JP5666218B2 - Mask blank, transfer mask, and transfer mask set - Google Patents

Description

  The present invention relates to a mask blank, a transfer mask, a transfer mask set, and the like used in manufacturing a semiconductor device and the like.

When transferring the transfer pattern formed on the transfer mask to the resist film on the wafer by reduction projection exposure, it is usually necessary to transfer as many transfer patterns as possible onto the resist film on the wafer. Therefore, the transfer patterns are continuously exposed with almost no gap between adjacent transfer patterns. In the exposure apparatus, a shutter (light-shielding member) is provided in the illumination optical system of the exposure apparatus so that the exposure light is exposed only to the area where the transfer pattern on the transfer mask chucked on the mask stage is formed. Yes. However, due to the problems of shutter position accuracy and light diffraction, it is technically difficult to accurately irradiate the exposure light to only the transfer pattern area of the transfer mask, and the exposure light is applied to the light shielding film around the transfer pattern area. Will leak and irradiate. Since the exposure of the transfer pattern onto the resist film on the wafer by the exposure apparatus is performed continuously with almost no gap, exposure light leaked to the light shielding film on the outer periphery of the transfer pattern region (this is called leakage light) is irradiated. Thus, the slightly transmitted exposure light is exposed by overlapping with the adjacent transfer pattern. For this reason, in the resist film on the wafer, a portion (overlapping exposure portion) that is exposed by being overlapped up to four times by exposure light slightly transmitted through the light shielding film is generated. If the resist is exposed to light that causes an influence on the transfer pattern in these four exposures, the transfer pattern cannot be normally transferred.
In the case of a light-shielding film used in a binary transfer mask that forms a transfer pattern only in black and white where the exposure light is transmitted and where the exposure light is shielded, the light-shielding film is slightly transmitted due to this leakage light. Therefore, a light shielding performance is required so that the exposure light to be exposed is not exposed even if the resist film on the wafer is exposed four times. As the light shielding performance, the optical density (OD) is preferably 3.0 or more (transmittance of about 0.1% or less), and 2.8 or more (transmittance of about 0.16% or less) is required. .
On the other hand, in an exposure technique using an ArF excimer laser (wavelength 193 nm) as exposure light, miniaturization of a transfer pattern has progressed, and it is required to correspond to a pattern line width smaller than the wavelength of exposure light. Super-resolution techniques such as phase shift method, and ultra-high NA techniques (immersion exposure, etc.) with NA = 1 or higher have been developed, but pattern pitches that are difficult to cope with with these techniques are beginning to be required.
As a means for solving this problem, a double patterning / double exposure (DP / DE) technique has been developed. In any exposure technique, a fine transfer pattern is divided into two relatively sparse patterns to produce two transfer masks, and two transfer masks (transfer mask sets) are used on the wafer. The resist film (transfer object) is transferred and exposed.

JP 2008-294352 A

In the double exposure (DE) technique, a resist pattern on a wafer is exposed to a transfer pattern using a first transfer mask, and then a second transfer mask is applied to the same resist film. The transfer pattern is exposed. For this reason, unlike the conventional case, a portion of the resist film on the wafer that is exposed eight times by exposure light slightly transmitted through the light-shielding film is generated due to leakage light. For this reason, even with a transfer mask using a light shielding film having an optical density (OD) of 2.8, which has been considered to be sufficient in the past, the resist film on the wafer is exposed so as to affect the transfer pattern. As a result, there is a problem that normal pattern transfer cannot be performed.
As a method for solving this problem, it is conceivable to simply increase the optical density by increasing the thickness of the light shielding film. However, when the thickness of the light shielding film is increased, it is necessary to increase the thickness of the resist pattern (resist film) that serves as a mask when performing etching for forming a transfer pattern on the light shielding film. When a fine pattern is formed on a thick resist film, problems such as collapse or missing of the resist pattern are likely to occur.
On the other hand, as the thickness of the light shielding film increases, the bias due to the electromagnetic field (EMF) effect increases. The EMF bias greatly affects the CD accuracy of the transfer pattern line width of the resist on the wafer. For this reason, the electromagnetic field effect is simulated, and the transfer pattern formed on the transfer mask for reducing the influence of the EMF bias is corrected. However, there is a problem that a complicated simulation is required as the film thickness increases, and a great load is applied.
From the above, it is problematic to increase the thickness of the light-shielding film in at least the region where the transfer pattern is formed on the transfer mask.
The present invention has been made under the above background, and an object of the present invention is to provide a binary mask blank suitable for the double exposure technique.

The present invention has the following configuration.
(Configuration 1)
A mask blank used for producing a binary transfer mask to which ArF exposure light is applied,
A light-shielding film for forming a transfer pattern and an auxiliary light-shielding film for forming a light-shielding band in a laminated structure with the light-shielding film are sequentially provided on the light-transmitting substrate from the substrate side,
The optical density of the light shielding film is 2.5 or more and 3.1 or less, and the optical density of the auxiliary light shielding film is 0.5 or more.
A mask blank characterized by that.
(Configuration 2)
2. The mask blank according to Configuration 1, which is used for producing a transfer mask to which a double exposure technique is applied.
(Configuration 3)
The mask blank according to Configuration 1 or 2, wherein the light shielding film has a laminated structure of a light shielding layer and a surface antireflection layer.
(Configuration 4)
4. The mask blank according to any one of configurations 1 to 3, wherein the auxiliary light shielding film has etching selectivity with respect to an etching medium used when the light shielding film is etched.
(Configuration 5)
5. The mask according to claim 1, wherein the light shielding film is a film mainly composed of a transition metal and silicon, and the auxiliary light shielding film is a film mainly composed of chromium. blank.
(Configuration 6)
5. The mask blank according to claim 1, wherein the light shielding film is a film containing chromium as a main component, and the auxiliary light shielding film is a film containing transition metal and silicon as main components. .
(Configuration 7)
5. The mask blank according to claim 1, wherein the light shielding film is a film containing tantalum as a main component, and the auxiliary light shielding film is a film containing chromium as a main component.
(Configuration 8)
Any one of the constitutions 1 to 3, wherein an etching mask film having an etching selectivity with respect to an etching medium used when etching these films is provided between the light shielding film and the auxiliary light shielding film. The mask blank described.
(Configuration 9)
9. The mask blank according to Configuration 8, wherein both the light shielding film and the auxiliary light shielding film are films mainly composed of a transition metal and silicon, and further include an etching mask film mainly composed of chromium.
(Configuration 10)
9. The mask blank according to Configuration 8, wherein both the light shielding film and the auxiliary light shielding film are films containing chromium as a main component and further having an etching mask film containing transition metal and silicon as main components.
(Configuration 11)
A transfer mask produced using the mask blank according to any one of Configurations 1 to 10.
(Configuration 12)
A binary transfer mask to which ArF exposure light is applied,
In the transfer pattern area on the translucent substrate, has a transfer pattern formed of a light shielding film,
A light-shielding band formed by a laminated structure of a light-shielding film and an auxiliary light-shielding film from the substrate side in a region outside the transfer pattern region,
The optical density of the light shielding film is 2.5 or more and 3.1 or less, and the optical density of the auxiliary light shielding film is 0.5 or more.
A transfer mask characterized by that.
(Configuration 13)
13. The transfer mask according to Configuration 12, wherein a double exposure technique is applied.
(Configuration 14)
14. The transfer mask according to Configuration 12 or 13, wherein the light shielding film has a laminated structure of a light shielding layer and a surface antireflection layer.
(Configuration 15)
The transfer mask according to any one of Structures 12 to 14, wherein the auxiliary light shielding film has an etching selectivity with respect to an etching medium, which is used when the light shielding film is etched.
(Configuration 16)
16. The transfer mask according to any one of Structures 12 to 15, wherein the light shielding film is a film containing transition metal and silicon as main components, and the auxiliary light shielding film is a film containing chromium as main components.
(Configuration 17)
The transfer mask according to any one of Items 12 to 15, wherein the light shielding film is a film containing chromium as a main component, and the auxiliary light shielding film is a film containing transition metal and silicon as main components.
(Configuration 18)
16. The transfer mask according to any one of Structures 12 to 15, wherein the light shielding film is a film containing tantalum as a main component, and the auxiliary light shielding film is a film containing chromium as a main component.
(Configuration 19)
The transfer according to any one of Items 12 to 14, wherein an etching mask film having an etching selectivity with respect to an etching medium used when etching these films is provided between the light shielding film and the auxiliary light shielding film. Mask.
(Configuration 20)
20. The transfer mask according to Configuration 19, wherein both the light shielding film and the auxiliary light shielding film are films mainly composed of a transition metal and silicon, and further include an etching mask film mainly composed of chromium.
(Configuration 21)
20. The transfer mask according to Configuration 19, wherein both the light-shielding film and the auxiliary light-shielding film are films mainly composed of chromium, and further include an etching mask film composed mainly of transition metals and silicon.
(Configuration 22)
A transfer mask set comprising two transfer masks according to any one of Configurations 13 to 21, wherein
The two transfer masks are used for transfer exposure by a double exposure technique, and each transfer pattern formed on the two transfer masks is one transfer pattern for transferring and exposing a transfer object. A mask set for transfer, characterized in that is divided into two sparse transfer patterns.

According to the present invention, it is for forming a transfer pattern, and the light shielding performance (OD2) that can suppress the exposure of the resist film on the wafer so as not to affect the transfer pattern in the double exposure by the double exposure technique. .5 or more) and a light-shielding band, and in combination with the light-shielding film, the exposure of the resist film on the wafer does not affect the transfer pattern even when exposed eight times. A mask blank having an auxiliary light-shielding film (OD 0.5 or more) exhibiting a light-shielding performance that can be suppressed to a low level, a transfer mask set for double exposure is produced from this mask blank, and a resist film on the wafer Even if the transfer pattern is transferred to the resist film, it is possible to prevent the resist film from being exposed to the portion exposed eight times.
In addition, it has a two-layer structure of a light shielding film for forming a transfer pattern and an auxiliary light shielding film for forming a light shielding band, and the light shielding film for forming the transfer pattern is exposed twice to affect the sensitivity of the resist film. By making the light-shielding performance that can be suppressed so as not to occur, the thickness of the light-shielding film in the transfer pattern region can be reduced compared to the case where the film thickness of the light-shielding film is simply increased to correspond to the double exposure technique. Thereby, the accuracy of the light shielding film pattern in the transfer pattern region can be improved.
Further, since it is not necessary to increase the thickness of the light-shielding film in the transfer pattern region, it is not necessary to increase the thickness of the resist, and the problem of resist pattern collapse and loss is less likely to occur.
In addition, since it is not necessary to increase the thickness of the light shielding film in the transfer pattern region, the bias due to the electromagnetic field (EMF) effect increases as the thickness of the light shielding film increases, and the complexity increases as the film thickness increases. A problem that a large simulation is required and a great load is applied can be avoided.
According to the present invention, the mask blank used as a transfer mask used in the double exposure technique is suppressed to a photosensitivity that does not affect the transfer pattern even if the resist film on the wafer in the overexposed portion is exposed eight times. It is possible to realize that an optical density that can be obtained is obtained at least in the area around the transfer pattern region of the light shielding film, and at the same time, it is possible to cope with without increasing the thickness of the light shielding film in the transfer pattern region.

FIG. 1 is a schematic cross section showing a first embodiment of a mask blank of the present invention. FIG. 2 is a schematic cross section showing a second embodiment of the mask blank of the present invention. FIG. 3 is a schematic cross section showing a third embodiment of the mask blank of the present invention. FIG. 4 is a diagram showing the relationship between the Mo / Mo + Si ratio and nitrogen content in the thin film and the optical density per unit film thickness. FIG. 5 is a schematic cross-sectional view for explaining the manufacturing process of the transfer mask according to the first embodiment of the invention. FIG. 6 is a schematic cross-sectional view for explaining the manufacturing process of the transfer mask according to the third embodiment of the invention.

Hereinafter, the present invention will be described in detail.
The mask blank of the present invention is
A mask blank used for producing a binary transfer mask to which ArF exposure light is applied,
A light-shielding film for forming a transfer pattern and an auxiliary light-shielding film for forming a light-shielding band in a laminated structure with the light-shielding film are sequentially provided on the light-transmitting substrate from the substrate side,
The optical density of the light shielding film is 2.5 or more and 3.1 or less, and the optical density of the auxiliary light shielding film is 0.5 or more.

In the present invention, the light-shielding film 10 is a lithography to which ArF exposure light is applied, and is a film having both a film thickness and an optical density suitable for generations after DRAM half pitch (hp) 32 nm and double exposure technology.
A double exposure technique is used to transfer a transfer pattern with two transfer masks to a resist film on a wafer formed of a material having characteristics similar to those used in the conventional single exposure technique. In this case, it is necessary to consider the following.

  When the transfer pattern is continuously transferred to the resist film on the wafer with almost no gap by the conventional single exposure technique using one transfer mask, (1) the transfer pattern is transferred to the resist film. In the transfer exposure, exposure is performed once by exposure light that slightly transmits the black portion of the transfer pattern of the transfer mask (the light shielding portion where the light shielding film is left) (hereinafter referred to as “transfer pattern exposure”), and ( 2) In transfer exposure when transferring a transfer pattern to an adjacent region of a resist film, exposure is performed up to three times by exposure light (leakage light) slightly transmitted through a light shielding band of a transfer mask (hereinafter referred to as “leakage light”). An area called “exposure” is created. In conventional binary transfer masks, the black part and the light-shielding zone of the transfer pattern are formed of a light-shielding film with the same optical density, so the most overlapping part is equivalent to four exposures of leaked light (or transfer pattern exposure) Will be exposed. Conventionally, the material and film thickness of the light-shielding film are selected so as to achieve an optical density that does not affect the transfer pattern exposed and transferred even when the resist film is exposed up to four times by leak light exposure.

  On the other hand, when the transfer pattern is continuously transferred to the resist film on the wafer with almost no gap by the double exposure technique using two transfer masks, the light leakage exposure is performed twice on the resist film by the transfer pattern exposure. Is exposed up to 6 times. In the case where the black portion and the light shielding band portion of the transfer pattern are formed of the same light shielding film as in the conventional case, even if the resist film is exposed up to 8 times by leak light exposure, there is no effect on the transfer pattern exposed and transferred. It is necessary to select the material and film thickness of the light-shielding film so as to obtain such an optical density. For this reason, the transfer mask applied with the double exposure technique has a problem that it is necessary to make the thickness of the light shielding film thicker than the transfer mask applied with the single exposure technique.

  In the present invention, the optical density required for forming the black portion of the transfer pattern for the light-shielding film, and the optical density insufficient for the light-shielding film alone to form the light-shielding band of the transfer mask applied with the double exposure technology, The auxiliary light shielding film is laminated to make up for the supplement. As a result, while the film thickness of the light-shielding film at the portion where the transfer pattern is to be formed is equivalent to the conventional one, in addition to the transfer pattern exposure twice, the resist film is exposed and transferred even if leak light exposure is exposed up to six times. A light-shielding band having an optical density that is not affected by the pattern can be formed.

When exposure transfer of a transfer pattern is performed on a resist film on a wafer, an optical density of 2.5 or more is required for a light shielding film for forming a black portion of the transfer pattern.
In the case of a conventional transfer mask for single exposure, in order to prevent the transfer pattern from being affected even if exposure corresponding to four exposures of leaked light is applied to the resist film on the wafer, the shading band must be a minimum. However, an optical density of 2.5 needs to be ensured. That is, the light shielding film needs to have an optical density of 2.5 at the minimum.
Furthermore, for a resist film having the same sensitivity characteristics as this, the optical density of the light shielding film for forming the transfer pattern is set to 2.5, which is the same as the light shielding film of the transfer mask applied with the conventional single exposure technique. When the transfer exposure is performed using the exposure technique, the integrated exposure amount corresponding to two transfer pattern exposures and six leaked light exposures is obtained when the above-described single exposure technique is applied to transfer exposure with a light-shielding film having an optical density of 2.5. It is necessary to select the optical density of the light-shielding band so as to be less than or equal to the integrated exposure amount for four leaked light exposures. The optical density of the light shielding zone that satisfies this condition is 3.0 or more.
Therefore, an optical density of 0.5 or more is required for the auxiliary light shielding film.

  The optical density required for the light-shielding film for forming the black portion of the transfer pattern varies depending on the photosensitive characteristics of the resist film on the wafer. When transfer exposure is performed on a resist film with high sensitivity, the optical density of the light shielding film is preferably 2.6 or more, and for a resist film with higher sensitivity, the optical density of the light shielding film is 2.8 or more. Is desirable. Further, when the optical density of the light shielding film is 2.6, the optical density required for the auxiliary light shielding film is 0.5 or more, and when the optical density of the light shielding film is 2.8, it is necessary for the auxiliary light shielding film. The optical density is also 0.5 or more. On the other hand, it is ideal that the light shielding film on which the transfer pattern of the binary transfer mask is formed has a higher optical density. However, there is a limit to increasing the optical density of the light shielding film by selecting a material, and the film thickness inevitably increases as the optical density is increased. As the thickness of the light-shielding film that forms the transfer pattern increases, the resist pattern becomes thicker when the light-shielding film is dry-etched to transfer the transfer pattern. The load related to the bias due to the electromagnetic field (EMF) effect increases. Considering these relationships, the light shielding film for forming the transfer pattern preferably has an optical density of 3.1 or less, and more preferably an optical density of 3.0 or less. In the case of a light shielding film having an optical density of 3.1, the optical density required for the auxiliary light shielding film is 0.5 or more.

The optical density of the auxiliary light shielding film needs to be selected in consideration of the photosensitive characteristics of the resist film on the wafer and the exposure conditions of the exposure apparatus. In order to reduce the influence when these conditions are changed, the optical density is preferably 0.7 or more, and more preferably 1.0 or more.
In the present invention, the light-shielding film and the auxiliary light-shielding film are formed as separate films. Therefore, in double exposure, a higher optical density (3.3 or more, or 3.5 or more) is formed in a region where a light-shielding band is to be formed. Even when the above is necessary, the auxiliary light shielding film can be easily made thick without affecting the thickness of the light shielding film pattern in the transfer pattern region.
On the other hand, as will be described later, the auxiliary light shielding film also functions as an etching mask when the transfer pattern is transferred to the light shielding film. In this case, since the auxiliary light shielding film is dry-etched using the resist pattern as a mask, it is not preferable that the thickness of the auxiliary light shielding film is increased in order to make the resist pattern thinner. Considering these things, the optical density of the auxiliary light shielding film is preferably 1.5 or less, and more preferably 1.2 or less.

  The mask blank of the present invention is suitable for use for producing a transfer mask to which the double exposure technique is applied.

In the present invention, the light shielding film may have a laminated structure of a light shielding layer and a surface antireflection layer.
FIG. 1 shows an example of a mask blank according to the first embodiment of the present invention.
In the first embodiment, as shown in FIG. 1, a light shielding film 10 having a laminated structure of a light shielding layer 11 and a surface antireflection layer 12 on an optically transparent substrate 1, and an auxiliary formed on the light shielding film 10. A light shielding film 20 and a resist film 100 are provided.

In the present invention, the light shielding film may have a structure including a back surface antireflection layer between the substrate and the light shielding layer.
FIG. 2 shows an example of a mask blank according to the second embodiment of the present invention.
In the second embodiment, as shown in FIG. 2, a light shielding film 10 having a laminated structure of a back surface antireflection layer 13, a light shielding layer 11, and a surface antireflection layer 12 on a light transmitting substrate 1, and the light shielding film 10. It has an auxiliary light shielding film 20 formed thereon and a resist film 100.

In the present invention, the auxiliary light shielding film preferably has etching selectivity with respect to an etching medium used when the light shielding film is etched.
In the embodiment in which the auxiliary light shielding film is formed in contact with the light shielding film as in the embodiment shown in FIGS. 1 and 2, the transfer pattern is formed only with the light shielding film in the transfer pattern area, and in the outer peripheral area of the transfer pattern area, This is because a transfer mask having a light shielding band having a laminated structure of a light shielding film and an auxiliary light shielding film can be manufactured. In addition, by using the auxiliary light shielding film as an etching mask and etching the light shielding film, the resist film is thinned and the transfer pattern is processed with high accuracy.

In this invention, the said light shielding film can be set as the film | membrane which has a transition metal and silicon as a main component, and the said auxiliary | assistant light shielding film is a film | membrane which has chromium as a main component.
Compared to dry etching with fluorine-based gas, etching films with transition metals and silicon as the main component have high etching rates, and films with chromium as the main component have significantly lower etching rates and high etching selectivity. ing. In contrast to dry etching using a mixed gas of chlorine and oxygen, a film containing chromium as a main component has a high etching rate, and a film containing transition metal and silicon as a main component has a significantly low etching rate, resulting in high etching selectivity. Have. Therefore, the auxiliary light shielding film sufficiently functions as an etching mask when the light shielding film is dry-etched. Further, a film containing chromium as a main component has an advantage that the wettability of the resist is good.

In this invention, the said light shielding film can be set as the film | membrane which has chromium as a main component, and the said auxiliary | assistant light shielding film is a film | membrane which has a transition metal and silicon as a main component.
For the same reason as described above, the auxiliary light shielding film sufficiently functions as an etching mask when the light shielding film is dry-etched. In addition, since the film containing chromium as a main component has high etching selectivity with respect to the light-transmitting substrate, there is a very small possibility that the substrate is dug when the light-shielding film is dry-etched. There is also.

In the present invention, the light shielding film may be a film containing tantalum as a main component, and the auxiliary light shielding film may be a film containing chromium as a main component.
Compared with dry etching using an etching gas of fluorine-based gas, a film containing tantalum as a main component has a high etching rate, and a film containing chrome as a main component has a significantly low etching rate and has high etching selectivity. In contrast to dry etching using a mixed gas of chlorine and oxygen, a film containing chromium as a main component has a high etching rate, and a film containing tantalum as a main component has a significantly low etching rate and has high etching selectivity. Yes. Therefore, the auxiliary light shielding film sufficiently functions as an etching mask when the light shielding film is dry-etched. Further, a film containing chromium as a main component has an advantage that the wettability of the resist is good.

In the present invention, an etching mask film having etching selectivity with respect to an etching medium used for etching these films may be provided between the light shielding film and the auxiliary light shielding film.
FIG. 3 shows an example of a mask blank according to the third embodiment of the present invention.
In the third embodiment, as shown in FIG. 3, a light shielding film 10 having a laminated structure of a light shielding layer 11 and a surface antireflection layer 12 on an optically transparent substrate 1, and etching formed on the light shielding film 10. The mask film 21, the auxiliary light shielding film 22 formed thereon, and the resist film 100 are included.

As in the third embodiment shown in FIG. 3, the etching mask film 21 is provided between the light shielding film 10 and the auxiliary light shielding film 22, so that the auxiliary light shielding film 20 having a lower limit of optical density is etched. Since the etching mask can be made thinner than when used as a mask (for example, FIGS. 1 and 2), a transfer pattern can be formed on the light shielding film 10 with higher accuracy.
For the auxiliary light shielding film 22, a material that is etched with an etching gas when the light shielding film 10 is etched can be selected. The same material as that applied to the light shielding film 10 can be applied to the auxiliary light shielding film 22.

  In the present invention, both the light shielding film and the auxiliary light shielding film can be configured to be a film containing transition metal and silicon as main components and further having an etching mask film containing chromium as a main component.

  In the present invention, both the light-shielding film and the auxiliary light-shielding film can be configured to be a film containing chromium as a main component and further having an etching mask film containing transition metal and silicon as main components.

In the present invention, the film containing transition metal and silicon as main components includes compounds containing transition metal and silicon containing nitrogen, oxygen, carbon, hydrogen, inert gas (helium, argon, xenon, etc.), boron, and the like. Can be mentioned. Here, as the transition metal (M), molybdenum (Mo), tantalum (Ta), chromium (Cr), tungsten (W), titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb) , Nickel (Ni), palladium (Pb), or an alloy thereof.
In the present invention, the film containing chromium as a main component may be a material such as chromium alone or a material containing at least one element composed of oxygen, nitrogen, carbon, hydrogen, and boron (a material containing Cr). Can be mentioned.
In the present invention, the film containing tantalum as a main component includes materials such as tantalum alone and tantalum containing at least one element composed of oxygen, nitrogen, carbon, hydrogen, and boron (material containing tantalum). Can be mentioned.
In the present invention, each of the light shielding film, the auxiliary light shielding film, and the etching mask film may have a single-layer structure or a multi-layer structure. The multi-layer structure can be a multi-layer structure formed stepwise with different compositions, or a film structure in which the composition is continuously changed.

In the present invention, the light shielding layer 11 in the light shielding film 10 is preferably made of a material having a very high light shielding property, and is preferably composed of a material having a light shielding property compared to chromium.
The light shielding layer 11 is preferably made of a Ta-based material or a material containing a transition metal and silicon having a higher optical density than that of a chromium-based layer. Moreover, it is preferable to use the material developed in order to raise optical density further about these materials.
The light shielding layer 11 is preferably made of a material (high MoSi type) having a light shielding property enhanced to the limit. The light shielding layer 11 may be made of a Ta-based material (TaN, TaB, TaC, TaBC, TaBN, TaCN, TaBCN, etc.). In particular, when Ta-based nitride is used as the material of the light shielding layer 11, even if the light shielding film 10 is a single layer (a configuration without the front surface antireflection layer 12), the surface reflectance and the back surface reflectance can be suppressed to some extent. It is. Thereby, when the upper limit of the surface reflectance and the back surface reflectance is loose, the light-shielding film 10 can be significantly thinned.

In the present invention, the surface antireflection layer 12 in the light shielding film 10 is preferably composed mainly of a material containing at least one element selected from oxygen and nitrogen in addition to transition metal and silicon.
The surface antireflection layer 12 is basically applicable to any material as long as a surface reflectance of a predetermined value or more can be obtained in a laminated structure with the light shielding layer, but is formed with the same target as the light shielding layer 11. It is preferable to use a material that can be used. When a material mainly composed of a transition metal and silicon is applied to the light shielding layer 11, the surface antireflection layer 12 is composed of a material mainly composed of a transition metal (M) and silicon (Si) (MSiO, MSiN, MSiON, MSiOC, MSiCN, MSiOCN, etc.) are preferred. Among these, MSiO and MSiON are preferable from the viewpoint of chemical resistance and heat resistance, and MSiON is preferable from the viewpoint of blanks defect quality. When a Ta-based material is applied to the light shielding layer 11, a material mainly composed of Ta (TaO, TaON, TaBO, TaBON, TaCO, TaCON, TaBCO, TaBCON, etc.) is used for the surface antireflection layer 12. preferable.

  The optical density of the entire light shielding film 10 is almost contributed by the light shielding layer 11. The surface antireflection layer 12 is provided in order to prevent a part of the exposure light reflected by the lens of the reduction optical system of the exposure apparatus from being further reflected by the light shielding film 10. It is adjusted to transmit to some extent. Thereby, the total reflection on the surface of the light shielding film 10 is suppressed, and the exposure light can be attenuated by utilizing the interference effect. Since the surface antireflection layer 12 is designed to obtain this predetermined transmittance, the contribution of the optical density to the entire light shielding film 10 is small. Even in the case of the light shielding film 10 including the back surface antireflection layer 13, the contribution of the optical density to the entire light shielding film 10 is small for the same reason. From the above, the adjustment of the optical density of the light shielding film 10 is basically performed by the light shielding layer 11. That is, it is desirable if the light shielding layer 11 can secure an optical density of 2.5 or more, and more desirably 2.8 or more.

The surface reflectance of the light shielding film 10 with respect to ArF exposure light is highly required to be 30% or less, preferably 25% or less, and 20% or less if the entire thickness of the light shielding film 1 is within an allowable range. Is most preferable.
In order to suppress the surface reflectance below a predetermined value, the thickness of the surface antireflection layer 12 is desirably larger than 5 nm. In order to obtain a lower reflectance, the film thickness is desirably 7 nm or more. Further, considering the production stability and the reduction in the thickness of the surface antireflection layer 12 due to repeated mask cleaning after the transfer mask is produced, the thickness of the surface antireflection layer 12 is preferably 10 nm or more. Considering the reduction of the thickness of the entire light shielding film 10, the thickness of the surface antireflection layer 12 having a low contribution to the optical density of the light shielding film is preferably 20 nm or less, and more preferably 15 nm or less. Furthermore, in order to further reduce the simulation load related to the electromagnetic field (EMF) effect, it is desired to be 12 nm or less.

The back surface reflectance of the light shielding film 10 with respect to ArF exposure light is highly required to be 40% or less, preferably 35% or less, and 30% or less if the entire thickness of the light shielding film 1 is within an allowable range. Is most preferable.
In the case of the light-shielding film 10 having a three-layer structure including the back surface antireflection layer 13, it is desirable that the film thickness of the back surface antireflection layer 13 is larger than 5 nm in order to suppress the back surface reflectance to a predetermined value or less. In order to obtain a lower reflectance, the film thickness is desirably 7 nm or more. Considering the reduction of the thickness of the entire light shielding film 10, the thickness of the back surface antireflection layer 13 having a low contribution to the optical density of the light shielding film is desirably 15 nm or less, and more desirably 12 nm or less. Furthermore, in order to further reduce the simulation load related to the electromagnetic field (EMF) effect, it is desired to be 10 nm or less.

As described above, the light shielding layer 11 in the light shielding film 10 is preferably made of a material having a very high light shielding property, and is preferably made of a material having a light shielding property higher than that of chromium.
A material containing a transition metal and silicon has higher light shielding properties than chromium. FIG. 4 shows a thin film containing transition metals molybdenum, silicon and nitrogen in the light-shielding film 10, and the nitrogen content in the film is 0 atomic%, 10 atomic%, 20 atomic%, 30 atomic%, 35 atomic%, In each case of 40 atomic%, the ratio of molybdenum content in the film divided by the total content of molybdenum and silicon (that is, molybdenum content when the total content of molybdenum and silicon in the light-shielding film is 100) The ratio of content expressed in atomic%, hereinafter referred to as (Mo / Mo + Si) ratio), and the relationship between the optical density per unit film thickness (ΔOD [/nm@193.4 nm]). As the nitrogen content of the light shielding film 10 increases, the optical density per unit film thickness decreases. On the other hand, as for the (Mo / Mo + Si) ratio, the optical density per unit film thickness increases as the ratio increases up to a predetermined ratio. It shows a trend. A material containing molybdenum and silicon has a problem that when the content of molybdenum is high, chemical resistance and cleaning resistance (particularly alkali cleaning and hot water cleaning) decrease. In consideration of these matters, it is preferable to set the upper limit to 40 atom%, which is a molybdenum content capable of ensuring the minimum necessary chemical resistance and washing resistance when used as a transfer mask.

  In consideration of thinning of the resist film for transferring the transfer pattern to the light shielding film 10 and reduction of the simulation load caused by the electromagnetic field (EMF) effect, the thickness of the light shielding film 10 should be at least less than 65 nm. Yes, it is desirable to be 60 nm or less. Further, as described above, the light-shielding film 10 has a two-layer laminated structure of the light-shielding layer 11 and the front-surface antireflection film 12, or three layers including the back-surface antireflection layer 13 between the light-shielding layer 11 and the translucent substrate 1. It is usual to have a laminated structure. Considering these conditions, it is desirable that the optical density per unit film thickness of the light shielding layer 11 is at least ΔOD = 0.05 [/nm@193.4 nm] or more. In this case, the nitrogen content of the light shielding layer 11 needs to be 40 atomic% or less. When the nitrogen content is 40 atomic%, the (Mo / Mo + Si) ratio needs to be 15 atomic% or more and 28 atomic% or less.

  Considering the reduction of the thickness of the light shielding film 10, it is desirable that ΔOD = 0.06 [/nm@193.4 nm] or more. In this case, the nitrogen content of the light shielding layer 11 needs to be 33 atomic% or less. When the nitrogen content is 33 atomic%, the (Mo / Mo + Si) ratio needs to be 20 atomic% or more and 30 atomic% or less, and when the nitrogen content is 30 atomic%, the (Mo / Mo + Si) ratio is It is necessary to be 15 atomic% or more and 33 atomic% or less. Furthermore, in consideration of further reduction of the simulation load related to the EMF effect, it is more desirable that the light shielding layer has ΔOD = 0.07 [/nm@193.4 nm] or more. In this case, the nitrogen content of the light shielding layer 11 needs to be 23 atomic% or less. When the nitrogen content is 23 atomic%, the (Mo / Mo + Si) ratio needs to be 20 atomic% or more and 30 atomic% or less. When the nitrogen content is 20 atomic%, the (Mo / Mo + Si) ratio is It is necessary to be 17 atomic% or more and 33 atomic% or less. When the nitrogen content of the light shielding layer 11 is 10 atomic% or more, the back surface reflectance is exposed even in a configuration without the back surface antireflection layer 13 (two-layer structure of the light shielding layer 11 and the front surface antireflection layer 12). It is possible to suppress to a range that does not affect the transfer. In consideration of dealing with various exposure conditions, it is required to suppress the back surface reflectance to 30% or less. In order to achieve this in a configuration without the back surface antireflection layer 13, it is desirable that the nitrogen content of the light shielding layer 11 is 20 atomic% or more. Although the optical density is higher when the nitrogen content of the light shielding layer 11 is less than 10 atomic%, it is necessary to reduce the back surface reflectance by providing the back surface antireflection layer 13.

  In addition, in FIG. 4, although the tendency was shown about the case where molybdenum is applied to a transition metal, the same tendency is shown also about the case where another transition metal is applied. In addition, the degree of decrease in the extinction coefficient with respect to the content in the layer is larger than that in nitrogen, and the film thickness required for the light shielding layer 11 is increased in proportion to the proportion of oxygen. Since it is possible to reduce the back surface reflectance with respect to exposure light with nitrogen alone, the content of oxygen in the lower layer is preferably less than 10 atomic%, and more preferably contains substantially no oxygen ( It is preferable that it is allowed to be contained by contamination or the like.

  In addition, the light-shielding layer containing transition metal and silicon has other elements (carbon, inert gas (helium, hydrogen, argon, xenon, etc.), etc.) within the range (less than 10%) that does not impair the above characteristics and effects. May be included.

  In the present invention, the light shielding layer substantially composed of MoSi, the light shielding layer substantially composed of MoSiCH, and the like can freely control tensile stress and compressive stress by gas pressure and heat treatment in the sputtering chamber. For example, by controlling the film stress of the MoSi light-shielding layer, the MoSiCH light-shielding layer, etc. so as to be a tensile stress, it is possible to match the compressive stress of the antireflection layer (for example, MoSiON). That is, the stress of each layer constituting the light shielding film can be offset, and the film stress of the light shielding film can be reduced as much as possible (can be substantially zero).

In the present invention, when MoSiON, MoSiO, MoSiN, MoSiOC, or MoSiOCN is applied to the surface antireflection layer, the cleaning resistance, particularly resistance to alkali (ammonia water or the like) or hot water is reduced when Mo is increased. From this point of view, it is preferable to reduce Mo as much as possible in the antireflection layer such as MoSiON, MoSiO, MoSiN, MoSiOC, and MoSiOCN.
In addition, it was found that when heat treatment (annealing) was performed at a high temperature for the purpose of stress control, a high Mo content caused a phenomenon that the surface of the film was clouded white (clouded). This is considered to be because MoO precipitates on the surface. From the viewpoint of avoiding such a phenomenon, the Mo content in the antireflection layer is preferably less than 10 at% in MoSiON, MoSiO, MoSiN, MoSiOC, MoSiOCN and the like which are antireflection layers. However, when the content of Mo is too small, abnormal discharge during DC sputtering becomes significant and the frequency of occurrence of defects increases. Therefore, it is desirable that Mo is contained within a range where it can be sputtered normally. Depending on other film formation techniques, film formation may be possible without containing Mo.

In the present invention, for example, as shown in FIG. 1, the light shielding film 10 is composed of two layers,
A light shielding layer 11 made of tantalum nitride;
A surface antireflection layer 12 formed on and in contact with the light shielding layer 11 and made of an oxide of tantalum;
The aspect which consists of is included.
By nitriding the tantalum of the light shielding layer 11, it is possible to prevent oxidation of the transfer pattern side wall of the light shielding film after the transfer mask is produced. On the other hand, in order to ensure high light-shielding performance, it is desirable to reduce the nitrogen content as much as possible. Considering these points, the nitrogen content in the light shielding layer is preferably 1 atomic% or more and 20 atomic% or less, and more preferably 5 atomic% or more and 10 atomic% or less.
An antireflection layer made of a tantalum oxide containing 50 atomic% or more of oxygen is preferable because it has an excellent antireflection effect.
With the configuration as described above, antireflection on the surface side of the light-shielding film is achieved. Further, even if the back surface antireflection layer is omitted, a certain back surface antireflection effect (for example, the back surface reflectance is 40% or less) can be obtained. Further, it is effective to improve the accuracy of the light shielding film pattern in the transfer pattern region by reducing the thickness of the light shielding film pattern in the transfer pattern region by using the structure in which the back surface antireflection layer is omitted. .

In the present invention, in the case where the light shielding film 10 is made of a transition metal and silicon-based material or a Ta-based material, the auxiliary light-shielding film 20 includes an embodiment formed of a chromium-based material.
When the light-shielding film 10 is made of a material containing a transition metal and silicon or a Ta-based material, most of these materials can be dry-etched with a fluorine-based gas. For this reason, it is preferable to use a material having resistance to the fluorine-based gas for the auxiliary light shielding film 20. Chromium-based materials are highly resistant to fluorine-based gases, and are basically materials that can be dry-etched with a mixed gas of chlorine and oxygen. When performing dry etching to be transferred to the film, the lower light shielding film can function as an etching stopper. Further, the transfer pattern can be transferred by dry etching the lower light shielding film using the auxiliary light shielding film as an etching mask, and the transfer pattern can be formed on the light shielding film with high accuracy.
In the present invention, as the auxiliary light shielding film 20, for example, a material such as chromium alone or a material containing at least one element composed of oxygen, nitrogen, carbon, and hydrogen in chromium (a material containing Cr) is used. it can. Especially, the aspect formed with the material which has any one of chromium nitride, chromium oxide, chromium nitride oxide, chromium oxycarbonitride is preferable. As the film structure of the auxiliary light-shielding film, a single-layer structure or a multi-layer structure made of the above film materials can be used. The multi-layer structure can be a multi-layer structure formed stepwise with different compositions, or a film structure in which the composition is continuously changed.
Furthermore, the auxiliary light shielding film 20 includes an embodiment in which the chromium content in the film is 45 atomic% or less. When the chromium content in the film is 45 atomic% or less, the etching rate of the auxiliary light-shielding film can be increased and the resist film thickness can be reduced.

In the present invention, for example, as shown in FIG. 3 and the like, when the light shielding film 10 is made of a MoSi material, the etching mask film 21 is made of a chromium material, and the auxiliary light shielding film 20 is a MoSi material. The aspect comprised by is included.
In this embodiment, the etching mask film 21 includes an embodiment in which chromium contains at least one of nitrogen and oxygen, and the chromium content in the film is 45 atomic% or less. Thereby, the etching rate of the etching mask film 21 can be increased.

  In the present invention, the etching mask film 21 preferably has a thickness of 5 nm to 20 nm. According to such a configuration, the CD shift amount of the etching target layer with respect to the CD (Critical Dimension) of the etching mask film (the dimensional change amount of the pattern dimension of the etching target layer with respect to the pattern dimension of the etching mask film) is less than 5 nm. A certain transfer mask can be obtained.

The inventors of the present invention provide a light-shielding film made of a material that can be dry-etched with a fluorine-based gas (a transition metal and silicon-based material or a Ta-based material), a Cr-based etching mask film, When processing using a mask blank provided with resist films (thickness of 100 nm or less) in this order (in contact with each other)
(1) The thickness of the resist film may not be reduced by simply reducing the thickness of the etching mask film (for example, 20 nm or less).
(2) From the viewpoint of reducing the film thickness of the resist film, the Cr-based etching mask film is not preferable for a material rich in Cr component because the etching rate of chlorine-based (Cl ₂ + O ₂ ) dry etching is slow. From the viewpoint, the Cr-based etching mask film is preferably a highly nitrided and highly oxidized Cr-based material with a small Cr component.
(3) From the viewpoint of reducing LER (Line Edge Roughness) of the light-shielding film pattern, a Cr-based etching mask film is preferably a material rich in Cr component because it has higher resistance to fluorine-based dry etching. The Cr-based etching mask film is preferably a Cr-based material with a large amount of Cr component.
(4) The above (2) and (3) are in a trade-off relationship, and considering this, the Cr-based etching mask film needs to have a chromium content of 45 atomic% or less. Preferably, the chromium content in the Cr-based etching mask film is preferably 35 atomic% or less, and the lower limit of the chromium content in the Cr-based etching mask film is 20 atomic%. The above is preferable, more preferably 30 atomic% or more, particularly 33 atomic% or more is preferable when the etching mask film is a chromium oxide film,
(5) Related to the above (2) and (4) (that is, related to shortening the etching time of the Cr-based etching mask film), and from the viewpoint of reducing the film thickness of the resist film, the film of the Cr-based etching mask film The thickness is preferably 20 nm or less,
(6) Related to the above (3) and (4) (that is, related to the etching resistance of the Cr-based etching mask film), the etching mask is masked until the etching process for transferring the mask pattern to the lower light shielding film is completed. Since the pattern must be able to be maintained, the thickness of the Cr-based etching mask film is preferably 5 nm or more,
I found out.

The etching rate with respect to chlorine-type gas improves, so that Cr-type material advances oxidation. Further, although not as much as when oxidized, the etching rate with respect to the chlorine-based gas is improved even if nitriding is advanced. Therefore, it is preferable to not only make the chromium content of the etching mask film 35 atomic% or less but also highly oxidize and highly nitride.
From the viewpoint of excellent defect quality of the film, chromium oxycarbonitride and chrome oxide are preferable. Further, from the viewpoint of stress controllability (a low stress film can be formed), chromium oxycarbonitride (CrOCN) is preferable.

In the present invention, the light shielding layer preferably contains a material containing at least one of carbon (C) and hydrogen (H) in addition to the transition metal (M) and silicon (Si).
In the present invention, the light-shielding film containing at least one of carbon (C) and hydrogen (H) in addition to the transition metal (M) and silicon (Si) becomes difficult to oxidize in the film during sputtering film formation. By forming silicon carbide (Si—C bond), transition metal carbide (M—C bond, for example, Mo—C bond), and silicon hydride (Si—H bond), light resistance and the like are excellent.
In the present invention, the light-shielding layer containing at least one of carbon (C) and hydrogen (H) in addition to transition metal (M) and silicon (Si) has M (transition metal) -Si bond, Si as a chemical bond state. -Si bond, MM bond, MC bond, Si-C bond, Si-H bond are included.
In the present invention, the transition metal (M) is molybdenum (Mo), tantalum (Ta), chromium (Cr), tungsten (W), titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb). , Nickel (Ni), palladium (Pb), or an alloy.

In the present invention, a thin film comprising a transition metal, silicon, carbon, silicon carbide and / or transition metal carbide is formed by sputtering film formation using a target containing carbon or an atmospheric gas containing carbon. it can.
Here, the hydrocarbon gas is, for example, methane (CH ₄ ), ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), butane (C ₄ H ₁₀ ), or the like.
By using hydrocarbon gas, carbon and hydrogen (silicon carbide, transition metal carbide, silicon hydride) can be introduced into the film.
By using a target containing carbon, only carbon (silicon carbide, transition metal carbide) can be introduced into the film. In this case, in addition to the embodiment using the MoSiC target, an embodiment using a target containing C in one or both of the Mo target and the Si target, and an embodiment using the MoSi target and the C target are included.

In the present invention, a thin film containing a transition metal, silicon, hydrogen, and containing silicon hydride can be formed by sputtering film formation using an atmospheric gas containing hydrogen.
In this method, only hydrogen (silicon hydride) can be introduced into the film.
This method includes an embodiment using a Mo target and an Si target in addition to an embodiment using a MoSi target. Further, in this method, when carbon (silicon carbide, transition metal carbide) is further included in the film, a target containing C in one or both of the Mo target and the Si target is used in addition to the embodiment using the MoSiC target. A mode to use and a mode to use a MoSi target and a C target are included.

In the present invention, the thin film is preferably formed by adjusting the pressure and / or power of the atmospheric gas during the sputtering film formation.
It is considered that when the pressure of the atmospheric gas is low (in this case, the film formation rate is low), carbides (silicon carbide or transition metal carbide) are easily formed. Further, it is considered that when power is lowered, carbides (silicon carbide and transition metal carbide) are easily formed.
In the present invention, carbide and the like (silicon carbide and transition metal carbide) are formed as described above, and the pressure and / or electric power of the atmospheric gas at the time of the sputtering film formation is set so that the above-described effects of the present invention can be obtained. adjust.
Further, the present invention provides a stable Si-C bond and / or a stable transition metal MC bond formed in the film during sputtering film formation so that the above-described effects of the present invention can be obtained. The pressure and / or power of the atmospheric gas during sputtering film formation is adjusted.
On the other hand, it is considered that carbide or the like (silicon carbide or transition metal carbide) is difficult to be formed when the pressure of the atmospheric gas is high (in this case, the film forming speed is high). Moreover, it is thought that it is difficult to form carbides (silicon carbides and transition metal carbides) when the power is lowered.

In addition, as for content of carbon in the light shielding layer 11, 1-10 atomic% is preferable. When the carbon content of the light shielding film is 1 atomic% or less, silicon carbide and / or transition metal carbide is difficult to form, and when the carbon content is more than 10 atomic%, it is difficult to reduce the thickness of the light shielding film. become.
The hydrogen content is preferably 1 to 10 atomic%. When the hydrogen content of the light shielding film is 1 atomic% or less, silicon hydride is hardly formed, and when the hydrogen content is 10 atomic% or more, film formation becomes difficult.

  In the present invention, an adhesion improving layer that improves the adhesion between the resist film 100 and a lower layer film in contact with the resist film such as the auxiliary light shielding film 20 may be formed. As the adhesion improving layer, for example, a configuration in which an HMDS (hexamethyldisilazane) layer is first formed on the surface of a lower layer film in contact with a resist film such as the auxiliary light shielding film 22 by a transpiration process. In addition, when the lower layer film in contact with the resist film such as the auxiliary light-shielding film 20 is dry-etched using the resist pattern as a mask, it does not dissolve in the developer used for forming the resist pattern on the resist film 100. A configuration is also possible in which both are etched and a resin layer having a characteristic of being removed at the time of removal processing (solvent removal, oxygen plasma ashing, etc.) for removing the resist pattern is also included.

  In the present invention, the auxiliary light shielding film 20 needs to have a film thickness that can secure an optical density of 0.5 or more. In the case where the etching mask film 21 is not provided between the light shielding film 10 and the auxiliary light shielding film 20 alone, it is necessary to ensure an optical density of 0.5 or more. In this case, the auxiliary light shielding film 20 needs to have a minimum thickness of at least 22 nm, preferably 25 nm or more, and more preferably 30 nm or more. On the other hand, in the case of this configuration, since the auxiliary light shielding film 20 needs to also serve as an etching mask, if the film thickness is too thick, the accuracy when the transfer pattern is transferred to the light shielding film 10 is lowered. Considering this point, the thickness of the auxiliary light shielding film 20 is at least 45 nm or less, preferably 40 nm or less, and more preferably 35 nm or less. Although the auxiliary light shielding film 20 is used, there is no need to reduce the surface reflectance of the auxiliary light shielding film 20 with respect to the exposure light to the extent of the surface reflectance with respect to the exposure light of the light shielding film 10 due to the mechanism of the exposure apparatus or the like. In this case, the content of the metal element in the film can be increased. In this case, the lower limit of the film thickness of the auxiliary light shielding film 20 can be set to 9 nm.

  In the present invention, in the case where the etching mask film 21 is provided between the light shielding film 10, the etching mask film 21 needs to be able to transfer the transfer pattern to the light shielding film 10 with high accuracy. Even if a material having etching selectivity with respect to an etching medium when dry-shielding the light-shielding film 10 is selected as a material for forming the etching mask film 21, the etching mask film 21 is slightly etched. Considering this point, the thickness of the etching mask film 21 needs to be at least 5 nm or more, preferably 7 nm or more. On the other hand, as described above, the transfer accuracy decreases as the thickness of the etching mask film increases. In addition, when the etching mask film is removed in the final stage of manufacturing the transfer mask, the light shielding film 10 and the light-transmitting film are used. The damage given to the substrate 1 also increases. Considering these, the thickness of the etching mask film 21 needs to be 20 nm or less, and preferably 15 nm or less.

The transfer mask of the present invention is produced using each of the above mask blanks.
Thereby, a transfer mask having the effects described above can be provided.

The transfer mask of the present invention is a binary transfer mask to which ArF exposure light is applied,
In the transfer pattern area on the translucent substrate, has a transfer pattern formed of a light shielding film,
A light-shielding band formed from a laminated structure of a light-shielding film and an auxiliary light-shielding film on the outer side of the transfer pattern area (leakage light area) from the substrate side,
The optical density of the light shielding film is 2.5 or more and 3.1 or less, and the optical density of the auxiliary light shielding film is 0.5 or more.
It is characterized by that.
Thereby, a transfer mask having the effects described above can be provided.

The transfer mask set of the present invention is a transfer mask set in which the above transfer mask is a set of two sheets,
The two transfer masks are used for exposure transfer by a double exposure technique,
Each of the transfer patterns formed on the two transfer masks is obtained by dividing one transfer pattern to be transferred and exposed onto a transfer target object into two sparse transfer patterns.
Thereby, a transfer mask set suitable for use in the double exposure technique can be provided. Note that this is a method of dividing one transfer pattern to be transferred and exposed on the transfer object into two sparse transfer patterns. Any known technique (such as simulation calculation) that divides a dense transfer pattern into two relatively sparse transfer patterns so that the transfer pattern can be transferred can be used. Technology may be used.

In the present invention, it is preferable to use a dry etching gas comprising a mixed gas containing a chlorine-based gas and an oxygen gas for the dry etching of the chromium-based thin film. The reason for this is that, for a chromium-based thin film made of a material containing chromium and an element such as oxygen or nitrogen, the dry etching rate can be increased by performing dry etching using the above dry etching gas, This is because the dry etching time can be shortened and a light-shielding film pattern having a good cross-sectional shape can be formed. The chlorine-based gas used for dry etching gas, for _{example, Cl 2, SiCl 4, HCl} , CCl 4, CHCl 3 , and the like.

In the present invention, dry etching of a thin film containing a transition metal and silicon includes, for example, fluorine-based gases such as SF ₆ , CF ₄ , C ₂ F ₆ , and CHF ₃ , and these, and He, H ₂ , and N _2. , Ar, C ₂ H ₄ , O _2, or a mixed gas can be used.
For dry etching of a tantalum-based material thin film, for example, fluorine-based gases such as SF ₆ , CF ₄ , C ₂ F ₆ , CHF ₃ , and these, and He, H ₂ , N ₂ , Ar, C ₂ H ₄ , O ₂ , mixed gases such as Cl ₂ and CH ₂ Cl ₂ , or mixed gases such as He, H ₂ , N ₂ , Ar, and C ₂ H ₄ can be used.

In the present invention, the resist is preferably a chemically amplified resist. This is because it is suitable for high-precision processing.
In the present invention, the resist is preferably an electron beam drawing resist. This is because it is suitable for high-precision processing.
The present invention is applied to a mask blank for electron beam drawing in which a resist pattern is formed by electron beam drawing.

In the present invention, examples of the substrate include a synthetic quartz substrate, a CaF ₂ substrate, a soda lime glass substrate, a non-alkali glass substrate, a low thermal expansion glass substrate, and an aluminosilicate glass substrate.

In the present invention, the mask blank includes a mask blank and a mask blank with a resist film.
In the present invention, the transfer mask includes a binary mask and a reticle that do not use the phase shift effect.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
(Manufacture of mask blank)
1 is a cross-sectional view of a binary mask blank of Example 1. FIG.
A synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the light-transmitting substrate 1. Each of the antireflection layers 12) was formed.
Specifically, a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 21 atomic%: 79 atomic%) is used on the light-transmitting substrate 1, and argon (Ar) and nitrogen (N ₂ ) are used. ) In a mixed gas atmosphere (gas flow ratio Ar: N ₂ = 25: 28), a gas pressure of 0.07 Pa, a DC power source power of 2.1 kW, and reactive sputtering (DC sputtering) to form the light shielding layer 11 ( MoSiN film: Mo: Si: N = 14.7 atomic%: 56.2 atomic%: 29.1 atomic%) was formed with a film thickness of 47 nm.
Next, a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 4 atomic%: 96 atomic%) is used on the light shielding layer 11, and argon (Ar), oxygen (O ₂ ), and nitrogen ( N ₂ ) and helium (He) mixed gas atmosphere (gas flow ratio Ar: O ₂ : N ₂ : He = 6: 3: 11: 17), gas pressure is 0.1 Pa, and DC power is 3. The surface antireflection layer (MoSiON film: Mo: Si: O: N = 2.6 atomic%: 57.1 atomic%: 15.9 atomic%: 24.4 atoms) was set to 0 kW by reactive sputtering (DC sputtering). %) 12 was formed with a film thickness of 10 nm.
The elemental analysis of each layer (thin film) used Rutherford backscattering analysis.
The total film thickness of the light shielding film 10 was 57 nm. The optical density (OD) of the light shielding film 10 was 2.8 at a wavelength of 193 nm of ArF excimer laser exposure light.
Next, the substrate was heated (annealed) at 450 ° C. for 30 minutes.

Next, the auxiliary light shielding film 20 was formed on the light shielding film 10 (FIG. 1).
Specifically, using a DC magnetron sputtering apparatus, using a chromium target, a mixed gas atmosphere of Ar, CO ₂ , N ₂ and He (gas flow ratio Ar: CO ₂ : N ₂ : He = 21: 37: 11:31), gas pressure: 0.2 Pa, DC power supply power: 1.8 kW, and a CrOCN film (Cr content in the film: 33 atomic%) was formed to a thickness of 22 nm. At this time, by annealing the CrOCN film at a temperature lower than the annealing temperature of the MoSi light-shielding film, the stress of the CrOCN film is as low as possible without affecting the film stress of the MoSi light-shielding film (preferably substantially zero film stress). It adjusted so that it might become.
For elemental analysis of the CrOCN film (thin film), Rutherford backscattering analysis was used.
The auxiliary light shielding film 20 is made of CrOCN having a Cr content of 33 atomic% in the film, and has an optical density of 0.5 with a film thickness of 22 nm.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure and a double exposure by the above was obtained.

(Production of transfer mask and transfer mask set)
In order to expose and transfer the transfer pattern onto the transfer object (resist film on the wafer) using the double exposure technique, one dense design transfer pattern was divided to generate two paired design transfer patterns. Next, using the manufactured two binary mask blanks, two transfer masks (transfer mask sets) each having two divided transfer patterns were prepared by the following procedure ( Hereinafter, a manufacturing process of one transfer mask will be described.)
On the auxiliary light shielding film 20 of the mask blank, a chemically amplified positive resist 100 (PRL009: manufactured by Fuji Film Electronics Materials) for electron beam drawing (exposure) was applied by spin coating so as to have a film thickness of 100 nm. (FIG. 1, FIG. 5 (1)).
Next, a desired pattern was drawn on the resist film 100 using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern 100a (FIG. 5 (2)).
Next, the auxiliary light shielding film 20 was dry-etched using the resist pattern 100a as a mask to form the auxiliary light shielding film pattern 20a (FIG. 5 (3)). As a dry etching gas, a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) was used.
Next, the remaining resist pattern 100a was peeled off with a chemical solution.
Next, using the auxiliary light shielding film pattern 20a as a mask, the light shielding film 10 was dry-etched using a mixed gas of SF ₆ and He to form the light shielding film pattern 10a (FIG. 5D).
Next, a resist film 110 of a positive resist for electron beam drawing (exposure) (FEP171: manufactured by Fuji Film Electronics Materials Co., Ltd.) was applied by spin coating so as to have a film thickness of 100 nm (FIG. 5 (5)).
Next, the resist film 110 is subjected to drawing exposure with a pattern of a light shielding portion (light shielding band) using an electron beam drawing apparatus, and developed with a predetermined developer to form a resist pattern 110b (FIG. 5 (6)). ) Using this resist pattern 110b as a mask, the auxiliary light shielding film pattern 20a was etched by dry etching with a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) to form the auxiliary light shielding film pattern 20b. (FIG. 5 (7)).
Next, the resist pattern 110b is peeled off, subjected to predetermined cleaning, and binary transfer having a light-shielding portion (light-shielding band) 80 composed of the auxiliary light-shielding film pattern 20b and the portion of the light-shielding film pattern 10a therebelow. A mask was obtained (FIG. 5 (8)).
As described above, two transfer masks were prepared from the mask blank of Example 1, and a binary transfer mask set corresponding to the double exposure technology was prepared.

  In the transfer mask manufacturing example, the resist pattern 100a is peeled and removed after the auxiliary light shielding film pattern 20a is formed. However, the resist pattern 100a can be peeled and removed after the light shielding film pattern 10a is formed. The same applies to Examples 2, 3, 6, and 7 described later.

(Comparative Example 1)
(Manufacture of mask blank)
In the same manner as in Example 1, a MoSiN film (light shielding layer 11) having a thickness of 50 nm and a MoSiON film (surface antireflection layer 12) having a thickness of 10 nm are formed on the light-transmitting substrate 1 as the light shielding film 10, respectively. Formed (FIG. 1).
Next, an etching mask film made of CrN having a Cr content of 50 atomic% is formed on the light shielding film 10 to a thickness of 10 nm (a configuration in which the auxiliary light shielding film 20 in FIG. 1 is replaced with an etching mask film). Hereinafter, description will be given as the etching mask film 20.)
The total film thickness of the light shielding film 10 was 60 nm, and the optical density (OD) of the light shielding film 10 was 2.8 at the wavelength of 193 nm of ArF excimer laser exposure light.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure by the above was obtained.

(Production of transfer mask and transfer mask set)
In the same process as in the second embodiment, an etching mask film that corresponds to the auxiliary light-shielding film pattern 20b is produced, and a binary type having a light-shielding part (light-shielding band) 80 composed of a part of the light-shielding film pattern 10a below the etching mask film. A transfer mask was obtained (FIG. 5 (8)).
As described above, two transfer masks were prepared from the mask blank of Comparative Example 1 to prepare a binary transfer mask set.

(Comparative Example 2)
(Manufacture of mask blank)
In the same manner as in Comparative Example 1, a MoSiN film (light shielding layer 11) and a MoSiON film (surface antireflection layer 12) were formed as the light shielding film 10 on the translucent substrate 1 (FIG. 1). At this time, the film thickness of the MoSiN film (light shielding layer 11) was changed from 50 nm to 60 nm.
The total film thickness of the light shielding film 10 was 70 nm. The optical density (OD) of the light-shielding film 10 was 3.3 at a wavelength of 193 nm of ArF excimer laser exposure light.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure by the above was obtained.

(Preparation of transfer mask)
After the light shielding film pattern 10a is formed in the same manner as in Comparative Example 1 (FIG. 5 (4)), the etching mask pattern 20a is peeled off by dry etching with a mixed gas of Cl ₂ and O ₂ and hits the auxiliary light shielding film pattern 20b. A binary transfer mask having a structure in which nothing was formed was obtained.
As described above, two transfer masks were prepared from the mask blank of Comparative Example 2 to prepare a binary transfer mask set.

(Example 2)
(Manufacture of mask blank)
FIG. 2 is a cross-sectional view of the binary mask blank of the second embodiment.
A synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the light-transmitting substrate 1. (Light shielding layer 11) and MoSiON film (surface antireflection layer 12) were formed.
Specifically, a mixed target (Mo: Si = 4 atomic%: 96 atomic%) of molybdenum (Mo) and silicon (Si) is used on the light-transmitting substrate 1, and argon (Ar) and nitrogen (N ₂ ) are used. ) And helium (He) mixed gas atmosphere (gas flow ratio Ar: N ₂ : He = 6: 11: 16), gas pressure is 0.1 Pa, DC power supply is 3.0 kW, and reactive sputtering ( A back antireflection layer (MoSiN film: Mo: Si: N = 2.3 atomic%: 56.5 atomic%: 41.2 atomic%) 13 was formed to a thickness of 12 nm by DC sputtering.
Next, a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 21 atomic%: 79 atomic%) is used on the back surface antireflection layer 13, and argon (Ar), methane (CH ₄ ), and Reactive sputtering (DC sputtering) in a mixed gas atmosphere of helium (He) (gas flow ratio Ar: CH ₄ : He = 10: 1: 50) with a gas pressure of 0.3 Pa and a DC power supply of 2.0 kW. ) To form a light shielding layer (MoSiCH film: Mo: Si: C: H = 19.2 atomic%: 77.3 atomic%, C: 2.0 atomic%, H: 1.5 atomic%) 11 to 29 nm Formed with thickness.
Next, a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 4 atomic%: 96 atomic%) is used on the light shielding layer 11, and argon (Ar), oxygen (O ₂ ), and nitrogen ( N ₂ ) and helium (He) mixed gas atmosphere (gas flow ratio Ar: O ₂ : N ₂ : He = 6: 5: 11: 16), gas pressure is 0.1 Pa, and DC power is 3. The surface antireflection layer (MoSiON film: Mo: Si: O: N = 2.6 atomic%: 57.1 atomic%: 15.9 atomic%: 24.4 atoms) was set to 0 kW by reactive sputtering (DC sputtering). %) 12 was formed with a film thickness of 15 nm.
The elemental analysis of each layer (thin film) used Rutherford backscattering analysis.
The total film thickness of the light shielding film 10 was 56 nm. The optical density (OD) of the light shielding film 10 was 2.8 at a wavelength of 193 nm of ArF excimer laser exposure light.
Next, the substrate was heated (annealed) at 450 ° C. for 30 minutes.

Next, the auxiliary light shielding film 20 was formed on the light shielding film 10 (FIG. 2).
Specifically, using a DC magnetron sputtering apparatus, using a chromium target, a mixed gas atmosphere of Ar, CO ₂ , N ₂ and He (gas flow ratio Ar: CO ₂ : N ₂ : He = 21: 37: 11:31), gas pressure: 0.2 Pa, DC power supply: 1.8 kW, and a CrOCN film (Cr content in the film: 33 atomic%) was formed to a thickness of 21 nm. At this time, by annealing the CrOCN film at a temperature lower than the annealing temperature of the MoSi light-shielding film, the stress of the CrOCN film is as low as possible without affecting the film stress of the MoSi light-shielding film (preferably substantially zero film stress). It adjusted so that it might become.
For elemental analysis of the CrOCN film (thin film), Rutherford backscattering analysis was used.
The auxiliary light shielding film 20 is made of CrOCN having a Cr content of 33 atomic% in the film, and has an optical density of 0.7 at a film thickness of 25 nm.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure and the double exposure technique according to the above was obtained.

(Preparation of transfer mask)
Using the binary mask blank of Example 2, the binary transfer mask of Example 2 was produced in the same manner as in Example 1 above.
As described above, a transfer mask set for double exposure was produced from the mask blank of Example 2.

Example 3
(Manufacture of mask blank)
FIG. 3 is a cross-sectional view of the binary mask blank of the third embodiment.
As in Example 1, a synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches was used as the light transmitting substrate 1, and a MoSiN film (light shielding layer) was formed on the light transmitting substrate 1 as the light shielding film 10. 11) and a MoSiON film (surface antireflection layer 12).
Next, an etching mask film 21 was formed on the light shielding film 10 (FIG. 3).
Specifically, a CrOCN film (Cr content in the film: 33 atom%) was formed to a thickness of 10 nm under the same film formation conditions as those of the auxiliary light shielding film 20 of Example 1.

Next, an auxiliary light shielding film 22 was formed on the etching mask film 21 (FIG. 3).
Specifically, the auxiliary light shielding film 22 (MoSiN film: Mo: Si: N = 14.7 atomic%: 56.2 atomic%: 29 under the same film formation conditions as the formation of the auxiliary light shielding film 20 of Example 3. .1 atomic%) was formed with a film thickness of 15 nm.
The etching mask film 21 is made of CrOCN having a Cr content of 33 atomic% in the film, and the auxiliary light shielding film 22 is made of MoSiN having a Mo content of 14.7 atomic%. And the auxiliary light shielding film 22 with a total film thickness of 25 nm and an optical density of 0.7.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure and a double exposure by the above was obtained.

  In the embodiment 3, the etching mask film 21 with respect to the light shielding film 10 can be made thinner than the Cr-based auxiliary light shielding film 20 (also serving as an etching mask) in the first embodiment. Thereby, higher etching accuracy of the light shielding film 10 is obtained.

(Preparation of transfer mask)
As in the first embodiment, the double exposure technique is applied to divide one dense design transfer pattern into two transfer patterns to be paired, and two pairs of binary mask blanks manufactured are used to form a pair 2 Two transfer masks (transfer mask sets) each having one transfer pattern were prepared by the following procedure.
HMDS (hexamethyldisilazane) evaporated using nitrogen gas was brought into contact with the surface of the auxiliary light shielding film 20 of the mask blank to form a very thin adhesion improving layer made of an HMDS layer. The HMDS layer is a hydrophobic surface layer and improves the adhesion of the resist. (FIG. 3, FIG. 6 (1)).
On the adhesion improving layer of the mask blank, a chemically amplified positive resist 100 for electron beam drawing (exposure) (PRL009: manufactured by Fuji Film Electronics Materials Co., Ltd.) was applied by spin coating so as to have a film thickness of 75 nm. (FIG. 3, FIG. 6 (1)).
Next, a desired pattern was drawn on the resist film 100 using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern 100a (FIG. 6B).
Next, the auxiliary light shielding film 22 was dry-etched using the resist pattern 100a as a mask to form the auxiliary light shielding film pattern 22a (FIG. 6 (3)). A mixed gas of SF ₆ and He was used as the dry etching gas.
Next, the remaining resist pattern 100a was peeled off with a chemical solution. At this time, the adhesion improving layer is also peeled and removed at the same time.
Next, dry etching of the etching mask film 21 was performed using the auxiliary light shielding film pattern 22a as a mask to form an etching mask pattern 21a (FIG. 6 (4)). As a dry etching gas, a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) was used.
Next, a resist film 110 of an electron beam drawing (exposure) positive resist (FEP171: manufactured by Fuji Film Electronics Materials) was applied on the substrate so as to have a film thickness of 100 nm (FIG. 6). (5)).
Next, the resist film 110 was subjected to drawing exposure with a pattern of a light-shielding portion (light-shielding band) using an electron beam drawing apparatus, and developed with a predetermined developer to form a resist pattern 110b (FIG. 6 (6)). ).
Next, using the etching mask pattern 21a as a mask, the light shielding film 10 was dry-etched using a mixed gas of SF ₆ and He to form the light shielding film pattern 10a (FIG. 6 (7)). At the same time, the auxiliary light shielding film pattern 22a was etched by dry etching using the resist pattern 110b as a mask to form the auxiliary light shielding film pattern 22b (FIG. 6 (7)).
Next, using the resist pattern 110b and the auxiliary light shielding film pattern 22b as a mask, the etching mask pattern 21a is etched by dry etching with a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) to obtain an etching mask pattern. 21b was formed (FIG. 6 (8)).
Next, the resist pattern 110b is peeled off, subjected to predetermined cleaning, and a transfer mask having a light-shielding portion (light-shielding band) 80 composed of the auxiliary light-shielding film pattern 22b, the etching mask pattern 21b, and the light-shielding film pattern 10a. (FIG. 6 (9)).
As described above, two transfer masks were produced from the mask blank of Example 3, and a transfer mask set corresponding to double exposure was produced.

Example 4
(Manufacture of mask blank)
FIG. 6A is a cross-sectional view of the binary mask blank of the fifth embodiment.
A synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the translucent substrate 1. (Light shielding layer 11) and a CrOCN film (surface antireflection layer 12) were formed (see FIG. 2).
Specifically, a chromium (Cr) target is used on the light-transmitting substrate 1 and a mixed gas atmosphere (gas flow rate) of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He). The ratio of Ar: CO ₂ : N ₂ : He = 24: 29: 12: 35), the gas pressure is 0.2 Pa, the power of the DC power source is 1.7 kW, and the back surface antireflection layer is formed by reactive sputtering (DC sputtering). (CrOCN film) 13 was formed to a thickness of 31 nm.
Next, a chromium (Cr) target is used on the back surface antireflection layer 13, and a mixed gas atmosphere of argon (Ar), nitric oxide (NO), and helium (He) (gas flow ratio Ar: NO: He = 27). 18:55), the gas pressure was 0.1 Pa, the power of the DC power source was 1.7 kW, and the light-shielding layer (CrON film) 11 was formed to a thickness of 15 nm by reactive sputtering (DC sputtering).
Next, a mixed gas atmosphere (gas flow ratio Ar: CO) of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He) is used on the light shielding layer 11 using a chromium (Cr) target. ₂ : N ₂ : He = 21: 37: 11: 31), the gas pressure is 0.2 Pa, the power of the DC power source is 1.8 kW, and the surface antireflection layer (CrOCN film) is formed by reactive sputtering (DC sputtering). 12 was deposited to a thickness of 14 nm.
The elemental analysis of each layer (thin film) used Rutherford backscattering analysis.
The total film thickness of the light shielding film 10 was 60 nm. The optical density (OD) of the light-shielding film 10 was 2.5 at a wavelength of 193 nm of ArF excimer laser exposure light.

Next, an etching mask film 21 was formed on the light shielding film 10 (FIG. 6A).
Specifically, using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 4 atomic%: 96 atomic%), the reaction is performed in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ). Etching mask film 21 (MoSiN film: Mo: Si: N = 2.9 atomic%: 67.5 atomic%: 29.6 atomic%) was formed to a thickness of 5 nm by reactive sputtering (DC sputtering).

Next, an auxiliary light shielding film 22 was formed on the etching mask film 21 (FIG. 6A).
Specifically, the auxiliary light shielding film 22 (CrOCN film) was formed to a thickness of 20 nm under the same film formation conditions as those of the auxiliary light shielding film 20 of Example 1.
The etching mask film 21 is made of MoSiN having a Mo content of 14.7 atomic%, and the auxiliary light shielding film 22 is made of CrOCN having a Cr content of 33 atomic% in the film. And the auxiliary light shielding film 22 with a total film thickness of 25 nm and an optical density of 0.6.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure and a double exposure by the above was obtained.

(Preparation of transfer mask)
As in the first embodiment, the double exposure technique is applied to divide one dense design transfer pattern into two transfer patterns to be paired, and two pairs of binary mask blanks manufactured are used to form a pair 2 Two transfer masks (transfer mask sets) each having one transfer pattern were prepared by the following procedure.
On the auxiliary light shielding film 22 of the mask blank, a chemically amplified positive resist 100 for electron beam drawing (exposure) (PRL009: manufactured by Fuji Film Electronics Materials Co., Ltd.) was applied by spin coating so that the film thickness became 75 nm. (FIG. 6 (1)).
Next, a desired pattern was drawn on the resist film 100 using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern 100a (FIG. 6B).
Next, the auxiliary light shielding film 22 was dry-etched using the resist pattern 100a as a mask to form the auxiliary light shielding film pattern 22a (FIG. 6 (3)). As a dry etching gas, a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) was used.
Next, the remaining resist pattern 100a was peeled off with a chemical solution.
Next, using the auxiliary light shielding film pattern 22a as a mask, the etching mask film 21 was dry-etched to form an etching mask film pattern 21a (FIG. 6D). A mixed gas of SF ₆ and He was used as the dry etching gas.
Next, a resist film 110 of an electron beam drawing (exposure) positive resist (FEP171: manufactured by Fuji Film Electronics Materials) was applied on the substrate so as to have a film thickness of 100 nm (FIG. 6). (5)).
Next, the resist film 110 was subjected to drawing exposure with a pattern of a light-shielding portion (light-shielding band) using an electron beam drawing apparatus, and developed with a predetermined developer to form a resist pattern 110b (FIG. 6 (6)). reference).
Next, using the etching mask film pattern 21a as a mask, the light shielding film 10 is dry-etched using a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) to form the light shielding film pattern 10a. (See FIG. 6 (7)). At the same time, the auxiliary light shielding film pattern 22a was etched by dry etching using the resist pattern 110b as a mask to form the auxiliary light shielding film pattern 22b (see FIG. 6 (7)).
Next, using the resist pattern 110b and the auxiliary light shielding film pattern 22b as a mask, the etching mask film pattern 21a is etched by dry etching with a mixed gas of SF ₆ and He to form an etching mask film pattern 21b (FIG. 6 ( 8)).
Next, the resist pattern 110b is peeled off, subjected to predetermined cleaning, and a transfer mask having a light shielding portion (light shielding band) 80 composed of the auxiliary light shielding film pattern 20b and the portion of the light shielding film pattern 10a below the auxiliary light shielding film pattern 20b. (See FIG. 6 (9)).
As described above, two transfer masks were prepared from the mask blank of Example 4, and a transfer mask set corresponding to double exposure was prepared.

Example 5
(Manufacture of mask blank)
FIG. 1 is a cross-sectional view of a binary mask blank of Example 5.
A synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the light-transmitting substrate 1, and a tantalum nitride (TaN) film (light-blocking layer 11) is formed on the light-transmitting substrate 1 as the light-blocking film 10. A tantalum oxide (TaO) film (surface antireflection layer 12) was formed.
Specifically, a DC magnetron sputtering apparatus is used, a Ta target is used, the introduced gas and its flow rate: Ar = 39.5 sccm, N ₂ = 3 sccm, the power of the DC power source: 1.5 kW, and the film thickness is 41 nm. A film made of tantalum nitride (TaN) (Ta: 93 atomic%, N: 7 atomic%) was formed. Next, using the same Ta target, it is made of tantalum oxide (TaO) with a film thickness of 11 nm under the conditions of introduced gas and its flow rate: Ar = 58 sccm, O ₂ = 32.5 sccm, and DC power supply: 0.7 kW. A film (Ta: 42 atomic%, O: 58 atomic%) was formed.
The total film thickness of the light shielding film 10 was 52 nm. The optical density (OD) of the light-shielding film 10 was 3.0 at a wavelength of 193 nm of ArF excimer laser exposure light.

Next, an auxiliary light shielding film 20 was formed on the light shielding film 10 (FIG. 5A).
Specifically, using a DC magnetron sputtering apparatus, using a chromium target, a mixed gas atmosphere of Ar, CO ₂ , N ₂ and He (gas flow ratio Ar: CO ₂ : N ₂ : He = 21: 37: 11:31), gas pressure: 0.2 Pa, DC power supply: 1.8 kW, and a CrOCN film (Cr content in the film: 33 atomic%) was formed to a thickness of 22 nm. At this time, by annealing the CrOCN film at a temperature lower than the annealing temperature of the MoSi light-shielding film, the stress of the CrOCN film is as low as possible without affecting the film stress of the MoSi light-shielding film (preferably substantially zero film stress). It adjusted so that it might become.
The elemental analysis of each layer (thin film) used Rutherford backscattering analysis.
The auxiliary light shielding film 20 is made of CrOCN having a Cr content of 33 atomic% in the film, and has an optical density of 0.5 with a film thickness of 22 nm.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure and the double exposure technique according to the above was obtained.

(Preparation of transfer mask)
As in the first embodiment, the double exposure technique is applied to divide one dense design transfer pattern into two transfer patterns to be paired, and two pairs of binary mask blanks manufactured are used to form a pair 2 Two transfer masks (transfer mask sets) each having one transfer pattern were prepared by the following procedure.
On the auxiliary light shielding film 20 of the mask blank, a chemically amplified positive resist 100 (PRL009: manufactured by Fuji Film Electronics Materials) for electron beam drawing (exposure) was applied by spin coating so as to have a film thickness of 100 nm. (FIG. 1, FIG. 5 (1)).
Next, a desired pattern was drawn on the resist film 100 using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern 100a (FIG. 5 (2)).
Next, the auxiliary light shielding film 20 is dry-etched using the resist pattern 100a as a mask to form the auxiliary light shielding film pattern 20a (FIG. 5 (3)). As a dry etching gas, a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) was used.
Next, the remaining resist pattern 100a was peeled off with a chemical solution.
Next, using the auxiliary light shielding film pattern 20a as a mask, the light shielding film 10 was dry etched to form the light shielding film pattern 10a (FIG. 5D). At this time, a mixed gas of CHF ₃ and He was used as a dry etching gas for the tantalum oxide (TaO) layer 12. A Cl ₂ gas was used as a dry etching gas for the tantalum nitride (TaN) layer 11.
Next, a resist film 110 of an electron beam drawing (exposure) positive resist (FEP171: manufactured by Fuji Film Electronics Materials Co., Ltd.) was applied by a spin coating method so as to have a film thickness of 200 nm (FIG. 5 (5)).
Next, the resist film 110 is subjected to drawing exposure with a pattern of a light shielding portion (light shielding band) using an electron beam drawing apparatus, and developed with a predetermined developer to form a resist pattern 110b (FIG. 5 (6)). ) Using this resist pattern 110b as a mask, the auxiliary light shielding film pattern 20a was etched by dry etching with a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) to form the auxiliary light shielding film pattern 20b. (FIG. 5 (7)).
Next, the resist pattern 110b is peeled off, subjected to predetermined cleaning, and binary transfer having a light-shielding portion (light-shielding band) 80 composed of the auxiliary light-shielding film pattern 20b and the portion of the light-shielding film pattern 10a therebelow. A mask was obtained (FIG. 5 (8)).
As described above, two transfer masks were produced from the mask blank of Example 5, and a transfer mask set corresponding to the double exposure technique was produced.

Example 6
(Manufacture of mask blank)
FIG. 1 is a sectional view of a binary mask blank of Example 6.
A synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the light-transmitting substrate 1, and a MoSiN film (light-blocking layer 11) and a MoSiN film (surface) are formed on the light-transmitting substrate 1 as the light-blocking film 10. Each of the antireflection layers 12) was formed.
Specifically, using a DC magnetron sputtering apparatus, using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 13 atomic%: 87 atomic%), argon (Ar) and nitrogen (N ₂ ) In a mixed gas atmosphere (Mo: 10.2 atomic%, Si: 64.7 atomic%, N: 25.1 atomic%). Next, using the same mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 13 atomic%: 87 atomic%), the film is formed in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ). A film made of MoSiN having a thickness of 13 nm (Mo: 7.5 atomic%, Si: 50.1 atomic%, N: 42.4 atomic%) was formed.
The total film thickness of the light shielding film 10 was 57 nm. The optical density (OD) of the light shielding film 10 was 2.8 at a wavelength of 193 nm of ArF excimer laser exposure light.

Next, an auxiliary light shielding film 20 was formed on the light shielding film 10. Specifically, a DC magnetron sputtering apparatus is used, a chromium target is used, a film is formed in a mixed gas atmosphere of Ar and N _2, and a CrN film (Cr content in the film: 80 atomic%) is 9 nm. It was formed with a film thickness. At this time, the CrN film was annealed at 200 ° C. to adjust the stress of the CrN film as low as possible.
The elemental analysis of each layer (thin film) used Rutherford backscattering analysis.
The auxiliary light shielding film 20 is made of CrN having a Cr content of 80 atomic% in the film, and has an optical density of 0.5 with a film thickness of 9 nm.
The binary mask blank which formed the light shielding film for ArF excimer laser exposure and the double exposure technique according to the above was obtained.

(Preparation of transfer mask)
As in the first embodiment, the double exposure technique is applied to divide one dense design transfer pattern into two transfer patterns to be paired, and two pairs of binary mask blanks manufactured are used to form a pair 2 Two transfer masks (transfer mask sets) each having one transfer pattern were produced.
As described above, two transfer masks were produced from the mask blank of Example 6 to produce a transfer mask set compatible with the double exposure technique.

Evaluation When the transfer pattern is transferred to the resist film on the wafer by double exposure using ArF exposure light using the binary transfer mask set corresponding to the double exposure technology obtained in Examples 1 to 6, exposure is performed 8 times. It was confirmed that the resist film photosensitivity was suppressed to such an extent that the transfer pattern was not affected.
On the other hand, the light shielding film pattern in the transfer pattern region is formed from the light shielding film having the optical density (OD) of 2.8 obtained in the comparative example 1, and the laminated structure of the light shielding film and the etching mask film. Then, when the transfer pattern is transferred to the resist film on the wafer by double exposure with ArF exposure light using a light shielding band outside the transfer pattern area), the resist film is exposed at the portion exposed eight times. Was exposed to light, and it was confirmed that the transfer pattern was affected. That is, the optical density is insufficient in an etching mask having a film thickness that is considered only as a mask for transferring a transfer pattern to the light shielding film 10 (from the viewpoint of the role of the etching mask, the pattern on the light shielding film 10 by dry etching is insufficient. It is clear that a thinner film thickness is preferable in a range that functions as a mask until the transfer is completed, which is contrary to securing optical density.

When the transfer pattern is transferred to the resist film on the wafer by double exposure with ArF exposure light using the binary transfer mask set corresponding to the double exposure technology obtained in Examples 1 to 6, it corresponds to the transfer pattern region. It was confirmed that the resist film exposure was suppressed to the extent that the transfer pattern was not affected in the portion exposed twice.
Further, since the thickness of the light shielding film in the transfer pattern region can be reduced, the accuracy of the light shielding film pattern in the transfer pattern region can be improved as compared with Comparative Example 2.
Furthermore, as the film thickness of the light shielding film increases, the bias due to the electromagnetic field (EMF) effect increases, and as the film thickness increases, a complicated simulation is required, thereby avoiding the problem that a large load is applied. .
In contrast, the binary photomask set obtained in Comparative Example 2 (in the case where the film thickness of the light shielding film is simply increased to correspond to the double exposure technique, from the light shielding film having an optical density (OD) of 3.3), The transfer pattern area is transferred to the resist film on the wafer by double exposure with ArF exposure light using a light shielding film pattern in the transfer pattern area and a light shielding band outside the transfer pattern area). Although the resist film exposure can be suppressed to the extent that the exposure of the resist film does not affect the transfer pattern in the portion exposed twice and the portion exposed eight times outside the transfer pattern region, Since the thickness of the light shielding film is increased, it was confirmed that the accuracy of the light shielding film pattern in the transfer pattern region was lowered.
Further, as the film thickness of the light shielding film increases, the bias due to the electromagnetic field (EMF) effect increases, and as the film thickness increases, a complicated simulation is required. In comparison, it was confirmed that there is a problem that a great load is applied.

  As mentioned above, although this invention was demonstrated using embodiment and an Example, the technical scope of this invention is not limited to the range as described in the said embodiment and Example. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments and examples. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Translucent substrate 10 Light shielding film 11 Light shielding layer 12 Front surface antireflection layer 13 Back surface antireflection layer 20 Auxiliary light shielding film 21 Etching mask film 22 Auxiliary light shielding film 100 Resist film 110 Resist film

Claims (20)

A mask blank used for producing a binary transfer mask to which ArF exposure light is applied,
On a transparent substrate, from the substrate side, comprising: a light film shielding, the auxiliary light-shielding film in this order,
The light shielding film has a laminated structure of a light shielding layer and a surface antireflection layer,
The light shielding film is for forming a transfer pattern,
The auxiliary light shielding film is for forming a light shielding band pattern, and for forming a light shielding band in a laminated structure with the light shielding film,
The optical density of the light shielding film is 2.5 or more and 3.1 or less, and the optical density of the auxiliary light shielding film is 0.5 or more and 1.5 or less .
A mask blank characterized by that.   The mask blank according to claim 1, wherein the mask blank is used for producing a transfer mask to which a double exposure technique is applied. The auxiliary shielding film is used when etching the light shielding film, the mask blank according to claim 1 or 2, characterized in that it has an etch selectivity with respect to etching medium. The said light shielding film is a film | membrane which has a transition metal and a silicon as a main component, and the said auxiliary | assistant light shielding film is a film | membrane which has chromium as a main component, The any one of Claim 1 to 3 characterized by the above-mentioned. The mask blank described. The said light shielding film is a film | membrane which has chromium as a main component, The said auxiliary | assistant light shielding film is a film | membrane which has a transition metal and a silicon as a main component, The any one of Claim 1 to 3 characterized by the above-mentioned. Mask blank. The light shielding film is a film composed mainly of tantalum, the auxiliary light-shielding film is a film mainly containing chromium mask according to any one of claims 1 to 3, characterized in that blank. Between the auxiliary light-shielding film and the light-shielding film, according to claim 1 or 2, characterized in that provision of the etching mask layer having an etch selectivity with respect to etching medium used in etching these films Mask blank. 8. The mask blank according to claim 7 , wherein both the light shielding film and the auxiliary light shielding film are films mainly composed of a transition metal and silicon, and further include an etching mask film mainly composed of chromium. The mask blank according to claim 7 , wherein both the light shielding film and the auxiliary light shielding film are films mainly composed of chromium, and further include an etching mask film mainly composed of transition metal and silicon. The transfer mask produced using the mask blank of any one of Claim 1 to 9 . A binary transfer mask to which ArF exposure light is applied,
In the transfer pattern area on the translucent substrate, has a transfer pattern formed of a light shielding film,
Outside the region of the transfer pattern region, from the substrate side, it has a light-shielding band formed in laminated structure of the auxiliary light-shielding film having a light-shielding band pattern and the light shielding film,
The light shielding film has a laminated structure of a light shielding layer and a surface antireflection layer,
The optical density of the light shielding film is 2.5 or more and 3.1 or less, and the optical density of the auxiliary light shielding film is 0.5 or more and 1.5 or less .
A transfer mask characterized by that. The transfer mask according to claim 11 , wherein a double exposure technique is applied. The transfer mask according to claim 11 , wherein the auxiliary light shielding film has etching selectivity with respect to an etching medium used when the light shielding film is etched. The light shielding film is a film composed mainly of a transition metal and silicon, wherein the auxiliary light-shielding film is a film mainly composed of chromium, that any one of claims 11 13, wherein The transfer mask as described. The said light shielding film is a film | membrane which has chromium as a main component, The said auxiliary | assistant light shielding film is a film | membrane which has a transition metal and a silicon as a main component, The any one of Claim 11 to 13 characterized by the above-mentioned. Transfer mask. The light shielding film is a film composed mainly of tantalum, the auxiliary light-shielding film is a film mainly composed of chromium, that transfer according to any one of claims 11, wherein 13 Mask. Between the auxiliary light-shielding film and the light-shielding film, according to claim 11 or 12, characterized in that provision of the etching mask layer having an etch selectivity with respect to etching medium used in etching these films Transfer mask. 18. The transfer mask according to claim 17 , wherein both the light shielding film and the auxiliary light shielding film are films mainly composed of transition metal and silicon, and further include an etching mask film mainly composed of chromium. 18. The transfer mask according to claim 17 , wherein both the light shielding film and the auxiliary light shielding film are films mainly composed of chromium, and further include an etching mask film mainly composed of transition metal and silicon. A transfer mask set comprising a set of two transfer masks according to any one of claims 12 to 19 ,
The two transfer masks are used for transfer exposure by a double exposure technique,
Each transfer pattern formed on the two transfer masks is obtained by dividing one transfer pattern to be transferred and exposed onto a transfer object into two sparse transfer patterns. .

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