JP2022079179A - Mask blank, phase shift mask, and method for producing semiconductor device - Google Patents

Abstract

To provide a mask blank including a phase shift film that includes a laminate structure of a high nitride layer with a relatively high nitrogen content and a low nitride layer with a relatively low nitrogen content, wherein the phase shift film has good in-plane uniformity of transmittance and phase difference and has film stress within an allowable range.SOLUTION: A mask blank includes a phase shift film on a light-transmissive substrate, the phase shift film including a high nitride layer and a low nitride layer, the high nitride layer and the low nitride layer including silicon, nitrogen, krypton and xenon.SELECTED DRAWING: Figure 3

Description

The present invention relates to a mask blank and a phase shift mask manufactured by using the mask blank. The present invention also relates to a method for manufacturing a semiconductor device using the above-mentioned phase shift mask.

In the manufacturing process of a semiconductor device, a fine pattern is formed by using a photolithography method. In addition, a number of transfer masks are usually used to form this fine pattern. In order to miniaturize the pattern of a semiconductor device, it is necessary to shorten the wavelength of the exposure light source used in photolithography in addition to miniaturizing the mask pattern formed on the transfer mask. In recent years, ArF excimer lasers (wavelength 193 nm) have been increasingly applied to exposure light sources for manufacturing semiconductor devices.

There is a halftone type phase shift mask as a kind of transfer mask. As a phase shift film of a halftone type phase shift mask, one formed of a material containing nitrogen and silicon is known. For example, Patent Document 1 describes, as a method for producing a mask blank provided with such a phase shift film, a silicon target or a material containing silicon and one or more elements selected from semi-metal elements and non-metal elements. By reactive sputtering in a sputtering gas containing nitrogen-based gas, krypton gas and helium gas, a low-permeability layer having a relatively low nitrogen content is formed as compared with the high-permeability layer and the high-permeability layer. It is disclosed that the present invention includes a phase shift film forming step of forming a phase shift film and a heat treatment step of performing a heat treatment at a temperature of 300 ° C. or higher.

Further, in Patent Document 2, as a method for producing a mask blank provided with such a phase shift film, a silicon target or a material containing silicon and one or more elements selected from semi-metal elements and non-metal elements is used. By reactive sputtering in a sputtering gas containing a nitrogen-based gas, xenone and helium gas, a low-permeability layer is formed with a relatively low nitrogen content as compared with the high-permeability layer and the high-permeability layer. It is disclosed that the present invention includes a phase shift film forming step of forming a phase shift film and a heat treatment step of performing a heat treatment at a temperature of 180 ° C. or higher.

Further, Patent Document 3 discloses a method for producing a silicon nitride film effective as a mask material for X-ray lithography. Specifically, in a method for producing a silicon nitride thin film by a reactive sputtering method, a predetermined amount of krypton gas is introduced into a nitrogen gas plasma, and the silicon nitride is nitrided under sputter conditions in which the internal stress of the formed thin film becomes a tensile stress. A method for producing a silicon nitride thin film including at least a step of depositing a silicon thin film is disclosed.

Further, in Patent Document 4, in a phase shift film including a structure in which a low transmission layer and a high transmission layer are laminated, the low transmission layer and the high transmission layer are made of a material made of silicon and nitrogen, or a semimetal element in the material. A mask blank made of a material containing one or more elements selected from non-metal elements and rare gases, the low permeable layer provided with a phase shift film having a relatively low nitrogen content compared to the high permeable layer. Is disclosed.

Japanese Unexamined Patent Publication No. 2016-20949 Japanese Unexamined Patent Publication No. 2016-20950 Japanese Unexamined Patent Publication No. 8-115912 Japanese Unexamined Patent Publication No. 2014-137388

As described above, conventionally, a phase shift mask including a phase shift film including a laminated structure of a high nitride layer having a relatively high nitrogen content and a low nitride layer having a relatively low nitrogen content is known. .. However, in recent years, there has been an increasing demand for miniaturization and complexity of mask patterns formed on transfer masks. In order to meet this requirement, it is desired to further improve the in-plane uniformity of the transmittance and phase difference required in the phase shift film. On the other hand, it has been found that when an attempt is made to increase the in-plane uniformity of the transmittance and the phase difference, the film stress becomes excessive and it becomes difficult to satisfy the required quality.

Therefore, the present invention has been made to solve the conventional problems, and is a phase shift including a laminated structure of a high nitride layer having a relatively high nitrogen content and a low nitride layer having a relatively low nitrogen content. It is an object of the present invention to provide a mask blank having a phase shift film having good in-plane uniformity of transmittance and phase difference and a film stress within an allowable range. Another object of the present invention is to provide a phase shift mask manufactured by using this mask blank. An object of the present invention is to provide a method for manufacturing a semiconductor device using such a phase shift mask.

In order to solve the above problems, the present invention has the following configurations.
(Structure 1)
A mask blank with a phase shift film on a translucent substrate.
The phase shift film includes a high nitriding layer and a low nitriding layer.
The mask blank, wherein the high nitriding layer and the low nitriding layer contain silicon, nitrogen, krypton and xenon.

(Structure 2)
The mask blank according to Configuration 1, wherein the highly nitrided layer has a nitrogen content of 50 atomic% or more.
(Structure 3)
The mask blank according to the configuration 1 or 2, wherein the low nitride layer has a nitrogen content of less than 50 atomic%.

(Structure 4)
The mask blank according to Configuration 1, wherein the high-nitriding layer and the low-nitriding layer have a total content of silicon, nitrogen, krypton, and xenon of 90 atomic% or more.
(Structure 5)
The mask according to any one of configurations 1 to 4, wherein the total thickness of the high nitride layer and the low nitride layer is 70% or more of the thickness of the phase shift film. blank.
(Structure 6)
The mask blank according to any one of configurations 1 to 5, wherein the phase shift film includes a structure in which two or more high-nitriding layers and two or more low-nitriding layers are alternately laminated.

(Structure 7)
The phase shift film has a function of transmitting the exposure light of the ArF excimer laser with a transmittance of 2% or more, and is in the air for the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. The mask blank according to any one of configurations 1 to 6, wherein the mask blank has a function of causing a phase difference of 150 degrees or more and 210 degrees or less with the exposed light that has passed through.
(Structure 8)
The mask blank according to any one of configurations 1 to 7, wherein a light-shielding film is provided on the phase shift film.

(Structure 9)
A phase shift mask provided with a phase shift film in which a transfer pattern is formed on a translucent substrate.
The phase shift film includes a high nitriding layer and a low nitriding layer.
The high nitriding layer and the low nitriding layer contain silicon, nitrogen, krypton and xenon.
A phase shift mask characterized by that.
(Structure 10)
The phase shift mask according to the configuration 9, wherein the highly nitrided layer has a nitrogen content of 50 atomic% or more.

(Structure 11)
The phase shift mask according to the configuration 9 or 10, wherein the low nitride layer has a nitrogen content of less than 50 atomic%.
(Structure 12)
The phase shift mask according to any one of configurations 9 to 11, wherein the high nitride layer and the low nitride layer have a total content of silicon, nitrogen, krypton and xenon of 90 atomic% or more.

(Structure 13)
The phase according to any one of configurations 9 to 12, wherein the total thickness of the thickness of the high nitride layer and the thickness of the low nitride layer is 70% or more of the thickness of the phase shift film. Shift mask.
(Structure 14)
The phase shift mask according to any one of configurations 9 to 13, wherein the phase shift film includes a structure in which two or more high nitride layers and two or more low nitride layers are alternately laminated.

(Structure 15)
The phase shift film has a function of transmitting the exposure light of the ArF excimer laser with a transmission rate of 2% or more, and the exposure light transmitted through the phase shift film is in the air by the same distance as the thickness of the phase shift film. The phase shift mask according to any one of configurations 9 to 14, further comprising a function of causing a phase difference of 150 degrees or more and 210 degrees or less with the exposed light that has passed through.

(Structure 16)
The phase shift mask according to any one of configurations 9 to 15, wherein a light-shielding film having a light-shielding pattern formed on the phase-shift film is provided.
(Structure 17)
A method for manufacturing a semiconductor device, comprising a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the phase shift mask according to any one of configurations 9 to 16.

The mask blank of the present invention is a mask blank provided with a phase shift film on a translucent substrate, wherein the phase shift film includes a high nitride layer and a low nitride layer, and the high nitride layer and the low nitride layer. Is characterized by containing silicon, nitrogen, krypton and xenon. By using a mask blank having such a structure, in-plane uniformity of transmittance and phase difference can be obtained in a phase shift film including a laminated structure of a high nitride layer having a high nitrogen content and a low nitride layer having a low nitrogen content. It is good and the film stress can be within the permissible range.

Further, the phase shift mask of the present invention is characterized in that the phase shift film having a transfer pattern has the same configuration as the phase shift film of the mask blank of the present invention. By using such a phase shift mask, in-plane uniformity of transmittance and phase difference is good in a phase shift film including a laminated structure of a high nitride layer having a high nitrogen content and a low nitride layer having a low nitrogen content. The film stress can be kept within the allowable range. Therefore, the phase shift mask of the present invention is a phase shift mask with high transfer accuracy.

It is sectional drawing which shows the structure of the mask blank in embodiment of this invention. It is sectional drawing which shows the manufacturing process of the phase shift mask in embodiment of this invention. 6 is a graph showing the relationship between the in-plane distribution of the phase shift amount and the flatness in the mask blanks in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention. It is a graph which shows the relationship between the in-plane distribution of transmittance, and the flatness in the mask blank in Examples 1 and 2 and Comparative Examples 1 and 2 of this invention. It is a graph which shows the observation result of HR-RBS in Example 2 of this invention. It is a graph which shows the observation result of HR-RBS in the comparative example 2 of this invention.

First, the circumstances leading to the completion of the present invention will be described. The present inventors have in-plane uniformity of transmittance and phase difference in a phase shift film including a laminated structure of a high nitride layer having a relatively high nitrogen content and a low nitride layer having a relatively low nitrogen content. A diligent study was conducted on a mask blank with a phase-shifted film that was good and the film stress was within the permissible range.

Generally, when a thin film of a metal compound is formed by a sputtering method, there are roughly the following two methods.
The first method is to preliminarily form a spatter target with a metal compound having the same composition as the thin film. In this case, the sputtered particles are laminated on the substrate by sputtering using only the noble gas as the sputter gas, and a thin film of the metal compound is formed on the substrate.
The second method is to form the spatter target with the same metal as the metal component of the thin film. In this case, the sputter particles and the compound of the non-metal element are laminated on the substrate by reactive sputtering using a mixed gas of a gas containing a non-metal element (for example, N ₂ gas) and a noble gas in the thin film as a sputter gas, and the metal is formed. A thin film of the compound is formed on the substrate.

In a phase shift film containing a laminated structure of a high nitride layer having a relatively high nitrogen content and a low nitride layer having a relatively low nitrogen content, the Si target is used when forming a film by the second method described above. By using reactive sputtering using a mixed gas of _N2 gas (reactive gas), Kr gas and He gas (noble gas) as the sputter gas, the flow ratio of nitrogen gas in the sputter gas can be increased or decreased. , The degree of nitridement of each layer formed on the substrate is adjusted. The present inventors first examined adjusting the film forming conditions such as the flow rate ratio of each gas in the sputter gas, the gas pressure in the sputter chamber, and the sputter power, but could not sufficiently improve them.

Next, the present inventors attempted to remove the He gas from the noble gas of the sputter gas to form a film (that is, the sputter gas is only _N2 gas and Kr gas). As a result, the uniformity of the phase difference and the uniformity of the transmittance in the plane of this phase shift film could be improved within a desired range. However, the film stress of this phase shift film is further increased (the substrate had a stress of large deformation in the convex direction. The absolute value of the stress is larger than that before the change), and this film stress is also at the same time. It was necessary to find a film formation method to reduce the film formation.
As a result of further research by the present inventor, it has been found that the noble gas of the sputter gas is a mixed gas containing Kr gas and Xe gas, and a phase shift film is formed by reactive sputtering. The phase shift film formed by the film forming method has a height in which the uniformity of the in-plane phase difference and the uniformity of the transmittance with respect to the ArF exposure light meet the predetermined criteria, and the film stress after the annealing treatment is also a problem. It turned out that there was no range. Further, even when the spatter target is formed in advance by a method of forming a metal compound having the same composition as the phase shift film, the noble gas of the sputter gas is a mixed gas containing Kr gas and Xe gas, so that ArF exposure light is obtained. It was found that the uniformity of the in-plane phase difference and the uniformity of the permeability with respect to the relative gas reached a height satisfying a predetermined standard, and the film stress after the annealing treatment was also within the range of no problem.
By using a mixed gas containing Kr gas and Xe gas as the noble gas of the sputter gas, the present inventors can improve the spread of the plasma distribution of the mixed gas in the film forming chamber at the time of film formation, thereby, as described above. It is presumed that the desired effect can be obtained. However, this inference is based on the inferences of the present inventors at the time of filing, and does not limit the scope of the present invention in any way.

As described above, the mask blank of the present invention is a mask blank provided with a phase shift film on a translucent substrate, and the phase shift film includes a high nitriding layer and a low nitriding layer, and the high nitriding layer and low nitriding layer. The layer is characterized by containing silicon, nitrogen, krypton and xenon.

Next, each embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing the configuration of the mask blank 100 according to the embodiment of the present invention. The mask blank 100 shown in FIG. 1 has a structure in which a phase shift film 2, a light shielding film 3, and a hard mask film 4 are laminated in this order on a translucent substrate 1.

The translucent substrate 1 can be formed of, in addition to synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.) and the like. Among these, synthetic quartz glass has a high transmittance for ArF excimer laser light (wavelength 193 nm), and is particularly preferable as a material for forming a translucent substrate of a mask blank.

In order for the phase shift film 2 to effectively function the phase shift effect, the transmission rate of the ArF excimer laser with respect to the exposure light (hereinafter referred to as ArF exposure light) is preferably 1% or more, preferably 2% or more. It is more preferable to have it. Further, the phase shift film 2 is preferably adjusted so that the transmittance with respect to the ArF exposure light is 30% or less, more preferably 20% or less, and further preferably 18% or less.
Further, in the phase shift film 2, the in-plane distribution (in-plane uniformity) of the transmittance with respect to the ArF exposure light is preferably 0.2% or less (within ± 0.2%) in absolute value with respect to the target value. , The absolute value is more preferably 0.18% or less (within ± 0.18%).

In order to obtain an appropriate phase shift effect, the phase shift film 2 causes a predetermined phase difference between the transmitted ArF exposed light and the light that has passed through the air by the same distance as the thickness of the phase shift film 2. It is required to have a function to generate it. Further, it is preferable that the phase difference is adjusted so as to be in the range of 150 degrees or more and 210 degrees or less. The lower limit of the phase difference in the phase shift film 2 is more preferably 160 degrees or more, and further preferably 170 degrees or more. On the other hand, the upper limit of the phase difference in the phase shift film 2 is more preferably 200 degrees or less, and further preferably 190 degrees or less.
Further, in the phase shift film 2, it is preferable that the in-plane distribution (in-plane uniformity) of the phase difference with respect to the ArF exposure light is 1.0 degree or less (within ± 1.0 degree) in absolute value with respect to the target value. ..

The phase shift film 2 of the present invention includes at least a structure (two-layer structure) having a set of a laminated structure composed of a high nitride layer 22 and a low nitride layer 21. The phase shift film 2 of the present invention includes a structure in which two or more high nitride layers 22 and two or more low nitride layers 21 are alternately laminated, which is a pattern side wall when the phase shift film 2 is patterned by etching. It is preferable from the viewpoint of controllability. The phase shift film 2 of FIG. 1 includes five sets of one set of laminated structures including a high nitride layer 22 and a low nitride layer 21. The phase shift film 2 includes five sets of laminated structures in which the high nitride layer 22 and the low nitride layer 21 are laminated in this order from the translucent substrate 1 side, and the uppermost layer 23 is placed on the uppermost low nitride layer 21. Has a further laminated structure.

The high nitride layer 22 and the low nitride layer 21 are formed of a material containing silicon, nitrogen, krypton and xenon. Noble gases containing krypton and xenon are elements that can increase the film forming speed and improve productivity by being present in the film forming chamber when forming a thin film by reactive sputtering. When this noble gas turns into plasma and collides with the target, the target constituent elements pop out from the target, and while taking in the reactive gas on the way, they are laminated on the translucent substrate 1 to form a thin film. A small amount of noble gas in the film forming chamber is taken in until the target constituent element jumps out of the target and adheres to the translucent substrate. As described above, by using krypton and xenon as the noble gases required for this reactive sputtering, the in-plane uniformity of transmittance and phase difference is good, and the film stress is within the allowable range. The phase shift film 2 can be formed.

From the viewpoint of light resistance to ArF exposure light, the low nitride layer 21 and the high nitride layer 22 preferably have a transition metal content of less than 1 atomic%, and more preferably no transition metal. .. Further, it is desirable that the high nitride layer 22 and the low nitride layer 21 do not contain any metal element other than the transition metal from the viewpoint of light resistance to ArF exposure light. The high nitride layer 22 and the low nitride layer 21 are made of a material composed of silicon, nitrogen, krypton and xenon, or a material composed of one or more elements selected from metalloid elements and non-metal elements and silicon, nitrogen, krypton and xenon. It is preferable to form it. The high nitride layer 22 and the low nitride layer 21 may contain any metalloid element in addition to silicon. Among these metalloid elements, it is preferable to contain one or more elements selected from boron, germanium, antimony and tellurium because it can be expected to increase the conductivity of silicon used as a sputtering target.

The high nitride layer 22 and the low nitride layer 21 may contain any non-metal element in addition to silicon, nitrogen, krypton and xenon. Here, the non-metal element in the present invention means a non-metal element (nitrogen, carbon, oxygen, phosphorus, sulfur, selenium) in a narrow sense, a halogen and a noble gas other than krypton and xenone. Among these non-metal elements, it is preferable to contain one or more elements selected from carbon, fluorine and hydrogen. The high nitride layer 22 and the low nitride layer 21 preferably have an oxygen content of 10 atomic% or less, more preferably 5 atomic% or less, and do not actively contain oxygen (X-rays). It is more preferable that it is equal to or less than the lower limit of detection when the composition is analyzed by photoelectron spectroscopy or the like. When oxygen is contained in the silicon nitride-based material film, the extinction coefficient k tends to be significantly reduced, and the overall thickness of the phase shift film 2 becomes thick.
The high nitride layer 22 and the low nitride layer 21 preferably have a total content of silicon, nitrogen, krypton and xenon of 90 atomic% or more, more preferably 95 atomic% or more, and 98 atomic% or more. It is even more preferable, and it is even more preferable that the content is 99 atomic% or more.

The translucent substrate is generally made of a material containing SiO ₂ as a main component, such as synthetic quartz glass. When either the high nitride layer 22 or the low nitride layer 21 is formed in contact with the surface of the translucent substrate 1, when the layer contains oxygen, the composition of the silicon nitride-based material film containing oxygen and the composition of the glass are formed. In dry etching with a fluorine-based gas, which is performed when a pattern is formed on the phase shift film 2, the layer (high nitride layer 22 or low nitride layer 21) in contact with the translucent substrate 1 and translucency are transmitted. There may be a problem that it becomes difficult to obtain etching selectivity with the sex substrate 1.

The high nitride layer 22 and the low nitride layer 21 may contain noble gases other than krypton and xenon. However, from the viewpoint of relaxation of film stress and in-plane uniformity, it is preferable not to positively contain noble gases other than krypton and xenon. That is, the noble gas is preferably krypton and xenon only.

The nitrogen content of the high nitride layer 22 is preferably 50 atomic% or more. The silicon-based film has a very small refractive index n with respect to ArF exposed light and a large extinction coefficient k with respect to ArF exposed light (hereinafter, when simply referred to as refractive index n, it means the refractive index n with respect to ArF exposed light. When simply expressed as the extinction coefficient k, it means the extinction coefficient k with respect to the ArF exposure light). As the nitrogen content in the silicon-based film increases, the refractive index n tends to increase and the extinction coefficient k tends to decrease. In order to secure the transmittance required for the phase shift film 2 and also secure the phase difference required for a thinner thickness, it is desired that the nitrogen content of the high nitride layer 22 be 50 atomic% or more. The nitrogen content of the high nitride layer 22 is preferably 52 atomic% or more. The nitrogen content of the high nitride layer 22 is preferably 57 atomic% or less, and more preferably 55 atomic% or less.

The nitrogen content of the low nitride layer 21 is preferably less than 50 atomic%. The nitrogen content of the low nitride layer 21 is preferably 48 atomic% or less, and more preferably 45 atomic% or less. The nitrogen content of the low nitride layer 21 is preferably 20 atomic% or more, and more preferably 25 atomic% or more. In order to secure the transmittance required for the phase shift film 2 and also secure the phase difference required for a thinner thickness, it is desired that the nitrogen content of the low nitride layer 21 be 20 atomic% or more.

The high nitride layer 22 and the low nitride layer 21 are preferably made of the same constituent elements. When either the high nitride layer 22 or the low nitride layer 21 contains different constituent elements and heat treatment or light irradiation treatment is performed in a state where these are in contact with each other and laminated, or when ArF exposure light is irradiated. If so, the different constituent elements may move to and diffuse to the layer on the side that does not contain the constituent elements. Then, the optical characteristics of the high nitride layer 22 and the low nitride layer 21 may change significantly from the beginning of film formation. Further, particularly when the different constituent elements are metalloid elements, it becomes necessary to form a film of the high nitride layer 22 and the low nitride layer 21 using different targets.
The high nitride layer 22 in the present embodiment preferably has a higher transmittance for ArF exposure light than the low nitride layer 21. In this case, the high nitride layer 22 functions as a high transmission layer and the low nitride layer 21 functions as a low transmission layer.

The high nitride layer 22 and the low nitride layer 21 are preferably formed of a material composed of silicon, nitrogen, krypton and xenon. Noble gases such as krypton and xenon are elements that are difficult to detect even by performing composition analysis such as RBS (Rutherford Back-Scattering Spectroscopy) or XPS (X-ray Photoelectron Spectroscopy) on a thin film. The high nitriding layer 22 and the low nitriding layer 21 preferably contain krypton and xenon at levels detected by HR-RBS (High Resolution Rutherford Backscattering Analysis). Further, it is more preferable that the high nitriding layer 22 and the low nitriding layer 21 contain krypton and xenon at the levels detected by the usual composition analysis of RBS or XPS.

The thickness of the high nitride layer 22 is preferably 20 nm or less from the viewpoint of controllability of the side wall of the pattern when the high nitride layer 22 is patterned by etching. The thickness of the high nitride layer 22 is preferably 15 nm or less, and more preferably 10 nm or less. On the other hand, the thickness of the high nitride layer 22 is preferably 3 nm or more, more preferably 4 nm or more, and further preferably 5 nm or more. If the thickness of the high nitride layer 22 is less than 3 nm, the low nitride layer 21 needs to be thinner than that, as will be described later. Such a thin low nitride layer 21 is only a mixed region (about 0.1 to 2 nm) in which the constituent elements of the low transmission layer and the constituent elements of the high transmission layer are mixed, which is desired for the low nitride layer 21. There is a risk that the optical characteristics of will not be obtained. It is assumed that the thickness of the high nitride layer 22 here includes the above-mentioned mixed region.

The thickness of the low nitride layer 21 is preferably thinner than that of the high nitride layer 22. When the thickness of the low nitride layer 21 is equal to or larger than the thickness of the high nitride layer 22, it becomes difficult for such a phase shift film 2 to obtain the required transmittance and phase difference. The thickness of the low nitride layer 21 is preferably 15 nm or less, and more preferably 10 nm or less. The thickness of the low nitride layer 21 is preferably 2 nm or more, and more preferably 3 nm or more.

The thickness of the low nitride layer 21 is preferably ½ or less of the thickness of the high nitride layer 22. The low nitride layer 21 has a smaller refractive index n with respect to ArF exposure light and a larger extinction coefficient k with respect to ArF exposure light than the high nitride layer 22. Therefore, when the total film thickness of the low nitride layer becomes larger than 1/2 of the total film thickness of the high nitride layer, it becomes difficult to adjust the phase shift film 2 to a desired transmittance and phase difference.

The number of sets of the laminated structure composed of the high nitride layer 22 and the low nitride layer 21 in the phase shift film 2 is preferably 2 sets (4 layers in total) or more, and 4 sets (8 layers in total) or more. preferable. Further, the number of sets of the laminated structure composed of the high nitride layer 22 and the low nitride layer 21 in the phase shift film 2 is preferably 10 sets (20 layers in total) or less, and 9 sets (18 layers in total) or less. More preferably, it is more preferably 8 sets (16 layers in total) or less. It is preferable that the high nitride layer 22 and the low nitride layer 21 in the phase shift film 2 have a structure in which they are directly in contact with each other and laminated without interposing another film.

EB defect correction for the phase shift film ₂ (This "EB defect correction" removes black defects by irradiating the black defect portion of the thin film pattern with an electron beam while supplying a gas containing fluorine such as XeF2. From the viewpoint of the end point detection accuracy of defect correction), the laminated structure composed of the high nitride layer 22 and the low nitride layer 21 has the high nitride layer 22 and the low nitride layer 21 from the translucent substrate 1 side. It is preferable to stack them in this order.

The translucent substrate 1 is made of a material containing silicon oxide as a main component. It is advantageous to arrange the highly nitrided layer 22 having a high nitrogen content in the layer on the side of the phase shift film 2 in contact with the translucent substrate 1 in order to detect the end point at the time of EB defect correction.

On the other hand, when forming a pattern on the phase shift film 2 of a silicon nitride-based material by dry etching, a fluorine-based gas having a relatively small dry etching etching rate for the translucent substrate 1 such as SF ₆ is generally used. It is a target. For dry etching with a fluorine-based gas such as SF ₆ , the low nitride layer 21 having a low nitrogen content can have higher etching selectivity with the translucent substrate 1. From the viewpoint of dry etching for the phase shift film 2, in the laminated structure composed of the high nitride layer 22 and the low nitride layer 21, the low nitride layer 21 and the high nitride layer 22 are laminated in this order from the translucent substrate 1 side. Is preferable.

The high nitride layer 22 has a refractive index n of 2.5 or more (preferably 2.6 or more) and an extinction coefficient k of less than 1.0 (preferably 0.9 or less, more preferably 0) with respect to ArF exposure light. It is preferably formed of a material having a coefficient of 0.7 or less, more preferably 0.5 or less). Further, the low nitride layer 21 has a refractive index n of less than 2.5 (preferably 2.4 or less, more preferably 2.2 or less) and an extinction coefficient k of 1.0 or more (preferably 1. It is preferably formed of a material having a value of 1 or more, more preferably 1.4 or more). When the phase shift film 2 is configured with a laminated structure of 6 or more layers, the high nitride layer 22 is required to satisfy a predetermined phase difference and a predetermined transmittance with respect to ArF exposure light, which is an optical characteristic required for the phase shift film 2. This is because it is difficult to realize the low nitride layer 21 and the low nitride layer 21 unless they are within the ranges of the above-mentioned refractive index n and extinction coefficient k, respectively.

The refractive index n and the extinction coefficient k of the thin film are not determined only by the composition of the thin film. The film density and crystal state of the thin film are also factors that influence the refractive index n and the extinction coefficient k. Therefore, various conditions for forming a thin film by reactive sputtering are adjusted so that the thin film has a desired refractive index n and an extinction coefficient k. In order to make the high nitride layer 22 and the low nitride layer 21 within the ranges of the above-mentioned refractive index n and extinction coefficient k, the ratio of the mixed gas of the noble gas and the reactive gas is set when the film is formed by reactive sputtering. It is not limited to adjusting. There are various positional relationships such as the pressure in the film forming chamber when forming a film by reactive sputtering, the electric power applied to the target, and the distance between the target and the translucent substrate. Further, these film forming conditions are unique to the film forming apparatus, and are appropriately adjusted so that the formed thin film has a desired refractive index n and an extinction coefficient k.

Although the high nitriding layer 22 and the low nitriding layer 21 are formed by sputtering, any sputtering such as DC sputtering, RF sputtering and ion beam sputtering can be applied. When using a target with low conductivity (silicon target, silicon compound target that does not contain metalloid elements or has a low content, etc.), it is preferable to apply RF sputtering or ion beam sputtering, but the film formation rate is taken into consideration. Then, it is more preferable to apply RF sputtering.

The total thickness of the high nitride layer 22 and the low nitride layer 21 is preferably 70% or more, more preferably 80% or more of the thickness of the phase shift film 2. Further, the total thickness of the high nitride layer 22 and the low nitride layer 21 is preferably 95% or less of the thickness of the phase shift film 2 in consideration of providing the uppermost layer described later. .. When there are a plurality of high nitriding layers 22 and / or low nitriding layers 21 in the phase shift film 2, the total thickness of the high nitriding layer 22 and the low nitriding layer 21 is the phase shift. It shall be calculated as the total thickness of the combined thickness of all the high nitride layers 22 in the film 2 and the combined thickness of all the low nitride layers 21 in the phase shift film 2. .. On the other hand, the thickness of the phase shift film 2 is preferably 50 nm or more. The thickness of the phase shift film 2 is preferably 90 nm or less, more preferably 80 nm or less, and even more preferably 70 nm or less.

The method for producing the mask blank 100 uses a silicon target or a target composed of one or more elements selected from semi-metal elements and non-metal elements and silicon, and is reactive in a sputtering gas containing a nitrogen-based gas and a noble gas. Using a high nitride layer forming step of forming the high nitride layer 22 on the translucent substrate 1 by sputtering, and a silicon target or a target composed of one or more elements selected from semi-metal elements and non-metal elements and silicon. A low nitride layer on the translucent substrate 1 by reactive sputtering in a sputtering gas that is a sputtering gas containing a nitrogen-based gas and a noble gas and has a lower mixing ratio of the nitrogen-based gas than in the high nitride layer forming step. It is preferable to have a low nitride layer forming step of forming 21.

Further, in the method for manufacturing the mask blank 100, the sputtering gas used in the high nitride layer forming step has a nitrogen gas larger than the range of the mixing ratio of the nitrogen gas in the transition mode in which the film formation tends to be unstable. The mixing ratio of nitrogen-based gas, which is selected as the so-called poison mode (reaction mode) and the sputtering gas used in the low nitride layer forming step is less than the range of the mixing ratio of nitrogen-based gas in the transition mode, It is preferable to select the so-called metal mode.

As the nitrogen-based gas used in the high nitride layer forming step and the low nitride layer forming step, any gas containing nitrogen can be applied. As described above, since it is preferable to keep the oxygen content of the high nitride layer 22 and the low nitride layer 21 low, it is preferable to apply a nitrogen-based gas containing no oxygen, and a nitrogen gas ( _N2 gas) is applied. Is more preferable. Further, the noble gas used in the high nitride layer forming step and the low nitride layer forming step preferably contains krypton and xenon, and more preferably only krypton and xenon.

The phase shift film 2 preferably includes an uppermost layer 23 made of a material containing silicon and oxygen at a position farthest from the translucent substrate 1. A silicon-based material film that does not actively contain oxygen and contains nitrogen has high light resistance to ArF exposure light, but has lower chemical resistance than a silicon-based material film that actively contains oxygen. There is a tendency. Further, as the uppermost layer 23 on the side opposite to the translucent substrate 1 side of the phase shift film 2, a high nitride layer 22 or a low nitride layer 21 that does not positively contain oxygen and contains nitrogen is arranged. In the case of the mask blank 100, it is possible to prevent the surface layer of the phase shift film 2 from being oxidized by performing mask cleaning on the phase shift mask 200 produced from the mask blank 100 or storing it in the atmosphere. It's difficult to do. In the case of the phase shift film 2 having such a configuration, when the surface layer is oxidized, the optical characteristics of the thin film at the time of film formation are significantly changed. In particular, in the case where the low nitride layer 21 is provided as the uppermost layer 23 of the phase shift film 2, the increase in transmittance due to the oxidation of the low nitride layer 21 becomes large. The phase shift film 2 is provided with the uppermost layer 23 made of a material containing silicon and oxygen on the laminated structure of the high nitriding layer 22 and the low nitriding layer 21, thereby providing the high nitriding layer 22 and the low nitriding layer 2. The surface oxidation of the layer 21 can be suppressed.

On the other hand, the uppermost layer 23 may be formed of a material containing silicon, oxygen, krypton and xenon. From the viewpoint of light resistance to ArF exposure light, the uppermost layer 23 preferably contains a transition metal of less than 1 atomic%, and more preferably does not contain a transition metal. Further, it is desirable that the uppermost layer 23 does not contain any metal element other than the transition metal from the viewpoint of light resistance to ArF exposure light. It is more preferable that the uppermost layer 23 further contains nitrogen. With such a configuration, the overall thickness of the phase shift film 2 can be reduced while suppressing the surface oxidation of the high nitride layer 22 and the low nitride layer 21.

The top layer 23 is formed of a material consisting of silicon, nitrogen, oxygen, krypton and xenon, or a material consisting of one or more elements selected from metalloid and non-metal elements and silicon, nitrogen, oxygen, krypton and xenon. It is preferable to do so. The uppermost layer 23 may contain any metalloid element in addition to silicon. The matters of the metalloid element and the non-metal element are the same as in the case of the high nitride layer 22 and the low nitride layer 21 described above. The uppermost layer 23 preferably has a total content of silicon, nitrogen, oxygen, krypton and xenon of 90 atomic% or more, more preferably 95 atomic% or more, further preferably 98 atomic% or more, and 99. It is even more preferable that the content is atomic% or more.

The thickness of the uppermost layer 23 is preferably 15 nm or less, and more preferably 10 nm or less. On the other hand, the thickness of the uppermost layer 23 is preferably 2 nm or more, more preferably 3 nm or more, and further preferably 4 nm or more. Although the uppermost layer 23 is formed by sputtering, any sputtering such as DC sputtering, RF sputtering and ion beam sputtering can be applied. When using a target with low conductivity (silicon target, silicon compound target that does not contain metalloid elements or has a low content, etc.), it is preferable to apply RF sputtering or ion beam sputtering, but the film formation rate is taken into consideration. Then, it is more preferable to apply RF sputtering.

In the phase shift film 2, the surface shape of the main surface of the translucent substrate 1 before the phase shift film 2 is formed, the phase shift film 2 is formed on the translucent substrate 1, and further annealing treatment (heating) is performed. The absolute value of the flatness change amount calculated from the difference shape between the phase shift film 2 and the surface shape after the processing) is within the film stress of 0.2 μm or less. It is more preferable that the film stress is within 0.15 μm or less.

In the mask blank 100, it is preferable to provide the light-shielding film 3 on the phase shift film 2. Generally, in the phase shift mask 200 (see FIG. 2), the outer peripheral region of the region where the transfer pattern is formed (transfer pattern forming region) is the outer peripheral region when exposure-transferred to the resist film on the semiconductor wafer by using an exposure apparatus. It is required to secure an optical density (OD) of a predetermined value or more so that the resist film is not affected by the exposure light transmitted through the resist film. In the outer peripheral region of the phase shift mask 200, it is required that the optical density is at least larger than 2.0. As described above, the phase shift film 2 has a function of transmitting the exposure light with a predetermined transmittance, and it is difficult to secure the above optical density only with the phase shift film 2. Therefore, it is desirable to laminate the light-shielding film 3 on the phase-shift film 2 at the stage of manufacturing the mask blank 100 in order to secure insufficient optical density. With such a configuration of the mask blank 100, if the light-shielding film 3 in the region where the phase shift effect is used (basically the transfer pattern forming region) is removed in the process of manufacturing the phase shift film 2, the outer peripheral region is formed. It is possible to manufacture a phase shift mask 200 in which the above optical density is ensured. The mask blank 100 preferably has an optical density of 2.5 or more in the laminated structure of the phase shift film 2 and the light-shielding film 3, and more preferably 2.8 or more. Further, in order to make the light-shielding film 3 thin, the optical density in the laminated structure of the phase shift film 2 and the light-shielding film 3 is preferably 4.0 or less.

As the light-shielding film 3, both a single-layer structure and a laminated structure having two or more layers can be applied. Further, each layer of the light-shielding film 3 having a single-layer structure and the light-shielding film 3 having a laminated structure of two or more layers may have substantially the same composition in the thickness direction of the film or the layer, and may be configured in the thickness direction of the layer. The composition may be inclined.

The light-shielding film 3 is made of a material having sufficient etching selectivity with respect to the etching gas used for forming a pattern on the phase-shift film 2 when another film is not interposed between the light-shielding film 3 and the phase-shift film 2. Need to apply. In this case, the light-shielding film 3 is preferably formed of a material containing chromium. Examples of the material containing chromium forming the light-shielding film 3 include a material containing one or more elements selected from oxygen, nitrogen, carbon, boron and fluorine in chromium, in addition to the chromium metal.

Generally, a chromium-based material is etched with a mixed gas of a chlorine-based gas and an oxygen gas, but a chromium metal does not have a very high etching rate with respect to this etching gas. Considering the point of increasing the etching rate of the mixed gas of chlorine-based gas and oxygen gas with respect to the etching gas, the material for forming the light-shielding film 3 is one or more selected from oxygen, nitrogen, carbon, boron and fluorine in chromium. It is preferable to use a material containing an element. Further, the chromium-containing material forming the light-shielding film 3 may contain one or more elements of molybdenum and tin. By containing one or more elements of molybdenum and tin, the etching rate for a mixed gas of a chlorine-based gas and an oxygen gas can be further increased.

On the other hand, in the case of the mask blank 100, in the case where another film is interposed between the light-shielding film 3 and the phase shift film 2, the other film (etching stopper and etching mask film) is made of the above-mentioned chromium-containing material. ) Is formed, and the light-shielding film 3 is preferably formed of a material containing silicon. The material containing chromium is etched by a mixed gas of chlorine-based gas and oxygen gas, and the resist film formed of the organic-based material is easily etched by this mixed gas. Silicon-containing materials are generally etched with a fluorine-based gas or a chlorine-based gas. Since these etching gases basically do not contain oxygen, the amount of film reduction of the resist film formed of the organic material can be reduced as compared with the case of etching with a mixed gas of chlorine-based gas and oxygen gas. Therefore, the film thickness of the resist film can be reduced.

The silicon-containing material forming the light-shielding film 3 may contain a transition metal or may contain a metal element other than the transition metal. This is because when the phase shift mask 200 is manufactured from the mask blank 100, the pattern formed by the light-shielding film 3 is basically a light-shielding band pattern in the outer peripheral region, and the ArF exposure light is higher than that in the transfer pattern formation region. This is because the integrated amount to be irradiated is small and the light-shielding film 3 rarely remains in a fine pattern, and even if the ArF light resistance is low, a substantial problem is unlikely to occur. Further, when the transition metal is contained in the light-shielding film 3, the light-shielding performance is greatly improved as compared with the case where the light-shielding film 3 is not contained, and the thickness of the light-shielding film can be reduced. The transition metals contained in the light-shielding film 3 include molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), and vanadium (V). , Zirconium (Zr), ruthenium (Ru), rhodium (Rh), niobium (Nb), palladium (Pd) and the like, or an alloy of these metals.

On the other hand, as the material containing silicon forming the light-shielding film 3, a material composed of silicon and nitrogen, or a material composed of one or more elements selected from metalloid elements and non-metal elements, silicon and nitrogen may be applied. good.

In the mask blank 100 provided with the light-shielding film 3 laminated on the phase shift film 2, it is formed of a material having etching selectivity for the etching gas used when etching the light-shielding film 3 on the light-shielding film 3. It is more preferable to have a structure in which the hard mask film 4 is further laminated. Since the light-shielding film 3 is essential to have a function of ensuring a predetermined optical density, there is a limit in reducing its thickness. It is sufficient for the hard mask film 4 to have a film thickness sufficient to function as an etching mask until the dry etching for forming a pattern on the light shielding film 3 immediately below the hard mask film 4 is completed, and the hard mask film 4 is basically optical. Not restricted. Therefore, the thickness of the hard mask film 4 can be made significantly thinner than the thickness of the light-shielding film 3. The resist film made of an organic material needs to have a thickness sufficient to function as an etching mask until the dry etching for forming a pattern on the hard mask film 4 is completed. The thickness of the resist film can be significantly reduced.

When the light-shielding film 3 is made of a material containing chromium, the hard mask film 4 is preferably formed of the material containing silicon. Since the hard mask film 4 in this case tends to have low adhesion to the resist film of the organic material, the surface of the hard mask film 4 is subjected to HMDS (Hexamethyldisilazane) treatment to improve the adhesion of the surface. Is preferable. The hard mask film 4 in this case is more preferably formed of SiO ₂ , SiN, SiON, or the like. Further, as the material of the hard mask film 4 when the light-shielding film 3 is made of a material containing chromium, in addition to the above, a material containing tantalum can also be applied. Examples of the material containing tantalum in this case include, in addition to tantalum metal, a material in which tantalum contains one or more elements selected from nitrogen, oxygen, boron and carbon. Examples of the material include Ta, TaN, TaON, TaBN, TaBON, TaCN, TaCON, TaBCN, TaBOCN and the like. On the other hand, when the light-shielding film 3 is made of a material containing silicon, the hard mask film 4 is preferably formed of the above-mentioned material containing chromium.

In the mask blank 100, a material having etching selectivity in both the translucent substrate 1 and the phase shift film 2 between the translucent substrate 1 and the phase shift film 2 (the above-mentioned material containing chromium, for example, Cr, An etching stopper film made of CrN, CrC, CrO, CrON, CrC, etc. may be formed. The etching stopper film may be formed of a material containing aluminum.

In the mask blank 100, it is preferable that the resist film of the organic material is formed with a film thickness of 100 nm or less in contact with the surface of the hard mask film 4. In the case of a fine pattern corresponding to the DRAM hp 32 nm generation, SRAF (Sub-Resolution Assist Feature) having a line width of 40 nm may be provided in the transfer pattern (phase shift pattern) to be formed on the hard mask film 4. However, even in this case, since the cross-sectional aspect ratio of the resist pattern can be as low as 1: 2.5, it is possible to prevent the resist pattern from collapsing or detaching during development, rinsing, etc. of the resist film. can. It is more preferable that the resist film has a film thickness of 80 nm or less.

FIG. 2 shows a schematic cross-sectional view of a process of manufacturing a phase shift mask 200 from a mask blank 100 according to an embodiment of the present invention.

The phase shift mask 200 of the present invention is a phase shift mask 200 provided with a phase shift film 2 (phase shift pattern 2a) having a transfer pattern on a translucent substrate 1, and the phase shift film 2 is highly nitrided. The layer 22 and the low nitrided layer 21 are included, and the high nitrided layer 22 and the low nitrided layer 21 are characterized by containing silicon, nitrogen, krypton and xenone.

The phase shift mask 200 has the same technical features as the mask blank 100. The matters relating to the translucent substrate 1 in the phase shift mask 200, the high nitride layer 22 and the low nitride layer 21 of the phase shift film 2, and the light shielding film 3 are the same as those of the mask blank 100. Therefore, the phase shift mask 200 provided with the phase shift film 2 (phase shift pattern 2a) having a transfer pattern in which the transmittance and the in-plane uniformity of the phase difference are good and the film stress is within the allowable range is provided. be able to.

Further, the method for manufacturing the phase shift mask 200 of the present invention uses the mask blank 100 described above, and is a step of forming a transfer pattern to be formed on the phase shift film 2 on the light shielding film 3 by dry etching in a subsequent step. , A step of forming a transfer pattern on the phase shift film 2 by dry etching using a light-shielding film 3 having a transfer pattern (light-shielding pattern 3a) as a mask, and using a resist film (resist pattern 6b) having a pattern including a light-shielding band as a mask. It is characterized by comprising a step of forming a pattern (light-shielding pattern 3b) including a light-shielding band on the light-shielding film 3 (light-shielding pattern 3a) by dry etching.

Hereinafter, an example of a method for manufacturing the phase shift mask 200 will be described according to the manufacturing process shown in FIG. In this example, a material containing chromium is applied to the light-shielding film 3, and a material containing silicon is applied to the hard mask film 4.

First, a resist film was formed by a spin coating method in contact with the hard mask film 4 of the mask blank 100. Next, a first pattern, which is a transfer pattern (phase shift pattern) to be formed on the phase shift film 2, is exposed and drawn on the resist film, and further predetermined processing such as development processing is performed to obtain a phase shift pattern. The first resist pattern 5a to have was formed (see FIG. 2A). Subsequently, dry etching using a fluorine-based gas was performed using the first resist pattern 5a as a mask to form the first pattern (hard mask pattern 4a) on the hard mask film 4 (see FIG. 2B). ..

Next, after removing the resist pattern 5a, dry etching is performed using a mixed gas of chlorine-based gas and oxygen gas using the hard mask pattern 4a as a mask, and the light-shielding film 3 is subjected to the first pattern (light-shielding pattern 3a). ) (See FIG. 2 (c)). Subsequently, dry etching using a fluorine-based gas was performed using the light-shielding pattern 3a as a mask to form a first pattern (phase shift pattern 2a) on the phase shift film 2, and at the same time, the hard mask pattern 4a was also removed (). See FIG. 2 (d)).

Next, a resist film was formed on the mask blank 100 by a spin coating method. Next, a second pattern, which is a pattern to be formed on the light-shielding film 3 (light-shielding pattern), is exposed and drawn on the resist film, and further subjected to a predetermined process such as a development process to have a light-shielding pattern. A resist pattern 6b was formed. Subsequently, using the second resist pattern 6b as a mask, dry etching was performed using a mixed gas of chlorine-based gas and oxygen gas to form a second pattern (light-shielding pattern 3b) on the light-shielding film 3 (FIG. 2). See (e). Further, the second resist pattern 6b was removed, and a predetermined process such as cleaning was performed to obtain a phase shift mask 200 (see FIG. 2 (f)).

The chlorine-based gas used in the above dry etching is not particularly limited as long as it contains Cl. For example, examples of the chlorine-based gas include Cl ₂ , NaCl ₂ , CHCl ₃ , CH ₂ Cl ₂ , CCl ₄ , BCl ₃ , and the like. Further, the fluorine-based gas used in the above dry etching is not particularly limited as long as F is contained. For example, examples of the fluorine-based gas include CHF ₃ , CF ₄ , C ₂ F ₆ , C ₄ F ₈ , SF ₆ , and the like. In particular, since the fluorine-based gas containing no C has a relatively low etching rate of the glass material with respect to the translucent substrate 1, damage to the translucent substrate 1 can be further reduced.

Further, in the method for manufacturing a semiconductor device of the present invention, a pattern is exposed and transferred to a resist film on a semiconductor substrate by using the phase shift mask 200 manufactured by using the phase shift mask 200 or the mask blank 100. It is characterized by. Since the phase shift mask 200 and the mask blank 100 of the present invention have the above-mentioned effects, the phase shift mask 200 of the present invention is set on the mask stage of the exposure apparatus using the ArF excimer laser as the exposure light, and the semiconductor substrate is used. Even when the phase shift pattern 2a is exposed and transferred to the upper resist film, the pattern can be transferred to the resist film on the semiconductor substrate with an accuracy that sufficiently satisfies the design specifications. Therefore, when the pattern of the resist film is used as a mask and the underlying film is dry-etched to form a circuit pattern, it is possible to form a highly accurate circuit pattern without wiring short circuit or disconnection due to insufficient accuracy.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples.
(Example 1)
[Manufacturing of mask blank]
A translucent substrate 1 made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.25 mm was prepared. The translucent substrate 1 had an end face and a main surface polished to a predetermined surface roughness, and then subjected to a predetermined cleaning treatment and a predetermined drying treatment.

Next, a translucent substrate 1 is installed in a single-wafer RF sputtering device, and a mixed gas (flow ratio) of krypton (Kr), xenone (Xe), and nitrogen ( _N2 ) is used using a silicon (Si) target. Kr: Xe: N ₂ = 4: 3:10, pressure = 0.13Pa) was used as the sputtering gas, the power of the RF power supply was set to 2.8 kW, and reactive sputtering (RF sputtering) was performed on the translucent substrate 1. , A highly nitrided layer 22 (Si: N = 44 atomic%: 56 atomic%) composed of silicon and nitrogen was formed with a thickness of 8.0 nm. Only the high nitride layer 22 is formed on the main surface of another translucent substrate under the same conditions, and the optical of this high nitride layer 22 is formed by using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 2.64, and the extinction coefficient k was 0.36.

Next, a translucent substrate 1 on which the high nitride layer 22 is laminated is installed in a single-wafer RF sputtering apparatus, and a silicon (Si) target is used to use krypton (Kr), xenone (Xe), and nitrogen (Kr), and nitrogen (Xe). The mixed gas of N ₂ ) (flow ratio Kr: He: N ₂ = 5: 4: 4, pressure = 0.11 Pa) is used as the sputtering gas, the power of the RF power supply is 2.8 kW, and reactive sputtering (RF sputtering). A low nitride layer 21 (Si: N = 62 atomic%: 38 atomic%) made of silicon and nitrogen was formed on the high nitride layer 22 with a thickness of 3.5 nm. Only the low nitride layer 21 is formed on the main surface of another translucent substrate under the same conditions, and the optical of this low nitride layer 21 is formed by using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 2.20, and the extinction coefficient k was 1.54.

By the above procedure, a set of laminated structures in which the high nitriding layer 22 and the low nitriding layer 21 are laminated in this order is formed in contact with the surface of the translucent substrate 1. Next, in contact with the surface of the low nitride layer 21 of the translucent substrate 1 on which this one set of laminated structures is formed, four more sets of the laminated structure of the high nitride layer 22 and the low nitride layer 21 are formed by the same procedure. did. Further, under the same film forming conditions as when the high nitride layer 22 was formed, the uppermost layer 23 was formed with a thickness of 8.0 nm in contact with the surface of the low nitride layer 21 farthest from the translucent substrate 1 side. By the above procedure, the phase shift film 2 having a laminated structure of 11 layers in total was formed.

Next, the in-plane distribution of the phase shift amount and the transmittance was measured for the phase shift film 2. Further, a high-nitriding SiN single-layer film having a thickness corresponding to the total thickness of all the high-nitriding layers and the uppermost layer in the phase shift film in Example 1 is formed on another translucent substrate. And, a film formed with a low nitride SiN single layer film having a thickness corresponding to the total thickness of all the low nitride layers in the phase shift film in Example 1 was prepared. Then, the in-plane distributions of the phase shift amount and the transmittance were measured for each of the high nitride SiN single layer film and the low nitride SiN single layer film. The results are shown in FIGS. 3 and 4.
As shown in FIG. 3, the in-plane distribution of the phase shift amount is the target value for the film formed only with the high-nitriding SiN single-layer film and only with the low-nitriding SiN single-layer film in Example 1. The absolute value exceeded 1.0 degree with respect to the standard of. However, for the phase shift film 2 in Example 1 in which the high nitride layer 22 and the low nitride layer 21 are laminated, the in-plane distribution of the phase shift amount is 0.91 degrees with respect to the target value, and the absolute value is 1. It met the criteria of 0 degrees or less.

Further, as shown in FIG. 4, the in-plane distribution of the transmittance is targeted for the film formed only with the high-nitriding SiN single-layer film and only with the low-nitriding SiN single-layer film in Example 1. The absolute value was more than 0.2% with respect to the value. However, for the phase shift film 2 in Example 1 in which the high nitride layer 22 and the low nitride layer 21 are laminated, the in-plane distribution of the transmittance is 0.16% with respect to the target value, and the absolute value is 0.2. It met the criteria of% or less.
As described above, the phase shift film 2 in Example 1 had good transmittance and in-plane uniformity of phase difference. As a result, due to the laminated structure of the high nitride layer 22 and the low nitride layer 21, the in-plane distributions of the portion of the high nitride layer 22 and the portion of the low nitride layer 21 cancel each other out and are improved as a whole. Inferred. Further, it is presumed that the multiple reflection between the high nitride layer 22 and the low nitride layer 21 also worked well.

Further, regarding the phase shift film 2 in the first embodiment, the surface shape of the main surface of the translucent substrate 1 before the phase shift film 2 measured in advance is formed, and after the phase shift film 2 is formed. The difference shape from the surface shape of the phase shift film 2 was derived, and the amount of change in flatness was calculated to be 0.241 μm (calculation area: 142 mm × 142 mm from the center of the substrate. Example 2 below. The same applies to Comparative Examples 1 and 2). Then, the phase shift film 2 was heat-treated in the atmosphere under the conditions of a heating temperature of 500 ° C. and a treatment time of 1 hour. With respect to the phase shift film 2 after the heat treatment, the surface shape of the main surface of the translucent substrate 1 before the phase shift film 2 is formed and the surface shape of the phase shift film 2 after the heat treatment are When the difference shape was derived and the amount of change in flatness was calculated, it was 0.103 μm, which was a good one satisfying the standard within 0.15 μm.
Further, when the transmittance and the phase difference at the light wavelength (about 193 nm) of the ArF excima laser were measured with the phase shift amount measuring device (MPM-193 manufactured by Lasertech) for the phase shift film 2 after the heat treatment, the transmittance was transmitted. The rate was 6.19% and the phase difference was 180.98 degrees.

Next, a translucent substrate 1 on which the phase shift film 2 after heat treatment was formed was installed in a single-wafer DC sputtering apparatus, and an argon (Ar) and carbon dioxide (CO ₂ ) were used using a chromium (Cr) target. ), Nitrogen (N ₂ ) and helium (He) mixed gas (flow ratio Ar: CO ₂ : N ₂ : He = 22: 39: 6: 33, pressure = 0.2 Pa) as the sputtering gas of the DC power supply. The power was 1.9 kW, and the bottom layer of the light-shielding film 3 made of CrOCN was formed with a thickness of 30 nm in contact with the surface of the phase shift film 2 by reactive sputtering (DC sputtering).

Next, using the same chromium (Cr) target, a mixed gas of argon (Ar) and nitrogen (N ₂ ) (flow ratio Ar: N ₂ = 83: 17, pressure = 0.1 Pa) was used as the sputtering gas, and a DC power supply was used. A light-shielding film 3 made of CrN was formed with a thickness of 4 nm on the bottom layer of the light-shielding film 3 by reactive sputtering (DC sputtering).

Next, using the same chromium (Cr) target, a mixed gas of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ) and helium (He) (flow ratio Ar: CO ₂ : N ₂ : He = 21:37:11:31, pressure = 0.2Pa) is used as the sputtering gas, the power of the DC power supply is set to 1.9 kW, and by reactive sputtering (DC sputtering), light-shielding composed of CrOCN is performed on the lower layer of the light-shielding film 3. The upper layer of the film 3 was formed with a thickness of 14 nm. By the above procedure, a light-shielding film 3 made of a chromium-based material having a three-layer structure consisting of a bottom layer made of CrOCN, a lower layer made of CrN, and an upper layer made of CrOCN was formed from the phase shift film 2 side with a total film thickness of 48 nm.

Further, a translucent substrate 1 in which a phase shift film 2 and a light-shielding film 3 are laminated is installed in a single-wafer RF sputtering apparatus, a silicon dioxide (SiO ₂ ) target is used, and an argon (Ar) gas (pressure =). 0.03 Pa) was used as the sputtering gas, the power of the RF power source was 1.5 kW, and a hard mask film 4 made of silicon and oxygen was formed on the light-shielding film 3 by RF sputtering to a thickness of 5 nm. By the above procedure, the mask blank 100 of Example 1 having a structure in which a phase shift film 2 having an 11-layer structure, a light-shielding film 3 and a hard mask film 4 are laminated on a translucent substrate 1 was manufactured.

[Manufacturing of phase shift mask]
Next, using the mask blank 100 of Example 1, the phase shift mask 200 of Example 1 was produced by the following procedure. First, the surface of the hard mask film 4 was subjected to HMDS treatment. Subsequently, a resist film made of a chemically amplified resist for electron beam writing was formed with a film thickness of 80 nm in contact with the surface of the hard mask film 4 by a spin coating method. Next, a first pattern, which is a phase shift pattern to be formed on the phase shift film 2, is drawn with an electron beam on the resist film, subjected to a predetermined development process and a cleaning process, and has the first pattern. The resist pattern 5a of No. 1 was formed (see FIG. 2A).

Next, using the first resist pattern 5a as a mask, dry etching was performed using CF ₄ gas to form the first pattern (hard mask pattern 4a) on the hard mask film 4 (see FIG. 2 (b)). ..

Next, the first resist pattern 5a was removed. Subsequently, using the hard mask pattern 4a as a mask, dry etching is performed using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1), and the first pattern (light shielding) is applied to the light shielding film 3. Pattern 3a) was formed (see FIG. 2C).

Next, using the light-shielding pattern 3a as a mask, dry etching is performed using a fluorine-based gas (mixed gas of SF ₆ and He) to form a first pattern (phase shift pattern 2a) on the phase shift film 2. At the same time, the hard mask pattern 4a was removed (see FIG. 2D).

Next, a resist film made of a chemically amplified resist for electron beam writing was formed on the light-shielding pattern 3a by a spin coating method with a film thickness of 150 nm. Next, a second pattern, which is a pattern to be formed on the light-shielding film 3 (light-shielding pattern), is exposed and drawn on the resist film, and further subjected to a predetermined process such as a development process to have a light-shielding pattern. A resist pattern 6b was formed. Subsequently, using the second resist pattern 6b as a mask, dry etching is performed using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1), and the second pattern is applied to the light shielding film 3. (Shading pattern 3b) was formed (see FIG. 2E). Further, the second resist pattern 6b was removed, and a predetermined process such as cleaning was performed to obtain a phase shift mask 200 (see FIG. 2 (f)).

Next, for the phase shift mask 200 of Example 1, AIMS193 (manufactured by Carl Zeiss) was used to simulate a transfer image when exposure transfer was performed on a resist film on a semiconductor substrate with exposure light having a wavelength of 193 nm. rice field.

When the exposure transfer image of this simulation was verified, the design specifications were fully satisfied. From this result, even when the phase shift mask 200 of Example 1 is exposed and transferred to the resist film on the semiconductor substrate by setting the mask stage of the exposure apparatus, the circuit pattern finally formed on the semiconductor substrate is highly accurate. It can be said that it can be formed with.

(Example 2)
[Manufacturing of mask blank]
The mask blank 100 of Example 2 was manufactured by the same procedure as the mask blank 100 of Example 1 except that the phase shift film 2 was changed. Specifically, the phase shift film 2 of Example 2 was manufactured as follows.
A translucent substrate 1 similar to that in Example 1 is installed in a single-wafer RF sputtering apparatus, and a mixed gas of krypton (Kr), xenone (Xe), and nitrogen ( _N2 ) is used using a silicon (Si) target. (Flow ratio Kr: Xe: N ₂ = 2: 1: 4, pressure = 0.13Pa) is used as the sputtering gas, the power of the RF power supply is set to 2.8 kW, and the translucent substrate is subjected to reactive sputtering (RF sputtering). A highly nitrided layer 22 (Si: N = 44 atomic%: 56 atomic%) composed of silicon and nitrogen was formed on No. 1 with a thickness of 8.0 nm. Only the high nitride layer 22 is formed on the main surface of another translucent substrate under the same conditions, and the optical of this high nitride layer 22 is formed by using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 2.64, and the extinction coefficient k was 0.36.

Next, in a single-wafer RF sputtering apparatus, a translucent substrate 1 on which a high nitride layer 22 is laminated is installed, and a silicon (Si) target is used to use krypton (Kr), xenone (Xe), and nitrogen ( The mixed gas of N ₂ ) (flow ratio Kr: Xe: N ₂ = 7: 3: 4, pressure = 0.11 Pa) is used as the sputtering gas, the power of the RF power supply is 2.8 kW, and reactive sputtering (RF sputtering). A low nitride layer 21 (Si: N = 62 atomic%: 38 atomic%) composed of silicon and nitrogen was formed on the high nitride layer 22 with a thickness of 3.5 nm. Only the low nitride layer 21 is formed on the main surface of another translucent substrate under the same conditions, and the optical of this low nitride layer 21 is formed by using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). When the characteristics were measured, the refractive index n at a wavelength of 193 nm was 2.20, and the extinction coefficient k was 1.54.

By the above procedure, a set of laminated structures in which the high nitriding layer 22 and the low nitriding layer 21 are laminated in this order is formed in contact with the surface of the translucent substrate 1. Next, in contact with the surface of the low nitride layer 21 of the translucent substrate 1 on which this one set of laminated structures is formed, four more sets of the laminated structure of the high nitride layer 22 and the low nitride layer 21 are formed by the same procedure. did. Further, under the same film forming conditions as when the high nitride layer 22 was formed, the uppermost layer 23 was formed with a thickness of 8.0 nm in contact with the surface of the low nitride layer 21 farthest from the translucent substrate 1 side. By the above procedure, the phase shift film 2 in Example 2 having a laminated structure of 11 layers in total was formed.

Next, the in-plane distribution of the phase shift amount and the transmittance was measured for the phase shift film 2. Further, a high-nitriding SiN single-layer film having a thickness corresponding to the total thickness of all the high-nitriding layers and the uppermost layer in the phase shift film in Example 2 is formed on another translucent substrate. And, a film having a low nitride SiN single layer film formed with a thickness corresponding to the total thickness of all the low nitride layers in the phase shift film in Example 2 was prepared. Then, the in-plane distributions of the phase shift amount and the transmittance were measured for each of the high nitride SiN single layer film and the low nitride SiN single layer film. The results are shown in FIGS. 3 and 4.
As shown in FIG. 3, the in-plane distribution of the phase shift amount is the target value for the film formed only with the high-nitriding SiN single-layer film and only with the low-nitriding SiN single-layer film in Example 2. The absolute value was higher than 1.0 degree. However, for the phase shift film 2 in Example 2 in which the high nitride layer 22 and the low nitride layer 21 are laminated, the in-plane distribution of the phase shift amount is 0.92 degrees with respect to the target value, and the absolute value is 1. It met the criteria of 0 degrees or less.

Further, as shown in FIG. 4, the in-plane distribution of the transmittance is targeted for the film formed only with the high-nitriding SiN single-layer film and only with the low-nitriding SiN single-layer film in Example 2. The absolute value was more than 0.2% with respect to the value. However, for the phase shift film 2 in Example 2 in which the high nitride layer 22 and the low nitride layer 21 are laminated, the in-plane distribution of the transmittance is 0.12% with respect to the target value, and the absolute value is 0.2. It met the criteria of% or less.
As described above, the phase shift film 2 in Example 2 had good in-plane uniformity of transmittance and phase difference. It is presumed that this result is improved as a whole by the laminated structure of the high nitride layer 22 and the low nitride layer 21 because the in-plane distributions of the high nitride layer 22 portion and the low nitride layer 21 portion cancel each other out. Will be done. Further, it is presumed that the multiple reflection between the high nitride layer 22 and the low nitride layer 21 also worked well.

Further, regarding the phase shift film 2 in the second embodiment, the surface shape of the main surface of the translucent substrate 1 before the phase shift film 2 measured in advance is formed, and after the phase shift film 2 is formed. When the difference shape from the surface shape of the phase shift film 2 was derived and the amount of change in flatness was calculated, it was 0.324 μm. Then, the phase shift film 2 was heat-treated in the atmosphere under the conditions of a heating temperature of 500 ° C. and a treatment time of 1 hour. With respect to the phase shift film 2 after the heat treatment, the surface shape of the main surface of the translucent substrate 1 before the phase shift film 2 is formed and the surface shape of the phase shift film 2 after the heat treatment are When the difference shape was derived and the amount of change in flatness was calculated, it was 0.128 μm, which was a good one satisfying the standard within 0.15 μm.
Further, when the transmittance and the phase difference at the light wavelength (about 193 nm) of the ArF excima laser were measured with the phase shift amount measuring device (MPM-193 manufactured by Lasertech) for the phase shift film 2 after the heat treatment, the transmittance was transmitted. The rate was 6.19% and the phase difference was 181.82 degrees.

Further, the phase shift film 2 in Example 2 was formed on another translucent substrate 1 and measured by the HR-RBS analysis method (high resolution Rutherford backscatter analysis method). FIG. 5 is a graph showing the observation results of HR-RBS in Example 2 of the present invention. More specifically, FIG. 5 is a graph showing the observation data and the result of performing simulation fitting on the observation data. As shown in FIG. 5, krypton and xenon were detected in the phase shift film 2 in Example 2 in addition to silicon and nitrogen. Moreover, when the depth profile of the phase shift film 2 in Example 2 was examined, the presence of krypton and xenon was confirmed in both the high nitride layer 22 and the low nitride layer 21.
Further, according to this result, krypton and xenon are also present in the phase shift film 2 of Example 1 in which the flow rate of xenon gas is larger than that of Example 2 and the flow rate of krypton gas is larger than the flow rate of the xenon gas. Is presumed to be.

Then, by the same procedure as in Example 1, the mask blank 100 of Example 2 having a structure in which the phase shift film 2, the light shielding film 3 and the hard mask film 4 are laminated on the translucent substrate 1 was manufactured.

[Manufacturing of phase shift mask]
Next, using the mask blank 100 of Example 2, the phase shift mask 200 of Example 2 was manufactured by the same procedure as that of Example 1.

Next, when the phase shift pattern 2a of the phase shift mask 200 of Example 2 is exposed and transferred to a resist film on a semiconductor substrate with exposure light having a wavelength of 193 nm using AIMS193 (manufactured by Carl Zeiss). A transfer image was simulated.

When the exposure transfer image of this simulation was verified, the design specifications were fully satisfied. From this result, even when the phase shift mask 200 of Example 2 is exposed and transferred to the resist film on the semiconductor substrate by setting the mask stage of the exposure apparatus, the circuit pattern finally formed on the semiconductor substrate is highly accurate. It can be said that it can be formed with.

(Comparative Example 1)
[Manufacturing of mask blank]
The mask blank of Comparative Example 1 was manufactured in the same procedure as the mask blank 100 of Example 1 except that the phase shift film was changed. Specifically, the phase shift film of Comparative Example 1 was manufactured as follows.
A translucent substrate similar to that in Example 1 is installed in a single-wafer RF sputtering apparatus, a silicon (Si) target is used, and a mixed gas (flow rate) of krypton (Kr), nitrogen ( _N2 ) and helium (He) is used. Ratio Kr: N ₂ : He = 3: 4: 20, pressure = 0.29 Pa) was used as the sputtering gas, the power of the RF power supply was set to 2.8 kW, and reactive sputtering (RF sputtering) was performed on the translucent substrate. , A highly nitrided layer (Si: N = 44 atomic%: 56 atomic%) composed of silicon and nitrogen was formed with a thickness of 8.0 nm. Only the high-nitriding layer is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of this high-nitriding layer are measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). As a result of measurement, the refractive index n at a wavelength of 193 nm was 2.64, and the extinction coefficient k was 0.36.

Next, a translucent substrate on which a high nitride layer was laminated was installed in a single-wafer RF sputtering apparatus, and a silicon (Si) target was used to use krypton (Kr), nitrogen (N ₂ ) and helium (He). Mixing gas (flow ratio Kr: N ₂ : He = 5: 2: 25, pressure = 0.27Pa) is used as the sputtering gas, the power of the RF power supply is set to 2.8 kW, and high by reactive sputtering (RF sputtering). A low nitrided layer (Si: N = 62 atomic%: 38 atomic%) composed of silicon and nitrogen was formed on the nitrided layer to a thickness of 3.5 nm. Only the low nitride layer is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of this low nitride layer are measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). As a result of measurement, the refractive index n at a wavelength of 193 nm was 2.20, and the extinction coefficient k was 1.54.

By the above procedure, a set of laminated structures in which the high nitriding layer and the low nitriding layer were laminated in this order was formed in contact with the surface of the translucent substrate. Next, in contact with the surface of the low nitride layer of the translucent substrate on which this one set of laminated structures was formed, four more sets of laminated structures of the high nitride layer and the low nitride layer were formed by the same procedure. Further, under the same film forming conditions as when the high nitride layer was formed, the uppermost layer was formed with a thickness of 8.0 nm in contact with the surface of the low nitride layer farthest from the translucent substrate side. By the above procedure, the phase shift film in Comparative Example 1 having a laminated structure of 11 layers in total was formed.

Next, the in-plane distribution of the phase shift amount and the transmittance was measured for the phase shift film in Comparative Example 1, respectively. Further, a high-nitriding SiN single-layer film having a thickness corresponding to the total thickness of all the high-nitriding layers and the uppermost layer in the phase shift film in Comparative Example 1 is formed on another translucent substrate. And, a film having a low nitride SiN single layer film formed with a thickness corresponding to the total thickness of all the low nitride layers in the phase shift film in Comparative Example 1 was prepared. Then, the in-plane distributions of the phase shift amount and the transmittance were measured for each of the high nitride SiN single layer film and the low nitride SiN single layer film. The results are shown in FIGS. 3 and 4.
As shown in FIG. 3, the in-plane distribution of the phase shift amount is the target value for both the high-nitriding SiN single-layer film and the low-nitriding SiN single-layer film formed in Comparative Example 1. The absolute value was higher than 1.0 degree. The in-plane distribution of the phase shift amount of the phase shift film 2 in Comparative Example 1 in which the high nitride layer and the low nitride layer are laminated is 2.59 degrees with respect to the target value, and the absolute value is 1.0 degree. It did not meet the following criteria.

Further, as shown in FIG. 4, the in-plane distribution of the transmittance is targeted for the film formed only with the high-nitriding SiN single-layer film and only with the low-nitriding SiN single-layer film in Comparative Example 1. The absolute value was more than 0.2% with respect to the value. The in-plane distribution of the transmittance of the phase shift film in Comparative Example 1 in which the high nitride layer and the low nitride layer are laminated is 0.21% with respect to the target value, and the absolute value is 0.2% or less. It did not meet the criteria.
As described above, the phase shift film 2 in Comparative Example 1 did not satisfy the criteria in terms of both the transmittance and the in-plane uniformity of the phase difference.

Further, regarding the phase shift film in Comparative Example 1, the surface shape of the main surface of the translucent substrate 1 before the phase shift film was formed and the phase shift after the phase shift film was formed, which were measured in advance. When the difference shape from the surface shape of the film was derived and the amount of change in flatness was calculated, it was 0.169 μm. Then, this phase shift film was heat-treated in the atmosphere under the conditions of a heating temperature of 500 ° C. and a treatment time of 1 hour. For the phase shift film after the heat treatment, the difference shape between the surface shape of the main surface of the translucent substrate 1 before the phase shift film is formed and the surface shape of the phase shift film after the heat treatment is obtained. When it was derived and the amount of change in flatness was calculated, it was −0.181 μm, which satisfied the standard within 0.2 μm but not within 0.15 μm.
Further, for the phase shift film of Comparative Example 1 after the heat treatment, the transmittance and the phase difference at the light wavelength (about 193 nm) of the ArF excima laser were measured with a phase shift amount measuring device (MPM-193 manufactured by Lasertech). However, the transmittance was 6.35% and the phase difference was 179.54 degrees.

Then, by the same procedure as in Example 1, a mask blank of Comparative Example 1 having a structure in which a phase shift film, a light-shielding film, and a hard mask film were laminated on a translucent substrate was manufactured.

[Manufacturing of phase shift mask]
Next, using the mask blank of Comparative Example 1, a phase shift mask of Comparative Example 1 was manufactured by the same procedure as in Example 1.

Next, for the phase shift pattern of the phase shift mask of Comparative Example 1, a transfer image when exposure transfer was performed on a resist film on a semiconductor substrate with exposure light having a wavelength of 193 nm using AIMS193 (manufactured by Carl Zeiss). Was simulated.

When the exposure transfer image of this simulation was verified, it did not fully meet the design specifications and was at a level where transfer defects occurred. From this result, when the phase shift mask of Comparative Example 1 is exposed and transferred to the resist film on the semiconductor substrate by setting the mask stage of the exposure apparatus, the circuit pattern finally formed on the semiconductor substrate is a circuit pattern. It is expected that disconnection and short circuit will occur.

(Comparative Example 2)
[Manufacturing of mask blank]
The mask blank of Comparative Example 2 was manufactured in the same procedure as the mask blank 100 of Example 1 except that the phase shift film was changed. Specifically, the phase shift film of Comparative Example 2 was manufactured as follows.
A translucent substrate similar to that in Example 1 was installed in a single-wafer RF sputtering apparatus, a silicon (Si) target was used, and a mixed gas of krypton (Kr) and nitrogen (N ₂ ) (flow ratio Kr: N ₂ ). = 3: 4, pressure = 0.13Pa) is used as the sputtering gas, the power of the RF power supply is set to 2.8 kW, and high nitriding composed of silicon and nitrogen is performed on the translucent substrate 1 by reactive sputtering (RF sputtering). A layer (Si: N = 44 atomic%: 56 atomic%) was formed with a thickness of 8.0 nm. Only the high-nitriding layer is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of this high-nitriding layer are measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). As a result of measurement, the refractive index n at a wavelength of 193 nm was 2.64, and the extinction coefficient k was 0.36.

Next, a translucent substrate on which a high nitride layer was laminated was installed in a single-wafer RF sputtering apparatus, and a mixed gas (flow rate) of krypton (Kr) and nitrogen (N ₂ ) was used using a silicon (Si) target. The ratio Kr: N ₂ = 20: 7, pressure = 0.11 Pa) was used as the sputtering gas, the power of the RF power supply was set to 2.8 kW, and reactive sputtering (RF sputtering) was performed on the high nitride layer from silicon and nitrogen. A low nitride layer (Si: N = 62 atomic%: 38 atomic%) was formed with a thickness of 3.5 nm. Only the low nitride layer is formed on the main surface of another translucent substrate under the same conditions, and the optical characteristics of this low nitride layer are measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). As a result of measurement, the refractive index n at a wavelength of 193 nm was 2.20, and the extinction coefficient k was 1.54.

By the above procedure, a set of laminated structures in which the high nitriding layer and the low nitriding layer were laminated in this order was formed in contact with the surface of the translucent substrate. Next, in contact with the surface of the low nitride layer of the translucent substrate on which this one set of laminated structures was formed, four more sets of laminated structures of the high nitride layer and the low nitride layer were formed by the same procedure. Further, under the same film forming conditions as when the high nitride layer was formed, the uppermost layer was formed with a thickness of 8.0 nm in contact with the surface of the low nitride layer farthest from the translucent substrate side. By the above procedure, the phase shift film of Comparative Example 2 having a laminated structure of 11 layers in total was formed.

Next, the in-plane distribution of the phase shift amount and the transmittance was measured for the phase shift film of Comparative Example 2, respectively. Further, a high-nitriding SiN single-layer film having a thickness corresponding to the total thickness of all the high-nitriding layers and the uppermost layer in the phase shift film in Comparative Example 2 is formed on another translucent substrate. And, a film having a low nitride SiN single layer film formed with a thickness corresponding to the total thickness of all the low nitride layers in the phase shift film in Comparative Example 2 was prepared. Then, the in-plane distributions of the phase shift amount and the transmittance were measured for each of the high nitride SiN single layer film and the low nitride SiN single layer film. The results are shown in FIGS. 3 and 4.
As shown in FIG. 3, the in-plane distribution of the phase shift amount is the target value for both the high-nitriding SiN single-layer film and the low-nitriding SiN single-layer film formed in Comparative Example 2. The absolute value was higher than the standard of 1.0 degree. However, for the phase shift film in Comparative Example 2 in which the high nitride layer and the low nitride layer are laminated, the in-plane distribution of the phase shift amount is 0.64 degrees with respect to the target value, and the absolute value is 1.0 degree or less. It met the criteria of.

Further, as shown in FIG. 4, the in-plane distribution of the transmittance is targeted for both the high-nitrided SiN single-layer film and the low-nitrided SiN single-layer film formed in Comparative Example 2. The absolute value of the value exceeded the standard of 0.2%. However, for the phase shift film in Comparative Example 2 in which the high nitride layer and the low nitride layer are laminated, the in-plane distribution of the transmittance is 0.18% with respect to the target value, and the absolute value is 0.2% or less. It met the criteria.

However, regarding the phase shift film in Comparative Example 2, the surface shape of the main surface of the translucent substrate 1 before the phase shift film was formed and the phase shift after the phase shift film was formed, which were measured in advance. When the difference shape from the surface shape of the film was derived and the amount of change in flatness was calculated, it was 0.490 μm. Then, this phase shift film was heat-treated in the atmosphere under the conditions of a heating temperature of 500 ° C. and a treatment time of 1 hour. For the phase shift film after the heat treatment, the difference shape between the surface shape of the main surface of the translucent substrate 1 before the phase shift film is formed and the surface shape of the phase shift film after the heat treatment is obtained. When it was derived and the amount of change in flatness was calculated, it was 0.246 μm, which did not satisfy the standard of 0.2 μm or less as well as the standard of 0.15 μm or less.
Further, for the phase shift film of Comparative Example 2 after the heat treatment, the transmittance and the phase difference at the light wavelength (about 193 nm) of the ArF excima laser were measured with a phase shift amount measuring device (MPM-193 manufactured by Lasertech). However, the transmittance was 6.25% and the phase difference was 180.77 degrees.

Further, a phase shift film in Comparative Example 2 was formed on another translucent substrate, and the measurement was performed by the HR-RBS analysis method (high resolution Rutherford backscatter analysis method). FIG. 6 is a graph showing the observation results of HR-RBS in Comparative Example 2 of the present invention. More specifically, FIG. 6 is a graph showing the observation data and the result of performing simulation fitting on the observation data. As shown in FIG. 6, in the phase shift film in Comparative Example 2, it was confirmed that krypton was detected in addition to silicon and nitrogen, but xenon was not detected.

Then, by the same procedure as in Example 1, a mask blank of Comparative Example 2 having a structure in which a phase shift film, a light-shielding film, and a hard mask film were laminated on a translucent substrate was manufactured.

[Manufacturing of phase shift mask]
Next, using the mask blank of Comparative Example 2, a phase shift mask of Comparative Example 2 was manufactured by the same procedure as in Example 1.

Next, for the phase shift pattern of the phase shift mask of Comparative Example 2, a transfer image when exposure transfer was performed on a resist film on a semiconductor substrate with exposure light having a wavelength of 193 nm using AIMS193 (manufactured by Carl Zeiss). Was simulated.

When the exposure transfer image of this simulation was verified, the position shift of the pattern, which seems to be caused by the film stress of the phase shift film, did not fully meet the design specifications, and the transfer defect occurred at the level. It was a thing. From this result, when the phase shift mask of Comparative Example 2 is exposed and transferred to the resist film on the semiconductor substrate by setting the mask stage of the exposure apparatus, the circuit pattern finally formed on the semiconductor substrate is a circuit pattern. It is expected that disconnection and short circuit will occur.

1 Translucent substrate 2 Phase shift film 2a Phase shift pattern 21 Low nitride layer 22 High nitride layer 23 Top layer 3 Light-shielding film 3a, 3b Light-shielding pattern 4 Hard mask film 4a Hard mask pattern 5a First resist pattern 6b Second Resist pattern 100 mask blank 200 phase shift mask

Claims (17)

A mask blank with a phase shift film on a translucent substrate.
The phase shift film includes a high nitriding layer and a low nitriding layer.
The mask blank, wherein the high nitriding layer and the low nitriding layer contain silicon, nitrogen, krypton and xenon. The mask blank according to claim 1, wherein the highly nitrided layer has a nitrogen content of 50 atomic% or more. The mask blank according to claim 1 or 2, wherein the low nitride layer has a nitrogen content of less than 50 atomic%. The mask blank according to claim 1, wherein the high nitride layer and the low nitride layer have a total content of silicon, nitrogen, krypton, and xenon of 90 atomic% or more. The invention according to any one of claims 1 to 4, wherein the total thickness of the high nitride layer and the low nitride layer is 70% or more of the thickness of the phase shift film. Mask blank. The mask blank according to any one of claims 1 to 5, wherein the phase shift film includes a structure in which two or more high-nitriding layers and two or more low-nitriding layers are alternately laminated. The phase shift film has a function of transmitting the exposure light of the ArF excimer laser with a transmittance of 2% or more, and is in the air for the same distance as the thickness of the phase shift film with respect to the exposure light transmitted through the phase shift film. The mask blank according to any one of claims 1 to 6, further comprising a function of causing a phase difference of 150 degrees or more and 210 degrees or less with the exposed light that has passed through. The mask blank according to any one of claims 1 to 7, wherein a light-shielding film is provided on the phase shift film. A phase shift mask provided with a phase shift film in which a transfer pattern is formed on a translucent substrate.
The phase shift film includes a high nitriding layer and a low nitriding layer.
The high nitriding layer and the low nitriding layer contain silicon, nitrogen, krypton and xenon.
A phase shift mask characterized by that. The phase shift mask according to claim 9, wherein the highly nitrided layer has a nitrogen content of 50 atomic% or more. The phase shift mask according to claim 9 or 10, wherein the low nitride layer has a nitrogen content of less than 50 atomic%. The phase shift mask according to any one of claims 9 to 11, wherein the high nitriding layer and the low nitriding layer have a total content of silicon, nitrogen, krypton and xenon of 90 atomic% or more. The method according to any one of claims 9 to 12, wherein the total thickness of the high nitride layer and the low nitride layer is 70% or more of the thickness of the phase shift film. Phase shift mask. The phase shift mask according to any one of claims 9 to 13, wherein the phase shift film includes a structure in which two or more high nitride layers and two or more low nitride layers are alternately laminated. The phase shift film has a function of transmitting the exposure light of the ArF excimer laser with a transmission rate of 2% or more, and the exposure light transmitted through the phase shift film is in the air by the same distance as the thickness of the phase shift film. The phase shift mask according to any one of claims 9 to 14, further comprising a function of causing a phase difference of 150 degrees or more and 210 degrees or less with the exposed light that has passed through. The phase shift mask according to any one of claims 9 to 15, wherein a light-shielding film having a light-shielding pattern formed on the phase-shift film is provided. A method for manufacturing a semiconductor device, comprising a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate by using the phase shift mask according to any one of claims 9 to 16.

Images