JP6477159B2 - Halftone phase shift mask blank and method of manufacturing halftone phase shift mask blank - Google Patents

Description

The present invention relates to a method for producing a halftone phase shift mask blank scan及 beauty halftone phase shift mask blanks used for manufacturing a semiconductor integrated circuit.

  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) Literature 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.

  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 50% humidity) where 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

  Also, when using a halftone phase shift mask blank in the halftone phase shift mask manufacturing process, if foreign matter is present on the halftone phase shift mask blank, the foreign matter may cause pattern defects. In order to remove, the halftone phase shift mask blanks are cleaned many times during the halftone phase shift mask manufacturing process. Furthermore, when the halftone phase shift mask is used in the photolithography process, even if there is no pattern defect in the manufactured halftone phase shift mask itself, foreign matters adhere to the halftone phase shift mask during the photolithography process. Since a pattern transfer defect occurs in the semiconductor substrate patterned using this, the halftone phase shift mask is also repeatedly cleaned.

  In order to remove foreign matter from the halftone phase shift mask blank or the halftone phase shift mask, in most cases, chemical cleaning with sulfuric acid / hydrogen peroxide, ozone water, ammonia water, or the like is performed. Here, sulfuric acid / hydrogen peroxide is a cleaning agent having a strong oxidizing action obtained by mixing sulfuric acid and hydrogen peroxide water, and ozone water is a solution in which ozone is dissolved in water. Used as an alternative. In particular, ammonia perwater is a cleaning agent obtained by mixing ammonia water and hydrogen peroxide water. When organic foreign matter adhering to the surface is immersed in ammonia perwater, the ammonia dissolving action and the hydrogen peroxide Cleaning is performed by separating and separating organic foreign matters from the surface by the oxidative action.

  Such chemical cleaning with a chemical solution is necessary to remove foreign substances such as particles and contaminants attached to the halftone phase shift mask blanks and halftone phase shift masks, while halftone phase shift mask blanks and halftones are removed. There is a possibility of damaging the halftone phase shift film provided in the tone phase shift mask. For example, the surface of the halftone phase shift film may be altered by the chemical cleaning as described above, and the optical characteristics that should be originally provided may change, and halftone phase shift mask blanks and halftones may be changed. Since chemical cleaning of the phase shift mask is performed repeatedly, it is necessary to suppress the characteristic change (for example, phase difference change) of the halftone phase shift film generated in each cleaning process as low as possible. is there.

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 halftone 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.

  As described above, as a halftone phase shift film, a film containing molybdenum and silicon was mainly used (Japanese Patent Laid-Open No. 7-140635 (Patent Document 1)), but a molybdenum silicon-based film having a transmittance of 6%. In order to obtain a phase difference of, for example, 177 ° with a light having a wavelength of 193 nm, generally, a halftone phase shift film of about 75 nm or 68 nm is used. Even if it is going to make a shift film thin, it is difficult to make it a film thickness of 62 nm or less. Further, in the halftone phase shift film having a high transmittance, oxygen must be contained. In order to obtain the same phase difference of 177 ° by reducing the refractive index due to the inclusion of oxygen, the film thickness is further increased. Must.

  In recent years, the minimum line width on a photomask used in the manufacture of LSI has been reduced to 50 nm or less, and the pattern width corresponding to the line width of the halftone phase shift film pattern and the thickness of the halftone phase shift film has been increased. The ratio (aspect ratio) is high. In such a photomask pattern having a high aspect ratio, there is a problem that when the pattern is subjected to a force in a process such as manufacturing a photomask or cleaning when using the photomask, the pattern itself is easily lost.

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 This is a half-tone phase shift film with a thin film thickness, which is advantageous in reducing the effect, etc., and has a low risk of loss of micropatterns when a half-tone phase shift film is formed to form a half-tone phase shift mask. and to provide a method of manufacturing a halftone phase shift mask blank scan及 beauty halftone phase shift mask blank having a halftone phase shift film which gives a tone phase shift mask blanks.

  In order to solve the above problems, the present inventors have secured the necessary phase difference and transmittance as a halftone phase shift film, and have a thin film thickness and a low risk of micropattern loss. As a result of intensive studies on a halftone phase shift film not containing a transition metal with the aim of developing a film, silicon and nitrogen are used as a halftone phase shift film having a phase difference of 150 to 200 ° with respect to light having a wavelength of 200 nm or less. A halftone phase shift film comprising at least one layer of silicon-based material or silicon-based material composed of silicon, nitrogen and oxygen, and having a low transmittance of 3% to 20% and a film thickness of 62 nm or less And a halftone phase shift film having a film thickness of 70 nm or less even with a high transmittance of 20% to 30%. It has been found that can be formed.

  By configuring the halftone phase shift film in this way, exposure light having a wavelength of 200 nm or less is formed on a substrate to be processed such as a silicon wafer using a halftone phase shift mask having a pattern of the halftone phase shift film. A halftone phase shift mask that can advantageously process a halftone phase shift film pattern having a main photomask pattern with a width of about 100 to 200 nm, which is necessary in photolithography for forming a transferred pattern with a half pitch of 50 nm or less. The inventors have found that blanks can be obtained, and have made the present invention.

Accordingly, the present invention provides a method for producing the following halftone phase shift mask blank scan及 beauty halftone phase shift mask blanks.
Claim 1:
A halftone phase shift mask blank having a halftone phase shift film having a phase shift amount of 150 to 200 ° with light having a wavelength of 200 nm or less on a transparent substrate,
The halftone phase shift film includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen, and has a transmittance of 3% to 20% with light having a wavelength of 200 nm or less. And having a second layer consisting of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film, and having a film thickness of 62 nm or less. And a third layer composed of a single layer or a plurality of layers made of a material containing silicon, and the second layer functions as a hard mask in patterning the halftone phase shift film, and A processing auxiliary film that functions as an etching stopper in pattern formation of the third layer, wherein the third layer is a light shielding film or a combination of a light shielding film and an antireflection film. Half-tone phase shift mask blanks that.
Claim 2:
A halftone phase shift mask blank having a halftone phase shift film having a phase shift amount of 150 to 200 ° with light having a wavelength of 200 nm or less on a transparent substrate,
The halftone phase shift film includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen, and has a transmittance of 20% to 30% with light having a wavelength of 200 nm or less. And having a second layer consisting of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film, and having a film thickness of 70 nm or less. And a third layer composed of a single layer or a plurality of layers made of a material containing silicon, and the second layer functions as a hard mask in patterning the halftone phase shift film, and A processing auxiliary film that functions as an etching stopper in pattern formation of the third layer, wherein the third layer is a light shielding film or a combination of a light shielding film and an antireflection film. Half-tone phase shift mask blanks to be.
Claim 3:
3. The halftone phase shift mask blank according to claim 1, 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 4:
4. The halftone phase shift mask blank according to claim 3, wherein the fourth layer is a processing auxiliary film that functions as a hard mask in pattern formation of the third layer.
Claim 5 :
A method for producing a halftone phase shift mask blank according to any one of claims 1 to 4 , comprising a step of forming a halftone phase shift film on a transparent substrate by sputtering.
The step of forming the halftone phase shift film comprises:
(A) On a transparent substrate, using a sputtering apparatus, using at least one silicon target, introducing argon gas and nitrogen gas into the sputtering chamber, and forming a layer composed of a silicon-based material composed of silicon and nitrogen (B) Sputtering argon gas and at least one gas selected from nitrogen gas, oxygen gas, and nitrogen oxide gas on a transparent substrate using a sputtering apparatus and using at least one silicon target. One or both of the steps of introducing into the chamber and forming a layer composed of a silicon-based material consisting of silicon, nitrogen and oxygen,
The method for manufacturing a halftone phase shift mask blank, further comprising a step of heat-treating the halftone phase shift film formed on the transparent substrate at 400 ° C. or more for 5 minutes or more.

  According to the present invention, it is a thinner halftone phase shift film, which is advantageous in the processing of a photomask pattern, and a micropattern when forming a halftone phase shift mask by patterning the halftone phase shift film. A halftone phase shift film which provides a halftone phase shift mask blank with a low risk of loss, and 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. A halftone phase shift mask blank and a halftone phase shift mask can be provided. According to the halftone phase shift mask of the present invention, it is possible to perform exposure that meets the requirements for further pattern miniaturization and higher precision in photolithography.

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

Hereinafter, the present invention will be described in more detail.
The halftone phase shift mask blank of the present invention (halftone phase shift photomask blank) is a halftone phase shift composed of a single layer or multiple layers (that is, two or more layers) formed on a transparent substrate such as a quartz substrate. Has a membrane. 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 blanks of the present invention. This halftone phase shift mask blanks 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 layer having an antireflection function and to have a multilayer structure so as to satisfy the phase difference and transmittance required as a halftone phase shift film as a whole.

  In either case of a single layer or a multilayer, 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 multiple 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. When the multilayer is composed of three or more layers If they are not adjacent layers, the same layers can be combined.

  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 of the halftone phase shift film of the present invention with respect to the exposure light passes through the boundary portion between the portion where the halftone phase shift film exists (phase shift portion) and the portion where the halftone phase shift film does not exist. As long as the phase difference of the exposure light to be interfered with the exposure light can increase the contrast, 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.

  When the halftone phase shift film is composed of a silicon-based material composed of silicon and nitrogen, the amount of silicon and nitrogen in the halftone phase shift film is adjusted, and the halftone phase shift film is In the case where it is composed of a silicon-based material composed of silicon, nitrogen, and oxygen, the transmittance is 3 with light having a wavelength of 200 nm or less by adjusting the amounts of silicon, nitrogen, and oxygen in the halftone phase shift film. % To 20% or less halftone phase shift film can be formed with a film thickness of 62 nm or less, and halftone phase shift film having a transmittance of 20% to 30% with light having a wavelength of 200 nm or less. , And a film thickness of 70 nm or less.

  In the halftone phase shift film of the present invention, when it is composed of a single layer, it is the whole of the single layer, and when it is composed of multiple layers, one or more of the layers constituting the multilayer, in particular, the surface oxide layer described later In the case where the surface oxide layer is provided, the refractive index n with respect to the exposure light is preferably 2.4 or more, particularly 2.5 or more, particularly 2.6 or more in the entire multilayer except for the surface oxide layer. By reducing the oxygen content of the halftone phase shift film, preferably by not containing oxygen or by not containing a transition metal, the refractive index n of the film can be increased at a predetermined transmittance, and In addition, the film thickness can be further reduced while ensuring the phase difference required for the halftone phase shift film. The refractive index n becomes higher as the oxygen content is lower, and the higher the refractive index n, the more necessary retardation can be obtained with a thinner film.

  In the halftone phase shift film of the present invention, when it is composed of a single layer, it is the whole of the single layer, and when it is composed of multiple layers, one or more of the layers constituting the multilayer, in particular, the surface oxide layer described later Except for this surface oxide layer, the extinction coefficient k with respect to the exposure light is preferably 0.1 or more, particularly 0.2 or more, 0.7 or less, particularly 0.65 or less in the entire multilayer. .

  The halftone phase shift film of the present invention includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen. The silicon-based material contains silicon and nitrogen, and may contain oxygen. Inclusion of elements other than these is acceptable as long as the amount of impurities is present, but it is particularly preferable that no transition metal (eg, molybdenum, zirconium, tungsten, titanium, hafnium, chromium, tantalum, etc.) is contained. The problem of pattern dimension fluctuation deterioration in silicon-based materials containing transition metals can be improved by using such silicon-based materials, and resistance to chemical cleaning can be improved by using such silicon-based materials. Chemical properties are improved.

  When the halftone phase shift film is composed of multiple layers, the thickness of the silicon-based material composed of silicon and nitrogen or the layer composed of the silicon-based material composed of silicon, nitrogen and oxygen (if the layer is two or more layers, The total thickness of the halftone phase shift film is preferably 60% or more, particularly preferably 80% or more. Particularly, when a surface oxide layer described later is provided, this surface oxide layer is excluded, The entire multilayer is preferably a layer composed of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen. Further, when the halftone phase shift film is composed of multiple layers, the silicon material made of silicon and nitrogen or the layer made of silicon material made of silicon, nitrogen and oxygen is separated from the transparent substrate side and the transparent substrate side. It may be provided on either the side or the central portion in the thickness direction.

  When the halftone phase shift film of the present invention is composed of a single layer, in the silicon-based material of the entire single layer, and when composed of multiple layers, the silicon-based material of one or more layers constituting the multilayer, In particular, when a surface oxide layer to be described later is provided, the silicon content in the silicon-based material is 30 atomic% or more, particularly 40 atomic% or more, especially 44, except for the surface oxide layer. It is preferable that it is not less than 55% by atom and more preferably not more than 50% by atom. In particular, when the halftone phase shift film has a low transmittance (for example, 3% or more and 20% or less, particularly 3% or more and 12% or less, especially 3% or more and less than 10%), silicon contained in the silicon-based material The rate is 40 atomic% or more, particularly 44 atomic% or more, preferably 55 atomic% or less, particularly 50 atomic% or less, and the halftone phase shift film has a high transmittance (for example, 20% or more and 30% or less ), The content of silicon contained 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, in the silicon-based material of the entire single layer, and when composed of multiple layers, the silicon-based material of one or more layers constituting the multilayer, In particular, when a surface oxide layer to be described later is provided, except for the surface oxide layer, in the silicon-based material of the entire multilayer, the content of nitrogen contained in the silicon-based material is 10 atomic% or more, particularly 40 atomic% or more. It is preferably at most atomic%, particularly at most 55 atomic%. In particular, when the halftone phase shift film has a low transmittance (for example, 3% or more and 20% or less, particularly 3% or more and 12% or less, especially 3% or more and less than 10%), the content 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 silicon-based material of the entire single layer is formed. In the case where a surface oxide layer described later is provided, the oxygen content in the silicon-based material is 50 atom% or less, particularly 20 atom% or less, especially 6 atoms in the silicon-based material of the entire multilayer except for the surface oxide layer. % Or less is preferable. In particular, when the halftone phase shift film has a low transmittance (eg, 3% or more and 20% or less, particularly 3% or more and 12% or less, particularly 3% or more and less than 10%), the oxygen content contained in the silicon-based material is included. The rate is 0 atomic% or more and 6 atomic% or less, particularly 3.5% or less, particularly 1% or less, and the halftone phase shift film has a high transmittance (for example, 20% or more and 30% or less). ), The content of oxygen contained in the silicon-based material is preferably 50 atomic percent or less, particularly preferably 20 atomic percent or less. In particular, the content of oxygen contained in the silicon-based material is 0 atomic percent or more. In particular, it is preferable that one or more layers of 1 atomic% or more are included.

  Specific examples of silicon-based materials include silicon-based materials consisting only of silicon and nitrogen (ie, silicon nitride (SiN)), and silicon-based materials consisting only of silicon, nitrogen and oxygen (ie, silicon oxynitride (SiON)). ).

  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 viewpoint, it is preferable that the halftone phase shift film includes a layer composed of a silicon-based material composed of silicon and nitrogen. For this purpose, it is effective to form the halftone phase shift film as a single layer composed of a silicon-based material composed of silicon and nitrogen, and to form a layer composed of a silicon-based material composed of silicon and nitrogen. It is also effective to form a multi-layer including one or more layers, in particular, a multi-layer including one or more layers composed of a silicon-based material composed of silicon and nitrogen and one or more layers composed of silicon, nitrogen and oxygen. is there.

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.

  The halftone phase shift mask blank of the present invention includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen on a transparent substrate. The halftone phase shift film formed by sputtering is preferably formed by heat treatment at 400 ° C. or higher for 5 minutes or longer.

  The step of forming a halftone phase shift film on a transparent substrate by sputtering includes: (A) Using a sputtering apparatus on the transparent substrate, using at least one silicon target, and supplying argon gas and nitrogen gas into the sputtering chamber. Introducing and forming a layer composed of a silicon-based material composed of silicon and nitrogen, and (B) using a sputtering apparatus on a transparent substrate, using at least one silicon target, argon gas, nitrogen One or both of the steps of introducing a gas, oxygen gas and at least one gas selected from nitrogen oxide gas into the sputtering chamber to form a layer composed of a silicon-based material comprising silicon, nitrogen and oxygen It is preferable to contain. In sputtering, the halftone phase shift film obtained is introduced with a sputtering gas during the formation of the halftone phase shift film so that the amount of change in warpage (ΔTIR) is reduced in the halftone phase shift mask blank. It is preferred to adjust the amount.

  The heat treatment after the formation of the halftone phase shift film is performed at 400 ° C. or higher, particularly 450 ° C. or higher, for 5 minutes or longer, particularly 30 minutes or longer, with the halftone phase shift film formed on the transparent substrate. Is preferred. Conventionally, a film containing a transition metal used as a halftone phase shift film is subjected to heat treatment at such a high temperature, and precipitates are formed on the surface, resulting in defects. However, the halftone phase shift film including at least one silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen, and oxygen according to the present invention does not change even when such a high temperature is applied. There is no problem like a film containing a metal. The heat treatment temperature is preferably 900 ° C. or less, particularly preferably 700 ° C. or less, and the heat treatment time is preferably 24 hours or less, particularly preferably 12 hours or less. The heat treatment may be performed in the sputtering chamber, or may be performed by moving to a heat treatment furnace different from the sputtering chamber. Even if the atmosphere of the heat treatment is an inert gas atmosphere such as helium gas or argon gas, or under vacuum, a surface oxide layer to be described later is formed on the outermost surface. Good.

  When the halftone phase shift film is a multilayer, a surface oxide layer may be 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. it can. 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.

  On the halftone phase shift film of the halftone phase shift mask blank of the present invention, a second layer consisting of a single layer or multiple layers can be provided. 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 halftone phase shift mask blanks 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 a 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 multiple 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 consisting of a single layer or multiple 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 halftone phase shift mask blanks 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 multilayer. 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 consisting of a single layer or multiple 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.

  Specific examples of such halftone phase shift mask blanks include those 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 halftone phase shift mask blanks by a conventional method. For example, in the 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, the 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 blanks, 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 the 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 blanks, 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. Alternatively, 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 blanks, 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 combination of a light-shielding film and an anti-reflection film, and a halftone phase shift mask blank in which 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 blanks, and after pattern drawing with an electron beam, 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).

  In the pattern exposure method of the present invention, a halftone phase shift mask manufactured from a halftone phase shift mask blank is used, and a photomask pattern including a halftone phase shift film pattern is irradiated with exposure light to process a substrate. The photomask pattern is transferred to the photoresist film that is the exposure target of the photomask pattern formed above. Irradiation of exposure light may be exposure under dry conditions or immersion exposure, but the pattern exposure method of the present invention is particularly effective due to immersion exposure in which the cumulative irradiation energy amount increases in a relatively short time in actual production. This is particularly effective when a photomask pattern is exposed by immersion exposure using a wafer of 300 mm or more as a substrate to be processed.

  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 152 mm square, 6.35 mm thick 6025 quartz substrate was installed in the chamber of the sputtering apparatus, a silicon target was used as the sputtering target, argon gas and nitrogen gas were used as the sputtering gas, and the power applied to the target was 1,900 W, A halftone phase shift film made of SiN was formed with an argon gas flow rate of 17 sccm and a nitrogen gas flow rate of 40 sccm. Thereafter, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after this heat treatment had a phase difference of 177 °, a transmittance of 19%, and a film thickness of 60 nm. Further, when the composition of this film was measured by XPS (X-ray photoelectron spectroscopy, the same applies hereinafter), the atomic ratio was Si: N = 46: 53.

  Next, a resist film is formed on the second layer of the halftone phase shift mask blank in which the second layer containing Cr is formed on the obtained halftone phase shift film, and the resist film is patterned, Using the obtained resist pattern as an etching mask, the second layer is etched by chlorine-based dry etching containing oxygen, and further, the halftone phase shift film is etched by fluorine-based dry etching, and the resist film and the second layer are etched. Was peeled to form a plurality of patterns of 40 nm × 160 nm to obtain a halftone phase shift mask. Next, to the obtained halftone phase shift mask, as a cleaning megasonic resistance test, ammonia-added hydrogen water (ammonia concentration: 10 to 20 ppm, hydrogen concentration: 1.4 ppm) at room temperature was used in a single wafer type cleaning machine. Then, ultrasonic waves (megasonic: frequency 1.5 MHz) were applied for 30 minutes, and then rinsed with pure water. When the phase shift film pattern of the halftone phase shift mask after rinsing was observed with an electron microscope, no pattern defect was confirmed.

  Further, an electron beam resist film is formed on the second layer of the phase shift mask blank formed with the second layer containing Cr on the halftone phase shift film made of SiN formed under the same conditions, After pattern drawing with an electron beam, a resist pattern is obtained by a predetermined development operation, and then the resist pattern is formed on the second layer by chlorine-based dry etching containing oxygen using the obtained resist pattern as an etching mask. The pattern of the second layer is formed by transfer, and the pattern of the second layer is transferred to the phase shift film by fluorine-based dry etching using the obtained pattern of the second layer as an etching mask. A shift film pattern was obtained, and the resist pattern and the second layer were removed by a conventional method to obtain a phase shift mask. The obtained phase shift mask could be corrected by a correction device using an electron beam.

[Example 2]
A 152 mm square, 6.35 mm thick 6025 quartz substrate was installed in the chamber of the sputtering apparatus, a silicon target was used as the sputtering target, argon gas and nitrogen gas were used as the sputtering gas, and the power applied to the target was 1,900 W, A halftone phase shift film made of SiN was formed with an argon gas flow rate of 17 sccm and a nitrogen gas flow rate of 30 sccm. Thereafter, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 179 °, a transmittance of 7%, and a film thickness of 61 nm. Further, when the composition of this film was measured by XPS, the atomic ratio was Si: N = 47: 52.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. Observation with an electron microscope revealed no pattern defects.

[Example 3]
A 152 mm square, 6.35 mm thick 6025 quartz substrate is installed in the chamber of the sputtering apparatus, a silicon target is used as the sputtering target, argon gas, nitrogen gas and oxygen gas are used as the sputtering gas, and the power applied to the target is 1 , 900 W, argon gas flow rate of 15 sccm, nitrogen gas flow rate of 40 sccm, oxygen gas flow rate of 2 sccm, and a halftone phase shift film made of SiON was formed. Thereafter, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 175 °, a transmittance of 24%, and a film thickness of 63 nm. Further, when the composition of this film was measured by XPS, the atomic ratio was Si: N: O = 43: 48: 8.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. Observation with an electron microscope revealed no pattern defects.

[Example 4]
A 152 mm square, 6.35 mm thick 6025 quartz substrate is installed in the chamber of the sputtering apparatus, a silicon target is used as the sputtering target, argon gas, nitrogen gas and oxygen gas are used as the sputtering gas, and the power applied to the target is 1 , 900 W, the flow rate of argon gas is 15 sccm, the flow rate of nitrogen gas is 40 sccm, and a SiN layer is formed. Subsequently, the power applied to the target is 1,900 W, the flow rate of argon gas is 10 sccm, The flow rate was 40 sccm, the flow rate of oxygen gas was 10 sccm, a layer made of SiON was formed, and a halftone phase shift film in which a layer made of SiN and a layer made of SiON were laminated was formed. Thereafter, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after this heat treatment had a phase difference of 177 °, a transmittance of 29%, and a film thickness of 66 nm. Further, when the composition of this film was measured by XPS, the layer made of SiN was Si: N = 45: 54 by atomic ratio, and the layer made of SiON was Si: N: O = 38: 20: 41 by atomic ratio. Met.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. Observation with an electron microscope revealed no pattern defects.

[Comparative Example 1]
A 15225 mm square, 6.35 mm thick 6025 quartz substrate is placed in the chamber of the sputtering apparatus, a mixed target of molybdenum and silicon (molybdenum: silicon = 1: 2 (molar ratio)), a silicon target, and a sputter as a sputtering target. Argon gas, nitrogen gas and oxygen gas are used as the gas, the power applied to the molybdenum and silicon target is 646 W, the power applied to the silicon target is 1,292 W, the flow rate of argon gas is 8.5 sccm, the flow rate of nitrogen gas Was 65 sccm and the flow rate of oxygen gas was 3 sccm, and a halftone phase shift film made of MoSiON was formed. Thereafter, heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 177 °, a transmittance of 6%, and a film thickness of 75 nm. Moreover, when the composition of this film was measured by XPS, the atomic ratio was Mo: Si: N: O = 9: 35: 46: 10.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. When observed with an electron microscope, a portion where the pattern was missing was confirmed.

[Comparative Example 2]
A 15225 mm square, 6.35 mm thick 6025 quartz substrate is placed in the chamber of the sputtering apparatus, a mixed target of molybdenum and silicon (molybdenum: silicon = 1: 2 (molar ratio)), a silicon target, and a sputter as a sputtering target. Argon gas, nitrogen gas, and oxygen gas are used as the gas. The power applied to the mixed target of molybdenum and silicon is 400 W, the power applied to the silicon target is 1,600 W, the flow rate of argon gas is 17 sccm, and the flow rate of nitrogen gas is 55 sccm. A halftone phase shift film made of MoSiON was formed at a flow rate of oxygen gas of 4 sccm. Thereafter, heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 177 °, a transmittance of 9%, and a film thickness of 75 nm. Moreover, when the composition of this film was measured by XPS, the atomic ratio was Mo: Si: N: O = 7: 39: 40: 14.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. When observed with an electron microscope, a portion where the pattern was missing was confirmed.

[Comparative Example 3]
A 15225 mm square, 6.35 mm thick 6025 quartz substrate is placed in the chamber of the sputtering apparatus, a mixed target of molybdenum and silicon (molybdenum: silicon = 1: 2 (molar ratio)), a silicon target, and a sputter as a sputtering target. Argon gas, nitrogen gas and oxygen gas are used as the gas, the power applied to the molybdenum and silicon mixed target is 300 W, the power applied to the silicon target is 1,700 W, the flow rate of argon gas is 18 sccm, the flow rate of nitrogen gas is 58 sccm. A halftone phase shift film made of MoSiON was formed at a flow rate of oxygen gas of 3.8 sccm. Thereafter, heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 177 °, a transmittance of 12%, and a film thickness of 75 nm. Moreover, when the composition of this film | membrane was measured by XPS, it was Mo: Si: N: O = 5: 40: 42: 12 by atomic ratio.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. When observed with an electron microscope, a portion where the pattern was missing was confirmed.

[Comparative Example 4]
A 15225 mm square, 6.35 mm thick 6025 quartz substrate is placed in the chamber of the sputtering apparatus, a mixed target of molybdenum and silicon (molybdenum: silicon = 1: 2 (molar ratio)), a silicon target, and a sputter as a sputtering target. Argon gas, nitrogen gas and oxygen gas are used as the gas, the power applied to the molybdenum and silicon mixed target is 400 W, the power applied to the silicon target is 1,600 W, the flow rate of argon gas is 15 sccm, and the flow rate of nitrogen gas is 65 sccm. A halftone phase shift film made of MoSiON was formed at a flow rate of oxygen gas of 9.3 sccm. Thereafter, heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 177 °, a transmittance of 20%, and a film thickness of 94 nm. Further, when the composition of this film was measured by XPS, the atomic ratio was Mo: Si: N: O = 5: 35: 23: 36.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. When observed with an electron microscope, a portion where the pattern was missing was confirmed.

[Comparative Example 5]
A 15225 mm square, 6.35 mm thick 6025 quartz substrate is placed in the chamber of the sputtering apparatus, a mixed target of molybdenum and silicon (molybdenum: silicon = 1: 2 (molar ratio)), a silicon target, and a sputter as a sputtering target. Argon gas, nitrogen gas, and oxygen gas are used as the gas. The power applied to the mixed target of molybdenum and silicon is 600 W, the power applied to the silicon target is 1,400 W, the flow rate of argon gas is 15 sccm, and the flow rate of nitrogen gas is 65 sccm. A halftone phase shift film made of MoSiON was formed at a flow rate of oxygen gas of 16.9 sccm. Thereafter, heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after this heat treatment had a phase difference of 177 °, a transmittance of 22%, and a film thickness of 114 nm. Moreover, when the composition of this film was measured by XPS, the atomic ratio was Mo: Si: N: O = 6: 30: 11: 53.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. When observed with an electron microscope, a portion where the pattern was missing was confirmed.

[Comparative Example 6]
A 15225 mm square, 6.35 mm thick 6025 quartz substrate is placed in the chamber of the sputtering apparatus, a mixed target of molybdenum and silicon (molybdenum: silicon = 1: 2 (molar ratio)), a silicon target, and a sputter as a sputtering target. Argon gas, nitrogen gas and oxygen gas are used as the gas, the power applied to the molybdenum and silicon mixed target is 150 W, the power applied to the silicon target is 1,850 W, the flow rate of argon gas is 15 sccm, the flow rate of nitrogen gas is 70 sccm. A halftone phase shift film made of MoSiON was formed at a flow rate of oxygen gas of 5.3 sccm. Thereafter, heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were approximately equal to the atmospheric partial pressure in a heat treatment furnace to obtain halftone phase shift mask blanks. The halftone phase shift film after the heat treatment had a phase difference of 177 °, a transmittance of 30%, and a film thickness of 83 nm. Further, when the composition of this film was measured by XPS, the atomic ratio was Mo: Si: N: O = 2: 40: 30: 28.

  Next, using the obtained halftone phase shift mask blanks, a pattern is formed in the same manner as in Example 1, and cleaning is performed in the same manner, and the phase shift film pattern of the halftone phase shift mask after cleaning is formed. When observed with an electron microscope, a portion where the pattern was missing was confirmed.

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

Claims (5)

A halftone phase shift mask blank having a halftone phase shift film having a phase shift amount of 150 to 200 ° with light having a wavelength of 200 nm or less on a transparent substrate,
The halftone phase shift film includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen, and has a transmittance of 3% to 20% with light having a wavelength of 200 nm or less. And having a second layer consisting of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film, and having a film thickness of 62 nm or less. And a third layer composed of a single layer or a plurality of layers made of a material containing silicon, and the second layer functions as a hard mask in patterning the halftone phase shift film, and A processing auxiliary film that functions as an etching stopper in pattern formation of the third layer, wherein the third layer is a light shielding film or a combination of a light shielding film and an antireflection film. Half-tone phase shift mask blanks that. A halftone phase shift mask blank having a halftone phase shift film having a phase shift amount of 150 to 200 ° with light having a wavelength of 200 nm or less on a transparent substrate,
The halftone phase shift film includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen, and has a transmittance of 20% to 30% with light having a wavelength of 200 nm or less. And having a second layer consisting of a single layer or a plurality of layers made of a material containing chromium on the halftone phase shift film, and having a film thickness of 70 nm or less. And a third layer composed of a single layer or a plurality of layers made of a material containing silicon, and the second layer functions as a hard mask in patterning the halftone phase shift film, and A processing auxiliary film that functions as an etching stopper in pattern formation of the third layer, wherein the third layer is a light shielding film or a combination of a light shielding film and an antireflection film. Half-tone phase shift mask blanks to be.   3. The halftone phase shift mask blank according to claim 1, 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. .   4. The halftone phase shift mask blank according to claim 3, wherein the fourth layer is a processing auxiliary film that functions as a hard mask in pattern formation of the third layer. A method for producing a halftone phase shift mask blank according to any one of claims 1 to 4 , comprising a step of forming a halftone phase shift film on a transparent substrate by sputtering.
The step of forming the halftone phase shift film comprises:
(A) On a transparent substrate, using a sputtering apparatus, using at least one silicon target, introducing argon gas and nitrogen gas into the sputtering chamber, and forming a layer composed of a silicon-based material composed of silicon and nitrogen (B) Sputtering argon gas and at least one gas selected from nitrogen gas, oxygen gas, and nitrogen oxide gas on a transparent substrate using a sputtering apparatus and using at least one silicon target. One or both of the steps of introducing into the chamber and forming a layer composed of a silicon-based material consisting of silicon, nitrogen and oxygen,
The method for manufacturing a halftone phase shift mask blank, further comprising a step of heat-treating the halftone phase shift film formed on the transparent substrate at 400 ° C. or more for 5 minutes or more.

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