JP2017049573A - Half tone phase shift type photomask blank, method for producing the same, and half tone phase shift type photomask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a half tone phase shift type photomask blank with a half tone phase shift film in which a prescribed phase difference is secured, low in stress, and also excellent in workability, and a half tone phase shift type photomask.SOLUTION: There is provided a half tone phase shift type photomask blank, comprising: a transparent substrate; and a half tone phase shift film having a permeability of 9 to 40% and a phase difference of 150 to 200°, in which the half tone phase shift film is composed of transition metal, silicon, oxygen, and nitrogen, and in which the average content of the transition metal is 3 atomic% or more, and is also composed of a double layer made of a stress relaxation layer and a phase difference regulation layer. The stress relaxation layer has an oxygen content of 3 atomic % or more, and also, the phase difference regulation layer as the lowest layer has an oxygen content of 5 atomic% or more, and being the layer higher by 2 atomic% or more than the stress relaxation layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a halftone phase shift photomask blank applied to the manufacture of a semiconductor integrated circuit or the like, a manufacturing method thereof, and a halftone phase shift photomask.

  In the photomask technology, as the miniaturization progresses, the pattern width becomes smaller than the exposure wavelength, and OPT (Resolution Enhancement Technology) such as OPC (Optical Proximity Correction), modified illumination, immersion exposure, and phase shift method, double High resolution techniques such as exposure are being used. In particular, in the phase shift method, a halftone phase shift film having a transmittance of about 6% has been conventionally used. However, when the pattern width is narrower, for example, a pattern with a half pitch of 50 nm or less is obtained by photolithography. In the case of forming, a high transmittance is necessary to obtain a higher contrast ratio, and a phase difference of about 180 ° and a transmittance of 9% to 40% are required. .

JP 2006-78953 A JP 2003-280168 A

  As for the high transmittance halftone phase shift photomask blank, a halftone phase shift photomask blank having a halftone phase shift film made of silicon and nitrogen, or silicon, oxygen and nitrogen has been studied. In the tone phase shift type photomask blank, it is expected that the film thickness is reduced and the cleaning resistance is improved. However, this halftone phase shift film has disadvantages in processability from a photomask blank to a photomask, such as a slow etching rate by fluorine-based dry etching and extremely difficult defect correction.

  The processability of photomask blanks can be improved by adding a transition metal to the halftone phase shift film. However, the addition of a transition metal tends to reduce the transmittance of the film. In order to obtain a phase shift film, it is necessary to add not only nitrogen but also oxygen to some extent. However, when a high-transmittance halftone phase shift film made of a transition metal, silicon, oxygen, and nitrogen is formed as a single layer film, there is a problem that the film stress increases. Since the film stress is released after processing from the photomask blank to the photomask, the high film stress causes a decrease in the positional accuracy of the formed film pattern. In particular, when the halftone phase shift film is formed as a single layer film by sputtering that is commonly used when forming the halftone phase shift film, the reactive gas is introduced into the chamber in accordance with the predetermined film composition. Since sputtering is performed in a state where the amount is always large, it is difficult to form a film by lowering the pressure in the chamber, which is effective for reducing the film stress, and the film stress can be reduced by adjusting the film formation conditions such as the pressure in the chamber. It is extremely difficult to keep it low.

  The present invention has been made to solve the above-mentioned problems, and is a halftone phase shift photomask having a high transmittance halftone phase shift film composed of a film made of a transition metal, silicon, oxygen and nitrogen. In a blank, a halftone phase shift photomask blank having a predetermined phase difference, a low stress, and a halftone phase shift film excellent in workability, a manufacturing method thereof, and a halftone phase shift photomask The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventor has found that a halftone phase shift photo having a high transmittance halftone phase shift film composed of a film made of a transition metal, silicon, oxygen and nitrogen. In a mask blank, a halftone phase shift film composed of transition metal, silicon, oxygen and nitrogen is formed of a multilayer of two or more layers composed of a stress relaxation layer having a low oxygen content and a phase difference adjusting layer having a high oxygen content. By forming it with a film, it becomes a halftone phase shift film with high transmittance for exposure light and a predetermined phase shift amount and high processing accuracy, and a halftone phase formed with such a multilayer film. In the case of a shift film, the transmittance of the stress relaxation layer tends to be lower on the longer wavelength side than exposure light wavelength, typically in infrared light. In light annealing treatment such as pre-annealing, the absorption efficiency of irradiated light is increased, so that a multi-layered halftone phase shift film composed of a stress relaxation layer and a phase difference adjusting layer is advantageous in reducing film stress due to light annealing treatment. As a result, the present invention has been made.

Accordingly, the present invention provides the following halftone phase shift photomask blank, method for manufacturing a halftone phase shift photomask blank, and halftone phase shift photomask.
Claim 1:
A transparent substrate, and a halftone phase shift film formed on the transparent substrate and having a transmittance of 9% to 40% and a phase difference of 150 ° to 200 ° with respect to light having a wavelength of 200 nm or less Halftone phase shift photomask blank,
The halftone phase shift film is
Consisting of transition metals, silicon, oxygen and nitrogen,
The average content of transition metal is 3 atomic% or more, and one or more layers of transition metal, silicon, oxygen and nitrogen, and one or more layers of transition metal, silicon and oxygen And a multilayer composed of a phase difference adjusting layer made of nitrogen,
The stress relaxation layer has an oxygen content of 3 atomic% or more and the lowest layer, the retardation adjusting layer has an oxygen content of 5 atomic% or more, and is more than the stress relaxation layer. A halftone phase shift photomask blank characterized in that the layer is a layer higher by 2 atomic% or more.
Claim 2:
2. The halftone phase shift photomask blank according to claim 1, wherein the halftone phase shift film is formed in contact with a transparent substrate.
Claim 3:
The halftone phase shift type photomask blank according to claim 2, wherein the layer formed on the most transparent substrate side is the stress relaxation layer.
Claim 4:
The halftone phase shift film is composed of three or more layers, and each phase difference adjusting layer is laminated so as to be in contact with any one of the stress relaxation layers. The halftone phase shift type photomask blank described in the item.
Claim 5:
5. The halftone phase shift photomask blank according to claim 1, wherein the content of the transition metal is 5 atomic% or more and 10 atomic% or less.
Claim 6:
The halftone phase shift photomask blank according to any one of claims 1 to 5, wherein the transition metal is molybdenum.
Claim 7:
The halftone phase shift photomask blank according to any one of claims 1 to 6, wherein the transmittance of the halftone phase shift film is 9% or more and 12% or less.
Claim 8:
The halftone phase shift photomask blank according to any one of claims 1 to 6, wherein the transmittance of the halftone phase shift film is 15% or more and 30% or less.
Claim 9:
In photolithography for forming a pattern with a half pitch of 50 nm or less on a substrate to be processed, a halftone phase shift used for pattern exposure in which the pattern is transferred to the photoresist film formed on the substrate to be processed with exposure light having a wavelength of 200 nm or less. The halftone phase shift photomask blank according to any one of claims 1 to 8, wherein the halftone phase shift photomask blank is used for a type photomask.
Claim 10:
A transparent substrate, and a halftone phase shift film formed on the transparent substrate and having a transmittance of 9% to 40% and a phase difference of 150 ° to 200 ° with respect to light having a wavelength of 200 nm or less A method of manufacturing a halftone phase shift photomask blank,
On a transparent substrate
Consisting of transition metals, silicon, oxygen and nitrogen,
The average content of transition metal is 3 atomic% or more, and one or more layers of transition metal, silicon, oxygen and nitrogen, and one or more layers of transition metal, silicon and oxygen And a multilayer composed of a phase difference adjusting layer made of nitrogen,
The stress relaxation layer has an oxygen content of 3 atomic% or more and the lowest layer, the retardation adjusting layer has an oxygen content of 5 atomic% or more, and is more than the stress relaxation layer. A method for producing a halftone phase shift type photomask blank comprising a step of forming a halftone phase shift film which is a layer higher by 2 atomic% or more.
Claim 11:
The halftone phase shift film has a transmittance of 9% or more and 12% or less, and includes a step of irradiating the halftone phase shift film formed on the transparent substrate with light containing infrared rays. The manufacturing method of the halftone phase shift type photomask blank of Claim 10.
Claim 12:
Before the step of irradiating light containing infrared rays, the method further includes a step of heat-treating the halftone phase shift film formed on the transparent substrate at 250 ° C. to 600 ° C. for 2 hours or more. The method for producing a halftone phase shift photomask blank according to claim 11.
Claim 13:
The halftone phase shift film has a transmittance of 15% or more and 30% or less, and the halftone phase shift film formed on the transparent substrate is heat treated by holding at 250 ° C. or more and 600 ° C. or less for 2 hours or more. The method for producing a halftone phase shift photomask blank according to claim 10, wherein the halftone phase shift film formed on the transparent substrate does not include a step of irradiating light containing infrared rays. Method.
Claim 14:
A transparent substrate, and a pattern of a halftone phase shift film formed on the transparent substrate and having a transmittance of 9% to 40% and a phase difference of 150 ° to 200 ° with respect to light having a wavelength of 200 nm or less A halftone phase shift photomask having
The halftone phase shift film is
Consisting of transition metals, silicon, oxygen and nitrogen,
The average content of transition metal is 3 atomic% or more, and one or more layers of transition metal, silicon, oxygen and nitrogen, and one or more layers of transition metal, silicon and oxygen And a multilayer composed of a phase difference adjusting layer made of nitrogen,
The stress relaxation layer has an oxygen content of 3 atomic% or more and the lowest layer, the retardation adjusting layer has an oxygen content of 5 atomic% or more, and is more than the stress relaxation layer. A halftone phase shift photomask characterized in that the layer is a layer higher by 2 atomic% or more.

  According to the present invention, in a halftone phase shift type photomask blank having a high transmittance halftone phase shift film composed of a film made of transition metal, silicon, oxygen and nitrogen, a predetermined phase difference is ensured, It is possible to provide a halftone phase shift photomask blank and a halftone phase shift photomask having a halftone phase shift film having a low stress and excellent workability, and further miniaturizing a pattern in photolithography. And pattern exposure that meets the requirements for higher accuracy.

6 is a graph showing the relationship between the oxygen content of the halftone phase shift film of Experimental Example 1 and ΔTIR.

Hereinafter, the present invention will be described in more detail.
The halftone phase shift photomask blank of the present invention comprises a transparent substrate such as a quartz substrate, and a halftone phase shift film composed of a film made of transition metal, silicon, oxygen and nitrogen formed on the transparent substrate. Have.

The halftone phase shift film of the present invention has a transmittance of 9% or more and 40% or less with respect to light (exposure light) having a wavelength of 200 nm or less such as ArF excimer laser (wavelength 193 nm), F ₂ laser (wavelength 157 nm), etc. In particular, it is 30% or less, and is intended to have a high transmittance as compared with a conventional halftone phase shift film containing a transition metal. When the transmittance exceeds 40%, the film stress is high, and even if the heat treatment described later is performed, the effect of reducing the stress cannot be sufficiently obtained.

  The phase difference of the halftone phase shift film of the present invention is determined by the phase difference of the exposure light passing through each of the phase shift film portion (phase shift portion) and the adjacent portion without the phase shift film. The phase difference may be any phase difference that can increase the contrast due to interference of light, and the phase difference may be set to 150 ° to 200 °. In a general phase shift film, the phase difference is set to about 180 °. However, from the viewpoint of increasing the contrast described above, the phase difference is not limited to about 180 °, and the phase difference should be smaller or larger than 180 °. Can do. For example, if the phase difference is smaller than 180 °, it is effective for thinning. In addition, it is needless to say that the phase difference close to 180 ° is more effective from the viewpoint of obtaining higher contrast. Needless to say, the phase difference is 160 ° or more, particularly 175 ° or more, 190 ° or less, particularly 185 ° or less. It is preferable that the angle is approximately 180 °.

  The halftone phase shift film of the present invention has a multilayer structure composed of two types of layers, a stress relaxation layer made of transition metal, silicon, oxygen and nitrogen, and a phase difference adjusting layer made of transition metal, silicon, oxygen and nitrogen. A film, that is, a film composed of two or more layers. The upper limit of the number of layers is not particularly limited, but is usually 4 layers or less.

  The stress relaxation layer is a layer having the lowest oxygen content among the layers constituting the multilayer, and the retardation adjusting layer has an oxygen content of 2 atomic% or more, preferably 5 than the stress relaxation layer. The layer is higher by atomic% or more, more preferably by 10 atomic% or more, and still more preferably by 15 atomic% or more. That is, of the layers constituting the multilayer, the layer having the lowest oxygen content is a stress relaxation layer, and the other layers are phase difference adjustment layers having a higher oxygen content than the stress relaxation layer. By configuring the halftone phase shift film with multiple layers consisting of a stress relaxation layer and a phase difference adjusting layer, the film stress of the entire halftone phase shift film is reduced compared to a halftone phase shift film having a single layer structure. Therefore, the processing accuracy when processing the halftone phase shift film into a film pattern is further improved.

  The stress relaxation layer may be one layer or two or more layers, but when the stress relaxation layer is two or more layers, the oxygen content of each stress relaxation layer needs to be the same. In this case, the transition metal, silicon, and nitrogen contents of each stress relaxation layer may all be different, but it is preferable that a part or all of them are the same. Moreover, when there are two or more stress relaxation layers, each thickness may be the same or different. On the other hand, when two or more retardation adjustment layers are used, the content of transition metal, silicon, oxygen and nitrogen in each retardation adjustment layer may all be different, or part or all of them may be the same. It may be. In addition, when there are two or more retardation adjustment layers, the thicknesses may be the same or different.

  The halftone phase shift film of the present invention is formed on a transparent substrate via, for example, an optical film such as a light shielding film or an antireflection film, a processing auxiliary film such as an etching mask film or an etching stopper film, or another film such as a conductive film. However, it is preferably formed in contact with the transparent substrate without interposing another film. In addition, on the side of the halftone phase shift film away from the transparent substrate, an optical film such as a light shielding film and an antireflection film, an auxiliary processing film such as an etching mask film and an etching stopper film, a conductive film, a resist film, and the like are formed. May be.

  Among the stress relaxation layer and the phase difference adjustment layer constituting the halftone phase shift film, the stress relaxation layer (the layer when the stress relaxation layer is one layer, the layer when it is two layers or more) is the most transparent. It is preferably formed on the substrate side, particularly in contact with the transparent substrate. If the stress relaxation layer is placed in contact with the transparent substrate, the film stress at the portion in contact with the transparent substrate due to the transparent substrate is effectively relieved, and the halftone is compared with the halftone phase shift film having a single layer structure. The film stress of the entire phase shift film can be further reduced, and the processing accuracy when the halftone phase shift film is processed into a film pattern is further improved.

  Specifically, as such a halftone phase shift film, in order from the transparent substrate side, a two-layer structure halftone phase shift film in which a stress relaxation layer and a phase difference adjusting layer are formed, in order from the transparent substrate side, stress is applied. A half-tone phase shift film having a three-layer structure in which a relaxation layer and two retardation adjustment layers are formed, and three layers in which a stress relaxation layer, a retardation adjustment layer, and a stress relaxation layer are formed in this order from the transparent substrate side Examples include a halftone phase shift film having a structure. The halftone phase shift film in which the stress relaxation layer is formed in contact with the transparent substrate has a lower film stress than a halftone phase shift film having a single layer structure with the same transmittance, retardation, and film thickness. This is particularly effective because the effect of reducing the film stress by the heat treatment described later and the treatment of pulsed irradiation with light containing infrared rays is high. In addition, in the stress relaxation layer and the phase difference adjustment layer constituting the halftone phase shift film, the stress relaxation layer is formed on the most surface side (side away from the substrate), particularly in the two-layer structure, in order from the substrate side. By using the phase difference adjusting layer and the stress relaxation layer, the reflectance from the surface side of the halftone phase shift film can be increased, and the defect detection sensitivity can be increased.

  Further, when the halftone phase shift film is composed of three or more layers, each of the phase difference adjusting layers (if the phase difference adjusting layer is one layer, that layer, and if more than one layer, all layers) It is preferable to laminate so as to be in contact with the stress relaxation layer, and in particular, alternately stack the stress relaxation layer and the phase difference adjusting layer. By laminating the retardation adjustment layer so as to be in contact with the stress relaxation layer, the film stress of the retardation adjustment layer, which has a higher film stress than that of the stress relaxation layer, can be efficiently relaxed, and a halftone phase shift film having a single layer structure As compared with the above, the film stress of the entire halftone phase shift film can be further reduced, and the processing accuracy when the halftone phase shift film is processed into a film pattern is further improved.

  Specifically, as such a halftone phase shift film, a halftone phase shift film having a three-layer structure in which a phase difference adjusting layer, a stress relaxation layer, and a phase difference adjusting layer are formed in order from the transparent substrate side, a transparent substrate In order from the side, a half-tone phase shift film having a four-layer structure in which a stress relaxation layer, a two-layer retardation adjustment layer, and a stress relaxation layer are formed, and from the transparent substrate side, the retardation adjustment layer and the stress relaxation layer, Examples thereof include a half-tone phase shift film having a four-layer structure alternately formed in order from a phase difference adjusting layer or a stress relaxation layer. In order from the transparent substrate side, a stress relaxation layer and a phase difference adjustment layer, such as a half-tone phase shift film having a three-layer structure in which a phase difference adjustment layer, a stress relaxation layer, and a phase difference adjustment layer are formed, are alternately laminated. The halftone phase shift film has a lower film stress than that of a halftone phase shift film having a single layer structure with the same transmittance, retardation, and film thickness, and pulse irradiation with light including heat treatment and infrared rays described later. This is particularly effective because the effect of reducing the film stress by the treatment is high.

  The halftone phase shift film of the present invention is a film made of transition metal, silicon, oxygen and nitrogen, that is, a film of transition metal silicon oxynitride, but excludes those containing other elements in the amount of impurities. is not. The halftone phase shift film is a high transmittance halftone phase shift film having a transmittance of 9% or more, and in order to ensure its workability, the average transition metal content is 3 atomic% or more, preferably 5 At least atomic percent. Further, the average content of the transition metal is preferably 10 atom% or less, particularly 8 atom% or less, particularly 7 atom% or less. When the average content of the transition metal exceeds 10 atomic%, the film may have poor cleaning resistance and exposure light irradiation resistance.

  On the other hand, the average silicon content of the halftone phase shift film is 30 atomic% or more, particularly 33 atomic% or more, 45 atomic% or less, particularly 40 atomic% or less, and the average oxygen content is 10 atomic% or more, particularly 12 It is preferably at least 45% by atom and more preferably at most 40% by atom. The average content of nitrogen is substantially the balance. Here, the average content in the halftone phase shift film corresponds to the ratio (percentage) of the total amount of each element to the total amount of atoms contained in all the layers constituting the halftone phase shift film.

  The transition metal, silicon, oxygen and nitrogen content of each layer constituting the halftone phase shift film is 3 for the transition metal and silicon, both for the stress relaxation layer and the phase difference adjusting layer. Atomic% or more, especially 5 atomic% or more, 10 atomic% or less, especially 7 atomic% or less, silicon is 30 atomic% or more, especially 33 atomic% or more, 45 atomic% or less, especially 40 atomic% or less. preferable. On the other hand, in the case of the stress relaxation layer, the oxygen content is preferably 5 atomic% or more, particularly 10 atomic% or more, 35 atomic% or less, particularly 30 atomic% or less, and particularly preferably 20 atomic% or less. In the case of the phase difference adjusting layer, it is preferably 7 atom% or more, particularly 12 atom% or more, 60 atom% or less, particularly 50 atom% or less, particularly 40 atom% or less. In this case, the nitrogen content is substantially the balance.

  In the present invention, a stress relaxation layer having a low oxygen content of 2 atomic% or more is applied to the phase difference adjusting layer, thereby reducing the film stress of the halftone phase shift film. Although it can function effectively, when the average content of oxygen in the halftone phase shift film is 26 atomic% or more, the oxygen content of all the layers constituting the halftone phase shift film is particularly high Is 26 atomic% or more, since a large amount of oxygen greatly affects the increase in film stress, the difference in oxygen content between the stress relaxation layer and the retardation adjustment layer is 10 atomic% or more. It is preferable to set it to 15 atomic% or more.

  If the thickness of the stress relaxation layer (the total thickness when there are two or more stress relaxation layers) is too thin relative to the total thickness of the halftone phase shift film, the film formed by the stress relaxation layer On the other hand, if the stress cannot be sufficiently reduced, and if it is too thick for the entire film thickness of the halftone phase shift film, the oxygen content of the retardation adjustment layer should be set to ensure a predetermined high transmittance. If there is a need to make it higher and the film stress is rather high, or the ratio of the stress relaxation layer with a low oxygen content is high, the oxygen content in the entire halftone phase shift film cannot be sufficiently increased, There are cases where a predetermined transmittance cannot be secured. Therefore, the thickness of the stress relaxation layer is preferably 5% or more, particularly 10% or more, and 50% or less, particularly 30% or less, with respect to the entire film thickness of the halftone phase shift film.

  The halftone phase shift type photomask blank of the present invention has a halftone phase shift film composed of the stress relaxation layer and the retardation adjustment layer on the transparent substrate, and between the transparent substrate and the halftone phase shift film. And the other film | membrane formed as needed in the one or both of the side spaced apart from the transparent substrate of a halftone phase shift film | membrane can be manufactured by forming into a film by the well-known method in a photomask blank.

The halftone phase shift film is preferably formed by reactive sputtering. Specifically, a transparent substrate is accommodated in a sputter chamber, a transition metal target, a transition metal silicon target, a silicon target, etc. as targets, and oxygen gas (O ₂ ), nitrogen gas (N ₂ ), oxidation as sputtering gases. A reactive gas such as nitrogen gas (N ₂ O, NO ₂ ) or a rare gas such as argon gas (Ar) is used and applied to the target according to the composition of the stress relaxation layer or retardation adjustment layer to be formed. A film can be formed by adjusting the flow rate of power and sputtering gas and performing sputtering. Then, if the sputtering conditions are sequentially changed according to the desired order of the stress relaxation layer and the retardation adjustment layer and the predetermined number of layers, and the sputtering time is set according to the thickness of each layer, the stress relaxation layer and A halftone phase shift film having a multilayer structure composed of a phase difference adjusting layer can be formed. In addition, it is preferable that sputtering pressure shall be 0.01 Pa or more and 0.5 Pa or less.

  The halftone phase shift film formed on the transparent substrate is heat-treated at a temperature of 250 ° C. or more, particularly 300 ° C. or more, 600 ° C. or less, particularly 500 ° C. or less for 2 hours or more, preferably 4 hours or more. It is preferable to apply. By performing the heat treatment, the film stress of the halftone phase shift film can be reduced. Examples of the heat treatment method include a method in which a transparent substrate on which a halftone phase shift film is formed is accommodated in a heat treatment furnace such as an electric furnace and heated at a predetermined temperature for a predetermined time. Even if the heat treatment was performed in a state where no other film was formed on the side separated from the transparent substrate of the halftone phase shift film, another film was formed on the side separated from the transparent substrate of the halftone phase shift film. It may be performed later. The upper limit of the heat treatment time is not particularly limited, but is usually 6 hours or less in consideration of the effect of reducing the film stress and the productivity.

  In addition, it is also preferable to subject the halftone phase shift film formed on the transparent substrate to a pulse irradiation with light containing infrared rays. The film stress of the halftone phase shift film can be reduced by irradiating light including infrared rays with pulses. This pulse irradiation treatment is effective when carried out in combination with the above-described heat treatment. If heat treatment is carried out before the pulse irradiation treatment is carried out, it is most effective for reducing the film stress. The pulse irradiation treatment can be performed after another film is formed on the side separated from the transparent substrate of the halftone phase shift film, but the halftone phase shift film and the transparent substrate of the halftone phase shift film are formed on the halftone phase shift film. It is preferable to carry out in a state where no other film is formed on the side to be separated because light can be directly irradiated onto the halftone phase shift film.

A flash lamp is suitable as a light source for irradiating light containing infrared rays. A flash lamp is a light source with a continuous and wide wavelength range that emits light for a short time. For example, a gas such as xenon is enclosed in a tube made of a material that allows light such as glass to pass through, and a high voltage is applied in a pulsed manner. This is a lamp that uses light generated by the light source as a light source. The energy given to the film by the pulse irradiation treatment varies depending on the composition of the film, but is preferably 15 J / cm ² or more, particularly 20 J / cm ² or more, and 35 J / cm ² or less, particularly 30 J / cm ² or less. .

  The treatment of irradiating light containing infrared rays is particularly effective for a halftone phase shift film having a transmittance in the range of 9% to 12%. On the other hand, in a halftone phase shift film having a transmittance exceeding 12%, the effect of reducing the film stress per irradiation energy becomes small, and if a large amount of energy is irradiated to compensate for this, it is economically disadvantageous. Since there are concerns about contamination due to mixing of material derived from the device in the irradiation device and adverse effects such as changes in the film quality, the halftone phase shift film having a transmittance of more than 12%, particularly when the transmittance is 15% or more The halftone phase shift film of 40% or less, particularly 30% or less is preferably subjected to heat treatment and not subjected to pulsed irradiation with light containing infrared rays.

  Specific examples of the transition metal constituting the halftone phase shift film of the present invention, that is, the transition metal constituting the stress relaxation layer and the phase difference adjusting layer, and the transition metal constituting the target used for forming the halftone phase shift film Includes molybdenum, zirconium, tungsten, titanium, hafnium, chromium, tantalum, and the like. It is preferable to use one or more selected from these transition metals, and it is particularly preferable to use molybdenum. .

  The halftone phase shift type photomask of the present invention is obtained by forming the above-described halftone phase shift film pattern comprising the stress relaxation layer and the phase difference adjusting layer on a transparent substrate. A halftone phase shift film can be manufactured from a phase shift type photomask blank by patterning by a known method applied to patterning of the film of the photomask blank. Specifically, for example, on a halftone phase shift photomask blank, a resist film is formed as necessary, the resist film is patterned by a conventional method, and the obtained resist film pattern is used as an etching mask. The underlying film is patterned by dry etching, and if necessary, the underlying film and transparent substrate are sequentially patterned by dry etching using the resist film pattern and the previously formed film pattern as an etching mask. And it can manufacture by removing an unnecessary film | membrane. The dry etching may be selected from chlorine-based dry etching, fluorine-based dry etching, etc. depending on the film composition, but fluorine-based dry etching is usually applied to the dry etching of the halftone phase shift film of the present invention. Is done.

The halftone phase shift photomask manufactured from the halftone phase shift photomask blank of the present invention is used in photolithography for forming a pattern with a half pitch of 50 nm or less, particularly 30 nm or less, particularly 20 nm or less on a substrate to be processed. This is particularly effective in pattern exposure in which a pattern is transferred to a photoresist film formed on a processed substrate with exposure light having a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm) or an F ₂ laser (wavelength 157 nm).

  In the pattern exposure using the halftone phase shift type photomask manufactured from the halftone phase shift type photomask blank of the present invention, the photomask including the pattern of the halftone phase shift film using the halftone phase shift type photomask The pattern is irradiated with exposure light, and the photomask pattern is transferred to a photoresist film that is an exposure target of the photomask pattern formed on the substrate to be processed. Irradiation of exposure light may be either exposure under dry conditions or immersion exposure. However, the halftone phase shift photomask of the present invention has an immersion exposure in which the accumulated irradiation energy increases in a relatively short time in actual production. This is particularly effective when exposing a photomask pattern using a wafer of 300 mm or more as a processing substrate by exposure.

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

[Experiment 1]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The power to be applied is 300 W, the power to be applied to the Si target is 1,700 W, the flow rate of argon gas is fixed at 18 sccm, the flow rate of nitrogen gas is fixed at 65 sccm, and the flow rate of oxygen gas is 0 sccm, 3 sccm, 6 sccm, 10 sccm, 15 sccm, respectively. As described above, halftone phase shift films made of five types of MoSiON were formed so that the phase difference with respect to exposure light (ArF excimer laser (wavelength 193 nm), the same applies hereinafter) was 177 °.

  For each of the obtained halftone phase shift films, TIR (Total Indicator Reading) after film formation was measured by a flat nesting tester (UltraFlat Type-G, manufactured by Corning Tropel) (the same applies to the following TIR measurements). The film stress was evaluated by the difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value measured before the film formation (that is, the quartz substrate). FIG. 1 shows the relationship between the oxygen content of the halftone phase shift film formed under each condition and ΔTIR. As shown in FIG. 1, the lower the oxygen content, the lower the film stress per unit phase difference.

[Example 1]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The power to be applied to the Si target is fixed to 1,700 W, the flow rate of argon gas is fixed to 18 sccm, the flow rate of nitrogen gas is fixed to 65 sccm, and the flow rates of oxygen gas are 6.6 sccm, 13.6 sccm, and 17. 6 sccm, a three-layer structure composed of MoSiON of a stress relaxation layer (thickness 28 nm), a first retardation adjustment layer (thickness 43 nm), and a second retardation adjustment layer (thickness 42 nm) in this order from the transparent substrate side A halftone phase shift film was formed. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.30 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the heat treatment from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.25 μm.

Further, irradiation with a flash lamp annealing apparatus LA3020F (Dainippon Screen Mfg. Co., Ltd., the same in the following example) is applied to the halftone phase shift film after the heat treatment so that the irradiation energy becomes 29.1 J / cm ^2. Under conditions (determined in advance by measurement with a calorimeter, the same under the following irradiation conditions), light containing infrared rays was subjected to pulse irradiation treatment to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.24 μm.

  The halftone phase shift film had a transmittance of 30% for exposure light, a phase difference of 177 °, and a film thickness of 113 nm. The molybdenum content in the stress relaxation layer is 4.2 atomic%, the silicon content is 35.9 atomic%, the oxygen content is 31.8 atomic%, the nitrogen content is 28.1 atomic%, the first phase difference Molybdenum content in the adjustment layer is 3.5 atomic%, silicon content is 32.6 atomic%, oxygen content is 49.1 atomic%, nitrogen content is 14.8 atomic%, second retardation adjustment The molybdenum content in the layer was 3.2 atomic percent, the silicon content was 31.5 atomic percent, the oxygen content was 57.1 atomic percent, and the nitrogen content was 8.2 atomic percent. Further, as an average of the whole halftone phase shift film, the molybdenum content is 3.6 atomic%, the silicon content is 33.0 atomic%, the oxygen content is 47.8 atomic%, and the nitrogen content is 15.6 atoms. %Met. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

[Comparative Example 1]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. A half-tone phase shift film of a single layer structure made of MoSiON with 300 W as the power to be applied, 1,700 W as the power applied to the Si target, 18 sccm as the flow rate of argon gas, 65 sccm as the flow rate of nitrogen gas, and 15 sccm as the flow rate of oxygen gas Was deposited. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.37 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the heat treatment from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.32 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 29.1 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.32 μm.

  The halftone phase shift film had a transmittance for exposure light of 30%, a phase difference of 177 °, and a film thickness of 114 nm. In the halftone phase shift film, the molybdenum content was 3.5 atomic%, the silicon content was 33.6 atomic%, the oxygen content was 47.5 atomic%, and the nitrogen content was 15.4 atomic%. It was. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

  When Example 1 and Comparative Example 1 are compared, the transmittance and the phase difference are the same and the film thickness is also the same. However, in any of ΔTIR after film formation, ΔTIR after heat treatment, and ΔTIR after pulse irradiation treatment The halftone phase shift film of Example 1 is superior, and as a high transmittance halftone phase shift film, a multilayer of a stress relaxation layer having a low oxygen content and a phase difference adjusting layer having a high oxygen content It can be seen that a film made of is effective in reducing film stress.

[Example 2]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The power to be applied to the Si target is 1,700 W, the argon gas flow rate is 18 sccm, the nitrogen gas flow rate is 65 sccm, and the oxygen gas flow rate is 6 sccm, 1 sccm, and 5 sccm, respectively. A halftone phase shift film having a three-layer structure composed of MoSiON of a first retardation adjustment layer (thickness 35 nm), a stress relaxation layer (thickness 11 nm), and a second retardation adjustment layer (thickness 35 nm) in order from Was deposited. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.16 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the heat treatment from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.11 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 29.1 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.09 μm.

  The transmittance of the halftone phase shift film for exposure light was 15%, the phase difference was 180 °, and the film thickness was 81 nm. The molybdenum content in the first retardation adjustment layer is 4.5 atomic%, the silicon content is 37.0 atomic%, the oxygen content is 25.3 atomic%, the nitrogen content is 33.2 atomic%, stress Molybdenum content in the relaxation layer is 5.2 atomic%, silicon content is 39.9 atomic%, oxygen content is 8.2 atomic%, nitrogen content is 46.7 atomic%, second phase difference adjustment The molybdenum content in the layer was 4.8 atomic%, the silicon content was 37.6 atomic%, the oxygen content was 21.0 atomic%, and the nitrogen content was 36.6 atomic%. Further, as an average of the whole halftone phase shift film, the molybdenum content is 4.7 atomic%, the silicon content is 37.7 atomic%, the oxygen content is 21.1 atomic%, and the nitrogen content is 36.5 atoms. %Met. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

[Comparative Example 2]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The half-tone phase of a single layer structure made of MoSiON is 300 W, the power applied to the Si target is 1,700 W, the flow rate of argon gas is 18 sccm, the flow rate of nitrogen gas is 65 sccm, and the flow rate of oxygen gas is 6.5 sccm. A shift film was formed. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the film formation from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.21 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the heat treatment from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.15 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 29.1 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.14 μm.

  The transmittance of the halftone phase shift film for exposure light was 15%, the phase difference was 180 °, and the film thickness was 81 nm. Further, the molybdenum content in the halftone phase shift film was 4.8 atomic%, the silicon content was 37.8 atomic%, the oxygen content was 21.1 atomic%, and the nitrogen content was 36.3 atomic%. It was. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

  When Example 2 and Comparative Example 2 are compared, the transmittance, phase difference, and film thickness are the same, but in any of ΔTIR after film formation, ΔTIR after heat treatment, and ΔTIR after pulse irradiation treatment, Example 2 No. 2 halftone phase shift film is superior, and as a high transmittance halftone phase shift film, a film comprising a multilayer of a stress relaxation layer having a low oxygen content and a phase difference adjusting layer having a high oxygen content However, it turns out that it is effective for reduction of a film | membrane stress.

[Example 3]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The power to be applied is 300 W, the power to be applied to the Si target is 1,700 W, the flow rate of argon gas is fixed at 18 sccm, the flow rate of nitrogen gas is fixed at 58 sccm, and the flow rate of oxygen gas is 3.5 sccm and 4.5 sccm, respectively. In order from the substrate side, a two-layer halftone phase shift film made of MoSiON as a stress relaxation layer (thickness: 37 nm) and retardation adjustment layer (thickness: 38 nm) was formed. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.23 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the heat treatment from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.18 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 26.8 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was +0.01 μm.

  The halftone phase shift film had a transmittance for exposure light of 12%, a phase difference of 177 °, and a film thickness of 75 nm. Further, the molybdenum content in the stress relaxation layer is 5.0 atomic%, the silicon content is 38.2 atomic%, the oxygen content is 13.8 atomic%, the nitrogen content is 43.0 atomic%, and the phase difference is adjusted. The molybdenum content in the layer was 5.4 atomic percent, the silicon content was 38.2 atomic percent, the oxygen content was 15.8 atomic percent, and the nitrogen content was 40.6 atomic percent. Further, as an average of the entire halftone phase shift film, the molybdenum content is 5.2 atomic%, the silicon content is 38.2 atomic%, the oxygen content is 14.9 atomic%, and the nitrogen content is 41.7 atoms. %Met. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

[Comparative Example 3]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The half-tone phase of a single layer structure made of MoSiON is 300 W, the power applied to the Si target is 1,700 W, the flow rate of argon gas is 18 sccm, the flow rate of nitrogen gas is 58 sccm, and the flow rate of oxygen gas is 4.2 sccm. A shift film was formed. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.25 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after heat treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.20 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 26.8 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.03 μm.

  The halftone phase shift film had a transmittance for exposure light of 12%, a phase difference of 177 °, and a film thickness of 75 nm. In the halftone phase shift film, the molybdenum content was 5.3 atomic%, the silicon content was 38.3 atomic%, the oxygen content was 15.6 atomic%, and the nitrogen content was 40.8 atomic%. It was. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

  When Example 3 and Comparative Example 3 are compared, the transmittance, phase difference, and film thickness are the same, but in any of ΔTIR after film formation, ΔTIR after heat treatment, and ΔTIR after pulse irradiation treatment, Example 3 No. 3 halftone phase shift film is superior, and as a high transmittance halftone phase shift film, a film comprising a multilayer of a stress relaxation layer having a low oxygen content and a phase difference adjusting layer having a high oxygen content Is effective in reducing the film stress, and in this case, the film stress can be reduced with a smaller amount of irradiation energy by pulse irradiation of light including infrared rays, and is particularly effective in reducing the film stress. I understand that.

[Example 4]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The power to be applied is 400 W, the power applied to the Si target is 1,600 W, the flow rate of argon gas is fixed at 17 sccm, the flow rate of nitrogen gas is fixed at 55 sccm, and the flow rate of oxygen gas is 3.6 sccm and 4.6 sccm, respectively. In order from the substrate side, a two-layer halftone phase shift film made of MoSiON as a stress relaxation layer (thickness: 21 nm) and a retardation adjustment layer (thickness: 54 nm) was formed. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.28 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the heat treatment from the TIR value before the film formation (that is, the quartz substrate) measured in advance was −0.21 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 23.4 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was +0.01 μm.

  The halftone phase shift film had a transmittance for exposure light of 9%, a phase difference of 177 °, and a film thickness of 75 nm. In addition, the molybdenum content in the stress relaxation layer is 6.3 atomic%, the silicon content is 38.3 atomic%, the oxygen content is 13.0 atomic%, the nitrogen content is 42.4 atomic%, and the phase difference is adjusted. The molybdenum content in the layer was 7.0 atomic%, the silicon content was 38.2 atomic%, the oxygen content was 15.0 atomic%, and the nitrogen content was 39.8 atomic%. Moreover, as an average of the whole halftone phase shift film, the molybdenum content is 6.8 atomic%, the silicon content is 38.3 atomic%, the oxygen content is 14.2 atomic%, and the nitrogen content is 40.7 atoms. %Met. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

[Comparative Example 4]
A 6025 quartz substrate with a 152 mm square and a thickness of 6.35 mm is accommodated in the chamber of the sputtering apparatus, MoSi target and Si target are used as the sputtering target, and argon gas, nitrogen gas and oxygen gas are used as the sputtering gas and applied to the MoSi target. The half-tone phase of a single layer structure made of MoSiON is 400 W, the power applied to the Si target is 1,600 W, the flow rate of argon gas is 17 sccm, the flow rate of nitrogen gas is 55 sccm, and the flow rate of oxygen gas is 4.4 sccm. A shift film was formed. About the obtained halftone phase shift film, TIR after film formation was measured. The difference (ΔTIR) obtained by subtracting the TIR value after film formation from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.31 μm.

  Next, the transparent substrate on which the halftone phase shift film was formed was subjected to heat treatment at 300 ° C. for 6 hours in a heat treatment furnace, and TIR after the heat treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after heat treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.24 μm.

Further, the light containing infrared rays is pulsed on the halftone phase shift film after the heat treatment using the flash lamp annealing apparatus in the same manner as in Example 1 under the irradiation condition where the irradiation energy is 23.4 J / cm ^2. Irradiation treatment was performed to obtain a halftone phase shift photomask blank. About the obtained halftone phase shift photomask blank, TIR after pulse irradiation treatment was measured. The difference (ΔTIR) obtained by subtracting the TIR value after the pulse irradiation treatment from the TIR value before film formation (that is, the quartz substrate) measured in advance was −0.04 μm.

  The halftone phase shift film had a transmittance for exposure light of 9%, a phase difference of 177 °, and a film thickness of 75 nm. Further, the molybdenum content in the halftone phase shift film was 6.8 atomic%, the silicon content was 37.2 atomic%, the oxygen content was 14.3 atomic%, and the nitrogen content was 41.7 atomic%. It was. Table 1 shows film formation conditions, film composition, irradiation energy amount, ΔTIR, film thickness, transmittance, and phase difference.

  When Example 4 and Comparative Example 4 are compared, the transmittance, phase difference, and film thickness are the same, but in any of ΔTIR after film formation, ΔTIR after heat treatment, and ΔTIR after pulse irradiation treatment, No. 4 halftone phase shift film is superior, and as a high transmittance halftone phase shift film, a film comprising a multilayer of a stress relaxation layer having a low oxygen content and a phase difference adjusting layer having a high oxygen content Is effective in reducing the film stress, and in this case, the film stress can be reduced with a smaller amount of irradiation energy by pulse irradiation of light including infrared rays, and is particularly effective in reducing the film stress. I understand that.

Claims (14)

A transparent substrate, and a halftone phase shift film formed on the transparent substrate and having a transmittance of 9% to 40% and a phase difference of 150 ° to 200 ° with respect to light having a wavelength of 200 nm or less Halftone phase shift photomask blank,
The halftone phase shift film is
Consisting of transition metals, silicon, oxygen and nitrogen,
The average content of transition metal is 3 atomic% or more, and one or more layers of transition metal, silicon, oxygen and nitrogen, and one or more layers of transition metal, silicon and oxygen And a multilayer composed of a phase difference adjusting layer made of nitrogen,
The stress relaxation layer has an oxygen content of 3 atomic% or more and the lowest layer, the retardation adjusting layer has an oxygen content of 5 atomic% or more, and is more than the stress relaxation layer. A halftone phase shift photomask blank characterized in that the layer is a layer higher by 2 atomic% or more.   2. The halftone phase shift photomask blank according to claim 1, wherein the halftone phase shift film is formed in contact with a transparent substrate.   The halftone phase shift type photomask blank according to claim 2, wherein the layer formed on the most transparent substrate side is the stress relaxation layer.   The halftone phase shift film is composed of three or more layers, and each phase difference adjusting layer is laminated so as to be in contact with any one of the stress relaxation layers. The halftone phase shift type photomask blank described in the item.   5. The halftone phase shift photomask blank according to claim 1, wherein the content of the transition metal is 5 atomic% or more and 10 atomic% or less.   The halftone phase shift photomask blank according to any one of claims 1 to 5, wherein the transition metal is molybdenum.   The halftone phase shift photomask blank according to any one of claims 1 to 6, wherein the transmittance of the halftone phase shift film is 9% or more and 12% or less.   The halftone phase shift photomask blank according to any one of claims 1 to 6, wherein the transmittance of the halftone phase shift film is 15% or more and 30% or less.   In photolithography for forming a pattern with a half pitch of 50 nm or less on a substrate to be processed, a halftone phase shift used for pattern exposure in which the pattern is transferred to the photoresist film formed on the substrate to be processed with exposure light having a wavelength of 200 nm or less. The halftone phase shift photomask blank according to any one of claims 1 to 8, wherein the halftone phase shift photomask blank is used for a type photomask. A transparent substrate, and a halftone phase shift film formed on the transparent substrate and having a transmittance of 9% to 40% and a phase difference of 150 ° to 200 ° with respect to light having a wavelength of 200 nm or less A method of manufacturing a halftone phase shift photomask blank,
On a transparent substrate
Consisting of transition metals, silicon, oxygen and nitrogen,
The average content of transition metal is 3 atomic% or more, and one or more layers of transition metal, silicon, oxygen and nitrogen, and one or more layers of transition metal, silicon and oxygen And a multilayer composed of a phase difference adjusting layer made of nitrogen,
The stress relaxation layer has an oxygen content of 3 atomic% or more and the lowest layer, the retardation adjusting layer has an oxygen content of 5 atomic% or more, and is more than the stress relaxation layer. A method for producing a halftone phase shift type photomask blank comprising a step of forming a halftone phase shift film which is a layer higher by 2 atomic% or more.   The halftone phase shift film has a transmittance of 9% or more and 12% or less, and includes a step of irradiating the halftone phase shift film formed on the transparent substrate with light containing infrared rays. The manufacturing method of the halftone phase shift type photomask blank of Claim 10.   Before the step of irradiating light containing infrared rays, the method further includes a step of heat-treating the halftone phase shift film formed on the transparent substrate at 250 ° C. to 600 ° C. for 2 hours or more. The method for producing a halftone phase shift photomask blank according to claim 11.   The halftone phase shift film has a transmittance of 15% or more and 30% or less, and the halftone phase shift film formed on the transparent substrate is heat treated by holding at 250 ° C. or more and 600 ° C. or less for 2 hours or more. The method for producing a halftone phase shift photomask blank according to claim 10, wherein the halftone phase shift film formed on the transparent substrate does not include a step of irradiating light containing infrared rays. Method. A transparent substrate, and a pattern of a halftone phase shift film formed on the transparent substrate and having a transmittance of 9% to 40% and a phase difference of 150 ° to 200 ° with respect to light having a wavelength of 200 nm or less A halftone phase shift photomask having
The halftone phase shift film is
Consisting of transition metals, silicon, oxygen and nitrogen,
The average content of transition metal is 3 atomic% or more, and one or more layers of transition metal, silicon, oxygen and nitrogen, and one or more layers of transition metal, silicon and oxygen And a multilayer composed of a phase difference adjusting layer made of nitrogen,
The stress relaxation layer has an oxygen content of 3 atomic% or more and the lowest layer, the retardation adjusting layer has an oxygen content of 5 atomic% or more, and is more than the stress relaxation layer. A halftone phase shift photomask characterized in that the layer is a layer higher by 2 atomic% or more.

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