JP2018124587A - Halftone phase shift mask blank, and halftone phase shift mask - Google Patents

Abstract

SOLUTION: There is provided a halftone phase shift mask blank having a halftone phase shift film constituted by a silicon-based material containing silicon and nitrogen as an essential constituent, optionally containing oxygen as an optional constituent, having a total content of silicon, nitrogen and oxygen of not less than 90 atom%, a content of silicone of 44-70 atom%, a total content of nitrogen and oxygen of 30-60 atom%, a content of oxygen of not greater than 30 atom%, a content of a transition metal of not greater than 1 atom%, and having a film thickness of not greater than 70 nm on a transparent substrate.EFFECT: A halftone phase shift mask blank can be provided, the mask blank having a thinner halftone phase shift film favorable for processing a photomask pattern, and small in pattern dimension variation degradation by irradiating with a light having a wave length of not greater than 200 nm, and secured by a phase difference necessary as a phase shift film and a transmittance necessary as a halftone film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a halftone phase shift mask blank and a halftone phase shift mask used for manufacturing a semiconductor integrated circuit or the like.

  In the field of semiconductor technology, research and development for further miniaturization of patterns is underway. In recent years, in particular, along with the high integration of large-scale integrated circuits, miniaturization of circuit patterns, thinning of wiring patterns, and miniaturization of contact hole patterns for interlayer wiring constituting cells have progressed. The demand for is getting higher and higher. As a result, in the field of manufacturing technology of photomasks used in photolithography processes during microfabrication, development of technology for forming finer and more accurate circuit patterns (mask patterns) has been required. It is coming.

  In general, reduction projection is performed when a pattern is formed on a semiconductor substrate by a photolithography technique. For this reason, the size of the pattern formed on the photomask is about four times the size of the pattern formed on the semiconductor substrate. In today's photolithography technology field, the size of a circuit pattern to be drawn is considerably less than the wavelength of light used for exposure. For this reason, when a photomask pattern is formed by simply quadrupling the size of the circuit pattern, the original shape is not transferred to the resist film on the semiconductor substrate due to the influence of light interference generated during exposure. Result.

  Therefore, there is a case where the effect of the above-described light interference or the like is reduced by making the pattern formed on the photomask more complicated than the actual circuit pattern. As such a pattern shape, for example, there is a shape in which an optical proximity effect correction (OPC: Optical Proximity Correction) is applied to an actual circuit pattern. In addition, in order to meet the miniaturization and high accuracy of patterns, technologies such as modified illumination, immersion technology, resolution enhancement technology (RET), double exposure (double patterning lithography) are also applied.

  As one of RET, a phase shift method is used. The phase shift method is a method in which a film pattern that inverts the phase by approximately 180 ° is formed on a photomask, and contrast is improved by utilizing light interference. One of the photomasks to which this is applied is a halftone phase shift mask. A halftone phase shift mask is a mask pattern of a halftone phase shift film on a substrate transparent to exposure light such as quartz, having a transmittance that does not contribute to pattern formation by inverting the phase by approximately 180 °. Formed. As a halftone phase shift mask, a mask having a halftone phase shift film made of molybdenum silicide oxide (MoSiO) or molybdenum silicide oxynitride (MoSiON) has been proposed (Japanese Patent Laid-Open No. 7-140635 (patent). Reference 1)).

  Also, in order to obtain a finer image by photolithography technology, an exposure light source having a shorter wavelength has been used. In the current state-of-the-art practical processing process, the exposure light source is a KrF excimer laser beam. It has shifted from (248 nm) to ArF excimer laser light (193 nm). However, it has been found that using higher energy ArF excimer laser light causes mask damage that was not seen with KrF excimer laser light. One of the problems is that when a photomask is continuously used, a foreign growth defect is generated on the photomask. This growth defect is called haze, and the cause was originally thought to be the growth of ammonium sulfate crystals on the surface of the mask pattern, but now it is also considered that organic matter is involved.

  As a countermeasure against the haze problem, for example, Japanese Patent Laid-Open No. 2008-276002 (Patent Document 2) discloses a predetermined stage for a growth defect that occurs when an ArF excimer laser beam is irradiated to a photomask for a long time. It is shown that the photomask can be used continuously by cleaning the photomask.

  Further, it has been reported that as the exposure dose of ArF excimer laser light in pattern transfer increases, damage different from haze occurs in the photomask, and the pattern size of the mask changes according to the cumulative amount of irradiation energy. (Thomas Faure et al., “Characterization of binary mask and attenuated phase shift mask blanks for 32 nm mask fabrication”, Proc. Of SPIE, vol. 7122, pp712209-1 to 712209-12 (Non-patent Document 1)). This is because, when ArF excimer laser light is irradiated for a long time, the cumulative irradiation energy amount increases, and a layer made of a material considered to be an oxide of the pattern material grows outside the film pattern, and the pattern width changes. It is. In addition, this damaged mask has been shown not to recover by cleaning with aqueous ammonia / hydrogen peroxide used to remove the above-mentioned haze, or cleaning with sulfuric acid / hydrogen peroxide. I think that.

  Further, according to the report by Thomas Faure et al. (Non-Patent Document 1), in the halftone phase shift mask which is a mask technique useful for increasing the depth of focus in pattern exposure of a circuit, the ArF excimer laser beam is particularly useful. It has been pointed out that deterioration due to pattern dimension fluctuation (hereinafter referred to as pattern dimension fluctuation deterioration) accompanied by alteration of a transition metal silicon-based material film such as a MoSi-based material film due to irradiation is large. Therefore, in order to use an expensive photomask for a long time, it is necessary to cope with deterioration in pattern dimension variation caused by irradiation with ArF excimer laser light.

JP-A-7-140635 JP 2008-276002 A JP 2004-133029 A JP 2007-33469 A JP 2007-233179 A JP 2007-2441065 A

Thomas Faure et al., “Characterization of binary mask and attenuated phase shift mask blanks for 32nm mask fabrication”, Proc. Of SPIE, vol. 7122, pp712209-1 to 712209-12

  A thinner phase shift film is advantageous not only for pattern formation but also for reducing three-dimensional effects. Therefore, a thinner film is required in order to form a finer pattern in photolithography.

  Pattern dimension fluctuation deterioration due to irradiation with short wavelength light such as ArF excimer laser light is not likely to occur when light is irradiated in a dry air atmosphere, as is clarified in the report by Thomas Faure et al. Therefore, as a new measure for preventing deterioration of pattern dimension fluctuation, a method of performing exposure in dry air is conceivable. However, the control in the dry air atmosphere requires an additional device and additionally requires countermeasures against static electricity, leading to an increase in cost. Therefore, it is necessary to enable long-time exposure in a normal atmosphere (for example, about 45% humidity) in which humidity is not completely removed.

  In addition, in a photomask used for lithography using ArF excimer laser light as a light source, a transition metal silicon-based material is conventionally used in the halftone phase shift film, and a silicon-based material containing molybdenum is usually used. . The main constituent elements of this transition metal silicon-based material are transition metal and silicon, and further, those containing nitrogen and / or oxygen as light elements (for example, JP-A-7-140635 (Patent Document 1)). is there. As the transition metal, molybdenum, zirconium, tantalum, tungsten, titanium, or the like is used. In particular, molybdenum is generally used (for example, JP-A-7-140635 (Patent Document 1)). In some cases, a transition metal is added (Japanese Patent Laid-Open No. 2004-133029 (Patent Document 3)). In addition, a transition metal silicon-based material is also used for the light shielding film, and a silicon-based material containing molybdenum is usually used. However, when a large amount of high-energy light is irradiated onto a photomask using such a transition metal silicon-based material, the deterioration of pattern dimension variation due to irradiation with high-energy light is large, and the service life of the photomask is required. It will be shorter.

  Deterioration of pattern dimension variation that changes the line width of the photomask pattern used for exposure due to irradiation of the photomask pattern of the halftone phase shift mask with short wavelength light such as ArF excimer laser light is a serious problem. is there. The permissible limit of the pattern width varies depending on the type of photomask pattern, particularly the applied pattern rule. In addition, if there are some fluctuations, the exposure conditions may be corrected and the irradiation conditions of the exposure apparatus may be reset and used. However, in the exposure for forming a semiconductor circuit with a 22 nm pattern rule, for example, The variation of the mask pattern line width needs to be approximately ± 5 nm or less. However, when the change amount of the pattern width is large, there is a possibility that the change amount has a distribution in the plane of the photomask. Further, by further miniaturization, an extremely fine auxiliary pattern of 100 nm or less is formed on the mask. For this reason, a halftone phase shift mask film that can be repeatedly exposed is required because the pattern dimension variation deterioration is extremely small due to pattern miniaturization on these masks and an increase in mask processing cost due to complicated mask patterns. The

  The present invention has been made in order to solve the above problems, and as a halftone phase shift film that can cope with pattern miniaturization, while ensuring necessary phase difference and transmittance, pattern formation and three-dimensional When performing pattern exposure using short-wavelength light with a wavelength of 200 nm or less, such as an ArF excimer laser, which is advantageous in reducing effects, etc. An object is to provide a halftone phase shift mask blank and a halftone phase shift mask having a halftone phase shift film in which deterioration of pattern dimension variation accompanied by a change in film quality of a photomask due to irradiation light is suppressed even in many cases. And

  The inventors of the present invention have ensured the phase difference and transmittance necessary for a halftone phase shift film, and have a thin film thickness and a small deterioration in pattern dimension variation with respect to ArF excimer laser light irradiation. First, a halftone phase shift film containing a transition metal such as molybdenum, which is commonly used as a halftone phase shift film, was studied. However, in the case of a halftone phase shift film, when a transition metal or oxygen is added, the refractive index of the film at a predetermined transmittance decreases depending on the amount added, so that the phase difference necessary for the phase shift film is secured. It has been found that the film needs to be thick, and further, the pattern dimension fluctuation deterioration due to irradiation with ArF excimer laser light increases.

  Therefore, in order to solve the above problems, the present inventors have intensively studied a halftone phase shift film that suppresses the transition metal content as much as possible. As a result, the halftone phase shift film has silicon and nitrogen as essential components. May contain oxygen as an optional component, the total content of silicon, nitrogen and oxygen is 90 atomic% or more, the content of silicon is 30 to 70 atomic%, the total content of nitrogen and oxygen By forming the silicon-based material having a rate of 30 to 60 atomic%, an oxygen content of 30 atomic% or less, and a transition metal content of 1 atomic% or less, the film thickness is set to 70 nm or less. It has been found that a halftone phase shift film having a phase difference of 150 to 200 ° and a transmittance of 3% to 30% can be formed with respect to light of 200 nm or less.

  Such a halftone phase shift film has a small deterioration in pattern dimension variation when irradiated with short-wavelength light of 200 nm or less such as ArF excimer laser light, and has a short wavelength of 200 nm or less such as ArF excimer laser light. It is excellent in the resistance to film quality change due to the cumulative irradiation of light, and by configuring the halftone phase shift film in this way, a halftone phase shift mask having a halftone phase shift film pattern is used. A main photomask pattern having a width of about 100 to 200 nm, which is necessary in photolithography for forming a transfer pattern having a half pitch of 50 nm or less with exposure light having a wavelength of 200 nm or less on a substrate to be processed For exposure using halftone phase shift mask It found that a halftone phase shift mask blank is obtained which gives less likely to occur halftone phase shift mask of kicking pattern size variation degradation, leading to the completion of the present invention.

Accordingly, the present invention provides the following halftone phase shift mask blank and halftone phase shift mask.
Claim 1:
A halftone having a halftone phase shift film composed of a single layer or a plurality of layers on a transparent substrate and having a wavelength of 200 nm or less, a phase shift amount of 150 to 200 °, and a transmittance of 3% to less than 20%. A phase shift mask blank,
Each of the single layer or the plurality of layers constituting the halftone phase shift film may contain silicon and nitrogen as essential components and oxygen as an optional component, and the halftone phase shift When the film is composed of a single layer, the whole is composed of a plurality of layers. When the film is composed of a plurality of layers, 60% or more of the film thickness is 90% by atom or more of the total content of silicon, nitrogen and oxygen. Is 44 to 70 atomic percent, the total content of nitrogen and oxygen is 30 to 60 atomic percent, the oxygen content is 30 atomic percent or less, and the transition metal content is 1 atomic percent or less. Consists of silicon-based material,
A halftone phase shift mask blank, wherein the film thickness of the halftone phase shift film is 70 nm or less.
Claim 2:
2. The halftone phase shift mask according to claim 1, wherein the silicon-based material is composed of a silicon-based material that does not contain oxygen and has a total content of silicon and nitrogen of 95 atomic% or more. blank.
Claim 3:
The halftone phase shift mask blank according to claim 1 or 2, further comprising a second layer composed of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film. .
Claim 4:
The second layer is a processing auxiliary film functioning as a hard mask in forming a light shielding film, a combination of a light shielding film and an antireflection film, or patterning of the halftone phase shift film. Halftone phase shift mask blank.
Claim 5:
4. The halftone phase shift mask blank according to claim 3, further comprising a third layer composed of a single layer or a plurality of layers made of a material containing silicon on the second layer.
Claim 6:
The second layer is a light shielding film, or a combination of a light shielding film and an antireflection film, and the third layer is a processing auxiliary film that functions as a hard mask in pattern formation of the second layer. The halftone phase shift mask blank according to claim 5.
Claim 7:
The second layer is a processing auxiliary film that functions as a hard mask in the pattern formation of the halftone phase shift film and also functions as an etching stopper in the pattern formation of the third layer. 6. The halftone phase shift mask blank according to claim 5, wherein the halftone phase shift mask blank is a light shielding film or a combination of a light shielding film and an antireflection film.
Claim 8:
6. The halftone phase shift mask blank according to claim 5, further comprising a fourth layer composed of a single layer or a plurality of layers made of a material containing chromium on the third layer.
Claim 9:
The second layer is a processing auxiliary film that functions as a hard mask in the pattern formation of the halftone phase shift film and also functions as an etching stopper in the pattern formation of the third layer. The light-shielding film, or a combination of a light-shielding film and an antireflection film, wherein the fourth layer is a processing auxiliary film that functions as a hard mask in pattern formation of the third layer. 8. A halftone phase shift mask blank according to 8.
Claim 10:
The halftone phase shift mask formed using the halftone phase shift mask blank of any one of Claims 1 thru | or 9.
Further, the present invention relates to the following halftone phase shift mask blank and halftone phase shift mask.
[1] A halftone phase shift film comprising a single layer or a plurality of layers on a transparent substrate, having a phase shift amount of 150 to 200 ° and a transmittance of 3% to 30% with light having a wavelength of 200 nm or less. A halftone phase shift mask blank having
Each of the single layer or the plurality of layers constituting the halftone phase shift film may contain silicon and nitrogen as essential components and oxygen as an optional component, and the halftone phase shift When the film is composed of a single layer, the whole is composed of a plurality of layers. When the film is composed of a plurality of layers, 60% or more of the film thickness is 90% by atom or more of the total content of silicon, nitrogen and oxygen. Is 30 to 70 atomic%, the total content of nitrogen and oxygen is 30 to 60 atomic%, the oxygen content is 30 atomic% or less, and the transition metal content is 1 atomic% or less. Consists of silicon-based material,
A halftone phase shift mask blank, wherein the film thickness of the halftone phase shift film is 70 nm or less.
[2] Silicon in which the transmittance of the halftone phase shift film is 3% or more and less than 20%, the silicon-based material does not contain oxygen, and the total content of silicon and nitrogen is 95 atomic% or more The halftone phase shift mask blank according to [1], which is made of a system material.
[3] The half of [1] or [2], further comprising a second layer composed of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film. Tone phase shift mask blank.
[4] The second layer is a processing auxiliary film that functions as a hard mask in a light shielding film, a combination of a light shielding film and an antireflection film, or a pattern formation of the halftone phase shift film. [3] The halftone phase shift mask blank described in [3].
[5] The halftone phase shift mask according to [3], further comprising a third layer composed of a single layer or a plurality of layers made of a material containing silicon on the second layer. blank.
[6] The processing auxiliary film in which the second layer is a light shielding film or a combination of a light shielding film and an antireflection film, and the third layer functions as a hard mask in patterning the second layer. The halftone phase shift mask blank according to [5], wherein
[7] The second layer is a processing auxiliary film that functions as a hard mask in the pattern formation of the halftone phase shift film and functions as an etching stopper in the pattern formation of the third layer. The halftone phase shift mask blank according to [5], wherein the layer is a light shielding film or a combination of a light shielding film and an antireflection film.
[8] The halftone phase shift mask according to [5], further comprising a fourth layer composed of a single layer or a plurality of layers made of a material containing chromium on the third layer. blank.
[9] The second layer is a processing auxiliary film that functions as a hard mask in pattern formation of the halftone phase shift film and functions as an etching stopper in pattern formation of the third layer. The layer is a light shielding film or a combination of a light shielding film and an antireflection film, and the fourth layer is a processing auxiliary film that functions as a hard mask in pattern formation of the third layer. The halftone phase shift mask blank according to [8].
[10] A halftone phase shift mask formed using the halftone phase shift mask blank according to any one of [1] to [9].

  According to the present invention, it is a thin halftone phase shift film that is advantageous in the processing of a photomask pattern, and is a halftone phase shift film that has a small deterioration in pattern dimension variation when irradiated with light having a wavelength of 200 nm or less. A halftone phase shift mask blank and a halftone phase shift mask including a halftone phase shift film in which a phase difference necessary as a phase shift film and a transmittance necessary as a halftone film are ensured can be provided. The halftone phase shift mask of the present invention is a long-life halftone phase shift mask that meets the demands for further pattern miniaturization and higher accuracy in photolithography, and has little deterioration in pattern dimension variation with respect to cumulative exposure. It is.

It is sectional drawing which shows an example of the halftone phase shift mask blank and halftone phase shift mask of this invention. It is sectional drawing which shows the other example of the halftone phase shift mask blank of this invention.

Hereinafter, the present invention will be described in more detail.
The halftone phase shift mask blank (halftone phase shift type photomask blank) of the present invention is a halftone phase comprising a single layer or a plurality of layers (that is, two or more layers) formed on a transparent substrate such as a quartz substrate. It has a shift film. In the present invention, the transparent substrate is preferably a transparent substrate called a 6025 substrate having a 6-inch square and a thickness of 25 millimeters, which is defined in the SEMI standard. When an SI unit system is used, it is usually a 152 mm square. And a transparent substrate having a thickness of 6.35 mm. The halftone phase shift mask (halftone phase shift type photomask) of the present invention has a mask pattern (photomask pattern) of a halftone phase shift film.

  FIG. 1A is a cross-sectional view showing an example of the halftone phase shift mask blank of the present invention. The halftone phase shift mask blank 100 includes a transparent substrate 10 and a halftone formed on the transparent substrate 10. A phase shift film 1. FIG. 1B is a cross-sectional view showing an example of the halftone phase shift mask of the present invention. The halftone phase shift mask 101 includes a transparent substrate 10 and a halftone formed on the transparent substrate 10. And a phase shift film pattern 11.

  The halftone phase shift film may be composed of a single layer so as to satisfy the phase difference and transmittance required as a halftone phase shift film.For example, in order to satisfy a predetermined surface reflectance, It is also preferable to include a plurality of layers so as to include a layer having antireflection functionality and to satisfy the phase difference and transmittance required as a halftone phase shift film as a whole.

  In any case of a single layer and a plurality of layers, each layer may be formed such that the composition continuously changes in the thickness direction. Further, when the halftone phase shift film is composed of a plurality of layers, it may be a combination of two or more layers selected from layers having different constituent elements and layers having the same constituent elements but different composition ratios, and the plurality of layers are composed of three or more layers. In this case, the same layers can be combined if they are not adjacent layers.

  The halftone phase shift film of the present invention has a predetermined film thickness with respect to light having a wavelength of 200 nm or less, particularly exposure light of ArF excimer laser light (wavelength 193 nm) used in photolithography using a halftone phase shift mask. Thus, the film provides a predetermined phase shift amount (phase difference) and a predetermined transmittance.

  The overall thickness of the halftone phase shift film of the present invention is preferably 70 nm or less, more preferably 62 nm or less, because the thinner the easier it is to form a fine pattern. On the other hand, the lower limit of the film thickness of the halftone phase shift film is set in a range in which necessary optical characteristics can be obtained with respect to light having a wavelength of 200 nm or less, which is an exposure wavelength. It becomes.

  The phase difference with respect to the exposure light of the halftone phase shift film of the present invention is the boundary between the part where the halftone phase shift film exists (halftone phase shift part) and the part where the halftone phase shift film does not exist, respectively. The phase difference of the exposure light passing through the exposure light may interfere with the exposure light to increase the contrast, and the phase difference may be 150 to 200 °. In a general halftone phase shift film, the phase difference is set to approximately 180 °. However, from the viewpoint of increasing the contrast described above, the phase difference is not limited to approximately 180 °, and the phase difference is 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 a phase difference close to 180 ° is more effective from the viewpoint of obtaining higher contrast, and it is preferable that the phase difference is 160 to 190 °, particularly 175 to 185 °, and particularly about 180 °. .

  The transmittance of the halftone phase shift film of the present invention with respect to exposure light is preferably 3% or more, particularly preferably 5% or more, and preferably 30% or less.

  In the halftone phase shift film of the present invention, the refractive index n with respect to the exposure light is 2.4 or more, particularly 2.5, within the range satisfying the above-mentioned predetermined phase difference, predetermined transmittance, and predetermined film thickness. As mentioned above, it is especially preferable that it is 2.6 or more. By reducing the oxygen content of the halftone phase shift film, preferably not containing oxygen, or lowering the transition metal content, preferably not containing a transition metal, the refractive index n of the film is reduced. In addition, the thickness of the film can be made thinner after securing the necessary phase difference as a phase shift film, and further, pattern dimension fluctuation deterioration due to irradiation with light having a wavelength of 200 nm or less can be reduced. Can be suppressed. The refractive index n is higher as the oxygen content is lower, and as the refractive index n is higher, the necessary phase difference can be obtained with a thinner film. Therefore, when the halftone phase shift film is configured as a single layer, In this single layer, the refractive index n is preferably 2.4 or more, particularly 2.5 or more, particularly 2.6 or more. On the other hand, when the halftone phase shift film is composed of a plurality of layers, it is 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, particularly preferably 100% of the total film thickness. Thus, the refractive index n is preferably 2.4 or more, particularly 2.5 or more, and particularly 2.6 or more.

  In the halftone phase shift film of the present invention, the extinction coefficient k with respect to the exposure light is 0.4 or more within the range satisfying the above-mentioned predetermined phase difference, predetermined transmittance, and predetermined film thickness. It is preferably 6 or more and 0.7 or less, particularly preferably 0.65 or less. When the halftone phase shift film is composed of a single layer, the extinction coefficient k may be 0.4 or more, particularly 0.6 or more, and 0.7 or less, particularly 0.65 or less. preferable. On the other hand, when the halftone phase shift film is composed of a plurality of layers, it is 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, particularly preferably 100% of the total film thickness. Thus, the extinction coefficient k is preferably 0.1 or more, particularly 0.2 or more, and 0.7 or less, particularly 0.65 or less.

  In the halftone phase shift film of the present invention, each of a single layer or a plurality of layers constituting the halftone phase shift film is made of a silicon-based material. The silicon-based material contains silicon and nitrogen as essential components, and may contain oxygen as an optional component. The content of elements other than these is allowed as long as the amount of impurities, but in particular, the content of transition metals (for example, molybdenum, zirconium, tungsten, titanium, hafnium, chromium, tantalum, etc.) is 1 atomic% or less. The transition metal is preferably not contained.

  When the halftone phase shift film of the present invention is composed of a single layer, the entire monolayer is composed of a plurality of layers. When a surface oxide layer to be described later is provided, the surface oxide layer is excluded. The total of silicon, nitrogen and oxygen contained in the silicon-based material is 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably 100% (that is, the whole). It is preferable that the content of silicon (content of silicon and oxygen when oxygen is not included) is 90 atomic% or more, particularly 95 atomic% or more.

  When the halftone phase shift film of the present invention is composed of a single layer, the entire monolayer is composed of a plurality of layers. When a surface oxide layer to be described later is provided, the surface oxide layer is excluded. 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably 100% (that is, the total), the silicon content in the silicon-based material is 30 atoms. % Or more, particularly 40 atom% or more, preferably 70 atom% or less, particularly 55 atom% or less, and particularly preferably 50 atom% or less. In particular, when the halftone phase shift film has a low transmittance (for example, 3% or more and less than 20%, particularly 3% or more and 12% or less, especially 3% or more and less than 10%), silicon contained in the silicon-based material The ratio is preferably 40 atomic% or more, particularly 44 atomic% or more, 70 atomic% or less, particularly 55 atomic% or less, particularly 50 atomic% or less, and the halftone phase shift film has a high transmittance (for example, In the case of 20% or more and 30% or less, the silicon content in the silicon-based material is preferably 30 atomic% or more, particularly 40 atomic% or more, and 55 atomic% or less, particularly 45 atomic% or less.

  When the halftone phase shift film of the present invention is composed of a single layer, the entire monolayer is composed of a plurality of layers. When a surface oxide layer to be described later is provided, the surface oxide layer is excluded. The total content of nitrogen and oxygen contained in the silicon-based material is 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, particularly preferably 100% (that is, the whole) The ratio is preferably 30 atomic% or more, particularly 45 atomic% or more, particularly 50 atomic% or more, and preferably 60 atomic% or less, particularly 55 atomic% or less.

  When the halftone phase shift film of the present invention is composed of a single layer, the entire monolayer is composed of a plurality of layers. When a surface oxide layer to be described later is provided, the surface oxide layer is excluded. The content of nitrogen contained in the silicon-based material is 10 atoms at 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, particularly preferably 100% (ie, the whole) of % Or more, particularly 40 atom% or more, preferably 60 atom% or less, particularly preferably 55 atom% or less. In particular, when the halftone phase shift film has a low transmittance (for example, 3% or more and less than 20%, particularly 3% or more and 12% or less, especially 3% or more and less than 10%), the inclusion of nitrogen contained in the silicon-based material The ratio is preferably 40 atomic% or more, particularly 44 atomic% or more, particularly 50 atomic% or more, preferably 60 atomic% or less, particularly 56 atomic% or less, and the halftone phase shift film has a high transmittance (for example, 20% or more and 30% or less), it is preferable that the content of nitrogen contained in the silicon-based material is 10 atomic% or more, particularly 40 atomic% or more, and 60 atomic% or less, particularly 55 atomic% or less.

  When the halftone phase shift film of the present invention is composed of a single layer, the entire monolayer is composed of a plurality of layers. When a surface oxide layer to be described later is provided, the surface oxide layer is excluded. 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably 100% (that is, the whole), the content of oxygen contained in the silicon-based material is 30%. It is preferably at most atomic percent, particularly at most 6 atomic percent. In particular, when the halftone phase shift film has a high transmittance (for example, 20% or more and 30% or less), it is preferably 30 atomic% or less, more preferably 25 atomic% or less, and the halftone phase shift film has a low transmittance. In the case of a ratio (for example, 3% or more and less than 20%, particularly 3% or more and 12% or less, especially 3% or more and less than 10%), preferably 6 atomic% or less, more preferably 3.5 atomic% or less, and still more preferably Is 1 atomic% or less.

  When the halftone phase shift film of the present invention is composed of a single layer, the entire monolayer is composed of a plurality of layers. When a surface oxide layer to be described later is provided, the surface oxide layer is excluded. 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, particularly preferably 100% (ie, the whole) of transition metals contained in silicon-based materials (for example, molybdenum, Zirconium, tungsten, titanium, hafnium, chromium, tantalum, etc.) content is preferably 1 atomic% or less. The silicon-based material may not contain a transition metal, but may contain 0.01 atomic% or more of a transition metal in order to improve the electric resistance of the film.

  Specifically, as the silicon-based material, a silicon-based material consisting only of silicon and nitrogen (ie, silicon nitride (SiN)), or a silicon-based material consisting only of silicon, nitrogen and oxygen (ie, silicon oxynitride (SiON) )).

  The silicon-based material of the halftone phase shift film of the present invention contains silicon, nitrogen and oxygen, and a silicon-based material having a total content of silicon, nitrogen and oxygen of 95 atomic% or more, particularly silicon, nitrogen and If the silicon-based material composed of only oxygen is used, the halftone phase shift film having the predetermined phase difference and the predetermined film thickness described above is obtained when the transmittance of the halftone phase shift film is in the range of 20% to 30%. This is preferable.

  Furthermore, in order to reduce the thickness of the halftone phase shift film, it is preferable that the oxygen content is low, and it is more preferable that oxygen is not included. From this point of view, the halftone phase shift film is preferably made of a silicon-based material that does not contain oxygen. Therefore, the silicon-based material of the halftone phase shift film of the present invention contains silicon and nitrogen, does not contain oxygen, and a silicon-based material in which the total content of silicon and nitrogen is 95 atomic% or more, in particular, By using a silicon-based material consisting only of silicon and nitrogen, the halftone phase shift film having a predetermined phase difference and a predetermined film thickness described above in a range where the transmittance of the halftone phase shift film is 3% or more and less than 20%. Is preferable.

The halftone phase shift film of the present invention can be formed by applying a known film formation method, but is preferably formed by a sputtering method that can easily obtain a film having excellent homogeneity. Any method of RF sputtering can be used. The target and the sputtering gas are appropriately selected according to the layer configuration and composition. As the target, a silicon target, a silicon nitride target, a target including both silicon and silicon nitride, or the like may be used. The content of nitrogen and oxygen is a sputtering gas that includes a reactive gas such as a gas containing nitrogen, a gas containing oxygen, a gas containing nitrogen and oxygen, and a gas containing carbon as necessary. It can be adjusted by adjusting and reactive sputtering. Specifically, nitrogen gas (N ₂ gas), oxygen gas (O ₂ gas), nitrogen oxide gas (N ₂ O gas, NO gas, NO ₂ gas) or the like can be used as the reactive gas. Further, as the sputtering gas, helium gas, neon gas, argon gas, or the like can be used as a rare gas.

  When the halftone phase shift film is composed of a plurality of layers, a surface oxide layer is provided as the outermost surface layer on the surface side (side away from the transparent substrate) in order to suppress the film quality change of the halftone phase shift film. Can do. The oxygen content of the surface oxide layer may be 20 atomic% or more, and may be 50 atomic% or more. As a method of forming the surface oxide layer, specifically, in addition to the oxidation by atmospheric oxidation (natural oxidation), as a method of forcibly oxidizing, a method of treating a silicon-based material film with ozone gas or ozone water, A method of heating to 300 ° C. or higher by oven heating, lamp annealing, laser heating or the like in an oxygen-existing atmosphere such as an oxygen gas atmosphere can be given. The thickness of the surface oxide layer is preferably 10 nm or less, particularly 5 nm or less, and particularly preferably 3 nm or less. Usually, the effect as an oxide layer is obtained when the thickness is 1 nm or more. The surface oxide layer can be formed by increasing the amount of oxygen in the sputtering process. However, in order to obtain a layer with fewer defects, it is preferable to form the surface oxide layer by the above-described atmospheric oxidation or oxidation treatment.

  A second layer composed of a single layer or a plurality of layers can be provided on the halftone phase shift film of the halftone phase shift mask blank of the present invention. The second layer is usually provided adjacent to the halftone phase shift film. Specific examples of the second layer include a light shielding film, a combination of a light shielding film and an antireflection film, and a processing auxiliary film that functions as a hard mask in pattern formation of a halftone phase shift film. When a third layer to be described later is provided, the second layer can be used as a processing auxiliary film (etching stopper film) that functions as an etching stopper in pattern formation of the third layer. As the material for the second layer, a material containing chromium is suitable.

  Specific examples of such a halftone phase shift mask blank include those shown in FIG. FIG. 2A is a cross-sectional view showing an example of the halftone phase shift mask blank of the present invention. The halftone phase shift mask blank 100 includes a transparent substrate 10 and a halftone formed on the transparent substrate 10. A phase shift film 1 and a second layer 2 formed on the halftone phase shift film 1 are provided.

  In the halftone phase shift mask blank of the present invention, a light shielding film can be provided as the second layer on the halftone phase shift film. In addition, a light shielding film and an antireflection film can be provided in combination as the second layer. By providing the second layer including the light shielding film, the halftone phase shift mask can be provided with a region that completely shields the exposure light. The light shielding film and the antireflection film can be used as a processing auxiliary film in etching. There are many reports (for example, JP 2007-33469 A (Patent Document 4), JP 2007-233179 A (Patent Document 5), etc.) regarding the film configuration and materials of the light shielding film and the antireflection film. As a preferable film configuration of a combination of a light shielding film and an antireflection film, for example, a light shielding film made of a material containing chromium is provided, and further, an antireflection film made of a material containing chromium that reduces reflection from the light shielding film is provided. Etc. Both the light shielding film and the antireflection film may be composed of a single layer or a plurality of layers. Examples of the material containing chromium for the light shielding film and the antireflection film include chromium alone, chromium oxide (CrO), chromium nitride (CrN), chromium carbide (CrC), chromium oxynitride (CrON), and chromium oxide carbide (CrOC). ), Chromium nitride carbide (CrNC), chromium oxynitride carbide (CrONC), and the like.

  When the second layer is a light shielding film or a combination of a light shielding film and an antireflection film, the chromium content in the chromium compound of the light shielding film is 40 atomic% or more, particularly 60 atomic% or more and less than 100 atomic%. In particular, it is preferably 99 atomic% or less, particularly 90 atomic% or less. The oxygen content is 0 atom% or more, preferably 60 atom% or less, particularly preferably 40 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, and particularly preferably 40 atomic% or less. When the etching rate needs to be adjusted, it is preferably 1 atomic% or more. The carbon content is 0 atom% or more, preferably 20 atom% or less, particularly preferably 10 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably 95 atomic% or more, particularly 99 atomic% or more, and particularly preferably 100 atomic%.

  Further, when the second layer is a combination of a light shielding film and an antireflection film, the antireflection film is preferably a chromium compound, and the chromium content in the chromium compound is 30 atomic% or more, particularly 35 atomic%. Above, it is preferable that it is 70 atomic% or less, especially 50 atomic% or less. The oxygen content is preferably 60 atomic percent or less, more preferably 1 atomic percent or more, and particularly preferably 20 atomic percent or more. The nitrogen content is preferably 50 atom% or less, particularly preferably 30 atom% or less, more preferably 1 atom% or more, and particularly preferably 3 atom% or more. The carbon content is 0 atom% or more, preferably 20 atom% or less, and particularly preferably 5 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably 95 atomic% or more, particularly 99 atomic% or more, and particularly preferably 100 atomic%.

  When the second layer is a light shielding film or a combination of a light shielding film and an antireflection film, the film thickness of the second layer is usually 20 to 100 nm, preferably 40 to 70 nm. The total optical density of the halftone phase shift film and the second layer with respect to exposure light having a wavelength of 200 nm or less is preferably 2.0 or more, particularly 2.5 or more, particularly 3.0 or more. .

  A third layer composed of a single layer or a plurality of layers can be provided on the second layer of the halftone phase shift mask blank of the present invention. The third layer is usually provided adjacent to the second layer. Specific examples of the third layer include a processing auxiliary film that functions as a hard mask in the pattern formation of the second layer, a light shielding film, and a combination of a light shielding film and an antireflection film. As the material of the third layer, a material containing silicon is preferable, and a material not containing chromium is particularly preferable.

  Specific examples of such a halftone phase shift mask blank include those shown in FIG. FIG. 2B is a cross-sectional view showing an example of the halftone phase shift mask blank of the present invention. The halftone phase shift mask blank 100 includes a transparent substrate 10 and a halftone formed on the transparent substrate 10. A phase shift film 1, a second layer 2 formed on the halftone phase shift film 1, and a third layer 3 formed on the second layer 2 are provided.

When the second layer is a light shielding film or a combination of a light shielding film and an antireflection film, a processing auxiliary film (etching mask film) that functions as a hard mask in pattern formation of the second layer is used as the third layer. Can be provided. When a fourth layer described later is provided, the third layer can be used as a processing auxiliary film (etching stopper film) that functions as an etching stopper in pattern formation of the fourth layer. This processing auxiliary film is a material having etching characteristics different from those of the second layer, for example, a material resistant to chlorine-based dry etching applied to etching of a material containing chromium, specifically, SF ₆ , CF _4, etc. It is preferable to use a material containing silicon that can be etched with a fluorine-based gas. Specifically, as a material containing silicon, silicon alone, a material containing silicon and one or both of nitrogen and oxygen, a material containing silicon and a transition metal, silicon, one or both of nitrogen and oxygen, transition Examples thereof include silicon compounds such as materials containing metals, and examples of transition metals include molybdenum, tantalum, and zirconium.

  When the third layer is a processing auxiliary film, the processing auxiliary film is preferably a silicon compound, and the silicon content in the silicon compound is 20 atomic% or more, particularly 33 atomic% or more, and 95 atomic% or less. In particular, it is preferably 80 atomic% or less. The nitrogen content is 0 atom% or more, preferably 50 atom% or less, particularly preferably 30 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. The oxygen content is 0 atomic% or more, particularly 20 atomic% or more, preferably 70 atomic% or less, particularly 66 atomic% or less, and when the etching rate needs to be adjusted, it is 1 atomic% or more. It is preferable. The content of the transition metal is 0 atomic% or more and preferably 35 atomic% or less, particularly preferably 20 atomic% or less. When the transition metal is contained, it is preferably 1 atomic% or more. In this case, the total content of silicon, oxygen, nitrogen and transition metal is preferably 95 atomic% or more, particularly 99 atomic% or more, and particularly preferably 100 atomic%.

  When the second layer is a light shielding film or a combination of a light shielding film and an antireflection film, and the third layer is a processing aid film, the thickness of the second layer is usually 20 to 100 nm, preferably 40 to 70 nm. The thickness of the third layer is usually 1 to 30 nm, preferably 2 to 15 nm. The total optical density of the halftone phase shift film and the second layer with respect to exposure light having a wavelength of 200 nm or less is preferably 2.0 or more, particularly 2.5 or more, particularly 3.0 or more. .

  Further, when the second layer is a processing auxiliary film, a light shielding film can be provided as the third layer. In addition, a light shielding film and an antireflection film can be provided in combination as the third layer. In this case, the second layer is a processing auxiliary film (etching mask film) that functions as a hard mask in the pattern formation of the halftone phase shift film, and a processing auxiliary film that functions as an etching stopper in the pattern formation of the third layer. It can also be used as (etching stopper film). An example of the processing auxiliary film is a film made of a material containing chromium as disclosed in Japanese Patent Application Laid-Open No. 2007-244105 (Patent Document 6). The processing auxiliary film may be composed of a single layer or a plurality of layers. The processing auxiliary film containing chromium includes chromium alone, chromium oxide (CrO), chromium nitride (CrN), chromium carbide (CrC), chromium oxynitride (CrON), chromium oxide carbide (CrOC), chromium Examples thereof include chromium compounds such as nitrided carbide (CrNC) and chromium oxynitride carbide (CrONC).

  When the second layer is a processing aid film, the chromium content in the second layer is 40 atomic% or more, particularly 50 atomic% or more, 100 atomic% or less, especially 99 atomic% or less, especially 90 atomic%. The following is preferable. The oxygen content is 0 atom% or more, preferably 60 atom% or less, and particularly preferably 55 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, and particularly preferably 40 atomic% or less. When the etching rate needs to be adjusted, it is preferably 1 atomic% or more. The carbon content is 0 atom% or more, preferably 20 atom% or less, particularly preferably 10 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably 95 atomic% or more, particularly 99 atomic% or more, and particularly preferably 100 atomic%.

On the other hand, the light-shielding film and the antireflection film of the third layer are materials having etching characteristics different from those of the second layer, for example, a material having resistance to chlorine-based dry etching applied to etching of a material containing chromium. It is preferable to use a silicon-containing material that can be etched with a fluorine-based gas such as SF ₆ or CF ₄ . Specifically, as a material containing silicon, silicon alone, a material containing silicon and one or both of nitrogen and oxygen, a material containing silicon and a transition metal, silicon, one or both of nitrogen and oxygen, transition Examples thereof include silicon compounds such as materials containing metals, and examples of transition metals include molybdenum, tantalum, and zirconium.

  When the third layer is a light shielding film or a combination of a light shielding film and an antireflection film, the light shielding film and the antireflection film are preferably silicon compounds, and the silicon content in the silicon compound is 10 atomic% or more. In particular, it is preferably 30 atomic% or more and less than 100 atomic%, particularly 95 atomic% or less. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, particularly preferably 40 atomic% or less, and particularly preferably 20 atomic% or less. When the etching rate needs to be adjusted, it is 1 atomic% or more. It is preferable. The oxygen content is 0 atom% or more, preferably 60 atom% or less, particularly preferably 30 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. The content of the transition metal is 0 atomic% or more and preferably 35 atomic% or less, particularly preferably 20 atomic% or less. When the transition metal is contained, it is preferably 1 atomic% or more. In this case, the total content of silicon, oxygen, nitrogen and transition metal is preferably 95 atomic% or more, particularly 99 atomic% or more, and particularly preferably 100 atomic%.

  When the second layer is a processing aid film and the third layer is a light shielding film, or a combination of a light shielding film and an antireflection film, the thickness of the second layer is usually 1 to 20 nm, preferably 2 to 10 nm. The film thickness of the third layer is usually 20 to 100 nm, preferably 30 to 70 nm. Further, the total optical density of the halftone phase shift film, the second layer, and the third layer with respect to exposure light having a wavelength of 200 nm or less is 2.0 or more, particularly 2.5 or more, particularly 3.0 or more. It is preferable to make it.

  On the third layer of the halftone phase shift mask blank of the present invention, a fourth layer composed of a single layer or a plurality of layers can be provided. The fourth layer is usually provided adjacent to the third layer. Specific examples of the fourth layer include a processing aid film that functions as a hard mask in pattern formation of the third layer. As the material for the fourth layer, a material containing chromium is suitable.

  A specific example of such a halftone phase shift mask blank is shown in FIG. FIG. 2C is a cross-sectional view showing an example of the halftone phase shift mask blank of the present invention. The halftone phase shift mask blank 100 includes a transparent substrate 10 and a halftone formed on the transparent substrate 10. Formed on the phase shift film 1, the second layer 2 formed on the halftone phase shift film 1, the third layer 3 formed on the second layer 2, and the third layer 3. And a fourth layer 4.

  When the third layer is a light shielding film or a combination of a light shielding film and an antireflection film, a processing auxiliary film (etching mask film) that functions as a hard mask in pattern formation of the third layer is used as the fourth layer. Can be provided. This processing aid film is a material having etching characteristics different from those of the third layer, for example, a material resistant to fluorine-based dry etching applied to etching of a material containing silicon, specifically, a chlorine-based material containing oxygen. A material containing chromium that can be etched with a gas is preferable. Specific examples of the material containing chromium include chromium alone, chromium oxide (CrO), chromium nitride (CrN), chromium carbide (CrC), chromium oxynitride (CrON), chromium oxide carbide (CrOC), and chromium nitride. Examples thereof include chromium compounds such as carbide (CrNC) and chromium oxynitride carbide (CrONC).

  When the fourth layer is a processing aid film, the chromium content in the fourth layer is 40 atomic% or more, particularly 50 atomic% or more, and 100 atomic% or less, particularly 99 atomic% or less, especially 90 atomic%. The following is preferable. The oxygen content is 0 atom% or more, preferably 60 atom% or less, particularly preferably 40 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, and particularly preferably 40 atomic% or less. When the etching rate needs to be adjusted, it is preferably 1 atomic% or more. The carbon content is 0 atom% or more, preferably 20 atom% or less, particularly preferably 10 atom% or less. When the etching rate needs to be adjusted, it is preferably 1 atom% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably 95 atomic% or more, particularly 99 atomic% or more, and particularly preferably 100 atomic%.

  When the second layer is a processing auxiliary film, the third layer is a light shielding film, or a combination of a light shielding film and an antireflection film, and the fourth layer is a processing auxiliary film, the thickness of the second layer is usually 1 to 20 nm, preferably 2 to 10 nm, the thickness of the third layer is usually 20 to 100 nm, preferably 30 to 70 nm, and the thickness of the fourth layer is usually 1 to 30 nm, preferably 2-20 nm. Further, the total optical density of the halftone phase shift film, the second layer, and the third layer with respect to exposure light having a wavelength of 200 nm or less is 2.0 or more, particularly 2.5 or more, particularly 3.0 or more. It is preferable to make it.

  The film made of the material containing chromium of the second layer and the fourth layer uses a chromium target, a target obtained by adding one or more selected from oxygen, nitrogen, and carbon to chromium, and the like. Reactivity using a sputtering gas in which a reactive gas selected from an oxygen-containing gas, a nitrogen-containing gas, a carbon-containing gas, or the like is appropriately added to a rare gas such as Ar, He, or Ne according to the composition of a film to be formed. A film can be formed by sputtering.

  On the other hand, the film made of the silicon-containing material of the third layer uses a silicon target, a silicon nitride target, a target containing both silicon and silicon nitride, a transition metal target, a composite target of silicon and transition metal, and the like. Reaction using a sputtering gas in which a reactive gas selected from an oxygen-containing gas, a nitrogen-containing gas, a carbon-containing gas, or the like is appropriately added to a rare gas such as Ar, He, or Ne according to the composition of a film to be formed The film can be formed by reactive sputtering.

  The halftone phase shift mask of the present invention can be manufactured from a halftone phase shift mask blank by a conventional method. For example, in a halftone phase shift mask blank in which a film of a material containing chromium is formed as the second layer on the halftone phase shift film, for example, a halftone phase shift mask is manufactured by the following process. be able to.

  First, an electron beam resist film is formed on the second layer of the halftone phase shift mask blank, a pattern is drawn with an electron beam, and then a resist pattern is obtained by a predetermined development operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the second layer by chlorine-based dry etching containing oxygen to obtain a pattern of the second layer. Next, by using the obtained second layer pattern as an etching mask, the second layer pattern is transferred to the halftone phase shift film by fluorine-based dry etching to obtain a halftone phase shift film pattern. Here, when it is necessary to leave a part of the second layer, a resist pattern for protecting the part is formed on the second layer, and then the resist pattern is formed by chlorine-based dry etching containing oxygen. The portion of the second layer not protected by is removed. Then, the halftone phase shift mask can be obtained by removing the resist pattern by a conventional method.

  Further, on the halftone phase shift film, a light shielding film of a material containing chromium or a combination of a light shielding film and an antireflection film is formed as a second layer, and a third layer is formed on the second layer. In a halftone phase shift mask blank in which a processing auxiliary film of a material containing silicon is formed as a layer, for example, a halftone phase shift mask can be manufactured by the following steps.

  First, an electron beam resist film is formed on the third layer of the halftone phase shift mask blank, a pattern is drawn with an electron beam, and then a resist pattern is obtained by a predetermined development operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the third layer by fluorine-based dry etching to obtain a pattern of the third layer. Next, using the pattern of the obtained third layer as an etching mask, the pattern of the third layer is transferred to the second layer by chlorine-based dry etching containing oxygen, and the pattern of the second layer is formed. obtain. Next, after removing the resist pattern, the pattern of the second layer is transferred to the halftone phase shift film by fluorine-based dry etching using the pattern of the obtained second layer as an etching mask. At the same time as obtaining the shift film pattern, the pattern of the third layer is removed. Next, after forming a resist pattern for protecting the portion where the second layer remains on the second layer, the second portion of the portion not protected by the resist pattern is subjected to chlorine-based dry etching containing oxygen. Remove the layer. Then, the halftone phase shift mask can be obtained by removing the resist pattern by a conventional method.

  On the other hand, a processing auxiliary film made of a material containing chromium is formed as a second layer on the halftone phase shift film, and a light shielding film made of a material containing silicon is used as the third layer on the second layer. In a halftone phase shift mask blank in which a combination of a light shielding film and an antireflection film is formed, for example, a halftone phase shift mask can be manufactured by the following process.

  First, an electron beam resist film is formed on the third layer of the halftone phase shift mask blank, a pattern is drawn with an electron beam, and then a resist pattern is obtained by a predetermined development operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the third layer by fluorine-based dry etching to obtain a pattern of the third layer. Next, using the obtained pattern of the third layer as an etching mask, the pattern of the third layer is transferred to the second layer by chlorine-based dry etching containing oxygen, and the halftone phase shift film is removed. A pattern of the second layer from which the second layer of the portion to be removed is removed is obtained. Next, after removing the resist pattern and forming a resist pattern on the third layer to protect the portion where the third layer remains, the obtained second layer pattern is used as an etching mask to form a fluorine-based material. The pattern of the second layer is transferred to the halftone phase shift film by dry etching to obtain a halftone phase shift film pattern, and at the same time, the portion of the third layer not protected by the resist pattern is removed. Next, the resist pattern is removed by a conventional method. Then, the second layer where the third layer has been removed is removed by chlorine-based dry etching containing oxygen, whereby a halftone phase shift mask can be obtained.

  Further, a processing aid film made of a material containing chromium is formed as a second layer on the halftone phase shift film, and a light shielding film made of a material containing silicon is used as the third layer on the second layer. Or a halftone phase shift mask blank in which a combination of a light shielding film and an antireflection film is formed, and a processing auxiliary film of a material containing chromium is formed as a fourth layer on the third layer. Then, for example, a halftone phase shift mask can be manufactured by the following steps.

  First, an electron beam resist film is formed on the fourth layer of the halftone phase shift mask blank, a pattern is drawn with an electron beam, and then a resist pattern is obtained by a predetermined development operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the fourth layer by chlorine-based dry etching containing oxygen to obtain a pattern of the fourth layer. Next, using the pattern of the obtained fourth layer as an etching mask, the pattern of the fourth layer is transferred to the third layer by fluorine-based dry etching to obtain the pattern of the third layer. Next, after removing the resist pattern and forming a resist pattern on the fourth layer to protect the portion where the third layer is to be left, oxygen is applied using the obtained third layer pattern as an etching mask. The chlorine layer dry etching contained therein transfers the pattern of the third layer to the second layer to obtain the pattern of the second layer, and at the same time, the portion of the fourth layer not protected by the resist pattern is removed. . Next, using the second layer pattern as an etching mask, the second layer pattern is transferred to the halftone phase shift film by fluorine-based dry etching to obtain a halftone phase shift film pattern. The third layer that is not protected by is removed. Next, the resist pattern is removed by a conventional method. Then, the second layer from which the third layer has been removed and the fourth layer from which the resist pattern has been removed are removed by chlorine-based dry etching containing oxygen, and a halftone phase shift mask. Can be obtained.

The halftone phase mask of the present invention is an ArF excimer formed on a photoresist film formed on a substrate to be processed in photolithography for forming a pattern having 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 exposure in which a pattern is transferred with exposure light having a wavelength of 200 nm or less, such as laser light (wavelength 193 nm) and F ₂ laser light (wavelength 157 nm).

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

[Example 1]
A SiN halftone phase shift film was formed on a 152 mm square and 6.35 mm thick quartz substrate using a silicon target as a sputtering target and nitrogen gas and argon gas as sputtering gases. When the film was formed by adjusting the film formation time so that the phase difference of light with a wavelength of 193 nm (ArF excimer laser, the same applies hereinafter) was 178 °, the transmittance with light with a wavelength of 193 nm was 6%. The film thickness was 61 nm. Further, when the composition of this film was measured by XPS (X-ray photoelectron spectroscopy, hereinafter the same), the atomic ratio was Si: N = 48: 52, and the transition metal was 0.1 atomic% or less.

  Next, a CrON light-shielding film having a film thickness of 45 nm is formed on the halftone phase shift film using a chromium target as a sputtering target and nitrogen gas, oxygen gas, and argon gas as sputtering gases. A halftone phase shift mask blank was obtained. Next, an electron beam resist film was formed on the light shielding film by a conventional method, and the resist film was patterned to form a resist pattern. Next, using the resist pattern as an etching mask, the light shielding film was patterned by chlorine-based dry etching to form a light shielding film pattern. Next, using the light shielding film pattern as an etching mask, the halftone phase shift film is etched by fluorine-based dry etching to form a halftone phase shift film pattern having a line width of 200 nm, and the resist film pattern is removed. A halftone phase shift mask was obtained.

Next, with respect to the obtained halftone phase shift mask, in a clean air atmosphere at a temperature of 25 ° C. and a humidity of 45%, an exposure apparatus (ArFES-3500PM (manufactured by RISOTEC Japan)) and an ArF excimer laser light source (IndyStar ( COHERENT, Inc.) was used, and pulsed irradiation was performed with light having a pulse frequency of 1.6 kHz and an energy per pulse of 2.5 to 4.0 mJ / cm ^{2 and} a wavelength of 193 nm until the cumulative amount reached 40 kJ / cm ² . The line width of the halftone phase shift film pattern before and after irradiation with light with a wavelength of 193 nm was observed with a scanning electron microscope (LWM9045 (manufactured by Vistec)) and measured, and the pattern before and after irradiation with light with a wavelength of 193 nm was measured. The dimensional variation was as good as 0.7 nm.

[Example 2]
A SiN halftone phase shift film was formed on a 152 mm square and 6.35 mm thick quartz substrate using a silicon target as a sputtering target and nitrogen gas and argon gas as sputtering gases. When this film was formed by adjusting the film formation time so that the phase difference with light with a wavelength of 193 nm was 180 °, the transmittance with light with a wavelength of 193 nm was 12% and the film thickness was 60 nm. . Moreover, when the composition of this film was measured by XPS, the atomic ratio was Si: N = 47: 53, and the transition metal content was 0.1 atomic% or less.

  Next, a light-shielding film is formed by the same method as in Example 1 to obtain a halftone phase shift mask blank. Further, an electron beam resist film is formed, and a halftone phase is formed by the same method as in Example 1. A shift mask was obtained. Next, the obtained halftone phase shift mask was irradiated with light having a wavelength of 193 nm in the same manner as in Example 1, and the line width before and after the irradiation of light having a wavelength of 193 nm of the halftone phase shift film pattern was measured. However, the pattern dimension variation before and after irradiation with light having a wavelength of 193 nm was as good as 0.6 nm.

[Example 3]
A SiON halftone phase shift film was formed on a 152 mm square and 6.35 mm thick quartz substrate using a silicon target as a sputtering target and oxygen gas, nitrogen gas and argon gas as sputtering gases. . When this film was formed by adjusting the film formation time so that the phase difference with light with a wavelength of 193 nm was 177 °, the transmittance with light with a wavelength of 193 nm was 19% and the film thickness was 60 nm. . Moreover, when the composition of this film was measured by XPS, the atomic ratio was Si: N: O = 45: 53: 2, and the transition metal content was 0.1 atomic% or less.

  Next, a light-shielding film is formed by the same method as in Example 1 to obtain a halftone phase shift mask blank. Further, an electron beam resist film is formed, and a halftone phase is formed by the same method as in Example 1. A shift mask was obtained. Next, the obtained halftone phase shift mask was irradiated with light having a wavelength of 193 nm in the same manner as in Example 1, and the line width before and after the irradiation of light having a wavelength of 193 nm of the halftone phase shift film pattern was measured. However, the pattern dimension variation before and after irradiation with light having a wavelength of 193 nm was as good as 0.7 nm.

[Example 4]
A MoSiN halftone phase shift film is formed on a 152 mm square and 6.35 mm thick quartz substrate using a silicon target and a molybdenum silicon target as sputtering targets and nitrogen gas and argon gas as sputtering gases. Filmed. When the film was formed by adjusting the film formation time so that the phase difference with light with a wavelength of 193 nm was 176 °, the transmittance with light with a wavelength of 193 nm was 4% and the film thickness was 60 nm. . Moreover, when the composition of this film was measured by XPS, the atomic ratio was Si: N = 47: 52, and the transition metal content was 0.9 atomic%.

  Next, a light-shielding film is formed by the same method as in Example 1 to obtain a halftone phase shift mask blank. Further, an electron beam resist film is formed, and a halftone phase is formed by the same method as in Example 1. A shift mask was obtained. Next, the obtained halftone phase shift mask was irradiated with light having a wavelength of 193 nm in the same manner as in Example 1, and the line width before and after the irradiation of light having a wavelength of 193 nm of the halftone phase shift film pattern was measured. However, the pattern dimension variation before and after irradiation with light having a wavelength of 193 nm was as good as 0.5 nm.

[Comparative Example 1]
On a quartz substrate having a size of 152 mm square and a thickness of 6.35 mm, as a sputtering target, a target containing molybdenum and silicon in a molar ratio of molybdenum: silicon = 1: 2 and a silicon target, and as a sputtering gas, A MoSiON halftone phase shift film was formed using oxygen gas, nitrogen gas, and argon gas. When the film was formed by adjusting the film formation time so that the phase difference with light with a wavelength of 193 nm was 177 °, the transmittance with light with a wavelength of 193 nm was 6% and the film thickness was 75 nm. . Moreover, when the composition of this film was measured by XPS, the atomic ratio was Si: N: O = 36: 45: 10, and Mo was 9 atomic%.

  Next, a light-shielding film is formed by the same method as in Example 1 to obtain a halftone phase shift mask blank. Further, an electron beam resist film is formed, and a halftone phase is formed by the same method as in Example 1. A shift mask was obtained. Next, the obtained halftone phase shift mask was irradiated with light having a wavelength of 193 nm in the same manner as in Example 1, and the line width before and after the irradiation of light having a wavelength of 193 nm of the halftone phase shift film pattern was measured. However, the pattern dimension fluctuation before and after irradiation with light having a wavelength of 193 nm was a large change amount of 26.7 nm.

[Comparative Example 2]
On a quartz substrate having a size of 152 mm square and a thickness of 6.35 mm, as a sputtering target, a target containing molybdenum and silicon in a molar ratio of molybdenum: silicon = 1: 2 and a silicon target, and as a sputtering gas, A MoSiON halftone phase shift film was formed using oxygen gas, nitrogen gas, and argon gas. When the film was formed by adjusting the film formation time so that the phase difference with light with a wavelength of 193 nm was 177 °, the transmittance with light with a wavelength of 193 nm was 6% and the film thickness was 72 nm. . Moreover, when the composition of this film was measured by XPS, the atomic ratio was Si: N: O = 36: 42: 14, and Mo was 9 atomic%.

  Next, a light-shielding film is formed by the same method as in Example 1 to obtain a halftone phase shift mask blank. Further, an electron beam resist film is formed, and a halftone phase is formed by the same method as in Example 1. A shift mask was obtained. Next, the obtained halftone phase shift mask was irradiated with light having a wavelength of 193 nm in the same manner as in Example 1, and the line width before and after the irradiation of light having a wavelength of 193 nm of the halftone phase shift film pattern was measured. However, the pattern dimension fluctuation before and after irradiation with light having a wavelength of 193 nm was a large change amount of 20.6 nm.

As described above, in the halftone phase shift film pattern in which the transition metal content is 1 atomic% or less, pattern dimension variation deterioration before and after irradiation with a cumulative 40 kJ / cm ² of light having a wavelength of 193 nm is extremely small, 1 nm or less. It can be seen that a halftone phase shift mask having such a halftone phase shift film pattern has a long lifetime. As described above, according to the present invention, a film having a film thickness of 70 nm or less, which is advantageous in the processing of a photomask pattern, with a necessary retardation and transmittance, and a pattern for irradiation with light having a wavelength of 193 nm. It can be seen that a halftone phase shift mask blank and a halftone phase shift mask provided with a halftone phase shift film with small dimensional variation deterioration can be provided.

DESCRIPTION OF SYMBOLS 1 Halftone phase shift film | membrane 2 2nd layer 3 3rd layer 4 4th layer 10 Transparent substrate 11 Halftone phase shift film pattern 100 Halftone phase shift mask blank 101 Halftone phase shift mask

Claims (10)

A halftone having a halftone phase shift film composed of a single layer or a plurality of layers on a transparent substrate and having a wavelength of 200 nm or less, a phase shift amount of 150 to 200 °, and a transmittance of 3% to less than 20%. A phase shift mask blank,
Each of the single layer or the plurality of layers constituting the halftone phase shift film may contain silicon and nitrogen as essential components and oxygen as an optional component, and the halftone phase shift When the film is composed of a single layer, the whole is composed of a plurality of layers. When the film is composed of a plurality of layers, 60% or more of the film thickness is 90% by atom or more of the total content of silicon, nitrogen and oxygen. Is 44 to 70 atomic percent, the total content of nitrogen and oxygen is 30 to 60 atomic percent, the oxygen content is 30 atomic percent or less, and the transition metal content is 1 atomic percent or less. Consists of silicon-based material,
A halftone phase shift mask blank, wherein the film thickness of the halftone phase shift film is 70 nm or less.   2. The halftone phase shift mask according to claim 1, wherein the silicon-based material is composed of a silicon-based material that does not contain oxygen and has a total content of silicon and nitrogen of 95 atomic% or more. blank.   The halftone phase shift mask blank according to claim 1 or 2, further comprising a second layer composed of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film. .   The second layer is a processing auxiliary film functioning as a hard mask in forming a light shielding film, a combination of a light shielding film and an antireflection film, or patterning of the halftone phase shift film. Halftone phase shift mask blank.   4. The halftone phase shift mask blank according to claim 3, further comprising a third layer composed of a single layer or a plurality of layers made of a material containing silicon on the second layer.   The second layer is a light shielding film, or a combination of a light shielding film and an antireflection film, and the third layer is a processing auxiliary film that functions as a hard mask in pattern formation of the second layer. The halftone phase shift mask blank according to claim 5.   The second layer is a processing auxiliary film that functions as a hard mask in the pattern formation of the halftone phase shift film and also functions as an etching stopper in the pattern formation of the third layer. 6. The halftone phase shift mask blank according to claim 5, wherein the halftone phase shift mask blank is a light shielding film or a combination of a light shielding film and an antireflection film.   6. The halftone phase shift mask blank according to claim 5, further comprising a fourth layer composed of a single layer or a plurality of layers made of a material containing chromium on the third layer.   The second layer is a processing auxiliary film that functions as a hard mask in the pattern formation of the halftone phase shift film and also functions as an etching stopper in the pattern formation of the third layer. The light-shielding film, or a combination of a light-shielding film and an antireflection film, wherein the fourth layer is a processing auxiliary film that functions as a hard mask in pattern formation of the third layer. 8. A halftone phase shift mask blank according to 8.   The halftone phase shift mask formed using the halftone phase shift mask blank of any one of Claims 1 thru | or 9.

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