JP4206940B2 - Phase shift mask blank, phase shift mask, and method of manufacturing phase shift mask blank - Google Patents

Description

  The present invention relates to a phase shift mask blank and a phase shift mask used in the manufacture of semiconductor integrated circuits and the like, and a method of manufacturing a phase shift mask blank, and in particular, a halftone phase that attenuates light having an exposure wavelength by a phase shift film. The present invention relates to a shift mask, a phase shift mask blank used therefor, and a manufacturing method thereof.

  Photomasks used in a wide range of applications including the manufacture of semiconductor integrated circuits such as ICs, LSIs, and VLSIs are basically photomasks having a light-shielding film containing chromium as a main component on a light-transmitting substrate. A predetermined pattern is formed on the light shielding film of the blank by applying a photolithographic method and using ultraviolet rays, electron beams, or the like. In recent years, along with market demands such as higher integration of semiconductor integrated circuits, pattern miniaturization has progressed rapidly, and this has been dealt with by shortening the exposure wavelength. However, while shortening the exposure wavelength improves the resolution, there is a problem in that the depth of focus is reduced, process stability is lowered, and product yield is adversely affected.

There is a phase shift method as an effective pattern transfer method for such a problem, and a phase shift mask is used as a mask for transferring a fine pattern.
For example, as shown in FIGS. 9A and 9B, the phase shift mask (halftone type phase shift mask) includes a phase shifter portion b that forms a pattern portion on the mask, and a phase shifter of the phase shifter. It consists of the part a where the non-existing substrate is exposed, and by setting the phase difference of the light transmitted through both to about 180 °, the light intensity at the interference part becomes zero due to the interference of the light at the pattern boundary part. The contrast of the transferred image can be improved. In addition, by using the phase shift method, it becomes possible to increase the depth of focus for obtaining the necessary resolution, compared with the case of using a normal mask having a general light-shielding pattern made of a chromium film or the like. It is possible to improve the resolution and the margin of the exposure process.

  The phase shift mask can be roughly divided into a practically transmissive phase shift mask and a halftone phase shift mask depending on the light transmission characteristics of the phase shifter. The completely transmissive phase shift mask is a mask that has a light transmittance of the phase shifter portion equivalent to that of the substrate exposed portion and is transparent to the exposure wavelength. In the halftone phase shift mask, the light transmittance of the phase shifter portion is about several percent to several tens percent of the substrate exposed portion.

  FIG. 1 shows a halftone phase shift mask blank, and FIG. 2 shows a basic structure of a halftone phase shift mask. The halftone phase shift mask blank of FIG. 1 is obtained by forming a halftone phase shift film 2 on almost the entire surface of a transparent substrate 1. The halftone phase shift mask of FIG. 2 is obtained by patterning the phase shift film 2 and includes a phase shifter portion 2a that forms a pattern portion on the substrate 1 and a substrate exposed portion 1a that does not have a phase shifter. . Here, the light transmitted through the phase shifter portion 2a is phase-shifted with respect to the light transmitted through the substrate exposed portion 1a, and the transmittance of the phase shifter portion 2a has a light intensity that is not sensitive to the resist on the transfer substrate. Is set. Therefore, it has a light shielding function that substantially blocks exposure light.

  As the halftone phase shift mask, there is a single-layer halftone phase shift mask that has a simple structure and is easy to manufacture. As this single-layer halftone phase shift mask, a mask having a phase shifter made of a MoSi-based material such as MoSiO, MoSiON or the like described in JP-A-7-140635 (Patent Document 1) has been proposed. .

  What is important in such a phase shift mask blank used for such a phase shift mask is that it satisfies optical characteristics such as transmittance, reflectance and refractive index at the exposure wavelength to be used, and is an etched cross section at the time of mask pattern formation. The shape and low defects must be realized.

  However, since the film composition of the single-layer halftone phase shift film is uniquely determined when the optical characteristics are set to a desired value, it is possible to obtain a phase shift film satisfying other required characteristics. It was difficult.

JP-A-7-140635

  The present invention has been made in order to solve the above-described problems. A phase shift mask blank having an excellent etching cross-sectional shape at the time of mask pattern formation, a phase shift mask using the same, and the optical characteristics described above are satisfied. It aims at providing the manufacturing method of a phase shift mask blank.

  As a result of intensive studies in order to solve the above problems, the present inventor has obtained a phase shift mask blank comprising a phase shift film composed of two or more layers on a transparent substrate. The composition having a zirconium silicide compound as a main component and the substrate side having a composition having a molybdenum silicide compound as a main component, and forming at least one film having a gently inclined composition, satisfying optical characteristics, It has been found that a phase shift mask blank and a phase shift mask having an excellent etch cross-sectional shape when forming a mask pattern can be obtained.

  That is, the present inventors have found that it is effective to combine a zirconium silicide compound film and a molybdenum silicide compound film as a structure excellent in chemical resistance and having a sufficiently small step in the etch cross section. However, the composition range of the zirconium silicide compound film and the molybdenum silicide compound film required to eliminate the step in the etched cross section is limited (ratio of zirconium concentration [Zr] to molybdenum concentration [Mo] [Zr] / [Mo] Therefore, in order to positively improve the cross-sectional shape (inclination angle of the cross-section) of the etch pattern, it is further desired to solve the problem that the degree of freedom is small. It was.

  In order to solve this problem, by continuously changing the composition of the zirconium silicide compound film and the molybdenum silicide compound film, there is no step in the etched cross section, the chemical resistance is excellent, and the etched cross sectional shape, in particular, the inclination It has been found that a phase shift film having an optimum angle can be obtained, and the present invention has been made.

Accordingly, the present invention provides the following phase shift mask blank, phase shift mask, and method for manufacturing the phase shift mask blank.
Claim 1:
In the phase shift mask blank in which a phase shift film composed of two or more layers is provided on a transparent substrate, the phase shift film has a surface layer composed mainly of a zirconium silicide compound, and the substrate side is composed of a molybdenum silicide compound. It is a composition having a main component, and between the at least one layer and another adjacent layer having a different composition, has a layer whose composition is gently inclined from the one layer composition to the other layer composition. Feature phase shift mask blank.
Claim 2:
An intermediate layer having a gentle gradient from the surface layer composition to the substrate side composition was interposed between the surface layer having a composition mainly composed of zirconium silicide compound and the substrate side layer having a composition mainly composed of molybdenum silicide compound. The phase shift mask blank according to claim 1.
Claim 3:
The surface layer having a composition mainly composed of a zirconium silicide compound is composed of a film mainly composed of a compound of zirconium silicide and oxygen and / or nitrogen, and the substrate side layer having a composition mainly composed of a molybdenum silicide compound is composed of molybdenum silicide. The phase shift mask blank according to claim 1 or 2, comprising a film mainly composed of an oxygen and / or nitrogen compound.
Claim 4:
2. A chrome-based light-shielding film or a chrome-based antireflection film, or a multi-layer film in which one or more of these chrome-based light-shielding films and chrome-based antireflection films are laminated on the phase shift film. , 2 or 3 phase shift mask blank.
Claim 5:
Using a sputtering film forming apparatus provided with a molybdenum silicide target, a zirconium silicide target, and, if necessary, a silicon target in one chamber, performing sputtering film formation using a sputtering gas containing at least oxygen and / or nitrogen, The method of manufacturing a phase shift mask blank according to any one of claims 1 to 4, wherein a phase shift film having an inclined composition is formed by changing a combination of electric power applied to a plurality of targets.
Claim 6:
The phase shift mask of any one of claims 1 to 4, wherein the phase shift film of the phase shift mask blank is patterned.

  In this case, according to the present invention, in the phase shift mask blank in which a phase shift film composed of two or more layers is provided on a transparent substrate, the phase shift film has a composition whose surface layer is mainly composed of a zirconium silicide compound. The substrate side has a composition containing a molybdenum silicide compound as a main component, and at least one layer having a gently inclined composition is formed, so that the etch cross-sectional shape at the time of mask pattern formation is satisfied while satisfying optical characteristics. An excellent phase shift mask blank and phase shift mask can be obtained.

  Furthermore, by forming a chromium-based light-shielding film or a chromium-based antireflection film on the phase shift film, or a multi-layer film in which one or more of these layers are laminated, a combination of these layers enables more precise patterning. Therefore, it is possible to sufficiently cope with further miniaturization and higher integration of the semiconductor integrated circuit.

  According to the present invention, it is possible to manufacture a phase shift mask having an improved etch cross-sectional shape when forming a mask pattern by adopting the above configuration.

Hereinafter, the present invention will be described in more detail.
As shown in FIG. 1, the phase shift mask blank of the present invention has a composition in which the surface layer is composed mainly of a zirconium silicide compound on a transparent substrate 1 through which exposure light such as quartz and CaF ₂ is transmitted, and the substrate side is molybdenum silicide. The phase shift film 2 is formed with a composition containing a compound as a main component and the composition is gently inclined. Further, the phase shift mask of the present invention is formed by patterning the phase shift film of the phase shift mask blank, and as shown in FIG. 2, the space between the patterned phase shifter portions is the first light transmitting portion (substrate). The exposed portion) 1a and the patterned phase shift film (phase shifter portion) 2 become the second light transmitting portion 2a.

  The layer mainly composed of the zirconium silicide compound is disposed on the surface layer for improving chemical resistance, and the layer mainly composed of the molybdenum silicide compound is composed of the zirconium silicide in order to satisfy the optical characteristics. It is provided on the substrate side of the silicide compound layer.

  Here, when the zirconium concentration of the zirconium silicide compound film is lowered, the amount of side etching in the surface layer portion increases during dry etching, and conversely, when the zirconium concentration is increased, the side etching amount of the surface layer portion decreases. . For example, when the inclination of the etched cross section spreads toward the surface layer, the cross-sectional shape can be corrected vertically by increasing the zirconium concentration in the surface layer portion. Further, since the composition is gently inclined from the surface layer toward the substrate side, there is no step in the etched cross section.

  The zirconium concentration [Zr] in the surface layer portion where the zirconium concentration is highest is 0.1 to 2 (molar ratio [Zr] / [Mo]) of the molybdenum concentration [Mo] on the substrate side where the molybdenum concentration is highest. It is desirable to be. More desirably, it is set to satisfy [Zr] / [Mo] = 0.2 to 1.5.

  Here, the zirconium silicide compound is preferably an oxide, nitride, or oxynitride, and similarly, the molybdenum silicide compound is preferably an oxide, nitride, or oxynitride. The phase shift mask blank is formed on a transparent substrate by a reactive sputtering method using a sputtering gas containing an oxygen source gas and / or a nitrogen source gas, and has a transmittance of several% to several tens% for exposure light ( In particular, it is preferably 3 to 40%), and an oxide of a metal silicide having a phase difference of 180 ° ± 5 ° with respect to the light transmitted through the phase shifter portion only with respect to the light transmitted through the transparent substrate, A phase shift film (phase shift multilayer film) formed of nitride or oxynitride is preferable.

  The manufacturing method of such a phase shift film will be described in more detail. First, a necessary number of molybdenum silicide targets, zirconium silicide targets, and, if necessary, silicon targets are attached in one sputter chamber. Here, a plurality of targets are simultaneously discharged and sputtered, and film formation is performed while synthesizing film components scattered from each target, thereby obtaining a desired film composition (generally referred to as “co-sputter”). It is desirable to rotate the substrate so that the film components from the respective targets are uniformly mixed. At this time, a desired gradient composition layer is obtained by adjusting the discharge power applied to each target.

  In the present invention, the sputtering method may be one using a DC power source or one using a high frequency power source, and may be a magnetron sputtering method or a conventional method.

  The composition of the sputtering gas is appropriately determined so that the phase shift film to be formed has a desired composition, such as an inert gas such as argon or xenon, and nitrogen gas, oxygen gas, various nitrogen oxide gases, or carbon oxide gas. A film is formed by addition.

  In this case, when it is desired to increase the transmittance of the phase shift film to be formed, a method of increasing the amount of oxygen or nitrogen containing gas added to the sputtering gas so that a large amount of oxygen and nitrogen is taken into the film, sputtering target It can be prepared by a method using a target to which a large amount of oxygen or nitrogen is previously added. Specifically, in the case of forming molybdenum silicide oxynitride (MoSiON) on the substrate side, molybdenum silicide is used as a target, and reactive sputtering is performed using a sputtering gas containing argon gas, nitrogen gas, and oxygen gas as sputtering gases. It is preferable to do.

  Further, when a surface layer of zirconium silicide oxynitride (ZrSiON) is formed, it is preferable to use zirconium silicide as a target and perform reactive sputtering with a sputtering gas containing argon gas, nitrogen gas, and oxygen gas as sputtering gases. .

  Here, in the present invention, the MoSiO film composition is preferably Mo = 0.2 to 25 atomic%, Si = 10 to 33 atomic%, O = 33 to 60 atomic%, and the MoSiN film composition is Mo = It is preferable that they are 0.2-25 atomic%, Si = 10-42 atomic%, N = 37-57 atomic%, and MoSiON film composition is Mo = 0.2-25 atomic%, Si = 10-42 atomic%. %, O = 1 to 60 atomic%, and N = 5 to 57 atomic%.

  The ZrSiO film composition is preferably Zr = 0.02 to 25 atomic%, Si = 10 to 33 atomic%, and O = 42 to 67 atomic%, and the ZrSiN film composition is Zr = 0.02 to 25 Atomic%, Si = 10 to 33 atomic%, and N = 42 to 67 atomic% are preferable. The composition of the ZrSiON film is Zr = 0.02 to 25 atomic%, Si = 10 to 57 atomic%, and O = 1. It is preferable that ˜60 atomic% and N = 5 to 57 atomic%.

  Further, when a layer having a gently inclined composition is interposed as an intermediate layer between the MoSi compound film on the substrate side and the ZrSi compound film on the surface layer, the composition of the intermediate layer is the same as the composition of the MoSi compound film on the substrate side and the surface layer. The composition has an intermediate composition with respect to the ZrSi compound film composition. However, the gentle inclination of the composition may mean that the composition may change continuously or stepwise. In the latter case, The composition changed from the substrate-side composition to the surface layer composition in 5 steps or more, particularly in 10 to 50 steps (for example, the amount of Mo is decreased in 5 steps or more, particularly in 10 to 50 steps and / or the Zr amount is 5 steps). As described above, it means that the number of times increases in particular in 10 to 50 steps.

  Here, such a tilted layer can be obtained by adjusting the discharge power for the target, but by changing the discharge power for the target continuously, the slope of the composition changes substantially continuously. A film is obtained, and a gradient film whose composition changes stepwise is obtained by changing the discharge power stepwise or intermittently.

  In the present invention, the thickness of the layer on the substrate side is preferably 20 to 1000 mm, particularly preferably 40 to 600 mm, the thickness of the surface layer is preferably 20 to 1000 mm, particularly 40 to 600 mm, and the gradient film The thickness of the phase shift film is 200 to 1000 mm, particularly 300 to 1000 mm, and is 1/2 to 1/1, particularly 1 / 1.5 to 1/1 of the thickness of the surface layer. This is preferable in that the shape can be appropriately controlled.

  In the present invention, as shown in FIG. 3, a chromium-based light-shielding film 3 is provided on the phase shift film 2, or a chromium-based material that reduces reflection from the chromium-based light-shielding film 3 as shown in FIG. The antireflection film 4 can also be formed on the chromium-based light shielding film 3. Further, as shown in FIG. 5, the phase shift film 2, the first chromium-based antireflection film 4, the chromium-based light-shielding film 3, and the second chromium-based antireflection film 4 ′ are formed in this order from the substrate 1 side. You can also. In this case, it is preferable to use chromium oxycarbide (CrOC), chromium oxynitride carbide (CrONC), or a laminate thereof as the chromium-based light-shielding film or the chromium-based antireflection film.

  Such a chromium-based light-shielding film or chromium-based antireflection film uses a target obtained by adding chromium alone or oxygen, nitrogen, carbon, or a combination thereof to an inert gas such as argon or krypton. The film can be formed by reactive sputtering using a sputtering gas to which carbon dioxide gas or the like is added as a carbon source.

Specifically, in the case of forming a CrONC film, as a sputtering gas, a gas containing carbon such as CH ₄ , CO ₂ and CO, a gas containing nitrogen such as NO, NO ₂ and N ₂ , and CO ₂ , NO, O _2, or other gases containing oxygen can be introduced, or a gas obtained by mixing an inert gas such as Ar, Ne, Kr, etc., can be used. In particular, it is preferable to use CO ₂ gas as the carbon source and oxygen source gas from the viewpoint of uniformity in the substrate surface and controllability during production. As an introduction method, various sputtering gases may be separately introduced into the chamber, or some gases may be combined or all gases may be mixed and introduced.

  In the CrOC film, Cr is 20 to 95 atomic%, particularly 30 to 85 atomic%, C is 1 to 30 atomic%, particularly 5 to 20 atomic%, and O is 1 to 60 atomic%, particularly 5 to 50 atomic%. In addition, the CrONC film has a Cr of 20 to 95 atomic%, particularly 30 to 80 atomic%, C of 1 to 20 atomic%, particularly 2 to 15 atomic%, O of 1 to 60 atomic%, In particular, 5 to 50 atom%, N is preferably 1 to 30 atom%, and particularly preferably 3 to 20 atom%.

  The phase shift mask of the present invention is obtained by patterning the phase shift film of the phase shift mask blank obtained as described above.

  Specifically, when the phase shift mask as shown in FIG. 2 is manufactured, as shown in FIG. 6A, after the phase shift multilayer film 12 is formed on the substrate 11 as described above. Then, a resist film 13 is formed, and the resist film 13 is patterned by a lithography method as shown in FIG. 6B, and further, the phase shift multilayer film 12 is etched as shown in FIG. 6C. Then, as shown in FIG. 6D, a method of removing the resist film 13 can be employed. In this case, application of the resist film, patterning (exposure, development), etching, and removal of the resist film can be performed by known methods.

  When a chromium-based light-shielding film and / or a chromium-based antireflection film (chromium-based film) is formed on the phase shift multilayer film, the light-shielding film and / or antireflection film in an area necessary for exposure is removed by etching. Then, after the phase shift film is exposed on the surface, the phase shift film is patterned in the same manner as described above to obtain a phase shift mask in which the chromium-based light shielding film 3 remains on the outer peripheral edge of the substrate as shown in FIG. Can do. In addition, a resist is applied on the chromium-based film, patterning is performed, the chromium-based film and the phase shift film are patterned by etching, and only the chromium-based film in a region necessary for exposure is removed by selective etching, A phase shift mask can also be obtained by exposing the phase shift pattern to the surface.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Example 1]
For forming the phase shift multilayer film, a DC sputtering apparatus provided with two targets 22a and 22b as shown in FIG. 8 was used. MoSi ₄ was used as the molybdenum silicide compound film target 22a, and ZrSi ₆ target was used as the zirconium silicide compound film target 22b.

On the quartz substrate, first, a discharge power of 1000 W was applied to the MoSi ₄ target to start sputtering film formation. At the same time as the film formation progressed, the discharge power of the MoSi ₄ target was gradually reduced. On the other hand, at the same time when the discharge by the MoSi ₄ target was started, the discharge power was gradually applied to the ZrSi ₆ target. When the film thickness was 700 mm, the electric power of each target was adjusted so that the discharge power of the MoSi ₄ target was 0 W and the discharge power of the ZrSi ₆ target was 500 W.

As a sputtering gas at this time, a mixed gas of Ar = 20 cm ³ / min, N ₂ = 100 cm ³ / min, and O ₂ = 5 cm ³ / min was introduced. The gas pressure during sputtering was set to 0.2 Pa. Furthermore, the substrate rotation speed was 30 rpm.

  When the film thickness reached 750 mm, the film formation was terminated to obtain a phase shift film. The following items were evaluated for the shift film. Note that the Mo concentration [Mo] and the Zr concentration [Zr] in the target were compared as approximate guidelines for the Mo concentration and the Zr concentration of the substrate-side film composition and the surface layer film composition. Under the experimental conditions, [Zr] / [Mo] = 0.714.

Changes in transmittance were measured when immersed in a chemical solution (23 ° C.) of chemical-resistant ammonia water: hydrogen peroxide solution: water 1: 1: 10 (volume ratio) for 1 hour. Those excellent in chemical resistance are considered to have less change in transmittance before and after immersion in the chemical solution. The measurement wavelength was 193 nm. As a result, the rate of change in transmittance before and after immersion in the chemical solution was 0.014.

Step and shape of etched cross section A resist film 13 is formed on the phase shift film obtained under the above conditions as shown in FIG. 6A, and the resist film 13 is formed as shown in FIG. After patterning and further dry etching the phase shift multilayer film 12 as shown in FIG. 6 (C), the resist film 13 was peeled off as shown in FIG. 6 (D). Note that gas containing CF ₄ as a main component was used for dry etching.

  When the cross section of the obtained pattern was observed and the step of the etched cross section (step shown by 14 in FIG. 10) generated at the interface between the surface layer film 2b of the phase shift film and the lower layer film 2c of the phase shift film was measured, No significant step was observed. Further, the angle θ of the etched cross section shown in FIG. 11 was 86 deg.

[Example 2]
A DC sputtering apparatus provided with two targets as shown in FIG. 8 was used for forming the phase shift multilayer film. MoSi ₄ was used as the target for the molybdenum silicide compound film, and ZrSi ₄ target was used as the target for the zirconium silicide compound film.

On the quartz substrate, first, a discharge power of 1000 W was applied to the MoSi ₄ target to start sputtering film formation, and simultaneously with the progress of film formation, the discharge power of the MoSi ₄ target was gradually reduced. On the other hand, at the same time when the discharge by the MoSi ₄ target was started, the discharge power was gradually applied to the ZrSi ₄ target. The power adjustment of each target was performed so that the discharge power of the MoSi ₄ target was 0 W and the discharge power of the ZrSi ₄ target was 500 W when the film thickness of the film was 650 Å.

As a sputtering gas at this time, a mixed gas of Ar = 20 cm ³ / min, N ₂ = 100 cm ³ / min, and O ₂ = 5 cm ³ / min was introduced. The gas pressure during sputtering was set to 0.2 Pa. Furthermore, the substrate rotation speed was 30 rpm.

  When the film thickness reached 700 mm, the film formation was finished to obtain a phase shift film. Note that the Mo concentration [Mo] and the Zr concentration [Zr] in the target were compared as approximate guidelines for the Mo concentration and the Zr concentration of the substrate-side film composition and the surface layer film composition. Under the experimental conditions, [Zr] / [Mo] = 1.00.

  As a result of evaluating chemical resistance in the same manner as in Example 1, the rate of change in transmittance before and after immersion in the chemical solution was 0.009, and no clear step was observed for the step in the etched cross section. It was 88 deg.

[Example 3]
A DC sputtering apparatus provided with two targets as shown in FIG. 8 was used for forming the phase shift multilayer film. MoSi ₄ was used as the target for the molybdenum silicide compound film, and ZrSi ₂₀ target was used as the target for the zirconium silicide compound film.

On the quartz substrate, first, a discharge power of 1000 W was applied to the MoSi ₄ target to start sputtering film formation, and simultaneously with the progress of film formation, the discharge power of the MoSi ₄ target was gradually reduced. On the other hand, at the same time when the discharge by the MoSi ₄ target was started, the discharge power was gradually applied to the ZrSi ₂₀ target. When the film thickness was 800 mm, the electric power of each target was adjusted so that the discharge power of the MoSi ₄ target was 0 W and the discharge power of the ZrSi ₂₀ target was 500 W.

As a sputtering gas at this time, a mixed gas of Ar = 20 cm ³ / min, N ₂ = 100 cm ³ / min, and O ₂ = 5 cm ³ / min was introduced. The gas pressure during sputtering was set to 0.2 Pa. The substrate rotation speed was 30 rpm.

  When the film thickness reached 850 mm, the film formation was terminated and a phase shift film was obtained. Note that the Mo concentration [Mo] and the Zr concentration [Zr] in the target were compared as approximate guidelines for the Mo concentration and the Zr concentration of the substrate-side film composition and the surface layer film composition. Under the experimental conditions, [Zr] / [Mo] = 0.238.

  As a result of evaluating chemical resistance in the same manner as in Example 1, the rate of change in transmittance before and after immersion in the chemical solution was 0.008, and no clear step was observed for the step in the etched section, and the angle θ of the etched section was It was 92 deg.

[Comparative Example 1]
A DC sputtering apparatus provided with two targets as shown in FIG. 8 was used. In this comparative example, only MoSi ₄ was used as the target for the molybdenum silicide compound film.

On the quartz substrate, a discharge power of 1000 W was applied to the MoSi ₄ target, and sputter film formation was performed while rotating the substrate at 30 rpm to provide a film having a thickness of 500 mm. As a sputtering gas at this time, a mixed gas of Ar = 20 cm ³ / min, N ₂ = 100 cm ³ / min, and O ₂ = 5 cm ³ / min was introduced. The gas pressure during sputtering was set to 0.2 Pa.

  As a result of evaluating chemical resistance in the same manner as in Example 1, the rate of change in transmittance before and after immersion in the chemical solution was 0.110, which was not sufficient chemical resistance. As for the step of the etched cross section, in the present comparative example, since it is a molybdenum silicide single layer film, no particularly problematic step was observed, but the angle θ of the etched cross section was 76 deg. It couldn't be said.

[Comparative Example 2]
A DC sputtering apparatus provided with two targets as shown in FIG. 8 was used for forming the phase shift multilayer film. MoSi ₄ was used as the target for the molybdenum silicide compound film, and ZrSi ₄ target was used as the target for the zirconium silicide compound film.

First, a discharge power of 1000 W was applied to a MoSi ₄ target on a quartz substrate, and sputter film formation was performed while rotating the substrate at 30 rpm, thereby providing a first layer film having a thickness of 500 mm. As a sputtering gas at this time, a mixed gas of Ar = 20 cm ³ / min, N ₂ = 100 cm ³ / min, and O ₂ = 5 cm ³ / min was introduced. The gas pressure during sputtering was set to 0.2 Pa.

Next, a discharge power of 500 W was applied to the ZrSi ₄ target to form a second layer film having a thickness of 200 mm. At this time, other film forming conditions were the same as those for the first layer. It should be noted that the Mo concentration [Mo] and the Zr concentration [Zr] in the target were compared as approximate guidelines for the Mo concentration and the Zr concentration of the first layer film and the second layer film. Under the experimental conditions, [Zr] / [Mo] = 1.000.

As a result of evaluating chemical resistance in the same manner as in Example 1, the rate of change in transmittance before and after immersion in the chemical solution was 0.014, and a step of about 4 nm was observed for the step in the etched cross section. In each layer, an inclination of the etched cross section was recognized, and the angle θ of the etched cross section was 78 deg in a portion where the inclination was conspicuous, which was not sufficient for practical use.
The above results are summarized in Table 1.

  As is apparent from these results, in the phase shift mask blank in which a phase shift film composed of two or more layers is provided on a transparent substrate, the surface layer is composed mainly of a zirconium silicide compound as the phase shift film. The substrate side has a composition containing a molybdenum silicide compound as a main component, and at least one film having a gently inclined composition is formed, so that the etched cross-sectional shape at the time of mask pattern formation is achieved while satisfying optical characteristics. It was confirmed that it was possible to obtain a phase shift mask blank and a phase shift mask excellent in chemical resistance.

It is sectional drawing of the phase shift mask blank which concerns on one Example of this invention. It is sectional drawing of the same phase shift mask. It is sectional drawing of the phase shift mask blank which provided the chromium-type light shielding film which concerns on one Example of this invention. It is sectional drawing of the phase shift mask blank which provided the chromium-type light shielding film and chromium-type antireflection film concerning one Example of this invention. It is sectional drawing of another phase shift mask blank. It is explanatory drawing which showed the manufacturing method of a phase shift mask, (A) is the state which formed the resist film, (B) is the state which patterned the resist film, (C) is the state which etched, (D) FIG. 3 is a schematic cross-sectional view with the resist film removed. It is sectional drawing which shows the other Example of a phase shift mask. It is the schematic of the direct current | flow sputtering apparatus used in the Example. (A), (B) is a figure explaining the principle of a halftone type | mold phase shift mask, (B) is the elements on larger scale of the X section of (A). It is a conceptual diagram of the level | step difference of an etch pattern cross section. It is a conceptual diagram of the shape of the etch pattern cross section.

Explanation of symbols

1,11,21 substrate 2,12 phase shift film (phase shift multilayer film)
2b Surface layer film of phase shift multilayer film 2c Lower layer film of phase shift multilayer film 3 Chrome-based light shielding film 4, 4 ′ Chrome-based antireflection film 1a Substrate exposed portion 2a Second light transmission portion (phase shifter portion)
13 Resist film 22a, 22b Target 14 Level of etched cross section θ Angle of etched section

Claims (6)

  In the phase shift mask blank comprising a phase shift film composed of two or more layers on a transparent substrate, the phase shift film has a composition whose surface layer is mainly composed of a zirconium silicide compound, and the substrate side is composed of a molybdenum silicide compound. It is a composition having a main component, and has a layer whose composition is gently inclined from the one layer composition to the other layer composition between at least one layer and another adjacent layer having a different composition. Feature phase shift mask blank.   An intermediate layer whose composition is gently inclined from the surface layer composition to the substrate side composition is interposed between the surface layer having a composition mainly composed of zirconium silicide compound and the substrate side layer having a composition mainly composed of molybdenum silicide compound. The phase shift mask blank according to claim 1.   The surface layer having a composition mainly composed of a zirconium silicide compound is composed of a film mainly composed of a compound of zirconium silicide and oxygen and / or nitrogen, and the substrate side layer having a composition mainly composed of a molybdenum silicide compound is composed of molybdenum silicide. The phase shift mask blank according to claim 1 or 2, comprising a film mainly composed of an oxygen and / or nitrogen compound.   2. A chrome-based light-shielding film, a chrome-based antireflection film, or a multi-layer film in which one or more of these chrome-based light-shielding films and chrome-based antireflection films are stacked on the phase shift film. , 2 or 3 phase shift mask blank.   Using a sputtering film forming apparatus provided with a molybdenum silicide target, a zirconium silicide target, and, if necessary, a silicon target in one chamber, performing sputtering film formation using a sputtering gas containing at least oxygen and / or nitrogen, The method of manufacturing a phase shift mask blank according to any one of claims 1 to 4, wherein a phase shift film having an inclined composition is formed by changing a combination of electric power applied to a plurality of targets. The phase shift mask of any one of claims 1 to 4, wherein the phase shift film of the phase shift mask blank is patterned.

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