JP4958149B2 - Method for manufacturing phase shift mask blank and method for manufacturing phase shift mask - Google Patents

Description

  The present invention relates to a phase shift mask that can improve the resolution of a transfer pattern by providing a phase difference between exposure light that passes through the mask, and more particularly, to a halftone phase shift mask and a phase shift that is an original of the phase shift mask. It relates to mask blank.

In semiconductor LSI manufacturing or the like, a photomask is used as a mask for fine pattern exposure. As a kind of this photomask, a phase shift mask that can improve the resolution of a transfer pattern by giving a phase difference between exposure light passing through the mask is used.
In recent years, a phase shift mask called a halftone phase shift mask has been developed as one of the phase shift masks. In this halftone phase shift mask, the mask pattern formed on the transparent substrate is substantially exposed to a portion that transmits light having an intensity that contributes substantially to exposure (hereinafter referred to as a light transmitting portion). And a portion that transmits light having an intensity that does not contribute to light (hereinafter referred to as a light semi-transmissive portion), and the phase of light passing through the light semi-transmissive portion is shifted to transmit the light semi-transmissive portion. The light transmitted through the vicinity of the boundary between the light transmission part and the light semi-transmission part can be obtained by making the phase of the transmitted light substantially invert with respect to the phase of the light transmitted through the light transmission part. By contrasting each other, the contrast of the boundary portion can be maintained satisfactorily.

  In such a halftone phase shift mask, the light semi-transmission part has both a light shielding function for substantially blocking exposure light and a phase shift function for shifting the phase of light, There is no need to separately form a phase shift film pattern with high transmittance that mainly controls the phase angle and a light shielding film pattern with low transmittance that mainly controls the light translucency, and the configuration is simple and easy to manufacture. It has the characteristic of being.

  In Patent Document 1 below, a light semi-transmissive film containing nitrogen, metal, and silicon as main components is transparent so that a light semi-transmissive part having a predetermined phase angle and transmittance and excellent film characteristics can be obtained. A method of manufacturing a halftone phase shift mask blank in which the light semi-transmissive film is heat-treated after being formed on a substrate is described.

JP 2002-162726 A

In recent years, with the miniaturization of circuit patterns, the exposure wavelength has been shortened, and the exposure wavelength is changing from 248 nm (KrF excimer laser) to 193 nm (ArF excimer laser). When the wavelength is shortened, the following problems become significant.
In the mask manufacturing process and mask use, chemical treatment (including cleaning) using an acid solution such as sulfuric acid or an alkali solution such as ammonia is performed. The film thickness of the light translucent film is determined by the acid solution or alkali solution. Change occurs. When the exposure wavelength is shortened, the phase angle shift increases even with the same amount of change in film thickness with respect to the chemical solution, so that it is necessary to further improve the durability (chemical resistance) against the chemical solution (acid or alkali). In other words, chemical resistance (acid resistance, alkali resistance) is becoming more demanding as the exposure light source becomes shorter in wavelength.

  In addition, as the wavelength of the laser light used for exposure is shortened, the energy of the laser light increases, so damage to the light semi-transmissive film due to exposure increases, and the service life limit required for the phase shift mask In some cases, a deviation occurs in the set transmittance and phase difference.

  In addition, the light semi-transmission part and the light semi-transmission film in the halftone phase shift mask and phase shift mask blank are made of a transparent substrate on which the light semi-transmission part and the light semi-transmission film are formed in order to ensure the depth of focus in exposure. It is necessary not to have a large internal stress that causes deformation. In particular, a phase shift mask or phase shift mask blank for an exposure wavelength of 193 nm (ArF excimer laser) needs to have a low internal stress.

  In order to solve the problems of chemical resistance, light resistance and internal stress as described above, in Patent Document 1, the light semi-transmissive film formed on the substrate is heat-treated. The above internal stress can be relaxed by, for example, heat treatment at 250 to 300 ° C. at the highest, but chemical resistance and light resistance are improved as the heat treatment temperature is increased. In order to have a heat treatment, a heat treatment of at least about 500 ° C. is required. However, when the light semi-transmissive film formed on the substrate is heat-treated at a high temperature of about 500 ° C., even if the chemical resistance and light resistance can be improved, there is a possibility that the film may be defective, and the film transmittance is further increased. Such a change in optical characteristics occurs, and the variation in the in-plane distribution of optical characteristics also increases. In the case of a halftone phase shift mask, the optical characteristics of the light semi-transmissive film must be strictly controlled, and a higher in-plane distribution of optical characteristics is required. Further, if the heat treatment temperature is increased too much, it takes a long time for the temperature to rise and fall, resulting in a problem that productivity is lowered. Therefore, as in Patent Document 1, the chemical resistance and light resistance are sufficiently improved without causing film defects and causing changes in optical properties only by heat treatment after the formation of the light semi-transmissive film. There are limits to this.

Further, according to the study of the present inventor, it has been found that there are the following problems when the exposure wavelength is shortened.
For example, since ArF excimer laser has a short wavelength, the energy of laser light increases. For this reason, the chemical reaction on the mask surface is promoted by the laser irradiation, whereby the formation of some precipitates is promoted, and there is a problem that the precipitates are generated and adhered as foreign matters on the mask. One such deposit has been identified as ammonium sulfate. The mask is generally cleaned using a sulfuric acid-based cleaning agent in the final process. It is thought that sulfuric acid or sulfate ions derived from the sulfuric acid-based cleaning agent used in the cleaning process often remain in the cleaned mask. For this reason, it is considered that the reaction of ammonium ions generated for some reason with this sulfate ion is promoted by laser irradiation, which is the cause of precipitates. The source of ammonium ions is considered to be substances or deposits derived from the atmosphere or pellicle. However, according to the study of the present inventor, as a result of investigating the use of a material containing nitrogen in the thin film used for the mask as described above, the thin film containing nitrogen is less than the thin film not containing nitrogen. It was found that many ammonium ions were present on the membrane surface. Therefore, it is considered that the thin film containing nitrogen may promote the precipitation of ammonium sulfate that can be a foreign matter defect.

Such a problem that foreign matters are deposited on the mask when the mask is used becomes apparent when the wavelength of the exposure light source used is 200 nm or less, such as an ArF excimer laser. That is, because the precipitation of foreign matter itself is promoted and the required pattern is miniaturized, a foreign matter having a smaller size that has not been a problem until now becomes a defect.

Therefore, when the sulfuric acid-based cleaning agent used in the mask cleaning process is surely removed and the above-described foreign matter precipitation is reduced, hot water cleaning at 50 to 60 ° C. is performed after sulfuric acid cleaning. The MoSiN film as described above is not sufficiently resistant to hot water, and changes in optical characteristics (transmittance and phase difference) due to film surface damage (erosion in the thickness direction) due to hot water cleaning, pattern cross-section There is a risk of causing a change in dimension of the transfer pattern due to damage (erosion in the width direction). In this case, similar to the above-mentioned chemical resistance and light resistance, it is considered possible to improve the hot water resistance by heat treatment of the light semi-transmissive film, but only by the heat treatment after the film formation of the light semi-transmissive film, There is a limit to sufficiently improving the hot water resistance without impairing the optical properties of the light semi-transmissive film.

  The present invention has been made in view of the conventional problems described above, and does not affect the optical characteristics and in-plane distribution of the light semi-transmissive film formed on the substrate, and the formed light. A phase shift mask blank with improved chemical resistance, light resistance and hot water resistance without causing film defects in the semi-transmissive film, and a halftone type phase shift mask obtained using the phase shift mask blank The purpose is to provide.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) A method of manufacturing a phase shift mask blank in which a light translucent film having a predetermined transmittance with respect to an exposure wavelength and having nitrogen, metal and silicon as main components is formed on a transparent substrate. A method of manufacturing a phase shift mask blank, comprising: forming the light semi-transmissive film on the transparent substrate; and causing ozone gas to act on the light semi-transmissive film.
As in Configuration 1, after forming the light semi-transmissive film on the transparent substrate, ozone gas is allowed to act on the light semi-transmissive film, thereby forming an oxide film on the surface of the light semi-transmissive film. The chemical resistance, light resistance and hot water resistance of the permeable membrane can be improved. Moreover, since it is not necessary to perform heat treatment at a high temperature as in the prior art, chemical resistance, light resistance, and warm water resistance can be achieved without causing film defects due to high temperature heat treatment or changing optical characteristics of the light semi-transmissive film. An improved phase shift mask blank is obtained. Therefore, pattern damage due to chemical treatment, pattern damage due to exposure light, or pattern damage due to hot water cleaning can be sufficiently prevented, and the function as a phase shift mask can be achieved even when the exposure light source wavelength is shortened to, for example, 200 nm or less. The present invention is particularly suitable without being damaged.

(Configuration 2) A method of manufacturing a phase shift mask blank according to Configuration 1, wherein the concentration of the ozone gas is 80% by volume or more.
As in Configuration 2, the ozone gas concentration in Configuration 1 is used at a high concentration of 80% by volume or more, so that even if the exposure wavelength is 200 nm or less and a short wavelength, sufficient chemical resistance and light resistance of the light translucent film are obtained. And hot water resistance can be obtained.

(Structure 3) Structure 1 characterized in that after the light semi-transmissive film is formed or ozone gas is allowed to act on the light semi-transmissive film, the light semi-transmissive film is subjected to heat treatment at 300 ° C. or lower. Or the manufacturing method of the phase shift mask blank of 2.
As in Configuration 3, for example, for the purpose of reducing (relaxing) the film stress of the light-semitransmissive film formed on the substrate, heat treatment may be performed at a temperature of 300 ° C. or lower sufficient to reduce the film stress. it can.

(Configuration 4) The method for producing a phase shift mask blank according to any one of Configurations 1 to 3, wherein the exposure wavelength is 200 nm or less.
As the exposure light source becomes shorter in wavelength, the need for chemical resistance, light resistance, and warm water resistance of the light translucent film is particularly high. Therefore, even if the exposure wavelength is as short as 200 nm or less, these resistances are maintained. The present invention that is sufficiently obtained has high utility.

(Configuration 5) Patterning the light-semitransmissive film of the phase shift mask blank obtained by the manufacturing method according to any one of Configurations 1 to 4, and main components nitrogen, metal, and silicon on a transparent substrate; A method of manufacturing a phase shift mask, comprising forming a light semi-transmissive portion.
By patterning the light-semitransmissive film of the phase shift mask blank according to any one of the structures 1 to 4, a light-semitransmissive part including nitrogen, metal, and silicon as main components is formed. A phase shift mask having excellent chemical resistance, light resistance and hot water resistance can be obtained.

(Structure 6) A method of manufacturing a phase shift mask according to Structure 5, wherein the light semi-transmissive portion formed on the transparent substrate is washed with warm water.
Since the light semi-transmissive film according to the present invention is excellent in hot water resistance, pattern damage does not occur even if the light semi-transmissive portion formed by patterning the light semi-transmissive film is washed with warm water. Therefore, by the hot water cleaning, it is possible to effectively suppress the occurrence of foreign matter defects on the mask even when the exposure wavelength is as short as 200 nm or less.

  According to the present invention, chemical resistance is achieved without affecting the optical characteristics and in-plane distribution of the light semi-transmissive film formed on the substrate, and without causing film defects in the formed light semi-transmissive film. A phase shift mask blank having improved properties, light resistance and warm water resistance is obtained. In addition, by using this phase shift mask blank, it is excellent in chemical resistance, light resistance, hot water resistance, and does not cause changes in the optical properties of the light translucent film, particularly when using a short wavelength exposure light source having a wavelength of 200 nm or less. A suitable halftone phase shift mask is obtained.

Hereinafter, the present invention will be described in detail by embodiments.
1A is a sectional view showing an embodiment of a phase shift mask blank obtained by the present invention, and FIG. 1B is an embodiment of a halftone phase shift mask obtained by the present invention. It is sectional drawing shown.
One embodiment of the phase shift mask blank obtained by the present invention is a phase shift mask blank 10 in which a light semi-transmissive film 2 is formed on a transparent substrate 1 as shown in FIG. The light semi-transmissive film 2 has a predetermined transmittance with respect to the exposure wavelength, and is made of a material mainly composed of nitrogen, metal, and silicon.

The light semi-transmissive film 2 in the present invention is a film mainly composed of metal, silicon, and nitrogen. By containing nitrogen in addition to the metal and silicon, the optical properties of the light semi-transmissive film (transmittance, (Phase angle) can be controlled.

Preferred examples of the metal that is a constituent element of the light translucent film 2 include metals such as molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and chromium (Cr). These materials containing metal and silicon have a relatively high refractive index with respect to exposure light having a wavelength of 200 nm or less, and can reduce the film thickness for shifting (preferably reversing) the phase. This is because the light transmittance (light shielding performance) with respect to the exposure light can also be set to a good value.

  In consideration of optical characteristics (transmittance, phase angle) in an exposure wavelength region of 200 nm or less, the composition of the light semi-transmissive film 2 is 2 to 8 atomic% for metal, 20 to 50 atomic% for silicon, and 30 for nitrogen. It is preferable to set it to -70 atomic%.

Specific materials of the light semi-transmissive film 2 mainly composed of nitrogen, metal, and silicon include, for example, nitrided molybdenum and silicon (MoSiN material), nitrided tantalum and silicon (TaSiN material), Examples include nitrided tungsten and silicon (WSiN-based material), nitrided titanium and silicon (TiSiN-based material), nitrided chromium and silicon (CrSiN-based material), and the like. Among these materials, a material made of nitrided molybdenum and silicon (MoSiN material) whose metal is molybdenum (Mo) or tantalum (Ta), a material made of nitrided tantalum and silicon (TaSiN material), This is preferable in terms of processing characteristics (pattern controllability) in the mask manufacturing process and prevention of defects due to a sputter target factor.

Such a translucent film 2 can be formed, for example, by sputtering film formation (DC sputtering, RF sputtering, ion beam sputtering, etc.) in a low-pressure atmosphere. This is because the use of a low-pressure atmosphere facilitates the formation of a dense film and is preferable for improving chemical resistance.

The light semitransmissive film 2 has two functions of a light shielding function that substantially blocks exposure light and a phase shift function that shifts the phase of light. Since the values of these functions differ depending on the exposure light source and its wavelength when the mask is used, it is necessary to design and select the values corresponding to the exposure light source to be used and its wavelength.

The phase shift amount of the light semitransmissive film 2 can be controlled by adjusting the film composition and film thickness of the light semitransmissive film. When the phase shift amount is φ, the wavelength of the exposure light is λ, and the refractive index of the light semi-transmissive film is n, the film thickness d of the light semi-transmissive film can be determined by the following equation (1).
d = (φ / 360) × [λ / (n−1)] (1)
The phase shift amount φ in the equation (1) is most desirably 180 degrees from the viewpoint of improving the resolution, but may be practically about 160 degrees to 200 degrees.

  The light transmittance (light-shielding performance) of the light semi-transmissive film 2 with respect to the exposure light is generally about 2 to 20%, although it depends on the sensitivity of the resist used when forming a pattern such as a semiconductor element. Within this range, the light transmittance is preferably higher because the higher the transmittance, the higher the phase effect. However, in the case of a line and space pattern, it is preferable that the light transmittance is low, and in the case of a hole or dot pattern, it is preferable that the light transmittance is high. The light transmittance of the light semi-transmissive film 2 can be controlled by adjusting the film composition.

  The transparent substrate 1 used for the phase shift mask blank 10 is not particularly limited as long as it is a substrate transparent to the exposure wavelength to be used. Examples of the transparent substrate 1 include a quartz substrate and other various glass substrates (for example, soda lime glass, aluminosilicate glass, and the like). In particular, a quartz substrate is suitable for the present invention because it is highly transparent to, for example, ArF excimer laser (wavelength 193 nm) or exposure light having a shorter wavelength.

The phase shift mask blank 10 of the present invention is manufactured by forming the light semi-transmissive film 2 on the transparent substrate 1 such as a quartz substrate using the above-mentioned known thin film forming method.
In the present invention, after the light semi-transmissive film 2 is formed on the transparent substrate 1, the surface of the light semi-transmissive film 2 is irradiated with ozone gas, or the substrate on which the light semi-transmissive film 2 is formed is treated with ozone gas. An oxide film is formed on the surface of the light semi-transmissive film 2 by allowing ozone gas to act on the surface of the light semi-transmissive film 2 by a method such as exposure to the inside. In this case, the concentration of ozone gas is preferably set to a high concentration of 80% by volume or more. By using such high-concentration ozone gas, even if the exposure light source wavelength is as short as 200 nm or less, the chemical resistance, light resistance, and warm water resistance sufficiently satisfy the resistance required for the light semi-transmissive film. can get.

  In addition, there is no need to particularly limit the time (treatment time) for which ozone gas is applied, the ambient temperature, etc. However, for example, if the ambient temperature is high, the oxidation rate by ozone gas increases, so from the viewpoint of increasing productivity, the treatment time Is preferably in the range of, for example, about 5 to 60 minutes, and the ambient temperature is in the range of, for example, room temperature to about 300 ° C.

According to the present invention, by applying ozone gas to the light semi-transmissive film 2 formed on the transparent substrate 1 as described above, an oxide film is formed on the surface of the light semi-transmissive film. Chemical properties, light resistance, and warm water resistance can be improved. Moreover, since it is not necessary to perform heat treatment at a high temperature as in the prior art, chemical resistance, light resistance, and warm water resistance can be achieved without causing film defects due to high temperature heat treatment or changing optical characteristics of the light semi-transmissive film. Can be improved. Therefore, pattern damage due to various chemical treatments in the mask blank and mask manufacturing process, pattern damage due to the energy of laser light used for exposure, or removal of sulfuric acid-based cleaning agent used in the mask cleaning process to generate foreign matter defects Pattern damage due to warm water cleaning performed after sulfuric acid cleaning for suppression can be sufficiently prevented. With the shortening of the exposure light source wavelength, the requirements for chemical resistance, light resistance, and warm water resistance of these light semi-transmissive films are particularly increasing, so even if the exposure wavelength is as short as 200 nm or less The present invention in which sufficient tolerance is obtained is particularly useful.

In the present invention, after the light semi-transmissive film 2 is formed on the transparent substrate 1 or ozone gas is allowed to act on the formed light semi-transmissive film 2, the light semi-transmissive film 2 is changed to 300. Heat treatment may be performed at a temperature not higher than ° C. This is for the purpose of reducing (relaxing) the film stress of the light-semitransmissive film 2 formed on the transparent substrate 1, and heat treatment can be performed at a temperature of 300 ° C. or less sufficient to reduce the film stress.

  In order to prevent generation of particles due to film peeling of the light semi-transmissive film at the peripheral edge of the substrate, a light semi-transmissive film may be formed in a region excluding the peripheral edge on the main surface of the transparent substrate. Moreover, although the case where the light semi-transmissive film is a single layer has been described in the above embodiment, a light semi-transmissive film having a multilayer structure in which two or more light semi-transmissive films having a single layer structure are stacked may be used. .

FIG. 1B shows a light semi-transmissive portion 2a and a light transmissive portion having nitrogen, metal and silicon as main components on the transparent substrate 1 by patterning the light semi-transmissive film 2 of the phase shift mask blank 10 described above. 3 shows a halftone phase shift mask 20 formed with 3.
FIG. 2 shows an example of a manufacturing process of a halftone phase shift mask using the phase shift mask blank according to the present invention.
According to this, first, a resist film 4 (for example, a positive resist film for electron beams) is formed on the light semi-transmissive film 2 of the phase shift mask blank 10 (see FIGS. 1A and 1B). Next, a predetermined pattern is drawn on the resist film 4 using an electron beam drawing machine, and development processing is performed to form a resist pattern 4a (see FIG. 5C).

Next, using the resist pattern 4a as a mask, the light semi-transmissive film 2 is etched to form a light semi-transmissive film pattern (light semi-transmissive portion 2a) (see FIG. 4D). The remaining resist pattern 4a is removed by oxygen ashing or the like.
As described above, the halftone phase shift mask 20 in which the light semi-transmissive portion 2a and the light transmissive portion 3 formed of a patterned light semi-transmissive film are formed on the transparent substrate 1 can be obtained (see FIG. (See (e)).

As described above, the phase shift mask blank and the phase shift mask according to the present invention are particularly suitable when exposure light having an exposure wavelength of 200 nm or less, for example, ArF excimer laser (wavelength 193 nm) or shorter wavelength is used as the exposure light source. is there. That is, with the shortening of the wavelength of the exposure light source, the level of resistance required for the light semi-transmissive film in the phase shift mask blank and the phase shift mask is also increased. According to the present invention, pattern damage due to various chemical treatments and Even if the pattern can be sufficiently prevented from being damaged by the energy of the laser beam used for the exposure, the exposure wavelength is a short wavelength such as 200 nm or less, and a laser beam having a large energy is used as the exposure light source, These required resistances are fully obtained. In addition, since the light semi-transmissive film according to the present invention is excellent in hot water resistance, pattern damage does not occur even if the light semi-transmissive portion formed by patterning the light semi-transmissive film is washed with warm water. Therefore, the remaining sulfuric acid-based cleaning agent used in the mask cleaning process is sufficiently removed by hot water cleaning, and the generation of foreign matter defects on the mask is effectively achieved even when the exposure wavelength is as short as 200 nm or less. Can be suppressed.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
Using a mixed target (Mo: Si = 8 mol%: 92 mol%) of molybdenum (Mo) and silicon (Si), a mixed gas atmosphere (Ar: N ₂ = 20 vol%) of argon (Ar) and nitrogen (N ₂ ). : A light translucent film (film thickness: 67 nm) of nitrided molybdenum and silicon (MoSiN) is formed on a synthetic quartz glass substrate by reactive sputtering (DC sputtering) at 80 volume% and pressure 0.1 Pa). did.

Next, ozone gas was irradiated to the light semi-transmissive film formed as described above. In this case, the ozone gas concentration was 80% by volume, the ambient temperature was 250 ° C., and the irradiation time was 30 minutes. Subsequently, after heat-treating in the atmosphere at 250 ° C. for 15 minutes, the surface of the light translucent film was scrubbed with pure water to produce a halftone phase shift mask blank for ArF excimer laser exposure.

The obtained halftone phase shift mask blank had an transmittance of 6.0% and a phase angle of 180 ° in an ArF excimer laser (wavelength: 193 nm). The transmittance was measured using a spectrophotometer (manufactured by Shimadzu Corporation: UV2400), and the phase angle was measured using a phase difference measuring machine (manufactured by Lasertec: MPM-193).

Next, the light resistance of the light semi-transmissive film was examined. That is, an ArF excimer laser (wavelength: 193 nm) was irradiated with an energy of 8 mJ / cm ² / pulse at 200 Hz and an accumulated energy amount of 50 kJ / cm ^2, and evaluation of transmittance change and phase angle change due to irradiation was performed. A negative phase angle change indicates that the phase angle has decreased. As a result, the transmittance change after irradiation was + 0.1%, and the phase angle change was −0.1 °, showing almost no change and excellent light resistance.

Next, using this halftone phase shift mask blank, a halftone phase shift mask was produced by the following method.
That is, after applying and forming a positive resist film for electron beam drawing on the light semi-transmissive film of the halftone phase shift mask blank, a predetermined pattern is drawn by an electron beam drawing machine, and development processing is performed to form a resist pattern. Formed.
Next, by using this resist pattern as a mask, the exposed portion of the light semi-transmissive film made of nitrided molybdenum and silicon is removed by dry etching with a mixed gas of SF ₆ gas and He gas, and the pattern of the light semi-transmissive film is obtained. (Holes, dots, etc.) were obtained.
Next, after removing the remaining resist pattern, it was immersed in 98% sulfuric acid (H ₂ SO ₄ ) at 100 ° C. for 30 minutes and washed with sulfuric acid, and then washed with warm water at 80 ° C. for 60 minutes to obtain ArF. A halftone phase shift mask for excimer laser exposure was obtained.

  When the transmittance and phase angle of the light semi-transmissive portion of the obtained phase shift mask were measured and the change from the value in the mask blank was examined, the transmittance change was + 0% and the phase angle change was -0.2 °. The change was very small and had excellent chemical resistance and hot water resistance. Further, the cross section of the pattern (light semi-transmissive portion) was good without any damage caused by hot water.

Hereinafter, a comparative example with respect to the above embodiment will be described.
(Comparative example)
An ArF excimer laser was formed in the same manner as in Example 1 except that after the light-semitransmissive film was formed, heat treatment was performed in the air at 500 ° C. for 15 minutes without irradiation with ozone gas. A halftone phase shift mask blank for exposure was prepared.

The obtained halftone phase shift mask blank had an transmittance of 6.0% and a phase angle of 180 ° in an ArF excimer laser (wavelength: 193 nm). The variation was 1.7%, and the in-plane transmittance variation was large. Therefore, the optical characteristics of the light semi-transmissive film have deviated from the design values. Further, surface defects occurred in the light semi-transmissive film after the heat treatment.
As a result of evaluating the light resistance of the obtained light semi-transmissive film in the same manner as in Example 1, the transmittance change after irradiation was + 0.2%, and the phase angle change was + 0.5 °, which was compared with Example 1. And the light resistance was slightly inferior.

Next, using this halftone phase shift mask blank, patterning was performed in the same manner as in Example 1, and sulfuric acid cleaning and hot water cleaning were performed to prepare a halftone phase shift mask.
When the transmittance and phase angle of the light semi-transmissive portion of the obtained phase shift mask were measured and the change from the value in the mask blank was examined, the transmittance change was + 0.1%, and the phase angle change was -0.4. The change was somewhat large, and the chemical resistance and hot water resistance were slightly inferior to those of Example 1.

Thus, the phase shift mask obtained by this comparative example is not sufficient in chemical resistance, light resistance, and warm water resistance especially when used at an exposure wavelength of 200 nm or less. If the heat treatment after the light semi-transmissive film is formed at a higher temperature for a long time in order to further improve these resistances, the effect on the optical characteristics of the light semi-transmissive film will be further increased. Conceivable.

(A) is sectional drawing which shows one Embodiment of the phase shift mask blank of this invention, (b) is sectional drawing which shows one Embodiment of the halftone type | mold phase shift mask of this invention. (A) thru | or (e) is sectional drawing which shows the manufacturing process of the halftone type phase shift mask using the phase shift mask blank of this invention in order.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Light semi-transmissive film 2a Light semi-transmissive part 3 Light transmissive part 4 Resist film 10 Phase shift mask blank 20 Halftone type phase shift mask

Claims (6)

In a method of manufacturing a phase shift mask blank having a predetermined transmittance with respect to an exposure wavelength on a transparent substrate, and a light semi-transmissive film having nitrogen, metal, and silicon as main components, is formed.
After forming the light semi-transmissive film on the transparent substrate, ozone gas is allowed to act on the light semi-transmissive film ,
The concentration of the ozone gas is 80% by volume or more;
A method of manufacturing a phase shift mask blank, characterized in that after the light semi-transmissive film is formed or ozone gas is allowed to act on the light semi-transmissive film, the light semi-transmissive film is heat-treated in the atmosphere. . The manufacturing method of the phase shift mask blank according to claim 1, wherein an atmospheric temperature when the ozone gas is allowed to act is room temperature to 300 ° C. The heat treatment, a method of manufacturing a phase shift mask blank according to claim 1 or 2, characterized in that at 300 ° C. or less. The method of manufacturing a phase shift mask blank according to any one of claims 1 to 3, wherein the ozone gas is applied to a surface of the light semi-transmissive film.   An optical half comprising nitrogen, metal and silicon as main components on a transparent substrate by patterning the light semitransmissive film of the phase shift mask blank obtained by the manufacturing method according to claim 1. A method of manufacturing a phase shift mask, comprising forming a transmission part.   6. The method of manufacturing a phase shift mask according to claim 5, wherein the light semi-transmissive portion formed on the transparent substrate is washed with warm water.

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