KR20110105520A - A blank mask, a photomask using the same and method of fabricating the same - Google Patents

Abstract

A blank mask is disclosed. The blank mask includes a metal film, a hard mask film, and a photoresist sequentially stacked on a transparent substrate. The metal film is a metal silicide having a thickness of 60 nm or less, the silicon content ratio is within 30 ~ 80at%, it can have excellent flatness. In the dry etching of the metal film, the loading effect generated by the distance difference between the metal film and the etching radical ions is reduced, so that a blank mask of excellent quality can be obtained.

Description

Blank Mask, A Photomask using the Same and Method of Fabricating the Same}

The present invention relates to a blank mask, a photo mask using the same and a method of manufacturing the same, and more particularly to a blank mask applicable to a 90 nm or less, in particular 45 nm or less, a photo mask using the same and a method of manufacturing the same. It is about.

In line with the demand for miniaturization of circuit patterns associated with the high integration of large scale integrated circuits, advanced semiconductor microprocessing technology has become a very important factor. In the case of integrated circuits, circuit wiring has been miniaturized for low power and high speed operation. To meet these demands, photomasks, used in photolithography, require techniques that can form more precise circuit patterns.

A general method of manufacturing a blank mask includes sequentially forming a metal film, a hard mask film and a photoresist on a transparent substrate, and forming a pattern through exposure, development, etching and stripping processes. The metal film may include a light blocking film. According to the conventional blank mask manufacturing method, a macro loading effect and a micro loading effect may occur during patterning of the photoresist. Therefore, even when the photoresist is exposed to the same size, the size of the patterns may be different depending on the density of the patterns. When the lower layer is etched using the photoresist as a mask, the reaction rate and removal rate of reacting per unit area with respect to the same developer, the same etchant, or the same amount of etching gas may vary depending on the degree of integration of the patterns. In the region of high density of the patterns, the reaction rate and the removal rate are lower than those in the low region, which may cause a difference in CD (Critical Dimension). That is, in the high density region of the patterns, the concentration of etching radicals for etching the metal film is lowered toward the lower portion of the metal film. As a result, a difference between the top CD and the bottom CD of the metal pattern may occur. On the other hand, in the region where the density of the patterns is low, for example, an isolated pattern region, since the portions to be etched are small, the concentration of the etching radicals may be relatively high. As a result, an undercut occurs in the metal pattern, and a large difference may occur between the top CD and the bottom CD.

When the thickness of the photoresist is thinned, the loading effect, the linearity of the fine pattern, and the fidelity may be improved. However, when the lower layer is patterned, it may be difficult to accurately transfer the original photoresist pattern to the lower layer because the photoresist pattern may be damaged and its shape may change and seriously the lower layer may be damaged. Can be.

In addition, if the thin photoresist pattern is made fine without reducing the thickness of the photoresist, the photoresist pattern aspect ratio may be increased. In general, as the aspect ratio of the photoresist pattern increases, the shape of the pattern tends to be deteriorated, and the pattern transfer accuracy at the time of patterning the lower film which uses this as a mask becomes worse. In extreme cases, a portion of the photoresist pattern may collapse or be peeled off, resulting in a missing pattern. Therefore, with the miniaturization of the photomask pattern, it is necessary to make the thickness of the photoresist thin so that the aspect ratio does not become too large.

As important as reducing the thickness of the photoresist is to lower the thickness of the hard mask film. However, if the thickness of the hard mask layer is too thin, it may be damaged during patterning of the lower layer as in the photoresist. Therefore, consideration of the material and thickness of the hard mask may be important.

In order to increase the resolution of the blank mask, a chemically amplified resist may be used. The chemically amplified resist may generate a strong acid (H +) in the exposure process. The strong acid is amplified in a Post Exposure Bake (PEB) process, so that the chemically amplified resist can be easily developed. In general, nitrogen is added to the metal film to control reflectance characteristics, etching characteristics, optical density, and the like. However, the strong acid generated in the chemically amplified resist may be neutralized by bonding with nitrogen of the metal layer, so that the chemically amplified resist may not be developed. If the chemically amplified resist is not developed, it may be difficult to realize high resolution and eventually may be difficult to manufacture high quality photomasks.

The technical idea of the present invention was created to solve the above problems, and is applicable to lithography techniques of 65 nm or less, in particular 45 nm or less, and has improved reliability of a blank mask, a photo mask using the same, and a manufacturing method thereof. It aims to provide.

The present invention for achieving the above object has the following configuration.

(Configuration 1)

Transparent substrates; A metal film on the transparent substrate; A hard mask film on the metal film; And a resist on the hard mask layer, wherein the metal layer has a silicon content of 30 to 80 at%.

(Composition 2)

The blank mask according to Configuration 1, further comprising a phase inversion film between the transparent substrate and the metal film.

(Composition 3)

In the configuration 2,

And a etch stop layer between the transparent substrate and the phase shift layer or between the phase shift layer and the metal layer.

(Composition 4)

The blank mask according to any one of Configurations 1 to 3, wherein the flatness of the metal film is changed within a range of 1 μm compared with the flatness of the transparent substrate before forming the metal film.

(Composition 5)

In any one of the structures 1 to 3, the metal film includes silicon, and at least one selected from molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and chromium (Cr) A blank mask, characterized in that it further comprises a metal, or a compound thereof.

(Composition 6)

The blank mask according to any one of Configurations 1 to 3, wherein the metal film includes at least one film selected from the group consisting of a light shielding film, an etching reduction film, and an antireflection film.

(Composition 7)

The blank mask according to any one of Configurations 1 to 3, wherein the optical density in the exposure light of the metal film is 2.5 to 3.5.

(Composition 8)

The blank mask according to any one of Configurations 1 to 3, wherein a selectivity ratio between the metal film and the hard mask film is 5 or more.

(Composition 9)

The blank mask according to any one of Configurations 1 to 3, wherein the content of silicon in the metal film increases from the surface thereof toward the transparent substrate.

(Configuration 10)

The blank mask according to any one of Configurations 1 to 3, wherein the content of nitrogen contained in the metal film is 0 to 80 at%.

(Configuration 11)

The blank mask according to any one of Configurations 1 to 3, wherein the absolute stress value of the metal film is 5000 MPa or less.

(Configuration 12)

The blank mask according to any one of Configurations 1 to 3, wherein the metal film contains tantalum.

(Configuration 13)

The blank mask according to any one of Configurations 1 to 3, wherein the reflectance of the metal film is 25% or less at 193 nm.

(Configuration 14)

The blank mask according to any one of Configurations 1 to 3, wherein the hard mask film comprises a metal and one selected from oxides, carbides, nitrides, oxidized carbides, carbides, and oxynitrides of the metals.

(Configuration 15)

The blank mask according to any one of Configurations 1 to 3, wherein the hard mask film is not dry etched in fluorine-based gas but is dry etched in chlorine-based gas.

(Configuration 16)

The blank mask according to any one of Configurations 1 to 3, wherein the hard mask film has a thickness of 3 to 30 nm.

(Configuration 17)

The blank mask according to any one of Configurations 1 to 3, wherein the impurity ions containing ammonia contained in the hard mask film are 1 ppmv or less.

(Configuration 18)

The blank mask according to any one of Configurations 1 to 3, further comprising a resist underlayer between the hard mask film and the resist.

(Configuration 19)

The blank mask according to Configuration 18, wherein the resist underlayer has a thickness of 3 to 50 nm.

(Configuration 20)

The blank mask according to Configuration 18, wherein the resist underlayer is dissolved in an alkaline developer.

(Configuration 21)

A blank mask manufacturing method comprising: preparing a transparent substrate; Forming a metal film on the transparent substrate; Forming a hard mask layer on the metal layer; And forming a resist on the hard mask film, wherein the metal film has a silicon content of 30 to 80 at%.

(Configuration 22)

21. The blank mask manufacturing method of configuration 21, further comprising forming a phase inversion film between the transparent substrate and the metal film.

(Configuration 23)

The blank mask manufacturing method of construction 22, further comprising forming an etch stop film between the transparent substrate and the phase shift film or between the phase shift film and the metal film.

(Configuration 24)

The method of claim 21, wherein the phase inversion film, the etch stop film, the metal film, and the hard mask film are formed by a long throw sputtering method. .

(Configuration 25)

The method for manufacturing a blank mask according to configuration 24, wherein the distance between the transparent substrate and the sputtering target is 200 mm or more.

(Configuration 26)

The blank mask manufacturing method according to any one of Configurations 21 to 23, further comprising forming a resist underlayer between the hard mask film and the resist.

(Configuration 27)

A photomask manufactured by exposing and developing the blank mask of any one of the structures 1-3.

The content of Si constituting the metal film of the blank mask is 30 to 80 at%, and the flatness of the metal film is controlled to be within 1 μm in comparison with the flatness of the transparent substrate before forming the metal film, thereby providing dry etching of the metal film ( The difference in density of radical ions generated during dry etching can be minimized. This allows a good quality blank mask and photomask with a reduced loading effect. High precision patterns are possible, and the pattern transfer accuracy is excellent, and the characteristics of CD linearity, fidelity, CD Mean To Target (MTT), CD Uniformity, and Line Edge Roughness (LER) Improved blank masks and photo masks can be obtained.

1 is a schematic cross-sectional view of a blank mask of a single layer metal film structure according to Embodiment 1 of the present invention.
2 is a schematic cross-sectional view of a blank mask of a two-layer metal film structure according to Examples 2 and 4 of the present invention.
3 is a schematic cross-sectional view of a blank mask of a three-layer metal film metal film structure according to Embodiment 3 of the present invention.
4 is a schematic cross-sectional view of a blank mask according to Embodiment 5 of the present invention.

A method of manufacturing a blank mask according to embodiments of the inventive concept includes forming a phase inversion film, a metal film, a hard mask film, and a resist on a transparent substrate. The flatness of the metal film is changed within a range of 1 μm compared with the flatness of the transparent substrate before forming the metal film.

If the blank mask is a binary intensity blank mask, the method

a1) preparing a transparent substrate;

b1) forming a metal film on the transparent substrate prepared in step a1);

c1) forming a hard mask film on the metal film formed in step b1); And

d1) may comprise forming a resist on the hard mask film formed in step c1).

If the blank mask is a phase inversion blank mask, the method

h1) preparing a transparent substrate;

i1) forming a phase inversion film on the transparent substrate prepared in step h1);

j1) forming an etch stop layer on the phase inversion film formed in step i1);

k1) forming a metal film on the etch stop layer formed in step j1);

l1) forming a hard mask film on the metal film formed in step k1); And

m1) may comprise forming a resist on the hard mask film formed in step l1).

Hereinafter, more specific manufacturing methods and features according to embodiments of the inventive concept will be described.

In steps a1) and h1), the transparent substrate may include soda lime, synthetic quartz or calcium fluoride (CaF ₂ ), which is an lithography light source, i-line (365 nm). To a substrate having at least 85% transmittance at an ArF laser (193 nm) wavelength. When applied to immersion lithography, the transparent substrate may have a birefringence of 5 nm / 6.35 mm or less.

In steps a1) and h1), an absolute flatness value of the transparent substrate may be within 1 μm.

In the steps b1) and k1), the metal film may be composed of a single film or a multilayer film of two or more layers.

In steps b1) and k1), when the metal film is a single film, light may be blocked by only a single film. When the metal film is a single film, the metal film may have a continuous composition from the surface of the single film to the substrate. The metal film contains silicon and additionally contains a material containing at least one metal selected from molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and chromium (Cr), and their oxides. , Carbides, nitrides, oxynitrides, oxidized carbides, carbonitrides, or oxynitrides. The content of silicon may increase from the surface of the single layer toward the substrate.

In the above steps b1) and k1), when the metal film is a multi-layered film of two or more layers, the metal film may function as a light shielding film capable of shielding light and a reflection prevention film for reducing reflection of light. An etch reducing layer may be further formed to correct the CD difference due to the loading effect generated in the uppermost layer during dry etching. The etching reduction film is preferably slower than the etching rate of the uppermost layer. For example, the metal film having a three-layer structure may include an antireflection film, an etch reduction film, and a light shielding film from the top layer, and correct the CD difference generated by the loading effect on the antireflection film in the etch reduction film during dry etching. After etching the light shielding film, the CD difference due to the loading effect may be corrected.

In the steps b1) and k1), the content ratio of silicon in the metal film may be 30 to 80 at%. When the content ratio of the silicon is 30 at% or less, the chemical resistance to the chemicals used after the metal film is formed may be deteriorated, thereby changing the optical properties. When the content ratio of the silicon is 80 at% or more, the stress of the metal film may increase due to the excessive amount of the silicon component. Therefore, the content of silicon included in the metal film should be controlled, and when the content ratio of silicon is 30 to 80 at%, stress and optical properties may be stabilized.

In the steps b1) and k1), the optical density of the exposed light of the metal film may be 2.5 to 3.5.

In steps b1) and k1), a selectivity ratio between the metal layer and the hard mask layer may be 5 or more.

In the steps b1) and k1), the metal film may have a thickness of 20 to 60nm. If the thickness of the metal film is 20 nm or less, the characteristics of the optical density may not be good, and if the thickness of the metal film is 60 nm or more, a loading effect may occur and CD control may be difficult.

In the steps b1) and k1), when the metal film is a nitride film, the nitrogen content may be 0 to 80 at%. When the nitrogen content is 80 at% or more, the extinction coefficient of the thin film may increase, resulting in poor optical density characteristics.

In steps b1) and k1), an absolute value of the stress after the metal film is formed may be 5000 MPa or less. The stress can be obtained through the following Stoney Equation.

The stress may be obtained through a difference between the radius of curvature of the substrate before forming the metal film and the radius of curvature of the substrate after forming the metal film. If the absolute value of the stress is 5000 MPa or more, the bending of the substrate is severe, causing CD Image Imagement Error when implementing the CD can be difficult to control.

In the steps b1) and k1), the metal film may include tantalum to control the stress thereof. The stress after thin film formation may be affected by formation conditions, material composition, and the like. Tantalum has a small change in stress due to changes in external processes.

In the steps b1) and k1), the metal film is a DC sputter, R.F. It may be formed by a sputter or an ion beam deposition method. In order to secure uniformity of the metal film, a long throw sputter method may be used. When the long throw sputtering method is used, it is possible to secure a uniformity of the metal film and to manufacture a high quality blank mask having excellent CD uniformity.

In steps b1) and k1), the reflectance of the surface of the metal film may be 25% or less at an exposure wavelength of 193 nm.

In steps c1) and i1), the hard mask layer may include a metal. The hard mask layer may include one selected from the group consisting of oxides, carbides, nitrides, and compounds thereof.

In the steps c1) and i1), the metal of the hard mask layer is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Rh, Pd And Ag, Cd, In, Sn, Hf, Ta, W, Os, Ir, Pt, and Au.

In steps c1) and i1), the hard mask layer may be etched in a chlorine-based gas without being etched in a fluorine-based gas. In this case, the selectivity ratio between the hard mask layer and the metal layer may be 5 or more.

In the above c1) and i1), the hard mask film is preferably formed to a thickness of 3 ~ 30nm. If the thickness of the hard mask layer is 3 nm or less, damage to the metal layer may occur because the hard mask does not function. When the thickness of the hard mask layer is 30 nm or more, productivity may decrease as the etching time becomes longer, and a loading effect may occur during dry etching, and it may be difficult to implement CD of excellent quality.

In steps c1) and i1), an absolute value of the stress after formation of the hard mask layer may be 5000 MPa or less.

In the steps b1) and k1) or always in steps c1) and i1), a method of heat treatment, a flash lamp, a laser and a plasma treatment method is selected so that the absolute value of the stress after formation of the metal film and the hard mask film is 5000 MPa or less. The method can be used. For stress control of the thin film, it is preferable to perform surface treatment during, during, or after deposition of the thin film. The surface treatment may use a method such as cooling in addition to a method of supplying external energy. The stress control may be performed after the metal film is formed or after the hard mask film is formed.

In steps c1) and i1), the surface resistance of the hard mask layer may be 10 Ω to 10 kΩ / □.

In steps c1) and i1), in order to form the hard mask film, DC sputtering, R.F. Sputtering, or ion beam deposition methods can be used. In order to secure uniformity and productivity of the hard mask layer, a long throw sputter method may be used. The distance between the substrate and the target in the long throw sputtering method is preferably 200 mm or more, in order to ensure excellent uniformity.

In the above steps c1) and i1), the hard mask layer preferably contains 1 ppmv or less of basic impurity ions including impurity ions, in particular, ammonia ions (NH ₄ ⁺ ). The basic ions are combined with the strong acid of the chemically amplified resist deposited on the hard mask film to neutralize the strong acid of the resist. Due to the neutralized strong acid, a substrate dependency phenomenon of the resist occurs, which degrades the resist properties. Accordingly, in order to control the substrate dependency, impurity ions, particularly basic impurity ions, are preferably 1 ppmv or less.

In steps c1) and i1), the hard mask layer may be surface treated to control the substrate dependency of the hard mask layer. The surface treatment method may include a rapid heat treatment apparatus (RTP), a hot-plate heat treatment, a plasma treatment, or a vacuum baking treatment.

In the above steps c1) and i1), the surface treatment of the hard mask film is preferably performed in a vacuum of 5 mtorr or less.

In steps c1) and i1), between the hard mask film and the resist, DBARC (Developable BARC without Exposure) for controlling the substrate dependency of the hard mask film and improving the adhesion between the hard mask film and the resist. This may be further formed. The DBARC has a similar composition to that of the resist, which has good adhesion properties, and can reduce phenomena such as scum exhibited by the substrate dependency. In addition, since the DBARC is dissolved in the developer without the exposure process, no additional Strip process is required.

In the steps c1) and i1), when the DBARC is formed on the hard mask film, the thickness of the DBARC is preferably 50 nm or less, more preferably 30 nm or less. If the DBARC is too thick, the optical properties of the resist may be degraded due to the reflectance of the DBARC, or the DBARC may not be completely removed when the strip is caused by a developer, and residues may remain. If the thickness of the DBARC is formed to be 3nm or less, the substrate dependency can not be controlled.

In the above steps c1) and i1), when the DBARC is formed on the hard mask layer, the DBARC may include a strong acid (ie, H +) for developing a chemically amplified resist. Since the DBARC contains a strong acid, the DBARC compensates for the strong acid being neutralized and lost in the chemically amplified resist, thereby reducing the substrate dependency.

In steps c1) and i1), when the DBARC is formed on the hard mask layer, the soft bake temperature of the DBARC may be higher than that of the resist layer.

Hereinafter, the technical spirit of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below may be modified in various forms, and the scope of the inventive concept is not limited to the embodiments described below.

(Example 1)

Referring to FIG. 1, the blank mask 101 according to the first embodiment of the inventive concept is a transparent substrate 1, a MoSi-based metal film 7, a hard mask film 5, and a photoresist 6. ) May be included. Si content ratio in the metal film may have a predetermined range.

First, using a MoSi (10:90 at%) target, a MoSi-based metal film 7 was formed on a transparent substrate. The reactive gas may include argon (Ar), nitrogen (N), methane (CH ₄ ), and / or oxygen (O) gas. The metal film 7 may be MoSi, MoSiC, MoSiN, MoSiO, MoSiCN, MoSiCO, MoSiON, or MoSiCON. Referring to Table 1, for evaluation of optical and chemical resistance characteristics of the metal film 7, the change in transmittance after immersion for 2 hours in sulfuric acid and SC 1 at OD and 90 degrees was observed. In addition, the content ratio of Si included in the metal film 7 was analyzed by Auger Electron Spectrometer (AES), and the flatness change of the metal film 7 was analyzed by using the flatmaster equipment.

Changes in Optical Properties and Flatness According to the Si Composition Ratio of Metal Films matter OD
@ 193 nm reflectivity(%)
@ 193 nm Chemical resistance
(Delta T% @ 193 nm) TIR (μm)
Change Si content
(at%) Sulfuric acid SC 1 One MoSi 3.1 24.9 0.12 0.23 0.85 62.5 2 MoSiN 2.9 21.2 0.14 0.34 0.43 59.5 3 MoSiO 2.6 17.4 0.09 0.21 0.52 55.3 4 MoSiC 2.9 22.3 0.12 0.43 0.74 56.3 5 MoSiON 3.0 19.8 0.19 0.32 0.63 60.2 6 MoSiCO 2.8 18.9 0.23 0.45 0.51 57.3 7 MoSiCN 2.7 20.1 0.23 0.44 0.60 54.2 8 MoSiCON 2.9 20.3 0.21 0.32 0.68 55.3 Comparison 1 MoSi 3.2 26.9 0.10 0.22 1.63 81.2 Comparison 2 MoSi 3.2 25.4 2.34 5.59 0.32 27.9

Referring to Table 1, the chemical resistance characteristics of sulfuric acid and SC 1 were changed according to the Si content ratio of the metal film 7 based on MoSi. When the content ratio of Si is 30 to 80 at%, the transmittance change in the exposure wavelength is less than 0.5% due to chemicals, but the chemical resistance is excellent. However, when the content ratio of Si is within 30 at% (Comparative 2), The transmittance was changed to 2.34% by sulfuric acid and 5.59% by SC 1, indicating a bad result.

In addition, the flatness was changed according to the content ratio of Si of the metal film 7. When the content ratio of Si is 30 to 80at%, all showed excellent flatness within 1 μm, but when the content ratio of Si is 80at% or more (Comparative 1), the flatness was 1.23 μm, which showed a bad result.

(Example 2)

Referring to FIG. 2, the blank mask 102 according to the second embodiment of the inventive concept is a transparent substrate 1, a MoSi-based metal film 7, a hard mask film 5, and a photoresist 6. ) May be included. Based on Example 1, the change in CD due to the flatness difference was evaluated. The metal film 7 may include a light blocking film 2 and an antireflection film 4 sequentially stacked on the transparent substrate 1. The transparent substrate 1 had a tensile stress whose flatness TIR of the surface before the formation of the metal film 7 was 0.32 mu m. The metal film 7 is formed on the transparent substrate 1 by sequentially stacking a light shielding film 2 of MoSi having a thickness of 28 nm and an anti-reflection film 4 of MoSiN having a thickness of 17 nm. On the metal film 7, a hard mask film 5 of CrCON of 10 nm was deposited. The flatness in the hard mask film 5, measured using the Flatmaster instrument, exhibited a compressive stress of 0.17 μm. After coating FEP-171, a positive chemically amplified resist 6, on the hard mask 5 to a thickness of 150 nm, a photomask 102 was manufactured through an exposure, development, PEB, and etching process. The CD change of the photomask for 70 nm Design CD was measured at 4 points in the center part and the edge part. The CD in the center portion was 68 nm, 2 nm Under CD, and the CD in the edge portion showed excellent results with 5 nm Under CD.

(Comparative Example 2)

To compare with Example 2, after forming a MoSi single metal film having a thickness of 450 kHz, a hard mask film of CrCON was formed. The flatness TIR of the hard mask film showed a value of 1.05 µm. The content ratio of Si in the metal film was 81.02 at%. After the positive chemically amplified resist FEP-171 was coated to a thickness of 150 nm, a photomask was prepared through exposure, development, PEB, and etching processes. In the same manner as in Example 2, the CD change of the photomask with respect to 70 nm Design CD in the center portion and the edge portion was measured. The CD in the center portion was 1 nm Under CD, but the CD in the edge portion was 12 nm Under CD. As the flatness change was larger, the CD deviation was larger.

(Example 3)

Referring to FIG. 3, the blank mask 103 according to the third embodiment of the inventive concept is a metal film 7, a hard mask film 5, and a chemical amplification type sequentially stacked on a transparent substrate 1. The resist 6 may be included.

The metal film 7 may have a three-layer structure and include a light blocking film 2, an etching reduction film 3, and an anti-reflection film 4. The etch reducing film 3 was used as a film for reducing the loading effect generated during the etching of the anti-reflection film.

More specifically, a MoSi light shielding film 2 was deposited on a transparent substrate with a thickness of 30 nm on a transparent substrate by DC sputtering under a MoSi (20: 80 at%) target and argon (Ar) of 100 sccm. The optical density at 193 nm of the light shielding film 2 of MoSi was 2.82, and the reflectance of the light shielding film 2 of MoSi was 52% at 193 nm. MoSi (10: 90at%) target and argon (Ar): nitrogen (N ₂ ) by the DC sputtering method under a gas condition of 95sccm: 5sccm, on the light-shielding film 2 the MoSiN etch reducing film 3 of 5nm Deposited in thickness. MoSiN (20: 80 at%) target and argon (Ar): nitrogen (N ₂ ) by using a DC sputtering method in a gas condition of 80 sccm: 20 sccm, the anti-reflection film (4) of MoSiN on the etch-resistant film (3) 10nm It formed in the thickness of. Thereafter, the optical density at 193 nm of the etch reducing film 3 was 3.0, and the reflectance of the etch reducing film 3 was 19.8% at 193 nm. After the chromium (Cr) target and argon (Ar): oxygen (O ₂ ): nitrogen (N ₂ ): methane (CH ₄ ) = 40sccm: 5sccm: 10sccm: 3sccm by the reactive DC sputtering method, chromium carbonization A hard mask film 5 of oxynitride (CrCON) was deposited to a thickness of 15 nm.

As a result of component analysis using Auger Electron Spectrometer (AES), the light shielding film (2) is molybdenum (Mo) 32at%, silicon (Si) 68at%, the etch reducing film (3) is molybdenum (Mo) 12at%, A composition ratio of 72 at% of silicon (Si) and 16 at% of nitrogen was shown, and the antireflection film 4 exhibited a composition ratio of 19 at% of molybdenum (Mo), 49 at% of silicon (Si), and 32 at% of nitrogen.

Observe the charge up during electron beam (E-beam) exposure of the surface where the light shielding film (2), the etch reducing film (3), the antireflection film (4), and the hard mask film (5) are stacked. In order to measure the sheet resistance using a 4-point probe. The average sheet resistance was 326 Ω / square, and there was no charge up problem.

FEP-171, a positive chemically amplified photoresist (CAR) for electron beam exposure apparatus (CAR) 6, was coated to a thickness of 150 nm and soft bake for 130 ° C./15 minutes. The blank mask 103 was manufactured.

The blank mask 103 was exposed and developed using an electron beam exposure apparatus to form a resist pattern. The hard mask layer was patterned by using the resist pattern as an etching mask by dry etching (chlorine (Cl ₂ ): oxygen (O ₂ ) = 80 sccm: 5 sccm, 400 W, 1 Pa) to form a hard mask pattern. The resist pattern was removed, and the anti-reflection film, the etch-lower film, and the light shielding film were etched by dry etching (CF ₄ = 80 sccm, 400 W, 1 Pa) using the hard mask pattern as an etching mask. The hard mask layer was removed using CR-7S, a chromium etchant, to prepare a photomask.

On the other hand, the blank mask without the etch reducing film was prepared through the same process as above.

CD evaluation results according to the presence or absence of etch reducing film evaluation
ITEM Design CD-Pattern CD [nm] 50 60 70 80 90 100 Etching
Low curtain
(U) Fidelity 0.96 0.97 0.99 One One One Dense pattern 0.8 0.6 0.5 0.3 0.2 0.1 Single pattern 0.4 0.4 0.3 0.1 0.1 0 Etching
Low curtain
(radish) Fidelity 0.93 0.95 0.95 0.97 One One Dense pattern 1.6 1.5 1.5 1.3 0.8 0.5 Single pattern 0.7 0.7 0.6 0.5 0.3 0.2

Table 2 shows CD evaluation results depending on the presence or absence of the etch reducing film. In the presence of the etch-resistant film, Fidelity was relatively excellent, and CD linearity and CD Bias between the dense patterns were relatively low. In the presence of the etch-resistant film, the CD Bias between the dense pattern and the single pattern was also greatly reduced. Therefore, due to the etching reduction film, Fidelity CD Linearity and CD Bias could be improved.

(Example 4)

Referring to FIG. 2, the blank mask 102 according to the fourth embodiment of the inventive concept is a light shielding film 2, an antireflection film 4, and a hard mask film sequentially stacked on the transparent substrate 1. (5) may be included. Dry etching characteristics for forming a vertical pattern of the metal film 7 including the light blocking film 2 and the anti-reflection film 4 were evaluated.

A MoTaSi (15: 5: 80at%) target was used to deposit a MoTaSi light shielding film (2) to a thickness of 25 nm, and a MoTaSi (15: 5: 80at%) target was used to form a MoTaSiN antireflection film (4). The metal film 7 was formed by evaporating to a thickness of nm. The Crmask hard mask film 5 was deposited to a thickness of 10 nm using a Cr target. The optical density at 193 nm of the antireflection film 4 was 2.9, and the excellent reflectivity of the antireflection film 4 was 20.2%. The composition ratio of the light shielding film 2 and the antireflection film 4 was analyzed by ESCA. The composition ratio of MoTaSi (33: 18: 49at%) was measured for the light shielding film 2, and the composition ratio of MoTaSiN (9: 4: 60: 27at%) was measured for the antireflection film 4. The density of the membranes was analyzed using an XRR instrument. The density of the light shielding film 2 was 3.2 gram / cm ² , and the density of the antireflection film 4 was 3.6 gram / cm ² . On the hard mask film 5, FEP-171, a positive chemical amplified photoresist (CAR) (6), was coated at 150 nm and patterned by dry etching. The pattern profile of the light shielding film 2 of MoTaSi and the antireflection film 4 of MoTaSiN was observed through FE-SEM. The pattern profile angle was 89 ° without footing or under cut, and very good results were measured.

The sputtering process conditions were changed, and the light shielding film 2 of MoTaSiN was formed, and the anti-reflection film 4 of MoTaSiN was formed. The composition ratio of the light shielding film 2 was MoTaSiN (8: 5: 62: 27 at%), and the composition ratio of the antireflection film 4 was MoTaSiN (9: 4: 60: 27 at%). The light shielding film 2 had a density of 3.8 grams / cm ² and the antireflection film 4 had a thin film density of 3.6 grams / cm ² . As a result of observing the pattern profile of the light shielding film 2 and the anti-reflection film 4, a pattern profile having a trapezoidal shape with a pattern profile angle of 82 ° was observed. As a result, the etching rate was varied according to the thin film density, and the Si content decreased in the depth direction and the density decreased, so that the dry etching Radical Ion and the amount of reactants increased, thereby having an excellent pattern profile in the depth direction. On the other hand, if the Si content and density were the same in the depth direction, it could be difficult to form a vertical pattern due to the loading effect along with the continuous damage of Radical Ion to the thin film.

(Example 5)

Referring to FIG. 4, according to the fifth embodiment of the inventive concept, the blank mask 104 is a phase inversion film 8, a metal film 7, and a hard mask film 5 sequentially stacked on a transparent substrate. , A resist underlayer 9 composed of DBARC, and a photoresist 6.

On the substrate, a phase inversion film 8 based on MoSi was formed. The phase inversion film 8 may have a transmittance of 2 to 25% in an ArF or KrF exposure wavelength, and may be formed to a thickness of 60 to 100 nm. The phase inversion film 8 may include at least one selected from MoSiO, MoSiN, MoSiC, MoSiON, MoSiOC, MoSiCN, and MoSiCON. The phase inversion film 8 may be formed of a single layer film or a multilayer film. An interface may exist in the multilayer film. Even if no interface exists in the multilayer film, when the composition ratio change between the upper and lower films is 2 at% or more, the multilayer films may be distinguished. The deposition method of the thin films may be CVD or PVD. When the PVD method is used, a Long Throw Sputter (LTS) method in which the distance between the substrate and the target is 200 mm or more may be preferable. By using the LTS method, it is possible to reduce the uniformity and stress of the thin film. In the case where the phase inversion film 8 is based on MoSi, etching is possible by fluorine gas, so that it is possible to etch in chlorine series without etching in fluorine series to improve the selectivity with the synthetic quartz glass substrate. , Chromium or tantalum-based first etch stop layer a1 may be formed between the substrate 1 and the phase inversion layer 8. The first etch stop layer a1 may function as a transmission membrane and a phase inversion membrane.

On the phase inversion film 8, a metal film 7 based on MoSi was formed. The metal film 7 may be formed of a single layer film or a multilayer film. The metal film 7 is preferably formed of at least two or more multilayer films in order to function as a light shielding film and an antireflection film. In this case, in order for the metal film 7 to function as a light shielding film and an anti-reflection film, the metal film 7 has a distinct interface between the light shielding film and the anti-reflection film, or the composition ratio change in the vertical direction does not occur. It can be made into a multilayer film by setting it to 2 at% or more. The metal film 7 is preferably formed to a thickness of 60 nm or less. Particularly, when an interface between the light shielding film and the antireflection film exists, the light shielding film is preferably formed to a thickness of 40 nm or less and the antireflection film of 20 nm or less. The optical density at the exposure wavelength of the antireflection film is preferably 2.5 or more. The light blocking film and the anti-reflection film may include one selected from MoSi, MoSiC, MoSiN, MoSiO, MoSiCON, MoSiCN, MoSiON, and MoSiOC. The reflectance of the antireflection film 4 is preferably 20% or less at the exposure wavelength. By controlling the content ratio of silicon of the metal film 7 to 30 to 80 at%, stress of the metal film 7 can be minimized. The stress of the metal film can be minimized by using the LTS method. In the case where the phase shift film 8 and the metal film 7 are based on MoSi, etching may be performed by fluorine gas, so that the selectivity ratio between the phase shift film 8 and the metal film 7 may be increased. In order to improve the efficiency, a chromium or tantalum-based second etch stop layer a2 is formed between the phase shifting film 8 and the metal film 7 that is not etched in the fluorine series and is etchable in the chlorine series. can do. The second etch stop layer a2 may function as a transmission and a phase inversion layer.

A hard mask film 5 based on chromium or tantalum was formed on the metal film 7. It is preferable that the hard mask film 5 is not etched by a fluorine-based etching gas capable of etching the metal film 7. The hard mask film is preferably formed to a thickness of 20nm or less. In forming the hard mask film, a sputtering method, in particular, an LTS method is preferable. The hard mask film 5 is based on chromium or tantalum, and may be formed of one selected from oxidation, carbonization, nitriding, oxidative carbonation, oxynitride, carbonitride, and oxycarbonitride.

On the hard mask film 5, the resist lower film 9 containing a polymer as a main component was formed. The resist underlayer 9 can reduce substrate dependence that occurs when the chemically amplified resist 6 is patterned, fogging effect, forward scattering, and back scattering that occur during electron beam exposure. In addition, the resist underlayer can reduce the thickness of the resist. The resist underlayer 9 may be formed by spin coating, scanning, or spraying. The resist underlayer 9 may be formed to a thickness of 3 to 50 nm or less. The resist underlayer 9 may function as a reflectance control and may include a strong acid. Due to this strong acid of the resist underlayer 9, it is possible to reduce the substrate dependency of the chemically amplified resist. Due to the reflectance adjusting function of the resist underlayer 9, it is possible to improve CD characteristics through dose reduction and standing wave effect reduction when applying a laser exposure process instead of electron beam exposure. The resist underlayer 9 may be developed by a developer including TMAH without an exposure process. The resist underlayer 9 may be developed using ultrapure water (DI water). The soft bake temperature of the resist underlayer 9 is preferably higher than that of the resist. If the soft bake temperature of the resist underlayer is lower than that of the resist, the resist underlayer 9 may be affected during the soft bake process after the resist coating. On the other hand, when the soft bake temperature of the resist underlayer 9 is lower than that of the resist, the soft undercut of the resist underlayer 9 and the resist may be simultaneously performed during soft bake of the resist layer.

A chemically amplified resist 6 was coated on the resist underlayer 9. The resist 6 may be formed to a thickness of 100 nm or less due to the resist underlayer 9. Although the fifth embodiment described the blank mask to which the phase shift film 8 was applied, similar techniques can be applied to the binary blank mask and the binary hard mask blank mask without the phase shift film 8.

Next, a photomask was produced using the blank mask.

The resist was exposed using an electron beam exposure apparatus. Using the developer containing 2.38% TMAH, development was performed on the resist. In this case, the resist underlayer may be removed by a developing process without an additional exposure process. Using the following conventional photomask process, a photomask was produced.

As in the above embodiments, by controlling the silicon content of the metal film and the hard mask film, it is possible to form a thin film with low stress, excellent in pattern CD characteristics, registration characteristics, and excellent photomask characteristics. Can be prepared. In addition, by applying a resist underlayer that can be developed without an exposure process, the substrate dependency of the chemically amplified resist can be reduced, and the thickness of the resist can be reduced. Therefore, it is possible to minimize the loading effect characteristics, it is possible to manufacture a high-quality photomask that can be applied to less than 45nm and 32nm class excellent in pattern characteristics, CD characteristics and defect characteristics.

1: transparent substrate
2: shading film
4: antireflection film
5: hard mask
6: photoresist
7: metal film
8: phase inversion film
9: resist underlayer
101, 102, 103: blank mask
a1: first etch stop
a2: second etch stop

Claims (27)

A transparent substrate;
A metal film on the transparent substrate;
A hard mask film on the metal film; And
A resist on the hard mask layer,
The metal film is a blank mask, characterized in that the silicon content of 30 to 80 at%. The method of claim 1,
And a phase inversion film between the transparent substrate and the metal film. The method of claim 2,
And a etch stop layer between the transparent substrate and the phase shift layer or between the phase shift layer and the metal layer. The method according to any one of claims 1 to 3,
And the flatness of the metal film is changed within a range of 1 μm compared with the flatness of the transparent substrate before forming the metal film. The method according to any one of claims 1 to 3,
The metal film includes silicon and further includes at least one metal selected from molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and chromium (Cr), or a compound thereof. Blank mask characterized in that. The method according to any one of claims 1 to 3,
And the metal film comprises at least one film selected from the group consisting of a light shielding film, an etching reducing film, and an antireflection film. The method according to any one of claims 1 to 3,
An optical density in the exposure light of the said metal film is 2.5-3.5, The blank mask characterized by the above-mentioned. The method according to any one of claims 1 to 3,
And a selectivity ratio between the metal film and the hard mask film is 5 or more. The method according to any one of claims 1 to 3,
The content of silicon in the metal film increases from the surface thereof in the direction of the transparent substrate. The method according to any one of claims 1 to 3,
The blank mask, characterized in that the content of nitrogen contained in the metal film is 0 to 80 at%. The method according to any one of claims 1 to 3,
The blank mask of claim 1, wherein the absolute stress value of the metal film is 5000 MPa or less. The method according to any one of claims 1 to 3,
The blank mask, characterized in that the metal film comprises tantalum. The method according to any one of claims 1 to 3,
And a reflectance of said metal film is 25% or less at 193 nm. The method according to any one of claims 1 to 3,
The hard mask film is a blank mask, characterized in that it comprises a metal and one selected from oxides, carbides, nitrides, oxidized carbides, carbides, and oxynitrides of the metal. The method according to any one of claims 1 to 3,
The hard mask layer is not a dry etching in the fluorine-based gas, the blank mask, characterized in that the dry etching in the chlorine-based gas. The method according to any one of claims 1 to 3,
The hard mask film is a blank mask, characterized in that having a thickness of 3 to 30nm. The method according to any one of claims 1 to 3,
The blank mask, characterized in that the impurity ions including ammonia included in the hard mask film is 1ppmv or less. The method according to any one of claims 1 to 3,
And a resist under layer between the hard mask layer and the resist. 19. The method of claim 18,
The resist underlayer is a blank mask, characterized in that having a thickness of 3 ~ 50nm. 19. The method of claim 18,
And the resist underlayer is dissolved in an alkali developer. In the blank mask manufacturing method,
Preparing a transparent substrate;
Forming a metal film on the transparent substrate;
Forming a hard mask layer on the metal layer; And
Forming a resist on the hard mask layer;
The metal film is a blank mask manufacturing method, characterized in that the silicon content of 30 to 80 at%. The method of claim 21,
And forming a phase inversion film between the transparent substrate and the metal film. The method of claim 22,
And forming an etch stop layer between the transparent substrate and the phase shift film or between the phase shift film and the metal film. The method according to any one of claims 21 to 23, wherein
And the phase inversion film, the etch stop film, the metal film, and the hard mask film are formed by a long throw sputtering method. 25. The method of claim 24,
And a distance between the transparent substrate and the sputtering target is 200 mm or more. The method according to any one of claims 21 to 23, wherein
And forming a resist resist layer between the hard mask layer and the resist. A photomask manufactured by exposing and developing the blank mask according to any one of claims 1 to 3.

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