JP6502143B2 - Mask blank, phase shift mask, method of manufacturing phase shift mask, and method of manufacturing semiconductor device - Google Patents

Description

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

  In general, in the process of manufacturing a semiconductor device, formation of a fine pattern is performed using a photolithography method. In addition, a number of transfer masks are usually used to form this fine pattern. In order to miniaturize the pattern of the semiconductor device, in addition to the refinement of the mask pattern formed on the transfer mask, it is necessary to shorten the wavelength of the exposure light source used in photolithography. In recent years, the exposure light source used at the time of semiconductor device manufacture has been shortened in wavelength from a KrF excimer laser (wavelength 248 nm) to an ArF excimer laser (wavelength 193 nm).

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

Patent Document 2 discloses a defect in which a black defect portion is etched and removed by supplying an electron beam to the black defect portion of the light shielding film while supplying xenon difluoride (XeF ₂ ) gas. A correction technique (hereinafter, such defect correction performed by irradiating charged particles such as electron beams is simply referred to as EB defect correction) is disclosed. Although this EB defect correction was originally used for black defect correction in the absorber film of a reflective mask for EUV lithography (Extreme Ultraviolet Lithography), it is also used in recent years for black defect correction of MoSi halftone masks. There is.

JP, 2010-217514, A Japanese Patent Publication No. 2004-537758

  In a halftone phase shift mask used in photolithography in which ArF excimer laser light is used as exposure light (hereinafter also referred to as ArF exposure light), a halftone phase shift film (hereinafter, simply referred to as “phase shift film”) is used. And a function of transmitting ArF exposure light with a predetermined transmittance, and a predetermined power between ArF exposure light transmitted through the phase shift film and light passing through the air by the same distance as the thickness of the phase shift film. The function of causing a phase difference (phase shift amount) is simultaneously determined. Heretofore, phase shift films having characteristics in which the transmittance to ArF exposure light is lower than 10% have been widely used, and it has been general that the phase shift amount be around 180 degrees. Single-layer structure (a single-layer structure including an area where surface oxidation can not be avoided; hereinafter, the single-layer structure includes an oxidation area in the surface layer except when mentioning in particular to the surface oxidation area) Of the phase shift film), and materials which can be formed with a thinner film thickness while satisfying simultaneously the conditions for the transmittance to the ArF exposure light as described above and the phase shift amount are relatively limited. ing. Materials made of molybdenum silicide nitride (MoSiN) satisfy these conditions and have been widely used.

  In recent years, in a halftone phase shift mask, a phase shift film with a high transmittance (a phase with a transmittance of 10% or more) for the purpose of obtaining a higher phase shift effect for transmitted light passing near the pattern edge. The demand for shift film is increasing. In the case of the conventional phase shift film having a single layer structure made of MoSiN, the content of molybdenum in the phase shift film is reduced, for example, in order to obtain a transmittance of 10% or more while securing a predetermined phase difference. A ratio [%] obtained by dividing the content [atomic%] of molybdenum in the phase shift film by the total content [atomic%] of molybdenum (Mo) and silicon (Si) (hereinafter, this ratio is “Mo / [Mo + Si The ratio must be 4% or less. However, when the content of molybdenum in the phase shift film is reduced, there arises a problem that the conductivity of the film is reduced. In addition, when the content of molybdenum in the phase shift film decreases, there is also a problem that the etching rate at the time of performing the above-mentioned EB defect correction on the black defect of the phase shift film is lowered.

A material used for the phase shift film is molybdenum silicide oxynitride (MoSiON). The single-layer phase shift film made of MoSiON is thicker than the single-layer phase shift film made of MoSiN, but even if the molybdenum content is relatively large (for example, Mo / [Mo + Si The transmittance can be 10% or more while securing a predetermined phase difference. However, in the case of the mask blank provided with the phase shift film of the single layer structure which consists of MoSiON, it became clear that there are the following problems.
When a black defect is found in a phase shift film in mask inspection when producing a phase shift mask from a mask blank, it is often corrected by EB defect correction. When a black defect of a phase shift film of a single layer structure made of MoSiON is corrected by EB defect correction, the detection of the etching end point for detecting the boundary between the phase shift film and the light transmitting substrate is made of MoSiN It has been newly found that it becomes more difficult than a single phase phase shift film.

  The present invention has been made to solve the above-described conventional problems, and in a mask blank provided with a high-transmittance phase shift film on a translucent substrate, the phase shift film secures a predetermined phase difference. However, even if it has an optical characteristic that makes the transmittance 10% or more, detection of the etching end point for detecting the boundary between the phase shift film and the light transmitting substrate at the time of EB defect correction is relatively easy. It aims at providing a mask blank which can perform EB defect correction with high accuracy by this. Another object of the present invention is to provide a high transmittance phase shift mask with few black defects, which is manufactured using this mask blank. Furthermore, it aims at providing a method of manufacturing such a phase shift mask. An object of the present invention is to provide a method of manufacturing a semiconductor device using such a phase shift mask.

In order to achieve the above-mentioned subject, the present invention has the following composition.
(Configuration 1)
A mask blank comprising a phase shift film on a light transmitting substrate,
The phase shift film has a function of transmitting exposure light of ArF excimer laser with a transmittance of 10% or more, and the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. And the function of causing a phase difference of not less than 150 degrees and not more than 190 degrees with the exposure light having passed through
The phase shift film is a composition gradient film made of a material containing metal, silicon, nitrogen and oxygen,
The ratio of the content of the metal to the total content of the metal and silicon in the phase shift film is 5% or more.
The oxygen content in the substrate side region of the phase shift film is 10 atomic% or less,
A mask blank, wherein the oxygen content in the region other than the substrate side region of the phase shift film is larger than the oxygen content in the substrate side region.

(Configuration 2)
The mask blank according to Configuration 1, wherein the substrate side region is a region ranging from the surface on the light transmitting substrate side to the opposite surface in the phase shift film to a thickness of 10 nm.

(Configuration 3)
The mask blank according to Configuration 1 or 2, wherein the phase shift film has an oxygen content of 10 atomic% or more in a 1/2 thickness region of the whole.

(Configuration 4)
4. The mask blank according to any one of constitutions 1 to 3, wherein the nitrogen content in the substrate side region of the phase shift film is 40 atomic% or more.

(Configuration 5)
4. The mask blank according to any one of the constitutions 1 to 4, wherein the oxygen content of the phase shift film increases from the surface on the translucent substrate side to the opposite surface.

(Configuration 6)
5. The mask blank according to any one of the constitutions 1 to 5, wherein the silicon content of the phase shift film decreases from the surface on the light transmitting substrate side to the opposite surface.

(Configuration 7)
The mask blank according to any one of the configurations 1 to 6, wherein the ratio of the content of the metal to the total content of the metal and silicon in the phase shift film is 15% or less.

(Configuration 8)
7. The mask blank according to any one of the configurations 1 to 7, wherein the phase shift film is formed in contact with the surface of the light transmitting substrate.

(Configuration 9)
8. The mask blank according to any one of the configurations 1 to 8, wherein the phase shift film has a thickness of 90 nm or less.

(Configuration 10)
The mask blank according to any one of the configurations 1 to 9, further comprising a light shielding film on the phase shift film.

(Configuration 11)
10. A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to Configuration 10, and a light shielding zone pattern is formed on the light shielding film.

(Configuration 12)
A method of manufacturing a phase shift mask using the mask blank according to Configuration 10, wherein
Forming a transfer pattern on the light shielding film by dry etching;
Forming a transfer pattern on the phase shift film by dry etching using a light shielding film having the transfer pattern as a mask;
Forming a light shielding zone pattern on the light shielding film by dry etching using a resist film having the light shielding zone pattern as a mask.

(Configuration 13)
11. A method of manufacturing a semiconductor device comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to Structure 11.

(Configuration 14)
A method of manufacturing a semiconductor device comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask manufactured by the method of manufacturing a phase shift mask according to Structure 12.

  The mask blank of the present invention is a mask blank provided with a phase shift film on a translucent substrate, and the phase shift film is a single-layer composition gradient film made of a material containing metal, silicon, nitrogen and oxygen. The ratio of the metal content to the total content of metal and silicon in the film is 5% or more, the oxygen content in the substrate side region is 10 atomic% or less, and the oxygen content in the region other than the substrate side region Is more than that. By forming a mask blank of such a structure, this phase shift film has a function of transmitting exposure light of ArF excimer laser with a transmittance of 10% or more, and a phase with respect to the exposure light transmitted through the phase shift film. A function to generate a phase difference of 150 degrees or more and 190 degrees or less with the exposure light having passed through the air by the same distance as the thickness of the shift film can be secured simultaneously. In addition, when this phase shift film is subjected to EB defect correction, detection of the etching end point for detecting the boundary between the phase shift film and the light transmitting substrate becomes easy, and the state of defect correction is insufficient. And it is possible to prevent the transparent substrate from being unintentionally dug up, and the accuracy of the EB defect correction is improved.

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

Hereinafter, each embodiment of the present invention will be described.
[Mask blank and its manufacture]
The inventors of the present invention have obtained a practically sufficient processing speed when EB defect correction is performed on a high transmittance type phase shift film of a single layer structure made of metal silicide oxynitride represented by MoSiON. Since the detection of the etching end point for detecting the boundary between the phase shift film and the light transmitting substrate is easy, as a result, intensive research has been conducted on the phase shift film and its composition which can correct EB defects with high accuracy. The phase shift film targeted in each embodiment of the present invention secures a predetermined phase difference (150 degrees or more and 190 degrees or less) and a high transmittance of 10% or more with respect to exposure light (ArF excimer laser light). Is a membrane that can The optical properties possessed by this phase shift film provide a high pattern edge enhancement effect, thereby improving the resolution and focus latitude when performing transfer using this phase shift mask. Further, by using a phase shift film having a single layer structure, the sidewall shape when forming a phase shift pattern by dry etching becomes better than a phase shift film having a laminated structure of two or more layers. Furthermore, by using a phase shift film having a single layer structure, the number of manufacturing steps can be reduced and the number of steps during film formation can be reduced as compared to a phase shift film having a laminated structure of two or more layers. The occurrence can be suppressed. For this reason, the defect correction target portion can be reduced.

  First, the optical requirement of the phase shift film required for the present invention will be described including the reason, and EB defect correction with high accuracy (end point detection at defect repair can be performed with high accuracy while satisfying the optical requirement) The material composition of the phase shift film which enables EB defect correction) will be described.

  The phase shift film is required to have a transmittance of 10% or more to ArF exposure light from an ArF excimer laser light source having a wavelength of 193 nm. As a result, since a light intensity distribution in which the vicinity of the pattern edge portion is more emphasized can be obtained compared to the conventional halftone phase shift mask, the resolution and focus latitude of the phase shift mask manufactured using this phase shift film Etc. transfer performance is improved.

  Although an unintended light intensity distribution called a subpeak is generated due to the interference between the diffracted light from the transfer pattern and the light transmitted through the field portion consisting of portions other than the transfer pattern, the transmittance of the phase shift film is generated. Is too high, the light intensity of the subpeak portion where this unintended light intensity distribution is generated becomes strong, and this becomes a defect and is transferred (this is called “subpeak transfer”). From the viewpoint of suppressing unintended subpeak transfer, the transmittance of the phase shift film to ArF exposure light is preferably 20% or less. Moreover, in order to ease the restriction of the pattern layout for preventing subpeak transfer, the transmittance of the phase shift film to ArF exposure light is preferably 15% or less.

  Furthermore, in order to obtain an appropriate phase shift effect, the phase shift film has a phase difference of 150 with the light which has passed through the air by the same distance as the thickness of the phase shift film, for the transmitted ArF exposure light. It is required to be adjusted to be within the range of not less than 190 degrees. The upper limit value of the phase difference in the phase shift film is more preferably 180 degrees or less. This is to reduce the influence of the increase in the phase difference due to minute etching of the light-transmissive substrate during dry etching when forming a pattern on the phase shift film. In addition, more and more exposure systems of ArF exposure light to the phase shift mask by the exposure apparatus in recent years are increasing the incidence of ArF exposure light from a direction inclined at a predetermined angle with respect to the vertical direction of the film surface It is also because

  In EB defect correction of a phase shift film made of metal silicide oxynitride, the three factors of the etching rate of metal silicide oxynitride and the etching rate difference between it and the light transmitting substrate and the etching end point detection accuracy are highly accurate. It is practically important in performing EB defect correction. Then, these characteristics need to be satisfied without losing the requirements for the transmittance and the phase difference required for the phase shift film described above.

  Here, as a metal element in the metal silicide oxynitride, a transition metal element is preferable. Although molybdenum (Mo) is widely used as a transition metal element contained in the phase shift film, it is not limited thereto. As a transition metal element contained in the phase shift film, tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V), zirconium ( And Zr), ruthenium (Ru), rhodium (Rh), zinc (Zn), niobium (Nb) and palladium (Pd), and any one or more metal elements can be mentioned. Moreover, as a metal element other than the transition metal element, aluminum (Al), indium (In), tin (Sn), gallium (Ga), etc. may be mentioned.

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

In EB defect correction of the phase shift film made of metal silicide oxynitride, fluorine-based gas (XeF ₂ , XeF ₄ , XeF ₆ , XeOF ₂ , XeOF ₄ , XeO ₂ F ₂ , XeO ₃ F ₂ , XeO ₂ F ₄ , ClF ₃ , ClF, BrF ₅ , BrF, IF ₃ , IF ₅ etc. can be applied, and in particular, XeF ₂ is supplied, while The black defect portion is etched and removed by irradiating the portion with an electron beam. The etching rate at this time is a ratio [%] (hereinafter, this ratio is “M / [,” the content [atomic%] of the metal (M) divided by the total content [atomic%] of the metal and silicon (Si). When the etching rate to this ratio is examined in detail, it depends on M + Si] ratio, and the M / [M + Si] ratio of the phase shift film consisting of metal silicide oxynitride is 5% or more. It was found that a sufficient etching rate was secured. In addition, it has been found that the etching selectivity with respect to the light-transmitting substrate containing silicon oxide as a main component can be sufficiently secured.

  It is effective to contain a predetermined amount or more of oxygen in order to give an optical characteristic that the transmittance to ArF exposure light is 10% or more while setting the M / [M + Si] ratio of the phase shift film to 5% or more. On the other hand, a translucent substrate such as synthetic quartz also contains silicon and oxygen as main components, and the constituent elements of both the phase shift film and the translucent substrate are in a relatively close state. Therefore, there is a problem that it is difficult to detect the etching end point even if any of the above-described etching end point detection methods is used in EB defect correction.

  In order to solve this problem, in the present embodiment, the composition gradient structure in which the oxygen content in the phase shift film is decreased on the light transmitting substrate side and is increased on the surface side opposite to the light transmitting substrate. I assume. The compositional gradient of the oxygen content is a distribution in which the oxygen content increases from the light transmitting substrate side which is the bottom of the phase shift film toward the surface side of the phase shift film in the phase shift film, particularly the oxygen content A monotonously increasing distribution (including the case where the increase in oxygen content is saturated near the surface layer portion) is preferable because it can increase the oxygen content of the phase shift film as a whole. When the oxygen content in the phase shift film and the oxygen content distribution were examined in detail, the substrate side region of the phase shift film (the base side portion and the base portion near the base portion where the phase shift film is in contact with the light transmitting substrate) 10 atomic% or less, preferably 5 atomic% or less, and more preferably less than the detection lower limit in order to detect the etching end point of EB defect correction with high accuracy. In the region other than the substrate side region of the phase shift film, it was found that the oxygen content in the substrate side region should be equal to or more than that. Here, from the viewpoint of reducing the film thickness of the phase shift film while detecting the etching end point with high accuracy, the thickness of the substrate side region serving as a reference for defining the region having an oxygen content of 10 atomic% or less is 10 nm. Is preferable, 15 nm is more preferable, and 20 nm is more preferable. When the film thickness of the phase shift film is made thin, it is effective in the formation of fine patterns on the photomask and in the reduction of bias (EMF bias) related to the electromagnetic field effect, and also defects due to pattern collapse on the mask are suppressed. The yield of the shift mask is improved. Here, the oxygen content in the substrate side region refers to the maximum value of the oxygen content across the entire substrate side region.

  With this structure, when determining the etching end point in EB defect correction, the oxygen content in the substrate side region in the phase shift film is small, so there is a clear difference from the light transmitting substrate having a high oxygen content. It becomes possible to detect the end point. On the other hand, a large amount of oxygen is contained in the phase shift film of a portion other than the substrate side region which does not affect the determination of the etching end point, whereby a phase shift satisfying a desired phase difference with high transmittance to ArF exposure light. It becomes possible to make a film.

  The content of silicon (Si) in the phase shift film is large on the side of the light transmitting substrate, and decreases toward the surface side opposite to the light transmitting substrate, particularly monotonically decreasing (when saturated near the surface) It is desirable to have a structure having a composition gradient to If the ratio of Si to O in the substrate side region of the phase shift film is significantly different from the ratio of Si to O in the light transmitting substrate, the determination of the etching end point in EB defect correction becomes easy. Also, as in the prior art, when the content of silicon (Si) is large throughout the phase shift film, the absorption of ArF exposure light becomes large, and the phase having a desired phase difference with a transmittance of 10% or more. It becomes difficult to construct a shift film. On the other hand, in the present embodiment, the content of silicon (Si) is decreased from the light transmitting substrate side toward the surface side, and as a whole, the content of silicon can be suppressed. It is possible to obtain a high transmittance of 10% or more for light.

  The phase shift film preferably has an oxygen content of 10 atomic% or more in the area of a half thickness of the whole. With this structure, even if the phase shift film is provided with a substrate side region with low transmittance of exposure light, the transmittance of the entire phase shift film to exposure light is 10% or more, and 150 for exposure light. It becomes easy to give the function to produce the phase difference within the range of not less than 190 degrees. The region of the phase shift film in which the oxygen content is 10 atomic% or more is more preferably 3⁄5, and more preferably 2⁄3 of the total thickness of the phase shift film. It is desirable to set the region in which the oxygen content in the phase shift film is 10 atomic% or more by the thickness from the surface side opposite to the light transmitting substrate. The oxygen content in this region refers to the minimum value of the oxygen content across the entire region.

  In order to make the phase shift film as thin as possible and control the transmittance and the phase difference to the exposure light to desired values, the extinction coefficient k and the refractive index n of the phase shift film to the exposure light are only oxygen (O). It is effective to contain nitrogen (N) so as to be larger than when containing. In particular, in the substrate side region of the phase shift film, it is preferable to adjust the component to lower the oxygen (O) content by increasing the content of nitrogen (N) to 40 atomic% or more, more preferably 45 atomic% or more. . Furthermore, when the content of nitrogen (N) in the substrate side region is large as described above, detection of the etching end point at the time of EB defect correction becomes easy. Further, in the region other than the substrate side region, the content of nitrogen (N) is preferably smaller than that in the substrate side region.

  Further, the M / [M + Si] ratio in the material forming the phase shift film is required to be at least 15% or less. If the M / [M + Si] ratio of the phase shift film is larger than 15%, the extinction coefficient of the phase shift film becomes too high, making it difficult to set the transmittance of the phase shift film to ArF exposure light to 10% or more Become. In addition, the ArF resistance of the phase shift film (the integrated irradiation amount resistance to ArF exposure light) also decreases.

  The phase shift film is a total of elements other than the main constituent elements in the phase shift film even when the material contains, in addition to metals, silicon, nitrogen and oxygen, elements other than these main constituent elements. It is acceptable if the content is in the range of 10 atomic% or less. Within this range, the optical characteristics of the phase shift film and the characteristics related to EB defect correction are small.

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

The translucent substrate 1 can be formed of quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.), etc. in addition to synthetic quartz glass. Among these, synthetic quartz glass is particularly preferable as a material for forming a light-transmissive substrate of a mask blank because it has high transmittance to ArF exposure light and sufficient rigidity not to cause deformation.

  The phase shift film 2 is preferably formed in contact with the surface of the translucent substrate 1. This is because it is preferable that there is no film (for example, a film of a chromium-based material) made of a material which is difficult to correct for the EB defect between the light transmitting substrate 1 and the phase shift film 2 at the EB defect correction.

The material of the phase shift film 2 is a metal silicide oxynitride having the above composition ratio.
The film thickness of the phase shift film 2 is preferably at least 90 nm or less. This is because EMF bias can be reduced by thinning the film. Therefore, the thickness of the phase shift film 2 is more preferably 85 nm or less, and more preferably 80 nm or less. Further, by making the film thickness of the phase shift film such a thin film, defects due to the pattern collapse on the mask are suppressed, and the yield of the phase shift mask is improved.

The refractive index and extinction coefficient of the phase shift film 2 generally have a distribution in the film thickness direction because they are materials with compositional gradients, but the phase shift film 2 has the above-described optical characteristics and film thickness. In order to satisfy the various conditions, it is desirable that the refractive index and the extinction coefficient be represented by an average value in the film thickness direction, and the values be within a predetermined range. Here, when the refractive index and extinction coefficient obtained by taking a simple average in the film thickness direction are referred to as average refractive index n _ave and average extinction coefficient k _ave , the exposure light of the phase shift film 2 (ArF The average refractive index n _ave for the exposure light) is preferably 1.9 or more as a lower limit value, and more preferably 2.0 or more. The upper limit value of the average refractive index n _ave of the phase shift film 2 is preferably 3.1 or less, and more preferably 2.7 or less. The lower limit value of the average extinction coefficient k _ave of the phase shift film 2 to ArF exposure light is preferably 0.26 or more, and more preferably 0.29 or more. The upper limit value of the average extinction coefficient k _ave of the phase shift film 2 is preferably 0.62 or less, and more preferably 0.54 or less.

The refractive index and extinction coefficient of the thin film including the phase shift film 2 are not determined only by the composition of the thin film. The film density and crystalline state of the thin film are also factors that influence the refractive index and extinction coefficient. Therefore, the conditions for forming a thin film by reactive sputtering are adjusted, and the thin film is formed to have a desired refractive index and extinction coefficient. In order to make the phase shift film 2 have a range of the above-mentioned refractive index n _ave and extinction coefficient k _ave , when forming a film by reactive sputtering, a rare gas and a reactive gas (oxygen gas, nitrogen gas, etc.) It is effective to adjust the ratio of mixed gas, but it is not limited thereto. When forming a film by reactive sputtering, the pressure, the electric power applied to the sputtering target, the positional relationship such as the distance between the target and the light-transmitting substrate 1, etc., are diverse. Further, these film forming conditions are specific to the film forming apparatus, and are appropriately adjusted so that the phase shift film 2 to be formed has desired refractive index n _ave and extinction coefficient k _ave .

  The phase shift film 2 is formed by sputtering, but sputtering is performed by appropriately changing the flow rate of an additive gas such as a reactive gas temporally, and the phase shift film 2 to be formed has the above-described composition inclination. Let Here, as the sputtering method, any sputtering method such as DC sputtering, RF sputtering and ion beam sputtering can be applied. From the viewpoint of controllability of the gradient composition, it is desirable to apply DC sputtering, and in the case of using a target with low conductivity, it is preferable to apply RF sputtering or ion beam sputtering. When the deposition rate is considered, it is preferable to apply RF sputtering.

  It is desirable that the phase shift film 2 has a layer having a higher oxygen content than the phase shift film of the portion excluding the surface layer (hereinafter, simply referred to as “surface oxide layer”). The phase shift film 2 having a layer with a high oxygen content in the surface layer is highly resistant to the cleaning process used in the mask manufacturing process and the mask cleaning used in the repeated use of the phase shift mask. Various oxidation treatments can be applied as a method of forming the surface oxide layer of the phase shift film 2. As this oxidation treatment, for example, heat treatment in a gas containing oxygen such as in the atmosphere, light irradiation treatment with a flash lamp or the like in a gas containing oxygen, treatment to bring ozone or oxygen plasma into contact with the uppermost layer, etc. It can be mentioned. In particular, it is preferable to form a surface oxide layer on the phase shift film 2 by using a heat treatment which simultaneously obtains an effect of reducing the film stress of the phase shift film 2 and a light irradiation process using a flash lamp or the like. The surface oxide layer of the phase shift film 2 preferably has a thickness of 1 nm or more, and more preferably 1.5 nm or more. The surface oxide layer of the phase shift film 2 preferably has a thickness of 5 nm or less, more preferably 3 nm or less.

The mask blank 100 includes the light shielding film 3 on the phase shift film 2. Generally, in the case of a binary transfer mask, the outer peripheral area of the area (transfer pattern forming area) where the transfer pattern is formed is exposed and transferred to a resist film on a semiconductor wafer using an exposure apparatus. It is required to secure an optical density (OD) equal to or greater than a predetermined value so that the resist film is not affected by the transmitted exposure light. In this respect, the same applies to the phase shift mask. Generally, in the outer peripheral region of the transfer mask including the phase shift mask, it is desirable that the OD be 3.0 or more, and at least 2.8 or more is required. The phase shift film 2 has a function of transmitting exposure light with a predetermined transmittance, and it is difficult to secure an optical density of a predetermined value required in the outer peripheral area by the phase shift film 2 alone. For this reason, it is necessary to laminate the light shielding film 3 for securing the insufficient optical density on the phase shift film 2 at the stage of manufacturing the mask blank 100. With such a configuration of the mask blank 100, while manufacturing the phase shift mask 200 (see FIG. 2), the light shielding film 3 in the area (basically the transfer pattern formation area) using the phase shift effect is used. If removed, it is possible to manufacture the phase shift mask 200 in which the optical density of the predetermined value is secured in the outer peripheral region.
The optical density OD is the intensity of light incident on the film in question when the I _0, the intensity of light having passed through the membrane was I,
OD = −log ₁₀ (I / I ₀ )
Defined by

  The light shielding film 3 may have any one of a single layer structure and a laminated structure of two or more layers. In addition, each layer of the light-shielding film having a single-layer structure and the light-shielding film having a laminated structure of two or more layers has a composition inclination in the thickness direction of the layer even if it has substantially the same composition in the thickness direction of the film or layer It may be a configuration.

  The mask blank 100 described in FIG. 1 has a configuration in which the light shielding film 3 is laminated on the phase shift film 2 without passing another film. In the light shielding film 3 in this configuration, it is necessary to apply a material having sufficient etching selectivity to the etching gas used when forming a pattern on the phase shift film 2.

  In this case, the light shielding film 3 is preferably formed of a material containing chromium. In addition to chromium metal, chromium (Cr) is selected from oxygen (O), nitrogen (N), carbon (C), boron (B) and fluorine (F) as a material containing chromium which forms the light shielding film 3 And materials containing one or more elements. Generally, chromium-based materials are etched with a mixed gas of chlorine-based gas and oxygen gas, but chromium metal does not have a very high etching rate for this etching gas. In view of enhancing the etching rate of the mixed gas of chlorine gas and oxygen gas to the etching gas, as a material for forming the light shielding film 3, one or more selected from chromium, oxygen, nitrogen, carbon, boron and fluorine Materials containing elements are preferred. In addition, one or more elements of molybdenum (Mo), indium (In) and tin (Sn) may be contained in the chromium-containing material forming the light shielding film. By containing one or more elements of molybdenum, indium and tin, the etching rate to the mixed gas of chlorine gas and oxygen gas can be made faster.

  The mask blank of the present invention is not limited to the one shown in FIG. 1, and another film (etching stopper film) may be interposed between the phase shift film 2 and the light shielding film 3. Good. In this case, it is preferable that the etching stopper film is formed of the above-described chromium-containing material, and the light shielding film 3 is formed of the silicon-containing material.

  The material containing silicon that forms the light shielding film 3 may contain a transition metal or may contain a metal element other than the transition metal. The pattern formed on the light shielding film 3 is basically the light shielding zone pattern of the outer peripheral area, and the integrated irradiation amount of ArF exposure light is smaller than that of the transfer pattern area, and the fine pattern is arranged in the outer peripheral area. Is rare, and even if ArF light resistance is low, no substantial problems occur. Further, when a transition metal is contained in the light shielding film 3, the light shielding performance is largely improved as compared with the case where the transition metal is not contained, and the thickness of the light shielding film 3 can be reduced. As a transition metal to be contained in the light shielding film 3, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V) And any one metal such as zirconium (Zr), ruthenium (Ru), rhodium (Rh), niobium (Nb), palladium (Pd) or an alloy of these metals.

  In the present embodiment, the hard mask film 4 stacked on the light shielding film 3 is formed of a material having etching selectivity to an etching gas used when the light shielding film 3 is etched. Thus, as described below, the thickness of the resist film can be made significantly thinner than when the resist film is used directly as a mask for the light shielding film 3.

  Since the light shielding film 3 needs to have a sufficient light shielding function by securing a predetermined optical density, there is a limit to the reduction of the thickness. On the other hand, it is sufficient for the hard mask film 4 to have a film thickness that can function as an etching mask until dry etching for forming a pattern in the light shielding film 3 immediately below it is completed, basically the optical surface Not subject to Therefore, the thickness of the hard mask film 4 can be made much thinner than the thickness of the light shielding film 3. The resist film of the organic material only needs to have a film thickness enough to function as an etching mask until dry etching for forming a pattern on the hard mask film 4 is completed. The thickness of the resist film can be made much thinner than in the case of using it directly as the third mask. Thus, since the resist film can be thinned, resist resolution can be improved and collapse of the formed pattern can be prevented. Thus, although it is preferable to form the hard mask film 4 laminated on the light shielding film 3 using the above-mentioned material, the present invention is not limited to this embodiment, and in the mask blank 100, the light shielding film A resist pattern may be directly formed on the surface 3 and the light shielding film 3 may be directly etched using the pattern as a mask.

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

In addition to the above, a material containing tantalum is also applicable as the material of the hard mask film 4 in the case where the light shielding film 3 is formed of a material containing chromium. The material containing tantalum in this case includes, in addition to tantalum metal, a material in which tantalum contains one or more elements selected from nitrogen, oxygen, boron and carbon. For example, Ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN etc. may be mentioned.
When the light shielding film 3 is formed of a material containing silicon, the hard mask film 4 is preferably formed of the above-described material containing chromium.

  In the mask blank 100, it is preferable that a resist film of an organic material be formed in a film thickness of 100 nm or less in contact with the surface of the hard mask film 4. In the case of a fine pattern corresponding to the DRAM hp 32 nm generation, a transfer pattern (phase shift pattern) to be formed on the hard mask film 4 may be provided with SRAF (Sub-Resolution Assist Feature) having a line width of 40 nm. Even in such a case, since the cross-sectional aspect ratio of the resist pattern is as low as 1: 2.5, collapse or peeling of the resist pattern at the time of development, rinse, etc. of the resist film is suppressed. In addition, since the film thickness of a resist film is 80 nm or less, since collapse and peeling of a resist pattern are further suppressed, it is more preferable.

[Phase shift mask and its manufacture]
The phase shift mask 200 of this embodiment is characterized in that a transfer pattern (phase shift pattern) is formed on the phase shift film 2 of the mask blank 100 and a light shielding band pattern is formed on the light shielding film 3. In the case of the configuration in which the hard mask film 4 is provided on the mask blank 100, the hard mask film 4 is removed during the production of the phase shift mask 200.

  The method for producing a phase shift mask according to the present invention uses the mask blank 100 described above, and the step of forming a transfer pattern on the light shielding film 3 by dry etching, and the light shielding film 3 having the transfer pattern Forming a transfer pattern on the phase shift film 2 by dry etching, and forming a light shielding zone pattern on the light shielding film 3 by dry etching using the resist film 6b having the light shielding zone pattern as a mask. And Hereinafter, the method for manufacturing the phase shift mask 200 of the present invention will be described according to the manufacturing steps shown in FIG. Here, a method of manufacturing the phase shift mask 200 using the mask blank 100 in which the hard mask film 4 is stacked on the light shielding film 3 will be described. Further, the case where a material containing chromium is applied to the light shielding film 3 and a material containing silicon is applied to the hard mask film 4 will be described.

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

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

  Next, a resist film is formed on the mask blank 100 by spin coating. Thereafter, on the resist film, a second pattern, which is a pattern to be formed on the light shielding film 3 (a light shielding zone pattern or a light shielding pattern including a light shielding zone) is exposed and drawn with an electron beam, and further predetermined processing such as development processing To form a second resist pattern 6b having a light shielding pattern (see FIG. 2E). Here, since the second pattern is a relatively large pattern, instead of exposure drawing using an electron beam, it is possible to use exposure drawing using a laser beam by a laser drawing apparatus with high throughput.

  Subsequently, dry etching using a mixed gas of chlorine gas and oxygen gas is performed using the second resist pattern 6b as a mask to form a second pattern (light shielding pattern 3b) on the light shielding film 3 (FIG. f) see). Further, the second resist pattern 6b is removed, and after predetermined processing such as cleaning, the phase shift mask 200 is obtained (see FIG. 2 (g)).

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

  The phase shift mask 200 of the present invention is manufactured using the mask blank 100 described above. Therefore, the phase shift film (phase shift pattern) on which the transfer pattern is formed has a transmittance of 10% or more to ArF exposure light, and the same distance as the thickness of the phase shift pattern and the exposure light transmitted through the phase shift pattern. The phase difference between the exposure light passing through the air and the exposure light is in the range of 150 degrees to 190 degrees, and a high phase shift effect can be produced. In addition, the etching end point can be detected relatively easily at the time of EB defect correction for the black defect found in the mask inspection performed in the process of manufacturing the phase shift mask 200.

[Manufacturing of semiconductor devices]
In the method of manufacturing a semiconductor device according to the present invention, a transfer pattern is exposed and transferred onto a resist film on a semiconductor substrate using the phase shift mask 200 manufactured using the phase shift mask 200 described above or the mask blank 100 described above. It is characterized by Since the phase shift mask 200 of the present invention produces a high phase shift effect, when the exposure transfer to the resist film on the semiconductor device is carried out using the phase shift mask 200 of the present invention, the design specification is sufficient for the resist film on the semiconductor device The pattern can be formed with the accuracy of filling. In addition, even when the black defect portion is exposed and transferred onto the resist film on the semiconductor device using the phase shift mask in which the black defect portion is corrected by EB defect correction in the process of manufacture, the pattern portion where the black defect of the phase shift mask existed. Can be prevented from occurring in the resist film on the semiconductor device corresponding to. Therefore, when the circuit pattern is formed by dry etching the film to be processed using this resist pattern as a mask, a highly accurate and high yield circuit pattern is formed without wiring shorts or disconnections caused by insufficient accuracy or transfer defects. be able to.

Hereinafter, embodiments of the present invention will be more specifically described by way of examples.
Example 1
[Manufacturing of mask blanks]
A translucent substrate 1 made of synthetic quartz glass having dimensions of the main surface of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. This light-transmissive substrate 1 is polished so that the end face and the main surface have a predetermined surface roughness or less (0.2 nm or less at the root-mean-square roughness Rq calculated in the inner region of one side of 1 μm). , And then subjected to predetermined cleaning treatment and drying treatment.

Next, the translucent substrate 1 is placed in a single-wafer DC sputtering apparatus, and a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 8 atomic%: 92 atomic%) is used, and argon is used. Molybdenum, silicon, nitrogen on the light-transmissive substrate 1 by reactive sputtering (DC sputtering) using a mixed gas of (Ar), nitrogen (N ₂ ), oxygen (O ₂ ) and helium (He) as a sputtering gas And a phase shift film 2 (MoSiON film) made of oxygen with a thickness of 74 nm. Here, the flow rate of oxygen gas was temporally changed such that the phase shift film 2 became a film having a desired compositional gradient. According to the above-described procedure, a single-layer phase shift film 2 having a composition gradient is formed in contact with the surface of the light-transmissive substrate 1 to a thickness of 74 nm.

Next, heat treatment is performed on the light-transmissive substrate 1 on which the phase shift film 2 is formed in order to reduce the film stress of the phase shift film 2 and to form an oxide layer having high cleaning resistance in the surface layer. went. Specifically, heat treatment was performed using a heating furnace (electric furnace) with the heating temperature set to 450 ° C. and the heating time set to 1 hour in the air. The phase shift film 2 was formed on the main surface of another light transmitting substrate 1 under the same conditions, and a heat treatment was performed.
The transmittance and phase difference of the phase shift film 2 for light of wavelength 193 nm were measured using a phase shift amount measuring apparatus (MPM 193 manufactured by Lasertec Corporation). The transmittance was 12%, and the phase difference was 176.2 degrees ( deg). Further, when the phase shift film 2 is analyzed by STEM (Scanning Transmission Electron Microscope) and EDX, it is confirmed that an oxide layer is formed with a thickness of about 2 nm from the surface of the phase shift film 2. The

Furthermore, the optical characteristics of the phase shift film 2 were measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). Although the refractive index n and the extinction coefficient k have a distribution with respect to the film thickness direction, the refractive index n _ave is 2.31 for a wavelength of 193 nm, represented by an average value obtained by taking a simple average with respect to the film thickness direction. The extinction coefficient k _ave was 0.41 (the refractive index and the extinction coefficient of each thin film described hereinafter were measured by the same spectroscopic ellipsometer).

  A phase shift film 2 is formed on another light transmitting substrate 1 in the same procedure as above, and the film composition of the phase shift film 2 is XPS (X-ray Photoelectron Spectroscopy). The measurement result was corrected (calibrated) to correspond to the measurement result of RBS (Rutherford Backscattering Spectrum).

  As a result, the elemental configuration of the phase shift film 2 was as follows. In the region (substrate side region) in the vicinity of the interface with the light-transmissive substrate 1 of the phase shift film 2, Mo is 2.8 atomic%, Si is 47.3 atomic%, O is 1.8 atomic%, and N is It was 48.1 atomic%. Mo is 2.8 at%, Si is 46.3 at%, O is in a region (substrate side region) located at a position of 9 nm from the light-transmissive substrate 1 side of the phase shift film 2 to the opposite surface (substrate side region) It was 5.0 atomic percent and N was 45.9 atomic percent. Mo is 2.8 at% and Si is 43.0 at% in a region (region other than the substrate side region) at a position of 40 nm from the light-transmissive substrate 1 side of the phase shift film 2 toward the opposite surface , O at 15.2 atomic percent and N at 39.0 atomic percent. In the region at the position excluding the surface layer due to the natural oxidation of the phase shift film 2 (the region at the position of 70 nm from the translucent substrate 1 side to the opposite surface, regions other than the substrate side region) .7 atomic percent, 39.8 atomic percent Si, 24.9 atomic percent O, and 32.6 atomic percent N;

  The composition was continuously inclined between the substrate side region and the top surface portion (the outermost surface portion excluding the surface layer portion) of the phase shift film 2. The substrate side region of the phase shift film 2 had an oxygen content of 10 at% or less in the entire region. Also, a region from the surface on the opposite side of the light transmitting substrate 1 side of the phase shift film 2 to a depth of 1⁄2 of the total thickness of the phase shift film 2 (that is, from the surface on the side on which the oxide layer is formed) In the region up to the depth of 37 nm, the oxygen content was 10 atomic% or more in the entire region. Mo / (Mo + Si) of the phase shift film 2 exceeded 5% in all regions of the phase shift film 2 excluding the surface layer due to natural oxidation.

Next, the light transmitting substrate 1 on which the phase shift film 2 is formed is placed in a single-wafer DC sputtering apparatus, and a chromium (Cr) target is used, and argon (Ar), carbon dioxide (CO ₂ ), nitrogen ( Reactive sputtering (DC sputtering) was performed using a mixed gas of N ₂ ) and helium (He) as a sputtering gas to form the bottom layer of the light shielding film 3 made of CrOCN with a thickness of 16 nm on the phase shift film 2 . The lowermost layer had a refractive index n of 2.29 and an extinction coefficient k of 1.00 for light of wavelength 193 nm. Next, reactive sputtering (DC sputtering) is performed using the same chromium (Cr) target and a mixed gas of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ) and helium (He) as sputtering gas. The lower layer of the light shielding film 3 made of CrOCN was formed to a thickness of 41 nm on the lowermost layer of the light shielding film 3. This lower layer had a refractive index n of 1.80 and a extinction coefficient k of 1.22 for light of wavelength 193 nm.

Next, reactive sputtering (DC sputtering) is performed using the same chromium (Cr) target and a mixed gas of argon (Ar) and nitrogen (N ₂ ) as the sputtering gas to form CrN on the lower layer of the light shielding film 3. The upper layer of the light shielding film 3 was formed to a thickness of 6 nm. This upper layer had a refractive index n of 1.51 and a extinction coefficient k of 1.60 for light of wavelength 193 nm. By the above method, a light shielding film 3 of chromium based material having a three-layer structure of the lowermost layer composed of CrOCN, the lower layer composed of CrOCN, and the lower layer composed of CrOCN from the phase shift film 2 side was formed in a total film thickness of 63 nm. The optical density (OD) at a wavelength of 193 nm in the laminated structure of the phase shift film 2 and the light shielding film 3 was 3.0 or more.

Furthermore, the light transmitting substrate 1 on which the phase shift film 2 and the light shielding film 3 are stacked is placed in a single wafer type RF sputtering apparatus, and a sputtering gas of argon (Ar) gas is used using a silicon dioxide (SiO ₂ ) target. Then, RF sputtering was performed to form a hard mask film 4 made of silicon and oxygen with a thickness of 5 nm on the light shielding film 3. By the above method, a mask blank 100 having a structure in which a single-layer phase shift film 2, 3 and a light shielding film 3 and a hard mask film 4 are laminated on a light transmitting substrate 1 was manufactured.

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

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

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

Next, a resist film made of a chemically amplified resist for electron beam writing was formed to a film thickness of 150 nm on the light shielding pattern 3a by spin coating. Next, a second pattern, which is a pattern to be formed on the light shielding film (a light shielding pattern including a light shielding zone pattern), is exposed and drawn on the resist film, and further predetermined processing such as development processing is performed. A second resist pattern 6b is formed (see FIG. 2 (e)). Subsequently, dry etching is performed using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) using the second resist pattern 6b as a mask to form a second pattern (a light shielding film 3). A light shielding pattern 3b) was formed (see FIG. 2 (f)). Furthermore, the second resist pattern 5b was removed, and after predetermined processing such as washing, a phase shift mask 200 was obtained (see FIG. 2 (g)).

When the mask pattern was inspected using the mask inspection apparatus with respect to the halftone phase shift mask 200 of Example 1 produced, black defects were confirmed in the phase shift pattern 2 a of the portion where the program defect was arranged. . When EB defect correction using an electron beam and XeF ₂ gas is performed on the black defect portion, the etching end point can be easily detected and etching on the surface of the light transmitting substrate 1 is minimized. It was possible.

When the halftone phase shift mask 200 of Example 1 after EB defect correction is exposed and transferred onto a resist film on a semiconductor device with exposure light of wavelength 193 nm using AIMS 193 (manufactured by Carl Zeiss) The simulation of the transferred image in When the exposure transfer image of this simulation was verified, the design specification was sufficiently satisfied. Also, the transferred image of the portion subjected to the EB defect correction was comparable to the transferred image of the other area.
From this result, even if the phase shift mask of Example 1 after EB defect correction is set on the mask stage of the exposure apparatus and exposure transfer is performed on the resist film on the semiconductor device, it is finally formed on the semiconductor device It can be said that the circuit pattern to be formed can be formed with high accuracy.

(Comparative example 1)
[Manufacturing of mask blanks]
The mask blank of Comparative Example 1 is an example in which the film composition of the phase shift film 2 is changed from that of Example 1, and was manufactured by the same method as that of Example 1 except for the phase shift film 2. The elements constituting the phase shift film 2 of Comparative Example 1 are the same as in Example 1, and consist of molybdenum, silicon, nitrogen and oxygen, and are films of a single layer structure (MoSiON film) as in Example 1. However, the film forming conditions were changed to change the component ratio (film composition) of the film, and a single layer film having uniform distribution without composition inclination in the film thickness direction was obtained. Specifically, the translucent substrate 1 is placed in a single wafer type DC sputtering apparatus, and a mixed sintering target of molybdenum (Mo) and silicon (Si) (Mo: Si = 4 atomic%: 96 atomic%) Consisting of molybdenum, silicon, nitrogen and oxygen by reactive sputtering (DC sputtering) using a mixed gas of argon (Ar), nitrogen (N ₂ ), oxygen (O ₂ ) and helium (He) as sputtering gas The phase shift film 2 was formed to a thickness of 66 nm. The material composition of the phase shift film 2 was adjusted by changing the gas flow rate etc. from that in the first embodiment.

  Further, the heat treatment was also performed on the phase shift film 2 under the same processing conditions as in Example 1. The phase shift film 2 of Comparative Example 1 was formed on the main surface of another light-transmissive substrate 1 under the same conditions, and a heat treatment was performed. The transmittance and phase difference of the light of wavelength 193 nm of the phase shift film 2 were measured using a phase shift amount measuring apparatus (MPM 193 manufactured by Lasertec Co., Ltd.). The transmittance was 12.1%, and the phase difference 177.1. Degree (deg). Further, when the phase shift film 2 was analyzed by STEM and EDX, it was confirmed that an oxide layer was formed with a thickness of about 1.7 nm from the surface of the phase shift film 2. Furthermore, when each optical characteristic of the phase shift film 2 was measured using a spectral ellipsometer for the phase shift film 2, the refractive index n is 2.48 and the extinction coefficient k is 0.45 for light of wavelength 193 nm. Met.

  Prepare a phase shift film formed on another translucent substrate in the same procedure as above, measure the film composition of the phase shift film by XPS, and make the measurement result correspond to the RBS measurement result Corrected (calibrated). As a result, the composition of the phase shift film in the portion excluding the surface oxide layer is 1.9 atomic% of Mo, 47.1 atomic% of Si, 16.1 atomic% of O, and 34.9 atomic% of N. %Met. Therefore, Mo / (Mo + Si) of the phase shift film 2 is 3.9%, and Si / O is 2.9. Also, no compositional gradient in the film thickness direction was observed in the portion of the phase shift film except for the oxidized layer.

  According to the above procedure, the phase shift film 2, the light shielding film 3 and the hard mask film 4 consisting of a single layer MoSiON film having a uniform composition in the film thickness direction are laminated on the light transmitting substrate 1 (synthetic quartz glass). The mask blank of Comparative Example 1 provided with the structure was manufactured.

[Production of phase shift mask]
Next, using the mask blank 100 of Comparative Example 1, a phase shift mask 200 of Comparative Example 1 was produced in the same manner as in Example 1.

  When the mask pattern inspection was performed on the halftone phase shift mask 200 of Comparative Example 1 by a mask inspection apparatus, black defects were confirmed in the phase shift pattern 2 a of the portion where the program defect was arranged. . When EB defect correction was performed on the black defect portion, it was difficult to detect the etching end point, and the etching progressed from the surface of the translucent substrate 1.

  When the halftone phase shift mask 200 of Comparative Example 1 after EB defect correction is exposed and transferred onto a resist film on a semiconductor device with exposure light of wavelength 193 nm using AIMS 193 (manufactured by Carl Zeiss) The simulation of the transferred image in When the exposure transfer image of this simulation was verified, the design specifications were generally satisfied sufficiently except for the portion where the EB defect correction was performed. However, the transferred image of the portion subjected to the EB defect correction was of a level at which a transfer failure occurs due to the influence of the etching on the translucent substrate 1 or the like. From this result, when the phase shift mask of Comparative Example 1 after EB defect correction is set on the mask stage of the exposure apparatus and exposed and transferred onto the resist film on the semiconductor device, it is finally formed on the semiconductor device. It is expected that disconnection or short circuit of the circuit pattern will occur in the circuit pattern.

DESCRIPTION OF SYMBOLS 1 translucent substrate 2 phase shift film 2 a phase shift pattern 3 light shielding film 3 a, 3 b light shielding pattern 4 hard mask film 4 a hard mask pattern 5 a first resist pattern 6 b second resist pattern 100 mask blank 200 phase shift mask

Claims (12)

A mask blank comprising a phase shift film on a light transmitting substrate,
The translucent substrate is formed of any glass selected from synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, and SiO ₂ -TiO ₂ glass,
The phase shift film is formed in contact with the surface of the light transmitting substrate,
The phase shift film has a function of transmitting exposure light of ArF excimer laser with a transmittance of 10% or more, and the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. And the function of causing a phase difference of not less than 150 degrees and not more than 190 degrees with the exposure light having passed through
The phase shift film is a composition gradient film made of a material containing metal, silicon, nitrogen and oxygen,
The ratio of the content of the metal to the total content of the metal and silicon in the phase shift film is 5% or more.
The oxygen content in the substrate side region of the phase shift film is 10 atomic% or less,
The oxygen content in the region other than the substrate-side region of the phase shift film, rather multi than the oxygen content in the substrate-side region,
The mask blank , wherein the substrate side region is a region ranging from a surface on the light transmitting substrate side in the phase shift film to a surface on the opposite side to a thickness of 10 nm . Wherein the phase shift film, a mask blank according to claim 1, wherein the oxygen content in the area of the entire half thickness is 10 atomic% or more. 3. The mask blank according to claim 1, wherein a nitrogen content in the substrate side region of the phase shift film is 40 atomic% or more. The mask blank according to any one of claims 1 to 3 , wherein the oxygen content of the phase shift film increases from the surface on the translucent substrate side to the opposite surface. The mask blank according to any one of claims 1 to 4 , wherein the silicon content of the phase shift film decreases from the surface on the light transmitting substrate side to the opposite surface. The mask blank according to any one of claims 1 to 5 , wherein a ratio of a content of the metal to a total content of the metal and silicon in the phase shift film is 15% or less. The mask blank according to any one of claims 1 to 6 , wherein the phase shift film has a thickness of 90 nm or less. The mask blank according to any one of claims 1 to 7 , further comprising a light shielding film on the phase shift film. A phase shift mask, wherein a transfer pattern is formed on the phase shift film of the mask blank according to claim 8, and a light shield zone pattern is formed on the light shield film. A method of manufacturing a phase shift mask using the mask blank according to claim 8 , wherein
Forming a transfer pattern on the light shielding film by dry etching;
Forming a transfer pattern on the phase shift film by dry etching using a light shielding film having the transfer pattern as a mask;
Forming a light shielding zone pattern on the light shielding film by dry etching using a resist film having the light shielding zone pattern as a mask. A method of manufacturing a semiconductor device comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to claim 9 . A method of manufacturing a semiconductor device, comprising: a step of exposing and transferring a transfer pattern on a resist film on a semiconductor substrate using the phase shift mask manufactured by the method of manufacturing a phase shift mask according to claim 10 .

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