JP6944255B2 - Manufacturing method of transfer mask and manufacturing method of semiconductor device - Google Patents

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 and transfer masks for manufacturing semiconductor devices, a resist pattern is formed using an organic or inorganic resist material, and a lower layer pattern etching using the resist pattern as a mask is performed. There is.

When an organic resist material is used, the patterned photoresist, for example, a typical acrylic ArF photoresist (organic resist material), is subjected to ion implantation, EB curing, UV curing, high temperature baking, or the like. Has proposed the introduction of a process for shrinking photoresists. It is said that the introduction of such a process also has the effect of improving the etching resistance of the patterned photoresist (see Patent Document 1 below).

When an inorganic resist material is used, the latent image of the radiation pattern is transferred to a coating material coated with an aqueous solution of an inorganic material (inorganic resist material) capable of forming a pattern, and then the coating material is brought into contact with the developer composition. A process has been proposed in which a patterned structure is formed by removing the non-irradiated coating material, and the coating material is further heat-treated to condense the material. In such a process, it is said that the resolution is improved by thinning the pattern, that is, the pattern is miniaturized, as compared with the case where the organic resist is used (see Patent Document 2 below).

Japanese Unexamined Patent Publication No. 2004-103999 Japanese Unexamined Patent Publication No. 2011-253185

However, even with the resist patterns obtained by any of the above processes, the etching resistance in the pattern etching of the base layer using these resist patterns as a mask is still insufficient, and the pin is formed on the base layer after the pattern etching. Holes were sometimes formed.

Therefore, the present invention provides a method for manufacturing a transfer mask and a semiconductor device, which can pattern-etch the lower layer without damage by using an inorganic resist pattern having good etching resistance as a mask, thereby forming a fine transfer pattern. It is an object of the present invention to provide the manufacturing method of.

<Structure 1>
A method for manufacturing a transfer mask using a mask blank having a thin film on the main surface of a substrate.
A step of forming an inorganic resist film on the thin film and
A step of drawing and exposing a transfer pattern on the inorganic resist film using an electron beam and then performing a development process to form a transfer pattern on the inorganic resist film.
The step of irradiating the inorganic resist film after the transfer pattern is formed with an electron beam, and
A method for producing a transfer mask, which comprises a step of using an inorganic resist film after being irradiated with an electron beam as a mask, performing dry etching on the thin film, and forming a transfer pattern on the thin film.

<Structure 2>
In the step of forming the inorganic resist film, an aqueous solution containing a metal suboxide cation, a polyatomic inorganic anion, and a peroxide-based ligant is applied onto the thin film to form a liquid film, and then the liquid film is formed. The method for producing a transfer mask according to Configuration 1, wherein an inorganic resist film is formed by drying the mixture.

<Structure 3>
The method for producing a transfer mask according to Constituent 2, wherein the metal suboxide cation is a polyatomic cation having an oxygen atom covalently bonded to hafnium.

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

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

<Structure 6>
In the step of irradiating the inorganic resist film with the electron beam after the transfer pattern is formed, any one of configurations 1 to 5 is characterized in that the electron beam is irradiated with an acceleration voltage lower than that of the drawing exposure. The method for manufacturing a transfer mask according to the description.

<Structure 7>
The method for manufacturing a transfer mask according to any one of configurations 1 to 6, wherein the dry etching uses an oxygen-containing chlorine-based gas as the etching gas.

<Structure 8>
The mask blank is provided with a light-shielding film between the substrate and the thin film.
A step of using the thin film on which the transfer pattern is formed as a mask, performing dry etching on the light-shielding film, and forming a transfer pattern on the light-shielding film.
The method for producing a transfer mask according to any one of configurations 1 to 7, further comprising a step of removing the thin film after forming a transfer pattern on the light-shielding film.

<Structure 9>
The mask blank is provided with a semitransmissive film between the substrate and the thin film.
Using the thin film on which the transfer pattern is formed as a mask, dry etching is performed on the light semi-transmissive film to form a transfer pattern on the light semi-transmissive film.
After forming a transfer pattern on the light transflective film, the inorganic resist film is removed, then a resist pattern including a light-shielding band pattern is formed on the thin film, and the resist pattern is used as a mask for dry etching on the thin film. The method for producing a transfer mask according to any one of configurations 1 to 7, further comprising a step of forming a pattern including a light-shielding band on the thin film.

<Structure 10>
A method for manufacturing a semiconductor device, which comprises a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to the configuration 8 or 9.

According to the present invention having the above configuration, it is possible to perform pattern etching of the lower layer using a resist pattern having good etching resistance as a mask, thereby forming a transfer mask capable of forming a fine transfer pattern, and a method for manufacturing a transfer mask. A method for manufacturing a semiconductor device can be obtained.

It is sectional drawing (the 1) which explains the manufacturing method of the transfer mask which concerns on 1st Embodiment. It is sectional drawing (the 2) explaining the manufacturing method of the transfer mask which concerns on 1st Embodiment. It is sectional drawing (the 1) which explains the manufacturing method of the transfer mask which concerns on 2nd Embodiment. It is sectional drawing (the 2) explaining the manufacturing method of the transfer mask which concerns on 2nd Embodiment. It is a secondary electron image of the irradiated region and the non-irradiated region of the electron beam observed in the evaluation 1 of the example. It is a secondary electron image of the irradiation region of the electron beam observed in the evaluation 2 of the Example. It is a secondary electron image of the non-irradiated region of the electron beam observed in the evaluation 2 of the example.

The inventors have formed a transfer pattern on the inorganic resist film by drawing exposure using an electron beam and subsequent development processing, and then irradiate the inorganic resist film with an electron beam to improve the etching resistance of the inorganic resist film. Found to improve. Hereinafter, a detailed configuration of the present invention for obtaining such an effect will be described in the order of a method for manufacturing a transfer mask and then a method for manufacturing a semiconductor device.

<< First Embodiment: Manufacturing Method of Transfer Mask >>
1 and 2 are cross-sectional process diagrams illustrating a method for manufacturing a transfer mask according to the first embodiment. The method for producing a transfer mask according to the first embodiment described with reference to these figures is a method applied when producing a binary mask or a reflective mask as a transfer mask. Hereinafter, the method for producing the transfer mask of the first embodiment will be described with reference to FIGS. 1 and 2.

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

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

Further, in particular, if the substrate 11 is a mask blank for a reflective mask, _{it is configured by 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, and the peripheral end surface and the main surface are polished to a predetermined surface roughness, and then a predetermined cleaning treatment and a drying treatment are performed. It is a thing.

The exposure light and the exposure time in the lithography referred to here are the exposure light and the exposure time in the lithography using the transfer mask produced by using the mask blank. As the 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 (Extreme Ultra Violet) light (wavelength: 13.56 nm) is applied as the exposure light.

[Light-shielding film (absorbent film) 13]
The light-shielding film (absorbent film) 13 is a film in which a fine pattern is formed by etching with a thin film as a mask, which will be described next. The light-shielding film (absorbent film) 13 is a single-layer or multi-layered film formed by using a material according 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 light-shielding performance (optical density equal to or higher than a predetermined value) with respect to the exposure light used for exposure transfer of a mask pattern when used as a binary mask. Can be configured. Specifically, it may be composed of a simple substance of a transition metal such as chromium, tantalum, ruthenium, tungsten, titanium, hafnium, molybdenum, nickel, vanadium, zirconium, niobium, palladium, rhodium, or a material containing a compound thereof. 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. It may be composed of a tantalum compound to which one or more elements are added.

Further, the light-shielding film 13 for the binary mask may be composed of a material containing a compound of a transition metal and silicon (including a 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 whose main components are transition metal and silicon, oxygen and / or nitrogen. Further, the light-shielding film 13 may be composed of a transition metal and a material containing oxygen, nitrogen and / or boron as main components. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium and the like can be applied.

The light-shielding film 13 for a binary mask may be composed of a material made of silicon and nitrogen, or a material made of silicon and nitrogen containing one or more elements selected from metalloid elements and non-metal elements. 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 non-metal element in addition to nitrogen. This non-metal element means a non-metal element (nitrogen, carbon, oxygen, phosphorus, sulfur, selenium), halogen and noble gas in a narrow sense. Among these non-metal elements, it is preferable to contain one or more elements selected from carbon, fluorine and hydrogen.

The light-shielding film 13 for a binary mask made of the above materials 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 having an antireflection function (MoSiN) composed of molybdenum (Mo), silicon (Si), and nitrogen (N) is laminated as a lower layer 13a and an upper layer 13b having different compositions. Is exemplified. Further, as the light-shielding film 13, a composition gradient film configured so that the composition in the film thickness direction is continuously or stepwise different is exemplified. The light-shielding film 13 as described above can be formed by, for example, a sputtering method.

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

(Absorbent film 13 for reflective mask)
The absorber film 13 for the reflective mask is a film provided on the multilayer reflective film (not shown here), and has a function of absorbing EUV light. As the absorber film 13 for such a reflective mask, 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 is preferably one having an amorphous or microcrystalline structure from the viewpoint of smoothness and flatness.

The multilayer reflective film provided between the absorber film 13 for the reflective mask and the substrate 11 which is the lower layer of the absorber film 13 for the reflective mask is a film having a function of reflecting EUV light. be. The multilayer reflective film is formed by alternately laminating high refractive index layers and low refractive index layers. The multilayer reflective film includes a Mo / Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 cycles, a Ru / Si periodic multilayer film, a Mo / Be periodic multilayer film, a Mo compound / Si compound periodic multilayer film, and Si. Examples thereof include / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo / Ru / Mo periodic multilayer film, Si / Ru / Mo / Ru periodic multilayer film, and the like, and the material is appropriately selected depending on the wavelength of the exposure light. You can choose. The absorber film 13 and the multilayer reflective film for the reflective mask as described above can be formed by, for example, a sputtering method.

[Thin film 15]
The thin film 15 functions as an etching mask film when etching the light-shielding film (absorbent film) 13. Such a thin film 15 is made of a material having etching resistance to the etchant used when etching the light-shielding film (absorbent film) 13. When the light-shielding film (absorbent film) 13 is made of a silicon-based material or a transition metal VDD-based material and is patterned by dry etching with a fluorine-based gas, the thin film 15 is a material having high resistance to these dry etchings. It is preferable to use a material made of chromium, which is a chromium compound, or a chromium compound obtained by adding elements such as oxygen, nitrogen, and carbon to chromium. Further, when the light-shielding film 13 is made of a chromium-based material and is patterned by dry etching with a mixed gas of chlorine-based gas and oxygen gas, the thin film 15 contains silicon or an element such as oxygen, nitrogen, or carbon in silicon. It is preferably composed of a material composed of the added silicon compound.

On the other hand, the absorber film 13 for the reflective mask is formed of a tantalum-based material, and such an absorber film 13 is either dry-etched with a fluorine-based gas or an oxygen-free chlorine-based gas (oxygen-free chlorine). Patterning is performed by dry etching with (based gas). In this case, the thin film 15 is preferably composed of chromium, which is a material having high resistance to these dry etchings, or a material made of a chromium compound obtained by adding elements such as oxygen, nitrogen, and carbon to chromium. The thin film 15 may further have an antireflection function, whereby a transfer mask in a state where the thin film 15 remains on the light-shielding film 13 may be produced.

Further, such a thin film 15 is formed by a sputtering method, whereby the edge roughness when the thin film 15 is pattern-etched is suppressed to be small, and a film having a good side wall shape can be obtained. It has become.

<Formation of Inorganic Resist Film 21>
Next, as shown in FIG. 1 (B), an inorganic resist film 21 is formed on the upper portion of the thin film 15 of the mask blank 1. The inorganic resist film 21 is a film that is patterned by a lithography process, and the patterned resist pattern serves as an etching mask when etching the thin film 15. The formation of such an inorganic resist film 21 is performed after forming a liquid film of an aqueous solution (precursor solution) containing a metal suboxide cation, a polyatomic anion, and a peroxide-based ligand on the thin film 15. It is carried out by drying the liquid film. Further, after the inorganic resist film 21 is formed, it is preferable to perform a heat treatment (Post applied bake: PAB) on the inorganic resist film 21 in order to stabilize the substance in the inorganic resist film 21.

The metal suboxide cation contained in the aqueous solution (precursor solution) is a polyatomic cation having a metal element and a covalently bonded oxygen atom. Among them, those that satisfactorily absorb the electron beam irradiated in the subsequent exposure treatment of the inorganic resist film 21 are preferably used. Such metal hydroxide cations are polyatomic cations (eg, HfO ²⁺ , HfOOH ⁺ , Hf (OH) ₂ ²⁺ , Hf (OH) ₃ ⁺ ) having oxygen atoms covalently bonded to hafnium. , At least one of these is contained in the aqueous solution.

Further, the polyatomic anion remains in the resist pattern as an inorganic oxide after the lithography treatment on the inorganic resist film 21, and constitutes the resist pattern. Such polyatomic anions has been made in view of oxygen-based, for example, _{^{SO 4 2-, BO 3 3-,}} AsO 4 3-, MoO 4 2-, PO 4 3-, WO 4 2-, SeO 4 ^2, and SiO ₄ ^4-like are exemplified, those of one or more combinations of these is to be contained in the aqueous solution (precursor solution). The concentration of polyatomic anions in the aqueous solution is preferably about 0.5 to about 2.0 times the concentration of metal suboxide cations.

The peroxide-based ligand is for stabilizing the condensation reaction occurring in the inorganic resist film 21 in the subsequent exposure treatment of the inorganic resist film 21. Such a peroxide-based ligand is particularly preferably a radioactive ligand having a peroxide group (-O-O-), and hydrogen peroxide (H 2 O 2 ) is exemplified. As the other peroxide-based ligand, a carbon-free inorganic peroxide-based ligand that can be a pollutant is preferably used. As the inorganic peroxide ligands include, for example peroxy sulfate ions (SO 5 H -), peroxydisulfate ion (S 2 O 8 2-), peroxy chlorate ion (ClO 5 H -) and the like. The concentration of the peroxide-based ligand in the aqueous solution (precursor solution) is preferably 2 to 25 times the concentration of the metal suboxide cation.

In addition to the metal suboxide cations, polyatomic anions, and peroxide-based ligands described above, the aqueous solution (precursor solution) contains anions for adjusting the PH of the aqueous solution. , And other necessary substances may be included. On the other hand, the inorganic resist film 21 may be formed of a material containing one or more elements selected from tin and cobalt.

The formation of the liquid film of the aqueous solution (precursor solution) is carried out by, for example, the spin coating method, but the liquid film is not limited to this, and the liquid film is formed into a solid film by applying another coating method or printing method. can do. The thickness of the inorganic resist film 21 is such that the resist pattern composed of the inorganic resist film 21 sufficiently functions as an etching mask for the lower layer thereof, and is, for example, 10 nm or more and 250 nm or less.

<Formation of inorganic resist pattern 21a>
Next, as shown in FIG. 1C, the inorganic resist film 21 on the mask blank 1 is exposed to an exposure treatment and then developed, so that the transfer pattern to be formed on the thin film 15 is formed on the inorganic resist film 21. Form. As a result, the inorganic resist pattern 21a in which the inorganic 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 inorganic resist film 21 by exposure drawing using an electron beam. At this time, the acceleration voltage [H1] of the electron beam is set to 5 V to about 200 kV, but the acceleration voltage [H1] of the electron beam is several kV to several kV to enable the electron beam drawing of a fine transfer pattern. It is preferable that the setting is as high as several tens of kV. Further, in electron beam drawing at this acceleration voltage [H1], the inorganic resist film 21 is sufficiently exposed, that is, an inorganic resist containing a metal suboxide cation, a polyatomic anion, and a peroxide-based ligand. The exposure amount [D1] of the electron beam is set so that the condensation reaction proceeds sufficiently in the film 21.

Next, the inorganic resist film 21 is subjected to PEB treatment, development treatment, rinsing treatment, and spin drying treatment. As a result, the inorganic resist film 21 forms a patterned inorganic resist pattern 21a. In the above development process, the unexposed portion in the electron beam drawing is dissolved in a developing solution and removed. As the developing solution, an organic solvent is preferably used, and specifically, a ketone solvent typified by 2-heptanone or an alcohol solvent is preferably used. In addition to this, an aqueous acid or base can also be used as a developing solution, and specifically, a quaternary ammonium hydroxide composition typified by tetramethylammonium hydroxide (TMAH) can be applied. ..

<Batch irradiation of electron beams>
Next, as shown in FIG. 1 (D), the inorganic resist film 21 after the transfer pattern is formed, that is, the inorganic resist pattern 21a is irradiated with the electron beam E. As a result, the condensation reaction of the substance left without being condensed in the inorganic resist pattern 21a is promoted.

At this time, the electron beam E is collectively irradiated to a wide area regardless of the planar shape of the inorganic resist pattern 21a. The range of batch irradiation of the electron beam E may be the entire surface of the surface on which the inorganic resist film 21 is formed on the substrate 11, or may be the entire surface of each region obtained by dividing this surface into a plurality of regions.

At this time, the acceleration voltage [H2] of the electron beam E may be a value lower than the acceleration voltage [H1] at the time of drawing the electron beam, which is stable in the electron beam irradiator. Any value that can be expected is sufficient.

Further, here, the entire region of the inorganic resist pattern 21a may be irradiated with the electron beam E. Therefore, the exposure amount [D2] of the electron beam E is not limited, but the exposure amount [D2] is the exposure amount [D1] at the acceleration voltage [H1] in the electron beam drawing performed earlier. It may be less than the value corresponding to. Here, in the irradiation of the resist film with an electron beam, the lower the setting of the acceleration voltage, the more the amount of charge acting on the film increases, and empirically, the value obtained by dividing the exposure amount by the acceleration voltage becomes a substantially constant value. .. Therefore, the exposure amount [D2] here is [D2] <([D1] / [H1]) × [H2] as an example. Further, it has been confirmed that the exposure amount [D2] is effective when [D2] ≧ 0.05 × ([D1] / [H1]) × [H2] from the examples described below.

<Patterning of thin film 15>
Next, as shown in FIG. 1 (E), the thin film 15 is etched using the inorganic resist pattern 21a as a mask to form the transfer pattern 15a on the thin film 15 to obtain the transfer pattern 15a composed of the thin film 15. Here, the chromium-based thin film 15 is etched using the inorganic resist pattern 21a composed of the inorganic resist 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 the etching gas. As a result, the chromium-based thin film 15 can be etched with respect to the inorganic resist pattern 21a with extremely high etching selectivity, and the transfer pattern 15a obtained by transferring the shape of the inorganic resist pattern 21a composed of the inorganic resist with good accuracy. To form.

After forming the transfer pattern 15a on the thin film 15 as described above, the inorganic resist pattern 21a on the transfer pattern 15a is removed. Here, for example, the inorganic resist pattern 21a is peeled off and removed by a cleaning treatment using a hydrogen peroxide mixture (SPM).

<Patterning of light-shielding film (absorbent film) 13>
Then, as shown in FIG. 2A, the light-shielding film (absorbent film) 13 is dry-etched using the transfer pattern 15a made of the thin film 15 made of the chromium-based material as a mask. As a result, a transfer pattern is formed on the light-shielding film (absorbent film) 13, and the light-shielding film 13 is patterned in the shape of the transfer pattern 15a to obtain a light-shielding pattern (absorbent pattern) 13aa. At this time, if the light-shielding film 13 is for a binary mask and is made of a material containing silicon, dry etching of the light-shielding film 13 using a fluorine-based gas is performed. If the mask blank 1 is a mask blank for a reflective mask and the absorber film 13 is made of a material containing tantalum as a main component, a fluorine-based gas or a chlorine-based gas containing no oxygen (chlorine-based gas) ( Dry etching using oxygen-free chlorine-based gas) is performed on the absorber film 13.

<Removal of thin film 15>
Next, as shown in FIG. 2B, 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, in order to remove the transfer pattern 15a made of a chromium-based material, a mixed gas of a chlorine-based gas and an oxygen gas (oxygen-containing chlorine-based gas) is used as the etching gas. Thereby, the thin film 15 of the chromium-based material can be removed by etching with extremely high etching selectivity with respect to the silicon-based or tantalum-based light-shielding film (absorbent 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. Further, if the transfer mask 1a is a reflective mask, the exposure light is used on the substrate 11 in which the thermal expansion due to the UV light which is the exposure light is suppressed to a low level, via a multilayer reflective film (not shown here). An absorber pattern 13aa that absorbs a certain EUV light is provided.

<< Second Embodiment: Manufacturing method of transfer mask >>
3 to 4 are cross-sectional process diagrams illustrating a method for manufacturing a transfer mask according to the second embodiment. The method for manufacturing a transfer mask according to the second embodiment, which will be described with reference to these figures, is a method applied when manufacturing a halftone type phase shift mask as a transfer mask. Hereinafter, the method for manufacturing the transfer mask of the second embodiment will be described with reference to FIGS. 3 to 4. In FIGS. 3 to 4, the same components as those described with reference to FIGS. 1 and 2 are designated by the same reference numerals, and duplicate description will be omitted.

<Preparation of mask blank 2>
First, as shown in FIG. 3A, a mask blank 2 in which a translucent film 43 and a thin film 45 are provided in this order is prepared on one main surface of the substrate 11. Of these elements constituting the mask blank 2, the substrate 11 may be the same as that of the mask blank 1 for the binary mask of the first embodiment described above. Therefore, here, the configurations 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 at an intensity that does not substantially contribute to the exposure (for example, the transmittance with respect to the exposure light is 1% to 30%), and the light semi-transmissive film 43 is transmitted. It has a function of causing a predetermined phase difference (for example, 150 ° C. to 200 ° C.) between the transmitted exposure light and the exposure light transmitted through the air by the same distance as the thickness of the semitransmissive film 43. If so, it may be composed of a known composition. Specifically, a material containing a compound of a transition metal and silicon (including a transition metal silicide) is exemplified, and a material containing these transition metal and silicon and oxygen and / or nitrogen as main components is exemplified. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium and the like can be applied. The light semi-transmissive film 43 as described above can be formed by, for example, a sputtering method.

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

[Thin film 45]
The thin film 45 is a film used as a light-shielding film, and is, for example, a material film containing chromium. Such a thin film 45 may be formed into a single layer, may be formed into a two-layer structure of a lower layer 45a and an upper layer 45b as shown in the figure, or may be further formed into a plurality of multiple layers. good. When the thin film 45 used as the light-shielding film is formed as a plurality of layers, each layer having a different chromium (Cr) content 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 pattern-etched is suppressed to a small value, and a film having a good side wall shape can be obtained. It has become.

Further, 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 chromium, in addition to the chromium metal. Further, the thin film 45 is selected from indium (In), tin (Sn), and molybdenum (Mo) for the purpose of suppressing a decrease in the etching rate of the entire film while maintaining the optical density (OD). It may contain at least one metal element (metal element 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. Further, 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. It is possible to remove the thin film 45 by etching.

<Formation of Inorganic Resist Film 21-Batch Irradiation of Electron Beams>
Next, the steps shown in FIGS. 3 (B) to 3 (D) are carried out in the same manner as the steps described with reference to FIGS. 1 (B) to 1 (D) in the first embodiment.

That is, the inorganic resist film 21 is formed as shown in FIG. 3 (B). Next, as shown in FIG. 3C, the inorganic resist pattern 21a is formed. Next, as shown in FIG. 3 (D), by collectively irradiating the electron beam E, the condensation reaction of the substance left without being condensed in the inorganic resist pattern 21a is advanced.

<Patterning of thin film 45>
After the above, as shown in FIG. 3 (E), the thin film 45 is etched using the inorganic resist pattern 21a as a mask to form a transfer pattern 45aa on the thin film 45. Here, for example, the inorganic resist pattern 21a is used as a mask to etch the thin film 45 of the chromium-based material. At this time, dry etching is performed using a mixed gas of chlorine-based gas and oxygen gas (oxygen-containing chlorine-based gas) as the etching gas. As a result, the thin film 45 of the chromium-based material can be etched with respect to the inorganic resist pattern 21a with extremely high etching selectivity, and the shape of the inorganic resist pattern 21a is transferred to the thin film 45 with good accuracy.

After forming the transfer pattern 45aa on the thin film 45 as described above, the inorganic resist pattern 21a on the transfer pattern 45aa is removed. Here, for example, the inorganic resist pattern 21a is peeled off and removed by a cleaning treatment using a hydrogen peroxide mixture (SPM).

<Patterning of light semi-transmissive film 43>
Next, as shown in FIG. 4A, the light semitransmissive film 43 using a fluorine-based gas was dry-etched using the thin film 45 on which the transfer pattern 45aa was formed as a mask, and formed of a silicon-containing material. The light transflective film 43 is patterned. As a result, a transfer pattern is formed on the light semi-transmissive film 43, and a 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 on the substrate 11. Further, a hole-shaped alignment mark pattern 43b that penetrates the thin film 45 and the light semitransmissive film 43 is formed in the outer peripheral region 11b of the substrate 11.

<Formation of resist pattern 47 including shading band pattern>
Next, as shown in FIG. 4B, 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, first, a resist film is formed on the substrate 11 by a spin coating method. Next, the resist film is exposed so that the resist film is left in a shape that covers 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. As a result, a resist pattern 47 including a light-shielding band pattern is formed so as to cover the outer peripheral region 11b of the substrate 11. Since the resist pattern 47 formed here is not a fine pattern, it may have a thick film thickness. Therefore, it may be formed using an organic resist material.

<Formation of shading pattern>
Next, as shown in FIG. 4C, the light-shielding pattern 45c formed by dry-etching the thin film 45 using the resist pattern 47 including the light-shielding band pattern as a mask and patterning the thin film 45 in a band shape covering the outer peripheral region 11b is formed. Form. At this time, the thin film 45 of the chromium-based material is etched by using a mixed gas of chlorine-based gas and oxygen gas as the etching gas.

<Removal of resist pattern 47>
Next, as shown in FIG. 4D, the resist pattern 47 including the light-shielding band pattern is removed, and a predetermined treatment such as cleaning is performed. As described above, a halftone type phase shift mask can be obtained as the transfer mask 2a.

In the transfer mask 2a thus obtained, the light semitransmissive pattern 43a is provided in the light semitransmissive pattern forming region 11a on the substrate 11, and the alignment mark pattern 43b and the light semitransmissive film 43 are provided in the outer peripheral region 11b on the substrate 11. The light-shielding pattern 45c is provided through the above.

≪Manufacturing method of semiconductor device≫
As the method for manufacturing the semiconductor device according to the embodiment, the transfer mask 1a or the transfer mask 2a manufactured by the method for manufacturing the transfer mask described above is used, and the transfer pattern is exposed and transferred to the resist film on the substrate. It is characterized by doing. The method for manufacturing such a semiconductor device is as follows.

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

After the above, the resist film on which the transfer pattern has been exposed and transferred is developed to form a resist pattern, and the surface layer of the substrate is etched or introduced with impurities using this resist pattern as a mask. After the treatment is completed, the resist pattern is removed.

The above processing is repeated on the substrate while exchanging the transfer mask, and further necessary processing is performed to complete the semiconductor device.

<< Effect of the embodiment >>
The method for manufacturing a transfer mask according to the above description has a configuration in which an inorganic resist pattern 21a is formed by electron beam drawing and subsequent development processing, and then the inorganic resist pattern 21a is collectively irradiated with an electron beam. .. As a result, the condensation reaction of the substance remaining in the inorganic resist pattern 21a without being condensed after the electron beam drawing can proceed, and the inorganic resist pattern 21a can be made into a dense structure.

Therefore, in the etching of the thin film 15 or the thin film 45 of the lower layer using the inorganic resist pattern 21a as a mask, it is possible to prevent the thin film 15 or the thin film 45 from causing damage such as pinholes, and the thin film 15 has good shape accuracy. Alternatively, the thin film 45 can be patterned. As a result, it is possible to obtain a transfer mask having a fine transfer pattern by etching using an inorganic resist pattern 21a that functions with a thinner film thickness than when an organic resist is used as a mask.

Further, by manufacturing a semiconductor device using the transfer mask 1a or the transfer mask 2a manufactured as described above, it is possible to obtain a semiconductor device having a fine line pattern with high shape accuracy.

<< Third Embodiment: Manufacturing method of transfer mask >>
The method for manufacturing a transfer mask according to the third embodiment relates to a method for manufacturing a transfer mask as a reflective mask using a mask blank having a structure in which a multilayer reflective film and a thin film are laminated in this order on a substrate. be. In this third embodiment, the thin film is provided with a function required as an absorber film. That is, an inorganic resist pattern having an absorption pattern is formed on a thin film having the function of an absorber film, and dry etching is performed on the thin film using the inorganic resist pattern as a mask to form an absorption pattern on the thin film. The completed reflective mask has a structure in which a multilayer reflective film and a thin film having an absorber pattern (absorbent film) are sequentially laminated on a substrate. The thin film has the same configuration as the absorber membrane 13 of the first embodiment. Therefore, a fluorine-based gas or an oxygen-free chlorine-based gas is used for dry etching of a thin film using an inorganic resist pattern as a mask. Other matters related to the substrate, the multilayer reflective film, the inorganic resist pattern, and the like are the same as in the case of the first embodiment.

The method for manufacturing a transfer mask of the third embodiment also has a configuration in which an inorganic resist pattern is formed by electron beam drawing and subsequent development processing, and then the inorganic resist pattern is collectively irradiated with an electron beam. As a result, the condensation reaction of the substance remaining in the inorganic resist pattern without being condensed after the electron beam drawing can proceed, and the inorganic resist pattern can be made into a dense structure.

Therefore, in the etching of the lower thin film (absorbent film) using this inorganic resist pattern as a mask, it is possible to prevent damage such as pinholes from being generated in the thin film, and the thin film can be patterned with good shape accuracy. Is possible. As a result, it is possible to obtain a transfer mask having a fine transfer pattern by etching using an inorganic resist pattern as a mask, which functions with a thinner film thickness than when an organic resist is used.

<< Another embodiment >>
The transfer mask manufacturing method of each of the above-described embodiments can also be applied to the case of manufacturing an imprint mold from a mask blank provided with an etching mask film (corresponding to the thin film of the present invention) on a substrate. That is, the method for manufacturing the imprint mold is a method for manufacturing an imprint mold using a mask blank having an etching mask film on the main surface of the substrate, and is a step of forming an inorganic resist film on the etching mask film. After drawing and exposing the transfer pattern to the inorganic resist film using an electron beam, the process of forming a transfer pattern on the inorganic resist film by developing treatment and the process of forming the transfer pattern on the inorganic resist film are performed. On the other hand, a step of irradiating an electron beam and a step of performing dry etching on the etching mask film using the inorganic resist film after the electron beam irradiation as a mask to form a transfer pattern on the etching mask film are provided. It is characterized by.

The imprint mold manufacturing method of this other embodiment also has a configuration in which an inorganic resist pattern is formed by electron beam drawing and subsequent development processing, and then the inorganic resist pattern is collectively irradiated with an electron beam. As a result, the condensation reaction of the substance remaining in the inorganic resist pattern without being condensed after the electron beam drawing can proceed, and the inorganic resist pattern can be made into a dense structure.

Therefore, in the etching of the etching mask film of the lower layer using this inorganic resist pattern as a mask, it is possible to prevent damage such as pinholes from being generated in the etching mask film, and it is possible to pattern the thin film with good shape accuracy. It will be possible. As a result, an etching mask film (etching mask pattern) having a fine transfer pattern can be formed by etching using an inorganic resist pattern as a mask, which functions with a thinner film thickness than when an organic resist is used. Further, by digging the surface of the substrate by dry etching using this etching mask pattern as a mask, it is possible to obtain an imprint mold having a fine transfer pattern on the surface of the substrate.

≪Manufacturing of transfer mask≫
The method for producing the transfer mask of the present invention will be described in more detail with reference to Examples. Here, referring to FIGS. 1 and 2, a transfer mask to be a binary mask was prepared by the following procedure.

First, referring to FIG. 1 (A), a translucent 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 the substrate 11. In this translucent substrate, the end face and the main surface are 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 treatment and a drying treatment. be.

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

Next, the translucent substrate (substrate 11) provided with the light-shielding film 13 was heat-treated at 450 ° C. for 30 minutes to reduce the film stress of the light-shielding film 13. An analysis by X-ray photoelectron spectroscopy was performed on the light-shielding film 13 which had been heat-treated on another translucent substrate (substrate 11) in the same procedure. 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). The surface layer of the upper layer 13b of the light-shielding film 13 contained 14.4 atomic% of nitrogen and 38.3 atomic% of oxygen. Further, when the optical density of the light-shielding film 13 was measured using a spectroscopic ellipsometer, it was 3.0, which was confirmed to be a sufficient optical density as the light-shielding film.

Next, a thin film 15 (CrN film) made of chromium and nitrogen was formed in contact with the surface of the upper layer 13b of the light-shielding film 13 to a thickness of 5 nm to obtain a mask blank 1. Specifically, a translucent substrate (substrate 11) provided with a light-shielding film 13 after heat treatment is installed in a single-wafer DC sputtering apparatus, and an argon (Ar) and nitrogen (N _{2) are used using a chromium (Cr) target.} ) Was used as the sputtering gas, and the thin film 15 was formed by reactive sputtering (DC sputtering). As a result of analysis by X-ray photoelectron spectroscopy on the thin film 15 formed on another translucent substrate under the same conditions, it was Cr: N = 72: 28 (atomic% ratio).

Next, referring to FIG. 1 (B), an inorganic resist film 21 for electron beam drawing exposure was formed with a film thickness of 40 nm in contact with the surface of the thin film 15 by a spin coating method. Then, the inorganic resist film 21 was subjected to PAB treatment at 140 ° C. for 10 minutes.

Next, referring to FIG. 1C, the inorganic resist film 21 was irradiated with an electron beam, and a line-and-space test pattern having a line width of 200 nm and a space width of 200 nm was drawn and exposed. At this time, electron beam drawing was performed at an acceleration voltage [H1] = 50 kV and an exposure amount [D1] = 600 μC / cm ^2. This exposure amount [D1] is an exposure amount at which a pattern according to the design dimensions is formed on the inorganic resist film 21. Next, the inorganic resist film 21 after the electron beam drawing was subjected to PEB treatment at 180 ° C. for 600 seconds.

After that, 2-heptanone is supplied as a developing solution to the inorganic resist film 21 on the substrate 11 to perform development processing of the inorganic resist film 21, and then the substrate 11 is rotated at high speed to remove the developing solution from the substrate 11. Then, the inorganic resist film 21 on the substrate 11 was naturally dried. As a result, an inorganic resist pattern 21a having a line-and-space test pattern shape with a line width of 200 nm and a space width of 200 nm was formed.

Next, with reference to FIG. 1 (D), a batch irradiation of the electron beam E was performed at an acceleration voltage [H2] = 700 V on a half region of the surface of the substrate 11 on which the inorganic resist film 21 was formed. At this time, the exposure amount [D2] was set to 0.4 μC / cm ² . This exposure amount [D2] is 0.05 times a value corresponding to the exposure amount [D1] at the acceleration voltage [H1] at the time of electron beam drawing, and [D2] = 0.05 × ([D1]]. / [H1]) × [H2].

As a result, an irradiation region in which the inorganic resist pattern 21a was collectively irradiated with electron beams and a non-irradiation region in which the electron beams were not collectively irradiated were formed on the substrate 11.

Next, referring to FIG. 1 (E), dry etching of the thin film 15 was performed using the inorganic resist pattern 21a after irradiation with the electron beam as a mask. At this time, a dry etching apparatus (Tetra II manufactured by Applied Materials) was used to dry-etch the thin film 15 made of chromium and nitrogen _{using a mixed gas of Cl 2} and O _{2 as an etching gas.} The etching time was 90 seconds including over-etching. As a result, a transfer pattern 15a to which the test pattern was transferred was formed on the thin film 15.

In this state, as evaluation 1, secondary electron images of the irradiated region and the non-irradiated region of the electron beam were observed using an electron microscope (CD-SEM manufactured by Advanced Co., Ltd.).

Then, the inorganic resist pattern 21a remaining on the upper part of the transfer pattern 15a was peeled off and removed using SPM.

Subsequently, with reference to FIG. 2A, dry etching of the light-shielding film 13 with the transfer pattern 15a as a mask was performed. At this time, using a dry etching apparatus (Tetra II manufactured by Applied Materials), a light-shielding film 13 made of molybdenum, silicon and nitrogen is formed _{by using a mixed gas of sulfur hexafluoride (SF 6) and helium (He) as an etching gas.} Dry etching was performed. As a result, a light-shielding pattern 13aa was formed on the light-shielding film 13.

In this state, as evaluation 2, secondary electron images of the irradiated region and the non-irradiated region of the electron beam were observed using an electron microscope (CD-SEM manufactured by Advanced Co., Ltd.).

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

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

≪Evaluation result≫
FIG. 5 is a secondary electron image of the irradiated region 10a and the non-irradiated region 10b observed in the evaluation 1, and a partially enlarged view of FIG. 5 (A) corresponds to FIG. 5 (B). In these figures, the surfaces of the inorganic resist pattern 21a and the light-shielding film 13 in the state shown in the cross-sectional view of FIG. 1 (E) are observed in both the irradiated region 10a and the non-irradiated region 10b.

As shown in these figures, it was confirmed that the inorganic resist pattern 21a in the irradiated region 10a has almost no surface roughness and less damage due to etching as compared with the inorganic resist pattern 21a in the non-irradiated region 10b. rice field. On the other hand, it was confirmed that the inorganic resist pattern 21a in the non-irradiated region 10b was damaged by etching because the surface was uneven.

FIG. 6 is a secondary electron image of the irradiation region 10a observed in the evaluation 2, and a partially enlarged view of FIG. 6A corresponds to FIG. 6B. Further, FIG. 7 is a secondary electron image of the non-irradiated region 10b observed in the evaluation 2, and a partially enlarged view of FIG. 7A corresponds to FIG. 7B. In these figures, the transfer pattern 15a and the surface of the substrate 11 in the state shown in the cross-sectional view of FIG. 2A are observed in both the irradiated region 10a and the non-irradiated region 10b.

As shown in these figures, the transfer pattern 15a in the irradiated region 10a has less surface roughness and edge roughness than the transfer pattern 15a in the non-irradiated region 10b, and masks the previously implemented inorganic resist pattern 21a. It was confirmed that there was little damage due to the etching. On the other hand, it was confirmed that the transfer pattern 15a in the non-irradiated region 10b had pinholes on the surface, had a large edge roughness, and was damaged by etching.

Further, from the above, it was confirmed that the inorganic resist pattern 21a has a dense structure by performing batch irradiation of electron beams after forming the inorganic resist pattern 12a by the lithography treatment.

1,2 ... Mask blank 1a, 2a ... Transfer mask 11 ... Substrate 13 ... Light-shielding film (absorbent film)
15 ... Thin film (etching mask film)
21 ... Inorganic resist film 21a ... Inorganic resist pattern (transfer pattern)
E ... Electron beam 43 ... Light semi-transmissive film 45 ... Thin film (light-shielding film)
47 ... Resist pattern including shading band pattern

Claims (10)

A method for manufacturing a transfer mask using a mask blank having a thin film on the main surface of a substrate.
An aqueous solution containing a metal suboxide cation, a polyatomic inorganic anion, and a peroxide-based ligant is applied onto the thin film to form a liquid film, and then the liquid film is dried to obtain the thin film . forming a non-machine resist film,
A step of drawing and exposing a transfer pattern on the inorganic resist film with an exposure amount D1 using an electron beam having an acceleration voltage H1 and then performing a development process to form a transfer pattern on the inorganic resist film.
A step of irradiating the inorganic resist film after the transfer pattern is formed with an exposure amount D2 using an electron beam having an acceleration voltage H2, and a step of irradiating the inorganic resist film with an exposure amount D2.
It is provided with a step of using the inorganic resist film after being irradiated with the electron beam as a mask, performing dry etching on the thin film, and forming a transfer pattern on the thin film .
A method for producing a transfer mask, wherein the acceleration voltages H1 and H2 and the exposure amounts D1 and D2 satisfy the condition of D2 <(D1 / H1) × H2. The method for producing a transfer mask according to claim 1 , wherein the metal suboxide cation is a polyatomic cation having an oxygen atom covalently bonded to hafnium. The method for producing a transfer mask according to claim 1 or 2 , wherein the thin film is formed by a sputtering method. The method for producing a transfer mask according to any one of claims 1 to 3 , wherein the thin film is made of a material containing chromium. Any of claims 1 to 4 , wherein in the step of irradiating the inorganic resist film with the electron beam after the transfer pattern is formed, the electron beam is irradiated with an acceleration voltage lower than that of the drawing exposure. The method for producing a transfer mask according to. The method for producing a transfer mask according to any one of claims 1 to 5 , wherein the dry etching uses an oxygen-containing chlorine-based gas as the etching gas. The mask blank is provided with a light-shielding film between the substrate and the thin film.
A step of using the thin film on which the transfer pattern is formed as a mask, performing dry etching on the light-shielding film, and forming a transfer pattern on the light-shielding film.
The method for producing a transfer mask according to any one of claims 1 to 6 , further comprising a step of removing the thin film after forming a transfer pattern on the light-shielding film. The mask blank is provided with a semitransmissive film between the substrate and the thin film.
Using the thin film on which the transfer pattern is formed as a mask, dry etching is performed on the light semi-transmissive film to form a transfer pattern on the light semi-transmissive film.
After forming a transfer pattern on the light semi-transmissive 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 light-shielding band is formed on the thin film. The method for producing a transfer mask according to any one of claims 1 to 6 , further comprising a step of forming the including pattern. The mask blank has a structure in which a light reflecting film and an absorber film are laminated in this order from the substrate side between the substrate and the thin film.
Using the thin film on which the transfer pattern is formed as a mask, dry etching is performed on the absorber film to form a transfer pattern on the absorber film.
The method for producing a transfer mask according to any one of claims 1 to 6 , further comprising a step of removing the thin film after forming a transfer pattern on the absorber film. A semiconductor device comprising a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the transfer mask produced by the method for producing a transfer mask according to any one of claims 7 to 9. Manufacturing method.

Images