KR20120057612A - Photomask blank, and photomask manufacturing method - Google Patents

Abstract

By increasing the dry etching speed of the light shielding film, the present invention can shorten the dry etching time, reduce the film reduction of the resist film, and reduce the thickness of the resist film to improve resolution and pattern accuracy (CD precision), It is characterized by providing a photomask blank capable of forming a pattern of a light shielding film having a good cross-sectional shape by shortening the dry etching time. The present invention provides a photomask blank having a light shielding film on a light-transmissive substrate, the photomask blank corresponding to a method for producing a photomask in which a light shielding film is patterned by a dry etching process using a mask pattern formed on the light shielding film as a mask. As a photomask blank for dry etching treatment, the light shielding film is mainly made of a material containing chromium (Cr) and nitrogen (N), and the diffraction peak by X-ray diffraction is substantially CrN 200. In addition, the said light shielding film contains nitrogen (N) substantially uniformly in a depth direction, based on chromium (Cr).

Description

Photomask blank and photomask manufacturing method {PHOTOMASK BLANK, AND PHOTOMASK MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a photomask blank and photomask in which a dry etching speed of a light shielding film is optimized for a dry etching process for forming a light shielding film pattern, and a method of manufacturing a semiconductor device.

Generally, in the manufacturing process of a semiconductor device, fine pattern formation is performed using the photolithographic method. In addition, a substrate called a plurality of photomasks is usually used for forming this fine pattern. This photomask generally forms a light-shielding fine pattern made of a metal thin film or the like on a light-transmissive glass substrate, and the photolithography method is also used in the manufacture of this photomask.

The photomask blank which has a light shielding film on translucent board | substrates, such as a glass substrate, is used for manufacture of the photomask by the photolithographic method. The photomask manufacturing using the photomask blank includes an exposure step of performing a desired pattern exposure on a resist film formed on the photomask blank, and a developing step of developing the resist film in accordance with a desired pattern exposure to form a resist pattern; And an etching step of etching the light shielding film along the resist pattern, and a step of peeling and removing the remaining resist pattern. In the above development step, after the desired pattern exposure is performed on the resist film formed on the photomask blank, a developer is supplied to dissolve a portion of the resist film available to the developer to form a resist pattern. In the above etching step, the resist pattern is used as a mask, for example, by wet etching, a portion where the light shielding film on which the resist pattern is not formed is exposed is dissolved, thereby forming a desired mask pattern on the light-transmissive substrate. do. In this way, a photomask is completed.

Patent document 1 describes a photomask blank having a chromium film containing chromium carbide as a light shielding film on a transparent substrate as a mask blank suitable for wet etching. In addition, Patent Document 2 also has a laminated film of a halftone material film and a metal film on a transparent substrate as a mask blank suitable for wet etching in a similar manner, and the metal film has a material having different etching rates from the surface side toward the transparent substrate side. There exists a region which consists of a half-tone phase shift mask blank which consists of a metal film of CrN / CrC and an anti-reflection film of CrON, for example.

By the way, in miniaturizing the pattern of the semiconductor device, in addition to miniaturization of the mask pattern formed on the photomask, shortening of the wavelength of the exposure light source used in photolithography is required. As an exposure light source at the time of semiconductor device manufacture, shortening of the wavelength from KrF excimer laser (wavelength 248 nm) to ArF excimer laser (wavelength 193 nm), and also F2 excimer laser (wavelength 157 nm) is progressing in recent years.

On the other hand, in the photomask and the photomask blank, in miniaturizing the mask pattern formed on the photomask, the resist film in the photomask blank is thinned and a patterning method in the manufacture of the photomask is used instead of the conventional wet etching. Etching processing is required.

However, the thin film of a resist film and the dry etching process generate | occur | produce the technical problem described below.

First, when thinning a resist film of a photomask blank, the processing time of a light shielding film is one big limitation. Generally as a material of a light shielding film, the chromium system material is used and the mixed gas of chlorine gas and oxygen gas is used for the etching gas in the dry etching process of chromium. When patterning a light shielding film by dry etching using a resist pattern as a mask, since the resist is an organic film and its main component is carbon, it is very weak against an oxygen plasma which is a dry etching environment. While patterning the light shielding film by dry etching, the resist pattern formed on the light shielding film must remain at a sufficient film thickness. As one index, in order to improve the cross-sectional shape of the mask pattern, the thickness of the resist film remaining even after performing about twice the just etching time (100% over etching) should be set. For example, since the etching selectivity ratio of chromium which is a material of a light shielding film, and a resist film is 1 or less generally, the film thickness of a resist film requires the film thickness more than twice the film thickness of a light shielding film. As a method of shortening the processing time of a light shielding film, thinning of a light shielding film is considered. Patent document 3 proposes thinning of the light shielding film.

Patent document 3 discloses that in the manufacture of a photomask, the etching time can be shortened by thinning the film thickness of the chromium light shielding film on the transparent substrate, thereby improving the shape of the chromium pattern.

[Patent Document 1] Patent Publication No. 62-32782

[Patent Document 2] Japanese Patent No. 2983020

[Patent Document 3] Japanese Patent Application Laid-Open No. 10-69055

However, if the film thickness of the light shielding film is made thin, the light shielding property is insufficient, so that even if the pattern is transferred using such a photomask, a transfer pattern defect occurs. Since the light shielding film requires a predetermined optical density (for example, 25 or more) in order to sufficiently secure the light shielding property, even if the film thickness of the light shielding film is made thin as in Patent Document 3, a limit naturally occurs.

In addition, when the chromium film containing chromium carbide described in Patent Document 1 is used as the light shielding film, the dry etching rate tends to be lowered, and the processing time of the light shielding film by dry etching cannot be shortened.

Further, in the CrN / CrC metal film having different wet etching rates in the film thickness direction described in Patent Document 2, it was necessary to make the CrC film thicker than the CrN film. The reason for this is as follows. First, both of the upper CrC film and the lower CrN film have a good wet etching rate. However, if nitrogen is contained in the lower layer, there is a problem that the undercut becomes large when the wet etching process is performed. This is because it was necessary to make the thickness relatively thin. Second, in the i-line (365 nm) and KrF excimer laser (248 nm), which are wavelengths used in the conventional exposure apparatus, the absorption coefficient of the CrN film is small, so that a high light-shielding CrC film is thickened to obtain a desired optical density as the light shielding film. Because I needed to. Third, exposure (drawing) for forming a resist pattern on the light shielding film is generally performed by using an electron beam. However, in order to suppress charge-up at that time, it is necessary to make the CrC film relatively thick to reduce the sheet resistance of the light shielding film. However, the mask blank of patent document 2 has a problem that the carbon content rate in the said metal film becomes high, and when the patterning is performed by dry etching, since an etching rate falls, the processing time of a light shielding film cannot be shortened. Moreover, when the mask blank of patent document 2 is used for a dry etching process, since a dry etching rate is initially high toward a depth direction of a light shielding film, it mainly slows in the area | region of a CrC film, and finally, it accelerates again in the area | region of a CrN film, There is a problem that the cross-sectional shape of the pattern is deteriorated or a global loading phenomenon is likely to occur.

Accordingly, the present invention has been made to solve the conventional problems. First, the object of the present invention is to increase the dry etching rate of the light shielding film, thereby reducing the dry etching time, and reducing the film reduction of the resist film. As a result, the photoresist blank and the photomask can be formed by thinning the resist film to improve resolution and pattern accuracy (CD accuracy), and to form a pattern of a light shielding film having a good cross-sectional shape by shortening the dry etching time. It is to provide a manufacturing method. Second, to provide a photomask blank and a photomask manufacturing method capable of forming a pattern of a light shielding film having a good cross-sectional shape by thinning the light shielding film while having the light shielding performance required for the light shielding film. Thirdly, the global loading phenomenon can be reduced by optimizing the dry etching speed in the depth direction of the light shielding film, and a photomask blank and a method of manufacturing the photomask are obtained. Fourth, the present invention provides a method for producing a semiconductor device, in which a satisfactory semiconductor device without a defect in a circuit pattern is obtained by pattern transfer on a semiconductor substrate by a photolithography method using the photomask of the present invention.

In order to solve the said subject, this invention has the following structures.

<Configuration 1>

A photomask blank having a light shielding film on a light-transmissive substrate, wherein the photomask blank is a dry etching corresponding to a method of manufacturing a photomask in which the light shielding film is patterned by a dry etching process using a mask pattern formed on the light shielding film as a mask. It is a photomask blank for processing, The said light shielding film consists mainly of the material containing chromium (Cr) and nitrogen (N), The diffraction peak by X-ray diffraction is substantially CrN (200), It is characterized by the above-mentioned. Photomask blanks.

<Configuration 2>

The said light shielding film is the photomask blank of the structure 1 characterized by the fact that nitrogen (N) is contained substantially uniformly in the depth direction when chromium (Cr) is a reference | standard.

<Configuration 3>

A photomask blank having a light shielding film on a light-transmissive substrate, wherein the photomask blank is a dry etching corresponding to a method of manufacturing a photomask in which the light shielding film is patterned by a dry etching process using a mask pattern formed on the light shielding film as a mask. It is a photomask blank for a process, The said light shielding film is a photomask blank characterized by containing nitrogen (N) substantially uniformly in the depth direction, based on chromium (Cr).

<Configuration 4>

The light shielding film further contains oxygen, and the content of oxygen is reduced from the surface side toward the light transmissive substrate side, which is the photomask blank according to any one of Configurations 1 to 3.

<Configuration 5>

It is a photomask blank in any one of the structures 1-4 characterized by forming the antireflection layer containing oxygen in the upper layer part of the said light shielding film.

<Configuration 6>

A halftone phase shifter film is formed between the translucent substrate and the light shielding film. The photomask blank according to any one of Configurations 1 to 5 characterized by the above-mentioned.

<Configuration 7>

The said light shielding film in the photomask blank in any one of the structures 1-6 is patterned by dry etching, and the light shielding film pattern is formed on the said translucent board | substrate, The manufacturing method of the photomask characterized by the above-mentioned.

<Configuration 8>

After patterning the said light shielding film in the photomask blank of the structure 6 by dry etching, and forming a light shielding film pattern, the said halftone type phase shifter film is patterned by dry etching using the light shielding film pattern as a mask, and is half on the said translucent board | substrate. It is a manufacturing method of the photomask characterized by forming a tone type phase shifter film pattern.

<Configuration 9>

The light shielding film pattern or the halftone phase shifter film pattern in the photomask according to Configuration 7 or 8 is transferred onto a semiconductor substrate by a photolithography method.

As in the configuration 1, the photomask blank of the present invention is a photomask blank having a light shielding film on a light-transmissive substrate, and the photomask blank is formed by dry etching treatment using a mask pattern formed on the light shielding film as a mask. It is a photomask blank for dry etching processes corresponding to the manufacturing method of the photomask which patternes a light shielding film, The said light shielding film consists mainly of the material containing chromium (Cr) and nitrogen (N), and is made by X-ray diffraction The diffraction peak is substantially CrN 200. Here, the fact that the diffraction peak by X-ray diffraction is substantially CrN 200 means that there is one significant diffraction peak, and no diffraction peak corresponding to crystals other than CrN 200 appears.

A light shielding film made mainly of such a material containing chromium (Cr) and nitrogen (N), and whose diffraction peak by X-ray diffraction is substantially CrN (200), has a dry etching rate higher than that of a light shielding film composed of chromium alone. It becomes faster and can shorten a dry etching time. By making the dry etching speed faster, the film thickness of the resist film required for patterning the light shielding film can be made thin, and the pattern precision (CD precision) of the light shielding film is improved. In addition, a light shielding film of a chromium-based material containing such an element has a desired optical density (for example, a thin film) at a certain thickness without increasing the film thickness at an exposure wavelength of 200 nm or less, which is effective in achieving a finer pattern. Preferably at least 2.5). That is, it becomes possible to achieve thinning of a light shielding film, having the light shielding performance required for a light shielding film.

As in the configuration 2, the light shielding film preferably contains nitrogen (N) substantially uniformly in the depth direction when chromium (Cr) is used as a reference. Nitrogen (N) is contained substantially uniformly in the depth direction when the light shielding film is based on chromium (Cr), whereby CrN 200 having a composition substantially uniform in the depth direction of the light shielding film is formed. As a result, the effect of speeding up the dry etching speed according to the configuration 1 is further exerted, and the setting of the etching process for setting the pattern cross section good, ie, vertical, becomes easy. In addition, when the light shielding film is based on chromium (Cr) as a reference, the structure in which nitrogen (N) is contained substantially uniformly in the depth direction is optimal when it is combined with the structure 6 mentioned later. That is, as in the configuration 6, when the light shielding film has a function as a mask layer when patterning a halftone phase shifter film, the cross-sectional shape of the halftone type phase shifter film pattern formed by using the light shielding film pattern as a mask is also good.

As in the configuration 3, the photomask blank of the present invention is a photomask blank having a light shielding film on the light-transmissive substrate, and the photomask blank is subjected to dry etching treatment using a mask pattern formed on the light shielding film as a mask. It is a photomask blank for dry etching processes corresponding to the manufacturing method of the photomask which patterns a light shielding film, The said light shielding film contains nitrogen (N) substantially uniformly in a depth direction, based on chromium (Cr).

By using such a film, the dry etching speed can be made faster than that of the light shielding film made of chromium alone, so that the film thickness of the resist film required for patterning the light shielding film can be made thin, and the pattern precision (CD precision) of the light shielding film is improved. In addition, a light shielding film of a chromium-based material containing such an element has a desired optical density (for example, a thin film) at a certain thickness without increasing the film thickness at an exposure wavelength of 200 nm or less, which is effective in achieving a finer pattern. Preferably at least 2.5). That is, it becomes possible to achieve thinning of a light shielding film, having the light shielding performance required for a light shielding film.

In addition, when the light shielding film has a structure in which nitrogen (N) is substantially uniformly contained in the depth direction when chromium (Cr) is used as a reference, it is easy to set the etching process for achieving a good pattern cross section, that is, vertically. In addition, this structure is optimal when it combines with the structure 6 mentioned later. That is, as in the configuration 6, when the light shielding film has a function as a mask layer when patterning a halftone phase shifter film, the cross-sectional shape of the halftone type phase shifter film pattern formed by using the light shielding film pattern as a mask is also good.

As in the configuration 4, the light shielding film further contains oxygen, and the content of oxygen decreases from the surface side toward the light transmissive substrate side, thereby reducing the depth direction of the light shielding film (that is, the light transmissive substrate side from the surface side of the light shielding film). Can be controlled to slow down the dry etch rate. As a result, the global loading phenomenon can be reduced, and the pattern precision can be improved. As the dry etching rate on the light transmissive substrate side approaches the dry etching rate on the surface side, the CD bias difference due to pattern density, that is, the global loading error increases. Therefore, if the dry etching speed on the light transmissive substrate side is moderately slower than the dry etching speed on the surface side, the global loading error can be reduced and the pattern precision can be improved.

As in the configuration 5, the light shielding film can form an antireflection layer containing oxygen in an upper portion thereof. By forming such an anti-reflection layer, the reflectance at the exposure wavelength can be suppressed to a low reflectance. Therefore, when the mask pattern is transferred to the transfer target body, multiple reflections between the projection exposure surfaces can be suppressed to reduce the deterioration of the imaging characteristics. Can be. Moreover, since the reflectance with respect to the wavelength (for example, 257 nm, 364 nm, 488 nm, etc.) used for defect inspection of a photomask blank and a photomask can be suppressed low, the precision which detects a defect improves.

As in the configuration 6, a halftone phase shifter film may be formed between the light transmissive substrate and the light shielding film.

In that case, the light shielding film may be set so as to have a desired optical density (for example, preferably 2.5 or more) with respect to the exposure light in a laminated structure with the halftone phase shifter film.

As in the structure 7, according to the manufacturing method of the photomask which has the process of patterning the light shielding film in the photomask blank in any one of structures 1-6 using a dry etching process, dry etching time can be shortened. The photomask in which the light shielding film pattern with a favorable cross-sectional shape was formed correctly can be obtained.

As in configuration 8, the light shielding film in the photomask blank according to configuration 6 is patterned by dry etching to form a light shielding film pattern, and then the halftone phase shifter film is subjected to dry etching using the light shielding film pattern as a mask. According to the manufacturing method of the photomask which forms a pattern, the photomask in which the halftone type phase shifter film pattern with favorable cross-sectional shape was formed with high precision can be obtained.

As in the configuration 9, the light shielding film pattern or the halftone phase shifter film pattern in the photomask according to the configuration 7 or 8 is transferred onto the semiconductor substrate by the photolithography method, so that the circuit pattern is formed on the semiconductor substrate. A semiconductor device free of defects can be manufactured.

According to the present invention, by increasing the dry etching speed of the light shielding film, the dry etching time can be shortened and the film reduction of the resist film can be reduced. As a result, the thin film of a resist film becomes possible, and the resolution of a pattern and pattern precision (CD precision) can be improved. Further, by shortening the dry etching time, it is possible to provide a photomask blank and a manufacturing method of a photomask capable of forming a light shielding film pattern having a good cross-sectional shape.

Moreover, according to this invention, the photomask blank and the manufacturing method of a photomask which can form the pattern of a light shielding film with favorable cross-sectional shape can be provided by thinning a light shielding film, having the light shielding performance required for a light shielding film.

Moreover, according to this invention, the global loading phenomenon can be reduced by optimizing the dry etching speed | rate in the depth direction of a light shielding film, and the manufacturing method of the photomask blank and photomask by which favorable pattern precision is obtained can be provided.

In addition, by pattern-transferring a light shielding film pattern or a halftone phase shifter film pattern in a photomask of the present invention onto a semiconductor substrate by a photolithography method, a semiconductor device free of defects in a circuit pattern formed on a semiconductor substrate can be provided. .

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows one Embodiment of the photomask blank obtained by this invention.
2 is a cross-sectional view showing a process for producing a photomask using a photomask blank.
3 is a cross-sectional view showing a photomask blank according to a second embodiment of the present invention and a process for producing a photomask using the photomask blank.
4 is a cross-sectional view of a halftone phase shift mask obtained by the present invention.
FIG. 5 is a diagram showing results obtained by Rutherford backscattering analysis of a light shielding film of Example 1; FIG.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, embodiment of this invention is described in detail.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows 1st Embodiment of the photomask blank obtained by this invention.

The photomask blank 10 of FIG. 1 is in the form of the photomask blank for binary masks which has the light shielding film 2 on the translucent board | substrate 1.

The photomask blank 10 is a mask for dry etching corresponding to a method of manufacturing a photomask in which the light shielding film 2 is patterned by a dry etching process using a resist pattern formed on the light shielding film 2 as a mask. Blank.

Here, as the transparent substrate 1, a glass substrate is common. Since a glass substrate is excellent in flatness and smoothness, when pattern transfer is performed on a semiconductor substrate using a photomask, distortion of a transfer pattern does not occur, and high-precision pattern transfer can be performed.

The light shielding film 2 mainly consists of a material containing chromium (Cr) and nitrogen (N), and the diffraction peak by X-ray diffraction is substantially CrN (200).

Here, the fact that the diffraction peak by X-ray diffraction is substantially CrN (200), as described above, has one significant diffraction peak except for the diffraction peak derived from impurities and the like, and the diffraction derived from the composition of the light shielding film. This means that the peak does not appear other than the diffraction peak corresponding to the crystal of CrN 200.

A light shielding film made mainly of such a material containing chromium (Cr) and nitrogen (N), and whose diffraction peak by X-ray diffraction is substantially CrN (200), has a dry etching rate higher than that of a light shielding film composed of chromium alone. It becomes faster and can shorten a dry etching time. Then, by increasing the dry etching speed, the film thickness of the resist film required for patterning the light shielding film can be made thin, and the pattern precision (CD precision) of the light shielding film is improved.

In the present invention, the light shielding film 2 preferably contains nitrogen (N) substantially uniformly in the depth direction when the chromium (Cr) is used as a reference. When the light shielding film contains nitrogen (N) substantially uniformly in the depth direction when chromium (Cr) is the reference, CrN 200 having a substantially uniform composition is formed in the depth direction of the light shielding film, and Cr (110) ) Component is substantially free. Therefore, the light-shielding film in which nitrogen (N) is contained substantially uniformly in the depth direction when chromium (Cr) is used as a reference has a further effect of speeding up the dry etching rate according to the present invention. Good setting, that is, setting of an etching process (etching conditions and the like) for vertical standing becomes easy.

Here, specifically, the fact that nitrogen (N) is contained substantially uniformly in the depth direction based on chromium (Cr) means that in the region near the surface of the light shielding film and the light shielding film interface on the light-transmitting substrate side, " The state which becomes the average value ± 0.05 "of the ratio of nitrogen (N) when chromium (Cr) is set to 1 is said. Preferably, the average value ± 0.025 of the ratio of nitrogen (N) when chromium (Cr) is 1, more preferably, the average value ± 0.01 of the ratio of nitrogen (N) when chromium (Cr) is 1 It is preferable to set it as.

In the dry etching process, the light shielding film 2 is formed so that the resist film remains at the end of patterning of the light shielding film even if the film reduction of the resist film occurs when patterning by dry etching using the resist pattern formed thereon as a mask. The selectivity of can be made into a material of more than 1. The selectivity is expressed by the ratio of the film reduction amount of the resist and the film reduction amount of the light shielding film (= film reduction amount of the light shielding film / resistance film reduction amount) to the dry etching treatment. Preferably, from the viewpoint of preventing the deterioration of the cross-sectional shape of the light shielding film pattern and suppressing the global loading phenomenon, the light shielding film has a selectivity to the resist of more than 1 but less than 10, more preferably more than 1 but less than 5 It is desirable to.

In addition, such a light shielding film of chromium and nitrogen-containing chromium-based materials has a desired optical density (eg, a thin film) at a certain thickness without increasing the film thickness at an exposure wavelength of 200 nm or less, which is effective in achieving a finer pattern. For example, preferably 2.5 or more). That is, it becomes possible to achieve thinning of a light shielding film, having the light shielding performance required for a light shielding film.

As nitrogen content in the said light shielding film 2, the range of 15-80 atomic% is preferable. When content of nitrogen is less than 15 atomic%, the effect which a dry etching rate becomes faster than a chromium single substance is hard to be acquired. In addition, when the content of nitrogen exceeds 80 atomic%, the absorption coefficient of a wavelength of 200 nm or less, for example, an ArF excimer laser (wavelength 193 nm) becomes small, so that a desired optical density (for example, 2.5 or more) is obtained. In order to increase the thickness it becomes necessary.

In the present invention, the light shielding film 2 may further contain oxygen. In that case, it is preferable that the content of oxygen decrease from the surface side toward the light transmissive substrate side. By decreasing the oxygen content from the surface side of the light shielding film toward the light transmissive substrate side, the dry etching rate can be controlled to be slowed toward the depth direction of the light shielding film (that is, from the surface side of the light shielding film to the light transmissive substrate side). As a result, the global loading phenomenon can be reduced, and the pattern precision can be improved. As the dry etching rate on the light transmissive substrate side approaches the dry etching rate on the surface side, the CD bias difference due to pattern density, that is, the global loading error increases. Therefore, if the dry etching speed on the light transmissive substrate side is moderately slower than the dry etching speed on the surface side, the global loading error can be reduced and the pattern precision can be improved.

As for content of oxygen in the case of containing oxygen in the light shielding film 2, the range of 5-80 atomic% is preferable. When content of oxygen is less than 5 atomic%, the effect of controlling so that a dry etching rate may be slowed toward the depth direction of a light shielding film is hard to be acquired. On the other hand, when the content of oxygen exceeds 80 atomic%, the absorption coefficient of an ArF excimer laser (wavelength 193 nm) having a wavelength of 20 nm or less, for example, becomes small, so that a desired optical density (for example, 2.5 or more) is obtained. In order to achieve this, the film thickness needs to be thickened. Moreover, it is preferable to make content of oxygen in the preferable light shielding film 2 into the range of 10-50 atomic% especially.

In addition, the light shielding film 2 may contain both nitrogen and oxygen. In that case, it is preferable that the sum total of nitrogen and oxygen shall be in the range of 10-80 atomic%. In addition, the content ratio of nitrogen and oxygen at the time of including both nitrogen and oxygen in the light shielding film 2 is not restrict | limited, It is suitably determined by balance, such as an absorption coefficient.

In addition, the light shielding film 2 may contain carbon. When carbon is contained in the light shielding film 2, the content of carbon is preferably in the range of 1 to 20 atomic%. Carbon has the effect of raising conductivity and reducing the reflectance. However, when carbon is contained in the light shielding film, the dry etching rate is lowered, and the dry etching time required for patterning the light shielding film by dry etching becomes long, making it difficult to thin the resist film. From the above point, 1-20 atomic% is preferable, and, as for content of carbon, 3-15 atomic% is more preferable.

Although the formation method of the said light shielding film 2 does not need to restrict | limit in particular, Especially, the sputtering film-forming method is mentioned especially. According to the sputtering film-forming method, since a uniform and constant film thickness can be formed, it is suitable for this invention. When the light shielding film 2 is formed on the light-transmissive substrate 1 by the sputtering film formation method, the sputter gas introduced into the chamber using a chromium (Cr) target as the sputter target is inert such as argon gas or helium gas. A mixture of a gas such as oxygen, nitrogen or carbon dioxide, or nitrogen monoxide is used. When the sputter gas which mixed nitrogen gas with inert gas, such as argon gas, is used, the light shielding film containing chromium and nitrogen can be formed. In addition, by using a sputter gas in which oxygen gas or carbon dioxide gas is mixed with an inert gas such as argon gas, a light shielding film containing oxygen in chromium can be formed, and nitrogen monoxide gas is mixed with an inert gas such as argon gas. By using a sputter gas, a light shielding film containing nitrogen and oxygen in chromium can be formed. In addition, by using a sputter gas in which methane gas is mixed with an inert gas such as argon gas, a light shielding film containing carbon in chromium can be formed.

In the present invention, in all layers constituting the light shielding film, sputtering film formation is carried out in an atmosphere containing nitrogen when the film is formed.

The film thickness of the said light shielding film 2 is set so that optical density may be 2.5 or more with respect to light shielding light. Specifically, the film thickness of the light shielding film 2 is preferably 90 nm or less. The reason for this is that in order to cope with the miniaturization of the pattern to the pattern size of the recent submicron level, when the film thickness exceeds 90 nm, it is difficult to form the fine pattern due to micro loading phenomenon of the pattern during dry etching or the like. This is because the case is considered. By making the film thickness thin to some extent, the aspect ratio of the pattern (the ratio of the pattern depth to the pattern width) can be reduced, and the line width error due to the global loading phenomenon and the micro loading phenomenon can be reduced. In addition, by making the film thickness thin to a certain extent, damage to the pattern (breakdown, etc.) can be prevented, particularly with respect to the pattern of the pattern size of the submicron level. The light shielding film 2 in this invention can obtain desired optical density (for example, 2.5 or more), even if it is a thin film of 90 nm or less in the exposure wavelength of 200 nm or less. The lower limit of the film thickness of the light shielding film 2 can be made thin as long as the desired optical density is obtained.

The light shielding film 2 is not limited to a single layer, and may be a multilayer, but any film preferably contains at least nitrogen. The light shielding film 2 may include an antireflection layer containing oxygen, for example, in the surface layer portion (upper layer portion). In that case, as an antireflection layer, Preferably, materials, such as CrO, CrCO, CrNO, CrCON, are mentioned, for example. By forming the antireflection layer, the reflectance at the exposure wavelength can be suppressed to, for example, 20% or less, preferably 15% or less. Therefore, when the mask pattern is transferred to the transfer object, multiple reflections between the projection exposure surfaces are prevented. It can suppress and the fall of imaging characteristic can be suppressed. In addition, the reflectance with respect to the wavelength (for example, 257 nm, 364 nm, 488 nm, etc.) used for defect inspection of a photomask blank or a photomask, for example, 30% or less is pointed out by the point which detects a defect with high precision. desirable. In particular, a film containing carbon as the antireflection layer is preferable because the reflectance with respect to the exposure wavelength can be reduced and the reflectance with respect to the inspection wavelength (particularly 257 nm) can be made 20% or less. Specifically, the carbon content is preferably 5 to 20 atomic%. When the content of carbon is less than 5 atomic%, the effect of reducing the reflectance is less. Further, when the content of carbon exceeds 20 atomic%, the dry etching rate is lowered, which is necessary when patterning the light shielding film by dry etching. The dry etching time is long, which makes it difficult to thin the resist film, which is not preferable.

In addition, the antireflection layer may be formed on the light transmissive substrate side as necessary.

In addition, the light shielding film 2 has a content of chromium, elements such as nitrogen, oxygen, and carbon, which are different from each other in the depth direction, and is formed stepwise or continuously in an antireflection layer of the surface layer portion and another layer (light shielding layer). You may make it the inclined composition inclined film. In order to make such a light shielding film into a composition gradient film, the method of switching suitably the kind (composition) of the sputter gas at the time of sputtering film formation mentioned above during film-forming, for example is preferable.

In addition, as a photomask blank, the form which formed the resist film 3 on the said light shielding film 2 may be sufficient as it is (a) of FIG. 2 mentioned later. As for the film thickness of the resist film 3, in order to make the pattern precision (CD precision) of a light shielding film favorable, it is preferable that it is as thin as possible. In the case of the so-called binary mask photomask blank like this embodiment, specifically, the film thickness of the resist film 3 is preferably 300 nm or less. More preferably, it is 200 nm or less, More preferably, it is 150 nm or less. The lower limit of the thickness of the resist film is set so that the resist film remains when the light shielding film is dry-etched using the resist pattern as a mask. In addition, in order to obtain high resolution, the material of the resist film 3 is preferably a chemically amplified resist having high resist sensitivity.

Next, the manufacturing method of the photomask using the photomask blank 10 shown in FIG. 1 is demonstrated.

The photomask manufacturing method using the photomask blank 10 has a process of patterning the light shielding film 2 of the photomask blank 10 using dry etching, Specifically, the photomask blank 10 Performing a desired pattern exposure (pattern drawing) on the resist film formed above, developing the resist film to form a resist pattern in accordance with a desired pattern exposure, etching the light shielding film along the resist pattern, And peeling off the remaining resist pattern.

2 is a cross-sectional view sequentially illustrating a manufacturing process of the photomask using the photomask blank 10.

FIG. 2A illustrates a state in which the resist film 3 is formed on the light shielding film 2 of the photomask blank 10 of FIG. 1. Moreover, as a resist material, even if it is a positive resist material or a negative resist material, it can be used.

Next, FIG.2 (b) shows the process of performing desired pattern exposure (pattern drawing) with respect to the resist film 3 formed on the photomask blank 10. Next, FIG. Pattern exposure is performed using an electron beam drawing apparatus etc. As the resist material described above, those having photosensitivity corresponding to electron beams or lasers are used.

Next, FIG. 2C shows a step of forming the resist pattern 3a by developing the resist film 3 in accordance with the desired pattern exposure. In this step, after the desired pattern exposure is performed on the resist film 3 formed on the photomask blank 10, a developer is supplied to dissolve a portion of the resist film available to the developer, thereby forming a resist pattern 3a. .

Next, FIG. 2D shows a step of etching the light shielding film 2 along the resist pattern 3a. Since the photomask blank of this invention is preferable for dry etching, it is preferable to use dry etching for etching. In the etching step, the exposed portion of the light shielding film 2 on which the resist pattern 3a is not formed is removed by dry etching using the resist pattern 3a as a mask, whereby the desired light shielding film pattern ( 2a (mask pattern) is formed on the light transmissive substrate 1.

In this invention, it is preferable to use the dry etching gas which consists of chlorine gas or mixed gas containing a chlorine gas and oxygen gas for this dry etching. With respect to the light shielding film 2 which consists mainly of the material which contains chromium and nitrogen in this invention, by performing dry etching using said dry etching gas, dry etching speed can be improved and shortening of dry etching time is aimed at. It is possible to form a light shielding film pattern having a good cross-sectional shape. As the chlorine-based gas used in the dry etching gas, for example, there may be mentioned _{Cl 2, SiCl 4, HCl,} CCl 2, CHCl 3.

In addition, in the case of the light shielding film which consists of a material which contains oxygen other than chromium and nitrogen, since chloromil chloride is produced | generated by reaction of chromium and chlorine gas with oxygen in a light shielding film, the mixed gas of chlorine gas and oxygen gas for dry etching is carried out. When using the dry etching gas which consists of these, content of oxygen in a dry etching gas can be reduced with content of oxygen contained in a light shielding film. By performing dry etching using the dry etching gas which reduced the amount of oxygen in this way, the amount of oxygen which adversely affects a resist pattern can be reduced, and the damage to the resist pattern at the time of dry etching can be prevented. Therefore, a photomask with improved pattern accuracy of the light shielding film is obtained. In addition, depending on the content of oxygen contained in the light shielding film, it is also possible to use a dry etching gas containing no oxygen in which the amount of oxygen in the dry etching gas is zero.

FIG. 2E shows the photomask 20 obtained by peeling off the remaining resist pattern 3a. In this way, a photomask in which the light shielding film pattern with a good cross-sectional shape is formed precisely is completed.

In addition, this invention is not limited to embodiment described above. That is, it is not limited to the so-called binary mask photomask blank in which the light shielding film was formed on the transparent substrate, for example, may be a photomask blank for use in manufacture of a halftone type phase shift mask. In this case, as shown in 2nd Embodiment mentioned later, a light shielding film is formed on the halftone phase shifter film on a translucent board | substrate, combining a halftone phase shifter film and a light shielding film, and desired optical density (for example, 2.5 or more) ) Can be obtained, the optical density of the light shielding film itself can be set to a value smaller than 2.5, for example.

Next, 2nd Embodiment of the photomask blank of this invention is described using FIG.

The photomask blank 30 of FIG. 3A is a light shielding film 2 composed of a halftone phase shifter film 4, a light shielding layer 5 and an antireflection layer 6 thereon, on a light transmissive substrate 1. ) Is of the form. Since the translucent board | substrate 1 and the light shielding film 2 were demonstrated in the said 1st Embodiment, it abbreviate | omits.

The halftone phase shifter film 4 transmits light having an intensity that does not substantially contribute to exposure (for example, 1% to 40% with respect to the exposure wavelength), and has a predetermined phase difference. The halftone phase shifter film 4 includes a light semitransmissive portion in which the halftone phase shifter film 4 is patterned, and light having an intensity that substantially contributes to exposure in which the halftone phase shifter film 4 is not formed. The light transmitting portion that transmits light transmits the light semi-transmissive portion so that the phase of the light is substantially inverted with respect to the phase of the light passing through the light transmissive portion, thereby passing through the vicinity of the boundary between the light semi-transmissive portion and the light transmitting portion, thereby preventing diffraction phenomenon. By this, the light returned to the mutually opposing area is canceled with each other, and the light intensity at the boundary is almost zero to improve the contrast, that is, the resolution, at the boundary.

It is preferable that this halftone type phase shifter film 4 be made of a material different from the light shielding film 2 formed thereon and etching characteristics. For example, as the halftone phase shifter film 4, materials such as molybdenum, tungsten, tantalum, hafnium, and other metals, silicon, oxygen, and / or nitrogen are the main components. The halftone phase shifter film 4 may be a single layer or a plurality of layers.

The said light shielding film 2 in this 2nd Embodiment is set so that optical density may be 2.5 or more with respect to exposure light in the laminated structure which combined the halftone type phase shift film and the light shielding film. It is preferable that the film thickness of the light shielding film 2 set as such is 50 nm or less. This is because, as in the first embodiment, the case where the formation of the fine pattern becomes difficult due to the micro loading phenomenon of the pattern during dry etching or the like is considered. By setting the film thickness of the light shielding film to 50 nm or less, the line width error due to the global loading phenomenon and the micro loading phenomenon during dry etching can be further reduced. In the present embodiment, the film thickness of the resist film formed on the antireflection layer 6 is preferably 250 nm or less. More preferably, it is 200 nm or less, More preferably, it is 150 nm or less. The lower limit of the thickness of the resist film is set so that the resist film remains when the light shielding film is dry-etched using the resist pattern as a mask. In addition, as in the case of the embodiment described above, in order to obtain high resolution, the material of the resist film is preferably a chemically amplified resist having high resist sensitivity.

Hereinafter, embodiment of this invention is described further more concretely by an Example. In addition, the comparative example with respect to an Example is also demonstrated.

&Lt; Example 1 >

The photomask blank of this embodiment consists of a light shielding film 2 which consists of a light shielding layer and an antireflection layer on the light transmissive substrate 1.

This photomask blank can be manufactured by the following method.

By using a sputtering apparatus, a chromium target is used as the sputter target, and a mixture of argon gas, nitrogen gas and helium gas (Ar: 30% by volume, N ₂ : 30% by volume, He: 40% by volume) is reactive in an atmosphere. Sputtering to form a light shielding layer on the light-transmissive substrate 1, and then a mixed gas of argon gas, nitrogen gas, methane gas, and helium gas (Ar: 54% by volume, N ₂ : 10% by volume, CH ₄ : 6). Volume%, He: 30% by volume) reactive sputtering in an atmosphere, followed by reactive sputtering in a mixed gas of argon gas and nitrogen monoxide gas (Ar: 90% by volume, NO: 10% by volume) , An antireflection layer was formed, and a light shielding film 2 was formed on the transparent substrate 1 made of synthetic quartz glass. Further, the power of the sputtering device at the time of forming the light shielding layer was 1.16 kPa, the total gas pressure was 0.17 pascal (Pa), the power of the sputtering device at the time of film formation of the antireflection layer was 0.33 kPa, and the total gas pressure was 0.28 pascal (Pa). A light shielding film was formed. The film thickness of the light shielding film was 67 nm. The composition of the light shielding film was analyzed by Rutherford backscattering analysis. As a result, chromium (Cr) containing 33.0 atomic% of nitrogen (N), 12.3 atomic% of oxygen (O), and 5.9 atomic% of hydrogen (H) It was. Moreover, as a result of composition analysis by Auger electron spectroscopy, 8.0 atomic% of carbon (C) was contained in the said light shielding film.

FIG. 5 is a diagram showing a composition analysis result in a depth direction of a light shielding film by Rutherford backscattering analysis of the light shielding film of this embodiment. FIG. However, the vertical axis | shaft of FIG. 5 is shown by the composition ratio of each element at the time of making chromium one.

According to this result, the light shielding layer of the light shielding film became a composition gradient film in which the oxygen and carbon used for formation of chromium, nitrogen, and an antireflection layer were mixed. In addition, the antireflection layer became a composition gradient film in which chromium, nitrogen, oxygen and carbon were slightly mixed. In addition, the content of oxygen in the light shielding film is high in the antireflection layer on the surface side, and the content is decreasing in the depth direction as a whole. Moreover, about hydrogen in a light shielding film, content in the antireflection layer on the surface side is high, and as a whole, content of hydrogen is decreasing substantially toward the depth direction of a light shielding film. In particular, the characteristic point is that nitrogen is uniformly contained in the depth direction of the light shielding film based on chromium.

Further, when the light shielding film of this embodiment was analyzed by X-ray diffraction, it was found that one diffraction peak was detected at the position of diffraction angle 2θ of 44.081 deg, and the light shielding film of this embodiment was found to be mainly a CrN 200 film. It became.

The optical density of this light shielding film was 3.0. Moreover, the reflectance in the exposure wavelength of 193 nm of this light shielding film was 14.8%, and it could be suppressed low. Moreover, about 257 nm or 364 nm which is a defect inspection wavelength of a photomask, it was 19.9% and 19.7%, respectively, and it was a reflectance which does not become a problem also in an inspection.

Next, on the said photomask blank, the resist film for electron beam drawing which is a chemically amplified type resist (FEP171 made by Fujifilm Electronics) was formed. Formation of the resist film was rotationally apply | coated using the spinner (rotary coating apparatus). Furthermore, after apply | coating the said resist film, the predetermined heat drying process was performed using the heat drying apparatus.

Next, the resist pattern formed on the photomask blank was subjected to a desired pattern drawing (80 nm line and space pattern) using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern.

Next, along the resist pattern, the dry etching process of the light shielding film 2 which consists of a light shielding layer and an antireflection layer was performed, and the light shielding film pattern 2a was formed. As a dry etching gas, a mixed gas of chlorine (Cl ₂ ) gas and oxygen (O ₂ ) gas (Cl ₂ : O ₂ = 4: 1) was used. At this time, the etching rate of the entire light shielding film was 3.8 Pa / sec. The etching rate in the depth direction of the light shielding film tended to have a high etching rate on the surface side of the light shielding film and a slow translucent substrate side.

In the present embodiment, since the light shielding film 2 mainly consists of a material containing chromium and nitrogen, and is mainly a film containing CrN 200, the etching rate of the light shielding film 2 as a whole can be increased. In addition, the global anti-loading error is practical by containing a large amount of oxygen mainly in the antireflection layer in the light shielding film 2 and decreasing the oxygen content in the depth direction, and by slowing the dry etching rate in the depth direction of the light shielding film. The figures have entered acceptable levels. Thus, since the light shielding film 2 has a thin film thickness and a fast etching speed and fast etching time, the cross-sectional shape of the light shielding film pattern 2a also became a vertical shape, and it became favorable. In addition, a resist film remained on the light shielding film pattern 2a.

Finally, the remaining resist pattern was peeled off to obtain a photomask. As a result, the photomask in which the light shielding film pattern of 80 nm of line and space was formed on the translucent board | substrate was produced.

<Example 2>

3 is a cross-sectional view showing a photomask blank according to the present embodiment and a manufacturing process of a photomask using the photomask blank. As shown in Fig. 3A, the photomask blank 30 of the present embodiment includes a halftone phase shifter film 4, a light shielding layer 5, and an antireflection layer on the light-transmissive substrate 1. It consists of the light shielding film 2 which consists of (6).

This photomask blank 30 can be manufactured by the following method.

On a translucent substrate made of synthetic quartz glass, argon (Ar) using a sheet-type sputtering device, and using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 8: 92 mol%) as a sputter target. ArF composed of a single layer composed of molybdenum, silicon, and nitrogen as a main component by reactive sputtering (DC sputtering) in a mixed gas atmosphere (Ar: N ₂ = 10% by volume: 90% by volume) of nitrogen and N ₂ . A halftone phase shifter film for an excimer laser (wavelength 193 nm) was formed with a film thickness of 69 nm. The halftone phase shifter film is an ArF excimer laser (wavelength: 193 nm), the transmittance is 55%, and the phase shift amount is approximately 180 degrees.

Next, on the halftone phase shifter film, a light shielding film composed of a light shielding layer having a total film thickness of 48 nm and an antireflection layer was formed in the same manner as in Example 1.

Next, on the said photomask blank 30, the resist film for electron beam drawing which is a chemically amplified type resist (FEP 171 material made from FUJIFILM Materials: film thickness: 200 nm) was formed. Formation of the resist film was rotationally apply | coated using the spinner (rotary coating apparatus). Furthermore, after apply | coating the said resist film, the predetermined heat drying process was performed using the heat drying apparatus.

Next, the resist film formed on the photomask blank 30 is subjected to a desired pattern drawing (70 nm line and space pattern) using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern 7 ) (See FIG. 3B).

Next, along the resist pattern 7, the dry shielding of the light shielding film 2 which consists of the light shielding layer 5 and the anti-reflective layer 6 was performed, and the light shielding film pattern 2a was formed (refer FIG.3 (c)). ).

Next, the halftone phase shifter film 4 was etched using the light shielding film pattern 2a and the resist pattern 7 described above as a mask to form a halftone phase shifter film pattern 4a (Fig. d)). In the etching of the halftone phase shifter film 4, the cross-sectional shape of the light shielding film pattern 2a affects the cross-sectional shape of the light shielding film pattern 2a, so that the halftone phase shifter film pattern 4a Cross-sectional shape also became favorable.

Next, after peeling off the resist pattern 7 remaining, the resist film 8 is apply | coated again, the pattern exposure for removing the unnecessary light shielding film pattern in a transcription | transfer area | region is performed, the resist film 8 is developed, and the resist The pattern 8a was formed (refer FIG. 3 (e), (f)). Next, unnecessary light shielding film patterns were removed using wet etching, and the remaining resist patterns were peeled off to obtain a photomask 40 (see FIG. 3 (g)).

As a result, the photomask in which the half-tone phase shifter film pattern of 70 nm line and space was formed on the translucent board | substrate was produced. In addition, global loading errors have reached acceptable levels in practice.

In the example shown in FIG. 3G, a light shielding film is formed on the phase shifter film in a peripheral region which is a region other than the transfer region (mask pattern formation region). This light shielding film prevents the peripheral region from passing through the exposure light. That is, although a phase shift mask is used as a mask of a reduction projection exposure apparatus (stepper), when performing pattern transfer using this reduction projection exposure apparatus, it is phased by the coating member (apache) with which the exposure apparatus was equipped. Exposure is performed by covering the peripheral region so as to expose only the transfer region of the shift mask. However, it is difficult to provide this covering member so as to expose only the transfer region with high accuracy, and in most cases, the exposed portion is protruded into the non-transfer region around the outer periphery of the transfer region. Usually, a light shielding film is formed in the non-transfer area | region of a mask in order to block this deviated exposure light. In the case of the halftone type phase shift mask, the phase shifter film has a light shielding function, but the phase shifter film does not completely block the exposure light, but a slight amount of the amount that cannot substantially contribute to the exposure depending on one exposure. The exposure light passes through the exposure light. Therefore, as the light exits during the repetitive step, the exposure light passing through the phase shifter film reaches the area where the pattern exposure has already been made and overlaps, or when it is another shot, the light exits similarly. There is a case where the exposure is superimposed on a portion where a slight exposure occurs. By this overlapping exposure, they may add up to reach an amount contributing to the exposure, and a defect may occur. The light shielding film formed on the phase shifter film in the peripheral region other than the mask pattern forming region solves this problem. In addition, when adding identification code etc. to the peripheral area of a mask, when a light shielding film exists, it will become easy to recognize an appended code etc.

<Example 3>

On the light-transmissive substrate made of the same synthetic quartz glass as in Example 1, a mixed target (Ta: Hf = 90: 10at%) of tantalum (Ta) and hafnium (Hf) was used as the sputter target using a sheet-type sputtering device. In a argon (Ar) gas atmosphere, a TaHf film having a film thickness of 75 kPa is formed by DC magnetron sputtering, and then reactive sputtering in a mixed gas atmosphere of argon, oxygen, and nitrogen using a Si target. And a SiON film (Si: O: N = 40: 27: 33at%) having a film thickness of 740 kPa was formed. That is, a halftone phase shifter film for an ArF excimer laser (wavelength 193 nm) composed of two layers having a TaHf film as a lower layer and a SiON film as an upper layer was formed. The halftone phase shifter film is placed with an ArF excimer laser (wavelength of 193 nm), has a high transmittance of 15.0%, and a phase shift amount of approximately 180 °.

Next, on the halftone phase shifter film, a light shielding film composed of a light shielding layer having a total film thickness of 48 nm and an antireflection layer was formed in the same manner as in Example 2.

A halftone phase shift mask was produced in the same manner as in Example 2 using the photomask blank for the halftone phase shift mask thus obtained. However, in this embodiment, as shown in Fig. 4, the boundary portion of the light transmitting portion (the portion of the transparent substrate exposed without the mask pattern being formed) in the mask pattern is removed without removing the light shielding film pattern in the transfer region. The light shielding film was formed in the excepting part.

As a result, the photomask in which the half-tone phase shifter film pattern of 70 nm line and space was formed on the translucent board | substrate was produced. In addition, global loading errors have reached acceptable levels in practice.

The halftone phase shift mask shown in Fig. 4 has a boundary portion with a light transmissive portion (a portion where the mask pattern is not formed and the transparent substrate is exposed) in the mask pattern in the region where the mask pattern of the phase shifter film is formed. By forming the light shielding film in the excluded portion, the original light shielding of the portion that is preferably completely shielded is made more complete. That is, in the area where the mask pattern is formed, the function originally required for the phase shifter film as the mask pattern is to pass the light shifted in phase only by the boundary with the light transmitting portion, and most of the other (parts except the boundary). It is because it is preferable to shield completely completely. As in the present embodiment, when the phase shifter film having a high transmittance with respect to the exposure light is provided, the form of the photomask of this embodiment is particularly preferable.

<Example 4>

A photomask blank and a photomask were produced in the same manner as in Example 2 except that the light shielding film 2 formed on the halftone phase shifter film 4 in Example 2 was formed by sputtering under the following conditions. The light shielding film on the halftone phase shifter film is a mixed gas of argon gas, nitrogen gas, and helium gas (Ar: 15 vol%, N ₂ : 30 vol%, using a chromium target as the sputter target using a sputtering apparatus). He: 55% by volume) After forming reactive shielding in an atmosphere to form a light shielding layer, a mixed gas of argon gas, nitrogen gas, methane gas, and helium gas (Ar: 54% by volume, N ₂ : 10% by volume, CH ₄₎ : 6 vol%, He: 30 vol) Reactive sputtering is performed in an atmosphere, followed by reactive sputtering in a mixed gas (Ar: 90 vol%, NO: 10 vol%) atmosphere of argon gas and nitrogen monoxide gas. Thus, an antireflection layer was formed to obtain a light shielding film. In addition, the power and total gas pressure of the sputtering apparatus at the time of film-forming of the light shielding layer and the reflection prevention layer were performed on the conditions similar to Example 1, and the film thickness of the light shielding film was 48 nm.

Composition analysis of the light shielding film's depth direction by Rutherford backscattering analysis of the present Example showed that nitrogen when chromium was used as the reference (ie, 1) was uniformly contained in the light shielding film's depth direction. .

Furthermore, when the light shielding film of this Example was analyzed by X-ray diffraction, it was a film whose weak diffraction peak intensity was not so high in crystallinity.

A halftone phase shift mask was produced in the same manner as in Example 2 using the photomask blank for halftone phase shift mask thus obtained.

As a result, the photomask in which the half-tone phase shifter film pattern of 70 nm line and space was formed on the translucent board | substrate was produced. In addition, global loading errors have reached acceptable levels in practice.

Comparative Example

A chromium target is used as the sputtering target, reactive sputtering is performed in an atmosphere of a mixed gas of argon gas and nitrogen gas (Ar: 70% by volume, N ₂ : 30% by volume) to form a light shielding layer on the transparent substrate 1, Thereafter, reactive sputtering is performed in a mixed gas (Ar: 90 vol%, CH ₄ : 10 vol%) atmosphere of argon gas and methane gas, and then a mixed gas (Ar: 90 vol) of argon gas and nitrogen monoxide gas. %, NO: 10 vol%) By performing reactive sputtering in an atmosphere, an antireflection layer was formed, and a light shielding film 2 was formed on the light transmissive substrate 1 made of synthetic quartz glass. In addition, the power of the sputtering device at the time of forming the light shielding layer was 0.33 kPa, the total gas pressure was 0.28 pascal (Pa), the power of the sputtering device at the time of film formation of the antireflection layer was 0.33 kPa, and the total gas pressure was 0.28 pascal (Pa). Formed. The film thickness of the light shielding film was 70 nm.

When the light shielding film of this comparative example was analyzed by X-ray diffraction, two diffraction peaks having a diffraction angle of 2θ of 43.993deg and 45.273deg were detected. It turned out to be a act.

Furthermore, when the composition analysis result of the light-shielding film depth direction by the Rutherford backscattering analysis of the light-shielding film of this comparative example was carried out, nitrogen was not contained uniformly in the depth direction of the light-shielding film based on chromium, Especially in a light-shielding layer It was found that nitrogen was reduced in the depth direction.

Next, on the said photomask blank, the resist film for electron beam drawing which is a chemically amplified type resist (FEP171 made by Fujifilm Electronics) was formed. Formation of the resist film was rotationally apply | coated using the spinner (rotary coating apparatus). Furthermore, after apply | coating the said resist film, the predetermined heat drying process was performed using the heat drying apparatus.

Next, the resist pattern formed on the photomask blank was subjected to desired pattern drawing (80 nm line and space pattern) using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern.

Next, along the said resist pattern, the dry etching process of the light shielding film 2 which consists of a light shielding film layer and an antireflection layer was performed, and the light shielding film pattern 2a was formed. As a dry etching gas, a mixed gas of chlorine (Cl ₂ ) gas and oxygen (O ₂ ) gas (Cl ₂ : O ₂ = 4: 1) was used. At this time, the etching rate of the entire light shielding film was 2.4 s / sec. The etching rate in the depth direction of the light shielding film was the same on the surface side of the light shielding film and the light transmissive substrate side.

In this comparative example, since the dry etching speed in the light shielding film 2 was slow, the dry etching time of the light shielding film 2 was long and the light shielding film pattern with favorable cross-sectional shape was not obtained. In addition, since the dry etching time was long, it was necessary to form the resist film thickly, and therefore, good resolution and pattern precision could not be obtained. In addition, since the dry etching speed became substantially constant toward the depth direction of the light shielding film, the global loading error became large, and the global loading error did not enter a practically acceptable value.

<Method for Manufacturing Semiconductor Device>

When the photomasks obtained in Examples 1 to 4 were set in the exposure apparatus, and the pattern transfer was performed on the resist film on the semiconductor substrate, and the semiconductor device was fabricated, there was no defect in the circuit pattern formed on the semiconductor substrate. Could get

1: translucent substrate
2: shading film
3: resist film
4: halftone phase shifter film
5: shading layer
6: antireflection layer
2a: pattern of light shielding film
3a: resist pattern
10, 30: photomask blank
20, 40: photomask

Claims (4)

A photomask blank having a laminated film set on a light-transmissive substrate such that the optical density is 2.5 or more with respect to the exposure light,
The photomask blank is a photomask blank for dry etching processing corresponding to a photomask manufacturing method for patterning the laminated film by dry etching using a mask pattern formed on the laminated film as a mask,
The laminated film is made of a layer made of a material containing at least one of metal, silicon, oxygen, and nitrogen from the light-transmissive substrate side, and mainly made of a material containing chromium (Cr) and nitrogen (N), and further, X-rays A photomask blank, wherein the diffraction peak due to diffraction has a layer substantially composed of CrN (200). The method of claim 1,
The layer mainly made of a material containing chromium (Cr) and nitrogen (N) contains nitrogen (N) substantially uniformly in the depth direction when chromium (Cr) is used as a reference. . The method according to claim 1 or 2,
The photomask blank, wherein the layer mainly made of a material containing chromium (Cr) and nitrogen (N) further contains oxygen, and the content of oxygen is reduced from the surface side toward the light transmissive substrate side. The pattern mainly consisting of the material containing chromium (Cr) and nitrogen (N) in the photomask blank of Claim 1 or 2 is patterned by dry etching, and the pattern mainly consisting of the material containing chromium and nitrogen is formed. And forming a layer made of a material containing at least one of the metal, silicon, oxygen, and nitrogen by dry etching, after forming the mask as a mask.

Images