JP2018146760A - Method for manufacturing transfer mask and method for manufacturing semiconductor device - Google Patents

Abstract

A transfer mask manufacturing method and a semiconductor device manufacturing method capable of forming a complicated fine line pattern are provided. A mask blank having a thin film on which a resist film for electron beam exposure is provided; a step of exposing and developing the resist film to form a transfer pattern on the resist film; depositing the first material film on the thin film in a state of burying the first material film; leaving the first material film between the resist films, forming a reverse pattern in the first material film, and removing the resist film; forming a film in a state of embedding the second material film on the material and the thin film; leaving the second material film between the first material films, forming a transfer pattern on the second material film, and dry etching the first material; A method of manufacturing a transfer mask, comprising the steps of: removing the film; and dry-etching the thin film using the second material film having the transfer pattern formed thereon as a mask to form the transfer pattern on the thin film. [Selection figure] None

Description

  The present invention relates to a method for manufacturing a transfer mask and a method for manufacturing a semiconductor device.

  In the manufacturing process of semiconductor devices, a resist pattern is formed on a substrate by lithography, and a processing technique for forming a fine pattern in the etched layer is performed by etching the underlying etched layer using this resist pattern as a mask. It is. In such a processing technique, pattern miniaturization is achieved by thinning a resist pattern, but there is a limit to thinning a resist pattern used as an etching mask.

  Therefore, after forming a planarization film covering the resist pattern, the planarization film on the resist pattern is etched back and removed, and then the resist pattern is removed, whereby an inverted pattern of the resist pattern is formed on the etched layer. A method of forming and using this inverted pattern as an etching mask has been proposed (see Patent Document 1 below).

  Furthermore, using the reverse pattern as a mask, the lower transfer layer is etched to form a reverse pattern of a laminated structure, and a second reverse layer is formed covering this reverse pattern, and the reverse pattern is further inverted in the same manner as described above. A method of forming a pattern that matches the resist pattern and using it as an etching mask has been proposed (see Patent Document 2 below).

JP-A-5-267253 JP 2008-290316 A

  The processing technique described above is also applied to the formation of a thin film pattern on a transfer mask. In recent years, the miniaturization of patterns formed on semiconductor devices has been remarkable, and illumination systems used in lithography have become more complex, and thin film patterns formed on transfer masks have increased line widths and complex patterns. Yes. For this reason, in the method proposed in Patent Document 1 described above, it is necessary to form a resist pattern with a narrow opening width, but it is extremely difficult to form such a resist pattern. On the other hand, in the method proposed in Patent Document 2 described above, since the resist pattern is inverted twice, such a problem does not occur. In the method proposed in Patent Document 2, a transfer layer is provided between an etching target layer and a resist pattern, and a reverse pattern is formed on the transfer layer by dry etching using the reverse resist pattern as a mask. However, etching when forming a pattern in the transfer layer by dry etching not only proceeds in the thickness direction of the transfer layer, but also proceeds in the direction of the side wall of the pattern formed in the transfer layer. For this reason, it is difficult to avoid the etching bias of the reverse pattern formed in the transfer layer, and the dimensional accuracy of the pattern tends to deteriorate.

  Accordingly, an object of the present invention is to provide a method for manufacturing a transfer mask and a method for manufacturing a semiconductor device capable of forming a complicated fine line pattern with good dimensional accuracy.

<Configuration 1>
A method for manufacturing a transfer mask using a mask blank having a thin film on a main surface of a substrate,
Preparing a mask blank provided with a resist film for electron beam exposure on the thin film;
Performing an exposure process and a development process on the resist film, and forming a transfer pattern to be formed on the thin film on the resist film;
Forming a first material film on the resist film and the thin film in a state where the resist film on which the transfer pattern is formed is embedded;
By removing the first material film until the upper surface of the resist film is exposed with the first material film remaining between the resist films on which the transfer pattern is formed, the film is inverted with respect to the transfer pattern. Forming a reverse pattern on the first material film, and then removing the resist film selectively with respect to the first material film;
Forming a second material film made of a material different from the first material film on the first material film and the thin film in a state of embedding the first material film in which the reverse pattern is formed;
By removing the second material film until the upper surface of the first material film is exposed while leaving the second material film between the first material films on which the reverse pattern is formed, the second material film is removed. Forming the transfer pattern on a material film, and then removing the first material film selectively with respect to the second material film by dry etching;
A method for manufacturing a transfer mask, comprising: using the second material film on which the transfer pattern is formed as a mask, and performing dry etching on the thin film to form a transfer pattern on the thin film.

<Configuration 2>
The method for manufacturing a transfer mask according to Configuration 1, wherein the first material film and the second material film are both made of a material having etching selectivity with respect to the thin film.

<Configuration 3>
The ratio of the etching rate of the second material film to the etching rate of the first material film when the first material film is selectively removed from the second material film by the dry etching is 1: 2 or more. A method for manufacturing a transfer mask according to Configuration 1 or 2, wherein the method is provided.

<Configuration 4>
The method for manufacturing a transfer mask according to any one of configurations 1 to 3, wherein the thin film is formed by a sputtering method.

<Configuration 5>
The method for manufacturing a transfer mask according to any one of configurations 1 to 4, wherein the thin film is made of a material containing chromium.

<Configuration 6>
Both the first material film and the second material film are made of a material containing silicon. The method for manufacturing a transfer mask according to any one of the structures 1 to 5, wherein:

<Configuration 7>
The mask blank is provided with a light shielding film between the substrate and the thin film,
Using the thin film on which the transfer pattern is formed as a mask, dry etching the light shielding film, and forming a transfer pattern on the light shielding film;
And a step of removing the thin film after forming a transfer pattern on the light-shielding film. The method for manufacturing a transfer mask according to any one of the configurations 1 to 6.

<Configuration 8>
The mask blank is provided with a light semi-transmissive film between the substrate and the thin film,
Using the thin film on which the transfer pattern is formed as a mask, performing dry etching on the light semi-transmissive film to form a transfer pattern on the light semi-transmissive film and removing the second material film;
After removing the second material film, a resist pattern including a light-shielding band pattern is formed on the thin film, dry etching is performed on the thin film using the resist pattern as a mask, and a pattern including a light-shielding band is formed on the thin film. The method for manufacturing a transfer mask according to any one of configurations 1 to 6, further comprising: a forming step.

<Configuration 9>
A method for manufacturing a semiconductor device, comprising: a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to Configuration 7 or 8.

  According to the present invention having the above-described configuration, it is possible to obtain a transfer mask manufacturing method and a semiconductor device manufacturing method capable of forming a complex thin line pattern with good dimensional accuracy.

FIG. 6 is a cross-sectional process diagram (part 1) illustrating the method for manufacturing the transfer mask according to the first embodiment. FIG. 6 is a sectional process view (No. 2) for explaining the method of manufacturing the transfer mask according to the first embodiment. FIG. 6 is a sectional process view (No. 3) for explaining the method of manufacturing the transfer mask according to the first embodiment. It is sectional process drawing (the 1) explaining the manufacturing method of the transfer mask which concerns on 2nd Embodiment. It is sectional process drawing (the 2) explaining the manufacturing method of the transfer mask which concerns on 2nd Embodiment. It is sectional drawing (the 3) explaining the manufacturing method of the transfer mask which concerns on 2nd Embodiment.

  The inventors form a pattern obtained by inverting the resist pattern twice using the first material film and the second material film resistant to the removal of the first material film, and use this as an etching mask. Thus, it has been found that a fine line pattern with good dimensional accuracy can be formed. Hereinafter, the detailed configuration of the present invention for obtaining such an effect will be described in the order of a transfer mask manufacturing method and then a semiconductor device manufacturing method.

First Embodiment: Method for Manufacturing Transfer Mask >>
1 to 3 are cross-sectional process diagrams illustrating a method for manufacturing a transfer mask according to the first embodiment. The transfer mask manufacturing method of the first embodiment described with reference to these drawings is a method applied when manufacturing a binary mask or a reflective mask as a transfer mask. Hereinafter, the manufacturing method of the transfer mask according to the first embodiment will be described with reference to FIGS.

<Preparation of mask blank 1>
First, as shown in FIG. 1A, a mask blank 1 in which a light shielding film (absorber film) 13, a thin film 15, and a resist film 21 are provided in this order on one main surface of a substrate 11 is prepared. Details of each component are as follows.

[Substrate 11]
The substrate 11 is selected from a material containing silicon. For example, in the case of a mask blank substrate 11 for a binary mask, for example, it may be made of a material that is transmissive to exposure light such as ArF excimer laser light (wavelength: about 193 nm). Synthetic quartz glass is used as such a material, but glass materials such as aluminosilicate glass and soda lime glass can also be used. In particular, a synthetic quartz glass substrate can be suitably used as the substrate 11 because it has high transparency in an ArF excimer laser beam or a shorter wavelength region.

In particular, if the substrate 11 is a mask blank for a reflective mask, it is configured using low thermal expansion glass (SiO ₂ —TiO ₂ glass or the like) in which thermal expansion due to heat generation during exposure is suppressed to a low level. .

  The substrate 11 as described above has a main surface having a rectangular shape including, for example, a square, the peripheral end surface and the main surface are polished to a predetermined surface roughness, and then subjected to a predetermined cleaning process and a drying process. Is.

  Note that the exposure light and exposure time in lithography referred to here are exposure light and exposure time in lithography using a transfer mask prepared using a mask blank. As this exposure light, any of ArF excimer laser light (wavelength: 193 nm), KrF excimer laser light (wavelength: 248 nm), and i-line light (wavelength: 365 nm) can be applied. When the transfer mask is a reflective mask, EUV light (wavelength: 13.56 nm) is applied as the exposure light.

[Light-shielding film (absorber film) 13]
The light-shielding film (absorber film) 13 is a film on which a fine pattern is formed by etching using a thin film described below as a mask. This light-shielding film (absorber film) 13 is a single-layer or multi-layer film formed using a material corresponding to the type of mask blank.

(Light shielding film 13 for binary mask)
The light shielding film 13 for a binary mask has a known composition as long as it has a light shielding performance (optical density higher than a predetermined value) for exposure light used for exposure transfer of a mask pattern when used as a binary mask. Can be configured. Specifically, it may be made of a material containing a transition metal alone or a compound thereof such as chromium, tantalum, ruthenium, tungsten, titanium, hafnium, molybdenum, nickel, vanadium, zirconium, niobium, palladium, rhodium. For example, it may be composed of chromium or a chromium compound in which one or more elements selected from elements such as oxygen, nitrogen, and carbon are added to chromium, and tantalum is selected from elements such as oxygen, nitrogen, and boron. You may comprise with the tantalum compound which added the 1 or more types of element.

  The light shielding film 13 for binary mask may be made of a material containing a compound of transition metal and silicon (including transition metal silicide, particularly molybdenum silicide). In this case, the light shielding film is made of a material containing a compound of a transition metal and silicon, and examples thereof include a material mainly composed of a transition metal and silicon and oxygen and / or nitrogen. Further, the light shielding film 13 may be composed of a transition metal and a material mainly composed of oxygen, nitrogen and / or boron. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium, or the like is applicable.

  The light shielding film 13 for the binary mask may be made of a material containing silicon and nitrogen, or a material containing one or more elements selected from a metalloid element and a nonmetallic element in a material made of silicon and nitrogen. This light shielding film may contain any metalloid element in addition to silicon. Examples of the metalloid element include boron, silicon, germanium, arsenic, antimony and tellurium. The light shielding film 13 may contain any nonmetallic element in addition to nitrogen. This nonmetallic element means a substance containing a nonmetallic element (nitrogen, carbon, oxygen, phosphorus, sulfur, selenium) in a narrow sense, a halogen, and a noble gas. Among these nonmetallic elements, it is preferable to include one or more elements selected from carbon, fluorine and hydrogen.

  The light shielding film 13 for the binary mask made of the material as described above is preferably a film having an antireflection function, and may have a two-layer or three-layer structure. As an example, a light-shielding film 13 having a two-layer structure in which a layer (MoSiN) composed of molybdenum (Mo), silicon (Si), and nitrogen (N) is stacked as a lower layer 13a and an upper layer 13b having different compositions. Is exemplified. Further, the light shielding film 13 is exemplified by a composition gradient film configured such that the composition in the film thickness direction varies continuously or stepwise. The light shielding film 13 as described above can be formed by sputtering, for example.

  The film thickness of the light shielding film 13 for binary mask is not particularly limited, and may be determined so that, for example, the optical density (OD: Optical Density) is 2.5 or more with respect to the exposure light.

(Absorber film 13 for reflective mask)
The absorber film 13 for the reflective mask is a film provided on a multilayer reflective film (not shown here) and has a function of absorbing EUV light. For the reflective mask absorber film 13, for example, tantalum (Ta) alone or a material containing tantalum as a main component (tantalum-based material) can be preferably used. The crystalline state of the absorber film 13 for such a reflective mask preferably has an amorphous or microcrystalline structure from the viewpoint of smoothness and flatness.

  Note that the multilayer reflective film provided below the reflective mask absorber film 13 and between the reflective mask absorber film 13 and the substrate 11 is a film having a function of reflecting EUV light. is there. Such a light reflecting film is, for example, a multilayer reflecting film. The multilayer reflective film is formed by alternately laminating high refractive index layers and low refractive index layers. As the multilayer reflective film, a Mo / Si periodic multilayer film in which Mo films and Si films are alternately stacked for about 40 periods, Ru / Si periodic multilayer film, Mo / Be periodic multilayer film, Mo compound / Si compound periodic multilayer film, Si / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo / Ru / Mo periodic multilayer film, Si / Ru / Mo / Ru periodic multilayer film, etc. are exemplified, and the material is appropriately selected according to the wavelength of exposure light. You can choose. The light shielding film 13 and the light reflecting film for the reflective mask as described above can be formed by, for example, sputtering.

[Thin film 15]
The thin film 15 functions as an etching mask film when the light shielding film 13 is etched. Such a thin film 15 is made of a material having etching resistance to an etchant used when etching the light shielding film (absorber film) 13. When the light shielding film 13 is composed of a silicon-based material or a transition metal silicide-based material and is patterned by dry etching with a fluorine-based gas, the thin film 15 is made of chromium, which is a material highly resistant to these dry etching, It is preferable to use a material made of a chromium compound in which elements such as oxygen, nitrogen, and carbon are added to chromium. Further, when the light shielding film 13 is made of a chromium-based material and is patterned by dry etching using a mixed gas of chlorine-based gas and oxygen gas, the thin film 15 is made of silicon or elements such as oxygen, nitrogen, carbon, etc. on silicon. It is preferable to use a material composed of an added silicon compound.

  On the other hand, the absorber film 13 for the reflective mask is formed of a tantalum-based material. Such an absorber film 13 may be formed by dry etching using a fluorine-based gas or a chlorine-based gas containing no oxygen (oxygen-free chlorine). Patterning is performed by dry etching using a system gas). In this case, the thin film 15 is preferably composed of chromium, which is a material having high resistance to dry etching, or a material made of a chromium compound in which elements such as oxygen, nitrogen, and carbon are added to chromium. Note that the thin film 15 may further have an antireflection function, so that a transfer mask in which the thin film 15 remains on the light shielding film 13 may be manufactured.

  Further, such a thin film 15 is formed by a sputtering method, whereby the edge roughness when the thin film 15 is subjected to pattern etching can be suppressed to be small, and a film capable of obtaining a pattern with a favorable sidewall shape. It has become.

[Resist film 21]
The resist film 21 is an organic material film that is patterned by lithography, and the patterned resist pattern serves as an etching mask when the thin film 15 is etched. Such a resist film 21 may be a positive type or a negative type as long as a fine resist pattern can be formed. However, as an example, a fine pattern of about several tens of nanometers can be formed. A positive chemically amplified resist for electron beam exposure is used.

  A well-known thing can be used as a chemically amplified resist, For example, the thing containing a base polymer and a photo-acid generator is illustrated. A base polymer will not be specifically limited if it is a polymer which the solubility with respect to a developing solution (alkali aqueous solution etc.) increases with generation | occurrence | production of an acid. The photoacid generator is not particularly limited as long as it is a known one. In addition to the above components, the chemically amplified resist may contain other components such as a surfactant, a sensitizer, a light absorber, an antioxidant, and a basic substance as necessary.

  The resist film 21 preferably has a slower dissolution rate of the non-dissolved portion after the exposure processing with respect to the developer used in the development processing, and is 0.05 nm / second or less and 0.03 nm / second or less. Preferably, it is 0.01 nm / second or less. As a result, a fine pattern that prevents thinning of the resist pattern and reduction in film thickness is formed as designed, and resolution is also ensured.

  In this transfer mask manufacturing method, it is difficult to make the thickness (height) of the pattern of the second material film to be formed later larger than the thickness of the resist film 21. For this reason, the resist film 21 is required to have a thickness equal to or larger than a thickness at which the transfer pattern of the second material film sufficiently functions as an etching mask for the thin film 15 below the second material film.

  Such a resist film 21 is formed by, for example, forming a resist material film by a coating method such as a spin coating method, a subsequent drying process, and a baking process performed as necessary.

<Formation of resist pattern 21a>
Next, as shown in FIG. 1B, a transfer pattern to be formed on the thin film 15 is formed on the resist film 21 by performing an exposure process and a subsequent development process on the resist film 21 of the mask blank 1. As a result, a resist pattern 21a in which the resist film 21 is patterned in the shape of the transfer pattern is obtained.

  Here, first, a transfer pattern to be formed on the thin film 15 is drawn on the resist film 21 by exposure drawing using an electron beam. Next, the resist film 21 is subjected to PEB processing, development processing, rinsing processing, and spin drying processing. Thereby, the resist film 21 is patterned to form a resist pattern 21a. At this time, if the resist film 21 is composed of a positive resist, the exposed portion irradiated with the electron beam is removed by the developer, and only the unexposed portion remains as the resist pattern 21a. On the other hand, if the resist film 21 is made of a negative resist, only the exposed portion irradiated with the electron beam remains as the resist pattern 21a.

<Deposition of the first material film 23>
Next, as shown in FIG. 1C, a first material film 23 is formed on the resist pattern 21a and the thin film 15 in a state where a resist film 21 (hereinafter referred to as a resist pattern 21a) on which a transfer pattern is formed is embedded. Film. It is assumed that the first material film 23 is made of a material that has high resistance to processing when removing the resist pattern 21a and has high etching selectivity with respect to the thin film 15.

  For example, when the resist pattern 21a is based on a polymer material and the thin film 15 is configured using a chromium compound, the first material film 23 is configured using a material containing silicon. Specific examples of the first material film 23 include (1) an amorphous silicon film formed by a plasma CVD method, and (2) an atomic layer deposition method (ALD method). A silicon dioxide film is exemplified.

  Further, the first material film 23 to be formed here is formed in a state of being embedded between the patterns of the resist pattern 21a, and is formed with a film thickness that is at least thicker than the height of the resist pattern 21a. To do.

<Formation of Inversion Pattern 23a>
Next, as shown in FIG. 1D, with the first material film 23 left between the resist patterns 21a, the first material film 23 is reduced from the surface side until the upper surface of the resist pattern 21a is exposed. Then, the first material film 23 on the resist pattern 21a is removed. Such removal of the first material film 23 may be performed by dry etching, or may be performed by chemical mechanical polishing or wet etching. From the viewpoint of controllability of the etching rate, it is preferable to carry out by dry etching.

  As described above, an inverted pattern 23 a obtained by inverting the resist pattern 21 a formed as a transfer pattern is formed on the first material film 23.

<Removal of resist pattern 21a>
Thereafter, as shown in FIG. 1E, the resist pattern 21a is selectively removed from the first material film 23 on which the inversion pattern 23a is formed. As a result, only the first material film 23 in which the reverse pattern 23 a is formed is left on the thin film 15, and the thin film 15 is exposed between the first material films 23.

  The removal of the resist pattern 21a is performed by ashing the resist pattern 21a by, for example, a dry process using ozone or plasma. The resist pattern 21a may be removed by performing a wet process using ozone water after the ashing process by such a dry process.

<Deposition of Second Material Film 25>
Next, as shown in FIG. 2A, the first material film 23 on which the inversion pattern 23a is formed is embedded, and the first material film 23 and the thin film 15 are made of a material different from the first material film 23. A second material film 25 is formed. The second material film 25 has high resistance to etching for removing the first material film 23 to be performed in the subsequent steps, and the ratio of the etching rates is the second material film 25: first material film 23. = 1: 2 or more, preferably composed of a material that can be 1: 4 or more. Further, the second material film 25 is made of a material having high etching selectivity with respect to the thin film 15.

  For example, when the thin film 15 is made of a chromium compound and the first material film 23 constituting the reversal pattern 23a is an amorphous silicon film formed by (1) plasma CVD, the second material film 25 is used. As an example, a silicon dioxide film formed by the ALD method is exemplified. Further, when the thin film 15 is made of a chromium compound and the first material film 23 constituting the reversal pattern 23a is a silicon dioxide film formed by (2) ALD, the second material film 25 is a plasma. An amorphous carbon film formed by a CVD method, that is, a diamond like carbon (DLC) film is exemplified.

  In addition, the second material film 25 formed here is formed in a state of being embedded between the patterns of the first material film 23 on which the inversion pattern 23a is formed, and is thicker than at least the inversion pattern 23a. It will be formed by.

<Formation of Transfer Pattern 25a>
Next, as shown in FIG. 2B, the second material film 25 is left between the first material films 23 on which the inversion pattern 23a is formed, and the first material film 23 is exposed until the upper surface is exposed. The two-material film 25 is reduced from the surface side, and the second material film 25 on the first material film 23 is removed. Such removal of the second material film 25 may be performed by dry etching, or may be performed by chemical mechanical polishing or wet etching. From the viewpoint of controllability of the etching rate, it is preferable to carry out by dry etching.

  As described above, the transfer pattern 25a obtained by further inverting the inverting pattern 23a is formed on the second material film 25.

<Removal of the first material film 23>
Thereafter, as shown in FIG. 2C, the first material film 23 on which the reverse pattern 23a is formed is selectively removed from the second material film 25 on which the transfer pattern 25a is formed. Thus, only the second material film 25 having the transfer pattern 25 a formed thereon is formed on the thin film 15, and the thin film 15 is exposed between the second material films 25.

At this time, as described above, the first material film 23 is an amorphous silicon film and the second material film 25 is a silicon dioxide film, and the first material film 23 is a silicon dioxide film and the second material film 25. Are amorphous carbon films (DLC), dry etching using a mixed gas of sulfur hexafluoride (SF ₆ ) and helium (He) as an etching gas is performed. Thereby, the ratio of the etching rate between the second material film 25 and the first material film 23 is set to the second material film 25: the first material film 23 = 1: 2 or more, and the first material film with respect to the second material film 25 is set. 23 selective removals can be performed.

<Patterning of thin film 15>
Next, as shown in FIG. 2D, the thin film 15 is etched using the second material film 25 on which the transfer pattern 25a is formed as a mask to form a transfer pattern 15a on the thin film 15, and the transfer pattern 15a made of the thin film 15 is formed. Get. Here, for example, the chromium-based thin film 15 is etched using the silicon-based second material film 25 on which the transfer pattern 25a is formed as a mask. At this time, dry etching is performed using a mixed gas of chlorine-based gas and oxygen gas (oxygen-containing chlorine-based gas) as an etching gas. As a result, the chromium-based thin film 15 can be etched with extremely high etching selectivity with respect to the silicon-based second material film 25, and the shape of the transfer pattern 25a of the second material film 25 is transferred with high accuracy. A transfer pattern 15a is formed.

<Patterning of light shielding film (absorber film) 13>
Thereafter, as shown in FIG. 3A, the light-shielding film (absorber film) 13 is dry-etched using the transfer pattern 15a formed of the thin film 15 made of a chromium-based material as a mask. Thereby, a light shielding pattern (absorber pattern) 13aa obtained by patterning the light shielding film (absorber film) 13 in the shape of the transfer pattern 15a is obtained. At this time, if the light shielding film 13 is for a binary mask and is made of a material containing silicon, the light shielding film 13 is dry-etched using a fluorine-based gas. Further, in the case of the absorber film 13 for the reflective mask, if the absorber film 13 is formed of a material mainly composed of tantalum, a fluorine-based gas or a chlorine-based gas not containing oxygen is used. Dry etching using (oxygen-free chlorine-based gas) is performed on the absorber film 13.

  In the dry etching of the light shielding film (absorber film) 13 as described above, the silicon-based second material film 25 is also removed at the same time.

<Removal of thin film 15>
Next, as shown in FIG. 3B, the transfer pattern 15a made of the thin film 15 made of a chromium-based material is removed to obtain a transfer mask 1a. At this time, to remove the transfer pattern 15a made of a chromium-based material, a mixed gas of chlorine-based gas and oxygen gas (oxygen-containing chlorine-based gas) is used as an etching gas. Accordingly, the chromium-based material thin film 15 can be removed by etching with extremely high etching selectivity with respect to the silicon-based or tantalum-based light-shielding film 13.

  If the transfer mask 1a thus obtained is a binary mask, a light shielding pattern 13aa that shields the exposure light is provided on the substrate 11 that is transparent to the exposure light. If the transfer mask 1a is a reflective mask, it is exposed to exposure light via a multilayer reflective film (not shown) on a substrate 11 whose thermal expansion due to EUV light as exposure light is kept low. An absorber pattern 13aa that absorbs certain EUV light is provided.

<< Second Embodiment: Method for Manufacturing Transfer Mask >>
4 to 6 are cross-sectional process diagrams illustrating a method for manufacturing a transfer mask according to the second embodiment. The transfer mask manufacturing method according to the second embodiment described with reference to these drawings is a method applied when manufacturing a halftone phase shift mask as a transfer mask. Hereinafter, a method for manufacturing a transfer mask according to the second embodiment will be described with reference to FIGS. 4 to 6, the same components as those described with reference to FIGS. 1 to 3 are denoted by the same reference numerals, and redundant description is omitted.

<Preparation of mask blank 2>
First, as shown in FIG. 4A, a mask blank 2 in which a light semi-transmissive film 43, a thin film 45, and a resist film 21 are provided in this order on one main surface of a substrate 11 is prepared. Of these elements constituting the mask blank 2, the substrate 11 may be the same as that of the mask blank 1 for binary mask of the first embodiment described above. The resist film 21 is the same as that of the first embodiment described above. Therefore, here, the configuration of the light semi-transmissive film 43 and the thin film 45 will be described.

[Light translucent film 43]
The light semi-transmissive film (phase shift film) 43 transmits the exposure light with an intensity that does not substantially contribute to exposure (for example, the transmittance with respect to the exposure light is 1% to 30%). It has a function of causing a predetermined phase difference (for example, 150 to 200 degrees) between the transmitted exposure light and the exposure light transmitted through the air by the same distance as the film thickness of the light semi-transmissive film 43. If it does, what is necessary is just to be comprised with a well-known composition. Specifically, it is made of a material containing a compound of a transition metal and silicon (including a transition metal silicide), and a material mainly composed of these transition metal and silicon and oxygen and / or nitrogen is exemplified. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium, and the like are applicable. The light semi-transmissive film 43 as described above can be formed, for example, by sputtering.

  Further, the light semi-transmissive film 43 may be made of the above-described material made of silicon and nitrogen, or a material containing one or more elements selected from a semi-metal element and a non-metal element in a material made of silicon and nitrogen. .

[Thin film 45]
The thin film 45 is a film used as a light shielding film, and is a material film containing chromium, for example. Such a thin film 45 may be formed as a single layer, may be formed into a two-layer structure of a lower layer 45a and an upper layer 45b as shown, or may be formed into a plurality of layers. Good. When the thin film 45 used as the light shielding film is formed as a plurality of layers, each layer in which the chromium (Cr) content is changed is formed.

  Such a thin film 45 is formed by, for example, a sputtering method, whereby the edge roughness when the thin film 45 is subjected to pattern etching can be suppressed to be small, and a film having a favorable sidewall shape can be obtained. It has become.

  The thin film 45 used as the light shielding film may contain a material containing one or more elements selected from oxygen, nitrogen, carbon, boron, hydrogen and fluorine in addition to chromium metal. Furthermore, the thin film 45 is selected from indium (In), tin (Sn), and molybdenum (Mo) for the purpose of suppressing the decrease in the etching rate of the entire film while maintaining the optical density (OD). It may contain at least one or more metal elements (metal elements such as indium).

  The thin film 45 used as such a light shielding film can be patterned by dry etching using an oxygen-containing chlorine-based gas. The thin film 45 has sufficient etching selectivity with the light semi-transmissive film 43 formed of a material containing silicon (Si), and hardly damages the light semi-transmissive film 43. The thin film 45 can be removed by etching.

<Formation of Resist Pattern 21a to Removal of First Material Film 23>
Next, the steps shown in FIGS. 4B to 5C are performed in the same manner as the steps described with reference to FIGS. 1B to 2C in the first embodiment.

  That is, a resist pattern 21a is formed as shown in FIG. Next, as shown in FIG. 4C, a first material film 23 is formed. Thereafter, as shown in FIG. 4D, an inversion pattern 23 a is formed in the first material film 23. Next, as shown in FIG. 4E, by removing the resist pattern 21a, only the first material film 23 in which the reverse pattern 23a is formed on the thin film 45 is left. Thereafter, as shown in FIG. 5A, the second material film 25 is formed, and then, as shown in FIG. 5B, a transfer pattern 25a is formed on the second material film 25. Next, as shown in FIG. 5C, the second material in which the transfer pattern 25 a is formed on the thin film 45 by selectively removing the first material film 23 from the second material film 25. Only the film 25 is formed.

<Patterning of thin film 45>
After the above, as shown in FIG. 5D, the thin film 45 is etched using the second material film 25 on which the transfer pattern 25a is formed as a mask to form the transfer pattern 45aa on the thin film 45. Here, the chromium-based material thin film 45 is etched using, for example, the silicon-based second material film 25 on which the transfer pattern 25a is formed as a mask. At this time, dry etching is performed using a mixed gas of chlorine-based gas and oxygen gas (oxygen-containing chlorine-based gas) as an etching gas. Thereby, the chromium-based thin film 45 can be etched with extremely high etching selectivity with respect to the silicon-based second material film 25, and the shape of the transfer pattern 25 a of the second material film 25 is compared with the thin film 45. Transferred with good accuracy.

<Patterning of light semi-transmissive film 43>
Next, as shown in FIG. 6A, using the thin film 45 on which the transfer pattern 45aa is formed as a mask, the light-semitransmissive film 43 using a fluorine-based gas is dry-etched to be formed of a material containing silicon. The light semi-transmissive film 43 is patterned. Thereby, the light semi-transmissive pattern 43a formed by patterning the light semi-transmissive film 43 is formed in the light semi-transmissive pattern forming region 11a of the substrate 11. In addition, a hole-shaped alignment mark pattern 43 b that penetrates the thin film 45 and the light semitransmissive film 43 is formed in the outer peripheral region 11 b of the substrate 11. In the dry etching of the light semitransmissive film 43 formed of such a material containing silicon, the second material film 25 made of the material containing silicon is also removed at the same time.

<Formation of resist pattern 47 including light-shielding band pattern>
Next, as shown in FIG. 6B, a resist pattern 47 including a light shielding band pattern is formed on the thin film 45 on which the transfer pattern 45aa is formed. Here, a resist pattern 47 having a shape including a light shielding band pattern covering the outer peripheral region 11b of the substrate 11 is formed. At this time, a resist film is first formed on the substrate 11 by a spin coating method. Next, the resist film is exposed so that the resist film remains in a shape covering the outer peripheral region 11b of the substrate 11, and then a predetermined process such as a development process is performed on the resist film. Thus, a resist pattern 47 including a light shielding band pattern is formed in a shape covering the outer peripheral region 11b of the substrate 11.

<Formation of light shielding pattern>
Next, as shown in FIG. 6C, with the resist pattern 47 including the light shielding band pattern as a mask, the thin film 45 is dry-etched, and a light shielding pattern 45c is formed by patterning the thin film 45 into a band shape covering the outer peripheral region 11b. Form. At this time, the chromium-based material thin film 45 is etched by using a mixed gas of a chlorine-based gas and an oxygen gas as an etching gas.

<Removal of resist pattern 47>
Next, as shown in FIG. 6D, the resist pattern 47 including the light shielding band pattern is removed, and a predetermined process such as cleaning is performed. As described above, a halftone phase shift mask is obtained as the transfer mask 2a.

  In the transfer mask 2a thus obtained, the light semi-transmissive pattern 43a is provided in the light semi-transmissive pattern forming region 11a of the substrate 11, and the alignment mark pattern 43b and the light semi-transmissive film 43 are provided in the outer peripheral region 11b of the substrate 11. A light shielding pattern 45c is provided via

≪Semiconductor device manufacturing method≫
The semiconductor device manufacturing method according to the embodiment uses the transfer mask 1a or transfer mask 2a manufactured by the transfer mask manufacturing method described above, and exposes and transfers the transfer pattern to the resist film on the substrate. It is characterized by doing. The manufacturing method of such a semiconductor device is performed as follows.

  First, a substrate for forming a semiconductor device is prepared. This substrate may be, for example, a semiconductor substrate, a substrate having a semiconductor thin film, or a substrate on which a finely processed film is formed. A resist film is formed on the prepared substrate, and pattern exposure using the transfer mask 1a or the transfer mask 2a produced as described above is performed on the resist film. In this pattern exposure, exposure light having a wavelength corresponding to each transfer mask 1a or transfer mask 2a is used.

  Thereafter, the resist film to which the transfer pattern is exposed and transferred is developed to form a resist pattern, and the resist layer is used as a mask to perform etching processing or introduce impurities into the surface layer of the substrate. After the processing is completed, the resist pattern is removed.

  The semiconductor device is completed by repeatedly performing the above processing on the substrate while exchanging the transfer mask, and further performing necessary processing.

<< Effects of Embodiment >>
In the manufacturing method of the transfer mask according to the embodiment described above, the resist pattern 21a having a transfer pattern is formed on the thin film 15 or the thin film 45 to be patterned, and the first material film 23 and the first material film 23 are removed. The resist pattern 21a is inverted twice using the second material film 25 having resistance to the above. As a result, a thin resist pattern 21a is formed, an inverted pattern of the resist pattern 21a is formed on the first material film 23, and a transfer pattern of the resist pattern 21a, which is the inverted pattern, is formed on the second material film 25. The thin film 15 or the thin film 45 can be pattern-etched using this as a mask.

  Therefore, when forming a highly accurate fine line pattern on the thin film 15 or the thin film 45, it is not necessary to form the resist pattern 21a having a narrow opening width, and the resist pattern 21a having a narrow line width may be formed. In addition, the first material film 23 on which the reversal pattern 23a is formed and the second material film 25 on which the transfer pattern 25a is formed may be a single layer, and both the reversal pattern 23a and the transfer pattern 25a have a small etching bias and the pattern dimensions. It is possible to ensure accuracy. As a result, even in the pattern etching of the thin film 15 or the thin film 45 using the second material film 25 on which the transfer pattern 25a is formed as a mask, a pattern with good dimensional accuracy can be obtained.

  Further, by manufacturing a semiconductor device using the transfer mask 1a or the transfer mask 2a manufactured as described above, a semiconductor device having a fine line pattern with high shape accuracy can be obtained.

<< Another Embodiment >>
The transfer mask manufacturing method of the embodiment described above can also be applied to manufacturing an imprint mold from a mask blank provided with a hard mask film (corresponding to the thin film of the present invention) on a substrate. That is, the imprint mold manufacturing method is an imprint mold manufacturing method using a mask blank having a hard mask film on the main surface of a substrate, and a resist film for electron beam exposure is formed on the hard mask film. A step of preparing the provided mask blank, a step of performing exposure processing and development processing on the resist film, and forming a mold pattern to be formed on the hard mask film on the resist film, and a resist film on which the mold pattern is formed The upper surface of the resist film is formed in a state where the first material film is left between the step of forming the first material film on the resist film and the hard mask film in a state where the mold pattern is embedded, and the resist film on which the mold pattern is formed. By removing the first material film until it is exposed, an inverted pattern that is inverted with respect to the mold pattern is formed on the first material film. Then, the step of selectively removing the resist film with respect to the first material film, and the first material film on the first material film and the hard mask film in a state of embedding the first material film on which the reverse pattern is formed Forming a second material film made of a material different from the first material film, and the second material film between the first material film having the reverse pattern formed until the upper surface of the first material film is exposed. A mold pattern is formed on the second material film by removing the two material film, and then the first material film is selectively removed from the second material film by dry etching, and the mold pattern is formed. Using the second material film as a mask, dry etching the hard mask film to form a mold pattern on the hard mask film, and using the hard mask film on which the mold pattern is formed as a mask, Characterized in that it comprises a step of dry etching is carried out to form a mold pattern on the main surface of the substrate with respect.

  According to the imprint mold manufacturing method of this another embodiment, when forming a highly accurate fine line pattern on a hard mask film, it is not necessary to form a resist pattern with a narrow opening width. That's fine. Moreover, the first material film on which the reverse pattern is formed and the second material film on which the mold pattern is formed may be a single layer, and the etching bias is applied to both the reverse pattern of the first material film and the mold pattern of the second material film. It is possible to ensure a small dimensional accuracy of the pattern. As a result, in the dry etching with respect to the hard mask film using the second material film on which the mold pattern is formed as a mask, it is possible to form a mold pattern with good dimensional accuracy on the hard mask film. Further, in dry etching on the main surface of the substrate using the hard mask film on which the mold pattern is formed as a mask, it is possible to form a mold pattern with good dimensional accuracy on the main surface.

≪Manufacture of transfer mask≫
The manufacturing method of the transfer mask of the present invention will be described more specifically with reference to examples. Here, referring to FIGS. 1 to 3, a transfer mask to be a binary mask was manufactured by the following procedure.

  First, referring to FIG. 1A, a light-transmitting substrate made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared as a substrate 11. This translucent substrate has its end face and main surface polished to a predetermined surface roughness or less (root mean square roughness Rq of 0.2 nm or less), and then subjected to a predetermined cleaning process and drying process. is there.

Next, a lower layer (MoSiN film) 13a of a light-shielding film 13 made of molybdenum, silicon, and nitrogen is formed to a thickness of 47 nm in contact with the surface of the translucent substrate (substrate 11), and an upper layer (MoSiN film) 13b. Was formed with a thickness of 4 nm. Specifically, a translucent substrate (substrate 11) is installed in a single wafer DC sputtering apparatus, and a mixed sintered target (Mo: Si = 13: 87 (atom) of molybdenum (Mo) and silicon (Si). The lower layer 13a and the upper layer 13b of the light shielding film 13 were formed by reactive sputtering (DC sputtering) using a mixed gas of argon (Ar) and nitrogen (N ₂ ) as a sputtering gas.

  Next, the light-transmitting substrate (substrate 11) provided with the light-shielding film 13 was subjected to a heat treatment at 450 ° C. for 30 minutes to reduce the film stress of the light-shielding film 13. In addition, the analysis by the X ray photoelectron spectroscopy was performed with respect to the light shielding film 13 which performed the heat processing in the same procedure on another translucent board | substrate (board | substrate 11). As a result, the lower layer 13a of the light shielding film 13 is Mo: Si: N = 9.2: 68.3: 22.5 (atomic% ratio), and the portion of the upper layer 13b near the lower layer 13a is Mo: Si: It was confirmed that N: O = 5.8: 64.4: 27.7: 2.1 (atomic% ratio). Moreover, about the surface layer of the upper layer 13b of the light shielding film 13, nitrogen was 14.4 atomic% and oxygen was 38.3 atomic%. Further, when the optical density of the light shielding film 13 was measured using a spectroscopic ellipsometer, it was 3.0, and it was confirmed that the optical density was sufficient as the light shielding film.

Next, in contact with the surface of the upper layer 13b of the light shielding film 13, a thin film 15 (CrN film) made of chromium and nitrogen was formed to a thickness of 5 nm. Specifically, a translucent substrate (substrate 11) having a light-shielding film 13 after heat treatment is placed in a single-wafer DC sputtering apparatus, a chromium (Cr) target is used, argon (Ar), and nitrogen (N ₂ ). The thin film 15 was formed by reactive sputtering (DC sputtering) using a mixed gas of) as a sputtering gas. As a result of analyzing the thin film 15 formed on another translucent substrate under the same conditions by X-ray photoelectron spectroscopy, it was Cr: N = 72: 28 (atomic% ratio).

  Next, a resist film 21 made of a chemically amplified resist for electron beam drawing (PRL009: manufactured by FUJIFILM Electronics Materials) is formed in a film thickness of 60 nm in contact with the surface of the thin film 15 by a spin coating method. Blank 1 was obtained.

  Next, referring to FIG. 1B, a test pattern was drawn and exposed to the resist film 21 of the produced mask blank 1 using an electron beam. Thereafter, development processing or the like of the resist film 21 was performed to form a resist pattern 21a having a test pattern shape with a line width of 100 nm and a space width of 100 nm.

  Next, referring to FIG. 1C, a first material film 23 made of amorphous silicon was formed to a thickness of 80 nm by plasma CVD in a state where the resist pattern 21a was embedded.

Thereafter, referring to FIG. 1D, the first material film 23 is formed on the surface side until the resist pattern 21a is exposed by dry etching using a mixed gas of sulfur hexafluoride (SF ₆ ) and helium (He). The inversion pattern 23a made of the first material film 23 was formed between the resist patterns 21a.

  Next, referring to FIG. 1E, the resist pattern 21a between the first material films 23 on which the reversal pattern 23a was formed was removed by ashing and subsequent wet process using ozone water.

  Next, referring to FIG. 2A, a second material film 25 made of silicon dioxide was formed to a thickness of 100 nm by the ALD method in a state where the first material film 23 on which the inversion pattern 23a was formed was embedded.

Thereafter, referring to FIG. 2B, the second material film 25 is formed by dry etching using a mixed gas of carbon tetrafluoride (CF ₄ ) and helium (He) until the first material film 23 is exposed. The film was reduced from the surface side, and a transfer pattern 25a made of the second material film 25 was formed between the first material films 23 on which the inversion patterns 23a were formed.

Next, referring to FIG. 2 (C), the second material film 25 made of silicon dioxide is etched by dry etching using a mixed gas of sulfur hexafluoride (SF ₆ ) and helium (He) as an etching gas. Then, the first material film 23 made of amorphous silicon was selectively removed by etching.

Next, referring to FIG. 2D, dry etching of the thin film 15 made of chromium and nitrogen is performed using the second material film 25 made of silicon dioxide as a mask and using a mixed gas of Cl ₂ and O ₂ as an etching gas. It was. As a result, a transfer pattern 15 a obtained by transferring the test pattern was formed on the thin film 15.

Subsequently, referring to FIG. 3A, from the second material film 25, using the transfer pattern 15a as a mask, a mixed gas of sulfur hexafluoride (SF ₆ ) and helium (He) is used as an etching gas, molybdenum, The light shielding film 13 made of silicon and nitrogen was dry etched. Thereby, the light shielding pattern 13aa was formed on the light shielding film 13.

Next, referring to FIG. 3B, the transfer pattern 15a was removed by dry etching using a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ) as an etching gas.

  As described above, a pattern test transfer mask (binary mask) 1a having a light-shielding pattern 13aa having a test pattern shape on a light-transmitting substrate (substrate 11) was produced.

≪Evaluation≫
A simulation of a transfer image when the transfer mask 1a manufactured as described above is exposed and transferred to a resist film for manufacturing a semiconductor device with exposure light having a wavelength of 193 nm using AIMS 193 (manufactured by Carl Zeiss). Went.

  When the exposure transfer image by this simulation was verified, the design specifications were sufficiently satisfied. From this result, even if this transfer mask 1a is set on the mask stage of an exposure apparatus and exposed and transferred to a resist film for manufacturing a semiconductor device, it is confirmed that a circuit pattern for a semiconductor device can be finally formed with high accuracy. It was done.

DESCRIPTION OF SYMBOLS 1, 2 ... Mask blank 1a, 2a ... Transfer mask 11 ... Substrate 13 ... Light-shielding film (absorber film)
15. Thin film (etching mask film)
21: Resist film 21a: Resist pattern (transfer pattern)
DESCRIPTION OF SYMBOLS 23 ... 1st material film 23a ... Inversion pattern 25 ... 2nd material film 25a ... Transfer pattern 43 ... Light semi-transmissive film 45 ... Thin film (light-shielding film)
47. Resist pattern including shading band pattern

Claims (9)

A method for manufacturing a transfer mask using a mask blank having a thin film on a main surface of a substrate,
Preparing a mask blank provided with a resist film for electron beam exposure on the thin film;
Performing an exposure process and a development process on the resist film, and forming a transfer pattern to be formed on the thin film on the resist film;
Forming a first material film on the resist film and the thin film in a state where the resist film on which the transfer pattern is formed is embedded;
By removing the first material film until the upper surface of the resist film is exposed with the first material film remaining between the resist films on which the transfer pattern is formed, the film is inverted with respect to the transfer pattern. Forming a reverse pattern on the first material film, and then removing the resist film selectively with respect to the first material film;
Forming a second material film made of a material different from the first material film on the first material film and the thin film in a state of embedding the first material film in which the reverse pattern is formed;
By removing the second material film until the upper surface of the first material film is exposed while leaving the second material film between the first material films on which the reverse pattern is formed, the second material film is removed. Forming the transfer pattern on a material film, and then removing the first material film selectively with respect to the second material film by dry etching;
A method for manufacturing a transfer mask, comprising: using the second material film on which the transfer pattern is formed as a mask, and performing dry etching on the thin film to form a transfer pattern on the thin film. The method for manufacturing a transfer mask according to claim 1, wherein the first material film and the second material film are both made of a material having etching selectivity with respect to the thin film. The ratio of the etching rate of the second material film to the etching rate of the first material film when the first material film is selectively removed from the second material film by the dry etching is 1: 2 or more. The transfer mask manufacturing method according to claim 1, wherein the transfer mask manufacturing method is provided. The method for manufacturing a transfer mask according to any one of claims 1 to 3, wherein the thin film is formed by a sputtering method. The method for manufacturing a transfer mask according to any one of claims 1 to 4, wherein the thin film is made of a material containing chromium. The method for manufacturing a transfer mask according to any one of claims 1 to 5, wherein the first material film and the second material film are both made of a material containing silicon. The mask blank is provided with a light shielding film between the substrate and the thin film,
Using the thin film on which the transfer pattern is formed as a mask, dry etching the light shielding film, and forming a transfer pattern on the light shielding film;
The method for producing a transfer mask according to claim 1, further comprising: removing the thin film after forming a transfer pattern on the light shielding film. The mask blank is provided with a light semi-transmissive film between the substrate and the thin film,
Using the thin film on which the transfer pattern is formed as a mask, performing dry etching on the light semi-transmissive film to form a transfer pattern on the light semi-transmissive film and removing the second material film;
After removing the second material film, a resist pattern including a light-shielding band pattern is formed on the thin film, dry etching is performed on the thin film using the resist pattern as a mask, and a pattern including a light-shielding band is formed on the thin film. The method for manufacturing a transfer mask according to claim 1, further comprising: a forming step. A method for manufacturing a semiconductor device, comprising: a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to claim 7 or 8.

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