thickness of the light shielding film 13 can be reduced. As transition metals to be contained in the light shielding film 13, transition metals include molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), and nickel (Ni). , Vanadium (V), zirconium (Zr), ruthenium (Ru), rhodium (Rh), niobium (Nb), palladium (Pd), or any one metal or an alloy of these metals.

  The light shielding film 13 may be formed of a material that contains one or more elements selected from hafnium (Hf) and zirconium (Zr) and tantalum (Ta), and does not contain oxygen except for the surface layer. In this case, the light-shielding film 13 can be dry-etched with an etching gas containing a chlorine-based gas and not containing an oxygen gas, and has a phase relative to the dry-etching with an etching gas containing a fluorine-based gas. It has etching selectivity with the material forming the shift film 11.

  In view of the above etching characteristics, it is more preferable to form the light shielding film 13 with a tantalum-hafnium alloy, a tantalum-zirconium alloy, a tantalum-hafnium-zirconium alloy, or a compound containing an element other than oxygen with respect to these alloys. . Examples of elements other than oxygen to be contained in the light shielding film 13 in this case include elements such as nitrogen (N), carbon (C), hydrogen (H), and boron (B). In this case, the material of the light shielding film 13 may include an inert gas such as helium (He), argon (Ar), krypton (Kr), and xenon (Xe). In this case, the light shielding film 13 is a material that can be dry-etched with an etching gas that contains a chlorine-based gas and does not contain an oxygen gas, and this etching gas is difficult to etch the phase shift film 11.

<Etching mask film 15>
In the mask blank 1 including the light shielding film 13 stacked on the phase shift film 11, an etching formed of a material having etching selectivity with respect to an etching gas used when etching the light shielding film 13 on the light shielding film 13. More preferably, the mask film 15 is further laminated. Since the light shielding film 13 has a function of ensuring a predetermined optical density (OD), there is a limit to reducing the thickness thereof. It is sufficient for the etching mask film 15 to have a film thickness that can function as an etching mask until dry etching for forming a pattern on the light shielding film 13 immediately below is completed. There are no restrictions. For this reason, the thickness of the etching mask film 15 can be made significantly thinner than the thickness of the light shielding film 13. The resist film 17 made of an organic material used as an etching mask in dry etching for forming a pattern on the etching mask film 15 is a film that only functions as an etching mask until dry etching of the etching mask film 15 is completed. Thickness is sufficient. For this reason, the thickness of the resist film 17 can be significantly reduced by providing the etching mask film 15 as compared with the conventional configuration in which the etching mask film 15 is not provided.

In the case where the light shielding film 13 is formed of a material containing chromium, the etching mask film 15 is preferably formed of the material containing silicon. In this case, since the etching mask film 15 tends to have low adhesion to the resist film made of an organic material, the surface of the etching mask film 15 is subjected to HMDS (Hexamethyldisilazane) treatment to improve surface adhesion. It is preferable. In this case, the etching mask film 15 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 etching mask film 15 when the light shielding film 13 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 of the material include Ta, TaN, TaON, TaBN, TaBON, TaCN, TaCON, TaBCN, TaBOCN, and the like. On the other hand, when the light shielding film 13 is formed of a material containing silicon, the etching mask film 15 is preferably formed of the material containing chromium.

<Resist film 17>
In the mask blank 1 of the present invention, the resist film 17 made of an organic material is preferably formed with a film thickness of 100 nm or less in contact with the surface of the etching mask film 15. In the case of a fine pattern corresponding to the DRAM hp32 nm generation, the transfer pattern to be formed on the etching mask film 15 may be provided with SRAF (Sub-Resolution Assist Feature) having a line width of 40 nm. However, even in this case, the film thickness of the resist film 17 can be suppressed by providing the etching mask film 15 as described above, whereby the cross-sectional aspect ratio of the resist pattern constituted by the resist film 17 is 1: 2. .5, the resist pattern can be prevented from collapsing or detaching during development, rinsing, or the like. The resist film 17 preferably has a film thickness of 80 nm or less.

≪Mask blank manufacturing method≫
Next, the manufacturing method of the mask blank of this invention is demonstrated. The manufacturing method of the mask blank of the present invention is the manufacturing method of the mask blank 1 of the present invention described above, and is characterized in that the oblique incident rotation sputtering method is applied to the formation of the phase shift film 11. First, the configuration of a film forming apparatus for forming a film by the oblique incidence rotation sputtering method will be described.

<Deposition system>
In FIG. 3, the schematic diagram of an example of the film-forming apparatus used for the manufacturing method of the mask blank 1 of this invention is shown. A film forming apparatus 30 shown in this figure is a sputter film forming apparatus in which film formation is performed by oblique incidence rotation sputtering. The film forming apparatus 30 includes a rotary stage 31 on which the translucent substrate 3 is placed, and a sputtering target 33 disposed in a predetermined state with respect to the rotary stage 31, and the main surface S of the translucent substrate 3. A film forming apparatus capable of forming a thin film by sputtering. In the film forming apparatus 30 that can be used in the manufacturing method of the present invention, the translucent substrate 3 placed on the rotary stage 31 and the sputtering target 33 are in a predetermined positional relationship.

  That is, the film forming apparatus 30 is characterized in that the sputtering surface 33 s of the sputtering target 33 is disposed at a position facing the main surface S of the translucent substrate 3 on the rotary stage 31 and obliquely upward. is there. The film forming apparatus 30 includes a film forming chamber 35 in which the rotary stage 31 and the sputtering target 33 are accommodated, and a thin film is formed on the translucent substrate 3 by sputtering in the film forming chamber 35. It is a configuration. The film formation chamber 35 has a gas introduction port 37 and an exhaust port 39 and functions as a vacuum chamber for film formation.

  FIG. 4 is a schematic diagram showing the positional relationship between the light-transmitting substrate 3 and the sputtering target 33 in the film forming apparatus 30 that can be used in the manufacturing method of the present invention. During film formation, the translucent substrate 3 is placed on the rotary stage 31. By the rotation of the rotary stage 31, the translucent substrate 3 rotates around the rotation axis φ that passes through the center of the main surface S and is perpendicular to the main surface S.

  The sputtering target 33 is arranged so as to have a predetermined inclination angle θ (target inclination angle θ) with respect to the main surface S of the translucent substrate 3. That is, the central axis φ1 perpendicular to the sputtering surface 33s of the sputtering target 33 passing through the center O of the sputtering target 33 and perpendicular to the sputtering surface 33s is oblique to the rotation axis φ of the translucent substrate 3.

  Further, in the sputtering target 33, a rotation axis φ of the translucent substrate 3 and a straight line φ2 passing through the center O of the sputtering surface 33s and parallel to the rotation axis φ of the translucent substrate 3 are a predetermined offset distance Doff. It is arranged so that it is in a shifted position.

  Here, in order to improve the in-plane uniformity of the thickness of the thin film formed on the main surface S of the translucent substrate 3, the positional relationship between the translucent substrate 3 and the sputtering target 33 is appropriate. It is necessary to make it. Therefore, the positional relationship between the translucent substrate 3 and the sputtering target 33 in the film forming apparatus of the present invention will be further described as follows.

  As shown in FIGS. 3 and 4, in the film forming apparatus 30 used in the present invention, the target inclination angle θ of the sputtering surface 33 s of the sputtering target 33 with respect to the main surface S of the translucent substrate 3 is determined by the translucent substrate 3. This affects not only the in-plane uniformity of the film thickness of the thin film formed on the main surface S but also the film forming rate. Specifically, the target inclination angle θ is suitably from 0 degree to 45 degrees in order to obtain a good in-plane uniformity of the film thickness of the thin film and to obtain a large film formation rate. Further, the preferable target inclination angle θ is 10 degrees to 30 degrees, whereby the in-plane uniformity of the thickness of the thin film formed on the main surface S of the translucent substrate 3 can be improved.

  The offset distance Doff in the film forming apparatus 30 can be adjusted by the area where the in-plane uniformity of the film thickness of the thin film formed on the main surface S of the translucent substrate 3 should be ensured. In general, when the area where good in-plane uniformity is to be ensured is large, the necessary offset distance Doff increases. For example, in the case of a 152 mm square translucent substrate 3, the region where the transfer pattern is formed on the thin film is usually a 132 mm square inner region with the center of the translucent substrate 3 as a reference. In order to realize the accuracy of the thin film thickness distribution within ± 1 nm in the 132 mm square inner region, the offset distance Doff needs to be about 240 mm to 400 mm, and the preferable offset distance Doff is 300 mm to 380 mm.

  Further, by providing the offset distance Doff in this way, it is possible to prevent particles from falling from the sputtering surface 33 s of the sputtering target 33 to the main surface S of the translucent substrate 3 during sputtering film formation. Thereby, it can prevent that a particle mixes into the thin film formed into the main surface S of the translucent board | substrate 3, and it becomes a defect, and it can suppress the defect generation rate in film-forming.

  The optimum range of the vertical distance H between the sputtering target 33 and the translucent substrate 3 in the film forming apparatus 30 varies depending on the offset distance Doff. The vertical distance H is a distance from the height position of the translucent substrate 3 to the height position of the center O of the sputtering target 33. For example, in order to ensure good in-plane uniformity within the 152 mm square translucent substrate 3, the vertical distance H needs to be about 200 mm to 380 mm, and the preferred vertical distance H is 210 mm to 300 mm. .

  Further, as an example, when the film forming apparatus 30 is a magnetron sputtering apparatus, the sputtering target 33 is attached to the magnetron electrode 41 via a backing plate 43. In the mask blank manufacturing method of the present invention, the phase shift film is formed by the oblique incidence rotation sputtering method. However, the sputtering method to which the oblique incidence rotation sputtering method is applied is limited to the magnetron sputtering apparatus. However, an ion beam sputtering apparatus may be used. In the case of magnetron sputtering, a direct current (DC) power source or a high frequency (RF) power source may be appropriately used as the magnetron power source depending on the material of the sputtering target. For example, when using a target with low conductivity (such as a silicon target or a silicon compound target that does not contain a metalloid element or has a low content), it is preferable to apply RF sputtering or ion beam sputtering. In view of the above, it is more preferable to apply RF sputtering.

  The film forming apparatus 30 that can be used in the present invention having the above-described configuration can be disposed as a film forming unit 30a for performing sputtering of the sputtering apparatus as shown in FIG. The sputtering apparatus shown in this figure has a load lock mechanism that can always maintain the film forming unit 30a in a high vacuum state. That is, the load lock chamber 53 is connected to the film forming unit 30 a via the transfer chamber 51. Thereby, it can be set as the apparatus structure which can introduce | transduce a translucent board | substrate to the film-forming part 30a continuously with a fixed space | interval.

  In the sputtering apparatus shown in FIG. 5, the load lock chamber 53 is provided with a valve 55 that isolates the load lock chamber 53 from the atmosphere, and a valve 57 that isolates the load lock chamber 53 and the transfer chamber 51. The load lock chamber 53 can be a single-wafer type in which the translucent substrate can be continuously introduced into the film forming unit 30a described above at a predetermined interval, and is designed to have a predetermined volume. Can be provided.

  The transfer chamber 51 houses a robot arm 61, and the robot arm 61 introduces the translucent substrate from the load lock chamber 53 to the film forming unit 30 a. The robot arm 61 is configured such that, for example, a pantograph-shaped arm 61a opens and closes in the direction A in the drawing and expands and contracts to move the hand 61b provided at the tip thereof in the direction B in the drawing. Further, the robot arm 61 is configured such that a fulcrum opposite to the side on which the hand 61b is provided is fixed to the pantograph-shaped arm 61a so as to be rotatable, and the robot arm 61 can rotate in the C direction in the transfer chamber 51. Further, the robot arm 61 is configured such that the fulcrum can be expanded and contracted vertically (perpendicular to the paper surface) perpendicular to the rotation direction. Furthermore, in order to improve the deposition throughput, an unload lock chamber 63 having the same configuration as the load lock chamber 53 may be added to the transfer chamber 51. A valve 65 for isolating the unload lock chamber 63 and a valve 67 for isolating the unload lock chamber 63 and the transfer chamber 51 are attached.

<Manufacturing procedure of mask blank>
The mask blank manufacturing method of the present invention includes the above-described mask blank 1 (including the modified mask blank 1a) described with reference to FIGS. The same applies hereinafter.

  That is, the manufacturing method of the mask blank of the present invention is a manufacturing method of the mask blank 1 in which the phase shift film 11 is provided on the main surface S having the concave defect portion F of the translucent substrate 3. In the step of forming the phase shift film 11, the translucent substrate 3 is rotated around a rotation axis passing through the center of the main surface S, and the concave defect portion F of the translucent substrate 3 is formed on the sputtering surface of the sputtering target. Film formation is performed by a so-called oblique incidence rotation sputtering method, which includes disposing the main surface S so as to face the main surface S.

  In the step of forming the phase shift film 11, a highly transmissive layer forming step of forming the highly transmissive layer 5 on the main surface S having the concave defect portion F of the translucent substrate 3 by oblique incidence rotation sputtering. Then, a low transmission layer forming step of forming the low transmission layer 7 having a light transmittance lower than that of the high transmission layer 5 on the high transmission layer 5 is performed. In the high transmission layer 5 formed in the high transmission layer forming step, the inner region of the portion of the high transmission layer 5 formed on the concave defect portion F has the low density region D, and the density in the low density region D is The density is relatively lower than the density in the inner region of the highly transmissive layer 5 in the portion formed on the main surface S without the concave defect F.

<High transmission layer formation process and low transmission layer formation process>
In the high permeable layer forming step and the low permeable layer forming step, reactive sputtering is performed in a sputtering gas containing a nitrogen-based gas and a rare gas using a sputtering target made of a material containing silicon. Here, it is particularly characteristic that the mixing ratio of the nitrogen-based gas in the sputtering gas in the low transmission layer forming step is lower than that in the high transmission layer forming step. Thereby, in the low transmission layer forming step, the nitrogen content is relatively less than that of the high transmission layer 5 formed in the high transmission layer forming step, and thereby the light transmission is lower than that of the high transmission layer 5. Layer 7 is deposited.

As the nitrogen-based gas used as the sputtering gas in the above-described high permeable layer forming step and low permeable layer forming step, any gas can be applied as long as it contains nitrogen. As described in the configuration of the mask blank, the high transmission layer 5 and the low transmission layer 7 preferably have a low oxygen content. Therefore, it is preferable to apply a nitrogen-based gas that does not contain oxygen. More preferably, ₂ gas) is applied.

  Moreover, a silicon target made of silicon may be used as a sputtering target containing silicon that is used in the high transmission layer forming step and the low transmission layer forming step. As another example, silicon containing one or more elements selected from metalloid elements and nonmetal elements may be used. Thereby, the high permeable layer 5 and the low permeable layer 7 containing one or more elements selected from a metalloid element and a nonmetallic element in silicon and nitrogen are formed. In this case, it is preferable that one or more elements selected from boron, germanium, antimony and tellurium are contained as the metalloid element. These metalloid elements can be expected to increase the conductivity of the target. For this reason, it is desirable to contain these metalloid elements in the target, particularly when the high transmission layer 5 and the low transmission layer 7 are formed by DC sputtering. As the nonmetallic element, one or more elements selected from carbon, fluorine and hydrogen may be contained.

  In the above high transmissive layer forming step and low transmissive layer forming step, the same sputtering target may be used, or sputtering targets having different compositions may be used. However, it is preferable to use different sputtering targets for the formation of the low transmission layer and the formation of the high transmission layer in the high transmission layer formation step and the low transmission layer formation step. The nitrogen content is greatly different between the low-permeability layer and the high-permeability layer, and the mixing ratio of the nitrogen-based gas of the sputtering gas during sputtering film formation is also greatly different. For this reason, the surface state of the sputtering target when the low transmission layer is formed by sputtering and the surface state of the sputtering target when the high transmission layer is formed by sputtering are greatly different. After forming a highly transmissive layer, using a sputtering target with the surface state as it is, changing the mixing ratio of the nitrogen-based gas of the sputtering gas and attempting to form a low transmissive layer, foreign matter is generated from the sputtering target, etc. There is a possibility that defects frequently occur in the formed low transmission layer. If different targets are used for the formation of the low transmission layer and the formation of the high transmission layer, this concern does not occur and the defect quality of the formed film can be improved.

  When two different sputtering targets are used for the formation of the low transmission layer and the high transmission layer, a configuration of a film forming apparatus in which two sputtering targets are arranged in one film forming chamber and two film forming chambers are prepared. A structure of a film forming apparatus in which one sputtering target is arranged in each film forming chamber can be applied. When the high permeable layer forming step and the low permeable layer forming step are performed in different film forming chambers, the film forming chambers are connected to each other through, for example, the transfer chamber of the film forming apparatus described above with reference to FIG. It is preferable to have a configuration as described above. Thereby, it is possible to perform the high transmissive layer forming step and the low transmissive layer forming step in different film forming chambers without releasing the translucent substrate to the atmosphere.

  On the other hand, in the case where both a high transmissive layer and a low transmissive layer are formed using a film forming apparatus in which one sputtering target is arranged in one film forming chamber, the second layer is formed after the first layer is formed. After adjusting the sputtering gas for forming the first layer, film formation is performed on the dummy substrate, the surface state of the sputtering target is optimized, and then the second layer is formed on the first layer. It is preferable to form a layer. By performing such a process, the defect quality of the second layer can be improved.

Of the high permeable layer forming step and the low permeable layer forming step, a sputtering target containing silicon, particularly used in the low permeable layer forming step, may be one in which a transition element is contained in silicon. Thereby, the low-permeability layer 7 containing a transition metal in silicon and nitrogen is formed.

  Furthermore, as a sputtering target containing silicon used in the high permeable layer forming step and the low permeable layer forming step, it is preferable to use a silicon target in any step. As a result, the light-transmitting layer 5 and the low-transmitting layer 7 made of silicon and nitrogen, which have good light resistance to the exposure light of the ArF excimer laser and prevent deterioration of optical characteristics over time, are formed.

  In particular, in the highly permeable layer forming step, when forming the highly permeable layer 5 having a higher nitrogen content than the low permeable layer 7, it is preferable to perform film formation by a reactive sputtering method in poison mode. In the film formation by the poison mode, the reactive sputtering method in which the mixing ratio of the nitrogen-based gas is set to be larger than the range of the mixing ratio of the nitrogen-based gas, which is a transition mode that tends to be unstable. A membrane is performed. On the other hand, in forming the low transmission layer 7 having a lower nitrogen content than the high transmission layer 5 in the low transmission layer forming step, it is preferable to perform film formation by a reactive sputtering method in a metal mode. In the metal mode film formation, the reactive sputtering method in which the nitrogen gas mixture ratio is set lower than the range of the nitrogen gas mixture ratio in the transition mode, which tends to be unstable. A membrane is performed.

  As a result, both the high transmissive layer 5 and the low transmissive layer 7 can be formed by reactive sputtering under film formation conditions in which film formation rate and voltage fluctuation during film formation are small. As a result, composition and optical characteristics The phase shift film 11 having high uniformity and low defects can be formed.

  When a plurality of laminated structures 10 each composed of one high transmission layer 5 and one low transmission layer 7 are laminated on the translucent substrate 3, the above high transmission layer forming step and low transmission are performed. The layer formation process may be repeated in this order. Further, in the case of manufacturing the mask blank 1a of the modified example 1 of FIG. 2, the formation of the high transmission layer 5 and the low transmission layer on the main surface S of the translucent substrate 3 by the high transmission layer forming step. After the formation of the low transmission layer 7 by the forming process is repeated as many times as necessary in this order, the high transmission layer 5 is formed by the high transmission layer forming process.

  In the high transmission layer forming process and the low transmission layer forming process as described above, the phase shift film 11 obtained by these processes has a predetermined phase difference and a predetermined transmittance with respect to exposure light (for example, ArF excimer laser light). It is necessary to form the high transmissive layer 5 and the low transmissive layer 7 in which the refractive index n and the extinction coefficient k are set within predetermined ranges so as to satisfy the above. For this reason, in the highly permeable layer forming step and the low permeable layer forming step, the ratio of the mixed gas of the nitrogen-based gas and the rare gas is adjusted. In addition, the positional relationship such as the pressure of the film formation atmosphere, the power applied to the sputtering target, and the distance between the sputtering target and the translucent substrate 3 is also adjusted. It is unique to the membrane device, and the formed high transmission layer 5 and low transmission layer 7 are appropriately adjusted so as to have a desired refractive index n and extinction coefficient k.

<Top layer formation process>
When the phase shift film 11 includes the uppermost layer 9 formed of a material containing silicon and oxygen at a position farthest from the translucent substrate 3, the high transmission layer formation step and the low transmission layer formation step are performed. After the completion, the uppermost layer forming step is performed. In the uppermost layer forming step, the uppermost layer 9 is formed by the oblique incidence rotation sputtering method, following the high transmissive layer forming step and the low transmissive layer forming step.

In the uppermost layer forming step, a silicon target or a sputtering target made of a material containing at least one element selected from a metalloid element and a nonmetallic element is used in a sputtering gas containing nitrogen gas, oxygen gas, and rare gas. The top layer 9 is formed by reactive sputtering at This uppermost layer forming step can be applied to the formation of the uppermost layer 9 having a configuration having substantially the same composition in the layer thickness direction and a composition having a gradient composition. In the uppermost layer forming step, a silicon dioxide (SiO ₂ ) target or a target made of a material containing at least one element selected from a metalloid element and a non-metal element in silicon dioxide (SiO ₂ ) is used, and a rare gas and If necessary, the uppermost layer 9 formed by reactive sputtering in a sputtering gas containing a nitrogen-based gas may be formed. This uppermost layer forming step can also be applied to the formation of the uppermost layer 9 in either a configuration having substantially the same composition in the layer thickness direction or a configuration having a composition gradient.

  In the case of forming the uppermost layer 9 having the composition gradient, after the material layer containing silicon and nitrogen is formed by the reactive sputtering described above, an additional process of oxidizing at least the surface layer of the material layer is performed. Thereby, the uppermost layer 9 having a composition gradient in the thickness direction of the layer is formed. Examples of the treatment for oxidizing the surface layer of the material layer in this case include a heat treatment in an oxygen-containing gas such as the air, and a treatment in which ozone or oxygen plasma is brought into contact with the uppermost layer. Also by this, as the distance from the translucent substrate 3 increases, the top layer 9 having a composition gradient is obtained so that the oxygen content in the layer increases. The material layer containing silicon and nitrogen may be formed by reactive sputtering under the same film formation conditions as those of the high transmission layer 5 or the low transmission layer 7.

  Further, as another example of the uppermost layer forming step for forming the uppermost layer 9 having a composition gradient, reactive sputtering in which the mixing ratio of each gas component contained in the sputtering gas is applied in the uppermost layer forming step described above is applied. You may do it. Thereby, the uppermost layer 9 having a composition gradient in the thickness direction of the layer can be formed. In this case, for example, the oxygen mixing ratio in the sputtering gas is increased as the film formation proceeds. Thereby, as the distance from the translucent substrate 3 increases, an uppermost layer 9 having a composition gradient is obtained so that the oxygen content in the layer increases.

  When the mask blank 1 of the present invention has a configuration in which the light shielding film 13 is laminated on the phase shift film 11, the light shielding film forming step is performed after the phase shift film 11 is formed. In the case where the etching mask film 15 is laminated on the light shielding film 13, the etching mask film forming process is performed after the light shielding film forming process. In the light shielding film forming step and the etching mask film forming step, the respective film forming methods are not limited, and, for example, a sputtering method is applied. Further, when the mask blank 1 has a structure in which a resist film 17 is laminated on the etching mask film 15, a resist film forming process is performed after the etching mask film forming process. For example, a spin coating method is applied to the resist film forming step.

≪Phase shift mask≫
FIG. 6 is a cross-sectional view showing the configuration of the phase shift mask of the present invention. As shown in this figure, the phase shift mask 2 is characterized in that a transfer pattern 20 is formed on the phase shift film in the above-described mask blank of the present invention. Here, the configuration in which the transfer pattern 20 is formed on the phase shift film 11 of the mask blank 1 described with reference to FIG. 1 will be described with reference to FIG. 6, but the mask of the modified example shown in FIG. Similarly, in the blank 1a, a transfer pattern is formed on each phase shift film 11a. The same applies to the method of manufacturing a phase shift mask described below.

  That is, the phase shift mask 2 has a transfer pattern 20 formed by patterning the phase shift film 11 in the transfer pattern forming region 3 a at the center of the translucent substrate 3. Further, the outer peripheral region 3 b of the transfer pattern forming region 3 a is covered with a light shielding film 13 left on the phase shift film 11. In particular, the concave defect portion F in the translucent substrate 3 is not disposed in a region of the transfer pattern 20 where a fine transfer pattern using phase shift is formed, that is, a large-area phase shift film 20. The concave defect portion F is covered with a transfer pattern 20a made of

  Here, as described above, a low-density region (not shown) having a lower density than the surroundings exists in the high-transmission layer 5 closest to the translucent substrate 3 in the phase shift film 11 above the concave defect portion F. To do. However, since the high transmission layer 5 is originally a layer having a high transmittance, even if the high transmission layer 5 is formed at a low density, the degree of increase in the overall transmittance in the film thickness direction of the phase shift film resulting therefrom. The phase shift mask 2 having such a phase shift film 11 can suppress the influence of the low density region on the exposure and transfer of the pattern. Further, even if the transfer pattern 20a on the concave defect portion F has a phase shift amount that is not set due to the presence of the low density region, a fine exposure pattern by pattern exposure using the phase shift mask 2 is used. Does not affect the formation of

≪Phase shift mask manufacturing method≫
FIG. 7 is a manufacturing process diagram of the phase shift mask of the present invention. As shown in this figure, the method for manufacturing a phase shift mask according to the present invention is characterized in that it has a step of forming a transfer pattern 20 on the phase shift film 11 of the mask blank 1 manufactured by the above manufacturing method. Hereinafter, a method of manufacturing the phase shift mask will be described with reference to FIG. Here, a case where a material containing chromium is applied to the light shielding film 13 and a material containing silicon is applied to the etching mask film 15 is illustrated.

  First, as shown in FIG. 7A, a first pattern, which is a transfer pattern (phase shift pattern) to be formed on the phase shift film 11, is exposed and drawn on the resist film 17 in the mask blank 1, and further developed, etc. The predetermined process is performed to form a first resist pattern 17a having a transfer pattern. At this time, the pattern design is such that the concave defect portion F of the translucent substrate 3 is covered with the first resist pattern 17a that does not use the phase shift.

  Next, as shown in FIG. 7B, dry etching of the etching mask film 15 using a fluorine-based gas is performed using the first resist pattern 17a as a mask, and the first pattern (etching mask pattern 15a) is applied to the etching mask film 15. Form. Thereafter, the first resist pattern 17a is removed.

  Next, as shown in FIG. 7C, using the etching mask pattern 15a as a mask, the light shielding film 13 is dry-etched using a mixed gas of chlorine-based gas and oxygen gas, and the first pattern (light shielding film) is formed on the light shielding film 13. Pattern 13a) is formed.

  Thereafter, as shown in FIG. 7D, the phase shift film 11 using fluorine-based gas is dry-etched using the light shielding film pattern 13a as a mask to form a first pattern (transfer pattern 20) on the phase shift film 11. . At the same time, the etching mask pattern 15a (see FIG. 7C) on the light shielding film pattern 13a is also removed.

  Next, as shown in FIG. 7E, a second resist pattern 21 is formed in a shape covering the outer peripheral region 3b of the translucent substrate 3. At this time, first, a resist film is formed on the translucent substrate 3 by a spin coating method. Next, the resist film is exposed so as to have a shape covering the outer peripheral region 3b of the translucent substrate 3 where the light shielding film pattern 13a is to be left, and a predetermined process such as a development process is further performed. A resist pattern 21 is formed. Thereafter, using the second resist pattern 21 as a mask, the light shielding film pattern 13a is dry-etched using a mixed gas of chlorine gas and oxygen gas, and the second pattern (light shielding pattern 13b) is applied to the light shielding film pattern 13a. Form. Thereafter, the second resist pattern 21 is removed, and a predetermined process such as cleaning is performed. Thus, the phase shift mask 2 shown in FIG. 6 is obtained.

The chlorine-based gas used in the dry etching is not particularly limited as long as it contains Cl. For example, a chlorine-based _{gas, Cl 2, SiCl 2, CHCl} 3, CH 2 Cl 2, CCl 4, BCl 3 and the like. Further, the fluorine-based gas used in the dry etching is not particularly limited as long as F is contained. For example, a fluorine-based _{gas, 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.

≪Semiconductor device manufacturing method≫
The semiconductor device manufacturing method of the present invention uses the phase shift mask manufactured using the phase shift mask or the mask blank, and exposes and transfers the transfer pattern of the phase shift mask to the resist film on the substrate. It is characterized by that. The manufacturing method of such a semiconductor device is performed as follows.

  First, a substrate for forming a semiconductor device is prepared. This substrate may be, for example, a semiconductor substrate, a substrate having a semiconductor thin film, or a substrate on which a finely processed film is formed. A resist film is formed on the prepared substrate, pattern exposure using the phase shift mask of the present invention is performed on the resist film, and the transfer pattern formed on the phase shift mask is exposed and transferred to the resist film. At this time, as the exposure light, exposure light corresponding to the phase shift film constituting the transfer pattern is used. For example, ArF excimer laser light is used here.

  Thereafter, the resist film to which the transfer pattern is exposed and transferred is developed to form a resist pattern, and the resist layer is used as a mask to perform etching processing or introduce impurities into the surface layer of the substrate. After the processing is completed, the resist pattern is removed.

  The semiconductor device is completed by repeatedly performing the above processing on the substrate while exchanging the transfer mask, and further performing necessary processing.

  In the manufacture of the semiconductor device as described above, by using the phase shift mask of the present invention, no transfer defect occurs even if the transfer pattern of the phase shift mask is exposed and transferred to the resist film on the substrate. The pattern can be transferred to the resist film with sufficient accuracy to meet the design specifications. For this reason, when the circuit pattern is formed by dry etching the lower layer film using this resist film pattern as a mask, a highly accurate circuit pattern free from wiring short-circuiting or disconnection due to insufficient accuracy can be formed.

  Hereinafter, the embodiment of the present invention will be described more specifically by way of example with reference to FIG. 1 and necessary drawings.

[Manufacture of mask blanks]
A translucent substrate 3 made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. The translucent substrate 3 is obtained by polishing the end surface and the main surface S to a predetermined surface roughness, and then performing a predetermined cleaning process and a drying process. Part F is included.

  Next, the translucent substrate 3 was placed on the rotating stage 31 in the film forming chamber 35 in the film forming apparatus for forming the film by the oblique incidence rotary sputtering method described with reference to FIGS. A silicon (Si) target was mounted on the backing plate 43 as the sputtering target 33. In this film forming apparatus, the target inclination angle θ between the sputtering surface 33 s of the sputtering target 33 and the main surface S of the translucent substrate 3 is 15 degrees, and the offset distance Doff between the sputtering target 33 and the translucent substrate 3. Was set to 340 mm, and the vertical distance (H) between the sputtering target 33 and the translucent substrate 3 was set to 280 mm.

  Next, the inside of the film forming chamber 35 is evacuated by a vacuum pump through the exhaust port 39, and after reaching a vacuum level that does not affect the characteristics of the thin film formed by the atmosphere in the film forming chamber 35, nitrogen is supplied from the gas inlet 37. The mixed gas was introduced, RF power was applied to the magnetron electrode 41 using an RF power source (not shown), and film formation was performed by sputtering. The RF power supply has an arc detection function and can monitor the discharge state during sputtering. The pressure inside the film forming chamber 35 was measured with a pressure gauge (not shown).

Then, a mixed gas of argon (Ar) and nitrogen (N ₂ ) (flow rate ratio: Ar: N ₂ = 1: 3, pressure = 0.09 Pa) is used as the sputtering gas, and the power of the RF power source is set to 2.8 kW. A highly transmissive layer 5 (Si: N = 46 at%: 54 at%) made of silicon and nitrogen was formed on the main surface S of the translucent substrate 3 by sputtering (RF sputtering) to a thickness of 55 nm. Only the highly transmissive layer 5 is formed on the main surface of another translucent substrate under the same conditions, and the optical property of the highly transmissive layer 5 is measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 2.52, and the extinction coefficient k was 0.39. The conditions used when forming the highly permeable layer 5 are as follows: the flow ratio of N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the sputtering gas is determined in advance by the RF sputtering apparatus used; Then, the relationship with the film forming speed is verified, and film forming conditions such as a flow rate ratio capable of stably forming a film in the reaction mode (poison mode) region are selected. The composition of the high transmission layer 5 is a result obtained by measurement by X-ray photoelectron spectroscopy (XPS). The same applies to other films.

Next, following the film formation of the high transmission layer 5, a mixed gas of argon (Ar) and nitrogen (N ₂ ) (flow rate ratio Ar: N ₂ = 2: 3, pressure = 0.035 Pa) is used as a sputtering gas, A low transmission layer 7 (Si: N = 59 at%: 41 at%) made of silicon and nitrogen was formed to a thickness of 12 nm by reactive sputtering (RF sputtering) with an RF power supply of 2.8 kW. Only the low transmission layer 7 is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of the low transmission layer 7 are measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 1.85, and the extinction coefficient k was 1.70. The conditions used when forming the low-permeability layer 7 are as follows: the flow ratio of N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the sputtering gas is determined in advance by the RF sputtering apparatus used; Then, the relationship with the film forming speed is verified, and film forming conditions such as a flow rate ratio capable of stably forming a film in the metal mode region are selected.

Next, the translucent substrate 3 on which the high transmission layer 5 and the low transmission layer 7 were laminated was placed on the rotary stage 31 in the film formation chamber 35 in the same film formation apparatus. A silicon dioxide (SiO ₂ ) target was mounted on the backing plate 43 as the sputtering target 33. Then, argon (Ar) gas (pressure = 0.03 Pa) is used as the sputtering gas, the power of the RF power source is set to 1.5 kW, and the uppermost layer 9 made of silicon and oxygen is formed to 4 nm on the low transmission layer 7 by RF sputtering. The thickness was formed. Note that only the uppermost layer 9 is formed under the same conditions on the main surface of another translucent substrate, and the optical property of the uppermost layer 9 is measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 1.56, and the extinction coefficient k was 0.00.

  The phase shift film 11 composed of the high transmission layer 5, the low transmission layer 7, and the uppermost layer 9 was formed on the translucent substrate 3 by the above procedure. When the transmittance and phase difference at the wavelength of the ArF excimer laser light (about 193 nm) were measured with respect to the phase shift film 11 with a phase shift amount measuring device, the transmittance was 5.97% and the phase difference was 177.7. It was a degree.

Next, the translucent substrate 3 on which the phase shift film 11 is formed is installed in a single-wafer DC sputtering apparatus, and using a chromium (Cr) target, argon (Ar), carbon dioxide (CO ₂ ), nitrogen ( N ₂ ) and helium (He) mixed gas (flow ratio Ar: CO ₂ : N ₂ : He = 22: 39: 6: 33, pressure = 0.2 Pa) is used as the sputtering gas, and the power of the DC power source is 1. The lowermost layer of the light shielding film 13 made of CrOCN was formed to a thickness of 30 nm on the phase shift film 11 by reactive sputtering (DC sputtering).

Next, using the same chromium (Cr) target, a mixed gas of argon (Ar) and nitrogen (N ₂ ) (flow rate ratio Ar: N ₂ = 83: 17, pressure = 0.1 Pa) is used as a sputtering gas, and a DC power source The lower layer of the light shielding film 13 made of CrOCN was formed to a thickness of 4 nm on the phase shift film 11 by reactive sputtering (DC sputtering) with a power of 1.4 kW.

Next, using the same chromium (Cr) target, a mixed gas of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He) (flow rate ratio: Ar: CO ₂ : N ₂ : He = 21: 37: 11: 31, pressure = 0.2 Pa) as the sputtering gas, the power of the DC power source is 1.9 kW, and the light-shielding film made of CrOCN is formed on the phase shift film 11 by reactive sputtering (DC sputtering). The upper layer of 13 was formed with a thickness of 14 nm. By the above procedure, the light shielding film 13 made of a chromium-based material having a three-layer structure of the lowermost layer made of CrOCN, the lower layer made of CrN, and the upper layer made of CrOCN was formed with a total film thickness of 48 nm from the phase shift film 11 side.

Further, the translucent substrate 3 on which the phase shift film 11 and the light shielding film 13 are laminated is installed in a single wafer RF sputtering apparatus, and a silicon dioxide (SiO ₂ ) target is used, and argon (Ar) gas (pressure = pressure = 0.03 Pa) was used as the sputtering gas, the power of the RF power source was set to 1.5 kW, and the etching mask film 15 made of silicon and oxygen was formed to a thickness of 5 nm on the light shielding film 13 by RF sputtering.

  Next, the surface of the etching mask film 15 was subjected to HMDS treatment. Subsequently, a resist film 17 made of a chemically amplified resist for electron beam drawing was formed with a film thickness of 80 nm in contact with the surface of the etching mask film 15 by spin coating. By the above procedure, a mask blank 1 having a structure in which a phase shift film 11 having a three-layer structure, a light shielding film 13, an etching mask film 15, and a resist film 17 are laminated in this order on the translucent substrate 3 was manufactured. .

[Manufacture of phase shift mask]
Using the mask blank 1 produced in this example, the phase shift mask 2 of the example was produced in the following procedure. First, referring to FIG. 7A, a first pattern, which is a phase shift pattern to be formed on the phase shift film, is drawn on the resist film 17 with an electron beam, and a predetermined development process and a cleaning process are performed. A first resist pattern 17a having a pattern was formed. At this time, the pattern design is such that the concave defect portion F of the translucent substrate 3 is covered with the first resist pattern 17a not using the phase shift.

Next, referring to FIG. 7B, dry etching using CF ₄ gas was performed using the first resist pattern 17 a as a mask to form a first pattern (etching mask pattern 15 a) on the etching mask film 15. Thereafter, the first resist pattern 17a was removed.

Next, referring to FIG. 7C, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed using the etching mask pattern 15a as a mask, and the light shielding film 13 is subjected to the first etching. 1 pattern (light shielding film pattern 13a) was formed.

Next, referring to FIG. 7D, the first pattern (transfer pattern 20) was formed on the phase shift film 11 by performing dry etching using a fluorine-based gas (SF ₆ + He) using the light shielding film pattern 13a as a mask. At this time, the etching mask pattern 15a was removed at the same time.

Next, referring to FIG. 7E, a resist film made of a chemically amplified resist for electron beam drawing with a film thickness of 150 nm was formed on the light shielding film pattern 13a by spin coating. Next, the resist film is subjected to pattern exposure of a second pattern, which is a pattern (light-shielding pattern 13b) to be formed on the light-shielding film 13, and further subjected to a predetermined process such as a development process, whereby the second pattern having the light-shielding pattern The resist pattern 21 was formed. Subsequently, using the second resist pattern 21 as a mask, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed, and the light shielding pattern 13 b is formed on the light shielding film 13. Formed. Thereafter, the second resist pattern 21 was removed, and a predetermined process such as cleaning was performed to obtain the phase shift mask 2 shown in FIG.

When the mask pattern was inspected by the mask inspection apparatus for the halftone phase shift mask 2 of the manufactured example, it was confirmed that a fine pattern was formed within the allowable range from the design value. Next, the ArF excimer laser beam was irradiated to the phase shift pattern of the phase shift mask 2 of this example at an integrated dose of 20 kJ / cm ² . The CD change amount of the phase shift pattern before and after this irradiation treatment was about 2 nm, and the CD change amount was within a range usable as a phase shift mask.

  The resist film on the semiconductor device is exposed to exposure light with a wavelength of 193 nm using AIMS 193 (Carl Zeiss) with respect to the halftone phase shift mask 200 of the embodiment after the irradiation process of ArF excimer laser light. The transferred image was simulated when transferred. When the exposure transfer image of this simulation was verified, the design specifications were sufficiently satisfied. From this result, even if the concave defect portion F exists on the main surface S of the translucent substrate 3, it is covered with the transfer pattern 20a made of the large-area phase shift film 11 that does not use the phase shift. By doing so, it can be said that the circuit pattern finally formed on the semiconductor device can be formed with high accuracy even if it is exposed and transferred to the resist film on the substrate in the manufacturing process of the semiconductor device.

DESCRIPTION OF SYMBOLS 1, 1a ... Mask blank 2 ... Phase shift mask 3 ... Translucent substrate 5 ... High transmission layer 7 ... Low transmission layer 9, 9 '... Top layer 10 ... Laminated structure 11, 11a ... Phase shift film 20 ... Transfer pattern 33 ... Sputtering target 33a ... Sputtering surface D ... Low density region F ... Concave defect part S ... Main surface

Claims (21)

A mask blank in which a phase shift film is provided on a main surface of a translucent substrate,
The translucent substrate has a concave defect portion on the main surface on which the phase shift film is formed,
The phase shift film includes a structure in which a high-transmitting layer and a low-transmitting layer having a lower light transmittance are stacked in this order from the light-transmitting substrate side,
The internal region of the high transmission layer of the portion formed on the concave defect portion has a low density region,
The mask blank, wherein the density in the low density region is relatively lower than the density in the inner region of the high transmission layer in a portion formed on the main surface without the concave defect. The high transmission layer and the low transmission layer are formed of a material containing silicon and nitrogen,
The mask blank according to claim 1, wherein the high transmission layer has a relatively high nitrogen content as compared with the low transmission layer. The high-permeability layer and the low-permeability layer are formed of a material composed of silicon and nitrogen, or a material containing one or more elements selected from a metalloid element, a nonmetal element, and a rare gas in the material. The mask blank according to claim 1 or 2. The mask blank according to any one of claims 1 to 3, wherein the high transmission layer and the low transmission layer are made of the same constituent element. The mask blank according to any one of claims 1 to 4, wherein the phase shift film has two or more combinations of laminated structures of the high transmission layer and the low transmission layer. The mask blank according to any one of claims 1 to 5, wherein the high transmission layer and the low transmission layer are formed of a material made of silicon and nitrogen. The mask blank according to claim 1, wherein the high transmission layer has a film thickness larger than that of the low transmission layer. The mask according to claim 1, wherein the phase shift film includes an uppermost layer formed of a material containing silicon and oxygen at a position farthest from the translucent substrate. blank. The phase shift film is formed at a position farthest from the light-transmitting substrate, from a material consisting of silicon and oxygen, a material consisting of silicon, nitrogen and oxygen, or a metalloid element, a nonmetallic element, and a rare gas. The mask blank according to any one of claims 1 to 8, further comprising an uppermost layer formed of any one of materials containing one or more selected elements. The phase shift film formed on the concave defect portion remains even after the phase shift film is washed with hot water for 5 minutes or more. Mask blank. A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to claim 1. A method for manufacturing a mask blank in which a phase shift film is provided on a main surface of a translucent substrate,
Rotating the translucent substrate with a rotation axis passing through the center of the main surface; and disposing the sputtering surface of the sputtering target obliquely so as to face the main surface having the concave defect portion of the translucent substrate; A step of forming the phase shift film on a main surface having a concave defect portion of the light transmitting substrate by a sputtering method including:
The step of forming the position shift film includes a highly transmissive layer forming step of forming a highly transmissive layer on a main surface having a concave defect in the light transmissive substrate, and a light transmittance higher than that of the highly transmissive layer. Forming a low low transmission layer on the high transmission layer, and a low transmission layer forming step,
In the high transmission layer formed in the high transmission layer forming step, the internal region of the high transmission layer of the portion formed on the concave defect portion has a low density region, and the density in the low density region is The mask blank manufacturing method, wherein the density of the portion formed on the main surface without the concave defect portion is relatively lower than the density in the inner region of the high transmission layer. The high transmission layer forming step uses the sputtering target made of a material containing silicon, and forms the high transmission layer by reactive sputtering in a sputtering gas containing a nitrogen-based gas and a rare gas,
The low permeable layer forming step uses the sputtering target made of a material containing silicon, and includes a nitrogen-based gas and a rare gas, and has a lower mixing ratio of the nitrogen-based gas than in the highly permeable layer forming step. The method for producing a mask blank according to claim 12, wherein the low transmission layer is formed by reactive sputtering in the inside. The high transmission layer forming step uses the sputtering target made of a material containing one or more elements selected from silicon or a metalloid element and a nonmetal element in silicon, and in a sputtering gas containing a nitrogen-based gas and a rare gas. The high transmission layer is formed by reactive sputtering of
The low transmission layer forming step uses the sputtering target made of a material containing one or more elements selected from silicon or a metalloid element and a nonmetal element in silicon, and includes a nitrogen-based gas and a rare gas, and the high transmission layer 14. The mask blank according to claim 12, wherein the low-permeability layer is formed by reactive sputtering in a sputtering gas having a lower nitrogen-based gas mixing ratio than in the forming step. Method. The highly permeable layer forming step is to form the highly permeable layer by reactive sputtering in a sputtering gas composed of nitrogen gas and a rare gas, using the sputtering target composed of silicon.
The low transmission layer forming step uses the sputtering target made of silicon, and reactive sputtering in a sputtering gas made of nitrogen gas and a rare gas and having a lower nitrogen-based gas mixing ratio than in the high transmission layer forming step. The method of manufacturing a mask blank according to any one of claims 12 to 14, wherein the low transmission layer is formed by: The high transmission layer forming step is to form the high transmission layer by reactive sputtering in poison mode,
The method for manufacturing a mask blank according to any one of claims 12 to 15, wherein the low transmission layer forming step forms the low transmission layer by reactive sputtering in a metal mode. The uppermost layer forming step of forming an uppermost layer made of a material containing silicon and oxygen at a position farthest from the translucent substrate of the phase shift film. A method for producing a mask blank as described in 1. The phase shift film is selected from a material consisting of silicon and oxygen, a material consisting of silicon, nitrogen and oxygen, or a semi-metal element, a non-metal element, and a rare gas at a position farthest from the translucent substrate. The method for producing a mask blank according to claim 12, further comprising: an uppermost layer forming step of forming an uppermost layer formed of any one of the materials containing one or more elements. A method for producing a phase shift mask, comprising a step of forming a transfer pattern on the phase shift film of a mask blank produced by the method for producing a mask blank according to claim 12. A method of manufacturing a semiconductor device, comprising: using the phase shift mask according to claim 11, and exposing and transferring the transfer pattern of the phase shift mask to a resist film on a substrate. A step of exposing and transferring the transfer pattern of the phase shift mask to a resist film on a substrate using the phase shift mask manufactured by the method of manufacturing a phase shift mask according to claim 19. A method for manufacturing a semiconductor device.

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