KR102109865B1 - Blankmask, Phase Shift Photomask and method for fabricating the same - Google Patents

Abstract

The phase reversing photomask according to the present invention includes a light transmitting part, a phase reversing part, and a light blocking part, wherein the phase reversing part is formed by etching a transparent substrate to a depth to reverse phase the exposure light, and the light blocking part is formed with a light shielding film pattern on the transparent substrate. , Hard film pattern is made by lamination.
The phase inversion photomask of the present invention can implement a high resolution pattern by etching a part of the transparent substrate to form a phase inversion pattern, and accurately and reproducibly etching the transparent substrate by determining the etching end point of the transparent substrate using a hard film. Endpoints can be secured.

Description

Blank mask, phase shift photomask and method for fabricating the same}

The present invention relates to a blank mask, a phase-reversing photomask and a method for manufacturing the same, and more specifically, a phase-reversing photomask including a phase-reversing portion formed by etching a transparent substrate and a method for manufacturing the same and a method for manufacturing the same. It relates to a blank mask (Blankmask).

A binary intensity mask and a half-tone type phase shift mask are mainly used as a photomask used in a semiconductor device manufacturing process and including information of a circuit original. Among them, the halftone phase reversal photomask is patterned by using a phase inversion film having a phase inversion amount of about 180 ° and a predetermined transmittance with respect to exposure light, for example, ArF at a wavelength of 193 nm and KrF exposure at a wavelength of 248 nm. Is formed. In general, a molybdenum silicide (MoSi) compound is used as the phase inversion film, and is designed to have a transmittance of about 6% and a phase inversion amount of 180 °.

On the other hand, the phase reversal photomask is a substrate type that forms a phase reversal pattern by etching a specific portion of a transparent substrate made of synthetic quartz glass, fluoride quartz glass, etc. to a predetermined depth to have a phase reversal amount of 180 ° in addition to a method using a phase reversal film. It can be formed into a square phase inversion photomask. The phase reversal pattern formed by etching the substrate has a high transmittance characteristic compared to a halftone phase reversal film, and thus, a phase reversal effect is large in the edge region of the pattern, and patterns are dense to form a high-precision pattern. It is easy to form the required line & space pattern.

The blank mask for manufacturing the substrate etched phase reversing photomask, unlike the halftone phase reversing blank mask, generally comprises a light shielding film and a resist film formed on a transparent substrate without a phase reversing film. The photomask using the blank mask is formed by forming a resist film pattern, and then etching the lower light-shielding film with an etch mask to form a light-shielding film pattern, and transparently exposing the light-shielding film pattern as an etch mask. The substrate portion is formed by etching.

However, the substrate etched phase-reversing photomask using the blank mask is difficult to realize a high resolution pattern due to difficulty in thinning the resist film provided in the blank mask, and accordingly, 65 nm or less, particularly 32 nm, 16 nm or less It is difficult to implement the transcription pattern.

In detail, the light-shielding film has a relatively thick thickness as it requires an optical density of about 2.5 or more in order to have the property of shielding the exposure light from a portion of a pattern or a blind area of a transparent substrate. In addition, when etching the transparent substrate, the light shielding film pattern needs a sufficient etching selectivity to the transparent substrate as it serves as an etching mask. To this end, in general, a light-shielding film is etched in a chlorine (Cl) -based gas, and a material not etched in a fluorine (F) -based gas is required, and a chromium (Cr) or chromium (Cr) compound is used as a representative material. The light-shielding film pattern containing chromium (Cr) has a low etching rate of 0.4 kPa / sec to 2 kPa / sec under general dry etching conditions. Therefore, when the thickness of the light-shielding film and the etch selectivity of the light-shielding film and the etch rate are compared, the resist film is difficult to be thinned, and it is difficult to realize a high resolution.

In addition, the substrate etching type phase-reversing photomask using the blank mask makes it difficult to determine the etching time of the transparent substrate when it is difficult to determine the end point of etching when etching the transparent substrate for forming the phase inversion.

In detail, the determination of the etching end point uses a difference in detection amount of a specific material, such as metal, silicon (Si), nitrogen (N), oxygen (O), and carbon (C), included in the thin film and the underlying thin film. Since the transparent substrate does not have a lower thin film, there is no difference in the amount of detection of a specific material that changes during etching, so it is difficult to securely end the etching. Accordingly, it is difficult to secure reproducibility of pattern characteristics such as a phase amount as the transparent substrate is etched to form a pattern depending on time during pattern production.

Accordingly, there is a need for a new blank mask and a substrate etched phase inversion photomask capable of realizing a high resolution pattern and accurately securing an etch end point when etching a transparent substrate.

The present invention provides a phase inversion photomask including a phase inversion portion formed by etching a substrate so that a high resolution pattern can be implemented and a blank mask for manufacturing the same.

The present invention provides a blank mask capable of accurately and reproducing the etching end point of a transparent substrate for forming a phase inversion, and a substrate etched phase inversion photomask manufactured using the same, and a method for manufacturing the same.

The substrate etched phase reversal photomask according to the present invention includes a light transmitting part, a phase reversing part, and a light blocking part, wherein the phase reversing part is made by etching a transparent substrate to a depth to phase-reverse exposure light, and the light blocking part is formed on a transparent substrate. A light-shielding film pattern and a hard film pattern are stacked on each other.

The phase inversion portion is formed by etching the transparent substrate to a depth of 90 nm to 250 nm, has a transmittance of 80% to 90%, and a phase inversion amount of 160 ° to 200 °.

The light shielding film pattern is etched on a chlorine (Cl) -based material, and the transparent substrate and hard film pattern are etched on a fluorine (F) -based material.

The present invention provides a substrate etched phase reversal photomask that forms a hard film having the same etching characteristics as a transparent substrate, and uses the hard film to determine the etching end point of a phase reversal pattern prepared by etching a part of the transparent substrate.

Accordingly, it is possible to provide a blank mask and a phase-reversing photomask capable of realizing a high-resolution pattern by etching a part of the transparent substrate of the present invention to form a phase-reversing pattern.

In addition, the present invention can provide a blank mask and a phase-reversing photomask capable of accurately and reproducibly securing the etching end point of the transparent substrate by determining the etching end point of the transparent substrate using a hard film.

1 is a cross-sectional view showing a blank mask according to an embodiment of the present invention.
Figure 2 is a cross-sectional view showing a blank mask according to another embodiment of the present invention.
Figure 3 is a cross-sectional view showing a phase inversion photomask according to an embodiment of the present invention.
4 is a cross-sectional view illustrating a method of manufacturing a phase inversion photomask according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail through examples of the present invention with reference to the drawings, but the examples are merely used for the purpose of illustrating and explaining the present invention, and the present invention described in the meaning limitation or the claims. It is not used to limit the scope of the. Therefore, those skilled in the art will appreciate that various modifications and other equivalent embodiments are possible from the embodiments. Therefore, the true technical protection scope of the present invention should be determined by the technical matters of the claims.

1 is a cross-sectional view showing a blank mask according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a blank mask according to another embodiment of the present invention.

Referring to FIG. 1, the blank mask 100 according to the present invention is a blank mask for forming a substrate etched phase inversion photomask including a phase inversion portion formed by etching a transparent substrate.

The blank mask 100 includes a light blocking film 104, a hard film 106 and a resist film 108 sequentially formed on the transparent substrate 102. Although not illustrated, on the light-shielding film 104, an anti-reflection film provided to adjust the reflectance of the exposure light may be further included.

The transparent substrate 102 is a portion on which a substrate etched phase inversion pattern is formed, and is made of quartz glass, synthetic quartz glass, fluorine-doped quartz glass, and the like, and it is important to control the transmittance and the amount of phase inversion required for the phase inversion pattern. To this end, it is preferable that the transparent substrate 102 has a transmittance of 90% or more with respect to exposure light of, for example, 193 nm and 248 nm wavelengths. In addition, as the control of the phase inversion amount is achieved through the control of the refractive index (n) of the transparent substrate 102, the transparent substrate 102 has a refractive index in the range of 1.3 to 2.0, preferably 1.4 to 1.8 with respect to the exposure wavelength.

The transparent substrate 102 may be applied to immersion lithography, multiple patterning lithography, and the like, for this purpose, the transparent substrate 102 is 2 nm / 6.35 mm or less, preferably 1 nm / It has a birefringence of 6.35 mm or less. However, the transparent substrate 102 may use a substrate having a birefringence of 5 nm / 6.35 mm or more when it is not necessary to control birefringence according to its use, such as dry lithography.

The flatness of the transparent substrate 102 acts as a factor for generating a spatial position difference between plasma and the transparent substrate when the substrate etched phase inversion film pattern is formed. For example, in the case of a transparent substrate showing a TIR (Total Indicated Reading) difference of 1,000 nm in the center and the outer circumference, respectively, when etching the transparent substrate, the distance and energy of the plasma reaching are generated, and finally the same pattern is etched. The time difference is generated to finally cause the same pattern size change. In addition, the flatness of the transparent substrate affects the depth of focus (DoF Margin) during wafer printing. Accordingly, when the flatness of the transparent substrate 102 is defined as a TIR value, it is preferable that the value is 1,000 nm or less, preferably 500 nm or 300 nm or less in the 142 mm 2 region.

The light-shielding film 104 includes molybdenum (Mo), nickel (Ni), zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn), chromium (Cr), aluminum (Al), and manganese (Mn) ), Cadmium (Cd), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), hafnium (Hf), tungsten (W) is selected from at least one material selected from, or comprises The material further comprises at least one light element of nitrogen (N), oxygen (O), or carbon (C).

The light shielding film 104 is processed in a pattern form exposing an etch target portion of the transparent substrate 102 when the transparent substrate 102 is etched together with the upper hard film 106 and serves as an etch mask of the transparent substrate 102 . Accordingly, the transparent substrate 102 etched by the fluorine (F) -based etching gas and the material having excellent etching selectivity (Etch Selectivity), preferably, chlorine (Cl) -based etching gas. In addition, the light shielding film 104 is preferably thinned to reduce the 3D effect (error due to width x height x height) caused by the thickness during wafer printing, and for this purpose, a high extinction coefficient with respect to the exposure wavelength It is preferably formed of a material having (k).

The light shielding film 104 is a material having a high extinction coefficient while having an etch selectivity with the transparent substrate 102, chromium (Cr), molybdenum chromium (MoCr) or CrN, CrO, CrC, CrON, CrCN, CrCO , CrCON, MoCrN, MoCrO, MoCrC, MoCrON, MoCrCN, MoCrCO, MoCrCON. Here, the molybdenum chromium (MoCr) and their compounds contain molybdenum (Mo), so as to increase the etching rate in chlorine (Cl) -based etching conditions, the critical dimension of the light-shielding film pattern during etching ( Critical Dimension) change can be minimized. The light shielding film 104 has a composition ratio of chromium (Cr) or molybdenum chromium (MoCr) of 50% to 100%, and light element of 0 to 50at%. Here, the content of oxygen (O) in the light element included in the light-shielding film 104 is preferably composed of 0 to 30at% or less for optical density and thickness thinning. This is because as the content of oxygen (O) increases, the transmittance increases and the thickness increases to secure a predetermined optical density.

The light-shielding film 104 is processed in the form of a pattern with the hard film 106 in the production of a substrate etched phase-reversing photomask, which is the final form, to form a light-shielding part in a blind area, etc. It has an optical density of 2.0 to 3.5 in order to secure light shielding properties. To this end, the light-shielding film 104 has an optical density of 1.5 to 3.0 with respect to exposure light. When the optical density of the light-shielding film 104 is 1.5 or less, the optical density required for the upper hard film 106 is increased, which causes a problem that the hard film 106 must be thickened, and finally, the thinning of the resist film becomes difficult. Therefore, it is difficult to implement high resolution. In addition, when the optical density of the light-shielding film 104 is 3.0 or more, the thickness of the light-shielding film 104 is increased, and when forming the light-shielding film pattern, there is a problem that CD linearity between patterns is deteriorated due to a loading effect. do.

The light-shielding film 104 has a reflectance of 70% or less with respect to the exposure wavelength. The reflectance of the light shielding film 104 may be reduced by increasing the content of light elements such as oxygen (O) or nitrogen (N), but when the content of the light elements increases, the optical density of the light shielding film 104 is relatively reduced. In order to satisfy the optical density, there is a problem that the thickness of the light-shielding film 104 is increased. Accordingly, since the reflectance of the final thin film can be controlled by controlling the properties of the hard film 106 formed on the light-shielding film 104, the surface reflectance of the light-shielding film 104 may be set to 70% or less.

The light shielding film 104 has a thickness of 20 nm to 60 nm, preferably a thickness of 30 nm to 50 nm, and is formed to a thickness having a ratio of 0.8 to 1.5 as compared to the hard film 106 provided thereon. desirable. The light-shielding film 104 may be formed in a single layer or multi-layer form, and may be formed in a single film or a continuous film in which the composition ratio is continuously or stepwisely changed in the depth direction.

The hard film 106 is processed in the form of a pattern to serve as an etch mask for etching the light-shielding film 104, and may also be used as a purpose of checking an etch end point when the transparent substrate 102 is etched. To this end, the hard film 106 has a light-shielding film 104 and a sufficient etching selectivity, and is etched in a fluorine (F) -based etching gas so as to have the same etching characteristics as the transparent substrate 102, and a chlorine (Cl) -based gas. It is formed of a material that is not etched.

The hard film 106 is molybdenum (Mo), silicon (Si), nickel (Ni), zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn), chromium (Cr), aluminum ( Al), manganese (Mn), cadmium (Cd), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), hafnium (Hf), tungsten (W) selected from one or more substances It is made of, or comprises at least one light element selected from nitrogen (N), oxygen (O), carbon (C) in the material.

The hard film 106 is, in particular, silicon (Si), molybdenum silicide (MoSi) or SiN, SiO, SiC, SiON, SiCN, SiCO, SiCON, MoSiN, MoSiCrO, MoSiC, MoSiON, MoSiCN, MoSiCO, MoSiCON and It is preferred to consist of one of these compounds. Here, when the hard film 106 is made of a molybdenum silicide (MoSi) compound, the composition ratio of the hard film 106 is Mo: Si: light element = 5at% to 20at%: 50at% to 70at%: 10at% to It has a content range of 45at%. The hard film 106 is preferably formed using a sputtering method, and the hard film 106 is a silicon (Si) single target or a two-component system composed of molybdenum silicide (MoSi) using a target. It can be formed and the composition ratio of the target is Mo: Si = 1at% to 30at%: 70at% to 99at%. When the content of molybdenum (Mo) in the composition ratio of the target is 30 at% or more, the hard film 106 is deteriorated in chemical resistance to the cleaning solution used in manufacturing the photomask. In addition, to form a hard film, a sputtering method can be produced using a co-sputtering method, wherein the sputtering target is molybdenum (Mo), silicon (Si), molybdenum silicide (MoSi). It can be manufactured using a composite target.

The hard film 106 may also be used for the purpose of confirming the etching end point of the transparent substrate 102 when forming the pattern of the transparent substrate 102. That is, the hard film 106 remaining in the form of a pattern in the main area (Main Area) during manufacturing of the photomask is indirectly removed as the transparent substrate (102) is removed during etching of the transparent substrate 102 for forming the phase inversion pattern ( The etching time of 102) can be confirmed. In detail, when the hard film 106 is formed of a molybdenum silicide (MoSi) compound, when the transparent substrate 102 is etched, the hard film 106 pattern is also etched, and at this time, the transparent substrate 106 and Different components, that is, changes in molybdenum (Mo) or light element components included in the hard film 106 pattern may be observed by EPD (End Point Detection) to indirectly confirm the etching end point of the transparent substrate.

The hard film 106 is preferably designed to have a slow etching speed in order to increase the accuracy of the etching end point identification for forming the phase inversion pattern of the transparent substrate 102. For example, the etching time for forming the phase inversion pattern of the transparent substrate 102 is 100 seconds, and when the etching of the hard film 106 pattern is completed in 20 seconds, the etching of the hard film 106 pattern After the time of 20 seconds, it is difficult to secure the etch end point data of the transparent substrate 102 for the remaining 80 seconds. Accordingly, in order to secure reliability for statistical probability, it is preferable that the etching rate of the hard film 106 pattern is slow, and the etching rate of the hard film 106 is 0.1 compared to the transparent substrate 102 in the transparent substrate 102 etching conditions. It is preferably controlled at times 1.5 times, preferably 0.3 times to 1.0 times. That is, the hard film 106 has an etch rate of 20 µs / sec or less, preferably 15 µs / sec, more preferably 10 µs / sec or less, with respect to the etching conditions of the transparent substrate 102.

The hard film 106 may be composed of a single layer or a multi-layered form, and may be formed of a single film having a same compositional ratio in a depth direction or a continuous film having a compositional ratio that is continuously or stepwise changed. The hard film 106 may be configured by laminating two or more layers of a molybdenum silicide (MoSi) compound with reference to FIG. 2 (a). This is a structure for designing such that the lower layer of the hard film 106 contains fewer light elements, and the upper layer reduces the surface reflectance by increasing the content of the light elements and lowers the total thickness. In addition, referring to (b) of FIG. 2, a hard film made of a chromium (Cr) compound may be formed on one or more hard films made of a molybdenum silicide (MoSi) compound. This is a structure for solving by forming an additional hard film of a chromium (Cr) compound on the upper portion of the hard film, which is difficult to thin due to the etching rate and thickness of the hard film made of a molybdenum silicide (MoSi) compound. In addition, the hard film 106 may be formed by alternately mixing a molybdenum silicide (MoSi) compound and a chromium (C) compound to form a manufacturing process and a fine pattern.

The thickness of the hard film 106 has a thickness of 10 nm to 60 nm, and preferably has a thickness of 20 nm to 50 nm.

As the resist film 108, a chemically amplified resist is preferably used, and has a thickness of 150 nm or less, preferably 100 nm or 80 nm or less.

3 is a cross-sectional view showing a phase inversion photomask according to an embodiment of the present invention.

Referring to FIG. 3, the phase inversion photomask 200 according to the present invention includes a light-transmitting part (A), a phase-reversing part (B) and a light-shielding part (C) including a phase inversion pattern formed by etching the transparent substrate 102. ).

The light-transmitting portion (A) is a region where the transparent substrate 102 is exposed, has a transmittance of 90% or more and a refractive index of 1.3 to 2.0 for exposure light such as 193nm and 248nm wavelengths, and has optical, physical, and chemical properties. It is the same area as the transparent substrate 102 of one blank mask.

The phase inversion unit B is formed by etching the transparent substrate 102 to a depth of 90 nm to 250 nm so as to phase-invert the exposure light passing through the light transmission unit A. At this time, the phase inversion unit B has a phase inversion amount of 160 ° to 200 ° with respect to the exposure wavelength, preferably 170 ° to 190 °, and a transmittance of 80% to 90%.

The light-shielding portion C is, for example, an area for shielding exposure light from the outer peripheral portion of the transparent substrate 102 of the substrate or a portion of the pattern. The light-shielding portion C is formed by laminating a light-shielding film pattern 104a and a hard film pattern 106a on a transparent substrate 102, has an optical density of 2.0 to 3.5 with respect to an exposure wavelength, and has a reflectance of 50% or less, Preferably, it has a reflectance of 40% or less.

4 is a cross-sectional view illustrating a method of manufacturing a phase inversion photomask according to an embodiment of the present invention.

Referring to FIG. 4, a light shielding film 104 and a hard film 106 are sequentially formed on the transparent substrate 102 and a first resist film 108 is applied to form a blank mask. (Fig. 4 (a))

The light-shielding film 104 is preferably Cr, CrN, CrO, CrC, CrON, CrCN, CrCO, CrCON, MoCr, MoCrN, MoCrO, MoCrC, MoCrON, MoCrCN, MoCrCO, MoCrCON that can be etched into a chlorine (Cl) -based material Form one of them. The hard film 106 has an etch selectivity with the light-shielding film 104, preferably Si, SiN, SiO, SiC, SiON, SiCN, SiCO, SiCON, MoSi, MoSiN, which can be etched in a fluorine (F) -based material. It is formed of one of MoSiCrO, MoSiC, MoSiON, MoSiCN, MoSiCO, and MoSiCON. Here, the light-shielding film 104 and the hard film 106 may be formed by various deposition methods such as a sputtering method, an atomic layer deposition method, a chemical vapor deposition method, and is preferably formed by a sputtering method.

An exposure and development process is performed on the resist film to form a first resist film pattern 108a exposing the etching target region of the transparent substrate 102 used as a phase inversion, and etching including a fluorine (F) -based material The hard film portion 106a is formed by etching the hard film portion exposed with gas. (Fig. 4 (b))

The first resist film pattern is removed, and a portion of the transparent substrate 102 is etched by etching the light-shielding film portion exposed with an etch gas containing a chlorine (Cl) -based material using the hard film pattern 106a as an etch mask. A light shielding film pattern 104a to be exposed is formed. (Fig. 4 (c))

A second resist film pattern that forms a second resist film on the exposed portion of the transparent substrate 102 and the hard film pattern 106a, and patterns the second resist film to expose an etch target portion of the transparent substrate 102 ( 112a). Then, the exposed hard film pattern 106a and the transparent substrate 102 are simultaneously etched with a fluorine (F) -based etching material to form a phase inversion portion T etched at a predetermined depth on the transparent substrate 102. . (Fig. 4 (d))

At this time, the etch end point of the transparent substrate 102 is determined based on the etch end speed of the hard film 106a, and the phase inversion part T has a phase inversion amount of about 180 ° and a predetermined 80% to 90% transmittance. It is formed to a depth having.

The second resist film pattern provided on the hard film pattern 106a is removed, and the light-shielding film pattern exposed by the etching of the hard film pattern is removed, so that the transparent portion 102 is a light-transmitting portion (A) and a transparent substrate The manufacturing of the substrate etched phase-reversing photomask having the light-reflecting portion C formed by laminating the phase-reversing portion B formed by etching 102 and the light-shielding film pattern 104a and the hard film pattern 106a is completed.

As described above, the present invention forms a hard film having the same etching characteristics as a transparent substrate, and uses a hard film to determine the etching end point of a phase inversion pattern prepared by etching a part of the transparent substrate. A mask was prepared.

Accordingly, a high-resolution pattern can be implemented by etching a part of the transparent substrate of the present invention to form a phase inversion pattern, and an etch end point of the transparent substrate can be secured with accuracy and reproducibility.

(Example)

Example  1-Preparation and evaluation of blank mask

Referring to FIG. 1, a transparent substrate 102 made of synthetic quartz glass was prepared to manufacture a blank mask used as a basis for manufacturing a substrate etched phase inversion photomask according to the present invention. The transparent substrate 102 has a size of 6 inches x 6 inches x 0.25 inches, the refractive index is 1.54 at 193 nm, the transmittance is 90.2%, the flatness is controlled to 300 nm in the 142 mm ² region, and the birefringence is 2 nm / 6.35 mm or less. .

Then, using a chromium (Cr) target having a purity of 4N, and injected with Ar: N ₂ = 5sccm: 2sccm as a process gas, the sputtering process for 240 seconds with a process power of 0.7kW to proceed to the transparent substrate 102 ), A light-shielding film 104 made of CrN having a thickness of 31 nm was formed. As a result of measuring the optical density and reflectance of the light-shielding film 104 at 193 nm wavelength using n & k Analyzer equipment, the optical density was 1.84 and the reflectance was 55.97%.

Then, using a molybdenum silicide (MoSi, composition ratio Mo: Si = 20at%: 80at%) target on the light-shielding film 104, and injected as Ar: N ₂ = 9.3sccm: 7.2sccm as a process gas, 0.6 The sputtering process was performed for 145 seconds at a process power of kW to form a hard film 106 made of MoSiN having a thickness of 25 nm. The optical density and reflectance of the structure in which the light-shielding film 104 and the hard film 106 were stacked were measured at a wavelength of 193 nm using n & k Analyzer equipment. As a result, the optical density was 3.0 and the reflectance was 35.94%, After manufacturing the final photomask, all the light-shielding properties in the outer peripheral part were secured.

Subsequently, the chemically amplified resist film 108 was formed on the hard film 106 to a thickness of 100 nm by a spin coating method to complete the production of the final blank mask 100.

As a result of analyzing the composition ratio of the blank mask 100 using AES equipment, the light-shielding film 104 showed Cr: N = 78 at%: 22 at%, and the hard film 106 was Mo: Si: N = 14.5 at% : 66.0at%: 19.5at%.

Example  2-Manufacturing and evaluation of a blank mask having a multi-layered hard film Ⅰ

In Example 2, a blank mask was prepared by forming two layers of hard films on a light-shielding film.

Referring to FIG. 2 (a), a chromium (Cr) target is used on the same transparent substrate 102 as in Example 1 described above, and Ar is injected at 8 sccm as a process gas, 60 seconds at a process power of 0.7 kW. During the sputtering process, a light shielding film 104 made of 15 nm thick Cr was formed on the transparent substrate 102.

Then, using a molybdenum silicide (MoSi, composition ratio Mo: Si = 20at%: 80at%) target on the light-shielding film 104, and injected with Ar: N ₂ = 6sccm: 4sccm as a process gas, 0.6kW A sputtering process was performed for 320 seconds at a process power to form a single layer hard film 106 made of 25 nm thick MoSiN.

Thereafter, the same target was used on the hard film 106 of the first layer, and Ar: N ₂ = 7.3 sccm: 6.4 sccm was injected as a process gas, and the sputtering process was performed for 200 seconds at a process power of 0.7 kW. A two-layer hard film 112 made of nm-thick MoSiN was formed.

The optical density and reflectance of the structure in which the light-shielding film 104 and the hard films 106 and 112 of the first and second layers were laminated were measured at a wavelength of 193 nm using an n & k analyzer, and the optical density was 3.05. , Reflectance was 33.2%, and thus all the light-shielding properties in the outer peripheral portion were secured after the final photomask was manufactured.

Subsequently, the chemically amplified resist film 108 was formed on the two-layer hard film 112 to a thickness of 100 nm by a spin coating method to complete the production of the final blank mask 100.

Example  3-Preparation and evaluation of a blank mask having a multi-layered hard film Ⅱ

In Example 3, a blank mask was prepared by forming three layers of hard films on a light-shielding film.

Referring to FIG. 2 (a), the chromium (Cr) target is used on the light-shielding film 104 made of Cr and the hard films 106 and 112 of the first and second layers made of MoSiN in the same manner as in Example 2 described above. Then, Ar: N ₂ = 5 sccm: 3 sccm was injected as a process gas, and a sputtering process was performed for 20 seconds with a process power of 0.77 kW to form a three-layer hard film 114 made of 4 nm thick CrN.

The optical density and reflectance of the structure in which the light-shielding film 104 and the hard films 106, 112, and 114 of the first to third layers were stacked were measured at a wavelength of 193 nm using n & k Analyzer equipment, and the optical density was 3.06. The reflectance was 30.4%, and thus all the light-shielding properties in the outer peripheral portion were secured after the final photomask was prepared.

Thereafter, the chemically amplified resist film 108 was thinly formed to a thickness of 80 nm by a spin coating method on the three-layer hard film 114 to complete the production of the final blank mask 100.

Example  4-Substrate Etched  Phase inversion Photomask  Manufacturing and evaluation Ⅰ

Referring to FIG. 4, a method of manufacturing a substrate etched phase inversion photomask using the blank mask prepared in Example 1 described above will be described.

After the light-blocking film 104, the hard film 106, and the first resist film 108 formed on the transparent substrate 100 were subjected to an exposure process using an EBM-8000 exposure facility, PEB (Post Exposure Bake) was performed. ) Was performed at a temperature of 112 ° C. for 10 minutes. Thereafter, a development process was performed to form a first resist film pattern 108a exposing a portion of the hard film 106.

The hard film pattern 106a was formed by dry etching the portion of the hard film 106 exposed with the etching mask as the first resist film pattern 108a with a fluorine (F) -based etching gas. At this time, as a result of confirming the etching time of the hard film 106 by EPD, the etch rate was 1.92 어 / sec, indicating 130 seconds, and over etching 50% was applied to complete the formation of the hard film pattern 106a. Subsequently, the thickness of the remaining first resist film pattern 108a was measured using AFM equipment to show 62 nm, confirming that there was no problem as an etching mask.

After removing the first resist film pattern 108a, the hard film pattern 106a is dry etched with a chlorine (Cl) -based gas to form a light-shielding film pattern 104a by exposing the lower light-shielding film 104 portion exposed as an etching mask. . At this time, the etching time of the light-shielding film 104 was 390 seconds, and the etching rate was 0.79 Å / sec, which was 2.43 times slower than the hard film 106 at the top.

The second resist film pattern 110 is formed on the exposed transparent substrate 102 portion and the hard film pattern 106a, and the exposure and development process is performed so that the second resist film pattern remains only on the outer circumferential region where the light blocking portion is formed. (110a) was formed.

A phase inversion portion formed by etching the transparent substrate 102 to a depth of 185 nm by performing an etching process using a fluorine (F) -based etching gas on the transparent substrate portion 102 exposed by the second resist film pattern 110a ( B) was formed. At this time, the hard film pattern provided on the transparent substrate 102 was simultaneously etched and removed. In addition, the hard film pattern 104a was etched in 35 seconds under the etching conditions of the transparent substrate, and the part of the transparent substrate 102 was etched in 132 seconds, so that the hard film pattern 104a was 7.14 Å / sec. , The transparent substrate 102 exhibited an etching rate of 14.02 Å / sec, so that the hard film exhibited an etching rate of 0.51 times slower than that of the transparent substrate.

The resist film pattern of the light blocking portion C and the light blocking film remaining on the transparent substrate 102 were removed to complete the production of the final photomask. At this time, as a result of measuring the transmittance of the phase inversion portion (B) made by etching the transparent substrate, it showed 85.9%, showing somewhat reduced results compared to the portion of the transparent substrate that was not etched, but it was possible to secure high transmittance and phase The amount of inversion was 183 °, so it was confirmed that there was no problem in using it as a phase inversion mask.

Example  5-Substrate Etched  Phase inversion Photomask  Manufacturing and evaluation Ⅱ

In the fifth embodiment, a method of manufacturing a substrate etched phase inversion photomask using the blank mask prepared in Example 3 will be described. In detail, after performing an exposure process using an EBM-8000 exposure facility on a blank mask on which a light-shielding film, a multilayer hard film, and a resist film are formed on a transparent substrate, PEB (Post Exposure Bake) is performed at a temperature of 112 ° C. for 10 minutes. Did. Thereafter, a development process was performed to form a resist film pattern exposing a portion of the hard film.

The resist film pattern was dry etched with a chlorine (F) -based etching gas on the hard film portion of the three layers exposed as an etch mask to form a hard film pattern composed of chromium (Cr). At this time, the etching rate of the Cr hard film was 0.85 Å / sec.

Thereafter, the resist film pattern was removed, and the MoSiN hard films of the lower and second layers were etched with a fluorine (F) -based gas using a chromium (Cr) hard film pattern to form a hard film pattern.

Then, the light-shielding film was etched with a chlorine (C) -based gas using a MoSiN hard film as an etch mask to form a light-shielding film pattern. At this time, the three-layer Cr hard film pattern was removed together.

A resist film was formed on the exposed transparent substrate portion and the hard film, and an exposure and development process was performed to form a resist film pattern so that it remained only on the outer circumferential region where the light blocking portion was formed.

An etching process using a fluorine (F) -based etching gas was performed on the exposed transparent substrate portion to form a phase inversion portion made by etching the transparent substrate to a depth of 185 nm. At this time, the hard film patterns of the first and second layers provided on the transparent substrate were etched together and removed. The resist film pattern of the light-shielding portion and the light-shielding film remaining on the transparent substrate were removed to complete the production of the final phase-reverse photomask. Here, as a result of measuring the transmittance of the phase inversion portion made by etching the transparent substrate, it showed 86.2%, showing a somewhat reduced result compared to the portion of the transparent substrate that was not etched. As shown in the figure, it was confirmed that there was no problem in using it as a phase inversion mask.

Comparative example  -Blank mask without hard film and Photomask  Manufacturing and evaluation

In this comparative example, a blank mask and a photomask without a hard film were prepared and evaluated, and compared with the examples of the present invention.

In the blank mask of the comparative example, a transparent substrate having the same properties as in Example 1 was prepared, a chromium (Cr) target having a purity of 4N was used, and Ar: N ₂ = 5sccm: 5sccm was injected as a process gas, 0.7 A sputtering process was performed for 420 seconds at a process power of kW to form a light shielding film made of CrN having a thickness of 60 nm. As a result of measuring the optical density and reflectance of the light-shielding film at a wavelength of 193 nm using n & k Analyzer equipment, the optical density was 2.9, and the reflectance was 45.54%. Showed relatively low and high reflectance results.

Thereafter, a resist film pattern was formed on the light shielding film, and the light shielding film was etched with a chlorine (Cl) -based gas to form a light shielding film pattern. At this time, the light-shielding film exhibited an etching rate of 0.93 kPa / sec, and the final etching time was 645 seconds. Accordingly, in the etching process of the light-shielding film, all of the 80 nm-thick resist film patterns are removed, and the part of the light-shielding film under the resist film pattern that should not be exposed is exposed, resulting in damage to the thickness due to damage, resulting in substrate etching. It was confirmed that it was difficult to apply to the production of a phase inversion photomask.

Example  6- target By composition Etch  Speed and chemical resistance evaluation results

In Example 6, the etching rate and chemical resistance evaluation of the hard film according to the composition of each MoSi target were performed for SC-1 and sulfuric acid.

Target composition

pellicle
Etch rate
(Substrate etching conditions) Chemical resistance (thickness change) SC-1
(40 ℃, 20min) Sulfuric acid
(80 ℃, 20min) Si
(100at%) SiN 16.2Å / sec 1.2Å 0.3Å MoSi
(5at: 95at%) MoSiN 15.3Å / sec 2.1Å 0.3Å MoSi
(10at: 90at%) MoSiN 14.8Å / sec 2.6Å 0.4Å MoSi
(20at: 80at%) MoSiN 12.2Å / sec 3.5Å 1.1Å MoSi
(30at: 70at%) MoSiN 8.5Å / sec 8.9Å 3.1Å MoSi
(50at: 50at%) MoSiN 5.2Å / sec 20.2Å 12.5Å

Referring to Table 1, it can be seen that as the content of molybdenum (Mo) included in the target for forming the hard film increases, the etching rate of the hard film decreases. However, as a result of evaluating the chemical resistance, it can be confirmed that the chemical resistance characteristics deteriorated as the molybdenum (Mo) increased. In particular, it is judged that it is difficult to use as the molybdenum (Mo) component is rapidly deteriorated when the target is 30 at% or more.

In the above, the present invention has been described using the most preferred embodiment, but the technical scope of the present invention is not limited to the range described in the above embodiment. It will be readily appreciated by those skilled in the art that it is possible to add various modifications or improvements to the above-described embodiments. It is clear from the description of the claims that the form to which such a change or improvement was added can also be included in the technical scope of the present invention.

100: blank mask
104: hard film
106: light shielding film
108: resist film
110: second resist film
112: 2-layer hard film
114: 3-layer hard film

Claims (20)

A phase inversion photomask comprising a light transmitting portion, a phase inverting portion and a light blocking portion,
The phase inversion portion is made by etching the transparent substrate to a depth to phase invert the exposure light,
The light-shielding portion is formed by laminating a light-shielding film pattern and a hard film pattern on a transparent substrate,
The hard film pattern has a property of being etched by the same etch material as the transparent substrate, and a phase inversion photomask having an etch rate of 0.1 to 1.5 times that of the transparent substrate in order to confirm the etch end point of the transparent substrate.
According to claim 1,
The phase inversion portion is a phase inversion photomask, characterized in that formed by etching the transparent substrate to a depth of 90nm to 250nm.
According to claim 1,
The phase inversion portion has a transmittance of 80% to 90%, a phase inversion photomask, characterized in that it has a phase inversion amount of 160 ° to 200 °.
According to claim 1,
The light-shielding portion has a phase inversion photomask, characterized in that it has a reflectance of 50% or less.
According to claim 1,
The light-shielding film pattern and the hard film pattern are made of a material having a mutual etch selectivity with respect to one etching material, respectively, molybdenum (Mo), nickel (Ni), zirconium (Zr), niobium (Nb), palladium ( Pd), zinc (Zn), chromium (Cr), aluminum (Al), manganese (Mn), cadmium (Cd), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), hafnium ( Hf), made of at least one material selected from tungsten (W), or characterized in that the material further comprises at least one light element of nitrogen (N), oxygen (O), carbon (C) Phase-reversing photomask.
According to claim 1,
The light-shielding film pattern is etched in a chlorine (Cl) -based material, the transparent substrate and the hard film pattern is a phase inversion photomask, characterized in that etched in a fluorine (F) -based material.
According to claim 1,
The light-shielding film pattern is a phase reversal photomask comprising Cr, CrN, CrO, CrC, CrON, CrCN, CrCO, CrCON, MoCr, MoCrN, MoCrO, MoCrC, MoCrON, MoCrCN, MoCrCO, or MoCrCON.
The method of claim 7,
The light-shielding film pattern is a phase inversion photomask, characterized in that chromium (Cr) or molybdenum chromium (MoCr) has a composition ratio of 50% to 100%, and light element of 50at% or less.
According to claim 1,
The light-shielding film pattern is a phase inversion photomask, characterized in that having a thickness of 20nm to 60nm.
According to claim 1,
The light-shielding film pattern has a phase inversion photomask, characterized in that it has a thickness of 0.8 to 1.5 ratio compared to the hard film pattern.
According to claim 1,
The light-shielding film pattern has a phase inversion photomask, characterized in that it has an optical density of 1.5 to 3.0 with respect to the exposure light.
According to claim 1,
The hard film pattern is Si, SiN, SiO, SiC, SiON, SiCN, SiCO, SiCON, MoSi, MoSiN, MoSiCrO, MoSiC, MoSiON, MoSiCN, MoSiCO, a phase inversion photomask, characterized in that made of one of MoSiCON.
The method of claim 12,
The hard film pattern is composed of a molybdenum silicide compound, Mo: Si: light element = 5at% ~ 20at%: 50at% ~ 70at%: 10at% ~ 45at% phase reversal photomask characterized in that it has a composition ratio .
delete According to claim 1,
The hard film pattern is a phase inversion photomask, characterized in that it has an etching rate of less than 20Å / sec with respect to the fluorine (F) -based etching material.
According to claim 1,
The hard film is a phase inversion photomask, characterized in that having a thickness of 10nm to 60nm.
According to claim 1,
The hard film is a phase inversion photomask, characterized in that it consists of a multi-layer film of two or more layers etched in the same etch material.
The method of claim 12,
It is provided on the hard film pattern, Cr, CrN, CrO, CrC, CrON, CrCN, CrCO, phase reversal photomask further comprising a hard film pattern made of one of CrCON.
delete A blank mask for manufacturing the phase inversion photomask of any one of claims 1 to 13 and 15 to 18,
Transparent substrates;
A light shielding film provided on the transparent substrate;
Includes; a hard film provided on the light-shielding film,
The hard film pattern has a property of being etched by the same etch material as the transparent substrate, and a blank mask having an etch rate of 0.1 to 1.5 times that of the transparent substrate in order to confirm the etch end point of the transparent substrate.

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